V 

 
 THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 LOS ANGELES
 
 E L E M E N T S 
 
 PHYSBOfeOGY: 
 
 BY 
 
 A. RICHERAND, 
 
 PROFESSOR OF THE FACULTY OF MEDICINE OF PARIS, MEMBER OF THE ACADEMIES 
 OF VIENNA, PETERSBURG!!, MADRID, TURIN, &C. 
 
 from ti)c 
 
 BY G. J. M. DE LYS, M.D. 
 FIFTH EDITION. 
 
 CAREFULLY REVISED AFTER THE NINTH AND LATEST FRENCH 
 EDITION, AND SUPPLIED WITH 
 
 NOTES AND A COPIOUS APPENDIX, 
 
 JAMES COPLAND, M.D. 
 
 LBCTURKR ON PHYSIOLOGY, PRINCIPLES OF PATHOLOGY, AND THE NATURE AND TREATMENT 
 
 or DISEASES; CONSULTING PHYSICIAN TO QUEEN CHARLOTTE'S- LYING-IN 
 HOSPITAL; SENIOR PHYSICIAN TO THB ROYAL INFIRMARY 
 
 FOR CHILDREN ; MEMBER OF THE ROYAL COLLEGE 
 Of PHYSICIANS, LONDON, &C. 
 
 SECOND EDITION. 
 
 LONDON: 
 
 PRINTED FOR LONGMAN, REES, ORME, BROWN, AXD GREEN; BALDWIN 
 
 AND CRADOCK; HURST, CHANCE, AND co.; WHITTAKER, TREACHEII, 
 
 AND CO. ; JAMES DUNCAN ; SIMPKIN AND MARSHALL ; 
 
 s. HIGHI.EY; BURGESS AKD HILL; 
 
 AND J. WILSON. 
 
 1829.
 
 LONDON: 
 
 MOTHS, TOOK'S COURT, CHASCMY LAP
 
 ar/ 
 
 TO 
 
 HALLIDAY LIDDERDALE, M.D. 
 
 MEMBER OF THE ROYAL COLLEGE OF PHYSICIANS, LONDON, &C. 
 
 THIS REVISED EDITION, 
 THE NOTES, 
 
 AND 
 
 THE APPENDIX, 
 
 AS AN ACKNOWLEDGMENT 
 
 OF HIS PRIVATE AND PUBLIC WORTH, 
 
 OF HIS PROFESSIONAL AND SCIENTIFIC ATTAINMENTS, 
 
 AS WELL AS 
 
 A SMALL TESTIMONY OF GRATEFUL RECOLLECTIONS 
 OF HIS VARIOUS ACTS OF KINDNESS, 
 
 regpictfuUg 
 
 BY THE EDITOR. 
 
 939580
 
 PREFACE 
 
 PRESENT EDITION OF THE TRANSLATION, 
 
 AND OF THE 
 
 EDITOR'S NOTES AND APPENDIX. 
 
 THE EDITOR has endeavoured to revise the present 
 edition, as carefully as was in his power, after the latest 
 French edition. He has been anxious to get rid, 
 as far as he could, of the foreign idiom and obscurities 
 which he found in the translation ; and he has intro- 
 duced whatever new matter could conveniently be 
 added to the body of the Work. He has made con- 
 siderable additions to his Annotations, as well those 
 which accompany the author's text, as those which 
 form the Appendix. In order that the Work should 
 not be too bulky, the Editor has enlarged the page 
 much beyond the size of that of former editions. He 
 has generally refrained from adducing in his Notes 
 old or obsolete opinions, in order that he should have 
 sufficient space wherein to discuss modern doctrines, 
 and to state his own views. 
 
 The former edition of the Editor's Notes contained 
 opinions which he is not aware to have seen previously 
 published, and which, indeed, were opposed to those
 
 VI PREFACE. 
 
 generally believed in, even by the latest observers and 
 writers. Many of these opinions have since received 
 confirmation in the researches and writings of various 
 continental physiologists. The reader "will find them 
 discussed as fully as the limits of the Notes could 
 admit. The Editor, however, has still hopes of being 
 able to bestow upon them these illustrations, and to 
 give them that degree of developement, which they 
 still require, and to consider them in their relations 
 to the nature and treatment of diseases. This, how- 
 ever, cannot be satisfactorily performed on an occa- 
 sion like the present, but must be made the object 
 of a separate undertaking. 
 
 1, Bulstrode Street, Welbeck-Slreet, 
 Cavendish Square, 
 9th May, 1829.
 
 / s 
 
 ':, 
 
 {' 
 
 \ 
 
 0VE Dl T O R * S P R E \A C E 
 
 ' x ' ' ' ' v'O ' 
 
 'TO THE 
 
 ^ -; ' ^ ' 
 
 '' .i /^IRST EDITJQj^ OF iflS 
 
 NOTES AND APPENDIX. 
 
 THE AUTHOR of the Notes to this Edition of the 
 English translation of M. RICHERAND'S Elements of 
 Physiology has endeavoured to give a full, but concise 
 account of the opinions recently offered on some of 
 the topics embraced by the Work. He has not, how- 
 ever, confined himself to the bare detail of the views 
 of others he has frequently stated his own opinions. 
 In doing this he has been as concise as the nature of 
 his subjects would allow him. 
 
 The office of an Annotator has not permitted him 
 to bestow that copiousness of illustration on his own 
 views which many may consider them to require : 
 this will be attended to on another occasion. In the 
 meanwhile, in whatever manner his opinions may 
 be received, he will not shrink from a fair discussion
 
 Vlll ED1TOU S PREFACE. 
 
 of them ; he will always respect, and endeavour to 
 profit by, a candid examination of them ; and he will 
 espouse them no longer than he is perfectly convinced 
 that they are founded on a correct interpretation of 
 the operations of the animal economy. 
 
 1, Bulstrode Street, 
 5th June, 1824.
 
 TRANSLATOR'S PREFACE. 
 
 IT is a singular fact, that in this country, which has given 
 birth to some of the most important discoveries in physiology, 
 there should not have been prod uced a single elementary or sys- 
 tematic work on the subject. Those only have written on 
 physiology who had discoveries to make known, and to these 
 they have, in general, confined their publications. The con- 
 sequence has been, that there are, in the English language, 
 many works in different departments and on single points of 
 physiological inquiry, and that our miscellaneous scientific 
 publications, the transactions of societies, and periodical works 
 of inferior importance, are stored with much valuable matter, 
 both of new facts and original speculation : but till this is 
 brought together, from the various quarters where it lies 
 scattered, into some more comprehensive form, it is not truly 
 within the reach of those to whom it would furnish an import- 
 ant part of their professional knowledge ; nor, indeed, until it 
 possesses some systematic work, embracing all that is known of 
 the subject, can the country itself exhibit its claims on the 
 scientific world for the service it has done to physiology. 
 
 Such a work, however, which should fairly represent the 
 state of physiology as it at present exists in Europe, was per- 
 haps scarcely to be expected ; for though it should contain no 
 discovery, it would be, if rightly executed, a work of great 
 magnitude, and requiring qualities which do not often go 
 together. The industry requisite for collecting materials from 
 so great a number of writers in different languages the judg- 
 ment and profound knowledge of the subject necessary in the 
 selection the acuteness required in arriving at the truth, 
 where the variety of opinions is so great, are qualities rare in 
 themselves, and still more rarely combined. The genius which 
 inspired to the great English physiologists the important dis- 
 coveries that have immortalised such names as Harvey, Hunter, 
 Monro, seems as if it had unfitted them for the more laborious 
 and ungracious task of compiling and arranging the discoveries
 
 X TRANSLATOR S PREFACE. 
 
 of others. How seldom may we expect to meet with such a 
 combination of genius and indefatigable industry as was seen 
 in the great Haller ; yet without a certain degree, at least, of 
 the same qualities, no writer can pretend to tread in his 
 footsteps. 
 
 It is probable, too, that the great work itself of Haller, at 
 the same time that it best illustrates the importance of the 
 undertaking and its difficulty, must be considered as having 
 long remained, by its excellence, an impediment to the pro- 
 duction of a similar succeeding work. Haller was fifty years 
 engaged in the most ardent study of physiology : his work, 
 besides all that he himself, the great leader in physiological 
 discovery, and also the most extensive discoverer, wished to 
 give to the world, of his own, contained all that was known 
 on the subject at the time it appeared. As it was written, too, 
 in the Latin language, it found a ready access to every school 
 of medicine, and was every where received by the profession 
 as, at once, the most authentic record of the /acts of physiology, 
 and the most luminous exposition of the principles of the 
 science. We cannot wonder, therefore, that while Haller had 
 exclusive possession of physiology, no other writer should have 
 attempted any work on the same subject, even for some time 
 after his death, while the additions to the mass of knowledge 
 were not sufficient to effect any important change in the 
 science. Now, however, enough has been added to change, in 
 many important respects, the face of the science, and to 
 demand systematic arrangement. Of late years, accordingly, 
 several works, composed with this view, have appeared on 
 the continent ; amongst which may be mentioned those of 
 Blumenbach, Bichat, Dr. Dumas of Montpellier, and M. 
 Richerand. 
 
 This priority in the systematic arrangement of our know- 
 ledge does not, however, at all imply that the progress of 
 physiology abroad has been more rapid than in this country. 
 It would be difficult to say where it is furthest advanced. If 
 a comparative view were to, be given of the science, as it exists 
 in Britain and on the continent, it would rather appear that 
 a different excellence fyas been attained on either side, .accom- 
 panied, of course, by different defects. In Britain, it might 
 be shewn that it is founded on sounder principles, and more 
 freed from the doctrines of the older physiologists, who were 
 rather given to invent, explanations of the phenomena of nature, 
 than to seek them in the laborious investigation of her opera- 
 tions. The physiologists of this country have studied with 
 intelligent, patient, and zealous research, the facts of phy- 
 siology ; they have distinguished themselves in this, as in the 
 other sciences, by an anxiety for exactness of knowledge. The
 
 TRANSLATOR'S PREFACE. xi 
 
 continental physiologists are fond of theory ; an adherence even 
 to the old theories characterises, very remarkably, the works 
 of the most modern foreign writers on medicine and surgery, 
 influencing even the practice of the profession in a very un- 
 favourable manner. But this spirit of theorising this anxiety 
 to extend individual facts into general principles, is as essential 
 to the progress of the science, as that zeal in the acquisition 
 of knowledge which prepares its materials. They carry this 
 spirit to excess ; but which is the most dangerous error to 
 science I will not pretend to determine that impatient 
 activity of mind, which, in its eagerness to theorise, will not 
 wait for fulness of knowledge, or that over distrust of theory, 
 which is not judicious caution, but timidity, or indolence, 
 or a real want of intellectual disposition to high philosophic 
 speculation. 
 
 The same comparison would shew a superiority in another 
 respect, in the physiologists of this country that they have 
 made further progress in pathological physiology. They have 
 applied themselves more to the study of nature under disease, 
 investigating both the disordered functions and the altered 
 structure of disease, and seeking to understand, and success- 
 fully availing themselves of, the powers of renovation and sub- 
 stitution, which are provided in the body for injuries of its 
 original organisation ; drawing, in short, from physiology a 
 light to the intelligence and practice of their art. The con- 
 tinental physiologists, on the other hand, have rather endea- 
 voured to bring light from other sciences to physiology. And 
 though here, too, their speculations have borne the same cha- 
 racter of precipitancy, there is no doubt their labours in this 
 department have been attended with considerable success; 
 and that while many of their applications and analogies have 
 passed away from 'the public mind almost as soon as they 
 were before it, much still remains that will be permanently 
 received as convincing illustration, from the sciences of in- 
 animate matter, of the processes of living nature.* 
 
 This different direction of the spirit of inquiry in different 
 countries, has probably been favourable to the rapid progress 
 of the science. Yet something has been lost to it by what 
 
 * It was in the contemplation of the translator, when he undertook this Work, 
 to have engaged, in some degree, in the comparison of which he has here spoken. 
 He intended to annex to it, in the form of an Appendix, a comparative view of 
 the opinions entertained in this country, and on the continent, on many interesting 
 points of physiology, which might serve the purpose of notes to the work, and be 
 some compensation to himself for the unsatisfactory labour of translation. It is 
 not till towards the close of the work, of which the translation and printing have 
 been unavoidably going on together, that he finds the time to which it was of im- 
 portance to the publisher to fix the publication, does not allow him to complete his 
 original intention.
 
 TRANSLATOR S PREFACE. 
 
 was not at all a necessary consequence of such a division of 
 labour, a. disregard of each other's pursuits and acquisitions. 
 Both here and abroad, we have every day discoveries brought 
 forward by writers, who are very legitimate discoverers, if real 
 ignorance 'of the previous knowledge of others entitle to the 
 name of originality. These imagined discoveries are prosecuted 
 with infinite zeal, and much good labour is lost to physiology, 
 in bringing facts to light that were well established in the 
 world before these authors were born. The Work now given to 
 the public can scarcely be offered as a remedy, as far as this 
 country is concerned, of the inconvenience ; for though it con- 
 tains a good summary of the knowledge and opinions of modern 
 physiologists, and does very fairly represent the present state 
 of the science on the continent, those who really desire to 
 possess themselves of what has been dope there will be aware 
 that they must undertake a much more laborious study, and 
 seek for the information they want, in most cases, at its original 
 sources. 
 
 This work, I believe, will be chiefly useful for the purpose 
 which was designed by the author, as an elementary book 
 for students. There is not, as I have said, one English element- 
 ary work on physiology; scarcely, indeed, on any part of our 
 professional knowledge. Whether it be that there is more 
 literary industry abroad, or that in the institutions for medical 
 education the public teachers are more separated from their 
 profession and devoted to the duties of instruction, it is certain 
 that in all departments of professional study they have dis- 
 tinguished themselves by the number and ability of their ele- 
 mentary works ; and in the science of physiology in parti- 
 cular, the English student who is desirous of engaging in it 
 will find himself at a loss for a guide, among the names that 
 have done honour to science at home, and compelled to seek 
 assistance in his pursuit from the writers of other countries. 
 
 An eloquent modern writer on anatomy complains that 
 too much attention is now bestowed on physiology, while 
 anatomy, on which sound physiology ought to rest, is 
 neglected. That anatomy ought to be made the ground- work 
 of all medical education, and that a thorough knowledge of 
 the structure of the human body ought to precede the study 
 of its functions, is indisputable; nor does the truth of this 
 opinion appear to be denied by any one in the present day : 
 and, accordingly, anatomy appears every where to be culti- 
 vated with ardour. In all places of medical education, the 
 number, both of teachers and students of anatomy, is in- 
 creased in much greater proportion than in any other depart- 
 ment of professional study. Dissection is now considered as 
 essential in the study of anatomy, and almost a new system
 
 TRANSLATOR'S PREFACE. XHI 
 
 of minute surgical anatomy has been instituted within a few 
 years. 
 
 There appears no reason, then, to complain that anatomy 
 has been neglected ; and if there were, it is not to physiology 
 the neglect could be imputed. The number of teachers of 
 anatomy, of medicine, and surgery, is more than four times 
 what it was half a century ago, but the number of teachers of 
 physiology remains nearly the same. Physiology is either 
 not taught at all, or forms a very insignificant part of a course 
 of anatomy. A professed course of physiology is, at present, 
 scarcely delivered any where out of the metropolis ; and even 
 there, only one lecturer is found to undertake such a course. 
 It is not true that in this country physiology absorbs too much 
 of the attention of students, and interferes with more important 
 studies ; it may rather be said to be too little attended to as a 
 branch of instruction : it is omitted until the engagements of 
 the profession leave no time for the prosecution of a laborious 
 study ; and it is, in the end, neglected altogether. If physiology, 
 if the knowledge of the healthy functions, be necessary to him 
 whose object in life is to understand the functions of the body 
 in disease, it is of consequence that physiology be more gene- 
 rally studied, that it be considered more as an essential object 
 of professional education, that our public teachers bestow on 
 it a greater share of their attention. 
 
 Let it not be objected to the public teaching of physiology, 
 that it may be learnt from books as well as from lectures. 
 The objection, if valid, would be equally applicable to most of 
 the other departments of professional study, the objects of 
 which do not admit of ocular demonstration ; yet no one ob- 
 jects to lectures on medicine, materia medica, &c. This study, 
 however, does require the frequent illustration of anatomy, of 
 drawings, of preparations, and even of experiments, which are 
 within the reach of few. The study of physiology in books 
 alone is dry and uninteresting to the young student, and will 
 never be prosecuted with ardour. It seems too much to rely 
 on the capacity for solitary study of young minds ; and, at all 
 events, the study of physiology, as of any other science, by a 
 number of young men under one teacher, will be more ardent, 
 from the frequency of discussion and experiment, than if car- 
 ried on by each separately. To study physiology with any 
 effect, the student should have access to public lectures on the 
 subject, in which he will see experiments and preparations, 
 besides such dissections in human and comparative anatomy 
 as may be required to illustrate the doctrines he hears : ne will 
 then be qualified to turn his private studies to account, and 
 will pursue them with interest. 
 
 Haller, who may justly be termed the father of physiology,
 
 XIV TRANSLATOR S PREFACE. 
 
 was himself a distinguished lecturer, and his mode of instruc- 
 tion may be safely followed. He was a pupil of the celebrated 
 Boerhaave, and when he himself became a public teacher, the 
 doctrines of that great man had possession of the schools : 
 these doctrines he tells us, in his preface to the Primae Linese 
 Physiologies, he continued to teach for twenty-four years, using 
 the work of his illustrious teacher, as he calls him, for his text- 
 book ; but finding that since the* time of Boerhaave many im- 
 provements and discoveries had been made in the science, he 
 thought it right to substitute an elementary work of his own, 
 containing the more recent discoveries; and this work he 
 addressed to his class. Physiology is improving, and new dis- 
 coveries are daily added to the store of knowledge already in 
 our possession. If all these scattered materials were brought 
 together, a work might be grounded on them of the highest 
 value to the public teacher who has to communicate instruction, 
 and to the student who has to meditate, in private and at 
 leisure, on the knowledge that has been rapidly communicated 
 to him in a public lecture. This object is, as was already 
 observed, in part fulfilled by the work of M. Richerand, though 
 incompletely as far as respects this country, as it does not 
 embrace sufficiently the state of the Science in Britain. 
 
 Birmingham, Sept. 14, 1812.
 
 THE 
 
 AUTHOR'S ADVERTISEMENT 
 
 THE FIFTH EDITION. 
 
 IN preparing for the press this Fifth Edition of his Work, 
 the Author has carefully revised and corrected it, in all its 
 parts, so as to render it more worthy of the success it has 
 already obtained. The additions which have been made will 
 be found not to consist of idle discourses or frivolous hypo- 
 theses. The ground-work and the order are the same, the 
 Author has merely added to the mass of facts, supported, by 
 additional proofs, the opinions which he had advanced, and 
 developed those parts of his subject, which, from being ex- 
 plained in too concise a manner, might be involved in some 
 degree of obscurity. 
 
 Among the variety of opinions which criticism, oftener 
 unjust than enlightened, has pronounced, in judging this Work, 
 there is one which requires to be refuted, because it proceeds 
 from an erroneous idea of what an elementary work should be. 
 The Author, it has been said, ought to have contented himself 
 with giving a view of the present state of the science, without 
 any additions of his own ; and he should have abstained from 
 inserting new opinions, which, until they had received the 
 sanction of the learned world, ought not to have been in- 
 troduced into an elementary work. This objection may be 
 answered by considering that modern physiology being, in 
 some measure, a new and regenerated science, there will be 
 found, in treating of it to its full extent, many deficiencies to be 
 filled up, and many doctrines evidently erroneous for which 
 truths are to be substituted, which it is of importance to 
 discover. Lavoisier, in his Elements of Chemistry, set forth, 
 in a methodical order, truths which he himself had discovered : 
 he introduced original ideas, not such as owe an appearance of 
 originality to minute explanation of what is already known, or 
 to a general want of erudition, too prevalent in the present day.
 
 XVI ADVERTISEMENT. 
 
 One of his most illustrious colleagues, in describing the state of 
 the science, has likewise given a history of his discoveries and 
 labours, and men of the soundest judgment ascribe the as- 
 tonishing progress of chemistry, in a great measure, to the 
 favourable circumstance of our possessing elementary works 
 written by the most distinguished chemists. 
 
 The present work has been translated in England, in Spain, 
 in Italy, in Germany, and men of merit have not disdained the 
 task. Since the publication of the Fourth Edition of this Work, 
 Professor Sprengell has published his Institutes of Physiology.* 
 The date of that new work, and the well-deserved reputation of 
 its author, entitle it to be considered as a faithful account of the 
 state of physiological science in Germany. In that work the 
 reader will be astonished to find it stated that every thing in 
 the human body is governed by polar influence and by the 
 laws of antagonism; that man is in a state of positive electricity ; 
 that his body is formed chiefly of oxygen; while the female 
 body is in a state of negative electricity, with a superabundant 
 quantity of hydrogen in the composition of its solids and fluids. 
 Thus, by the premature application of a few facts borrowed 
 from the physico-chemical sciences, the learned of Germany 
 have thrown back physiology into the uncertainty of con- 
 jectures and hypotheses. 
 
 On the other hand, Gall, by his anatomical discoveries on 
 the organisation of the brain and nerves ; and a few other 
 physiologists, by their experiments on living animals, have 
 been usefully employed in advancing the progress of phy- 
 siology. The Author has been anxious to increase the value 
 of this new edition by adding to it the result of their ob- 
 servations. 
 
 Institutiones Physiologic*. Amstelod. 1809, 2 vol. 8vo.
 
 PREFACE 
 
 THE FIRST EDITION.* 
 
 THESE Elements of Physiology, which contain an abstract 
 of the doctrines I have taught for several years past in my 
 public lectures, are written on the model of the small work on 
 Physiology of the great and immortal Haller, (Prima Line<E 
 Physiologic). I am far, however, from presuming to say that 
 I have equalled the merit of a work which, as is remarked by 
 a man of the highest ability, f when it appeared, gave a new 
 aspect to the science, and commanded universal approbation. 
 If these new Elements of Physiology deserve any preference 
 over that work, the honour is not due to the Author, but to 
 the times in which he writes, enriched by the progress of the 
 physical sciences, with a multitude of data and results that 
 may be said to have rendered Physiology altogether a new 
 science. 
 
 It will be easily perceived that the plan 1 have adopted 
 differs essentially from that followed by several respectable 
 physicians ; and that the treatises on Physiology, most lately 
 published, resemble the present only in their title. In com- 
 bining a great number of facts, in adding to those already 
 known the result of my own- observation and experience, and 
 in connecting them, by a method that should unite accuracy 
 and simplicity, I have had it in view to keep a due measure 
 between those elementary works whose conciseness approaches 
 to obscurity and dryness, and those in which the authors, 
 omitting no detail, and exhausting in a manner their subject, 
 
 * Published in 1801. 
 
 j- " When Haller published his Primes Linece Physiologies, which he valued 
 most of all his works, a considerable sensation was excited in the schools. In works 
 on the same subject, it was customary to find long dissertations, almost always void 
 of proof, extraordinary opinions, or brilliant fictions. It was matter of wonder, 
 that in Haller's work there should be found only numerous facts, precise details, 
 and- direct inferences." VtcQ-D'AzvR.
 
 XVlll PREFACE. 
 
 seem to have written only for those who have leisure or 
 inclination for the profoundest study. 
 
 Should any conceive that the present undertaking is above 
 the, capacity of my age, 1 will say, even at the risk of a para- 
 dox, that young men are perhaps fittest to compose elementary 
 works, because the difficulties they have encountered in the 
 study are yet fresh in their memory, as well as the steps which 
 they have taken to overcome them ; and further, because their 
 recent experience points out to them the defects and advan- 
 tages of the different methods of other instructors :* so that 
 he who in the shortest space of time has carried to the great- 
 est extent his own acquisition of sound knowledge, will, in 
 some respects, be the best guide to his successors in the dif- 
 ficult and perplexing paths of elementary study. 
 
 In the composition of the work I have borne constantly in 
 mind the necessity of sacrificing elegance to clearness, which I 
 know to be the most important merit of an elementary treatise. 
 Further, I have throughout followed, I believe, the same 
 arrangement in the succession of the subjects, and applied to 
 the science of living man the principle of the association of 
 ideas ; a principle so well developed by Condillac, in his 
 Treatise on the Art of Writing, and to which that philosopher 
 has shewn that all the rules of the art are to be referred. Not- 
 withstanding the rigorous law to which I have subjected 
 myself, I have, after the example of the ancients, and, among 
 the moderns, of Bordeu, and of several other physicians and 
 physiologists of equal celebrity, thought myself justified in 
 employing, when I felt it necessary, metaphorical expres- 
 sions ; because, as has been justly observed by a writer who 
 has been, in our own times, an honour to her sex, if conciseness 
 do not consist in the art of reducing the number of words, 
 still less does it consist in depriving language of imagery. 
 The conciseness which is to be envied is that of Tacitus, at 
 once eloquent and energetic; and, far from any fear that 
 imagery should injure that justly -admired compression of 
 style, figurative expressions are, indeed, those which comprise 
 in fewest words the greatest sum of ideas.f 
 
 Those who insist on meeting, in a work on Physiology, 
 with a romance instead of the history of the animal economy, 
 will, no doubt, reproach me with having entirely neglected a 
 great number of hypotheses, ingenious or absurd, on the uses 
 
 * " The best order in which truth can be set forth, is that in which it might 
 naturally have been discovered ; for the surest method of instructing others, is to lead 
 them along the path which we ourselves have followed in our own instruction. In 
 this way we shall seem not so much to lay before them our own knowledge, as to 
 set themselves on the search and discovery of unknown truths." CONDILLAC. 
 
 -|- De la Literature, considtrfe dans ses rapports avec les Institutions Sociales, 
 par Madame de Stael Holstein, tome ii.
 
 PREFACE. XIX 
 
 of organs ; with having omitted, for example, while speaking 
 of the spleen, to mention the opinion which considers that 
 viscus as the seat of mirth and laughter; with having said 
 nothing of the opinion of those authors who conceive it to main- 
 tain, by counterpoising the liver, the equilibrium of the two 
 hypochondria; nor even of the doctrine of the ancients, who 
 ascribed to it the excretion of the atrabilis, &c- To recall 
 such errors for the sake of elaborate refutation, would be 
 wasting much precious time in idle discussions, and possess- 
 ing, as Bacon calls it, the art of making one question bring 
 forth a thousand, by answers more and more unsatisfactory. 
 I have chosen to forego all such vain parade, from a clear 
 conviction, that works of merit are as often distinguished by 
 some things that are not to be found in them, as by those they 
 do contain. 
 
 Several authors, in treating of the science of man, have 
 indulged themselves in frequent excursion into the vast field of 
 accessory sciences, and have, without necessity, incorporated 
 . in their works whole chapters on air, on sound, on light, and 
 other subjects which belong to the department of natural phi- 
 losophy and chemistry. Haller himself is not entirely free 
 from blame, for having discredited Physiology by this borrowed 
 display. I have introduced only such general ideas of the 
 subject as were absolutely necessary to render my own intel- 
 ligible, and were, indeed, too closely connected with it to 
 admit of separation. 
 
 One of the principal faults of writers on Physiology is, that 
 they are apt to fall into frequent repetitions ; and that fault is 
 often owing to the difficulty of settling satisfactorily the limits 
 of actions which are mutually connected and dependent among 
 themselves, and running into each other, like those that are 
 carried on in the animal economy. 
 
 " In composition, one should avoid prolixity, because it is 
 fatiguing to the mind ; digressions, because they divert the 
 attention ; frequent divisions and subdivisions, because they 
 are perplexing ; and repetitions, because they are oppressive. 
 What has been once said, and in its proper place, is clearer 
 than if several times repeated elsewhere."* In following these 
 precepts, and they cannot be too much attended to, one may, 
 it is true, incur the risk of being thought superficial by super- 
 ficial readers, who form their opinion of a work from the 
 perusal of a single chapter ; but a most ample compensation 
 will be found in the opinion of those who choose to be tho- 
 roughly acquainted with a work before they pass on it their 
 final judgment. 
 
 * Condillac, Essai sur VOriyinc des Connoissances Humaines, seconde partie, 
 sec.-ii. chap. iv.
 
 XX PREFACE. 
 
 After having stated in what spirit this work has been writ- 
 ten, I may say something of the motives which have led to its 
 publication. I would mention, in the first place, the advantage 
 which, it might be expected, would accrue to the science, and 
 to those who are engaged in its pursuit; and, in the next place, 
 the satisfaction which study has in store for him who bestows 
 on it the time he can snatch from the laborious practice of our 
 art. In his short intervals of leisure from public instruction 
 and from professional duty, left to himself and his own thoughts, 
 in the silence of study, and in the calm of meditation, he looks 
 down with an eye of pity on those who drag on, through the 
 lowest intrigues, a despicable existence, and finds his consola- 
 tions against the endless vexations that are prepared for him 
 by supercilious ignorance and jealous mediocrity.
 
 ANALYTICAL TABLE 
 
 CONTENTS. 
 
 ^ PACK 
 
 DEDICATION iii 
 
 PREFACE by the Editor v 
 
 .. to the First Edition of his Notes and Appendix... vii 
 
 - by the Translator ix 
 
 by the Author xv 
 
 to the First Edition . . xvii 
 
 PRELIMINARY DISCOURSE Physiology the science of life. Definition of 
 life, 1. 
 
 SECT. I. Of natural beings They are inorganic or organised the former are 
 
 simple or complex ; the latter always complex, and distinguished into vegetable and 
 animal. Reciprocal dependence of all these beings, 2. 
 
 SECT. II. Of the elements of bodies The elements of bodies. Their number 
 forty-four ; but it is probable that several appear to us simple, from the imperfection 
 of our means of analysis, 2. 
 
 SECT. III. Differences between organised and inorganised bodies Differences 
 between organised and inorganised bodies, 3. Homogeneousness of the latter; 
 complex nature of the former ; necessary co-existence of fluids and solids in all 
 organised and living beings ; simplicity of inanimate matter ; complex nature and 
 tendency to decomposition of organised bodies, 4. 
 
 SECT. IV. Differences between animals and plants. Differences between 
 animals and plants, 7- The great distance between the mineral and vegetable 
 kingdom ; a considerable approximation, on the contrary, between animals and 
 plants, 8. Of all the characters which .mark the differences between these sub- 
 stances, the most remarkable is the presence of an alimentary tube, which is found in 
 every animal from man down to the polypus, 8. In all animals, nutrition is ptr- 
 formed by two surfaces, especially by the internal ; the alimentary canal is the 
 most essential part of their body, 9. It retains life longer than any other part ; 
 experiments disproving Haller's opinion on this subject, 9. 
 
 SECT. V. Of life Consists of a number of phenomena proportioned t%the com- 
 plication of the organisation, 10. Simple in plants, in which its actions are limited 
 to nutrition and reproduction, 10. Of life in the polypus ; this animal consist- 
 ing merely of a sentient and contractile pulp, shaped into an alimentary cavity, 11. 
 Of life in" worms, 12. In crustaceous animals, its apparatus more perfect, 13. Of 
 life In cold-blooded animals, 13. In warm-blooded animals and in man, 14. 
 C
 
 XXll CONTEXTS. 
 
 General view of the human organisation, 14. Of the elementary fibre, I?- De- 
 pendence of life on the oxidation of the blood in the lungs, and on the distribution 
 of this vivified blood throughout the organs, 18. 
 
 SECT. VI. Of the vital properties, sensibility and contractility Those two 
 properties not possessed in a'n equal degree by all living bodies, 19. Modifications 
 of sensibility in different organs, 22. Observations on the contractility of serous 
 membranes, 24. Caloricity, 25. Laws of sensibility, 2?. Influence of sleep, of 
 climate, of the seasons, of the age, &c. on the vital properties, 29-33. 
 
 SECT. VII. Of sympathies Of sympathy, 32 Diseases arising from asso- 
 ciation ; synergies, 34. 
 
 SECT. VIII. Of habit Of habit, 36. It uniformly lessens physical sensi- 
 bility, 37. A curious fact, shewing the effects of habit, 37- Habit impairs the 
 sensitive power, but improves the judgment, 39. 
 
 SECT. IX. Of the vital principle The vital principle not a being existing by 
 itself, and independently of the actions by which it manifests itself, 41. A per- 
 petual struggle in organised bodies between the laws of the vital principle and those 
 of universal nature, 42. The vital principle resists the laws of chemistry, of 
 physics, and mechanics, 42. There take place, however, in the animal economy, 
 chemical, physical, and mechanical phenomena, but they are always modified by the' 
 vital principle, 42. Influence of the stature on the energy of the vital powers and 
 even on longevity, 43. Vis medicatrix naturae, 46. Theory of inflammation, 46. 
 Analogy between the turgescence of an inflamed part and of one in a state of 
 erection, as the penis, &c. 48. Indirectly tonic influence of cold, 48. 
 
 SECT. X. Of the system of the great sympathetic nerves These nerves are to 
 be considered as connecting the organs of the functions of assimilation, as the 
 cerebral nerves unite that of the external functions, 49. They are the only nerves 
 found in several animals without vertebrae, 50. They arise from all the ver- 
 tebral nerves, from which they receive filaments, as well as from the fifth and sixth 
 cerebral pairs, 50. Ganglions of the sympathetic nerves ; the semi-lunar ganglion 
 the principal, 51. The great sympathetic render the internal organs independent 
 of the will, 52. Pathological relations of the great sympathetic, 54. 
 
 SECT. XI. Of the relations of physiology to several other sciences The rela- 
 tion of physiology to physics, chemistry, and mechanics, 55. Connexion of 
 physiology with human and comparative anatomy, 57-60. Its connexion with 
 medicine, 62. 
 
 SECT. XII. Classification of the vital functions The best division of the vital 
 
 functions is that which was first pointed out by Aristotle, adopted by Buffon, and 
 completely developed by Grimaud, 62. Modifications of which this division is sus- 
 ceptible ; preservative functions of the individual or of the species, 64. These two 
 great divisions further divided into two orders, 64. Other classifications of the 
 functions, 64. Why man is subject to more diseases than other animals, 67. 
 
 Of the arrangement of this work, 70. The voice is a natural connexion be- 
 tween the preservative functions of the individual and those of the species, ?0. The 
 history of the ages and temperaments, and of the varieties of the human species ; 
 the account of death and putrefaction forms a separate appendix, 71- Table of the 
 classification of the functions, as adopted in thi p work, 73.
 
 CONTENTS. 
 
 FIRST CLASS. 
 
 FUNCTIONS SUBSERVIENT TO THE PRESERVATION 
 OF THE INDIVIDUAL. 
 
 ORDER FIRST. 
 
 FUNCTIONS OF ASSIMILATION. 
 
 CHAPTER I. 
 
 On digestion. 
 
 Definition of this function, 75- General considerations on the digestive appa- 
 ratus, 75. Connexion between the nature of the aliment and the extent of the 
 digestive tube, 76. Of aliments, 77- The nutrient principle obtained from the 
 aliment, by our organs, is always the same, 78. Of the nature of the alimentary 
 principle, 78. Differences of regimen, according to the climate, 79- Of hunger, 
 82. Of thirst, 84. Mastication, 86. Action of the lips, of the cheeks, of the 
 tongue, of the teeth, of the jaws, 87-89. The salivary solution, 89. Deglutition, 
 its mechanism, 91. Deglutition of fluids and of gaseous substances, 93. Of the 
 abdomen, 94. Of digestion in the stomach, 95. Different systems of digestion ; 
 of concoction, fermentation, 96. Of putrefaction, 98. Of trituration ; of digestion 
 in graiiivorous fowls, 99. Of maceration, 100. Phenomena of rumination, 101. 
 Of the gastric juices, 102. Its source, its quantity, and solvent qualities, 102, 103. 
 Digestion chiefly consists in the solution of the aliment in this fluid, 104. Singular 
 case of a fistula of the stomach, 108. Chemical constitution of chyme, 109. Action 
 of the stomach, 110. Functions of the pylorus, 111. Of nervous influence in 
 digestion, 113. Of vomiting, 114. Digestion in the duodenum, 116. Analysis of 
 chyme taken from the duodenum, 117- Of the bile and its secretory organs, 117. 
 Circulation of the blood in the liver, 118. Uses of the spleen, 120. Of the pan- 
 creas and pancreatic juice, 1 22. Separation of the alimentary matter into two sub- 
 stances, the one chylous, the other excrementitious, 123. Of the action in the small 
 intestines, 123. The uses of their curvatures and valvulae conniventes; of the 
 peristaltic motion, 124. Of digestion hi the great intestines, 126. Uses of the 
 appendicula vermiformis of the cuecum, 127- Of the evacuation of the faeces, 127- 
 Intestinal gases, 128. 
 
 Of the secretion and excretion of the urine, 129. Of the calibre of the renal 
 arteries, structure of the kidneys, 130. Action of the kidneys and ureters, 132. 
 Accumulation of the urine within the bladder, 134. In what manner it is expelled, 
 136. Physical qualities of the urine, 138. Chemical analysis of this fluid, urea, 
 139. Its retention produces urinous fever, 140. Experiments on the effects at- 
 tending retention of urine by tying the ureters in living animals, 140. Urea, 141. 
 Occasional changes in the urine, 142. Urinary calculi, 144. Why most frequent 
 in cold and damp climates, 144. ^ ^ 
 
 CHAPTER II. 
 
 Of absorption. 
 
 Absorption takes place in every part of the body, both on its surface and in its 
 internal parts, 145. Absorption more or less active in different circumstances, 148. 
 Its activity is very slight on the external surface .except where the skin is thin and 
 the epidermis moist, 147-
 
 XX iv CONTEXTS. 
 
 Absorbing mouths, 149. Their mode of action in absorption, 149. Of the 
 lymphatics, 150. Their innumerable anastomoses, from the union of which there is 
 formed a mesh-work enveloping the whole body, 150. Pathological inferences, 151. 
 
 Of the conglobate glands, 152. Their action, 153. Circulation of the lymph, 
 153. Morbid states of the absorbent system, 155. Observations on cancer, 156. 
 
 Of the thoracic duct, 157- Of the physical and chemical properties of the 
 lymph, 158. 
 
 CHAPTER III. 
 
 Of ihe circulation. 
 
 Definition and general idea of this function, 160. Of the structure and action 
 of the heart, 160 ; uses of the pericardium, 161. Connexion between the bulk of 
 the heart and strength and courage, 161. Singular case of communication be- 
 tween the two ventricles, 163. Structure of the heart, 164. Action of the heart 
 in circulation, 166. Decurtation and pulsation of the heart every time the ven- 
 tricles contract, 169. The quantity of blood which these cavities send out along the 
 arteries, 169. 
 
 Action of the arteries, 170; their arrangement and anastomoses, 170. Of the 
 structure of the arteries, the force and contractility of their different coats, 171. 
 Dilatation of the arteries, 175. Of the pulse and its varieties, 177- Velocity of the 
 circulation along the arteries, 178. 
 
 Of the capillary vessels, 179. Those which convey a colourless fluid, 180. Of 
 the manner in which the blood flows along these vessels, 181. Terminations of 
 the arterial system, 182. Functions and conditions of the capillaries, 183. 
 
 Of the action of the veins, 184. Proportion of the arterial to the venous 
 blood ; difference of arrangement and structure between the arteries and veins; 185. 
 Of the use of the valves of the veins, 186. Of the use of the vena azygos, 187. 
 Gradual increase of velocity iTi the venous circulation, 188. Reflux of the blood in 
 the great venous trunks, 188. Theory of the circulation, 189. Of the systemic 
 circulation, 189. Partial circulations in the midst of the general circulation, 190. 
 Of the pulmonary circulation, 190. Of the two divisions, venous and arterial, of 
 the circle of circulation, 191. Organs situated on the two points of intersection of 
 this great circle, 191. 
 
 CHAPTER IV. 
 
 Of respiration. 
 
 Of all the changes which the blood undergoes, in penetrating through the 
 organs placed in the course of the circulation, the most remarkable are those it 
 receives from respiration, 191. Differences of arterial and venous blood, 191. Of 
 the atmosphere, 192. Mechanism by which respiration is performed, K)6. Motions 
 of the ribs, 197. Action of the respiratory muscles, 198. Difficult respiration, 200. 
 Of inspiration, 200. Of expiration, 200. State of the lungs during inspiration, 200. 
 Of the pulmonary vessels, 201. Structure of the lungs, 201. Use of the bronchial 
 arteries, 202. Pulmonary inflammations, 202. Absorbents of the lungs, 203. 
 Changes on the air and on the blood by respiration, 204. Vitality of the lungs, 208. 
 Respiration of certain animals, 209. Division or ligature of the eighth pair of 
 nerves, 210. 
 
 Of animal heat, 211. Animal heat is^Upendent of the media in which 
 animated beings live, 211. The heat of the VJ^al body thirty-two degrees, 213. 
 The lungs not the only parts in which caloric if disengaged, 213. Caloric evolved, 
 to a certain degree, in all organs receiving arterial blood, 214. Cutaneous evapora- 
 tion the most powerful means of lowering the temperature, 216. It does not ex- 
 plain, however, why the animal temperature remains the same, in a medium hotter 
 than the body ; case of a man said to be incombustible, 217' Causes enabling the 
 body to resist cold, 218. Effects of cold, 218. Source of animal heat, 219. 
 
 Phenomena of the circulation of the blood through the lungs, 220. Pulmonary 
 exhalation, 221. Of asphyxia, from drowning and from strangulation, 222. From
 
 CONTENTS. XXV 
 
 noxious gases and from intoxication, 223. From obstruction of the glottis ; of the 
 asphyxia of new-born children, 224. 
 
 Of several phenomena of respiration, as sighing, yawning, sneezing, coughing, 
 hiccup, and laughter, 225. Cutaneous perspiration, 227- Its connexion with the 
 other functions, 228. Its quantity, 229. Of the sweat, 229. Of the formation of 
 carbonic acid gas on the surface of the skin, 230. Of the uses of the cutaneous 
 perspiration, 230. 
 
 CHAPTER V. 
 
 Of the secretions. 
 
 Classification of the animal fluids, 231. Chemical classification of the fluids by 
 Fourcroy, the best, 232. Other classifications, 232. Of the blood, 232. The con- 
 stituent parts of the blood, 233. Of the ultimate elements of the blood^ 235. Of 
 the changes in the blood, 236. Of the transfusion of blood, 238. 
 
 Of the secretions, 240. Of arterial exhalation, 240. Of foliicular secretion, 241. 
 Secretions of conglomerate glands, 242. Accidental secretions, 243. Of nervous 
 influence on secretion, 244. Of the secretion of synovia, &c. 246. State of the 
 circulation during secretion, 247. Influence of the brain and of the mind on the 
 secretions, 248, Quantity of fluids secreted, 249. Of other secreting parts, 250. 
 Of the secretion of adeps, 250. Circumstances which increase or lessen its secretion, 
 251. Of the use of the fat, 252. Of the secretion of the marrow, 254. Insensi- 
 bility of the medullary membrane, 255. 
 
 CHAPTER VI. 
 
 Of nutrition. 
 
 Nutrition is the complement of assimilation, 255. Period of the complete reno- 
 vation of the body, 256. Process of nutrition, 256; from arterial blood only, 257. 
 Substances capable of yielding nutrition, 257- Difference of vegetable and animal 
 substances, 257. New products, 258. Changes produced in alimentary substances, 
 260. Of the emunctories, 261. General view of the functions of nutrition, 262. 
 Man enjoys sensation in its greatest perfection, 263. 
 
 SECOND ORDER. 
 
 FUNCTIONS WHICH TEND TO THE PRESERVATION OF THE INDI- 
 VIDUAL, BY ESTABLISHING HIS RELATIONS WITH THE BEINGS 
 THAT SURROUND HIM. 
 
 CHAPTER VII. 
 
 Of sensations. 
 
 Of light and of colours, 264. Organ of sight, 266. Formed of three distinct 
 parts, 266. Use of the eye-lids, eye-lashes, and lachrymal ducts, 267. Eye-ball, its 
 structure, 270. Chemical analysis of the different parts of the eye, 272., Mechanism 
 and phenomena of vision, 275. Structure and motions of the iris, 275. Refraction 
 of the rays of light by the membranes, 276, and by the flnids of the eye ; inversion 
 of object on the retina; point of distinct vision, 278. Defects of vision, 279. De- 
 velopement of the eyes and theiipattplions, 281. Errors of vision, 281. Its difference 
 in different animals, 282. S / , 
 
 Of sound, 284. Organ of lifting, 285. Structure of the ear, and mechanism 
 of hearing, 286. Differences in animals, 288. Pathological physiology of hearing, 
 288. 
 
 Of odours, 290. Organ of smell, 291. Sensation of smell, 292. Of flavours, 
 293. Of taste, 294. Of the tastes of different substances; organ of taste, 294- In 
 different animals, 295. Uses of the nerves of the tongue, 295. Galvanic experi- 
 ments on this subject, 296.
 
 XXTi' CONTEXTS. 
 
 Of touch, 297. Its certainty and errors, 297- Of the integuments, 298. Of 
 the nails, 303. Of the hair, 304. The sense of touch, 30?. Of the haud, 307- 
 Touch in different animals, 308. 
 
 Of the nerves, 309. Of their origin in sensible parts, 310. Of their structure, 
 310. Opinion of Reil on this subject, 310. Of the manner they arise from each other, 
 310. Distribution of the nerves into four different kinds, 311. Of their termina- 
 tion in the brain, 312. Of their comparative size in different animals, and in man 
 at different ages, 312. 
 
 Of the spinal chord and its functions, 313-315. 
 
 Of the coverings of the brain, 315. Mechanism of the bones of the skull and 
 face, 316. Uses of the sphenoid, 317- Rounded form of the skull, 320. Uses of 
 the dura mater, of the arachnoid, and the pia mater, 320. Size of the brain, 321. 
 Form of the head, 322. Connexion with the intellectual powers, 323. Structure of 
 the brain, 323. Nerves crossing, 324. Divergent and convergent fibres, 325. 
 Cerebral circulation, 326. Arterial blood retarded, 327- Jugular veins, 328. 
 Connexion of the action of the brain and heart, 328. Theory of syncope, 330. 
 Motion of the brain, 333. Experiments shewing the cause of the brain's motion, 
 337. Actions of the nerves and brain, 342. Principle of motion and sensation, 
 344. Different intellectual functions of different parts of the brain, 344. Not yet 
 perfectly understood, 345. 
 
 Analysis of the understanding, 345. Sources of our ideas, 346. Perception, 
 346. Reasoning and instinct, 348. Generation of the faculties, 348. Sensation, 
 perception, attention, memory, imagination, association of ideas, comparison, judg- 
 ment, reasoning, 348. Influence of signs on the faculties of thought, 351. Analysis 
 of ideas, by Tracey, 353. Derangements of the mind, 354. Mania, 354. Idiocy, 
 356. 
 
 Of the passions, 35?. State of the intellectual powers connected with them, 358. 
 Effects on the animal economy, 359. Of sleep and waking, 360. Repose of the 
 functions which connect us with surrounding objects ; condition of the functions of 
 assimilation during sleep, 361. Proximate causes of sleep, 364. Of dreams and 
 somnambulism, 365. Animals are also subject to dreams, 367- 
 
 CHAPTER VIII. 
 
 Of voluntary motions. 
 
 This chapter treats only of voluntary motions, whose organs may be distin- 
 guished into active and passive (the bones and the muscles), 368. Structure and 
 properties of muscular fibres, 369. Of the tendons and aponeuroses, 371. Pheno- 
 mena of muscular contraction determined by an act of the will, 372. A sound state 
 of tjhe nerves, arteries, and veins belonging to a muscle, necessary to its action, 372. 
 Theory of this action, 373. Preponderance of the flexor muscles over the ex- 
 tensors, 375. This preponderance varies, according to the age, and the state of 
 health or disease, 377. Pathological physiology of muscular action, 377. Of the 
 power of the muscles ; it bears a proportion to the number of their fibres, 379. The 
 degree of decurtation of which they are capable is proportioned to the length of 
 their fibres, 380. Direction of the motions performed by the action of the muscles, 
 381. Of the fixed point or fulcrum in muscular action, 382. Of muscular 
 flesh, 383. 
 
 Galvanism, 384. Volta's apparatus or galvanic pile, 389. Effects of galvanism 
 in the treatment of disease, 391. 
 
 General view of the osseous system, 393. Of the vertebral column ; it forms the 
 most essential part of the skeleton, 394. Difference of the stature at different 
 times of the day, 395. Of the lower limbs, 396. Structure of the bones, 396. 
 Uses of the periosteum and of the marrow, 399. Theory of necrosis, 399. Of the 
 articulations, 401. Of the articulating cartilages, 401. Of the synovia, 402. 
 Theory of anchyloses, 403. 
 
 Of animal mechanics ; of standing, 405. Of the centre of gravity, 405. Ten- 
 dency of the body to fall, 406. Standing is performed by an effort of the extensor
 
 CONTENTS. xxvii 
 
 muscles, 406. Reasons why it is impossible for a new-born child to stand, 407. 
 Man is the only animal that can stand upright, 411. Of falls, 414. Of standing 
 on one foot, 4 15. A degree of separation of the feet necessary in standing, 415. 
 Of kneeling; of sitting; of the recumbent posture, 416. Of lying on the sides, 
 416. Of the prone and supine postures, 417. The different modes of the recum- 
 bent posture have a reference to the degrees of facility of respiration and to the period 
 of life, 418. Recumbent posture, on an inclined plane, necessary, especially to old 
 people, 419. Of motions of progression; of walking, 420. Of walking up or 
 down an inclined surface, 421. Mechanism of the articulation between the leg and 
 foot, 422. Of running, 424. Of leaping, 425. Leaping is performed by the 
 sudden extension of the lower extremities, previously in a state of flexion, 426. 
 Of the vertical and oblique leap, 427- Of swimming ; man swims with difficulty, 
 428. Swimming natural and easy to fishes ; its mechanism, 429. Of flying, 430. 
 The structure of the body in birds is favourable to this action ; how performed, 431. 
 Of crawling, 432. All the phenomena of animal mechanics may be referred to the 
 theory of the lever of the third kind, 432. Partial motions performed by the upper 
 extremities, 434. Of climbing ; of pushing, 435. Of throwing a projectile, 436. 
 Partial motions, as signs expressive of ideas, 437. Of gestures and attitudes, 437- 
 
 CHAPTER IX. 
 
 Of voice and speech. 
 
 Definition of the voice and of speech ; circumstances necessary to the formation 
 of the voice ; its organs, 438. Opinions of Ferrein and Dodart, on the uses of the 
 glottis, 439. The larynx is at once a wind and a stringed instrument, 440. Of 
 the power of the voice ; of speech; man alone is capable of speech, 441. Of the 
 vowels and consonants, 442. Of song and music, 443. Of stammering, burr, and 
 dumbness, 444. Instruction of the deaf and dumb, 445. Ventriloquism, 445. 
 
 SECOND CLASS. 
 
 FUNCTIONS SUBSERVIENT TO THE PRESERVATION 
 OF THE SPECIES. 
 
 FIRST ORDER. 
 
 THOSE GENERATIVE FUNCTIONS WHICH APPERTAIN TO BOTH SEXES. 
 
 CHAPTER X. 
 
 Of generation. 
 
 Differences of the sexes, 449. Case in which the sexual organs did not exist. 450. 
 Hermaphrodism is never met with in the human species, 451. Of generation in 
 man, 452. Man, in the exercise of the functions of generation, not under the 
 control of the seasons, 452. Of the organs of generation in man, 453. Of (the 
 female organs of generation, 455. Of the signs of virginity, 456. 
 
 Of the functions of- the generative organs, 457- Of erection, 457. Of the 
 human semen, 458. Of the ovaria, 461. Of the impregnation of the ovum, 462. 
 Of barrenness, 463. Systems of generation, 464.
 
 CONTENTS. 
 
 
 
 SECOND ORDER. 
 
 FUNCTIONS EXCLUSIVELY BELONG?IG : TO THE FEMALE. 
 
 '; '*- ' * 
 CHAPTER XI. 
 
 Of the foetus, parturition, afd lactation. 
 
 Gestation, 466. Of the foetus and its coverings, 469. Of the developement of 
 its organs, 469. Of the circulation of the bfciod in the foetus, 4? I. Of the pla- 
 centa, 471. The umbilical chord, 474. Mode of existence of the foetus, 475. 
 Morbid affections to which it is subject while in the womb, 477- Of monsters, 
 477. Their different kinds, and the causes which produce them, 4?8. History 
 of a remarkable case, 478. 
 
 Of the chorion ; of the amnion and liquor amnii, 480. Of the allantois and 
 urachus, 481. 
 
 Of the natural term of gestation, 481. Of parturition, 482. Of the mechanism 
 of parturition, 484. Of twins, 485. The number of male children born exceeds 
 that of female, 486. Of superfoetations, 486. Of suckling, 487. Sympathy be- 
 tween the uterus and mammae ; structure of the latter, 488. The milk appears 
 not to be brought to the breasts by the lymphatics, 489. Chemical qualities of the 
 milk, 490. Connexion between the new-born child and the mother, 492. Im- 
 perfect developement of the foetal lungs, 493. 
 
 CHAPTER XII. 
 
 Containing the history of the ages, the temperaments, and the varieties of the 
 human species ; of death and putrefaction. 
 
 Of infancy, 494. Of dentition, 494. Ossification, 496. Phenomena of puberty, 
 497. Connexion between the developement of the sexual organs and the voice, 498. 
 Of menstruation, 498. Of the cause of menstruation, 499. Of the cessation of 
 this evacuation, 501. Of manhood, 501- 
 
 Of temperaments and idiosyncrasies, 501. Of the sanguine temperament, 502. 
 Of the muscular or athletic temperament, 504. Of the bilious temperament, pro- 
 duced by an increased energy of the hepatic system, joined to considerable activity 
 of the sanguineous system, 504. Of the melancholy temperament, 506. Lym- 
 phatic temperament, 509. Nervous temperament, 510. Mixed and acquired 
 temperaments, 511. Influence of climate on temperaments, 512. 
 
 Varieties of the human species, 513. European Arab race, 513. Mogul, 514. 
 Hyperborean, 515. Negro, 515. Moral characteristics of the different races, 515. 
 Giants and dwarfs, 516. 
 
 Of old age and decrepitude, 516. Decay, 518. Death, 519. Gradual extinc- 
 tion of bodily and mental powers, in the reversed order of their production, 520. 
 Period of death, 521. Probabilities of human life, 522. Returns of longevity in 
 Great Britain, 524. Putrefaction, 525.
 
 ADDITIONAL NOt)g, AND .DISQUISITIONS, 
 BY THE EDITOR. 
 
 ADDITIONAL NOTES 
 TO THE PRELIMINARY DISCOURSE. 
 
 Of life (Note A), 531 Life, although connected with organisation, is not a 
 
 function of organisation, 531. The arguments used by the organists shewn to be 
 inconclusive, &c. 532. 
 
 Of the nervous system in the lower animals (Note B), 534 This system 
 
 exists in all animals, 534. Its organisation more perfect, and its parts more com- 
 plicated, as we ascend the scale of animal creation, 535. 
 
 Of the primary solids and compound textures of the body (Note C), 535 
 Meckel's opinion respecting the elementary tissues, 536. Opinions of Pfaff and of 
 Meyer, 536, 537- The Editor's division of the primary solids, 537- The divisions 
 of Chaussier and of Bichat, 538. The divisions of the animal textures adopted by 
 Dupuytren and Beclard, 538. By Meckel and De Blainville, 539. By Professor 
 Meyer, 539. 
 
 The analytical division of the various textures of the body proposed by the 
 Editor, 539: 1, Complex, or associated structures, 540; 2, Particular textures, 
 540 ; 3, General systems, 540 ; 4, Elementary solids or fibres, 540. A synthe- 
 tical table of the Editor's classification of the animal textures, 540. Simple tissues, 
 as enumerated by Dr. Craigie, 541. 
 
 Of sensibility and contractility (Note D), 542 Of sensibility, and its various 
 
 states or modes, 542. Active sensibility, 542. Passive sensibility, 543. Organic 
 sensibility, 544. The states or modes of organic sensibility, 544. 
 
 Contractility, 545. Insensible organic contractility, 545. Sensible organic 
 contractility, or irritability, 545. Cerebral contractility, or the contractions occa- 
 sioned by the will, 545. Sensibility and contractility contrasted, 545. 
 
 Of sympathy (NoteE), 546 Sympathies divided into direct and reflex, 546. 
 
 The ganglial nerves, in their direct ramifications, and in their course along the 
 blood-vessels, the chief agents of sympathy, 546. Organic sympathies, in which 
 the vital energy evinces various modifications in degree and distribution, 54?. 
 Illustrations, 547- Organic sympathies, in which, in addition to various modifi- 
 cations in degree and distribution, the vital manifestations suffer a change in kind, 
 549. Illustrations, 549. 
 
 Of habit (NoteF), 550. Modifications in the effects of habit on the volun- 
 tary and involuntary organs, 550.
 
 XXX CONTENTS. 
 
 Of inflammation (Note G), 550 The first change inducing the phenomena 
 
 of inflammation commences in the fibriles of the organic nerves, 551. Phenomena 
 of inflammation, 552 : 1 , Uneasy sensation, 552 ; 2, Redness, 553 ; 3, Increased 
 animal heat, 554. Turgescence of the capillaries, and consequently of the inflamed 
 part, 555. 
 
 Of the ganglial or great sympathetic system of nerves (Note H), 556 This 
 
 system exists in every individual of the animal creation, 556. The other orders of 
 nerves proceed from this system, 557- The ganglial nerves differ in organisation, 
 distribution, and function, from the other nerves, 557- They form an original and 
 distinct system, 558. Proofs of the independence of the ganglial system of nerves, 
 558. Of the parts supplied by the ganglial nerves, 558. Influence of the ganglial 
 nerves on the circulating system, 559. The subordinate ganglia bestow a modified 
 vital influence on the organs which they supply with nerves, 559. The relations of 
 the ganglial nerves with the heart and arteries, 560. Influence of the ganglial 
 system on the blood, 560. Influence of this system on the secreting organs and 
 secretions, 560. Influence of this system on the portal circulation, and functions 
 of the liver, 561. Influence of this system on animalisation and nutrition, 560. 
 Influence of the ganglial system in the production of animal heat, 562. The reci- 
 procating influences of this system on the cerebro-spinal nervous system, and of this, 
 latter on the former, 562, 563. Modified vital functions of distinct ganglia and 
 plexuses, 565. 
 
 ADDITIONAL NOTES TO THE CHAPTER ON 
 DIGESTION. 
 
 Of some collateral phenomena of digestion (Notes I and K), 565, 568 The 
 
 effects of long-protracted abstinence illustrated by a singular case, 565. Opinions of 
 M. Lallemand respecting digestion in the stomach,, 568. Opinions of the Editor 
 respecting digestion, 569. Of human rumination, 569. Its nature and causes, 
 570. Of the influence of the pneumo-gastric nerves on digestion, 573. The conclu- 
 sions drawn by MM. Breschet, Edwards, and Vavasseur, from their experiments, 573. 
 Reflections by the Editor, 574. Conclusions of the Editor as to the influence of the 
 nerves in digestion, and as to the operation of galvanism, 5?5. 
 
 Of vomiting (Note L), 576 The opinion of Magendie on this subject contro- 
 verted, 576. Opinions of the Editor respecting it, 577- 
 
 Of the intimate structure and functions of the liver (Note M), 578. The re- 
 searches of M. Mappes on the structure of the liver, 578. Function of the granular 
 structure of the organ, 580. The assimilating function of the liver maintained by 
 the Editor, 580. The assimilating and secreting processes of the organ necessarily 
 related to each other, 580. Source of the vital actions of the liver, 581. , Of the 
 varying characters and properties of bile, 581. Of the uses of bile, 582. Opinions 
 of Mr. Brodie and of Dr. Prout as to the bile, 583. Of the gall-bladder and 
 cystic bile, 584. Opinion of Dr. Stearns, 584. 
 
 Of the structure and functions of the spleen (Note N), 685. Opinions of va- 
 rious authors as to its functions adduced, 585. Researches into the structure of the 
 spleen, 586. Inquiries of Be"clard, Home, Schmidt, Tiedemann, Gmelin, and 
 others, as to its structure and functions, 586-588. The nervous connexions of the 
 organ, 588. The influence of various agents on the spleen, 589. 
 
 Functions of the small and large intestines (Note O), 589 Of the stricture of 
 the mucous surface of the digestive tube, 589. Of the villosities, 589. Of the func- 
 tions of the digestive mucous surface, 590. Of the digestive process in the intes- 
 tines, 590. Is not a chemical, but a vital process, 590. Of the functions of the 
 caecum, 591. The opinion of Viridet confirmed by Tiedemann and Gmelin, 591. 
 Physiological pathology of the caecum, 592. The function of feecation, 593. 
 
 Of the functions of the kidneys (Note P), 594 Results of experiments per- 
 formed by MM. Dumas, Prevost, and Legulas, 594. Of the production of urea, 
 594. Pathological relations of the states of the urine, 595.
 
 CONTENTS* xxxi 
 
 ADDITIONAL NOTES TO THE CHAPTER ON 
 ABSORPTION. 
 
 Of absorption (Note Q), 596 Of absorption from the digestive canal, 596. The 
 
 results of Tiedemann's and Gmeliii's researches, 596. Of the passage of chyle into 
 the vena portee, 597- Results of experiments, 597- Experiments of MM. Seller 
 and Ficinus, 59?. Inferences of the Editor, 597, 598. 
 
 Of absorption in the lungs, 598. Opinions of Professor Meyer of Bonn, 598. 
 
 Of the manner in which absorption is performed, 600. Opinions of Magendie, 
 600. Investigations of MM. Segalas and Fodera, 601. Their opinions, 601. Of 
 transudation and imbibition, 601. The veins and absorbents only absorb, 605. 
 Certain substances seem to be absorbed chiefly by the veins, 605. The rapidity 
 of absorption, 605. Inferences of the Editor, 606. The researches of Drs. Law- 
 rence and Coates, 606. Their experiments referred to, 607- Opinions of Dr. 
 Barry as to the agency of atmospheric pressure in absorption, 609. 
 
 The Editor's views as to absorption of foreign substances into the blood, and as 
 to the operation of medicines in this way, 609. Inferences by him as to va- 
 rious points connected with absorption, overlooked by physiologists, 610. 
 
 ADDITIONAL NOTES TO THE CHAPTER ON THE 
 CIRCULATION. 
 
 Of the action of the heart and arteries (Note R), 611. Of the nerves of the 
 heart, 611. The actions of the heart are chiefly dependent upon the ganglial 
 nerves, 612. Indirect influence of the cerebro-spinal nervous system on the actions 
 of the heart, 612. Of the active dilatation of the heart, 613. 
 
 Of the arteries, 613. Their connexion with the ganglial system of nerves, 613. 
 Of the action of the arteries in the circulation, 614. Opinions of Magendie, 
 Home, Hastings, and others, 614. Inferences of the Editor, 615. 
 
 Of the functions of the capillaries (Note S), 615 Division of the capillary 
 
 vessels, 615. Of subordinate capillary vessels, 616. Opinions of Drs. Alard and 
 Hutchinson, 616. 
 
 Of the veins (Note T), 617- Of the commencement of the veins, 617. Of 
 the functions of veins, 618. Influences by which the veins circulate their contents, 
 618. Absorbing function of the veins, 618.' Assimilating function of the veins, 
 618. Of the functions of the portal veins, 619. 
 
 ADDITIONAL NOTES TO THE CHAPTER ON 
 RESPIRATION. 
 
 Of the mechanism of the respiratory organs (Note U), 619 Of the structure of 
 the lungs, 619. Magendie's description of the cellules of the lungs, 619. The 
 description of the bronchia and air-cells, given by M. Reisseisen, 620. Of the 
 actions of the glottis, 620. Of the state of the lungs during respiration, 621. 
 Opinions of Dr. Carson, 621. Experiments of Dr. D. Williams, 622. 
 
 Of the effects of respiration on the venous circulation, 622. The experiments 
 of Haller, Lamure, Lorry, Cloquet, and Bourdon, referred to, 622. The inferences 
 of M. Magendie, 623. The experiments and opinions of Dr. Barry, 623. 
 Inferences of Dr. Arnott, and of the Editor, respecting the opinions of Drs. Barry 
 and Carson, 623. 
 
 Dr. Williams's inferences as to the effects of suspended respiration on the 
 circulation, 624. 
 
 Of the changes induced on the air and the blood by respiration (Note W), 
 625 Of the production of carbonic acid during respiration, 625. Opinions of the 
 Editor, 625. The experiments of Drs. Edwards, Murray, Prout, Fyfe, &c., 

 
 xxxii CONTENTS. 
 
 referred to, 626. Influence of temperature and other causes, in the production of 
 carbonic acid during respiration, 626. Results of the Editor's researches, 627- Is 
 the carbonic acid formed within, or external to, the vessels ? 627. Inferences of 
 the Editor, 628. Of the absorption and exhalation of azote during respiration, 628. 
 The experiments of Dr. Edwards on this point referred to, 628. 
 
 Of pulmonary transpiration, 629. Experiments of Magendie and of the Editor 
 on this topic referred to, 629. 
 
 Of the assimilating function of the lungs, 629. The influence of respiration on 
 the generation of animal heat, 630. 
 
 Of the production of animal heat, 630. The preparatory changes take place in 
 the lungs, 630. The ganglial nervous influe/ice a chief agent in the generation of 
 animal heat, 630. The state of the blood modifies the degree of heat, 630. 
 Animal heat is a vital secretion rather, than a chemical phenomenon, 631. 
 
 Of the cutaneous function (Note Z), 631 Of insensible transpiration, 631. 
 
 Of the influence of states of the air in promoting the cutaneous function, 631. 
 Opinions of Dr. Edwards, 631. Of the sweat, or sensible exhalation, 632. The 
 skin is a respiratory organ, 632. Proofs, 632. The skin is an eliminating 
 organ, 633. 
 
 ADDITIONAL NOTES TO THE CHAPTERS ON THE 
 SECRETIONS AND NUTRITION. 
 
 Of the fluids (Notes A A), 633. Of the classifications of the fluids, 633. 
 Classification of Adelon, 633. The absorbed fluids, 633. The nutritive fluids, 634. 
 The secreted fluids, 634. The recrementitial fluids, 634. The excremeutitial 
 fluids, 635. Humours secreted by follicular glands, 635. Secretions of glandular 
 organs, 635. 
 
 Of the states of the various secretions, 635. Editor's opinion as to their being 
 endowed, to a certain extent, with an emanation of vitality, which, for a time, 
 resists the changes which they are disposed to enter into, 636. 
 
 Of the blood (Notes B B), 637 Of the small or colourless globules of the 
 blood, 637 Results of the microscopic observations of Home and Bauer, 637- Of 
 HIM. Prevost and Dumas, 638. Of the red globules, 638. 
 
 Of the coagulation of the blood, and on its vitality, 638. Results of the 
 researches and observations of the Editor on these subjects, 639. The motion of 
 the particles of the blood, 639. The vitality of the blood derived from the vessels 
 containing it, and the organs in which it circulates, 639. Vitality first manifested, 
 in an obscure manner, in the chyle, 639. Coagulation proceeds from the loss of 
 the vital emanation with which the blood was endowed when in the vessels, and 
 from the presence of the air. 639. Coagulation of arterial blood, 639. Circum- 
 stances influencing the coagulation of the blood, 639. Of the formation and source 
 of the fibrin, 640. Circumstances influencing the state and appearances of the 
 coagulum, 640. The state of the coagulum is chiefly owing to the state of the 
 vital influence of the system generally, modified by the condition of the blood itself 
 at the time, 640. The lower the vital action, the quicker the coagulation, but the 
 looser will be the coagulum, 640. The state of the coagulum shewn to be 
 dependent upon the vital influence, 641. The subject illustrated, by referring to 
 various diseases of an opposite character, 640, 641. Various pathological in- 
 ferences, 640-642. 
 
 Of the transfusion of blood, and the injection of various foreign matters into 
 it, 642. Experiments of MM. Prevost and Dumas referred to, 642. The 
 practical success of Dr. Blundell with transfusion, 643. 
 
 Of secretion and exhalation (Notes C C), 643. Of the mechanism by which 
 these functions are performed, 643. As to the existence of distinct secreting 
 capillaries, or of pores, &c., 644. Of the influence of the ganglial nerves in 
 secretion, 644. 
 
 Of nutrition (Notes D D), 645. Of the mechanism of nutrition, 645. 
 Opinions of Mascagni, Bichat, and Prochaska, on this point, 645. Inferences 
 deduced by the Editor, 646. The subject illustrated, by reference to nutrition in
 
 CONTENTS. 
 
 the lower classes of animals, 647- The ganglial nerves shewn to be instrumental 
 in nutrition, 647- Nutrition essentially a vital action, C48. 
 
 ADDITIONAL NOTES TO THE CHAPTER ON SENSATIONS. 
 
 Of the decussation of the optic nerves, and motions of the eye (Notes E E), 
 649 Decussation of the optic nerves, 649. Inferences of Treviranus and Ma- 
 gendie, 649. 
 
 Of the motions of the eyes ; opinions of Mr. C. Bell, 650. Of the connexion, 
 of the fifth pair of nerves with the function of vision, 651. Case recorded by 
 M. Lerres, illustrating this connexion, 651. 
 
 Of the adaptation of the lens to distinct vision, 651. The inferences of 
 Professor Mile on this subject, 652. 
 
 Of the nerves chiefly concerned in the sense of smell (Notes', F F), 653 
 
 Opinions of various authors respecting the nerves concerned in the sense of smell, 
 653. Inferences of the Editor, 654. 
 
 Of the formation of the spinal chord and brain (Notes G G), 654 The 
 
 formation of the spinal marrow, according to the observations of Gall, Tiedemann, 
 Wenzel, Doellinger, Cams, and the Editor, 654. The Editor's opinion that the 
 spinal chord is produced from the ganglial system of nerves, 655. The de- 
 velopement of the chord at the various periods of fetal life, 655-657- 
 
 Of the formation of the brain, 658. Researches of Tiedemann, 658. De- 
 velopement of the brain at the different epochs of foetal existence, 659. 
 
 The relative weights of the cerebrum, of the cerebellum, and of the whole brain, 
 at the various epochs of existence, 660. 
 
 Of the cephalo-spinal fluid, C61. M. Magendie's inferences respecting its 
 uses, 662. 
 
 Of the functions of the cerebro-spinal system of nerves (Notes G G), 662 
 
 General view of the nervous system through the different classes of animals, 662. The 
 rudiments of a nervous system, 602. Its progressive developement as we ascend 
 the scale of animals, 663. Opinions of Home, Saint Hilaire, De Blainville, and 
 Schultze, on the protection which the skeleton gives to the nervous system, 664. 
 
 Of the functions of distinct parts of the cerebro-spinal order of the nervous 
 system, 665. The results of the researches of M. Flourens, 665. Functions of the 
 hemispheres, 666. Of the cerebellum, 667. Of the tubercula quadrigemina, 667. 
 Conclusions from the experiments of M. Flourens, 668. The results of experiments 
 by M. Rolando, 669. Inferences of M. Flourens, 669. 
 
 Of the distinct functions of the anterior and posterior columns of the spinal 
 marrow, 669. Opinions and experiments of Bell and Magendie, 670. Opinion of 
 M. Ollivier, 671. Opinion of Dr. Spurzheim, and of the Editor, 672. Experiments 
 of Dr. Bellingeri, 672. Experiments of M. Schcepf referred to, 673. 
 
 Of the respiratory order of nerves, 673. The researches of Bell, Shaw, Mayo, 
 and Broughton, into the functions of this order of nerves, 674. Inferences of the 
 Editor, 675. Principle observed in the origin of the cerebro-spinal nerves, 676. 
 
 General remarks on the different parts composing the nervous system, 676. 
 Divisions proposed of the nervous system, 677- The functions of distinct nerves 
 not yet assigned with sufficient precision, 677- The functions of nerves vary 
 according to the nature of the organs they supply, 677- Many nerves seem 
 concerned in more than one function, 677, 678. The opinions of Johnstone, 
 Bichat, Soemmering, and Reil, respecting the ganglial nerves referred to, 678. 
 Opinions of the Editor, 678. 
 
 Of the phenomena of mind, as manifested through the instrumentality of a 
 perfect nervous system (Notes H H), 679. The slow progress of the science of 
 mind, 679. Difficulty of the subject, 679. Causes of the slow progress of our 
 knowledge respecting it, 680. Impeded by the doctrine of materialism, 680. 
 The doctrine of materialism combated, 681. Dr. Brown quoted, 681. The 
 materialists have falsely assigned the opinions of Gassendi to Locke, 682. The 
 writings of various metaphysicians referred to, 680-682.
 
 xxxi* CONTENTS. 
 
 Basis of a classification of the phenomena of mind proposed by the Editor, f<82. 
 Table of the Editor's arrangement of the manifestations of mind, 682. Instinctive 
 feelings and emotions, 682. Instinctive feelings which tend to preserve the 
 individual, 682. Instinctive feelings which tend to perpetuate the species, 683. 
 Other instinctive 'emotions of mind, 683. Intellectual powers or states of mind, 
 683. Powers of consciousness, 683. Powers of intellection, 683. Ideas of re- 
 flection, arising from the exercise of the former powers, 683. Moral affections of 
 mind, 684. 
 
 Reflections on the above classification, 684. Consciousness accompanies all 
 present mental manifestations ; but is more intimately related to certain states of 
 mind, 684. Instinctive affections of mind inquired into, 685. Man is possessed of 
 various instinctive or innate emotions and affections of mind, beyond those evinced 
 by the lower animals, 685. The opinions of Locke, Berkeley, Hume, and 
 Condillac, as to the instinctive feelings, denied, 685. 
 
 An analytical classification of the phenomena of mind, according to the views 
 of the late Dr. Thomas Brown, 685. External affections of mind, 685. Internal 
 affections of mind, 686. Intellectual states of mind, 686. Emotions of mind, 687- 
 
 Of the doctrines of Gall, 688. Dr. Gall's summary of his doctrine, 689. Of 
 dreaming, 689. 
 
 Of the formation and developement of the muscular textures, and of the source of 
 
 irritability (Notes I I), 690 Researches of Dr. Isenflamm, 690. Results of 
 
 microscopic observations of the muscular fibre, 691. Relations of the muscular 
 fibres with the nervous tissue, 691. Source of irritability, 692. Inferences of the 
 Editor, 692. The nerves of volition merely convey a stimulus to parts already 
 possessed of the faculty of contraction, 693. The opinion thrown out, that the 
 voluntary and other nerves originate in the structures which they supply, 694. 
 
 Of galvanic electricity (Notes K K), 694 The researches of Davy, Wol- 
 
 laston, Biot, Coulcomb, Poisson, Oersted, and Becquerel, referred to, 694". Elec- 
 tricity results from two distinct fluids, 694. Mode of their existence on the surface 
 of the earth, 694. The classes of phenomena which -they produce in their electro- 
 motive capacity, 694. The circulation of the electricities, or their electro-motive 
 state, gives rise to the phenomena of galvanism, 695. General law established by 
 M. Biot, 695. Law as to the attraction existing between the electric fluid and 
 material substances, 696. Relation of chemical affinity to galvanic electricity, 696. 
 Gravitation and repulsion depend upon the electricities, 696. Late discovery by 
 Mr. Brown, of motion existing in all organic and inorganic matter, referred to 
 vitality in the former, and the electricity in the latter, 696. The relation of the 
 electrical states with light, 696. The polarisation of matter depends upon the 
 electricities, 697. Connexion between the electrical agencies and magnetical at- 
 tractions, 697. 
 
 Opinion of the Editor, that all the phenomena of the inorganised world, and of 
 the solar systems (as attraction, gravitation, affinity, combustion, crystallisation, 
 magnetism, light, and heat), may be explained by means of the agency of the two 
 universally diffused electricities, 697. The electro-motive energy cannot, however, 
 account for all the vital phenomena, 698. The opinions of Sprengel, Reil, 
 Prochaska, Philip, Lenhossek, &c., referred to, and controverted, 698. Influence 
 of the electro-motive energy upon living bodies and textures referred to and 
 illustrated, 700. Experiments of Ritter, Ure, and Philip, referred to, 700. 
 Criticisms by the Editor, 701. The opinion that life is identical with galvanism, 
 noticed and rebutted, 701. Observations of Dr. Pring as to this topic, referred 
 to and quoted, 701. 
 
 Of ossification (Notes L L), 703 Observations of MM. B<5clard and Serres, 
 703. Progress of ossification at the different epochs of foetal life, 703-704. 
 
 Of voice (Notes MM), 705 Office of the muscles of the larynx in the 
 
 5 reduction of voice, 705. Of ventriloquism, 705. Explanations of Dr.' Good and 
 1. Magendie, 705. 
 
 Of the generative organs and their functions (Notes N N), 706 Of the 
 male organs, of generation, 706. Of the structure of the penis, 706. Of the
 
 CONTENTS. XXXV 
 
 jjervous influence upon the circulation of the organ, 70G. Of the function of the 
 vesicul seminales, 707- Of the spermatic animalculw, 707- 
 
 Of the female organs of generation,- 707' Of the nerves supplying the female 
 generative organs, 70?. Description of Tiedemann, &c. 707- These nerves 
 enlarge during gestation, 708. 
 
 Of impregnation, 708. Opinions of authors, 708. Ovarian feetation, and cases 
 of referred to, 709. The venereal desire exists previous to the developement of 
 the ovaria and testes, 709 ; and continues after the disappearance of the menses, 
 709. Conception may take place even although the female may be indifferent 
 during the venereal congress, 709. Experiments of Dr. Blundell referred to, 710. 
 The presenoe of corpora lutea cannot be relied upon as a proof that impregnation 
 had taken place, 710. Impregnation cannot take place unless the semen comes in 
 contact with the rudiments, 711. 
 
 Of superf relation, 711. Cases of, referred to, 71 ! 
 
 Of the developement of the textures and organs of the foetus (Notes OO), 771. _ 
 The early state of the embryo, 712. Progressive developement, 712. Early appear- 
 ance of the rudiments of a nervous system, 712. First appearance of the intestinal 
 canal, 712. The progressive phases through which the human embryo passes during 
 the early epochs of foetal existence, 713. These correspond to the different stages of 
 organisation observed as we ascend the scale of animal creation, 713. 
 
 Developement of the nervous system of the foetus, 713. This system seems to 
 be formed from the circumference, the nerves advancing from the organs which 
 they supply towards centres, which become more fully developed as the embryo 
 advances, 714. 
 
 Of the developement of the heart, 714. Observations of M. Meckel, 714. Of 
 the developement of the pulmonary organs, 715- Researches of Meckel, 71G- 
 
 Of the circulation of the placenta, 717- Experiments of M. Gaspard, 717- 
 Proofs that the fcetal blood is fabricated by the foetus itself, chiefly from the nu- 
 tritious juices furnished to the placenta, 717- By what organs is the sanguifying 
 process of the foetus performed ? 717- The question answered, 718. Opinions of 
 M. Geoffrey St. Hilaire and Dr. R. Lee, 718. The sanguifying process of the 
 liver of the foetus intimately connected with a secreting function, 718. 
 
 Respiration of the foetus, 718. Means by which the requisite changes are 
 effected in the fcetal blood, 718. Opinions of Mueller and Saint Hilaire, 719. 
 
 Of the varieties of the human species (Notes PP), 719 The classification of 
 
 Cuvier preferred to those of other authors, 719. The Caucasian variety, 719- 
 Mongolian variety, 720. The Negro variety, 720. Of the Malays and the Papuas, 
 720. The American tribes, 720. 
 
 Of the mortality of females at the change of life (Note Q Q), 720. _ Results of 
 M. Benoiston de Chateauneuf's inquiries, 720. 
 
 APPENDIX, No. II. 
 
 THE CHEMICAL CONSTITUTION OF THE SOLIDS AND FLUIDS 
 OF THE HUMAN BODY. 
 
 I. Simple substances entering into the constitution of the different animal prin- 
 ciples or constituents of the human body, 721. 
 
 II. Animal constituents or principles, 721 Gelatine, 721. Albumen, 721. 
 
 Fibrin, 721. Colouring matter of the blood, 721. Urea, 722. Mucus, 722. 
 Osmazome, 722. Picromel, 722. Sugar of milk, 722. Fixed oils, 723. Acids, 723. 
 
 III. Individual textures and fluids of the human body, 723. Constituents of 
 the bones and teeth, 723. Of the enamel of the teeth, 724. Of tophus, 724. 
 Of the marrow of bones, 725. Of cartilages, 725. Of the synovia, 725. Synovia
 
 xxxvi CONTENTS. 
 
 of the horse and elephant, 725. Composition of the periosteum, 726. Of the 
 ligaments, 726. Of the membranes, 726. 
 
 Chemical constitution of the integuments, 726. Of the cutis vera, 726. Of the 
 rete mucosum, 726. The epidermis, 726. Of the hair, 726. 
 
 Constitution of the muscular flesh, 727- Of the heart, 727- Of ossific deposits 
 in muscular flesh, 727- 
 
 Constituents of the brain and nerves, 727. Of the medulla oblongata, 728. 
 Of the nerves, 728. Of the greasy substance of the brain, 728. Of the white 
 medullary matter, 728. Of the lymph found in the ventricles of the brain, 728. 
 Of concretions found in the brain, 728. 
 
 Constituents of mucus, 728. Of the saliva, 729. Of salivary calculi, 729. 
 Of the tartar of the teeth, 729. Of the lachrymal fluid, 729. 
 
 Constituents of the gastric juice, 729. Of the lymph, 729. Of the chyle, 729. 
 Chyle of the horse, 729. Of the dog, 730. 
 
 Constituents of the blood, 730. Of the serum, 731. Of the cruor or clot, 731. 
 Of the fetal blood, 732. Of diseased blood, 732. 
 
 Constituents of milk, 732. Of the curd, 732. Of the cream, 732. Of, the 
 whey, 733. Of fermented milk and whey, 733. Peculiarities of human milk, 733. 
 
 Constituents of bile, 734. Of biliary calculi, 734. 
 
 Cerumen of the ears, 734. Of the tears, 734. Of the sweat, 734. 
 
 Constituents of urine, 734. Of the urine in various diseases, 735. Of the 
 semen, 735. Of the human ova, 736. Of the amniotic fluid, 736. 
 
 Constituents of pus, 736. Of expectorated matter, 736. Liquor of the peri- 
 cardium, 737. Liquor of dropsy, 737. Fluid from blisters, 737. 
 
 Composition of human. faeces, 737- Gases existing in the intestinal canal, 737. 
 In the stomach, 738. In the small intestines, 738. In the large intestines, 738.
 
 PRELIMINARY DISCOURSE. 
 
 PHYSIOLOGY* is the science of life. The term life is applied to an 
 aggregate of phenomena, which manifest themselves in succession, 
 for a limited time, in organised bodies. Combustion is likewise only 
 a combination of phenomena ; oxygen unites with the substance which 
 is burning, caloric is disengaged from it ; affinity is the cause of these 
 chemical phenomena, as attraction is the cause of the phenomena of 
 astronomy, and in the same manner as the sensibility and contractility 
 of living and organised bodies are the primary causes of all the phe- 
 nomena which such bodies exhibit phenomena which, in their union 
 and aggregate succession, constitute life. 
 
 The false notions which have been entertained on the subject 
 of life, and the vague definitions which have been given of it, are 
 to be accounted for, by considering that physiologists, instead of 
 regarding life as a simple result, have mistaken it for the properties 
 of life. These last are causes : the first is merely an effect, more 
 or less complex ; and, as the spring of a watch, or rather the elasticity 
 of that spring, determines, by the mere action of the wheels, the 
 motion of the hands, and all the phenomena of which the machine 
 is capable ; so the vital properties acting by the organs produce 
 all those effects, which in their combination constitute life.f These 
 effects are more or less numerous, according to the number of the 
 organs: they become more rapid, too, in their succession, and life 
 more active with the increase of energy in the vital properties, pre- 
 cisely as the motions of a watch become more complicated, stronger, 
 or quicker, according to the greater tension of the spring, or the 
 increased number of the wheels. Sensibility and contractility are to 
 be ranked among primary causes, of whose existence and laws we 
 acquire a knowledge from observation, but whose essence eludes our 
 investigation,^ and will probably remain for ever beyond its reach. 
 
 * Anatomy is the science of organization. -f- See APPENDIX, Note A. 
 
 : It would be wrong to infer, from our ignorance of the nature of the vital pro- 
 perties, that physiology is an uncertain science. Its certainty, in that point of
 
 OF THE ELEMENTS OF BODIES. 
 
 SECT. I. OF NATURAL BEINGS. 
 
 The vast domain of nature is divided between two classes of 
 beings. Inorganic beings, possessing merely the common properties 
 of matter ; organic and living beings, obeying particular laws, though 
 subjected to the general laws which regulate the universe. Each of 
 these two grand divisions is naturally divided into two classes: we 
 meet with inorganic bodies under the form of elementary substances, 
 simple and not capable of analysis, or else under the form of mixed 
 substances, compound, and admitting of decomposition. Thus, too, 
 organised beings exist under two very different forms of life, which 
 distinguish them into vegetables and animals. 
 
 The first general conception with which we ought to enter upon 
 this comprehensive study of nature is, the mutual dependence of 
 those beings, which, in their co-ordinate whole, compose the system 
 of nature a dependence which requires for each the simultaneous 
 existence of all. Thus a vegetable derives its nourishment from in- 
 organic bodies,* and alters their inert substance, which is unfit for the 
 food of animals, unless it has previously undergone the influence of 
 vegetable life. 
 
 SECT. II.OF THE ELEMENTS OF BODIES. 
 
 Another consideration, of equal importance with the former, is, 
 the convertibility of all those substances so different from one another, 
 and their capacity of being reduced to a small number of simple 
 substances, called elements. The ancient doctrine of Aristotle, relative 
 to the four elements, still prevailed in the schools, with a few mo- 
 difications which it had received from the chemists, when the 
 " pneumatists" f demonstrated, by their beautiful experiments, that 
 
 view, is equal to that of other parts of natural philosophy. The chemist, who 
 explains all his combinations by referring them to the principle of affinity, and the 
 astronomer, who finds in attraction the cause that rules the universe, are absolutely 
 ignorant of the nature of those properties. 
 
 * MIRBEL, in his Treatise on Vegetable Anatomy and Physiology, observes, 
 " that plants have the power of deriving nourishment from inorganic matter, which 
 is not the case with animals who feed on animals and vegetables, or on both, but 
 are never nourished on earths, salts, and airs." Richerand has adopted the 
 plausible opinion of Mirbel. Farther inquiry might, however, have shewn them 
 that " earths and salts" furnish as little direct nourishment to plants as to animals. 
 Indeed, it may be observed, that the vegetable kingdom derives the chief part of 
 its food from dead animal and vegetable matters, which, although they contain 
 both " earths and salts," cannot be either ranked under these substances, nor 
 even classed with them J. C. 
 
 + This is the name given to the school of modern chemistry, because it 
 originated from the discoveries made relative to the nature of air and elastic 
 fluids. It must be acknowledged, to the credit of metaphysics, that the old errors
 
 CHARACTERISTICS OF ORGANISED BODIES. :: 
 
 three, at least, of these pretended principles of bodies, air, water, 
 and earth, far from being simple substances, were evidently formed 
 by the union and combination of several others ; that atmospherical 
 air, for example, far from being a homogeneous fluid, was composed 
 of many different gases, and that in its purest state it contains at least' 
 two very distinct principles oxygen and azote; that water is a 
 compound of oxygen and hydrogen, and that earth contains clay, 
 lime, silex, &c. 
 
 We have seen added, in the present day, to the number of the 
 elements or simple substances, several which were not considered as 
 such at the time when natural philosophers, misled by erroneous 
 metaphysical doctrines, had created out of their imaginations beings 
 of the existence of which they could find no proof. There is every 
 reason to believe, that the number of substances not admitting of 
 decomposition, limited at present to fifty-one, without embracing the 
 imponderable bodies, may hereafter be increased or diminished by 
 the discovery of new principles in simple substances, or of new elements 
 in compound bodies, which have hitherto eluded the investigation of 
 chemists. Whatever may be the success of their inquiries, of which 
 it is impossible to foresee the results or to fix the limits, there is reason 
 to believe that it will ever be denied us to arrive at a knowledge of the 
 true elements of bodies, and that many of those substances, which 
 the imperfection of our means of decomposition or analysis obliges us 
 to consider as such, are frequently compound substances, and subject 
 to their laws. 
 
 After what has been stated on the elements or constituent prin- 
 ciples of substances, let us now see in what manner the combination 
 of these elements gives existence to all beings, and what are the 
 general differences existing among the great classes into which they 
 are divided. 
 
 SECT. III. DIFFERENCES BETWEEN ORGANISED AND 
 INORGANISED BODIES. 
 
 Much attention has been bestowed of late on the difference which 
 exists between organised and inorganised bodies. The latter have 
 been observed to be very different from those which are endowed 
 with life, in the homogeneous nature of their substance, in the com- 
 plete independence of their molecules, each of which, according to 
 the observation of Kant, has in itself causes to account for its peculiar 
 mode of existence, in that power of resisting decomposition which they 
 
 were forsaken, only at the period when chemists were thoroughly convinced of this 
 truth, that every idea is obtained through the medium of the senses, and that 
 nothing is to be admitted beyond what they demonstrate in actual experiment.
 
 4 CHARACTERISTICS OF ORGANISED BODIES. 
 
 owe to the simplicity of their structure, and in the absence of those 
 peculiar powers which free organic bodies from the absolute dominion 
 Of physical laws. The multiplicity, the volatility of their elements, 
 the necessary union of fluids and solids, the nutrition and development 
 from the diffusive combination, while the growth of inanimate bodies 
 takes place from the mere juxta-posidon of particles, the origin of 
 living bodies in generation, their destruction in death, such are the 
 characters which distinguish organised beings from inorganised sub- 
 stances. We are about to enter into a detail of those characters, 
 to appreciate all their differences ; for knowledge is to be acquired 
 only by comparison, and the greater our accuracy in comparing, the 
 more precise and extensive will be the knowledge we obtain. Several 
 modern authors have proved, that it is impossible to obtain an accurate 
 idea of life, except by comparing those bodies which are endowed with 
 it with those in which life has never existed, or has ceased to exist. 
 This comparison, I hope, will be fruitful in interesting results, and 
 will furnish several useful considerations immediately applicable to the 
 knowledge of man. 
 
 The first remarkable difference between organised and inorganised 
 bodies is to be found in the homogeneousness of the latter, and the 
 compound nature of the former. Let a block of marble be broken ; 
 each piece will be perfectly similar to the rest; there will be no 
 differences among them, but such as relate to size or shape. Break 
 down the fragments; each grain will contain particles of carbonate 
 of lime, which will be throughout the same. On the other hand, the 
 division of a vegetable or an animal shews parts heterogeneous or 
 dissimilar. In different parts there will be found muscles, bones, 
 arteries, blossoms, leaves, bark, pith, &c. 
 
 Organised beings cannot live or exist in their natural condition, 
 unless solids and liquids enter at once into their composition. The 
 co-existence of these two elements is necessary ; and living bodies 
 always contain a liquid mass more or less considerable, and incessantly 
 agitated by the motion of the solid and living parts. It is, in fact, 
 impossible to conceive life existing without a complicated combination 
 of solids and fluids ; and without admitting in the former the faculty 
 of being affected by impressions from the latter, and the power of 
 acting in consequence of those impressions. The water which pene- 
 trates into mineral substances does not form a necessary part of them ; 
 and one cannot adduce in proof of the existence of liquids in that 
 class of substances, the water of crystallisation, though intimately 
 combined, and rendered solid in the crystallised substances. 
 
 These inorganic and homogeneous substances, formed of particles 
 similar to one another, when resolved by decomposition into their last 
 elements, possess a great implicity of inward nature. Among them are
 
 CHARACTERISTICS OF ORGANISED BODIES. 5 
 
 ranked all the substances which do not admit of analysis ; the mineral 
 compounds are often binary, as the greater part of saline substances ; 
 sometimes they are ternary, but seldom quaternary ; while the most 
 simple vegetable contains at least three constituent principles, oxygen, 
 hydrogen, and carbon ; and no being possessed^of life consists of less 
 than four, oxygen, hydrogen, carbon, and azote. In the degree of 
 composition, nature appears, therefore, to rise in gradations, from the 
 mineral to the vegetable, and from the latter to the animal kingdom. 
 The complicated nature of the latter, the multiplicity of their elements, 
 account for their tendency to alteration. Minerals are not subject to 
 change, unless they are acted upon by external causes. Endowed with 
 a vis inertias, they continue in one condition without change. The 
 state of organised bodies is incessantly varying. Their internal parts 
 contain an active laboratory, in which a number of instruments are 
 constantly transforming into their own substance nutritious particles. 
 Besides that tendency to alteration in living animals and vegetables, 
 when deprived of life they become decomposed by a process of fer- 
 mentation which begins in their internal parts, and by which their 
 nature is changed in proportion to the complication of their structure, 
 and the greater number and volatility of their constituent principles. 
 
 All the parts of a living body, whether of an animal or a vegetable, 
 have a natural tendency to a 'common object, the preservation of the 
 individual and of the species : each of the organs, though provided 
 for a peculiar action, concurs in this object; and life in general, or 
 life properly so called, is the result of that series of concurring and 
 harmonic actions. On the contrary, each part of an inorganic mass 
 is independent of the other parts, to which it is united only by the 
 force or affinity of aggregation. When such a part is separated from 
 the rest, it maintains all its characteristic properties, and differs only 
 by its size from the mass to which it no longer belongs. 
 
 Among animals and vegetables, all the individuals of the same 
 class appear to have been formed after the same model ; their parts 
 are equal in number, and resemble each other in colour; their dif- 
 ferences are slight and evanescent. The forms peculiar to organised 
 beings are, therefore, invariably determined ; and when nature departs 
 from them, she never does so to such a degree as in the shapes of 
 minerals. The veins of mines are never precisely alike, as the leaves 
 of vegetables or the limbs of animals. Crystals, formed from similar 
 substances, assume very different shapes, equally distinct and precise. 
 Carbonate of lime, for example, assumes, according to circumstances, 
 the shape of a rhomboid, that of a six-sided regular prism, that of 
 a solid, terminated by twelve scaleni triangles, that of a different 
 dodecahedron with pentagonal faces, &c., as may be seen at large in 
 the writings of Haiiy.
 
 6 CHABACTEKISTICS OF ORGANISED BODIES. 
 
 A powerful inward cause seems to arrange the constituent parts 
 of animal and vegetable bodies by a determinate rule, in such a 
 manner that they shall present a surface more or less completely 
 rounded. Minerals often take their form from external bodies; and 
 when an especial force assigns it to them, as in crystals, their surfaces 
 are flat and angular. When the crystallisation is disturbed, and the 
 molecules of the crystals are driven tumultuously together, the geome- 
 trical form is impaired ; the parts are rounded which would have been 
 terminated by angles, if a slow and tranquil crystallisation had allowed 
 of regular aggregation; and, as M. Haliy has remarked, these waving 
 outlines, these roundings, so frequent in vegetables and plants, where 
 they belong to beauty of form, are, in minerals, indication of defects. 
 True beauty, in these beings, is characterised by the straight line; 
 and it is on good grounds that Rome de Lisle* has said of this sort 
 of line, that it seems to have an especial determination to live mineral 
 kingdom. 
 
 Amongst all the characteristics which distinguish the two great 
 divisions of natural bodies, the most absolute and the most palpable 
 is that which is drawn from the manner of growth and of nourish- 
 ment. Inorganic bodies grow only by accretion, that is, by the 
 accession of new layers to their surface ; whilst the organic, in virtue 
 of its vital powers, receives into intimate combination, and is pene- 
 trated and pervaded by, the substance it assimilates to itself. In 
 animals and plants, nutrition is the effect of an internal mechanism; 
 their growth is a development from within. In minerals, on the 
 contrary, growth cannot claim the name of development : it goes 
 on externally, by successive addition of new layers ; it is the same 
 being, assuming other dimensions, whilst the organic body is renewed 
 in its growth. 
 
 Living bodies spring from a germ, which at first was part of 
 another being, from which it detaches itself for the sake of its own 
 development and growth. From the first, they are already aggregates. 
 Inorganic bodies have no germ : they are made up of distinct parts 
 brought together; they have no.birth; but a multitude of molecules, 
 collecting into one, compose masses of various bulk and figure. 
 
 Organised bodies alone can die ; all have a duration, determined 
 by their own nature; and this duration is not, like that of minerals, 
 proportioned to the bulk and density : for if man has not the life of 
 the oak, whose substance much exceeds his in. density, neither does 
 he equal the life of many animals, such as fishes, whose flesh is of 
 inferior consistence to his own : and he lives longer than the lanre 
 quadrupeds, though his bulk is less. The parts, also, of a living body, 
 
 * Cristallographie, torn. i. p. 04.
 
 CHARACTERISTICS OF ANIMAL BODIES- 7 
 
 are developed and strengthened by exercise : a muscle or an organ, 
 instead of being wasted by repeated action, increases in bulk, whilst 
 friction and use destroy inorganised substances. Spontaneous motion 
 is proper to living bodies, but inorganised matter evinces only commu- 
 nicated movements. 
 
 Finally, inorganic are essentially distinguished from organic bodies 
 by the want of these peculiar powers or properties of living nature ; 
 powers which uphold the equilibrium of the whole system of nature, 
 as I shall explain more at large when I have considered the differences 
 that mark the two divisions of the organic kingdom, vegetables and 
 animals. 
 
 SECT. IV DIFFERENCES BETWEEN VEGETABLES AND 
 ANIMALS. 
 
 These are much fewer, less absolute, and therefore more difficult 
 to establish. There is, in fact, very little difference between a zoophyte 
 and a plant ; and there is a much wider distance in their internal eco- 
 nomy, between man, who stands at the height of the animal scale, and 
 the polypus on its lowest line, than between the polypus and a plant. 
 There lies between organised and inorganic bodies a space, which is 
 not to be filled up by figured stones, nor by lithophytes, nor by 
 crystals, in which some naturalists have thought they saw a beginning 
 of organisation : whilst, at the extremity of the animal chain, are 
 found beings, fixed, like plants, on the spot of their birth, sensitive 
 and contractile, like the sensitive and some other plants, and repro- 
 duced like them from slips. Yet we are able to state some differences 
 sufficiently marked, to assign to the vegetable kind a character of 
 their own, which will not suit the individuals of either of the other 
 kingdoms. 
 
 Their nature, more complex than that of minerals, is less so than 
 that of animals : the proportion of the solids to the liquids is greater 
 than in these last : accordingly they retain, long after death, their 
 form and bulk, only that they grow lighter. The solids are, in man, 
 nearly a sixth of the whole body : his carcass, decomposed by pu- 
 trefaction, remains a little earth, and a light skeleton, when the ground 
 and the air have drawn from it all its juices. A tree, on the contrary, 
 is more than three parts of its substance solid wood. It has been 
 dead for ages ; and yet in our buildings it preserves its form and size, 
 though, by drying, it has lost a little of its weight. 
 
 Their constituent principles, as they are less in number, are also 
 less diffusable. In fact, azote, yhich is predominant in animal 
 substances, is a gaseous and volatile principle ; whilst carbon, the base 
 of vegetable substance, is fixed and solid. This circumstance, added
 
 8 CHARACTERISTICS OF ANIMAL BODIES. 
 
 to the smaller quantity of their liquids, explains the long duration, after 
 death, of vegetable substances. 
 
 But of all the characteristics which have been employed in 
 establishing the limits of animal and vegetable nature, there is one 
 quite sufficient to distinguish these two great classes of beings; but 
 which has not been allowed the weight it deserves. 
 
 The zoophyte, who, fixed in his rocky habitation, cannot change 
 his place, confined to partial movements, which certain plants are 
 possessed of, who, besides, has not that sensitive unity so remarkable 
 in man, and in the animals who nearest resemble him in their 
 organisation ; the zoophyte, whose name indicates an animal plant, is 
 totally separated from all beings of the vegetable kingdom, by the 
 existence of a cavity, in which alimentary digestion is carried on, a 
 cavity, by the surface of which is an absorption, an imbibition, far 
 more active than that which takes place by the external surface of the 
 body. From this shapeless animal, up to man, nutrition is effected by 
 two surfaces, and especially the internal ; whilst in the plant, nutrition, 
 or rather the absorption of nutritive principles, is only by the external 
 surface.* 
 
 Every animal may be considered, in extreme abstraction, as a 
 nutritive tube, open at the extremities;! the whole existence of the 
 polypus seems reduced to the act of nutrition, as its whole substance 
 is employed in the formation of an alimentary tube, of which the soft 
 parietes, extremely sensible and contractile, are busied in appropri- 
 ating to themselves, by a sort of absorption, the substances which 
 are brought into it. From the worm up to man, the alimentary 
 canal is a long tube, open at the extremities; at first only of the 
 length of the body of the animal, not bent at all in passing from the 
 head to the tail, and carried on towards the mouth, and towards the 
 anus, with the external covering of the body; but soon returning upon 
 itself, and stretching out into length far beyond that of the body 
 which contains it. 
 
 It is in the thickness of the parietes of this animated tube, betwixt 
 the mucous membrane that lines it inwardly, and the skin with which 
 this membrane is continuous, that all the organs are placed, which 
 
 * This most prominent characteristic of animal organisation was first pointed 
 out by Boerhaave ; and afterwards insisted on by Dr. Alston of Edinburgh ; and re- 
 cently by Dr. A. T. Thomson, in his excellent work on the Elements of Botany.,/. C. 
 
 j- Lacepede, Histoire Naturelle 4s Poissons, tom. i. There may be brought 
 against this principle, the instance of some zoophytes, such as sponges, &c. ; but 
 do these bodies really belong to the animal kingdom? and should not we be 
 warranted in rejecting them, by the want of the alimentary cavity, the 'essential 
 characteristic of animal existence ?
 
 CHARACTERISTICS OF ANIMAL BODIES. 9 
 
 serve for the transmission and elaboration of fluids, together with the 
 nerves, the muscles, in short, all that serves for the carrying on of life. 
 As we rise from the white-blooded animals to the red and cold- 
 blooded, from these to the warm-blooded, and from these to man, we 
 see a progressive multiplication of the organs that are contained 
 within the thickness of the parietes of the canal : if we follow, on 
 the other hand, the descending scale, we see this structure gradually 
 simplified, till we arrive at last at the polypus, and find in it only the 
 essential part of animal existence. The simplicity of its organisation 
 is such, that it may be turned inside out, and the external be made 
 the internal surface ; the phenomena of nutrition, which are the 
 whole life of the animal, go on, from the close analogy between the 
 two surfaces ; unlike to man and the greater part of animals, in whom 
 the skin and the mucous membranes, though growing into each other, 
 though linked by close sympathies, are far from possessing a complete 
 analogy of structure, or a capacity for the interchange of functions. 
 
 Man, then, and the whole animal kind, carry about within them- 
 selves the supply of their subsistence; and absorption, by an inward 
 surface, is their distinguishing characteristic. It is inaccurate to 
 ascribe to Boerhaave' the comparison of the digestive system of 
 animals to the soil in which plants suck up the juices that feed them, 
 and the chylous vessels to real internal roots. I find the same 
 thought well expressed in the work on humours, which, justly or 
 falsely, bears the name of Hippocrates : Quemadmodum terra arbori- 
 bus, ita animalibus ventriculus. 
 
 The digestive tube, that essential part of every animal, is the part 
 of which the existence and action are the most independent of the 
 concurrence of the other organs, and to which the properties of life 
 seem to adhere, if one may say so, with most force. Haller,* who has 
 made so many and such interesting inquiries into the contractile power 
 of the muscular organs, examining them under the twofold relation 
 of their irritability, as it is more or less lively, or more or less lasting, 
 looks on the heart as the one in which these two conditions are 
 found in the highest combination. He gives the second place to the 
 intestines, the stomach, the bladder, the uterus, and the diaphragm ; 
 and, after these, all the muscles under the command of the will. I 
 had at first admitted, with every other writer, this classification of the 
 contractile parts ; but more than a hundred experiments on living 
 animals have satisfied me that the intestines are always the last part 
 in which the traces of life may be discovered. Whatever may be the 
 sort of death by which they are destroyed, peristaltic motions, undula- 
 tions, are still continued in this canal, while the heart has already 
 
 * Opera Minora. 3 vols. 4to.
 
 tO OF LIFE. 
 
 ceased to beat, and the rest of the body is all an inanimate mass. 
 M. Jurine had already observed on the pulex mbnoculus, that, of all 
 the parts of the body of this little white-blooded animal, the intestines 
 were the last to die.* 
 
 SECT. V OF LIFE.f 
 
 After having thus laid down, between organic bodies and organised 
 living beings, and again between animal and vegetable nature, a line 
 of demarcation that cannot be mistaken, let us endeavour to exalt our- 
 selves to the conception of Life ; and, for accuracy of thought, let us, 
 in some sort, analyse it, by studying it in all the beings of nature that 
 are endowed with it. Jn this study, of which I may be allowed to 
 state, in advance, the results, we shall see life composed at first of a 
 small number of phenomena, simple as the apparatus to which it is 
 given in charge ; but soon extending itself as its organs or instruments 
 are multiplied, and as the whole organic machine becomes more com- 
 plex ; the properties which characterise it and bear witness of its 
 presence, at first obscure, becoming more and more manifest, increasing 
 in number as in development and energy ; the field of existence 
 enlarging, as from the lower beings we re-ascend to man, who, of all, 
 is the most perfect: and observe, that by this time of perfection, it is 
 simply meant that the living beings to which we apply it, possessed of 
 more means, present also more numerous results, and multiply the 
 acts of their existence : for in this wonderful order of the universe 
 every being is perfect in itself, each being is constructed most favour- 
 ably for the purpose it is to fulfil ; and all is equally admirable, in 
 living and animated nature, from the lowest vegetation to the sublimity 
 of thought. 
 
 What does this plant present to us that springs up, and grows, 
 and dies every year ? A being whose existence is limited to the phe- 
 nomena of nutrition and reproduction : a machine constructed of a 
 multitude of vessels, straight or winding capillary tubes, through which 
 the sap is filtrated, and other juices necessary to vegetation ; these 
 vegetable liquors ascend, generally, from the roots, where their mate- 
 rials are taken in, to the summit, where what remains from nutrition is 
 
 * If the intestinal tube be the ultimum moriens, if it be the last organ in 
 which life lingers and goes out, it is to it we ought to direct, in preference, the 
 stimulants that are capable of recalling it in case of asphyxia. After the 
 blowing of pure air into the lungs, the means that ought next to be attended 
 to is the injection of acrid and irritating clysters thrown in with force. The 
 large intestines are connected with the diaphragm by a close sympathy, as is 
 proved by the phenomena of fecal evacuation : the irritation of them is the 
 surest means of accelerating it ; and this irritation is the easier, as the alimentary 
 canal is the last part that is forsaken by life. 
 
 f See APPENDIX, Note A.
 
 OF LIFE. 11 
 
 evaporated by the leaves, and what the plant could not assimilate to 
 itself is thrown off in transudation. Two properties direct the action 
 of this small number of functions : a latent and faint sensibility, in 
 virtue of which each vessel, every part of the plant, is affected in its 
 own way by the fluids with which it is in contact : a contractility as 
 little apparent, though the results prove irrefragably its existence ; a 
 contractility, in virtue of which the vessels, sensible to the impression 
 of liquids, close or dilate themselves, to effect their transmission and 
 elaboration. The organs allotted to reproduction animate, for a 
 moment, this exhibition : more sensible, more irritable, they are 
 visibly in action : the stamina or male organs bow themselves over 
 the female organ, the pistils, shake on the stigma their fertilising dust, 
 then straighten, retire from it, and die with the flower, which is suc- 
 ceeded by the seed or fruit. 
 
 This plant, divided into many parts, which are set in the earth 
 with suitable precautions, is reproduced and multiplied by slips, which 
 proves that these parts are little enough dependent on each other ; 
 that each of them contains the set of organs necessary to life, and can 
 exist alone. The different parts of a plant can live separately, because 
 life in its simpler organs and properties is diffused more equably, more 
 uniformly, than in animals like man, and its phenomena are connected 
 in a less strict and absolute dependence. I myself have witnessed a 
 very curious fact, which confirms what 1 have said.* A vine, trained 
 against the eastern wall of a forge, shot into the building a few 
 branches, These branches, which entered by straight enough passages, 
 
 * Vegetable life compared in its means and in its results to the life of 
 animals, would throw the greatest light on many phenomena which it is still 
 difficult for us to conceive and to explain. The treatment of disease in plants, 
 for which as much would be gained by these inquiries, is almost entirely surgical. 
 When, to make vegetation more fruitful, the gardener prunes a luxuriant branch ; 
 when the peasants of the Cervennes, as M. Chaptal has observed, burn the 
 inside of their chestnut trees to stop the progress of a destructive caries ; when 
 the actual cautery is applied to the really ichorous and foul ulcers of many 
 trees, &c., it is to the organs of inward life (or that which carries on the pro- 
 cess of assimilation), the only life of vegetables, that surgery is applied ; while, 
 on the contrary, in man and animals, it is to the derangement of the external 
 organs that the remedy is directed. I shall conclude this note with an ob- 
 servation on the wounds of plants. Like those of the human body, they are 
 much less dangerous when their surface is smooth than when their edges are 
 hacked, torn, or bruised. Trees felled with the saw will hardly shoot up from 
 the stool, which always furnishes a better growth when an axe has been employed. 
 The saw lacerates the vegetable texture; and its violent and distressing action 
 on the fibres, extending towards the roots, affects, more or less, the organisa- 
 tion. The uneven surface of a tree felled in this manner holds wet, as injurious 
 to the trunk, which it rots, as a too great quantity of pus, which bathes con- 
 stantly the surface of a wound, checks the process of granulation, and resists 
 cicatrisation.
 
 12 OF LIFE. 
 
 were covered with leaves in the middle of the hardest winters ; and 
 this premature but partial vegetation went through all its periods, 
 and was already in flower when the part that remained without was 
 beginning to bud with the spring. 
 
 If we pass from the plant to the polypus, which forms the last link 
 of the animal chain, we find a tube of soft substance, sensible and 
 contractile in all its parts, a life and an organisation at least as simple 
 as that of the plant. The vessels which carry the liquids, the con- 
 tractile fibres, the tracheae which give access to the atmospheric air, 
 are no longer distinctly to be traced in this almost homogeneous sub- 
 stance. There is no organ especially allotted to the reproduction of 
 the kind. Moisture oozes from the internal surface of the tube, softens 
 and digests the aliments which it finds there ; the whole mass draws 
 in nourishment from it ; the tube then spontaneously contracts, and 
 casts out the residue of digestion. The mutual independence of parts 
 is absolute and perfect: cut the creature into many pieces, it is repro- 
 duced in every piece ; for each becomes a new polypus, organised and 
 living, like that to which it originally belonged. These gemmiparous 
 animals enjoy, in a higher degree than plants, the faculties of feeling 
 and of self-motion ; their substance dilates, and lengthens, and con- 
 tracts, according to the impressions they receive. Nevertheless, these 
 spontaneous movements do not suppose, any more than those of the 
 mimosa, the existence of reflection and will ; like those of a muscle 
 detached from the thigh of a frog and exposed to galvanic excitation, 
 they spring from an impression which does not extend beyond the part 
 that feels it, and in which sensibility and contractility are blended and 
 lost in each other. 
 
 From this first degree of the animal scale, let us now ascend to 
 worms. We have no longer a mere animated pulp shaped into an 
 alimentary tube : parcels of contractile or muscular fibres ; a vessel 
 divided by several constrictions into a series of vesicles, which empty 
 themselves into one another by a movement of contraction that begins 
 from the head, or the entrance of the alimentary canal, and proceeds 
 towards the tail, which answers to the anus ; a vessel from which, in 
 all probability, are sent out lateral ramifications ; a spinal marrow* 
 equally knotted, or composed of a chain of ganglions, f stigmas, and 
 trachea, analogous to the respiratory organs of plants, and, in some, 
 ' even gills : all shews clearly an organisation further advanced, and 
 more perfect : sensibility and contractility are more distinct ; the 
 motions are no longer absolutely automatic ; there are some which 
 
 * This class of animals cannot be considered to possess a spinal marrow. The 
 series of ganglions which they exhibit is merely the vertebral ganglia of the 
 sympathetic nerve. 7. C. 
 
 t APPENDIX, Note B.
 
 OF LIFE. 13 
 
 seem to suppose choice. The worm, too, may be divided into many 
 pieces; each will become a separate and perfect worm, a head and 
 tail growing to each ;* but this division has its term, beyond which 
 there is no longer complete regeneration. It cannot, therefore, be 
 pushed so far as in the polypi. The substance of the worm being 
 formed of elements more dissimilar, it may be that too small a portion 
 does not contain all that is necessary to constitute the animal. 
 
 The crustaceous tribes, and among them the lobster, discover a 
 more complex apparatus of organisation. Here you will find distinct 
 muscles, an external articulated skeleton, of which the separate parts 
 are movable upon each other, distinct nerres, a spinal marrow with 
 bulgings, but, above all, a brain 'and a heart. These two organs, 
 though imperfect, assign the animal to an order much above that of 
 worms. The first becomes the seat of a sort of intelligence; and 
 the lobster acts evidently under impulses of will, when, attracted by 
 a smell, it pursues a distant prey, or when it flies a danger discovered 
 to it by its eyes. There are viscera accompanying the intestinal tube, 
 which give out to it liquids that concur in alimentary digestion. Sensi- 
 bility and contractility present each two shades : in fact, the parts of 
 the animal are obedient to the internal stimuli, feel the impression 
 of fluids, and contract to impel them ; on the other hand, by its nerves 
 and locomotive muscles, the lobster places itself in connexion with 
 the objects that surround it. The phenomena of life are linked 
 together by a strict necessity : it is no longer possible to separate 
 the creature into two parts, of which each may continue to live : there 
 are but few parts you may cut off without injury, while you spare the 
 central foci of life. So, if you take off a claw, you observe soon 
 a little granulation, which swells and is developed, and which, soft 
 at first, is soon clothed in a calcareous covering like that which en- 
 closes the rest of its body. This partial regeneration is frequently 
 to be seen. 
 
 If from white-blooded animals we go on to the red and cold- 
 blooded, such as fishes and reptiles, we see this power of reproduction 
 becoming more and more limited, and life more involved in organisa- 
 tion. In fact, if you cut off a part of the body of a fish, the tail 
 of a serpent, or the foot of a frog, the separated parts are either 
 not supplied at all, or very imperfectly reproduced. All these crea- 
 tures maintain, with the medium in which they live, relations of more 
 strict dependence. Gills in these, lungs in others, are added to a 
 heart, nor are less essential to life. However, the action of these chief 
 organs is not so frequent, nor of momentary necessity for the con- 
 
 * This may be observed in several of the intestinal worms. It ought to be kept 
 in recollection during our endeavours to remove them from the body.
 
 14 OF LIFE. 
 
 tinuance of life. The serpent passes long winters, torpid with cold, 
 in holes where he has no air, without breathing, without any motion 
 of life, and in all appearance dead. These creatures, like all reptiles, 
 are able to breathe only at long intervals, and to suspend, for a time, 
 the admission of air, without risking their existence. Here, the vital 
 powers are distinct and strong, and differ from those of the more 
 perfect animals, and of man, by very slight shades: the heart and 
 the vessels of the fish feel and act with'in him without his consciousness. 
 Further, he has senses, nerves, and a brain, from which he has in- 
 timation of whatever can affect him ; muscles and hard parts, by the 
 action of which he moves and changes his place, adapting himself to 
 the relations that subsist between the substances around him and his 
 own peculiar mode of existence. 
 
 We are come, at last, to the red and warm-blooded animals, at 
 the head of which are the mammiferse and man. They are entirely 
 alike, save some slight differences in the less essential organs? There 
 is none that has not the vertebral column, four limbs, a brain which 
 fills exactly the cavity of the skull, a spinal marrow, nerves of two 
 sorts, five senses, muscles partly obedient to the will, partly inde- 
 pendent in their action : add to these, a long digestive tube coiled 
 upon itself, furnished at its mouth with agents of saliva and masti- 
 cation ; vessels and lymphatic glands, arteries and veins, a heart with 
 two auricles and two ventricles, lobular lungs, which must act in- 
 cessantly in impregnating the blood that passes through them with 
 the vital part of the atmosphere,* if which fail, life is suspended 
 or gone. None of their organs live but while they partake in the 
 general action of the system, and while they are under the influence 
 of the heart : all die, irrecoverably, when they are parted from the 
 body of the animal, and are in no way replaced, whatever some phy- 
 siologists may have said on pretended regeneration of the nerves and 
 some other parts. 
 
 Every thing that is important to life is to be found in these 
 animals ; and as the most essential organs are within, and concealed 
 in deep cavities, a celebrated naturalist was correc.t in saying, that 
 all animals are essentially the same, and that their differences are 
 in their external parts, and chiefly to be observed in their coverings 
 and in their extremities. 
 
 The human body, consisting of a collection of liquids and solids, 
 contains of the former about five-sixths of its weight. This proportion 
 of the liquids to the solids, may, at first sight, appear to you beyond 
 the truth : but consider the excessive decrease of size of a dried limb ; 
 the gluteus maximus, for example, becomes, by drying, no thicker 
 
 * See Chapter on Respiration.
 
 ELEMENTS OF ANIMAL BODIES. 15 
 
 lhan a sheet of paper. The liquids, which constitute the greatest 
 weight of the body, exist before the solids ; for the embryo, which 
 is at first in a gelatinous state, may be considered as fluid : besides, 
 it is from a liquid that all the organs receive their nourishment and 
 repair their wastes. The solids, formed from the liquids, return to 
 their former state, when, having for a sufficient length of time formed 
 a part of the animal, they become decomposed by the nutritive process. 
 Even from this slight view of the subject, fluidity is seen to be essential 
 to living matter, since the solids are uniformly formed from the fluids, 
 and eventually return to their former state. Solidity is, then,, only 
 a transient condition and an accidental state of organised and living 
 matter; and this circumstance affords to the humoral pathologists 
 ample opportunities of embarrassing their opponents with many ob- 
 jections not easily answered. 
 
 The simplest living bodies, as the infusoria, polypi, &c. are only 
 found in water ; so that we may justly say, with M. Lamarck, that 
 it is exclusively in this fluid that the animal kingdom has derived 
 its origin. Water forms the principal part, and the principal vehicle 
 of all the animal fluids; it contains saline substances in a state of 
 solution, and even animal matter itself is found in it fluid, and that 
 in three different conditions, under the form of gelatine, of albumine, 
 or fibrine. The first of these substances, solidified, forms the basis 
 of all the organs of a white colour, to which the ancients gave the 
 name of spermatic organs, such as the tendons, the aponeurosis, the 
 cellular tissue, and the membranes. Albumine exists in abundance 
 in almost all the humours : the fibrine of the blood is the cement 
 which is employed in repairing the waste of a system of organs, which, 
 in point of bulk, hold the first rank among the constituent parts of the 
 human body I mean the muscular system. The chemists suspect, 
 and not without reason, that the animal matter passes successively 
 through the different states of gelatine, albumine, and fibrine ; that 
 these different changes depend upon the progressive animalisation of 
 the animal matter, which is at first gelatinous, a hydro-carbonous 
 oxyde, containing no azote, and acidifiable by fermentation, becomes 
 more closely combined with oxygen, takes up azote, so as to become 
 albumen, capable of putrefaction ; and finally is converted into fibrine 
 by a super-addition of the same principles. 
 
 The solid parts are formed into different systems, to each of which 
 is intrusted the exercise of a function of a certain degree of import- 
 ance. Limiting the term organic apparatus, or system, to a combina- 
 tion of parts which concur in the same uses, we reckon ten, viz. the 
 digestive apparatus, consisting essentially of the canal which extends 
 from the mouth to the anus ; the absorbent, or lymphatic system 
 whic.h is formed of the vessels or glands of that name ; the circulatory
 
 10 ARRANGEMENT OF JFHE AXIMAL TF.XTU11KS. 
 
 system, which consists of an union of the heart, the veins, the arteries, 
 and the capillary vessels ; the respiratory, or pulmonary system ; the 
 glandular, or secretory system ; the sensitive system, including the 
 organs of sense, the brain, and spinal marrow; the muscular system, 
 or that of motion, including not only the muscles, but their tendons 
 and aponeuroses; the osseous system, including the appendages of 
 the bones, the cartilages, the ligaments, and the synovial capsules; 
 the vocal system ; and the sexual or generative system, different in 
 the two sexes. Each of these organic systems contains in its struc- 
 ture several simple tissues, or " similar parts," as the ancients called 
 them. These tissues, in man, may be enumerated as follow : cellular 
 tissue, nervous tissue, muscular tissue, besides that horny substance 
 which constitutes the basis of the epidermis, the nails, and the hair.* 
 
 These four substances may be considered as real organic elements, 
 since, with our means of analysis, we never can succeed in converting 
 any one of these substances into another. The cerebral pulp is not 
 convertible into a horny substance, into cellular substance, or into mus- 
 cular fibre ; neither can any one of these tissues ever be converted into 
 cerebral pulp. The bones, the cartilages, the ligaments, the tendons, 
 the aponeuroses, may, by long maceration, be converted into cellular 
 substance. Muscular fibres are not subject to that alteration, nor is 
 the nervous or cerebral pulp : the horny substance also resists that 
 
 * One of the oldest divisions of the primary textures of the body, and one 
 which nearly coincides with that given by the author, acknowledges three tissues 
 only, viz. the cellular, nervous, and muscular. This arrangement has been adopted 
 by the majority of physiologists since the time of Haller. It may be shewn, that 
 all the textures and organs of the body result either from the various distribution 
 of these primary tissues, or from the cellular only, in consequence of a greater 
 condensation of its substance, or approximation of the molecules of matter entering 
 into its constitution, and owing to a deposition of earthy substance between its in- 
 terstices, as in the-bohei. It may, however, be a matter of doubt, whether the 
 muscular texture does not arise from the union of the cellular tissue with the 
 nervous substance ; the former combining with the fibril* of the organic or 
 ganglial nerves to form the muscular fibres generally, whether involuntary or 
 voluntary ; while the latter class of muscular fibres derive their peculiar characters 
 and functions from the accession of the fibrilae of voluntary nerves to the ganglial 
 and cellular textures. If this position be allowed, the involuntary muscular fibres 
 will appear to result from the combination of the cellular substance with the ganglial 
 nerves only ; the voluntary, from the union of the cellular with both the ganglial 
 and cerebral matters composing the extremities of their ramifications, the muscular 
 fibre varying its character and phenomena according as more or less of either kind 
 of nervous substance enters into its composition. An intimate view of the mode of 
 distribution which characterises both classes of nerves, as well as various other 
 considerations, support this opinion, which is calculated to form the basis of 
 plausible explanations of many of the most important appearances and functions of 
 the different kinds of muscular texture J. C.
 
 ARRANGEMENT OF THE ANIMAL TEXTURES. 
 
 17 
 
 change. Every thing, therefore, leads us to acknowledge these four 
 constituent principles in our organs. 
 
 The primitive or simple tissues, variously modified and combined 
 in different quantities and in various proportions, constitute the sub- 
 stance of our organs. Their number is much more considerable, 
 according to Bichat, whose happiest conception was this analysis of 
 the human organisation. This physiologist reckoned in the human 
 economy no fewer than twenty-one general or generating tissues.* But 
 it is evident that this analysis is carried too far ; that the tissues of 
 which the skin and the hair are formed are exactly of the same nature, 
 are analogous in their properties, and are nourished in a similar manner ; 
 that the cellular tissue is the common basis of the osseous, cartila- 
 ginous, mucous, serous, synovial, dermoid, &c. 
 
 It must be confessed, that this separate consideration of each 
 organic tissue has furnished him with new ideas, ingenious analogies, 
 and useful results ; and that his " Anatomic Generate," in which those 
 researches are contained, is his chief title to glory. That glory would 
 be complete, if, in that book, and yet more in his other works, he had 
 done his predecessors, as well as his contemporaries, the justice they 
 had a right to expect from him. 
 
 The simple or elementary fibre, about which so much has been 
 written, may be considered as the philosopher's stone of physiologists-! 
 
 * The following classification of the primary and compound textures nearly 
 coincides with that recommended by Dupuytren and Magendie : 
 1. Cellular. 
 
 * 
 
 (Arterial, 
 
 4. Vascular < Venous, 
 
 ( Lymphatic. 
 
 5. Osseous. 
 
 ( Fibrous, 
 
 6. Fibrous -| Fibro-Cartil 
 
 ( Dermoid. 
 
 7. Erectile. 
 
 8. Mucous. 
 
 9. Serous. 
 
 10. Synovial. 
 
 11. Glandular. 
 
 12. Epidermous, or Corneous. 7. C. 
 
 \ Almost every physiologist who has written on animal 
 proposed a new arrangement of the primary textures. We will only take notice of 
 the two following: WAI. T HER considered the different organs and compound 
 textures to result from the cellular or membranous, the vascular or fibrous, and 
 from the nervous. J. F. MECKEL founds his classification of organic substances 
 on microscopic researches. He is of opinion that the solids and fluids of the human 
 
 C
 
 18 ARRANGEMENT OF THE ANIMAL TEXTURES. 
 
 In vain has Haller himself, in his pursuit of his chimera, told us, that 
 the elementary fibre is to the physiologist what the line is to the 
 geometer, and that, as all figures are formed from the latter, so are all 
 the tissues formed from this fibre. Fibra enim physiologo id est quod 
 lineageometrcE, ex qud nempt figurce omncs oriuntur. The mathematical 
 line is imaginary, and a mere abstraction of the mind ; while the 
 elementary fibre is allowed a material or physical existence. Nothing, 
 therefore, can make us admit the existence of a simple, elementary, 
 or primitive fibre, since our senses shew us, in the human organisation, 
 four very distinct materials. 
 
 Each of these four substances, of which our solids are formed, and 
 the principles of which, as we have seen above, are contained in the 
 fluids, may be chemically resolved into azote, oxygen, hydrogen, and 
 carbon. To these four chemical elements of our textures may be added 
 phosphorus, sulphur, lime, iron, and some other substances which are 
 not so constantly present in the fluids and solids as those enumerated. 
 Shall we also mention, as constituents of the animal economy, certain 
 substances which are not subjected to the laws which ponderable bodies 
 evince, and which are made known to us chiefly by their effects, such 
 as caloric, light, and electricity, of which magnetism and galvanism are 
 the effects ? 
 
 Among the organs, whether single or combined in systems, which 
 enter into the human organisation, there are some whose action is 
 so essential to life, that with the cessation of that action life at once 
 becomes extinct. These primary systems, whose action regulates that 
 of all secondary systems, are as numerous in man as in the other warm- 
 blooded animals. None of them can act unless the heart sends into 
 the brain a certain quantity of blood, vivified by the contact of atmo- 
 spherical air in the pulmonary tissue. Every serious wound of the 
 brain or heart, every lasting interruption to the access of blood into 
 the former of these organs, is invariably attended with death. The 
 oxydation of the blood, and its distribution into all the organs, is con- 
 sequently the principal phenomenon on which the life of man and of 
 the most perfect beings depends. 
 
 SECT. VI OF THE VITAL PROPERTIES; SENSIBILITY 
 
 AND CONTRACTILITY." 
 
 By sensibility is meant that faculty of living organs which renders 
 them capable of receiving, from the contact of other bodies, an im- 
 
 body can be reduced to lu-o elementary substances, the one formed by globules, the 
 other by a coagulable matter which, either alone or united to the former, con- 
 stitutes the living fluids, if it be in the liquid state, and gives rise to the solid tissues, 
 when it assumes the concrete form. See APPENDIX, Note C, for a more detailed 
 account of the opinion of this eminent anatomist. J. C. 
 * See APPENDIX, Note D.
 
 OF THE VITAL PROPERTIES. 19 
 
 pression, stronger or fainter, that alters the order of their motions, 
 increases or diminishes their activity, suspends or directs them. Con- 
 tractility is that other property by which parts excited, that is, in which 
 sensibility has been called into action, contract or dilate ; in a word, 
 act and execute motions. In the same manner, as we have not always 
 a consciousness of the impressions received 'by our organs, and as, for 
 example, no sensation informs us of the stimulating impression by 
 which the blood calls the heart into action ; so it is by reflection only 
 that we are induced to admit the existence of certain motions ; of those, 
 for instance, by which the humours, when they have reached the 
 smallest vessels, become incorporated into the tissue of our organs.* 
 These motions, to make use of an ingenious comparison, resemble those 
 of the hour-hand compared with the second-hand of a watch. The 
 hour-hand appears motionless, and yet in twelve hours it describes the 
 whole circumference of the dial-plate, round which the other hand 
 moves in one minute, with a motion that is visible. 
 
 In considering life through the great series of beings that possess 
 it, we have seen that, those in which it is most limited, or rather, 
 in which it consists of the least number of actions and phenomena, 
 vegetables, for instance, and animals like the polypus, which have 
 no brain, no distinct nervous system, are at once endowed with 
 sensibility and contractility in all their parts. All living beings, all 
 the organs which enter into their composition, are impregnated, if 
 we may be allowed the expression, with these two faculties necessarily 
 co-existing, and which shew themselves by internal and nutritive 
 motions, obscure, indeed, and to be distinguished only by their effects. 
 These two faculties appear to exist in the degree absolutely required 
 for enabling the fluids that pervade all the parts of a living body to 
 induce the action by which these parts are to assimilate such fluids. 
 It is clear that the two properties of feeling and of motion are indis- 
 pensable to all parts of the body. They are properties universally dif- 
 fused through organised and living matter ; but they exist without 
 possessing any peculiar organ or instrument of action. Were it not 
 for these two faculties, how would the different parts act on the blood, 
 or on the fluid which supplies its place, so as to obtain from it the 
 materials subservient to nutrition, and the different secretions? These 
 faculties are therefore given to every thing that has life to animals, 
 to vegetables, to man in his waking hours, or in his most profound 
 sleep, to the foetus, to the child that is born, to the organs of the 
 assimilating functions, and to those which connect us with surrounding 
 
 * If the suggestions offered in the note at p. 16, respecting the constitution of 
 the different kinds of muscular fibres, were adopted, the explanation of the pro- 
 perties, sensibility and contractility, and the relations which they hold with the 
 circle of"dtal functions, would be more apparent and better understood. -/. C.
 
 20 OF SENSIBILITY. 
 
 beings. Both these faculties, obscure and inseparable, preside over 
 the circulation of the blood, of the fluids, and, in short, over all the 
 phenomena of nutrition. 
 
 Though this kind of sensibility is always latent or concealed, it is 
 otherwise with regard to contractility, which may be sensible or other- 
 wise. The bone, which takes up the phosphate of lime, to which it 
 owes its solidity, exerts that action without our being aware of its 
 taking place, except by its effect ; but the heart which feels the pre- 
 sence of the blood, without any consciousness on pur part of such 
 sensation, exerts motions that are easily perceptible, but over which we 
 have no control, either to suspend or accelerate them. 
 
 Vital properties in so weak a degree would not have been sufficient 
 to the existence of man, and of the animals which resemble him, obliged 
 to keep up multifarious intercourse with every thing that surrounds 
 them ; thus they enjoy a very superior kind of sensibility, by means of 
 which the impressions which affect some of their organs are perceived, 
 judged, and compared. This mode of sensibility might be more pro- 
 perly called perceptibility, or the faculty of accounting to oneself for 
 the emotions which are experienced. It requires a centre to which 
 the impressions may be referred, and therefore it exists only in the 
 animals which, like man, have a brain, or some organ in its stead ; so 
 that the zoophytes and vegetables wanting that organ are equally desti- 
 tute of this faculty. The polypi, and some plants, as the sensitive, 
 perform, nevertheless, certain spontaneous motions, which seem to 
 indicate the existence of volition, and consequently of perceptibility. 
 But these motions are the result of an impression which does not 
 extend beyond the part in which it is experienced, and in which sensi- 
 bility and contractility are blended. 
 
 The almost latent sensibility of certain parts of the body cannot be 
 absolutely compared to that of vegetables, since those organs, whose 
 sensibility is so imperfect, manifest in disease a percipient sensibility, 
 which shews itself by acute pain ; and it is even sufficient to change the 
 stimulus to which they are accustomed to determine the occurrence of 
 this phenomenon. Thus the stomach, on the parietes of which the food 
 does not in health produce any perceptible impression, becomes the 
 seat of very distinct sensation, and of dreadful pain, when a small quan- 
 tity of poisonous matter is introduced into it. In like manner, we are 
 not conscious of the impressions excited in the parietes of the bladder 
 or rectum by the collection of urine or feecal substances, except when 
 their contents have become sufficiently irritating by their presence to 
 excite in a certain degree those irritable and sensient cavities, and to 
 transform their obscure into a very distinct sensibility. Is there not 
 reason to suspect, that our unconsciousness in health of the impressions 
 made on our organs by the fluids which they contain, depends on our
 
 OF SENSIBILITY AND CONTRACTILITY. 21 
 
 being accustomed to the sensations which they incessantly excite ? so 
 that there remains but a confused perception, which in time disap- 
 pears ; and may we not, under that point of view, compare all these 
 organs to those of sight, hearing, smelling, tasting, and touching, that 
 are no longer irritable by stimulants, to which they have long been 
 habituated ? 
 
 Two systems of organs, very different in their uses and in their 
 qualities, enter into the composition of the human body ; they are as 
 two living and united machines, the one, formed by the organs of 
 sense, the nerves, the brain, the muscles, and the bones, serves, to main- 
 tain its connexion with external objects ; the other, destined to internal 
 life, consists in the digestive tube, and the organs of absorption, circu- 
 lation, respiration, and secretion. The organs of generation in the 
 two sexes form a separate class, which, as far as relates to the vital 
 properties, partakes of the nature of the other two. 
 
 By the organs of sense, and the nerves which form a communica- 
 tion between these organs and the brain, we are enabled to perceive, 
 or to feel, the impressions made on us by external objects : the brain, 
 the true seat of that relative sensibility, which might very justly be 
 termed perceptibility, or the perceptive power (Pott), when excited by 
 these impressions, is able to irradiate into the muscles the principle of 
 motion, and to induce the exertion of their contractility. This pro- 
 perty, which is under the direction of the will, manifests itself by the 
 sudden decurtation of a muscle, which swells, hardens, and determines 
 the motion of those parts of the skeleton to which it is attached. The- 
 nerves and the brain are essentially the organs of these two properties ; 
 a division of the former is attended with a loss of sentiment and volun- 
 tary motion in the parts to which they are distributed. The other kind 
 of sensibility is, on the contrary, quite independent of the presence of 
 nerves; it exists in all organs, although all do not receive nervous 
 filaments. It might even be asserted, that the cerebral nerves are 
 not at all essential to the life of nutrition; the bones, the arteries, the 
 cartilages, and several other tissues, in which no nerves are seen to 
 enter, are nourished equally well with the organs in which they exist in 
 considerable number ; the muscles themselves will carry on their own 
 internal economy, notwithstanding the division of their nerves ; only, 
 deprived of those means of communication with the brain, they can no 
 longer receive from it the principle of voluntary contraction ; instead of 
 that sudden, energetic, and lasting decurtation, which the will deter- 
 mines in them, they become merely capable of those quiverings called 
 palpitations. 
 
 The anatomist who studies the nerves with a view to ascertain 
 their termination, finds them all arising from the brain and spinal 
 marrow, and proceeding, by a longer or shorter course, to the organs
 
 22 OF SENSIBILITY AND CONTRACTILITY. 
 
 of motion or of sensation : let him take his scalpel and dissect one of 
 our limbs, the thigh, for instance; he will see the cords parting into 
 numerous threads, most of which disappear in the thickness of the 
 muscles; whilst others, after creeping for a time about the cellular 
 tissue, which joins the skin to the aponeurosis, end on the inward 
 surface of the skin, of which they compose the texture, and expand 
 into sentient papillse on its surface. The bones, the cartilages, the 
 ligaments, the arteries, and the veins, all those parts whose action is 
 not under the control of the will, are without them.* Nevertheless, 
 all those parts which, in their natural state, send no perceptible 
 impressions to the brain, which, when once insulated, may be tied and 
 cut, without any sign of pain from the animal, and whose action the 
 will does not control, are yet endued with a sensibility and a con- 
 tractility, which enable them, after their own manner, to feel and to 
 act, to recognise in the fluids that moisten them what is suited to 
 their nourishment, and to separate that recrementitious part which 
 has suitably affected their particular mode of sensibility. f 
 
 In confining our attention, then, to the consideration of a single 
 limb, we may easily satisfy ourselves of the existence of two modes of 
 feeling, as of two sorts of motion; a sensibility, in virtue. of which 
 certain parts can send up to the brain the impressions they receive, to 
 be there objects of consciousness ; and another sensibility belonging to 
 all organs, without exception, and all that some of them possess, 
 which is sufficient for the exercise of the functions of nutrition, and by 
 means. of which they are evolved, and are kept up in their natural 
 state; two kinds of contractility, appropriated to the two different 
 kinds of sensibility : the one, in virtue of which the muscles, obedient 
 to the will, exercise the contractions which it determines ; the other, 
 independent of the will, manifests itself by actions, of which we have 
 no intimation, any more than of the impressions by which they are 
 determined. 
 
 The distinction being fairly laid down between sensibility and con- 
 tractility, it is easy to understand the origin of the endless disputes of 
 
 * Are destitute, or at least nearly so, of voluntary nerves. J. C. 
 
 f All these parts may be considered to possess ganglial nerves; for as these 
 nerves may be demonstrated on the more considerable trunks of arteries, even in 
 the extremities, they may be supposed to accompany these vessels to their most 
 minute ramifications and extremities, and to bestow on them those manifestations 
 which these parts of the vascular system evince. Such, then, being the con- 
 stitution and connexion of the arterial and capillary vessels, no texture which 
 possesses these vessels can be considered to be destitute of this class of nerves. 
 Those nerves that belong to the other class, the cerebro-spinal, may be inferred to 
 exist in an organ more or less abundantly, or to be entirely absent from it, 
 according to the nature of the phenomena which that organ presents. See the 
 CHAPTERS ON THE CIRCULATION, SENSATION, AND MOTION J. C.
 
 OF SENSIBILITY ANJ) CONTRACTILITY. 23 
 
 Haller and his followers, about the parts of the body, in man and 
 animals, which are endowed with sensibility and irritability.* All the 
 organs to which that learned physiologist has denied these properties, 
 as bones, tendons, membranes, cartilages, and cellular membranes, &c. 
 possess only that latent sensibility, and , that obscure contractility, 
 common to all living beings, <and without which it is impossible to con- 
 ceive life to exist. In a state of health, they are utterly incapable of 
 transmitting to the brain perceptible impressions, and of receiving from 
 it the principle of manifest and sensible motion. It has likewise been 
 a matter of much dispute, whether sensibility and contractility are 
 qualities of nerves, if these parts are their only instruments, and if 
 their destruction is attended with a loss of these two vital properties 
 in the parts to which they are transmitted. We may answer in the 
 affirmative, as far as relates to the sensibility of perception and the 
 voluntary motion which is entirely subservient to it; but that the 
 existence of nerves is not at all necessary to the exercise of the sensi- 
 bility and contractility which are indispensable to the assimilation of 
 nutrition. 
 
 No part of the living body is absolutely insensible, but that sen- 
 sibility of every organ is so modified that it is not affected by the same 
 stimuli. Thus, the eye is insensible to sound, and the ear to light. A 
 solution of tartar emetic causes no disagreeable impression to the con- 
 junctiva; taken into the stomach, it excites convulsive motions; while 
 an acid from which the stomach does not suffer, proves a cause of irri- 
 tation to the conjunctiva, and brings on a violent inflammation of the 
 eye. In the same manner, purgatives pass along the stomach without 
 producing any effect on that viscus, but they stimulate the alimentary 
 canal. Cantharides have a specific action on the bladder, and mercury 
 on the salivary glands. Each part feels, lives, moves, after its own 
 way ; in each, the vital properties appear under such shades and modi- 
 fications, that they* may be looked upon as so many separate members 
 of the same family, concurring in one endeavour, working for a common 
 end, consentientia omnia. (Hipp.) 
 
 The faculty of assigning a cause to the sensations, and that of 
 moving by volition, which man possesses in common with all animals 
 formed with a distinct nervous centre, are essentially bound together. 
 For, suppose a living being, furnished with locomotive organs, but 
 without sensation, placed in the midst of bodies that every moment 
 endanger its existence, without any means of distinguishing them, it 
 
 * If the constitution of the muscular fibre, as formerly alluded to, be considered 
 maturely, the source of irritability, aud its various degrees of intensity, with the re- 
 lation which it holds to sensibility, and the other modes of action which the animal 
 textures evince, will become more apparent J. C.
 
 24 OF SENSIBILITY AND CONTRACTILITY. 
 
 will hasten its own destruction. If perceptibility could, on the other 
 hand, exist independently of motion, how dreadful would be the fate of 
 such sentient beings, similar to the fabulous Hamadryads, who, im- 
 movably fixed in the trees of our forests, received, without any power 
 to shun them, all the blows inflicted on their rustic abode. Dreams 
 place us sometimes in situations which give us a just idea of their con- 
 dition. A certain danger threatens our existence ; an enormous rock 
 seems to detach itself, to roll and precipitate itself on our frail machine ; 
 a frightful monster seems to pursue us, and opens a yawning mouth to 
 ingulf us. We struggle to escape this imaginary danger, to avoid or 
 to repel it; but an irresistible and unknown power, a mighty hand, 
 paralyses our efforts, and keeps us rooted to the spot : it is a situation 
 of horror and despair, and we awaken overwhelmed with the uneasiness 
 which we have suffered. 
 
 As there is no part that does not feel in a manner peculiar to itself, 
 so there is no one that does not act, move, or contract, in a manner 
 peculiar to itself; and the parts which have been found without a power 
 of motion analogous to muscular contractility, have remained in that 
 state of immobility only for want of a stimulus fitted to their peculiar 
 nature. Some physiologists say they have excited a distinct quivering 
 in the mesentery of a frog and of a cat, by touching them after they 
 had been previously moistened with alcohol, or muriatic acid. 
 
 In the operation for sarcocele,* I have often perceived that, while 
 with my left hand I supported the tumour, and with a scalpel in the 
 right divided the spermatic chord, the tunica vaginalis shewed oscilla-^. 
 tory contractions. It visibly contracts in the operation for hydrocele. 
 The injection of an irritating fluid determines evident motions in the 
 tunica vaginalis. The osseous tissue, notwithstanding the phosphate of 
 lime with which it is encrusted, is susceptible of a contraction, whose 
 effects, though slow, are nevertheless undeniable. After teeth have 
 been shed or extracted, the edges of the alveolar processes become 
 thinned from contraction, and the alveolar cavities disappear. These 
 facts appear to me to prove, still better than all the experiments per- 
 formed on living animals (experiments of which, by the by, the results 
 ought not too confidently to be applied to the economy of man), what 
 one should think of the assertions of Haller and his followers, on the 
 
 * The contraction of the membrane, formed by the expansion of the cremaster 
 muscle, has doubtless assisted in rendering more distinct the appearance in question. 
 This effect must be particularly distinct at the moment of dividing the spermatic 
 chord. The contractions of the same muscle corrugate the skin of the scrotum 
 when this part is exposed to cold, and draw up the testicles towards the inguinal 
 rings. The contractility of the skin of the scrotum has but little influence in pro. 
 duciug this effect.
 
 OF SENSIBILITY AND CONTRACTILITY. 25 
 
 insensibility and inirritability of the serous membranes, and of the 
 organs of a structure analogous to theirs. 
 
 We shall, at present, say nothing of the porosity, of the divisibility, 
 of the elasticity, and other properties, which are common to living 
 bodies and inanimate substances. These properties are never possessed 
 in their whole extent and in all their purity, if that expression may be 
 allowed. Their results are always influenced by the vital power, which 
 constantly modifies the effects which seem to depend most immediately 
 upon a physical, chemical, or mechanical cause, or upon any other 
 agent whatsoever. When life no longer is present, the organisation is 
 the source of the physical properties exhibited by our organs, and which 
 may be denominated the properties of the tissues. It is owing to the 
 organisation that a part exhibits the property of elasticity, and retracts 
 and hardens when submitted to the action of fire. The extensibility 
 proceeding from distention, traction, or the application of an analogous 
 force, is dependent upon the organisation, and should not be con- 
 founded with the truly vital extensibility which is so manifest in certain 
 organs, as the penis and the clitoris. When excited, they become 
 turgid and dilated by the afflux of humours ; but that effect does not 
 depend on a peculiar property distinct from sensibility and contractility. 
 These parts dilate, their tissue stretches under the action of these two 
 properties, which would occasion the same phenomenon in all other 
 parts if their structure were similar. 
 
 The same applies to caloricity, or that power inherent in all living 
 beings of maintaining the same degree of heat in varying tempera- 
 tures.* In consequence of which property, the human body preserves 
 its temperature of from thirty to forty degrees (of Reaumur's scale) 
 under the frozen climate of the polar regions, as well as in the burning 
 atmosphere of the torrid zone. It is by the exercise of sensibility and 
 of contractility, that is, by the exercise of the functions over which 
 these vital powers preside, that the body resists the equally destructive 
 influence of excessive heat and cold. 
 
 If one were to admit caloricity as one of the vital properties, be- 
 cause, according to Professor Chaussier, that power of preserving a 
 uniform warmth is a very remarkable phenomenon, one might be led 
 to suppose a distinct cause or a peculiar property to operate in pro- 
 ducing other phenomena of no less importance. 
 
 Barthez and Professor Dumas have fallen into the same error ; the. 
 former, in wishing to establish the existence of a power of permanent 
 situation in the molecules of muscular fibres ; the latter, in adding to 
 
 * See the notes on the subject of animal heat contained in the CHAPTER ON 
 RESPIRATION.
 
 26 OF SENSIBILITY AN!) CONTRACTILITY. 
 
 sensibility and contractility a third property, which he terms the power 
 of vital resistance. Living muscles are torn with much more difficulty 
 than when dead, because the contractility which these organs possess 
 in the highest degree is incessantly tending to preserve the contact of 
 the molecules, the series of which forms the muscular fibre, and even 
 to draw them into closer connexion. This fact, which is brought for- 
 ward as a proof of the existence of a peculiar power, is easily explained 
 on the principle of contractility. 
 
 Organised and living bedies resist putrefaction from the very cir- 
 cumstance of their being endowed with life. The continual motion of 
 the fluids, the re-action of the solids on the fluids, the successive and 
 continual renovation of the latter by the reception of new chyle, their 
 constant purification by means of the secretions through which the 
 products animalised in excess are parted with, such are the causes which 
 prevent the putrefactive action from taking place in bodies endowed 
 with life, notwithstanding the multiplicity and the volatility of their 
 elements. Their preservation is therefore a secondary effect, and de- 
 pending on the exercise of the functions regulated by sensibility and 
 contractility. Nature is distinguished for deriving a multitude of 
 effects from a very small-number of causes; it, therefore, shews a very 
 imperfect acquaintance with her laws, to assign a separate cause to 
 each fact. 
 
 The separation of the chyle which takes place in the duodenum, 
 from the admixture of the. bile with the alimentary substance, the 
 vivification of the blood by respiration, the secretion of the fluids in 
 the conglobate glands, nutrition in the organs, are so many acts of 
 the living economy to which one might feel disposed to assign distinct 
 causes ; but these chemico-vital processes are so subordinate to sensi- 
 bility and contractility, that they are met with only in organs endowed 
 with these two properties, and they take place in a degree more or less 
 perfect according to the condition of these properties in the organs in 
 which they occur. 
 
 We have stated that there exist two great modifications of sensi- 
 bility and contractility ; that sensibility is divided into percipient 
 sensibility and latent sensibility; that contractility is at times volun- 
 tary, at others involuntary, and that the latter may be perceivable or 
 insensible.
 
 OF SENSIBILITY AND CONTRACTILITY. 
 
 27 
 
 SENSIBILITY. 
 
 CONTRACTILITY. - 
 
 Perceiving. (Cerebral, nervous, animal sen- 
 sibility, perceptibility.) 
 
 With consciousness of impressions, or percepti- 
 bility ; it requires a peculiar apparatus. 
 
 Latent. (Nutritive, organic sensibility.) 
 
 Without consciousness of impressions, or ge- 
 neral sensibility, common to every thing 
 that has life ; it has no peculiar organ, and 
 is found universally diffused in living parts, 
 animal or vegetable.* 
 
 Voluntary and sentient, subordinate to per- 
 ceptibility. 
 
 Involuntary and insensible, corresponding to 
 latent sensibility. Tonicity. 
 
 Involuntary and sentient. 
 
 The cause of this last modification of contractility appears to depend 
 on the peculiar organisation of the system of the great sympathetic 
 nerves. From these nerves, the heart, the digestive canal, &c. seem to 
 receive the power of exerting sensible contraction ; an effect produced 
 by the direct application of a stimulus, and over which volition has no 
 control, as will be stated in speaking of those nerves. 
 
 Sensibility and contractility offer a vast number of differences, the 
 principal of which depend on the age, the sex, the regimen, the cli- 
 mate, the state of waking or of sleep, of health or of sickness, on 
 the relative development of the lymphatic, cellular, or adipose systems, 
 and on the proportions which exist between the nervous and muscular 
 systems. 
 
 In the first place, the principle of sensibility and of contractility 
 may in its action be likened to a fluid flowing from any source what- 
 soever, which is consumed, repaired, and drained by use, re-supplied, 
 or exhausted, equally distributed, or occasionally concentrated on 
 certain organs. 
 
 Secondly. Sensibility, like contractility, is very considerable at 
 the instant of birth, and seems to diminish more or less rapidly till 
 death. 
 
 Thirdly. The liveliness and frequency of impressions wear it out 
 very early. It, in a manner, repairs itself, that is, recovers its original 
 delicacy, when the sentient organs have been long at rest. Thus, an 
 epicure, whose taste has grown dull with high living, will recover all its 
 accuracy, if, during several months, instead of spiced ragouts and 
 spirituous liquors, he lives on dry bread and plain water. In like 
 
 Sec Note at page 24.
 
 OF SENSIBILITY AND CONTRACTILITY. 
 
 manner, contractility becomes exhausted in the muscles which are too 
 long employed, and it is recovered during the repose of sleep. 
 
 Fourthly. The following is an instance of the manner in which 
 sensibility becomes concentrated in one organ, and appears to forsake 
 the others : when the venereal excitement is in its highest degree, animals 
 under its influence receive blows and stings without pain. Domestic 
 animals in that condition are often ill treated, without appearing to feel 
 what is done to them. If the hind legs of the toad are cut off, at the 
 time that he is holding the female firmly embraced, and is pouring his 
 prolific seminal fluid on the ova which are issuing at her anus, he does 
 not lose his hold, he seems insensible to every other sensation ; as a 
 man who is taken up with one thought, and absorbed in reflection, is 
 scarcely diverted from it by any means that can be employed. When, 
 during the influence of satyriasis, the vital power is carried to excess 
 in the penis, patients have been known (as we are told by Aetius) 
 to cut off both their testicles, without suffering the pain usually 
 attending so severe an operation. It is by this law of sensibility that 
 we are to explain the observation of Hippocrates, that two parts of 
 the body cannot be in pain at the same time. If two pains come 
 on at once, the more violent prevents the slighter from being felt. 
 Duobus doloribus, simul orientibus, non eodem in loco, vehementior 
 obscurat alterum. In cases of scrofulous swellings, the parts are ob- 
 served to inflame, to become painful, and suppuration occurs but 
 rarely in every part at once, if the case is serious and attended with 
 acute pain. The germ of a disease, or of a slighter affection, may 
 sometimes remain dormant under a greater pain. I was once over- 
 turned in a carriage, from the awkwardness of the coachman, the 
 windows were broken, and my wrists sprained. The right wrist, which 
 had suffered most, swelled first ; I employed the proper treatment, and 
 when, at the end of a week, the swelling and pain had almost com- 
 pletely ceased, and the right hand was beginning to recover its supple- 
 ness and flexibility, the left wrist swelled, and, in its turn, became 
 pained ; two complaints, if they may be called such, appeared in suc- 
 cession, and separately went through their regular course.* 
 
 The perfection of one sense is never obtained but at the expense of 
 another ; the blind, who bestow more attention on the sensations com- 
 municated by the sense of touch and of hearing, often astonish us by 
 the delicacy of these organs ; so that, as has been observed, those who, 
 to improve the human voice, have dared to mutilate their fellow- 
 creatures, by depriving them of the organs of generation, might have 
 
 John Hunter maintains, from theory, the position that no two different 
 fevers can take place at the same time in the constitution ; but that if the two 
 causes of disease exist together, the diseases themselves must be vicarious. And he 
 verifies his reasonings from experience.
 
 OF SENSIBILITY AND CONTRACTILITY. 29 
 
 bethought themselves of putting out their eyes, to render them more 
 sensible to the sweet impressions of harmony. 
 
 Fifthly. During sound sleep, the exercise of the percipient faculty, 
 and that of voluntary contractility, are entirely suspended. In that 
 state, it seems as if some covering were thrown over the sentient ex- 
 tremities. We know how hard the hearing becomes, how dull the 
 senses of smell and of taste, how dim the sight, a cloud spreading before 
 the eyes, the moment we are fallen asleep. Vir quidam, exquisitissimd 
 sensibilitate prceditus, semiconsopitus coibat ; huic, ut si velamento levi 
 glans obductusfuisset, sensus voluptatis referebatur. 
 
 Sixthly. Sensibility is more lively, and more easily excited, in the 
 inhabitants of warm climates than in those of northern regions. What 
 a prodigious difference there is in that respect between the native of 
 Germany and of the southern provinces of France. Travellers tell us, 
 that there are in the neighbourhood of the poles natives so little en- 
 dowed with sensibility, that they feel no pain from the deepest wounds. 
 The inhabitants of the coast of North America, if we may believe the 
 testimony of Dixon and Vancouver, thrust sharp nails and pieces of 
 glass into the soles of their feet without feeling the slightest uneasiness. 
 On the contrary, the slightest prick from a thorn, for instance, in the 
 foot, is in the strongest African frequently followed by convulsions and 
 locked jaw. The impression of the air is alone sufficient to produce 
 the same accident in the negro children in the colonies, the greater 
 number of whom die of locked jaw a few days after birth. 
 
 Montesquieu* very justly observed this difference which exists in 
 the sensibility of the southern and northern nations, and he says of the 
 latter, that " if you would tickle, you must flay them." Now, as the 
 imagination is always proportioned to the sensibility, all the arts that 
 are cultivated and brought to perfection only by the exercise of that 
 faculty, will flourish with difficulty near the icy polar regions, unless 
 the powerful influence of climate be counteracted by we. 11 -directed 
 moral and physical causes. 
 
 Man is of all beings the one that most powerfully resists the in^ 
 fluence of external causes ; and although the influence of climate is 
 
 * This philosopher has borrowed from the father of physic one of his most bril- 
 liant and paradoxical opinions. In his conception, warm climates are the seats of 
 despotism, and the cold, the seat of liberty. This error is completely refuted in thfi 
 profound and philosophical work of Volney on Egypt and Syria. He shews that 
 what Montesquieu has said of cold climates applies to mountainous regions, while a 
 champaign is more favourable to the establishment of tyranny. Hippocrates had 
 said of the Asiatics, that their being less warlike than the Europeans depended on 
 the difference of climate, and likewise on the despotic form of their government. 
 And he observes, that men who do not enjoy their natural rights, but whose affec- 
 tions are controlled by masters, cannot feel the bold passion of war See Chap. XI. 
 on the Varieties of the Human Species.
 
 30 OF SENSIBILITY AND CONTRACTILITY. 
 
 sufficient to modify his external appearance, so as to lead to a division 
 of the species into several distinct varieties or kinds, this superficial 
 impression is very different from the great alterations to which other 
 beings are exposed from the mere change of climate. Man is every 
 where indigenous, and exists in all climates ; while the plants and 
 animals of' the equator languish and die when conveyed to the polar 
 regions. From the flexibility of his nature, man enjoys the power of 
 adapting himself to the most opposite situations, of establishing be- 
 tween them and himself relations compatible with the preservation of 
 life. Nevertheless, it is not without difficulty that man undergoes 
 these changes, and accustoms himself to new impressions. The peri- 
 odical return of the seasons determines that of certain derangements to 
 which the animal economy is subject. The same diseases manifest 
 themselves under the influence of the same temperature, and, to use an 
 ingenious comparison, resemble those birds of passage which visit us at 
 stated seasons of the year. Thus, hemorrhages and eruptive affections 
 come on with the return of the spring ; summer comes attended by 
 bilious fevers; autumn brings on a return of dysenteric affections; and 
 winter abounds in inflammations of the lungs and other parts. The 
 influence of climate on the human body does not shew itself merely in 
 occasioning epidemic diseases, the consideration of which leads to the 
 establishing what physicians call medical constitutions : this influence 
 operates on man in health, as well as in sickness ; and to say nothing 
 of the alterations which our moral nature experiences from the ten- 
 dency to love, rendered more impetuous with the return of spring, or of 
 the melancholy to which nervous people are often subject towards the 
 end of autumn, when the trees are shedding their leaves, the increase of 
 growth is particularly remarkable at the time of the first growth of 
 plants, as was observed again and again by a friend of mine, physician 
 to a large seminary. 
 
 Seventhly. Sensibility is greater in women and children, their 
 nerves* are likewise larger and softer, in proportion to the other parts 
 of the body. In general, the principle of sensibility seems to decrease 
 in proportion as it has contributed to the development of the acts of 
 life ; and the power of being impressed by external objects diminishes 
 gradually with age, so that there is a period ofdecrepid old age at 
 which death appears a necessary consequence of the complete ex- 
 haustion of that principle. In short, as I have said in describing the 
 progress of death, at its approach sensibility shews increase of activity 
 and liveliness, as if its quantity required to be completely exhausted 
 before the termination of existence, or as if the organs made a last 
 effort to cling to life. 
 
 * Their voluntary nerves.
 
 OF SENSIBILITY AND CONTRACTILITY. 31 
 
 Eighthly. The development of the cellular and adipose substance 
 diminishes the energy of sensibility; the extremities of the nerves being 
 more covered, and therefore not so immediately applied to the objects, 
 the impressions which are felt are more obscure. The fat operates on 
 the nerves as wool would do on vibrating chords, if wrapped round 
 them, to fix them, to prevent their quiverings, and stop their vibrations. 
 
 Very nervous women are very thin; persons of much sensibility 
 have seldom much embonpoint. Swine, in which the nerves are 
 covered by a thick layer of fat, are the most insensible of all animals. 
 The susceptibility of the nerves may be diminished, and their sensi- 
 bility blunted by pressure. The application of a bandage firmly rolled 
 round the body and limbs of an hysterical woman, will diminish the 
 violence of her fits. In dressing wounds affected with what is called- 
 the hospital gangrene, I have often relieved the pain by desiring an 
 assistant to apply firm pressure above the sore. 
 
 Ninthly. There exists between the force of the muscles and the 
 sensibility of the nerves, between the sensible energy and the force of 
 contraction, a constant opposition, so that the most vigorous athletes, 
 whose muscles are capable of the most prodigious efforts and of the 
 most powerful contractions, are but slightly affected by impressions, 
 and are with difficulty roused into action, as we have explained in 
 giving a history of the nervous and muscular temperaments, which are 
 characterised by this difference. Hence, man has more sensibility than 
 the quadrupeds, although his nerves are smaller than theirs, which 
 seem destined to set the muscles in action, and to serve as nerves of 
 motion rather than of sensation. 
 
 There is no muscular fibre, however minute, in which we are not 
 obliged to admit the existence of a small nervous filament, to which it 
 probably owes the power of contracting. Contractility, at least volun- 
 tary contractility, does not appear to be inherent in the muscular fibre, 
 nor independent of the nerves, through the medium of which the will 
 determines the action of the muscles ; and if these last organs, when 
 insulated, contract on the direct application of a stimulus, is there not 
 reason to suspect that this stimulus acts on that portion of nerves 
 which remains in the muscle after it has been insulated, and which is 
 intimately united to its fibres ? The animals which have no distinct 
 nervous system possess at once in all their parts sensibility and con- 
 tractility; these two properties become blended in the organs, as well, 
 as in the phenomena of life, and can be perceived separate only by a 
 pure abstraction of the mind, which considers in succession the im- 
 pression produced on these beings, and the motion of their substance, 
 which is an immediate consequence of that impression.* 
 
 * See the notes on Sensibility and Contractility in APPENDIX, Note D.
 
 32 OF SYMPATHY. 
 
 Sensibility and contractility being always present in living animal 
 bodies, some authors have conceived it more natural to combine them 
 under the common appellation of excitability. This one term has 
 been even considered sufficient to designate the whole of the vital pro- 
 perties. But in embracing these properties by this abridged expression, 
 Brown, far from having simplified the study of them, has only 
 increased the obscurity in which they are veiled. In health, as well 
 as in disease, sensibility and contractility do not appear constantly to 
 obey the same laws : action and repose produce not similar effects on 
 them. The sensibility of the eye is enlivened and repaired by the 
 absence of impressions ; but a muscle condemned to repose becomes 
 paralytic. 
 
 The physiologist who wishes to ascertain the causes of sensibility 
 and contractility is as absurd as the person who endeavours to account 
 for the weight, elasticity, and other secondary properties of matter. 
 These two vital principles are only found in organised bodies : their 
 existence is related to a certain arrangement of parts, which has been 
 conveniently called organisation ; but it suffices not that a body should 
 be organised in order that it should enjoy sensibility and contractility 
 that it should live. Death often supervenes without the organisation 
 having evinced any derangement. A certain commixture or amalga- 
 mation of electricity, or of some other imponderable agent, with 
 organised matter, is most probably indispensable to life. But what 
 are the conditions or states of this amalgamation ? 
 
 We will not enter any farther into a consideration of the laws and 
 phenomena of the vital properties, for fear of being led into useless 
 repetitions when we come to the history of the functions over which 
 they preside. We will conclude what relates to them by presenting 
 the two most important features of their history, I mean sympathy 
 and habit. 
 
 SECT. VII OF SYMPATHY. 
 
 There exist among all the parts of the living body intimate rela- 
 tions ; all correspond to each other, and carry on a reciprocal inter- 
 course of sensations and affections. These links which unite together 
 all the organs, by establishing a wonderful concurrence and a perfect 
 harmony among all the actions that take place in the animal economy, 
 are known under the name of sympathies. The nature of this phe- 
 nomenon is yet unknown ; we know not why, when a part is irritated, 
 another very distant part partakes in that irritation, or even contracts: 
 we do not even understand what are the instruments of sympathy, that 
 is, what are the organs which connect two parts in such a manner, that 1 
 when one feels or acts the other is affected. But though beyond 
 explanation, sympathy is not the less important in the economy of
 
 OF SYMPATHY. 33 
 
 living beings ; and these connexions between remote parts constitute 
 one of the most remarkable differences between those beings and 
 inorganic bodies. They are the most characteristic phenomena of 
 vitality. Nothing similar is observable in dead or inanimate nature, 
 in which all things are connected together only by palpable and 
 material links ; here the chain is invisible, the connexion evident, the 
 cause occult, and the effect apparent. 
 
 Whytt has clearly shewn that the nerves cannot be considered as 
 the exclusive instruments of sympathy,* since several muscles of a 
 limb, which receive filaments from the same nerve, do not sympathise 
 together, while there may be a close and manifest relation between two 
 parts, of which the nerves have no immediate connexion, since each 
 nervous filament having one of its extremities terminating in the brain, 
 the other, in the part to which it is sent, remains distinct from those of 
 the same trunk, and does not communicate with them. 
 
 Sympathies may be distinguished into different kinds. In the first 
 place, two organs which execute similar functions : tfie kidneys may 
 supply each other's office. When the uterus is in a state of preg- 
 nancy, the breasts participate in its condition, and there is determined 
 into them a flow of humours necessary to the secretion which is to 
 take place. Secondly : the continuity of membranes is a powerful 
 source of sympathy. The presence of worms in the bowels determines 
 an uneasy pruritus around the nostrils. When there is a stone in the 
 bladder, a certain degree of itching is felt at the extremity of the 
 glans penis. The secretion of several fluids is determined in the same 
 manner ; thus the presence of food in the mouth brings at the extre- 
 mity of the parotid duct an irritation which extends to the parotid 
 glands, calls them into action, and increases their secretion. Thirdly : 
 if the pituitary membrane is irritated, the diaphragm with which it has 
 no immediate organic connexion, nervous, vascular, or membranous, 
 contracts and occasions sneezing. Is not this sympathy one of those 
 which Haller ascribed to a re-action of the sensorium commune? If 
 the impression produced on the olfactory nerves by snuff is too power- 
 ful, the uneasy sensation is transmitted to the brain, which determines 
 towards the diaphragm a quantity of the principle of motion sufficient 
 to enable that muscle suddenly to contract the dimensions of the 
 chest, so as to expel a column of air, that may detach from the 
 pituitary membrane the substances that are a cause of uneasiness to 
 it. Fourthly : does not the principle of life seem to control at plea- 
 
 * The nerves of voluntary motion certainly cannot be supposed to be the in. 
 struments of sympathy ; but no valid argument can be adduced against the opinion 
 which refers the sympathies to the distribution and connexions of the ganglial 
 class of nerves. See the notes on the chapter which treats of " the System of the 
 great Sympathetic Nerves." J. C. 
 
 D
 
 34 OF SYMPATHY". 
 
 sure the phenomena of sympathy ? The rectum, when irritated by the 
 presence of the excrements, contracts; what cause determines the 
 accessory and simultaneous action of the diaphragm and abdominal 
 muscles? Does this connexion depend on organic communications? 
 Why, then, is not the sympathy reciprocal, and why does not the 
 rectum contract when the diaphragm is irritated ? Fifthly : can the 
 repeated habit of the same motions explain the harmony which is 
 observed in the symmetrical organs?'* Why, when our sight is directed 
 to an object placed laterally, does the rectus externus of the eye 
 on that side act at the same time as the rectus externus of the other 
 eye? The indispensable utility of this phenomenon, in keeping a 
 parallelism of the axis of vision, is very obvious ; but who can assign 
 the cause ? Why are rotatory motions, in different directions, per- 
 formed with so much difficulty by the arm and leg of the same side of 
 the body? Can it be called a just idea of the innumerable varieties of 
 this phenomenon and of its frequent anomalies, to say, with Rega, 
 that there are f sympathies of action or of contractility (consensus 
 actionum), sympathies of sensibility (coiisensus passionum). 
 
 All these difficulties render it pardonable in Whytt to have con- 
 sidered the soul as the sole cause of sympathy, which was, in fact, 
 a modest avowal of the difficulty of explaining the subject. We are 
 not justified in considering sympathy as an anomalous action, as an 
 aberration of the vital power.* Can it be said that the natural order 
 of sensibility and irritability is inverted in the sympathetic erection of 
 the clitoris and of the nipple, or in the turgescence of the breasts, 
 determined by the gravid state of the uterus ? 
 
 It is by means of sympathy that all the organs concur in the same 
 end, and yield each other mutual assistance. It affords us the means 
 of explaining how an affection, at first local or limited in its extent, 
 spreads and extends to all the systems ; it is thus that every morbid 
 process is carried on. The diseases termed general, always originate, 
 
 * Sympathy may be considered to be that state of an organ or texture which 
 holds a certain relation to the condition characterising another organ or texture, 
 in health or in disease : or, it may be viewed as a certain relative state of 
 the vital power as it exists in separate organs or textures ; as when one part is 
 excited, another participates in the change, and evinces a similar feeling, motion, 
 or function. 
 
 Sympathies may be classed into the reflex and direct. The former may be 
 referred to the cerebral nerves and to the reaction of the sensorium, as when the 
 Schneiderian membrane is irritated, the diaphragm is affected in consequence of 
 the excitement conveyed to the brain, and thence to this muscle by means of its 
 voluntary nerves. The latter class takes place independently of the sensorium, 
 and arises from the ramification and distribution of the ganglial nerves, especially 
 those which are sent to the vascular system. For the elucidation of this subject, 
 tee APPENDIX, Note E. 7. C.
 
 OF SYMPATHY. 35 
 
 through the medium of association, in the insulated affection of an 
 organ or a system of organs. 
 
 In fact, the affections which appear to us most complex in the 
 number, the variety, and the dissimilarity of their symptoms, consist of 
 only one, or of a small number of primitive or essential elements; all 
 the rest are accessory, and depend on numerous sympathies of the 
 affected organ, with the other organs of the animal economy. Thus, if 
 the stomach is the seat of irritation, from foulness of its contents, 
 pains of all kinds come on, but especially in the head and limbs, with a 
 burning heat, nausea, loss of appetite, anxiety ; and these symptoms 
 constitute a disease, which appears to affect the whole system. 
 
 To go on with the same illustration, the stomach, when oppressed 
 by irritating substances, contracts spontaneously to get rid of them. 
 The universal disturbance which their presence occasions, seems 
 directed towards the same end, as if the suffering organ called upon 
 all the others to assist in relieving it. 
 
 These synergies, or aggregate motions, tending to one end, and 
 arising out of the laws of sympathy, constitute the diseases termed 
 general, as well as the greater part of those which are called local. 
 It is by means of them, and through these kinds of organic insur- 
 rections, if we may be permitted to use this term, which perfectly 
 expresses our meaning, that nature struggles with advantage, and 
 rids herself of the morbific principle, or of the cause of the disease ; 
 and the art of exciting and directing these actions furnishes the 
 materials of the most important doctrines of the practice of medicine. 
 I have used the terms excite and direct ; for it is necessary at times to 
 increase, at others to diminish, their intensity and force, and on some 
 occasions to excite them, when- nature, overwhelmed under disease, is 
 almost incapable of reaction. This last circumstance belongs to the 
 diseases of the most dangerous kind, if we include those in which the 
 efforts of nature, though marked by a certain degree of energy, are 
 without connexion or consent, and frustrated by their want of co- 
 herence. The character of these affections was first well expressed by 
 Selle, who substituted for the term malignant, which used to be applied 
 to them without any precise meaning, that of ataxic, which points out 
 very correctly the want of order, and the irregular succession of their 
 symptoms.* 
 
 A knowledge of sympathies is of the highest importance in the 
 practice of medicine.f When we wish to avert an irritation fixed in 
 
 * * Symptomata nervosa, nee inter se, neque causis manifestos respondentia. Ordo 
 tert. ataxiae, C. G. Selle. Rudimenta Pyretologiifi Methodicae. 
 
 f This information may be obtained by consulting the works of the ancients, 
 and especially of Hippocrates, who appears to have felt all the importance of this
 
 36 OF HABIT. 
 
 a diseased organ, experience and observation prove that it is on the 
 organ which bears to it the closest sympathetic connexions that it is 
 useful to apply medicines intended to excite counter-irritation. 
 
 This might perhaps be the fittest place to inquire into the nature 
 of those concealed relations which draw men together, and of those 
 aversions which prevent their union ; to discover the causes of those 
 secret impulses which lead two beings towards each other, and force 
 them to yield to an irresistible propensity. We might inquire into 
 the reason of antipathy; and, in a word, establish the complete theory 
 of moral sentiments and affections. Such an undertaking is greatly 
 above our strength ; and, besides, does not absolutely belong to our 
 subject. It would require a considerable time ; and whoever should 
 undertake it, would be in considerable danger of losing his way at every 
 step in the extensive field of conjectures. 
 
 SECT. VIII OF HABIT. 
 
 It is easier to feel the meaning of this term than to define it. 
 Habit, however, may be said to consist in the frequent repetition of 
 certain acts, of certain motions, in which the whole body participates, 
 or only some of its parts. The most remarkable effect of habit is to 
 weaken, after a time, the sensibility of organs.* Thus, a catheter 
 introduced along the urethra, and allowed to remain there, causes, 
 during the first day, rather sharp pain ; on the second day it feels 
 less uneasy ; on the third day it is only troublesome ; and on the fourth 
 the patient scarcely feels it. The use of snuff at first increases the 
 secretion of mucus in the nose ; but if continued a certain time, it 
 ceases to affect the pituitary membrane, and the secretion would 
 diminish considerably but for the practice of increasing daily the 
 quantity of that acrid powder : the presence of a canula in the nasal 
 duct, after the operation for fistula lachrymalis, increases at first the 
 mucous secretion of that canal ; but in proportion as it becomes ac- 
 customed to the extraneous body, the secretion returns to its natural 
 condition. 
 
 It is only by our sensations that we are aware of our existence. 
 
 subject. Among the moderns, Vanhelmont, Baglivi, Rega, Whytt, Hunter, 
 Barthez, and Bichat, have collected on this topic a great number of facts obtained 
 from experiments on animals, and especially from observations on diseases. 
 
 * The influence of habit is chiefly perceptible on the organs of sense and volun- 
 tary motion. 
 
 Habit produces very different effects upon separate parts of the animal economy, 
 according as they are altogether removed from the influence of the will, or as they 
 are more or less, or entirely, subjected to it : the effects of habit, for instance, on our 
 voluntary organs, differ very much from those which result from its operation on 
 the viscera of organic life. See APPENDIX, Note F._ J, C.
 
 OF HABIT- 37 
 
 Life, to make use of the figurative language of system, of a modern 
 writer, consists in the action of stimuli on the vital powers. (Tota vita, 
 quanta est, consistit in stimulo et vi vitali. Brown.) Sentient beings 
 feel a continual necessity of renewed emotions ; all their actions tend 
 to the obtaining agreeable or disagreeable sensations: for, in the 
 absence of other sensations, pain is sometimes attended with enjoy- 
 ment. Those who have exhausted every kind of enjoyment, and who 
 have had no pleasures ungratified, are led to suicide from a weariness 
 of life : who can live, when all power of feeling is gone ? 
 
 The following is the most extraordinary and remarkable instance 
 known of the manner in which habit, and a frequent repetition of the 
 same impressions, wear out by degrees the sensibility of organs : 
 A shepherd, about the age of fifteen, became addicted to onanism, 
 and to such a degree as to practise it seven or eight times in a day. 
 Emission became at last so difficult, that he would strive for an hour, 
 and then discharge only a few drops of blood. At the age of six-and- 
 twenty, his hand became insufficient ; all he could do, was to keep the 
 penis in a continual state of priapism. He then bethought himself of 
 tickling the internal part of his urethra, by means of a bit of wood six 
 inches long; and he would spend in that occupation several hours, 
 while tending his flock in the solitude of the mountains. By a con- 
 tinuation of this titillation for sixteen years, the canal of the urethra 
 became hard, callous, and insensible. The piece of wood then became 
 
 as ineffectual as his hand. At last, after much fruitless effort, G 
 
 one day in despair drew from his pocket a blunt knife, and made an 
 incision into his glans along the course of the urethra : this operation, 
 which would have been painful to any one else, was in him attended 
 with a sensation of pleasure, followed by a copious emission. He had 
 recourse to his new discovery every time his desires returned. When, 
 after an incision into the cavernous bodies, the blood flowed profusely, 
 he stopped the haemorrhage by applying around the penis a pretty tight 
 ligature. At last, after repeating the same process perhaps a thousand 
 times, he ended in splitting his penis into two equal parts, from the 
 meatus urinarius to the scrotum, very near to the symphysis pubis. 
 When he had got so far, unable to carry his incision any farther, and 
 again reduced to new privations, he had recourse to a piece of wood 
 shorter than the former : he introduced it into what remained of the 
 urethra, and exciting at pleasure the extremities of the ejaculatory 
 ducts, he provoked easily the discharge of semen. He continued this 
 about ten years : after that long space of time, he one day introduced 
 his bit of wood so carelessly, that it slipped from his fingers and 
 dropped into the bladder. Excruciating pain and serious symptoms 
 came on. The patient was conveyed to the hospital at Narbonne. 
 The surgeon, surprised at the sight of two penes of ordinary size,
 
 38 OF HABIT. 
 
 both capable of erection, and in that stage diverging on both sides, 
 and seeing besides, from the scars and from the callous edges of the 
 division, that this conformation was not congenial, obliged the patient 
 to give him an account of his life, which he did, with the details which 
 have been related. This wretch was cut as for the stone, recovered of 
 the operation ; but died three months after, of an abscess in the right 
 side of the chest, his phthisical state having been evidently brought on 
 by the practice of onanism carried on nearly forty years.* 
 
 The habit of suffering renders us, in the end, insensible to pain : 
 but every thing in this world is balanced ; and if habit lightens our 
 evils by blunting sensibility, it, on the other hand, drains the source of 
 our sweetest enjoyments. Pleasure and pain> these two extremes of 
 sensation, in a manner approximate to each other, and become indifferent 
 to him who is accustomed to them. Hence arises inconstancy, or rather, 
 that insatiable desire of varying the objects of our inclinations, that im- 
 perious want of new emotions ; hence we possess with indifference what 
 we pursued with the utmost ardour and perseverance, and even cease 
 to be impressed by those charms which once held us captivated. 
 
 A striking instance of the powerful influence of habit on the action 
 of organs is afforded by that criminal who, we are told by Sanctorius, 
 was taken ill on being removed from a noisome dungeon, and did not 
 recover till he was replaced in the impure air to which he had been 
 long accustomed. Mithridates, that formidable rival of the Roman 
 power, dreading to be taken alive by his enemies, tried in vain to put 
 an end to his life by taking large doses of the most subtle poisons, 
 because he had long inured himself to their action. f It has, therefore, 
 been justly said of habit, that it is a second nature, whose laws ought 
 to be respected. 
 
 The organs of generation in women, in consequence of their lively 
 sensibility, are in an especial manner submitted to the powerful in- 
 fluence of habit. The womb, after a miscarriage, has a tendency to 
 a renewal of the same occurrence when the same period of pregnancy 
 recurs ; so that the greatest precautions are necessary to prevent 
 abortion in women who are subject to it, when they have reached 
 the month in which they before miscarried. 
 
 May not death be considered as a natural consequence of the laws 
 of sensibility ? Life, depending on the continual excitement of the 
 living solids by the fluids which moisten them, ceases, because the 
 parts endowed with sensibility and contractility, after long habitude 
 
 * Chopart, Maladies des Voies Urinaires, tome ii. 
 
 f In some very rare cases, habit produces a quite contrary effect. Cullen states, 
 that he knew persons so accustomed to excite vomiting in themselves, that the 
 twentieth part of a grain of tartar emetic was sufficient to excite a convulsive action 
 of the stomach.
 
 OF HABIT. 39 
 
 of the impressions of those fluids, lose their capacity of feeling them. 
 Their action, gradually extinguished, would perhaps revive, if the 
 energy of the stimulating power were increased. 
 
 A knowledge of the power of habit is a useful guide in the appli- 
 cation of remedies, the greatest part of which operate in the cure of 
 diseases, only by modifying sensibility. A wound in which lint has 
 kept up the degree of inflammation necessary to cicatrisation, becomes 
 insensible to that application, the parts become spongy and soft, and 
 the cure is protracted. The lint should then be covered with an 
 irritating powder, and the pledgets soaked in an active fluid : one 
 may safely increase the doses of a medicine which has been long 
 employed. Thus, in the treatment of the venereal disease by mer- 
 curials, the dose is to be gradually increased : with the same view, 
 Frederick Hoffman recommended, in the treatment of chronic diseases, 
 that the remedies should be suspended for a time and then resumed, 
 lest the system should get accustomed to them, and their influence be 
 lost. The same motive should lead one to vary the treatment, and 
 to employ, in succession, those medicines to which nearly the same 
 qualities are assigned, for each of them call forth the sensibility in a 
 peculiar manner. The nervous system may be compared to an earth 
 abounding in various juices, and for a full display of whose fecundity 
 it is necessary that the husbandman commit to it the germs of various 
 plants. 
 
 It is very remarkable, that habit, or the frequent repetition of the 
 same act, which uniformly, under all circumstances and in all organs, 
 blunts physical sensibility, should improve the intellect,* and increase 
 the facility and activity of execution of all the operations of the 
 understanding, or of the actions which depend on them. " Habit 
 impairs the sensitive power, and improves the judgment" Bichat 
 was therefore incorrect, when, in his distinction of the organs which 
 are subservient to the functions of assimilation, from those which serve 
 to keep up our relation with the surrounding objects, he maintained, 
 that the sensibility of the latter becomes more exquisite, while the 
 sensibility of the former becomes impaired from habit. 
 
 But can a painter, because he judges more correctly than the 
 ignorant of the beauties of a picture, be said to see it better ? Surely 
 not; for he may, with a sight far less penetrating and more infirm, 
 form a more accurate analysis, from the habit which he has acquired, 
 
 * As soon as an act fails to excite our sensations, in an inordinate degree 
 at least, the reasoning powers proceed to analyse its nature : as sensation ceases, 
 reflection commences ; an exquisite state of the former is seldom compatible with 
 a sound judgment. J. C.
 
 40 OF HABIT. 
 
 and judge with a great deal more promptitude and certainty, of the 
 several parts and of the whole ; just as the practised ear of the musi- 
 cian seizes, in a piece of music, and during the most rapid execution, 
 the expression and the value of all the notes and tones. The error 
 has arisen, from its being forgotten, that, correctly speaking, it is not 
 the eyes that see, or the ears that hear ; that the impressions produced 
 by the sounds on these organs are but the occasional cause of the 
 sensation, or of the perception of which the brain is the exclusive 
 seat. Which has the more delicate sense of hearing, the North 
 American savage, who hears the noise of the step of his enemies at 
 distances that astonish us ; or the artist who does not hear a person 
 speaking at the distance of fifty paces from him, but who directs with 
 judgment all the operations of a great orchestra, and who distinguishes 
 skilfully the effect of each part ? 
 
 Bring down to a frugal Pythagorean regimen one of our modern 
 epicures : his palate, exhausted of its sensibility by the most savoury 
 dishes, by ardent liquors, and the most exquisite ragouts, will discover 
 no taste in dry bread. Let him, however, live on bread, if he can, for 
 some time ; it will soon appear to him to have a grateful taste, as it 
 does to those who make it their principal article of food, or who take 
 it only with substances which have not a very distinct taste. Although, 
 with the sense of smell, that of taste furnishes us only with ideas the 
 most directly connected with our preservation, those which most turn 
 upon the wants of our animal nature ; although we retain with diffi- 
 culty the impressions of these senses, and that, to enable us to retain 
 them, they must be often repeated ; the epicure had so carefully 
 analysed them, that he had attained to the discernment of the faintest 
 differences of taste, all those delicacies of sensation, which, as Montes- 
 quieu said, are lost to us vulgar eaters. 
 
 The motions, under the direction of the will, acquire, by the pre- 
 cision of the determinations, the same aptness, facility, and readiness ; 
 and the dancer, who surprises us with his agility, has reflected, more 
 than might be imagined, on the very complicated steps of which a 
 ballet is composed. 
 
 Morbid sensibility is equally under the influence of habit. I have 
 always observed, that discharges from the urethra become less painful 
 from their frequency. There is nothing, down to disease itself, that 
 is not made lighter by habit, as has been well observed by the old 
 man of Cos. 
 
 It remains then demonstrated, even as a general thesis, that habit, 
 or the frequent repetition of the same acts, whilst it regularly reduces 
 physical sensibility, improves intelligence, and gives facility and prompt- 
 ness to all the motions that are under the direction of the will.
 
 OF THE VITAL PRINCIPLE. 41 
 
 SECT. IX OF THE VITAL PRINCIPLE.* 
 
 The words vital principle, vital force, &c. do not express a being 
 existing by itself, and independently of the actions by which it is 
 manifested : it must be used only as an abridged formula, which serves 
 to mark the total of the powers that animate living bodies, and distin- 
 guishes them from inert matter. So that whenever, in the course of 
 this section, I shall use these terms, or any equivalent, it is to be 
 taken as if I had said, the aggregate of the properties and laws that 
 regulate the animal economy. This explanation is become indispen- 
 sable, now that several writers, realising a mere abstraction, have 
 spoken of the vital principle as of something very distinct from the 
 body, as of a being altogether separable, which they have invested 
 with feeling, and thought, and even deliberate intentions. 
 
 From the furthest antiquity, the many and striking differences of 
 living and inorganic bodies, have led some philosophers to conceive 
 in the former a principle of particular actions, a force which maintains 
 the harmony of their functions, and directs them all to a common end, 
 the preservation of individuals and of the species. This simple and 
 luminous doctrine has remained, even to our own days, only modified 
 in its passage through many years : and no one now disputes the 
 existence of a principle of life, which subjects the beings that enjoy 
 it to a system of laws different from those which inanimate beings 
 obey; a force. which might be characterised as withdrawing the bodies 
 it animates from the absolute dominion of chemical affinities, which 
 would else, from the multiplicity of their elements, act on them with 
 great power ; and as maintaining them in a nearly equal temperature, 
 whatever may be that of the atmosphere. Its essence is not in pre- 
 serving the aggregation of constituent molecules, but in drawing to 
 it other molecules, which, by assimilation to the organs it pervades, 
 replace those that are carried off in daily waste, and serve for their 
 nourishment and growth. 
 
 All the phenomena that are to be observed in the living human 
 body might be brought as proofs of the principle which animates it. 
 The actions of the digestive organs on its food; the absorption, by 
 the chylous vessels, of its nutritious parts; the circulation of these 
 nutritious juices through the sanguineous system; the changes they 
 undergo in their passage through the lungs and the secretory glands ; 
 the impressibility by outward objects ; the power of approaching or 
 avoiding them; in a word, all the functions that are carried on 
 throughout the animal economy, proclaim its existence. But it is 
 customary to take a proof of it yet more direct from the properties 
 
 * See APPENDIX, Note A.
 
 42 OF THE VITAL PRINCIPLE. 
 
 with which the organs of these functions are endowed. We have 
 examined these properties, and we have seen that each of them pre- 
 sents us with at least two great modifications ; that the last discovers 
 three, which are, voluntary contractility, contractility involuntary and 
 insensible, Stahl's tonic motion ; and lastly, contractility involuntary 
 and sensible, as that of the heart and the intestines. 
 
 If it is useful to analyse in order to know, it is of equal importance 
 not to multiply causes, from misconceiving the nature of effects. And 
 if, on the one hand, the multitude of the phenomena of life inclines 
 us to the belief of many causes to produce them ; the unfailing har- 
 mony that pervades all the actions, their mutual connexions and 
 reciprocal dependencies, point much more decisively to a sole agent, 
 as causing, directing, and controlling these phenomena. 
 
 The hypothesis of the vital principle is to the philosophy of living 
 beings what attraction is to astronomy. To calculate the revolutions 
 of the planets, this science is compelled to recognise a force, which 
 draws them constantly towards the sun, and constrains their tendency 
 to fly from it, within the measured distance of those ellipses which 
 they describe around that common centre of light and heat, which 
 dispenses to them, as they roll, the precious germs of life and of 
 fertility. We are about to speak of this force, to which all the powers 
 that animate each separate organ join themselves, and in which all 
 the vital powers are blended; but under the declaration, for the second 
 time, of using the term only in a metaphorical sense. Without this 
 precaution, I might lead you into all the false reasonings which those 
 have fallen into who have assigned to it a real and separate existence. 
 
 The vital power is in perpetual strife with the powers that govern 
 inanimate bodies. The laws of individual nature are, according to 
 the saying of antiquity, for ever struggling against those of universal 
 nature ; and life, which is only this contest prolonged, in favour alto- 
 gether of the vital powers during health, but with uncertain issue in 
 disease, is at an end the moment in which the bodies endowed with it 
 fall again into the system of lifeless being. This constant opposition 
 of vital to physical laws, both mechanical and chemical, does not 
 withdraw altogether living bodies from the control of these laws. 
 There are effects always going on in the living being, chemical, 
 physical, and mechanical : only these effects are constantly influenced, 
 modified, and altered by the powers of life.* 
 
 Why, when we stand up, are not all the humours carried down to 
 the lower parts, by the force of gravitation? The vital power resists 
 
 * In proof of this may be adduced the observation long since made by Dr. 
 Alexander, that the range of temperature most favourable to the putrefaction of 
 dead animal matter, being between 86 and 1 00 of Fahrenheit, includes the usual 
 standard of human heat /. C.
 
 OF THE VITAL PRINCIPLE. 43 
 
 the completion of this hydrostatic phenomenon, and neutralises this 
 tendency of the fluids, the more successfully as the individual is more 
 robust and vigorous. If it is one enfeebled by previous disease, the 
 propensity will be but imperfectly repressed : the feet, after a certain 
 time, swell; and this cedematous swelling can be ascribed only to the 
 insufficient energy of the vital powers, which determine the distribution 
 of the fluids, &c. 
 
 When a tumbler throws himself backwards, the blood does not flow 
 altogether to his head, though this is become the lowest part :' yet the 
 natural tendency of fluids downwards is not altogether overcome, it is 
 only diminished ; for if he preserve long the same attitude, the struggle 
 of the hydraulic and vital powers becomes unequal ; the former pre- 
 vail ; they accumulate the blood upon the brain, and the man dies. 
 
 The following experiment proves incontestably what has just been 
 said of the power of resistance, which, in the human body, more or less, 
 effectually counterbalances the force of physical laws. I applied bags 
 filled with very hot sand along the leg and foot of a man whose artery 
 had been tied by two ligatures, in the hollow of the ham, for popliteal 
 aneurism. Not cnly the limb was not chilled, which is what happens 
 when the course of the blood is intercepted, but the extremity thus 
 covered acquired a heat much above the ordinary temperature of the 
 body. The same apparatus applied to the sound leg did not produce 
 this excess of heat certainly, because the fulness of life in that limb 
 resisted the physical action. 
 
 The vital principle seems to act with the greater energy as the 
 sphere of its activity is narrowed ; which has led Pliny to say, that it 
 was chiefly in the smallest things that Nature has shewn the fulness of 
 her power.* 
 
 The circulation is quicker, the pulse more frequent, the determina- 
 tions more prompt, in men of short stature. Such was the great 
 Alexander : never did man of colossal make display great activity of 
 imagination : none of them have glowed with the fire of genius. Slow 
 in their actions, moderate in their desires, they obey without murmur- 
 ing the will that governs them, and seem made for slavery. Agrippa 
 (says Omilius Probus, in his History of Augustus) advised that they 
 should disband the Spanish guard, and that, in its room, Csesar should 
 choose one of German, " wotting well, that in these large bodies there 
 was little of coverte malice, and yet lesse of subtiltie, and that it was a 
 people more minded to be ruled than to rule." 
 
 To judge soundly of the remarkable difference which inequality of 
 stature brings into the character, compare extremes; set against a 
 
 * Nusquam magis quam in minimis iota est Natura, Hist. Nat. lib. ii. 
 cap. 2.
 
 44 OF THE VITAL PRINCIPLE- 
 
 Colossus a little man of diminutive stature ; granting, nevertheless, to 
 this last full and vigorous health. You may guess that he is talkative, 
 stirring, always in action, always changing his place; one would say 
 that he is labouring to recover in time what he has lost in space. The 
 probable reason of this difference in the vital activity, following the 
 difference of stature, arises from the relative bulk of the primary organs 
 of life. The heart, the viscera of digestion, &c. are of nearly the same 
 bulk in all men : in all, the great cavities are nearly of the same extent, 
 and it is principally in the length of the lower limbs that the difference 
 of stature will be found to lie. It is easily conceivable, that the viscera 
 supplying the same quantity of nutritious juices to a smaller bulk, that 
 the heart giving the same impulse to blood which is to traverse a shorter 
 course, all the functions will be executed with greater rapidity and 
 energy. 
 
 By an obvious consequence, the diseases of little men have a more 
 acute character ; they are more vehement, and tend more rapidly to 
 their crisis.* They have in them something of the velocity, I would 
 even say the instability, of morbid reaction during infancy. There is 
 nothing, even to the duration of life, on which the differences of stature 
 have not some influence. With this suspicion, and some curiosity to 
 ascertain its justness, I have made inquiries in the hospitals where people 
 in advanced life are taken in, and I found them, for the most part, 
 occupied by old men above the middle size; so that reasoning and 
 observation concur in shewing that, all things else being equal, those of 
 superior stature have a grounded hope of prolonging their life beyond 
 the ordinary term. 
 
 I have observed, with many others, that the whole body unfailingly 
 receives an increase of vigour from the amputation of a limb. Fre- 
 quently, after the loss of a part of the body, you will see a manifest 
 change take place in the temperament; those that were weak, even 
 before the disease which brings on the necessity of the operation, be- 
 coming robust ; affections, chronic from debility, such as scrofula, tabes 
 mesenterica, dissipated; and glandular swellings resolved; pheno- 
 mena which indicate a very remarkable increase in the actions of all 
 the organs, f ^ , 
 
 * The acute diseases of tropical countries, especially fever, prove more fatal to 
 short men, or those of middle size, than to the tall /. C. 
 
 f- The extraordinary development of an organ never takes place but at the 
 expense of those about it, of which it draws off the juices. Aristotle observes, that 
 the lower extremities are most always dry and wasted in those who are of ardent 
 temperament, or in habits of frequent venery. Hippocrates relates (in his work 
 De eere, locis, et aquis, Foes : fol. 293), that the Scythian women seared their right 
 breast, that the arm on that side might grow in size and strength. Galen speaks of 
 athletes, who, in his time, kept the sexual organs in the most entire inaction, that, 
 withered, shrunk, and perished, in some sort, by this absolute repose, they might
 
 OF THE VITAL PRINCIPLE- 45 
 
 The parts most remote from the centre of circulation are, in general, 
 less alive than those which are nearer. Wounds of the legs and feet 
 are more liable to ulcerate, because, besides the circulation of the 
 fluids, which the slightest weakness greatly retards in them, their life 
 is too feeble for their wounds to go quickly through their periods, and 
 readily cicatrise. The toes freeze first, when we remain too long ex- 
 posed to severe cold : it is in them, too, that the mortification begins, 
 which sometimes attacks a limb after the ligature of its vessels. 
 
 Thus, although we may say that the principle of life is not seated 
 in any part of our being, that it animates every system of organs, every 
 separate organ, every living molecule, that it endows them with dif- 
 ferent properties, and assigns to them, in some sort, specific characters, 
 it must be confessed that there are in the living body some parts more 
 alive, from which all the others seem to derive motion and life. We 
 have already seen, that these central organs, these foci of vitality, in 
 whose life that of the whole body is involved, diminish gradually in 
 number in the animal kinds as they are more removed from man; 
 whilst the fewer they are, the more they are spread out over the body ; 
 so that life is more generally diffused, and its phenomena less rigorously 
 and strictly connected, as we descend in the scale of being, from the 
 red and warm-blooded, to the red ami cold-blooded animals, from these 
 to the.mollusca, the Crustacea, worms and insects, to the polypus, who 
 forms the extreme link of the animal chain ; and, lastly, to plants, 
 of which not a few, like the zoophytes, so similar to them in many 
 respects, are endowed with the remarkable property of reproduction by 
 slips, which implies, that each part contains the aggregate of organs 
 necessary to life, and can exist alone. 
 
 The vital principle has by some been confounded with the rational 
 soul ; but others have distinguished it from that emanation of Divinity, 
 to which, as much as to the perfection of his organisation, man owes 
 his superiority to all the animal kinds. What bond unites the material 
 principle, which receives impressions and transmits them to the intelli- 
 gence, which feels, perceives, examines, compares, judges, and reasons 
 on them ? Were man one, says Hippocrates, did his material principle 
 make up his whole nature, pleasure and pain would be as nothing to 
 him, he would be without sensation ; for how could he account to him- 
 self for impressions ? Si unus esset homo, non doleret, quiet non sciret 
 unde doleret. Here we stand on the confines of physiology and meta- 
 physics : let us beware of setting foot in the dim paths that are before 
 
 not draw off the nutritious juices from the sole nourishment of the muscular organs. 
 A young man who has several times carried off the prize by running at the public 
 fetes, abstains from venery for some months before entering the lists, in perfect 
 certainty of victory after this privation.
 
 46 THEORY OF INFLAMMATION'. 
 
 us : the torch of observation would yield but ineffectual light, too faint 
 to dispel the thick darkness that lies over them. 
 
 The vital power is merely the vis medicatrix naturae, more powerful 
 than the physician in the cure of many diseases ; the art of the phy- 
 sician consisting, in most cases, in awakening or directing the action of 
 that power. When a thorn is thrust into a part endowed with sensi- 
 bility, a sharp pain is felt, the fluids rush in abundance to the part, it 
 becomes red and swollen ; all the vital powers are excited, the sensi- 
 bility becomes more acute, the contractility greater, and the temperature 
 rises. Does not this increase of vital energy in the injured part, this 
 process which takes place around the substance that is the cause of the 
 disorder, those means which are provided to expel it, indicate the 
 existence of a preserving principle, incessantly watching over the har- 
 mony of the functions, and struggling against all the powers that may 
 tend to interrupt its exercise, or to annihilate the vital motion ? 
 
 Theory of inflammation* Inflammation may, I believe, be de- 
 fined, the increase of vital properties in the parts which it affects. 
 Sensibility becomes more acute in the part so affected, its contractility 
 greater ; and from that increase of sensibility and action arise all the 
 symptoms characteristic of inflammation. Thus the pain, the swelling, 
 the redness, the heat, and the difference in the state of the secretions, 
 denote in the part a more energetic and active vitality. 
 
 Those who have objected to the definition which I have given of 
 inflammation, have evidently mistaken the functions of the organs for 
 their properties. It is very true, that inflammation of the eye is at- 
 tended with loss of sight; but that circumstance depends on the opacity 
 of the transparent parts, which should transmit the luminous rays to the 
 retina. The sight is prevented by a mechanical obstacle; but the 
 sensibility of the organ is augmented to such a degree, that the faintest 
 light reaching the bottom of the eye through the transparent cornea 
 dimmed by the congestion of the vessels, causes in it intolerable pain. 
 On this principle, darkness is universally recommended to patients 
 affected with ophthalmia. In like manner, when a muscle is inflamed, 
 the action of the fibre, its decurtation, is prevented by the congestion 
 in the cellular membrane, which covers it, and fills its interstices. The 
 cause preventing contraction, or the exercise of contractility, is me- 
 chanical, and may be compared to that which, in an inflamed lung, 
 opposes the admission of air and the passage of the blood from the 
 right to the left side of the heart. Can any one call in question the 
 increase of vital action in peripneumony ? I am, therefore, of opinion, 
 that the above definition is better than that proposed by Bichat in his 
 Anatomie Generate, a work of later date than the first edition of these 
 
 " See APPENDIX, Note G.
 
 THEORY OF INFLAMMATION. 47 
 
 Elements of Physiology, and in which he makes inflammation to consist 
 in the increase of those vital properties which he terms insensible. 
 
 All the parts of the human body, with the exception of the epi- 
 dermis and its different productions, as the nails and the hair, appear 
 capable of inflammation. One might include among these " epider- 
 moid " parts, certain dry and slender tendons, as those of the flexors of 
 the fingers, which when pricked, lacerated, and irritated in a thousand 
 ways, are insensible to pain, and remain uninjured in the midst of a 
 whitlow, though attended with suppuration of all the neighbouring soft 
 parts ; and when exposed to the air, they exfoliate instead of granulat- 
 ing. Organisation is so indistinct in all these parts, life so feeble and 
 languid, that they remain insensible to the impression of all those causes 
 which might tend to increase its activity. 
 
 The degree of sensibility in a part, the number and size of the 
 nerves and vessels which are sent into it, determine the degree of its 
 aptitude to inflammation ; thus, the bones and cartilages inflame with 
 considerable difficulty. When one of these parts is laid bare, the first 
 effect of the irritation to which it is exposed, is a softening of its sub- 
 stance. When a bone is laid bare it becomes cartilaginous and softens, 
 in consequence of the absorption of the phosphate of lime which fills up 
 the interstices of its tissue ; and it is only after this kind of incarnation 
 that fleshy granulations begin to spout, as may be observed on the 
 extremities of bones after amputation. The difficulty with which in- 
 flammation is set up in the harder parts of the body explains why, 
 before the twelfth or fifteenth day after a fracture, it is of little conse- 
 quence towards union of the bone that the fractured ends should be 
 placed in apposition ; not that it is right to wait so long before applying 
 the proper bandages, which are indispensable from the first, to prevent 
 the pain and laceration occasioned by the displaced bone. 
 
 The blood is determined, from all quarters, towards the irritated 
 and painful part, which swells and assumes a red colour from the pre- 
 sence of that fluid. The swelling would be unlimited, if, at the same 
 time that the arteries increase in power and calibre to occasion that 
 determination, the veins and lymphatics did not acquire a correspond- 
 ing energy, to enable them to relieve the part of the fluids which have 
 accumulated in it, and which irritation is constantly determining to it. 
 The power of irrita 1 ility and contractility increases with sensibility ; 
 the circulation is more rapid in the inflamed part ; the pulsations of the 
 capillary vessels are manifest. The part is likewise hotter ; because in 
 a giveji time there passes through its tissue more arterial blood, from 
 which a larger quantity of caloric is disengaged, and the continued 
 effects of the pulmonary respiration are better marked in it than in any 
 other organ. 
 
 It forms no part of our intention to treat of the varieties of inflam-
 
 48 THEORY OF INFLAMMATION. 
 
 mation : they depend principally on the structure of the organ which 
 is affected, on the violence and rapidity of the symptoms, and on its 
 effects.* 
 
 Is not the turgescence of an inflamed part occasioned in the same 
 manner as in parts subject to erection, as the corpora cavernosa of the 
 penis and of the clitoris, the nipples, the iris, &c. ? In erection of the 
 penis, as in inflammation, there is an irritation, a determination of fluids 
 to the part, an increase of sensibility and contractility; yet its condi- 
 tion is not that of inflammation. Nature has so disposed the organisa- 
 tion of these parts, that they can sustain, without injury, those in- 
 stantaneous augmentations of vital energy necessary to the exercise of 
 the functions performed by the organs to which they belong. As in 
 inflammation, these congestions disappear when the cause of irritation 
 has ceased to act ; thus, the pupil dilates because the iris recedes when 
 the eye is no longer exposed to the rays of a vivid light. The penis 
 returns to its naturally flaccid and soft state when no irritation operates 
 to determine to it the fluids, whose presence, as long as the erection 
 lasts, is easily explained by the continuance of the irritation, without its 
 being necessary to have recourse to mechanical explanations to account 
 for that phenomenon. When the irritation which produces the vital 
 turgescence of the penis, or iris, is carried too far, or continues too 
 long, the natural congestion becomes morbid. It is well known that 
 priapism is frequently attended with mortification of the penis; and 
 that the too long continued action of light on the eye brings on in- 
 flammation of that organ. 
 
 The preceding observations on inflammation shew that an acquaint- 
 ance with its phenomena is useful, even in a physiological view. The 
 vital processes, which in some organs take place in so obscure a manner 
 that they are imperceptible, acquire in inflammation a character of 
 rapidity and intensity, which renders it much easier to observe and 
 recognise them. Considered in a general and abstract point of view, 
 and merely with a reference to its object, inflammation may be con- 
 sidered as a means employed by nature to repel the influence of noxious 
 agents, which, when introduced within the body, or on its surface, she 
 has no power of resisting but by a more active development of the 
 powers which animate it. 
 
 During the severe winter of 1793, the chemist Pelletier repeated 
 the celebrated experiment of freezing mercury, and obtained a solid 
 ball in the bulb of a barometer, which he had for a long while kept 
 immersed in the midst of a quantity of ice, continually moistened with 
 nitric acid. When the metal had attained a completely solid state, he 
 
 * They depend also upon the causes which produced them, on the habit and 
 constitution of the patient, and the endemic or epidemic influences operating on his 
 frame either previous to or during the progress of the inflammatory disease. /. C.
 
 OF THE GREAT SYMPATHETIC NERVES. 49 
 
 drew the ball from the bulb, and placed it on his hand. The heat of 
 the part ; joined to that of the atmosphere, soon restored the quick- 
 silver to its fluid state : at the same instant he experienced in his hand 
 so intolerable a degree of cold, that he was obliged to drop the 
 quicksilver instantly. There soon came on, in the painful and chilled 
 part, a phlegmonous inflammation, which was cured by resolution. 
 Quicksilver, in a solid state, is one of the coldest bodies in nature : 
 how very rapidly the caloric must have been carried off in this case, 
 and how deep the impression must have been in the palm of the hand, 
 doubly affected by the cold and by the vital re-action, which termi- 
 nated in inflammation ! I have produced a similar effect, by en- 
 deavouring- to melt a piece of ice in my hand, during the heat of 
 summer. In this experiment, the impression of cold is soon succeeded 
 by a sensation of acute pain, and extraordinary throbbings in the 
 hand and fore-arm. When the two hands are afterwards com- 
 pared, that which held the piece of ice is extremely red, from the 
 congestion of blood in the cutaneous capillary tissue, and is very 
 different in its appearance from that which was not the subject of ex- 
 periment. 
 
 Analogous facts, if seriously considered, should induce the fol- 
 lowers of Brown to apply to the effects of cold the distinction which 
 he applied to debility, of direct and indirect. They would have no 
 difficulty in ascertaining, that, in its medical application, that negative 
 state of caloric which is directly debilitating, may, nevertheless, by 
 the re-action which it excites, be considered as an indirect tonic. 
 
 SECT. X OF THE SYSTEM OF THE GREAT SYMPATHETIC 
 
 NERVES.* 
 
 The great sympathetic nerves are to be considered as the bond 
 destined to unite the organs of the nutritive functions, by whose 
 action man grows, is evolved, and incessantly repairs the continual 
 waste attending the vital motions. They form a nervous system, very 
 distinct from the system of the cerebral nerves ; and, as the latter are 
 the instruments of the functions by which we hold intercourse with 
 external objects, the great sympathetic nerves supply motion and life 
 to the organs of the inward, assimilating, or nutritive functions. 
 
 In animals without vertebrae, may not the nervous system, which 
 floats in the great cavities, with the viscera which they contain, be con- 
 sidered as consisting entirely of the great sympathetics ?f These nerves 
 
 * See APPENDIX, Note H. 
 
 f- TREVIRAXTJS, in his Biologic, considers the knotted chord found in the 
 abdomen of insects and worms to be the vertebral ganglia of the sympathetic 
 
 E
 
 50 OF THE GREAT SYMPATHETIC .NERVES- 
 
 are principally distributed to the organs of inward life, whose activity in 
 those animals seems to grow in proportion as their external senses, and 
 their faculty of locomotion, are imperfect. If the great sympathetics 
 exist in all the animals which have a distinct nervous system, do they 
 not, in an especial manner, contain the principle of vegetable life, 
 essential to the existence of every organised body possessing the power 
 of digestion, absorption, circulation,, secretion, and nutrition? Fi- 
 nally, is it not probable, that in man the system of the sympathetic 
 nerves has a ?ery great share in occasioning a number of diseases ; 
 and that the impressions with which patients are affected, are to be 
 referred to their numerous ganglions, while the brain is exclusively the 
 seat of intellect and thought ?* 
 
 These suggestions will, doubtless, be answered in the affirmative, if 
 one considers the origin, the distribution, and the peculiar structure of 
 these nerves, the acute sensibility of their branches, as well as the 
 disorders attending their injury. 
 
 Extended along the vertebral column, from the base of the skull to 
 the lower part of the sacrum, these great nerves, in some measure 
 parasitic, do not arise from the branches supplied them by the fifth 
 and sixth pairs arising from each side of the brain : they live, and are 
 nourished, as it were, at the expense of all the nerves of the spinal 
 marrow, from which they receive branches, so that there is not one of 
 them from which one can say that the great sympathetics arise 
 exclusively. The numerous ganglions which are distributed along 
 their course, divide them into so many small systems, from which 
 arise the nerves of tue organs nearest to them. Amid these bulgings, 
 
 nerve. That it cannot be considered a spinal chord is evident. Its situation shews 
 sufficiently the difference. The molluscae, and many animals removed a little above 
 this class in the scale of creation, possess merely single ganglia, from which proceed 
 fibrilae to the different organs. The great sympathetic nerve is the most general 
 and the most original of all the nerves. Its characters are, however, modified in 
 different classes. In worms and insects there are merely vertebral ganglia, without 
 the cceliac ganglia of mammalia and birds ; in the acephalous molluscae there are 
 the latter, without the former ; in the cuttle-fish and snails there are single ganglia 
 of both kinds. All these animals have no spinal marrow ; fishes and reptiles have 
 one, and also vertebral ganglia ; but the coeliac is not fully developed in them as in 
 birds and mammalia. 
 
 These remarks convey the sum of the observations made by those who have 
 inquired into the subject: how, therefore, can the ganglial class of nerves be 
 considered to arise from the cerebral and vertebral masses ? J. C. 
 
 * These opinions on the uses of the great sympathetic nerves, are explained in 
 my essay on the connexion of life with the circulation. This essay was published 
 before any thing that has appeared on the same subject. Consult the " Memoires 
 de la Societ^ MtJdicale pour 1'an vn."
 
 OF THE GREAT SYMPATHETIC NERVES. 51 
 
 considered by several physiologists as so many little brains, in which 
 is performed the elaboration of the fluid which they transmit to the 
 nerves, no one is of more importance than the semi-lunar ganglion, 
 situated behind the organs which occupy the epigastric region ; and 
 from which those nerves originate which are distributed to the greater 
 part of the viscera of the abdomen. It is to the region occupied by 
 that ganglion, in which the great sympathetic nerves unite, and which 
 may be considered as the centre of the system formed by their union, 
 that we refer all our agreeable sensations ; there it is that we feel, in 
 sadness, a constriction which is commonly referred to the heart. 
 Thence, in the sad emotions of the soul, seem to originate those 
 painful irradiations which trouble and disorder the exercise of all the 
 functions.* 
 
 The numerous filaments of the great sympathetic nerves are finer, 
 they are not of the same whitish colour, nor of the same consistence 
 as the filaments of the cerebral nerves. On that account, they are 
 less easily dissected,f the nervous fibrilse are less distinct, their 
 reddish chords are moister, and they appear formed of a more 
 homogeneous substance : their membraneous coverings are less con- 
 siderable. They are likewise endowed with a more acute and more 
 delicate sensibility. Every one knows the danger attending wounds of 
 the mesentery, a membraneous duplicature, in itself insensible; but 
 containing such numerous nerves destined to the intestinal tube, that 
 the most pointed instrument can scarcely wound the mesentery 
 without injuring some of their branches. The pain attending affec- 
 tions of the great sympathetic nerves is of a very peculiar kind ; it 
 leads directly to the extinction of the vital power. It is a well-known, 
 fact, that a bruise of the testicles overpowers, in a moment, the 
 strongest man. Every one knows, that patients who die of a 
 strangulated hernia, of volvulus, or of any other affection of the same 
 kind, die in the most distressing anguish ; their heart feels oppressed, 
 and they are tormented with constant vomiting. Intestinal and 
 nephritic colics are attended with the same sort of pain : that at- 
 
 * Consult, on the subject of the epigastric centre, Van Helmont, who calls it 
 the Archceus ; Buffon, Bordeu, Barthez, and Lacaze, who give it the name of the 
 phrenic centre, because they ascribe to the diaphragm what belongs to the nervous 
 ganglions placed in front of its crura. 
 
 f One of the best modes of dissecting them, is to macerate the part in which 
 we wish to trace their ramifications, during two or three days in water ; then place 
 it for a short time in a very dilute acid, or warm spirits, or in oil of turpentine. 
 The filaments of these nerves may be then traced more distinctly. Other pro- 
 cesses, which are complex, are requisite to the dissection of the minuter ramifica . 
 tions, especially those which supply the blood-vessels. J. C.
 
 52 OF THE GREAT SYMPATHETIC SERVES. 
 
 tending injection of the tunica vaginalis, in hydrocele, is of the same 
 kind. And one expects a favourable event of the operation only in 
 those cases in which the patient has felt pain along the spermatic 
 chord, in the course of the spermatic nerves, which arise, as it is well 
 known, from the renal plexus. In three cases of wounds of the ab- 
 domen, I was led by the nature of the pain which the patients suf- 
 fered to prognosticate that the wounds had penetrated : the event 
 justified my prognostic. In all these affections of the great sympa- 
 thetic nerves, the pulse is frequent and hard, the face is covered with 
 a cold sweat, the features are sunk ; all the symptoms are alarming, 
 and soon terminate fatally. 
 
 The use of the system of the great sympathetic nerves is, not 
 merely to establish a closer connexion and a greater union between all 
 the organs which perform the functions of assimilation, but likewise to 
 free those parts from the influence of the will, a power of the mind 
 so fickle and so varying, that life would be in constant danger, if we 
 had it in our power to stop or suspend the exercise of the functions 
 with which it is essentially connected. 
 
 If we consider what are the organs to which the functions of assimi- 
 lation are intrusted, and which receive their nervous influence from the 
 great sympathetic nerves, we shall find that the action of the greater 
 number is wholly independent of the control of the will.* The heart, 
 the stomach, the intestinal canal, &c. do not obey the will, and seem 
 to possess a more insulated and more independent existence, and to 
 act and rest without any influence on our part. Some of these organs, 
 as the bladder, the rectum, and the muscles of respiration, which do 
 not receive their nerves exclusively from the great sympathetics, are 
 obedient to the will, and receive from the brain the principle of mo- 
 tion ; the former from the branches which the sacral nerves send to 
 the hypogastric plexuses; the diaphragm from the nerves which it 
 receives from the fifth and sixth cervical pairs. ' 
 
 The great sympathetic nerves supply the diaphragm, the rectum, 
 and bladder, only with nerves of sensation. This provision was a very 
 necessary one, for if, as is the case with the heart and the intestines, 
 
 * All those parts which receive their nerves from ganglions are equally inde- 
 pendent. Professor Chaussier thinks, that the upper filaments of the great sympa- 
 thetic nerves ascend along the internal carotid, and join the spheno-palatine and 
 lenticular ganglions. M. Ribes thinks he has ascertained by dissection that several 
 very long and slender filaments follow the course of the branches of the internal 
 carotid, and like them are sent to the base of the brain, beyond which they cannot 
 be traced. I hare myself observed in dissection these filaments around the branches 
 of the internal carotid artery, but I had always considered them to be formed of 
 cellular substance.
 
 OF THE GREAT SYMPATHETIC NERVES. 53 
 
 these parts had received their nerves of motion from the great sympa- 
 thetics, their action would have been independent of the will, as is the 
 case with all the parts which these nerves supply with motion. The 
 bladder and rectum, placed at the extremities of the digestive appa- 
 ratus, and destined to serve as reservoirs to the excrementitious residue 
 of our solid and liquid aliments, would have been constantly evacuat- 
 ing their contents as fast as the substances which are destined to be 
 retained within them for some time reached their cavity. 
 
 On the other hand, if the diaphragm had received its nerves of 
 motion from the great sympathetics, respiration would have ceased to 
 be a* voluntary function, of which we nugkt at pleasure accelerate, 
 slacken, or even completely suspend the action. To prove that the 
 act of respiration is under the control of the will, we may have recourse f 
 to analogy, and adduce the instance of reptiles, as lizards, frogs, ser- 
 pents, salamanders, and toads, which are cold-blooded animals, and in 
 which this function is manifestly voluntary. We may further mention 
 those slaves, who, we are told by Galen, pat themselves to death when 
 summoned before their executioners ot judges. According to that 
 physiologist, and others, they choaked themselves, by swallowing their 
 tongue. But it is sufficient to know how the muscles that bind 
 down the tongue are situated, and the degree of motion which they 
 allow, to see how little ground there is for that opinion. The action 
 of the brain would, in that case, have been no longer necessary to 
 the maintenance of life ; in an animal without a brain, respiration would 
 have continued, and the circulation would not have been interrupted. 
 The death of that viscus would not have been attended with the sudden 
 death of all the rest. 
 
 The nerves which arise from the spinal marrow, and which give to 
 the diaphragm the power of contraction a power which that muscle 
 loses suddenly if these nerves be tied appear to me the chief links 
 which unite the internal assimilating, or nutritive functions, to those 
 which keep up the relation of the animal with external objects. 
 Without this bond of union, the series of vital phenomena would have 
 been less close, and their dependence less necessary. Had it not 
 been for the necessity that the diaphragm should receive from the 
 brain, by means of the phrenic nerves, the principle which determines 
 its contractions, acephalous animals, which are born without that 
 organ, might continue to live as they, did before birth, when the organs 
 of nutritive life received blood which had undergone, in the lungs of 
 the mother, the changes necessary to life. But where the bond which 
 united them to the mother is destroyed, obliged themselves to produce 
 in their fluids the necessary changes, by the inhalation of the vivifying 
 principle contained in the atmosphere, they no longer can obey that
 
 54 OF THE GREAT SYMPATHETIC NERVES. 
 
 necessity : the organs of respiration are deficient in the principle 
 which should excite them. 
 
 When an internal inflammation is of small extent,*.and is seated in 
 a part in which there are not many nerves, and whose tissue yields 
 easily to the humours which irritation determines into it, the whole 
 morbid action takes place in the affected part, and the general order of 
 the functions is not sensibly deranged. But when inflammation takes 
 place in a part endowed with much sensibility, or of a close texture, as 
 the ringers and toes, then fever comes on, because a sympathy in the 
 morbid action takes place between the diseased part and the rest of the 
 system. This diffusion of the local action almost infallibly takes place 
 when inflammation occurs in one of the organs of the assimilating 
 functions. This effect may be considered as uniform, though Mor- 
 gagni mentions several instances of inflammation of the liver, marked 
 by no peculiar symptoms. 
 
 A knowledge of the great sympathetic nerves accounts for this 
 difference. When an external part is affected with inflammation, the 
 irritation which it suffers is, by means of its nerves, propagated to the 
 brain, which by a re-action, f called by Vicq-d'Azyr (who on this sub- 
 ject has only developed the opinions of Van Helmont) internal nervous 
 action, transmits that irritation to the heart, to the organs of respi- 
 ration, of digestion, and of secretion, in which the phenomena, denot- 
 ing a febrile state, are principally evolved. When, on the contrary, 
 the heart, the lungs, or any other internal organ, is affected with acute 
 inflammation, all the viscera partake in the derangement with which any 
 one of them is affected, and without the intervention of the brain. 
 They are all intimately connected by the filaments which they receive 
 from the great sympathetic nerves ; and by means of that nervous sys- 
 
 * A thousand pustules in the small-pox occasion only a moderate degree of fever, 
 if they are at a distance from each other ; but if the disease is confluent, that is, if 
 the pustules are close together, and run into each other, the fever becomes consi- 
 derable, and the patient's life is endangered. The fleshy granulations which sprout 
 in abundance from an ulcerated surface, are so many small phlegmons unaccom- 
 panied by a febrile state ; but if brought close to each other by irritation, that con- 
 dition will not fail to ensue. Vaccination is not, in the greater number of cases, 
 attended by the slightest febrile action, if, as I always have done, the punctures are 
 made at a certain distance from each other, so that the inflammatory areolae may 
 not run into each other. 
 
 f The cerebral re-action appears to be in no measure necessary to the induction 
 of symptomatic fever : it may, however, contribute to its continuance. The irri- 
 tation appears to be propagated to the heart in consequence of the numerous con- 
 nexions which this organ holds, by means of t^.e ganglial nerves, with the other 
 viscera, and owing to the continuous reticulation of these nerves upon the arterial 
 system from the heart to the capillary terminations of the vessels. See the 
 APPENDIX, Note II, for further observations on this subject. J. C.
 
 RELATIONS OF PHYSIOLOGY. 55 
 
 tern, which is in an especial manner appropriated to them, they carry 
 on a more intimate intercourse of sensations and affections. Besides? 
 the derangement of the important functions intrusted to the diseased 
 organs, is necessarily attended with proportionate changes in all the 
 acts of the animal economy, in the same manner, no doubt, as the 
 defect of one wheel interrupts or disturbs the mechanism of the whole 
 machine. 
 
 There exists in the stomach a union of the cerebral and sympa- 
 thetic nerves, which explains the manifest dependency of this viscus 
 on the brain ; a dependency so marked, that every strong affection of 
 the soul, every violent agitation of the mind, weakens, or even totally 
 suspends, the action of digestion in the stomach. " This combination 
 of cerebral and sympathetic nerves likewise accounts for various 
 phenomena connected with disease, and for the operation of several 
 remedies in removing it."* 
 
 SECT. XI OF THE RELATIONS OF PHYSIOLOGY TO SEVERAL. 
 
 OTHER SCIENCES. 
 
 It would be entertaining a very incorrect notion of the science of 
 living man, to imagine, with some authors, that it solely consists in the 
 application of the laws of natural philosophy to the explanation of the 
 phenomena of the animal economy. Physiology is an independent 
 science, resting upon truths of its own, which it draws from the observa- 
 tion of those actions which, in their aggregate succession and con- 
 nexion, constitute life. It is enriched, it is true, with facts furnished 
 to it by natural philosophy, chemistry, and mathematics ; but what it 
 has borrowed from these is accessory merely, and does not form an 
 essential part of the edifice of the science. Thus, the better to under- 
 stand the mechanism of hearing and vision, physiology borrows, from 
 acoustics and optics, elementary notions on sound and light; and in 
 order to obtain a more correct knowledge of the nature of our solids 
 and fluids, and of the manner in which animal substances are con- 
 stantly passing from the one to the other of these two conditions, 
 physiology calls in the aid of chemistry. Thus, geometry and mecha- 
 nism furnish it with the means of better understanding the advantageous 
 form of the organs, and the perfection of their structure, f Where the 
 
 * See the observations on the functions of the Stomach, and on the influence 
 of the eight pair of nerves in Digestion, in the APPENDIX, Notes K and L. 
 
 f A knowledge of mathematics, and of the whole circle of natural philosophy, 
 including more especially chemistry and natural history, and, in a more particular 
 manner, human and comparative anatomy, is requisite to the successful study of 
 physiology. This last branch of knowledge, although independent of some of these, 
 is yet more easily acquired, and its difficulties are better explained, by a previous
 
 56 RELATIONS OF PHYSIOLOGY. 
 
 natural philosopher stops, the physician commences. Ubi desinit phy- 
 sicus, ibi incipit medians, was well said by Aristotle. 
 
 No study carries along with it a more lively interest than that of 
 the admirable relations existing between the conformation of our parts 
 and the external objects to which they are applied. These relations 
 are calculated with such precision, and laid down with such accuracy, 
 that the organs of sense and of motion, considered in this point of view, 
 mav be regarded as the model of the most ingenious productions of art. 
 So true it is, in the words of the great physician of Pergamus, that 
 nature did every thing before art, and better.* 
 
 At the beginning of the last century, geometrical physicians, de- 
 ceived by an appearance of rigid precision, attempted to explain every 
 thing by the calibre of vessels, their length, their curvatures, the com- 
 pound ratio of the action of solids, and the impulse of fluids. Hence 
 were formed theories so very imperfect, that, as we shall see, in treating 
 of several points of physiology, and especially of the force with which 
 the heart acts, not one of those who proposed them" coincides with 
 those who have since followed their track. However, it does not 
 admit of a doubt, that there occur, in the animal machine, effects 
 which are referable to the laws of hydraulics. The brain, for example, 
 required a large and constant supply of arterial blood, vivified by 
 recent circulation through the lungs; but the too rapid and abrupt 
 access of that fluid in the brain might have disordered its structure. 
 Nature, therefore, has, as we shall mention in the article of the 
 cerebral circulation, employed all the hydraulic resources in her power, 
 to break the force with which the blood enters the brain, and to 
 slacken its course. 
 
 Has man ever applied the laws of hydraulics in a more felicitous 
 manner than nature, in the rete mirabile formed at the base of the 
 brain by the carotids of quadrupeds ? an arrangement truly remark- 
 able, without which the blood conveyed to the brain by those arteries, 
 impelled by a force superior to that of the human heart, and not 
 having to overcome the resistance of its own gravity, would infallibly 
 have occasioned a disorganisation of that organ, whose consistence is 
 so soft. 
 
 As to the application which is allowable of mathematical sciences, 
 
 acquaintance with all of them. Pathology and the treatment of diseases, also, 
 reflect a light upon physiology which they first derive from this productive 
 source J. C. 
 
 * Quandoquidem natura, ut arbitror, et prior tempore sit, et in operibus mayis 
 sapiens quam ars. GALENUS de Usu Partium, lib. vii. cap. 13. 
 
 It was from observing the manner in which nature prevents the diffusion of 
 light in the globe of the eye, that Euler was led to the improvement of his astro- 
 nomical telescopes.
 
 RELATIONS OF PHYSIOLOGY. 57 
 
 it may be said, that, as in physiology, but little is absolutely certain,* 
 and much merely probable, we can reckon only on probabilities, and 
 seek our elements in facts deduced from observation or experience ; 
 . facts which, when collected and multiplied to a certain degree, lead to 
 results of equal value with truths absolutely demonstrated. 
 
 The phenomena presented by living bodies vary incessantly in 
 their activity, their intensity, and their velocity. How can mathe- 
 matical formulae apply to such variable elements ? As well might you 
 enclose in a frail vessel, hermetically sealed, a fluid subject to expansion, 
 and of variable bulk. The motions of progression in man and in the 
 animals afford, nevertheless, sufficiently correct applications of calcu- 
 lation. Calculation may likewise be applied with advantage to the 
 measurement of the results of our different secretions, to ascertain the 
 quantity of air or of aliment introduced into our organs, &c. 
 
 Among the principal causes which have retarded, in a considerable 
 degree, the progress of physiology, may be enumerated the mistake of 
 those who have endeavoured to explain all the phenomena of living 
 bodies by a single science, as chemistry, hydraulics, &c., while the 
 union of all these sciences will not account for the sum of these 
 phenomena. The abuse, however, of these sciences should not be a 
 reason for setting them aside altogether. The facts obtained from 
 natural philosophy, chemistry, mechanics, and geometry, are so many 
 means applicable to the solution of the great problem of the vital 
 economy; a solution which, though as yet undiscovered, should not 
 be considered as unattainable, and to which we shall approach the 
 nearer as we attempt it with a greater number of data. But it cannot 
 be too often repeated, that he alone can hope for that honour who, 
 in the application of the laws of natural philosophy to living bodies, 
 will take into account the powers inherent in organised nature, which 
 control, with supreme influence, all the acts of life, and modify the 
 results that appear most to depend on the laws by which inorganic 
 bodies are governed. 
 
 Anatomy and physiology are united by such close relations, that 
 it has been an opinion with some that they are absolutely inseparable. 
 If physiology, say they, has for its object a knowledge of the functions 
 carried on by our organs, how is one to understand their mechanism, 
 without knowing the instruments by which they are performed ? .One 
 might as well attempt to explain the manner in which the hand of a 
 
 tivatch performs the circle of its diurnal revolution, without under- 
 * This is to be understood as applying only to the causes of the phenomena, 
 md not to the phenomena themselves ; for physiology is perhaps riqher than any 
 >ther science, in facts unquestionable, and easily ascertained by observation. 
 '
 
 58 RELATIONS OF PHYSIOLOGY. 
 
 standing the springs and numerous wheels which set it in motion. 
 Haller is the first who established the connexion between anatomy 
 and physiology, and who illustrated it in his great work. Since Haller, 
 a great number of anatomists, and among them Soemmering,* in a 
 work recently published, have combined, as much as possible, these 
 two sciences ; the latter, in treating separately of each system of 
 organs, explains what is best known of their uses and properties. 
 
 However close the connexion between anatomy and physiology, 
 they have, nevertheless, appeared perfectly distinct to the greater 
 number of authors, and we have several valuable works on anatomy, 
 of which physiology occupies but a small part. This manner of em- 
 bracing the two sciences appears to me attended with the greatest 
 advantage : in fact, if the insulated description of organs suffices to 
 the physiologist who wishes to study their functions, that method is 
 attended with the disadvantage of furnishing few truly useful views 
 in the practice of operative surgery. To render the knowledge of the 
 human body more especially applicable to the practice of surgery, it 
 is necessary not only to consider separately the different parts, but 
 likewise to view them in their connexion, and to determine precisely 
 their relations. The anatomist, who knows that the principal artery of 
 the thigh is the crural ; that, continued under the name of popliteal, it 
 passes behind the knee in its way to the leg ; that in its course it 
 supplies with branches different parts of the limb; even though he 
 knew perfectly the names, the number of these branches, the varieties 
 to which they are subject, the parts to which they are distributed, 
 would, nevertheless, possess a knowledge of that branch of the system, 
 almost useless in the treatment of the diseases with which it may be 
 affected. The situation of the artery, its direction, the parts which 
 surround it, its precise relations to each of them, its superficial or deep- 
 seated course, &c. are the only circumstances from which he can 
 derive any advantage. 
 
 He who, in this point of view, cultivates anatomy, may be com- 
 pared to the chemist : in the same manner as the latter is never better 
 acquainted with a substance than when he is able to decompose it, and 
 to reproduce it from a combination of its parts ; so the anatomist is well 
 acquainted with the body of man only when, having studied separately 
 and with the greatest care each of his organs, and each of the systems 
 formed by the collection of a certain number of similar organs, he is 
 able to assign to each of them its place, to determine its relations, and 
 the proportions which it bears in the structure of any one of our limbs. 
 The study of the latter is much more difficult and extensive than that 
 
 J. Ch. Scemmering, de Corporis Humani Fabrica, 6 vols. 8vo. 1804.
 
 RELATIONS OF PHYSIOLOGY. 59 
 
 of the former; for, the chemist who decomposes and recom pounds a 
 well-known substance, phosphate of lime, for instance, attains only 
 to the knowledge of its constituent principles and respective propor- 
 tions : the phenomena of situation altogether escape him. The ana- 
 tomist, on the other hand, who knows that such a part is composed of 
 bones, of muscles, of nerves, of vessels, must know not only every one 
 of these parts, and their relative bulk, but the exact place in which they 
 are to be found. 
 
 Anatomy, pursued in this spirit, offers a field of wide extent : it is 
 the art which Leibnitz called the analysis of situation, analysis sit&s ; 
 and the knowledge of it is too important not to require a separate 
 place among the departments of medical knowledge. I will not pass 
 over the motives that are alleged for combining anatomy and phy- 
 siology in one course of instruction. Anatomy, confined to the mere 
 description of the organs, is too dry and fatiguing : physiology throws 
 over it interest and variety ; it helps to ensure the attention of the 
 hearers, who will retain more permanently what they have listened to 
 with pleasure. Would not one think that physiological details were, 
 for an audience, what is contrived for a sick and froward child, in the 
 honey that is rubbed on the edge of the cup, to disguise the bitterness 
 of the draught that is to recall him to health? In combining two objects, 
 of which one has no interest but that of usefulness, whilst the other is 
 engaging as well, the attention will be not merely divided, but altogether 
 distracted ; and the mind of those who read or listen will skim over dry 
 details, to seize with avidity what furnishes more to its activity of intel- 
 ligence. Anatomy is to physiology what geography is to history. 
 General considerations on the situation, the size, the form, the rela- 
 tions, the structure of the organ, are an indispensable preparation to 
 the perfect understanding of its functions : accordingly, you shall find 
 much anatomy in physiological treatises, as you find much geographical 
 detail in faithful historians. 
 
 I have said enough, I trust, to escape the reproach of not having 
 filled my book with anatomical descriptions from the multitude of 
 excellent works we possess on the anatomy of the human body. Let us 
 now inquire what relation physiology bears to comparative anatomy. 
 
 If a machine can be perfectly known only after taking it to pieces, 
 down to its simplest elements; if the whole mechanism of its perform- 
 ance can be conceived only by examining separately the action of each 
 different part composing it, comparative anatomy, by aid of which 
 we may study, in the great chain composing the various classes 
 of the animal kingdom, the separate action of each organ, appre- 
 ciate its absolute or relative importance, consider it at first insulated 
 and reduced, so to speak, to its own powers, in order to deter- 
 mine what part it bears in the carrying on of a function, comparative
 
 60 RELATIONS OF PHYSIOLOGY. 
 
 anatomy is of absolute necessity to him who would make great progress 
 in the knowledge of man : it may be looked upon as a sort of ana- 
 lytical method of study, by means of which we more completely attain 
 to the knowledge of ourselves. 
 
 In order to conceive rightly the operations of the human intellect, 
 and explain the generation of the faculties of the soul, metaphysicians 
 have imagined a statue, into which they have infused a gradual anima- 
 tion, by investing it, one by one, with, our organs of sensation. Now 
 nature has realised, in some sort, this dream of philosophy. There are 
 animals to which she has entirely denied the organs of sight and hear- 
 ing; in some, taste and smell seem to have no separate existence 
 from touch ; in others, she has exercised a sort of analysis on a system 
 of parts which all concur in one function. It is thus, that in some 
 animals, divesting the organ of hearing of the accessories allotted to 
 collect, transmit, and modify the rays of sound, she has reduced it to a 
 simple cavity, filled with a gelatinous fluid, in which float the extremi- 
 ties of the acoustic nerve, alone fitted to receive the impression of 
 sound ; a fact which overthrows all the hypotheses that had ascribed 
 this sensation to other parts of the auditory apparatus. 
 
 Of all the physical sciences, comparative anatomy is that which 
 furnishes the most useful facts to physiology.* Like physiology, it is 
 concerned with organised living beings ; there is, therefore, no need 
 of watching against the false applications, so often made from the 
 sciences, whose objects are matter inorganic and dead, or which study, 
 in living beings, only the general properties of matter. Haller was so 
 well aware of the utility of introducing this science into physiology, 
 that he has brought together the greater part of the facts known in his 
 time on the anatomy of animals, at the head of each chapter of his 
 immortal work. 
 
 This general consideration of living and animated beings, so well 
 adapted to unveiling the secret of our organisation, has this further 
 advantage, that it enlarges the sphere of ideas of him who applies to it. 
 Let him who aspires to that largeness of conception, so requisite in 
 medicine, where facts are so multiplied and various, explanations so 
 contradictory, and rules of conduct so unfixed, cast a general glance 
 on this great division of organised beings, of which many, in their 
 physical structure, so nearly resemble man, he will see the sovereign 
 
 * " The extensive examination of various structures," Mr. Lawrence very 
 justly observes, " is not only a necessary ground-work for the edifice of general 
 physiology, but it has thrown great light on the organisation and functions of the 
 human frame. Whoever will reflect on our present knowledge of the digestive, 
 respiratory, generative, or other processes of man, and will review the successive 
 stages of its progress, will find that comparative anatomy has rendered us the moet 
 essential assistance." J. C.
 
 RELATIONS OF PHYSIOLOGY. 61 
 
 Architect of Jfcfr world$Hstributing to all the elements of life and acti- 
 vity, giving to some a less power of motion, to others more; so that, 
 formed all on one model, they seem only the infinitely varied but 
 gradual shades of the same form, if forms have shades like colours ; 
 never passing abruptly from one to another, but rising or falling by 
 gentle and due degrees, covering the interval that separates two dif- 
 ferent beings with many species that serve as a transition* from one 
 to the other, and which present a continuous series of advancement or 
 degradation ; organisation being constantly simplified in descending 
 from man to the inferior creatures, but rising in complexity in re- 
 ascending from those animals to man, who is the most complex being 
 in nature, and was justly considered by ancient philosophy as the 
 master-piece of the Creator. 
 
 If the intimate structure of our organs totally eludes our investi- 
 gation, it is that the finest and most delicate of their constituent parts 
 are of such minute dimensions that our senses have no hold on them. 
 It is then well to have recourse to analogy, and to study the organisation 
 of animals that exhibit the same organs on a larger scale. Thus the 
 cellular texture of the lungs, which cannot be distinctly shewn in man, 
 on account of the extreme minuteness of the smallest bronchiae, may 
 be satisfactorily seen in the vesicular lungs of salamanders and frogs. 
 In like manner, the scales which cover the bodies of fishes and reptiles, 
 or the legs of birds, give us a just idea of the structure of the epi- 
 dermis, and of the arrangement of its small scales, which lie over each 
 other, in a part of their surface. 
 
 The human structure being more complicated, must produce effects 
 more numerous, and results more varied and more difficult to under- 
 
 * The conception of a scale of being, which, as was said by C. Bonnet, con- 
 necting all the worlds, embracing all the spheres, should extend from the atom 
 to the most exalted of cherubim, is noble and interesting. Without carrying it so 
 high or so low, if we confine it to the natural beings with which we are well ac- 
 quainted, and which can be brought under observation, it will be seen, that the 
 idea is not so chimerical as some writers of most respectable authority have sup- 
 posed it. The plan traced by C. Bonnet is evidently defective ; we find in it beings 
 set beside each other, that have but faint lines of resemblance, or altogether illusive. 
 The present state of the natural sciences would allow of its being better done : one 
 might try at least for all bodies what Jussieu has executed with regard to vegetable 
 productions ; and if this undertaking, in the hands of men the most able to bring 
 it to a successful termination, left any thing defective, would not that imperfec- 
 tion be an indication of the existence of other worlds, or of lands yet unknown on 
 the globe we inhabit ; undiscovered regions, where those animals, and plants, and 
 minerals, would be found which were wanting to fill up the gaps in the immense 
 series of co-ordinate existence ? 
 
 Demonstratum full et hoc, nullam rem contrarias, vel omnino multum differentes, 
 qualitates recipere posse, nisi per medias prius iter fecerit GAI.ENUS de Usu Par- 
 Hum, lib. iv. cap. 12.
 
 62 CLASSIFICATION OF THE FUNCTIONS. 
 
 stand. In commencing the study of the animal organisation by that 
 of man, we do not therefore follow the analytic method ; we do not 
 proceed from what is simple to what is more complex. It would per- 
 haps be an easier and a more natural way of arriving at a solution of 
 the grand and difficult problem of the animal economy, to begin by 
 explaining its most simple terms ; to rise by degrees from plants^ to 
 vegetating animals, as polypi ; from these to white-blooded animals ; 
 then to fishes and reptiles ; from the latter to warm-blooded animals ; 
 and, lastly, to man himself, placed at the head of that long series 
 of being, whose existence becomes complicated in proportion as they 
 approach him. 
 
 The study of every part of natural history, and especially of com- 
 parative anatomy, cannot fail, therefore, to prove of infinite advantage 
 to the physiologist; a truth well expressed by the eloquent M. de 
 Buffon,* who says, that if there existed no animals, the nature of man 
 would be still more incomprehensible. 
 
 I shall say nothing of the well-known relations of physiology to 
 medical science, of which it is justly considered as the base or support. 
 Medicine, called by some the art of healing, by others, more properly, 
 the art of treating diseases, may be defined the art of preserving health, 
 of curing diseases, or of rendering them more supportable ; medicine, 
 in all its parts, is enlightened by physiology, and cannot have a surer 
 guide. Owing to a neglect of this auspicious guide, fherapeutics and 
 materia medica long remained involved in a mist of conjectures and 
 hypotheses. Physicians should never for a moment forget, that as 
 a great mimberf of diseases consist in a derangement of the vital 
 functions, all their efforts should tend to bring back sensibility and 
 contractility to their natural condition ; that the best classification of 
 diseases and of medicines is that which is founded on a judicious 
 distinction of the vital powers. With this view it is that M. Alibert, in 
 his elements of materia medica, classes medicines according to their 
 effects on sensibility or contractility, and according to the organs on 
 which their action is particularly exerted. 
 
 SECT. XII. CLASSIFICATION OF THE VITAL FUNCTIONS. 
 
 After having treated separately of the vital powers or faculties, 
 nothing is easier than to arrange, in a clear and methodical order, the 
 functions carried on by the organs which these powers call into action. 
 
 * Histoire Nat. torn. v. 12mo. p. 241. Discours sur la Nature des Animaux. 
 
 f All diseases consist in physical derangements, as solutions of continuity, dis- 
 placements ; organic alterations, as polypi, aneurisms, and other affections resulting 
 from organic affection and alteration of structure ; vital lesions, as stlienic, asthenic, 
 ataxic disorders, asphyxia, &c See Nosographie et Th'erapculique Chirurgicales, 
 5 edit. Paris, 1821 ; Prolegomen.es, torn. i.
 
 CLASSIFICATION OF THE FUNCTIONS. 63 
 
 The term function might be defined means of existence. This defini- 
 tion would be the more just, as life is only the exercise of these func- 
 tions, and as it ceases when any one of the more important can no 
 longer be carried on. From not distinguishing the faculties from the 
 functions, which are merely the acts of the faculties or powers, several 
 modern divisions, though far preferable to the old classification of the 
 functions into vital, animal, and natural, are, nevertheless, deficient in 
 accuracy and simplicity. Thus Vicq-d'Azyr, in the classification of the 
 phenomena of physiology, inserted in the discourse which he has 
 prefixed to his work on anatomy, mistakes the cause for the effect, 
 and places sensibility and irritability among the functions ; and com- 
 mits another mistake, by ranking ossification among the latter, which 
 is but a peculiar mode of nutrition, belonging to parts of a hard 
 structure. 
 
 The best method of classing the actions which are performed in the 
 living human body is, doubtless, that by which they are distributed and 
 arranged according to the object which they fulfil. Aristotle, Buffon, 
 and especially Grimaud, have laid on that base the foundation of a 
 method which we shall adopt, with the modifications which we are 
 about to mention. 
 
 Aristotle and Buffon had observed, that among the acts of the 
 living economy, some were common to all beings that have life, to 
 plants and animals during sleep and in waking, while others seemed to 
 belong exclusively to man, and to the animals which more or less 
 resemble him. Of these two modes of existence, the one vegetative, 
 the other animal, the former appeared to them the more essential, as 
 being more diffused, and consisting merely in the assimilation of nutri- 
 tive molecules, in the nutrition absolutely necessary to the preservation 
 of the living being,* who, as his substance is incessantly wasting, would 
 soon cease to exist, if these continual losses were not always repaired 
 by the act of nutrition. 
 
 Grimaud, Professor of Physiology at Montpellier, too soon lost to 
 the science whidh he cultivated as a philosopher, truly deserving that 
 name, adopted this simple and luminous division, developed it better 
 than had been done before him, and uniformly followed it in his lec- 
 tures and in his works.-f This division of the functions into internal, 
 
 * A r ant anima nutritiva etiam aliis inest, et prima et maxima communis facultas 
 animae, seeundum quam omnibus vivere inest. ARISTOT. de Anim. lib. ii. cap. 4. 
 
 j- In his MS. lectures on physiology, he seems to feel a complacency in that 
 division which he had in a manner appropriated to himself, by his happy illustra- 
 tions of it, and by the changes which he had introduced into it. In every lecture, 
 I might almost say in every page, he returns to this division, explains it, dilates, 
 and comments upon it. " The functions," says he, " may be divided into two 
 " great classes ; some are formed in the interior of the body, and exclusively belong
 
 64 CLASSIFICATION OF THE FUNCTIONS. 
 
 which he likewise calls digestive, and into external or locomotive, 
 lately brought forward under the name of organic and animal, the 
 former of which terms is quite inaccurate and defective, since it leads 
 to a belief that the animal life or that of relation is not confided to 
 organs, and that the vital instruments are solely employed on internal 
 life or of nutrition (Motus assimilationis, Bacon ; Bias alterativum, Van 
 Helmont) this division does not comprehend the whole of the phe-' 
 nomena, and does not embrace the, sum of the functions which are 
 performed in the animal economy. In fact, there are not found in the 
 two great classes which it establishes, the acts by which animals and 
 vegetables reproduce and perpetuate themselves, and immortalise the 
 duration of their species. All the functions destined to the preser- 
 vation of the species are not included ; they merely relate to the 
 functions subservient to the preservation of individuals. 
 
 I have, therefore, thought it right to include under two general 
 classes: 1, the functions which tend to the preservation of the indi- 
 vidual, and enable him to enjoy an isolated mode of existence ; 2, the 
 functions which belong to the preservation of the species, functions 
 without which man might exist, as we see in eunuchs, but without 
 which the human species would soon perish, from a loss of the power 
 of reproduction. In laying down these two great divisions, I have 
 merely considered the object and end which each function has to 
 fulfil. 
 
 Among the functions which are employed in the preservation of 
 the individual, some fulfil this office by assimilating to his own sub- 
 stance the food with which he is nourished ; the others, by establish- 
 ing, in a manner suited to his existence, his relations with the beings 
 which surround him. 
 
 The functions destined to the preservation of the species, may like- 
 wise be divided into two classes. Those of the first class require the 
 concourse of two sexes; they constitute generation, properly so called: 
 those of the second order, exclusively belong to the female, who, after 
 conception, is alone destined to bear, to nourish, to bring into the 
 world, and suckle the new being, the result of conception.* 
 
 " to it ; others take place outwardly, and belong to external objects," &c. The 
 digestive power presides, in his opinion, over the internal functions, whose object 
 is nutrition ; the locomotive power directs the external functions. " It is by 
 means of the organs of sense that the animal enlarges his existence, that he applies 
 and distributes it to the surrounding objects, and takes cognizance of the qua- 
 lities in those objects which concern him ; it is by means of the muscles essen- 
 tially obedient to the organs of sense, that he adapts himself to those objects, 
 that he places himself in a manner suited to the mode of their activity," &c. 
 * The classification of the functions which Richerand has adopted, with a slight 
 modification, from Grimaud, nearly agrees with the one more generally followed
 
 CLASSIFICATION OF THE FUNCTIONS. 65 
 
 The internal, assimilating, or nutritive functions concur in the 
 same end, and all serve to the elaboration of the nutritive matter. The 
 aliment once admitted into the body is subjected to the action of the 
 digestive organs, which separate its nutritive parts ; the absorbents 
 take it up, and convey it into the mass of fluids ; the circulatory sys- 
 tem conveys it to all the parts of the body, and makes it flow towards 
 the organs ; the lungs and the secretory glands supply it with certain 
 elements, and deprive it of others, alter, modify, and animalise it : in 
 fine, nutrition, which may be considered as the complement of assimi- 
 lating functions, whose object it is to provide for the maintenance and 
 growth of the organs, applies to them this animalised substance, 
 assimilated by successive acts, when it has become quite similar to 
 them. 
 
 Several, however, of these functions serve at once to preserve and 
 to destroy : absorption, which takes up extraneous molecules, to be 
 employed in the growth of the organs, takes up equally the organic 
 molecules which are detached by motion, friction, heat, and all the 
 other physical, chemical, and vital causes : the action of the heart and 
 of the blood-vessels sends these fragments, together with the parts 
 truly recrementitious, towards the lungs, which, at the same time that 
 they bring about a combination of the nutritive parts with the oxygen 
 of the atmosphere, separate from the blood the materials which can no 
 longer be employed in nourishing the organs ; the same power propels 
 them towards the secretory glands, which not only purify what is 
 liquid, by separating from it that which cannot without danger remain 
 in the animal economy, but which likewise elaborate or prepare pecu- 
 liar fluids, some of which are results of the act of nutrition, are em- 
 ployed in that act, and impart to the substances on which it is per- 
 formed a certain degree of animalisation (as to the bile and saliva), 
 while the others seem to be intermediate states, which the nutritive 
 particles of the food are obliged to undergo, before complete animali- 
 sation ; such are the serous fluids and the fat. 
 
 It might perhaps seem more in conformity to the order of nature, 
 to have combined the account of respiration with that of the circula- 
 tion, by treating of the course of the venous blood, after the action of 
 the absorbent vessels, with which the veins have so much analogy; 
 then to have treated of the phenomena of respiration, or of the con- 
 by the best modern physiologists. Sprengel arranges them into the vegetative, 
 the sensiferous, and the generative. Cuvier forms but too classes, the vital and 
 animal. Magendie and Adelon divide them into functions of relation, functions 
 of nutrition, and functions of generation. Lenhossek, professor of anatomy and 
 physiology in the university of Vienna, classes the functions into those of organic 
 life, of sensiferous or animal life, and those belonging to generation. Dr. Bostock 
 admits only two classes, the contractile and sensitive. J. C. 
 
 T
 
 66 CLASSIFICATION OF THE FUNCTIONS. 
 
 version of the venous blood into arterial, and of the course of the latter 
 into all the parts of the body by the action of the heart and arteries ; 
 but the advantage which would be obtained from a method so contrary 
 to the common practice, which is to consider separately the functions 
 of circulation and respiration, appeared to me too unimportant to 
 justify its adoption. 
 
 The external or relative functions, equally connected by their 
 common destination, associate the individual to every thing that sur- 
 rounds him : the sensations, by warning him of the presence of objects 
 which may be useful or injurious to him ; motion, by enabling him to 
 approach or avoid such objects, according as he perceives relations of 
 advantage or disadvantage, according as the opposite sensations of 
 pain or pleasure result from his action on them, or from theirs on him. 
 In fine, voice and speech give him communication with beings enjoying 
 the same means of communication, and that without a necessity of 
 motion. The brain is the principal organ of these functions, as the 
 system of circulation is the centre of the assimilating functions. All 
 the impressions received by the organs of sense are transmitted to the 
 brain, and from the brain determinations arise, as well as the volun- 
 tary motions and the voice. The sanguineous system receives the 
 molecules destined to nutrition, and those which are to be thrown out 
 of the body. The sensitive and circulatory systems are the only sys- 
 tems provided with a centre (the brain and the heart), which extend to 
 all parts of the body, by emanations originating from that organ, or 
 terminating in it (the nerves, the arteries, and veins): and as the 
 motions and the voice depend on sensation, and are immediately 
 connected with it as necessary results, so respiration, secretion, and 
 nutrition, are, in a manner, but consequences of the circulation which 
 distributes the blood to all the organs, in order that these may pro- 
 duce on it various changes, which constitute respiration, secretion, and 
 nutrition. They are, if I may anticipate what is to come hereafter, 
 only different kinds of secretion that take place at the expense of the 
 different principles contained in the blood. 
 
 The circulation, which holds the functions of nutrition in a kind of 
 dependence, subjects the brain, which is the principal organ of the 
 external functions, to an influence still more immediate and indis- 
 pensable. The muscular motions are not less under its influence. It 
 is the first function that is apparent in the embryo, whose evolution it 
 brings about : in natural death, of all the functions, it is the last to 
 cease. These reasons justify Haller for having placed the circulation 
 in the first order, and for having begun by its history his great work 
 on physiology. I enter into this digression only to expose the absur- 
 dity of the claims of some authors, who, because they have varied the 
 methodical order of the functions, broken the series, or made the
 
 
 CLASSIFICATION OF THE FUNCTIONS. 67 
 
 slightest changes, for example, by placing the history of the functions 
 of smell and taste before the account of the internal or nutritive func- 
 tions, think they have totally changed the aspect of the science: 
 pitiful sophists, who accumulate subtleties instead of facts and ideas. 
 
 In warm and red-blooded animals, the nutritive functions, diges- 
 tion, absorption, circulation, respiration, the secretions, and digestion, 
 are performed as in man, and in that respect there exist between them, 
 very slight differences : nay, in some animals, these functions are per- 
 formed with much more energy. Thus several animals digest sub- 
 stances on which our own organs produce no effect, and others (birds) 
 have a more rapid circulation, a more active nutrition, and evolve more 
 heat. But not one of them is as well provided with organs to keep up 
 intercourse, as a living being, with the surrounding objects. In no 
 one animal are the senses possessed of the same degree of perfection ; 
 the eagle, whose sight is so piercing, has a very dull sense of touch, 
 taste, and smell. The dog, whose smell is exquisite, has a very ordinary 
 extent of sight : in him the taste and touch are equally imperfect 
 his touch, in the perfection of which no animal comes up to man, has 
 not been improved in delicacy, at the expense of the other senses. 
 The sight, the hearing, the taste and smell, preserve a great delicacy, 
 when their sensibility has not been impaired by injudicious or too fre- 
 quent impressions. The sensitive centre is in no one better developed, 
 and fitter to direct safely the use of the organs of motion. No other 
 animal can articulate vocal sounds, so as to acquire speech. 
 
 This greater extension of life in man, from the number and per- 
 fection of his organs, makes him liable to many more diseases than 
 the other animals. It is with the human body as with those ma- 
 chines, which become more liable to be deranged, by increasing the 
 number of their wheels, with a view of obtaining more extensive /or 
 more varied effects. 
 
 All organised bodies are possessed of assimilating functions ; but 
 as assimilation requires means varying in number and power, according 
 to the nature of the being which performs it. The series of assimilating 
 phenomena commences in the plant by absorption, since it draws im- 
 mediately from the earth, the juices which it is to appropriate to 
 itself. Its absorbing system at the same time performs the functions 
 of a circulatory organ, or rather the circulation does not exist in 
 plants ; and the direct and progressive motion of the sap, which 
 ascends from the root towards the branches, and sometimes in a retro- 
 grade course from the branches towards the roots, cannot be com- 
 pared to the circulation of the fluids which takes place in man, and in 
 the animals which most resemble him, by means of a system of vessels 
 which every moment bring back the fluids to the same spot, and convey 
 them over the whole body, by making them describe a complete circle,
 
 68 
 
 CLASSIFICATION OF THE FUNCTIONS. 
 
 frequently even a double rotation, (animals with a single or double 
 circulation, that is, whose heart has one or two ventricles). Plants 
 breathe after their own manner, and produce a change in the atmo- 
 spherical air, by depriving it of its carbonic acid gas, the result of com-- 
 bustion and of animal respiration : so that, by a truly admirable reci- 
 procity, plants which decompose carbonic acid, and allow oxygen to 
 exhale, continually purify the air, which combustion and animal respira- 
 tion are incessantly contaminating.* , 
 
 The functions preservative of the species are common to animals 
 and plants. The organs by which these functions are performed, when 
 compared in these two kingdoms of nature, offer a resemblance which 
 has struck all naturalists, and has led them to observe, that of all the 
 acts of vegetable life, no one is more analogous to the animal economy 
 than that by which fecundation is effected. 
 
 I shall not here explain the general characters of the two 
 orders of functions which are subservient to the preservation of the 
 species : the differences which belong to them are pointed out in seve- 
 ral parts of this work.f I shall merely observe, with the authors who 
 have considered them generally, that they are in an inverse ratio to 
 each other; so that, in proportion as the activity of the assimilating 
 functions increases, that of the external functions is abated. Grimaud 
 has, in the most complete manner, illustrated this idea of the constant 
 opposition which exists between those two series of actions, over which, 
 in the opinion of that physician, there preside two powers, which he 
 calls locomotive and digestive, It is in no kind of animals more dis- 
 
 * This opinion originated with Priestley, and was generally adopted, in oppo- 
 sition to the experience of his contemporary, the celebrated Scheele. More 
 modern physiologists, especially Ellis, Gilby, and T. de Saussure, have shewn, 
 by well-conducted experiments, that all plants, whether growing in absolute dark- 
 ness, in the shade, or when not exposed to the direct rays of the sun, " are con- 
 stantly removing a quantity of oxygen from the atmosphere, and substituting an 
 equal volume of carbonic acid." Thus far these philosophers nearly agree. They 
 differ, however, very widely respecting the manner in which this change is effected. 
 Ellis supposes that the leaves, flowers, fruits, stems, and roots of plants emit 
 carbonaceous matter, which combines with the oxygen of the surrounding air. 
 Gilby and Saussure are of opinion that the oxygen is absorbed by the respiratory 
 organs, and that the carbonic acid is formed within the plant. 
 
 Although vegetables, under the ordinary circumstances of their growth, con- 
 sume oxygen during respiration, and disengage carbonic acid, yet, according as their 
 situation and particular condition may require, they partially absorb the carbonic 
 acid from the air, convert it to their use, decompose it, and emit the oxygen which 
 results from the decomposition, especially when they are exposed to the sun's rays. 
 The illustration of this subject belongs to vegetable physiology J. C. 
 
 f Especially in the account of living beings, Sect. V. of the Preliminary Dis- 
 course, articles sleep and foetus. It is impossible at present to go over all these 
 distinctions, without entering into useless and disagreeable repetitions.
 
 CLASSIFICATION OF THE FUNCTIONS. 69 
 
 tinct than in the carnivorous, which possess organs of sense of the 
 greatest delicacy, together with muscles capable of prodigious efforts, 
 and yet powers of assimilation so feeble that their food cannot be 
 digested, unless it be composed of materials analogous in composition 
 to their own organs.* 
 
 Too much importance should not be attached to this classification; 
 like all other divisions, it is purely hypothetical. All is connected 
 together, all is co-ordinate in the animal economy ; the functions are 
 linked together, and depend on one another, and are performed simul- 
 taneously; all represent a circle of which it is not possible to mark 
 the beginning or the end. In circulum abeunt (Hippocrates). In man, 
 while awake, digestion, absorption, circulation, respiration, secretion, 
 nutrition, sensation, motion, voice, and even generation, may be per- 
 formed at the same time ; but whoever, in the study of the animal 
 economy, should bestow his attention on this simultaneous exertion 
 of th'e functions, would acquire but a very confused knowledge of 
 them.f 
 
 By becoming familiar with these abstractions, one might soon mis- 
 take them for realities, and even go the length of seeing two dis- 
 tinct lives in the same individual ; one would be apt to assign, as the 
 character of internal life, that it is carried on by organs independent 
 of the will, although this faculty of the mind presides over the pheno- 
 mena of respiration, of mastication, and of the expulsion of the urine 
 and fseces; one might consider life as intrusted to unsymmetrical organs, 
 although the heart, the lungs, and the kidneys, are evidently symme- 
 trical ; and might fancy it to exist in the foetus, which neither breathes 
 nor digests, &c. Nothing in the animal economy, said Galen, is 
 ruled by invariable laws, or can be subject to the same accurate 
 
 * In carnivorous animals the power of digestion is exceedingly weak, but their 
 muscles are very powerful. This relative force of the muscles was necessary in 
 carnivorous animals, as they live by depredations and slaughter, as their instinct, 
 in unison with their organisation, sets them constantly at war with every thing 
 that has life, and as their subsistence depends on their being victorious in their 
 
 battles to which nature incessantly calls them GRIMAUD, first Memoir on 
 
 Nutrition. 
 
 f~ The division which I lay down is not to be strictly adopted, and as being ab- 
 solutely true. It is a mere hypothesis, to be attended to only in so far as it assists 
 in arranging one's ideas in a more orderly manner. For every arrangement, even 
 when arbitrary, is useful in laying before us a great number of ideas, and in 
 thereby facilitating the comparison that is to" be instituted among them. All the 
 acts of Nature are so connected, and are linked together in so close a union, and 
 she passes from the one to the other by such uniform motions, and by gradations 
 so insensible and so adjusted, as to leave no space for us to lay down the lines of 
 separation or demarcation, which we may choose to draw. All our methods of 
 classing and arranging the productions of nature are mere abstractions of the mind, 
 which does not consider things as they really are, but which attends to certain 
 qualities, and neglects or rejects all the rest. GRIMAUD, Lecturet on Physiology.
 
 70 CLASSIFICATION OF THE FUNCTION'S. 
 
 results and calculations as an inanimate machine. (Nil est in corpore 
 viventi plan& sincerum. Galen.) Thus respiration, which connects 
 the external and assimilating functions, furnishes the blood with the 
 principle which is to keep up the action of the brain, and to excite 
 muscular contractions. On the other hand, the motion of the muscles 
 is of use in the distribution of the humours, and concurs in the pheno- 
 mena of assimilation. The brain, by means of the eighth pair of 
 nerves, holds influence over the stomach. The sensations of taste 
 and smell seem to preside in an especial manner over the choice of 
 food and of air, and to belong rather to the digestive and respiratory 
 functions than to those of the intellect or of thought. 
 
 We have seen in this kind of general introduction of the study of 
 physiology what idea is to be formed of that science as well as of life, 
 the study of which is its object ; into how many classes the beings in 
 nature may be divided, and into how many elements they are resolv- 
 able ; what differences exist between inorganised and organised and 
 living bodies, between plants and animals; how life is complicated, 
 modified, and extended, in the immense series of beings which are 
 endowed with it, from the plant to man ; and in further particularising 
 the object under our consideration, we have examined what are the organs 
 which, by their union, form the human machine ; what powers govern 
 the exercise of their functions. Then we have laid down the funda- 
 mental laws of sensibility and contractility ; we have spoken of sympa- 
 thies and habits; of the internal nervous apparatus, which unites, 
 collects, and systematises the organs of the assimilating functions ; we 
 have endeavoured to determine from facts the existence of the cause 
 which subjects living beings to a set of laws very different from those 
 which inorganic matter obeys. The knowledge of these laws is the 
 light which is to guide us in the application to physiology of the acces- 
 sory sciences. Finally, in the arrangement of the objects which this 
 science considers, I have adopted a more simple and natural division 
 than any hitherto employed. 
 
 I shall close this Preliminary Discourse by saying a few words on 
 the order adopted in the distribution of the chapters. I might have 
 begun by a view of the external functions, as well as of those of assimi- 
 lation or nutrition, of sensation, or of digestion. I have given prefer- 
 ence to the functions of assimilation, because of all others they are the 
 most essential to existence, and their exercise is never interrupted from 
 the instant in which the embryo begins to live till death. In beginning 
 with an account of them, we imitate nature, therefore, who imparts to 
 man this mode of existence before she has connected him with outward 
 objects, and who does not deprive him of it until the organs of sense, 
 of motion, and of the voice, have completely ceased to act. 
 
 As to the course which has been followed in the arrangement of
 
 CLASSIFICATION OF THE FUNCTIONS. 71 
 
 the functions that belong to the same order, or which concur in the 
 same end, it was too well laid down by nature to allow us to depart 
 from it. I have thought it right that the consideration of the voice 
 should immediately precede that of generation, in order that the 
 arrangement might, at a glance, shew the connexion which exists 
 between their phenomena. Several animals use their voice only during 
 the season of love : the birds which sing at all times, have, during that 
 period, a more powerful and sonorous voice. When man becomes 
 capable of reproduction, his vocal organs suddenly become evolved, 
 as though nature had wished to inform him that it is through them 
 he is to express his desires to the gentle being who may sympathise in 
 them. The voice, therefore, serves as a natural connexion between the 
 external functions and those which are employed in the preservation of 
 the human species. 
 
 The voice, which leads so naturally from the functions which 
 establish our external relations to those whose end is the preservation 
 of the species, is still more intimately connected with motion. It is, in 
 a manner, the complement of the phenomena of locomotion; by 
 means of it our communication with external objects is rendered easier, 
 more prompt, and more extensive : it depends on muscular action, and 
 is the result of voluntary motion. Finally, these motions sometimes 
 supply the place of speech in pantomime, for example; and in the 
 greater number of cases the language of action concurs in adding to its 
 effect. Every thing, therefore, justifies me in placing this function 
 after motion, in separating it from respiration, with which every other 
 author has joined it, without considering that the relation between the 
 voice and respiration is purely anatomical, and can therefore in no- 
 wise apply to physiology. 
 
 I have placed after generation an abridged account of life and 
 death, in which will be found whatever did not belong to any of the 
 preceding divisions. The necessity of this Appendix, containing the 
 history of the different periods of life, that of the temperaments and 
 varieties of the human species, that of death and putrefaction, arises 
 from the impossibility of introducing into the particular history of the 
 functions these general phenomena in which they all participate.
 
 &f- 
 
 ' *' 
 
 FIRST CLASS. 
 
 THOSE FUNCTIONS WHICH TEND TO PRESE^E THE 
 INDIVIDUAL. 
 
 Ortrer. 
 
 FUNCTIONS OF ASSIMILATION; 
 
 OR, 
 
 FUNCTIONS WHICH ARE SUBSERVIENT TO THE PRESERVATION OP 
 
 THE INDIVIDUAL, BY ASSIMILATING TO HIS SUBSTANCE 
 
 THE FOOD BY WHICH HE IS NOURISHED. 
 

 
 CHAPTER I. 
 
 OF DIGESTION. 
 
 I. Definition of Digestion. II. General considerations on the Digestive Organs. 
 
 III. Of Food, solid and liquid IV. Of Hunger V. Of Thirst VI. to IX. 
 
 Of Mastication. X. and XI. Of Salivary Solution. XII. Of Deglutition. 
 
 XIII. Of the Abdomen. XIV. to XIX. Of Digestion in the Stomach : 
 various opinions respecting this process XX. to XXII. Of the Gastric Juice. 
 
 XXIII. Of the Uses of the Pylorus. XXIV. Of Vomiting XXV. Of 
 
 Digestion in the Duodenum XXVI. Of the Bile, and Biliary Apparatus 
 
 XXVII. Of the Uses of the Bile. XXVIII. Of the Actions of the small 
 
 Intestines XXIX. Of the Functions of the large Intestines XXX. Of 
 
 Faecation and Faecal Evacuation. XXXI. to XXXV. Of the Secretion and 
 Excretion of the Urine. XXXVI. Of the Physical Properties of the Urine. 
 XXXVII. and XXXVIII. Of the Chemical Properties of the Urine. XXXIX. 
 Of various States of the Urine. 
 
 I. DIGESTION is a function common to all animals, by which sub- 
 stances extraneous to them are introduced into their body, and 
 subjected to the action of a peculiar system of organs, their qualities 
 altered, and a new compound formed, fitted to their nourishment and 
 growth. 
 
 II. General considerations on the Digestive Organs. Animals 
 alone are provided with organs of digestion ; all of them, from man 
 down to the polypus, contain an alimentary cavity, variously shaped. 
 The existence of a digestive apparatus may, therefore, be taken as the 
 essential characteristic of the animal kind. In man this apparatus 
 consists of a long tube, extending from the mouth to the anus ; within 
 this canal there empty themselves the excretory ducts of several neigh- 
 bouring glands, that secrete fluids fit for changing, for liquefying, and 
 animalising the alimentary substance. The different parts of this 
 digestive tube are not of equal capacity ; at first, enlarged in the part 
 which forms the mouth and pharynx, it becomes narrower in the reso- 
 pkagus ; this last, dilating considerably, forms the stomach, which 
 again contracting, is continued down under the name of intestine. The 
 tube itself varies in size in different parts of its extent; and it is by the 
 consideration of these differences of size, that anatomists have prin- 
 cipally been guided in their divisions. 
 
 The length of the digestive tube is from five to six times the length 
 of the whole body in an adult; jt is greater in proportion in a child.
 
 76 OF DIGESTION. 
 
 At this age, likewise, digestion is more active, and proportioned to the 
 necessities of growth in the individual. The digestive cavity is in man 
 open at both extremities : in some animals, in the zoophyte for ex- 
 ample, one opening serves the purpose of mouth and of anus, receives 
 the food, and ejects the excrementitious remains. 
 
 The extent of the digestive canal is according to the nature of the 
 aliments on which the animals feed : the less those aliments are analo- 
 gous in their nature to the substance of the animal which they are to 
 nourish, the longer must they remain in his body to undergo the neces- 
 sary changes. Therefore, it is observed, that the intestine of grami- 
 nivorous animals is very long, their stomach very capacious, and often 
 complex, while carnivorous animals have their intestinal canal short 
 and strait, and so arranged, that the animal substances which are most 
 nourishing, in least bulk, of easy and rapid digestion, and which, by too 
 long a stay in the intestines might become putrid, pass readily through 
 it. In this respect man holds a middle station between those animals 
 which feed on vegetables, and those which feed on animal substances. 
 He is, therefore, equally fitted for these two kinds of food ; he is 
 neither exclusively herbivorous nor carnivorous, but omnivorous, or 
 polyphagous. This question, of such easy solution, has long employed 
 physicians, naturalists, and philosophers ; each bringing, in favour of 
 his opinion, very plausible arguments, drawn from the form and num- 
 ber of the teeth, from the length of the intestinal canal, from the force 
 of its parietes, &c. 
 
 The parietes of the digestive tube are essentially muscular ; a 
 mucous membrane lines its inside, forming within it various folds ; 
 /astly, a third coat is accidentally placed over the other two, and is 
 furnished by the pleura to the oasophagus, and by the peritoneum to 
 the stomach, as well as to the intestinal canal. 
 
 The characteristic of this third coat is, that it does not cover the 
 whole surface of the parts of the tube to which it is applied. The 
 muscular coat may be considered as a long hollow muscle, extending 
 from the mouth to the anus, and formed, throughout almost the whole 
 of its length, by two layers of fibres; the one set longitudinal, the other 
 circular. The will directs the motions of the two extremities, while 
 the rest of its course is not under its control. In the cells of the tissue 
 which unites its surfaces to the other coats, fat never accumulates, 
 which might have impeded its contractions, and straitened, and even 
 obliterated, the tube along which the food was to pass.* 
 
 The digestive tube comprehends; 1, the mouth; 2, the pharynx; 3, the 
 oesophagus ; 4, the stomach ; 5, the small intestines ; 6, the large intestines ; and, 
 7, the anus. The commencement and termination of this apparatus are subjected, 
 but not completely, to the influence of the will. Volition and sensation are dis- 
 tinctly evinced in the mouth and pharynx : in the oesophagus and stomach the
 
 OF DIGESTION. KINDS OF FOOD. 77 
 
 III. Of food, solid and liquid. The aliments which nourish man 
 are obtained from vegetables or from animals. The mineral kingdom- 
 furnishes only condiments, medicinal substances, or poisons.* 
 
 By aliment is meant whatever substance affords nutrition, or what- 
 ever is capable of being acted upon by the organs of digestion. Sub- 
 stances which resist the digestive action, those which the gastric juice 
 cannot sheath-e, whose asperities it cannot soften down, whose nature 
 it cannot change, possess, to a certain degree, the power of disturbing 
 the action of the digestive tube, which revolts from whatever it cannot 
 overcome : there is no essential difference between a medicinal sub- 
 stance and a poison. Our most active remedies are obtained from 
 among the poisonous substances : tartar emetic, corrosive sublimate, 
 opium all of them remedies of so much efficacy in skilful hands 
 when administered unseasonably, or in too strong doses, act as most 
 violent poisons : they forcibly resist the digestive powers, and furnish 
 them nothing to be acted upon, while mild and inert substances yield 
 to these powers, and come under the class of aliments. What then is 
 to be thought of our ptisans, of chicken and veal broth, and other such 
 remedies ? That they are employed to deceive the hunger and thirst 
 of the patient, to prevent his receiving into his stomach substances 
 whose laborious digestion would exhaust the strength required for the 
 cure of the disease ; that they are mere precautions of regimen ; and 
 that he who most varies this kind of resource, can only be said to 
 adopt a treatment of expectation, leaving to nature alone the care of 
 exciting those salutary motions which are to bring about a cure. Why 
 do certain vegetable purgatives, as manna and tamarinds, produce so 
 little effect, even though given in large doses ? Because these sub- 
 stances contain many nutritious particles capable of being assimilated, 
 so that strong constitutions digest them, and completely neutralise 
 
 influence of the will gradually disappears, and sensation becomes imperfect and 
 peculiar. It is in consequence of the distribution of voluntary nerves, in greater or 
 less number, to the extremities of the alimentary canal, and of the accession of 
 their influence to the ganglial system of nerves which chiefly supply the digestive 
 apparatus, that many of the sensations and operations which belong to its upper 
 portion, as the pharynx, resophagus, and the stomach, are so peculiar, and so difficult 
 of explanation. J. C. 
 
 * Magendie arranges the aliments which nourish man according to the imme- 
 diate principle which predominates in their composition. After this manner he 
 distinguishes nine classes; namely, farinaceous, mucilaginous, saccharine, acidu- 
 lated, oleaginous, milky or cheesy, gelatinous, albuminous, and fibrinous aliments. 
 Dr. Prout, in the paper which lately obtained the Copleyan Medal of the Royal 
 Society, considers that the food of the higher animals may be arranged in three 
 classes : the saccharine, the oily, and the albuminous. The first consists of sugars, 
 starches, gums, acetic acid, and some other analogous substances ; the second, of 
 oils, fats, alcohol, &c. ; the third, of other animal matters, and vegetable gluten, 
 which abounds in wheat. J. C,
 
 78 OF DIGESTION. KINDS OF FOOD. 
 
 their irritating or purgative qualities. An animal or vegetable sub- 
 stance, though essentially nutritious, may act as a medicine, or even as 
 a poison, when, in consequence of the extreme debility of the digestive 
 tube, or because it has not been sufficiently divided by the organs of 
 mastication, it resists the digestive action. Thus surfeits are brought 
 on, because the stomach is debilitated, because it is oppressed by too 
 great a mass of substances, or because, having been imperfectly tritu- 
 rated, they are insoluble. It is on considerations of this kind that the 
 true foundations of materia medica are laid. 
 
 Mineral substances are of a nature too heterogeneous to our own 
 to admit of being converted into our substance. It appears that their 
 elements require the elaboration of vegetable life ; hence it has been 
 justly observed, that plants are laboratories in which nature prepares 
 the food of animals. 
 
 Aliments obtained from plants are less nutritious than those fur- 
 nished by the animal kingdom, because in a given bulk they contain 
 fewer parts than can be assimilated to our own substance. Of all the 
 parts of vegetables, the most nourishing is their amylaceous fsecula ; but 
 it yields the more readily to the action of the digestive organs from 
 having already experienced an incipient fermentation ; on that account 
 leavened bread is the best of vegetable aliments. The flesh of young 
 animals is less nourishing than that of the full-grown, although, at an 
 early age, the flesh of the former abounds more in gelatinous juices; 
 for this abundant gelatine is also much more watery. 
 
 However various our aliments may be, the action of our organs 
 always separates from them the same nutritious principles : in fact, 
 whether we live exclusively on animal or vegetable substances, the in- 
 ternal composition of our organs does not alter ; an evident proof, that 
 the substance which we obtain from aliments to incorporate with our 
 own, is always the same ; and this affords an explanation of the saying 
 of the father of physic, " There is but one food, but there exist several 
 forms of food." 
 
 Attempts have been made to ascertain the nature of this alimentary 
 principle, common to all nutritive substances, and it is conjectured, 
 with some probability, that it must be analogous to gummy, mucilagi- 
 nous, or saccharine substances : they are all formed from hydrogen and 
 carbon ; and are well known to differ chemically only in the different 
 proportions of oxygen which they contain. Thus sugar is a kind of 
 gum, containing a considerable quantity of oxygen, and which is re- 
 duced, in a certain degree, to a state of starch, when brought to a very 
 fine powder by means of a rasp ; for the friction, disengaging a portion 
 of its oxygen, deprives it in part of its flavour, and leaves it an insipid 
 taste, similar to that of farinaceous substances. Nothing, in fact, nourishes 
 better, more quickly, and from a smaller bulk, than substances of this
 
 OF DIGESTION. KINDS OF FOOD. 79 
 
 kind. The Arab crosses the vast plains of the desert, and supports 
 himself by swallowing a small quantity of gum arabic. The nourishing 
 quality of animal and vegetable jellies is well known ; saccharine sub- 
 stances soon cloy the appetite of those who are fondest of them. In 
 decrepit old age, some persons live exclusively on sugar: I know 
 several in that condition, who spend the day in chewing this substance, 
 which is a laborious employment for their feeble and toothless jaws.* 
 Lastly, milk, the sole nourishment of the early periods of life, contains 
 a great proportion of gelatinous and saccharine matter. 
 
 Though man, destined to live in all latitudes, is formed to subsist 
 on all kinds of food, it has been -observed that the inhabitants of 
 warm climates generally prefer a vegetable diet.f The Bramins in 
 
 * Magendie concluded, from his experiments, that no animal seems capable of 
 deriving nutriment from any substance that does not contain some portion of 
 azote. There are, however, many circumstances which prove the contrary. Adan- 
 son asserts, that the Nomadic Moors have scarcely any other food than gum 
 senega. Hasselquist relates, that a caravan of Abyssinians, consisting of 1000 
 persons, subsisted for two months on a stock of gum arabic alone, which they found 
 among their merchandise ; and it is well known, that negroes, and individuals 
 otherwise imperfectly fed, soon become fat from the mastication of the sugar-cane. 
 A case, which fully exemplifies the nutritious quality of sugar, lately came under 
 our observation, in a lady, about the middle age, who consulted us respecting 
 great and increasing corpulency. Her countenance was full, clear, and florid ; her 
 pulse strong ; her health excellent ; and her strength very considerable. She par. 
 took of animal food only once in a day, and then in a very small quantity. She 
 never took suppers, and was very moderate in the use of fluids. She had always 
 taken considerable exercise on foot, and even up to the period at which we saw 
 her, she resorted to it as much as the great bulk of her body could permit. The 
 secret, however, of her increasing obesity was disclosed, when she mentioned her 
 insatiable desire for refined sugar, which she almost hourly made use of, frequently 
 to the extent of one pound weight daily. She considered it her chief article of 
 diet. She reckoned the average quantity which she used at about three-fourths 
 of a pound in the day. Tea or coffee was taken by her sweetened in the usual 
 way. She ate the sugar in the solid state, and unaccompanied with any other 
 article of diet ; the finest sort only was relished. Her digestive functions were in 
 a perfect condition ; neither cardialgia, acidity, nor flatulence, were complained of. 
 Her teeth were sound. She found her corpulence supervene to a spare habit of body, 
 some time after the practice of eating sugar was acquired. She thought that the 
 obesity increased with the increase in the quantity of sugar which she consumed. 
 The habit had become so confirmed, at the time when we saw her, that she con- 
 ceived it to be quite impossible to relinquish it J. C. 
 
 f The inhabitants of warm climates, who are subjected, in consequence of the 
 nature of the situation in which they live, to a moist and miasmatous atmosphere, 
 generally adapt their vegetable diet, as much as may be in their power, 19 the cir- 
 cumstances in which they are placed. They endeavour, by adding a large propor- 
 tion of the stimulant and tonic seeds of plants to their aliments, to counteract 
 the debilitating and septic influence of the air which they breathe, and of other seda- 
 tive causes of disease to which they are more or less exposed. Hot spices are their 
 chief condiments, and even prophylactics : without the use of these their very ali-
 
 80 OF DIGESTION. KINDS OF FOOD. 
 
 India, the inhabitants of the Canary Islands, and of the Brazils, &c. 
 who live almost exclusively on herbs, grain, and roots, inhabit a cli- 
 mate against the excessive heat of which they have to seek means of 
 protection ; now, the digestion of vegetables is attended with less heat 
 and irritation. The philosophical or religious sects, by which the absti- 
 nence from animal food was considered as a meritorious act, were all 
 instituted in warm climates. The school of Pythagoras flourished in 
 Greece ; and the anchorets, who in the. beginning of the Christian reli- 
 gion peopled the solitudes of Thebais, could not have endured such 
 long fastings, or supported themselves on dates and water, in a more 
 severe climate ; so that the monks that removed into different parts of 
 Europe were obliged to relax from the excessive severity of such a 
 regimen, and yielded to their resistible influence of the climate : thus, 
 the most austere were induced to add to vegetables, which formed the 
 base of their food, eggs, butter, fish, and even water-fowl. In books 
 of casuistry it may be seen on what ridiculous grounds there was granted 
 a dispensation in favour of plovers, of water hens, wild ducks, snipes, 
 and scoters ; birds whose brown flesh, more animalised and more heat- 
 ing, ought to have been proscribed from the kitchens of monasteries 
 much more strictly than that of common poultry. 
 
 Consider what is the alimentary regimen of the different nations on 
 the face of the earth, and you will see that a vegetable diet is pre- 
 ferred by the inhabitants of warm countries : to them sobriety is an 
 easy virtue ; it is a happy consequence of the climate. Northern 
 nations, on the contrary, are voracious from instinct and necessity. 
 They swallow enormous quantities of food, and prefer those substances 
 which in digestion produce the most heat. Obliged to struggle inces- 
 santly against the action of cold, which tends to benumb the vital 
 powers, to suspend every organic motion, their life is but a continual 
 act of resistance to external influences. Let us not reproach them 
 with their voracity and their avidity for ardent spirits and fermented 
 liquors. Those nations that inhabit the confines of the habitable 
 world, in which man is scarcely able to withstand the severity of the 
 climate, the inhabitants of Kamtschatka, the Samoiedes, live on fish 
 that, in the heaps in which they are piled up, have already undergone 
 a certain degree of putrefactive fermentation. Does not the use of a 
 food so acrid and heating, that in our climate it would inevitably be 
 attended with a febrile action, prove plainly the necessity of balancing, 
 
 ments would become a source of disease ; the various kinds of parasitical animals 
 which prey on man would abound to the most loathsome degree, and they would be 
 continually the subject of dysentery, and the other maladies which imperfect or im- 
 proper nourishment, and an unwholesome climate, induce. The hot spices are, to 
 individuals so circumstanced, more requisite than salt is to the inhabitants of 
 temperate or cold climates, who live chiefly on animal food. J. C.
 
 OF DIGESTION. KINDS OF FOOD. 81 
 
 by a vigorous inward excitement, the debilitating influence of powers 
 that are operating from without ? The abuse of spirituous liquors is 
 fatal to the European transported to the burning climate of the West 
 Indies; yet the Russian drinks spirituous liquors with a sort of impunity, 
 and lives on to an advanced age, amidst excesses under which an inha- 
 bitant of the south of Europe would sink. 
 
 This influence of climate affects alike the regimen of man in health 
 and that of man in sickness ; and it has been justly observed of medi- 
 cine, that it ought to vary according to the places in which it is prac- 
 tised. Barley, ptisan, honey, and a few other substances, the greater 
 part obtained. from the vegetable kingdom, sufficed to Hippocrates in 
 the treatment of diseases; his therapeutic treatment was, in almost every 
 case, soothing and refreshing. Physicians who practise in a climate 
 such as that of Greece, may imitate this simplicity of the father of 
 physic. Opium, bark, wine, spirits, aromatics, and the most active 
 cordials are, on the other hand, the medicines suited to the inhabitants 
 of the North. The English physicians use, freely and without risk, 
 these medicines, which elsewhere would be attended with the utmost 
 danger. 
 
 Simple aqueous drinks promote digestion,* by facilitating the solu- 
 tion of the solids, by serving as a vehicle to their divided parts ; and 
 when rendered active by saline or other substances, as spirituous 
 liquors are by alcohol, they are further useful in stimulating the organs 
 and exciting their action. 
 
 The least compound drinks are possessed, in different degrees, of 
 this double property of dissolving solid aliments and of stimulating the 
 digestive organs. The purest water is rendered stimulating by the air 
 and by the salts which it contains in different proportions ; and to the 
 want of that stimulating quality is to be attributed the difficult diges- 
 tion of distilled water. 
 
 The drinks best suited to the wants of the animal economy are 
 those in which the stimulating principles are blended in due propor- 
 tions with the water which holds them in solution. But almost all the 
 fluids which we drink contain a certain proportion of nutritious par- 
 ticles. Wine, for example, contains these nutritive particles in greater 
 quantity, as it is the produce of a warmer climate, and as saccharine 
 matter predominates in its composition. Thus, Spanish wines are in 
 themselves nourishing, and are perhaps fitter to satisfy hunger than to 
 allay thirst; while the acidulous Rhenish wines, which are merely 
 
 * Simple fluids promote this process only when they are taken in small quan- 
 tity, and when thirst indicates the propriety of resorting to them. If they are 
 used so largely as to dilute in too great a degree the gastric juice, and to over- 
 distend the stomach, especially during meals, they evidently retard digestion 
 
 '
 
 82 OF HUNGER AND THIRST. 
 
 thirst-allaying, scarcely contain any cordial quality. Between the two 
 extremes are the French wines, which possess, in a nearly equal degree, 
 the treble advantage of diluting the fluids, of stimulating the organs, 
 and of furnishing to the animal economy materials of nutrition. 
 
 IV. Of hunger and thirst. By the words hunger and thirst are 
 meant two sensations, which warn us of the necessity of repairing the 
 loss which our body is continually undergoing from the action of the 
 vital principle. Their nature, as is well observed by M. Gall, is not 
 better known than that of thought. Let us endeavour to explain the 
 phenomena by which they are attended. 
 
 The effects of a protracted abstinence are, a diminution of the 
 weight of the body a diminution which becomes sensible in the course 
 of twenty -four hours, a wasting of the body from the loss of fat, dis- 
 coloration of the fluids, especially the blood, loss of strength, exces- 
 sive sensibility, sleeplessness, with painful sensations in the epigastric 
 region.* 
 
 Death from inanition is most easily brought on in those who are 
 young and robust. Thus, the unfortunate father, whose horrible story 
 has been narrated by Dante, condemned to die of hunger, and shut up 
 with his children in a dark dungeon, died the last, on the eighth day, 
 after having witnessed, in the convulsions of rage and despair, the death 
 of his four sons, unhappy victims of the most execrable vengeance ever 
 recorded in the history of man. Haller has related, in his great work 
 on physiology, several instances of prolonged abstinence : if we are to 
 give credit to these accounts, some of which are deficient in the degree 
 of authenticity required to warrant belief, persons have been known to 
 pass eighteen months, two, three, four, five, six, seven, and even ten 
 years, without taking any nourishment. In the Memoirs of the Edin- 
 burgh Society is found the history of a worrTan who lived on whey only 
 for fifty years. The subjects of these cases are mostly weak, infirm 
 women, living in obscurity and inaction, and in whom life, nearly ex- 
 tinct, just shewed itself in an almost insensible pulse, and an unfrequent 
 and indistinct respiration. It is a fact well worthy of observation, that 
 the muscles and viscera of some of them, when examined after death, 
 shone with a light evidently phosphoric.f Can it be that phosphorus 
 is the result of the lowest degree of animalisation ? It may be easily 
 conceived, that living in a manner on their own substance, the fluids in 
 such persons have been frequently subjected to the causes which pro- 
 duce assimilation and animalisation, and have undergone the greatest 
 alteration of which they are capable. 
 
 The proximate cause of hunger has by some been conceived to 
 
 * See APPENDIX, Note I. 
 
 f Nitidissima viscera sunt animalium fame enectorum, et argentei fibrarum fas. 
 etculi HALLER, Elem. Phys. torn. vi. p. 183.
 
 OF HUKGER. 83 
 
 depend on the friction of the nervous papillse of the empty stomach on 
 each other ; by others it has been imputed to the irritation produced 
 on its parietes by the accumulation of the gastric juice. It has been 
 thought to depend on the lassitude attending the permanent contrac- 
 tion of the muscular fibres of the stomach, and on the compression and 
 creasing of the nerves during that permanent constriction ; on the 
 dragging down of the diaphragm by the liver and spleen, when the 
 stomach and intestines, being empty, cease to support those viscera, a 
 dragging which is the greater, as a new mode of circulation takes 
 place in the viscera, which are supplied with blood by the coeliac artery, 
 and while the stomach receives less blood, the spleen and liver increase 
 in weight and size, because their supply is increased.* 
 
 Those who maintain that hunger depends on the friction of the 
 parietes of the stomach against each other, when brought together 
 in an empty state, adduce the example of serpents, whose stomach is 
 purely membranous, and who endure hunger a long time ; while fowls, 
 whose powerful and muscular stomach is able to contract strongly on 
 itself, endure it with difficulty. But, to say nothing of the great differ- 
 ence of vitality in the organs of a bird and of a reptile, the stomach 
 which continues closing on itself as it is emptied, may contract to such 
 a degree as scarcely to equal in size a small intestine, without its fol- 
 lowing, as a necessary consequence, that the parietes which are in 
 contact should exert on each other any friction on which the sensation 
 of hunger may depend. In fact, the presence of food is necessary to 
 
 * The most prevalent opinions respecting the proximate causes of hunger are, 
 that it is owing to the action of the gastric juice on the stomach, or that it is a sen- 
 sation connected with the contracted state of this organ and the corrugation of its 
 internal membrane. It is not unlikely that both causes may contribute to the 
 production of this sensation, in consequence of the impression which they may 
 make on the sentient extremities of these cerebro-spinal nerves, which reinforce the 
 vital operations of the stomach. The state of the absorbent vessels, and the irrita- 
 tion which the gastric fluid induces on the extremities of those vessels during an 
 empty state of this viscus, ought also to be taken into consideration in our specu- 
 lations respecting the origin of this sensation. 
 
 The following experiment of Dr. W. Philip, detailed in his excellent work on 
 indigestion, appears to confirm the opinion that the influence of the gastric juice on 
 the stomach is, in some way or other, productive of the sense of hunger. 
 
 " A person in good health was prevailed upon to abstain from eating for more 
 than twenty hours, and further to increase the appetite by more exercise than 
 usual. At the end of this time he was very hungry ; but, instead of eating, ex- 
 cited vomiting by drinking warm water and irritating the fauces. The water 
 returned mixed only with a ropy fluid, such as the gastric fluid is described to be 
 by Spallanzani, or as I have myself obtained it from the stomach of a crow. After 
 ' this operation, not only all desire to eat was removed, but a degree of disgust was 
 excited by seeing others eat. He, however, was prevailed upon to take a little 
 milk and bread, which in a very short time ran into the acetous fermentation, indi- 
 cated by flatulence and acid eructations." /. C.
 
 84 OF THIRST. 
 
 determine an action of the parietes of the stomach ; and as long as it 
 is empty, there is nothing to call forth such action. 
 
 Those who think that hunger is mechanically produced by the 
 weight of the spleen and liver, that keeps pulling down the diaphragm, 
 which the empty stomach no longer bears up, observe, that it may be 
 appeased for a time, by supporting the abdominal viscera by means of 
 a wide girdle ; that hunger ceases as soon as the stomach is full, 
 before the food can have yielded to it any materials of nutrition. On 
 this hypothesis, which is purely mechanical, as that which explains 
 hunger by the irritation of the gastric juice, by the lassitude of the con- 
 tracted muscles, by the compression of the nerves, how shall we explain 
 the fact, that when the hour of a meal is over, hunger ceases for a 
 time? Ought not hunger, on the contrary, to be considered as a 
 nervous sensation which exists in the stomach, is communicated by sym- 
 pathy to all the other parts, and, keeping up an active and continuous 
 excitement in the organ in which it is principally seated, determines 
 into it the fluids from all parts? This phenomenon, like all those 
 which depend on nervous influence, is governed by the laws of habit, 
 by the influence of sleep, and of the passions of the mind, whose power 
 is so great, that literary men, absorbed in meditation and thought, have 
 been known entirely to forget that they required food. Every thing 
 which awakens the sensibility of the stomach, in a direct or sympathetic 
 manner, increases the appetite and occasions hunger. Thus, bulimia 
 depends sometimes on the irritation of a tape-worm in the organs of 
 digestion. The application of cold to the skin, by increasing from 
 sympathy the action of the stomach, has been known to occasion fames 
 canina, of which several instances are related by Plutarch (Life of 
 Brutus). Ardent spirits and highly seasoned food excite the appetite, 
 even when the stomach is over-filled. Whatever, on the contrary, 
 blunts or renders less acute the sensibility of the stomach, renders 
 more endurable or suspends the sensation of hunger. Thus, we are 
 told by travellers, that the Turkish dervises/and the Indian faquirs 
 endure long fasts, because they are in the habit of using opium, and 
 lull, in a manner, by this narcotic, the sensibility of the stomach. 
 Tepid and relaxing drinks impair the appetite ; the use of opiates sus- 
 pends suddenly the action of the stomach. 
 
 V. Of thirst. The blood, deprived of its serosity by insensible 
 perspiration and by internal exhalation, requires incessant dilution, by 
 the admixture of aqueous parts, to lessen its acrimony ; and as the 
 serosity is incessantly exhausting itself, the necessity for repairing that 
 loss is ever urgent.* The calls of thirst are still more absolute than 
 
 * As hunger seems to depend upon a certain condition of, or impression made 
 upon, the nerves distributed to the stomach, so thirst appears to arise from an
 
 OF THIRST- 85 
 
 those of hunger, and it is much less patiently endured. If it be not 
 satisfied, the blood and the fluids which ere formed from it become 
 more and more stimulating, -from the concentration of the saline 
 and other substances which they contain. The general irritation 
 gives rise to an acute fever, with heat and parching of the fauces, which 
 inflame, and may even become gangrenous, as happens in some cases 
 of hydrophobia. English sailors, who were becalmed, had exhausted 
 all their stock of fresh water, and were at a distance from land ; not 
 a drop of rain had for a long while cooled the atmosphere : after 
 having borne, for some time, the agonies of thirst, further increased 
 by the use of salt provisions, they resolved to drink their own urine. 
 This fluid, though very disgusting, allayed their thirst ; but at the end 
 of a few days it became so thick and acrid, that they were incapable 
 of swallowing a mouthful of it. Reduced to despair, they expected 
 a speedy death, when they fell in with a ship which restored them to 
 hope and life. Thirst is increased every time that the aqueous secre- 
 tions are increased; thus, it becomes distressing to a dropsical patient, 
 in whom the fluids are determined towards the seat of effusion. It is 
 excessive in diabetes, and in proportion to the increased quantity of 
 urine. In fever it is increased from the effect of perspiration, or because 
 in some of these affections, for example in bilious fevers, the blood 
 seems to become more acrid. Hence the advantage of cooling, diluting, 
 
 altered state of the fluids, which state modifies the functions of the vessels, 
 diminishes, or otherwise alters, the condition of the fluids secreted in the mouth and 
 fauces, and which impresses the nerves of sensation, in these situations, in such a 
 manner as to give rise to the phenomenon under consideration. 
 
 As the sense of thirst is induced by a state of the circulating fluids which would 
 become hurtful to the system were it to continue for any considerable period, so 
 this sensation is to be regarded in the light of a watchful guardian, which both 
 points out that state, and the only way in which it can be removed. 
 
 The superabundance of saline or stimulating substances in the blood is readily 
 indicated by the sensation induced in the mouth and fauces, which are the first 
 parts to evince the deleterious effects of these substances upon the animal economy : 
 hence the state of these organs is an important index to the condition of the circu- 
 lating fluids, and of the whole system, in a number of diseases. 
 
 Those physiologists who refer the operations of the living body to a galvanic 
 process, carried on by the nervous system on the fluids contained in the vascular, 
 especially in the capillaries, assign, as the proximate cause of thirst, a deficiency of 
 oxygen, and an abundance of the inflammable materials amongst those elements 
 which constitute the fluids circulating at the time in which the sensation is induced, 
 (Oxy genii autem defectum, et phlogisticorum abundantiam sitim adducere.} This,' 
 or a similar opinion, is entertained by Sprengel, Prochaska, Burdach, and Len- 
 hosseck. The arguments which these systematic writers on physiology adduce, 
 as well as the experiments of Dr. Philip, in support of the theory which as- 
 cribes the vital phenomena to galvanic processes taking place in the system, deserve 
 to be calmly considered before they are designated to be either visionary or unten- 
 able J. C.
 
 86 OF MASTICATION. 
 
 and refreshing drinks, administered copiously, with a view to correct the 
 temporary acrimony occasioned by the absence of a great quantity of 
 the serous parts of the blood, and to lessen the over-excitement of a 
 fluid become too stimulating. 
 
 The use of aqueous drink is not the most effectual method of allay- 
 ing thirst. A traveller, exposed to the scorching heat of summer, 
 finds it advantageous to mix spirits with plain water, which alone does 
 not stimulate sufficiently the mucous a,nd salivary glands, whose secre- 
 tion moistens the inside of the mouth and pharynx, and covers these 
 surfaces with the substance best calculated to suspend, at least for a 
 time, the erethism on which thirst appears to depend. 
 
 VI. Of mastication* The organs employed in the mastication 
 of the food are the lips, the jaws, and the teeth : with these are fur- 
 nished the muscles by which they are moved, and those which form the 
 parietes of the mouth. The motions of the lips are extremely varied, 
 and depend on the single or combined action of their muscles, by 
 which the greater part of the face is covered, and which may be enu- 
 merated as follows : Elevators of the upper lip (caninus, incisivus, 
 levatores communes labiorum et myrtiformes). Depressors of the under 
 lip (triangularis labiorum, quadratus gena). Abductors (buccinator, 
 zygomaticus major et minor, platysma-myoides). Constrictors (orbicu- 
 laris oris). 
 
 VII. The motions of the upper jaw are so confined, that some have 
 denied that it has any motion : it, nevertheless, rises a little when the 
 lower jaw descends; but it is principally by the depression of the 
 latter that the mouth is opened. The muscles at the back of the neck, 
 and that part of the digastric muscle nearest the mastoid process, pro- 
 duce a slight elevation of the upper jaw, which moves with the whole 
 head, to the bones of which it is firmly united. This connexion of the 
 upper jaw with the bones of the head renders this jaw less movable in 
 man than in the greater number of animals, in which, freed from the 
 enormous weight of the skull, it stretches out in front of that cavity, 
 over the lower jaw. As we follow downwards the scale of animal 
 existence, the motions of the upper jaw are seen to increase the further 
 we descend from the human species ; it is equal to that of the lower jaw 
 in the reptiles, and in several fishes ; hence the enormous dimensions 
 of the mouth of the crocodile and shark ; hence serpents frequently 
 swallow a prey of a bulk greater than their own, and would be suffo- 
 cated, but for the power they possess of suspending respiration for a 
 
 * The following operations are comprehended under the process of digestion, 
 namely, 1 , mastication ; 2, insalivation ; 3, deglutition ; 4, the action of the sto- 
 mach ; 5, the action of the duodenum ; 6, the action of the small intestines ; 
 7, the function of the caecum ; 8, the action of the colon ; 9, the expulsion of th 
 f*ces._,7. C.
 
 Of MASTICATION. 87 
 
 long time, and of waiting patiently till the gastric juice dissolves the 
 food as it is swallowed. 
 
 In the act of mastication the upper jaw may be considered as an 
 anvil, on which the lower jaw strikes as a movable hammer ; and the 
 motions of the under jaw, the pressure it exerts, and its efforts, would 
 soon have disturbed the connexion of the different bones of which the 
 face is formed, if this unsteady edifice, merely formed of bones in 
 juxta-position, or united by sutures, were not supported, and did not 
 transmit to the skull, the double effort which presses on it from below 
 upwards, and pushes it out laterally. Six vertical columns, the ascend- 
 ing apophyses of the superior maxillary bones, the orbitar processes of 
 the malar bones, and the vertical processes of the palate bones, support 
 and transmit the effort which takes place in the first direction, while 
 the zygomatic processes forcibly press the bones of the face against 
 each other, and powerfully resist separation outwardly or laterally. 
 The lower jaw falls by its own weight when its elevators are relaxed ; 
 the external pterygoid muscles, and those attached to the os hyoides, 
 complete this motion, the centre of which is not in the articulation of 
 the jaw to the temporal bones, but corresponds to a line that should 
 cross the coronoid processes a little above the angles of the jaw. It is 
 around this axis that, in falling, the lower jaw performs a motion of 
 rotation, by which its condyles are turned forwards, while its angles 
 are carried backwards. In children, the coronoid processes standing 
 off at a smaller distance from the body of the bone, of which they 
 have nearly the same direction, the centre of motion is always in the 
 glenoid cavities, which the condyles never quit, however much the 
 jaw may be depressed. By this arrangement, nature has guarded 
 against dislocation, which would have been frequent at an early period 
 of life from crying, during which the jaw is depressed beyond measure, 
 or when, not knowing the just proportion between the capacity of the 
 mouth and the size of the bodies they would put into it, children 
 endeavour to introduce those which it cannot receive. The lower jaw 
 forms a double bended lever of the third kind, in which the power 
 represented by the temporal masseter and internal pterygoid muscles 
 lies between the fulcrum and the resistance, at a smaller or greater 
 distance from the chin. 
 
 The mode of articulation of the jaw to the temporal bones allows it 
 only a motion upwards and downwards, in which the teeth of both 
 jaws meet like the blades of scissors, and a lateral motion, in which the 
 teeth glide on each other, producing a friction well calculated to grind 
 the food, which in the first part of the act of mastication was torn or 
 divided. 
 
 VIII. In carnivorous animals, the levator muscles of the under jaw 
 especially the temporals and masseters, are prodigiously large and
 
 88 OF MASTICATION. 
 
 powerful. In them the coronoid processes, to which the temporal 
 muscles are attached, are very prominent ; the condyles are received 
 into a very deep cavity ; while in herbivorous animals, on the contrary, 
 they are less strong and bulky, and the pterygoid muscles, by whose 
 action the lateral or grinding motion is performed, are stronger and 
 more marked. The glenoid cavities are also in them wide but shallow, 
 so that they allow the condyles to move freely on their surface. The 
 comparative power of the levator and, abductor muscles of the lower 
 jaw may be easily appreciated by viewing the temporal and zygomatic 
 fossae. Their depth is always in an inverse ratio, and proportioned to 
 the bulk of the muscles which they contain. In carnivorous animals, 
 the zygomatic- arch, to which the masseter is attached, is depressed, and 
 seems to have yielded to the effort of the muscle. In the point of 
 view which we have just taken, man holds a middle station between 
 carnivorous animals and x those which feed on vegetable substances ; 
 nothing, however, determines his nature better than the composition 
 of his dental arches. 
 
 IX. The small white and hard bones which form the dental arches, 
 are not s alike in all the animals whose jaws are furnished with them. 
 All have not, as man, three kinds of teeth. The laniary* teeth are 
 not to be met with in the numerous class of rodentia. Some are with- 
 out incisors ; the former appear more fitted to tear fibrous tissues which 
 offer much resistance. In carnivorous animals they are likewise very 
 long, and bent like curved pincers. The grinders are principally 
 employed in grinding substances previously divided by the laniary 
 
 * After the example of several naturalists, I have thought it right to give that 
 name to the canine teeth ; in the first place, because their principal use being to 
 lacerate or tear fibrous tissues, it is fit that they should have a name from their manner 
 of acting on the food, as is the case with the incisors and molares ; in the second 
 place, because the word canine may lead to an erroneous conception, by inducing 
 a belief that this kind of tooth belongs only to one kind of carnivorous animals, 
 while they are stronger and more distinct in the lion, the tiger, &c. 
 
 Such an explanation is indispensable, at a period when every body aspires to the 
 easy glory of introducing innovations in language. The invention of words is, 
 however, in the opinion of a celebrated female writer, a decided symptom of barren- 
 ness of ideas. 
 
 The teeth differ essentially from the other bones ; 1st, by thaacute sensibility with 
 which they are endowed; 2dly, by the nerves which may be traced into them, 
 while they seem to be wanting in every other part of the osseous system ; 3dly, 
 by the mode of distribution of the blood-vessels : these penetrate into them at an 
 aperture which is seen at the extremity of their root, and they expand in the 
 mucous membrane contained in the tooth, and which forms the most essential part 
 of the bone ; 4thly, by their not undergoing any change from exposure to the air, 
 a property which they owe to the enamel that covers them externally. It has 
 been said with justice, that nature, in sheathing the tooth with this covering, has 
 imitated the process of tempering, by means of which we harden the edge of steel 
 ur iron tools.
 
 SALIVARY SOLUTION. 89 
 
 teeth, which tear them, or by the incisors, which, in meeting as the 
 blades of scissors, fairly cut them through ; the latter, of which each 
 jaw contains four, acting only on bodies which present but a slight 
 resistance, are placed at the extremity of the maxillary lever. The 
 grinders are brought nearer to the fulcrum, and it is on them that the 
 great stress of mastication rests. If we wish to crush a very hard 
 substance, we instinctively place it between the last large grinders, 
 and by thus shortening considerably the lever between the resistance 
 and the fulcrum, we improve on the lever of the third kind, which, 
 though most employed in the animal economy, acts the most unfa- 
 vourably. The laniary teeth have very long fangs, which lying deeply 
 buried in the alveolar .processes, give them a degree of firmness to 
 enable them to act powerfully, without a danger of being loosened 
 from their situation. 
 
 The enamel which covers the teeth preserves the substance of the 
 bone exposed to the contact of the air from the injurious effects which 
 would not fail to result from direct exposure; and as enamel is much 
 harder than bone, it enables the teeth to break the hardest bodies with- 
 out injury. The concentrated acids soften this substance, and occasion 
 a painful affection of the teeth. The sensibility possessed by these 
 bones is seated in the mucous membrane which lines their inward 
 cavity, through which are distributed the vessels and nerves that 
 enter by openings at their roots. This membrane is the seat of a 
 great number of diseases, to which the teeth are subject. The enamel, 
 incessantly worn by repeated friction, grows and repairs its waste. 
 The alveolar processes which receive the fangs of the teeth firmly em- 
 brace them, and all of them being exactly conical in form, every point 
 of these small cavities, and not merely their lower part at which the 
 nerves and vessels enter, supports the pressure which is applied to 
 these bones. When, from accidental causes, or in the progress of age, 
 the teeth are gone, their alveoli first contract, and then disappear ; the 
 gums, a reddish and dense membranous substance, which connects the 
 teeth to the sockets, harden and become callous over their thinned 
 edges. Old men, who have lost all their teeth, masticate but imper- 
 fectly; and this circumstance is one of the causes of their slow diges- 
 tion, as the gastric juice acts with difficulty on food whose particles are 
 not sufficiently divided. 
 
 X. Salivary solution. The above mechanical trituration is not 
 the only change which the food undergoes in the mouth. Subjected 
 to the action of the organs of mastication, which overcome the force 
 of cohesion of its molecules, it is at the same time imbued with the 
 saliva. This fluid, secreted by the glands placed in the vicinity of the 
 mouth, is poured in considerable quantity into that cavity during 
 mastication.
 
 90 SALIVARY SOLUTION'. 
 
 The saliva is a transparent and viscous fluid, formed of about four 
 parts of water and one of albumen, in which are dissolved phosphates 
 of soda, of lime, and of ammonia, as well as a small quantity of muriate 
 of soda : like all other albuminous fluids, it froths when agitated, by 
 absorbing oxygen, for which it appears to have a strong affinity. Its 
 affinity for oxygen is such, that one may oxydise gold and silver, by 
 triturating in saliva thin leaves of those metals, which are of such diffi- 
 cult oxydisement. 
 
 The irritation occasioned by the presence or the desire of food, 
 excites the salivary glands ; they swell and become so many centres 
 of fluxion, towards which the humours flow abundantly.* Bordeu 
 first called the attention of physiologists to the great number of 
 nerves and vessels received by the parotid, maxillary, and sublingual 
 glands, from the carotid, maxillary, and lingual arteries, from the portio 
 dura of the seventh pair of nerves, from the lingual nerve of the fifth 
 pair, which penetrate their substance, or pass over a portion of their 
 surface. This great number of vessels and nerves is proportioned to 
 the quantity of saliva which is secreted, and this is estimated at about 
 six ounces during the average time of a meal. It flows in greater 
 quantity when the food that is used is acrid and stimulating : it mixes 
 with the mucus, copiously secreted with the mucous, buccal, labial, 
 palatine, and lingual glands, and with the serous fluid exhaled by the 
 exhalent arteries of the mouth. The saliva moistens, imbues, and dis- 
 solves the ball formed by the aliment, brings together its divided mole- 
 cules, and produces on them the first change. There can be no doubt 
 that the saliva, mixing with the food by the motion of the jaws, absorbs 
 oxygen, and unites to the alimentary substances a quantity of that 
 gas fit to bring about the changes which they are ultimately destined to 
 undergo, f 
 
 * The intimate sympathy or consent of action that exists between the functions 
 of the stomach and the salivary apparatus, by means of the nerves which chiefly 
 preside over the process of digestion and all the operations of secretion and nutri- 
 tion, is strongly evinced by the following fact. An individual, in an attempt to 
 commit suicide, divided the esophagus to a considerable extent. During the en- 
 deavours to preserve his existence, food was conveyed into the stomach by means of 
 a tube. As soon as the aliments were received into this viscus, the salivary secre- 
 tion became abundant, although the process of mastication was not, of course, 
 attempted. J. C. 
 
 j- The specific gravity of saliva is 1-0038. It mixes with water only by tritura- 
 tion, has a strong affinity for oxygen, absorbs it readily from the air, and gives it 
 out again to other bodies. Whether it possesses any affinity for nitrogen, has not 
 been shewn ; nor has the absorption of oxygen by this fluid, during the process of 
 mastication, been sufficiently attended to in our speculations respecting the process 
 of digestion. We can hardly suppose that it takes up oxygen without a portion of 
 nitrogen, or of common air. If any quantity of the latter be mixed with it during 
 the insalivation of the food, an evident source is disclosed from which nitrogen may
 
 OK DEGLUTITION- 91 
 
 XL The muscular parietes of the mouth are, during mastication, 
 in perpetual action. The tongue presses on the food, in every direction, 
 and brings it under the teeth ; the muscles of the cheek, especially the 
 buccinator, against which the food is pressed, force it back again under 
 the teeth, that it may be duly triturated. When the food has been 
 sufficiently divided, and imbued with saliva, the tip of the tongue is 
 carried to every part of the mouth, and the food is collected on its 
 upper surface. The food having been thus completely gathered toge- 
 ther, the tongue presses it against the roof of the mouth, and turning its 
 tip upwards and backwards, at the same time that its base is depressed, 
 there is offered to the food an inclined plane, over which the tongue 
 presses it from before backwards, to make it clear the isthmus of the 
 fauces, and to thrust it into the oesophagus. In this course of the food 
 
 be conveyed into the circulating fluids, in addition to that portion of it which is 
 derived from the ordinary aliments. 
 
 The affinity which the saliva has for oxygen, and the readiness with which it 
 gives out this substance to other bodies, explains the reason why gold or silver tri- 
 turated with it is oxydised ; and why mercury soon disappears when triturated with 
 saliva. Hence, also, the reason why the application of saliva to sores is an useful 
 remedy, and one to which the lower animals have a constant recourse. J. C. 
 
 The constituents of saliva, according to Berzelius, are as follow : 
 
 Water 992-9 
 
 Peculiar animal matter (precipitated by acet. plumbi), mucus of Bostock 2'9 
 
 Mucus* albumen of Bostock and Thompson 1-4 
 
 Alkaline muriates -. 1-7 
 
 Lactate of soda and animal matter 0'9 
 
 Pure soda.... 0-2 
 
 1000-0 
 
 * The mucous or albuminous portion has all the characters of albumen. On 
 incineration, its ashes contain a considerable portion of phosphate of lime, although 
 none of that salt can be detected in it before the incineration. It is this peculiar 
 substance which adheres to the teeth, and gives origin to the tartar that surrounds 
 them. This deposition, according to Berzelius, is composed of 
 
 Earthy phosphates 79'0 
 
 Undecomposed mucus 12-5 
 
 Peculiar salivary matter 1-0 
 
 Animal matter soluble in mur. acid 7'5 
 
 100-0 
 
 It cannot be doubted, that, like the other animal fluids, the constitution of this 
 is liable to changes from disease. It is, however, a subject which has excited little 
 attention among chemists and physiologists. Brugnatelli found the saliva of a 
 patient labouring under an obstinate venereal disease impregnated with oxalic acid. 
 
 The concretions which sometimes form in the salivary ducts chiefly consist of 
 phosphate of lime in coagulated albumen. J, C.
 
 92 OF DEGLUT1TIOX. 
 
 along the pharynx and into the resophagus, consists deglutition, a 
 function which is assisted by the co-operation of several organs whose 
 mechanism is rather complicated. 
 
 XII. Deglutition. In the process of deglutition, the mouth closes 
 by the approximation of both, jaws ; at the same time, the submaxillary 
 muscles, the digastrici, the genio-hyoidei, the mylo-hyoidei, &c. elevate 
 the larynx and pharynx, by drawing down the os hyoides towards the 
 lower jaw, which is fixed by its leyator muscles. The hyoglossus 
 muscle, at the same time that it elevates the os hyoides, depresses and 
 carries backwards the base of the tongue. Then the epiglottis, situated 
 between these two parts, which are brought together, is pushed down- 
 wards and backwards by the base of the tongue, which lays it over the 
 opening of the larynx. The alimentary mass, pressed between the 
 palate and the upper surface of the tongue, slides on the inclined plane 
 formed by the latter, and pressed by its tip, which bends back, clears 
 the isthmus of the fauces. The mucous substance which exudes from 
 the surface of amygdalae further facilitates the passage of the food. 
 When the food has thus dropped into the pharynx, the larynx, which 
 had risen, and had come forward, and which in that motion had drawn 
 the pharynx along with it, descends and falls backwards. This last 
 organ, stimulated by the presence of the food, contracts, and would in 
 part send it back in a retrograde direction, by the nasal fossae, if the 
 velum palati, elevated by the action of the levatores palati, stretched 
 transversely by the tensores palati, was not applied to their posterior 
 apertures, and towards the openings of the Eustachian tubes. Some- 
 times this obstacle is overcome, and the food returns, in part, by the 
 nostrils. This happens, when, during the act of deglutition, we 
 attempt either to laugh or speak. At such times, the air, expelled 
 from the lungs with a certain degree 'of force, elevates the epiglottis, 
 and meeting the alimentary mass, pushes it back towards the nostrils 
 through which it is to pass. The isthmus faucium is closed against the 
 return of the food into the mouth, by the swelling of the base of the 
 tongue, raised by .the action of the constrictor faucium, and of the con- 
 strictor pharyngis superior, which are small muscles contained in the 
 thickness of the pillars of the velum. 
 
 The alimentary mass is directed towards the esophagus, and is 
 thrust into that canal by the peristaltic contractions of the pharynx, 
 which may be considered as the narrow part of a funnel-like tube. 
 The solid food passes behind the aperture of the larynx, which is 
 accurately covered over by the epiglottis.* The liquids flow along the 
 
 * During deglutition the glottis is accurately closed, as well as protracted by 
 the epiglottis, so as to prevent the entrance or irritation of foreign^ substances. 
 Attention to the phenomena of respiration and deglutition, particularly as connected 
 the one with the other, will prove this. The fact, however, has been demonstrated
 
 OF DEGLUTITION. 93 
 
 sides of that opening, in two channels, easily distinguished. They 
 are always of a more difficult deglutition than the solids ; the mole- 
 cules of a fluid have an incessant tendency to separate from one another; 
 and to prevent this separation, the organs are obliged to use greater 
 exertion, and to embrace with more precision the substance that is 
 swallowed. Thus, it is observed in those cases in which deglutition 
 is prevented by some organic affection of the oesophagus, that the 
 patients, though they have the power of swallowing solid food, find it 
 difficult to swallow a few drops of a liquid, and are tortured with thirst, 
 though they have still the power of satisfying their hunger. 
 
 The deglutition of air and of gaseous substances is still more diffi- 
 cult than that of liquids, because these elastic fluids are much less 
 coercible, and it requires considerable practice to transmit a mouthful 
 of air into the stomach. M. Gosse, of Geneva, had acquired that 
 power from repeated experience, and he made use of it to induce vomit- 
 ing at pleasure, and by the application of that faculty to the interests 
 of science, he ascertained the digestibility of the articles of food in 
 most common use. 
 
 The food descends into the oesophagus, propelled by the contrac- 
 tions of that musculo-menubranous duct situated along the vertebral/ 
 column, from the pharynx to the stomach. Mucus is secreted, in 
 considerable quantity, by the membrane which lines the inner part 
 of the oesophagus, it sheathes the substances which pass along it, and 
 renders their passage more free. The longitudinal folds of the inner 
 membrane allow the oesophagus to dilate; nevertheless, when it is 
 stretched beyond measure, severe pain is experienced, occasioned, 
 no doubt, by the distension of the nervous plexuses, formed by the 
 nerves of the eighth pair, which embrace the oesophagus, as they 
 course along its sides. I purposely avoid speaking of the weight of 
 the food, as one of the causes which enable it to pass along the oeso- 
 phagus. Although, in man as in quadrupeds, that weight is no ob- 
 stacle to deglutition, it favours that function in so slight a degree, that 
 the diminution of muscular contractility at the approach of death 
 is sufficient altogether to prevent it. The act of drinking is then 
 attended with a noise of unfavourable omen. This noise consists in a 
 gurgling of the fluid, which has a tendency to get into the larynx, 
 whose opening is not covered over by the epiglottis; and if it be 
 insisted upon that the patient shall swallow some ptisan, the deglu-. 
 tition of which is impracticable, it flows into the trachea, and the patient 
 dies of suffocation. 
 
 ^Magendie and others, who have seen the epiglottis completely destroyed by di 
 ease, without either deglutition or speech being impaired. J. C.
 
 94 OF THE ABDOMINAL CAVITY. 
 
 XIII. Of the abdomen* Before inquiring any farther into the 
 phenomena of digestion, let us shortly attend to the cavity which con- 
 tains its principal organs. The abdomen is almost entirely filled by 
 the digestive apparatus, of which the urinary passages form a part; 
 its size, and the structure of its parietes, are evidently adapted to the 
 functions of that apparatus. The capacity of the abdomen exceeds 
 that of the other two great cavities ; its dimensions are not invariably 
 fixed, as those of the skull, whose size is determined by the extent of 
 its osseous and inelastic parietes. They are likewise more varying 
 than those of the chest, because the degree of dilatation of which the 
 latter is susceptible, is limited by the extent of motion of which the 
 ribs and sternum are capable. The abdomen, on the contrary, enlarges 
 in a sort of indefinite manner, by the yielding of its soft and extensible 
 parietes. In some cases of ascites, the abdomen has been known to 
 'contain as much as eighty pints of liquid, and yet death has not fol- 
 owed as a consequence of so enormous an accumulation; while 
 by reason of the delicate texture of the brain, of the_exact fulness 
 of the skull, and especially of the inflexibility of its parietes, the 
 slightest effusions within that cavity are attended with so much danger; 
 while the collection of a few pints of fluid within the chest occasions 
 suffocation. This vast capacity of the abdomen, capable of being easily 
 increased, was required in a cavity whose viscera, for the most part 
 hollow, and admitting of dilatation, contain substances varying in quan- 
 tity, and from which are disengaged gases occupying a considerable 
 space. What a difference is there not in the capacity of the abdomen 
 of animals, according to the quality of the food on which they feed ! 
 Compare the slender body of the tiger, of the leopard, and of all car- 
 nivorous animals, with the heavy mass of the elephant, of the ox, and 
 of all animals that wholly or principally live on vegetable food. In 
 the child, who digests a considerable quantity of food for the purposes 
 
 * It is requisite, in physiology as well as in medical practice, to have an arti- 
 ficial division of the abdominal cavity, in order to point out the exact and relative 
 situations of the viscera which it contains. With this view it has been usually 
 divided into three regions, called the upper, middle, and under region : each of these 
 is subdivided into three others. The UPPER region begins at the ensiform carti- 
 lage, and extends downwards to about four inches from the umbilicus ; the middle 
 of it is termed the epigastrium, and the two lateral portions hypochondria, from 
 their situation under the cartilages of the false ribs. The MIDDLE region occupies 
 about four inches above and below the umbilicus. Its middle portion is called the 
 umbilical, and its lateral parts the loins or lumbar regions. The UNDER division 
 of the abdominal cavity commences where the former one terminates, or at a line 
 drawn between the superior and anterior spinous processes of the ossa ilii, and 
 forms, in the middle, the hypogastrium, or bottom of the belly ; and at the sides , 
 the iliac regions. J. C.
 
 THE FUNCTIONS OF THE STOMACH. 95 
 
 of growth and development, the abdomen is much more capacious than 
 in the adult or the old man. In the child, the ensiform cartilage is 
 situated opposite to the body of the eighth or ninth dorsal vertebra. 
 In old men, it descends to the tenth or even the eleventh ; so that the 
 capacity of the abdomen decreases with the want of food and with the 
 activity of digestion. 
 
 The internal organs of the body are incessantly called into action 
 by different causes, and excited to different motions. The action of 
 the arterial system tends to raise the cerebral mass, and to impart to it 
 motions of elevation and depression. The motion of the ribs brings 
 about the expansion and the compression of the pulmonary tissue ; the 
 heart, which adheres to the diaphragm, drawn down by that muscle 
 when it descends, strikes against the parietes of the chest every time 
 its ventricles contract. The abdominal viscera are not less agitated 
 by the motions. of respiration; they experience from the diaphragm and 
 from the abdominal muscles a perpetual action and re-action, by means 
 of which the circulation of the fluids in their vessels is promoted, the 
 course of the food in the alimentary canal is accelerated, the activity of 
 digestion increased, and several excretions, as of the urine and faeces, 
 "performed. 
 
 XIV. Of Digestion in the Stomach.* ^The food which is taken 
 into the stomach accumulates gradually within its cavity, and separates 
 its pariete.s, which are always in contact with each other when it is 
 empty. The stomach, in that mechanical distension by the food, 
 yields without re-acting. It is not, however, absolutely passive; its, 
 parietes apply themselves by a general contraction, by a kind of tonic 
 motion, to the food which lies within it; and to this action of the whole 
 stomach, the ancients gave the name of peristole.^- As the stomach 
 dilates, its great curvature is thrust forward, the two folds of the 
 omentum recede from each other, receive it between them, and em- 
 brace its outer and dilated part. In man, the principal use of this 
 fold of the peritoneum appears to be to facilitate the dilatation of the 
 stomach, which expands chiefly at its forepart, as may be observed by 
 inflating it in a dead body. As this viscus becomes distended with air, 
 the two folds of the. omentum apply themselves to its surface, and if 
 
 * See APPENDIX, Note K. 
 
 f In order to explain correctly the functions of the stomach, either in their 
 healthy or disordered state, the conformation of the muscular coat requires to be 
 pointed out. This tunic is composed of three strata : the first, or the exterior, 
 consists of longitudinal fibres, proceeding from the cesophagus along the axis of the 
 stomach, and is continued to the duodenum ; the second, or middle stratum, which is 
 the thickest, is, composed of fibres that have an oblique direction, and which, sur- 
 rounding the stomach, decussate one another ; the third, or interior stratum, con- 
 sists entirely of circular fibres, which extend from one curvature of this viscus to the 
 other J. C.
 
 96 THE FUNCTIONS OF THE STOMACH. 
 
 this membrane is pierced with a pin, at the distance of an inch from 
 its great curvature, the pin is observed to get nearer to this curvature ; 
 but the upper portion of the omentum can alone be employed in this 
 use, and the whole of this membranous fold is never entirely occupied 
 by the stomach. Shall we say with Galen, that the omentum guards 
 the intestines against cold, and preserves in them a gentle warmth 
 necessary to digestion ; or, shall we admit the opinion of those who 
 maintain that it answers the purpose* of a fluid, filling up spaces, and 
 lessening the effect of friction and. pressure from the anterior parietes 
 of the abdomen ; or, shall we assert with others, that the use of the 
 omentum is to allow the blood to flow into it, when the stomach, in 
 a state of contraction, is incapable of receiving it? May not the 
 blood which flows so slowly in its long and slender vessels, acquire 
 some oleaginous quality which renders it fitter to supply the materials 
 of bile?* 
 
 The stomach likewise stretches, though in a less distinct manner, 
 towards its lesser curvature; and the laminae of the gastro-hepatic 
 omentum are separated from each other, as those of the omentum 
 majus. Such is the utility of the gastro-hepatic omentum, which may 
 be considered as a necessary result of the manner in which the peri- 
 toneum is disposed in relation to the viscera of the abdomen. This 
 membrane, extending from the stomach to the liver, so as to cover 
 it, could not fill the space which separates those organs, were it not 
 for a kind of membraneous communication that connects them, and in 
 which are contained the vessels and nerves, that, from the lesser cur- 
 vature, or the posterior edge of the stomach, course towards the con- 
 cave surface of the liver. This gastro-hepatic epiploon may, besides, by 
 the separation of the two laminae of which it is formed, favour the dila- 
 tation of the hepatic vein, which is situated, as well as the vessels, 
 the nerves, and the excretory ducts of the liver, in the thickness of its 
 right border. 
 
 The stomach has ever been considered as the principal organ of 
 digestion, yet its function in that process is but secondary and pre- 
 paratory ; it is not in the stomach that the principal and most essential 
 phenomenon of digestion takes place, I mean the separation of the 
 nutritive from the excrementitious part of the food". The food when 
 
 * The omentum seems to lubricate the intestines by means of its adipose halitus, 
 and to aid in facilitating the continual movements of the intestines. It also appears 
 to assist in the reciprocal motion which takes place between the digestive tube and 
 the anterior abdominal parietes, especially in preventing the natural and increased 
 action of the latter, during respiration and muscular exertion, from impeding or 
 injuring the functions of the former. It likewise obviates, during disease, the ad- 
 hesion of the intestines to the peritoneum covering the abdominal parietes, and the 
 consequent impediment to the operations of the primte visa J. C.
 
 OF CHYMIFACTION. 97 
 
 received into the stomach, is prepared for this separation which is 
 soon to be performed, it becomes fluid, and undergoes a material alter- 
 ation ; it is converted into a soft and homogeneous paste, known under 
 the name of chyme. What is the agent that brings about this 
 change ? or, in other words, in what does digestion in the stomach 
 consist ? 
 
 As it is frequently necessary to clear a spot on which one means to 
 build, we will bring forward and refute the hypotheses that have been 
 successively broached to explain the mechanism of digestion. They 
 may be enumerated as follows : concoction, fermentation, putrefaction, 
 trituration, and maceration, of the food taken into the cavity of the 
 stomach. 
 
 XV. The first of these opinions was that of the ancients and of the 
 father of physic; but, by the term concoction, Hippocrates did not 
 mean a phenomenon similar to that which takes place when food is 
 put into a vessel and exposed to the influence of heat. The tempera- 
 ture of the stomach, which does not exceed that of the rest of the body 
 (32 degrees of Reaumur's scale), would be insufficient. Cold-blooded 
 animals 'digest equally with the warm-blooded ; and, as Van Helmont 
 observes, febrile heat impairs instead of increasing the powers of diges- 
 tion. In the language of the ancients, concoction means the alteration, 
 the maturation, the animalisation of alimentary substances, assimilated 
 to our nature by the changes which they undergo in the cavity of the 
 stomach. It is, however, a verified fact, that the natural heat of the 
 stomach promotes and facilitates those changes. The experiments of 
 Spallanzani on artificial digestion shew that the gastric juice is not of 
 more efficacy than plain water in softening and dissolving alimentary 
 substances when the heat is below seven degrees (of Reaumur's scale) ; 
 J,hat its activity, on the contrary, is greatly increased when the heat is 
 ten, twenty, thirty, or forty degrees above the freezing point. The 
 digestion in the cold-blooded animals is, besides, slower than in the 
 hot-blooded. 
 
 XVI. The abettors of the theory of fermentation admit, that the 
 food taken into the stomach undergoes an inward and spontaneous 
 motion, in virtue of which it forms new combinations, and, as the pro- 
 cess of fermentation is promoted by adding to the substance that is 
 undergoing the change a certain quantity of the same which has already 
 undergone the process, some have supposed that there continually 
 exists in the stomach a leaven, formed, according to Van Helmont, by 
 a subtile acid,* and consisting,, in the opinion of others, of a small 
 quantity of the food that remains from the former digestion. But, in- 
 dependently of the circumstance that the stomach empties itself com- 
 
 * See APPENDIX, Note K.
 
 98 OF CHYMIFACTION.' 
 
 pletely, and presents no appearance of leaven when examined a few 
 hours after digestion, substances undergoing fermentation require to be 
 kept perfectly at rest, whereas the food is exposed to the oscillatory 
 circulations, and to the peristaltic contractions of the stomach, and 
 this viscus is shaken by the pulsations of the neighbouring arteries ; it 
 is besides kept in continual motion by the act of respiration. In fer- 
 mentation gases are either absorbed or extricated, neither of which cir- 
 cumstances takes place when the stomach is not out of order. 
 
 It should, however, be stated, in support of the opinion that accounts 
 for digestion on the principle of fermentation, that we can derive 
 nourishment only from substances capable of undergoing fermentation, 
 and that the substances which have undergone the panary and saccha- 
 rine fermentation are more easily digested and in less time. This 
 imperceptible fermentation, if it really take place, must bear a greater 
 analogy to these two last processes, to those which are called vinous 
 and acetous fermentation, but chiefly to the acid fermentation : indeed, 
 matters received into the stomach soon become somewhat acid, and 
 milk is frequently curdled ; but this effect is chiefly remarkable in the 
 stomach of herbivorous animals. The internal membrane of the fourth 
 stomach of a calf preserves for several months its property of curdling 
 milk, and is thus used in the making of cheese. According to Reaumur, 
 the internal membrane of the stomach of the domestic fowl possesses 
 similar virtues. Food insufficiently digested is manifestly acid.* It 
 cannot therefore be doubted that acid properties are developed in sub- 
 stances subjected to the action of the stomach; a circumstance opposed 
 to the notion that digestion is connected with the putrid fermentation. 
 
 XVII. There have been physiologists, however, from the time of 
 Plistonicus, the disciple of Praxagoras, who maintain that digestion is, 
 in fact, the consequence of putrefaction. But not only is ammonia 
 not disengaged during that process, but our digestive organs have the 
 power, as will be seen presently, of retarding, or of suspending, the 
 putrefaction of the substances which are submitted to their action. In 
 serpents, which, in consequence of the great power of dilatation of the 
 oesophagus, and from the power of holding asunder their jaws, both of 
 which are movable nearly in an equal degree, frequently swallow 
 larger animals than themselves, and take several days to digest them, 
 that part of the animal which is exposed to, the action of the stomach 
 is observed to be perfectly fresh, and dissolved to a certain extent, 
 while the part which remains out, exhibits signs of incipient putrefac- 
 tion. In fine, notwithstanding the heat and moisture of the stomach, 
 
 " From the experiments of Dr. Prout, published in the Philosophical Transac- 
 tions for 1824, and of Tiedemann and Gmelin in their work on digestion, the acid 
 found in the stomach during chymifaction is the muriatic, with a little of the 
 acetic. See on this subject the APPENDIX, Notes K. J. C.
 
 OF CHYMIFACTION. 99 
 
 the food does not remain in it long enough to allow putrefaction to 
 come on, even though every thing else should favour that process. 
 Animals which have by chance swallowed putrescent animal substances, 
 either reject them by vomiting, or, as Spallanzani has observed in some 
 birds, deprive them of their putridity. 
 
 XVII I. The system of fermentation was invented by the chemists ; 
 that of trituration by the mechanical philosophers, who compare the 
 changes which substances undergo in a mortar from the action of the 
 pestle, to the changes which the food undergoes in the stomach. But 
 how different is the triturating action of a pestle, which crushes a 
 substance softer than itself against a resisting surface, to the gentle 
 and peristaltic action of the fibres of the stomach, on the substances 
 which it contains ! Trituration, which is a mechanical effect, does not 
 alter the nature of the substance exposed to its action ; but the 
 food is decomposed, and no longer the same substance after it has 
 remained some time in the stomach. As this evidently absurd hypo- 
 thesis has long been held in high estimation, it will not be improper 
 to spend a little time in the refutation of the proofs which are adduced 
 in its support. 
 
 The manner in which digestion is brought about in birds whose 
 stomach is muscular, and especially in the gallinaceous fowls, is the 
 most specious argument adduced by the abettors of mechanical diges- 
 tion. Those granivorous birds all have a double stomach ; the first is 
 called the crop, its sides are thin, and almost entirely membranous ; a 
 fluid is abundantly effused on its inner surface, the seeds on which 
 they feed get softened, and undergo a kind of preliminary maceration in 
 the crop, after which they are more easily ground by the gizzard, which 
 is a truly muscular stomach, that fulfils the office of organs of mastica- 
 tion, almost entirely deficient in that class of animals. The gizzard 
 acts so powerfully that it crushes the solid substances exposed to its 
 action, reduces into dust balls of glass and crystal, flattens tubes of 
 tin, breaks pieces of metal, arid, what is much more extraordinary, 
 breaks, with impunity, the points of the sharpest needles and lancets. 
 Its internal part is lined with a thick semicartilaginous membrane, in- 
 crusted with a number of small stones and gravel, taken in with the 
 food of those birds. The turkey cock is, of all other fowls, that in 
 which this structure is most apparent; besides the small pebbles 
 which line its inner membrane, its cavity contains, almost in all cases, 
 a number of them. The rubbing together of these hard substances, 
 exposed along with the seeds among which they are mixed, to the 
 action of the stomach, may assist in breaking them down. The 
 pieces of iron and the pebbles which the ostrich swallows, some- of 
 which Valisnieri met with in the stomach of that bird, are destined to the 
 same use. But this mechanical division which the gizzard performs in
 
 100 OF CHYMIF ACTION. 
 
 the absence of organs of mastication, does not constitute digestion ; 
 the food, softened and divided by the action of the crop and of the 
 gizzard, passes into the duodenum, and, exposed in that intestine to the 
 action of the biliary juices, undergoes within it the changes most 
 essential to the act of digestion. 
 
 The singular structure of the lobster's stomach is not more favour- 
 able to the hypothesis of trituration. In that crustaceous animal the 
 stomach is furnished with a real mandibular apparatus, destined to 
 break down the food. There are found in it, besides, at certain times 
 of the year, two roundish concretions on each side, under its internal 
 membrane. These concretions, improperly termed crabs' eyes, consist 
 of carbonate of lime joined to a small quantity of gelatinous animal 
 matter; they disappear when, after the annual shedding of the shell, 
 the external covering, at first membranous, becomes solid from the 
 deposition of the calcareous matter of which they are formed. 
 
 The very great difference between the stomach of these animals and 
 that of man, ought to have precluded every idea of comparing them 
 together. Spallanzani has justly observed, that in regard to the mus- 
 cular power of the parietes of the stomach, animals might be divided 
 into three classes, the most numerous of which consists of those crea- 
 tures whose stomach is almost entirely membranous, and furnished 
 with a muscular coat of very little thickness. In this class are con- 
 tained man, quadrupeds, birds of prey, reptiles, and fishes. Notwith- 
 standing the weakness of that muscular coat, Pitcairn, by a misapplied 
 calculation, has estimated its power at 12,951 pounds; he reckons at 
 248,335 pounds that of the diaphragm and of the abdominal muscles 
 which act on the stomach and compress it in the alternate motions of 
 respiration. What does so exaggerated a calculation prove, except, as 
 Garat observes, that this vain shew of axioms, definitions, scholia, and 
 corollaries, with which works not belonging to mathematics have been 
 disfigured, have served only to protect vague, confused, and false 
 notions, under the cover of imposing and respected forms ? One need 
 only introduce one's hand into the abdomen of a living animal, or a 
 finger into a wound of the stomach, to ascertain that the force of that 
 viscus on its contents does not exceed a few ounces. 
 
 XIX. The learned and indefatigable Haller thought that the food 
 was merely softened and diluted by the gastric juice. This maceration 
 was, in his opinion, promoted and accelerated by the warmth of the 
 part, by the incipient putrefaction, by the gentle but continual motions 
 which the alimentary substance undergoes. Maceration, in time, 
 overcomes the force of cohesion of the most solid substances ; but by 
 dilution it never changes their nature. Haller rested on the experi- 
 ments of Albinuson the conversion of membranous tissues into mucilage 
 by protracted maceration.
 
 OF CHYMIFACTION. 101 
 
 In ruminating animals the cavity of the stomach is divided into 
 four parts, which open into one another, and of which the three first 
 communicate with the oesophagus. When the grass, after imperfect 
 trituration by the organs of mastication, whose power is inconsider- 
 able, has reached the paunch, which is the first and largest of the 
 four stomachs, it undergoes a real maceration, together with an inci- 
 pient acid fermentation. The contractions of the stomach propel the 
 food, in small quantities at a time, into the bonnet, which is smaller 
 and more muscular than the paunch ; it coils on itself, covers with 
 mucus the already softened food, then forms it into a ball, which rises 
 into the mouth by a truly antiperistaltic motion of the oesophagus. 
 The alimentary bolus, after having been chewed over again by the 
 animal, which seems to enjoy that process, descends along the oeso- 
 phagus into the third stomach, called the manyplus, on account of the 
 large and numerous folds of its inner membrane. From this cavity 
 the food enters into the abomasum, in which the stomachic digestion 
 is completed. Such is the mechanism of rumination, a function pecu- 
 liar to animals that have four stomachs ; they do not, however, rumi- 
 nate at all periods of their life. The sucking lamb does not ruminate; 
 the half-digested milk does not pass along the paunch or the bonnet, 
 which are useless, but at once descends into the third stomach. Some 
 men have been capable of a kind of rumination ; the alimentary ball, 
 after descending into the stomach, shortly after rose into the mouth, to 
 be there chewed a second time, and to be anew imbued with saliva. 
 Conrad Peyer has made this morbid phenomenon the subject of a dis- 
 sertation, entitled Mericologia, sive de Ruminantibus.* 
 
 This fourfold division of the stomach, so favourable to Haller's 
 theory, is observed only in ruminating animals. But though animals 
 are in general monogastric, as man, that is, provided with only one 
 stomach, this viscus offers a number of varieties, the most remarkable 
 of which refer to the relative facility which the food meets in remaining 
 within its cavity. The insertion of the oesophagus is nearer to its left 
 extremity, and the great fundus of that viscus is smaller, as animals 
 feed more exclusively on flesh, which is a substance of remarkably easy ' 
 decomposition, and not requiring for its digestion a long stay in the 
 stomach. In herbivorous quadrupeds, which do not ruminate, this 
 great fundus forms nearly one half, sometimes even the greater part, of 
 the stomach, as the oesophagus enters into it very near the pylorus. 
 In some, as in the hog, the stomach is divided into two parts by a 
 circular contraction. The food which is received into the great fundus 
 of the stomach may remain longer in that viscus, as this part of its 
 cavity lies out of the course of the aliment. 
 
 * See APPENDIX, Notes K.
 
 102 OF THE GASTRIC JUICES. 
 
 .XX. Of the gastric juices. Of all the organs, the stomach pro- 
 bably receives, in proportion to its bulk, the greatest number of blood- 
 vessels ; in its membrane-muscular parietes, which are little more than 
 the twelfth part of an inch in thickness,' there is distributed the coro- 
 nary artery of the stomach, entirely destined to that organ, the pyloric 
 and the right gastro-epiploic, given off by the hepatic artery, the arterice 
 breves, and the left gastro-epiploic, branches of the splenic artery. The 
 greater part of the blood, therefore, which passes from the aorta to the 
 creliac artery goes to the stomach ; for though of the arteries into which 
 that trunk is divided, the coronary of the stomach is the least, the arteries 
 of the liver and spleen send to the stomach several pretty considerable 
 branches before entering the viscera to which they are more particu- 
 larly allotted. "One need only observe the great disproportion between 
 the stomach and the quantity of blood which it receives, to conclude 
 that this fluid is not merely subservient to its nutrition, but is destined 
 to furnish the materials of some secretion. 
 
 The secretion in question is that of the gastric juice, which is most 
 abundantly supplied by arterial exhalation from the internal surface of 
 the stomach ; it is most active at the instant when the food received 
 within its cavity excites irritation, transforms it into a centre of fluxion, 
 towards which the fluids flow from all directions. The state of fulness 
 of the stomach favours the afflux of the fluids into the vessels, as, in 
 consequence of the extension of its parietes, previously collapsed, the 
 vessels are no longer bent and creased. The arteries of the stomach, 
 of the spleen and liver, arising from a common trunk, it may be easily 
 understood how, when the stomach is empty, little blood enters into 
 it in that state of contraction ; how, at the same time, the spleen, 
 which is less compressed, and the liver, must receive a larger supply of 
 blood, and again a smaller quantity when the stomach is full. 
 
 The gastric juice, the result of arterial exhalation, mixes with the 
 mucus poured out by the mucous follicles of the internal membrane 
 of the stomach. This mixture renders it viscous and ropy, like the 
 saliva, to which, in man, the gastric juice bears a great analogy. It is 
 very difficult to obtain it pure, so as to analyse it ; and even if, by long 
 fasting, the stomach should be deprived of the alimentary residue which 
 might affect its purity, one could not prevent it being mixed with a 
 certain quantity of liquid bile, which always flows back through the 
 pyloric orifice, turns yellow the inner surface of the stomach in the 
 neighbourhood of that orifice, and even imparts a certain degree of 
 bitterness to the gastric juice. The passage of the bile from the duo- 
 denum into the stomach cannot be looked upon as morbid ; it occurs 
 in the most perfect health, which has led to a well-founded opinion, 
 that a small quantity of the biliary fluid is a useful stimulus to the 
 stomach. This opinion is confirmed by an observation of Vesalius,
 
 CP THE GASTRIC JUICES. 103 
 
 who relates, that he found the ductus communis choledochus opening 
 into the stomach in the body of a convict noted for his voracious appe- 
 tite. It is further confirmed by what is observed in birds of prey, 
 in the pike, &c., which digest easily and with great rapidity, because 
 the termination into the duodenum of the ductus communis chole- 
 dochus being very near to the pylorus, the bile easily ascends into the 
 stomach, and is always found there in considerable quantity. 
 
 To obtain some of this gastric juice, it is necessary either to open 
 a living animal under the influence of hunger, or to oblige a night bird 
 of prey, as an owl, to swallow small sponges fastened to a long thread. 
 When the sponge has remained for a short time in the stomach, it 
 is withdrawn soaked with gastric juice, of which the secretion has been 
 promoted by its presence in the stomach. 
 
 The gastric juice, in its natural state, is neither acid nor alkaline; 
 it does not turn red or green vegetable blue colours. Its most remarkable 
 quality is, its singularly powerful solvent faculty; the hardest bones 
 cannot withstand its action ; it acts on those on which the dog feeds ; 
 it combines with all their organised and gelatinous parts, reduces them 
 to a calcareous residue, forming those excrementitious substances so ab- 
 surdly called album Grcecum by the older chemists. The solvent energy 
 of the gastric juice is in inverse ratio of the muscular strength of the 
 parietes of the stomach ; and in those animals in which the parietes 
 of that viscus are very thin and almost entirely membranous, it has 
 most power and activity. In the numerous class of zoophytes it alone 
 suffices to effect decomposition of the food, always more prompt when 
 accompanied by warmth of the atmosphere, as was observed by Du 
 Trembley in the polypi, which in summer dissolve in twelve hours 
 what in colder weather it would take three days to digest. In the 
 actinia, and in the holothuria, the gastric juice destroys even the shells of 
 the muscles which they swallow. Are we not all acquainted with the 
 peculiar flavour of oysters, how much they tend to whet the appetite ? 
 This sensation depends less on the salt water contained in the shell 
 than on the gastric juice which acts on the tongue, which softens its 
 tissue, and quickens its sensibility. This mucous substance, when 
 received into the stomach, promotes the digestion of the food which 
 is afterwards taken into it, for the oyster itself is very little nutritious, 
 and is used rather as a condiment than as affording nourishment. 
 
 The gastric juice not only pervades and dissolves the food received 
 into the stomach, but it unites and intimately combines with it, com- 
 pletely alters its nature, and changes its composition. The gastric 
 juice acts in a manner peculiar to itself on the food exposed to its 
 action, and, far from inducing a beginning of putrefaction, suspends, on 
 the contrary, and corrects putrescency. This antiseptic quality of 
 the gastric juice suggested the practice of moistening ulcers with it
 
 104 OF THE GASTRIC JUICES. 
 
 to accelerate their cure; and the experiments made at Geneva and in 
 Italy have, it is said, been fully successful. I have made similar expe- 
 riments with saliva, which, there is every reason to consider, is very 
 similar to the gastric juice; and I have seen old aud foul ulcers assume 
 a better appearance, the granulations become healthy, and the affec- 
 tion rapidly advance towards a cure, from the use of that irritating 
 fluid. I had under my care an obstinate sore on the inner ankle of 
 the left leg of an adult: notwithstanding the external application of 
 powdered bark, and of compresses soaked in the most detergent fluids, 
 this sore was improving very slowly, when 1 bethought myself of moist- 
 ening it every morning with my saliva, the secretion of which was in- 
 creased by the hideous aspect of the sore. From that time the patient 
 evidently mended, and his wound contracting daily, at last became 
 completely cicatrised. 
 
 However powerful the efficacy of the gastric juice to dissolve the 
 alimentary substances, it does not direct against the coats of the sto- 
 mach its active solvent faculty. These parietes, endowed with life, 
 powerfully resist solution. The lumbrici, so tender and delicate, for 
 the same reason, can exist within it, without being in the least affected 
 by it; and such is this power of vital resistance, that the polypus rejects 
 unhurt its arms, when it happens to swallow them among its food.* 
 But when the stomach and the other organs have lost their vitality, its 
 parietes yield fo the solvent power of the juices which it may contain, 
 they become softened, and even in part destroyed, if we may believe 
 Hunter, who found its inner membrane digested in several points itj 
 the body of a criminal, who, for some time before his execution, had 
 been prevailed upon, in consideration of a sum of money, to abstain 
 from food.f 
 
 * It had been thought that no animal could live on the flesh of its own kind, 
 and this circumstance was explained on the same principle ; but to refute it, we need 
 only quote the instance of cannibals and of several tribes of carnivorous animals, 
 who, in the absence of other prey, devour one another. 
 
 f The following case of solution of the stomach after death came under the 
 observation of Professor Haviland. The subject was a young man, whose body was 
 opened twelve hours after death ; and the stomach, on being examined after its 
 removal from the body, presented the following appearances : The mucous mem- 
 brane seemed more red and vascular than usual throughout its whole extent, and 
 here and there were small spots of what seemed to be extravasated blood, lying 
 beneath the mucous coat, as they could not be washed off", nor removed by the 
 edge of the scalpel. There were two holes in the stomach ; the larger very near 
 to the cardiac end of the small curvature, and on the posterior surface ; this was 
 more than an inch in length, and about half an inch in breadth. The other, not far 
 from the former, and likewise upon the posterior surface, was about the size of a 
 sixpence. The edges of these holes were smooth, well denned, and slightly elevated. 
 The coats of the stomach were thin in many other spots, and in one part nothing 
 was left but the peritoneum, the mucous and muscular coats being entirely destroyed.
 
 OP THE GASTRIC JUICES. 105 
 
 The gastric juice is capable, even after death, of dissolving food 
 introduced into the stomach by a wound made into it, provided the 
 animal still preserves some degree of animal heat. It acts on vegetable 
 and animal substances triturated and put into a small vessel, such as 
 those under which Spallanzani, in his experiments on artificial diges- 
 tion, kept up a moderate heat. Let us not, however, consider as the 
 same this solution of the food in the gastric juice out of the stomach, 
 and that which occurs in digestion within the organ. Every thing 
 tends to shew that the stomach ought not to be considered as a che- 
 mical vessel, in which there takes place a mixture giving rise to new 
 
 There was a hole in the diaphragm through the muscular portion, where it is of 
 considerable thickness, large enough to admit the end of the finger. There was no 
 appearance of ulceration or of pus adhering to the edges of this perforation of the 
 diaphragm. Dr. Haviland concludes, that, owing to the activity of the solvent 
 power of the gastric juice, it sometimes not only corrodes the parietes of the sto- 
 mach, but even the thick muscle of the diaphragm, and that within the space of 
 twelve hours after death, as was exemplified in this case. Transactions of the 
 Cambridge Philosophical Society, vol. i. part ii. 1822. 
 
 Hunter's view of this subject has been disputed, to the present day, by several 
 eminent pathologists, and by the author, in a sentence added to the above para- 
 graph in the last edition, from which this edition of the translation is revised ; but 
 Dr. Philip's observations are qualified to prove it in a very satisfactory manner to 
 those who yet require convincing arguments. On opening the abdomen of rabbits 
 which had been killed immediately after having eaten, and which were allowed to 
 lie undisturbed for some time before the examination, he has found " the great end 
 of the stomach soft, eaten through, sometimes altogether consumed, the food being 
 only covered by the peritoneum, or lying quite bare for the space of an inch and a 
 half in diameter ; and part of the contiguous intestines in the last case also con. 
 sumed, while the cabbage, which the animal had just taken, lay in the centre of the 
 stomach unchanged, if we except the alteration which had taken place in the 
 external parts of the mass it had formed, in consequence of imbibing gastric fluid 
 from the half-digested food in contact with it." 
 
 The following are Dr. Philip's observations : " We sometimes found the 
 great end of the stomach dissolved within an hour and a half after death. It was 
 more frequently found so when the animal had lain dead for many hours. This 
 effect does not always ensue, however long it has lain dead. It seems only to take 
 place when there happens to be a greater than usual supply of gastric fluid : 
 for we always observed it most apt to happen when the animal had eaten vora- 
 ciously. 
 
 " Why it should take place without the food being digested, is evident from what 
 Jtas been said. Soon after death, the motions of the stomach, which are constantly 
 carrying on towards the pylorus the most digested food, cease. Thus, the food 
 which lies next to the surface of the stomach becoming fully saturated with gastric 
 fluid, neutralises no more, and no new food being presented to it, it necessarily acts 
 on the stomach itself, now deprived of life, and, on this account, as Mr. Hunter 
 justly observes, equally subject to its action with other dead animal matter. It is 
 remarkable that the gastric fluid of the rabbit, which in its natural state refuses 
 animal food, should so completely digest its own stomach as not to leave a trace of 
 the parts acted on. I never saw the stomach eaten through, except in the large 
 end ; in other parts, its internal membrane is sometimes injured." J. C.
 
 106 OF THE GASTRIC .1 DICES. 
 
 combinations. The tying, dividing, or rather removing, a portion of 
 the nerves of the eighth pair,* the use of narcotics and of opium, 
 intense thought, every powerful affection of the mind, trouble or even 
 gaiety, entirely suspend digestion in the stomach, which cannot take 
 place independently of nervous influence. Yet this nervous influence 
 may possibly not concur directly and of itself to stomachic digestion ; 
 it is, perhaps, merely relative to the secretion of the gastric juice, 
 which the ligature or division of the nerves, the action of narcotics, 
 or of other substances, may impede, alter, or even completely 
 suspend. 
 
 It is now pretty generally admitted, that digestion in the stomach 
 consists in the solution of the food in the gastric juice.f This power- 
 ful solvent penetrates, in every direction, the alimentary mass, removes 
 from one another, or divides its molecules, combines with it, alters its 
 
 * See the APPENDIX, Note K, for the results of the most recent researches into 
 this subject 7. C. 
 
 f Dr. Beaumont published, in the American Medical Recorder for January 
 1828, some interesting experiments made by him upon a young man with a fistulous 
 opening into the stomach. He first introduced into this viscus, through the open- 
 ing, and attached by means of a silk thread, small pieces of the following substances, 
 the quantity of each being about forty grains : a piece of highly seasoned beef 
 a la mode, lean of salted beef raw, lean fresh beef also raw, salted bacon raw, 
 boiled beef, bread, and cauliflower. At the end of two hours the bread, cauliflower, 
 boiled beef, and the bacon, were completely digested, and had separated from the 
 thread : the other substances were scarcely altered ; these were returned into the sto- 
 mach ; and, after two hours, the patient complained of pain in the epigastrium, with 
 nausea. They were withdrawn at the end of five hours from the time of their first 
 introduction, scarcely more altered than- when removed previously. The liquids of 
 the stomach had an acrid and rancid flavour, and the subject of the experiment 
 complained previous to the removal of the above substances of general debility, 
 nausea, oppression and pain at the stomach, with headach. 
 
 Seven days afterwards, the bulb of a thermometer was carefully introduced 
 through the fistulous opening into the stomach, after fasting for a considerable time, 
 and in a few minutes the mercury rose to 100 of F. An ounce of pure gastric 
 juice was withdrawn, by means of a gum elastic tube, and poured into a glass 
 vessel capable of holding three ounces, in which a small piece of salted beef was 
 placed. The vessel was surrounded by water, at the temperature of 100 F., and 
 preserved at that height by means of a sand-bath. At the end of forty minutes 
 the surface of the beef was evidently acted upon. After fifty minutes, solution was 
 becoming very apparent, and after two hours the cellular texture of the beef was 
 completely dissolved, and the muscular fibres separated and floating in the turbid 
 fluid in the form of extremely fine short and white filaments. After five hours, the 
 solution was nearly complete ; and at the termination of the ninth hour, the whole 
 was dissolved. The gastric fluid which, when removed from the stomach, was clear 
 and limpid, was now slightly frothy, thickened, and more opaque ; and when 
 allowed to stand for a few minutes, deposited a sediment of a flesh colour. 
 
 At the same time that the above experiment was being performed with the 
 gastric fluid out of the stomach, a piece of salted beef, of the same weight and 
 form, was introduced through the fistulous opening into the stomach, and, at the
 
 OF THE GASTRIC JUICES. 107 
 
 inward composition, and imparts to it qualities very different from those 
 which it possessed before the mixture. If, in fact, a mouthful of 
 wine or of food is rejected a few minutes after being swallowed, the 
 smell, the flavour, all the sensible and chemical qualities of such sub- 
 stances are so completely altered that they can scarcely be recognised ; 
 the vinous substances turned, to a certain degree, sour, are no longer 
 capable of the acetous fermentation. The energy of the solvent power 
 of the gastric juice, perhaps over-rated by some physiologists, is suf- 
 ficient to dissolve and reduce into a pulp the hardest bones on which 
 some animals feed. It is highly probable that its chemical composi- 
 tion varies at different times ; that it is acid, alkaline, or saponaceous, 
 according to the nature of the food. Although the gastric juice be 
 the most powerful agent of digestion, its solvent power requires to be 
 aided by several secondary ^causes, as warmth, which seems to increase, 
 and, in a manner, to concentrate itself in the epigastric region, as long 
 as the stomach is engaged in digestion ; a sort of inward fermentation 
 which cannot be, strictly speaking, compared to the decomposition 
 which substances subject to putrefaction and acescency undergo. The 
 gentle and peristaltic action of the muscular fibres of the stomach, 
 which press, in every direction, on the alimentary substance, performs 
 on it a slight trituration, while the moisture of the stomach softens and 
 macerates the food before it is dissolved ; one might therefore say, 
 that the process of digestion is at once cheniical, mechanical, and 
 vital; in that case, the authors of the theories that have been broached 
 have been wrong, in ascribing to only one cause, such as heat, fermen- 
 tation, putrefaction, trituration, maceration, and the action of the 
 gastric juice, a process which is the result of a concurrence of these 
 causes united. 
 
 The food remains in the stomach during a longer or shorter space 
 of time, according as, by its nature, it yields more or less readily to the 
 changes which it has to undergo. Gosse, of Geneva, ascertained, by 
 experiments performed on himself, that the animal and vegetable fibr 
 concrete albumen, white and tendinous parts, paste containing fat or 
 butter, substances which have either not undergone fermentation, or 
 which do not readily undergo that process, remain longer in the 
 stomach, offer more resistance to the gastric juice, than the gelatinous 
 parts of animals or vegetables, fermented bread, &c. ; that the latter 
 required but an hour for their complete solution, while the former were 
 scarcely dissolved at the end of several hours. 
 
 end of two hours, it had undergone precisely the same change as that which was 
 placed in the glass vessel, and was completely detached from the thread by which it 
 was held ; so that there was an end to further observation respecting it. 
 
 The above experiments fully illustrate the accuracy of the opinion stated above. 
 J.C,
 
 108 OF DIGESTION. 
 
 XXI. The following case throws some light on the mechanism and 
 importance of the action of the stomach in digestion. The patient was 
 a woman, whom I had frequent opportunities of examining at the 
 Hopital de la Charite, at Paris, in the clinical wards of Professor 
 Corvisart, in which she died on the 9th Nivose of the year 10, after 
 six months stay in the hospital. 
 
 A fistulous opening, of an oval form, an inch and a half in length, 
 and upwards of an inch in breadth, situated at the lower part of the 
 chest, at the upper and left side of the epigastric region, afforded an 
 opportunity of viewing the inner part of the stomach, which, when 
 empty of food, appeared of a vermilion colour, was covered with 
 mucus, its surface wrinkled over with folds, about half an inch deep, 
 and enabled one to distinguish the vermicular undulations of these 
 folds, and of all the parts which were in sight. The patient, who was 
 then forty-seven years of age, had had this fistula since she was 
 in her thirty-eighth year. Eighteen years before, she had fallen 
 on the threshold of a door, the blow had struck against her epi- 
 gastric region. The place remained affected with pain, and she 
 became incapable of walking or of sitting otherwise than bent forward, 
 and to the left side. At the end of this long interval, a phlegmonous 
 and oblong tumour appeared on the injured spot : during the nausea 
 and vomiting which supervened, the tumour broke, and there escaped 
 at the wound left by this rupture, two pints of a fluid which the 
 patient had just swallowed. From that time, the fistula, which 
 at first would scarcely have admitted the tip of the little finger, 
 increased daily; at first it allowed only the fluids to pass, but on the 
 eighth day, the solid food came away freely, and continued to do so 
 till she died. When admitted into the hospital she ate as much as 
 three women of her age, she voided about a pint of urine, and went to 
 stool only once in three days. Her fseces were yellowish, dry, rounded, 
 and weighed more than a pound. Her pulse was very feeble and ex- 
 tremely slow, its pulsation scarcely exceeding forty-five or forty-six 
 beats in a minute. Three or four hours after a meal, an irresistible 
 desire obliged her to take off the lint and compresses with which she 
 covered the fistulous opening, and to give vent to the food which her 
 stomach might happen to contain : it came out rapidly, and there 
 escaped at the same time, and with a noise, a certain quantity of gases. 
 The food thus evacuated exhaled an insipid smell, was neither acid nor 
 alkaline ; for the chymous and grayish-coloured pulp into which it 
 was reduced, when suspended in a certain quantity of distilled water, 
 did not affect vegetable blues. The digestion of the food was far 
 from being always complete ; sometimes, however, the smell of wine 
 could not be recognised, and the bread formed a viscid, thick, and soft 
 substance, pretty similar to fibrine newly precipitated by the acetous
 
 OF DIGBSTION. 
 
 109 
 
 acid, and it floated in a tenacious liquid of the colour of common 
 broth.* 
 
 It follows, from the experiments performed at the Ecole de Mede- 
 cine on these half-digested substances, and on the same before their 
 admission into the stomach, that the changes which they undergo 
 consist in the increase of gelatine, in the formation of a substance 
 which has the appearance of fibrine, without having all its qualities, 
 and in a greater proportion of muriate and phosphate of soda, as well 
 as of phosphate of lime. 
 
 This patient was unable to sleep till she had emptied her stomach, 
 which she cleared by swallowing a pint of infusion of chamomile. In 
 the morning there was seen in the empty stomach a small quantity of 
 a ropy frothy fluid, like saliva. It did not turn vegetable blues to a 
 green or red colour, was not homogeneous, but exhibited particles of 
 some degree of consistence, among the more fluid parts, and even al- 
 buminous flakes completely opaque. The experiments performed on 
 this fluid shewed that it bore a considerable analogy to saliva, which, 
 however, is rather more liable to putrefaction. 
 
 The vermicular motion by which the stomach cleared itself of its 
 contents, took place in two different but not in opposite directions, 
 
 * Dr. Prout has made several experiments in order to ascertain the chemical 
 composition of the chyme, from which he obtained the following results : 
 
 No. 1. Chyme of a dog fed on vegetable food Composed of a semifluid, opaque, 
 yellowish white part, containing another portion of similar colour, but of firmer 
 consistence, mixed with it. Spec. grav. 1-056. It shewed no traces of a free acid, 
 or alkali, but coagulated milk completely when assisted by a gentle heat. 
 
 No. 2. Chyme of a dog fed on animal food. This was more thick and viscid 
 than No. 1, and its colour was more inclining to red. Spec. grav. 1-022. It shewed 
 no traces of a free acid, or alkali, nor did it coagulate milk, even when assisted by 
 the most favourable circumstances. 
 
 On being subjected to analysis, these two specimens of chyme were found to 
 consist of 
 
 A Water . ... 
 
 1. Chyme from 
 Vegetable Food. 
 
 86-5 
 
 2. Chyme from 
 Animal Food. 
 
 80* 
 
 B. Gastric principle, or mucus united with aliO 
 mentary matters, and apparently consti- 1 
 tuting the chyme properly so called, j 
 mixed with excrementitious matter J 
 
 6 
 
 15-8 
 1-3 
 
 
 1-6 
 
 17 
 
 
 5 
 
 
 
 "7 
 
 7 
 
 
 2 
 
 5 
 
 
 
 
 
 100- 
 
 100- 
 
 F. The saline matters were obtained by incineration, and consisted chiefly of 
 the muriates, sulphates, and phosphates. <7.<7*
 
 OF DIGESTION. 
 
 the one pressing the food towards the fistulous opening, the other 
 towards the pylorus, through which the smaller quantity was allowed to 
 
 On opening the body, it was found that the fistula extended from 
 the cartilage of the seventh left rib, as high as the osseous termination 
 of the sixth ; its edges were rounded, and from three to four lines in 
 thickness; they were covered with a thin moist skin, of a red colour, 
 and similar to that of the lips. The peritoneal coat of the stomach 
 adhered so firmly to the peritoneum lining the fore part of the abdomen 
 around the opening, that the line of adhesion could not be observed. 
 The opening was in the anterior part of the stomach, at the union of 
 the two-thirds on the left side, with the third on the right of that viscus ; 
 that is, about eight fingers' breadth from its greater extremity, and 
 only four from the pylorus. It extended from the greater to the lesser 
 curvature. In other respects it was the only organic affection of that 
 viscus. 
 
 It should be stated, that for several years the patient had been thin 
 and emaciated, and had led a languid life, which was terminated by a 
 colliquative diarrhoea. She seemed to be supported only by the small 
 quantity of food which passed through the pylorus into the duodenum, 
 where it received the influence of the bile, whose action on the chyme 
 is, as we shall presently state, absolutely essential to the separation of 
 the nutritious parts. Not that there was any thing to prevent the 
 absorbents of the stomach from taking up a certain quantity of nutri- 
 tious particles, but that small quantity of food, in an imperfect condi- 
 tion, was of very little service in ipiparting nourishment ; and in that 
 respect she was in similar circumstances to patients who are affected 
 with obstruction of the pylorus, and reject the greater part of their 
 food, when, digestion being over, this contracted opening can no longer 
 allow any food to pass. 
 
 XXII. While the alimentary solution is going on, the two open- 
 ings of the stomach remain perfectly closed ; no gas disengaged from 
 the food escapes along the oesophagus, except when digestion is 
 imperfect. A slight shivering is felt, the pulse becomes quicker 
 and more contracted, the vital power seems to forsake the other 
 organs, to concentrate itself on that which is the seat of the digestive 
 process. The parietes of the stomach are soon called into action ; its 
 circular fibres contract in different points ; these peristaltic oscillations, 
 at first irregular and uncertain, acquire more regularity, and act from 
 above downwards, and from the left to the right ; that is to say, from 
 the cardiac to the pyloric orifice. Besides, its longitudinal fibres 
 shorten it, in the direction of its greatest diameter, and bring nearer to 
 each other its two orifices. In these different motions the stomach 
 rises over the pylorus, so that the angle which it forms with the duode-
 
 OF THE PYLORUS. Ill 
 
 num almost entirely ceases, and this facilitates the escape of the food. 
 It has been observed, that during sleep digestion takes place much 
 more readily when we lie on the right than on the left side, and this 
 circumstance has been ascribed to the compression of the liver on the 
 stomach. It is much more likely to depend on the circumstance, that 
 when we lie on the right side the passage of the food is facilitated by 
 its own weight, the natural obliquity of the stomach from left to right 
 being increased by the changes attending the presence of the food. 
 
 XXIII. On the uses of the pylorus. The pyloric orifice is fur- 
 nished with a muscular ring, covered over by a fold of the mucous 
 membrane of the stomach. This kind of sphincter keeps it perfectly 
 closed while digestion is going on in the stomach, and will not allow 
 a free passage to the food which has not yet undergone a sufficient 
 change. The pylorus, which is endowed with a peculiar and delicate 
 sensibility, may be considered as a vigilant guard, which prevents any 
 thing from passing into the intestinal canal till it has undergone the 
 necessary changes. Several authors, quoted by Haller, have very 
 justly observed, that the alimentary substances do not leave the 
 ^tomach in the same order that they were received into it, but that they 
 are evacuated according to their degrees of digestibility. 
 
 One may say that there really takes place in the stomach a 
 sorting of the different substances which it contains. Those that are 
 most readily dissolved get near to the pylorus, which admits them, re- 
 jecting those which, not yet sufficiently digested, cannot produce on it 
 the necessary affection. To this delicacy of tact, which I ascribe to 
 the pylorus, will be objected, perhaps, the passage it allows to pieces 
 of money and other foreign indigestible substances. But these bodies, 
 which have always lain some time in the stomach before they make 
 their way into the intestines, repeatedly attempt the orifice of the 
 pylorus, and pass through only when they have at last accustomed it to 
 their contact. The gastric system is under the laws of a secretory 
 gland ; and as the roots of the excretory ducts, being endued with a 
 sort of elective sensibility, will not receive the secreted fluid until it 
 has undergone the necessary preparation in the glandular parenchyma, 
 in the same manner the pylorus admits aliments, and gives them pas- 
 sage into the intestines, which may be regarded as the excretory ducts 
 of the stomach, only when they have been sufficiently elaborated by the 
 action of this organ. 
 
 As the stomach empties itself, the spasm of the skin goes off; the 
 shivering is followed by a gentle warmth ; the pulse increases in fulness 
 and frequency ; the insensible perspiration is augmented. Digestion 
 brings on, therefore, a general action analogous to a febrile paroxysm ; 
 and this fever of digestion, noticed already by the ancients, is particu- 
 larly observable in women of great sensibility. Nothing positive can
 
 112 OF THE PYLORUS. 
 
 be said on the duration of stomachic digestion ; food passes sooner or 
 slower from the stomach, according as its nature is such as to resist, 
 more or less, the actions which tend to dissolve it ; according, too, to 
 the strength and vigour of the stomach at the time, and to the activity 
 of the gastric juices. Yet we may state from three to four hours as the 
 mean time of their remaining there. It is of consequence to know the 
 time required for digestion in the stomach, that we may not disturb it 
 by baths, bleedings, &c., which wouH call off towards other organs 
 those powers which ought at that time to be concentrated upon the 
 stomach. 
 
 If, as is indisputable, the stomach carries with it, into its action, all 
 the other organs of the economy ; if it summons to its aid, so to say, 
 the whole system of the vital powers ; if this sort of derivation is the 
 more conspicuous, as the organisation is more delicate, the sensibility 
 more lively, the susceptibility greater, the importance is apparent of 
 enforcing a strict diet in acute diseases, and in all cases where nature 
 is engaged in an organic operation, which a little increase of irritation 
 could not fail to disorder or to break oft". Those who have practised in 
 great hospitals know to how many patients indigestions are fatal. I 
 have seen some with large ulcers, suppuration was copious and 
 healthy, the granulations florid, and all promising a happy issue, 
 when ignorant friends bring them by stealth indigestible food, with 
 which they cram themselves in spite of the utmost watchfulness. The 
 stomach, used to a mild and moderate regimen, at once overloaded 
 with food, is changed into a centre of fluxion, towards which the juices 
 and humours all tend, an irritation is produced beyond that on: the 
 ulcerated surface, which in a little time ceases to secrete pus, the fleshy 
 granulation becomes flabby, extreme oppression is felt; with a diffi- 
 culty of breathing comes on a pungent pain in the side; the pain, 
 sympathetically felt in the lungs, makes this organ the seat of an 
 inflammatory and purulent congestion, a rattle ensues, and the patients 
 die of suffocation, at the end of two or three days, sometimes in twenty- 
 four hours ; and this fatal termination is especially accelerated, when, 
 as I have often witnessed, a blister is applied to the seat of the pain, 
 instead of the ulcerated surface. 
 
 It will seem surprising, perhaps, that in the case of which I have 
 just been speaking, it should be in the lungs, and not the stomach 
 itself, that the congestion and the pain take place ; but besides that 
 the most permeable organ of the body is the lungs, as well as the 
 weakest and the most easily yielding to fluctionary motion* a host of 
 
 * Of all the organs it is that in which we most meet with organic injury ; and 
 those who have opened many bodies may have observed how rare it is to find the 
 lungs completely sound in adults and in old men. 
 

 
 OF DIGESTION, &C. 113 
 
 instances prove what a close sympathy unites it to the stomach. Let 
 us but call to mind pleurisies and bilious peripneumonies, those acute 
 pains of the side which, since Stahl, physicians have so successfully 
 treated with vomits. The rapidity with which their symptoms go off, 
 on the evacuation of the sordes which oppress the stomach, shews 
 clearly that the sympathetic diseases are not owing to the metastasis of 
 bile upon the lungs, and that they do not consist in the simultaneous 
 existence of a gastric affection, and of an inflammatory state of the 
 pleura or of the lungs ; but that they are simple gastric affections, in 
 which the lungs are, at the same time, the seat of a sympathetic 
 pain. 
 
 The action of the parietes of the stomach ceases only when this vis- 
 cus is completely cleared of the food it contained. The gastric juice 
 is no longer secreted so freely by the arteries, and the parietes of the 
 viscus, which close upon each other, are chiefly lubricated by the mucus 
 so plentifully secreted by the inner coat. 
 
 Digestion in the stomach is essentially assisted by nervous influ- 
 ence. Many physiologists since Brunner have found that the tying of 
 the eighth pair of nerves (the pneumo-gastriqties) provoked vomiting 
 and retarded the work of digestion.* As it is impossible to make this 
 experiment without affecting respiration, a function of very different 
 importance, it becomes difficult to know whether the derangement of 
 digestion did not proceed from the general disturbance brought upon 
 all the functions : however, the brain does appear to be in more imme- 
 diate sympathy with the stomach than with any other part of the diges- 
 tive tube. Disgust from the recollection of loathed food excites 
 vomiting. A more than ordinary exertion of the brain relaxes, dis- 
 orders, and even suspends altogether, the functions of the stomach : an 
 unexpected piece of news, a violent emotion, are attended with a 
 cessation of the strongest sensation of hunger. 
 
 It would be useless to bring together in this place proofs of the 
 intimate connexion subsisting between the brain and the stomach, 
 through the intervention of the pneumo-gastric nerves, for the con- 
 nexion is questioned by no one. The most satisfactory pathological 
 proofs may be adduced in support of it; and the experiments per- 
 formed by Dr. W. Philip, and confirmed by Girard, Broughton, and 
 Breschet, shew, that the removal of a portion of the pneumo-gastric 
 nerves greatly retards digestion ; and that the galvanic current, trans- 
 mitted through the nerve below the place of its division, restores this 
 
 * Dr. Haighton has proved, in the most satisfactory manner, that a ligature on 
 the eighth pair of nerves, far from inducing vomiting, renders the stomach incapable 
 of rejecting its contents, even though excited by the most powerful emetics. T. 
 See Memoirs of the London Medical Society^ vol. ii. p. 512. 
 
 I
 
 114 OF VOMITING. 
 
 function. These experiments seem fully to prove what was indeed 
 already evident, namely, that the influence of the eighth pa'r of nerves 
 upon the digestive process is considerable ; and they further shew, that, 
 when this process is impeded by the division of the nerves, the galvanic 
 fluid will, to a certain extent, restore it, and act in an analogous 
 manner to the cerebral influence transmitted to the stomach through 
 the eighth pair of nerves ; but they by. no means prove what Dr. Philip 
 seems desirous of establishing, that the galvanic current and nervous 
 influence are identical in their nature.* 
 
 XXIV. Of vomiting. At times, the action of the muscular fibres 
 of the stomach is altogether inverted ; they contract from the pylorus 
 towards the cardia, and this anti-peristaltic motion, in which the con- 
 tractions are effected more forcibly, more rapidly, and in a manner 
 really convulsive, produces vomiting. Then, the action of the abdo- 
 minal muscles is added to that of the stomach ; the viscera are driven 
 upwards and backwards, by the contraction of the larger muscles of the 
 abdomen ; the diaphragm rises up towards the chest. If it sunk or 
 were contracted, the oesophagus, which passes in the interval of its two 
 crura, would be compressed, and the passage of the alimentary sub- 
 stances by the cardiac orifice could not take place. Accordingly it is 
 observed, that it is only during expiration that any thing passes from 
 the stomach into the oesophagus. Vomiting may depend upon the 
 obstruction of the pylorus, f on the too irritating impression of any 
 substance on the coats of the stomach ; it may be produced by the 
 irritation of some other organ with which the stomach is in sym- 
 pathy, &c. 
 
 The evacuation by the mouth of substances contained in the sto- 
 mach, depends at once upon the inverted action of this organ, and the 
 pressure exercised upon it by the abdominal parietes. But what share 
 has the stomach in this operation ? Is it the principal agent of the 
 phenomenon ? If we believe Francis Bayle, Chirac, Duverney, Senac, 
 and other physicians, whose opinions have been revived in our days, 
 the stomach is entirely passive in the act of vomiting. According to 
 them, it is only the pressure exercised upon this organ by the diaphragm 
 and abdominal muscles which occasions the operation. On the other 
 hand, Haller and his disciples contend that the stomach performs the 
 essential part of the process, to which the diaphragm and abdominal 
 
 * For a fuller discussion on this subject, see the APPENDIX, Note K. 
 
 f- The best description of the pylorus is given by Blumenbach from Levelling, 
 who designates it an annular fold, " consisting not, like the other rugae of the sto- 
 mach, of merely the mucous, but also of fibres derived from the nervous and muscular 
 coats. All these united form a conoidal opening at the termination of the stomach^ 
 projecting into the duodenum, as the uterus does into the vagina, and, in a man- 
 ner, embraced by it." J. C.
 
 OF VOMITING. 115 
 
 muscles contribute merely an accessary part. Here, as in many other 
 matters, truth seems to lie between both opinions. The experiments 
 performed by M. Magendie, and which seem to reduce the function of 
 the stomach in this process to a passive state, are in every respect 
 fallacious. The substitution of a bladder for the stomach ; the cir- 
 cumstance of its possessing only one opening, corresponding to that 
 of the cardia, without a second to answer to the pylorus ; and the 
 unnatural and painful conditions in which the subjects of the experi- 
 ments were placed, fully constitute the experimentumfallax, and shew 
 that experiment may differ widely from experience and correct ob- 
 servation. 
 
 Careful examinations of the phenomena of disease are more calcu- 
 lated to throw light upon physiology than painful experiments per- 
 formed upon the lower animals. Many pathological facts may be 
 adduced in corroboration of the e-xplanation I have given of the 
 phenomenon of vomiting ; and in support of it I may refer to the 
 conclusive observations and reasoning of Professor Lallemand and M. 
 Bourdon on this subject. 
 
 It is probable that the action of vomiting may vary in different 
 animals, conformably to modifications of structure in the organs engaged 
 in the process. It is thus, according to the remark of M. Berlin, that 
 it is extremely difficult for the horse to vomit; two thick bands of 
 muscular fibres augmenting, in this animal, the strength of the cardiac 
 orifice. Dogs and carnivorous quadrupeds throw up with much facility 
 the contents of their stomachs. Vomiting is still more easy to birds of 
 prey, which, devoid of a diaphragm, in this manner get rid of the inju- 
 rious parts of animals which they have swallowed. The absence of the 
 diaphragm in these does not at all prevent this process from being 
 readily and fully performed. 
 
 In vomiting, then, the expulsion of the contents of the stomach 
 depends both upon the action of the parietes of this organ, and the 
 concurrence of the abdominal muscles. The contents of the viscus, 
 pressed on all sides, escape through the opening which offers the least 
 resistance. The pylorus, surround d by its ring, resists the passaere of 
 the contained matters, which find a readier outlet through the cardia, 
 and thus they pass into the oesophagus, and are expelled by the forcible 
 contractions of its muscular parietes.* 
 
 * The above section has been condensed from the last Frencli edition of the 
 work. We conceive that the author is wrong in considering that the muscular 
 contractions of the oesophagus are concerned in the expulsion of the contents of the 
 stomach : we believe that the matters are ejected along the oesophagus by the in- 
 verted action of the stomach, and forcible contractions of the abdominal muscles ; 
 that instead of the muscular parietes of the resophagus being in a state of contrac- 
 tion at the moment, they are either passive or in a state of relaxation ; and that the
 
 116 OF THE FUNCTIONS OF THE DUODENUM. 
 
 XXV. Of digestion in the duodenum. The food, on quitting the 
 stomach, enters the duodenum, and there experiences new changes, as 
 essential as those which were produced upon it by digestion in the 
 stomach. It might even be said, that as the essence of digestion and 
 its principal object is the separation of the food into two parts, the one 
 recrementitious, and the other chylous or nutritious, the duodenum, in 
 which that separation is performed,* is its principal organ. In fact, 
 however carefully one may examine the grayish chyme which is sent 
 out of the stomach, it will be discovered to be a mere slimy homoge- 
 neous pulp ; and in more than a hundred animals which I have opened 
 during the process of digestion, I never observed the absorbents of the 
 stomach filled with real chyle, like those of the intestines. 
 
 The duodenum may be considered as a second stomach, very dis- 
 tinct from the other small intestines, by its situation exterior to the 
 peritonaeum, by its size, and by its readiness of dilatation, the size and 
 regularity of its curvatures, the great number of valvulse conniventes 
 with which its inner part is furnished, the prodigious quantity of chy- 
 lous vessels which arise from it, and especially by its receiving within 
 its cavity the biliary and pancreatic fluids. If the situation of the 
 duodenum and the peculiarities of its structure are attended to, it will 
 be readily observed, that every thing in that intestine tends to slacken 
 the course of the alimentary substance, and to prolong its stay 
 within it, that it may remain the longer exposed to the action of these 
 fluids. 
 
 The duodenum is, in fact, almost entirely uncovered by the peri- 
 tonaeum, a serous membrane, which, like all those that line the inside 
 of the great cavities, and reflect themselves over the viscera which they 
 contain, by furnishing them external coverings, admits but of little ex- 
 tension, and seems to stretch when these viscera become dilated, only 
 by the unfolding of its numerous duplicatures. Fixed by a rather 
 loose cellular tissue to the posterior side of the abdomen, the duodenum 
 is susceptible of such dilatation as to equal the stomach -in size, as is 
 sometimes seen in opening dead bodies. Its curvatures depend on the 
 neighbouring organs, and seem almost invariably fixed ; lastly, nume- 
 rous valvulse line its inner surface, so as to add to the friction, and to 
 increase the extent of surface, and thereby the number of absorbents 
 destined to take up the chyle separated in the duodenum from the 
 
 rising of the diaphragm, and action of the abdominal muscles whilst contributing 
 to the process, occasions, consentaneously with the ejection of the contents of the 
 organ, the expulsion of air from the lungs, which passing through the glottis at the 
 moment of the expulsion of the matters from the stomach, prevents the escape of 
 any part of these matters into the larynx. See APJ-ENDIX, Note L, for further 
 observations on the subject of vomiting J. C. 

 
 OF THE VESSELS OF THE LIVER. 117 
 
 excrementitious part of the food, by the action of the fluids poured into 
 it from the united ducts of the liver and pancreas.* 
 
 XXVI. Of the bile, and of the organs which serve for its secretion. 
 The bile is a viscous, bitter, and yellowish fluid, containing a great 
 quantity of water, of albumen to which it owes its viscid condition, and 
 oil to which the colouring and bitter principle is united ; soda, to 
 which the bile owes the property of turning vegetable blues to a green 
 colour; phosphates, carbonates, and muriates of soda; phosphates of 
 lime and of ammonia ; and, lastly, as some say, oxide of iron, and a 
 saccharine substance resembling the sugar of milk. This latter sub- 
 stance, known by the name of picromel, is very abundant in the bile of 
 bullocks, and exists but in small quantity in the human bile. The 
 biliary fluid, which the ancients looked upon as animal soap, fitted for 
 effecting a more intimate mixture of the alimentary matter by combining 
 its watery with its fat and oily parts, is, therefore, extremely compound : 
 it is at once watery, albuminous, oily, alkaline, and saline.f The liver, 
 
 * The muscular coat of the duodenum is thicker than that of the small intes- 
 tines. The base of the villi of the mucous tunic is more thickly set with glandular 
 follicles, and the whole duodenum presents a more vascular appearance than any 
 other portion of the intestines. 
 
 The experiments of Dr. Prout on chyme, taken from the duodenum, exhibit 
 the following results : 
 
 1. Vegetable Food. 
 
 Composed of a semifluid, opaque, yellowish white part, having mixed with it 
 another portion of a similar colour, but of firmer consistence. It coagulated milk 
 completely. 
 
 Water 86-5 
 
 Chyme, &c. 6 
 
 Biliary principle 1'6 
 
 Vegetable gluten 5 
 
 Saline matter '7 
 
 Insoluble residuum -2 
 
 ' . 100 
 
 2. Animal Food. 
 
 More thick and viscid than chyme from vegetable food, and its colour more 
 inclining to red. Did not coagulate milk. 
 
 Water 80 
 
 Chyme, &c 15-8 
 
 Albuminous matter 1-3 
 
 Biliary principle 1*7 
 
 Saline matters -7 
 
 Insoluble residuum , -5 
 
 100~~ 
 
 f- " Human bile differs considerably from that of all other animals. Its colour 
 is sometimes green, sometimes yellowish brown, and sometimes it is nearly colour-
 
 118 OF THE VESSELS OF THE LIVEK. 
 
 which secretes it, is a very bulky viscus, situated in the upper part of 
 the abdomen, and kept in its place chiefly by its attachment to the 
 diaphragm, of which it follows all the motion. 
 
 The hepatic artery, which the cseliac sends off to the liver, supplies 
 it only with the blood requisite for its nutrition : the materials of its 
 secretion are brought by the blood of the vena portae. 
 
 This opinion on the uses of the hepatic artery, which I adopt with 
 Haller, cannot rest upon the experiments of those who pretend to have 
 seen the secretion of the bile going on after it was tied. Besides, that 
 the position of this vessel makes the operation almost impossible, which 
 gives me reason to doubt that ever it was practised, if we intercept the 
 course of the arterial blood carried to the liver, this viscus, even under 
 the received hypothesis, would remain deprived of nourishment and of 
 action ; and the vena portse would supply it in vain with a blood on 
 which it could exert no influence. When this vein is tied, which is 
 far more easily done than the artery, the secretion of bile is seen to 
 stop ; but the experiment which suspends the abdominal venous circu- 
 lation is too speedily fatal to justify any conclusive inference. It is on 
 analogical proofs that the received hypothesis rests, touching the man- 
 ner of the biliary secretion. The hepatic artery, remarkably lessened 
 by the branches it has sent off in its way towards the liver, is to that 
 organ what the bronchial arteries are to the lungs ; and in the same 
 manner, the branches of the vena portee, spread through its substance, 
 may be compared to the system of pulmonary vessels. It is still to be 
 confessed, however, that the enormous bulk of the liver, its being found 
 in almost all animals, and the quantity of blood carried into it by the 
 vena portse, compared to the small secretion there is of bile, lead to 
 the belief, that the blood sent to it from all the other organs of digestion 
 undergoes changes there, on which science possesses as yet no certain 
 
 less. Its taste is not very bitter. It is seldom completely liquid, but usually con- 
 tains some yellow matter suspended in it. When evaporated to dryness, it leaves a 
 brown matter, amounting to lillth of the original weight. When this matter is 
 calcined, it yields all the salts which are to be found in the bile. All the acids 
 decompose human bile, and throw down a copious precipitate, consisting of albumen 
 and resin." THOMSON'S Chemistry^ &c. 
 
 The following is the analysis of human bile according to Berzelius : 
 
 Water '908-4 
 
 Picromel 80 
 
 Albumen 3 
 
 Soda 4-1 
 
 Phosphate of lime ! 
 
 Common salt .'5'4 
 
 Phosphate of soda with some lime 1 
 
 1000. J. C.
 
 OF THE LIVER AND SPLEEN.'' 119 
 
 data, though the chemists maintain that the liver is, in some sort, the 
 supplementary organ of the lungs, and assists in clearing the blood of 
 its hydrogen and carbon. 
 
 This name of vena portae is given to a particular venous system, 
 enclosed in the abdominal cavity, and formed as follows : the veins, 
 which bring back the blood of the spleen and the pancreas, of the 
 stomach and intestinal canal, are united in a very large trunk, which 
 ascends towards the concave face of the liver, and there divides into 
 two branches.* These lie in a deep fissure in the substance of this 
 viscus : they send out, through all its thickness, a multitude of 
 branches, which divide like arterial vessels, and end in part by opening 
 into the biliary ducts or pores, and in part by producing the simple 
 hepatic veins. These veins, situated chiefly towards the convex or 
 upper surface of the liver, bring back into the course of the circulation 
 the blood which has not been employed in the formation of bile, and 
 that which has not served to nourish the substance of the liver; for 
 they arise equally from the extremities of the vena portae, and from the 
 extremities of the ramifications of the hepatic artery. f 
 
 The liver^ differs from all'organs of secretion in this, that the mate- 
 rials of the fluid it elaborates are not supplied to it by its arteries. It 
 should seem that the bile, a fat and oily fluid, in which hydrogen and 
 carbon predominate, could be. drawn only from venous blood, in 
 which, as is known, these two principles are in superabundance. The 
 blood acquires ,the venous qualities as it passes along the course of 
 the circulation, and is supplied with hydrogen and carbon the more 
 fully the slower it flows. Now, it is easy to see that all is naturally 
 disposed for retarding the circulation of the hepatic blood, and to 
 give it eminently the distinguishing properties of venous blood. The 
 arteries which furnish blood to the organs in which the vena portae 
 rises, are either very flexuous, as the splenic, or frequently anastomose, 
 like the arteries of the intestinal tube, which arteries, of all that are in the 
 body , 'abound most in visible divisions and anastomoses. It will be seen in 
 the chapter on circulation, how well these dispositions are adapted for 
 retarding the course of the arterial blood. Once carried into the organs 
 of digestion, the blood flows there much more slowly, whether it be that 
 the coats of the hollow viscera, being collapsed or closed upon themselves, 
 hardly yield it passage, or that the organisation of some one of these 
 viscera is favourable to its stagnation. 
 
 * In two instances, the vena portae has been found running not to the liver, but 
 directly to the vena cava inferior. One of these is described by Mr. Abernethy, in. 
 vol. Ixxxiii. of the Philosophical Transactions, and the other by Mr. Lawrence, in 
 vol. iv. of the Medico-Chirurgical Transactions. 
 
 f- For some observations oa the Structure and Functions of the Liver, *ee 
 Not* M.
 
 120 OF THE LIVER AND SPLEEN. 
 
 The spleen seems to serve this purpose. Does this dingy and soft 
 viscus, lodged in the left hypochondrium, and attached to the great 
 fundus of the stomach, receive the blood into the minute cells of its 
 spungy parenchyma; or does this fluid merely traverse, very slowly, the 
 delicate and tortuous ramifications of the splenic vessels ? In other 
 respects, there is no organ that exhibits more variety of number, of 
 bulk, of figure, of colour, and of consistence. Sometimes manifold, 
 often divided into several lobes by deep'clefts ; its bulk varies, not only 
 in different individuals, but even in the same, at different times of the 
 day, as the stomach, full or empty, admits or rejects the arterial blood, 
 and compresses the spleen between its large extremity and the ribs 
 under which it is situated, or leaves it free. 
 
 The blood which fills the tissue of the spleen, blacker, more fluid, 
 richer in oily principles, owes all these qualities, which led the ancients 
 to consider it as a peculiar substance, called by them the atra bilis, or 
 black bile, to its long-protracted continuance within that viscus. 
 
 The branches, which by their union form the vena portse, have 
 thinner parietes than the other veins of the body, they are not fur- 
 nished with valves, and they do not readily free themselves of the 
 blood which fills them. The action of these veins is, in fact, so feeble, 
 that it would not suffice to enable them to carry the blood onward, 
 if the gentle and alternate compression of the diaphragm and abdo- 
 minal muscles on the viscera of the abdomen did not favour its circu- 
 lation. On reaching the liver, the blood, which is highly venous, is 
 further slackened in its circulation by the increased dimensions of the 
 space in which it is contained, the united calibre of the branches of the 
 hepatic vena portse exceeding considerably that of the principal trunk. 
 Besides, these vessels are enveloped in the parenchymatous substance 
 of the liver, and can act but feebly. The blood therefore circulates 
 slowly through that organ, and with difficulty returns into the course 
 of circulation. The hepatic veins, which are of pretty considerable 
 calibre, and without valves, remain constantly open; their parietes 
 cannot close and contract on the blood which fills them, on account 
 of their adhesion to the parenchymatous substance of the liver. They 
 open into the vena cava, very near the place at which that vein termi- 
 nates into the right auricle. The regurgitation of the blood during the 
 contraction of that cavity of the heart, is felt in the veins; and the 
 blood, forced back towards the liver, is exposed for a longer time to its 
 action. 
 
 The spleen, therefore, performs only preparatory functions, and 
 may be considered as the auxiliary of the liver, in the secretion of 
 the bile.* It is observed, that the quantity of the latter increases 
 
 * See APPENDIX, Note N, for an account of the latest observations and 
 opinions respecting the Structure and Functions of the Spleen.
 
 OF THE LIVER AND SPLEEN. 121 
 
 after the spleen has been extirpated, and that it is less yellow, less 
 bitter, and always imperfect.* The blood which circulates in the omen- 
 turn is very similar to that of the spleen ; I would even say that it 
 contains oily particles, if the drops which I have clearly noticed on 
 its surface might not have come from the adipose tissue of the 
 omentum, which allows the fluid contained in its cells to flow when 
 a small puncture is made into it, in examining the blood contained 
 in its veins. 
 
 The bile secreted in the tissue of the liverf is absorbed by the 
 biliary ducts, the union of which forms the hepatic duct. The latter 
 issues from the concave surface of the liver, and conveys the bile 
 either immediately into the duodenum, by means of the ductus com- 
 munis choledochus, or into the gall-bladder. This small membranous 
 pouch, which adheres by means of cellular tissue to the lower surface 
 of the liver, is in some animals entirely distinct from that organ, and 
 connected with it only by the insertion of its duct into that which 
 comes from the liver. Its inner membrane is soft, fungous, plicated, 
 and always covered with the mucus secreted by the glandular cryptae 
 which it contains. This mucus defends the gall-bladder against the 
 action of the bile contained in it. The almost parallel course of the 
 hepatic and cystic ducts, the acute angle at which they meet, renders 
 it difficult to account for the passage of the bile into the gall-bladder. 
 This, however, is promoted by the constriction of the common duct, 
 where it passes obliquely between the tunics of the duodenum, forming 
 a narrow valvular opening into this intestine, when it is empty, or in 
 a contracted state. Besides, the neck of the gall-bladder is provided 
 with a spiral valve, which favours the passage of the biliary fluid 
 into this receptacle, as has been well shewn by the experiments 
 performed by M. Amussat before the Academy of Surgery, in 
 March 1824; and it appears, that when the duodenum is empty, 
 the bile regurgitates, in part, from the hepatic duct into the gall- 
 bladder, collects within it, becomes thicker and yellower, and acquires 
 a greater degree of bitterness. Consequently, the use of the gall- 
 bladder is to serve as a reservoir to a portion of the bile, which, by 
 remaining within it, is improved in quality, acquires consistence and bit- 
 terness, and is heightened in colour, by the absorption of its fluid parts. 
 
 * Dr. C. H. Schmidt, in his " Comraentatio de Pathologia Lienis," (Got. 1816. 
 4to.), argues, that the vasa brevia contribute to strengthen and nourish the 
 stomach, that the blood and fluids of dogs deprived of the spleen, is found to tend 
 more rapidly to putrefaction than under ordinary circumstances, that the spleen 
 performs an analogous office tathe liver that the lungs do to the heart, and that 
 it presides over the preparation and assimilation of the elements of the blood. 
 J. C. 
 
 f See, in the chapter on Secretion, the laws which that function obeys.
 
 122 OF THE BILIARY AND PANCREATIC FLUIDS. 
 
 XXVII. The irritation produced on the parietes of the duodenum, 
 when distended by the chyme, is propagated to the gall-bladder by 
 the cystic and common ducts. The parietes of the gall-bladder 
 then contract, and oblige the bile to flow along the cystic duct 
 into the ductus communis choledochus. The pressure of the dis- 
 tended stomach and intestines on the gall-bladder also favours the 
 excretion of bile. The hepatic bile is, at the same time, more 
 abundantly poured into the duodenum during digestion, from being 
 secreted in greater quantity by the liver, which participates in the 
 irritation affecting the organs of digestion, and secretes a greater quan- 
 tity. The cystic and hepatic bile, mixed in the ductus communis 
 choledochus, undergoes a change before entering the duodenum, by 
 uniting with the fluid of the pancreas. The excretory duct of the 
 pancreas, a glandular organ, which, in structure, bears so great an 
 analogy to the parotid glands, that some physiologists, assuming an 
 identity of functions, have called it the abdominal salivary gland, joins 
 the biliary duct before the latter opens in the duodenum, after having 
 insinuated itself obliquely between the coats of that intestine. It 
 arises within the pancreas, from a great number of radicles which join 
 it, like the feathers of a quill to a common trunk. Its calibre increases 
 in size as it approaches the large end of the pancreas, situated on the 
 right, in the concavity of the second curvature of the duodenum. 
 Nothing precise is known with regard to the nature of the pancreatic 
 fluid; the striking resemblance of the pancreas to the salivary glands 
 leads to a presumption, that this fluid bears considerable analogy to the 
 saliva. The quantity of fluid secreted by the pancreas is likewise 
 unknown, but it must be Considerable, if one may judge from the great 
 number of nerves and vessels which pervade its glandular tissue; and 
 its quantity is, most probably, increased by the irritation of the food in 
 the duodenum.* 
 
 This combination of the united pancreatic and biliary fluids poured 
 
 * Opinions are various respecting the quantity of the secreted fluid which the 
 pancreas yields. Autenrieth reckoned the quantity at nine ounces in the twenty- 
 four hours. It has been generally supposed that the quantity of this secretion is 
 considerably augmented at the time that the chyme flows into the duodenum ; and 
 the intimate connexion existing between the ganglial nerves supplying these vis- 
 cera, favours the conclusion. Magendie, however, rejects this inference, and 
 asserts, without stating the grounds of his opinion, that the flow of the pancreatic 
 juice is least abundant during digestion. 
 
 The disordered functions of this organ appear to be very essentially concerned 
 in the production of some diseases which are too often referred entirely to the 
 stomach and small intestines, which, no doubt, become consecutively deranged from 
 this cause; or, if the actions of the pancreas be not primarily diseased, a co- 
 existent disorder may be present in these allied viscera, and be equally the result of 
 one cause. J- C.
 
 OF THE FUNCTIONS OF THE SMALL INTESTINES. 123 
 
 on the chyme, penetrates it, renders it fluid, animalises it, separates 
 the chylous from the excrementitious part, and precipitates what- 
 ever is not nutritious. In bringing about this separation, the bile 
 itself seems to be divided into two parts; its oily, coloured, and bitter 
 portion passes along with the excrements, sheathes them, and imparts 
 to them the stimulating qualities necessary to excite the action of the 
 digestive tube; its albuminous and saline particles combine with the 
 chyle, become incorporated with it, are absorbed along with it, and 
 return into the circulation. There may, in fact, be noticed in the 
 alimentary mass, after it has undergone this combination, two very 
 distinct parts the one is a whitish milky substance, which swims to the 
 surface, and is the least in quantity ; the other is a yellowish pulp, in 
 which, when digestion is healthy, it is not easy to recognise the nature 
 of the food. When the liver is obstructed, and the bile does not flow 
 in sufficient quantity, the faeces are dry and discoloured; the patients 
 are troubled with obstinate costiveness, the excrement, uncombined 
 with the bitter and colouring matter of the bile, not proving sufficiently 
 irritating to the intestinal canal. 
 
 I have just mentioned how the separation of the chyle is per- 
 formed; but the mechanism of that separation, and the process of 
 chylification, are absolutely unknown. How does the union of the 
 bile with the chyme operate, in extracting from the latter the recre- 
 mentitious part, and in making it swim above the rest ? Is there any 
 connexion between that process and the nature of the constituent 
 principles of the bile? The knowledge of the composition of the 
 bile affords as little assistance in the explanation, as does the know- 
 ledge of the chemical properties of the semen in understanding the 
 admirable function of generation. All these acts of the animal eco- 
 nomy are as mysterious and inexplicable as the action of the brain 
 in producing thought; a phenomenon which so many physiologists 
 have considered as exceeding the power of matter, and for which 
 they seem to have reserved all their admiration, though nil mirari, 
 which I would translate by wondering at nothing, ought to be the motto 
 of any one who has made some progress in the study of the laws of life. 
 
 XXVJII. Of the action of the small intestines. After remaining a 
 certain time within the duodenum, the alimentary mass, decomposed by 
 the bile, or rather by the pancreatico-biliary fluid, separated into two 
 parts, the one chylous, the other excrementitious, passes into the jeju- 
 num and ileum, which are not easily distinguished from each other, 
 and which differ in their relative length, according to the elements on 
 which anatomists ground the distinction,* 
 
 * The redness of the parietes of the jejunum, the empty condition of that 
 intestine, its situation in the umbilical region, the great number of its valvulw
 
 124 OF THE FUNCTIONS OF THE SMALL INTESTINES- 
 
 The jejunum and the ileum alone occupy nearly three-fourths of 
 the whole length of the digestive canal ; they are straighter than the 
 duodenum, and do not dilate so readily, because the peritonaeum, 
 which forms their outer covering, lies over their whole surface, with 
 the exception of the posterior border at which their vessels and nerves 
 enter. It is along that border that they are fixed to the mesentery, a 
 membranous band formed by a duplicature of the peritonaeum, which 
 contains the vessels and nerves going to the jejunum and ileum, which 
 prevents knots from forming in the intestines, and is a security against 
 the occurrence of intus-susceptio. It is well known, however, that in 
 some rare cases, intus-susceptio does take place, with utmost danger of 
 the patient's life, who generally dies in the agonies of insufferable colic 
 pains, which nothing can alleviate. The progress of the food along 
 the small intestines is retarded by its numerous curvatures, very aptly 
 compared by some physiologists to the windings of a meandering stream, 
 which fertilises the soil it waters. These numerous convolutions of the 
 intestinal canal favour the long-continued presence of the food within 
 its cavity, so that the chyle expressed from the excrementitious part by 
 the peristaltic contractions of the intestine, may present itself to the 
 inhaling mouths of the lacteals, by which it is to be absorbed. These 
 chylous absorbents are in greatest number on the surface of the 
 valvulse conniventes, which are circular folds of the inner membrane, 
 and these are at a greater distance from each other, the nearer they are 
 to the termination of the ileum. The valvulse conniventes not only 
 slacken the progress of the food, but by their projections they sink, 
 during the contraction of the bowels, into the alimentary mass, and 
 the lacteals on their surface take up, from its inmost part, the chyle 
 which they are destined to absorb.* 
 
 conniventes, do not distinguish it from the ileum ; for the colour of the intestinal 
 canal varies in different parts of its extent, and the substances which fill it are 
 found in different parts of the canal, according to the progress of digestion at 
 the time the parts are examined, according as the convolutions are situated 
 within the cavity of the pelvis or rise towards the epigastric region, according to 
 the full or empty state of the bladder and stomach ; and the number of circular 
 folds, called valvulas conniventes, diminishes, as one gets near to the termination 
 of the ileum. Winslow surmounted the difficulty, by considering the upper two-fifths 
 of the small intestines as jejunum, and the remaining three-fifths as ileum. This 
 last division, from measurement, is wholly arbitrary, and is besides useless, for 
 there is not, perhaps, above one occasion in which it would be interesting to 
 distinguish the jejunum from the ileum. In operating for hernia, when the intes- 
 tine is mortified, one would decide the more readily to leave an artificial anus, if 
 one could be sure that the gangrenous portion belonged to the latter intestine ; but 
 of this it is absolutely impossible to be certain. 
 
 * See APPENDIX, Note O, for some remarks respecting the mucous coat of the 
 digestive cunal, and the functions of the small and large intestines.
 
 OF THE FUNCTIONS OF THE SMALL INTESTINES. 125 
 
 The number of the valvulse conniventes diminishes with that of the 
 lymphatics. The progress of the alimentary substance is gradually 
 accelerated as it parts with its nutritive and recrementitious particles. 
 A quantity of mucus, secreted by the internal membrane of the small 
 intestines, envelops the chymous mass, and promotes its progress by 
 lubricating it : this intestinal mucus, thrown out [by the exhalent arte- 
 ries,* imbues it, renders it liquid, and adds to its bulk. This fluid, 
 which seems to partake of the nature of albumen and gelatine, and to 
 hold several saline substances in solution, is, for the greater part, re- 
 crementitious, and must be very considerable in quantity, if we may 
 judge from the calibre of the mesenteric arteries, and from the extent 
 of the internal surface of the intestines. It is, however, scarcely pos- 
 sible that this exhalation should amount to eight pounds in twenty- 
 four hours, according to Haller's calculation, who, as we shall 
 observe when we treat of the secretions, has generally over-rated their 
 amount. 
 
 The peristaltic contractions, by the assistance of which the alimen- 
 tary mass is sent along the whole course of the small intestines, do not 
 occur in a regular and uninterrupted succession, from the stomach to 
 the ceecum. This undulatory and vermicular motion manifests itself 
 at once, in several points of the length of the tube, whose curvatures 
 straighthen themselves at intervals. In this action the intestinal 
 curves are decomposed into a great number of short straight lines, 
 which meet so as to form obtuse angles. The peristaltic motion 
 which affects the muscular fibres of the intestines, is caused by the 
 irritation of the alimentary substance on the sentient parietes of the 
 canal along which it descends towards the great intestines. The 
 jejunum and the ileum, covered by the peritonseum, except at the part 
 which connects them to the mesentery at the time of dilatation, separate 
 the two peritoneal laminae forming the mesentery. They occupy the 
 space between the branches of the mesenteric vessels, whose last divi- 
 sion is always at some distance from the adhering edge of the intestine. 
 If this division of the vessels had taken place nearer to the union of the 
 intestine and mesentery, the intestinal canal would not have admitted 
 of dilatation, without stretching the vessels situated at" the angle of 
 separation. It is likewise observed, that in the portions of the digestive 
 tube which are most susceptible of dilatation, the last vascular divi- 
 sions are most distant. Hence, the left gastro-epiploic artery is always 
 at a greater distance from the great curvature of the stomach than 
 
 * This lubricating mucus should be considered as being the secretion of the 
 mucous follicles, rather than a product of the exhalents ; whilst the fluid which is 
 poured out by the exhalents may be viewed as serving to dilute the chyme, and faci- 
 litate the function of digestion in the intestines. J. C.
 
 126 OF THE FUNCTIONS OF THfc LARGE BOWELS. 
 
 the right; a circumstance of which no anatomist has hitherto taken 
 notice. 
 
 XXIX. Of the functions of the great intestines. The alimentary 
 mass, after it has parted with nearly the whole of its nutritive par- 
 ticles, passes from the ileum into the caecum ; it then is received into 
 the great intestines, which are more spacious, though shorter, than 
 the small, forming scarcely a fifth of.^he whole length of the digestive 
 tube. 
 
 A musculo-membranous valvular ring is placed at the oblique inser- 
 tion of the ileum into the first of the great intestines. This valve, 
 called after Eustachius or Bauhinus, who are considered as its disco- 
 verers, though the merit of the discovery belongs to F llopius, is 
 formed of two semicircular segments, the right edge of which is free, 
 and floats towards the cavity of the caecum. The more the parietes of 
 that intestine are distended by the substances which it contains, the 
 greater is the difficulty to the retrograde flow of such substances ; for, 
 under those circumstances, the two extremities of the valve are placed 
 at a greater distance, and its edges, which are free, close on each 
 other, like those of a button-hole whose angles are drawn in opposite 
 directions ; besides, the muscular fibres which enter into its structure 
 render it capable of exerting constriction. It is, therefore, calculated 
 to permit the ready flow of matters from the ileum into the caecum, and 
 forcibly prevent their return into the small intestines. There are facts 
 which lead to a belief that its resistance is sometimes overcome, and 
 that a clyster, thrown in with violence, would force the valve, and be 
 thrown up by vomiting. The great intestines may be considered as a 
 kind of reservoir, destined to contain, for a certain time, the excremen- 
 titious residue of our solid aliments, so as to save us the disgusting 
 inconvenience of constantly parting with it. 
 
 As the peritonaeum does not wholly cover the great intestines, they 
 are capable of considerable dilatation, and of extending into the cellular 
 substance which connects them to the posterior part of the abdomen. 
 Their muscular coat, which, in a manner, is the base of the intestinal 
 tube, does not consist throughout of circular and longitudinal fibres. 
 The latter, collected into fasciculi, form three narrow bands, in the 
 intervals of which the parietes of the gut are exceedingly weakened, 
 and consequently capable of greater extension. These longitudinal 
 fibres being, besides, shorter than the intestine, crease it transversely, 
 and form within it a number of cavities and cells, marked outwardly by 
 prominences, separated by depressions. If, in addition to these pecu- 
 liarities of structure, it be considered that in the caecum* and a great 
 
 * See the APPENDIX, Note O, for some remarks on the functions of the caecum. 
 J. C.
 
 OF F.ECATIOX. 127 
 
 part of the colon, the contents of the bowels have to ascend against 
 their own weight ; that the curvature forming the sigmoid flexure of 
 the colon is very considerable ; and that, in short, the rectum, before its 
 outer termination in a narrow aperture, is considerably dilated, it will 
 be evident, that in the great intestines every thing tends to protract 
 the stay of the excrements. 
 
 The appendicula vermiformis of the caecum is, in man, too small 
 to perform this office ; in the herbivorous quadrupeds, in which it is 
 much larger, and sometimes not single, it may serve as a reservoir to 
 the faecal matter. Its existence merely shews, in man, an analogy to 
 those animals in which it is truly useful ; and it concurs in manifesting, 
 that nature, in the formation of particular organs in certain kinds of 
 animals, aims at a mere outline which she fills up in others; to shew, 
 as it were, that there are points of resemblance between all beings 
 whom she has gifted with life and motion. 
 
 While in the great intestines, the alimentary substance becomes 
 merely faecal, by parting with the small quantity of chyle which it may 
 yet contain. The number of the absorbents decreases progressively 
 from the ceecum to the rectum ; the small number of these vessels 
 accounts for the difficulty of throwing in nourishment by means of 
 clysters, when there is an obstruction to deglutition. The excrements 
 thicken, harden, and become formed or moulded in the cells of the 
 colon ; they are then urged by the peristaltic action into the rectum, in 
 the cavity of which they accumulate, till they excite on its parietes an 
 action which determines their expulsion. 
 
 XXX. Of the evacuation of the fasces. When a call to evacute 
 the faeces is experienced, the rectum contracts, while the diaphragm 
 descending, and the abdominal muscles receding towards the spine,* 
 thrust the viscera of the abdomen towards the cavity of the pelvis, and 
 compress the intestines which are filled with faecal matter. During these 
 efforts the perineeum perceptibly descends, and the fibres of the levator 
 ani are somewhat elongated. The combined action of the rectum and 
 of the abdominal muscles overcomes the resistance of the sphincters, 
 and the alvine evacuation takes place, and is facilitated by the secre- 
 tion of the mucous follicles of the rectum: these glands, squeezed by 
 the pressure of the faeces, pour out their contents, and lubricate the 
 
 * Some physiologists have considered as unnecessary this concurrent action of 
 the diaphragm and abdominal muscles : they ground their opinion on the circum. 
 stance that animals whose abdomen has been laid open are capable of voiding their 
 fseces. Astruc, one of the luminaries of Montpelier, denies the action of the abdo- 
 minal muscles in the efforts which one makes at stool ; and, in support of his opi- 
 nion, he brings forward this geometrical proposition, " that a cord disposed in the 
 form of a circle, can, by contracting, shorten itself in an infinitely small degree, 
 and, therefore, not perceptibly." On which Pitcairn humorously enough observes, 
 that Astruc had never practised what he reasons upon," credo Astrrtccium nun- 
 qnam cacasse."
 
 128 OF F.ECAT1ON. 
 
 circumference of its lower aperture. When the fceces have been voided, 
 the diaphragm rises, the large muscles of the abdomen cease to press 
 backwards and downwards upon the viscera of that cavity, the perinaeum 
 ascends, and the sphincters close, till a renewal of the same call again 
 brings on the same action. 
 
 The call to void the faeces is more frequent in children than in 
 adults, because, at an early period of life, the sensibility of the intes- 
 tinal canal is greater, the contents of the bowels more fluid, and diges- 
 tion more active. As we advance in years, sensibility becoming 
 impaired, and contractility experiencing a proportionate loss of power, 
 the secretions being likewise less abundant, the bowels become slug- 
 gish, the stools more scanty and indurated. They are likewise less 
 frequent and copious in women than in men, whether it be that the 
 digestive power extracts from the aliment a greater proportion of nutri- 
 tious matter, or that the menstrual evacuation being a kind of substi- 
 tute for the intestinal secretions, less remains to add to the bulk of the 
 excrementitious mass. The evacuation of the faeces may be brought 
 on by throwing liquids into the rectum, which dilute the faeces, detach 
 them from the panetes of the intestines, and exciting on these parietes 
 an irritation to which they are not accustomed, determine their con- 
 traction. 
 
 The fetor of the excrements depends on their incipient putrefaction 
 in the great intestines.* This decomposition is almost always attended 
 with the extrication of gases, in which sulphuretted hydrogen prevails. 
 This gas, which at times escapes, and which at others impregnates the 
 faeces, is the cause of the black colour which they give to silver exposed 
 to their action. One may recognise in the excrements the colouring 
 matter of vegetables, such as the green colour of spinage, the red of 
 beet-root ; one may likewise find among them the fibrous parts of 
 plants and animals, the indurated bark, and the seeds covered with 
 their husks. The digestive juices have so little action on husks, that 
 seeds which have not been broken down by the organs of mastication, 
 frequently continue capable of vegetation. 
 
 During the progress of digestion, the food contained in the stomach 
 and intestines absorbs or extricates different gases. M. Jurine, of 
 Geneva, opened the body of a maniac who had been dead a few hours, 
 and collected the gases which escaped : he observed, that the propor- 
 tion of oxygen and carbonic acid diminishes from the stomach towards 
 the great intestines, while, on the contrary, there is in these an 
 increased proportion of azote ; that hydrogen is more abundant in the 
 great than in the small intestines ; that it is less in quantity in these 
 
 * The fetor of the excrements, in their ordinary or healthy state, may be more 
 correctly ascribed to the sensible properties of the secretion proceeding from the 
 follicular glands situate in the caecum, colon, and rectum. J, C,
 
 OF THE SECRETION OF URINE. 129 
 
 than in the stomach.* Do the oxygen and azote form a part of the 
 atmospherical air which is taken in with the food and with the saliva, 
 and which is disengaged by the heat of the intestinal canal ? Or are 
 these gases the result of the decomposition of the food and of the 
 intestinal fluids ? Besides, may not the gas contained in the intestines 
 of a dead body have been formed at the moment of death ? We know 
 that, in several instances, at the moment contractility is forsaking our 
 organs, the intestines become distended by gas, which hastens the 
 approach of death, by impeding the descent of the diaphragm. 
 
 Digestion, when healthy, is unaccompanied by the production of 
 gases. In indigestion, there almost always escapes carbonated or 
 sulphuretted hydrogen gas, which produces the offensive smell of the 
 air which escapes at the anus: this smell is different from that of the 
 flatus which are brought upwards ; these contain pure hydrogen or 
 carbonic acid gas. The latter is, likewise, sometimes voided by the 
 rectum, but less frequently than hydrogen combined with carbon, 
 sulphur, or even phosphorus. Is not ammonia itself extricated, and 
 does it not accompany the evacuation of the faeces in certain putrid 
 diarrhoeas, as in dysentery combined with low fever? Though the 
 formation of this gas implies a putrefactive motion opposed to the vital 
 principle, may not this decomposition commence in substances lying in 
 the great intestines, when these are become almost inert from the 
 impaired condition of the vital power. This would not be the only 
 instance of a chemical process taking place in the intestinal canal, 
 notwithstanding the counteracting influence of vitality. Thus, on some 
 occasions, grapes eaten in too great quantity ferment and produce 
 carbonic acid gas in such abundance, that this elastic fluid overcomes 
 the resistance of the intestines. This is the kind of distension from 
 flatulence which is cured by drinking plentifully of cold water, which 
 dissolves the gas naturally soluble in that fluid. 
 
 XXXI. Of the secretion and excretion of the urine. The fluids 
 absorbed with the chyle, and taken up by the lymphatics of the intes- 
 tinal tube, dilute the nutritive part extracted from the solid aliment, 
 and serve it as a vehicle. When they have reached the mass of the 
 blood, they increase its quantity, diminish its viscidity, and render it 
 more fluid : going along with ifthroughout the whole course of the 
 circulation, they supply moisture to all the parts of the body, and be- 
 come loaded with the molecules detached from them by the vital motion. 
 Then, conveyed to the urinary organs, they become disengaged from 
 the rest of the fluids, carrying along with them a number of products 
 of every kind, which by a longer stay in the animal economy would 
 not fail to occasion a manifest disturbance in the exercise of the 
 functions. 
 
 * See APPENDIX, Note O. 
 K
 
 130 OF THE SECRETION OF URINE. 
 
 XXXII. The rapidity with which we void, with the urine, certain 
 diuretics, has induced several physiologists to think that there exists a 
 direct communication between the stomach and bladder : no one, 
 however, has yet succeeded in pointing out those peculiar ducts 
 which might serve to convey the urine from the stomach to the urinary 
 organs, without taking the circuitous course of absorption and of the 
 circulation ; and, besides, the learned Haller has proved, by accurate 
 calculations, that the size of the renal arteries, whose calibre amounts 
 to an eighth of that of the aorta, and the quickness with which the 
 blood flows, suffice to account for the shortness of the time in which 
 certain fluids reach the urinary organs.* 
 
 A thousand ounces of blood pass through the renal tissue in the 
 space of an hour: supposing that this fluid only contains a tenth of the 
 materials fit for supplying urine, a hundred ounces, or seven pounds 
 and a quarter, may be given out in this short time ; and never, with the 
 most copious and diuretic drinks, does more of it pass in an hour. We 
 shall see, however, in treating of absorption, that it is not absolutely 
 impossible, that by means of the numerous anastomoses of the lymph- 
 atics, this set of vessels may carry a liquid directly from the stomach 
 into the bladder. It would be superfluous to mention in this place the 
 
 * The experiments of Darwin with the nitrate of potash, and of Brande with 
 the prussiate of potash, have led several in modern times, and amongst these, Sir 
 Everard Home, to support the opinion alluded to above. Magendie made experi- 
 ments in order to ascertain this matter, and deduced from them the following 
 inferences : 
 
 1. Whenever the prussiate of potash is injected into the veins, or absorbed from 
 the intestinal canal, or from a serous surface, it passes quickly into the bladder, 
 where it may be easily recognised in the urine. 2. Whenever a very considerable 
 quantity of the prussiate is injected, it can be detected in the blood by means of re- 
 agents ; but when the quantity is small, it is impossible to discover its presence by 
 any of the usual tests. 3. That the same thing takes place if the prussiate be 
 mixed with blood in a vessel. 4. That this salt may be detected in the urine in any 
 proportion ; and therefore it is by no means extraordinary, that Darwin and Brande 
 
 could not find in the blood a substance which they easily perceived in the urine . 
 
 Journ. de Phys. vol. ii. p. 380. 
 
 The existence of absorbent vessels which open into veins along their smaller 
 ramifications, and even towards their terminations, and the frequent anastomoses 
 of the former set of vessels with the latter, all which appears to be satisfactorily 
 shewn (see APPENDIX, Note Q,) sufficiently explain the rapid transit of liquids, or 
 other substances, from the stomach and other parts of the body into the circulating 
 fluid, and their quick, but Subsequent, appearance in the secretions. 
 
 In consequence of the activity of those secreting organs, whose chief function it 
 is to remove substances from the blood which would become deleterious from accu- 
 mulating in it, and owing to the stimulus which such substances give these organs 
 when conveyed to them in the course of the circulation, they are eliminated from 
 the blood as fast as they enter it, so that they seldom can be present in sufficient 
 quantity to be readily detected by the usual chemical agents. J. C.
 
 OF THE SECRETION OF URINE. 131 
 
 varieties observable in the kidneys, in point of number, size, and situ- 
 ation. These two lobular viscera, composed of the union of from 
 twelve to fifteen glandular bodies, divided in the fetus, and in some 
 quadrupeds attached to ths, posterior part of the abdomen, and situate 
 behind the peritonaeum, are surrounded with a cellular covering of 
 different thickness, and are particularly remarkable by the consist- 
 ence, approaching to that of tallow, of the fat which fills its cells. 
 
 If ever the art of man shall penetrate into the mystery of the inti- 
 mate structure of our organs, it seems probable that the kidneys will 
 furnish the first solution of the problem.* Even coarse injections pass 
 
 * One of the latest and most minute dissections of the kidney has been made 
 by Eysenhardt, of Berlin, (De StructuraRenumObservationesAnat&miece, Ber. 1818, 
 4to.) His observations were made on very thin slices of the kidney cut longitudi- 
 nally, and also in the short diameter ; these were wetted with diluted alcohol, and 
 examined in the microscope. " The experiments were originally made to discover 
 the peculiarity, if any, of a diabetic kidney ;" but no perceptible difference was 
 found to exist between the diabetic and healthy state of this organ. 
 
 " The naked eye discovered small points on these slices, which the microscope re- 
 presented as oval and sometimes as round granulations, situated at different distances 
 from each other, and varying in size, both in the same kidney and in the kidneys of 
 different sexes. After maceration, these grains could be detached with their ad- 
 hering vessels, and a void was left. They were composed of knotty vessels, sur- 
 rounded by an ash-gray substance, and united, not so much by frequent anasto- 
 moses, as by numerous meetings with each other. The ash-coloured substance 
 was not granular ; it appeared as if traced with a pencil. Injection by the renal 
 artery made these corpuscles wholly red ; but still, some deeper and other clearer 
 points could be perceived in them. Dr. E. considered these corpuscles to be the 
 glandules and glomerules of Malpighi and of Schumlansky. He could not trace the 
 veins arising from these glandules ; but he refers to an observation of Prochascka, 
 in which a successful injection of the renal vein shewed, under the microscope, a 
 very loose, vascular, little net, surrounding the isolated corpuscles of the cortical 
 substance." Dr. Mappes, of Frankfort on the Maine, says, that he has seen 
 distinctly this structure from injections of the hepatic vein, and therefore he infers 
 that the anatomy of the liver and kidney may be similar in other respects. 
 
 From these glandules Eysenhardt says, "that the grayish and transparent urini- 
 ferous vessels, which seem to be articulated, arise. These vessels form a net-work 
 which every where unites the glandules with each other. He therefore thinks 
 Schumlansky was deceived in supposing that each glandule had an excretory 
 duct, which, after making numerous curves, ran straight into the medullary sub- 
 stance. 
 
 " Little precise information is given by Eysenhardt respecting the medullary part. 
 The excretory ducts, however, which become straight when they pass out of the cor- 
 tical substance, pass along in fasciculi of about twenty in each fasciculus. 
 
 " In a foetus, the cortical substance was smaller in proportion, and the glandules 
 were of scarcely half the size. Each vascular vessel of the medullary substance was 
 composed of granulations, some of them being voluminous, and others much smaller, 
 and all strongly pressed against each other, so that the vessels could no longer be 
 distinguished from each other, but their passage only marked by strise. The 
 granules were not produced by putrefaction, although putrefaction gives a globular 
 appearance to these parts." J. C.
 
 132 OF THE SECRETION OF URINE. 
 
 readily from the renal arteries into the ureters, or excretory ducts of 
 the kidneys; a convincing proof of immediate communication among 
 the minute arteries, which, exceedingly tortuous, form, with the minute 
 veins, the cortical or outward substance of the kidneys, and the straight 
 urinary tubes, which, distributed in conical fasciculi in the interior of 
 these organs, constitute what has been called its tubuli and papillae. 
 The passage of injections from the arteries into the renal veins is as 
 easy ; and I have often seen the coarsest liquids flowing at once by the 
 ureters and by the emulgent veins. This free communication between 
 the arteries, the veins, and excretory ducts of the kidneys, gives an idea 
 of the rapidity with which the blood must flow through these organs, 
 whose firm consistence allows a very moderate dilatation to the vessels; 
 and suggests the possibility of a sort of filtration of the urinary fluid, 
 the secretion of which would be only a succession of chemical or 
 mechanical separations of the more aqueous portions of the blood 
 in its passage along very minute ducts, of a progressively decreasing 
 diameter. This was the opinion at least of Ruysch, whose system 
 on the intimate composition of our organs, and on the immediate 
 continuation of the blood-vessels with the excretory ducts, is chiefly 
 founded on the facts of structure, discovered to him by his beautiful 
 injections of the renal arteries. 
 
 The kidneys are of duller sensibility and less energetic action than 
 the other glands. The force of life has less to do in their secretion, 
 and their functions may be more readily explained on the principles 
 of chemistry or hydraulics. 
 
 XXXIII. If we attempt, indeed, to apply to the urinary organs 
 the fundamental laws on the mechanism of secretions,* it will be seen 
 that these organs are not under their absolute control. Of all the ani- 
 mal fluids, urine is the one most complex in its elements, and most vari- 
 able in its qualities. Not only do foreign substances sometimes appear 
 in it, affect, and even change its composition ; other fluids may at times 
 mix with it, and disguise it altogether. Thus, credible observers tell us 
 of the appearance in urine of bile, fat, milk, blood, pus, of which many 
 facts may be found collected in Haller's great work on physiology. The 
 kidneys, then, have less sensibility than the other secretory organs : they 
 reason less, if I may venture on the expression, on the sensation pro- 
 duced by the various substances in the blood ; their action is also less 
 powerful ; it does not so intimately affect the fluid subjected to it. It 
 does not change the heterogeneous qualities of those that are mixed 
 with it, but often allows them to pass in a pure state, f- 
 
 * See the chapter on Secretion. 
 
 + This opinion is very different from that entertained by Dr. Thomson. He 
 conceives that it is not merely the abstraction of a quantity of water and of salts
 
 OF THE SECRETION OF URINE. 133 
 
 This multitude of elements in the composition of urine had surely 
 been understood by the ancients, before it was demonstrated by modern 
 chemistry; for they considered it as a sort of extract of animal 
 substance, as a real lixivium, carrying off all that* is impure in the 
 economy, and gave it the name of lotium, which indicates that 
 destination. 
 
 Finally, the secretion of urine is more uniformly carried on ; it is 
 continual, or at least does not exhibit so prominently those alterations 
 of action and repose, so apparent in the work of the other secretory 
 organs. When, in a case of retention of urine, we introduce a catheter 
 into, the urinary bladder and leave it there, the urine keeps dropping 
 continually, and would wet the patient's bed, if the orifice of the 
 catheter were not kept closed. In the memoirs of the Academy of 
 Sciences for the year 1761, there is related a case of singular confor- 
 nAtion of the urinary bladder. This musculo-membranous viscus pro- 
 truded through an opening at the lower part of the linea alba, and was 
 turned inside out, so as to present externally its mucous membrane. 
 This case afforded an opportunity of observing the continual flow of 
 the urine through the orifices of the ureters, and of ascertaining the 
 different circumstances attending this process, either with regard to 
 the qualities of the fluid, or to the quantity which might be voided in 
 a certain space of time; and in this respect there was a good deal of 
 difference, according to the state of sleep and walking, to the quantity 
 and to the diuretic qualities of the drink. 
 
 The urine contained in the ureters is turbid and imperfect ; its con- 
 stituent parts are not thoroughly blended together, as may be observed 
 if made to flow by compressing the kidneys in a dead body. It 
 
 accumulated in the blood which the kidneys perform, but that a chemical change 
 is produced by them, either upon the whole blood, or at least upon some important 
 part of it. In proof of this additional function, he adduces the formation of nephrin 
 and uric acid, as he supposes, in the kidneys. " These two substances," he says, 
 " are formed in the kidneys, and as they are thrown out after being formed, with- 
 out being applied to any useful purpose, they are certainly not formed in the kid- 
 neys for their own sake. Some part of the blood then must be decomposed in the 
 kidney, and a new substance, or substances, must be formed ; and the urea and uric 
 acid must be formed at the same time, in consequence of the combined action of the 
 affinities which produce the change on the blood; and being useless, they are 
 thrown out, together with a quantity of water and salts, which, in all probability, 
 were useful in bringing about the changes which take place in the arteries and in 
 the kidneys, but which are no longer of any service after these changes are brought 
 about." THOM. Sysl. of Chem. vol. iv. p. 62. 
 
 This reasoning rests entirely ou the assumption that these substances are ac- 
 tually formed in the kidneys; it is quite as probable that they are produced in other 
 parts of the body, and, with other substances, removed from the blood by the action 
 of these organs. See APPENDIX, Note P, for some experiments and farther obser- 
 vations in support of the latter opinion J. C.
 
 134 OF THE SECRETION OF URINE- 
 
 improves by passing along those ducts, acquires the characteristic quali- 
 ties of urine, oozes at the surface of the papillae, and flows into the 
 membranous calices which embrace the rounded terminations of the 
 tubuli uriniferi. The union of the calices forms the pelvis, or the ex- 
 panded portion of the ureters, or membranous ducts, along which the 
 urine is incessantly flowing into the bladder. The urine flows into the 
 bladder by its own weight, and especially by the action of the parietes 
 of the ureters, which possess a certain degree of contractility. To the 
 above causes may be added the concussions excited by the pulsations 
 of the renal arteries, behind which the pelvis of the kidney is situated, 
 and by the pulsations of the iliac arteries, in front of which the ureter 
 passes before entering the cavity of the pelvis; the alternate compres- 
 sion from the viscera of the abdomen during the motions of respiration; 
 the concussion attending bodily exercise, as riding on horseback, walk- 
 ing, running, &c.; the pressure of the column of urine from the kidneys; 
 and the want of resistance towards the bladder. 
 
 XXXIV. The urine is continually passing in drops into the 
 bladder; it separates its parietes, without, however, exciting in' them any 
 perceptible impression, as they are accustomed to its stimulus. The 
 urine cannot accumulate in the musculo-membranous cavity of the 
 bladder,* which is situated exterior to the peritonaeum, in the cavity of 
 the pelvis behind the pubes, above which, in the adult, it never rises, 
 except when excessively distended, unless it is prevented from flowing 
 along the urethra, or from returning by the ureters. This retrograde 
 flow is prevented by the oblique insertion of these ducts, which pass 
 for some distance between the muscular and mucous coats of the 
 bladder before opening within it, towards the posterior angles of the 
 trigone vesical,-f by openings of smaller dimensions than their cavity. 
 The inner coat of the bladder, raised over these apertures, gives them 
 
 * In the numerous tribe of birds, the bladder is wanting. In them the ureters 
 open into the cloaca, a musculo-membranous bag, which supplies the place of the 
 rectum, bladder, and uterus, and which serves as a reservoir to the solid excrements, 
 to the urine, and to the eggs detached from the ovaria. The urine of birds dilutes 
 the faeces, and famishes the carbonate of lime, which forms the basis of the egg- 
 shell. It has such a tendency to concretion, that I have always observed, in dis- 
 secting various fowls of different kinds, an earthy, saline, or crystallised substance, 
 forming white striae, easily seen in the fluid of the ureters through their skin and 
 transparent coats. Hence one may readily conceive how frequently calculi would 
 form in these animals if their urine accumulated and remained for any length of 
 time stationary in a cavity destined to contain it. 
 
 f- The French anatomists give the name of trigone vesical to that portion of the 
 bladder included between the openings of the ureters and the neck of the bladder, 
 and forming a triangle, whose base is represented by a line drawn from the opening 
 of one ureter to the other, and whose apex is situated at the insertion of the urethra 
 into the neck of the bladder. 7'. 

 
 OF THE SECRETION OF URINE. 135 
 
 the appearance of being provided with valves, which fit these orifices 
 the better according as the urine contained in the bladder, by sepa- 
 rating its parietes, presses against each other the coats by which they 
 are formed, and between which the ureters pass, along a space of from 
 seven to eight lines. 
 
 The urine which flows into the bladder requires a certain degree of 
 force to separate its parietes, on which the weight of the intestines 
 presses. This is effected by no other power than by that which causes 
 the flow of the urine along the ureters, and though inconsiderable, it 
 will appear sufficient if it be considered that the fluids which pass from 
 a narrow channel into a larger cavity, act on every superficial portion 
 of its parietes equal to the area of the channel, with a power equal to 
 that which determines their flow into the latter ; so that if the urine 
 descends along the ureters with a degree of force equal to one, and 
 if the inner surface of the bladder is a thousand times more exten- 
 sive than the area of the ureters, the power will be multiplied a thou- 
 sand fold. 
 
 This purely mathematical proposition is expressed by saying, that the 
 force with which the urine passes along the ureters is to that by which 
 the parietes of the bladder are distended, as the calibre of the ureters 
 is to the superficies of the bladder. 
 
 The pressure which the urine, accumulated within the bladder, 
 exerts on the lower part of the ureters, does not prevent the force, 
 which determines its descent along the ureters, from carrying it into 
 the bladder : for, the column which descends along the ureters being 
 higher than that contained in the bladder, these two organs represent 
 an inverted syphon, the longer branch of which is represented by the 
 ureter. 
 
 The following are the causes which enable the bladder to retain the 
 urine : the contraction of its sphincter, a muscular ring surrounding 
 the termination of the urethra into the bladder ; the angle formed by 
 that canal after it leaves the bladder ; and lastly, the action of the 
 anterior fibres of the levator ani, which surround the neck of that 
 organ, surrounded besides and supported by the prostate gland. These 
 fibres, which are calculated to compress the prostate over the neck of 
 the bladder, and to raise the latter against the pubes, have been called 
 by Morgagni, pseudo-sphincteres vesicce. 
 
 The urine, deposited by drops into the bladder, gradually separates 
 its parietes. This musculo-membranous organ rises, and at the same 
 time carries upwards the convolutions of the ileum and the peritonaeum, 
 before which it lies, behind the pubes and the recti muscles, with which 
 it is in immediate contact. These relations of the peritonaeum to the 
 distended bladder account for the possibility of puncturing it above the 
 pubes, so as to let out an accumulation of urine, without penetrating
 
 136 OF THE EXCRETION OF URINE. 
 
 into the cavity of the peritonaeum. The urine remains a certain time 
 in the bladder, according to the capacity of the latter, to the irritability 
 and extensibility of its parietes, and according to the acrid or stimu- 
 lating qualities of the fluid itself. Thus, in old men, in whom the 
 bladder has but a small degree of irritability and contractility, the 
 urine is voided less frequently ; it accumulates in greater quantity, and 
 is, at times, evacuated with difficulty. The use of diuretics, especially 
 of cantharides, renders the urine mote stimulating ; it excites power- 
 fully the parietes of the bladder, and incessantly stimulates it to con- 
 traction. Every cause of irritation seated within the bladder itself, or 
 in its vicinity, renders more frequent the calls to void urine. This is 
 observed in cases of stone in the bladder, of piles, gonorrhoea, &c. The 
 urine, while in the bladder, becomes thicker from the absorption of 
 its more fluid parts, its elements become more intimately blended, 
 sometimes even it appears to undergo a certain degree of decompo- 
 sition. 
 
 XXXV. When, either by the extension which the urine occasions 
 in the muscular fibres of the bladder, or by the irritation which it 
 excites in the nerves distributed on its inner membrane, we experience 
 in the pelvis a sensation of weight, together with a kind of tenesmus, 
 which, as it extends along the urethra, warns us to void urine ; then we 
 bring on a contraction of the bladder, and joining to its action that of 
 the abdominal muscles and of the diaphragm, we expel the urine by a 
 process very similar to that of the excretion of the faeces. (XXIX.) It 
 should be observed, however, that in a healthy state of the parts, this 
 assistance is required only to overcome the equilibrium between the 
 contractions of the bladder and the resistance which the cause of reten- 
 tion opposes to the evacuation of the urine. After the simultaneous 
 contractions of the diaphragm and abdominal muscles, which press 
 down the intestines on the bladder, and determine the first flow of the 
 urine, we cease that effort, and the bladder alone, still supporting the 
 weight of the surrounding viscera, which compress it as it empties itself, 
 completes the evacuation. We repeat the first effort, only in case we 
 wish to accelerate the flow of the urine. In the evacuation of the faeces, 
 on the contrary, the muscular coat of the rectum requires the incessant 
 co-operation of the respiratory powers, as these solid substances are 
 evacuated with more effort than the urine. To prove, beyond a doubt, 
 that the urine is evacuated chiefly by the action of the bladder, one 
 need only observe the violent but useless straining of patients affected 
 with retention of urine from paralysis of the bladder.* 
 
 * It is scarcely credible that some physiologists should have considered this 
 organ as inert, and absolutely passive in the evacuation of the urine, which, in 
 their opinion, is performed by the immediate pressure of the abdominal muscles and
 
 % OF THE EXCRETION OF URINE. 137 
 
 The urine is projected along the urethra with the greater force, as 
 it passes from a spacious cavity into a narrow canal, and it is expelled 
 with a force proportioned to that of the muscular coat of the bladder : 
 we know, that in old men this is so weak, that the jet of urine is not 
 projected more than a few inches beyond the urethra. The urethra is 
 not to be considered as inert in the evacuation of the urine ; it closes 
 upon it and accelerates its flow, aided in that action by the bulbo- 
 cavernous muscles, to which several anatomists have given a name taken 
 from their functions (accelerator -es urince). 
 
 The action of these muscles expels the last drops of urine which 
 remain within the urethra, when the bladder is completely emptied. 
 The contractile and tonic action of the. urethra is so distinctly marked, 
 that its spasmodic contraction may be enumerated among the causes 
 which frequently occasion a difficulty in introducing the catheter. If 
 we attempt to inject fluids along the urethra, the moment we remove 
 the pipe of the syringe, which closes its external orifice, that instant 
 the parietes of the canal contract on the fluid, and expel it with a 
 rapid jet. 
 
 The bladder and the canal of the urethra are lined internally with a 
 membrane, whose mucous follicles secrete a viscid humour calculated 
 to protect the parietes of these organs against the action of the urine, 
 and to facilitate the evacuation of that fluid. This membrane, whose 
 surface is more extensive than the cavities which it lines, forms a great 
 number of folds, which disappear when the bladder is distended with 
 urine. This mucus is secreted in an unusual quantity in catarrhal 
 affections of the bladder, and becomes, likewise, more ropy and more 
 albuminous. The mucous secretion of the glands of the urethra is 
 altered in its quality, and becomes more abundant, from the action of 
 the venereal poison, and gives rise to the discharge of gonorrhoea ; the 
 orifices of these lacunae may stop the end of a catheter, so as to add to 
 the difficulty of introducing that instrument.* 
 
 The urine cannot be voided at the same time as the fseces, when 
 
 diaphragm on that cavity. Amid this variety of opinions, if you wish to come at 
 the truth you must take a medium. Iliacos intra muros peccatur, et extra, y 
 
 * When this operation is performed in a case of simple paralysis of the bladder, 
 it is better to employ a very large catheter, which may stretch the parietes of the 
 urethra, and prevent their forming into wrinkles, and whose rounded beak may 
 not get engaged in the lacunae of that canal. 
 
 When in a case of retention of urine the bladder rises above the pubes, its bos 
 fond, orfundus, is carried upwards, and there is a period of excessive distension, at 
 which, like the uterus in an advstnced state of .pregnancy, it seems to make 
 an effort to rise above the brim of the pelvis : under such circumstances in 
 women, it is impossible to introduce the catheter, except by increasing the curve 
 of the instrument.
 
 138 OF THE PHYSICAL PROPERTIES OF URINE. 
 
 these, by their hardness, compress the prostatic and the membranous 
 part of the urethra, situated before the lower extremity of the rectum. 
 It is difficult, and often impossible, to void urine during a violent 
 erection, as the parietes of the canal are then closely applied to each 
 other, by the turgescence of the corpus spongiosum and of the corpora 
 cavernosa of the penis. The mode of sensibility of the urethra is 
 besides changed in such a manner, that it is calculated to permit only 
 the emission of the seminal fluid. 
 
 When the bladder is completely emptied, it sinks behind the pubes; 
 the tumour which it formed above these bones while in a state of dis- 
 tension collapses, the abdomen becomes less prominent, respiration 
 more free, and there is a general feeling of lightness. The bladder 
 cannot be completely evacuated, unless the pelvis is gently inclined 
 forward; its has fond, which is on a lower level than its neck, would, 
 in any other posture, retain a certain quantity of urine. 
 
 XXXVI. Of the physical properties of urine. As this fluid va- 
 ries in quantity in a healthy man, according to the quantity and 
 diuretic qualities of the drink, the state of sleep or waking, the con- 
 dition of the secretions, and especially of the perspiration, it is very 
 difficult to determine accurately its proportions. Nothing varies more 
 than its quantity, as may be ascertained by comparing the different 
 calculations on that subject of a great number of physiologists. At 
 times the urine is less in quantity than the drink that has been taken 
 in, at others more. It may be affirmed, however, that the quantity of 
 urine voided in twenty-four hours is equal to that of the insensible 
 perspiration in the same time, and it may, therefore, be estimated at 
 between three and four pounds in a healthy adult. Its colour varies 
 from a light lemon yellow to an orange approaching to red. Its smell 
 and flavour are peculiar, and distinguish it from every other animal 
 fluid. Its colour is, in general, darker, its smell and flavour stronger 
 and more pungent, as it is less in quantity, as the circulatory system is 
 more active and powerful, and as the substances of our food are more 
 animalised. We all know how fetid and how scanty is the urine of 
 carnivorous animals ; how offensive to the smell is that of the cat ! The 
 specific gravity of urine is greater than that of distilled water, and 
 varies according to the quantity of saline and other substances which 
 it holds in solution : it is, likewise, slightly viscid, but not ropy, like 
 the serum of the blood, the bile, the saliva, and other albuminous 
 fluids. 
 
 XXXVII. Of the chemical properties of urine.* The peculiar qua- 
 lities of urine are always more marked in a powerful and adult male 
 
 * For some observations on the physical and chemical properties of urine, see 
 APPENDIX, Note P.
 
 OF THE CHEMICAL PROPERTIES OF URINE. 139 
 
 than in children, women, and weakly persons. By chemical analysis, 
 the urine is found to contain eleven substances, dissolved in a consi- 
 derable quantity of water ; viz. urea, a gelatinous animal matter, mu- 
 riates and phosphates of soda and ammonia, in separate or in triple 
 salts, phosphate of lime, phosphate of magnesia, phosphorus, uric and 
 benzoic acids. Besides these substances, which are constantly found 
 in human urine, this fluid may contain a great number of others ; and 
 if it be true that the urinary system is to be considered as the emunc- 
 tory of the whole economy, one would expect to find in it, in certain 
 proportions, and under different circumstances, the whole of the con- 
 stituent principles which analysis has hitherto discovered in our 
 solids, and liquids. Hence, doubtless, the difference in the results ob- 
 tained by the chemists who have investigated the nature of the urine, 
 by allowing it to run into decomposition, or by applying to it various 
 re-agents. 
 
 As the urine is, of all our fluids, that which has the greatest tend- 
 ency to putrefaction, it should be examined shortly after being voided ; 
 it is then distinctly acid, but in a very short time, and especially if the 
 heat of the atmosphere promotes and accelerates these changes, it be- 
 comes turbid, its component parts separate and form various pre- 
 cipitates. Urea and gelatine, which alone of its constituent prin- 
 ciples are capable of fermentation and decomposition, give out ammonia, 
 acetous and carbonic acids ; and from the chemical attraction between 
 these newly formed substances, and from the primitive elements, there 
 are produced new compounds, the knowledge of which is of the depart- 
 ment of chemistry. 
 
 Of all the constituent parts of urine, the most essential is a sub- 
 stance of the consistence of syrup, deliquescent, susceptible of crystal- 
 lisation, to which M. Fourcroy has given the name of urea. This sub- 
 stance, to which the urine owes its characteristic properties, its peculiar 
 colour, smell, and flavour, which was imperfectly known to several 
 chemists who had sketched some of its features, giving it different 
 names, according to the notions they entertained of its nature, was 
 never well understood till the late investigations of this celebrated pro- 
 fessor.* It is a compound in which azote prevails, as is shewn by the 
 immense quantity of carbonate of ammonia which it gives out in dis- 
 tillation ; it may be considered as the most animalised product, having 
 such a tendency to the putrid fermentation, that, even while in the 
 animal economy, it is liable to that decomposition, and might overcome 
 the antiseptic influence of the vital power, if nature did not get rid of 
 it by the evacuation of the urine. 
 
 * See his work, entitled, Systeme des Connmssances Chimiques, 8vo. torn. x. 
 p. 153.
 
 140 OF THE CHEMICAL PROPERTIES OF TJRIXE. 
 
 Sufficient attention has not hitherto been paid to the symptoms of 
 urinary fever, an affection occasioned by the protracted retention of the 
 urine within the bladder. I have observed, on several occasions, that 
 no kind of fever is attended with more ma r ked signs of what physicians 
 term putridity. The urinous and ammoniacal smell exhaled from the 
 body of the patients, the yellowish and oily moisture of their skin, the 
 parching thirst with which they are tormented, the dryness and redness 
 of their tongue and throat, their frequent and irritable pulse, combined 
 with a flaccid and doughy feel of the cellular tissue, every thing indi- 
 cates that the animal frame is threatened with the most speedy and 
 dangerous decomposition.* 
 
 I observed similar appearances in a cat and in a rabbit, in which I 
 tied the ureters. Nothing is easier than to find the ureters, and to 
 perform this experiment. After a crucial incision of the parietes of the 
 abdomen, on the left side, the intestines are pushed aside to the left, 
 so as to apply a ligature on the right ureter ; they are then pushed to 
 the right while the left ureter is tied. Both ureters are seen through 
 the peritonaeum, situated behind that membrane, in the lumbar region. 
 When the ligatures have been applied to the ureters about the middle, 
 the divided edges of the abdomen are brought together and united by 
 sutures, and the body of the animal is wrapped round with a cloak 
 soaked in some emollient decoction. At the end of six and thirty 
 hours the animals became exceedingly thirsty and restless, their eyes 
 glistening; their saliva, which flowed copiously, exhaled a smell evi- 
 dently urinous : on the third day, the cat was seized with vomiting of 
 a slimy substance, remarkable by its having the same smell. This 
 convulsive agitation was followed by an excessive prostration of 
 strength ; it died on the fifth day ; the intestines were not inflamed, 
 the bladder quite empty, the ureters distended with urine between the 
 ligatures and the kidneys, and as large as the ring finger. The kid- 
 neys themselves, gorged with urine, were turgid, softened, and as if 
 macerated. All the organs, all the fluids, the blood itself, partook of 
 this urinous diathesis; putrefaction came on immediately after death, 
 and at the end of a few days an almost complete decomposition of the 
 body had taken place. In the rabbit the symptoms were less violent 
 and rapid ; it did not die till the seventh day ; the smell of its whole 
 body, though evidently urinous, was less offensive, and the putrefaction 
 which succeeded was less rapid. 
 
 These two experiments confirm, in the first instance, what some 
 authors have said of the absence of urine in the bladder, when the 
 ureters have been tied; an undeniable proof that these are the only 
 channels which convey the urine into the bladder : they likewise con- 
 
 * See APPENDIX, Note P.
 
 OF THE CHEMICAL PROPERTIES OF URINE. 141 
 
 cur in affording the most convincing proof that the kidneys are the 
 emunctories by means of which the blood clears itself of that part of it 
 which is animalised in excess : finally, they prove that the retention of 
 this fluid is the more dangerous to the animal economy as the urine is 
 itself more animalised. 
 
 Has nature the means of supplying the evacuation of urine by other 
 excretions? might this highly recrementitious fluid be, without dan- 
 ger, evacuated by other emunctories? With a view to answer this 
 interesting question, the kidneys have been extirpated in dogs. The 
 removal of one kidney did not prevent the secretion from being carried 
 on ; in every case in which both kidneys were removed at once, the 
 animal died in a few days, and on opening the body, there was uni- 
 formly found a considerable quantity of bile in the gall-bladder, in the 
 small intestines, and even in the stomach, as if the urea had endea- 
 voured to make its escape in that direction by combining with the 
 bile. As the experiments of MM. Prevost and Dumas have shewn, 
 the extirpation of the kidneys does not impede the formation of urea, 
 which seems to be the debris of the organs, absorbed and carried into 
 the circulation.* 
 
 Urea, combined with a certain quantity of oxygen, appears to form 
 an acid peculiar to human urine, and which is the substance of the 
 greater numbers of urinary calculi. It resembles urea in this, that its 
 crystals, exposed to heat, give out carbonate of ammonia ; but it dif- 
 fers essentially from it by its ready con credibility. It, in fact, crys- 
 tallises every time the urine grows cold, and forms the greatest part of 
 the urinary sediment. This acid, so weak that several chemists have 
 considered it to be a mere oxide, has been called by MM. Fourcroy 
 and Vauquelin, the uric acid. Among its distinguishing characters, 
 may be mentioned its being insoluble in cold water; it is so fixed, that 
 several thousand times its own weight of boiling water is required to 
 dissolve it ; hence it may be easy to account for its so frequently 
 giving rise to urinary calculi : we may, indeed, wonder, that this com- 
 plaint is not of more frequent occurrence, since a slight cooling of the 
 urine is sufficient to cause a precipitation and crystallisation of the 
 urine. Thus, every time an extraneous substance drops into the 
 bladder, it becomes the nucleus of a calculus, formed by the uric acid 
 becoming concrete on the surface of this body, which is of a colder 
 temperature. Quadrupeds are less frequently affected with urinary 
 calculi, from the absence of the uric acid in their urine, and because 
 carbonate of lime, of which, in those animals, such concretions are 
 formed, is a salt decomposed with effervescence by the weaker acids; 
 and several such acids are found in the urine. 
 
 * See the APPENDIX, Note P, for further remarks on this subject.
 
 H2 OF THE PHYSICAL AND CHEMICAL 
 
 The uric acid is converted into rosacic acid by a slight alteration in 
 the proportion of its constituent elements, as shewn by M. Vogel.* 
 This new acid, discovered by Wollaston, is only found in urine in a 
 small number of cases. It is this acid which sometimes gives the urine 
 its deep colour in inflammatory diseases. 
 
 Phosphorus, which may be considered as the result of a high degree 
 of animalisation, enters, in considerable proportions, into human urine. 
 Besides the phosphoric salts which it' contains, there is always found a 
 certain quantity of disengaged phosphoric acid, which holds in solution 
 the calcareous phosphate, and gives to the urine its manifest acidity 
 when examined fresh, or shortly after it has been voided. It was from 
 urine that phosphorus was first obtained by those who originally disco- 
 vered it, and from that fluid it has long been procured for the purposes 
 of commerce. But it is seldom obtained from urine since the disco- 
 very of the phosphoric acid in the earth of bones has rendered the 
 manufacture of phosphorus easier and less expensive. In the urine of 
 frugivorous mammiferous animals, phosphoric salts have their place 
 supplied by calcareous carbonate. 
 
 Certain substances impregnate the urine with a peculiar odour. It is 
 well known, that if one remain a few minutes in a room newly painted 
 with oil of turpentine, the urine, for some time afterwards, gives out a 
 smell of violets ; asparagus gives to the urine a very remarkable fetor. 
 
 XXXVIII. Occasional changes in the urine. Besides' the acci- 
 dental varieties observed in the urine, varieties which cannot be deter- 
 mined, since the urine is never uniformly the same in its composition, 
 and does not contain the same ingredients in the same person at dif- 
 ferent times of the day, according to the quantity and quality of the 
 food and drink, the exercise which has been taken, the affections of the 
 mind which have been experienced, &c. ; it constantly varies, according 
 to the time which has elapsed since a meal, the age of the subject, and 
 the diseases under which he may labour. 
 
 Physiologists have, for a long while, admitted two and even three 
 different kinds of urine, according to the time at which it is voided ; 
 they are distinguished by the names of urine of the drink, urine of the 
 chyle, and urine of the blood. The first is a limpid and nearly colour- 
 less fluid, which frequently retains, in a remarkable manner, the quali- 
 ties of the drink, and is voided shortly after drinking, and has scarcely 
 one of the characters of perfect urine. The urine of the chyle or of 
 digestion, voided two or three hours after a meal, is more formed ; still 
 it is not perfect, and does not contain all the component parts of this 
 fluid. Lastly, the urine of the blood, which is voided seven or eight 
 hours after a meal, and in the morning after the night's rest, contains, 
 
 * Annales de Chimie, Dec 1815.
 
 PROPERTIES OF URINE. CALCULI. 143 
 
 in an eminent degree, all the qualities of urine ; hence it is that which 
 chemists prefer using in their analysis. The imperfect state of the 
 two former kinds of urine would prove, better than the rapidity of 
 their secretion, the disputed existence of a peculiar communication 
 from the stomach and intestines into the bladder. 
 
 The urine of children and that of nurses contains very little phos- 
 phate of lime and phosphoric acid ; it is only after the process of 
 ossification is completed, that these elements abound in the urine. 
 That of old men, on the other hand, contains a considerable quantity 
 of these substances ; their osseous system already containing phosphate 
 of lime in excess, and incapable of receiving more, this saline substance 
 would ossify all the tissues, as it sometimes does that of the arteries, 
 the ligaments, the cartilages, and membranes, if the urine did not carry 
 off the greater part. 
 
 In the rickets, it is by the urine that the phosphate of lime is carried 
 out of the system, and the absence of that substance is the cause of 
 mollities ossium ; on the approach of fits of the gout, the phosphoric 
 ingredients of the urine diminish, and seem to be carried to the joints, 
 to produce in their vicinity arthritic concretions. 
 
 The great quantity of saline and crystallisable elements which 
 enter into human urine, accounts for the frequency of the concretions 
 which form in that fluid. Urinary calculi were long considered as 
 formed of a single substance, which the ancients thought analogous 
 to the earth of the bones, and which Scheele took for uric acid. The 
 late investigations of MM. Fourcroy and Vauquelin have shewn, that 
 the component parts of urine are too numerous and too complex to 
 produce uniformly calculi of one kind ; that urinary concretions, most 
 frequently formed from uric acid, contain urate of ammonia, phosphate 
 of lime, phosphate of ammonia and magnesia, oxalate of lime, silex ; 
 and that these substances, singly, or in binary and ternary combina- 
 tions, form the materials of nearly six hundred calculi which they 
 analysed. Notwithstanding the extent of these researches, there is 
 reason to believe, that when carried further by the same chemists, they 
 will be attended with results still more varied. For, as there is no 
 integral molecule in the body which may not be voided with the urine, 
 and be found in the urine, so it is conceivable, that under certain cir- 
 cumstances, which it is impossible to assign or to foresee, every thing 
 in the human body that is capable of concretion might supply the 
 materials of urinary concretions. 
 
 This variety of elements in the composition of urinary calculi, 
 the absence of signs by which to ascertain their nature, the sensibility 
 of the parietes of the bladder, which would be irritated by agents 
 capable of dissolving the concretions so frequently formed in its cavity, 
 must render it very difficult, not to say impossible, to discover a lithon-
 
 144 URINARY CALCULI. 
 
 triptic which should supersede the necessity of a surgical operation, 
 whose difficulties and danger have been much over-rated. 
 
 XXXIX. Urinary calculi. The energy of the urinary system in 
 the inhabitants of temperate climates has been considered as the cause 
 of the frequency of calculous affections in Holland, England, and 
 France, while they are very rare in more southern countries, in which 
 the cutaneous perspiration seems to be substituted, in great measure, 
 to the urinary secretion. There is rio part of the world in which cases 
 of stone in the bladder are more frequent than in England, and espe- 
 cially in Holland, in which a cold and damp atmosphere is unfavourable 
 to perspiration, which is, at any rate, but scanty in persons of a leuco- 
 phlegmatic temperament like that of the Dutch. In no other country 
 could a lithotomist (Raw) have operated on more than fifteen hundred 
 patients, it is said, successfully. Diabetes, or an immoderate discharge 
 of urine, a disease which appears to depend on an excessive relaxation 
 of the renal tissue, is of frequent occurrence only in cold and damp 
 countries, as Holland, England, and Scotland; it is more rare in 
 France and Germany, and is unknown in warm climates. This relaxa- 
 tion of the renal tissue in diabetes depends on the exhaustion of the 
 urinary organs called into too frequent action, as is proved by the 
 efficacy of tonics and astringents in the treatment of that complaint. 
 
 Cutaneous affections, on the contrary, seem to belong to the inha- 
 bitants of southern countries. Lepra originated in Judea; the elephan- 
 tiasis rubra of Cayenne, the framboasia of Java, the yaws, elephantiasis, 
 herpetic and psoric eruptions, are more frequent among the inhabitants 
 of southern latitudes than among those who live under the temperate 
 zones. In countries near to the equator, the surface of the body, habit- 
 ually exposed to an ardent atmosphere, is powerfully excited ; the 
 skin is irritated, and its secretion increased ; perspiration becomes so 
 profuse, that it weakens, in a short time, those who, coming from dis- 
 tant countries, are not accustomed to so intense a heat. The activity 
 of the cutaneous system exceeds that of the urinary system, whose 
 action decreases in proportion. These differences in the energy of the 
 two systems account readily for the difference of their diseases ; for it 
 is a law of nature, that the more an organ, or system of organs, is 
 called into action, the more it is liable to disease, which is but a 
 derangement of its action. 
 
 Calculous affections are more frequent in children and old people 
 than in adults. In old age, the proportionate quantity of the urine 
 exceeds that of the perspiration. Phosphoric salts, the base of a great 
 number of urinary calculi, are more abundant in old men, as is proved 
 by the ossification in them of the arteries, of the ligaments, of the 
 cartilages, of the membranes, the solidification and the almost uni- 
 versal induration of the different parts. In children, the activity of the
 
 OF ABSORPTION. 145 
 
 urinary system is proportionate to that of the digestive organs. Des- 
 tined to throw out the residue of nutrition, which at that period is very 
 active, the organs by which the urine is secreted are likewise endowed 
 with considerable energy. Lastly, it is observed, that the greatest 
 number of calculous patients received into the hospitals of large towns 
 come from low and damp streets near to rivers. Every thing, therefore, 
 tends evidently to establish, that the frequency of urinary calculi 
 depends on an increase of activity in the organs destined to the secre- 
 tion and excretion of urine. 
 
 CHAPTER II. 
 
 OF ABSORPTION. , 
 
 XL. Absorption takes place in every part of the body XLI. Circumstances 
 
 influencing the Function of Absorption XLII. The Absorbents have Radicles, 
 
 or open Mouths XLIII. Their numerous Anastomoses, and mode of uniting 
 
 in Trunks, &c XLIV. Their Course through, and Connexion with, Glands 
 
 XLV. Structure and Functions of Lymphatic Vessels and Glands XLVI. Pa- 
 thological Views. XL VII. Of the Thoracic Duct XLVIII. Of the Physical 
 
 and Chemical Properties of the Lymph and Chyle. 
 
 XL. IN the history of the phenomena of life, a statement of the 
 functions of the absorbent system ought immediately to follow that of 
 the functions of the digestive organs. The vessels which take up the 
 chyle separated from the food .by the action of the organs of digestion, 
 form a considerable part of the absorbent system, bear a perfect 
 resemblance to the other lymphatics, and differ from them only in 
 their origin. When digestion is not going on, those vessels convey 
 lymph absorbed in the intestinal canal, the inner part of which, even 
 when in a state of emptiness, is always bedewed by an abundant quan- 
 tity of serous mucus. 
 
 There exists in all the parts of the human body, in the interior, 
 as well as on the surface of our organs, vessels whose office it is 
 to absorb, and to. carry into the mass of the blood those substances 
 by which our machine is maintained and kept in repair, as well as 
 what comes off in the continual destruction of our parts ; for, it must 
 not be forgotten, that the organised and living machine, inwardly 
 acted upon by a double impulse, is perpetually undergoing decay and 
 renovation.
 
 !46 OF ABSORPTION. 
 
 XLI. Absorption is effected on substances introduced from with- 
 out ; such is the absorption from the skin, and the absorption of the 
 chyle, &c. At other times, absorption takes place in fluids effused by 
 arterial transudation ; such is the serosity which moistens the serous 
 membranes, the fat, the marrow of the bones, and this absorption, 
 almost always, bears a proportion to transudation, so that the serosity, 
 absorbed as fast as it is effused on the surface of the membranes which 
 lie in close contact, never accumulates so as to separate those mem- 
 branes, except in cases of dropsy. Finally, there is a kind of absorption 
 which may be termed nutritive or molecular, because it exerts its influ- 
 ence on molecules, which, in the process of nutrition, are separated 
 from the organs, and replaced by others. It is this absorption which 
 brings about the decomposition of organs, and to which John Hunter 
 gave the name of interstitial absorption. By means of it, the thymus 
 gland, so voluminous in the foetus, disappears entirely in the adult. This 
 absorption seems to be incessantly going on, and to carry on decom- 
 position, with a force that cannot be resisted. It explains, in a satis- 
 factory manner, the spontaneous erosions of the living solids, of which 
 ulceration* is the consequence. M. Dumas has endeavoured to 
 explain in this way the sensation of hunger, which, in the opinion 
 of that physician, is felt when the absorbents exert on the solid coats 
 of the stomach their activity previously employed in taking up 
 liquids. But to give even a degree of probability to that supposition, 
 which is entirely gratuitous, it would be necessary to shew, that the 
 parietes of the stomach have been found destroyed or thinned, in 
 persons who have died of hunger. The parietes of the stomach of 
 such persons have, on the contrary, been found thickened and in 
 a state of contraction. This inward absorption is promoted by 
 inflammation; hence the advantage of applying heat to indolent 
 tumours, and of exciting a slight inflammation in swollen glands, in 
 order to bring about resolution. It is on that account, that in 
 swelling and induration of the testicle, unattended by cancer of the 
 part, the operation for hydrocele by injection may be safely employed. 
 Of this I had a convincing proof a few years ago : a gardener, born 
 deaf and dumb, had had for some years an hydrocele, which he was in 
 the habit of getting tapped every six months. When I last tapped it, 
 I found the testicle swollen and hard, and three times larger than in its 
 natural state ; the patient, however, was free from pain. A con- 
 siderable quantity of a reddish serous fluid was discharged ; at the end 
 of two days, inflammation of the tunica vaginalis came on, the scrotum 
 became enlarged, and was covered with emollient poultices. At the 
 end of twenty days, the testicle was a good deal lessened in size, and 
 
 * Nosographie Chirurgicale, tome i. art. Ulceres Atoniqucs.
 
 CIRCUMSTANCES INFLUENCING ABSORPTION. t47 
 
 adhered to the inside of the tunica vaginalis: the cure was considered 
 radical, and proved such ; for, though it is now ten years since the 
 operation was performed, the water has not collected, and the patient 
 continues in the laborious employment of his business. 
 
 The process of absorption is very active in children, in women, 
 during sleep, in the morning, when the body _is refreshed by the 
 night's rest. Is a state of weakness favourable or unfavourable to that 
 process ? It is well known, that there are robust men who have inter- 
 course with women infected with the venereal virus, and who escape 
 the contagion, unless they expose themselves to it when debilitated by 
 excesses. A mind free of fear and anxiety has ever been considered 
 in the Eastern countries a safe-guard against the plague. A dog, 
 cceteris paribus, is in much less danger from the bite of a viper, when 
 suddenly bitten, than, when he has been some time gazing at the 
 reptile, and is, more or less, terrified by the sight. But in all these 
 cases, does debility favour the introduction of the contagious matter, 
 by increasing the force of absorption ; or is it not more probable, that 
 by affecting the nervous system, it renders it more susceptible of dele- 
 terious impressions ? 
 
 XLII. Absorption from the external surface. Absorption is much 
 less active on the external surface of the body than on the surface of 
 its internal cavities, and in the very substance of our organs. Cuta- 
 neous absorption, under certain circumstances, has even so little 
 activity, as to have led some physiologists to doubt its existence. The 
 absorbing orifices of vessels which arise on the surface of the body are 
 covered by the epidermis. This covering, which is insensible, and, as 
 it were, inorganic, forms a so?t of separation between the external and 
 internal part of our being, and opposes, or renders mere difficult, the 
 absorption of substances in immediate contact with our body : and if 
 it be considered that we are frequently immersed in the midst of gases 
 and other substances, to a certain degree deleterious, it will be under- 
 stood how essential it was that the absorbing surface of the skin should 
 not be entirely exposed, and that cutaneous absorption should not be 
 easily carried on. 
 
 The increased weight of the body after exercise in wet weather, 
 the abundant secretion of urine after remaining long in the bath, 
 the manifest enlargement of the glands of the groin after keeping the 
 feet immersed, for a considerable time, in water an experiment 
 often performed by Mascagni on himself, the effects of mercurial 
 frictions, &c., shew, however, in an unquestionable manner, that 
 absorption takes place through the skin, with more or less rapidity, 
 according to circumstances. It must be taken into account, that the 
 means which promote cutaneous absorption, operate at least as much 
 by altering the structure of the epidermis, as by increasing the action
 
 CIRCUMSTANCES INFLUENCING ABSORPTION. 
 
 of the absorbing orifices. In this manner the bath appears to operate, 
 by softening the texture of the epidermis; and frictions, by displacing 
 and raising its scales. 
 
 It is by means of frictions that we, succeed in introducing into the 
 lymphatic system medicines possessing purgative, febrifuge, sedative, 
 or diuretic qualities, combined with the gastric juice, or diluted in any 
 other liquids ; for, as has been shewn by the experiments performed at 
 the Salptriere, by MM. Dumeril and Alibert, in the name of the 
 Philomathic Society, the mixture with saliva or gastric juice, of the 
 medicines which are to be administered by friction, is not necessary to 
 ensure their absorption. Extract of opium has soothed pain, bark 
 has checked fits of intermittent fever, rhubarb has procured alvine 
 evacuations, squills have stimulated powerfully the action of -the 
 urinary organs ; nor has the previous mixture of these substances, re- 
 duced into powder with gastric juice, seemed to increase or diminish 
 their efficacy. 
 
 Absorption takes place quickly and readily wherever the epidermis 
 is thin, habitually moist, and the skin delicate, so as to leave almost 
 bare of covering the subjacent parts, as on the lips, in the inside of the 
 mouth, on the surface of the glands, &c. The complete removal 
 of the epidermis favours absorption from all parts of the skin which it 
 covered. Hence the least scratch on the fingers of an accoucheur 
 touching women infected with the venereal virus, exposes him to this 
 peculiar infection, which, in such cases, Js the more to be dreaded, 
 from the admission of the virus by an unusual course. The inoculation 
 of variolous and vaccine matter, equally furnishes proofs of the obstacle 
 which the epidermis presents to cutaneous absorption, and of the 
 facility with which that function takes place, from surfaces denuded of 
 that covering. 
 
 Absorption goes on, likewise, with great activity, from the surfaces 
 of internal parts, but it no where is so considerable as in the intestinal 
 canal, and it would perhaps be the most favourable part for intro- 
 ducing medicinal substances into the animal economy, if, when swal- 
 lowed, they did not undergo changes, by mixing with the gastric 
 jdices ; or with the intestinal fluids and feecal substances, when injected 
 by the rectum. From the evacuation by urine of clysters of warm 
 water, soon after they have been administered, it is to be presumed 
 that the great intestines ab'sorb almost as powerfully as the rest of the 
 digestive canal. A pint of warm water injected into the abdomen 
 of a large dog or sheep, is often absorbed in less than an hour ; 
 and the effusions which take place in those cavities would possibly 
 not require an operation to let them out, if such fluids were not 
 subject to coagulation, and if the absorbing surfaces were not 
 diseased.
 
 OF THE FUNCTION OF ABSORPTION. 149 
 
 Besides absorption from surfaces, there exists, as we have already 
 stated, another which takes place in the living solid, and in the 
 internal substance of the organs. It is by this kind of absorption that 
 the nutritive decomposition is effected; by means of it, the living 
 matter is incessantly renovated. Its vitiated action accounts for the 
 spontaneous formation of ulcers ; the disappearing of the thymus, the 
 atrophy of parts in which nutrition is carried on in a sluggish manner, 
 the resolution of certain tumours, and many other phenomena, are 
 dependent on the same cause. I do not think, however, that it is pos- 
 sible to admit the explanation of the sensation of hunger adopted by 
 Professor Dumas, who believes that it depends on the action of the 
 absorbing orifices directed against the organised substance of the sto- 
 mach, in the absence of aliment on which to act. The sensation of 
 hunger is felt only in the stomach, although its effects extend to all 
 parts of the body ; it begins in a circumscribed spot, its seat is limited, 
 yet absorption takes place every where, so that if the hypothesis in 
 question had any foundation, the sensation of hunger ought to be felt 
 at the heel as well as the pit of the stomach.* 
 
 The radicles from which the lymphatics arise have orifices so very 
 minute that they are imperceptible to the naked eye ; a tolerably 
 accurate notion may be formed of them, by comparing them to the 
 puncta lachrymalia, which are larger and more easily discovered. 
 Each orifice, endowed with sensibility, and with a peculiar power of 
 contraction, dilates or contracts, absorbs or rejects, according as it is 
 affected by the substances which are applied to it. The variations of 
 the absorbing power, according to the age, the sex, the constitution, 
 and different periods of the day, shew that it cannot be compared, as 
 several physiologists have done, to that principle which makes fluids 
 ascend, contrary to the laws of gravitation, in capillary tubes. If 
 absorption were a process merely mechanical, it would in no cas3 be 
 accelerated or retarded, and would proceed with a regularity never 
 observed in the vital functions. The mouth of every lymphatic, when 
 about to absorb, erects itself, draws towards itself and raises the sur- 
 
 * It does not fall to the lot of every one to err like M. Dumas, whose talents 
 and ingenuity I have much pleasure in acknowledging. He imagines rickets to 
 consist in a deficient influence of the nervous system on the bones; which would 
 constitute a kind of paralysis. Anatomy shews the presence of no nerves in the 
 tissue of the bones, and veins and arteries are alone seen to enter the foramina, 
 and no nerves appear to be transmitted through them. The functions of the bones 
 made it unnecessary that they should be endowed with that peculiar sensibility 
 which requires the existence of nerves. The bones are active by being subject to 
 the process of nutrition, but in every other respect they are absolutely passive. 
 In the opinion of some people, such doctrines are real discoveries. Credat Jwlaus 
 Apella^ non ego.
 
 150 OF THE ABSORBENT VESSELS. 
 
 rounding membranous parts, and thus forms a small tubercle, similar 
 to the puncta lachrymalia. These little bulgings deceived Lieberkuhn, 
 and led him to think, that the absorbents of the intestines originated 
 from small ampullulse, or vesicular enlargements, which, as so many 
 exhausted Receivers, pumped up the fluid extracted from the food. 
 This physiologist may further have been led into error, by the nervous 
 papillae of the inner membrane of the canal, swollen by the deter- 
 mination of blood attending irritation, the natural consequence of the 
 friction of the alimentary substances. The inhaling faculty belongs 
 not only to the orifices at the extremity of each radicle, but likewise 
 to the lateral pores, which are infinitely numerous, in the parietes of 
 the vessels.* 
 
 XLIII. Anastomoses, distribution and coiirse of the lymphatics. 
 After arising on the surface, and in the interior of the body, by 
 radicles in close contact, the lympathetics creep and coil themselves, 
 describe numerous curves, unite, then divide, and presently unite 
 again, and from these numerous inosculations, there results a net- 
 work, with close meshes, forming, with that of the blood-vessels, the 
 texture of the cellular tissue and of the membranes. 
 
 Each lamina of cellular tissue is, in the opinion of Mascagni, 
 nothing but a mesh-work of lymphatics; the texture of the mem- 
 branous and transparent tissues, as the pleura and the peritonaeum, 
 resembles that of the laminae of the cellular tissue : in fine, the same 
 vessels form the basis of the mucous membranes which line the internal 
 parts of the alimentary canal of the trachea and urethra. The Italian 
 anatomist succeeded in filling with quicksilver all the tissues which he 
 considered as lymphatic ; but Ruysch, in his admirable injections, 
 reduced all the membranes, and the laminae of the adipose tissue, into 
 a net-work purely arterial, of which the meshes were so very closely 
 united as to leave spaces that could scarcely be perceived by the 
 microscope ; and from his preparations he inferred, that arterial capil- 
 lary vessels, singularly divided and convoluted, form the basis of 
 cellular and membranous tissues. To satisfy one's self, that neither the 
 pleura nor the peritonaeum are formed as Mascagni or Ruysch imagined, 
 one need only consider, that arterial exhalation and lymphatic absorp- 
 tion take place from the whole extent of the internal surfaces, and 
 that these two functions prove the existence of both arteries and 
 absorbents in those membranes and in the cellular tissue. The pre- 
 judices of those two anatomists, so celebrated, the one by his study of 
 the absorbents, and the other by his beautiful injections of the most 
 minute arteries, are to be attributed to the importance which we are 
 pleased to assign to the objects which particularly engage our attention, 
 
 * See Arl'EKJDix, Note Q.
 
 OF THE ABSORBENT VESSELS, 151 
 
 and likewise to the distension of the minute vessels by the injection ; 
 these being distended beyond their natural state, compress and conceal 
 the neighbouring parts. 
 
 The lymphatics, after emerging from among the cellular substance, 
 unite into trunks sufficiently large to be distinguished from the laminae 
 of that tissue. These trunks proceed towards certain parts of the 
 body, there they become united to other, trunks, follow a parallel 
 course, and frequently communicate together. The lymphatics are not 
 single in their course, as the arteries and veins ; they collect together, 
 form fasciculi of different sizes, some of which are deep-seated and 
 accompany the blood-vessels, while others of them are more super- 
 ficial, corresponding to the subcutaneous veins of the limbs, and, 
 like them, lying between the skin and the aponeuroses, and in 
 greatest number on the inner side of the limbs, in which they are 
 best protected against external injuries. The lymphatics of the pa- 
 rietes of the great cavities, those of the viscera, which these cavities 
 contain, are likewise in two layers, the one superficial, the other deep- 
 seated.* 
 
 The absorbents differ likewise from the blood-vessels, in their 
 singularly tortuous course, their frequent communications, and espe- 
 cially in their unequal size in different parts of their extent. An 
 absorbent, of very small dimensions, frequently enlarges, so as to 
 equal in size the thoracic duct, then contracts and again bulges out, 
 though in the length of the vessel in which these differences of size 
 may have been noticed, it may have received no collateral branches. 
 The lymphatics, when completely filled with quicksilver, appear to 
 cover the whole surface of our organs; and the whole body seems 
 enveloped in a net-work of close and small meshes. The metastasis 
 of humours from one part of the body to another at a distance, is 
 easily understood by any one who has seen those numerous inoscu- 
 lations rendered manifest by injection. Metastasis ceases to be an 
 inexplicable phenomenon ; one has no difficulty in conceiving how, 
 by means of the lymphatics, all the parts of the body communicate 
 freely ; how fluids, absorbed by those vessels in one part, may be 
 conveyed into another, and pervade the whole body, without following 1 
 the circuitous route of the circulation ; and that it is, therefore, not 
 altogether impossible, however improbable, that fluids taken into 
 the stomach may be conveyed directly from the stomach to the 
 bladder, and that pus may be removed from the place in which it 
 is collected, and be carried to the place to which irritation calls 
 it forth. All that Bordeu has said of the oscillations and currents 
 of humours through the cellular texture, irr his " Recherches . sur 
 
 * See APPENDIX, Note Q.
 
 152 OF THE ABSORBENT VESSELS. 
 
 le Tissu muqueux" may be equally explained by the anastomoses 
 of the lymphatics. The existence of valves in the lymphatic vessels 
 also promotes the circulation of the lymph through them, and renders 
 it impossible for this fluid to flow through them but in one direction. 
 Hence we must necessarily reject the opinions of our predecessors, 
 who supposed it possible that fluids could be conveyed to the urinary 
 bladder, or to the breasts, by means of the retrograde action of these 
 vessels, as stated in the foregoing page.* 
 
 A young man whom I had ordered to rub in mercury along the 
 inner part of his left leg and thigh, for the cure of a pretty large 
 bubo, was affected, on the third day, with salivation, though he used 
 only half a dram of ointment at each friction. The salivary glands 
 on the left side were alone swollen, the left side of the tongue was 
 covered with aphthae, and the right side of the body remained unaffected 
 by the mercurial action : a clear proof, that the mercury had been 
 carried to the mouth, along the left side of the body, without entering 
 into the course of the circulation, and, perhaps, without passing through 
 any of the conglobate glands ; for that of the left groin, which alone 
 was swollen, did not sensibly diminish in size. Salivation may, there- 
 fore, take place in the cure of the venereal disease, though none of the 
 mercury enter the circulation ; which warrants the opinion, that the 
 action of syphilis, as well as of the remedies which are administered 
 for its removal, operates chiefly on the lymphatic system. 
 
 XLIV. Connexion of lymphatics with their glands. If the fluids 
 absorbed by these vessels can, in consequence of their numerous 
 inosculations, pervade all parts of the body, without mixing with the 
 blood, not a drop can enter the course of the circulation without 
 having previously passed through the glandular bodies that lie in the 
 course of the lymphatics, dispersed like those vessels in all parts of the 
 body, seldom insulated, but in clusters in the hollows of the ham, the 
 arm-pit, in the bends of the groin and elbow, along the iliac vessels, 
 the aorta, and the blood-vessels of the neck, around the base of the jaw 
 and of the occiput, behind the sternum, along the internal mammary 
 vessels, lastly, within the mesentery, in which their number and size 
 bear a proportion to the quantity of absorbents which pass through 
 them. These reddish glandsf varying, in size, of an oval or globular 
 
 * For some further remarks on this subject, see APPEKDIX, Note Q. 
 
 f It is with a view of conforming to the language in common use, that I give the 
 name of gland to those coils of lymphatic vessels which are totally different from 
 the real conglomerate or secretory glands. It might be better, perhaps, to call them 
 ganglions, as has been done by my learned and respected colleague Chaussier, 
 though that name is objectionable, from its association in the mind with the 
 nervous ganglions, whose structure is not at all similar to that of the lymphatic 
 ganglions.
 
 OF THE ABSORBENT GLANDS. 153 
 
 form, have two extremities, one of which is turned towards the part 
 from whence the lymphatics arise, and at which they enter in greater 
 or less number, and are there called " afferentia;' and the other 
 extremity turned towards the thoracic duct, which sends out vessels, 
 fewer in number but of a larger size, and called " efferentia ;" from 
 their use. 
 
 The lymphatics, on reaching the glands, divide, unite again and 
 inosculate, they likewise bend back on themselves, and thus form the 
 tissue of the conglobate glands, which are merely clusters of coiled 
 vessels, united by cellular tissue, in which blood-vessels are distributed, 
 so as to occasion their reddish colour. The coats of the lymphatics 
 are thinner in the glands than elsewhere ; and their dilatations, their divi- 
 sions, and their anastomoses, are likewise more frequent, while they are 
 embraced in the glandular tissue. All the lymphatic vessels, whose 
 course lies in the direction of a gland, do not enter its substance ; several 
 pass b'y the gland and embrace it, forming around it a sort of plexus, of 
 which the ramifications are directed towards other glands, more in the 
 vicinity of the thoracic duct. The lymphatic glands form so essential 
 a part of the absorbent system, they produce on the lymph such 
 indispensable changes, that no lymphatic vessel enters the thoracic duct 
 without having previously passed through these glands. It even fre- 
 quently happens, that the same vessel passes through several glands 
 before opening into that common centre of the lymphatic system. 
 Thus, the vessels which absorb the chyle of the intestinal tube pass 
 several times through the glands of the mesentery. The lymphatics 
 of the liver, situated very near to the receptaculum of Pecquet, 
 have been thought, by some anatomists, not to follow that general 
 rule ; but there are uniformly found, in the course of these vessels, 
 glands which they enter. As, however, the glands are few in number, 
 the lymph conveyed from the liver is only once subjected to the 
 action of the glands; and this circumstance appears to me to explain, 
 in- a satisfactory manner, the transmission of the colouring matter of 
 the bile, which, in jaundice, manifestly discolours the blood, in which 
 M. Deyeux found it by chemical analysis. , . 
 
 XLV. The structure and functions of the lymphatics. The parietes 
 of the lymphatic vessels are formed of two coats, both very thin and 
 transparent, yet very strong, since they support the weight of a column 
 of mercury, which would rupture the coats of arteries of the same 
 calibre. The internal coat, which is the thinner of the two, forms 
 valvular folds, arranged in pairs, like the valves of the veins, and, 
 like them, preventing a retrograde circulation. Although these coats 
 are very strong, and likewise very elastic and contractile, as they 
 may be seen to contract, and to expel the lymph with great im-
 
 154 FUNCTIONS OF ABSORBENT GLANDS. 
 
 petus, when the abdomen of a living animal* is laid open, yet the 
 course of the lymph is far from being as rapid as that of the blood ; 
 it even frequently appears affected with irregular oscillations, such 
 as are to be met with in the circulation 6f the blood through the capil- 
 lary arteries. The numerous dilatations, curvatures, and anastomoses 
 of the absorbents must, in a considerable degree, impede the rapid 
 progress of the lymph, but the circulation must be retarded, chiefly 
 in the glands, as there the vessels are most convoluted, dilated, and 
 form the greatest number of anastomoses, and are most subdivided. 
 Besides, the parietes of the absorbents are thinnest in their passage 
 through the glands, for these may be ruptured by the weight of a 
 column of mercury, which the vessels themselves are able to support. 
 And the action of these vessels, naturally weaker in that situation, is 
 still farther diminished by the close, cellular adhesion which unites 
 together the vessels whose union forms the glandular bodies. 
 
 It was necessary that the course of the lymph should be slackened 
 in its passage through the glands, in order that it might undergo all the 
 changes which those organs are to produce upon it. Although we 
 do not know precisely what those changes are, their object appears 
 to consist in a more perfect union and combination of its elements, 
 and in bestowing on it a certain degree of animalisation, as is seen by 
 the greater tendencies to coagulation of the fluid taken from the vasa 
 efferentia. Another object of the passage of the lymph through the 
 glands, appears to be to deprive it of its heterogeneous particles, 
 or at least to alter their nature, so that they may not become in- 
 jurious when they get into the mass of the fluids. The yellow colour of 
 the glands through which the absorbents of the liver pass, the dark 
 colour of the bronchial glands, the red colour of the mesenteric 
 glands, in animals which have been fed on madder or beet-root, 
 the whiteness of the same glands, while the chyle is passing through 
 them, are circumstances which shew, that the glands separate, or 
 tend to separate, the colouring matter of the lymph, and that if they 
 do not effectually prevent its transmission into the blood, it is 
 because certain colours, as indigo and madder, have too much tenacity, 
 while other substances, as the bile, do not pass through a sufficient 
 number of glands to lose their colour entirely. The blood-vessels, 
 
 * In some cases, the activity of the absorbents appears increased in a singular 
 degree. Thus jaundice has been known to be the immediate consequence of a 
 wound of the liver; and on other occasions, a metastasis of humours has taken 
 place witli the utmost rapidity. I suspect that, in such cases, the substance that 
 has been absorbed circulates by means of the, anastomoses, and pervades the lym- 
 phatics with which the whole body is covered, but without passing through the 
 glands, which would slacken its course, and, to a certain degree, alter its nature.
 
 DISOUDEKS OK ABSORBENT GLANDS. 155 
 
 which are very numerous in the tissue of the conglobate glands, 
 pour into the lymphatics a serous fluid, which dilutes the lymph, in- 
 creases its quantity, and at the same time animalises it. The number 
 of the lymphatic glands is very great ; many are so small as to escape 
 the eye, but become enlarged and visible in certain cases of disease. 
 I have daily opportunities of observing in scrofulous patients swollen 
 glands, in situations in which anatomists have not pointed out any. 
 The absorbent glands are at no time so large or numerous as in 
 infancy. They very frequently disappear in old people, and it is 
 difficult to say, whether they have been totally destroyed, or whether 
 they are merely exceedingly reduced in bulk. 
 
 XLVI. Morbid states of the absorbent glands. The frequent con- 
 gestions of the conglobate glands depend on the stagnation of the 
 lymphatic fluid in their substance, and on the comparative weakness of 
 the sides of the vessels in these parts. The influence of debilitating 
 causes on the lymphatic system acts most powerfully on the glands, 
 which are the weakest part of that system. In such cases, the 
 vessels which enter into the composition of the glands act feebly, or 
 cease to act altogether ; the fluids, of which there is a continual 
 accession, accumulate ; the most liquid part alone penetrates through 
 the glandular organ, the grosser particles remain, the humour 
 thickens, hardens, and forms congestions of various kinds. If there 
 is a tendency to cancer, such tumours, at first indolent, become 
 painful; the more inspissated matter being, in a manner, out of the 
 influence of the vital power, since its vessels are in a state of com- 
 plete atony, undergoes a sort of putrid fermentation, the consequence 
 of which is a destruction and erosion of the cellular tissue, attended 
 by inflammation of the skin and neighbouring parts. The tumour 
 becomes an abscess, and discharges matter rendered liquid by the 
 process of fermentation, and so acrid and irritating, that it extends 
 the affection towards all the parts with which it comes in contact. 
 
 The notions entertained hitherto on cancer are, at once, deficient 
 in precision and accuracy ; and it is to their fallacy that we are to 
 attribute the number of contradictory opinions on the subject of its 
 proper treatment. Too precise a distinction cannot be laid down 
 between the cancerous or phagedenic ulcer, whose seat is always 
 in the skin, or in the mucous membranes (which being mere pro- 
 longations of the skin, retain much of its structure), and those 
 cancers which affect the other parts of the animal economy, especially 
 the lymphatic glands, the testicles, and the breasts. In the cancerous 
 ulcers, peculiarly frequent in the face, the lips, the tongue, in the 
 inner coat of the stomach, of the rectum, and of the uterus, the parts 
 affected with inflammation of a malignant kind are destroyed, without 
 any means of checking the progress of that destructive action, the
 
 156 DISEASES OF ABSORBENT GLANDS. 
 
 cause of which is easily conceived ; while in true cancer, the glandular 
 tumefaction always precedes the cancerous diathesis. As long as the 
 affection consists merely in the obstruction of the vessels by indurated 
 lymph, the tumour is indolent, and is' yet only a scirrhus; but soon 
 all trace of organisation is lost in the tumefied part, the ruptured 
 vessels are lost in the mass of different substances ; the process of 
 fermentation which takes place, converts every part into a grayish 
 pulpy substance, in which the most expert eye can discover no or- 
 ganisation, and no distinction of parts. Whenever this cancerous 
 destruction of parts occurs, whether the whole organ is affected, or 
 whether the disease extends only to a few points, extirpation is the 
 only remedy to be employed ; it is absolutely necessary that a 
 surgical operation should rid the constitution of a part in which organ- 
 isation and life no longer exist. 
 
 The lymphatic glands, which swell in the vicinity of cancerous 
 tumours, have already received, by means of the absorbents, the 
 destructive germ, and must be removed, with the rest of the diseased 
 part, that the operation may be attended with the greater prospect of 
 success. It is very true, that open cancers of the breast may, for 
 a long time, discharge putrid matter, without inducing a cancerous 
 affection of the glands of the axilla. But may not the discharge, in 
 this case, act on the principle of revulsion? and besides, what shall we 
 oppose to experience, which shews that these glands, if not removed 
 along with the cancerous breast, soon becomes affected with cancer ? 
 If the nature of this work did not circumscribe me within certain limits, 
 I should point out several other particulars relative to the history of 
 cancer ; and, among other cases, in my own practice I should relate 
 that of a woman, in whom I removed a cancerous tumour situated on 
 the left side of the chest : this case is remarkable from the number of 
 operations which her disease required, and for which M. Pelletan 
 removed, six years ago, the left breast, and three years ago a gland 
 under the axilla of the same side. 
 
 Th& difference in the termination of glandular swellings aqgr those - 
 arising from cancer, scrofula, or syphilis, makes it probable that there 
 exist ferments, or specific poisons, which dispose the accumulated 
 matter to undergo peculiar changes. 
 
 The venereal virus, absorbed by the lymphatics of the organs of 
 generation, remains for some time in the glands of the groin, before it 
 extends beyond, as is proved by the cure of the venereal disease by 
 extirpating the diseased glands. In short, the impediment which the 
 lymph meets with in passing through the glands, shews why these 
 parts are so frequently the seat of critical abscesses, by which we judge 
 of the nature of several fevers of a malignant kind. In the plague of 
 Eastern countries, the virus that occasions this dreadful malady is
 
 OF THE THORACIC DUCT. 157 
 
 disseminated throughout the body, collects in the glands, is transmitted 
 through them with difficulty, brings on an irritation and gangrenous 
 inflammation, terminating in pestilential buboes. 
 
 XLVII. Of the thoracic duct. The thoracic duct may be con- 
 sidered as the centre in which the lymphatic system terminates; it 
 arises at the upper part of the abdomen, from the union of the chylous 
 vessels with the lymphatics coming from the inferior extremities. 
 At the part where all these vessels meet, there is a dilatation, a sort of 
 ampullula, called lumbar cistern, receptaculum chyli, or of Pecquet, 
 which, in truth, is not always found, and the size of which is very 
 variable. The thoracic duct enters the chest through the opening in the 
 diaphragm through which the aorta passes; it then ascends along the 
 spine, on the right side of the aorta, within the posterior mediastinum. 
 At the upper part of the chest opposite to the seventh cervical 
 vertebra, it inclines from the right to the left side, passes behind the 
 oesophagus and the trachea, and opens into the subclavian vein of 
 the left side, at the back part of the insertion of the internal jugular 
 into that vein. While the thoracic duct is ascending along the spine, 
 it receives the lymphatics of the parietes of the chest ; those of the 
 lungs enter it as it passes behind the root of these organs. In 
 its course from the right towards the left side, it receives the absorbents 
 of the right upper extremity, and those of the right side of the head 
 and neck. Lastly, it unites with those vessels which are coming from 
 the left side of the head and neck, as well as from the left upper extre- 
 mity, just before opening into the subclavian vein. The thoracic duct 
 sometimes has its insertion in the jugular vein of the same side, and 
 not unfrequently the lymphatics of the right side of the chest, neck, 
 and head, and of the right upper extremity, unite to form a second 
 duct, which opens separately into the right subclavian vein.* What- 
 ever be the vein into which the duct opens, its structure is the same as 
 that of the lymphatics, and its inner part is furnished with valvular 
 folds. Its increase of size is not progressive as it approaches ^towards 
 its termination ; on the contrary, there are seen, here and there, dilata- 
 tions of different sizes, separated by proportionate contractions. Some- 
 times it divides into several vessels, which inosculate and form lym* 
 phatic plexuses. The opening at which the thoracic duct enters the 
 
 * In some cases, lymphatic vessels, in other parts of the body, are seen to 
 open into neighbouring veins. This enables one to account for the presence of the 
 chyle which is said to have been found in the meseraic veins, into which it had 
 been poured by some lacteal. Mascagni was aware of this anatomical fact. The 
 lymphatic system is, however, the most subject to deviations of any in the animal 
 economy. 
 
 See APPENDIX, Note Q, for later observations connected with the subject mat- 
 ter of this note.
 
 158 OF THE NATURE OF THE LYMPH. 
 
 subclavian vein is furnished with a valve, better calculated to prevent 
 the flow of blood into the lymphatic system, than to moderate the too 
 rapid flow of the lymph into the torrent of circulation. Compression 
 of the thoracic duct, in aneurism of the heart and aorta, gives rise to 
 several kinds of dropsy, a disease always depending on the loss of equi- 
 librium between the processes of inhalation and exhalation, either from 
 increased action of the exhalants, or from the absorbents refusing to 
 take up the lymph, in consequence of obstruction in the glands, or of 
 compression of the duct. 
 
 XLVI1I. Of the nature of the lymph and chyle. The nature of 
 the lymph is far from being as well understood as that of the vessels 
 along which it circulates. Haller considers it as very analogous to the 
 serum of the blood, and says that this substance, to which he frequently 
 gives the name of lymph, is, like the fluid contained in the absorbents, 
 slightly viscous and saltish ; that heat, alcohol, and the acids coagu- 
 late it ; in short, that it possesses all the qualities of the albuminous 
 fluids. The serum of the blood exhaled, throughout the extent of the 
 internal surfaces, and even within the substance of our organs, by the 
 capillary arteries, is absorbed by the lymphatics, and is one of the 
 principal sources of the lymph, which resembles it much. It may 
 be conceived, however, that the lymph must be much more compound 
 than the serum of the blood, since the lymphatics which absorb, almost 
 indiscriminately, every kind of substance, take up what comes off from 
 our organs, and the recrementitious parts of our fluids, and these, 
 when marked by striking qualities, are sometimes recognisable in the 
 absorbents, as fat, by its not mixing with aqueous fluids and bile, 
 by its deep yellow colour. 
 
 The chyle, which is necessarily affected by the various kinds of 
 food which we use, has different appearances in the same persons, 
 varying according to the quality of the different substances on which 
 we feed : indigo gives it a blue colour ; it is reddened by madder and 
 beet-root ; and is changed to green by the colouring matter of several 
 vegetables, &c. In a great number of experiments performed on living 
 animals, it has always appeared to me such as it is described by 
 authors, white, with a slight viscidity, and very like milk containing a 
 very small quantity of flour. It is easy to collect a certain quantity of 
 chyle, by tying the thoracic duct of a large dog, of a sheep, or even of 
 a horse, as was done several times at the veterinary school at Alfort. 
 This fluid, when exposed to the air, on cooling, separates into two 
 parts, the one forming a kind of gelatinous coagulum, very thin and 
 not unlike the buffy coat of inflammatory blood ; the other, in greater 
 quantity and liquid, rising above the coagulum, on its being detached 
 from the sides of the cup, to which it adheres. The coagulated mass is 
 semi-transparent, of a light pink colour, does not resemble the curd of
 
 OF THE NATURE OF THE LYMPH. 159 
 
 milk ; so that all that has been said by a few modern physiologists, the 
 exact resemblance which they have pretended to discover between milk 
 and chyle, is totally void of foundation.* 
 
 The lymph, which constantly unites with the chyle before the 
 latter enters the sanguiferous system, on being received into a vessel 
 by Mascagni, coagulated in the space of seven or ten minutes, turned 
 sour, and soon separated into two parts, the one more abundant, serous, 
 in the midst of which there floated a fibrous coagulum, which by 
 contracting formed into a small cake on the surface of the fluid. 
 Hence he concludes, contrary to the opinion of Hewson, that lymph 
 consists, for the greatest part, of serum, and that fibrine constitutes its 
 least part. 
 
 XLIX. The practice of surgery in a great hospital has afforded 
 me frequent opportunities of examining the lymph which is dis- 
 charged, in abundance, from ulcerated scrofulous tumours in the 
 groin, in the axilla, and in various other parts of the body. I have 
 always met with a liquid nearly transparent, slightly saline, coagu- 
 lable by heat, alcohol, and the acids. Small fibrous flocculi form, even 
 on the surface of the cloths which are wetted with it, and shew the 
 existence of two parts ; the one a gelatino-albuminous fluid holding 
 in solution several salts ; the other, in smaller quantity, is a fibrous 
 substance which concretes spontaneously. The lymph in rnan.and the 
 warm-blooded animals appears to me in every respect similar to the 
 fluid which is contained in the vessels of white-blooded animals.f 
 
 * According to the analysis of the chyle performed by Dr. Marcet, and pub- 
 lished in the sixth volume of the Transactions of the Medico-Chirurgical Society, 
 this fluid presents very different properties according as it is the product of vege- 
 table or animal food. When it proceeds from vegetable diet, it contains much 
 more carbon, and may be preserved a much longer time, without undergoing putre- 
 faction, than that which is the product of animal food. The former, also, is nearly 
 transparent, whilst the latter is milky, very putrescent, and, besides albumen, con- 
 tains an oily matter resembling cream, and furnishes much carbonate of ammonia by 
 distillation. Neither kind of chyle contains gelatine, which seems to be replaced, 
 whatever may be the nature of the food, by albumen. J. C. 
 
 j- See APPENDIX, Note Q.
 
 160 OF THE CIRCULATION*. 
 
 CHAPTER III. 
 
 OF THE CIRCULATION. . 
 
 L. The Circulation defined, and its Uses stated LI. Of the Structure and Action 
 
 of the Heart LII. and LIII. Of the Mechanism of the Circulation through 
 
 the Heart. LIV. Of the Action of the Arteries. LV. Of the Structure of 
 
 the Arteries LVI. Of the Formation of Aneurisms. LVII. Of the Action 
 
 of Arteries LVI II. and LIX. Of the Pulse. LX. Of the Capillary Ves- 
 sels LXI. Anastomoses and Properties of the Capillaries LXII. Of the 
 
 Actions of the Veins LXIII. to LXV. Of the Venous Circulation, &c 
 
 LXVI. and LXVII. Of the general, greater, or systemic Circulation 
 
 LXVIII. Of the Pulmonary or lesser Circulation. 
 
 L. THE term circulation is applied to that motion by which the 
 blood setting out from the heart is incessantly carried to all parts of 
 the body by means of the arteries, and returns by the veins to the 
 centre whence it began its circuit. 
 
 The uses of this circulatory motion are to expose the blood, changed 
 by mixing with the lymph and the chyle, to the air in the lungs (respi- 
 ration); to convey it to several viscera, in which it passes through dif- 
 ferent steps of purification (secretions) ; and to send it into the organs 
 whose growth is to be promoted, or whose losses are to be repaired, by 
 the nutritive and animalised part of the blood brought into a state of 
 perfection by these successive processes (nutrition). 
 
 The circulatory organs are less useful in elaborating than in con- 
 veying the fluids. To form a just conception of their uses, one may 
 compare them to those workmen in a large manufactory in which 
 various kinds of goods are made, who are employed in carrying the 
 materials to those who are to work them ; and as among the latter 
 some finish the work, while others prepare the materials, so the liyigs 
 and the secretory glands are continually occupied in separating from 
 the blood whatever is too heterogeneous to our nature to become 
 assimilated to our organs, or to afford them nourishment. 
 
 To understand thoroughly the mechanism of this function, it is neces- 
 sary to study separately the action of the heart, that of the arteries 
 which arise from it, and, lastly, that of the veins which enter it. The 
 union of these three classes of organs forms the circle of the circulation. 
 
 LI. Of the structure and action of the heart. In man and in all 
 warm-blooded animals the heart is a hollow muscle, the inner part of 
 which is divided into four large cavities which communicate with one 
 another; from these, vessels arise which convey the blood to all parts of 
 the body, and the vessels which bring it back from all those parts like- 
 wise terminate in these cavities.
 
 POSITION or THE HEAR!. ll 
 
 The heart is placed in the chest, between the lungs, above the 
 diaphragm, whose motions it follows; it is surrounded by the pericar- 
 dium, a dense and fibrous membrane admitting of very slight extension, 
 closely united to the substance of the diaphragm, covering the heart 
 and great vessels, without containing them in its cavity, furnishing an 
 external covering to the heart, and bedewing its surface with a serous 
 fluid which, never accumulating, except in disease, facilitates its motion 
 and prevents its adhering to the neighbouring parts. The principal 
 use of the pericardium is to fix the heart in its place, to prevent its 
 being displaced into other parts of the chest, which could not happen 
 without occasioning a fatal disorder in the circulation. If, after having 
 laid open the chest of a living animal, by raising the sternum, an inci- 
 sion is made into the pericardium, the heart protrudes through the 
 opening, and moves to the right and left by bending itself on the origin 
 of the large vessels ; the course of'the blood is then intercepted, and 
 the animal threatened with immediate suffocation.* 
 
 In man, the heart is placed nearly towards the union of the upper 
 third of the body with the lower two-thirds ; it is, therefore, nearer to 
 the upper parts ; it holds them under a more immediate control ; and 
 as that organ keeps up the action of all the rest, by the blood which it 
 sends into them, the parts above the diaphragm have much more 
 vitality than the parts beneath. The skin of the upper part of the body, 
 and especially of the face, has more colour and is warmer than that 
 of the lower parts ; the phenomena of diseases come on more rapidly 
 in the upper parts ; they are, however, less liable to put on a chronic 
 character. 
 
 The bulk of the heart, compared to that of other parts, is larger 
 in the foetus than in the child that has breathed, in short men than in 
 those of high stature. The heart is likewise larger, stronger, and more 
 powerful, in courageous animals than in weak and timid creatures. 
 
 This is the first instance of a moral quality depending on the original 
 conformation of parts ; it is one of the most striking proofs of the influ- 
 ence of the moral character of man on his physical nature. Courage 
 arises out of the consciousness of strength, and the latter is in propor- 
 tion to the activity with which the heart propels the blood towards all 
 the organs. The inward sensation occasioned by the afflux of the 
 blood is the more lively and better felt when the heart is powerful. It 
 is on that account that some passions, for example, anger, by in- 
 creasing- the action of the heart, increase a hundred fold both the 
 strength and courage ; while fear produces an opposite effect. Every 
 being that is feeble is timorous, and shuns danger, because an inward 
 
 * For some remarks on the intimate connexion, owing to the above con- 
 formation, subsisting between the Functions of Respiration and Circulation, see 
 APPENDIX, Notes R and U J. C. 
 
 M
 
 162 DESCRIPTION OF THE HEART. 
 
 feeling warns him that he does not possess sufficient strength to resist it. 
 It may perhaps be objected, that some animals, as the turkey-cock and 
 the ostrich, possess less courage than the least bird of prey, that the ox 
 has less than the lion and other carnivorous animals. What has been 
 said does not apply to the absolute, but to the relative size of the 
 heart. Now, though the heart of a hawk be absolutely smaller than 
 that of a turkey-cock, it is nevertheless larger in proportion to the other 
 parts of the animal. Besides, the bird of prey, like the other carni- 
 vorous animals, in part owes his courage to the strength of his weapons 
 of offence. 
 
 Another objection, more specious, but not better founded, is drawn 
 from the courage manifested on certain occasions by the most timid 
 animals ; for example, by the hen in protecting her young ; from the 
 courage with which other animals, pressed by hunger or lust, surmount 
 all obstacles ; but particularly from the heroic valour of men of the most 
 feeble bodies. All these facts, however, are only proofs of the influence 
 of the mind on the body. In civilised man, the prejudices of honour, 
 interested considerations, and a thousand other circumstances, degrade 
 his natural inclinations, so as to make a coward of one whose 
 strength is such as would induce him to brave all kinds of dangers; 
 while, on the other hand, men whose organisation should render them 
 most timid, are inspired to perform the most daring actions. But all 
 these passions, all these moral affections, operate only by increasing 
 the action of the heart, by increasing the frequency and the force of its 
 pulsations, so that it excites the brain or the muscular system by a 
 more abundant supply of blood. 
 
 The heart is not quite so ovoid in man as it is in several animals, 
 nor is it parallel to the vertebral column, but it lies obliquely, and is 
 flattened towards the side next the diaphragm on which it rests. 
 
 Of the four cavities which form the heart, two are, in a measure, 
 accessary, viz. the auricles : they are small musculo-membranous bags 
 opposed to each other, receiving the blood of all the veins, and pouring 
 that fluid into the ventricles, at the base of which the auricles are, 
 as it were, applied. The ventricles are two muscular bags separated 
 by a partition of the same nature, and belonging equally to both : 
 they form the greatest part of the heart, and give origin to the 
 arteries. 
 
 The auricle and ventricle on the right side are larger than those 
 on the left. But that difference of size depends as much on the 
 manner in which the blood circulates at the approach of death, as ou 
 the original conformation of the lungs. On the point of death, the 
 lungs expand with difficulty, and the blood sent into them by the con- 
 tractions of the right ventricle, being no longer able to circulate through 
 them, collects in that cavity, flows back into the right auricle, in which
 
 OF THE CAVITIES OF THE HEART. 163 
 
 the veins continue to deposit blood, stretches their parietes, and in- 
 creases considerably the dimensions of those cavities. The capacity 
 of the right cavities is, however, originally greater than that of the 
 left, and is proportioned to that of the venous system which opens into 
 them. The right cavities of the heart, which might be called its venous 
 cavities, have likewise thinner parietes than the left or arterial, and in 
 this respect the same difference is observed as in the parietes of the 
 arteries and veins. The right ventricle, having to send the blood des- 
 tined to the lungs to a very short distance, and through a tissue easily 
 penetrated, requires but a moderate impelling force. 
 
 As will be shewn, in speaking of respiration, a function of which 
 the physiological history is not easily separated from that of the circu- 
 lation, the heart may further be considered as formed of two parts in 
 contact, the one right or venous, the other left or arterial. Notwith- 
 standing the juxta-position of these two parts of the same organ, they 
 are perfectly distinct, and the blood in each cavity is very different from 
 that in the other. The blood in the adult can never pass immediately 
 from the one to the other : the right side of the heart receives the 
 blood of the whole body, and transmits it to the lungs ; the left side of 
 the heart receives the blood of the lungs, and distributes it over the 
 whole body; so that, in a physiological point of view, the lungs form 
 a part of the circle of the circulation, and serve as an indispensable 
 medium between the two divisions of the heart ; and, as will be 
 seen hereafter, their part of the circle is by no means the least 
 important. 
 
 If there existed between the ventricles a direct communication, the 
 venous blood would mix with the arterial, and the union of these two 
 fluids would mutually impair the qualities of each. Recent observa- 
 tions have furnished an opportunity of judging of the effects of such a 
 communication between the ventricles, which had been imagined by 
 the ancients, but of which no case had yet been met with. A man, 
 forty-one years of age, came to the Hopital de la Charite, to undergo 
 the operation of lithotomy. He was remarkable for the lividity of his 
 complexion, the turgescence of the vessels of the conjunctiva, and the 
 thickness of his lips, which, like the rest of his face, were of a dark 
 colour; his respiration was laborious, his pulse irregular; he could not 
 utter two words in succession without taking breath, was obliged to 
 sleep in a sitting posture, and was particularly remarkable for his indo- 
 lence. This indolence, joined to great simplicity of nature, was such, 
 that he had never been able to maintain himself without the assistance 
 of hi* wife. A very small quantity of blood was taken from his arm, in 
 consequence of which his pains were diminished, but his difficulty of 
 breathing increased, was followed by syncope, and he died from suffo- 
 cation. On opening his body, his heart was found filled with blood,
 
 1<54 COMMUNICATION BETWEEN ITS CAVITIES. 
 
 and especially the right auricle, which was considerably distended; the 
 pulmonary artery was aneurismal, and uniformly distended from the 
 right ventricle to its division ; none of its coats had yet given way. 
 The two ventricles of the heart were of nearly the same capacity, and 
 the relative thickness of their parietes did not vary so much as in 
 health. The partition between them contained an opening of commu- 
 nication of an oblong shape, about half an inch in extent, and directed 
 obliquely from below upwards, from before backward, and from left to 
 right ; so that, not only the direction of the opening, but likewise a 
 kind of valve, formed in the right ventricle by a fleshy column, so 
 placed as to prevent the return of the blood into the left ventricle, 
 clearly shewed that the blood flowed from the left into the right ven- 
 tricle, and thence into the pulmonary artery. The ductus arteriosus, 
 an inch in length, and large enough to admit a goose quill, allowed, as 
 in the foetus, a free passage to the blood, from the pulmonary artery 
 into the aorta. The foramen ovale was closed. 
 
 This singular conformation explains, in the most satisfactory man- 
 ner, the phenomena observed during the life of the patient, and the 
 organic affection of the pulmonary artery. There was necessarily in 
 this vessel a mixture of venous and arterial blood, and this blood was 
 sent into it in part by the action of the left ventricle, with an increased 
 impetus, which accounts for the aneurism. The blood which reached 
 the lungs was already vivified, and required less action from that 
 organ to complete its oxydation ; on the other hand, the right auricle 
 emptied itself, with difficulty, into the right ventricle, in part filled 
 with the blood which the left ventricle sent into it with greater force : 
 hence the extreme difficulty in the venous circulation, the lividity of the 
 complexion, the colour and the puffiness of the face, and the habitual 
 and general torpor. This state of languor and inactivity might like- 
 wise depend on the flow of the venous blood into the aorta along the 
 ductus arteriosus. It is worthy of observation, however, that this 
 impure blood was not transmitted to the brain, whose vital excitement 
 it would not have been able to maintain. The lower extremities bore 
 no proportion to the upper, and this inequality, analogous to what is 
 observed in the foetus, depended on a similar cause. The morbid pre- 
 paration made from this person was deposited by M. Deschamps in the 
 museum of the Ecole de Medecine of Paris, and was, by their desire, 
 modelled in wax. M. Beauchene, junior, presented the same museum 
 with a similar preparation, which he procured from a subject in the 
 dissecting-room. 
 
 Several anatomists have paid attention to the structure of the 
 heart ; much has been said on the subject of the peculiar arrangement 
 of the muscular fibres which form its parietes ; yet the only result that 
 can be obtained from all these researches is, that it is absolutely impos-
 
 STRUCTURE OF THE HEAKT. 165 ., 
 
 sible to unravel the intricacy of these fibres.* Fibres of the ordinary 
 structure, and crossing each other in various directions, form the two 
 auricles ; other and more numerous fibres form the parietes of the ven- 
 tricles, reach from the apex to the base, extend into the septum which 
 divides them, pass from the one to the other, and are lost in each 
 other in several points. They are exceedingly red, short, close, and 
 united by a cellular tissue, in which fat scarcely ever accumulates. 
 
 These fibres, forcibly pressed against each other, form a tissue 
 similar to the fleshy part of the tongue, endowed with but little sensi- 
 bility, but contractile in the highest degree. Vessels and nerves, in . 
 considerable number, if compared to the bulk of the heart, pervade 
 this muscular tissue, whose contraction, whatever in other respects may 
 be the direction of its fibres, tends to draw towards the centre of the 
 cavities every point of their parietes. Lastly, a very fine membrane 
 lines the inner part of these cavities, facilitates the flow of the blood, 
 and prevents the infiltration of that fluid. 
 
 * On this point the author is by no means correct. The structure of the heart 
 may be demonstrated with tolerable accuracy. The latest and most correct descrip- 
 tion of it has been furnished by J. F. Vauss, teacher of anatomy in the University 
 of Lieges. 
 
 As an accurate view of the distribution of its fibres is requisite to enable us to 
 know the nature of the actions of this viscus, the following account by this.^ anato- 
 mist is here introduced : 
 
 " The heart is a conical hollow muscle, covered by a serous (fibro-serous) mem- 
 brane, the pericardium, lined by a membrane, which is of a different nature in 
 each ventricle, and composed of three layers of muscular fibres, the superficial one 
 commqn to both ventricles the middle one at least four times as large as the pre- 
 ceding, and, like it, common to the two great cavities of the heart, and the 
 lower one divided into two parts, the right and the left, each belonging to the 
 corresponding ventricle ; both of them forming the septum by their junction, and 
 giving birth to the carneae column. 
 
 " The other layer is very fine ; its bundles of fibres, which become more oblique 
 as they get lower, are directed, the anterior ones from the right to left, and the 
 posterior ones from left to right, from the base to the apex of the heart, where they 
 are confounded with the fibres of the middle layer. 
 
 " The fibres of the middle layer are much more numerous, and follow the 
 same direction; only they are more oblique, and are not all of them carried to 
 the apex of the heart. The inferior fibres only reach the apex, and are there 
 confounded with the fibres of the outer layers ; whilst the others, according as 
 they become more superficial, reach the posterior furrow, where the layer untwists 
 itself, to form the two unequal portions which compose the lower layer of each 
 ventricle. , . 
 
 " The lower layer of the right venttf.cle, which is much thinner than that of 
 the left, separates itself from the latter ori^level with the posterior furrow, and is 
 carried backwards on the outside before,-3tod then within the ventricle which it 
 immediately envelopes. All its bundles bend from below upwards, and crossing 
 the direction of those of the middle layer,lbe fixed, the upper ones, which are 
 almost transverse, to the circumference of t^Kbriculo-ventricular opening, and to
 
 166 CIRCULATION IN THE HEART. 
 
 LI I. Of the circulation through the heart. If we suppose, for a 
 moment, that all the cavities of the heart are perfectly emptied of blood, 
 and that they are filled in succession, the following may be considered 
 as the mechanism of the circulation through the heart. The blood 
 brought back from every part of the body, and deposited into the right 
 auricle by the two venae cavse and by the coronary vein, separates its pa- 
 rietes, and dilates it in every direction. The irritation attending the pre- 
 sence of the blood stimulates the auricle to contraction : this fluid, which 
 is incompressible, flows back in part into the veins, but it chiefly passes 
 into the pulmonary ventricle through a large aperture, by means of 
 which it communicates with the right auricle. The auricle, after 
 freeing itself of the blood with which it is filled, relaxes and again 
 dilates by the accession of a new supply of this fluid, continually 
 brought by the veins which open into it. 
 
 the anterior part .of the mouth of the pulmonary artery ; the others, which are 
 longer and more oblique, and which form the right side of the septum, successively 
 to the part of that orifice which is between the two ventricles, and to its posterior 
 part. 
 
 " The lower layer of the left ventricle, which is much thicker than that of the 
 right, arises, like it, from the middle layer, on a level with the posterior furrow. 
 Its bundles run from behind to before, between the two cavities, thus forming the 
 left side of the septum ; reach the anterior furrow ; then, running from right to 
 left, and from below upwards, they surround the ventricles ; and crossing the line 
 of the bundles of the middle layer, are fixed successively, one by the side of the 
 other, to the origin of the aorta, and to the opening of communication between the 
 ventricle and auricle, all the way to the upper extremity of the posterior furrow. 
 
 " The lowest bundles on each side alone follow a different direction. These 
 bundles, after separating from the others, approach the centre of the corresponding 
 ventricle, and form the carneae columnae of the heart. 
 
 " Thus, all the fibres of the superficial layer assume the form of a lengthened 
 spiral, which takes a direction from the base towards the apex of the heart, where 
 the fibres are confounded with those of the middle layer, after having made a turn, 
 or a turn and a half. Those of the middle layer have the same form, the same 
 general direction, and the same origin ; but they are more oblique, and are so 
 arranged that one part only of them reach the apex of the heart, whilst the greater 
 part terminate at its posterior furrow. Those of the last layer of each ventricle 
 have still a spiral form, but the screw takes the inverse direction ; for the fibres 
 stretch from the posterior furrow to the base of the heart, and they do not reach 
 that part until they have surrounded the corresponding ventricle from right to left, 
 crossing the line of the fibres of the two other layers. The septum is formed by the 
 junction of the two lower layers, with the addition of a few bundles, which run 
 from the apex of the heart, and appertain to the middle and superficial layers, which 
 are mixed together at that part. 
 
 ** The structure of the auricles is less regular. In general, the fleshy fibres pass 
 from the circumference of the mouths of the veins, and from the auriculo-ventri- 
 cular opening, to be distributed over the parietes, and especially on the septum ; 
 where, in the situation of the fossa ovalis, they form two crescents, the concave parts 
 of which are opposed to each other." 
 
 For remarks on the Functions of the Heart, see APPENDIX, Note R. J. C.
 
 CIRCULATION IN THE HEART. 167 
 
 However, the right ventricle, filled with the blood which it has 
 received from the auricle, contracts in its turn on the fluid whose pre- 
 sence excites its parietes, and tends, in part, to return it into the right 
 auricle, and to send it along the pulmonary artery. Regurgitation 
 from the ventricle into the auricle is prevented by the tricuspid valve, 
 a membranous ring surrounding the edge of the opening of commu- 
 nication, the free edge of which is divided into three divisions, to 
 which are attached small tendons terminating in the columilee car- 
 nese of the heart. These valves, laid against the parietes of the ven- 
 tricle the instant the blood passes into its cavity, recede from them 
 when it contracts, and rise towards the auricular opening. They can- 
 not be forced into the auricle, as their free and loose edge is kept in 
 its situation by the columnse carnese, which are like so many little 
 muscles, whose tendons, inserted into the loose edges of the valves, 
 bind them down when the stream of blood tends to force those mem- 
 branous folds towards the auricles. The three divisions, however, of 
 the tricuspid. valve, by rising towards the auricular aperture, return 
 into the auricle all the blood contained in the inverted cone which 
 they form immediately before rising. Besides, these three portions of 
 the tricuspid valve do not close completely the aperture around which 
 they are placed ; they are perforated by a number of small holes : a 
 part of the blood, therefore, returns into the auricle, but the greatest 
 portion is sent into the pulmonary artery. The action of this vessel 
 begins when the parietes of the ventricle are in a state of relaxation ; 
 and the blood would be forced back into the ventricle, if the sigmoid 
 valves, by rising suddenly, did not prevent it. Supported on a kind 
 of floor, formed by three valves, which lie across the calibre of the 
 vessel, the blood pervades the tissue of the lungs, and flows along the 
 divisions of the pulmonary vessels ; from the arteries it passes into the 
 veins, and these, four in number, return it into the left auricle. This 
 auricle, stimulated by the presence of the blood, contracts in the same 
 manner as the right; part of the blood flows back into the lungs, but 
 the greatest part enters the left ventricle, which sends it along the 
 aorta to every part of the body, whence it returns again to the heart 
 by the veins. The regurgitation of the blood into the left auricle is pre- 
 vented by the mitral valve, which is similar to the tricuspid, except that 
 its loose edge is divided only into two divisions. As soon as the blood 
 has reached the aorta, this vessel contracts, its sigmoid valves fall, and 
 the blood is sent to every part of the body, which is supplied by some 
 of the innumerable branches of that great artery. 
 
 In a natural state, the circulation is not carried as has been just 
 stated ; and we have supposed this successive action of the four cavities 
 of the heart, only to render more intelligible the mechanism of the cir- 
 culation in that organ. If we lay bare the heart in a living animal, we
 
 168 ACTION OF THE HEART'S CAVITIES. 
 
 observe that the two auricles contract at the same time, and that the 
 contraction of the ventricles is likewise simultaneous, so that while the 
 auricles are contracting, to expel the blood which fills them, the ven- 
 tricles are dilating to receive it. This* successive contraction of the 
 auricles and ventricles is readily explained, by the alternate application 
 of the stimulus which determines the action of these cavities. The 
 blood which the veins bring into the auricles does not excite their con- 
 traction till a sufficient quantity has been collected. While this accu- 
 mulation is taking place, they yield, and the resistance which is felt on 
 touching them,, during their diastole, depends, almost entirely, on the 
 presence of the blood which separates and supports their parietes.* The 
 same applies to the ventricles ; they cannot contract until a sufficient 
 quantity of blood is collected within them : that there remains some 
 blood in these cavities, (for they are never completely emptied,) is 
 no objection to the theory, since this small quantity is not sufficient 
 to bring on contraction of the heart, and is not worth taking into 
 account. 
 
 If I am asked why the four cavities of the heart do not all contract 
 at once, I answer, that it is easier to assign the final than the proxi- 
 mate cause. If the contraction of these cavities had been simultaneous 
 instead of being successive, it is evident that the auricles could not 
 have emptied themselves into the ventricle. The alternate action is, 
 moreover, absolutely necessary, as the heart, any more than the other 
 organs, is unable to keep up a perpetual action ; the principle of its 
 motion, which is soon exhausted, being incapable of restoring itself 
 except during rest. But, as was observed at the beginning of this 
 work, in speaking of the vital power and functions, the alternations of 
 action and repose in organs which, like the heart, perform functions 
 essential to life, must be extremely short in their duration, and at very 
 close intervals. 
 
 The cavities of the heart, however, are not entirely passive during 
 dilatation, and the action of that organ does not wholly depend on the 
 excitement of the blood on its parietes, since the heart, after it has 
 been torn from the body of a living animal, palpitates, its cavities con- 
 tract and dilate, though quite emptied of blood, and appear agitated 
 by alternate motions, which become fainter as the part gets cold. If 
 you attempt to check the diastole of the heart, this organ resists the 
 hand which compresses it, and its cavities appear endowed with a 
 power which Galen termed pulsive, in virtue of which they dilate to 
 receive the blood, and not because they receive it.* In that respect 
 the heart differs essentially from the arteries, whose dilatation is occa- 
 
 * See the APPENDIX, Note R, for some recent opinions and experiments on 
 this luhject. ./. C.
 
 ACTION OF THE HEART. 169 
 
 sioned by the presence of the blood, whatever some physiologists may 
 have said to the contrary. I have repeated, but unsuccessfully, the 
 famous experiment by which it is attempted to be proved that these 
 vessels have the power of moving independently of the presence of 
 the blood. An artery, tied and emptied of blood, contracts between 
 the two ligatures, and is no longer seen to move in alternate con- 
 tractions. 
 
 LIII. The heart manifestly shortens itself, and the base approaches 
 towards the apex during the systole or contraction of the ventricles. 
 If it became elongated, as some anatomists have thought, the tricuspid 
 and mitral valves would be incapable of fulfilling the functions to 
 which they are destined, since the columnee carnese, whose tendons are 
 inserted in the edges of these valves, would keep them applied to the 
 parietes of the ventricles. The pulsations which are felt in the interval 
 between the cartilages of the fifth and sixth true ribs, are occasioned 
 by the apex of the heart, which strikes against the parietes of the chest. 
 In the explanation of this phenomenon, it is not necessary to admit the 
 elongation of the heart during its systole; it is sufficient to consider 
 that the base of the heart, in which the auricles are situated, rests 
 against the vertebral column, and that these two cavities, by dilating 
 at the same time, and by their inability to move the vertebrae before 
 which they are situated, displace the heart, and thrust it downwards 
 and forwards. This motion depends, likewise, on the effort which the 
 blood sent into the aorta makes to bring to a straight line the curvature 
 of that artery, which re-acts, and carries downwards and forwards the 
 whose mass of the heart, as it were suspended to it. 
 
 The quantity of blood which each contraction of the ventricles 
 sends into the aorta and pulmonary artery, most probably does not 
 exceed two ounces in each of these vessels. The force with which the 
 heart acts on the blood which it sends into them, is but imperfectly 
 known, however numerous the calculations by which it has been 
 endeavoured to solve this physiological problem. In fact, from Keil, 
 who estimates at a few ounces only the force of the heart, to Borelli, 
 who makes it amount to one hundred and eighty thousand pounds, we 
 have the calculations of Michelot, Jurine, Robinson, Morgan, Hales, 
 Sauvages, Cheselden, &c. ; but as Vicq. d'Azir observes, not one of 
 these calculations is without some error, either anatomical or arith- 
 metical : hence we may conclude, with Haller, that the force of the heart 
 is great, but that it is, perhaps, impossible to estimate it with mathe- 
 matical precision. If we open the chest of a living animal, and make 
 a puncture in his heart, and introduce a finger into the wound, 
 pretty considerable pressure is felt during the contraction of the 
 ventricles. 
 
 Those who admit to its full extent Harvey's opinion on the circu-
 
 170 OF THE ACTION OF THE ARTERIES 
 
 lation of the blood, and who think with him that the heart is the sole 
 agent of the circulation, over-rate the power of that organ, so as to 
 proportion it to the extent of the course which the blood is to take, and 
 to the number of the obstacles which i is to meet in its way. But, as 
 I am about to state, the blood-vessels should not be considered as inert 
 tubes, in which the blood flows from the mere impulse which it has 
 received from the heart.* 
 
 LI V. Of the distribution, structure, and action of the arteries. 
 There is no part of the body to which the heart does not send blood by 
 the arteries, for it is impossible to make a puncture with the finest needle 
 into any of our organs without wounding several of these vessels, and 
 causing an effusion of blood. The aortic arterial system may be com- 
 pared to a tree, whose trunk, represented by the aorta, having its root 
 in the left ventricle of the heart, extends afar its branches, and throws 
 out on every side its numerous ramifications. The size of the arteries 
 decreases the farther they are from the trunk by which they are given 
 off. Their form, however, is not that of a cone; they are rather cylin- 
 ders arising from one another, and decreasing successively in size. As 
 the branches given off by a trunk, taken collectively, have a greater 
 diameter than that of the trunk itself, the capacity of the arterial sys- 
 tem increases with the distance from the heart; hence it follows, that as 
 the blood is continually flowing from a straiter to a wider channel, its 
 course must slacken. The direction of the arteries is often tortuous ; 
 and it is observed, that the arteries which are sent to hollow viscera, 
 as the stomach, the uterus, and the bladder, or other parts capable of 
 contracting, of stretching, and of changing their dimensions every 
 moment, as the lips, are much the most curved, no doubt that they 
 may, by unfolding, give way to the extension of the tissues into which 
 they are distributed. Lastly, the arteries arise from one another, and 
 form, with the branch or trunk from which they are given off, an angle 
 varying in size, but which is always obtuse, and more or less acute 
 towards the branch. 
 
 As the arteries recede from their origin, they communicate to- 
 gether; and these anastomoses form arches, two branches bending 
 towards each other and joining at their extremities, as we see in the 
 vessels of the mesentery ; sometimes two parallel branches meet at an 
 acute angle, and unite into one trunk ; thus the two vertebrals join to 
 form the basilary artery : some communicate by transverse branches, 
 which pass from the one to the other, as is seen within the skull. 
 
 In the anastomoses of the first kind, the columns of blood, flowing 
 
 * For some observations on the source of the heart's action, and on the experi- 
 ments and opinions of Le Gallois and Dr. W. Philip, made in order to ascertain it, 
 see the APPENDIX, Note R J. C.
 
 STRUCTURE OF THE ARTERIES. 171 
 
 in contrary directions along the two branches, meet at the point of 
 union, and mutually repel each other; their particle's mingle, and lose 
 much of their motion in that reciprocal shock. The blood then follows 
 a middle direction, and enters the branches which arise from the con- 
 vexity of these anastomotic arches. 
 
 When two branches unite to produce a new artery, of a greater 
 calibre than each taken separately, but not so large as both together, 
 the motion of the blood becomes accelerated, because it passes from 
 a more capacious into a straiter channel, and the forces which deter- 
 mined its progression are concentrated into one. Lastly, the transverse 
 anastomoses are well calculated to promote the passage of the blood 
 from the one branch into the other, and to prevent congestion in the 
 parts. 
 
 LV. Structure of arteries. The arteries are imbedded in a certain 
 quantity of cellular tissue, are almost universally accompanied by cor- 
 responding veins, by lymphatics and nerves, and their coats are thicker 
 in proportion as their calibre is smaller. The experiments of Clifton 
 Wintringham prove, that the parietes are stronger in the small than 
 in the large arteries; hence it is observed, that aneurisms are much less 
 frequent in the former. Their parietes have sufficient firmness not to 
 collapse when the tube of the artery is empty. They are formed of 
 three coats : the external or cellular admits of considerable extension, 
 and appears to be formed by the condensation of the laminae of the 
 cellular tissue which surrounds the artery, and unites it to the neigh- 
 bouring parts. The second coat is thicker and firmer, of a yellow 
 colour, and fibrous, and is by some considered as muscular* and con- 
 tractile, while other physiologists merely allow it to possess a consider- 
 able degree of elasticity. The longitudinal fibres, admitted by some 
 authors in the texture of this second coat, cannot be distinguished, 
 and their existence is not necessary to. account for the longitudinal 
 retraction of arteries. In fact, this retraction might depend on elas- 
 ticity ; it might likewise be occasioned by the contraction' of fibres not 
 absolutely circular nor longitudinal, but spiral, and imperfectly sur- 
 rounding- the vessel, and crossing each other in various directions. 
 This yellow coat, thicker in proportion in the smaller arterial twigs than 
 in the larger branches, and thicker in these than in the trunks, is dry, 
 hard, not capable of much extension, and is ruptured by an effort to 
 
 * If in man and the greater number of animals, the yellow fibres which form 
 this coat differ greatly from muscular fibres, they in the elephant resemble that 
 texture very completely, as I had an opportunity of observing, when I wit- 
 nessed the dissection of the elephant that died in the year 10, at the Museum of 
 Natural History. Let men of judgment decide whether the analogy is sufficient to. 
 warrant our admitting, in the arteries of the human body, the existence of muscular 
 fibres.
 
 172 STRUCTURE OF THE ARTERIES. 
 
 which the external coat yields by stretching. Lastly, a third, thin 
 and epidermoid coat lines the inside of these vessels, and seems less 
 calculated to give strength to the parietes of the arteries than to faci- 
 litate the flow of the blood, by presenting to it a smooth, even, and 
 slippery surface, continually moistened by a serous exudation from the 
 minute arteries, or vasa vasorum, which are distributed between these 
 coats.* 
 
 Besides these three coats, the great arteries receive a fourth from 
 the membranes lining the great cavities ; thus, the pericardium and the 
 pleura in the chest, and the peritonaeum in the abdomen, furnish to the 
 different parts of the aorta an adventitious coat which does not com- 
 pletely surround the vessel. 
 
 Of the three coats which form the parietes of the arteries, the 
 fibrous, though thicker than the other two, offers, however, the least 
 resistance. If you take the carotid artery, which for a considerable 
 space does not send off any branches, and forcibly inject into it a 
 fluid, the internal and middle coat will be torn before dilatation has 
 increased by one half the calibre of the vessel. The external coat 
 resists the cause of rupture by dilating, and forms a tumour ; and it is 
 only by applying a pretty considerable force that it can be ruptured. 
 The experiment is attended with the same success, if performed with 
 air or any other gas. In aneurism, the internal and fibrous coats of 
 the arteries, but more particularly the fibrous, are ruptured at an early 
 stage of the disease, which at that period increases suddenly, in a very 
 rapid manner ; and on opening the tumour, it is observed that the sac 
 is entirely formed by the dilated cellular coat. Take an artery of a 
 certain calibre, -for example, the carotid or humeral, apply a ligature 
 around it, and tighten it with some degree of force. Dissect and take 
 out the vessel, then cut the thread, and examine the place to which it 
 was applied; you will observe that the parietes of the artery are in that 
 part thinner, and formed merely by the cellular coat, which alone has 
 withstood the constriction. Take hold of the two ends of an insulated 
 arterial tube and stretch it, then examine its inner coat, and you will 
 find it torn and cracked in several places, and the parietes of the 
 artery evidently weakened. 
 
 LVI. This want of extensibility in the coats of arteries is the 
 principal cause of aneurism ; hence the popliteal artery is so liable to 
 that affection, from its situation behind the knee, whose extension is 
 limited merely by the resistance of the posterior tendons and liga- 
 ments : this artery is affected by the jar which takes place through all 
 the soft parts when the leg is violently extended ; and being less exten- 
 
 * See APPENDIX, Note R, for remarks on the Structure and Action of the 
 Arteries.
 
 PROPERTIES OF ARTERIAL VESSELS. " 173 
 
 sible than the other parts, its inner coat is ruptured, or at least weak- 
 ened, so as to occasion an aneurism, always rapid in its progress. Of 
 ten popliteal aneurisms which I have seen in different hospitals, eight 
 were ascribed to a violent extension of the ham. In looking over 
 the cases that have been recorded, it will be seen that a consider- 
 able number of aneurisms of the aorta have been occasioned by too 
 forcible and too sudden an extension of the trunk in raising a heavy 
 burden. 
 
 From the dryness and the frailty of the yellow or fibrous coat of 
 arteries, the application of ligatures to these vessels is attended with a 
 speedy laceration of their tissue ; a moderate degree of compression is 
 sufficient to rupture that coat, the external and internal remaining, at 
 the same time, uninjured, provided the constriction be not excessive. 
 Why is the arterial tissue, almost the only one on which ligatures 
 require to be applied, the least fitted of all the organic tissues to bear 
 them ? This inconvenience attending the ligature of arteries led 
 Pouteau to prefer tying them so as to include the surrounding soft 
 parts within the ligature, though this process is, in other respects, less 
 eligible. The objections will be obviated by employing flat ligatures, 
 which, by acting on a greater surface of the artery, are less likely to 
 divide the coats of the vessel which will become obliterated at the spot 
 to which the ligature is applied, the more rapidly as the patient is 
 younger and stronger. 
 
 I once saw, in, a man whose thigh was amputated on account of 
 caries of the knee-joint combined with a scorbutic affection, haemor- 
 rhage attend the fall of the ligatures, which did not come away till 
 nineteen days after the operation; as if the fibrous coat of these 
 arteries, partaking in the debility of the muscular organs, had not pre- 
 served a sufficient degree of contractile power to close the cavity of 
 the vessel. 
 
 LVII. Properties of arterial vessels. The contractile power of 
 the arteries is in their middle coat; it is greater as this coat is thicker 
 in proportion to the calibre of the artery. Hence, as Hunter observes 
 in his work on the blood and inflammation, the larger arteries are 
 endowed with elasticity merely, while, on the other hand, contractility 
 is very apparent in those of a smaller calibre, and is found complete in 
 the capillary vessels ; hence, in the trunks near the heart, the progres- 
 sion of the blood is effected chiefly by the impulse which it receives 
 from the heart; and, as Lazarus Riviere observed, the circulation of 
 the blood in the large vessels is more an hydraulic than a vital pheno- 
 menon. The action of the main arterial trunks near the heart has so 
 little influence on the motion of the blood sent into them by that 
 organ, that the aorta is frequently ossified without affecting the circu- 
 lation. The aorta is naturally bony in the sturgeon. J. L. Petit, in
 
 174 THE CIRCULATION IN ARTERIES. 
 
 the case of a bookseller whose leg he had taken off, found all the 
 arteries of a certain calibre in a state of ossification ; they were indu- 
 rated, and, of course, incapable of acting, in the slightest degree, on 
 the column of blood which flowed along them. All these facts seem 
 conclusive arguments in favour of those physiologists who explain, on 
 the principle of elasticity, the contraction of arteries. But however 
 correct this explanation may be with regard to the vessels near the 
 heart, it does not apply to the capillaries ; the influence of that organ 
 does not operate on these vessels. One may easily conceive, that the 
 column of blood which, by the impulse it has received in the first 
 instance, has been sent along the whole length of tubes whose sides 
 are ossified, inflexible, and consequently inert, on reaching the extre- 
 mity of these canals, is, in a manner, again taken up by the vital 
 power residing in the capillary vessels, and circulates from the influ- 
 ence of the action belonging to these vessels. Besides, elasticity, 
 however considerable, merely restores those tissues that have been 
 stretched to the condition in which they were before extension. Elas- 
 ticity is a kind of re-action, proportionate or relative to the action 
 which precedes it. Why do arteries in the living body contract to 
 such a degree that when empty their canal becomes obliterated, while 
 in the dead body, however perfect the depletion of the arterial system 
 may have been, the cavity of the arteries remains perfectly open? 
 Several physiologists, however, and those among the most modern, 
 consider elasticity as the principal cause of the progression of the 
 blood along the arteries. 
 
 As the distance from the centre increases, the circulation slackens, 
 from several causes, and the blood could not reach all the parts of the 
 body, if the arteries, whose vitality increases with their distance from 
 thfe heart, and as they become smaller, did not propel it to all the 
 organs. The causes which retard the circulation of the arterial blood 
 are, the increased dimensions of the space in which it is contained ; 
 the resistance from the curves of the vessels ; the friction which it 
 undergoes, and which increases, as, at a distance from the heart, the 
 canals along which it circulates increase in number ; and lastly, the 
 deviations the blood meets with in its course from the trunks into 
 the branches, which, coming off sometimes almost at right angles, divert 
 it from its original direction. 
 
 Many physiologists have called in question this progressive slack- 
 ening of the flow of arterial blood ; and several among them, who reject 
 entirely the application of the physical sciences to that of the animal 
 economy, have, nevertheless, supported their opinion by a fact taken 
 from hydraulics. To give any certainty to these calculations respecting 
 the impediments to the circulation of the blood in the arteries, it would, 
 they say, be necessary that the arteries should be empty at the instant
 
 THE CIRCULATION IN ARTERIES. 175 
 
 when they receive the jet of blood sent into them by the contraction of 
 the ventricles. This, however, is not the case ; the arteries are always 
 full, the blood flows along all of them with the same degree of velocity. 
 This system of vessels may be compared to a syringe, from which a 
 number of straight and tortuous tubes should arise ; each of these 
 would throw out the fluid with an equal degree of velocity, on applying 
 pressure to the piston. 
 
 In refuting this doctrine, I must take notice of the manifest contra- 
 diction of pretending to exclude absolutely all application of the 
 principles of mechanics to physiology, and the complete application of 
 these principles to the phenomena of the animal economy. This con- 
 tradiction, however, is not more surprising than that of authors who 
 exclaim against the abuse of modern nomenclatures, and who, never- 
 theless, eagerly embrace every opportunity of adding to it, by assigning 
 new names to such parts as may have escaped the attention of the new 
 nomenclators. What resemblance is there between a forcing-pump, 
 whose sides are unyielding, as well as those of the tubes which might 
 arise from it, and the aorta, which dilates every time the blood is sent 
 into it? And again, what resemblance is there between tubes which 
 decrease towards their open extremities, while the space contained in 
 the arterial tube constantly enlarges, from the innumerable divisions of 
 the vessels? Since it is admitted that the course of the blood is slower 
 in the capillary vessels, must not this resistance, opposed to the blood 
 which fills the series of vessels from the capillaries to the heart, be felt 
 more at a greater distance from that organ, &c. ? Without this pro- 
 gressive increase of resistance, as the arterial blood is at a greater dis- 
 tance from the heart, this fluid would flow along the arteries, as it does 
 along the veins, without any pulsations ; for this resistance, which 
 causes the lateral effort of dilatation effected by the blood on the 
 parietes of the arteries, is the principal cause of the pulse, which belongs 
 only to that set of vessels. A very remarkable difference is observable 
 between the blood which is sent to the toes and that which goes to the 
 mammae, as I have several times noticed in removing the carious bones 
 of the toes, or in extirpating cancerous breasts : the small arteries of 
 these parts are nearly of the same size, but the jet of blood is much 
 more rapid, and the blood is sent to a much greater distance, when one 
 of the mammary arteries is divided. 
 
 The re-action of the arteries on the blood which dilates them, de- 
 pends not only on the great elasticity of their parietes, but likewise on 
 the contractility of the muscular coat. Elasticity has a considerable 
 share in the action of the larger trunks, while contractility is almost 
 the sole agent in producing the action of the minute arteries. If a 
 finger is introduced into the artery of a living animal, its parietes 
 compress it in every direction ; if the blood is prevented from flowing
 
 176 THE CIRCULATION IN ARTEIUES. 
 
 in it, the canal becomes obliterated by the adhesion of its parietes, and 
 the vessel is converted into a ligamentous cord, such as that formed in 
 the adult by the remains of the umbilical arteries and veins. This 
 contractility, which, during life, is always in action, keeps the arteries, 
 distended by the blood that fills them, of a smaller calibre than 
 after death. In performing great operations, especially in the ampu- 
 tation of limbs, I have always found the arteries, whether filled with 
 blood or empty, much smaller than I should have expected from their 
 appearance in the dead body. 
 
 It happens, however, sometimes, that the quantity of blood sent to 
 an organ increases, in consequence of some cause of irritation ; the 
 calibre of the arteries of the part then becomes remarkably enlarged. 
 Thus, the arteries of the uterus, which are very small in its unimpreg- 
 nated state, acquire, towards the end of pregnancy, a calibre equal to 
 that of the radial artery ; the small arteries which are sent to the 
 mammae are not in the same condition, as I have had an opportunity 
 of ascertaining, in a woman who had been suckling a child for two 
 months before her death they retained their almost capillary minute- 
 ness ; which would seem to prove, that the lymphatics are alone con- 
 cerned in bringing to these glands the materials of their secretion. The 
 mammary arteries are evidently enlarged in open cancer of the breast ; 
 in cancer of the penis, the blood-vessels likewise become enlarged ; 
 hence, in removing the penis for that affection, it is absolutely neces- 
 sary to secure the arteries with ligatures, a precaution which need not 
 be attended to in a case of gangrene. Gangrene is attended with this 
 peculiarity, that the arteries of the mortified parts contract, so as to 
 become obliterated, when their calibre is inconsiderable. 
 
 As the arteries are the canals which convey to all our organs the 
 materials of growth and reparation, they are larger, in proportion, in 
 children, in whom nutrition is more active, and their calibre is always 
 proportionate to the natural or morbid development of organs : hence, 
 the descending aorta and the iliac arteries are larger in women than in 
 men ; hence the right subclavian artery, which conveys blood to the larger 
 and more powerful of the two upper extremities, because the more 
 employed, is larger than the left subclavian. But the effect should not 
 be mistaken for the cause, and it should not be imagined that the right 
 upper extremity owes its superiority to the greater calibre of its 
 artery. In the new-born child this vessel is not larger than the left 
 subclavian ; but the right arm being more frequently employed, the 
 distribution of the fluids takes place more favourably, nutrition is car- 
 ried on with more energy, it acquires more bulk and strength, and 
 therefore the right subclavian artery conveys blood to it by a wider 
 channel. If the left upper extremity were employed in the same 
 manner, and if the right were kept in a state of inaction, the left
 
 OF THE PULSE. 177 
 
 subclavian would, no doubt, exceed the right. I am warranted by two 
 facts in forming this conjecture. In dissecting the bodies of two men 
 that were left-handed, I observed in the left subclavian arteries the 
 same proportionate enlargement which is usually met with in the same 
 vessels on the right side. 
 
 LVIII. Of the pulse. As the arteries are always full during life, 
 and as the blood flows along them with less velocity the greater their 
 distance from the heart, the blood which the contractions of the left 
 ventricle send into the aorta, meeting the column of blood already in 
 that vessel, communicates to it the impulse which it has received ; 
 but, retarded in its direct progression by the resistance of that column, 
 it acts against the parietes of the vessels, and removes them to a 
 greater distance from their axis. This lateral action, which dilates the 
 arteries, depends, therefore, on the resistance of the parietes of these 
 cavities, always filled with blood, to that which the heart sends into 
 them. This dilatation, which is more considerable in the large arteries 
 than in the smaller ones, manifests itself by a beat, known under 
 the name of pulse. The experiments of Lamure would lead one to 
 believe, that another cause of this phenomenon is a slight displacement 
 of the arteries every time they dilate. These displacements are most 
 easily observed at their curvatures, and where the^ adhere to sur- 
 rounding parts by a loose and yielding cellular tissue. 
 
 The pulse is more frequent in women, in- children, in pejrsons of 
 small stature, during the influence of the passions, and under violent 
 bodily exercise, than in an adult man, of high stature, and of a calm 
 physical and moral nature. At an early period of life, the pulse beats 
 as often as a hundred and forty times in a minute. But as the child 
 gets older, the motion of the circulation slackens, and at two years old 
 the pulse beats only a hundred times in the same space of time. At 
 the age of puberty, the beats of the pulse are about eighty in a minute ; 
 in manhood, seventy-five ; and lastly, in old men of sixty the pulse is 
 not above sixty.* It is slower in the inhabitants of cold than in those 
 of warm climates. 
 
 Since the time of Galen, the pulse has furnished physicians with 
 one of their principal sources of diagnosis. The force, the regularity, 
 the equality of its pulsations, opposed to their weakness, inequality, 
 irregularity, and intermittence, afford the means of judging of the 
 nature and danger of a disease, of the power of nature in bringing 
 about a cure, of the organ that is most affected, of the time or period 
 of the complaint, &c. No one has been more successful than Bordeu 
 in the consideration of the pulse under these different points of view. 
 
 * The author has adduced the instance of an old man of eighty-seven years of 
 age, in good health and spirits, whose pulse is only twenty-nine in a minute. J. C.
 
 178 OF THE AOHTAL VALVES. 
 
 Its modifications indicative of the periods of diseases, establish, ac- 
 cording to that celebrated physician, as may be seen in his Recherches 
 sur le pouls par rapport aux crises, the pulse of crudity, of irritation, 
 and of concoction. Certain general characters indicate whether the 
 affection is situated above or below the diaphragm, hence the distinc- 
 tion of superior and inferior pulse. Lastly, peculiar characters denote 
 the lesion of peculiar organs ; which constitutes the nasal, guttural, 
 pectoral, stomachic, hepatic, intestinal, renal, uterine, &c. 
 
 Besides these sensible beats, which constitute the phenomenon of 
 the pulse in the arteries, there is an inward and obscure pulsatory 
 motion, by which all the parts of the body are agitated every time 
 that the ventricles of the heart contract. There is a kind of anta- 
 gonism between the heart and the other organs ; they yield to the 
 impulse which it gives to the blood, dilate on receiving this fluid, and 
 collapse when the effort of contraction is over. Every part vibrates, 
 trembles, and palpitates, within the body; the motions of the heart 
 shake the whole frame; and these quiverings, which may be observed 
 externally, are most manifest when the circulation is carried on with 
 rapidity and force. In some headachs, the internal carotid arteries 
 pulsate with such violence, that not only the ear is sensible to the 
 noise made by the column of blood striking against the curvature of 
 the osseous canal, but the head is evidently moved and raised, as it 
 were, at each pulsation. If you look at your hand or foot, when the 
 tipper or lower extremity is quiescent and pendulous, you will observe 
 in it a slight motion, corresponding to the beats of the heart. This 
 motion increases, and even makes the hand shake, when, from the 
 influence of the passions, or from violent exercise, the circulation is 
 accelerated; in every violent emotion, we feel within ourselves the 
 effort by which the blood, at each beat of the pulse, penetrates into 
 our organs, and fills every tissue. And it is in a great measure from 
 this inward tact that we are conscious of existence ; a consciousness 
 the more lively and distinct, as the effect of which we are speaking is 
 more marked. It is likewise from observing this phenomenon, that 
 several physiologists have been led to conceive the idea of a double 
 motion, which dilates or condenses, which contracts or expands, al- 
 ternately, all organs endowed with life : they have observed, that 
 dilatation prevails in youth, in inflammation and erection, con- 
 ditions of which all parts are capable, according to their difference of 
 structure. 
 
 LIX. Uses of the aortal valves, fyc. At the moment when the left 
 ventricle contracts, to send the blood into the aorta, the sigmoid valves 
 of that artery rise, and apply themselves to its parietes, without, 
 however, closing the orifices of the coronary arteries, which lie above 
 the loose edges of the talves ; so that the blood is received into these
 
 OF THE CAPILLARY VESSELS. 179 
 
 vessels at the same time as into the others. When the contrac- 
 tion of the ventricle is over, the aorta acts on the blood which it con- 
 tains, and would send it back into the ventricle, if the valves, by sud- 
 denly descending, did not present an insuperable obstacle to the return 
 of blood, and did not yield a point of resistance to the action of the 
 whole arterial system; only the small quantity of blood below the 
 valves, at the moment of their descending, flows back towards the heart, 
 and returns into the ventricle. 
 
 Though the rate at which the blood flows along the aorta has been 
 estimated at only about eight inches in a second, a pulsation is felt in 
 all the arteries of a certain calibre, at the instant the ventricles are 
 contracting. The reason why the pulsations of the heart appear to take 
 place at the same time as those of the arteries is, that the columns of 
 blood in these vessels receive an impulse from that which is issuing 
 from the ventricles, and this concussion is felt in an instant of time, 
 too short to be measured, such as that which is felt by the hand 
 applied to the end of a piece of timber, struck at the other end with a 
 hammer. The blood that fills the main trunk supplies to each of the 
 branches which arise from it columns proportionate to their calibre. 
 This division of the principal column is effected by a kind of projec- 
 tion at the mouth of each artery. These internal projections detach 
 from the main stream the lesser ones, which flow the more readily 
 into the branches, according as these arise from the trunk at a more 
 acute angle, as the projection is more prominent, and the deviation of 
 the fluid less considerable. If the branches are given off at an almost 
 right angle, the orifices of the arteries scarcely project at all, and 
 nothing but the effort of lateral pressure determines the flow of the 
 blood into them. 
 
 The flow of the blood into the arteries which are distributed to muscles, 
 is not interrupted when these muscles contract ; for, whenever arteries of 
 a certain calibre penetrate into muscles, they are surrounded by a 
 tendinous ring, which, during the contraction of the muscle, becomes 
 enlarged, from the extension in every direction effected by the fibres 
 which are attached to it around its circumference. The existence 
 of this truly admirable conformation may be readily ascertained by 
 observing the aorta in its passage through the crura of the diaphragm ; 
 the perforating arteries of the thigh, where they enter at the back part 
 of the limb into the adductor muscles ; and the popliteal, as it passes 
 through the upper extremity of the soleus muscle. 
 
 LX. Of the capillary vessels. The arteries, after dividing into 
 branches, these branches into lesser ones, and these into progressively 
 smaller ramifications, terminate in the tissue of our organs, by becoming 
 continuous with the veins. The venous system arises, therefore, from 
 the arterial system, the origins of the veins being merely the more
 
 180 OF THE CAPILLARY CIRCULATION. 
 
 minute extremities of the arteries, which, becoming capillary from the 
 great number of divisions* they have undergone, bend in an opposite 
 direction, and become altered in their structure. 
 
 These minute capillary arteries Yorm, with the minute veins with 
 which they are continuous, and with the lymphatics, wonderful meshes 
 in the tissue of our organs. 
 
 Several physiologists consider the capillary blood-vessels as an 
 intermediate system between the arteries and veins, in which the blood, 
 entirely out of the influence of the action of the heart, flows slowly, 
 with an oscillatory and sometimes retrograde motion, is no longer red, 
 because its globules are strained, as it were, and, in a manner, lost in 
 a colourless serum, which serves them as a vehicle. 
 
 It is, in fact, necessary that bodies should be of a certain bulk to 
 reflect the rays of light at an angle sufficiently obtuse that the eye 
 may discover their colour. We know that grains of sand reduced to 
 a very fine dust appear colourless when examined separately, and are 
 seen to possess colour only when in a state of aggregation: further, very 
 thin laminae of a horny substance appear transparent, though the part 
 from which they have been detached be of a red or blue colour. But 
 if several of these transparent laminae be laid on one another, the red 
 colour becomes darker, in proportion as a greater number are brought 
 together. 
 
 Let irritation, from whatever cause, determine the blood to flow 
 into the serous capillary vessels in greater quantity, and with more 
 force, these vessels will become apparent, the organs in whose structure 
 they circulate will acquire a red colour, more or less deep ; thus, the 
 conjunctiva, the pleura, the peritonaeum, the cartilages, the ligaments, 
 &c. which naturally are whitish or transparent, become red when 
 affected with inflammation, either from the increased impetus of the 
 circulation, which forces and accumulates into the capillary vessels 
 a greater number of red globules, or that the sensibility of these 
 small vessels is impaired by inflammation, so that they admit globules 
 which they formerly rejected. 
 
 Some capillary vessels transmit blood at all times, and uniformly 
 exhibit a red colour : this is the case with the capillary vessels of the 
 spleen, of the corpora cavernosa of the penis, of the bulb and corpus 
 spongiosum of the urethea ; the same applies to the capillaries of the 
 muscles of the mucous membranes : there are, however, very few of 
 those organs in which the whole portion of the capillary tube, be- 
 
 * The arterial divisions which may be discerned by the aid of anatomy do not 
 exceed eighteen or twenty; nevertheless, they divide still further, when they are 
 become so minute as not to be discernible without the help of the most powerful 
 microscope.
 
 OB' THE CAPILLARY CIRCULATION. 181 
 
 tween the termination of the artery and the origin of the vein, is filled 
 with red blood. There is almost always a division in the tortuous line 
 described by the capillary, and within this space the blood cannot be 
 . detected of its usual colour.* 
 
 The number of the capillary vessels, as well as that of the arteries, to 
 which the former are as auxiliaries, is much more considerable in the 
 secretory organs than in those in which life carries on only the process 
 of nutrition, It is on that account that the bones, the tendons, 
 the ligaments, the cartilages, contain so much smaller a quantity of 
 blood than the mucous and serous membranes and the skin. The 
 capillary vessels are, however, very numerous in the muscles, which 
 owe that colour to the great quantity of blood they contain ; but, as we 
 shall point out when we come to speak of motion, this fluid appears 
 to form an essential element in muscular contraction ; it is, therefore, 
 not to be wondered that these organs should have a greater number of 
 capillary vessels sent to them, since these vessels do not. supply them 
 merely with molecules to carry on nutrition, and to repair the waste 
 of the part, but impart to them the principle of their frequent con- 
 traction : the quantity of them is so considerable in all these parts, 
 employed in the twofold offices of nutrition and secretion, that Ruysch 
 penetrated with his injections the whole thickness of their substance, 
 to such a degree, that the organs which he had prepared were only a 
 wonderful and inextricable net-work of capillary vessels, extremely 
 minute. On these anatomical preparations, made with an art hitherto 
 unrivalled, Ruysch grounded his hypothesis relative to the intimate 
 structure of the body, in which he imagined all was capillary tubes, an 
 hypothesis which has obtained the most favourable reception, and has 
 reigned during more than a century in the schools. It is enough to 
 reflect a moment on their uses, to conceive that the number of them 
 must be really prodigious. As long as the blood is enclosed within the 
 arteries, and flows under the control of the heart, it fulfils no purpose, 
 either of nutrition or secretion. To make it subservient to these great 
 functions, it must be diffused through the very tissue of the organs, by 
 means of the capillary divisions ; these little vessels exist, then, in every 
 part where any organised molecules are found united, since the particle 
 formed by their assemblage must, at least, find in the juices which 
 they bring to it the materials of its reparation. Entering, in greater 
 or less proportion, into the organisation of all the tissues, the capillaries 
 
 * There is every reason for concluding that capillary vessels exist, which, run- 
 ning between some of the terminations of the arteries and the commencement of 
 veins, admit only the serous portion of the blood when performing their healthy 
 functions ; but which may, in a state of inflammation, admit also the red particles 
 of this fluid to flow along them J. C.
 
 182 OF CAPILLARY POROSITIES. 
 
 receive certain modifications from the organs of which they are an 
 integral part ; modifications which enable them to deposit the serous 
 part of the blood on the surface of the serous membranes, admit the 
 transudation of the fat into the ceHs of the cellular tissue, furnish the 
 urine to the kidneys, and the liver with the materials of the bile : in a 
 word, suffer to escape through the porosities with which their parietes 
 are pierced, the principles which the blood has to furnish to every 
 organ. 
 
 It is by these lateral porosities, and not by extremities open on all 
 the surfaces, and in all the points of the organs, that the capillaries 
 transpire, in some sort, the elements of nutrition and of the various 
 secretions.* Mascagni was aware that Nature, skilful in deducing 
 many effects from few causes, has not deviated, in the construction of 
 the system of circulation, from the invariable laws of her ordinary 
 simplicity; but the lateral pores of the capillaries, which are sufficient 
 for the explanation of all the phenomena ascribed to the exhaling 
 mouths of the arteries, and to the pretended continuity of these 
 vessels with the' excretory ducts of the organs, &c. are not openings 
 like the pores common to all matter ; each of them may be considered 
 as an orifice, sensible, and especially contractile, of differing size, 
 according to the state of the strength or of the vital powers. The 
 size, then, of these capillary pores is subject to frequent variations; 
 and this is the explanation given of the formation of scorbutic ecchy- 
 moses, of petechise, and of passive or relaxed haemorrhages. In all 
 these affections, contractility being really diminished, the pores of the 
 capillaries enlarge, and suffer the red blood to transude through 
 their relaxed mouths. This phenomenon takes place, not only under 
 the skin, and on the various mucous surfaces ; it is observed also in the 
 very tissue of the organs. It is thus that I have often seen, on opening 
 the bodies of those that had died of scurvy in its last stage, the muscles 
 of the leg filled with blood. This sort of interior haemorrhage con- 
 verts the muscles into a kind of pulp, and the extravasated blood itself 
 undergoes a beginning of decomposition. The bones themselves are 
 liable to these scorbutic, bloody infiltrations. I had an opportunity 
 of ascertaining this in the Hospital of St. Louis, at the same time that 
 I learnt the difficulty of procuring a durable skeleton from such bodies. 
 The greatest number die in a very advanced stage of the disease, and 
 the bones dissolve in maceration, or rot in a very little time. 
 
 The capillary vessels, whether the blood flow through them red or 
 colourless, are not a system of vessels distinct from that of the arteries 
 and from that of the veins ; they belong essentially to these two 
 
 * See APPENDIX, Note S, for observations on the Functions of the Capillary 
 System, and on Nutrition.
 
 THE ANASTOMOSES OF CAPILLARIES. 183 
 
 orders of vessels. Those which, ramifying in the tissue of the skin 
 or of the serous membranes, suffer the serum of the blood to transude, 
 are not more entitled to the name of exhalant system, which some 
 authors have given them. To consider as distinct and insulated 
 systems, separate parts of a system of organs, is to encumber science 
 with a crowd of divisions, as false as they are useless. 
 
 LXI. The sanguineous capillaries anastomose, and form, like the 
 lymphatic capillaries, a net-work that envelopes all the organs. Their 
 frequent communications do not allow obstructions to take place, and 
 to produce inflammation, as Boerhaave thought, and as was long taught 
 on the authority of that celebrated physician. Haller, Spallanzani, 
 all the microscopic observers, have perceived threads of blood flowing 
 in the capillaries, offering themselves at the various inosculations of 
 these vessels, and have seen them flow back, when they were not 
 admitted, to seek other easier entrances. 
 
 I will not heap up in this place superfluous arguments against the 
 theory of the Leyden professor, rejected at its birth by the physi- 
 cians of Moutpelier, absolutely refuted, and now universally given up. 
 Irritation alone keeps the blood in the inflamed part ; for when 
 death, which puts an end to all irritations, and relaxes all spasms, 
 (mors spasmos solvit, Hipp.) when, I say, death comes on, all slight 
 inflammations are dissipated ; and whenever they have not been suffi- 
 ciently intense to induce transudation of the blood through the parietes 
 of the capillaries into the areolae of the organic tissues, the blood flows 
 back into the large vessels, and there is no trace of it left. It is thus 
 that erysipelas of the skin disappears, that the pleura preserves its 
 transparency, in individuals affected before death with sharp pains in 
 the side. If to this we add our ignorance of the real organisation of 
 the nervous system, of the conditions absolutely required of the brain, 
 and nerves for the maintenance of life, we shall cease to be surprised 
 that the opening of bodies has taught us no more on the real seat of 
 disease; and we shall confess with Morgagni, who, however, employed 
 with great success this means of improving the art of healing, that 
 there are numberless diseases, of which, after death, no trace is left, 
 and for the fatal termination of which we are unable to account. 
 
 Contractility and sensibility exist in a much higher degree in 
 the capillary and serous vessels than in the veins and arteries. Life 
 must needs be more active in the former ; for, the motion given to the 
 blood by the contractions of the heart being exhausted, this fluid, no 
 longer in the sphere of action of that organ, can circulate but from the 
 influence of the action of the vessels themselves. 
 
 The termination of the arteries into veins is the only well-ascer- 
 tained termination of those vessels; it may be seen, by the help of the 
 microscope, in cold-blooded animals, in frogs and salamanders. In
 
 184 OF THE VEINS. 
 
 some fish we may, even with the naked eye, observe frequent and con- 
 siderable inosculations between the arteries and veins. In man, 
 however, and in other warm-blooded animals, these communications 
 take place only at the extremities of ( the two systems of vessels. In 
 this case the arteries terminate sometimes in capillary vessels, carrying 
 serous fluid, such as the vessels of the sclerotic coat ; these vessels 
 become small veins, whose calibre gradually increases, until they 
 admit red globules in sufficient number to reflect that colour. At 
 other times the artery and vein are continuous, without the inter- 
 vention of that extremely minute subdivision : the red blood then 
 passes readily and immediately from the artery into the vein. 
 
 It will be shewn, in speaking of secretion, that the continuation of 
 the arteries into the excretory ducts of the conglomerate glands, and 
 their termination in exhaling orifices, cannot be admitted ; and that 
 the presence of small pores in the sides of the minute arteries 
 and veins would afford an explanation of the phenomena on which 
 the belief of this termination of the arteries rests. There exists no 
 parenchyma, no spongy tissue, between the extremities of the arteries 
 and the origin of the veins, with, perhaps, the exception of the 
 substance of the cavernous bodies of the penis and of the clitoris, 
 of the bulb and spongy part of the urethra,* the retiform plexus 
 which surrounds the orifice of the vagina, and perhaps also the tissue 
 of the spleen ; though the experiments of anatomists (Mascagni and 
 Lobstein) seem to prove that in these organs the arteries and veins are 
 immediately continuous.f 
 
 LXII. Of the distribution and action of the veins.l These vessels, 
 whose function it is to carry back to the heart the blood which the 
 arteries have sent to all the organs, are much more numerous than 
 the arteries themselves. It is observed, in fact, that arteries of a 
 middle size, as those of the leg and fore arm, have each two corre- 
 sponding veins, whose calibre at least equals theirs, and that there is, 
 besides, a set of superficial veins, lying between the skin which covers 
 the limbs, and the aponenroses which envelop the muscles : these have 
 no corresponding arteries. The space which the venous blood occu- 
 pies is, therefore, much greater than that taken up by the blood in the 
 arteries. Hence, also, it is estimated, that of twenty-eight or thirty 
 pounds of this fluid, making about a fifth part of the whole weight 
 of the body in an adult man, nine parts are present in the veins, and 
 only four in the arteries. In this calculation, one should consider 
 as arterial the blood contained in the pulmonary veins and in the 
 left cavities of the heart, while that which fills the cavities in the 
 
 * See the chapter on the Organs of Generation. 
 
 f See APPENDIX, Note T. See APPENDIX, Note N.
 
 0F THE VEINS. 185 
 
 right side of the heart and the pulmonary artery, is truly venous, and 
 has every character of such blood. 
 
 Although the veins generally accompany the arteries, and are 
 united to them by a common sheath of cellular membrane, this dispo- 
 sition of parts is not without exceptions. The veins which bring back 
 the blood from the liver, do not, in any respect, follow the course of the 
 branches of the hepatic artery ; the sinuses of the brain are very dif- 
 ferent in their arrangement from the cerebral arteries ; the veins of the 
 bones, which are particularly numerous, and of a much greater calibre 
 than the arteries of the same parts, from the slow circulation of the 
 blood along them, do not generally follow the direction of the arteries, 
 and arise singly from the substance of the bone, with the exception of 
 those in the middle canal, and which pass through the nutritious 
 foramen of the bone. The veins are not only more numerous than the 
 arteries, but they are likewise more capacious, and dilate more readily: 
 this structure was necessary, on account of the slowness with which the 
 blood circulates, and of the readiness with which it stagnates, when 
 the slightest obstacle impedes its circulation.* The force which car- 
 ries on the circulation of the blood along the arteries is so great, that 
 Nature seems not to have availed herself of the mechanical advantages 
 which might have facilitated its flow. On the other hand, the power 
 which determines the progression of the venous blood is so feeble, that 
 she has sedulously removed every obstacle which might have impeded its 
 course. And as the relation of the minute to the larger branches, and of 
 these to the trunk, is the same as in the arteries, two branches uniting 
 to form a vein of greater calibre than each separate vessel, but smaller 
 than the two taken together, the blood flows along a space which 
 becomes narrower the nearer it approaches the heart ; the rapidity of 
 its course must, therefore, be progressively increased. 
 
 The veins are almost straight in their course ; at least, they are 
 much less tortuous than the arteries. The force which makes the 
 blood flow along them is consequently not taken up in straightening 
 these curves ; the anastomoses are likewise more frequent ; and, as the 
 flow of the blood might have been intercepted in the deep-seated veins 
 of the limbs, when the muscles, among which these vessels lie during 
 contraction, compress them by their enlargement and induration, they 
 
 * The arteries contain, at all times, nearly the same quantity of blood. The 
 veins are always the seat of plethora, because the blood stagnates in them more 
 readily ; and this condition brings on inflammatory fever (consisting merely in an 
 increased action of the vascular system, as is expressed by the term angeiotenique^ 
 applied to it by Professor Pinel), only when the venous congestion becoming exces. 
 sive, the blood passes with difficulty from the arteries into the veins. The heart 
 and the arteries then struggle, with considerable effort, to rid themselves of the fluid 
 which oppresses them, &c.
 
 186 OF THE VENOUS CIRCULATION'. 
 
 communicate freely with the superficial veins, towards which the blood 
 is carried, and flows the more readily, as they are not liable to be com- 
 pressed. It is observed, and is to be accounted for on the same prin- 
 ciple, that the superficial veins are very large and distinct among- the 
 lower orders, who are employed in laborious occupations, requiring 
 an almost continual exertion of their limbs. Lastly, the internal part 
 of the veins, like that of the lymphatics, is furnished with valvular 
 folds, formed by the duplicature of their epidermoid coat. These valves, 
 which are seldom single, and almost always in pairs, are not found in 
 the minute veins, nor in the great trunks, nor in the veins which bring 
 back the blood from the viscera in the great cavities. 
 
 These valves in falling close completely the canal of the vessel, 
 destroy the continuity of the column of blood returning to the heart, 
 divide it into smaller columns, as numerous as the intervals between 
 the valves, and the height of which is determined by the distance 
 between these folds. So that the power which carries onward the 
 venous blood, and which would be incapable of propelling the whole 
 mass, acts advantageously on each of the small portions into which it 
 is divided. 
 
 LXIII. It has been thought that the principal cause which makes 
 the blood flow into the veins, is the combined action of the heart 
 and arteries ; but the impulse from those organs is lost in the system 
 of capillary vessels, and does not extend to the veins. The specific 
 action of their own parietes, aided by auxiliary means, such as the 
 motion of the neighbouring arteries, is sufficient to carry the blood on 
 to the heart.* 
 
 These parietes, which are much thinner than those of the arteries, 
 are contained, like theirs, in a sheath common to all the vessels. 
 Three coats, likewise, enter into their structure ; the middle, or fibrous 
 coat, is not very distinct, and consists merely of a few longitudinal 
 reddish fibres, which can be distinguished only in the larger veins 
 near the heart. In some of the larger quadrupeds, as in the ox, 
 these fibres form distinct fasciculi, and their muscularity is much more 
 manifest. 
 
 The internal coat, which is more extensible than that of the arte- 
 ries, and equally thin, adheres more closely to the other coats. The 
 cellular coat, which connects it to the middle one, is less abundant ; 
 hence phosphate of lime is seldom deposited into it, as happens to the 
 arteries, which frequently become ossified as we advance in years. 
 This internal coat is merely a continuation of that which lines the cavi- 
 
 * It would perhaps be more just to assign the cause of the flow of blood in the 
 veins to the vis a tergo, assisted by the action of their own parietes, and by the 
 active dilatation of the heart. See APPENDIX, Note T J. C.
 
 OF THE VENOUS CIRCULATION. 187 
 
 ties of the heart ; and as the origin of the inner coat of the arteries is 
 the same, there exists a non-interrupted continuity in the membrane 
 which lines all the canals of the circulation. The inner coat forms 
 the only essential part of the venous system ; it alone constitutes 
 the veins within the bones, the sinuses of the dura mater, the hepatic 
 veins, in a word, all the veins which are so firmly attached externally 
 to the neighbouring parts, that the blood flows along them as along 
 inert tubes, their parietes being almost completely incapable of 
 contracting. 
 
 The veins in their passage through muscles, are, like the arteries, 
 guarded by aponeurotic rings, than which none is more remarkable 
 than that belonging to the aperture in the diaphragm, which trans- 
 mits the ascending cava from the abdomen into the thorax. This 
 vessel is, therefore, not compressed by the contraction of that muscle 
 in inspiration. 
 
 LXIV. As the inferior cava passes through the lower edge of the 
 liver, whether along a deep fissure, or in a real canal in the parenchy- 
 matous substance of that viscus, the course of the blood must be 
 impeded, when, from congestion of the parenchyma, the vessel is, in 
 some sort, strangulated. 
 
 Obstruction of the liver, which is of such frequent occurrence, 
 would have been attended with fatal consequences, by preventing the 
 return of the blood from the inferior parts, along the ascending cava, 
 if this great venous trunk did not keep up, by means of the vena 
 azygos, an open and free communication with the descending or supe- 
 rior cava. The use of this anastomosis of the two great veins, is 
 evidently to facilitate the passage of the blood from the one of these 
 vessels into the other, when either, especially the lower, does not 
 readily evacuate its contents into the right auricle. On this account, 
 the vena azygos is capable of considerable dilatation, and is entirely 
 without valves. In the body of a man opened this day in my pre- 
 sence, and whose liver was twice as large as in health, I observed that 
 the vena azygos, which was distended with blood, was of the size of the 
 little finger : the terminations downwards of this vessel, in the right renal 
 vein, and above in the superior cava, were most distinct; and by com- 
 pressing it from above downward, or from below upward, the blood 
 flowed into the one or other of these vessels. 
 
 As the causes which determine the circulation of the venous blood 
 communicate to it an impulse which is far from rapid, and as this fluid 
 meets with only trifling obstacles, and such as are easily overcome, the 
 pressure against the parietes of the veins is very inconsiderable ; and 
 these vessels do not pulsate as the arteries. There is observed, how- 
 ever, near the heart an undulatory motion, which the blood communi- 
 cates to the parietes of the vessels. These kinds of alternate pulsations
 
 OF THE VENOUS CIRCULATION. 
 
 depend on the rapidity with which the blood, whose course is progres- 
 sively accelerated, flows towards the heart, and on the reflux of the 
 blood du'ring the contraction of the right auricle. The contraction of 
 this cavity forces back the blood into the veins which open into it ; this 
 retrograde course is manifest in the superior cava, and is the more 
 readily occasioned, as the orifice of this vein is not furnished with any 
 valve that might prevent it. It does not, however, extend very far 
 towards the brain, the blood having to ascend against its own weight, 
 and the jugulars admitting of considerable dilatation. This regurgi- 
 tation is still more marked in the inferior cava, the orifice of which is 
 but imperfectly closed by the valve of Eustachius; it is felt in the abdo- 
 minal veins, and extends even to the external iliacs, according to the 
 testimony of Haller. 
 
 LXV. The orifice of the great coronary vein being exactly covered 
 over by its valve, the blood does not return into the tissue of the heart, 
 which, being a contractile organ, would have had its irritability impaired 
 by the presence of venous blood. It is of consequence to observe, 
 that this reflux never extends to the veins which bring back the blood 
 from the muscles, and that it is never felt in the veins of the limbs 
 which are furnished internally with valvular folds. The case is very 
 different between our organs of motion and these secretory glands : 
 towards these latter the blood is required to be sent back, so as to 
 be the longer exposed to their action ; whereas venous blood dimi- 
 nishes and even destroys muscular irritability, and is truly oppressive 
 to the organs of motion, as may be ascertained by injecting some* in 
 the arteries of a living animal, or else by tying the veins, so as to pre- 
 vent its return, or by observing what happens when the course of the 
 blood is interrupted, either by applying firm ligatures round the limbs, 
 or by wearing confined clothes. 
 
 I am satisfied, that it was from observing the oscillatory undulations 
 of the venous blood in the great vessels, that the ancients were led to 
 the opinions they entertained on the course of the blood, which they 
 compared to the Euripus, whose waves were represented by the poets 
 as uncertain in their course, and in currents running in contrary 
 directions. 
 
 The internal veins in which this reflux is observed shew this motion 
 of the blood most distinctly of any ; their sides, which are thin and 
 semi-transparent, not being, as in other parts, surrounded by an adi- 
 pose cellular tissue. To give a complete notion of the doctrine of the 
 ancients on the' subject of the circulation, it will merely be necessary 
 to add to the above idea the opinion which they entertained, that the 
 chyle taken up by the meseraic veins was carried to the liver, in which 
 its sanguification was effected ; and lastly, that the arteries were filled 
 with vital spirit, and contained only a few drops of blood, which passed
 
 OF THE GENERAL CIRCULATION. 189 
 
 through small holes, that Galen says, perforate the septum of the 
 ventricles. 
 
 The blood, however, continually urged on by the columns which 
 follow each other in succession, by the action of the veins whose 
 parietes become gradually stronger, and by the compression which 
 these vessels experience from the viscera during the motions of respira- 
 tion, reaches the heart, and enters the auricles with the greater facility, 
 as the orifices of the cavse not being directly opposed to each other, 
 the columns of blood which they convey do not meet, and do not 
 oppose each other. 
 
 LXVI. Of the general or systemic circulation. The blood con- 
 tinually carried to all parts of the body by the arteries, returns, there- 
 fore, to the heart, by a motion which can never be interrupted without 
 considerable danger of life. We know that the circulation is thus 
 effected, from the direction of the valves of the heart, of the arteries 
 and veins, by what happens when these vessels are opened, compressed, 
 or tied, or when a fluid is injected into them. When an artery is 
 wounded, the blood comes from the part of the vessel nearest the heart; 
 it comes, on the contrary, from towards the extremities, if it is a vein 
 that has been opened. By compressing or tying an artery, the course 
 of the blood is suspended below the ligature, and the vessel swells 
 above. The veins, on the contrary, when tied or compressed, dilate 
 below. Lastly, when an acid fluid is injected into a vein, the blood is 
 seen to coagulate in the direction of the heart. By the help of the 
 microscope, we may see in the semi-transparent vessels of frogs and other 
 cold-blooded animals, the blood flowing from the heart into the arte- 
 ries, and from these into the veins, which return it to the heart. It 
 was on the strength of these convincing proofs, that William Harvey 
 established, towards the middle of the sixteenth century, the theory of 
 the circulation of the blood. Its mechanism had been rather guessed 
 at, than understood, by several authors : Servetus and Cesalpine appear 
 to have been acquainted with it ; but no one has more clearly explained 
 it than the English physiologist, who is justly considered the author of 
 that immortal discovery. 
 
 LXVII. The theory of Harvey, such as it is laid down in his 
 work, entitled, De sanguinis circuitu exercitationes anatomicce, does 
 not appear to me entirely admissible. He considers the heart as the 
 only agent which sets the blood in motion, and does not take into 
 account the action of the veins and arteries, which he considers as com- 
 pletely inert tubes ; while every thing tends to prove that the arteries 
 and veins assist the motion of the blood,* by an action peculiar to 
 
 " See APPENDIX, Notes A, B, S, T.
 
 190 OF THE PULMOXARY CIRCULATION. 
 
 themselves. He admits, that the blood flows in every part of the 
 circulatory system with an uniform degree of speed ; an opinion so 
 manifestly contradicted by reasoning and experience, which prove that 
 the velocity of its course diminishes, the greater its distance from the 
 heart, from the influence of a great number of circumstances, which 
 it would be useless to repeat (LVII). This doctrine has yet, how- 
 ever, several abettors; and among the moderns, Spallanzani has 
 endeavoured to support it, by a number of experiments so contradic- 
 tory, that one is surprised that so judicious a physiologist should have 
 collected them to establish a theory completely refuted by several of 
 them. Nothing, for example, contradicts it more fully, than the con- 
 tinuation of the flow of the blood, in the vessels of frogs and sala- 
 manders, after the heart of these reptiles has been torn out: there are, 
 besides, animals which, not possessed of that central organ, have, 
 nevertheless, vessels along which the blood flows, and which contract 
 and dilate by alternate motions. 
 
 If the mere force of the heart propelled the blood to every part, 
 the course of this fluid ought, at intervals, to be suspended ; its circu- 
 lation, at least, ought to be slackened when the ventricles cease to 
 contract ; but as the contraction of the arteries corresponds to the 
 relaxation of the ventricles, these two powers, whose action alternates, 
 are continually employed in propelling the blood along its innumerable 
 channels. 
 
 Besides the general circulation, of which the laws and phenomena 
 have just been mentioned, each part may be said to have its peculiar 
 mode of circulation, more or less rapid, according to the arrangement 
 and structure of its vessels. Each of these individual circulations forms 
 a part of the machinery included in the great circle of the general cir- 
 culation, and in which the course of the blood takes place in a different 
 manner, may be accelerated or retarded, without affecting the general 
 circulation. Thus, the circulation in the brain is modified from that 
 of the lungs ; and this latter, from the circulation of the abdominal 
 viscera, the venous blood of which, destined to furnish the materials 
 of the bile, flows much more slowly than that of other parts. 
 
 These modifications, affecting the velocity of the circulatory motion 
 of the blood, account for the difference of its qualities in different 
 organs : all these differences form a part of the plan of nature, and it 
 is not difficult to understand their utility. 
 
 LXVIII. Of the pulmonary or lesser circulation. In what has 
 been said of the circulation, no separate mention has been made of the 
 course of the blood through the lungs, called by authors the lesser or 
 pulmonary circulation. The vascular system of the lungs, with the 
 addition even of the cavities of the heart which belong to it, does not
 
 OF THE PULMOXAIIY CIRCULATION. 191 
 
 represent a complete circle ; it is only a segment, or rather an arch, of 
 the great circle of general circulation. 
 
 The blood, in going along that great circle, meets with the organs, 
 situated like so many points of intersection in the course of the vessel, 
 which form that circle. 
 
 To render still more simple the idea which is to be entertained on 
 the subject, one may reduce these intersections to two principal ones ; 
 the one corresponding to the lungs, the other to the rest of the body ; 
 the veins, the right cavities of the heart, and the pulmonary artery 
 with its divisions, forming one half of the circle ; the pulmonary veins, 
 the left cavities of the heart, the aorta with all its branches, represent- 
 ing the other half. The capillary vessels of the lungs form one of the 
 points of intersection, and the capillaries of all the other organs 
 represent the other point of intersection, by uniting together the arte- 
 ries and veins of the whole body, in the same manner as those of the 
 lungs establish a communication between the veins and arteries of these 
 organs. 
 
 This division of the system of circulation into two parts, in one of 
 which there circulates a dark or venous blood, while the other contains 
 red or arterial blood, is at once more simple and more accurate. As 
 was already stated, in the history of the circulation, its organs are, 
 in an especial manner, destined to the mechanical act of conveying 
 the fluids : the changes, the alterations which the blood undergoes in 
 passing through the organs, are effected only at the moment when, in 
 penetrating into their tissue, it passes into the capillary vessels which 
 are distributed into them. The columns of blood are then sufficiently 
 minute to be operated upon by the vital action ; till then, the columns 
 of blood are too large, and resist, by their bulk, if one may so speak, 
 any decomposition. It is, therefore, in the capillary vessels that the 
 blood undergoes its essential changes, and from them it deposits its 
 nutritious elements ; and to understand how the nutritious lymph, 
 which is carried by the thoracic duct into the left subclavian vein, expe- 
 riences, in its course along the sanguiferous system, the changes which 
 are to assimilate it to our own substance, it is necessary to follow it, 
 along the venous blood with which it unites, into the heart, through 
 the right half of which it passes in its way to the lungs, there to com- 
 bine with the atmospherical air, from which we are perpetually deriv- 
 ing another aliment indispensable to life ; then, to examine how, when 
 modified and conveyed with the red blood from the lungs to the whole 
 body, it serves to the secretions, and supplies nourishment to the dif- 
 ferent structures of the frame. 
 
 In considering, in this manner, the circulation of the blood, with a 
 reference to the changes which it undergoes in the organs through 
 which it passes in describing that circle, we shall find that this fluid,
 
 192 OF RESPIRATION. 
 
 already combined with the lymph and chyle, parts, in the lungs, with 
 some of its principles, at the same time that it becomes impregnated 
 with the vital portion of the atmosphere, which suddenly changes its colour 
 and other qualities. The blood will then be seen to flow into all the parts 
 which it stimulates, to keep up their energy, to awaken their action, 
 and furnish them the materials of the fluids which they secrete, or the 
 molecules by which they grow or are repaired ; so that, in supplying 
 thus the different organs, the blood loses all the qualities which it had 
 acquired by the union of the chyle and of the vital air, parts with 
 the principles to which it owed its colour, and again becomes dark, 
 to be repaired anew by combining with the lymph, and by the absorp- 
 tion of the vital part of the atmospheric air:* this constitutes the prin- 
 cipal phenomenon of the function which will be considered in the 
 next chapter. 
 
 CHAPTER IV. 
 
 OF RESPIRATION. 
 
 LXIX. The Purposes of this Function LXX. Of the Atmosphere LXXI. The 
 Mechanism of the Respiratory Organs. LXXII. Actions of the Respiratory 
 Muscles. LXXIII. Of Inspiration and Expiration. LXXIV. State of the 
 Lungs during Inspiration. LXXV. Of the Pulmonary Vessels. LXXVI. 
 
 Changes induced on the Blood and in the Air by Respiration LXXVII. Of 
 
 the nervous Influence in the function of Respiration LXX VIII. and LXXIX. 
 
 Of Animal Heat LXXX. and LXXXI. Of the Causes enabling the Body to resist 
 Increase or Diminution of Temperature. LXXXII. Source of Animal Heat 
 LXXXIII. The Pulmonary Circulation, and Changes induced upon the Chyle 
 received into the Venous Blood. LXXXIV. Of Pulmonary Exhalation 
 LXXXV. Of Asphyxia. LXXX VI. Of Sighing, Sobbing, Yawning, Sneezing, 
 Coughing, Hiccup, Laughing, &c LXXX VII. Of the Cutaneous Perspiration. 
 
 LXIX. OF the different changes which the blood undergoes in the 
 different organs, none are more essential or more remarkable than those 
 it receives from the air which during respiration is alternately received 
 into the lungs and expelled from them. The blood which the veins 
 convey to the heart, and which the right ventricle transmits to the 
 lungs, is of a dark colour, and heavy ; its temperature is only thirty 
 degrees (Reaumur) ; if laid by, it coagulates slowly, and there is sepa- 
 rated from it a considerable quantity of serum. The blood which is 
 brought by the pulmonary veins to the left side of the heart, and which 
 
 * j5ee the Note on Respiration, in the APPENDIX, for a different opinion.
 
 OF THE ATMOSPHERE. 198 
 
 is conveyed to all parts of the body by means of the arteries, is, on the 
 contrary, of a florid red colour; it is spumous, lighter, and warmer by 
 two degrees. It likewise coagulates more readily, and contains a 
 smaller quantity of serum. All these differences, which are so easily 
 distinguished, depend on the changes which it has undergone, by being 
 in contact with the atmospherical air. 
 
 LXX. Of the atmosphere. The mass of air which surrounds the 
 globe, and to which we give the name of atmosphere, bears on all 
 bodies with a pressure proportioned to their surface. That of man* 
 bears a weight of air amouffting to about thirty-six thousand pounds. 
 Moreover, one of its constituent principles is absolutely necessary to 
 the keeping up of life, of which it is a principal agent. 
 
 The variations in the weight of the atmosphere have, in general, but 
 little influence on the exercise of the functions ; nevertheless, when, by 
 ascending the tops of very high mountains, man rises several thou- 
 sand fathoms above the level of the sea, the remarkable diminution of 
 the weight of the air produces a very sensible effect. Respiration 
 becomes laborious and panting, the pulse is quickened, and there is felt 
 an universal uneasiness joined to excessive weakness, and haemorrhages 
 come on : these symptoms are occasioned both by the diminished pres- 
 sure of the air and by the smaller quantity of oxygen contained in a 
 rarer atmosphere. (Saussure, Voyage au Mont-Blanc). 
 
 The human body resists, without any effort, the atmospherical pres- 
 sure, because it is applied at all times, and in every direction. f But if 
 a part of its surface ceases for a moment to be under its influence, it 
 swells, the fluids are determined to it in considerable quantity, the inte- 
 guments become excessively distended, so as to be in danger of burst- 
 ing ; such are the phenomena which attend the application of cupping 
 glasses. 
 
 The pressure of the air on the surface of the globe is necessary to 
 the existence of bodies in the condition in which we see them. Several 
 very volatile fluids, as alcohol and ether, would become gaseous under 
 a less pressure of the atmosphere ; water would boil under eighty 
 degrees of temperature (Reaumur's scale); solid bodies themselves 
 might become fluid. In a word, a considerable diminution in the 
 weight of the atmosphere would have absolutely the same effect as 
 raising its temperature to a very great height, which, changing the face 
 
 * The surface of the body is estimated at fifteen or sixteen square feet, in a man 
 of middle size. 
 
 f- The pressure of the atmosphere is even necessary to the due performance of 
 some of our functions, as particularly respiration and venous circulation, to which 
 latter, according to the experiments of Dr. Cuf son and Dr. Barry, it appears to con- 
 tribute. See on this subject the Notes on Reipiration, iu the APPENDIX. /. C. 
 o
 
 194 CONSTITUTION OF THE ATMOSPHERE. 
 
 of the universe, would convert all liquids into elastic fluids, and would, 
 doubtless, melt all solid bodies. 
 
 The variations in the weight of the atmosphere, distinguishable by 
 the barometer, are of very little importance to the physiologist, and, 1 
 might even add, to the physician, notwithstanding the minute attention 
 with which some writers note the state of the barometer, of the thermo- 
 meter and hygrometer, and of the electrical state of the atmosphere, in 
 giving an account of a disease or of an experiment, on which the above 
 circumstances have no apparent or certain influence. The atmosphere, 
 like every other fluid, has a perpetual teridency to a state of equili- 
 brium ; hence the rush of air into the lungs, or into other situations, 
 in which its quantity is diminished by the combinations which it 
 forms, or by the effects of heat, which renders it lighter by rarefac- 
 tion : the same principle explains the formation of the trade and other 
 winds. 
 
 The atmospherical air combines with water and dissolves it, as the 
 latter dissolves saline substances. In this consists the process of eva- 
 poration. The air becomes saturated with water, in the same manner 
 as water becomes saturated with salt, to such a degree as to be inca- 
 pable of holding a greater quantity in solution. As its temperature 
 rises, its solvent power increases, and the latter diminishes as it grows 
 cold ; variations of temperature produce the same effect on solutions of 
 salts in liquids. The formation of all the aqueous meteors depends on 
 the different conditions of the solvent powers of the atmosphere ; when 
 considerable, the atmosphere is warm and dry, and the -air serene; 
 clouds form when it is saturated; dews, fogs, and rain, are the conse- 
 quence of a diminution of its solvent power, as snow and hail of a 
 degree of cold which precipitates the fluid. The different degrees of 
 dryness or moisture, marked by the hygrometer, only sensibly affect 
 the human body when it has been exposed for a considerable time to 
 its influence. 
 
 Chemically considered, the atmospherical air, which was long 
 regarded as a simple body, is composed of about -21 of oxygen, -79 
 of azote, by measure, and of -01 or -02 of carbonic acid. The car- 
 bonic acid is the more abundant as the air is less pure. This part of 
 natural philosophy, which is called eudiometry, or the measurement of 
 the purity of the air, is far from accomplishing what its name indicates, 
 and has disappointed the hopes which had been entertained on the sub- 
 ject. Eudiometrical instruments can inform us only of the proportion 
 of oxygen contained in the atmosphere ; now, its salubrity, its fitness 
 for respiration, is not in proportion to the quantity of oxygen. The 
 volatilised remains of putrid animal or vegetable substances, and various 
 mephitic gases, combine with it and affect its purity. In the compa-
 
 CONSTITUTION OF THE ATMOSPHERE. 195 
 
 rative analysis of air procured on the Alps and in the marshes of Lom- 
 bardy, there was found in each the same quantity of oxygen ; and yet, 
 those who breathe the former enjoy robust health, while the inhabitants 
 of the marshy plains of Lombardy are carried off by epidemic diseases, 
 are pale, emaciated, and habitually lead a languid existence. 
 
 Though at least '20 parts of oxygen are necessary to render the air 
 fit for respiration, the proportion may be diminished to seven or eight 
 parts in the hundred; but in such cases the breathing is laborious, 
 panting, and attended with a sense of suffocation; in short, asphyxia 
 comes on even while the air still contains a certain quantity of oxygen, 
 of which the lungs cannot entirely deprive it. Whenever a number of 
 persons are collected in a confined place, in which the air cannot be 
 easily renewed, the quantity of oxygen diminishes rapidly, while that 
 of carbonic acid increases. The latter, in consequence of its specific 
 gravity, sinks to the lowest part, and strikes with death every living 
 being which it envelopes. When two lighted candles of different 
 lengths are placed under the same bell, the shorter candle goes out 
 first, because the carbonic acid formed during combustion sinks to the 
 most depending part. For the same reason, the pit is the most 
 unhealthy part of a playhouse, when a great number of people, after 
 remaining in it for several hours, have deprived the air of a consider- 
 able portion of its oxygen. 
 
 Persons collected together and enclosed in a small space, injure 
 each other, not only by depriving the atmosphere of its respirable 
 element, but particularly by altering its composition, by the combina- 
 tion of all the substances exhaled from their bodies. These volatilised 
 animal emanations become putrid while in the atmosphere, and con- 
 veyed to the lungs during respiration, become the germ of the most 
 fatal diseases. It is in this manner that the gaol and hospital fever, so 
 fatal to almost all whom it attacks, arises and spreads. A dry and 
 temperate air, containing -21 of oxygen and -79 of azote, and free of 
 other gases or other volatilised substances, is the fittest for respiration. 
 In certain cases of disease, however, this function is most freely per- 
 formed in a less pure air. Thus, patients labouring under pulmonary 
 consumption, prefer the thick and damp air of low situations to the 
 sharp and dry air of mountains ; nervous women prefer that in which 
 horn, feathers, or other animal substances are burning. An atmo- 
 sphere highly electrical, at the approach of a storm, renders respiration 
 very laborious, in some cases of asthma. In short, the qualities of the 
 air must be suited to the condition of the vital power in the lungs, as 
 those of the food to the sensibility of the stomach. 
 
 Being obliged, on this subject, to content myself with the ungra- 
 cious office of compiler, I hasten to bring this article to a close, and to 
 refer the reader for a fuller account of the air, considered in its phy-
 
 196 MECHANISM OF THE RESPIRATORY ORGANS. 
 
 sical and chemical relations, to the works of MM. Fourcroy, Haiiy, 
 Brisson, Thenard, &c. ; and to that of M. Guyton Morveau, on the 
 method of purifying the air, when from different combinations it is be- 
 come unfit for respiration. 
 
 LXXI. The mechanism of the respiratory organs. In man, and in 
 all warm-blooded animals, with a heart containing two auricles and 
 two ventricles, the blood which has been conveyed to all the organs by 
 the arteries, and which has been brought back by the veins to the 
 heart, cannot return to it without having previously passed through the 
 lungs, which are viscera destined to the transmission of air, of a 
 spungy texture, and through which the blood must, of necessity, cir- 
 culate, to get from the right to the left cavities of the heart. This 
 course of the blood constitutes the pulmonary, or lesser circulation : 
 it does not exist in some cold-blooded animals. In reptiles, for 
 instance, the heart has but one auricle and one ventricle; the pul- 
 monary artery in them arises from the aorta, and conveys but a small 
 proportion of the blood ; hence, the habitual temperature of these ani- 
 mals is much lower than that of man. For the same reason, too, there 
 exists so small a difference between their venous and arterial blood ; 
 the quantity of fluid vivified by exposure to the air in the pulmonary 
 tissue being too small to effect, by its union with the general mass, a 
 material change on its qualities. 
 
 Mayow has given the most accurate notion of the respiratory 
 organ by comparing it to a pair of bellows, containing an empty blad- 
 der, the neck of which, by being adapted to that of the bellows, should 
 admit air on drawing asunder its sides. The air r in fact, enters the 
 lungs only when the chest dilates and enlarges, by the separation of its 
 parietes. The agents, of respiration are, therefore, the muscles which 
 move the parietes of the chest : these parietes are formed of osseous and 
 soft parts, in such a manner as to possess a solidity proportioned 
 to the importance of the organs which the chest contains, besides a 
 capacity of motion required to carry on the functions intrusted to 
 them.* 
 
 To carry on respiration, which may be defined the alternate 
 ingress of air into the lungs and its egress from those organs, it is 
 necessary that the dimensions of the chest should be enlarged (this 
 active dilatation of the cavity of the chest is called inspiration), and 
 that it should contract to expel the air which it had received during 
 the first process. This second action is called expiration ; it is always 
 of shorter duration than the former, its agents are more mechanical, 
 and the muscles have much less influence upon it. 
 
 * See APPENDIX, Note U, for remarks on the Mechanism of the Respiratory 
 Organs.
 
 MECHANISM OF THE THORAX. 197 
 
 The parietes of the chest are formed, at the back part, by the verte- 
 bral column, at the fore part by the sternum, and on the sides by the 
 ribs, which are osseo-cartilaginous arches, situated obliquely between the 
 vertebral column, which is fixed, and becomes the point of support of their 
 motions, and the sternum which is somewhat movable the spaces be- 
 tween the ribs are filled by muscular planes of inconsiderable thickness, 
 consisting of the internal and external intercostal muscles, the fibres of 
 which lie in opposite directions. Besides, several muscles cover the 
 outer part of the thorax, and pass from the ribs to the neighbouring 
 bones ; as the subclavian muscles, the great and lesser pectorals, the 
 serrati, the latissimi dorsi, the scaleni, the longissimi dorsi, the sacro- 
 lumbales, and the serrati minores, posteriores, superiores, and inferiores. 
 But of all the muscles which form the anterior, posterior, and lateral 
 parietes of the chest, the most important is the diaphragm, a fleshy and 
 tendinous partition, lying horizontally between the chest and the abdo- 
 men, which it divides from each other; it is attached to the cartilages 
 of the false ribs, and to the lumbar vertebrae, and has three openings to 
 transmit the oesophagus and the vessels which pass from the abdomen 
 to the chest, or from the latter into the abdomen. 
 
 In health, the chest dilates only by the descent of the diaphragm. 
 The curved fibres of that muscle, straightened in contraction, descend 
 towards the abdomen, and compress the viscera. The descent of the 
 viscera thrusts forward the anterior parietes of that cavity, and these 
 recede, when, on expiration taking place after inspiration, the dia- 
 phragm, now relaxed, rises, pressed upward by the abdominal viscera, 
 compressed themselves by the large muscles of the abdomen. But 
 when it is necessary to take into the chest a great quantity of air, it is 
 not sufficient that it should be enlarged merely by the descent of the 
 diaphragm it is required besides, that its dimensions should be 
 increased in every direction. The intercostal muscles then contract, 
 and tend to bring together the ribs between which they are situated. 
 The intercostal spaces, however, become wider, especially at their 
 anterior part ; for, whenever lines falling obliquely on a vertical line 
 change their direction, approaching to a right angle, the intermediate 
 spaces receive the greater increase, as the lines, more oblique at first, 
 become at last more nearly horizontal. Besides, as the ribs are curved 
 in the course of their length in two directions, and both in the direction 
 of their faces and edgewise, the convexity of the first curvature is out- 
 wards, and the ribs recede to a distance from the axis of the chest, whose 
 cavity is enlarged transversely; while the second curvature (in the direc- 
 tion of their edge) being increased by a real twisting of these bones, 
 and which reaches to the cartilaginous parts, the sternum is heaved for- 
 ward and upward, so that the posterior extremity of the ribs is removed 
 from their sternal end. But as the ribs are not all equally movable,
 
 193 ACTION OF THE RESHHATORY MUSCLES. 
 
 as the first is almost always invariably fixed, and as the others are 
 movable in proportion to their length, the sternum is tilted in such a 
 way that ihe lowermost extremity is thrust forward. The diameter of 
 the chest from the fore to the back pajrt increases, therefore, as well as 
 the transverse diameter. This increase of dimensions has been esti- 
 mated at two inches to each of these diameters ; the dimensions of the 
 vertical diameter, which are regulated by the depression of the dia- 
 phragm, are much greater. 
 
 LXXII. Action of the respiratory muscles, Professor Sabatier, in 
 his memoir on the motion of the ribs, and on the action of the inter- 
 costal muscles, maintains, that during the action of inspiration, the 
 upper ribs alone rise, that the lower ribs descend and slightly close on 
 the chest, while the middle ribs project outwardly ; and that in expi- 
 ration, the former set of ribs descend, that the latter start a little out- 
 wardly, and that the middle set encroach on the cavity of the chest. 
 The learned professor adds, that the cartilaginous articulating surfaces, 
 by which the ribs are connected to the transverse processes of the verte- 
 brae, appear to him to favour these different motions, as the direction of 
 the articulations of the upper ribs is upward, and that of the lower down- 
 ward; but, on considering the subject with attention, it will be seen, 
 that the surfaces by which the transverse processes of the vertebrae are 
 articulated to the tuberosities of the ribs, are turned directly forward in 
 the greatest number, while some of the lower ribs are, at the same 
 time, directed slightly upward. If we examine the action of the bones 
 of the chest during inspiration, in a very fchin person, for example, in 
 phthisical patients, whose bones are covered with little else than skin, 
 we shall find, that all the ribs rise, and are carried somewhat out- 
 wardly. It is not easy to conceive how the intercostal muscles, which 
 Professor Sabatier considers as the agents of respiration, should elevate 
 the upper ribs and depress the lower. The diaphragm, whose circum- 
 ference is inserted in the latter, might, by its contraction, produce this 
 effect ; but as the intercostals have their fixed point of action in the 
 upper ribs, they oppose and neutralise this effort, and all the ribs are 
 elevated at once. If this were not the case, the ribs ought to be 
 depressed whenever the intercostals contract, since the lowermost, 
 fixed by the diaphragm, would become the fixed point on which all the 
 others should move. 
 
 As the fibres of the external and internal intercostal muscles are in 
 direct opposition to each other, those of the former set of muscles hav- 
 ing an oblique direction, from above downward, and from behind for- 
 ward, and crossing the fibres of the other set, whose obliquity is in a 
 different direction, several physiologists have thought that these 
 muscles were opposed to each other; that the internal intercostal 
 muscles brought together the ribs after they had been separated by
 
 ACTION OF THE RESPIRATORY MUSCLES. 199 
 
 the external intercostals, the one set being muscles of expiration, while 
 the other set contracted during inspiration. 
 
 It is well known with what pertinacity Hamberger, in other 
 respects a physiologist of considerable merit, defended this erroneous 
 opinion in his dispute with Haller: it is now, however, ascertained, 
 that all the intercostal muscles concur itjudilating the chest, and that 
 they ought to be ranked among the agents of inspiration, because the 
 unequal capacity of motion in the ribs prevents the internal intercostals, 
 the lower insertion of which is nearer to the articulation of these 
 bones to the vertebrae, from depressing the upper ribs. Of the very 
 conclusive experiments by which Haller undertook to refute the argu- 
 ments of his adversary, I shall relate only that which is performed by 
 stripping the parietes of the chest in a living animal of all the muscles 
 which cover it, and by removing, in different parts of *he thorax, some 
 of the external intercostal muscles. The internal intercostals are then 
 seen to contract during inspiration, together with the remaining exter- 
 nal intercostals. These muscles, therefore, have a common action, and 
 are not in opposition to each other. . 4The same experiment serves to 
 prove the increased dimensions of the space between the ribs. On 
 holding one's finger between two of the ribs, it feels less confined, 
 when, during inspiration, these bones rise and thrust forward the 
 sternum. 
 
 This question being at rest, although in the pursuit of science one 
 should inquire how things are effected, and not wherefore they come 
 to pass, we feel naturally desirous to know what purpose is answered 
 by the different direction of the fibres of the two sets of intercostal ' 
 muscles; and with what view Nature has departed from her wonted 
 simplicity, in giving to their fibres opposite directions. In answer to 
 this I may observe, that the action of powers applied obliquely to a 
 lever being decomposed in consequence of that obliquity, a part of the 
 action of the external intercostals would tend to draw the ribs towards 
 the vertebral column, which could not? happen without forcing back 
 the sternum, if the internal intercostals did not tend to bring forward 
 the ribs at the same time that they elevate them ; so that these two 
 muscular planes, united in their action of raising the ribs, antagonise 
 and reciprocally neutralise each other, in the effort by which they tend 
 to draw them in different directions. 
 
 To this advantage of mutually correcting the effects that would 
 result from their respective obliquity, may be added the benefit arising 
 from a texture capable of a greater resi tance : it is clearly obvious, 
 that a tiss"e whose threads cross each other, is firmer than one in 
 which all tne threads, merely in juxta-position, or united by means of 
 another substance, should all lie in the same direction. Hence Nature 
 has adopted this arrangement in the formation of the muscular planes
 
 200 OF INSPIRATION AND EXPIRATION. 
 
 constituting the anterior and lateral parietes of the abdomen, without 
 which the abdominal viscera would frequently have formed herniary 
 tumours, by separating the fibres and getting engaged between them. 
 In this respect we may compare the tissue of the abdominal parietes, 
 in which the fibres of the external and internal oblique muscles, which 
 cross each other, are themselves crossed by the fibres of the transver- 
 sales, to the tissue of those stuffs whose threads cross each other, or 
 rather to wicker-work, to which basket-makers give so much strength 
 by interweaving the osier in a variety of directions. 
 
 LXXIII. Of inspiration and expiration. When from any cause 
 respiration becomes difficult, and the diaphragm is prevented from de- 
 scending towards the abdomen, or the motion of inspiration in any 
 way impeded, the intercostals are not alone employed in dilating the 
 chest, but are assisted by several other auxiliary muscles ; the scaleni, 
 the subclavii, the pectorals, the serrati magni, and the latlssimi dorsi r 
 by contracting, elevate the ribs, and increase, in more directions than 
 one, the diameter of the chest. The fixed point of these muscles then 
 becomes their movable point, the cerrical column, the clavicle, the 
 scapula, and the humerus, being kept fixed by other powers, which it 
 is unnecessary to enumerate. Whoever witnesses a fit of convulsive 
 asthma, or of a suffocating cough, will readily understand the import- 
 ance and action of these auxiliary muscles. 
 
 Inspiration is truly a state of action, an effort of contractile organs, 
 which must cease when these are relaxed. The expiration which fol- 
 lows is passive, and assisted by very few muscles, depending chiefly 
 on the re-action of the elastic parts which enter into the structure of 
 the parietes of the chest. We have seen that the cartilages of the ribs 
 are pretty considerably twisted, so as to carry outward and down- 
 ward their upper edge : when the cause which occasions this twisting 
 ceases to act, these parts return to their natural condition, and 
 bring back the sternum towards the vertebral column, towards which 
 the ribs descend from their weight. The diaphragm is forced towards 
 the chest by the .abdominal viscera, which are compressed by the 
 broad muscles of the abdomen. 
 
 In every effort of expiration, as in cough and vomiting, these muscles 
 re-act, not merely by their own elasticity, but they besides contract 
 and tend to approach towards the vertebral column, by pressing 
 upwards the abdominal viscera towards the chest. The triangularis 
 sterni, the subcostales, and the serratus inferior pesticus, may likewise 
 be ranked among the agents of expiration ; but they appear to be 
 seldom employed, and to be too slender and weak to contribute much 
 to the contraction of the chest. 
 
 LXXIV, State of the lungs during inspiration. When the chest 
 enlarges, the lungs dilate and follow its parietes as these recede from
 
 OF THE PULMONARY VESSELS. 201 
 
 each other. These two viscera, soft, spungy, and of less specific 
 gravity than water, covered by the pleura, which is reflected over them, 
 are always in contact with the portion of that membrane which lines' 
 the cavity of the thorax ; no air is interposed between their surfaces 
 (which are habitually moistened by a sgrous fluid exuding from the 
 pleura) and that membrane, as may be seen by opening under water 
 the body of a living animal, when no air will be seen to escape. As 
 the lungs dilate their vessels expand, and the blood circulates through 
 them more freely : the air contained in the innumerable cells of their 
 tissue becomes rarified, in proportion as the space in which it is 
 contained is enlarged. .Besides, the warmth communicated to it by 
 the surrounding parts, enables it, in a very imperfect manner, to 
 resist the pressure of the atmosphere, rushing through the nostrils and 
 mouth into the lungs by the opening in the larynx, which is always 
 pervious except during deglutition. 
 
 LXXV. Of the pulmonary vessels. The pulmonary tissue into 
 which the air is thus drawn every time the capacity of the chest is 
 increased, does not consist merely of air-vessels, which are but branches, 
 of different sizes, of the two principal divisions of the trachea, but js 
 formed, likewise, by the lobular tissue into which these canals deposit 
 the air ; it contains, also, a great quantity of lymphatics and blood- 
 vessels, of glands and nerves. Cellular tissue unites together all these 
 parts, and forms them into two masses, covered over by the pleura, and 
 of nearly the same bulk ;* suspended in the chest from the bronchia 
 and trachea, and every where in contact with the parietes of the 
 cavities of the chest, except towards their root, at which they receive 
 all their nerves and vessels. 
 
 The pulmonary artery arises from the base of the right ventricle, 
 and divides into two arteries, one .to each lung. On reaching the 
 substance of the lungs, these arteries divide into as many branches 
 as there are principal lobes. From these branches there arise others, 
 which again subdivide into lesser ones, until they become capillary, 
 and continuous with the radicles of the pulmonary veins. 
 
 These vessels, formed from the extremities of the artery, unite into 
 trunks, which progressively enlarging, emerge from the lungs, and 
 open, four in number, into the left auricle. Besides these large vessels, 
 by means of which the cavities in both sides of the heart communicate 
 together, the lungs receive from the aorta two or three arteries called 
 bronchial arteries : these penetrate into their tissue, where they follow 
 the direction of the other vessels, and terminate in the bronchial veins, 
 which open in the superior cava, not far from its termination into the 
 
 * It is well known that the right lung is larger than the left, and that it is di- 
 vided into thre principal lobes, while the latter has only two.
 
 202 OF THE PULMONARY VESSELS. 
 
 right auricle. These bronchial vessels are sufficient for the nourish- 
 ment of the pulmonary organ, which, in reality, is not near so bulky 
 as it appears, as may be ascertained by examining the lungs after all 
 the air has been extracted from them, by means of an air-pump applied 
 to the trachea. 
 
 Physiologists, for the most part, consider the bronchial arteries 
 as the nutritious vessels of the lungs. They assert, that as the blood 
 which flows along the branches of the pulmonary artery resembles 
 venous blood, it is unfit for the nutrition of the lungs, and that it was 
 necessary that these organs should be supplied by arteries arising from 
 the aorta, and containing blood analogous to that which is sent to 
 every part of the body. But though it be admitted that this venous 
 blood, brought from every part of the body and sent into the lungs 
 by their principal artery, may not be fit to maintain the organ in its 
 natural economy, this blood is fit for that use, when, after being made 
 hot, spumous, and florid, by the absorption of the atmospherical 
 oxygen, it returns by the pulmonary veins into the left cavities of 
 the heart. 
 
 Some have thought, that the Wood which flows in the bronchial 
 vessels, exposed to the action of the air, like the portion of this 
 fluid which traverses the pulmonary system, loses nothing of its 
 arterial qualities, and that, poured by the bronchial veins into the 
 superior or descending vena cava, it was a necessary stimulus for the 
 right cavities of the heart, of which blood entirely dark and venous 
 would not have awakened the contractility. But even, if the experi- 
 ments of Goodwin had not proved that the parietes of these cavities 
 have a sensibility relative to dark blood, by virtue of which this 
 stimulus is sufficient to determine their contraction, the action of the 
 heart does not depend as closely as has been said^ on the impression 
 of the blood on its substance, since it contracts, though empty, and 
 prolongs its contractions to relieve itself of the black blood which fills 
 it, when an animal dies of asphyxia. 
 
 Boerhaave, who admitted one sort of peripneumony depending 
 on the obstruction of the bronchial vessels, whilst another, according 
 to the same writer, depends on the obstruction of the pulmonary 
 vessels, seems to justify, in some measure, the reproach, exaggerated, 
 unquestionably, which some authors have thrown out against anatomy 
 of having rather retarded than accelerated the progress of the Hippo- 
 cratic practice of medicine. The anatomical analysis of the lungs, 
 or the distinction of the tissues which enter into their composition, 
 furnishes juster ideas of the difference of the inflammations by 
 which they may be attacked. It has been seen, that of these pul- 
 monary phlegmasise, the commonest and least serious consists in 
 inflammation of the mucous membrane which lines the air passages,
 
 OF THE PULMONARY VESSELS. 203 
 
 whilst the real peripneumony has its seat in the parenchyma of the 
 organ, which it converts into a hard and compact., mass. It is this 
 state that anatomists have long designated by the name of hepatisa- 
 tion, because, in fact, the substance of the lung has acquired the 
 hardness, the weight, and something of the appearance, of the liver. 
 The same anatomical researches have shewn that pleurisy consists in 
 inflammation of the pleura and of the surface of the lung, an in- 
 flammation which sometimes leaves no trace, but which oftener exhi- 
 bits, on the opening of bodies, the pleura thickened and opaque, 
 covered with a layer of coagulable lymph, whitish, more or less thick, 
 or even adhering to the lung.* 
 
 There arise from the surface and from the internal substance of the 
 lungs, a prodigious number of absorbents, which may be divided into 
 superficial and deep-seated. The latter accompany the bronchial 
 tubes, and penetrate into the substance of the glandular bodies 
 situated where those air-vessels divide, but collected in greatest 
 number towards the root of the lungs, and at the angle formed by 
 the bifurcation of the trachea. These bronchial glands, belonging to 
 the lymphatic system, do not differ from the glands of the same 
 kind, and are remarkable only by their number, their size, and their 
 habitually darkish colour. The absorbents of the lungs, after ramify- 
 ing in these glands, terminate in the upper part of the thoracic duct, 
 at the distance of a few inches from its termination into the subclavian 
 vein. Lastly, the lungs, though endowed with a very imperfect degree 
 of sensibility, have a pretty considerable number of nerves furnished by 
 the great sympathetic, and especially by the eighth pair. 
 
 It was long believed, on the authority of Willis, that the aerial 
 
 * These adhesions of the lung to the pleura costalis are so common, that the old 
 anatomists considered them as a natural disposition, and called them ligaments of 
 the lungs. It has been believed till now, that these adhesions arose from the or- 
 ganisation of a substance transuding from the two surfaces. Numerous dissections 
 have convinced me, that in all the points where they are met with, the pleura has 
 disappeared ; that it is decomposed ; and'that whether it be at the surface of the 
 lungs, or within the ribs and their muscles, it is produced by the act of inflamma- 
 tion ; that it is become cellular, by the thinning of its tissue and the separation of 
 its laminae. The pleura thus reduced to cellular tissue, the adhesion is produced 
 by the first intention, in the same way as in simple wounds immediately united. 
 There is no organ that abounds more than the lungs in facts important to morbid 
 anatomy. The variety of appearances they exhibit on the opening of bodies, is 
 almost innumerable ; and to give one instance, the pleura appears after pleurisy in 
 five perfectly distinct conditions : 1st, in its natural state, when the disease being 
 incipient and slight, the resolution is effected at the moment of death ; 2dly, 
 when it is red, thickened, and opaque; 3dly, when it is covered with coagulable 
 lymph ; 4thly, when it adheres ; Sthly, when, in consequence of chronic inflam- 
 mation, hydrothorax has taken place, &c. &c.
 
 204 CHANGES PRODUCED BY RESPIRATION- 
 
 tissue of the lungs is vesicular, that each ramification of the bronchia 
 terminated in their substance, in the form of a small ampullula ; but 
 at present most anatomists adopt the opinion of Helvetius. According 
 to him, every air-vessel terminates in a small lobe, or kind of spunge 
 fitted for the reception of air, and formed of a number of cells 
 communicating together. These lobes, united by cellular tissue, form 
 larger lobes, and these together form the mass of the lungs. 
 
 The tissue that connects together the different lobes is very 
 different from that in which the ramifications of the bronchia ter- 
 minate : air never penetrates into it, except when the tissue of the 
 air-cells is ruptured. On such occasions, which are not of rare 
 occurrence, on account of the excessive thinness of the laminse of the 
 air-cells of that tissue, the lung loses its form, and becomes emphy- 
 sematous. Haller estimates at about the thousandth part of an inch 
 the thickness of the parietes of the air-cells; and as the extreme 
 ramifications of the pulmonary vessels are distributed on these parietes, 
 the blood is almost in immediate contact with the air. There can be 
 no doubt that the oxygen of the atmosphere acts on the blood, under 
 such circumstances, since it alters its qualities, and communicates to it 
 a florid red colour, when enclosed in a pig's bladder, and placed under 
 a vessel filled with oxygen gas. 
 
 LXXVI. Changes produced in the air and blood by respiration. 
 Every time the chest dilates, in an adult, there enter into the lungs 
 between thirty and forty cubic inches of atmospherical air,* consisting, 
 
 * Some physiologists think that the quantity of air inspired is much less 
 considerable. Professor Gregory, of Edinburgh, states, in his public lectures, that 
 scarcely two inches of air enter into the lungs at each inspiration. It may be 
 proved, however, that this calculation is inaccurate, either by drawing a full 
 inspiration, as was done by Mayow, at the expense of a certain quantity of air 
 contained in a bladder, or by breathing into a vessel connected with a pneumatic 
 apparatus the air taken in by drawing a deep inspiration. Or else one may 
 inflate the lungs of a dead body, by adapting to the trachea a stop-cock, connected 
 with a curved tube to receive the air, under a vessel of the same apparatus. 
 Various means have been employed to measure the capacity of the chest. 
 Boerhaave placed a man in a tub containing water above his shoulders ; he then 
 made him take a deep inspiration, and measured the height at which the fluid rose 
 from the dilatation of the chest. Keill injected water into the chest of a dead body. 
 Lastly, it has been proposed to inject the bronchial tubes, and the lobular tissue into 
 which they terminate, with fusible metal, consisting of eight parts of pewter, five 
 of lead, three of bismuth, to which may be added one of mercury. 
 
 Menzies calculates the quantity of air admitted into the lungs at each re- 
 spiration, at 43 cubic inches; Sir H. Davy estimates it at about 17 ; Messrs. Allen 
 and Pepys at 16J ; and Goodwin and Abernethy at 12 only. There can be no 
 doubt that the estimate of Menzies is too high for the natural state of the 
 respiration ; but the quantity of aii received at such inspiration must necessarily 
 vary very much, according to the size and conformation of the individual.
 
 CHANGES PRODUCED BY RESPIRATIOX. 205 
 
 when pure, of seventy-nine parts in the hundred of azote, twenty-one 
 of oxygen, and a fractional part of carbonic acid.* 
 
 When the air has been exposed, for a few moments, in the 
 pulmonary tissue, it is expelled by the effort of expiration ; but it is 
 diminished in quantity, and is reduced to thirty-eight inches. Its 
 composition is no longer the same ; it contains, it is true, -79 parts 
 of azote, but the vital portion fit for respiration, the oxygen, has un- 
 dergone a great diminution; its proportion is only '14: carbonic acid 
 forms the remaining *07, and there are sometimes found one or 
 two parts of hydrogen. It is, besides, affected by the addition of an 
 aqueous vapour, which is condensed in cold weather, as it escapes at 
 the mouth and nostrils. It is called the humour of the pulmonary 
 transpiration. These changes, compared to those which the blood 
 experiences in passing through the lungs, clearly shew a reciprocal 
 action of this fluid and of the oxygen of the atmosphere. The dark 
 venous "blood which coagulates slowly, and which then disengages a 
 considerable quantity of serum, abounding in hydrogen and carbon, 
 and of a temperature of only thirty degrees, yields its hydrogen and 
 carbon to the oxygen of the atmosphere, to form carbonic acid and 
 the pulmonary vapour ; and as oxygen cannot enter into these new 
 combinations without parting with a portion of the caloric which 
 keeps it in a state of gas, the blood acquires this warmth, which is 
 disengaged the more readily, according to the ingenious experiments 
 of Crawford, as, by parting with its hydrogen and carbon, its capacity 
 for caloric increases in the proportion of 10 : 11 -5. 
 
 In parting with its carbon, which, by uniting with oxygen, forms 
 the carbonic acid that is thrown out during expiration, the blood loses 
 its dark and nearly purple colour, and becomes of a florid red, and 
 its consistence increases, from the escape of its hydrogen and of its 
 aqueous parts. Besides, as it absorbs a certain quantity of oxygen, it 
 becomes spumous and light ; its concrescibility and plasticity increase, 
 and on coagulating, there is separated from it a smaller quantity of 
 serum. 
 
 After parting with its hydrogen and carbon, and combining with, 
 oxygen and caloric, in its passage through the lungs, the blood, which 
 is become arterial, parts with these two principles, in proportion as, in 
 receding from the heart, it forms new combinations, and is converted 
 into oxides of hydrogen and carbon, which, on receiving an additional 
 quantity of oxygen, are changed into water and carbonic acid, when, 
 on being carried along with the venous blood into the pulmonary 
 tissue, they are exposed to the influence of the atmospherical air. 
 
 .* See APPENDIX, Note W, for observations on the changes induced on the 
 air, and on the blood, by respiration.
 
 206 ON THE VENOUS BLOOD. 
 
 The arterial blood becomes venous by yielding its oxygen, when 
 any cause whatever suspends or slackens its course, as is proved by 
 the following experiment of John Hunter. He tied the carotid artery 
 of a dog with ligatures placed at the distance of about four inches 
 frpm each other : the blood contained in the portion of artery 
 included between the two ligatures, on faying open this part of the 
 vessel at the end of a few hours, was found coagulated, and as dark 
 as that in the veins. The blood contained in an aneurismal sac, and 
 which is frequently found in a fluid state, when the internal coats of 
 the artery are but lately ruptured, becomes venous after remaining in it 
 some time. The changes, however, which the blood undergoes in its 
 course through the arterial system, are not very remarkable, owing to 
 the rapidity with which it flows along those vessels : there is less 
 difference between the blood contained in an artery near the heart 
 and that contained in an artery at a distance from that organ, than in 
 the blood taken from the veins near their extremities and from the 
 great trunks which deposit it into the right auricle. The blood in the 
 small veins resembles arterial blood ; and frequently, in a very copious 
 bleeding, the colour of the blood, which, at first, is very dark, 
 gradually becomes less so, till, towards the end of the bleeding, it 
 shews nearly the same qualities as the arterial ; a phenomenon which, 
 as is well observed by the English writer already quoted, depends on 
 the more easy and rapid flow of the blood of the arteries into the 
 veins, in consequence of the evacuation of the venous system. This 
 observation is a complete refutation of the assertion of Bellini, who 
 maintains, that when a vein is wounded, the blood which comes from 
 it forms-a double current, which flows out at the wound. The abcve 
 opinion is maintained by highly distinguished physiologists, as Haller 
 and Spallanzani, who support it by experiments performed on the 
 vessels of cold-blooded animals, or on veins without valves. In 
 bleeding at the bend of the arm, the blood cannot come from that part 
 of the vessel which is above the wound ; the valves oppose insuperable 
 obstacles to its retrograde flow: hence it is very easy to distinguish the 
 red blood which comes 1 from the lower extremity of the vein from that 
 which flows from the upper end, and which is poured into the vessel 
 by the veins which open into it, between the puncture and the nearest 
 valve. 
 
 In its course to the parts among which the arteries are distri- 
 buted, the blood, vivified in its passage through the lungs, and 
 fitted, as M. Fourcroy says, for a new life, loses its oxygen and 
 caloric. Its capacity for the latter diminishes in proportion as the 
 oxygen, by combining with hydrogen and carbon, restores it to the 
 venous state. 
 
 This theory of the process by which the blood parts with its
 
 THEORY OF RESPIRATION. 207 
 
 oxygen in its progress along the blood vessels, is rendered still more 
 probable by recent discoveries on the nature of the diamond. This 
 substance is the only pure carbon, and that which is called so by 
 chemists is an oxide of carbon, which owes its dark colour to the 
 oxygen with which it is combined. Before these experiments, it was 
 not easy to determine the particular condition of the carbon which 
 exists so plentifully in venous blood. 
 
 No precise calculation has yet been made of the quantity of 
 oxygen absorbed by the venous blood, nor of the quantity employed 
 in the combustion of hydrogen and carbon in the lungs, so as to form 
 water and carbonic acid.* 
 
 Is the carbon in venous blood merely combined with oxygen, or 
 is it united with hydrogen, so as to form carburetted hydrogen? It 
 appears to me more probable, that the oxygen which is absorbed by 
 combining with hydrogen in every part of the body produces the 
 water which dilutes the venous blood, renders it more fluid and 
 richer in serum than arterial blood, while, by its union with carbon, 
 it forms an oxide that gives to the blood the dark colour which is one 
 of its most remarkable characters. On reaching the lungs, which 
 are real secretory organs, the water is exhaled, dissolved in the air, 
 and forms the pulmonary transpiration ; the oxide of carbon, com- 
 pletely decomposed by an additional quantity of oxygen, constitutes 
 carbonic acid, which gives to the air that is expired the power of 
 forming a precipitate in lime water. 
 
 The absorption of oxygen by the venous blood explains how the 
 phenomena of respiration are continued into every part of the body, 
 and produce the warmth uniformly diffused over all our organs. In 
 proportion as the blood parts with its caloric, for which its affinity 
 diminishes as it becomes venous, the parts which give out their 
 hydrogen and carbon combine with it. If the lungs were the only 
 organs in which caloric might be disengaged, the temperature of those 
 viscera ought considerably to exceed that of other parts : experience, 
 however, shews that the temperature of the lungs is not sensibly 
 more elevated. ' ^- 1 
 
 This theory of respiration, for which we are entirely indebted to 
 modern chemistry, is contradicted by no one phenomenon. The 
 greater the extent and capacity of the lungs, the more frequent is 
 respiration, and the greater the warmth and vivacity of animals. 
 
 * Instead of saying that the venous blood absorbs oxygen, it will approach nearer 
 the state of our knowledge to believe, that the venous blood both gives off its car- 
 bon, which combines in the lungs with the oxygen of the inspired air, and absorbs 
 a portion of oxygen, with a very variable proportion of azote. For a full view of 
 the^ latest opinions on this subject, see APPENDIX, Note W. J. C.
 
 208 VITAL INFLUENCE OF THE LUNGS. 
 
 Birds, whose lungs extend into the abdomen by various membranous 
 sacs, and whose bones are hollow and communicate with the lungs, con- 
 sume a great deal of oxygen, either on account of the magnitude 
 of this respiratory apparatus, or from their frequent, and, at times, 
 hurried respiration. On that account, the habitual temperature of 
 their body exceeds that of man and mammiferous animals. In rep- 
 tiles, on the contrary, whose vesicular lungs admit but a very small 
 quantity of blood, and present to the atmosphere a surface of very 
 limited extent, and in which respiration is performed with intervals of 
 longer duration, the body is at a temperature which, naturally, 
 never rises above seven or eight degrees. 
 
 LXXVII. Of the vital influence of the lungs in the function of re- 
 spiration. Though the temperature or warmth of the body is ge- 
 nerally proportioned to the extent of respiration, to the quantity 
 of blood exposed in a given time to the action of the atmospherical 
 air, it may be higher or lower, according to the degree of the vital 
 energy of the lungs. These organs should not be considered as mere 
 chemical receivers; they act on the air, digest it, as the ancients 
 said, and combine it with the blood, by a power which is peculiar to 
 them.* If it were otherwise, there would be nothing to prevent a 
 dead body from being restored to life,' by inflating with oxygen its 
 pulmonary tissue. The ancients alluded to this action of the lungs 
 on the air we breathe, by calling that air the pabulum vita. Its 
 digestion was, they thought, effected in the lungs, in the same manner 
 as the digestion in the stomach of other aliments less essential to life, 
 and whose privation may be borne for a certain time, while life is en- 
 dangered when the aeriform nutriment ceases to be furnished to the 
 lungs for the short space of a few minutest 
 
 In proof of the vitality of the lungs, and of the share which they 
 have in producing the changes which the blood undergoes in passing 
 through them, I may mention the experiment which proves that an 
 animal placed under a vessel filled with oxygen, and breathing that 
 gas in a pure state, consumes no more of it than if it was received 
 into the chest mixed with other gases unfit for respiration. A 
 guinea-pig placed under a vessel full of vital air, and of known ca- 
 pacity, will live four times longer than if the vessel contained atmosphe- 
 rical air. No remarkable difference is at first perceived in the act of 
 respiration, but if the animal remains long immersed in the oxygen, his 
 respiration becomes more frequent, his circulation more rapid, and all the 
 vital functions are executed with more energy. The lungs separate, 
 by a power inherent in themselves, the two atmospherical gases, and 
 this process is effected by a pretty considerable power ; for oxygen, in 
 
 * See APPENDIX, Note W.
 
 VITAL INFLUENCE OF THE LUNGS. 209 
 
 its combination with the blood, is with difficulty separated from azote. 
 In fact, the blood, though in thin layers, becomes dark when exposed 
 to the atmospherical air. 
 
 It is observed, that the purity of the air contained in the receiver 
 is the more readily affected, as the animal placed under it is younger, 
 more robust, and as his lungs are more capacious. Hence birds, 
 whose lungs are very large, contaminate a considerable quantity of 
 air, and consume more quickly its respirable part. A frog, on the 
 contrary, will remain a considerable time in the same quantity of air, 
 without depriving it of its oxygen. 
 
 The vesicular lungs of that reptile, as well as of all oviparous 
 quadrupeds, are much more irritable than those of warm-blooded 
 animals ; they appear to contract at the will of the animal. The 
 frog is without a diaphragm, attracts the air into its lungs by swal- 
 lowing it by a real process of deglutition, as was proved by Professor 
 Rafu, of Copenhagen, who killed those animals by holding their jaws 
 asunder for a certain time. They reject the air by a contraction 
 of the lungs, in the same manner as in man the bladder empties 
 itself of urine. 
 
 In birds, whose diaphragm is equally membranous, and contains 
 several openings to transmit the air into the pulmonary appendices, 
 the parietes of the thorax are likewise more movable than iu man and 
 quadrupeds. Their pectoral muscles are more powerful, their ribs 
 contain a joint situated in the middle of those arches which are com- 
 pletely ossified in that class of animals : and those two portions move 
 on each other, forming, at their point of union, angles more or less 
 acute, according to the distance of the sternum from the vertebral 
 column. J^-; '-'.I 
 
 A numerous class of cold red-blooded animals, viz. fishes, have no 
 lungs ; the gills, which supply their place, are small penniform laminae, 
 generally four in number, situated on each side, at the posterior and 
 lateral part of the head, covered over by a movable lid, to which 
 naturalists give the name of operculum. The water which the animal 
 swallows, passes, when it chooses, through the parietes 'of the 
 pharynx, which contain several pretty considerable openings, is spread 
 over the gills and the pulmonary vessels which are distributed in them, 
 then escapes at the auricular apertures, when the animal closes its 
 mouth and raises the opercula. It is not known whether the water 
 is decomposed and yields its oxygen to the blood which circulates in 
 the gills, or whether the small quantity of air that is dissolved in the 
 water, alone serves to vivify the pulmonary blood. The latter opinion 
 seems the most probable, if it be considered that a fish may be 
 suffocated by closing accurately the vessel of water in which it is en- 
 closed. The same result might, I conceive, be obtained, by placing
 
 210 VITAL INFLUENCE OF THE LUNGS. 
 
 the vessel under the receiver of an air-pump, so as entirely to 
 exhaust it. 
 
 Respiration, which is completely under the influence of the brain, 
 as far as relates to its mechanism, is Mess dependent upon it in regard 
 to the action of the lungs on the blood, and the combination of this 
 fluid and of its carbonaceous elements with oxygen, which is the 
 essential object of that function. The nerves, however, have some 
 influence on the changes which the blood experiences in the lungs 
 during respiration, as well as on the various secretions, in the for- 
 mation of which, according to Bordeu, they are of first-rate import- 
 ance. M. Dupuytren ascertained by his experiments, that the divi- 
 sion of the cervical portion of the eighth pair of nerves did not 
 sensibly affect respiration; but the animal died with all the symp- 
 toms of asphyxia when this nerve was divided on both sides. Death 
 took place in the course of a few minutes, when the experiment 
 was performed on horses. Other animals did not die so soon after ; 
 dogs, for instance, have been known to live several days after the ex- 
 periment. By interrupting the communication between the lungs and 
 the brain, we paralyse the former of these organs, and it ceases to 
 convert the venous into arterial blood.* This fluid, conveyed by the 
 pulmonary artery, continues of a dark colour when brought to the 
 left cavities of the heart ; the arteries convey the blood without its 
 having received its vivifying principle, in passing through the lungs, 
 which are paralysed by having their nerves tied or divided. It is 
 easy to conceive that all organs, for want of the stimulus which deter- 
 mines their action, carry on their functions imperfectly, and at last 
 cease to act. The animal heat is likewise lowered a few degrees, as 
 was ascertained by the above-mentioned physician, who thinks he has 
 established as a fact, that the ligature of the nerves of the lungs does 
 not destroy, but weakens the vital power> which enables them to take up 
 the oxygen, and to give out the carbonic acid. The brain, therefore, 
 possesses a double influence over the function of respiration ; on the 
 one hand, it directs its mechanism by means of the nerves which it 
 sends to the diaphragm and to the intercostal muscles ; and on the 
 other hand, it is through the nerves which arise from the brain, that 
 the lungs have the power of converting dark blood into arterial blood, 
 which is the principal phenomenon of respiration.* 
 
 Experiments performed on the same subject by Dr. Legallois, sub- 
 sequent to, those I have just related, tend to throw some degree of 
 uncertainty on their results. Dr. Legallois repeated these experiments 
 
 * By dividing these nerves (the eighth pair) we paralyse the muscles of respira- 
 tion, and occasion a species of asphyxia. We prevent the renewal of the air, . 
 but we do not directly injure the vital functions of the lungs themselves J. C.
 
 OF ANIMAL HEAT. 211 
 
 publicly, in my presence, and at the society of the Ecole de Mede- 
 cine of Paris. After dividing the two nerves of the eighth pair, in a 
 guinea-pig, and after having by that process brought on a state of 
 asphyxia, he restored life and motion to the animal by opening the 
 trachea at its anterior part. The blood of the carotids, which from 
 red had become dark the moment the nerves were divided, assumes 
 a brighter colour as soon as respiration is restored, and the animal lives 
 several days after the experiment. Whence does this difference arise ? 
 does the division of the eighth pair bring on asphyxia, by occasioning 
 spasmodic constriction of the glottis, and by impeding or even com- 
 pletely obstructing, the admission of the atmospherical air ? * 
 
 LXXVIII. Of animal heat. The human body, which is habitually 
 of a temperature of between thirty-two and thirty-four degrees of 
 Reaumur's thermometer,t preserves the same degree of warmth under 
 the frozen climate of the polar region, as well as under the burning 
 atmosphere of the torrid zone, during the most severe winters and the 
 hottest summers. Nay, further, the experiments of Blagden and 
 Fordyce in England, and of Duhamel and Tillet in France, shew, that 
 the human body is capable of enduring a degree of heat sufficient to 
 bake animal substances. The fellows of the Academy of Sciences saw 
 two girls enter into an oven in which fruits and animal substances 
 were being baked ; Reaumur's thermometer, which they took in with 
 them, stood at 150 degrees; they remained several minutes in the 
 oven without suffering any inconvenience. 
 
 All living bodies have a temperature peculiar to themselves, and 
 independent of that of the atmosphere. The sap of plants does not 
 freeze, when the thermometer stands only at a few degrees below zero ; 
 on placing the bulb of a thermometer in a hole in the trunk of a tree 
 during winter, the fluid sensibly rises. Now, three circumstances 
 remain to be investigated : in the first place, what produces in living 
 bodies this inherent and independent temperature ? In the second 
 place, how do these bodies resist the admission of a greater degree of 
 heat' than that which is natural to them? What prevents caloric, 
 which has a perpetual tendency to a state of equilibrium, from passing 
 into a body surrounded by a burning atmosphere ? Lastly, how does a 
 body which resists the influence of heat, withstand equally the de- 
 structive influence of an excessive degree of cold ? J 
 
 LXXIX. Caloric, in a latent state, or in combination with bodies, 
 is disengaged from them, whenever they assume a different state ; 
 when, from a gaseous form they become liquid ; or when from being 
 liquid they become solid. Now, living bodies, are a kind of labora- 
 
 * See APPENDIX, Note W. f Between 96 and 98 of Fahrenheit. 
 
 See the remarks in APPENDIX, Note Y, on the production of Jnimal Heat.
 
 212 OF ANIMAL HEAT. 
 
 tory, in which all these changes are perpetually going on ; the 
 blood which circulates in every part of the human frame is con- 
 stantly receiving supplies of fresh materials ; from the thoracic duct, 
 which pours into it the chyle, abounding in nutritious particles ; from 
 respiration, which imparts to it an aeriform principle, obtained from 
 the atmosphere ; and even, in some cases, from cutaneous absorption, 
 through which different elements are received into it. All these 
 different substances carry along with them into the blood a certain 
 quantity of caloric, which is combined with them, and which is dis- 
 engaged during the changes which they undergo, from the influence 
 of the action of the organs, and gives out its caloric to the parts 
 among which it is disengaged. Of all the principles in the blood 
 which have the power of communicating heat to the organs, none 
 furnishes a greater quantity than oxygen, which, during respiration, 
 combines with the blood in the lungs. Gaseous substances, it is well 
 known, contain most combined caloric; their state of elastic fluidity 
 is entirely owing to the accumulation of that principle, and they part 
 with it, when from any cause whatever they become liquid. It is on 
 that account that the heat of bodies is greater, the more they have 
 the power of impregnating their fluids with a considerable quantity of 
 oxygen from the atmosphere. For the same reason, as was already 
 observed, in animals that have cellular lungs, and a heart with two 
 ventricles, the blood is of the same temperature as in man ; and 
 such animals belong, as well as man, to the great class of warm red- 
 blooded animals; a class in which birds occupy the first place, from 
 the vast extent of their lungs, which reach into the abdomen, a'nd 
 communicate with the principal bones of the skeleton. The capacity 
 of the pulmonary organ of birds is not the only cause why their tem- 
 perature is eight or ten degrees higher than that of man : this increase 
 of temperature depends, likewise, on the greater frequency of their 
 respiration, and on the velocity of their pulse ; on the quickness and 
 multiplicity of their motions, and on the vital activity which animates 
 them. In reptiles, which have vesicular lungs, and a heart with a 
 single ventricle, whose respiration is slow, and performed at distant 
 intervals, the blood, though red, is of very inferior temperature to that 
 of man. They have, from that circumstance, been called cold red- 
 blooded animals : this numerous class includes fishes, which possess 
 an organ supplying but imperfectly the office of lungs. In fishes, 
 the heart, which has but a single ventricle, sends, it is true, to the gills 
 (the organ supplying the place of lungs is so called) the whole of the 
 blood ; that fluid, however, is but imperfectly vivified in the gills, on 
 account of the small quantity of air which can be taken in during 
 the act of respiration. Lastly, in white-blooded animals and in plants, 
 the combinations with the air being more difficult, the vital energy less
 
 OF AX1MAL HEAT. 213 
 
 marked, the temperature differs only by a few degrees from that of the 
 atmosphere, and they do not endure heat or cold so well as the more 
 perfect animals. 
 
 The lungs, as was before observed, consuming only a certain 
 quantity of air, there is no increase of temperature, however great the 
 quantity of oxygen contained in the atmosphere that is breathed; as 
 a man who should take a double quantity of aliment could not receive 
 more nourishment than if he contented himself with the quantity 
 of food proportioned to his wants ; for, as the digestive organs can 
 extract only a certain quantity of chyle, the quantity of recre- 
 mentitious matter would only be greater, if more than the due quantity 
 of food were received into the stomach. Hence the common saying, 
 N that nourishment comes from what we digest, and not from what we eat. 
 
 The pulmonary organ may, however, act on the air with different 
 degrees of power in robbing it of its oxygen ; and when the body 
 becomes of an icy coldness, in certain nervous and convulsive affec- 
 tions, this cold may depend as much on the atony of the lungs, and 
 on the spasmodic condition of the chest, which, dilating with difficulty, 
 does not admit the air readily, as on the spasm and general insensibility 
 of the organs, which allow the blood to pass without affecting its 
 component parts. It would be curious to ascertain, whether or no 
 the air expired from the lungs of a cateleptic is deprived of less oxy- 
 gen, is less impaired in purity, and contains a smaller quantity of car- 
 bonic acid, than the breath of a sound active adult. Perhaps it would 
 be found, that in catalepsy, and other similar affections, the blood does 
 not part with its hydrogen and carbon, that it retains its colouring 
 principles and the different materials of the urine, which is voided 
 in a colourless and limpid state, insipid and without smell, and in the 
 condition of a mere serosity. 
 
 The temperature of the body is not only produced by the pulmo- 
 nary and circulatory combinations, it is besides developed in several 
 organs, in which fluid or gaseous substances become solid, by parting 
 with a portion of their caloric. Thus, digestion, particularly of 
 certain kinds of food, is an abundant source of caloric ; the skin, 
 which is habitually in contact with the atmosphere, decomposes it, and 
 deprives it of its caloric. Lastly, caloric is produced and evolved in 
 all parts whose molecules, affected by a double motion, in conse- 
 quence of which they are incessantly being formed and decomposed, 
 by changing their condition and consistence, absorb or disengage 
 more or less caloric. The great activity of the power of assimila- 
 tion in children is, no doubt, the cause of the habitually high tem- 
 perature at that period of life.* The temperature of the body is 
 
 * Considering the temperature of the body to be under the influence of that part 
 of the nervous system which is distributed to the blood-vessels, as pointed out in
 
 214 OF AXIMAL HEAT. 
 
 not only one or two degrees higher at that period of life, but young 
 people, after death, preserve, for a longer period, the remains of vital 
 heat; or rather, as tonicity does not so soon forsake the capillary 
 vessels, life departing reluctantly, the'combinations from which caloric 
 is evolved continue some time, even after it is extinct. For the same 
 reason, the bodies of persons that have died suddenly retain their 
 warmth long, while an icy coldness seizes those who have died of a 
 lingering disease, from the slow, gradual, and total abolition of the 
 powers of life. 
 
 - Calorification, or the disengaging of animal heat, like nutrition, 
 takes place at all times, and may be considered as belonging to all 
 organs. It was of the utmost consequence that the internal temperature 
 of the human body should be nearly the same at all times. For, let us 
 for one moment suppose, that the temperature of the blood should rise 
 to fifty degrees of Reaumur's thermometer, its albuminous parts would 
 suddenly coagulate, obstruct all the vessels, interrupt the circulation, 
 and destroy life. When, therefore, from an increased activity of the 
 nutritive combinations, a greater quantity of heat is disengaged, the ani- 
 mal economy parts with it, and it is taken up in greater quantity by 
 the surrounding bodies. This accounts for the equality of the tempera 
 ture of the internal parts of the body in old people and in children, 
 notwithstanding the difference of their temperature externally. The 
 difference consists in this, that where most caloric is produced most is 
 given out, and though the blood and urine in old people, as well as in 
 the young, are at thirty-two degrees, what a difference is there not 
 between the hot and penetrating perspiration which is poured in abun- 
 dance from the child, and the clryness and coldness of the skin in 
 old people ! between the sweet and warm breath of the former, and the 
 frozen breath of the latter ! Hence the opinion so generally received, 
 and of such antiquity, that old people are benefited by cohabiting with 
 the young. Thus we are told, that David had a young virgin brought 
 to him, that he might lie with her, and get heat in his limbs that Vere 
 stiffened with years.* 
 
 If it be true, that in the very act of nutrition, which converts our 
 fluids into solids, there is disengaged a considerable quantity of caloric, 
 
 the note on this suhject in the APPENDIX, the reason will appear evident, why 
 animal warmth is greater in young and robust subjects, than in the old and debili- 
 tated. Indeed, the temperature holds a close relation with the other changes which 
 take place in the different textures of the body ; and it, as well as these, seems 
 equally to result from the influence of these nerves upon the vessels to which they 
 
 are distributed J. C. 
 
 * The ancients appeared to have some idea of what the moderns would do well 
 to attend to more than they have done, if, indeed, they have attended to it at all, 
 namely., the beneficial influence of the application of animal warmth to the system 
 when its vital influence is either languid or sinking. J. C.
 
 OF ANIMAL HEAT. 215 
 
 the motion of nutritive decomposition, by which our solids are con- 
 verted into liquids, must cause an equal quantity of heat to he absorbed. 
 The objection is a very strong one, and not easily trot over : it may be 
 answered by observing, that all living bodies, from the instant of 
 their formation, contain a certain quantity of caloric, which they 
 retain, so that this double process of acquiring heat and parting with 
 it, the unavoidable result of nutritive composition and decomposition, 
 merely keeps up an equilibrium, and maintains the same degree of 
 temperature. 
 
 The blood, which becomes saturated with oxygen in the capillaries 
 of the lungs, parts with that principle, and disengages its caloric 
 throughout the capillary vessels of the whole body, of which each 
 organ must set free a greater quantity, in proportion to the activity 
 of the living principle, and to the rapidity of the circulation. The 
 parts through which the greatest number of vessels circulates, perhaps, 
 give out most caloric, and communicate a portion of it to the organs 
 which receive but a small quantity of blood, as the bones, the car- 
 tilages, &c. It is easy to understand why an inflamed part, through 
 which the blood circulates with more rapidity, and whose sensibility 
 and contractility are much increased, is manifestly hotter to the feel 
 of the patient and of the physician, though, as was observed by John 
 Hunter, a thermometer applied to the inflamed part shews a scarcely 
 perceptible increase of temperature. He injected into the rectum of a 
 dog, and into the vagina of an ass, a strong solution of oxymuriate of 
 mercury. Acute inflammation came on, the swollen mucous mem- 
 brane formed, externally, a considerable projection. Blood flowed from 
 the torn capillaries, yet the thermometer rose very slightly, only one 
 degree of Fahrenheit. But however slight that increase of heat in the 
 inflamed part, it is very sensibly felt, on account of the extreme sen- 
 sibility of the organ, whose vital properties are all increased. The 
 liveliness of impressions being proportionate to the degree of the power 
 of sensation, one need not wonder that the patient should experience a 
 sense of burning heat in a part in which the thermometer indicates 
 no increase of temperature, or in which it cannot be perceived even by 
 the touch. I have just felt a young man's hand that is swollen from 
 chilblains ; though the pain which he feels in it seems to him to be 
 occasioned by an accumulation of caloric, his hand is colder than 
 mine, which is of the same degree of warmth as the rest of my body, 
 and in which I have no peculiar sensation. It may, therefore, be laid 
 down as an axiom, that the real or thermometrical increase of heat is 
 inconsiderable in inflammation, but that it is intensely felt in conse- 
 quence of the increase of sensibility.* 
 
 * For some remarks on the Influence of the Nervous System in the production 
 of Animal Heat, see ATPEXDIX, Note Y.
 
 216 OK ANIMAL HEAT. 
 
 What is the reason that, during the cold fit of a febrile paroxysm^ 
 a sensation of excessive cold is felt in a part in which no diminution 
 of heat can be discovered by the touch? Whence comes the burning- 
 heat which attends inflammatory fever (causus) ? What is the cause 
 of the difference of the sensations attending the heat of erysipelas, 
 bilious fevers, and phlegmon, &c. ? These various sensations are 
 owing to the different modifications of sensibility in these different dis- 
 eases. Should this explanation appear unsatisfactory, let it be recol- 
 .lected, that however accurate may be the calculations that have been 
 made on the subject of caloric, or of the matter of heat, the exist- 
 ence of caloric itself is hypothetical, and that it is not known whe- 
 ther caloric is a body, or whether heat is merely a property of 
 matter. 
 
 LXXX. Of the causes enabling the body to resist increased tempera- 
 ture. If we now inquire into the causes which enable the body to 
 resist the admission of a degree of heat superior to that which habitu- 
 ally belongs to it, we shall be compelled to admit a power in all living 
 bodies, by means of which they repel an increase of heat, and retain 
 the same temperature. Cutaneous perspiration, it is true, acts very 
 powerfully in lowering the temperature; and as this evaporation increases 
 with the temperature, it should seem as if this function, sufficed to mode- 
 rate the heat of the body, and to restore the equilibrium. 
 
 It is a fact known since the time of Cullen,* that the evaporation 
 of fluids,, or their solution in the air, is the most powerful means of 
 cooling bodies, and that the mercury in the bulb of a thermometer may 
 be frozen merely by moistening it with aether, spirits of wine, or any 
 other volatile substance, and then exposing it to a dry and warm air. 
 This method is equally successful in its application to the human body, 
 and the hands may be cooled to such a degree as to feel benumbed, 
 by being frequently wetted with a spirituous fluid, and by being moved 
 in a dry and renewed air. But though cutaneous perspiration operates 
 in a somewhat similar manner, and though it may be ranked among 
 the means which nature employs to preserve the animal temperature in 
 a nearly uniform state, it must, however, be confessed, that it is not 
 Ihe only way in which this object is accomplished, and that it does not 
 satisfactorily account for this phenomenon ; for, the evaporation of the 
 fluids contained in dead animal substances does not prevent their 
 being roasted on the application of heat; and besides, fishes and 
 frogs have been known to live and retain their temperature in mineral 
 waters nearly of a boiling heat.f 
 
 * This celebrated physician made this discovery about forty years ago, which 
 has thrown much light on several physico-chemical phenomena, and he published it 
 in a dissertation, entitled, " Of the cold produced by evaporating fluids, and of some 
 other means of producing cold," by Dr. W. Cullen. 
 
 f See Sonnerat's " Voyage to the East Indies."
 
 OF ANIMAL HEAT. 217 
 
 I thought it right to repeat these experiments, and with this view, I 
 placed living frogs in a vessel containing water at fifty degrees of tem- 
 perature, and on taking them out, at the end of ten minutes, I ascer- 
 tained that they were not so hot as the liquid, nor as pieces of flesh 
 which had been put into it at the same time. 
 
 We cannot admit the opinion of Grimaud, that living bodies have 
 the power of producing cold ; for as cold is merely the absence of heat, 
 one cannot allow a positive existence to a negative being. 
 
 Habit has a remarkable influence on the faculty which the body 
 possesses of bearing a degree of heat much exceeding that which is 
 natural to it. Cooks handle burning coals with impunity ; workmen 
 employed in .forges leave the mark of their feet on the burning and 
 liquid metal at the moment when it becomes solid by cooling. Many, no 
 doubt, recollect the too famous instance of a Spaniard, who became so 
 general a subject of conversation in Paris : this young man, in making 
 his way through a house on fire, perceived that the heat was less 
 inconvenient to him than he had imagined. He applied himself to bear, 
 with impunity, the action of fire, and was enabled to touch with his 
 tongue a spatula heated red hot, and to apply the soles of his feet and 
 the palms of his hands on a red hot iron, or on the surface of boiling 
 oil. Nothing can equal the absurdity and the exaggeration of the 
 stories that were told of this man, except the ignorance and the want 
 of veracity of those who invented them. The following is a correct 
 statement of the feats of this man, who was represented as in- 
 combustible and insensible. He passes rapidly along the surface of 
 his tongue, which is covered with saliva, a red-hot spatula, the action 
 of which seems merely to dry it, by bringing on an evaporation of 
 the fluids with which it is covered. After carrying the spatula 
 from the base to the tip of his tongue, he brings it back again into his 
 mouth, and applies it to his palate, to which it communicates a part of 
 its heat, at the same time that it becomes moistened with saliva. 
 This man having, in a public exhibition, carried on too long the appli- 
 cation of the spatula, the caustic effects of its heat shewed themselves ; 
 the epidermis was detached, and found coiled, like the outer covering 
 of an onion, in the cloth which he used to wipe his .mouth. He does 
 not dip his hands and feet in boiling oil, he merely applies to the sur- 
 face of the fluid his palms and his soles, and he repeats this frequently, 
 with only .3. short interval between each application. When the 
 experiment is carried on for a certain length of time, there is emitted 
 a smell of burnt horn. No one has yet observed, that though this 
 man's hands are not callous, the palms of these, and the soles of 
 his feet, are cushioned with fat. A thick layer of fat, which is a bad 
 conductor of heat, separates the skin from the subjacent aponeuroses
 
 218 OF ANIMAL HEAT. 
 
 and nerves : this circumstance, to a certain degree, accounts for his 
 imperfect sensibility. 
 
 His pulse, during those experiments, was about a hundred and 
 twenty ; the perspiration evidently increased, and sometimes copious. 
 Every part of his body possesses the ordinary degree of sensibility, may 
 be destroyed by the protracted application of caustic substances, and 
 would be consumed by fire, if applied for a sufficient length of time ; 
 and nitric acid would infallibly destroy his tongue, if he took any into 
 his mouth, as it has been said he did. This man, therefore, in no 
 one respect departs from the known laws of the animal economy, but, 
 on the contrary, affords an additional proof of the influence of habit on 
 our organs.* 
 
 LXXXI. Causes enabling the body to resist cold. Before bringing 
 to a conclusion this article on animal heat, it remains for me to explain 
 how the body resists cold, and preserves its temperature in the midst of 
 a frozen atmosphere. This cannot be accomplished without an increase 
 of activity in the organs; it is only by augmenting the sum of the com- 
 binations by which caloric is disengaged, that we can succeed in 
 making up for the loss of that principle so necessary to our existence. 
 What is the reason that in cold weather digestion is more active, 
 (Hieme verb venires sunt calidiores, Hipp.) the pulse stronger and more 
 frequent, and the vital energy greater ? It is because heat comes from 
 the same source, and is produced by the same mechanism, as the nutri- 
 tion of the organs; and that its evolution may go on increasing, it is 
 necessary that the secretions, nutrition, in a word, all the vital func- 
 tions, should increase in the same proportion. 
 
 Observe, for a moment, a man who is exposed to a moderate 
 degree of cold ; he feels more activity, more strength, and is more 
 nimble ; he walks and exerts himself, the most violent exertions do not 
 appear to him laborious, he struggles against the disadvantages of the 
 debilitating influence ; and provided the cold is not excessive, and the 
 body tolerably vigorous, there is disengaged within himself a sufficient 
 quantity of caloric to make up for the. loss of that which is carried off 
 by the air and the surrounding bodies. These general effects of cold 
 are not disproved by what happens, when only a part of the body is 
 exposed to it. Supposing the temperature a few degrees below zero, 
 there is felt, at first, a sensation of cold much more inconvenient, 
 ccEteris paribus, than if it acted on a more extensive surface. The spot 
 on which the cold air acts becomes affected with a painful sense 
 
 * There is every, reason to believe that these feats are performed by means of a 
 composition previously applied to the parts about to be exposed to the high temper, 
 ature J. C.
 
 SOURCE OF ANIMAL HKAT. 219 
 
 of pricking, reddens, then inflames; and in this case, inflammation is 
 evidently the result of a salutary effort of nature, which determines 
 into the inflamed part an excess of the vital principle, so that the quan- 
 tity of heat that is disengaged may correspond to that which has been 
 abstracted. The effort of this conservatory principle is more marked 
 than if the whole surface of the body were at once exposed to cold, 
 because, acting wholly on a limited point, of small extent, it operates 
 with more intensity. 
 
 Beyond a certain degree, however, nature in vain struggles against 
 .cold ; if severe, and if the creature exposed to it have not the power of 
 sufficient re-action, the part becomes purple and benumbed from the 
 loss of its caloric, vitality ceases, and it mortifies ; and if the whole 
 body is equally exposed to the influence of cold, the person is benumbed, 
 feels a stiffening of his limbs, stammers, and, overpowered by an irre- 
 sistible propensity, yields to a sleep which inevitably ends in death. 
 By yielding thus to the illusive sweets of a perfidious sleep, many 
 travellers have perished, after losing their way, in the mountains of 
 the old and of the new world. Thus, two thousand soldiers of Charles the 
 Twelfth's army perished, during a siege, in the severe winter of 1790. 
 
 To resist the effects of cold, a certain degree of strength and vigour 
 is therefore necessary ; it is consequently very injudicious to recom- 
 mend the cold bath to very young children, to delicate and nervous 
 women, to persons whose constitution is not capable of a sufficient 
 re -action. The evil attending the injudicious use of this remedy in the 
 cases that have just been enumerated, justifies the apparently singular 
 terms in which Galen expressed himself: " Let the Germans (says this 
 first of physiologists), let the Sarmatians, those northern nations as bar- 
 barous as bears and lions, plunge their children in frozen water ; what 
 I write is not intended for them." 
 
 On the other hand, if it be recollected that there is within us a 
 power of re-action which increases with use, that motion strengthens 
 our organs, it will be readily understood that cold acts as a tonic, 
 whenever it is nqt applied to such a degree as to extinguish the vital 
 power. 
 
 The manner in which enlightened physicians have, at all times, 
 prescribed the cold bath, shews that they were acquainted with this 
 tonic effect depending, not on the application of cold, which in itself is 
 debilitating, but on the re- action which it occasions. Hence, along 
 with the cold bath, they are in the habit of recommending exercise, a 
 generous wine, bark, nutritious food, and an aualeptic regimen, calcu- 
 lated to excite a salutary re-action. 
 
 LXXXII. Source of animal heat. Animal heat is, therefore, pro- 
 duced by the combinations of our fluids and solids in the process of 
 nutrition ; it is a function common to all the organs, for, as they all
 
 220 SANGUIFYING FUNCTION OF THE LUNGS. 
 
 nourish themselves, so they all disengage, more or less, the caloric 
 combined with the substances which they apply to their nutrition. 
 
 Though we are without precise information respecting the manner 
 in which a living body resists the admission of a degree of heat exceed- 
 ing that which is natural to it, one may consider cutaneous exhalation, 
 which is increased by the use of heating substances, as the most power- 
 ful means employed by nature to get rid of the excess of heat, and to 
 restore the equilibrium. 
 
 Lastly, the body resists cold, because the 'organs being rendered 
 more active by cold, there is disengaged a quantity of caloric equal to 
 that which is carried off by the air, or by the other substances with 
 which the body happens to be in contact.* 
 
 LXXXIII. Sanguifying function of the lungs. The rapidity of the 
 circulation of the blood through the lungs, is equal to the velocity with 
 which it flows in the other organs. For if, on the one hand, the pari- 
 etes of the right ventricle and of the pulmonary artery are weaker and 
 thinner than those of the left ventricle and aorta, the lungs, from their 
 soft, easily dilated, and spungy texture, are the most easily penetrated 
 by fluids of all our organs. 
 
 The right ventricle sends into the lungs a quantity of blood equal 
 to that which each contraction of the left ventricle propels into the 
 aorta, and it is not necessary to adopt the opinion of M. Kruger, that 
 each contraction of the heart propels into the lungs, and into the rest of 
 the body, an equal quantity of blood ; for, in that case, the circulation 
 would have been much slower, the length of the lungs being much 
 shorter than the whole body. Nor need we say, with Boerhaave, that 
 this circulation is much more rapid, because the same quantity of blood 
 returns by the extremities of the pulmonary artery, and of all the other 
 arteries of the body. 
 
 The extension of the pulmonary tissue, and the straightening of its 
 vessels, are, no doubt, favourable to the circulation of the blood, but if 
 the admission of air did not answer a different purpose, the circulation 
 would not be indispensably necessary. The blood flows from the right 
 into the left cavities of the heart, notwithstanding the collapse of the 
 lungs, and the creases of their vessels. The air which penetrates, 
 at all times, into the lungs, supports their tissue and the vessels which 
 are distributed to it; so that, even during expiration, the vessels are 
 much less creased than has been imagined by several physiologists. 
 
 The animal economy resists a moderate degree of cold, and is even strength- 
 ened by it, owing to the re-action of the vital influence. If, however, the degree of 
 cold be either absolutely or relatively great, the energy of the system is entirely 
 overwhelmed by its sedative operation. The effects of cold differ not only according 
 to its degree, but also according to the duration of exposure to it, to the state ot the 
 nervous system previous to, or during the exposure, and to the general condition 
 of the body at the time. J. C.
 
 OF PULMON 7 ARY EXHALATION. 221 
 
 But the changes produced by the contact of the atmosphere, renovate 
 this fluid, and fit it to re-excite and keep up the action of all the organs 
 which require to be stimulated by arterial blood. If you make a liv- 
 ing animal breathe de-oxygenated air, the blood undergoes no change 
 by its pulmonary circulation ; the left cavities of the heart are no 
 longer duly irritated by this fluid, which preserves all its venous quali- 
 ties ; their action becomes languid, and with it that of all the organs ; 
 and in a little while it ceases altogether. It is revived by introducing 
 pure air, through a tube fitted to the trachea ; all the parts seem to 
 awake out of a sort of lethargic sleep, in which they are again 
 immersed by depriving the lungs anew of the vital air. 
 
 The chyle, mixed in great quantity with the venous blood, under- 
 goes, in its passage through the heart and the sanguineous svstem, a 
 more violent agitation: its molecules are struck together, break on 
 each other, and, thus attenuated, become more perfectly intermingled : 
 in its passage through the lungs, a great part of this recrementitious 
 fluid is deposited by a sort of internal perspiration, in the parenchy- 
 matous substance of these viscera. Oxydated by the contact of the 
 air, and re-absorbed by a multitude of lymphatic or inhalant vessels, it 
 is carried into the bronchial glands, which are found blackened by 
 what it there deposits of carbonic and fuliginous matter. Purified by 
 this elaboration, it returns into the thoracic duct, which pours it into 
 the subclavian vein, whence it soon returns to the lungs, to be there 
 anew subjected to the action of the atmosphere ; so that there is 
 effected, through these organs, a real lymphatic circulation, of which 
 the object is to bring the chyle to a higher degree of animalisation. 
 
 LXXXIV. Of pulmonary exhalation. It will be remembered that 
 one of the great differences between the blood of the arteries and that 
 of the veins consists in the great quantity of serum found in this last. 
 It is in the lungs that the separation of this aqueous part takes place 
 and that its proportion is reduced, whether it be that oxygen gives 
 albumen and gelatine a greater tendency to concrete, or that the 
 serum, formed by the fixation of oxygen throughout the whole extent 
 of the circulatory system, exhales from the arteries, and thus furnishes 
 the matter of pulmonary exhalation. It is scarcely possible to admit 
 the combination of oxygen with the hydrogen of the venous blood, and 
 that water is thus formed from its elements, as happens when storms 
 are gathering in the high regions of the atmosphere. If a similar pro- 
 cess can be carried on in the lungs, without producing deflagration and 
 the various phenomena attending the production of aqueous meteors, it 
 is probable that it furnishes but a small part of the exhalation ; and 
 that this humour, analogous to the serum of the blood, exhales, com- 
 pletely formed, from the arterial capillaries ramified in the bronchia
 
 222 OF ASPHYXIA. 
 
 and the lobular tissue of the lungs. It is believed that the quantity of 
 the pulmonary exhalation is equal to that of the cutaneous exhalation 
 (four pounds in twenty-four hours). These two secretions are supple- 
 mental to one another ; when much water passes off by the pulmonary 
 exhalation, the cutaneous is less, and vice versd. 
 
 The surface from which the pulmonary exhalation is given out, is 
 equal, if not superior, in extent to that of the skin ; exhalation and 
 absorption are at once carried on from that surface, many nerves are 
 distributed to it, and are almost exposed in the tissue of the membranes, 
 which are extremely thin. Are the miasmata, with which the atmo- 
 sphere is sometimes loaded, absorbed by the lymphatics, which, it is well 
 known, have the power of taking up gaseous substances ; or do they 
 merely produce on the nervous and sensible membranes of the bron- 
 chia, and of the lobular tissue, the impression whence the diseases of 
 which they are the germ arise ? 
 
 A part of the caloric which is disengaged in the combinations which 
 oxygen undergoes in the lungs, is taken up in dissolving and redu- 
 cing into vapour the pulmonary exhalation, which is the more abun- 
 dant according as respiration is more complete. Pulmonary exhalation 
 should be carefully distinguished from the mucous matter secreted 
 within the bronchia and trachea, and which is thrown up by a forcible 
 expiration, and forms the matter which we expectorate. 
 
 LXXXV. Of asphyxia* The term asphyxia, though merely indi- 
 cating a want of pulse, is applied to any kind of apparent death occa- 
 sioned by an external cause, and suspending respiration, as submersion, 
 strangulation, the diminution of oxygen in the air inhaled, &c. The 
 only difference between real death and asphyxia is, that in this last 
 state the principle of life may yet be re-animated, whilst in the other 
 it is completely extinct. 
 
 Asphyxia takes place in drowning, because the lungs, deprived of 
 air, no longer impart to the blood which passes through them the qua- 
 lities essential to the support of life. The water does not find its way 
 into these viscera ; the spasmodic closing of the glottis prevents its 
 getting into the trachea and its branches. Yet there is found a small 
 quantity in the bronchia after drowning, always frothy, because air has 
 mixed with it, in the struggles which precede asphyxia. If the body 
 remain long under water, the spasmodic state of the glottis ceases, 
 water passes into the trachea and fills the lungs. The anatomical 
 examination of a drowned body shews the lungs collapsed, and in 
 the state of expiration ; the right cavities of the heart, the venous 
 trunks which terminate in them, and, generally, all the veins, are 
 
 * See APPENDIX, Note W.
 
 ASPHYXIA FKOM DROWNING AND HANGING. 223 
 
 gorged with blood,* whilst the left cavities and the arteries are almost 
 entirely empty. Life ceases in this kind of asphyxia, because the 
 heart has sent to the different organs, and especially to the lungs, no 
 blood that is not deficient in the qualities necessary to their action ; 
 and, perhaps, also, because the venous blood that is accumulated in 
 the tissues, affects them by its oppressive and deadly influence. On 
 that account, the best way of restoring the drowned to life is to blow 
 pure air into their lungs. This is done by means of bellows adapted to 
 a canula introduced into the nostril ; if a proper apparatus cannot be 
 procured, one might blow with his mouth into that of the drowned 
 person, or into his nostrils, by means of a tube ; but air so expired, 
 having already undergone the process of respiration," contains a much 
 smaller quantity of oxygen, and is much less fitted to excite the action 
 of the heart. There remain several other less efficacious remedies, 
 such as friction, bronchotomy, glysters, fumigations and suppositories, 
 stimulating errhines, and especially ammonia ; stimulants taken into 
 the mouth and stomach, the application of fire, bleeding, the bath, 
 electricity, and galvanism. 
 
 The redness and lividity of the face in persons who are hanged, had 
 led to the opinion, that death, in such cases, was from apoplexy ; but it 
 appears that in the asphyxia from strangulation, as in that from drown- 
 ing, death is caused by the interception of the air. To prove this, 
 Gregory perfohned the following experiment : he opened the trachea 
 of a dog, and passed a noose round his neck, above the wound. The 
 animal, though hanged, continued to live and to breathe ; the air 
 entered and came out alternately, at the small opening : he died when 
 the constriction was applied below the wound. A respectable surgeon, 
 who served in the Austrian army, assured me, that he had saved the 
 life of a soldier, by performing upon him the operation of laryngotomy 
 a few hours before his execution. 
 
 Persons who are hanged may die, however, from dislocation of the 
 cervical vertebrae, and from the injury done at the same time to the 
 spinal marrow. Louis, it is well known, ascertained, that of the two 
 executioners in Lyons and Paris, the one despatched the criminals 
 he executed by dislocating the head at its articulation with the 
 neck, while the other executioner destroyed them by inducing 
 asphyxia. 
 
 Of the different mephitic gases unfit for respiration, some appear 
 to bring on asphyxia, merely by depriving the lungs of the vital air 
 necessary to the support of life, while others evidently affect the 
 
 * Hence the dark and livid colour of the skin and conjunctiva. This last mem- 
 brane is frequently injected with dark blood ; the very delicate veins of the brain 
 are considerably dilated, and this viscus is distended with venous blood.
 
 224 ASPHYXIA FllOM INKHKIATIOX AM) DKCLUTITION. 
 
 organs and the blood which fills them, by their poisonous and dele- 
 terious influence. 
 
 One may mention, among the former, carbonic acid : in the 
 asphyxia occasioned by this gas, aiid wh'cb, of ail others, is the most 
 frequent, the blood preserves its fluidity, the limbs their suppleness, 
 and the body its natural warmth, or even a greater degree of warmth, 
 for some hours after death ; for, this kind of asphyxia occurring always 
 in a very hot situation, the body, deprived of life, admits an excess of 
 caloric, such as would have been resisted if the vital power had not 
 been suspended. However, in this asphyxia, as in the preceding, the 
 lungs remain uninjured ; the right cavities of the heart and the venous 
 system are gorged with a dark but fluid blood. In the asphyxia, on 
 the other hand, that is occasioned by sulphuretted or phosphuretted 
 hydrogen, &c., or by certain vapours whose nature is not well under- 
 stood, and which escape from privies, or from vaults in which a num- 
 ber of dead bodies undergo putrefaction, there are frequently found 
 in the lungs dark and gangrenous marks, and death seems the effect 
 of a poison which is the more active, as its particles, exceedingly 
 divided and in a gaseous state, are more insinuating, and affect, 
 throughout its whole extent, the nervous and sensible surface of the 
 
 Inebriation seldom goes the length of bringing on asphyxia ; it most 
 commonly produces a stupor readily distinguished from the affection 
 treated of in this article, by the perceptible, though obscure pulse, and 
 by the motions of respiration, though these are rare and indistinct. On 
 this account, M. Pinel, in his Nosographie Philosophujue, has placed 
 inebriation, and the different kinds of asphyxia, in two separate genera 
 of the class neuroses. It is conceivable, however, that the muscular 
 irritability may be so far impaired by the use of spirituous liquors, that 
 the heart and diaphragm might lose the power of contraction, which 
 would bring on complete asphyxia. 
 
 The glottis, through which the atmospherical air passes in its way 
 to the lungs, is so small, that it may be readily obstructed, when the 
 epiglottis rising at the moment of deglutition, the substance that is 
 swallowed stops at the orifice of the larynx : a grape seed may produce 
 this effect ; and it was in this manner, we are told, that Anacreon, that 
 lovely poet of the graces and of voluptuousness, came by his death. 
 Gilbert, the poet, died in the same way, after a long and painful 
 agony. A great eater, in the midst of a feast went into an adjoining 
 room, and did not return, to the great surprise of all the guests. He 
 was found stretched on the floor, without any sign of life. Help, 
 given by ignorant people, was of no use. On opening the body, a piece 
 of mutton was found fixed in the larynx, and completely stopping the 
 passage of the air.
 
 OF SIGHIMG, SOBBIXO, YAWNING, &C. 225 
 
 Sometimes a child is born, and shews no signs of life. When it 
 is prob'able, from the circumstances of the delivery, that there has been 
 no organic injury decidedly mortal, it must be considered as a case of 
 asphyxia from weakness ; and all means employed that are recom- 
 mended in such cases, especially blowing in air into the lungs, by 
 means of a tube introduced into the mouth or nostrils. It is thus 
 that the Prophet Elisha restored to life the son of the Shunamite, as 
 we are informed in the second book of Kings, chapter the fourth. 
 
 LXXXVI. Of certain phenomena of respiration^, as sighing, sobbing, 
 yawning, sneezing, coughing, hiccup, laughing, <rc. When the imagi- 
 nation is strongly impressed with any object, when the vital functions are 
 languid, the vital principle seems to forsake all the organs, to concentrate 
 itself on those which partake most in the affection of the mind. When a 
 lover, in the midst of an agreeable reverie, sighs deeply, and at intervals, 
 a physiologist perceives in that expression of desire, nothing but a long 
 and deep inspiration, which, by fully distending the lungs, enables the 
 blood collected in the right cavities of the heart to flow readily into 
 the left cavities of that organ. This deep inspiration, which is fre- 
 quently accompanied by groans, becomes necessary, as the motions of 
 respiration, rendered progressively slower, are no longer sufficient to 
 dilate the pulmonary tissue. 
 
 Sobbing differs from sighing merely in this, that though the ex- 
 piration is long, it is interrupted, that is, divided into distinct periods. 
 
 Yawning is effected in the same manner ; it is the certain sign of 
 ennui, a disagreeable affection, which, to use the expression of Brown, 
 may be considered as debilitating, or asthenic. The fatigued inspi- 
 ratory muscles have some difficulty in dilating the chest, the contracted 
 lungs are not easily penetrated by the blood which stagnates in the 
 right cavities of the heart, and produces an uneasy sensation, which is 
 put an end to by a long and deep inspiration ; the admission of a 
 considerable quantity of air is facilitated by opening the mouth 
 widely by the separation of both jaws. One yawns at the approach of 
 sleep, because the agents of inspiration, being gradually debilitated, 
 require to be roused at intervals. One is, 'likewise, apt to yawn on 
 waking, that the muscles of the chest may be set for respiration, which 
 is always slower and deeper during sleep. It is for the same reason 
 that all animals yawn on waking, that the muscles may be prepared 
 for the contractions which the motions of respiration require. The 
 crowing of the cock, and the flapping of his wings, seem to answer the 
 same purpose. It is in consequence of the same necessity, that the 
 numerous tribes of birds in our groves, on the rising of the sun, 
 warble, and fill the air with harmonious sounds. A poet then fancies 
 he hears the joyous hymn by which the fea hered throngs greet the 
 return of the god of light.
 
 226 OF RESPIRATION DURIXG MUSCULAR ACTIONS. 
 
 While gasping lasts, the perception of sounds is less distinct ; the 
 air, as it enters the mouth, rushes along the Enstachian tubes into the 
 tympanum, and the membrane is acted upon in a different direction. 
 The recollection of the relief attending the deep inspirations which 
 constitute gaping, the recollection of the grateful sensation which 
 follows the oppression that was felt before, involuntarily leads us to 
 repeat this act whenever we see any one yawning. 
 
 Sneezing consists in a violent and forcible expiration, during 
 which the air, expelled with considerable rapidity, strikes against the 
 tortuous nasal passages, and occasions a remarkable noise. The 
 irritation of the pituitary membrane determines, by sympathy, this 
 truly convulsive effort of the pectoral muscles, and particularly of the 
 diaphragm. 
 
 Coughing bears a considerable resemblance to sneezing, and 
 differs from it only in the shorter period of duration, and the greater 
 frequency of the expirations ; and, as in sneezing, the air sweeps along 
 the surface of the pituitary membrane, and clears it of the mucus 
 which may be lying upon it, so the air, when we cough, carries along 
 with it the mucus contained in the bronchia, in the trachea, and 
 which we spit up. The violent cough at the beginning of a 
 pulmonary catarrh, the sneezing which attends coryza, shew that the 
 functions of the animal economy are not directed by an intelligent 
 principle, for such an archaeus could not mistake, in such a manner, 
 the means of putting a stop to the disease, and would not call forth 
 actions which, instead of removing the irritation and inflammation 
 already existing, can only aggravate them. 
 
 Laughing is but a succession of very short and very frequent 
 expirations. In hiccup the air is forcibly inspired, enters the larynx 
 
 with difficulty, on account of the spasmodic constriction of the glottis ; 
 
 it is then expelled rapidly, and striking against the sides of that 
 
 aperture, occasions the particular noise attending it. 
 
 I shall, on another occasion, explain the mechanism of sucking, of 
 
 panting, and of the efforts by which the muscles of the thorax fix the 
 
 parietes of that cavity, so that it may serve, as a fixed point of the other 
 
 muscles of the trunk and of the limbs. 
 
 Respiration is besides employed in the formation of the voice ; but 
 
 the voice, and the different modifications of which it is capable, will 
 
 form the subject of a separate chapter.* 
 
 * The author has neglected to notice the state of respiration during the more 
 active voluntary motions. Muscular exertion, especially when considerable, is 
 preceded by a full inspiration, immediately upon which the glottis is firmly closed 
 and the abdominal muscles contracted. At this moment the diaphragm is relaxed ; 
 but the complete closure of the glottis, and contraction of the abdominal muscles 
 engaged in respiration, furnish a fixed basis of action to the muscles employed in
 
 OF THE CUTANEOUS PERSPIRATION. 227 
 
 LXXXVII. Of cutaneous perspiration. An abundant vapour is 
 continually exhaling from the whole surface of the body, and is called 
 the insensible perspiration, when in a state of gas in the air which 
 holds it in solution, it then eludes our sight; it is called sweat, when 
 in greater quantity and in a liquid form. Sweat differs, therefore, 
 from insensible perspiration, only by the condition in which it appears ; 
 and it is sufficient for its production, that the air should be incapable 
 of reducing it into vapour, whether from an increased secretion by 
 the skin, or from the dampness and consequent diminished solvent 
 powers of the atmosphere. The insensible perspiration is constantly 
 escaping through the innumerable pores in the parietes of the minute 
 arteries of the integuments ; it oozes in the interstices of the scales of 
 the skin; the air which immediately surrounds our body becomes 
 saturated with it, and carries it off as soon as it is renewed. There is 
 the greatest resemblance between the cutaneous perspiration and the 
 pulmonary exhalation ; both are mere arterial exhalations ; and the 
 mucous membrane which lines the canals along which the air is 
 transmitted, is a mere prolongation of the skin into those organs and 
 into the digestive tube. The surface from which the cutaneous 
 perspiration is exhaled, is not quite so considerable as that from which 
 the pulmonary exhalation arises, since it is reckoned at only fifteen 
 
 great exertions. At the same time that the glottis is closed, the muscles of the 
 face participate in the action, in consequence of being supplied with branches of the 
 respiratory order of nerves, (see the Notes in the APPENDIX on the different Orders 
 and Functions of the Voluntary System of Nerves), and the jaws are forcibly pressed 
 together. By this action of the muscles engaged in respiration, the chest is 
 rendered capacious, the circulation through the lungs facilitated, and the strength 
 thereby greatly increased because the trunk of the body is thus rendered immov- 
 able in respect of its individual parts, the muscles arise from fixed points, and 
 consequently wield the limbs with their full energy. Haller appears to be correct, 
 in concluding that, under a state of increased action of the muscles, the flow of 
 blood becomes greater towards the head : the nervous energy is increased, by means 
 of this augmented flow, and supplied so as to keep up the muscular action for a 
 longer period than otherwise would be the case. During violent exertions, also, 
 the return of blood from the brain is in some degree impeded. 
 
 The physiological state of muscular actions, as they are related to the mecha- 
 nical function of respiration, is very happily described by Shakespeare, where he 
 makes the fifth Henry encourage his soldiers at the siege of Harfleur : 
 
 " Stiffen the sinews, summon up the blood, 
 
 ****** 
 
 Now set the teeth, and stretch the nostrils wide ; 
 Hold hard the breath, and bend up every spirit 
 To his full height." 
 
 In vomiting also, and in the action of expelling the faeces and contents of the 
 bladder, the thoracic and abdominal muscles of respiration are brought into 
 action, and the glottis closed J. C.
 
 228 OF THE CUTANEOUS PERSPIRATION. 
 
 square feet in a man of middle size. These two secretions are 
 supplementary to each other; the increase of the one is generally 
 attended with a sensible diminution of the other ; lastly, the mucous 
 membrane of the intestinal canal, besides secreting mucus, exhales 
 likewise a fluid which increases much in quantity when the cutaneous 
 perspiration is languid, as is proved jby the serous diarrhoeas so 
 frequently occasioned by a suppressed perspiration. It must be 
 owned, however, that notwithstanding those analogies of structure and 
 function in the skin and mucous membranes, there exists perhaps a 
 still more intimate connexion between its action and that of the organs 
 which secrete the urine : it has always been observed, that when this 
 last fluid is scanty, there is a greater cutaneous perspiration, and 
 vice versd. 
 
 If we examine with a microscope the naked body, exposed 
 during summer to the rays of a burning sun, it appears surrounded 
 with a cloud of steam, which becomes invisible at a little distance 
 from the surface. And if the body is placed before a white wall, it is 
 easy to distinguish the shadow of that emanation. We may likewise 
 satisfy ourselves of the existence of the cutaneous perspiration, by the 
 following experiment : hold the tip of the finger at the distance of the 
 twelfth part of an inch from a looking-glass, or any other highly 
 polished surface, its surface will soon be dimmed by a vapour 
 condensed in very small drops, which disappear on removing the 
 finger. One may, in this manner, ascertain that the cutaneous 
 perspiration varies in quantity in different parts of the surface of the 
 body ; for, on placing the back of the hand before a looking-glass, the 
 latter will be covered by no vapour. 
 
 No function of the animal economy has been the subject of more 
 investigation, nor has any excited the attention of more accurate and 
 indefatigable physicians, than the secretion now under consideration. 
 From the time of Sanctorius, who, in the beginning of the seventeenth 
 century, published in his immortal work, Medicina Statica, the 
 result of experiments carried on for thirty years, with a patience 
 which very few will imitate, to that of Lavoisier, who, jointly with 
 Seguin, aided by the resources of the improved state of chemistry, 
 instituted an examination of the insensible perspiration, we find 
 engaged in this inquiry, Dodart, who, in 1668, communicated to the 
 Academy of Sciences, which had been founded but a short time, the 
 result of his observations at Paris, under a climate different from that 
 of Venice, where Sanctorius lived: Keill, Robinson, and Rye, who 
 repeated the same experiments in England and Ireland: Linnings, 
 who performed his in South Carolina; and several physiologists of 
 no less merit, as Gorter, Hartmann, Arbuthnot, Takenius, Winslow, 
 'Haller, &c., who all aimed at ascertaining, with more precision than
 
 OF THE CUTANEOUS PERSPIRATION 229 
 
 had been done by Sanctorius, the variations in the cutaneous perspi- 
 ration, according to the climate, the season of the year, the age, the 
 sex, the state of health or disease, the hour of the day, and the 
 quantity of other secretions. 
 
 According to Sanctorius, of eight pounds of solid and liquid 
 aliments taken in twenty-four hours,, five were carried off by the 
 perspiration, and only three in excrement and urine. Haller conceives 
 this calculation to be exaggerated ; Dodart, however, carried it still 
 further, and maintained that the relation of the perspiration to the 
 solid excrements was as seven to one. 
 
 In France, and in temperate climates, the quantity of the cuta- 
 neous perspiration and of the urine is nearly the same; it may be 
 estimated at between two and four pounds in the twenty- four hours. 
 We perspire most in summer, and void most urine in winter. The 
 perspiration, like every other secretion, is in smaller quantity during 
 sleep than while we are awake ; in old age than during infancy ; in 
 weak persons, and in damp weather, than under the opposite 
 circumstances. 
 
 The perspiration may be said to be in a compound ratio of the force 
 with which the heart propels the blood into the minute capillary 
 arteries, of the vital energy of the cutaneous organ, and of the solvent 
 powers of the atmosphere. The strongest and most robust men 
 perspire most ; some parts of the skin perspire more than others, as the 
 palms of the hands, the soles of the feet, the arm-pits, &c. When the 
 air is warm, dry, and frequently renewed, cutaneous perspiration is 
 greater, and the necessity of taking liquid aliment is more urgent, and 
 more frequently experienced : in summer, as every body knows, a 
 profuse perspiration is brought on by passing from the heat of the sun 
 into the shade ; and on no occasion is a copious sweat more easily 
 brought on, than by taking exercise in summer, when, on the approach 
 of a storm, the atmosphere, containing a small quantity of vapours, 
 and warm from the rays of the sun, which shews itself now and then, 
 surrounded by the clouds, is little capable of dissolving the insensible 
 perspiration. 
 
 The skin may be covered with sweat, without any increase of the 
 cutaneous perspiration ; this may happen from dampness in the air, or 
 from its being imperfectly renewed. It must be owned, however, that 
 sweating is more frequently occasioned by an increase of the insensible 
 perspiration, and that the warmth of the bed which excitefit, acts by 
 increasing the power of the organs of circulation, and the energy of 
 the cutaneous system. The body is weakened by sweating, which is 
 seldom the case with the insensible perspiration. A profuse sweat is 
 attended with a very speedy exhaustion ; thus, in hectic fever, in the
 
 230 OF THE CUTANEOUS PERSPIRATION. 
 
 , suelte (sudor anglicus,} and other affections equally dangerous, it is 
 the cause of a wasting almost universally fatal. 
 
 The matter of the insensible perspiration, and of the sweat, is, in 
 great measure, aqueous. Like the urine, it holds in solution several 
 salts, also the volatilised recrementitiQus matter of animal substances, 
 sometimes even acids, as in the case in which Berthollet detected the 
 phosphoric acid in children affected with worms, in pregnant women, 
 in nurses, from whom there exhales an odour manifestly acid. It may 
 contain ammonia, and, on certain occasions, the smell enables us to 
 discover that alkali in the sweat or perspiration. 
 
 The air which constantly surrounds our body does not merely 
 dissolve the aqueous vapour which arises from it ; but several 
 physiologists very reasonably conjecture, that the oxygen of the at- 
 mosphere may combine with the carbon of the blood brought to the 
 skin by the numerous vessels which are sent to it, and likewise with 
 the gelatine forming the substance of the rete mucosum of Malpighi. 
 
 The experiments of Jurine, of Tingry, and of several other 
 naturalists, shew that carbonic acid is constantly formed* on the 
 surface of the skin, so that the skin may be considered as a supple- 
 mentary organ to that of respiration ; and in that point of view, one 
 may compare to it the mucous membranes which are in contact with 
 the atmospherical air in the nasal fos'sse, and in the intestinal canal 
 which they line. 
 
 The cutaneous perspiration "is, likewise, as was before mentioned, 
 a powerful means of cooling the body, and of keeping it, while living, 
 in a uniform temperature. The water which is exhaled from the whole 
 surface of the body, carries off from it, in passing into vapour, a 
 considerable quantity of caloric ; and it is observed, that every thing 
 which increases the production of caloric gives rise to a proportionate 
 increase of the cutaneous perspiration, and of the pulmonary ex- 
 halation ; so that a constant equilibrium being kept up between its 
 production and escape, the animal warmth always remains nearly the 
 
 * If transpiration be restrained or stopped, and if the causes productive of heat 
 act with intensity, it would appear that the temperature of the surface of the body 
 rises some degrees; hence the reason that the heat is so distressing in those 
 diseases which are characterised by diminished transpiration, and in which the 
 dryness of the skin is so remarkable, as erysipelas, erythema, &c. MM. Berger 
 and DelaiS^m have supposed that they have seen, when the air of a room is 
 saturated with humidity, and rendered very warm, that the human body exposed 
 to this atmosphere acquires a higher temperature than is natural to it; the 
 cutaneous and pulmonary transpiration either being altogether arrested, or im- 
 pei'fettly performed. For farther observations on this subject, see*ArpENDix, 
 Note 2 J. C.
 
 OF THE ANIMAL FLUIDS. 231 
 
 To conclude, the extremities of the nerves of our organs of 
 sensation are all moistened by a fluid varying in quantity, and which 
 maintains them in a softened state, favourable to the exercise of their 
 functions. It was likewise necessary that the membrane in which the 
 sense of touch resides should be habitually kept moist by a fluid that 
 should penetrate it throughout : this use of the insensible perspiration 
 is not less important than the preceding, on which physiologists have 
 bestowed most attention. 
 
 CHAPTER V. 
 
 OF THE SECRETIONS. 
 
 LXXXVIII. Of the Animal Fluids. LXXXIX. Of the Blood._XC. Of the 
 constituent Parts of the Blood XCI. Of the ultimate Elements of the 
 BkxxLXCII. Of the Changes in the Blood XCIII. Of the Transfusion of 
 Blood. XCIV. Of the Secretions._XCV. Of Arterial Exhalation or Trans. 
 
 udation XCVI. Of Secretion from Glandular Follicles XCVII. Of the 
 
 Secretions of Conglomerate Glands XCVIII. Of Accidental Secretions 
 
 XCIX. Of Nervous Influence on Secretion C. Of the Secretion of Synovia, 
 &c CI. Of the State of the Circulation in Secreting Organs CII. Of other 
 
 Glands CIII. Of the Secretion of Adeps CIV. Of the Use of the Fat 
 
 CV. Of the Secretion of the Marrow. 
 
 LXXXVIII. Of the animal fluids. The animal fluids were formerly 
 divided into recrementitious, excrementitious, and excremento-recremen- 
 titious : this division, founded on the uses to which the fluids are sub- 
 servient, is preferable to any that has since been adopted, and in which 
 they are ranked according to their nature. 
 
 The first class remain in the body, and are employed in its 
 nutrition and growth ; such as the chyle, the blood, the serosity which 
 lubricates the surface of the pleura, of the peritonaeum, and of the 
 other membranes of the same kind. The second kind are ejected 
 from our body, and cannot remain long within it without danger; 
 such as the urine, the matter of insensible perspiration and of sweat. 
 Lastly, those of the third class partake of the nature of the two 
 preceding, and are in part rejected, while another part is retained 
 and employed in the support and growth of the organ ; this is the 
 case with the saliva, the bile, the mucus of the intestines, &c. If one 
 affected to be very minutely scrupulous, one might consider all the 
 animal fluids as recremento-excrementitious. The chyle and the
 
 232 OF THE BLOOD. 
 
 blood, which are so very nutritious, contain an abundance of he- 
 terogeneous and excrementitious parts; the urine, which of all our 
 fluids is that which may, with most propriety, be termed such, 
 contains likewise aqueous parts, which, while it remains in the bladder, 
 the lymphatics absorb and carry into the mass of the fluids. 
 
 Of all the modern divisions, Fourcroy's is the best ; Vicq-d'Azyr 
 acknowledged its superiority over that proposed by Haller in his 
 Physiology. Fourcroy admits six classes of fluids: 1st, those which 
 hold salts in solution, as the sweat and urine, he gives the name of 
 saline to such fluids ; 2d, inflammable oily fluids, all possessing a 
 certain degree of consistence and concrescibility, as fat, and the 
 cerumen of the ears, &c. ; 3d, the saponaceous fluids, as the bile and 
 milk ; 4th, the mucous fluids, as those which lubricate the internal coat 
 of the intestinal canal; 5th, the albuminous fluids, among which one 
 may rank the serum of the blood ; 6th, thejibrinous fluids, containing 
 fibrina, as the fluid last mentioned.* 
 
 In proportion as we advance in our knowledge of animal chemistry, 
 the defects of these divisions become more and more evident. In 
 short, the animal fluids are so compound, that there is not one which 
 does not, at once, belong to several of these classes, and whose 
 prevailing element is not sometimes exceeded in quantity by materials 
 which commonly 'form but a small part of them. 
 
 LXXXIX. Of the blood. The blood is the reservoir and the 
 common source of the fluids ; these do not exist in the blood, with the 
 qualities which characterise them, unless, after having been previously 
 formed by the secretory organs, they have been absorbed by the 
 lymphatics, and conveyed, with the chyle and lymph, into the 
 circulatory system. Let us shortly attend to its nature, although this 
 belongs more especially to tne department of chemistry. The blood is 
 red in man and in all warm-blooded animals, and even in some whose 
 temperature is not very different from that of the atmosphere, as in 
 fishes and reptiles. This colour, of a deeper or lighter shade, 
 according as the blood is drawn from an artery or a vein, varies in its 
 degree of intensity according to the state of health or weakness. It is 
 of a deep red in strong and active persons, pale and colourless in 
 
 * Berzelius distinguishes the fluids formed from the hlood into secretions, 
 properly so called, and excretions, or those which are directly discharged from the 
 body. The former are destined to perform a farther office in the animal economy 
 all of these are alkaline; they are the bile, the saliva, and the fluid, which is 
 secreted on the mucous and serous surfaces. In the latter division acids pre- 
 dominate: the excretory fluids embrace the urine, the cutaneous and pulmonary 
 transpiration, and the milk. Magendie divides the secretions into exhalations, 
 follicular secretions, and glandular secretions. See APPENDIX, Note A A, for 
 farther observations on this subject. J. C.
 
 OF THE BLOOD. 233 
 
 dropsical patients, and whenever the health is weak. By its colour, 
 one may judge of all its other qualities. Its viscidity is greater, its 
 saline taste more marked, its peculiar smell stronger, when its colour 
 is deep. This colour is produced by a prodigious number of globular 
 molecules, which move and float in an aqueous and very liquid fluid. 
 When the blood is pale, the number of these molecules diminishes : 
 they seem to be dissolved in cachexise. 
 
 Does the microscope, which affords the only method of perceiving 
 them, enable one to determine their bulk and their figure ? Sir E. Home 
 considers the red particles to be 3-^77 of an inch in diameter. Leeu- 
 wenhoek, who brought forward the idea of their being so minute, by 
 his calculation that they were one millionth part of an inch in size, 
 thought them spherical. Hewson says they are annular, and have an 
 opening in their centre. Others compare them to a flattened lentil, 
 with a dark spot in the middle. They are solid, and formed by a nucleus 
 or red point, covered over by a membranous vesicle, which appears to 
 be readily formed and destroyed.* 
 
 XC. The constituent parts of the blood. The blood, when no 
 longer in the course of the circulation, and on being received into a vessel, 
 parts with its caloric, and exhales at the same time a powerful smell, a 
 gas to which, according to some physiologists, (Moscati, Rosa, &c.) it 
 owes its vital properties, and the absence of which is attended with a 
 loss of its vitality ; so that its analysis cannot furnish facts applicable 
 to the explanation of the phenomena of health and disease. This 
 odour, extremely strong in carnivorous animals, is very distinguishable 
 in man, especially in arterial blood. I remember retaining it a whole 
 day in my throat, after removing the dressings, and suppressing a 
 haemorrhage occasioned by a relaxation of the ligatures, a week after 
 the operation for popliteal aneurism. Unless the blood is prevented by 
 agitation from coagulating as it cools, its consistence increases, and on 
 being laid by, it separates into two very different parts, the one aqueous, 
 more or less red, heavier than common water, and evidently saltish ; 
 this is called the serum, consisting of water, in which are dissolved 
 albumen, gelatine, soda, phosphates and muriates of soda, nitrate of 
 potash, and muriate of lime. 
 
 Serum, though bearing some analogy to the albumen of egg, differs 
 from it, in forming, on coagulating, a less solid and less homogeneous 
 mass. The albumen is evidently mixed with a portion of transparent 
 gelatine, not coagulable by heat. Albumen has so great an attraction 
 for oxygen, that it is fair to presume that the. serum absorbs oxygen 
 and combines with it, through the very thin parietes of the air-cells of 
 the lungs, aud that it gives to arterial blood that spumous appearance 
 
 * See the APPENDIX, Note B B.
 
 234 OF THE BLOOD. 
 
 which is one of its distinguishing characters. This oxidisement, and 
 the fixation of the caloric which accompanies it, equally increase its 
 consistence. It does not, however, coagulate, because it is kept in 
 perpetual motion by the circulatory action, and is diluted by a sufficient 
 quantity of water; because the animal temperature, which never 
 exceeds thirty-two or thirty-four degrees, cannot give a solid form to 
 albumen, which coagulates only at fifty degrees of Reaumur's thermo- 
 meter ; and lastly, because as serum contains a certain quantity of 
 uncombined soda, which enables it to turn green vegetable blues, 
 this alkali concurs in keeping the albumen in a dissolved state, which 
 it renders fluid when it has been coagulated by the acids, by heat, or 
 by alcohol. 
 
 Amid the serum, and on its surface, there floats a red cake, spungy 
 and solid (insula rubra), which, by repeated washing, may be separated 
 into two very distinct parts. The one is the cruor, or the colouring 
 matter, which mixes with the water ; it is a more highly oxygenated 
 and more concrescible albumen than that of the serum ; it holds in 
 solution soda, as well as phosphate of iron, with an excess of iron.* 
 The other is a solid and fibrous substance, which, after being re- 
 peatedly washed, has the appearance of felt, the filaments of. which 
 cross each other, are extensible, and very elastic. This third part of 
 the blood is called Jibrina ; it is very similar in its nature to muscular 
 fibre, and, like it, gives out, on distillation, a considerable quantity of 
 carbonate of ammonia. Fibrina does not exist in the blood in a solid 
 form, but in a state of solution, and combined with the other consti- 
 tuent parts of the fluid, as is indicated by the appropriate expression 
 of liquid flesh (chair coulante), first used by Bordeu in speaking of the 
 blood. 
 
 * It is a more oxygenated and a more coagulable albumen than that of the 
 serum. The colouring part of the blood, when incinerated, after giving off a con- 
 siderable quantity of ammonia during the combustion, leaves ashes which, accord- 
 ing to Berzelius, are only a hundredth part of its weight, and which contain 55 
 parts of the oxide of iron, 8 of the phosphate of lime, a little of magnesia, 17^ parts 
 of lime, and 16^ of carbonic acid. The oxide of iron is neither found in the ashes 
 of the coagulable part of the serum, nor in those of the fibrine. Berzelius, however, 
 further informs us, that the serum, although able to dissolve a small portion of 
 the oxides of iron, but not of its phosphates, does not acquire a red colour by this 
 weak solution, and that he has neither detected iron nor lime in the entire blood, 
 although both are so abundant in its ashes. He therefore concludes, that the 
 blood contains the elements only of the phosphate of iron, and of lime and mag- 
 nesia, and of the carbonate of lime, united very differently from their combination in 
 these salts. Nor is it unlikely that these salts are formed during incineration, 
 from the presence of the elements of their respective bases, the other elements being 
 furnished during incineration. The existence" of iron in the colouring particles 
 of the blood, and its absence from the serum, have been continued by the recent 
 experiments of several chemists on the continent J. C.
 
 OF THE ELEMENTS OF THE BLOOD. 235 
 
 XCI. Of the ultimate elements of the blood. If the blood be 
 exposed to the action of fire, if it be calcined and reduced to powder, 
 and if this pulverised substance be exposed to a magnet, the pre- 
 sence of iron will be manifestly seen by the magnetic attraction. 
 Authors do not agree in their accounts of the quantity of iron con- 
 tained in the blood. Menghini says there is one part in the hundred; 
 others that it is in the proportion of 1 to 303 ; so that it is pro- 
 bable that this constituent principle of the blood, like all the mate- 
 rials of our fluids, may vary in quantity according to different cir- 
 cumstances. 
 
 Blumenbach justly observes, that iron is found only in calcined 
 blood ; that none is to be found if it be slowly dried. This peculiarity 
 is no longer surprising, since M. Fourcroy has shewn that iron existed 
 in the- blood, in combination with the phosphoric acid, and formed with 
 that acid a phosphate of iron, with an excess of its base. This salt 
 becomes decomposed by calcination, the iron is set free, and is acted 
 upon by the magnet. Physiologists attribute the colour of the blood 
 to the presence of the oxide of iron in that fluid. 
 
 It has been the received opinion, that the red colour of the blood is 
 owing to the presence of phosphate of iron, which being conveyed of a 
 white, colour into the blood, along with the chyle, meets with the pure 
 soda, by which it is dissolved, and from which it receives its colour ; the 
 colour of the blood is likewise owing to the oxidisement of the metal- 
 lic portion, which is in very considerable quantity in that salt. This 
 solution of the phosphate of iron by soda, the oxidisement of the excess 
 of iron, and the absorption of oxygen by albumen, constitute, in an 
 especial manner, hematosis or sanguification, which is principally carried 
 on in the lungs. 
 
 This opinion of Fourcroy respecting the source whence the blood 
 acquires its red colour, has, since his time, been adopted by some, and 
 combated by other, physiologists. It is now entirely abandoned, 
 because it is known that the colouring part of this fluid may be 
 obtained separately, and entirely exempt from iron. This colouring 
 portion of the blood, according to M. Vauquelin, does not change its 
 colour when tested with gallic acid, a farther proof that it contains no 
 iron.* 
 
 The respective proportion of the three parts into which the blood 
 separates spontaneously, varies considerably. The serum constitutes 
 about one-half or three-fourths of the fluid ; the colouring matter and 
 
 * Since the time of Fourcroy, chemists have differed widely respecting the pre- 
 sence of iron in the red particles of the blood. The recent researches, however, of 
 some continental inquirers seem to have settled the question in. the affirmative. 
 See APPENDIX, Note BB. </. C. 
 
 kctc< 
 !'JJ ^V . v-
 
 236 OF THE CHANGES IN THE BLOOD. 
 
 fibrina are in inverse ratio of the serum ; and it is observed, that the 
 more brilliant and red the colour of the blood, the greater the proportion of 
 the fibrous part. The pale, aqueous, and colourless blood of a dropsical 
 patient contains very little fibrina. In putrid or adynamic fever, in 
 which bleeding, as is universally known> is improper, I have sometimes 
 seen the blood containing but a small portion of fibrina, and very slow 
 of coagulating ; its texture seemed to suffer from the affection under 
 which the muscular organs were evidently labouring. In inflammatory 
 diseases, on the contrary, the plastic power of the blood is augmented, 
 the fibrina is in greater quantity, even the albumen coagulates spon- 
 taneously, and forms a crust above the serum, which is always in smaller 
 quantity.* 
 
 XCII. Of the changes in the blood. The fluids not only undergo 
 changes in their composition, in their qualities and nature, when the 
 action of the solids is itself altered, but even the absorbent system may 
 introduce into the mass of our fluids heterogeneous principles, evi- 
 dently the cause of several diseases. In this manner, all contagions 
 spread, the virus of small-pox, of syphilis, of the plague, &c. Thus, in 
 time, the habitual use of the same aliment produces in our fluids a crasis 
 or peculiar constitution, which has on organised solids an influence 
 acting even on the mind. 
 
 A purely vegetable diet conveys into the blood, according to Pytha- 
 goras, bland and mild principles: this fluid excites the organs in a 
 moderate degree, and this check over the physical excitement facilitates 
 the observance of the laws of temperance, the original source of all 
 virtues. These observations of ancient philosophy on the influence of 
 regimen have, doubtless, led their authors to exaggerated inferences ; 
 but they should not be considered as altogether unsupported. "The 
 carnivorous species are marked by their strength, their courage, and 
 their ferocity; savages who live by hunting, and who feed on raw, 
 bloody, and palpitating flesh, are the most ferocious of men ; and in 
 our own country, in the midst of those scenes of horror which we have 
 witnessed, and from which we have suffered, it was observed that 
 butchers were foremost in the massacres, and in all the acts of atrocity 
 and barbarity. I know that this fact, which was uniformly noticed, 
 has been explained by saying that the habit of slaying animals had 
 familiarised them to shed human blood. But though I do not deny the 
 existence of this moral cause, which certainly operates, I think I may 
 
 * According to Mr. Brande and Sir E. Home, both venous and arterial blood 
 contain carbonic acid in the proportion of two cubic inches of the gas for each ounce 
 of blood. This acid disengages itself immediately when a portion of the warm 
 Mood is placed in an air-pump. Dr. Davy has, however, recently contended tliat 
 the blood contains little or no carbonic acid. See APPENDIX, Note BB, for farther 
 remarks respecting the Blood.
 
 OF THE CHANGES IN THE BLOOD. 237 
 
 add to it as a physical cause, the daily and plentiful use of animal 
 food, and the breathing an air filled with emanations of the same kind, 
 which contributes to their embonpoint, which is sometimes excessive. 
 
 As the plasticity and concrescibility of the blood are diminished in 
 asthenic diseases, or of debility, as putrid fevers and scurvy, two causes 
 may be assigned for the haemorrhages which come on in those diseases, 
 viz. the relaxed state of the vessels, and the dissolution of the blood. 
 In scurvy the tissue of the capillaries is relaxed, its meshes enlarged, 
 red blood passes into them, transudes through their parietes, and forms 
 scorbutic spots. I have sometimes seen those ecchymoses or sangui- 
 neous cutaneous transudations extend under the skin of the whole of 
 one lower extremity. Petechiee, in putrid fever, are formed in the same 
 manner, and depend, likewise, on the relaxation of the minute vessels, 
 and on the greater fluidity of the blood, whose molecules are less 
 coherent, and more readily separated from each other. 
 
 In the summer of the year 1801 I amputated the arm of an old man 
 of sixty, on account of a corroding and varicose ulcer, which for thirty 
 years had occupied a part of the fore arm, and extended to the elbow. 
 All who were present at this operation observed that the blood which 
 flowed from the arteries was not nearly so red as that from the arteries 
 of a young man, whose thigh had just been taken off on account of a 
 scrofulous caries of the leg ; that the venous blood was entirely dis- 
 solved, purple, and similar to a weak dye of logwood. The blood did 
 not coagulate like that of the young man ; it became fluid, and was 
 converted into a serum, containing a few colourless clots. 
 
 Those who have endeavoured to find in the changes undergone by 
 the blood and the other fluids, the cause of all diseases, have fallen into 
 as serious blunders as the determined solidists, who maintain that all 
 diseases arise from a deranged condition of the solids, and that every 
 change in the condition of the fluids is a consequence of that derange- 
 ment. The believers in the humoral pathology have certainly gone too 
 far ; they have admitted that the animal fluids might be acid, alkales- 
 cent, or acrimonious, while we have no proof whatever that they ever do 
 undergo such changes. The solidists have, likewise, gone much beyond 
 the truth, in saying that every primitive change in the condition of .the 
 fluids is imaginary, and that the doctrine of humoral pathology is 
 without foundation. Stahl relates* that the blood of a young woman, 
 who was bled during a fit of epilepsy, was absolutely coagulated, as if 
 that fluid had partaken in the rigidity affecting the muscular organs. 
 Some authors say they have met with the same appearance ; I have, 
 however, never been able to discover any sensible difference between the 
 
 * Theoria Medico, Vera, p. G78.
 
 238 OF THE TRANSFUSION OF BLOOD. 
 
 blood of an epileptic patient and of any other person of the same con- 
 stitution, of the same age, and living on the same regimen ; and it 
 should be considered, t\\ at to make a just comparison of our fluids, it 
 is necessary that every thing should be v alike in the persons from whom 
 they are taken, with the exception of the difference of which we are to 
 judge. In fact, the blood has not the same appearance, and does not 
 coagulate in the same manner, when taken from a child, a woman, or 
 an old man ; from a man who lives abstemiously, or from one who lives 
 on a full diet. 
 
 After enumerating the changes which the blood undergoes, one 
 might speak of those which affect the fluids that are formed from it, 
 one might attend to the greenish, leek colour, and sometimes even 
 darkish appearance of the bile, which is not always of the same degree 
 of bitterness ; the limpid state of the urine, which is voided colourless, 
 without smell or flavour, after a fright, or during the convulsive fits of 
 hysterical women ; the foetid smell and the viscidity of the saliva, when 
 the salivary glands are under mercurial influence ; the milky state of 
 the serum which lubricates the parietes of the abdomen, and of the 
 viscera which it contains after inflammation of the peritonaeum ; 
 changes which almost universally depend on a derangement of action 
 in the secretory organ, and sometimes, likewise, on the general condi- 
 tion of the fluids ; for a gland cannot secrete a fluid endowed with the 
 qualities which peculiarly belong to it, unless the blood furnish it with 
 the materials of secretion, and unless it be in a state to bring about a 
 due combination of their particles. When we come to the article 
 of accidental secretions, we shall speak of some of those disorders of 
 the fluids depending on a depraved condition of the secretory organs.* 
 
 XCIII. Of the transfusion of blood. In the midst of the disputes 
 to which the discovery of the circulation gave rise, some physicians 
 conceived the idea of renovating completely the whole mass of the fluids 
 in persons in whom they might be vitiated, by filling their vessels with 
 the blood of an animal, or of a person in good health. Richard Lower, 
 known by his work on the heart, first practised it on dogs, in 1665. 
 Two years afterwards, transfusion was performed at Paris on men : it 
 excited the greatest expectations : it was thought that by this process, 
 called transfusive surgery (chirurgie transfusiore), all remedies would 
 be superseded ; that henceforth, to cure the most serious and inveterate 
 diseases, it would be necessary merely to transfuse the blood of a strong 
 and healthy man into the veins of the diseased ; nay, they went so far 
 as actually to imagine they might realise the fabulous fountain of 
 
 * For additional remarks on the changes observed, under various circumstances, 
 in the condition of the Blood, see APPENDIX, Note B B. J. C,
 
 Of THE TRANSFUSSON OF BLOOD. 233 
 
 Jouvence ; they expected no less than to restore youthful vigour to the 
 old, by infusing into them the blood of the young, and thus to perpe- 
 "tuate life. All these brilliant chimeras soon vanished ; some under- 
 went the experiment without any remarkable effects from it, others were 
 affected with the most violent delirium ; a lad of fifteen lost his senses, 
 after suffering two months from the most violent fever. The legis- 
 lative authority at last interfered, and prohibited those dangerous 
 experiments. 
 
 The experiments on the subject of the transfusion of blood were 
 repeated, but without success, at the Academy of Sciences. Perault 
 opposed this new method, and shewed that it was very difficult for one 
 animal to exist on the blood of another ; that this fluid, though appa- 
 rently the same in animals of the same age, was as different from it as 
 the features of their face, their temper, &c. ; that an extraneous fluid 
 was thus introduced, which conveying to the organs an irritation to 
 which they were not accustomed, must disorder their action in various 
 ways ; that if, as an objection to what he had said, they should bring for- 
 ward what takes place in grafting, in which the sap of one tree nourishes 
 another of a different kind, he would answer, that vegetation does 
 not depend on so complicated or on so delicate a mechanism as the 
 nutrition of animals ; that a hut may be formed of all kinds of stones 
 taken at random, but that to build a palace stones must be designedly 
 shaped for the purpose, so that a stone destined for an arch will not do 
 for a wall, or even for another arch.* 
 
 It would be easy, by means of a curved tube, to transfuse the 
 arterial blood of an animal, from a wound in its carotid artery, 
 into the saphena vein of a man, into the internal jugular, or into 
 some of the cutaneous veins of the fore arm ; but it is to be presumed, 
 from experiments on living animals, that it would be very difficult 
 to transfuse blood into the arteries, as these vessels, filled with blood 
 during life, do not yield to a greater distension. The capillaries, in 
 which the arteries terminate, become corrugated, and refuse to 
 transmit a fluid 'which does not act upon them according to their 
 wonted sensibility. Such was the result of the experiments of Pro- 
 fessor Buniva : he observed in a living calf, that the vessels did not 
 transmit freely the fluid which was forced into them till the instant 
 when the animal was killed, by dividing the upper part of the spinal 
 marrow. Attempts have been made to turn to useful purposes these 
 experiments on transfusion, by limiting the process to the injecting of 
 medicinal substances into the veins. It is singular, that the mo- 
 ment a fluid is injected into the veins of an animal, it endeavours to 
 perform motions of deglutition, as if the substance had been taken in 
 
 * Acad6mie Royale des Sciences, p. 37-
 
 240 OF THE ARTERIAL EXHALATION. 
 
 at the mouth. All these attempts have been too few in number, and 
 are not sufficiently authenticated, to justify their application to the 
 human subject. But there is every reason to believe, that, even 
 with the utmost care, the life of those who should submit to them 
 would be endangered ; so that it is at once humane and prudent to 
 abstain from them. * 
 
 XCIV. Of the secretions. It has been said in too general a 
 way, that the organs receive from the blood conveyed to them by 
 the arteries, the materials of the fluids which they separate from it. 
 We have seen that the liver is a remarkable exception to this general 
 rule. 
 
 One is, therefore, justified in saying that the elements of our fluids 
 may be furnished by vessels of every kind, to the organs in which 
 such fluids may be elaborated. The term secretion, whatever its 
 etymology may be, denotes that function by which an organ separates 
 from the blood the materials of a substance which does not exist 
 in that fluid with its characteristic qualities. By the term secre- 
 tion, one should not, therefore, understand the mere separation 
 of a fluid existing before the action of the organ by which it is 
 prepared. 
 
 XC V. Of arterial exhalation. The differences between the se- 
 creted fluids are evidently connected with those of the organs em- 
 ployed in their formation. Thus, the arterial exhalation which takes 
 place throughout the whole extent of the internal surfaces maintains 
 their contiguity, throws out an albuminous serosity, which is merely 
 the serum of the blood slightly changed by the feeble action of a 
 very simple organisation. The analysis of the fluid of dropsy, which is 
 merely the serosity constantly transuding from the surface of the serous 
 membranes, as the pleura and peritonaeum, shews, that it bears the 
 strongest resemblance to the serum of the blood, and that it differs 
 from it only in the varying proportions of albumen and of the different 
 salts which it holds in solution. 
 
 This first kind of secretion, this perspiratory transudation, would 
 seem to be a mere filtration, through the pores of the arteries, of a 
 fluid already formed in the blood. There is, however, besides, an 
 inherent action in the membranes whose surface it continually lubri- 
 cates. If it were not for this action, the serum would remain united to 
 the other constituent parts of the fluid, which is in too much motion, 
 and at too high a temperature, to allow of a spontaneous separation. 
 The term exhalation, which is applied to this secretion, gives an in- 
 correct idea of it; for exhalation, which is a purely physical phenomenon, 
 
 * See APPENDIX, Note B B, for some remarks on transfusion, and on the 
 injection of medicinal substances into the veins. J. C.
 
 
 Otf THE FOLLICULAR SECRETIONS. 241 
 
 and requiring the presence of air to dissolve the fluid that is ex- 
 haling, cannot take place from surfaces that are in absolute contact, 
 and between which there is no interval. The character of this mode 
 of secretion is the absence of any intermediate substance between 
 the vasa afferentia and the excretory ducts ; the minute arteries and 
 veins which enter into the structure of the membranes, being at once 
 both the one and the other. The fluid secreted by the serous 
 membranes, though bearing a considerable analogy to the serum of 
 the blood, differs from it, however, by being animalised in a greater 
 degree. The most important function of these organs is, therefore, 
 that they concur in the common process of assimilation : the office, 
 which has long been assigned to them, of facilitating the motion of 
 the organs which they envelope, by lubricating their surface, will 
 appear to be of very secondary importance, if it be considered, that 
 respiration is not impeded by adhesions between the lungs and the 
 pleura, and that, besides, the brain, which, when the cranium is 
 whole, is completely motionless, is entirely surrounded by a serous 
 membrane. 
 
 XCVI. Of secretion from glandular follicles. Next in order to 
 the serous transudation, which requires a very simple organisation, 
 comes the secretion which takes place in the cryptee, in the glan- 
 dular follicles, and in the mucous lacunae. Each of these small glands, 
 contained within the membranes lining the digestive canal, the air 
 tubes, and the urinary passages, and the collection of which forms 
 the amygdalae, the arytsenoid glands, &c. may be compared to a small 
 bottle, with a round bottom and a very short neck : the membranous 
 parietes of these vesicular cryptee receive a considerable number of 
 vessels and nerves. The peculiar action of the parietes of these dif- 
 ferent parts determines the secretion of the mucus furnished by those 
 glands. These mucous fluids, less liquid and more viscid than the 
 serosity which is the product of the first mode of secretion, contain 
 more albumen and a greater number of salts, differ still more from the 
 serum of the blood, are more animalised, and are of a more excre- 
 mentitious nature. 
 
 The bottom of these utricular glandulse is turned towards the parts 
 to which the mucous membranes adhere; and their mouth or neck 
 opens on the free or unattached surface of those membranes. These 
 kinds of excretory ducts, which are wider or narrower, and always very 
 short, sometimes unite, run into each other, and open within the cavities. 
 These common orifices, at which several mucous glands empty them- 
 selves, are easily seen on the amygdalae, towards the mucous lacunae 
 of the rectum and of the urethra, at the base of the tongue, &c. 
 The albuminous fluid, which is poured within those glandular cryptae, 
 remains some time within the cavity, and becomes thicker, from the
 
 242 SECRETIONS OF CONGLOMERATE GLAXDS. 
 
 absorption of its more fluid parts ; for there are, likewise, lymphatics 
 within the texture of their parietes. When the surfaces on which they 
 are situated require to be moistened, this small pouch contracts and 
 throws up the fluid with which it is filled. The secretion and ex- 
 cretion are promoted by the irritation which the presence of the 
 air, of the aliment, or of the urine, occasions, by the compression 
 exerted by those substances, and, lastly, by the peristaltic contractions 
 of the muscular planes to which the mucous membranes adhere 
 throughout the whole extent of the digestive tube. 
 
 XCVII. Secretions of conglomerate glands. Those fluids which 
 differ much from the blood, require for their secretion organs of a 
 more complicated nature ; such organs are called conglomerate glands, 
 to distinguish them from the lymphatic glands, which have been 
 termed conglobate. Those glands constitute the viscera, and are 
 formed by a number of nerves and vessels of all kinds, arranged in 
 fasciculi, and united by cellular membrane. A membrane peculiar 
 to the organs, or supplied by those which line the cavities in which 
 they are contained, covers their outer part, and insulates them from the 
 neighbouring organs. 
 
 The intimate arrangement of the different parts which form the 
 secretory glands, the disposition of the arteries, of the veins and 
 nerves, and the manner in which the lymphatic and excretory ducts 
 arise from them, has given rise to endless discussions, and formed the 
 basis of former physiological theories. What' follows may be con- 
 sidered as a correct abstract of what is known on the subject. 
 
 The respective arrangement of the similar parts (parties similaires*) 
 which enter into the structure of the glands, and which form their 
 proper substance, or parenchyma, f is different in each of them : this 
 explains their differences in the double relation of their properties and 
 their uses. The arteries are not, as Ruysch thought, immediately 
 continuous with the excretory ducts, nor are there immediate glands 
 between those vessels, as Malpighi conceived. It seems more pro- 
 bable that each gland has its own peculiar cellular or parenchyma- 
 tous tissue, in the areolee of which the arteries pour the materials of 
 
 By parties similaires, the author means the simple elementary tissues. See 
 the Preliminary Discourse. 
 
 f Do the different appearances of the substance of glandular bodies depend on 
 the different manner in which the similar parts cross each other, and on their differ, 
 erit proportions in each kind of gland ? or do these differences of colour, of density, by 
 means of which we so readily distinguish the substance of the liver from that of the 
 salivary glands, depend on the existence of a peculiar tissue in each organ ? This 
 question cannot be answered in the present state of anatomy. The opinion, how. 
 ever, which supposes the different nature of the glands to depend on the different 
 proportions of those constituent parts in each of them, appears the most probable.
 
 OF THE SECHETIONS. 243 
 
 the fluid which the gland prepares, in virtue of a power which is 
 inherent to it, and which is its distinguishing character. The lym- 
 phatics and the excretory ducts arise from the parietes of those 
 cells, and these two kinds of vessels absorb; the one set, the se- 
 creted fluid, which they carry to the reservoirs in which it accumu- 
 lates ; while the other set take up that part of the fluid on which 
 the organ has not completed its action in other words, the residue of 
 secretion. 
 
 XCVIII. Of accidental secretions. If one wished to extend the 
 idea attached to the term secretion, one might say that every thing 
 in the living economy is performed by means of the secretions. What 
 is digestion but the separation or secretion of the chylous or nutritive 
 parts of aliments from their faecal or excrementitious portion ? Do 
 not the absorbents concur in this secretion ? May they not be con- 
 sidered as the excretory ducts of the digestive organs, which act on 
 the aliment in the same manner as a secretory gland acts on the 
 blood that contains the materials of the fluid to be elaborated ? 
 Respiration, as we have already seen, is but a double secretion which 
 the lungs perform, on the one hand, of the oxygen contained in the 
 atmospherical air ; and, on the other hand, of the hydrogen and 
 carbon, of the water, and of the other heterogeneous principles 
 contained in venous blood; and, as will be shewn in the ensuing 
 chapter, nutrition is but a peculiar mode of secretion, which is dif-. 
 ferent in every organ. It is, therefore, only after a series of very 
 delicate and very complicated separations and analyses, that the or- 
 gans are enabled to make extraneous substances undergo such a 
 change of composition as to render them fit for their growth and 
 reparation . 
 
 There is every reason to believe, that the phenomena of sensation 
 and of motion, by means of which man keeps up with surrounding 
 objects the relations necessary to his existence, are the result of the 
 secretions of which the blood furnishes the materials prepared by the 
 brain, by the nerves, by the muscles, &c. A plant separates from 
 the earth, in which its roots are buried, the juices that it requires ; 
 these juices constitute the sap, which, after being filtered through 9. 
 multitude of canals, supplies the different secretions, whose products 
 are leaves, blossoms, and fruits, with gums, essential oils, and acids. 
 All organised bodies are, therefore, so many laboratories, in which 
 numerous instruments spontaneously perform various compositions, 
 decompositions, syntheses, analyses, which may be considered as so 
 many secretions from the common fluid. 
 
 If we confine ourselves in our view of the subject, and limit our 
 attention to man, the principal and almost the sole object of our 
 study, we shall see that the different secretions that may take place
 
 244 OF THE SECRETIONS. 
 
 in him are extremely numerous and varied, and that a change in 
 the condition of one of his organs is sufficient to enable it to secrete a 
 new fluid. Hence inflammation in any gland is sufficient to alter the 
 secretion of the organ that is affected. A portion of adipose tissue, 
 on being affected with inflammation, shall secrete, instead of fat, 
 a whitish fluid, known by the name of pus ; the pituitary membrane, 
 when inflamed, furnishes a mucus more fluid and more abundant, 
 and which, by degrees, returns to its natural state, in proportion as 
 the coryza goes off"; the serous membranes, as the pleura and the 
 peritonseum, will allow a greater quantity of serum of a more albu- 
 minous quality, sometimes even coagulable lymph, to exude. At other 
 times, inflammation causes an adhesion of their contiguous surfaces, 
 and as the inflammatory state varies in intensity, the accidental 
 secretion will likewise vary as to its qualities ; thus, the phlegmonoui 
 inflammation, which should furnish, on terminating in suppuration, 
 a whitish fluid, thick, consistent, and almost without smell, will 
 give out, if the process is not sufficiently active, a serous pus, colour- 
 less, and without consistence, &c. For the same reason, the blood- 
 vessels of the uterus pour out in some women a dark-coloured blood, 
 while in others they give out a mere serosity, very slightly, if at all, 
 tinged with blood. 
 
 The menstrual discharge in women is the product of a real secre- 
 tion of the arterial capillaries of the uterus, in the same manner 
 as those vessels in the pituitary membrane, the membrane which 
 lines the bronchia, the stomach, the intestines, the bladder, &c. pour 
 out blood abundantly, or allow its transudation, when irritation is deter- 
 mined to those parts ; as in haemorrhage from the nose, in bleeding 
 from the lungs, or from the stomach, when the vessels are not rup- 
 tured by external violence. Apoplexy itself, whether sanguineous or 
 serous, may, in several instances, be ranked amongst those secretory 
 evacuations, the quality of which varies according to the energy of 
 the capillaries which produce it. On opening dead bodies, one fre- 
 quently meets with a collection of blood in the ventricles of the brain 
 in persons who have died from apoplexy; yet the most careful examin- 
 ation does not enable one to detect the slightest laceration or rupture 
 in the veins, or in the arteries within the skull. 
 
 XCIX. Of nervous influence on secretion. The nerves, of which 
 there is always a certain number in the structure of the secretory 
 organs, and which are principally branches of the great sympathetic* 
 nerves, terminating in various ways in their substance, give to each 
 
 * They are likewise given off in great numbers from the cerebral ; thus, the 
 salivary glands receive from the seventh pair, from the maxillary nerve, from the 
 fifth pair, and from the cervical nerves, a number of nerves that will appear very 
 great, if the bulk of those glands is considered J. C.
 
 OF THE SECRETIONS. 245 
 
 of them a peculiar sensibility, by means of which they discover, in the 
 blood which the vessels bring to them, the materials of the fluid 
 they are destined to secrete, and these they appropriate to themselves 
 by a real selection. Besides, the nerves communicate to them a 
 peculiar mode of activity, the exercise of which makes those separated 
 elements undergo a peculiar composition, and bestows on the fluid 
 which is the product of it, specific qualities, always bearing a certain 
 relation to the mode of action of which it is the result. Thus, the 
 liver seizes the materials of the bile contained in the blood of the vena 
 portae, elaborates, combines those materials, and converts them into 
 bile, an animal fluid, distinguishable by peculiar characteristic pro- 
 perties, subject to certain variations, according as the blood contains, 
 in different proportions, the elements of which it is formed ; and accord- 
 ing as the gland is more or less disposed to retain them, and blend 
 them together. The qualities of the bile, depending on a concurrence 
 of all these circumstances, must present as many differences as the 
 blood which contains its elements, and the liver, may present varieties, 
 with regard to the composition of the former, and to the activity of 
 the latter. Hence the many changes in the qualities of the fluid, the 
 slightest of which, not affecting the health, escape observation ; while 
 those changes which are greater, and which disorder the natural 
 order of the functions, shew themselves in diseases of which they 
 may be considered as the effect, and at other times as the cause. 
 These changes in the condition of the bile (and what is now said 
 applies to almost all the secretions of the animal economy), are never 
 carried so far as to make the bile lose all its distinguishing charac- 
 ters; it never takes on the qualities belonging to another fluid, it 
 never resembles semen, urine, or saliva. 
 
 The secretory glands do not carry on an uninterrupted action ; 
 almost all of them are subject to alternate action and repose ; all, 
 as Bordeu observed, sleep or waken when irritation affects them or their 
 neighbouring parts, and determines their immediate or sympathetic 
 action. Thus, the saliva is more plentifully secreted during mastica- 
 tion, and the gastric juice is poured within the stomach only while diges- 
 tion is going on ; when the stomach is emptied of food, the secretion 
 ceases, and is renewed when the presence of food again excites a 
 sufficient degree of irritation. The bile flows more abundantly, and 
 the gall-bladder frees itself more readily of that which it contains, while 
 the duodenum is filled by the chymous mass. 
 
 When a secretory organ is in action, it determines the motion of 
 the parts in its vicinity, or, as Bordeu expresses it, within its atmo- 
 sphere. A part is said to belong to the department of a certain gland, 
 when it partakes in the motion affecting the latter during the process 
 of secretion, or when it is employed in functions subservient to that
 
 246 OF THE SECRETIONS. 
 
 of the gland : these departments are of different extent, according to 
 the importance of the action of the gland. Thus, one may say that 
 the spleen, and most of the viscera of the abdomen, are of the depart- 
 ment of the liver, since they receive from it the blood on which they 
 are to act. The liver is also comprised in the sphere of activity of the 
 duodenum, since the distension of that intestine irritates it, and deter- 
 mines a more copious flow of its fluids, and a more abundant secre- 
 tion of bile. 
 
 C. Of the secretion of synovia, fyc. The blood which is sent 
 to a secretory gland, before reaching it, undergoes preparatory 
 changes, which dispose it to furnish the materials of the fluid that 
 is to be separated from it. We have seen, in treating of digestion, 
 how the blood which the vena portae sends to the liver is fitted for the 
 secretion of bile. There can be no doubt that the portion of blood 
 which is carried to the testicles, by the long, slender, and tortuous 
 spermatic arteries, undergoes changes which bring it nearer to the 
 seminal fluid. 
 
 The rapidity with which the blood flows into an organ, the length, 
 the diameter, the direction, the angles of its vessels, the arrangement 
 of their extreme ramifications, which may be stellated, as in the liver 
 in fasciculi, as in the spleen convoluted, as in the testicles, &c., are 
 circumstances which should be taken into account in the study of 
 each secretion, since all have some influence on the nature of the 
 fluid secreted, and on the manner in which the secretion is effected. 
 
 The fluid which lubricates the whole extent of the movable sur- 
 faces by which the bones of the skeleton are articulated together, is 
 not exclusively prepared by the membranous capsules which envelope 
 the articulations. A number of reddish-coloured cellular substances, 
 placed in their vicinity, co-operate in the secretion. Though these 
 parts, which were long considered as synovial glands, do not com- 
 pletely resemble the conglomerate glands, and although no glandular 
 bodies nor excretory ducts can be demonstrated in them, they can- 
 not, however, but be considered as fulfilling, to a certain degree, 
 the same functions ; and one must admit that they are of some utility 
 in the secretion of the synovia. They are always met with, and their 
 extent and bulk are always proportioned to the extent of the auri- 
 cular surfaces, and to the frequency of motion in the joints near 
 which they are situated. They are found in all animals ; pale and 
 light coloured in those which have been long at rest ; red, highly 
 vascular, and bearing the marks of a kind of inflammatory diathesis, 
 in those which have been compelled to violent exercise, as the 
 oxen which are brought to Paris from distant provinces, and the 
 wild animals which have been hunted. In anchylosis they are less 
 red, and of greater consistence, than in a healthy state.
 
 OF THE SECRETIONS. 247 
 
 When, from the irritation attending friction, the fluids are deter- 
 mined towards an articulation which is in motion, do they not then, by 
 passing through those glandulo-cellular bodies, undergo a peculiar 
 modification, which renders them fitter for the secretion of synovia? 
 This would not be the only instance in the human body of parts whose 
 action is but secondary, and connected with that of other organs 
 principally engaged in a secretion whose materials are contained in the 
 blood which passes through them. It will be urged, no doubt, that 
 this preparatory apparatus is not met with in the neighbourhood of the 
 great cavities : but it should be recollected, that the chemical compo- 
 sition and the uses of the synovia are not precisely the same as those of 
 the fluids secreted by the pleura or the peritonaeum ; and that, besides, 
 the analogy between two objects does not constitute their identity. 
 The human mind, being naturally indolent, loves to discover analogies 
 that support it in its weakness, and that may save it the trouble of 
 seeking points of difference. I am aware that, to prove that the me- 
 chanism of the synovial secretion, which exactly resembles that of the 
 fluid which moistens the inside of the great cavities, and requires, like it, 
 but a simple membranous apparatus, it is. customary to repeat, in every 
 possible way, that Nature is scanty in her means, and lavish in her 
 results ; that she produces from the same cause a variety of different 
 effects, &c. ; but, without pointing out the manifest absurdity of admit- 
 ting metaphysical arguments in the natural sciences, is it not much more 
 reasonable to acknowledge, with philosophers, that the primitive cause 
 may vary in many ways, and that its innumerable modifications, whence 
 arise the difference in the effects, exceed the limited powers of our 
 understanding ? 
 
 CI. Of the state of the circulation and nervous influence in secreting 
 parts. When a gland is irritated it becomes a centre of fluxion, 
 towards which the fluids are determined from every part ; it swells, 
 hardens, contracts, is in a kind of state of erection, bends on itself, and 
 acts on the blood conveyed by its vessels. Secretion, depending on the 
 peculiar and inherent power of the glandular organ, is promoted by 
 the slight motion which it receives from the neighbouring muscles. 
 The gentle pressure of those parts on the glandular organs is sufficient 
 to keep up their excitement, and to assist in the separation and excre- 
 tion of the fluid. Bordeu, in his excellent work on the glands and on 
 their action, has shewn that it is not in consequence of the compres- 
 sion which is produced on them by the neighbouring muscles, that they 
 part with the fluid they have prepared ; and that physiologists were there- 
 fore very much in the wrong in saying that the excretion of a fluid 
 consisted merely in t its expression, and in comparing, under that^point 
 of view, the glands to spunges soaked with a fluid which they give out 
 on being squeezed.
 
 248 OF THE SECRETIONS. 
 
 The excretory ducts of organs absorb or reject the secreted fluid 
 according as it affects their inhalant mouths : these canals partake in 
 the convulsive state of the gland, undergo a degree of erection, and 
 contract on the fluid to expel it. Thus, the saliva starts from the paro- 
 tid duct at the sight, o& on the recollection, of food that has been 
 longed for ; thus, the vesiculae seminales and the urethra (for the reser- 
 voirs in which the fluids lie some time before being expelled may be 
 considered as forming a part of the excretory ducts), contract, become 
 straighter, and lengthen themselves, to force to a distance the spermatic 
 fluid. 
 
 The thin and transparent ureters of fowls have been seen to con- 
 tract on the urine, which, in these animals, concretes on the slightest 
 stagnation. 
 
 After remaining a certain length of time in that state of excite- 
 ment, the glands relax, their tissue collapses, the juices cease to be 
 conveyed to it as plentifully, they fall into a state of repose or sleep, 
 which restores their sensibility, exhausted by too much action. It is 
 well known that a gland over-stimulated, becomes, like any other part, 
 insensible to the stimulus, the continued application of wkich parches 
 and exhausts it. 
 
 From what has just been said relative to the mechanism of the 
 secretions, it will be seen that this function may be divided into three 
 very distinct periods ; 1st, that of irritation, characterised by the growth 
 of the vital properties, and by the more copious accession of the fluids, 
 the necessary consequence of that excitement ; 2dly, the action of the 
 gland, that is, its secretion, properly so called ; 3d, and lastly, the action 
 by which the organ parts with the fluid which it has prepared : this is 
 the last process, it is called excretion, and is promoted by the action of 
 the neighbouring parts. The determination of fluids to the part, the 
 secretion and excretion succeed each other ; they are preceded by the 
 excitement, which is the primary cause of all the subsequent pheno- 
 mena. The circulation is at first excited, more blood is sent into the 
 part, and penetrates into the tissue of the gland. Dr. Murat has had 
 occasion to open a considerable number of old men, who died at the 
 Bicetre, and who were known to be great smokers of tobacco. He uni- 
 formly observed that their parotid glands, continually called into action 
 by that habit, were larger than in those who were not given to it, and 
 that they were remarkably red , in consequence of the blood with which 
 they were constantly injected. 
 
 What rs the office of the nerves in the act of secretion ? what share 
 has the nervous influence in the elaboration of the fluids furnished by 
 the glandular organs? All the glands which receive their nerves from 
 the system of animal . life, such as the lachrymal and salivary glands, 
 appear, in certain cases, to receive from the brain the secretory
 
 ,* OF THE SECRETIONS. 249 
 
 excitation. The influence of the imagination is sufficient to de- 
 termine it ; thus, we shed involuntary tears when the mind is 
 taken up with painful thoughts ; and the mouth fills with saliva on 
 the recollection of a grateful meal.* In such cases, the influence 
 of the nerves on the process of secretion is indisputable ; it is not so, 
 however, with the conglomerate glands that receive their nerves from 
 the great sympathetics. The secretion of the kidneys, of the liver, 
 and of the pancreas, appears less influenced by affections of the 
 mind; the brain, besides, has no immediate connexion with these 
 glands; their nerves are almost entirely given off by the great sym- 
 pathetics ; the kidneys, in particular, receive no nerves from the brain 
 or from the spinal marrow ; hence the secretion of urine seems, more 
 than any other, to be independent of the nervous influence.f 
 
 This great number of secretory organs, constantly engaged in sepa- 
 rating various secretions from the mass of the fluids, would soon 
 exhaust it, if the calculations of physiologists of the amount of what a 
 gland is capable of secreting, were not manifestly exaggerated. In 
 fact, if we admit with Haller, that the mucous glands of the intestinal 
 canal secrete in twenty-four hours eight pounds of mucus ; that, in the 
 
 * These glands, viz. the lachrymal and salivary, receive nerves both from the 
 nearest ganglions and from the nerves of voluntary motion : the former set of 
 nerves most probably enables them to perform their ordinary functions, the latter 
 excites or reinforces these functions whenever the mind is under certain impres- 
 sions /. C. 
 
 f Although these organs are not directly influenced by the cerebral and spinal 
 nerves, it cannot be satisfactorily denied that the ganglial nerves, which are so 
 abundantly distributed to the blood-vessels supplying these organs, bestow on these 
 vessels that peculiar influence which determines the nature and quantity of the 
 secretion ; for how can we suppose the capillary tubes, through which the blood 
 flows, to be able to secrete a peculiar fluid of themselves, without resorting to the 
 position that the nerves, which so abundantly supply the ramifications of the blood, 
 vessels, and the substance of the secreting organs, actually influence, and, through 
 the medium of those vessels, even produce, the secretions in question ? Are not 
 these nerves requisite to the vital actions of the viscera which they supply ? Do 
 we know an animal that does not possess them as a most essential part of its organ- 
 isation ? And can we suppose that they are distributed in so abundant a manner 
 to the vessels of a secreting organ, without performing a most requisite part in the 
 production of the fluids which that organ secretes ? A close investigation of the 
 structure of the secreting viscera and surfaces shews that their blood-vessels, 
 which bear a close relation to the extent of function which such viscera individually 
 perform, are more liberally supplied with this class of nerves than the vessels of any 
 other of the animal textures : indeed, every important secreting gland has a dis- 
 tinct ganglion, or plexus of these nerves, surrounding the blood-vessels which 
 belong to it, but more especially the arteries ; and some of these organs have both 
 a large plexus of nerves and a ganglion, whence their nerves are exclusively derived, 
 and which appears to be entirely devoted to the functions of the viscus whose 
 blood-vessels they so plentifully supply. See on this subject the APPENDIX, Notes 
 H, A A, and those on Digestion. J. C. 

 
 250 OF THE SECRETION OF FAT. 
 
 same space of time, the kidneys secrete four pounds of urine ; that the 
 same quantity is lost by the insensible perspiration, and again as much 
 by the pulmonary exhalation ; there will be lost, daily, twenty pounds 
 of fluids, almost entirely excrementitious ; for we do not include in 
 that calculation the bile, the tears, nor the saliva and pancreatic fluid, 
 which, in part, return into the blood after being separated from it ; 
 nor the serum, which moistens the internal surfaces, and which is purely 
 recrementitious. 
 
 This exaggeration in the calculation of the fluids which are daily 
 poured out by the different emunctories, is to be attributed to the cir- 
 cumstance of having taken the maximum of each secretion, without 
 considering that they mutually supply each other ; so that when less 
 urine is voided, the quantity of perspiration is greater, and vice versd. 
 It is very well known, that a violent diarrhoea is frequently the conse- 
 quence of sudden cold applied to the skin ; the fluids, at once re- 
 pelled towards the intestinal canal, having to pass through the mucous 
 glands, whose action is greatly increased.* 
 
 CII. Of other glands. It has been customary to enumerate among 
 the glands certain bodies which have truly a glandular appearance, 
 but the uses of which are yet unknown. Thus, the thyroid and thymus 
 glands, which are parenchymatous organs, destitute of excretory ducts, 
 though receiving many vessels and some nerves, do not appear to 
 secrete any fluid. But may not the blood which is conveyed so plen- 
 tifully to the thyroid gland, undergo, nevertheless, certain changes, 
 though we may not be able to discover what they are ? Besides, may 
 not the lymphatics perform the office of excretory ducts, and convey 
 back again immediately into the mass of the blood the fluid which has 
 undergone changes in the glandular body ? The capsulse renales are in 
 the same condition : they have, however, in addition, an internal reser- 
 voir, a kind of lacuna, whose parietes are smeared with a viscid and 
 brown coloured substance secreted by the capsule, and which, doubt- 
 less, is conveyed into the mass of the blood by the lymphatics arising 
 from the parietes of its internal cavity. 
 
 CHI. Of thff secretion of adeps within the cellular tissue. This 
 soft tissue, which is diffused over the whole body, and affords a covering 
 to all our organs, is of use not merely in separating them from one ano- 
 ther, and in connecting together the different parts ; it is, besides, the 
 secretory organ of the adipose substance, a semi-concrete oily animal 
 matter, which is found in almost every part of the body, deposited 
 
 , * An increased flow of urine takes place in most persons during the first cold of 
 autumn ; and cold suddenly applied to the surface of the body, by checking the 
 perspiration, often increases exhalation into the cellular textures and on the serous 
 membranes, thus inducing dropsies.
 
 OF THE SECRETION Of FAT. 251 
 
 in its innumerable cells. The membranous parietes of these small cellular 
 cavities are supplied by numerous minute arteries, in which the adeps is 
 separated ; it is conveyed by its specific light weight to the circumfe- 
 rence of the column of blood in the vessels, and transudes through the 
 pores in their parietes. Its quantity and consistence vary in different 
 parts of the body, and in different persons : there is situated below the 
 skin a thick layer of cellular substance (pannicule grassieux) ; it is 
 found in considerable quantity between the interstices of the muscles, 
 along the blood-vessels, near the articulations, and in the vicinity of 
 certain organs, as the eyes, the kidneys, and the breasts. That which 
 fills the bottom of the orbit, and which surrounds the eye-ball, is 
 softish and almost fluid ; that which envelopes the kidneys and the 
 great joint, is, on the contrary, of the consistence of suet. Between 
 these two extremes there are many gradations ; and it may be said that 
 the animal oil in question is not exactly the same in any two differ- 
 ent parts of the body. The high temperature of the human body 
 maintains it in a state of semi-fluidity, as may be observed in surgical 
 operations. 
 
 In some parts it is even absolutely fluid ; but its nature is then 
 observed to be greatly changed, it no longer contains any oily sub- 
 stance, and differs but little from a mere aqueous gelatine. Thus, the 
 fluid in the cellular tissue of the eye-lids, of the scrotum, &c., has 
 been considered by several physiologists as positively different from 
 fat. It may not be amiss to observe, that the laminae of the cellular 
 tissue in such circumstances yield more readily to extension, pre- 
 sent a greater surface, form membranous expansions, and circumscribe 
 cells of a considerable size, so that the differences in the secretion 
 perfectly coincide with the difference of structure. It may further be 
 observed, that the functions of the eye-lids and of the penis required 
 that they should not contain any fat. Considerable deformity, when 
 the person grew fat, would have been the consequence of the 
 increased bulk of these parts ; and besides, the folds of the skin 
 would not have that free motion which their functions require. No 
 real adeps is ever found within the skull, and the utility of this condi- 
 tion is very obvious. To how many dangers would not life have been 
 exposed, if a fluid so varying in quantity, and the amount of which 
 may be trebled in a very short space of time, had been deposited in a 
 cavity accurately filled by an organ which is affected by the slightest 
 compression ? 
 
 In an adult male, of moderate embonpoint, the proportion of adeps 
 is about one-twentieth of the weight of the whole body ; it is greater 
 in proportion in children and in females, for its quantity is always 
 relative to the energy of the functions of assimilation. When diges-
 
 252 OF THE USES OF THE FAT. , 
 
 tion and absorption are performed with great activity, fat accumulates 
 within the cellular substance : and if it be considered that it is but 
 imperfectly animalised ; that it bears the most striking analogy to 
 the oils extracted from plants; that it contains very little azote and 
 much hydrogen and carbon, like "all other oily substances, since, on 
 distillation, it is decomposed, and yields water and carbonic acid, with 
 a very small quantity of ammonia ; that its proportions are very vari- 
 able, and may be considerably increased or diminished, without mani- 
 festly impairing the order of the functions ; that animals that spend a 
 great part of their life without eating, seem to exist during their torpid 
 state on the fat which they have previously accumulated in certain 
 parts of the body ;* one will be led to think that the state of fat is to 
 a portion of the nutritive matter, extracted from the food, a kind of 
 intermediate state through which it has to pass before it can be assimi- 
 lated to the animal whose waste it is destined to repair. Animals 
 that live on grain and vegetables are always fatter than those which 
 live exclusively on flesh. Their fat is consistent and firm, while that 
 of carnivorous animals is almost completely fluid. 
 
 A corpulent man on having his diet suddenly reduced, sensibly 
 becomes thinner in a very short time ; the bulk and weight of his body 
 diminishes from the absorption of the fat which supplies the deficient 
 quantity of blood. Adeps may, therefore, be considered as a substance 
 in reserve, by means of which, notwithstanding the small quantity of 
 food and its want of nutritious qualities, Nature finds wherewith to 
 repair the daily waste. 
 
 CIV. Of the use of the fat. The use of adeps is not, as has been 
 stated, on the authority of Macquer, to absorb the acids that are formed 
 in the animal economy ; that which is obtained from it by distillation 
 (the sebaceous acid) is a new product, formed by the combination of the 
 oxygen of the atmosphere with the hydrogen, the carbon, and the small 
 quantity of azote which it contains. The small quantity of this last 
 substance nearly constitutes it a vegetable acid. Fat has a consi- 
 derable affinity for oxygen, and by combining with it turns rancid, 
 after remaining some time exposed to the air. It deprives metallic 
 oxides of a part of their oxygen, and likewise, on being tritu- 
 rated with metallic substances, promotes their oxidisement. In pro- 
 portion as it absorbs oxygen its density increases; thus, oils be- 
 
 * Marmots and dormice become prodigiously fat during the autumn ; they then 
 take to their holes, and live in them during the six winter months on the fat 
 which is accumulated in all their organs. There is most fat collected in the abdo- 
 men, in which the epiploon forms masses of a considerable size. When, in the 
 spring, their torpor ceases, and they awaken from their sleep, they are, for the most 
 part, exceedingly emaciated.
 
 OF THE USES OF THE FAT. 253 
 
 come concrete by combining with oxygen, and fat acquires a con- 
 sistence almost equal to that of wax, which is itself a fatty substance 
 highly oxidised. 
 
 Besides the principal use we have assigned to adeps, and accord- 
 ing to which the cellular system may be looked upon as a vast reser- 
 voir, in which there is deposited a considerable quantity of nutritive 
 and semi-animalised matter, this fluid answers several purposes of 
 secondary utility. It preserves the body in its natural temperature, 
 being, as well as the tissue of the cells in which it is contained, a very 
 bad conductor of heat. Persons who are excessively corpulent, scarcely 
 feel the most severe cold ; and the animals which inhabit northern cli- 
 mates, besides being clothed in a thick fur, are likewise provided with a 
 considerable quantity of fat. The fishes of the frozen seas, the animals 
 which seldom go far from the polar regions, and all kinds of whales, 
 are covered with fat, and have also a considerable quantity within their 
 bodies. By its unctuous qualities, fat promotes muscular contraction, 
 the motion of the different organs, and the free motion on each other 
 of the different surfaces ; it stretches and supports the skin, fills vacui- 
 ties, and gives to our limbs those rounded outlines, those elegant and 
 graceful forms, peculiar to the female body. Lastly, it envelopes and 
 covers over the extremities of the nerves, diminishes their susceptibility, 
 which is always in an inverse ratio of the embonpoint, a circumstance 
 that induced a physician of merit to say, that the nervous tree, planted 
 in the adipose and cellular substance, suffers when, from the collapse 
 and removal of that tissue, its branches are exposed in an unprotected 
 state to the action of external causes, as injurious to them as the rays 
 of the sun to a plant torn from its native soil. It is, in fact, observed, 
 that nervous people are exceedingly thin, and have an excessive degree 
 of sensibility. Too much fat, however, is as injurious as too small a 
 quantity of it. I have seen several persons whose obesity was such 
 that, besides being completely incapable of taking the slightest exercise, 
 they were in great danger of suffocation. Respiration in such per- 
 sons is, at times, interrupted by deep sighs ; and their heart, pro- 
 bably overloaded with fat, expels with difficulty the blood within its 
 cavities. 
 
 CV. According to modern chemists the use of fat is to take from 
 the system a part of its hydrogen. When the lungs or liver are dis- 
 eased, when respiration or the biliary secretion does not carry out of the 
 system a sufficient quantity of that oily and inflammable principle, fat 
 forms in a greater proportion. They appeal to the result of the expe- 
 riment of shutting up a goose, whose liver is to be fattened, in a con- 
 fined cage, placed in a hot and dark situation, and in gorging it with 
 paste, of which it eats the more greedily, as being unable to stir, it
 
 254 OF THE SECRETION OF THE MARROW. 
 
 gratifies its inclination to action by exerting the organs of digestion. 
 Notwithstanding this quantity of food, the bird becomes emaciated, is 
 affected with a kind of marasmus, its liver softens, grows fatter, more 
 oily, and attains an enormous size. 
 
 This experiment, and many otfrer facts, prove that the secretions 
 from which analogous products are formed, may mutually supply each 
 other : but can we admit the chemical theory of the use of fat, when 
 we recollect, that frequently, in the most corpulent persons, respiration 
 and the secretion of the bile are performed with great freedom and with 
 no difficulty ; while the difficult respiration attending pulmonary con- 
 sumption, and the difficult flow of the bile from an obstruction of the 
 liver, are always accompanied with complete marasmus? 
 
 Whatever moderates the activity of the circulatory system, tends 
 to bring on adipose plethora. Thus, an inactive state of the mind and 
 body, profuse bleedings, castration, sometimes induce obesity; an affec- 
 tion in which the cellular tissue appears affected with atony, and under- 
 goes an actual adipose infiltration, somewhat analogous to that which 
 gives rise to tumours called steatomatous. If the energy of the heart 
 and arteries is too great, emaciation is always the consequence ; when, 
 on the contrary, the sanguineous system is languid, there is formed 
 a gelatinous fat, and the embonpoint is a mere state of bloatedness. 
 
 -This incompletely formed fluid, which distends the parts in persons 
 of a leucophlegmatic habit, is but an imperfect kind of fat; it re- 
 sembles the marrow or the medullary juice, which is a very liquid fat, 
 whose consistence diminishes when animals become lean. Enclosed 
 within the cells of the osseous tissue, in cavities whose sides cannot 
 collapse, and whose dimensions must always remain the same, the mar- 
 row, of which they are never free, is of different degrees of density; 
 and what authors say of its diminished quantity, must be understood as 
 applying to the diminution of its consistence. 
 
 CVI. Of the secretion of the marrow. The secretion of the mar- 
 row is, like that of the fat, a mere arterial transudation : it is performed 
 by the medullary membrane, which is thin, transparent, and cel- 
 lular, lines the inside of the central cavity of the long bones, and 
 extends over all the cells of that spungy substance. The medullary 
 membrane, when in a healthy state, does not give any marks of relative 
 sensibility. In all the amputations I have performed, and they have 
 not been few, in all the operations of the same kind at which I have 
 been present, whatever the bone was, whether it was divided near a 
 joint or in the middle of its body, I never knew the patient complain 
 of pain, provided the limb was well supported by the assistants, and 
 provided no jerk was given by the operator himself. In that operation, 
 the pain occasioned by the division of the skin and of the nerves
 
 OF NUTJUTION. 255 
 
 overcomes every other pain; and I have always seen patients, impressed 
 with the popular prejudice, and expecting anxiously the division of the 
 bone, feel quite free from pain as soon as the saw had begun to work. 
 Nay, several, after expressing by their cries the most acute pain, taking 
 advantage of the kind of ease which follows the division of the flesh, 
 raise their head, and look on while the bone is being sawn through ; 
 at once actors and spectators in this last part of a painful and bloody 
 operation. 
 
 Yet the medullary membrane, the injury of which is attended with 
 no pain while in a healthy state, becomes the seat of the most exqui- 
 site sensibility in the pains in the bones which mark the last stages of 
 the venereal disease ; in the kind of conversion into flesh of the solid 
 bone, known by the name of spina ventosa, as will be mentioned in 
 speaking of the uses of the marrow, in the chapter on the Organs of 
 Motion and on their Action.* 
 
 i 
 
 CHAPTER VI. 
 
 OF NUTRITION. 
 
 CVII. Nutrition the end of the assimilating Processes CVIII. and CIX. Of the 
 
 Process of Nutrition CX. Substances capable of yielding Nutriment CXI. 
 
 Changes produced in alimentary Substances CXII. The ultimate result. 
 
 CVII. ALL the functions which we have hitherto made the object 
 of our study, digestion, by which the alimentary substances received 
 within the body are deprived of their nutritive parts ; absorption, 
 which conveys that recrementitious extract into the mass of the fluids; 
 the circulation, by which it is carried to the parts wherein it is to 
 undergo different changes ; digestion, circulation, absorption, respi- 
 ration, and the secretions, are but preliminary acts, preparatory to 
 the more essential function treated of in this chapter, and the consi- 
 deration of which terminates the history of the phenomena of assi- 
 milation. 
 
 Nutrition may be considered as the complement of the functions of 
 assimilation. The aliment, altered in its qualities by a series of 
 decompositions, animalised, and rendered similar to the substance of 
 the being which it is to nourish, is applied to the organs whose waste it 
 
 * For some further remarks on Secretion, see APPENDIX, Note C C. /. C.
 
 256 OF NUTRITION. 
 
 is to repair; and this identification of the nutritive matter to our 
 organs, which take it up and appropriate it to themselves, constitutes 
 nutrition. Thus there is accomplished a real conversion of the aliment 
 into our own substance. 
 
 There is incessantly going on a waste of the integrant particles of 
 the living body, which a multiplicity of circumstances tend to j carry 
 away from it: several of its organs are constantly engaged in separating 
 from it the fluids containing the recrementitious materials of its sub- 
 stance, worn by the combined action of the air and of caloric, by inward 
 friction, and by a pulsatory motion that detaches its particles. 
 
 Analogous, therefore, to the vessel of the Argonauts, so often repaired 
 in the course of a long and perilous navigation, that on her return no 
 part of her former materials remained, an animal is incessantly under- 
 going decay, and if examined at two different periods of its duration, 
 does not contain one of the same molecules. The experiment per- 
 formed with madder, which dyes red the bones of animals among whose 
 food it is mixed, proves, most unquestionably, this incessant decom- 
 position of animated and living matter. One has only to interrupt, 
 for a sufficient length of time, the use of that plant, to make the 
 uniformly red colour assumed by the bones completely disappear. 
 Now, if the hardest and most solid parts, which are best calculated to 
 resist decay, are undergoing a perpetual motion of decomposition and of 
 regeneration, there can be no doubt that this motion must be far more 
 rapid in those whose power of cohesion is much inferior for example, 
 in the fluids. 
 
 Attempts have been made to determine the period at which the 
 body is completely renovated ; it has been said, that an interval of 
 seven years was required for one set of molecules to disappear and be 
 replaced by others ; but this change must go on more rapidly in child- 
 hood and in youth. It must be slower at a mature age, and must 
 require a considerable time at a very advanced period of life, when all 
 the parts of the body become, in a remarkable degree, fixed and firm 
 in their consistence, while the vital powers become more languid. 
 There can be no doubt, that the sex, the habit, the climate in which 
 we live, the profession we follow, our mode of life, and a variety of 
 other circumstances, accelerate or retard it; so that it is impossible 
 to fix, with any degree of certainty, its absolute duration. 
 
 CVIII. Of the process of nutrition. The parts of our body, in pro- 
 portion as they undergo decay, are repaired only by means of homo- 
 geneous particles exactly like themselves ; were it otherwise, their 
 nature, which always remains the same, would be undergoing perpetual 
 changes. 
 
 When, in consequence of the successive changes which it has under- 
 gone from the action of the organs of digestion, of absorption, of the
 
 OF NUTRITION. 257 
 
 circulation, of respiration, and of secretion, the nutritive matter is 
 animalised or assimilated to the body which it is to nourish, the parts 
 which it moistens retain it and incorporate it to their own substance. 
 This nutritive identification is not performed alike in the brain, in the 
 muscles, in the bones, &c. Each of them appropriates to itself, by a 
 real process of secretion, whatever it meets with fitted for its nature in 
 the fluids conveyed to it by the different kinds of vessels, but especially 
 by the arteries ; it leaves unaffected the remaining heterogeneous par- 
 ticles. A bone is a secretory organ, around which phosphate of lime 
 is deposited ; the lymphatic vessels which, in the process of nutrition, 
 perform the office of excretory ducts, remove that saline substance, 
 when it has lain sufficiently long in the cells of its tissue. The same 
 happens to the muscles with regard to fibrina, and to albumen with 
 regard to the brain ; every part appropriates to itself, and converts 
 into a solid form, those fluids which are of the same nature, in virtue 
 of a power of which the term affinity of aggregation, used in chemistry, 
 gives an idea, and of which it is perhaps the emblem.* 
 
 The nutrition of a part requires that it should be possessed of 
 sensibility and motion ; by tying the arteries and nerves of a part, it 
 cannot be nourished, nor can it live. The blood which flows along 
 the veins, the fluid conveyed by the absorbents, contain, in a smaller 
 proportion than arterial blood, vivifying and reparatory particles. It 
 is even commonly thought, that the lymph and venous blood contain 
 no directly nutritive particles. As to the share which the nerves take 
 in the process of nutrition, that is not yet completely determined. 
 A limb that is paralysed, by the division or tying of its nerves, or by 
 any other affection, sometimes retains its original size and plumpness ;f 
 most frequently, however, though perhaps for want of motion, it be- 
 comes parched, emaciated, and shrinks in a remarkable degree. 
 
 CIX. We should be enabled to understand the process of nutrition, 
 if, after having accurately determined the difference of composition be- 
 tween our food and the substance itself of our organs, we could see 
 how each function robs the aliments of their qualities, to assimilate 
 them to our own bodies ; and what share each function takes in the 
 transmutation of the nutritive particles into our own substance. To 
 illustrate this point, suppose a man to live exclusively on vegetable 
 substances, which, in fact, form the basis of our food : on whatever 
 part of the plant he may live, whether on the stem, on the leaves, OB 
 
 * Assimilation takes place in a more perfect manner when the vital influence is 
 complete in all its relations. See APPENDIX, Note D D. J. C. 
 
 f This and various other considerations evince that nutrition is not essentially 
 dependent upon the voluntary nerves, but upon that class of nerves (the ganglial), 
 which is chiefly ramified on the blood-vessels. See the above Note in the AP- 
 PENDIX J. C. 
 
 s
 
 258 OK XUT1UTIOX. 
 
 the blossoms, on the seeds, or on the root, carbon, hydrogen, and 
 oxygen, enter into the composition of these vegetable substances, which, 
 by a complete analysis, may all be resolved into water and carbonic 
 acid. To these three constituent principles there is frequently united 
 a small quantity of azote, of salts, and of other materials, in different 
 proportions. If, then, we examine the nature of the organs in this 
 man, whose food is entirely vegetable, it will be found that they are 
 different in their composition, and far more animalised than that kind 
 of food ; that azote predominates, though the vegetable substance con- 
 tains none or only a very small quantity ; that new products, undis- 
 tinguishable in the aliments, exist in considerable quantity in the 
 body which is fed on them, and appear produced by the very act of 
 nutrition. 
 
 The essence of this function is, therefore, to make the nutritive 
 matter undergo a more advanced state of composition, to deprive it 
 of a portion of its carbon and of its hydrogen, to make azote predo- 
 minate, and to produce several substances which did not exist in it 
 before. All living bodies seem to possess the faculty of composing 
 and decomposing the substances by means of which they are main- 
 tained, and to form new products; but they possess it in various 
 degrees of energy. The sea- weed, from the ashes of which soda is 
 obtained, on being sown in a box of soil in which there is not a single 
 particle of that alkali, and watered with distilled water, will no longer 
 contain it, as if it had grown on the sea shore, in the midst of marshes 
 constantly inundated by salt and brackish water.* 
 
 Living bodies, then, are real laboratories, in which there are carried 
 on combinations and decompositions which art cannot imitate ; bodies 
 that appear to us simple, as soda and silex, seem to be formed by the 
 union of their constituent particles ; while other bodies, whose compo- 
 sition we do not understand, undergo an irresistible decomposition : 
 hence, methinks, one may infer, that the power of nature in the com- 
 position and decomposition of bodies far exceeds that of chemistry. 
 
 " I am unacquainted with the details of the experiment referred to by the 
 author ; he quotes it, I conceive, to shew that the power which, he says, is common 
 to all living bodies, of producing a substance not supplied to them from without, is 
 not possessed, in the same degree, by all bodies endowed with life ; since the sea- 
 weed here alluded to does not possess it in an equal degree when watered with 
 distilled as with sea-water. This, I apprehend, is the author's meaning, though 
 the text is somewhat obscure, and would almost lead one to believe he meant, that 
 no alkali whatever can be obtained from the sea plant under the circumstances he 
 states : L'algue marine, dont les cendres fournissent la soude, semde dans line 
 caisse pleine d'un terreau qui ne contient pas un seul atome de cet alkali, arrosee 
 avec 1'eau distilhfe, ne le fournit plus, comme si elle avoit pris sa croissance au milieu 
 des marais toujours inondes par leurs eaux saumatres et muriatiques." T.
 
 OF NUTUITION. 259 
 
 Straw and cereal plants contain a considerable quantity of silex, 
 even when the earth in which they grow has been carefully deprived 
 of its silicious particles. Oats, particularly, contain a large quan- 
 tity of that verifiable earth ; the ashes obtained by burning its seed, 
 on being analysed by means of the nitric acid, were found by M. Vau- 
 quelin to contain -$$-$ of pure silex indissoluble in that acid, and 
 O393 of phosphate of lime dissolved in it. 
 
 The excrements of a hen fed for ten days on oats only, on being 
 calcined and analysed by the same chemist, produced twice as much 
 phosphate and carbonate of lime as was contained in the oats, with 
 a small deficiency in the quantity of silex, which might have been 
 employed in furnishing the excess of calcareous matter ; a transmuta- 
 tion depending "on the absorption of an unknown principle, to the 
 amount of nearly five times its own weight.* 
 
 CX. Substances capable of yielding nutriment* A substance, to 
 be fit for our nourishment, should be capable of decomposition and 
 fermentation ; that is, capable of undergoing an inward and sponta- 
 neous change, so that its elements and relations may be altered. This 
 spontaneous susceptibility of decomposition excludes from the class of 
 aliments whatever is not organised and is not a part of a living body ; 
 thus, mineral substances absolutely resist the action of our organs, and 
 are not convertible into their own substance. The common principle 
 extracted from alimentary substances, however varied they may be, the 
 aliment, as Hippocrates terms it, is, most probably, a compound highly 
 subject to decomposition and fermentation ; this is likewise the opinion 
 of all those who have endeavoured to determine its nature. Lorry 
 thinks it a mucous substance; Cullen says it is saccharine; Professor 
 Halle considers it as an hydro-carbonous oxide, which differs from the 
 oxalic acid only in containing a smaller quantity of oxygen. It is 
 evident that these three opinions are very much alike, since oxygen, 
 carbon, and hydrogen, combined in different proportions, form the 
 mucous saccharine substances and the base of the oxalic acid. On 
 analysing the animal substance, by means of the nitric acid, it is 
 reduced to this last base by depriving it of a considerable quantity of 
 azote, which constitutes its most remarkable character. 
 
 But whence comes this enormous quantity of azote ? How happens 
 it that the flesh of a man living exclusively on vegetables contains as 
 much azote and ammonia, and is as putrescent, as that of a man living 
 on animal food? Respiration does not introduce a single particle of 
 azote into our fluids : this gas comes out of the lungs as it entered ; the 
 
 * See the Annales de Chimie, and the Systtme dcs Connaissances Chimiques de 
 Fourcroy, torn. x. p. 72.
 
 260 OF XUTKITION. 
 
 oxygen alone is diminished in quantity.* Might not one suspect that 
 this element of animal substances is a product of the vital action, and 
 that, instead of receiving it from our aliments, we form it within 
 ourselves, by an act that is hyper-chemical, that is, which chemistry 
 cannot imitate ?f 
 
 CXI. Changes produced in alimentary substances. It has been 
 maintained, that the hydro-carbonous oxide combines, in the stomach 
 and intestinal canal, with oxygen, whether this principle has entered 
 with the aliments into the digestive tube, or whether it is furnished by 
 the decomposition of the fluids within that cavity. The intestinal 
 fluids extricate azote, which combines with the alimentary mass, and 
 occupies the place of the carbon, which the oxygen has taken from it, 
 to form carbonic acid. On reaching the lungs, and being again ex- 
 posed to the action of the oxygen of the atmosphere, this gas robs it 
 of a portion of its carbon, and as it disengages the azote of the venous 
 blood, it brings about a new combination of that principle with the 
 chyle. Lastly, propelled with the blood to the surface of the skin, the 
 atmospherical oxygen disengages its carbon and completes its azotisa- 
 tion. The cutaneous organ is perhaps to the lymphatic system, what the 
 pulmonary organ is to the sanguineous system. 
 
 The animalisation of the animal substance is therefore effected 
 principally by the loss of its carbon, which is replaced by the excess 
 of azote in the animal fluids. These maintain themselves, in this 
 manner, in a due temperament ; for, continually parting with the 
 carbonous principle in the intestinal, pulmonary, and cutaneous com- 
 binations, they would be over-animalised, if an additional quantity of 
 chyle did not seize the azote, which is in excess. Still, this theory 
 does not account for the formation of the phosphoric salts, of the 
 adipocire, and a variety of other products : but, without adopting it to 
 the full, one may presume, from the experiments and facts on which 
 it rests, that the oxygen of the atmospherical air is one of the most 
 powerful agents employed by nature in the transformation of the 
 aliments we live upon into our substance. 
 
 How are those animals nourished which live solely on mere ani- 
 malised flesh ; that is, containing a greater quantity of azote, and a 
 greater proportion of ammonia, than their own substance ? In such a 
 
 * See APPENDIX, Notes W and D D. 
 
 f The experiments of Messrs. Allen and Pepys prove, that when an animal is 
 made to breathe pure oxygen, the blood disengages a certain quantity of azote, and 
 absorbs an equal quantity of oxygen Philosophical Transactions, 1809. But this 
 arises from the azote already absorbed by the blood from the air ; for the recent 
 experiments of M. Edwards demonstrate that azote is absorbed by the blood in the 
 lungs, and thence given out during respiration. See Les Agens Physiques sur la 
 Vie, par M. Edwards, 1824. J. C.
 
 
 OF XCTIUTION. 261 
 
 case, the assimilation of the aliments consists in their disanimalisation, 
 either by the co-operation of all the organs, or by the sole action of 
 the digestive organs, by the combination of the gastric juice with the 
 other fluids. 
 
 The constituent elements entering into the composition of our 
 organs, whether coming from the exterior, or formed by the vital power 
 itself, are thrown out of our body by the different emunctories, and 
 cease to form a part of it, after remaining within it for a limited time. 
 The urine carries along with it an enormous quantity of azote ; the 
 lungs and the liver rid us of the carbon and of the hydrogen ; the 
 oxygen, of which eighty-five parts in the hundred enter into the com- 
 position of water, is evacuated by means of the aqueous secretions, 
 which carry off, in a state of solution, the saline and other soluble 
 principles. 
 
 Among those salts there is one but little soluble, and which never- 
 theless, is of primary consequence among the constituent principles 
 of the animal economy. Phosphate of lime, in fact, forms the base 
 of several organs ; it almost entirely forms the osseous system at an 
 advanced period of life ; all the white organs, all our fluids, contain a 
 remarkable quantity of that substance, of which the economy rids 
 itself by a kind of dry secretion. The outer covering is, in all animals, 
 the emunctory destined for that purpose : the annual moulting of birds, 
 the fall of the hair of quadrupeds, the renovation of the scales of 
 fishes and reptiles, carry off every year a considerable quantity of 
 calcareous phosphate. Man is subject to the same laws, with this 
 difference, that the annual desquamation of the epidermis is not under 
 the absolute influence of the seasons, as in the brute creation. The 
 human epidermis is renewed annually, as well as the hair on the head 
 and on the body ; but this change is brought about gradually, and is 
 not completed in a season : it does not take place in the spring, as in 
 most animals, nor in autumn with the fall of the leaf, though at these 
 two periods the hair falls off in greatest quantity, and the desquamation 
 of the cuticle is most active. These two phenomena last throughout the 
 whole year, as in southern climates the fall of the leaves and the reno- 
 vation of vegetation are continually going on. As will be mentioned, in 
 speaking of the functions of generation, man living in a state of society, 
 and enjoying all the advantages of civilisation, is not as much under the 
 influence of the seasons as the inferior animals. One cannot, however, 
 but observe, that the successive shedding and renewing of the epider- 
 moid parts, as the cuticle, the nails, and the hair, are among the most 
 effective means which nature possesses of parting with the phosphate 
 of lime, so abundant in all animals, and which, nevertheless, is so 
 insoluble, and consequently so unfit to be carried out of the system 
 along with the excrementitious fluids. This effect is very remarkable,
 
 202 OF NUTRITION. 
 
 on the termination of several diseases, in the salutary renovation of the 
 solids and fluids which takes place during convalescence. The hair 
 ceases to grow on the bald head of an old man; his perspiration 
 diminishes. May not this be the cause of the great quantity of calca- 
 reous salts, of the ossification of the vessels, of the induration of the 
 membranes ? 
 
 CXI I. What is the ultimate result presented to us by this series of 
 functions, linked together, growing out of one another, and all acting 
 on the matter of nutrition, from the moment it is received within the 
 body, till it is applied to the growth and reparation of its organs ? * It 
 shews us man living within himself, unremittingly employed in con- 
 verting into his own substance heterogeneous substances, and reduced 
 to an existence purely vegetative, inferior even to the greater part of 
 organised beings in his powers of assimilation. But how high is he not 
 placed above them all in the exercise of those functions we are now 
 about to contemplate, functions which raise him above his own 
 nature, which enlarge the sphere of his existence, which serve him to 
 provide for all his wants, and to keep up, with all nature, those mani- 
 fold relations which subject her to his empire !f 
 
 * Intimately connected with the consideration of nutrition is that of reproduc- 
 tion. This phenomenon takes place to a very limited extent indeed in the more 
 perfect animals ; but as we descend in the scale of creation, we find that the de- 
 struction of a member or part of the body of an animal is, after a time, followed by 
 a partial or entire reproduction of the part destroyed ; and amongst the lowest class 
 of animals, even a portion only of the body becomes a perfect animal, and presents 
 the specific characters of the parent. In this respect, the phenomena of animal life, 
 as we descend through its gradations, approach those of vegetable existence. 
 
 f For further observations on Nutrition, see APPENDIX, Notes S and CC.
 
 OF SENSATIONS. 263 
 
 FUNCTIONS WHICH TEND TO THE PRESERVATION OF THE 
 
 INDIVIDUAL, BY ESTABLISHING HIS RELATIONS 
 
 WITH THE BEINGS THAT SURROUND HIM. 
 
 CHAPTER VII. 
 
 OF SENSATIONS. 
 
 CXIII. Man enjoys the existence of Sensation in its greatest perfection. 
 CXIV. Of Light CXV. Sense of Sight CXVI. Of the Eye-brows, Eye- 
 lids, and Lachrymal Apparatus CXVII. Of the Globe of the Eye, &c. 
 CXVIII. Mechanism and Phenomena of Vision CXIX. Of the Organ of 
 Light in the lower Animals CXX. Of Sound CXXI. Of the Organ and 
 
 Mechanism of Hearing CXXII. Pathological Physiology of Hearing 
 
 CXXIII. Of Odours CXXIV. Of the Organ of Smell CXXV. Of the 
 
 Sensation of Odours CXXVI. Of Flavours CXXVII. and CXXVIII. Of 
 
 the Sense of Taste CXX IX. Of the Sense of Touch CXXX. Of the 
 
 Integuments CXXXI. Of the Nails CXXXII. and CXXXIII. Of the 
 
 Hair of the Head and of other parts CXXXIV. and CXXXV. Of the 
 
 Sensations conveyed by Touch, and of its States in different parts of the 
 
 Body CXXXVI. Of the Nerves. CXXXVII. Structure of Nerves 
 
 CXXXVIII. and CXXXIX. Distribution of Nerves CXL. Of the Spinal 
 
 Chord and its Functions CXLI. Of the Coverings of the Brain CXLII. 
 
 Of the Size of the Brain CXLIII. Structure of the Cerebral Mass 
 
 CXLIV. The Circulation of the Brain CXLV. The Connexion between the 
 
 Actions of the Brain and Heart CXLVI. Of the Theory of Syncope . 
 
 CXLVII. to CL. Of the Motions of the Brain CLI. Functions of the 
 
 Brain and Nerves CLII. Analysis of the Understanding CLIII. Sources of 
 our Ideas CLIV. Of Perception, Attention, Memory, Imagination, and 
 Reasoning CLV. Of spoken Signs or Words CLVI. to CLVIII. Of the 
 
 Disorders of Thought CLIX. Of Sleep and Waking CLX. Of Dreams and 
 
 Somnambulism. 
 
 CXIII. WE have already seen how the human body, essentially 
 changeable and perishable, maintains itself in its natural economy, 
 carries on its growth, and supplies its decay, by assimilating to its 
 own substance principles that are yielded to it by the food it digests, 
 and by the air it breathes. I shall now proceed to examine by 
 what organs man is enabled to keep up, with all nature, the relations 
 on which his existence depends ; by what means he is made aware of 
 the presence of objects which concern him, what means he possesses to 
 fit his connexion with them to his welfare, to draw them towards him
 
 264 OF LIGHT. 
 
 or to repel them, to approach or to avoid and escape them, as he 
 perceives in them danger, or the promise of enjoyment. 
 
 Man possesses, in all its plenitude, this new mode of existence, 
 which is denied to vegetable nature. Of all animals, it is he that 
 receives impressions the most crowded and various, that is most filled 
 with sensations, and that employs them with the most powerful 
 combination, as the materials of thought, and the sources of in- 
 telligence : he is the best organised for feeling the action of all beings 
 around him, and re-acting on them in his turn. In the study which 
 we are about to undertake, we shall see many instruments placed on 
 the limits of existence, on the surface of the living being ready to 
 receive every impression ; conductors, stretching from these instru- 
 ments to one common centre, to which all is carried ; conductors 
 through which this central organ regulates the actions, which now 
 transport the whole body from one place to another (locomotion) ; now 
 merely change the relative situation of its parts (partial motion) ; and 
 at other times produce in the organs certain dispositions, of which 
 speech and language, in their various forms, are the result. 
 
 If we are thoroughly to understand the mechanism of this action 
 of outward objects on our body, we must follow the natural succession 
 of the phenomena of sensation ; studying first the bodies which 
 produce the sensitive impression, examining next the organs that 
 receive it, and next the conductors which transmit it to a particular 
 centre, whose office is perception. To take the sense of sight, for 
 instance, we can never understand how it is that light procures us the 
 knowledge of certain qualities of bodies, if we have not learnt the laws 
 to which that, fluid is subjected, if we know nothing of the con- 
 formation of the eyes, of the nerves by which those organs com- 
 municate with the brain, and of the brain itself, whither all sensations, 
 or rather the motions in which they consist, are ultimately carried. 
 
 CXIV. Of iight. At this day, the greater part of natural 
 philosophers consider it as a fluid impalpable, from its exceeding 
 tenuity. Many believe it to be only a modification of caloric, or of 
 the matter of heat; and this last opinion has received much plau- 
 sibility from the late observations of Herschel.* I shall not examine 
 
 * This celebrated astronomer has published in the Philosophical Transactions 
 of the Royal Society for 1800, a series of experiments, which shew that the 
 different coloured rays heat in different degrees the bodies on which they fall, and 
 that the red ray, which is the least refrangible, gives also the greatest heat. 
 
 The thermometer placed out of the spectrum, and towards the red ray, so that 
 It would receive any rays yet less refrangible, rises higher than when it is placed in 
 that colour : from which Herschel concludes that rays are given out by the sun, too 
 little refrangible to produce the sensation of light, and of colours, but which 
 produce the sensation of heat.
 
 OF LIGHT. 265 
 
 whether, as Descartes and his followers imagine, light, consisting of 
 globular molecules, exists of itself, uniformly diffused through space ; or 
 as Newton has taught us to believe, it be but an emanation of the sun 
 and fixed stars, which throw off from their whole surface a part of 
 their substance, without ever exhausting themselves by this continual 
 efflux : it is enough for us to know, 1st, That the rays of this fluid 
 move with such velocity, that light passes in a second through a 
 distance of seventy-two thousand leagues, since, according to the 
 calculation of Roemer, and the tables of Cassini, it traverses in 
 something less than eight minutes the thirty-three millions of leagues 
 that separate us from the sun; 2dly, That light is called direct, when 
 it passes from the luminous body to the eye without meeting any 
 obstacle ; reflected, when it is thrown back to that organ by an opaque 
 body; refracted, when its direction has been changed by passing from 
 one transparent medium to another of different density. 3dly, That the 
 rays of light are reflected at an angle equal to that of incidence ; that 
 a ray passing through a transparent body, is more strongly refracted 
 as the body is more convex on the surface, denser, or of more 
 combustible elements. It was from this last observation, that Newton 
 conjectured the combustibility of the diamond, and the existence of a 
 combustible principle in water, since placed beyond doubt, by the 
 beautiful experiments of modern chemistry. 4thly, That a ray of light 
 refracted by a glass prism, is decomposed into seven rays, red, orange, 
 yellow, green, blue, indigo, and violet. Each of these rays is less 
 refrangible as it is nearer to the red. This ray is, of all, that which 
 strikes the eye with the greatest force, and produces on the retina this 
 liveliest impressions. The eagerness of savages for stuffs of this colour 
 is well known. Among almost all nations it has dyed the mantle of 
 kings : it is the most brilliant and splendid of all : there are animals 
 whose eyes seem scarcely to sustain it:, I have seen maniacs whose 
 madness, after a long suspension, never failed to break out at the sight 
 of a red cloth, or of one clothed in that colour. Green is, on the 
 contrary, the softest of colours, the most permanently grateful, that 
 which least fatigues the eyes, and on which they will longest and 
 most willingly repose. Accordingly, nature has been profuse of green, 
 in the colouring of all plants ; she has dyed, in some sort, of this 
 colour the greater part of the surface of the globe. When the eyes 
 bear uneasily the glare of too strong a light, glasses of this colour are 
 used to soften the impression, which slightly tinge with their own hue 
 all the objects seen through them. 5thly, the violet ray, last in the 
 scale, of which the middle place is filled by the green, is of all the 
 akest, the most refrangible. Of all colours, violet has the least 
 stre ; forms shew to less advantage under it, their prominences are 
 painters accordingly make but little use of it. When an
 
 266 OF THE SENSE OF SIGHT. 
 
 enlightened body reflects all the rays, the sensations they might sepa- 
 rately produce blend into the sensation of white ; if it reflects a few, 
 it appears differently coloured according to the rays it repels : finally, 
 if all be absorbed, the sensation of black is produced, which is merely 
 the negation of all colour. A black body is wrapped in utter dark- 
 ness, and is visible only by the lustre of those that surround it. 
 Lastly, That from every point in the surface of a luminous or enlight- 
 ened body there issue a multitude of rays, diverging according to their 
 distance, with a proportionate diminution of their effect ; so that the 
 rays from each visible point of the body form a cone, of which the 
 summit is at that point, and the base the surface, of the eye on which 
 they fall. 
 
 CXV. Sense of sight. The eyes, the seat of this sense, are so 
 placed as to command a great extent of objects at once, and enclosed 
 in two osseous cavities, known by the name of orbits. The base of 
 these cavities is forwards, and shaped obliquely outwards ; so that their 
 outward side not being so long as the others, the ball of the eye, sup- 
 ported on that side only by soft parts, may be directed outwards, and 
 take cognisance of objects placed to a side, without it being necessary, 
 at the same time, to turn the head. In proportion as we descend from 
 man in the scale of animated beings, the shape of the base of the 
 orbits becomes more and more oblique ; the eyes cease to be directed 
 forward ; in short, the external side of the socket disappears, and the 
 sight is entirely directed outward ; and, as the physiognomy derives its 
 principal character from the eyes, its expression is absolutely changed. 
 In certain animals very fleet in running, such as the hare, the lateral 
 situation of the organs of vision prevents the animals from seeing 
 small objects placed directly before them ; hence those animals, when 
 closely pursued, are so easily caught in the snares which are laid 
 for them. 
 
 The organ of sight consists of three essentially distinct parts. The 
 one set intended to protect the eye-ball, to screen it, at times, from 
 the influence of light, and to maintain it in the conditions necessary 
 to the exercise of its functions : these parts are the eye-brows, the 
 eye-lids, and the lachrymal apparatus, and they serve as appendages 
 of the organ. The eye-ball itself contains two parts, answering very 
 different purposes ; the one, formed by nearly the whole globe, is a 
 real optical instrument, placed immediately in front of the retina, and 
 destined to produce on the luminous rays those changes which are 
 indispensable in the mechanism of vision ; the other, formed by the 
 medullary expansion of the optic nerve, is the immediate organ of that 
 function. It is the retina which alone is affected by the impression 
 of light, and set in motion by the contact of that very subtle fluid. 
 This impression, this motion, this sensation, is transmitted to the
 
 OF THE EYES, EYE-LIDS, &C. 267 
 
 cerebral organ by the optic nerve, the expansion of which forms the 
 retina. 
 
 CXVI. Of the eye-brows, the eye-lids, and the lachrymal appa- 
 ratus (tutamina oculi, Haller). The more or less dark colour of the 
 hairs of the eye-brows renders that projection very well adapted to 
 diminish the effect of too vivid a light, by absorbing a part of its rays. 
 The eye-brows answer this purpose the more completely, from being 
 more projecting, and from the darker colour of the hairs which cover 
 them ; hence we depress the eye-brows, by knitting them transversely, 
 in passing from the dark into a place strongly illuminated, which 
 causes an uneasy sensation to the organ of sight. Hence, likewise, 
 the custom that prevails with some southern nations, whose eye-brows 
 are shaded by thicker and darker hairs, to blacken them, that they may 
 still better answer the purpose for which they are intended. 
 
 The eye-lids are two movable curtains placed before the eyes, 
 which they alternately cover and uncover. It was requisite that they 
 should be on the stretch, and yet capable of free motion ; now, both 
 these ends are obtained by the tarsal cartilages, which are situated 
 along the whole of their free edges, and of the muscles which enter 
 into their structure. The cellular tissue which unites the thin and 
 delicate skin of the eye-lids to the muscular fibres, contains, instead of 
 a consistent fat, which would have impeded its motion, a gelatinous 
 lymph, which, when in excess, constitutes oedema of the eye-lids. The 
 tissue of the eye-lids is not absolutely opaque, since, even when 
 strongly drawn together, and completely covering the globe of the eye, 
 one may still discern through their texture light from darkness. On 
 that account, light may be considered as one of the causes of 
 awakening, and it is of consequence to keep in the dark patients 
 fatigued by want of sleep. 
 
 The principal use of the eye-lids is to shade the eyes from the 
 continual impression of light. Like all the other organs, the eyes 
 require to recruit themselves by repose ; and they had not been able to 
 enjoy it, if the incessant impression of the luminous rays had conti- 
 nually excited their sensibility. The removal of the eye-lids* is 
 attended with loss of sleep. The fluids are determined to the affected 
 organ, which suffers from incessant irritation. The eyes inflame, the 
 inflammation spreads towards the brain, and the patient expires in the 
 most dreadful agony. Thanks to an advanced state of civilisation, 
 these barbarous tortures have long been abolished ; but what happens, 
 when, from ectropium o( one or other of the eye-lids, a small portion of 
 sclerotic coat or cornea remains uncovered, proves the indis- 
 
 * A mode of punishment in use amongst the ancients, especially the Cartha- 
 ginians.
 
 268 OF THE TEAKS. 
 
 pensable necessity of those parts. The spot exposed to the continued 
 action of the air and of the light becomes irritated and inflamed, and 
 there comes on an ophthalmia, which can be cured only by bringing 
 together, by means of a surgical operation, the divided edges of the 
 opening which is the cause of the affection. From the movable edges 
 of both eye-lids there arise short curved hairs, of the same colour as 
 those of the eye-brows ; they are called eye-lashes, and are intended 
 to prevent insects, or other very light substances floating in the at- 
 mosphere, from getting between the eye-ball and the eye-lids.* 
 
 The anterior part of the eye, thus defended against external in- 
 juries, is continually moistened by the tears. The organ which secretes 
 this fluid is a small gland, situate in a depression at the anterior and 
 external part of the arch of the orbit, imbedded in fat, and supplied 
 with pretty considerable vessels and nerves in proportion to its bulk, 
 and pouring the fluid it secretes, by means of seven or eight ducts 
 which open on the internal surface of the upper eye-lid, by capillary 
 orifices directed downward and inward. The tears are a muco-serous 
 fluid, rather heavier than distilled water, saltish, changing to a green 
 colour vegetable blues, and containing soda, muriate and carbonate of 
 soda, and a very small quantity of phosphate of soda and of lime.f 
 
 In ophthalmia, the irritation of the conjunctiva, transmitted by 
 sympathy to the lachrymal gland, not only augments the quantity 
 of its secretion, but appears likewise to alter the qualities of the fluid 
 that is secreted. The tears, which in those cases flow in such pro- 
 fusion, bring on a sense of burning heat in the inflamed part. Do they 
 not, perhaps, contain a greater quantity of the fixed alkali than in the 
 ordinary state of the parts? and may not the painful sensation depend 
 as much on the increased proportion of soda in the tears, as on the 
 greater sensibility of the conjunctiva ? 
 
 This last membrane is merely a fold of the skin, which is exceed- 
 ingly thin, covers the posterior surface of the eye-lids, and is then 
 reflected over the anterior part of the eye, which it thus unites to the 
 eye-lids. From the whole extent of its surface there oozes an albu- 
 minous serosity, which mingles with the tears, and adds to their 
 quantity. J 
 
 * They also absorb and intercept some of the luminous rays, and thus diminish 
 the hurtful effects of too strong a light J. C. 
 
 f The saline parts amount only to about O'Ol of the whole. The mucus con. 
 tained in the tears has the property of absorbing oxygen from the atmosphere, and 
 of becoming thick and viscid, and of a yellow colour. The circumstance of their 
 acquiring new properties from the absorption of oxygen explains the changes which 
 take place in the tears in some diseases of the eye. See the Chapter in the APPEN- 
 DIX, on the Chemical Constitution of the Textures and Secretions, &c J. C. 
 
 : There is no opening in the skin at the part which corresponds to the globe of 
 the eye; it is exceedingly thin, and is continued, under the name of conjunctiva,
 
 OF THE TEARS. 269 
 
 The tears are equably diffused over the globe of the eye by the 
 alternate motions of the palpebrse ; they prevent the effects of friction, 
 and save the organ of sight from being dried at that part which is 
 exposed to the air. The air dissolves, and carries off in evaporation, a 
 part of the lachrymal fluid. This evaporation of the tears is proved by 
 the weeping, to which those in whom that secretion is very profuse are 
 subject, whenever the atmospherical air, from being damp, does not 
 carry off a sufficient quantity of the fluid. The unctuous and oily fluid 
 secreted by the Meibomian glands, smears the loose edge of the palpe- 
 bree, prevents the tears from falling on the cheek, and answers the 
 same purpose as the greasy substance with which one anoints the edges 
 of a vessel filled above its level, to prevent the overflowing of the 
 contained fluid. 
 
 The greatest part of the tears, however, flow from without inward 
 and towards the inner canthus of the eye ; they take that direction in 
 consequence of the natural slope of the movable edge of the palpebrse, of 
 the triangular groove, which is formed behind the line of union of 
 their edges, whose round and convex surfaces touch each other 
 only in a point ; and this course of the tears is likewise promoted by 
 the action of the palpebral portions of the orbicularis palpebrarum, 
 whose fibres, having their fixed point at the inner angle of the orbit 
 where the tendon is inserted, always draw inward their external 
 commissure. 
 
 On reaching the internal angle of the palpebrae, the tears accumu- 
 late in the lacus lachrymalis,a. small space formed between the edges of 
 the palpebrse, kept separated from each other by the caruncula lachry- 
 malis. This last substance, long considered by the ancients as the 
 secretory organ of the tears, is merely a collection of mucous cryptee, 
 covered over by a loose fold of the conjunctiva. These follicles, alike 
 in nature to the Meibomian glands, secrete, like them, an unctuous 
 substance, which smears the movable edges of the palpebrse, near the 
 internal commissure. The edges of the eye-lids in this situation require 
 a thicker coating, as the tears accumulated in that spot have no where 
 a greater tendency to flow on the cheek. 
 
 Near the union of the inner sixth of the free edge of the palpebrse 
 with the remaining five-sixths, at the outer part, where their internal, 
 
 over the transparent cornea, to which it adheres so firmly that it is not easily sepa. 
 rated from it. In some animals that have no palpebrae, the skin is continued, of 
 the same thickness, over the fore part of the eye. The conjunctiva (if, however, 
 this portion of the skin deserves that name) when opaque, renders the globe of the 
 eye, in other respects imperfect, absolutely useless. This is observed in the kind of 
 eel called, in books of natural history, rmirena ccecilia : the gastrobranchus emeus is 
 
 blind from the same circumstance (Richerand). M. Ribes is of opinion that it 
 
 terminates at the circumference of the cornea.
 
 270 OF THE GLOBE OF THE EYE. 
 
 straight, or horizontal portion unites with the curved part, there are 
 situated two small tubercles, at the top of each of which there is a 
 minute orifice. These are the puncta lachrymalia, and they are called 
 superior and inferior, according to the palpebrse to which they belong. 
 In 'the dead body the puncta do not 'appear tubercular, the small bul- 
 gings, produced doubtless by a state of orgasm and of vital erection, 
 collapse at the approach of death. These small apertures, directed 
 inward and backward, are incessantly immersed in the accumulated 
 tears, absorb them, and convey them into the lachrymal sac by means 
 of the lachrymal ducts, of which they are the external orifices. The 
 absorption of the tears, and their flow into a membranous reservoir 
 lodged in the groove formed by the os unguis, do not depend on the 
 capillary attraction of the lachrymal ducts ; each of them, endowed 
 with a peculiar vital action, takes up, by a real process of suction, the 
 tears accumulated in the lacus lachrymalis, and determines their flow 
 into the sac. The weight of the fluid, the effort of the columns which 
 succeed each other, co-operate with the action of the parietes of the 
 duct. The flow of the tears is further facilitated by the compression 
 and slight concussions attending the contractions of the palpebral 
 fibres of the orbicularis, behind which the lachrymal ducts are 
 situated. 
 
 The vitality of the puncta lachrymalia and of the ducts is readily 
 discovered when we attempt to introduce into them Anel's syringe or 
 Mejean's stylet, to remove slight obstructions of the lachrymal pas- 
 sages. In a child now under my care for a mucous obstruction of the 
 nasal duct, I can see the puncta lachrymalia contract, when the extre- 
 mity of the syphon does not at once enter the canal. One is then 
 obliged to wait, before it can be introduced, for a cessation of the 
 spasmodic contraction, which lasts but a few moments. The tears 
 which flow into the lachrymal sac by the common orifice of the united 
 puncta lachrymalia, never accumulate within it, except in case of mor- 
 bid obstruction ; they, in that case at once enter into the nasal duct, 
 which is a continuation of it, and fall into the nasal fossae below the 
 anterior part of the inferior turbinated bones of these cavities. There 
 they unite with the mucus of the nose, increase its quantity, render 
 it more fluid, and change its composition. The use of the tears is to 
 protect the eye-ball against the irritating impression of the immediate 
 contact of the atmosphere. They at the same time favour the sliding 
 of the palpebree, lessen the friction in those parts and in the eye-ball, 
 and thus promote their motion. 
 
 CXVII. Of the globe of the eye. The eye-ball, as was already 
 observed, may be considered as a dioptrical instrument, placed before 
 the retina, whose office it is to refract the luminous rays, and to collect 
 them into one fasciculus, that may strike a single point of the nervous
 
 OF THE GLOBE OF THE EYE. 271 
 
 membrane exclusively calculated to feel its impression. An outer, 
 membranous, hard, and consistent covering supports all its parts. 
 Within the first membrane, called the sclerotic, lies the choroid, a 
 darkish coat, which lines the inside of the sclerotic, and forms the eye 
 into a real camera obscura.* At the anterior part of the globe there 
 is a circular opening in the sclerotic, in which the transparent cornea is 
 inserted. At about the distance of a twelfth part of an inch from 
 this convex segment, received in the anterior aperture of the sclerotica, 
 lies the iris, a membranous partition, placed perpendicularly, and con- 
 taining a round opening (the pupil), which dilates or contracts, accord- 
 ing to the state of dilatation or contraction of the iris. 
 
 At the distance of about half a line from the back part of the iris, 
 towards the union of the anterior fourth of the globe of the eye with the 
 posterior three-fourths, opposite to the opening of the pupil, there is 
 situated a lenticular body, enclosed in a membranous capsule, immov- 
 ably fixed in its situation by adhering to the capsule of the vitreous 
 humour. 
 
 Behind the crystalline lens the posterior three-fourths of the cavity 
 pf the eye contain a viscid transparent humour, enclosed in the cells 
 of a remarkably fine capsule, called hyaloid. This vitreous humour 
 forms about two-thirds of a sphere, from which the anterior segment 
 had been taken out; the pulpous expansion of the optic nerve, the 
 retina, is spread out on its surface so as to be concentrical to the choroid 
 and sclerotic coats. 
 
 The eye-ball being nearly spherical, the length of its different dia- 
 meters differs but little. The diameter of the eye, from the fore to the 
 back part, is between ten and eleven lines ; the transverse and vertical 
 diameters are somewhat shorter. Within the space measured by the 
 diameter from the fore to the back part, there are situated, taking them 
 in their order from the fore part, the cornea ; the aqueous humour con- 
 tained in the anterior chamber ; the iris, and its central opening or 
 pupil ; the aqueous humour of the posterior chamber ; the crystalline 
 
 * Gmelin (Schweigger's Journ. vol. x. p. 507) made an interesting set of expe- 
 riments in order to determine the composition of the black pigment which lines the 
 choroid coat of the eye. 
 
 " Its colour," he informs us, " is blackish-brown ; it is tasteless, and adheres 
 to the tongue like clay ; is insoluble in water, alcohol, ether, oils, lime-water, and 
 distilled vinegar. It dissolves in potash and ammonia when assisted by heat, and 
 is again precipitated by acids. Sulphuric acid dissolves it, and changes its colour to 
 reddish-brown. When distilled, it yields water, a brown oil, and carbonate of 
 ammonia. It gives out at the same time carburetted hydrogen, carbonic oxide, 
 azotic and oxygen gases. The coal remaining in the retort consists almost entirely 
 of charcoal." Mich. Mondini (Osservaz. sull nero pigmento dell' occhio, &c.) con- 
 tends that the dark colour of this pigment is owing to the presence in it of the oxide 
 of iron. J. C.
 
 272 OF THE HUMOURS OF THE EYE- 
 
 lens, surrounded by the ciliary processes ; then the vitreous humour in 
 its capsule ; and behind those transparent parts of the eye, through which 
 the luminous rays pass in approaching to a perpendicular, are the 
 retinae, which receive the impression ; the choroid, whose black point 
 absorbs the rays that pass through the thin and transparent retina ; and 
 the sclerotic, in which there is an opening for the passage of the optic 
 nerve to the globe of the eye. 
 
 The cornea, contained in the anterior aperture of the sclerotica, like 
 the glass of a watch-case within its frame, is about the third of a line 
 in thickness ; it forms at the fore-part of the eye the segment of a 
 smaller sphere, behind it lies the aqueous humour, which fills what are 
 called the chambers of the eye ; these form spaces, divided into ante- 
 rior and posterior ; the former, which is the larger of the two, bounded 
 by the cornea at the fore part, and by the iris at the back part ; the 
 latter, which is smaller, and separates the crystalline humour from the 
 iris, the posterior part of which, covered by a black pigment, is called 
 the uvea* The specific gravity of the aqueous humour does not 
 much exceed that of distilled water ; some have even thought it less ; 
 it is albuminous, and holds in solution several saline substances, f The 
 
 * Some anatomists have doubted the existence of the posterior chamber of the 
 eye ; but to be convinced of its existence, one need but to freeze an eye, when 
 there will be found a piece of ice between the crystalline lens and the uvea. 
 The formation of this icicle is not owing to the admission, through the opening of 
 the pupil, of the aqueous humour, which, like all other fluids, expands considerably 
 on freezing ; for, the expansion of fluids on their freezing being proportioned to 
 their bulk, the vitreous humour, which freezes at the same time as the aqueous, 
 must prevent its retrograde flow through the pupil. Lastly, the uvea or posterior 
 part of the iris is covered with a black point, which is easily detached from it : now, 
 if the anterior part of the crystalline lens had been in immediate contact with 
 it, it would have been soiled by some of this colouring matter, which would have 
 tarnished its natural transparency, indispensable to perfect vision. It is, there- 
 fore, undeniable, that there does exist a posterior chamber, which is to the ante- 
 rior in the proportion of two to five, and containing about two-fifths of the aqueous 
 humour, the whole of which is estimated at five grains, and that the iris forms a 
 loose partition between the two portions of the aqueous humour in which the dark 
 pigment of the uvea is insoluble. The aqueous humour appears to be the pro- 
 duct of arterial exhalation ; it is soon re-produced, as we see after the operation for 
 cataract. 
 
 4- The aqueous humour Specific gravity 1 -090 at a temperature of 60. From 
 
 various recent experiments it appears to be water slightly impregnated with 1st, 
 Albumen ; 2d, Gelatine ; 3d, Muriate of soda. Its constituents, according to the 
 analysis of Berzelius, are : 
 
 Water 98-10 
 
 Albumen a trace. 
 
 Muriates and lactates 1*15 
 
 Soda, with animal matter soluble only in water "75 
 
 100-00 /. C.
 
 OF THE HUMOURS OF THE EYE. 273 
 
 crystalline, enclosed in its membranous and transparent capsule, is a 
 lenticular body, rather solid than fluid ; its consistence is particularly 
 great towards its centre; it there forms a kind .of nucleus, around 
 which are several concentric layers, whose density diminishes as they 
 approach the surface, where the external layers, truly fluid, form what 
 Morgagni considered as a peculiar liquid, on which the lens might be 
 nourished by a kind of imbibition. This body, composed of two seg- 
 ments' of unequal convexity, about two lines in thickness at its centre, 
 consists of an albuminous substance coagulable by heat and alcohol. 
 Extremely minute arteries, given off by the central artery of Zinn, pass 
 through the vitreous humour, and bring to it the materials of its 
 growth and reparation.* 
 
 The vitreous humour, so called from its resemblance to melted glass, 
 is less dense than the crystalline, and more so than the vitreous, and is 
 in considerable quantity in the human eye : it appears to be secreted 
 by the minute arteries which are distributed to the parietes of the mem- 
 brane of the vitreous humour ; it is heavier than common water, some- 
 what albuminous and saltish. f 
 
 The sclerotica is a fibrous membrane, to which the tendons that 
 move the globe of the eye are attached ; it supports all the parts of 
 
 * The crystalline lens Its specific gravity is 1-100. When fresh it has little 
 
 taste. It putrefies very rapidly. It is almost completely soluble in water. The solu- 
 tion is partly coagulated by heat, and gives a copious precipitate with tannin, both 
 before and after the coagulation. Its composition, according to the analysis of 
 Berzelius, is as follows : 
 
 Water 58'0 
 
 Peculiar matter 35-9 
 
 Muriates, lactates, and animal matter soluble in alcohol. . . 2*4 
 
 Animal matter soluble only in water with some phosphates 1*3 
 
 Portions of the remaining insoluble cellular membrane ... 2-4 
 
 100-0 
 
 The peculiar matter of the lens possesses all the chemical characters of the 
 colouring matter of the blood, except colour. When burnt it leaves a little ash, 
 containing a very small portion of iron. When its solution in water is coagulated 
 by boiling, the liquid in which the coagulum was formed reddens litmus, containing 
 free lactic acid. (Ann. of Phil. vol. xi. p. 385.) J. C. 
 
 f- The vitreous humour possesses the same properties as the aqueous; even its 
 specific gravity is the same, or only a very little greater. Its constituents, according 
 to the analysis of Berzelius, are : 
 
 Water 98-40 
 
 Albumen -16 
 
 -"Muriates and lactates 1'42 
 
 Soda, with animal matter soluble only in water -02 
 
 10000. .J. C.
 
 274 OF THE SEAT OF VISION. 
 
 that organ, and these collapse and decay whenever the continuity of 
 its external covering is destroyed. The use of the choroid is not so 
 much to afford a covering to the other parts, as to present a dark 
 surface, destined to absorb the luminous rays, when they have pro- 
 duced on the retina a sufficient impression. If it were not for the 
 choroid, the light would be reflected ; after having impinged on the 
 nervous membrane, its rays would cross, and produce only indistinct 
 sensations. Mariotte thought that the choroid was the immediate seat 
 of vision, and that the retina was only its epidermis. This hypothesis 
 would never have obtained so much celebrity, if, besides the objections 
 that analogy might have furnished against it, there had been adduced, 
 in opposition to it, the fact observed in fishes, in which the choroid is 
 separated from the retina by a glandular body, opaque, and incapable 
 of transmitting the luminous rays. The retina loses its form as soon 
 as it is separated from the vitreous humour, or from the choroid coat, 
 between which it is spread out as a very thin capsule, so soft as to be 
 almost fluid. A number of blood-vessels, from the central artery of 
 Zinn, are distributed on the nervous substance of the retina, and give 
 it a slight pink colour. Ought we, with Boerhaave, to attribute to 
 aneurismal or varicose enlargements of those small vessels, the spots 
 which are seen in objects, in the disease to which Maitre Jean gave 
 the name of imaginations? In order to form the retina, the optic 
 nerve (which proceeds to the globe *>f the eye, by piercing the 
 sclerotica, to which the covering given to that nerve by the dura mater 
 is connected) penetrates through a very thin membrane, perforated 
 by a number of small holes ; and, closing the opening left for the 
 nerve, and which belongs as much to the choroid as to the sclerotic 
 coats, it then spreads out to furnish the expansion which lines the 
 concavity of the choroid, and covers over the convex surface of 
 the vitreous humour.* The whole extent of the retina, which is 
 
 * The optic nerves differ very remarkably from the other cerebral pairs, both 
 in their thickness, and in the delicacy of their substance, which appears to be an 
 immediate continuation of the medullary fibres of the brain, to which the meninges 
 furnish one common envelope, and not a distinct membranous canal for each fibre. 
 
 The nerves of vision cross each other before the cella turcica, in a manner 
 similar to the primitive crossing, which their roots, as well as those of the other 
 nerves, undergo in the substance of the brain. These double decussations may be 
 said to neutralise each other ; and, consequently, each optic nerve may be considered 
 to arise primarily from the hemisphere corresponding to the eye which it supplies. 
 In hemiplegia, the affected eye is not on that aide of the body struck with the 
 paralysis, it is on the opposite side that the pupil is dilated ; and this pathological 
 phenomenon, which is easily proved in persons who have experienced a paralytic 
 seizure, seems to be one of the best proofs which can be opposed to those who 
 suppose that the optic nerves, where they approach each other, experience an 
 approximation of their fibres only. It may be farther argued, in support of the 
 actual decnssation of these nerves, that the wasted optic nerve of an eye that has
 
 OF THE MECHANISM OF VISION. 275 
 
 equally nervous and sentient, may receive the impression of the lu- 
 minous rays ; though this faculty has, by several philosophers, been 
 exclusively assigned to its central part, called the optical axis, or 
 porus opticus. This central part is easily recognised in man by a 
 yellow spot discovered by Soemmering ; in the middle of this spot, 
 situated at the outer side of the entrance of the optic nerve into the 
 globe of the eye, there is seen a dark spot, and a slight depression, the 
 use of which is not understood. This peculiar structure is met with 
 only in the eye of man and of monkeys.* 
 
 CXIX. Mechanism and phenomena of vision. The rays of light 
 passing from any point of an enlightened object form a cone, of which 
 the apex answers to the point of the object, and of which the base 
 covers the anterior part of the cornea. All the rays, more diverging, 
 which fall without the area of the cornea on the eye-brows, the 
 eye-lids, and the sclerotica, are lost to vision. Those which strike the 
 mirror of the eye pass through it, under a refraction proportioned to 
 the density of the cornea, which much exceeds that of the atmosphere, 
 and to the convexity of that membrane ; approaching the perpendicular, 
 they now pass through the aqueous humour, less dense, and fall upon 
 the membrane called the iris. All those that fall upon this membrane 
 are reflected, and shew its colour different in different persons, and ^/ , > 
 apparently depending on the organic texture, and on the particular 
 and very diversified arrangement of the nerves, of the vessels, and, . ,-f?" 
 cellular tissue, which enter into its structure. None but the mostf^ 
 central traverse the pupil and serve to sight. These will pass that 
 opening, in. greater or less number, as it is more or less dilated. Now, ' - ^C^-i 
 the pupil is enlarged or diminished by the contraction or expansion of 
 the iris. The motions of this membrane depend entirely on the 
 manner in which light affects the retina. The iris itself is insensible 
 to the impression of the rays of light, as Fontana has proved, who 
 always found it immovable when he directed on it alone the luminous 
 rays. When the retina is disagreeably affected by the lustre of too 
 strong a light, the pupil contracts, to give passage only to a smaller 
 number of rays : it dilates, on the contrary, in gloom, to admit enough 
 to make the requisite impression on the retina. 
 
 To explain the motions of the iris, it is not necessary to admit 
 that muscular fibres enter into its structure \\ it is enough to know 
 
 been for some time in a state of atrophy, can be traced towards the opposite lobe of 
 the bruin ; and that an evident crossing of the optic nerves may be observed in 
 many of the class of fishes J. C. 
 
 * See APPENDIX, Note E E. \^ 
 
 f Some anatomists contend, and we think justly, that two sets of muscular 
 fibres enter into the structure of the iris ; the one radiant, and the other orbicular. 
 Amongst those who have lately argued in support of this position, we may mention
 
 276 OF THE STRUCTURE AND MOTIONS OF THE IRIS. 
 
 its vascular, spongy, and nervous texture; the irritation of the retina 
 sympathetically transmitted to the iris determines a more copious afflux 
 of humours ; its tissue dilates and stretches, the circumference of the 
 pupil is pushed towards the axis of this opening, which becomes con- 
 tracted by this vital expansion of the membranous tissue. When the 
 irritating cause ceases to 'act, by our passing from light into darkness, 
 the humours flow back into the neighbouring vessels, the membrane of 
 the iris returns upon itself, and the pupil enlarges the more as the 
 darkness is greater. 
 
 The rays admitted by the pupil pass through the aqueous humour 
 of the posterior chamber, and soon meet the crystalline, which power- 
 fully refracts them, both from its density and its lenticular form. 
 Brought towards the perpendicular by this body, they pass on towards 
 the retina through the vitreous humour, less dense, and which preserves, 
 without increasing it, the refraction produced by the crystalline lens. 
 The rays, gathered into one, strike en a single point of the retina, 
 
 M. Maunoir of Geneva, and M. Edwards. Some anatomists consider the iris to 
 be a tissue sui generis; whilst others rank it among the erectile structures. It 
 appears to us, that those who deny muscularity to this part, do so in consequence of 
 a mistaken idea, which seems to be too generally adopted, viz. that no part is 
 really muscular but that which possesses fibres of a similar appearance to those 
 which perform the function of voluntary motion. It should, however, be kept in 
 recollection, that involuntary muscles those fibrous textures which receive only 
 nerves proceeding from the ganglia, which are not supplied with voluntary nerves, 
 and which are consequently not directly influenced by the will differ very 
 essentially from voluntary muscles in their structure. Indeed muscular textures 
 vary not only in their functions, but even in their external characters, according as 
 they are more or less plentifully supplied with either class of nerves the cerebral 
 or ganglial. The structure also of muscular parts, especially those which are 
 removed from the influence of volition, has some relation to the kinds of irritants by 
 which they are designed to be influenced by Nature. Thus, the eye being formed 
 with an intimate relation to the functions which it has to perform, and to the 
 external influences which act on it, possesses in the structure of its iris a muscular 
 texture of peculiar delicacy; and hence it is more sensible to the irritations which 
 accompany, and are subservient to, the right performance of this important 
 animal function. 
 
 If the structure of the iris, the number of the soft and delicate nervous fibrils 
 which proceed to it from the lenticular ganglion and the nasal branch of the fifth 
 pair, and the connexion which they form with the retina in their course, be kept 
 in view, we shall readily be able to comprehend the procession of phenomena which 
 lead to the motions of the iris. It is not improbable, that the nervous fibrils 
 proceeding from the ganglion to the iris, form, with the capillary arteries which 
 supply its cellular texture, that particular organisation which may be considered as 
 muscular ; or, in other words, that these ganglial nerves terminating conjunctly 
 with capillary ramifications in the delicate cellular substance of the iris, constitute 
 by such a disposition its particular structure, and enable it to perform its peculiar 
 functions. Hence it will be seen, that impressions made upon the retina, (in the 
 sensible state of that nervous expansion, and in proportion to the extent of its
 
 OF THE I1US. 277 
 
 and produce the impression which gives us the idea of certain pro- 
 perties of the body which reflects them. As. the retina embraces the 
 vitreous humour, it presents a very extensive surface to the contact of 
 the rays, which enables us to behold at once a great diversity of 
 objects variously situated towards us, even when we or these objects 
 change our relative situation.* The luminous rays refracted by the 
 transparent parts of the eye, form therefore in the interior of the 
 organ a cone, of which the base covers the cornea, and applies to that 
 
 sensibility), and transmitted to the iris, by means of the connexion which exists 
 between the retina and the nerves supplying the iris, cause a contraction of its 
 circular fibres : as soon as such impressions cease, these fibres relax, and the 
 comparative action in the circular and radiated fibres, giving rise to certain states 
 of pupil, is relative to the conditions of the nervous system, and the extent to which 
 the irritation proceeds along the axis of the nerves and vessels, and affects either 
 set of fibres. 
 
 According to this view of the subject, compression of the brain, or an insensible 
 state of the optic neirve, is followed by expansion of the pupil, because the impression 
 requisite to contraction of the orbicular fibres cannot be made, unless occasionally to 
 a small extent, owing to the loss of sensibility ; and, consequently, the greater tonic 
 power of the antagonist (the radiated) fibres predominates in preserving a perma- 
 nently dilated state of the pupil. The pupil is also dilated in weak children, and in 
 those afflicted with worms, conformably to what is generally observed in the 
 animal economy, namely, that all orbicular muscles, when no adjoining irritation 
 exists, evince a greater or less degree of relaxation as the vital energies are 
 more or less diminished. It would appear that, in a debilitated state of the sys- 
 tem, the nervous influence proceeding from the lenticular ganglion is insufficient 
 to the purpose of exciting fully the orbicular fibres of the iris ; and at the same time 
 the retina perhaps possesses that low degree of sensibility to the irritation of light 
 which is followed by an inadequate effect upon the nerves supplying the iris. 
 Indeed, it seems, under the circumstances just referred to, where irritation gene- 
 rally is present in the abdominal viscera, that nervous influence is secreted in the 
 brain and parts adjoining in an insufficient manner, and consequently the di- 
 minished activity of the cerebral and ganglial nerves supplying the various struc- 
 tures of the eye is the .result. When, however, irritation exists in the brain, or 
 when an increase of the circulation occurs in that organ, without overwhelming its 
 powers, accompanied with or preceded by debility, the pupil contracts, or even 
 remains contracted ; because, in consequence of such irritation or increase of circu- 
 lation in the brain and connected parts, the sensibility and nervous activity are 
 heightened J. C. 
 
 * The rays of light may be said to penetrate or traverse the demi-transparent 
 tissue of the retina, and, as it were, to search through the nervous pulp when they 
 arrive at the choroid coat, which is designed in a great measure to absorb these rays. 
 Does any intimate combination take place between the nervous pulp and the light, 
 which may give rise to that sensation which follows a violent compression of the 
 globe of the eye in an obscure situation ? The spots which are observable, after 
 having had the eye fixed for a considerable time on certain coloured objects, do 
 they arise from this sort of an impregnation of the retina, or rather of a portion of 
 it with the rays of light ? or, as is more generally believed, has the sensibility of the 
 retina become partially increased or diminished by the circumstance of inaction or 
 of exercise ?
 
 278 OF THE PHENOMENA OF VISION- 
 
 of the external luminous cone, whilst its apex is on some point of the 
 retina. It is conceived, generally, that the luminous cones, issuing 
 from all points of the object beheld, cross in their passage through the 
 eye, so that the object is imaged on the retina reversed. Admitting 
 this opinion, established on a physical experiment, we have to inquire 
 why we see objects upright, whilst their image is reversed on the 
 retina ? The best explanation we possess of this phenomenon we owe 
 to the philosopher Berkeley, who proposed it in his English work, 
 entitled Theory of Vision, SfC. In his opinion, there is no need of 
 the touch to correct this error into which sight ought to betray us. 
 As we refer all our sensations to ourselves, the uprightness of the 
 object is only relative, and its inversion really exists at the bottom of 
 the eye. 
 
 By the point of distinct vision is understood the distance at which 
 we can read a book of which the characters are of middling size, or 
 distinguish any other object equally small. This distance is not con- 
 fined within very narrow limits, since we can read the same book at 
 six inches from the eye, or at five or six times the distance. Thjs 
 faculty of the eyes to adapt themselves to the distance and the small- 
 ness of objects, cannot depend, as has been fondly repeated, on the 
 lengthening or shortening of the globe of the eye by the muscles that 
 move it. Its four recti muscles are not, in any case, capable of com- 
 pressing it on its sides, nor of lengthening it by altering its spherical 
 form : their simultaneous action can only sink the ball in its socket, 
 flatten it from the fore to the back part, diminish its depth, and make 
 the refraction consequently less powerful when objects are very distant 
 or very small : this last effect even might be disputed. The eye, 
 which moves and rests on the adipose cushion that fills the bottom 
 of the socket, is never strongly enough pressed to lose its spherical 
 figure, which, of nil the forms that bodies can be invested in, is that 
 which, by its especial nature, best resists alteration. The extremities 
 of the ciliary processes, which surround the circumference of the 
 crystalline lens, cannot act on this transparent lens, compress, nor 
 move it; for these little membranous folds, of which the aggregate 
 composes the irradiated disk, known under the name of corpus ciliare, 
 possessing no sort of contractile power, arc incapable of moving the 
 crystalline lens, with which their extremities, lying in simple contiguity, 
 have no adherence, and which, besides, is immovably fixed in the 
 depression it occupies by the adhesions of its capsule with the mem- 
 brane of the vitreous humour. The various degrees of contraction 
 or dilatation of which the eye-ball is susceptible, afford a much more 
 satisfactory explanation of this physiological problem. 
 
 The rays of light which come from a very near object are very 
 divergent : the eye would want the refracting power necessary to
 
 OF THE PHENOMENA OF VISION. 279 
 
 collect them into one, if the pupil, contracting by the enlargement of 
 the iris, did not throw off the more divergent rays, or those which form 
 the circumference of the luminous cone. Then those which form the 
 centre of the cone, and which need but a much smaller refraction for 
 their reunion on a single point of the retina, are alone admitted by the 
 narrowed opening. When, on the contrary, we look at a distant 
 object from which rays are given out, already very convergent, and 
 which need but a small refraction to bring them towards the perpen^ 
 dicular, we dilate the pupil, in order to admit the more diverging rays, 
 which, when collected, will give the image of the object. In this 
 respect very small bodies are on the same footing as those at a great 
 distance. 
 
 Though the image of every object is traced at the same time in 
 both our eyes, we have but one sensation, because the two sensations 
 are in harmony and are blended, and serve only, one aiding the other, 
 to make the impression stronger and more durable. It has long been 
 observed, that sight is more precise and correct when we use only one 
 eye ; and Jurine thinks that the power of the two eyes united exceeds 
 only by one-thirteenth that of a single eye. The correspondence of 
 affection requires the direction of the optical axes on the same objects ; 
 and, be that direction ever so little disturbed, we see really double, which 
 is what happens in squinting. 
 
 If the eyes are too powerfully refractive, either by the too great 
 convexity of the cornea and the crystalline, the greater density of the 
 humours, or the excessive depth of the ball, the rays of light, too soon 
 reunited, diverge anew, fall scattering on the retina, and yield only a 
 confused sensation. In this defect of sight, called myopia, the eye 
 distinguishes only very near objects, giving out rays of such extreme 
 divergence as to require a very powerful refractor. In presbytia, on 
 the other hand, the cornea too much flattened, the crystalline little 
 convex, or set too deeply, the humours too scanty, are the cause that 
 the rays are not yet collected when they fall upon the retina, so that 
 none but very distant objects are distinctly seen, because the very* 
 convergent rays they give out have no need of much refraction. 
 
 Myopia is sometimes the effect of the habit which some children 
 get of looking very close at objects which catch their attention. The 
 pupil then becomes accustomed to great constriction, md dilates after- 
 wards with difficulty. It is obvious, that to correct this vicious disposi- 
 tion, you must shew the child distant objects which will strongly engage 
 his curiosity, and keep him at some distance from every thing he 
 looks at. 
 
 The sensibility of the retina on some occasions rises to such excess 
 
 * The author means " scarcely divergent." T.
 
 280 OF THE PHENOMENA OF VISION'. 
 
 that the eye can scarcely bear the impression of the faintest light. 
 Nyctalopes, such is the name given to those affected with this disorder, 
 distinguish objects amidst the deepest darkness : a few rays are suf- 
 ficient to impress their organ. 
 
 It is related that an English gentleman, shut up in a dark dungeon, 
 came gradually to distinguish all it contained : when he returned to 
 the light of day, of which he had in some sort lost the habit, he could 
 not endure its splendour ; the edges of the pupil, before extremely 
 dilated, became contracted to such a degree as entirely to efface the 
 opening. 
 
 When, on the other hand, the retina has little sensibility, strong 
 daylight is requisite to sight. This injury of vision, known by the 
 name of hemeralopia* may be considered as the first step of total 
 paralysis of the optic nerve, or gutta serena. It may arise from any 
 thing that can impair the sensibility of the retina. Saint-Yves relates, 
 in his work on diseases of the eyes, many cases of hemeralopia. The 
 subjects were chiefly workmen employed at the Hotel des Monnoies, 
 in melting the metals. The inhabitants of the northern regions, 
 where the earth is covered with snow great part of the year, become 
 at an early age hemeralopes. Both contract this weakness from 
 their eyes being habitually fatigued by the splendour of too strong 
 a light. 
 
 Finally, in order to the completion of the mechanism of vision, it 
 is requisite that all parts of the eye be under certain conditions, the 
 want of which is more or less troublesome. It is especially necessary 
 that the membranes and the humours which the rays of light are to 
 pass through should be perfectly transparent. Thus, specks of the 
 cornea, the closing of the pupil by the preservation of the membrane 
 which stops that opening during the first months of the life of the 
 foetus ; cataract, an affection which consists in the opacity of the 
 crystalline lens or its capsule ; the glaucoma, or defect of transparency, 
 in the vitreous humour, weaken or altogether destroy sight, by im- 
 peding the passage oflhe rays to the retina. This membrane itself 
 must be of tempered sensibility to be suitably affected by the contact of 
 the rays of light. -The choroid, the concavity of which it fills, must 
 present a coating black enough to absorb the rays that pass through it. 
 
 * I give to the words nyctalopia and hemeralopia the same meaning as all other 
 writers down to Scarpa, who- have published treatises on diseases of the eyes. 
 This acceptation is, however, a grammatical error ; since, of the two terms, nycta- 
 lopia, in its Greek roots, signifies an affection which takes away sight during the 
 night ; and hetneralopia, one in which it is lost during the day. It is accordingly 
 in this sense that they are used by the father of physic. I owe this remark to 
 Dr. Roussille Chamseru, who has carefully verified the text of Hippocrates, in the 
 MSS. of the Imperial Library.
 
 OF THE PHENOMENA OF VISION. 281 
 
 It is to the sensible decay of the dye of the choriod in advancing years, 
 as much as to the collapsing induration and discolouring of different 
 parts of the eye, and the impaired sensibility of the retina from long use, 
 that we ascribe the confusion and weakness of sight in old people. The 
 extreme delicacy of the eyes of the Albinos proves equally the necessity 
 of the absorption of light by the black coating which covers the 
 choroid. 
 
 Of all the organs of sense, the eyes are those which are the most 
 developed in a new-born child ; they have then nearly the bulk 
 which they are to retain during life. Hence it happens, that the 
 countenance of children, whose eyes are proportion ably larger, is 
 seldom disagreeable, because it is chiefly in these organs that phy- 
 siognomy seeks expression. Might we not say, that if Nature sooner 
 completes the organ of sight, it is because the changes which it pro- 
 duces on the rays of light arising purely from a physical necessity, 
 the perfection of the instrument was required for the exercise of the 
 sense ? 
 
 The eyes are not immovable in the place they occupy. Drawn 
 into very various motions, by four recti muscles and two oblique, 
 they direct themselves towards all objects of which we wish to take 
 cognizance : and it is observed, that there is, between the muscles 
 which move the two eyes, such a correspondence of action, that these 
 organs turn at once the same way, and are directed at once towards 
 the same object, in such a manner that the visual axes are exactly 
 parallel. It sometimes happens that this harmony of motion is dis- 
 turbed, and thence squinting, an affection which, depending almost 
 always on the unequal force of the muscles of the eye, may be distin- 
 guished into as many species as there are muscles which can draw the 
 globe of the eye into their direction, when from any cause they become 
 possessed of a predominating power. Buffon has further assigned as 
 a cause of squinting, the different aptitude of the eyes to be affected 
 by light. According to this celebrated naturalist, it may happen, that 
 one of the eyes being originally of greater sensibility, the child will 
 close the weaker to use the stronger, which is yet strengthened by 
 exercise, whilst repose still weakens the one that remains in inaction. 
 The examination of a great many young people who had fallen under 
 military conscription, and claimed exemption on the score of infirmi- 
 ties, has shewn me that squinting is constantly connected with the 
 unequal power of the eyes. Constantly, the inactive eye is the 
 weakest, being almost useless ; and it was quite a matter of necessity 
 that the diverging globe should be thus neutralised, else the image it 
 would have sent to the brain, different from that which the sound 
 eye gives, would have introduced confusion into the visual functions.
 
 282 OF VISION IN THE LOWER ANIMALS. 
 
 The squinting eye, being inactive, falls by degrees into that state of 
 debility, from default of exercise, which Brown has so well called 
 indirect debility. 
 
 The sense of sight appears to me much rather to deserve the 
 name which J. J. Rousseau has given to that of smell, of sense of 
 the imagination. Like that brilliant faculty of the soul, the sight, 
 which furnishes us with ideas so rich and varied, is liable to betray 
 us into many errors. It may be doubted whether it gives the notion 
 of distance, since the boy couched by Cheselden conceived every thing 
 he saw to touch his eye. It exposes us to false judgments on the 
 form and size of objects ; since, agreeably to the laws of optics, 
 a square tower seen at a distance appears to us round ; very lofty 
 trees seen also very far off, seem no taller than the shrubs near us ; 
 a body moving with great rapidity appears to us motionless, &c. 
 It is from the touch that we gain the correction of these errors, 
 which Condillac, in his treatise on sensation, has perhaps ex- 
 aggerated. 
 
 CXX. Of the organ of sight in the lower animals. The organ of 
 sight in different animals varies according to the medium in which 
 they live ; thus, in birds which fly in the higher regions of the air, 
 there is an additional and very remarkable eye-lid : this is particularly 
 the case with the eagle, which is thus enabled to look at the sun ; and 
 with night-birds, whose very delicate eye it seems to protect from the 
 effects of too strong a light. In birds, likewise, there is a copious 
 secretion of tears, the medium in which they live causing a con- 
 siderable evaporation. The greater part of fishes, on the contrary, 
 have no movable eye-lid, and their eyes are not moistened by tears, 
 as the water in which they are immersed answers the same purpose. 
 In some fishes, however, the eyes are smeared with an unctuous 
 substance calculated to prevent the action of the water on the organ. 
 
 The globe of the eye in birds is remarkable for the convexity of 
 the cornea, which is sometimes a complete hemisphere ; hence it pos- 
 sesses a considerable power of refraction. This power of refraction 
 appears to be very weak in fishes, the forepart of their eyes being 
 very much flattened ; but the water in which they live made it un- 
 necessary that they should have an aqueous humour, for the density 
 of this fluid being nearly the same as that of water, it would not 
 have produced any refraction ; besides, being in sea-fish of inferior 
 density to that of salt water, it would have broken the rays of light 
 by making them diverge from the perpendicular. In fact, the re- 
 fractive power of a medium is never but a relative quantity ; the degree 
 of refraction is not determined by the density of the medium, but by 
 the difference of density between it and the medium that is next to it.
 
 OF VISION IN THE LOWER ANIMALS. 283 
 
 To make up for the flatness of the cornea occasioned by the small 
 quantity, or even by the absence, of aqueous humour, fishes have a 
 very dense and spherical crystalline humour, the spherical part of 
 which forms a part of a small sphere. 
 
 The eyes of birds, whose cornea is thrust out by a very copious 
 aqueous humour, possess, in consequence of the presence of this fluid, 
 a very considerable power of refraction ; the air, in its higher regions, 
 owing to its extreme rarefaction, being but little calculated to approxi- 
 mate the rays of light. 
 
 The pupil admits of greater dilatation in the cat, in the owl, in 
 night-birds, and in general in all animals that see in the dark. The 
 sensibility of the retina is, likewise, greater in those animals ; seve- 
 ral of them appear incommoded by the light of day, and never pursue 
 their prey but in the most obscure darkness. 
 
 The crystalline humour of several aquatic fowls, as the cormo- 
 rant, is spherical like that of fishes; and this is not, as will be men- 
 tioned hereafter, the only peculiarity of structure in this kind of 
 amphibious animals. Lastly, the choroid of some animals, more 
 easily separated into two distinct laminae than that of man, presents, 
 at the bottom of the eye, instead of a darkish, uniformly diffused 
 coating, a pretty extensive spot of various colours, and in some it is 
 most beautiful and brilliant. It is not easy to say what is the use of 
 this coloured spot, known by the name of tapetum. 
 
 The rays of light reflected by this opaque substance, in passing 
 through the eye, cross those which are entering at the same time ; 
 they must, consequently, prevent distinct vision, or at least impair the 
 impression, in a manner which it is impossible to determine. It has 
 been said, that the lower animals, provided with less perfect and often 
 less numerous senses than those of man, must have different ideas of the 
 universe : is it not likewise probable, that in consequence of the indis- 
 tinct vision occasioned by the reflection from the tapetum, they may 
 entertain erroneous and exaggerated notions of the power of man ? And 
 notwithstanding the power granted to man by the Creator over the lower 
 animals, as we are told in the book of Genesis, is it probable that those 
 which Nature has gifted with prodigious strength, or with offensive 
 weapons, would obey the lord of the creation, if they saw him in his 
 feeble and destitute condition, in a word, such as he is? 
 
 The head of insects with numerous eyes is joined to their body, 
 and moves along with it : their existence is, besides, so frail, that it 
 was requisite that Nature should furnish them abundantly with the 
 means of seeing those objects which may be injurious to them. 
 We shall not enter any farther into these remarks relative to the dif- 
 ferences in the organ of sight in the various kinds of animals :
 
 284 OF SOUND. 
 
 more ample details on this subject belong, in an especial manner, to 
 comparative anatomy.* 
 
 CXXI. Of sound. Sound is not, like light, a body having a distinct 
 existence; we give the name of sound to a sensation which we ex- 
 perience whenever the vibrations of an elastic body strike our ears. 
 All bodies are capable of producing it, provided their molecules are 
 susceptible of a certain degree of re-action and resistance. When a 
 sonorous body is struck, its integrant particles experience a sudden 
 concussion, are displaced, and oscillate with more or less rapidity. 
 This tremulous motion is communicated to the bodies applied to its 
 surface : if we lay our hand on a bell that has been struck by its clap- 
 per, we feel a certain degree of this trembling. The air, which en- 
 velopes the sonorous body, receives and transmits its vibrations with 
 the more effect from being more elastic. Hence it is observed that, 
 cceteris jiaribus, the voice is heard at a greater distance in winter, 
 when the air is dry and condensed by the cold. 
 
 The sonorous rays are merely series of particles of air, along which 
 the vibration is transmitted from the sonorous body to the ear which 
 perceives the noise occasioned by its percussion. These molecules 
 participate in the vibrations which are communicated to them ; they 
 change their form and situation in proportion as they are nearer to 
 the body that is struck, and vice versa ; for, sound becomes weaker 
 in proportion to the increase of distance. But this oscillatory motion 
 of the aerial molecules should be well distinguished from that by 
 which the atmosphere, agitated by the winds, is transported and 
 changes its situation. And in the same manner as the balance of a 
 pendulum moves incessantly within the same limits, so this oscillatory 
 motion affects the molecules of the air within the space which they 
 occupy, so that they move to and fro during the presence or the absence 
 of the vibration. The atmospherical air, when set in motion in a con- 
 siderable mass at a time, produces no sound, unless in its course it 
 meets with a body which vibrates from the percussion which it expe- 
 riences. 
 
 The force of sound depends entirely on the extent of the vibrations 
 experienced by the molecules of the sonorous body. In a large bell 
 struck violently, the agitation of the molecules is such that they are 
 transmitted to considerable distances, and that the form of the body 
 is evidently changed by it. Acute or grave sounds are produced by 
 the greater or smaller number of vibrations in a given time, and the 
 vibrations will be more numerous the smaller the length and dia- 
 meter of the body. Two catgut strings, of the same length and thick- 
 
 * For some further remarks on the Organ and Sense of Vision, see APPENDIX, 
 Note E E.
 
 OF THE ORGAN OF HEARING- 285 
 
 ness, and with an equal degree of tension, will vibrate an equal number 
 of timesnn a given period, and produce the same sound. This, in music, 
 is called unison. If one of the strings is shortened by -one-half, it 
 vibrates as often again as the other, and gives out a sound more 
 acute, or higher by one octave. The same result may be obtained by 
 reducing the string one-half of its original thickness, without taking 
 from its length. The vibrations will, in the same manner, be accele- 
 rated by giving a greater degree of tension to the sonorous cord. 
 The difference of the sounds produced by a bass, a harp, or any 
 other stringed instrument, depends on the unequal tension, length, 
 and size of the strings. 
 
 This division of the elementary sound is an act of the understand- 
 ing, which distinguishes, in a noise apparently monotonous, innumer- 
 able varieties and shades, expressed by signs of convention. But in the 
 same manner as light, refracted by a prism, presents innumerable in- 
 termediate shades between the seven primitive colours, and as the 
 transition is gradual from one to the other of these colours ; so the 
 division of the primitive sound into seven tones, expressed by notes, 
 is not absolute, and there are a number of intermediate sounds which 
 augment or diminish their value, &c. 
 
 Sound has, therefore, been analysed as well as light : the use of 
 the ear with regard to sound corresponds to that of the prism with 
 regard to light ; and the modifications of which sound is capable are as 
 numerous and as various as the shades between the primitive colours. 
 
 Sound is propagated with less velocity than light. The report of 
 a cannon fired at a distance is heard only a moment after the eye has 
 perceived the flash of the explosion. Its rays diverge and are reflected, 
 like those of light, when they meet with an obstacle at an angle equal 
 to that of incidence. The force of sound, like that of light, may be 
 increased, by collecting and concentrating its rays. The sonorous rays 
 which strike a hard and elastic body, when reflected by it, impart to it 
 a vibratory motion, giving rise to a secondary sound, which increases 
 the force of the primitive sound. 
 
 When these secondary sounds, produced by the percussion of a 
 body at a certain distance, reach the ear, they give rise to what is 
 called an echo. Who is unacquainted with the ingenious allegory 
 by which its nature is expressed in ancient mythology, in which echo 
 was called daughter of the air and earth ? 
 
 CXXII. Of the organ and mechanism of hearing. The organ of 
 hearing in man consists of three very distinct parts ; the one, placed 
 externally, is intended to collect and to transmit the sonorous rays 
 which are modified in passing along an intermediate cavity, between 
 the external and internal ear. It is within the cavities of this third 
 part of the organ, excavated in the substance of the petrous portion
 
 286 OF THE ORGAN OF HEAUIXG. 
 
 of the bone, that the nerve destined to the perception of sound, 
 exclusively resides. The external ear and the meatus auditorius 
 externus may be compared to an acoustic trumpet, the broad part of 
 which, represented by the concha, collects the sonorous rays, which 
 are afterwards transmitted along the contracted part, represented by 
 the meatus externus. The concha contains several prominences 
 separated by corresponding depressions ; its concave part is not 
 wholly turned outward; in those who have not laid their ears flat 
 against the side of the head by tight bandages, it is turned slightly 
 forward, and this arrangement, favourable to the collection of sound, 
 is particularly remarkable in savages, whose hearing, it is well known, 
 is remarkably delicate. The base of the concha consists of a fibro- 
 cartilaginous substance, thin, elastic, calculated to reflect sounds, and 
 to increase their strength and intensity by the vibrations to which it is 
 liable. This cartilage is covered by a very thin skin, under which no 
 fat is collected that could impair its elasticity : these prominences are 
 connected together by small muscles, which may relax it by drawing 
 the projections together, and thus place it in unison with the acute or 
 grave sounds. These small muscles within the external ear, as the 
 musculi helicis major and minor, the tragicus and anti-tragicus, and 
 the transversus auris, are like the muscles on the outer part of the ear, 
 stronger and more developed in timid animals with long ears. In the 
 .hare the fibres of these muscles are most distinctly marked ; their action 
 is most apparent in this feeble and fearful animal, which has no resource 
 but in flight against the dangers which incessantly threaten its exist- 
 ence, and which required that it should receive early intimation of 
 the approach of danger : hence hares have the power of making their 
 ears assume various forms, of shaping them into more advantageous 
 trumpets, of moving them in every direction, of directing them towards 
 the quarter from which the noise proceeds, so as to meet the sounds 
 and collect the slightest. 
 
 The form of the external ear is not sufficiently advantageous in 
 man, whatever Boerhaave may have said to the contrary, to enable all 
 the sonorous rays, which in striking against it are reflected at an angle 
 equal to that of their incidence, to be directed towards the meatus 
 auditorius externus. United for the most part into a single fasciculus, 
 and directed towards the concha, they penetrate into the meatus audi- 
 torius externns, and the tremulous motions which they excite in its 
 osso-cartilaginous parietes contribute to increase their force. On 
 reaching the bottom of the meatus, they strike against the membrana 
 tympani, a thin and transparent septum, stretched between the bottom 
 of the meatus, and the cavity in which the small bones of the ear are 
 lodged. These small bones form a chain of bone which crosses the 
 tympanum from without inward, and which extends from the membrana
 
 OF THE SENSE OF HEARING. 287 
 
 tympani to that which connects the base of the stapes to the edge of 
 the fenestra ovalis. 
 
 An elastic air, continually renewed by the Eustachian tube, fills the 
 cavity of the tympanum ; small muscles attached to the malleus and 
 stapes move these bones, or relax the membranes to which they are 
 attached, and thus institute a due relation between the organ of hear- 
 ing and the sounds which strike it. It will be easily conceived, that 
 the relaxation of the membrana tympani, effected by the action of 
 the anterior muscle of the malleus, must weaken acute sounds ; while 
 the tension of the same membrane, by the internal muscles of the 
 same bone, must increase the force of the grave sounds. In the same 
 manner as the eye, by the contraction or dilatation of the pupil, 
 accommodates itself to the light, so as to admit a greater or smaller 
 number of its rays, according to the impression which they produce, so 
 by the relaxation or tension of the membrane of the tympanum, or of 
 the fenestra ovalis, the ear reduces or increases the strength of sounds, 
 whose violence would affect its sensibility in a painful manner, or 
 whose impression would be insufficient. The iris and the muscles of the 
 stapes and of the malleus are, therefore, the regulators of the auditory 
 and visual impression ; there is as close a sympathetic connexion 
 between these muscles and the auditory nerve as between the iris and 
 the retina. The air which fills the tympanum is the true vehicle of 
 sound; this air diffuses itself over the mastoid cells, the use of which 
 is to augment the dimensions of the tympanum, and the force and ex- 
 tent of the vibrations which the air experiences within it. 
 
 These vibrations, transmitted by the membrana tympani, are com- 
 municated to those membranes which cover the fenestra ovalis and the 
 fenestra rotunda ; then, by means of these, to the fluid which fills the 
 different cavities of the internal ear, and in which lie the soft and deli- 
 cate filaments of the auditory nerve, or of the portio mollis of the 
 seventh pair. 
 
 The agitation of the fluid affects these nerves, and determines the 
 sensation of grave or acute sounds, according as they are slower or 
 more rapid. It appears that the diversity of sounds should rather be 
 attributed to the more or less rapid oscillations, and to the undulations 
 of the lymph of Cotunni, than to the impressions on filaments of differ- 
 ent lengths of the auditory nerve. These nervous filaments are too 
 soft and too slender to be traced to their extreme terminations. It is, 
 however, probable, that the various forms of the internal ear (the semi- 
 circular canals, the vestibule, and the cochlea), have something to do 
 with the diversity of sounds. It must also be observed, that the 
 cavities of the ear are contained in a bony part, harder than any 
 other substance of the same kind, and well fitted to maintain, or even
 
 288 OF 'THE SENSE OF HEARING. 
 
 to augment by the re-action of which it is capable, the force of the 
 sonorous rays.* 
 
 The essential part of the organ of -hearing, that which appears 
 exclusively employed in receiving the sensation'of sounds, is, doubtless, 
 that which exists in all animals endowed with the faculty of hearing. 
 This part is the soft pulp of the auditory nerve, floating in the midst of 
 a gelatinous fluid, contained in a thin and elastic membranous cavity. 
 It is found in all animals, from man to the sepia. 'In no animal lower 
 in the scale of animation has an organ of hearing been met with, 
 although some of these inferior animals do not seern to be absolutely 
 destitute of that organ. This gelatinous pulp is in the lobster con- 
 tained in a hard and horny covering. In animals of a higher order its 
 internal part is divided into various bony cavities. In birds there is 
 interposed a cavity between that which contains the nerve of hearing 
 and the outer part of the head ; in man and in quadrupeds the organ 
 of hearing is very complicated; it is enclosed in an osseous cavity, 
 extremely hard, situated at a considerable depth, and separated from 
 the outer part of the head by a cavity and a canal, along which the 
 sonorous rays are transmitted, after having been collected into fasciculi 
 by trumpets situated on the outside. 
 
 This kind of natural analysis of the organ of hearing is well calcu- 
 lated to give accurate notions of the nature and importance of the 
 functions fulfilled by each of its parts. But in the investigation of the 
 uses and of the relative importance of the auditory apparatus, morbid 
 anatomy furnishes data of an equal value with those obtained from 
 comparative anatomy. 
 
 CXXIII. Pathological physiology of hearing. The external ear 
 may be removed with impunity in man, and even in animals in which 
 its form is more advantageous : the hearing is at first impaired, but at 
 the end of a few days recovers its wonted delicacy. The entire ob- 
 literation of the meatus auditorius externus is attended with complete 
 deafness. It is not essentially necessary for the mechanism of hearing that 
 the membrana tympani should be whole ; persons in whom it has been ac- 
 cidentally ruptured can force out smoke at their ears without losing the 
 power of hearing ; it may be conceived, however, that if, instead of 
 having merely a small opening that would not prevent its receiving the 
 impression of the sonorous rays, nor its being acted upon by the handle 
 of the malleus, the membrana tympani were almost entirely destroyed, 
 
 * If the cavities of the internal ear were hermetically sealed, it may be con- 
 ceived that the violent undulations of the lymph of Cotunni would injure the ner- 
 vous pulp ; but the most violent agitation of this fluid does not amount to such a 
 height, for it may flow towards the internal surfaces of the cranium by means of 
 the two small conduits named aqueducts. J. C.
 
 OF THE SENSE OF HEARIKG. 289 
 
 deafness would be the almost unavoidable consequence.* If, owing 
 to the obstruction of the Eustachian tube, the air in the tympa- 
 num is not renewed, jt loses its elasticity, and combines with the 
 mucus within the tympanum. The cavity of the tympanum is then 
 in the same condition as an exhausted receiver, in which the sonorous 
 rays are transmitted with difficulty. It has been thought that the use 
 of the Eustachian tube was, not only to renew the air contained in the 
 tympanum, but also to transmit the sonorous rays into that cavity. In 
 listening attentively, we slightly open our mouth ; in order, it is said, 
 that the sound may pass from this cavity into the pharynx, and thence 
 reach the organ of hearing. This explanation is far from satisfactory ; 
 for the obliteration of the meatus auditorius externus is attended with 
 complete deafness, which would not happen if the Eustachian tubes 
 transmitted the sonorous rays. When a man listens attentively, and with 
 his mouth open, the condyles of the lower jaw, situated in front of the 
 external auditory meatus, being depressed and brought forward, the 
 openings are evidently enlarged, as may be ascertained by putting the 
 little finger into one's ear, at the moment of depressing the lower jaw.f 
 The luxation of the small bones of the ear, or even their complete 
 destruction, does not occasion deafness; the only consequence is, aeon- 
 fusion in the perception of sounds. When, however, the stapes, the 
 base of which rests on the greatest part of the fenestra ovalis, or when 
 the thin membrane which closes the fenestra ovalis, or when that which 
 closes the fenestra rotunda, is destroyed, deafness takes place in conse- 
 quence of the escape of the fluid which fills the cavities in which the 
 auditory nerve is distributed. 
 
 The existence of this fluid appears essential to the mechanism of 
 hearing; either from its keeping the nerves in the soft and moist state 
 required for the purpose of sensation, or from its transmitting to them 
 the undulatory motion with which it is agitated. 
 
 The deafness of old people, which, according to authors, depends 
 on the impaired sensibility of the nerves, whose excitability has been 
 
 * We find that a temporary obstruction of the Eustachian tube in guttural 
 angina is sufficient to occasion a considerable degree of deafness. In such a case the 
 inflammation of the mucous membrane of the pharynx extends itself to that which 
 lines the tube, of which it is a continuation ; and the effects that the inflammation 
 produces on the function of the organ are proportionate to the extent to which it 
 advances in the different departments of the internal ear. J. C. 
 
 f The open state of the mouth in an attentive listener, by no means proves that 
 the sonorous rays are introduced along the Eustachian tube. Indeed, if such were 
 the case, the aerial pulsations arriving by this tube would strike the tympanum 
 in an opposite direction to those that are admitted by the external passage, and 
 thus render the hearing confused. The purpose, therefore, which the Eustachian 
 tube performs is nothing more than to allow the renewal of the air within the 
 tympanum J. C. 
 
 U
 
 290 OF ODOURS. 
 
 exhausted by impressions too frequently repeated, appears sometimes 
 to be occasioned by a deficiency of this humour, and by the want of 
 moisture in the internal cavities of the ear. During the severe winter 
 of 1798, Professor Pinel opened, $t the Hospital of Saltpetriere, the 
 skulls of several women who died at a very advanced age, and who had 
 been deaf for several years. The cavities of the internal ear were found 
 quite empty ; they contained an icicle in younger subjects who had pos- 
 sessed the power of hearing. 
 
 Deafness may likewise be produced by a palsy of the portio mollis 
 of the seventh pair, or by a morbid condition of the pail of the brain 
 from which this nerve arises. The mechanical explanation applied by 
 Willis to the anomalous affections of the organ of hearing, is inadmis- 
 sible, those in which that organ is sensible only to the impression of 
 weak or strong sounds acting together or separately. 
 
 This author relates the case of a woman who could not hear unless 
 a great noise was made near her, either by beating a drum or by ringing 
 a bell, because, says he, under such circumstances these loud noises 
 determine in the membrana tympani, which he supposes in a state of 
 relaxation, the degree of tension required to enable it to vibrate under 
 the impression of weaker sounds. This membrane, to present greater 
 resistance, must be put on the stretch by the internal muscle of the 
 malleus, or by its own contraction. The total absence of muscular 
 fibres in the membrana tympani in man, renders very doubtful this 
 spontaneous contraction. Mr. Home, however, has just ascertained 
 that the membrana tympani of the elephant is muscular and contrac- 
 tile. Admitting all these suppositions, we only substitute one difficulty 
 for another, and it remains to be shewn, why the more powerful 
 sounds merely increase the tone of the membrana tympani ; why they 
 do not become objects of perception of the organ of hearing, though 
 they might be expected to render us insensible to the perception of 
 weaker sounds. 
 
 CXXIV. Of odours. Chemists have long thought that the odori- 
 ferous parts of bodies formed a peculiar principle, distinct from all the 
 other substances entering into their composition ; they gave it the name 
 of aroma. M. Fourcroy, however, has clearly shewn, that this pretended 
 element consisted merely of minute particles of bodies, detached by 
 heat and dissolved in the atmosphere, which becomes loaded with them, 
 and conveys them to the olfactory organs. According to this theory, 
 all bodies are odoriferous, since caloric may sublimate some of the par- 
 ticles of those which are least volatile. Linnseus and Lorry had endea- 
 voured to class odours according to the sensations which they produce ;* 
 
 * Linnaeus admits seven classes of odours : 1st class, amlrosiac odours, those of 
 the rose and of musk belong to this class, they are characterised by their tenacity ;
 
 OF THE ORGAN OF SMELL. 231 
 
 M. Fourcroy has been guided by the chemical nature of substances : 
 but, however advantageous this last classification may be, it is difficult 
 to include in it the infinite variety of odours which exhale from sub- 
 stances of all kinds ; and it is perhaps as difficult to arrange them in 
 classes, as the bodies from which they are produced. 
 
 This being laid down on the nature of odours, it is next explained 
 why the atmosphere becomes loaded with the greater quantity, the 
 warmer and the more moist it is. We know that in a flower-garden 
 the air is at no time more loaded with fragrant odours, and the smell is 
 never the source of greater enjoyment, than in the morning, when the 
 dew is evaporating by the rays of the sun. It is, likewise, easily 
 understood why the most pungent smells generally evaporate very 
 readily, as aether, alcohol, the spirituous tinctures, and essential 
 volatile oils. 
 
 CXXV. Of the organ of smell The nasal fossse, within which 
 this organ is situated, are two cavities in the depth of the face, and 
 extending backward into other cavities, called frontal, ethmoideal, 
 sphenoideal, palatine, and maxillary sinuses. 
 
 A pretty thick mucous membrane, always moist, and in the tissue 
 of which the olfactory nerves and a considerable number of other 
 nerves and vessels are distributed, lines the nostrils, and extends into 
 the sinuses which communicate with them and covers their parietes 
 throughout their windings and prominences. This membrane, called 
 pituitary, is soft and fungous, and is the organ which secretes the 
 mucus of the nose ; it is thicker over the turbinated bones which lie 
 within the olfactory cavities ; it grows thinner and firmer in the dif- 
 ferent sinuses. 
 
 The smell appears more delicate in proportion as the nasal fossae are 
 more capacious, and the pituitary membrane covers a greater space. 
 The soft and moist condition of the membrane is likewise essentially 
 necessary to the perfection of this sense. In the dog, and in all animals 
 which have a very exquisite sense of smell, the frontal, ethmoideal, 
 sphenoidal, palatine, and maxillary sinuses, are prodigiously capacious, 
 and the parietes of the skull are in great measure hollowed by these 
 different parts of the olfactory apparatus ; the turbinated bones are 
 
 2d, fraarant,~for example, the lily, the saffron, and the jasmine, they fly off 
 readily ; 3d, aromatic, as the smell of the laurel ; 4th, aliaceous, approaching to that 
 of garlic ; 5th, fetid, as that of valerian and fungi ; 6th, virous, as of poppies and 
 opium ; 7th, natiseous, as that of gourds, melons, cucumbers, and, in general, all 
 cucurbitaceous plants. 
 
 Lorry admits only five kinds of odours, camphorated, narcotic, ethereal, volatile- 
 acid, and alkaline. 
 
 M. Fourcroy admits the miaous aroma belonging to plants, improperly termed 
 inodorous. Oily and fugacious, oily and volatile, add and hyh-n.su/pfnireou*.
 
 292 OF THE SEXSE OF SMELL. 
 
 likewise very prominent in them, and the grooves between them very 
 deep; lastly, the nerves of the first pair are large in proportion. 
 Among the animals possessed of great delicacy of smell, few are more 
 remarkable than the hog. This impure animal, accustomed to live 
 in the most offensive smells and in the most disgusting filth, has, how- 
 ever, so very nice a smell, that it can detect certain roots, though 
 buried in the earth at a considerable depth. In some countries this 
 quality is turned to advantage, and swine are employed in looking for 
 truffles. The animal is taken to those places where they are suspected 
 to be, turns up the earth in which they are buried, and would feed 
 on them greedily, if the herdsman, satisfied with this indication, did 
 not drive them away from this substance intended for more delicate 
 palates. 
 
 CXXVI. Of the sensation of odours. Do the nerves of the first 
 pair alone give to the pituitary membrane the power of receiving the 
 impression of smell, and do the numerous filaments of the fifth pair 
 merely impart to it the general sensibility belonging to other parts ? 
 This question appears to require an answer in the affirmative. The 
 pituitary membrane, in fact, possesses two modes of sensibility perfectly 
 distinct, since the one of the two may be almost completely destroyed, 
 and the other considerably increased. Thus, in violent catarrh, the 
 sensibility of the part, as far as relates to the touch, is very acute, since 
 the pituitary membrane is affected with pain ; while the patient is insen- 
 sible to the strongest smells. 
 
 It seems probable, that the olfactory nerves do not extend into the 
 sinuses, and that these improve the sense of smell merely by retaining, 
 for a longer space of time, a considerable mass of air, loaded with 
 odoriferous particles. I have known detergent injections, strongly 
 scented, thrown into the antrum Highmorianum by a fistula in the 
 alveolar processes, produce no sensation of smell. A phial filled with 
 spirituous liquor having been applied to a fistula in the frontal sinuses, 
 gave no impression to the patient. The true seat of the sense of smell 
 is at the most elevated part of the nostrils, which the nose covers over 
 in the form of a capital. There the pituitary membrane is moister, 
 receives into its tissue the numerous filaments of the first pair of nerves, 
 which, arising by two roots from the anterior lobe of the brain, and from 
 the fissure which separates it from the posterior lobe, passes from the 
 cranium, through the openings of the cribriform plate of the ethmoid 
 bone, and terminates by the expansion of its filaments forming a 
 kind of parenchymatous tissue, not easily distinguished from that of 
 the membrane. The olfactory papillae would soon be destroyed by the 
 contact of the atmospherical air, if they were not covered over by the 
 mucus of the nose. The use of this mucus is, not merely to preserve 
 the extremities of the nerves in a sentient state, by preventing them
 
 OF FLAVOURS. 293 
 
 from becoming dry, but likewise to lessen the too strong impression 
 that would arise from the immediate contact of the odoriferous par- 
 ticles. It perhaps even combines with the odours, and these affect 
 the olfactory organs only when dissolved in mucus, as the food in saliva. 
 
 As the air is the vehicle of odours, these affect the pituitary mem- 
 brane only when we inhale it into the nostrils. Hence, when any 
 odour is grateful to us, we take in short and frequent inspirations, that 
 the whole of the air which is received into the lungs may pass through 
 the nasal fossse. We, on the contrary, breathe through the mouth, 
 or we suspend respiration altogether, when smells are disagreeable 
 to us. 
 
 The sense of smell, like all the other senses, is readily impressed in 
 children, though the nasal fossae are in them much contracted, and 
 though the sinuses are not yet formed. The general increase of sensibi- 
 lity at this period of life makes up for the imperfect state of the organ- 
 isation, and it is in this respect with the nasal fossae as with the audi- 
 tory apparatus, of which an important part, the meatus externus, is 
 then not completely evolved. The sense of smell is perfected by the 
 loss of some of the other senses ; every body, for example, knows the 
 history of the blind man whom that organ enabled to judge of the 
 continence of his daughter, it becomes blunted by the application of 
 strong and pungent odours. Thus, snuff changes the quality of the 
 mucus secreted by the membrane of the nose, alters its tissue, dries its 
 nerves, and in the course of time impairs their sensibility. 
 
 The shortness of the distance between the origin of the olfactory 
 nerves in the brain, and their termination in the nasal fossse, render 
 very prompt and easy the transmission of the impressions which they 
 experience. This vicinity to the brain induces us to apply to those 
 nerves those stimulants calculated to rouse the sensibility when life is 
 suspended, as in fainting and asphyxia. The sympathetic connexions 
 between the pituitary membrane and the diaphragm account for the good 
 effects of sternutatories, in cases of apparent death.* 
 
 CXXVII. Of flavours. Flavours are no less varied and no less 
 numerous than odours, and it is as difficult to reduce them to general 
 classes connected by analogies and including the whole. f Besides, 
 
 * For some remarks on the Organ and Sense of Smell, see APPENDIX, Notes 
 F F. _ J. C. 
 
 f- This has been attempted, though with indifferent success, by Boerhaave, 
 Haller, and Linnaeus. Acid, sweet, bitter, acrid, saltish, alkaline, vinous, spiri- 
 tuous, aromatic, and acerb, were the terms employed by those physicians to express 
 the general characters of flavours. 
 
 The, flavour of any substance appears chiefly to arise from the odoriferous par- 
 ticles which escape from it, during the process of mastication and deglutition, 
 through the posterior nares, and affect the olfactory nervei in that situation. 
 J. C.
 
 294 OF THE SENSE OF TASTE- 
 
 there exists no element of flavour, any more than an odoriferous prin- 
 ciple. The flavour of fruits alters as they ripen, and appears to 
 depend on the inward composition of bodies, on their peculiar nature, 
 rather than on the form of their molecules ; since crystals of the same 
 figure, but belonging to different > salts, do not produce similar 
 sensations. 
 
 To affect the organ of taste, a body should be soluble at the ordi- 
 nary temperature of the saliva ; all insoluble substances are insipid ; 
 and one might apply to the organ of taste this celebrated axiom in 
 chemistry, corpora non agunt nisi soluta. If there is a complete absence 
 of saliva, and if the body that is chewed is altogether without mois- 
 ture, it will affect the parched tongue only by its tactile, and not at all 
 by its gustatory, qualities. The substances which have most flavour 
 are those which yield most readily to chemical combinations and 
 decompositions, as acids, alkalies, and neutral salts. When, in affec- 
 tions of the digestive organs, the tongue is covered with a mucous or 
 whitish fur, or of a yellowish or bilious colour, we have only incorrect 
 ideas of flavours; the thinner or thicker coating prevents the imme- 
 diate contact of the sapid particles ; when they act, besides, on the ner- 
 vous papillee, the impression which they produce is lost in that occa- 
 sioned by the morbid contents of the stomach ; hence every aliment 
 appears bitter while the bilious disposition exists, and insipid in those 
 diseases in which the mucous elements prevail. 
 
 CXXVIII. Of the sense of taste. No sense is so much akin to 
 that of the touch, or resembles it more. The surface of the organ of 
 taste differs from the common integuments only in this respect, that 
 the chorion, the mucous body, and the epidermis which envelop the 
 fleshy part of the tongue, are softer, thinner, and receive a greater 
 quantity of nerves and vessels, and are habitually moistened by the 
 saliva, and by the mucus secreted by the mucous glands contained 
 in their substance. These mucous cryptee, and the nerves of the cuta- 
 neous covering of the tongue, raise the very thin epidermis which 
 covers its upper surface, and form a number of papillae, distinguished 
 by their form into fungous, conical, and villous. With the exception 
 of the first kind, these small prominences are formed by the extremities 
 of nerves, surrounding a plexus of capillary blood-vessels, which give to 
 these papillae the power of becoming turgid and prominent, and of being 
 affected with a kind of erection when we eat highly-seasoned food, or 
 when we long for a savoury dish. The fungous papillae are mostly situ- 
 ated at the remotest part of the upper surface of the tongue, towards 
 its root, where it forms a part of the isthmus faucium. The pressure 
 with which they are affected by the alimentary bolus, in its passage 
 from the mouth into the pharynx, squeezes out the mucus which lubri- 
 cates the edges of the aperture, and serves to promote its passage :
 
 OF THE SENSE OF TASTE. 295 
 
 these mucous follicles fulfil, in this respect, the same office as the 
 amygdalae. 
 
 The upper surface of the tongue is the seat of taste ; it is unde- 
 niable, however, that the lips^the gums, the membrane lining the arch 
 of the palate, and the velum palati,* may be affected by the impression 
 of certain flavours. 
 
 It is observed in the different animals, that the organ of taste is 
 more perfect according as the nerves of the tongue are larger, its skin 
 thinner and moister, its tissue more flexible, its surface more extensive, 
 its motions easier and more varied. Hence, the bone in the tongue of 
 birds, by diminishing its flexibility ; the osseous scales of the swan's 
 tongue, by reducing the extent of the sentient surface ; the adhesion 
 of the tongue to the jaws in frogs, in the salamander, and in the croco- 
 dile, by preventing freedom of motion, render, in these animals, the 
 sense of taste duller, and less calculated to feel the impression of sapid 
 bodies, than in man and the other mammiferous animals. Man would, 
 probably, excel all the other animals in delicacy of taste, if he did not at 
 an early period impair its sensibility by strong drinks, and by the use 
 of spices, and of all the luxuries that are daily brought to our tables. 
 The quadrupeds, whose tongue is covered by a rougher skin, discover 
 better than we can, by the sense of taste, poisonous or noxious sub- 
 stances. We know that in the great variety of plants which cover 
 the face of the earth, herbivorous animals select a certain number 
 suited to their nature, and uniformly reject those which would be 
 injurious to them. 
 
 CXXIX. Is the lingual branch of the fifth pair of nerves, alone 
 subservient to the sense of taste ? Are not the ninth pair (almost wholly 
 distributed in the tissue of the tongue), and the glosso-pharyngeal 
 branch of the eighth, likewise subservient to this function ? Most 
 anatomists, since Galen, have thought that the eighth and ninth pair 
 supplied the tongue with its nerves of motion, and that it received from 
 the fifth its nerves of sensation. Several filaments, however, of the great 
 hypoglossal nerve may be traced into the nervous papillae of the 
 tongue. This nerve is larger than the lingual, and is more exclusively 
 distributed to this organ than the fifth pair, to which the other nerve 
 belongs. Hevermann states, that he knew a case in which the sense of 
 taste was lost from the division of the nerve of the ninth pair, in 
 removing a scirrhous gland. This case, however, appears to me a very 
 
 * Especially the anterior part of the palatine membrane. The naso-palatine 
 nerve, discovered by Scarpa, after arising from the ganglion of Mekel, and going for 
 a pretty considerable distance into the nasal fossae, terminates in that thick and 
 rugous portion of the palatine membrane situated behind the upper incisors, and 
 with which the tip of the tongue is in such frequent contact.
 
 206 OF THE SENSE OF TASTE. 
 
 suspicious one. The patient might still have tasted, by means of the 
 lingual nerve, and the sense would only have been weakened. The 
 division of one of the nerves of the ninth pair could render insensible 
 only that half of the tongue to which it is distributed, the other half 
 would continue fully to possess the faculty of taste. 
 
 The application of metals to the different nervous filaments distri- 
 buted to the tongue, ought to inform us of their different uses, if, as 
 Humboldt suspects, the galvanic excitement of the nerves of motion 
 alone produces contractions. To ascertain the truth of this conjecture, 
 I placed a plate of zinc within the skull, under the trunk of the nerve 
 of the fifth pair, in a dog that had been killed a few minutes before, 
 and that still retained its warmth : the muscles of the tongue, under 
 which a piece of silver was placed, quivered very slightly; those of the 
 forehead and temples in contact with the same metal experienced very 
 sensible contractions whenever a communication was made by means 
 of an iron rod. This experiment shewed that the lingual branch of thi* 
 nerve was almost solely subservient to the sensation of taste, which 
 agrees with the opinion of most physiologists ; and the same inference 
 maybe drawn from the anatomical knowledge of the situation of this 
 nerve, which almost entirely terminates in the papillae of the membrane 
 of the tongue, and sends very few filaments to the muscles of that 
 organ. But though the galvanic irritation applied to the hypoglossal 
 nerve affected the whole tongue in a convulsive manner, I did not think 
 myself justified to infer that this nerve was solely destined to perform 
 its motions; as this nervous trunk might, in this part of the body, as it 
 does in others, contain filaments both of sensation and motion. 
 
 'The tongue, though an azygous organ, is composed of parts com- 
 pletely symmetrical ; there are on each side four muscles, (stylo, hyo, 
 r/enio-glossal, and lingual}; three nerves, (lingual, glosso-pliaryngeal, 
 and hypoglossal) ; a ranine artery and vein ; and a set of lymphatic 
 vessels precisely alike. All these parts, by their union, form a fleshy 
 body of a close texture, and not easily unravelled, similar to that of 
 the ventricles of the heart, endowed with a considerable degree of 
 mobility, in consequence of the numerous vessels and nerves entering 
 into its substance.* If we compare their number and size with the 
 
 * Haller concluded that the tongue possesses irritability. Blumenbach has 
 lately determined the point by direct experiment. He caused the tongue of a four- 
 year-old ox, which had been killed in the usual way, to be cut out while the animal 
 was yet warm, and at the same time the heart, in order that he might compare the 
 oscillatory motions of both viscera ; and when they were excited at the same time 
 by mechanical stimuli, the tongue appeared to survive the heart by more tban 
 seven minutes ; and so vivid were its movements, when cut across after its sepa- 
 ration, that its motions might be compared to those of the tail of a mutilated snake. 
 Thr same phenomenon was remarkable in the divided tongues of other animals, on
 
 OF THE ORGAN OF TOUCH. 297 
 
 small bulk of the organ, it will be readily understood, that as no part 
 of the body can execute more frequent, more extensive, and more 
 varied motions, so no one receives more vessels and nerves. A middle 
 line separates and marks the limits of the two halves of the tongue, 
 which, anatomically and physiologically considered, appears formed of 
 two distinct organs in juxta-position. 
 
 This independence of the two parts of the tongue is confirmed by 
 the phenomena of disease : in hemiplegia, the side of the tongue cor- 
 responding to the half of the body that is paralysed, loses likewise the 
 power of motion ; the other retains its mobility, and draws the tongue 
 towards that side. In carcinoma of the tongue, one side remains un- 
 affected by [ the disease which destroys the other half: lastly, the 
 arteries and nerves of the left side rarely anastomose with those on 
 the right ; injections forced along one of the ranine arteries, fill only 
 the corresponding half of the organ, &c. 
 
 CXXX. Of the organ of touch. No part of the surface of our 
 body is exposed to receive the touch of a foreign body, without our 
 being speedily informed of it. If the organs of sight, of hearing, of 
 smell, and of taste, occupy only limited spaces, touch resides in all 
 the other parts, and effectually watches over our preservation. The 
 touch, distributed over the whole surface, appears to be the elementary 
 sense, and all the others are only modifications of it, accommodated to 
 certain properties of bodies. All that is not light, sound, smell, or 
 flavour, is appreciated by the touch, which thus instructs us in the 
 greater part of the qualities of bodies which it concerns us to know, as 
 their temperature, their consistence, their state of dryness or humidity, 
 their figure, their size, their distance, &c. It corrects the errors of the 
 sight, and of all the other senses, of which it may justly be called 
 the regulator ; and it furnishes us with the most exact and distinct 
 ideas. 
 
 The touch, of which some authors have sought to consecrate the 
 excellence, by giving it the name of the geometrical sense, is not, how- 
 ever, safe from all mistake. Whilst it is employed on the geometrical 
 properties derived from space, and that it appreciates the length, the 
 breadth, the thickness, the form of bodies, it transmits to the intellect 
 
 the application of mechanical or chemical stimuli ; and also in that of a boy, which 
 had been bit off during a violent fit of epilepsy. 
 
 From this, it would appear that the account which Ovid gives of the cruel deed 
 of Tereus is nearly correct : 
 
 . " Compressam forcipe linguam 
 
 Abstulit ense fero. , Radix micat ultima linguae, 
 
 Ipsa jacet, terrseque tremens immurmurat atrae, 
 
 Utque salire solet mutilatae cauda colubrae, 
 
 Palpkat, et moriens dominae vestigia quaerit." Metamor. VI. J. C. 
 
 . t Jit^r/i 
 
 , , -,
 
 298 OF THK IXTEGUMEXTS. 
 
 rigorous and mathematical results ; but the ideas we acquire by its 
 means, on the temperature of bodies, are far from being equally pre- 
 cise. For, if you have, just touched ice, another body colder than 
 yours will appear warm. It is for this reason that subterraneous places 
 appear warm to us during winter. They have kept their temperature 
 whilst all things else have changed theirs ; and as we judge of the 
 heat of an object by its relation not only to our own, but also to that 
 of other bodies, and of the air about us, we find the same places warm 
 which had appeared cold to us in the middle of summer. 
 
 The densest bodies being the best conductors of heat,* marble, 
 metals, &c., appear colder to us than they really are, because they 
 carry it off so rapidly. Marble and metals, when polished, appear still 
 colder, because as they touch the skin in many more points at once, 
 they effect this abstraction more effectually. Every one knows the 
 experiment of placing a little ball between the two fingers crossed, and 
 producing the sensation of two different balls. 
 
 CXXXI. Of the integuments. The general covering of the whole 
 body is the organ of touch, which resides in the skin properly so called. 
 The cellular tissue, which connects together all our parts, forms over 
 the whole body a layer, varying in thickness, which covers it in every 
 part : it is called panniculus adiposus. As it approaches the surface, 
 its laminae are more condensed, are in more immediate contact with 
 each other, and are no longer separated by adeps. It is by the closer 
 juxta-position of the laminae of the cellular tissue that the skin or 
 dermis is formed', a dense and elastic membrane, into which numerous 
 vessels, of all kinds, are distributed, and into which so great a quan- 
 tity of nerves terminate, that the ancients did not hesitate to consider 
 the skin as purely nervous. 
 
 In certain parts of the body a very thin muscular plane separates 
 the skin from the panniculus adiposus. This kind of panniculus car- 
 nosus envelopes, almost entirely, the body of some animals ; its con- 
 tractions wrinkle their skin covered with hairs, these rise, vibrate, and 
 thus are cleared of the dust and dirt which may have gathered on them. 
 It is by means of a cutaneous muscle, of very complex structure, that 
 
 * Woolly substances, &c., all felts, of which the crossing hairs confine, in some 
 sort, a great quantity of air, a fluid which, from its gaseous state, is a very bad con- 
 ductor of heat, retain heat well ; and, being of equal thickness, a stuff of fine wool, of 
 which the hairs are more separated and the tissue softer, will be warmer than a stuff 
 of coarse wool, of which the threads, too close, form a dense body, through which 
 cold, as well as heat, will pass with ease. It is by thus confining a certain mass 
 of air that snow keeps the soil it covers in a mild temperature, and preserves 
 plants from the injury of excessive cold ; a physical truth which is found figura- 
 tively expressed in the words of the Psalmist, " El dcdit illi nivem tanquam vesti- 
 menlum."
 
 OF THE INTEGUMENTS. 299 
 
 the hedge-hog is enabled to coil himself up, and to present to his 
 enemy a surface studded with sharp points : only a few scattered rudi- 
 ments of an analogous structure are to be met with in the human 
 body ; the occipito-frontalis, the corrugator supercilii, several muscles 
 of the face, the platysma myoides, the palmaris cutaneus, may be 
 considered as forming part of this muscle. We may even include the 
 cremaster, whose expanded fibres, surrounded by the dartos, have 
 misled some anatomists to such a degree that they have admitted the 
 existence of a muscular texture in the latter. These fibres of the cre- 
 master produce distinct motions in the skin of the scrotum, wrinkle it 
 in a transverse direction, and at the same time bring up the testicles. 
 The platysma myoides acts likewise on the skin of the neck : lastly, 
 the occipito-frontalis in some men performs so distinct a motion of the 
 hairy scalp, as to throw off a hat, a cap, or any other covering that may 
 be on the head. One may compare to the panniculus carnosus, the 
 muscular coat of the digestive tube situated throughout its whole 
 length below the mucous membrane, which is merely a prolongation of 
 the skin modified and softened. 
 
 But if in man the subcutaneous muscle, from its imperfect state, 
 answers purposes only of secondary importance, the layer of cellular 
 adipose substance, extended under the skin, gives to the latter its 
 tension, its whiteness, its polish, its suppleness, favours its applying 
 itself to tangible objects, and thus renders the touch more delicate. 
 Too hard or wrinkled a skin would have applied itself in a very incom- 
 plete manner to bodies of a small size, and would not readily have 
 accommodated itself to the small irregularities of those of inconsider- 
 able bulk. Hence, the pulp of the fingers, which is the seat of a more 
 delicate touch, is furnished with a kind of adipose cushion supported 
 by the nails, ready to be applied to polished surfaces, and to discover 
 the slightest asperities. I have observed the sense of touch to be 
 very imperfect in men wasted by marasmus, and whose hard, dry, and 
 wrinkled skin adheres, in certain situations, to the subjacent parts. 
 
 The chemical analysis of the cutaneous tissue shews that it does 
 not exactly resemble that of the cellular and membranous tissue ; it is 
 gelatino-fibrous, and, with regard to its structure and to its share of 
 contractility, it occupies a medium between the cellular tissues and 
 the muscular flesh.* There arise from the surface of the skin in- 
 numerable small papillae, fungous, conical, pointed, obtuse, and 
 variously shaped, in the different parts of the body. These papillee 
 are merely the pulpous extremities of the nerves which terminate into 
 
 * See the chnpter in the APPENDIX, on the Chemical Constitution of the Animal 
 Textures and Secretions.
 
 300 OF THE IXTEGUMEXTb. 
 
 them, and around which there are distributed vascular tissues, of the 
 utmost minuteness. The papillae of the skin, which are more distinct 
 in the fingers and lips than elsewhere, swell when irritated, and elevate 
 in a manner the epidermis; and this kind of erection, which is useful 
 when we wish to touch a substance >yith great precision, may be excited 
 by friction, or by moderate heat. 
 
 The nervous or sentient surface of the skin is covered with a 
 mucous coating, colourless in Europeans blackened, from the effects 
 of light, among the natives of southern climates ; of a gelatinous nature, 
 destined to maintain the papillae in that state of moisture and softness 
 favourable to the sense of touch. This mucilaginous layer, known 
 under the name of rete mucosum of Malpighi, seems to contain the 
 principle which causes the variety of colour in the skin of different 
 nations, as will be observed in speaking of the varieties of the human 
 species. 
 
 The reticular state of the rete mucosum may be explained in two 
 ways : a thin and gelatinous layer, extended on the papillar surface of 
 the skin, is perforated at each nervous papilla, and if it were possible to 
 coagulate or to detach this coating, we should have a real sieve or reti- 
 culated mesh-work, with a perforation at every point, corresponding to 
 a cutaneous papilla. The sanguineous and lymphatic capillaries which 
 surround the nervous papillae, form, besides, by their connexions, a net- 
 work, the meshes of which are very minute, and adhere to the epidermis 
 by a multitude of small vascular filaments, that insinuate themselves 
 between the scales of this last envelope, and terminate in exhaling or 
 absorbing pores, according as they belong to the arterial capillaries or 
 to the lymphatic absorbents. It is sufficient, indeed, to remove gently 
 the scales of the epidermis, in order to bare their orifices, and procure 
 the absorption of any virus. It is the net-work of Malpighi, or rather 
 this assemblage of interlaced capillary vessels below the epidermis, 
 which appears to be the seat of the primary phenomena in the majority 
 of cutaneous inflammations "and eruptive diseases. 
 
 The skin would be unable to perform its functions, if an outer, thin, 
 and transparent membrane, the epidermis, did not prevent it from being 
 over-dried. This superficial covering is quite insensible; no nerves, 
 and no vessels of any kind, are found in it; and even in the present 
 state of the science, we do not understand how it is formed, or how it 
 repairs and reproduces itself when destroyed. The most minute 
 researches on its structure merely shew the existence of an infinite 
 number of lamellae, overlapping each other, like the tiles of a roof. 
 This imbrication of the epidermoid lamellae is very obvious in fishes 
 and reptiles; the scaly skin of which is merely an epidermis whose 
 parts are much more coarsely shaped.
 
 OF THE CUTANEOUS TISSUES. 301 
 
 It was observed (XLII.) in the account of absorption, how much 
 friction facilitates the absorption of substances applied to the surface 
 of the skin, by raising the scales of the epidermis so as to expose 
 the orifices of the absorbents, whose activity it in other respects 
 increases. 
 
 Haller conceives that the epidermis is formed by the drying up of 
 the outer layers of the rete mucosum. Morgagni thinks it is formed 
 by the induration of the skin, in consequence of the pressure of the 
 atmosphere. In objection to these hypotheses, one may inquire how it 
 happens, that by the time the foetus, immersed in the liquor amnii, has 
 attained its third month, it is covered with such an envelope.* Pres- 
 sure renders the skin hard and callous, increases considerably its thick- 
 ness, as we see in the soles of the feet and in the palms of the hands of 
 persons engaged in laborious employments. The epidermis reproduces 
 itself with an incredible rapidity, after falling off in scales, after erysi- 
 pelas orherpetic eruptions ; or, when removed in large flakes by blister- 
 ing, it is renewed in the course of a very few days. The cuticle, toge- 
 ther with the hairs and nails, which may be considered as productions 
 of the same substance, are the only parts in man that are capable of 
 reproducing themselves. The hairs and the horns of quadrupeds, the 
 feathers of birds, the calcareous matter of the lobster and of seve- 
 ral molusca, the shell of the turtle, the solid sheaths of a number of 
 insects, possess, as well as the epidermis, this singular property. In 
 other respects the chemical structure of all these parts is the same ; they 
 all contain a considerable proportion of phosphate of lime, withstand 
 decomposition, and give out a considerable quantity of ammonia on 
 being exposed to heat. The use of the epidermis is to cover the ner- 
 vous papillae, in which the faculty of the touch essentially resides, to 
 moderate the too vivid impression that would have been produced by an 
 immediate contact, and to prevent the air from drying the skin or 
 from impairing its sensibility. 
 
 This dessication of the cutaneous tissue is further prevented, and 
 its suppleness maintained, by an oily substance which exudes through 
 its pores, and is apparently secreted by the cutaneous exhalants. This 
 unctuous liniment should not be mistaken for that which is furnished 
 by the sebaceous glands in certain situations, as around the nostrils, in 
 
 i* The epidermis seems to be formed from a certain dry secretion, of which the 
 skin is the organ. The exhalants, with which the dermal tissue is abundantly sup. 
 plied, allow a viscus and albuminous fluid to escape, which contains a great propor- 
 tion of phosphate of lime; thus an envelope is formed analogous to the shell 
 which covers the egg. The epidermis may, therefore, be considered as a kind of 
 excremental tissue as a residue or product of nutrition thrown on the surface of 
 the body, and forming a useful and requisite protection to the economy of organised 
 beings.
 
 302 f)F THE CUTANEOUS TISSUKS. 
 
 the hollow of the arm-pits, and in the groins. This adipose substance 
 with which the skin is anointed, is abundant and fetid in some persons, 
 especially in those of a bilious temperament, with red hair. It is like- 
 wise more copious in the African negroes, as if Nature had been 
 anxious to guard against the too rapid dessication, by the burning 
 atmosphere of tropical climates. This use of the oil of the skin is like- 
 wise answered by the tallow, the fat, and the disgusting substances 
 with which the Caffres and the Hottentots anoint their body, in the 
 manner described under the name of tatooing by the travellers* who 
 have penetrated into the interior of the burning regions of Africa. 
 
 The ancients had a somewhat similar practice; and the anointing 
 with oil, so frequently used in ancient Rome, answered the same pur- 
 pose of softening the skin, of preventing its becoming dry or chapped.f 
 The pomatums employed at the present day at the toilet possess the 
 same advantages. The continual transudation of this animal oil ren- 
 ders it necessary, occasionally, to clean the skin by bathing ; the water 
 removes the dust and the other impurities which may be attached to 
 its surface by the fluid which lubricates it. It is this humour which 
 soils our linen, and obliges us so frequently to renew that in immediate 
 contact with the skin, and which makes the water collect in drops 
 when we come out of the bath, &c. 
 
 Though the parts in which there is found the greatest quantity of 
 subcutaneous fat are not always the most oily, and though one cannot 
 consider this secretion as a mere filtration of this adeps through the 
 tissue of the skin ; corpulence has, however, a manifest influence on 
 its quantity. I know several very corpulent persons in whom it appeal's to 
 be evacuated by perspiration, on their being heated by the slightest 
 exertion. They all grease their linen in less than twenty-four hours. 
 An excess of the oily matter of perspiration is injurious, by pre- 
 venting the evacuation of the perspiration, and its solution in the 
 atmosphere. 
 
 We all know how, after the epidermis has been removed, the slight- 
 est contact is painful ; that of the air is sufficient to bring on a painful 
 inflammation of the skin, exposed by the application of a blister. The 
 epidermis, as was likewise mentioned in speaking of the absorption, 
 placed on the limits of the animal economy, and in a manner inor- 
 ganic, serves to prevent heterogeneous substances from being too 
 readily admitted into the body, and, at the same time, it lessens the too 
 
 * Among others, Kolben, Description du Cap de Bonne-Espcrance. Sparmann, 
 Voyage an Cap de Bonne -Espcrance et chez les Hottentots. Vaillant, Voyage dans 
 rinterieur de FAfrique. 
 
 f- The reply of the old soldier is well known, who, on being asked by Augustus 
 how he came to live so long, said he owed his long life to the use of wine inwardly, 
 and to that of oil outwardly : intus vino, e.rtns oleo.
 
 OF THE NAILS. 303 
 
 vivid action of external objects en our organs. All organised and 
 living bodies are furnished with this covering ; and in all, in the seed of 
 a plant, in its stem, and on the surface of the body in man and ani- 
 mals, it bears to the skin the greatest analogy of function and nature. 
 Incorruptibility is in a manner its essence, and is its peculiar charac- 
 ter ; and in tombs, which contain merely the dust of the skeleton, it is 
 not uncommon to find whole, and in a state to be readily distinguished, 
 the thickened epidermis that forms the sole of the foot, and especially 
 the heel. However, this incorruptibility is possessed, as well as others 
 of the qualities of the skin, by the nails and the hairs, which may be 
 considered as its appendages. 
 
 CXXXII. Of the nails. The nails are, in fact, only a part of the 
 epidermis ; they are continuous with it, and after death fall off along 
 with it. They are thicker and harder ; like it they are inorganic and 
 lamellated ; they grow rapidly from their root towards their free ex- 
 tremity; they reproduce themselves rapidly, and acquire several 
 inches in length, when the part beyond the ends of the fingers and toes 
 has not been removed ; as is the case with the Indian fakirs. In 
 this state of development they bend over the tips of the fingers and 
 toes, and impair the sense of touch, whose free enjoyment is preferable 
 to any advantages which savages can derive from their long and 
 crooked nails, in defending themselves, or in attacking animals, or 
 tearing to pieces those which they have killed in hunting. The nails 
 are quite insensible, and the reason that so much pain is felt when the 
 nails run into the flesh, and that the operation of tearing them out, which 
 is sometimes necessary, is so painful, is, that the nerves over which 
 the nail grows are more or less injured when it grows in a wrong direc- 
 tion. The pain from the growing of the nails into the quick, is no 
 proof of their being sentient ; any more than the growth of corns 
 proves the sensibility of the epidermis, of which they are but thickened 
 parts, become hard and callous by pressure, and which, confined in 
 tight shoes, press painfully on the nerves below. The nail itself may 
 acquire a considerable degree of thickness ; I have seen that of the 
 great toe nearly half an inch thick. The use of the nails is to support 
 the tips of the fingers, when they are applied to unyielding substances; 
 they likewise concur in improving the mechanism of the touch.* 
 
 * The toe-nails are favourable to the laying the foot to the surface on which 
 the body is supported ; they likewise improve the sense of touch in this part. 
 The use of the feet is not merely to support the weight of the body ; they are also 
 intended to guide us in feeling for the plane on which we are to rest them, to enable 
 us to judge of the solidity, of the temperature, and of the inequalities of the ground 
 on which we tread. They, therefore, required rather a delicate sense of touch. 
 The division of the fore part of the foot into several distinct and separate parts, 
 serves to enable us to stand more firmly, and facilitates the action of walking. I
 
 304 OF THE HAltt. 
 
 CXXXIII. Of the hair on the head and other parts of the body.~ 
 These parts are treated of in the present instance, only in con- 
 sequence of their connexion with the epidermis ; as, far from im- 
 proving the touch, they interfere with it, or at least render it less 
 delicate. 
 
 The skin in man is more bare than that of other animals ; it is 
 likewise least covered with insensible parts that might blunt the 
 sense of touch. In almost all mammiferous animals the whole body 
 is covered with hair ; only a small part of the human body has any hair 
 on it, and that in too small a quantity, and of too delicate a texture, 
 to interfere with the touch. Some men, however, have a very hairy 
 skin, and I have seen several who, when naked, looked as if covered 
 over with the skin of an animal, so great was the quantity of hair over 
 the whole body, of which no part was bare but a small portion of the 
 face, the palms of the hands, and the soles of the feet." This extraor- 
 dinary growth of hair is in general a sure sign of vigour and strength. 
 In childhood, there is no hair except on the head, the rest of the 
 body is covered with down. Women have no beard, and there is in 
 them a smaller quantity of hair in the arm-pits and on the parts of 
 generation, and scarcely any on the limbs and trunk. But as though 
 the matter which should provide for the growth of the hair were wholly 
 applied to the hairy scalp, it is observed, that the hair of their head is 
 longer and in greater quantity. 
 
 The colour of the hair varies from white to jet black ; and, as will 
 be mentioned in speaking of the temperaments and of the varieties of 
 the human species, this difference of colour is a test by which we 
 judge of those varieties. The colour of the hairs enables us to judge of 
 their thickness : Withof, who, with a truly German patience, was at 
 the pains to count how many hairs were contained in the space of a 
 square inch, states, in his dissertation on the human hair, that there 
 are five hundred and seventy-two black hairs, six hundred and eight 
 chestnut, and seven hundred and ninety light coloured ; so that the 
 diameter of a hair, which is between the three and seven hundredth 
 part of an inch, is least in light hair, and these are the finer the lighter 
 their shade. It is likewise observed, that men of a bilious constitu- 
 tion, with dark hair, and inhabiting warm climates, have more hair in 
 other parts of the body, and that it is coarser and more greasy. 
 
 In whatever part of the body hairs may grow, they are every 
 where of the same structure, they all arise from a vesicular bulb in the 
 
 have seen several soldiers who lost, from severe cold, the extremities of their feet, in 
 crossing the Alps which separate France from Italy. Those who had lost only 
 their toes, did not walk so steadily, and frequently fell in treading on uneven 
 ground. Those who had lost one half of their feet were obliged to use crutches.
 
 OF THE HAIR 305 
 
 adipose cellular tissue : from this bulb, containing a gelatinous lymph, 
 on which the hair seems to be nourished, the latter, at first divided into 
 two or three filaments which constitute a kind of root, comes out in 
 a single trunk, passes through the skin and epidermis, receiving from 
 the latter a sheath that covers it to its extremity, which terminates in a 
 point. 
 
 A hair may therefore be considered as an epidermoid tube, filled 
 with a peculiar kind of marrow. This spongy stem, which forms the 
 centre of a hair, is a more essential part of it than the sheath supplied 
 by the epidermis. Along this spongy and cellular filament, the animal 
 oil of the hair and the juices on which it is repaired flow. Though we 
 see, in some animals, vascular branches and very small nervous fila- 
 ments directed towards the root of certain kinds of hair, and lost in it, 
 as is the case with the long and stiff whiskers of some of the quad- 
 rupeds, it is impossible to say, whether in man the hair or its bulbs 
 receives vessels and nerves. Is the human hair nourished by the im- 
 bibition of the gelatinous fluid contained in its bulb, or is it nourished 
 on the fat in which the latter is imbedded ? Are vessels distributed 
 along their axis, from the root to the extremity ? In favour of this 
 opinion, it was usual to mention the bleeding from the hair when cut, 
 in the disease called plica Polonica. But this disease, lately observed 
 in Poland by the French physicians, appeared to them a mere en- 
 tangling of hair, in consequence of the filth of the Poles, and of their 
 habit of keeping their head constantly covered with a woollen cap. 
 The hairy scalp remains perfectly sound beneath the entangled hair, 
 and the only way to cure the complaint is to cut off the hair. Four- 
 croy* thinks that each hair has several short branches that stand oft" 
 from it, which, according to the explanation given by Monge, favour 
 the matting of the hairs that are to be converted into tissues, by the 
 process called felting. 
 
 C XXXIV. Among the most remarkable qualities of the hair one 
 may take notice of the manner in which it is affected by damp air, 
 which, by relaxing its substance, increases its length. It is on that 
 account that hairs are used for the construction of the best hygrome- 
 ters. Nor must we omit either the readiness with which they grow 
 and are reproduced, even after being plucked out by the roots, as I 
 have often seen after the cure of tinea by a painful method : nor 
 their insulating property with respect to the electric fluid, of which 
 they are very bad conductors; a remarkable property, viewed with 
 reference to the conjectured nature of the nervous fluid. 
 
 The hairs possess no power of spontaneous motion by which they 
 can rise on the head, when the soul shudders with horror or fear ; but 
 
 * Systeme des Connoissances Chimiques, tome ix. p. 263. 
 x
 
 306 OF THE HAIR. 
 
 they do bristle at those times, by the contraction of the occipito- 
 frontalis, which, intimately adhering to the hairy scalp, carries it along 
 in all its motions. 
 
 They appear totally without sensibility ; nevertheless, the passions 
 have over them such influence that the heads of young people have 
 turned white the night before execution. The Revolution, which pro- 
 duced in abundance the extremes of human suffering, furnished many 
 authentic instances of persons that grew hoary in the space of a few 
 days. In this premature hoariness, is the hair dried up, as in old 
 people, when it seems to die for want of moisture and its natural 
 juices ? 
 
 The following fact seems to shew that they are the excretory organ 
 of some principle, the retention of which might be of very injurious 
 consequence. A chartreux, who every month had his head shaved, 
 according to the rule of his order, quitting it at its destruction, went 
 into the army, and let his hair grow. After a few months, he was 
 attacked with excruciating headaches, which nothing relieved. At 
 last, some one advised him to resume his old habit, and to have 
 his head frequently shaved ; the headaches went off, and never 
 returned. 
 
 We know, says Grimaud,* that there are nervous headaches, which 
 give way to frequent cropping the hair : when it is kept close cut, 
 the more active growth that takes place sets in motion stagnating 
 juices. A friend of Valsalva, as Morgagnif relates, dispelled a ma- 
 niacal affection, by having the head of the patient shaved ; Casimir 
 Medicus cured obstinate gonorrhoea, by the frequent shaving of the 
 parts of generation. 
 
 The hairs partake of the inalterability, the almost indestructibility 
 of the epidermis. Like it, they burn with a fizzing, and give out in 
 abundance a fetid ammoniacal oil. The ashes that remain from burn- 
 ing them contain much phosphate of lime.J The horns of mammiferse, 
 the feathers of birds, give out the same smell in burning, and yield the 
 same products as the hair on the head and other parts; which has led to 
 the saying that these last were a sort of horny substance, drawn out 
 like wire. Acids, but especially alkalies, dissolve them : accordingly^, 
 all nations that cut the beard, first soften it, by rubbing it with alkaline 
 and soapy solutions. 
 
 Is the use of the hair to evacuate the superabundant nutritious 
 matter? The epoch of puberty and of the termination of growth, is 
 that in which it first springs, in many parts of the body which were 
 
 * Second Memoir on Nutrition, p. 49. 
 j- De Sedibus et Causis, Epist. 8. No. ? 
 
 J See the Chapter in the APPENDIX, on the Chemical Constitution of the 
 Textures, &c.
 
 OF THE SENSE OF TOUCH. 307 
 
 before without it. They are, at the same time, the emunctory by which 
 nature gets rid of the phosphate of lime, which is the residue of the 
 work of nutrition. The hairs of quadrupeds, whose urine abounds less 
 in phosphoric salts than that of man, seem especially to fulfil this des- 
 tination. The hairs have some analogy with the fat, which has not yet 
 been ascertained. They are often found accidentally developed in the 
 fatty tumours known under the name of steatomas. Finally, they 
 have uses relative to the parts on which they grow. 
 
 CXXXV. Of the sense of touch, c. The faculty of taking cog- 
 nizance of tangible qualities belongs to all parts of the cutaneous 
 organ. We have only to apply a substance to any part of the surface 
 of our body, to acquire the idea of its temperature, of its dryness 
 or moisture, of its weight, its consistence, and even its particular 
 figure. But no part is better fitted to acquire exact notions on all 
 these properties, than the hand, which has ever been considered as the 
 especial organ of touch. The great number of bones that form its 
 structure, make it susceptible of very various motion, by which it 
 changes its form, adapts itself to the inequalities of the surfaces of 
 bodies, and exactly embraces them : this apt conformation is particu- 
 larly manifest at the extremities of the fingers. Their anterior part, 
 which is endued with the most delicate feeling, receives, from the me- 
 dium and cubital nerves, branches of some size, which end in rounded 
 extremities, close, and surrounded with a cellular tissue. The part 
 of the fingers which is called their pulp, is supported by the nails ; 
 vessels in great number are spread through this nervo-cellular tissue, 
 and moisten it with abundant juices, that keep up its suppleness. 
 When perspiration is increased, it breaks out in small drops over this 
 extremity of the fingers, along the hollow of the concentric lines with 
 which the epidermis is furrowed. 
 
 It has been attempted to explain the pleasure we feel in touching 
 rounded and smooth surfaces, by shewing that the reciprocal con- 
 figuration of the hand and of the body to which it is applied, is such, 
 that they touch in the greatest number of points possible. The 
 delicacy of the touch is kept up by the fineness of the epidermis : it 
 increases by education, which has more power over this sense than over 
 any of the others. It is known with what eagerness a child, allowed 
 the free use of his limbs, stretches his little hands to all the objects 
 within his reach, what pleasure he seems to take in touching them in 
 all their parts, and running over all their surfaces. Blind men have 
 been known to distinguish by touch the different colours, and even 
 their different shades. As the difference of colour depends on the dis- 
 position, the arrangement, and .number of the little inequalities which 
 roughen the surface of bodies that appear the most polished, and fit 
 them to reflect such or such a ray of light, absorbing all the others, one
 
 308 OF THE SENSE OF TOUCH. 
 
 does not refuse to believe facts of this kind, related by Boyle, and 
 other natural philosophers. 
 
 Some parts appear endowed with a peculiar touch ; such are the 
 lips, whose tissue swells and spreads out under a voluptuous contact ; 
 a vital turgescence, explicable without the supposition of a spongy 
 tissue in their structure, such are those organs which Buffon con- 
 siders as the seat of a sixth sense. In most animals, the lips, and 
 especially the lower one, without feathers, scales, or hair, are the organ 
 of a sort of touch, imperfect at best. When the domestic quadrupeds, 
 such as the horse, the dog, the ox, &c. want to judge of the tangible 
 qualities of bodies, you will see them apply to it the end of their nose, 
 the only part where the external covering is without hair ; the fleshy 
 appendages of certain birds, and many fish ; the antennae of butterflies, 
 always set near the opening of the mouth, answer the same purpose. 
 The tail of the beaver, the trunk of the elephant, are, in like manner, 
 the parts of their body where touch is most delicate. Observe that the 
 perfection of the organ of touch insures to these two animals a degree 
 of intelligence allotted to no other quadruped, and becomes, perhaps, 
 the principle of their sociability. The books of travellers and naturalists 
 swarm with facts attesting the wonderful sagacity of the elephant. 
 Some Indian philosophers have gone the length of allowing him an 
 immortal soul. If birds, notwithstanding the prodigious activity of 
 their life of nutrition, are yet of such confined intelligence, so little 
 susceptible of durable attachment, so restive to education, is not the 
 cause to be assigned to their imperfection of touch ? In vain the heart 
 sends towards all their organs, with more force and velocity than 
 in any other animal, a warmer blood, and endued more remarkably 
 with all the qualities which characterise arterial blood ; in vain is 
 their digestion rapid, their muscular power lively and capable of long- 
 continued motion, and certain of their senses, as those of sight and 
 hearing, happily disposed ; touch being almost nothing with them, as 
 also the greater number of impressions belonging to this sense, which 
 informs us of the greater part of the properties of bodies, the circle of 
 their ideas must be extremely narrow, and their habits and manners 
 much more remote than those of quadrupeds from the habits and man- 
 ners of man. 
 
 CXXXVI. Of all the senses the touch is the most generally dif- 
 fused among animals. All possess it, from man, who in the perfec- 
 tion of this sense excels all vertebral animals, to the polypus, who, 
 confined to the sense of touch only, has it in such delicacy, that he 
 appears, to use a happy expression of M. Dumeril, to feel even light. 
 The skin of man is more delicate, fuller of nerves than that of the other 
 mammiferae ; its surface is covered only by the epidermis, insensible 
 indeed, but so thin that it does not intercept sensation, whilst the hairs
 
 OF THE STRUCTURE OF NERVES. 309 
 
 which cover so thickly the body of quadrupeds, the feathers which 
 clothe that of birds, quite deaden it. The hand of man, that admirable 
 instrument of his intelligence, of which the structure has appeared to 
 some philosophers* to explain sufficiently his superiority over all living 
 species ; the hand of man naked, and divided into many movable parts, 
 capable of changing every moment its form, of exactly embracing the 
 surface of bodies, is much fitter for ascertaining their tangible qualities 
 than the foot of the quadruped, enclosed in a horny substance, or 
 than that of the bird, covered with scales too thick not to blunt all 
 sensation. 
 
 CXXXVII. Of the nerves. These whitish cords, which arise from 
 the base of the brain and from the medulla oblongata, are distributed 
 to all parts of the body, and give them at once the power of moving 
 and feeling. In this analysis of the functions of the nervous system^ 
 the most natural order is to consider them merely as conductors of the 
 power of sensation. We shall then see in what manner they transmit 
 the principle of motion to the organs by which it is performed. The 
 nerves arisef from all sentient parts, by extremities that are in general 
 soft and pulpy, but not alike in all in consistence and form ; and it is 
 to these varieties of arrangement and structure, that the varieties of 
 sensation in the different organs are to be referred. 
 
 One may say, that there exists in the organs of sense a certain rela-V 
 ti&n between the softness of the nervous extremity and the nature of 
 the bodies which produce an impression upon it. Thus, the almost 
 fluid state of the retina bears an evident relation to the subtilty of 
 light. The contact of this fluid could not produce a sufficient im- 
 pression unless the sentient part were capable of being set in motion 
 by the slightest impression. The portio mollis of the seventh pair, 
 wholly deprived of its solid covering, and reduced to its medullary 
 pulp, readily partakes in the sonorous motions transmitted to it by the 
 fluid, in the midst of which its filaments are immersed. The nerves of 
 smell and of taste are more exposed than the nervous papillae of the 
 skin which are employed" in receiving the impressions produced by % 
 the coarser properties of bodies, &c. 
 
 * See the work of Galen, de Usu Partium, cap* iv. v. vi. ; and Buffon, Histoire 
 Naturelle, torn. iv. et v. 12mo. 
 
 f- In considering the nerves as conductors of sensation, it is correct to say, that 
 they arise from sentient parts, since it is the extremity most distant from the brain 
 which experiences the sensitive impression that is propagated to the organ itself 
 along the course of the nerve. In attending, on the contrary, to the phenomena of 
 motion, the nerves are considered to arise from the brain ; for it is from the centre 
 to the circumference that the principle of motion is transmitted to the muscles 
 called by Cullen moving extremities of the nerves. Some anatomists have thought 
 it a doubtful point, whether the nerves arise from the brain and spinal marrow, or 
 whether these parts are formed by the uniou of the nerves.
 
 310 OF THE DISTRIBUTION OF NERVES. 
 
 From their origin the nerves ascend towards the medulla oblongata 
 and the spinal marrow, in a line nearly straight, and seldom tortuous, 
 as most of the vessels. When they have reached these parts they ter- 
 minate in them, and are lost in their substance, as will be mentioned 
 in speaking of the structure of these nervous cords. 
 
 CXXXVIII. Structure of nerves. Every nerve is formed of a 
 great nuihber of filaments, extremely delicate, and which have two 
 extremities, the one in the brain, and the other from the pan into which 
 they terminate, or from which they originate. Each of these nervous 
 fibres, however minute, is composed of a membranous tube, which is a 
 production of the pia mater. Within the parietes of this tube there 
 are distributed innumerable vessels of extreme minuteness ; it is filled 
 within with a whitish marrow, a kind of pulp, which Kiel states he 
 insulated from the small canal containing it, by concreting it by means 
 of the nitric acid, which dissolves the membranous sheath, and leaves 
 uncovered the medullary pulp, forming the essential part or basis of 
 the nervous filament. The same physiologist discovered by a different 
 process the internal structure of each nervous fibrilla : he dissolved the 
 whitish or pulpy part by a long-continued solution in alkaline ley, and 
 he succeeded thus in separating it from the membranous tube which 
 enclosed it, and which was emptied. The membranous sheath is of cel- 
 lular structure, and is remarkable only by its consistence, and by the 
 very considerable number of vessels of all kinds that are distributed to 
 its parietes ; it ceases to cover the nerves near their two extremities, and 
 protects them only along their course. 
 
 Each nervous fibre, thus formed of two very distinct parts, joins 
 other fibres of a perfectly similar structure, to form a nervous filament 
 enveloped in a common sheath of cellular tissue. These filaments by 
 their union form small ramifications, and these progressively larger 
 branches, and lastly trunks, wrapped in a common covering of cellular 
 tissue ; then other envelopes to each fasciculus of filaments, and lastly, 
 a sheath to each individual filament. When nervous cords are of a 
 certain size, veins and arteries of a pretty considerable calibre may be 
 seen to insinuate themselves between the bundles of fibres of which 
 they are composed ; these vessels then divide, after penetrating among 
 them, and furnish the capillary ramifications which are distributed to 
 the parietes of the sheath common to each filament. These small ves- 
 sels, according to Reil, allow the nervous substance to exhale into each 
 membranous tube ; this likewise becomes the secretory organ of the 
 medulla, with which it is filled. 
 
 CXXXIX. Distribution of nerves. The nervous filaments unite, 
 or are separated from one another, but do not run into each other. The 
 divisions of the nerves are different from those of the arteries, and their 
 mode of junction does not admit of being compared to that of the
 
 OF THE DISTRIBUTION OF NERVES. 311 
 
 veins. It is, in the first instance, a mere separation ; in the second, an 
 approximation of filaments which had been separated, and which, 
 though united in common sheaths, have, nevertheless, each a proper 
 covering, are merely in juxta-position, and perfectly distinct. If that 
 were not the case, one could not say that each fibre has one extremity 
 in the brain, and the other in some one point of the body; nor could 
 one conceive how the impressions which several sentient extremities 
 receive at once, reach the brain without running into each other ; nor 
 in what manner the principle of motion could be directed towards a 
 single muscle receiving its nerves from the same trunk as the other 
 muscles of the limb. 
 
 We may admit the existence of four kinds of nerves : 1st, those 
 having double roots, as the spinal nerves, the sub-occipital, and the 
 trigeminal or the fifth pair of cranial nerves, one of these roots being 
 subservient to voluntary motion, whilst the other is a conductor of 
 sensibility, as the anterior and posterior roots of the spinal nerves ; 
 2dly, nerves having a single root or origin, as the first, second, third, 
 fourth, sixth, the portio mollis of the seventh, and the ninth pairs, nerves 
 which are exclusively subservient either to sensation, as the olfactory, 
 optic, and auditory nerves, or to the motion of the muscles which they 
 supply, as the third, fourth, sixth, and ninth pairs ; 3dly, the respiratory 
 nerves, which have been called by Mr. Bell also the superadded, and 
 Avhich consist in the portio dura of the seventh pair, the eighth or pneu- 
 mogastric, which may be considered as the centre of this class of 
 nerves, the glosso-pharyngian, the spinal or accessory of Willis, and the 
 diaphragmatic or external thoracic : all these nerves proceed from the 
 lateral columns of the superior portion of the medulla oblongata, and 
 are destined to preside over the organs concerned in respiration ; 
 4thly, the sympathetic order of nerves, which communicate with all the 
 spinal nerves. 
 
 It is by thus distributing the nerves in four divisions, that we are 
 enabled to form an accurate conception of the particular functions of 
 this very complicated and difficult part of the animal economy, and to 
 ascertain that sensation and motion have, in the first and second 
 classes, peculiar and distinct agents, whilst the third and fourth divi- 
 sions serve to associate, by more or less intimate connexions, the most 
 important functions of our economy. The earlier anatomists seem to 
 have had some idea of this important distinction, since they applied 
 the terms of middle and little sympathetics to the eighth pair, and the 
 portio dura of the seventh. 
 
 In general, the nerves divide from each other, and unite at an angle 
 more or less acute, and equally favourable to the circulation of a fluid, 
 from the circumference to the centre, and from the centre to the 
 circumference.
 
 312 OF THE DISTRIBUTION OF NERVES. 
 
 The structure of the nerves is different according to their situation. 
 Thus, the medullary fibres of the optic nerve are not provided with 
 membranous coverings, the pia mater alone furnishing a sheath to the 
 cord formed by the union of these filaments ; the dura mater adds a 
 second coat to it on its leaving the skull. This coat, belonging like- 
 wise to the whole nerve, is not continued over it after it has entered 
 the eye-ball, and is lost in the sclerotica. A minute artery passes 
 through the centre of the optic nerve, and then dividing, forms a rete 
 mirabile, which supports the medullary pulp of the retina. The 
 nerves which pass along osseous canals, as the Vidian nerve of the 
 fifth pair, are not provided with a cellular covering, and their consist- 
 ence is always greater than that of the nerves which are surrounded 
 by soft parts. 
 
 CXL. On reaching the brain, the medulla oblongata, or the spinal 
 marrow, every nervous filament, as was already mentioned, parts with 
 its membranous covering, which is lost in the pia mater, or immediate 
 covering of these central parts of the brain. The medullary or white 
 part of the brain is continued into their substance, which may be con- 
 sidered as principally formed by the assemblage of these nervous extre- 
 mities, which it is difficult to distinguish in its tissue, from its want of 
 consistence* It has long been known, that the origin of the nerves is 
 not the spot at which they are detached from the brain, that they sink 
 into the substance of this viscus, in which their fibres cross each other, 
 so that those on the right pass to the left, and vice versd. Soemmering 
 thought that the roots of the nerves, especially of the nerves of the 
 organs of sense, reached to the prominences in the parietes of the ven- 
 tricles of the brain, and that their furthest extremity was moistened by 
 the serosity which keeps these inward surfaces in contact. It has like- 
 wise long been thought, that the cerebral extremities or the nerves all 
 joined in a fixed point of the brain, and that to this central point all 
 sensations were carried, and that from it all the determinations pro- 
 ducing voluntary motion arose. But the inquiries of Gall on the 
 structure of the brain and nervous system have completely overset 
 these various hypotheses. 
 
 The spinal marrow and the nerves, in the different animals fur- 
 nished with them, are larger in proportion to the brain, according as the 
 animal is more distant from man in the scale of animation. In carnivo- 
 rous animals the prodigious developement of the muscles required 
 nerves of motion of a proportionate size ; hence in them the cerebral 
 mass, compared to the nerves and spinal marrow, is very inconsider- 
 able. It is observed that there exists the same relation in men of an 
 athletic disposition; the whole nervous power seems employed in mov- 
 ing their large muscles ; and the nerves, though very small in propor- 
 tion to the rest of the body, are, however, very large, if compared to the
 
 OF THE SPINAL CORD. 313 
 
 cerebral organ. In children, in women, and in individuals possessed, 
 of much sensibility, the nerves are very large in proportion to the other 
 parts of the. body ; they decrease in size and shrink in persons advanced 
 in years ; the cellular tissue which surrounds them becomes more con- 
 sistent, adheres to them more closely, and there exists a certain ana- 
 logy between the nerves of old men, enveloped by that yellowish tissue 
 which makes their dissection laborious, and the branches of an old tree 
 covered over by a destructive moss. 
 
 As the uses of the nerves cannot be explained independently of 
 those of the brain, I shall now go on to consider this important viscus. 
 
 CXLI. Of the spinal cord and its functions. This part of the 
 nervous system ought no more to be called the spinal prolongation of 
 the encephalon, as it has been by some writers, than it ought to be 
 named the spinal marrow ; both designations are equally erroneous. 
 It is independent of the encephalic organ. As the central portion of 
 the nervous system, it is to be found in many animals which possess no- 
 brain, and its volume is not proportionate to that of this organ. The 
 ox, horse, and sheep, for example, which have smaller brains than man, 
 have a much larger spinal cord. It is found in acephalous foetuses, 
 where the brain never existed. This latter organ appears to be super- 
 added to it, and that only in the perfect animals, its proportionate 
 size being always in an inverse ratio to the spinal cord. This part 
 of the nervous system cannot, therefore, be considered as a production 
 from the brain, and as formed by a collection of nerves which succes- 
 sively detach themselves from it. Its volume does not gradually dimi- 
 nish, owing to the nerves which it sends off; and instead of presenting 
 the characters of a cord, which gradually decreases in thickness as it 
 advances from the brain, its consists of a set of knots, bulbs, or sepa- 
 rate prominences, equal in number to the pairs of nerves which arise 
 from it. Finally, the spinal marrow is formed in the foetus before either 
 cerebellum or cerebrum ; these organs proceeding from it, and not it 
 from them. About the second month of the foetal existence, the first 
 epoch at which the brain can be rendered apparent by the action of 
 alcohol, this organ is" uncommonly small in proportion to the size of 
 the spinal marrow, and arises evidently from a prolongation of the 
 pyramidal eminences and the corpora olivaria. The different parts of 
 the encephalic mass are gradually formed by the successive develope- 
 ment of the corpora pyramidalia, and it is only towards the end of ges- 
 tation that the hemispheres are fully formed.* 
 
 The special functions that may be assigned to the spinal cord are 
 different from those performed by the brain. In the spinal marrow 
 
 * See APPENDIX, Note G G.
 
 314 ' FUNCTIONS OF THE SPINAL CORD- 
 
 resides the source of all the movements, both voluntary and involun- 
 tary, that are performed by the animal economy : it presides over those 
 of the heart, of all the muscles of the interior life, as well as over those 
 of the locomotive apparatus ; and while the brain, reserved for the 
 most noble and most important functions, seems exclusively charged 
 with the operations of intelligence and thought, the spinal marrow holds 
 under its controul all the contractile organs, and it is by its influence 
 that all their contractions are executed.* 
 
 Thomas Bartholin had already acknowledged that the brain was 
 more particularly the organ of sensation, and the spinal marrow that of 
 motion. f He was equally sensible, that the best way of proceeding in 
 the dissection of the brain, was to advance from the base to the ver- 
 tex, and not from the summit to the base, as was the custom until our 
 own times. 
 
 If we take a view of the graduated scale of the animal creation, 
 says Dr. Gall, in his Researches on the Nervous System, &c. the sen- 
 sible substance, which is merely a gelatinous pulp in the polypus, gra- 
 dually becomes disposed into nervous filaments and cords in the more 
 perfect animals. In order to establish a more extended intercourse 
 with the external world, Nature has added more complex organs, 
 according as the relations of the species with the surrounding creation 
 become more numerous : it is thus that, by the successive addition of 
 new organs, and the perfection of others, that the animal creation is 
 elevated to man himself. 
 
 The brain, a simple tubercle added to the anterior extremity of 
 the spinal marrow, of which it seems to be nothing else than an acces- 
 sory part, an appendix, in the insects, because amongst them it is but 
 little larger than one of their numerous ganglions, becomes more complex 
 and more perfect in the higher animals : in the fishes it but little 
 exceeds the spinal cord ; whilst in the mammalia it possesses the same 
 parts as in man, it is disposed nearly in the same form ; but in no ani- 
 mal is the double appearance of diverging and converging fibres better 
 developed than in him ; in no other animal is the brain properly so 
 called, that is to say, the superior part of the encephalon, or the 
 hemispheres, possessed of a greater volume in proportion to the size of 
 the animal. J The brain proper seems to be the seat of the nobler 
 
 * See APPENDIX, Note G G. 
 
 f- " Et id quidem manifesting fit inspicientibus anatomen plscium ; ibi enim 
 medullaj caput et cauda insignia est magnitudinis; processus vero medullae ad cere- 
 brum admodum exiguum ; cnjus rei causa est, quod pisces motu magis quam sensu 
 utantur, ac sic ad sensum plus conferat cerebrum vel cortex, ad motum plus medulla 
 ipsa." Anatomia. 
 
 $ See APPENDIX, Note G G.
 
 OF THE COVERINGS OF THE BRAIN. 315 
 
 functions of intelligence ; whilst in the cerebellum, the medulla oblon- 
 gata, and the spinal cord, appear to reside those faculties and manifes- 
 tations that are common to us and the lower animals. 
 
 The nervous system ought not, therefore, to be compared to a tree, 
 the trunk of which, represented by the spinal marrow, has its roots in 
 the brain, and expands its branches through all parts of the body; but 
 ought rather to be considered as a net-work, whose threads communi- 
 cate with each other, separate, re-unite, and join several masses or dila- 
 tations of greater or less size ; these masses or ganglions ought to be 
 viewed as being the centres of communication. 
 
 The brain should not be considered as a ganglion, or even as a col- 
 lection of ganglions, as the common ganglion of the nerves of the cra- 
 nium, as some physiologists have done : the nerves which detach them- 
 selves from its base, or from the medulla oblongata, have their origins 
 distinct from its substance. Their volume has no relation to its bulk, 
 but is proportionate to the perfection of the different senses in the 
 various species of animals ; thus, the olfactory nerve, which is very 
 large in the mole, is small in the eagle; while the optic nerve is, 
 on the contrary, largely developed in the latter. 
 
 The spinal marrow may be considered as a series of ganglions, 
 communicating with each other and with the brain.* These ganglions 
 are of a size proportioned to that of the nerves which originate from 
 them. It is owing to this that the spinal marrow is thicker towards the 
 inferior part of the cervical and dorsal regions than in other portions 
 of its length. Can the vertebral column be compared to a galvanic 
 pile, of which the spinal cord is the conductor, and of which the brain 
 and the parts of generation form the two extremities, occupying, and 
 as if constituting, the two extremities of this kind of electro-motive 
 apparatus ? Observation establishes, it may be said, a sort of antago- 
 nism between these two organs. Is there any analogous opposition 
 existing between the cerebral nervous system and that which forms the 
 grand sympathetic nerves? We have formerly remarked, more than 
 once, how ill-founded this attempt at identifying the vital phenomena 
 with those of electricity appears to us. The communication of the 
 spinal marrow with the brain is established by the medium of a 
 double bundle of fibres, which, crossing each other, form the corpora 
 pyramidalia, and direct themselves towards the brain, where we 
 shall find them again, when the structure of this viscus coines under 
 consideration. 
 
 CXLII. Of the coverings of the brain. If it be true that one may 
 judge of the importance of an organ by the care which Nature has 
 taken to protect it from external injury, no organ will appear of 
 
 * See APPENDIX, Note G G.
 
 316 OF THE COVERINGS OF THE BRAIX. 
 
 greater importance than'.the brain, for no one appears to have been 
 protected with greater care. The substance of this viscus has so little 
 consistence, that the slightest injury would have altered its structure, 
 and deranged its action ; hence it is powerfully guarded by several 
 envelopes, the most solid of which > is the bony case in which it is 
 contained. 
 
 No part of anatomy is better understood than that of the many 
 bones which, by their union, form the different parts of the human 
 head. Every thing that relates to the place they occupy, to their 
 respective size, to their projections and depressions, to the cavities whose 
 parietes they form every thing that relates to their internal structure, 
 to the different proportions of their component parts, to the aggregation 
 of some of these substances in certain points of their extent, has been 
 described by several modern anatomists with an accuracy which it 
 would not be easy to surpass. Several, however, have not sufficiently 
 appreciated the direct influence of their mode of union on the purposes 
 which they are destined to fulfil ; no one has insisted sufficiently on 
 the manner in which they all concur to a principal object, the preser- 
 vation of the organs enclosed within the skull. 
 
 Hunauld, in a memoir inserted among those of the Academy of 
 Sciences for the year 1730, was the first that endeavoured to account 
 for the arrangement of the articulating surfaces of the bones of the 
 skull. After laying down a few principles on the theory of arches, and 
 after shewing, that the difference of extent of their concave and con- 
 vex surfaces render it necessary that the parts of which they are formed 
 should be shaped obliquely, he explains the advantages of the squa- 
 mous articulation between the temporal and parietal bones. 
 
 When the arch of the cranium is loaded with a very heavy burthen, 
 the temporal bones prevent the parietals on which the effort is imme- 
 diately applied from being forced inwardly, or from being separated 
 outwardly. Hunauld very aptly compares them to buttresses, which 
 are to the parietal bones of the same use as walls to the arches which 
 they support. 
 
 Bordeu* endeavoured to apply to the bones of the face the prin- 
 ciples by which Hunauld has been guided in his investigation with 
 regard to those of the skull. According to Bordeu, the greater part of 
 the bones of the upper jaw, but particularly the superior maxillary 
 bones, resist the effort of the lower jaw, which, by acting on the upper 
 dental arch, has a perpetual tendency to force upward, or to separate 
 outwardly, the bones in which the teeth of that jaw are inserted. As 
 the greatest stress of the effort determines them upward, it is likewise 
 in that direction that the bones of the upper jaw rest most powerfully 
 
 * Acadfmie det Sciencei, Mt'moircs prescntes par let Savant Ed-angers, torn. iii.
 
 OF THE COVERINGS OF THE BRAIN. 317 
 
 on those of the skull. The author concludes this very ingenious me- 
 moir, by proposing to physiologists the solution of the following pro- 
 blem : " When a man supports a great weight on his head, and holds 
 at the same time any thing very firmly between his teeth, which is the 
 bone of the head that is most acted upon? which supports the weight 
 of the whole machine ?" 
 
 The body of the sphenoid, and especially its posterior half, appears 
 to me to be the central point on which the united efforts of the 
 bones of the skull and of the face act. in the case supposed by 
 Bordeu. 
 
 The sphenoid is connected with all the other bones of the skull ; it 
 is immediately connected with several of the bones of the face, as with 
 the malar bones, with the palatine bones, with the vomer, and some- 
 times with the superior maxillary bones. These bones of the face, in 
 the case in question, alone support the lower jaw against the upper. 
 The ethmoid bone, the ossa unguis, and the inferior turbinated bones, 
 are thin and frail, and serve merely to form the nasal fossae, of which 
 they increase the windings, and do not deserve to be attended to in 
 this investigation. The vomer may, it is true, communicate to the eth- 
 moid, in an inferior degree, a part of the effort ; for the anterior part of 
 its upper edge is articulated with the perpendicular lamellae of that 
 bone ; but this quantity is very small, as the vomer is thin, and trans- 
 mits it almost wholly to the body of the sphenoid, with the lower face 
 of which it is articulated. 
 
 The effort exerted on the bones of the upper jaw is transmitted, by 
 means of the nasal processes of the upper maxillary bones, by the 
 orbitar and zygomatic processes of the malar bones, and by the upper 
 edge of the palate bones and of the vomer, to the frontal, to the 
 temporal, and sphenoidal bones. 
 
 If we wish to determine what becomes of the greater part of the 
 effort transmitted to the frontal bone by the maxillary and malar 
 bones, we may observe, in the first place, that it is articulated with the 
 sphenoid bone by the whole of its lower edge, which is bevelled at its 
 inner part, so that it is covered by the arlae minores of the os sphenoides, 
 which is shaped obliquely at the outer part of the bone. The frontal 
 bone is articulated, besides, with the latter and inferior parts of its 
 upper edge. The remainder of this upper part is united to the 
 anterior edge of the parietal bones, which, by means of a slope in a 
 different direction, rest on the middle part of this edge, while the 
 frontal bone is applied to them laterally. 
 
 This bone, which the effort tends to force upward and backward, 
 cannot yield to this double impulse ; for, on the one hand, its mode of 
 articulation with the anterior edge of the alae minores of the sphenoidal
 
 318 OF THE COVERINGS OF THE BRAIN. 
 
 bone, and the internal part of the anterior edge of the parietal bones, 
 resist this tendency upward, while the resistance from the latter 
 prevents them being forced backward. That share of the effort which 
 affects the parietal bones follows the curved line described by these 
 bones, and extends along that formed by the occipital, and thus 
 reaches the posterior face of the body of the sphenoid bone. 
 
 The portion directly transmitted to the anterior and inferior face 
 of this bone by the ossa palati and by the vomer, is inconsiderable, 
 and proportioned to their thinness. The anterior half of the body of 
 the sphenoid bone, hollowed by the sphenoidal sinus, would have been 
 incapable of supporting greater pressure. Lastly, the situation of the 
 body, placed between the dental arches, in front of the place occupied 
 by the ossa palati, explains why this transmission is chiefly effected by 
 the upper maxillary bones. 
 
 The above is the manner in which the effort exerted from below 
 upward, by the lower on the upper jaw, is carried to the anterior, 
 posterior, and inferior faces of the body of the sphenoid bone. 
 
 The temporal bones, which are affected by it in a very slight 
 degree, by means of the zygomatic processes of the malar bones, 
 support the greater weight of the effort acting from above downward, 
 or from the arch of the skull towards its base. The weight laid on the 
 head tends to depress or to separate the parietal bones, which resist 
 the pressure, in consequence of the support afforded them by the 
 temporals. These transmit the effort to the lateral and posterior 
 parts of the body of the sphenoid, by means of the alee majores of 
 that bone, which are articulated, along the whole extent of their 
 external edge, and along the posterior fourth of their internal edge, 
 with the temporals. Besides, the upper extremity of the alse majores 
 is sloped on the inner part of the bone, that it may be articulated 
 with the anterior and inferior angles of the parietal bones, and 
 answer the same purpose to them as the squamous portion of the 
 temporals. 
 
 The lateral and posterior parts of the body of the sphenoid support, 
 therefore, almost the whole effort of the pressure applied to the 
 parietal bones. It is communicated to them by the alae majores, 
 which receive it themselves, either directly at the anterior and inferior 
 angles of this bone, or through the medium of the temporals. The 
 small portion of the effort transmitted by the latter to the occipital 
 follows the curved line of this bone, and is felt on the posterior face of 
 the body of the sphenoid. 
 
 To the effort resulting from the pressure exerted by the body on 
 the summit of the head, one should add that occasioned by the 
 contraction of the muscles which elevate the lower jaw. These tend
 
 OF THE COVERINGS OF THE BRAIW. 319 
 
 to depress the temporal, the malar, and sphenoid bones; and in this 
 action they employ a power equal to that by which they raise the 
 lower jaw, and press it firmly against the upper. 
 
 The effort exerted from the arch to the base of the skull depends, 
 therefore, on two very different causes : the portion resulting from the 
 action of the elevators of the lower jaw is equal to the effort exerted 
 from below upward by this bone. After what has been stated, it 
 would be useless to say any thing further of the manner in which the 
 effort is transmitted : we may merely observe, that the least powerful 
 of these muscles, the internal pterygoid, tends to draw the sphenoid 
 downward, and prevents this bone, fixed like a wedge, with its base 
 turned upward, from being disengaged by the effort applied to it by 
 the bones between which it is situated. 
 
 The posterior, anterior, inferior, and lateral faces of the sphenoid 
 bone support, therefore, the whole effort of the bones of the skull and 
 face, on one another, when, the top of the head being loaded with a 
 heavy burden, one presses at the same time something very firmly 
 between the dental arches. 
 
 The anterior part of the body of the bone, containing the sphe- 
 noidal sinus, is thin and very frail ; the posterior part, corresponding 
 to the cella turcica, is alone capable of resisting the effort which I 
 believe it is destined to sustain;* hence it is at this point that 
 ossification begins ; and this confirms the observation of Kerkringius, 
 that the spot at which bones begin to ossify is that on which they 
 have to bear the greatest effort; thus the alse majores, by means of 
 which .the greatest part of the efforts that the body of the sphenoid 
 has to support,; arise from the lateral parts of its posterior half, by an 
 origin of considerable size, and which is further increased by the base 
 of the pterygoid processes which arise from its lower part. 
 
 The shocks which the cranium has often to endure are chiefly 
 experienced towards its base, where its parietes are thickest, and offer 
 the greatest resistance. This transmission of the shock to the base 
 explains wherefore, in wounds or injuries of the head, fractures often 
 take place in the base, whilst the rest of the skull, even at the place 
 of the external injury, preserved its integrity. 
 
 I have in this inquiry purposely avoided mentioning the support 
 
 * The sphenoidal sinus is prolonged, it is true, into this posterior part of the 
 body of the bone, in persons far advanced in years; but the parietes of this 
 portion of its cavity are of considerable thickness. The anterior part of the 
 basilary process of the occipital bone is then firmly united to the sphenoid, and 
 may be considered as forming a part of that bone, from which it cannot be 
 detached. The cranium of an old man, in this respect, resembles that of several 
 quadrupeds, in which the union of the sphenoid to the occipital bone takes place so 
 early, that these two bones might well be considered as forming but one.
 
 320 OF THE COVERINGS OF THE BRAIN. 
 
 which the head receives from the vertebral column, and which, in the 
 case under consideration, is of use merely in preventing it from 
 yielding to the law of gravitation. If the bones of the skull and of 
 the face had pressed, during the effort which they sustain, on the 
 circumference of the foramen magnum, this aperture would have been 
 incapable of increasing its dimensions, and this would have been 
 attended with the most serious inconveniences. 
 
 The name given by the ancients to the bone whose principal use 
 has just been explained, is composed of sphenos, which means a 
 wedge, and eidos, which signifies resemblance ; and would lead one to 
 think that they were not ignorant of its uses. From its situation, 
 at the middle and inferior part of the skull, and from its various 
 connexions with the bones which form this osseous case, it is to them 
 of the same use as the key-stone of arches, with regard to the different 
 parts of which they are formed. The numerous connexions required 
 for this purpose, account for its strange and irregular form, and for the 
 different shapes of its articular surfaces, and the great number of its 
 projections, which render the demonstration of this bone so com- 
 plicated, and a knowledge of it so difficult. 
 
 It is more advantageous, with regard to the brain, that the skull 
 should be formed of several bones, than if it had consisted of a single 
 bone. It resists more effectually the blows it receives, their effect 
 being lessened in passing from one bone to the other, and being 
 interrupted in the obscure motions which they may experience at their 
 sutures ; its rounded form increases likewise its power of resistance. 
 This force would be equal, in every point of the parietes of the 
 cranium, if the form of that cavity were completely spherical, and if 
 the thickness of its parietes were, in every part of it, the same. In 
 that case, no fractures by contre coup could occur, a kind of lesion 
 occasioned by the unequal resistance of the bones of the head to the 
 force applied to their surface. The pericranium, the hairy scalp, the 
 muscles which cover it, and the great quantity of hair on its surface, 
 serve, besides, to defend the brain, and are well calculated to break the 
 force of blows applied to the cranium. 
 
 In addition to this hard and unyielding case, there lies over the 
 brain a treble membranous covering, formed by the dura mater, which 
 owes its name to the erroneous opinion, according to which it was 
 supposed to form all the other membranes of the body ; it is further 
 covered by the tunica arachuoidea, so called from the extreme 
 minuteness of its tissue ; and by the pia mater, which adheres firmly to 
 the substance of the brain. 
 
 The dura mater lines not only the inside of the skull and of the 
 vertebral canal, which may be considered as a prolongation of it, but 
 likewise penetrates between the different parts of the cerebral mass,
 
 SIXR OF THE BRAIK. 321 
 
 sxipports them in the different positions of the head, and prevents 
 mutual compression. Thus, the greatest of its folds, the falx, 
 stretched between the crysta galli of the ethmoid bone, and the inner 
 protuberance of the occipital bone, prevents the two hemispheres of 
 the brain, between which it lies, from compressing each other, when 
 the body is on the side, and maintains on the other hand the tentorium 
 cerebelli in the state of tension necessary to enable it to support the weight 
 of the posterior lobes of the brain. This second fold of the dura mater is 
 of a semicircular form, and separates the portion of the skull which 
 contains the brain from that in which the cerebellum is situated. It is 
 kept in a state of tension by the falx cerebri, on which it also exerts 
 the same action : it does not present an horizontal plane to the portion 
 of brain which lies upon it, but one that slopes in every direction 
 towards the parietes of the skull, to which it transmits most of the 
 weight which it has to support. The tentorium cerebelli, which thus 
 divides the internal cavity of the skull into two parts of unequal 
 dimensions, is bony in some animals that move by bounding and with 
 rapid action : this is the case with the cat, which can, without being 
 stunned, take leaps from a considerable height. By means of this 
 complete partition, the two portions of the brain are prevented from 
 pressing on each other, in the violent concussions which they 
 experience. 
 
 The tunica arachnoides, according to Bohn,* who was thoroughly 
 acquainted with its structure, and who has given a very beautiful plate 
 of it, is the secretory organ of the serum which moistens the internal 
 surface of the dura mater, a fibrous membrane which serves as a 
 periosteum to the bones it lines.f 
 
 CXLIII. Of the size of the brain.\ Of all animals, man has the 
 most capacious skull in proportion to his face ; and as the bulk of 
 the brain is always of a size proportioned to that of the osseous case 
 which contains it, the brain is also most bulky in man. This 
 difference of size between the cranium and face may be taken as the 
 measure of the human understanding and of the instinct of the lower 
 animals : the stupidity and ferocity of the latter are greater according 
 
 * Dissertatio de Con-tinuationibus Membranarum. Lugdun. Bat. 4to, 1763. 
 
 f Analogous to the serous membranes which line the cavities of the body, the 
 arachnoid is a shut sac, whose internal surface is every where in contact with 
 itself, while its external surface "adheres to the two other meninges. The serosity 
 Which exudes from the internal surface of the arachnoid differs from that which 
 escapes from the other serous membranes, owing to the almost entire absence of 
 albumen from the former. The exhalation that takes place from this membrane 
 appears to be the source of a more limpid and dilute effusion, even in disease, than 
 that which is observed in the other serous cavities. J. C. 
 
 See APPENDIX, Note G G. 
 
 y
 
 322 SIZE OF THE BRAIN". 
 
 as the proportions of these two parts of their skull vary from those of 
 the human head. 
 
 To express this difference of ^ize, Camper imagined ft vertical line,, 
 drawn from the forehead to the chin, and perpendicular to another 
 drawn in the direction of the base of the skull. He has called the 
 first of these lines facial, the second palatine or mental. It is easy to 
 understand, that as the projection of the forehead is determined by 
 the size of the skull, the larger it is the more the angle at which the 
 facial line meets that from the base of the skull must be obtuse. In a 
 well-formed European head, the facial line meets the palatine at an 
 angle nearly straight (6f between 80 and 90 degrees). When the 
 angle is quite straight, and the line which measures the height of the 
 face is completely vertical, the head is of the most beautiful form 
 possible ; it approaches most to that conventional degree of perfection 
 which is termed ideal beauty. If the facial line slopes backward, it 
 forms with the palatine line an angle more or less acute ; and project- 
 ing forward, the inclination increases, and the sinus of the angle is 
 shorter. If from man we pass to monkeys, then to quadrupeds, to 
 birds, reptiles, and fishes, we find this line slope more and more, and 
 at last become almost parallel to the mental, as in reptiles, and in 
 fishes with flat heads. If, on the contrary, we ascend from man to 
 the gods, whose images have been transmitted to us by the ancients, 
 we find the facial line to incline in a different direction : the angle then 
 enlarges and becomes more or less obtuse. From this inclination 
 forward of the facial line there results an air of grandeur and ma- 
 jesty, a projecting forehead, indicating a voluminous brain and a divine 
 intellect. 
 
 To obtain with precision, by this means, the respective dimensions 
 of the skull and face, one must measure, not only the outside, but 
 likewise draw the tangents on the internal surfaces, after dividing the 
 head vertically. There are, in fact, animals in which the sinuses of 
 the frontal bone are so large that a considerable portion of the parietes 
 of the skull is protruded by their cells. Thus, in the dog, in the 
 elephant, in the owl, &c. the apparent size of the skull exceeds greatly 
 its real capacity.* 
 
 The relative size of the head, and consequently the proportionate 
 bulk of the brain , is inconsiderable in very tall and muscular subjects : 
 this fact will be confirmed by observing the proportions of antique 
 statues. In all those which represent heroes or athletes gifted with a 
 prodigious bodily power, the head is very small in proportion to the 
 rest of the body. In the statues of Hercules, the head scarcely 
 equals in size the top of the shoulder. The statues alone of the 
 
 * See APPENDIX, Notes G G.
 
 STKUCTURE OF THE BllAItf. 333 
 
 king of the gods present the singular combination of an enormous 
 head resting on limbs of a proportionate size : but the Greek artists 
 have transgressed the laws of nature only in favour of the god that 
 rules over her, as if a vast brain had been necessary to one whose 
 intellect carries him, at a glance, over the whole universe. The rela- 
 tively small dimensions of the head in athletes depend on this circum- 
 stance, that in such men the excessive development of the organs of 
 motion gives to the body, and especially to the limbs, an enormous 
 size; while the head, covered by few muscles, remains very small. 
 Soemmering has stated, that the head in women is larger than in 
 men, and that their brain is heavier ; but it must be recollected, that 
 this great anatomist obtained this result by examining two bodies, male 
 and female, of the same length. Now, the absolute size being the 
 same, the proportionate magnitude was not so, and he was wrong in 
 comparing the head, the skull, and brain of a very tall woman to that 
 of a very short man. 
 
 It has long been believed that there exists a connexion between the 
 bulk of the cerebral mass and the energy of the intellectual faculties. 
 It has been thought that, in general, men whose mind is most capa- 
 cious, Avhose genius is most capable of bold conceptions, had a large 
 head supported on a short neck. The exceptions to this general rule 
 have been so numerous, that many have doubted its truth . should it 
 then be absolutely rejected ? and will it be allowed to be wholly without 
 foundation, when we consider that man, the only rational being out of 
 so great a number, and some of which bear to him a considerable 
 resemblance both as to organisation and structure, is likewise the only 
 animal in which the brain, properly so called, is largest in proportion 
 to the cerebellum, to the spinal marrow, to the nerves, and to the other 
 parts of the body ? Why may it not be with the brain as with the 
 other organs, which fulfil their functions the better from being more 
 completely developed ? It should be recollected, in this comparison 
 of the brain and of the intellectual powers, that several causes may 
 give to this viscus an unnatural degree of enlargement. Thus, in 
 subjects of a leucophlegmatic temperament, the tardy ossification of 
 the bones of the skull causes the brain, gorged with aqueous fluids, to 
 acquire a considerable size, without its containing a greater quantity of 
 real medullary substance. Hence it is observed, that men of this 
 temperament are most frequently unfit for mental exertion, and rarely 
 succeed in undertakings that require activity and perseverance.* 
 
 CXLIV. Structure of the cerebral mass.- What we know of the 
 brain serves only to shew us that we are ignorant of much more. All 
 
 * See, in the article on Temperaments, an account of the influence of the physical 
 organisation on the moral disposition and on the intellectual faculties.
 
 324 STRUCTURE OF THE BRAIN. 
 
 that we know of it consists of tolerably exact notions of its external 
 conformation, its colour, its density, and of the different substances 
 that enter into its composition ; but the knowledge of its intimate 
 structure is yet a mystery, which will not be so soon unveiled to us. 
 The brain, properly called, is divided by a longitudinal furrow into 
 two lobes of equal bulk. Gunzius, however, imagined that he found 
 the right lobe, or hemisphere, a little larger than the left : but even 
 were this fact as certain as it is doubtful, we could not thereby explain 
 the predominant force of the right side of the body ; since the nerves 
 which are distributed to this side rise from the left lobe of the brain, 
 in the substance of which all the roots of these cords cross. This fact 
 of the crossing of the nerves at their origin is proved by a multitude of 
 pathological observations, in which the injury of a lobe is always found 
 to bring on paralysis, convulsion, or some, other symptomatic affection, 
 on the opposite side of the body, unless you choose to explain this 
 phenomenon by admitting a necessary equilibrium in the action of the 
 two lobes an equilibrium, the disturbance of which is the occasion 
 that the sound lobe, acting with more force, compresses the origin of 
 the nerves on its side, and determines paralysis. May not the want of 
 judgment, the unevenness of humour and character, depend on the 
 want of harmony between the two corresponding halves of the cere- 
 bral mass? 
 
 In order to disclose, better than had before been done, the structure 
 of the brain, M. Gall began his dissection at the lower part : examining, 
 in the first place, the anterior part of the prolongation, known under 
 the name of cauda of the medulla oblongata, he finds the two pyra- 
 midical eminences. If you part the two edges of the median line 
 below the furrow which separates the two pyramids, you see distinctly 
 the crossing of three or four cords, or fasciculi of nerves, which, con- 
 sisting of many filaments, tend obliquely from right to left, and vice 
 versd. This crossing of nervous fibres, which is not found in any other 
 part of the brain, had been observed by several anatomists : it is not 
 known how it came to be forgotten ; so that the most exact and latest 
 among them, Boyer for instance, says that the crossing of the nerves 
 cannot be proved by anatomy. These nervous cords, traced upwards, 
 enlarge, strengthen, and, forming pyramidical eminences, ascend to- 
 wards the tuber annulare. Having reached the ganglion, the fibres 
 strike into it, and are lost in a mass of pulpy or grayish substance, of 
 the same nature as that which, under the name of cortical substance, 
 covers the two lobes of the brain. This grayish pulp, distributed in 
 various parts, may be considered, agreeably to the views of M. Gall, 
 who calls it the matrix of the nerves, as the source from which the 
 medullary fibres take their origin. These ascending fibres cross other 
 transverse fibres, which, on either side, proceed from the crura of the
 
 STRUCTURE OF THE BRAIN. 325 
 
 cerebellum, enlarged and multiplied by means of their passage through 
 the gray substance which is found in the tuber annulare : they rise from 
 it at its upper part in two fasciculi, which compose nearly the whole 
 of the crura cerebri. The interior of these crura contains a certain 
 quantity of gray substance, which is what nourishes the nervous fibre. 
 On reaching the ventricles, these peduncles, or rather the two fasciculi 
 of fibres which form them, meet with large ganglions, full of gray sub- 
 stance : they have long been called thalami optici, though they do not 
 give origin to the optic nerves. There the fibres are sensibly enlarged, 
 and they pass from the thalami optici into new ganglions. These are 
 the corpora striata ; and the striae which are apparent on cutting these 
 pyriform masses of gray substance are only the same fibres, which, 
 enlarged, multiplied,- and radiated, spread out in the manner of a fan 
 towards the lobes of the brain, where, after forming by their expansion 
 a whitish and fibrous substance, they terminate at the outer part of 
 that viscus, forming its convolutions, all covered with the substance in 
 which are terminated in like manner the extremities of the diverging 
 fibres. From this gray substance proceed cortverging fibres, tending 
 from all parts of the periphery to the centre of the brain, where they 
 unite to form the different commissures, the corpus callosum, and 
 other productions destined to facilitate the communication of the two 
 hemispheres.* 
 
 The exterior of the brain may, therefore, be considered as a vast 
 nervous membrane, formed by the gray substance. To have a due 
 conception of its extent, it must be understood that the convolutions 
 of the brain are a sort of duplicatures, susceptible of extension by 
 the unfolding of two contiguous medullary laminae which form its 
 base. The exterior surface of the brain, by means of this unfolding, 
 offers then some relation to the skin, a vast nervous expanse every 
 where covered by a sort of pulpy substance, known by the name of the 
 rete mucosum of Malpighi. M. Gall compares this cutaneous pulp to 
 the cineritious substance which forms the outer part of the brain ; and, 
 I must confess, it is not every one that will admit the analogy. How- 
 ever, true it is that the brain consists principally of a mass of ganglions, 
 that it produces neither the elongated medulla nor the spinal marrow, 
 that this last may be considered as a series of ganglions united to- 
 gether, that the vertebral nerves arise from the grayish pulp of which 
 the spinal marrow is full, as is best seen in animals without a brain, 
 but not the less provided with a spinal marrow, or series of ganglions, 
 from which the nerves arise, and that the ganglions, or rather the 
 gray substance which they always shew, produce the nervous fibres, and 
 thicken the nervous cords that pass through them. 
 
 * See APPENDIX, Notes G G.
 
 326 CIRCULATION IK THE BRAIN. 
 
 That is the only use that can be assigned to these parts of the 
 nervous system ; for if they were meant to withdraw from the do- 
 minion of the will the parts in which they are found, why do not the 
 ganglions of the vertebral nerves fulfil' the same function ? All 
 these nerves communicate by reciprocal anastomoses. These commu-p 
 nications in man are equivalent to a real continuity. In truth, the 
 brain acts upon the nerves that proceed from the spinal marrow as if 
 this were one of its productions, and all the nervous fibres spread 
 through the different organs had an extremity terminating in this 
 viscus. 
 
 One thing well worthy of attention, and on which no anatomist 
 has dwelt, is, that the brain of the foetus, and of the child just born, 
 appears to consist almost entirely of a cineritious pulp, to such a 
 degree that the medullary substance is with difficulty perceived in it. 
 Would it be absurd to believe, that the medullary part of the brain 
 does not take its perfect organisation till after birth, by the develop- 
 ment of the fasciculi of medullary fibres in the midst of these 
 masses of cinefitious substance, which must be considered as the 
 common source from which the nerves have their origin ; or, to use 
 the language of Gall, as the uterus which gives them birth. The 
 almost total inactivity, the passive state of the brain in the foetus, 
 makes unnecessary there the existence of the medullary apparatus, to 
 which the most important operations of intelligence seem intrusted. 
 Its first rudiments are found in the foetus at its full time. That fibro- 
 medullary apparatus will be strengthened by the exercise of thought, 
 as the -muscles are seen to enlarge and perfect their growth by the 
 effect of muscular action.* 
 
 CXLV. Circulation in the brain. I have said that the blood, in 
 its circular course, does not traverse the different parts of the body 
 with uniform velocity, that there are partial circulations in the midst 
 of the general circulation. In no organ are the laws to which this 
 function is subjected more remarkably modified than in the brain. 
 There is none which receives, in proportion to its bulk, larger arteries 
 and more in number. The internal carotid and vertebral arteries, as 
 
 . * See the APPENDIX, Notes G G, where the reader will find some observa- 
 tions by the Editor, on the development of the spinal cord and brain, and on the 
 functions of the cerebro-spinal nervous system in man and the lower animals. The 
 views contained in that part of our Appendix were published in the former edi- 
 tion of our Notes, before the publication of the work of M. Serres, which soon 
 afterwards appeared, and fully confirmed them. We think it right thus to allude 
 to the circumstance, as some physiological writers have taken occasion to quote 
 M. Serres as the originator of these views, without reference to the earlier publica- 
 tion of similar opinions in this country, opinions which had been long enter- 
 tained, and frequently discussed by us with anatomists and physiologists, both in 
 this country and on the continent, before their publication. .7. C,
 
 CIRCULATION IN THE BRAIN. 32T 
 
 we may satisfy ourselves from the calculations of Haller, carry 
 thither a great portion of the "whole quantity of blood that flows 
 along the aorta (from a third to a half). 
 
 The blood which goes to the brain, said Boerhaave, is more 
 aerated than that which is distributed to the other parts : the obser- 
 vation is not without foundation. Though the blood which the con- 
 tractions of the left ventricle send into the vessels arising from the 
 arch of the aorta does not undergo at the place of this curvature a 
 mechanical separation, carrying its lighter parts towards the head; 
 it is not less true that this blood, just passing from the contact of 
 the air in the lungs, possesses, in the highest degree, all the peculiar 
 qualities of arterial blood. So great a quantity of light, red, frothy 
 blood, impregnated with caloric and oxygen, coming upon the brain 
 with all the force it has received from the action of the heart, would 
 unavoidably have deranged its soft and delicate structure, if Nature had 
 not multiplied precautions to weaken its impulse. 
 
 The fluid, compelled to ascend against its own weight, loses, from 
 that cause alone, a part of its motion. The vertical column must strike 
 against the angular curvature which the internal carotid makes in its 
 passage along the osseous canal of the petrous portion of the temporal 
 bone ; and as this curvature, supported by hard parts, cannot straighten 
 itself, the column of blood is violently broken, and turned out of its 
 first direction with considerable loss of velocity. 
 
 The artery immersed in the blood of the cavernous sinus, as it comes 
 out from the carotid canal, is very easily dilated. Finally, the branches 
 into which it parts on reaching the base of the brain have coats 
 exceedingly thin, and so weak that they collapse when they are empty 
 like those of the veins. This weakness of the cerebral arteries explains 
 their frequent ruptures, when the heart sends the blood into them too 
 violently ; and it is thus that the greater part of sanguineous apoplexies 
 are occasioned, many of which, however, take effect without rupture, 
 and by the mere transudation of blood through the coats of the arteries. 
 These vessels, like the branches arising from their divisions, are lodged 
 in the depressions with which the base of the brain is furrowed, and 
 do not enter its substance 1^11 they are reduced to a state of extreme 
 tenuity, by the further divisions they undergo in the tissue of the pia 
 mater. 
 
 Notwithstanding the proximity of the brain to the heart, the blood 
 reaches it, then, with an exceedingly slackened motion ; it returns, on 
 the contrary, with a motion progressively accelerated. The position 
 of the veins at the upper part of the brain, between its convex surface 
 and the hollow of the skull, causes these vessels, gently compressed by 
 the alternate motions of rising and falling of the cerebral mass, to 
 disgorge their contents readily into the membranous reservoirs of the
 
 328 ACTION OF THE BRAIN. 
 
 dura mater, known by the name of sinuses. These, all communicating 
 together, offer to this fluid a sufficiently large receptacle, from which it 
 passes into the great jugular vein, which is to carry it again into the 
 general course of the circulation. Not only is the calibre of this vein 
 considerable, but its coats too, of little thickness, are very extensible : 
 so much so, that it acquires by injection a calibre superior to that of 
 the venae cavse. The flowing of thq blood is favoured by its own- 
 weight, which makes a retrograde course very difficult.* Thus, to sum 
 up all that is peculiar in the cerebral circulation, the brain receives 
 in great quantity a blood abounding in oxygen ; the fluid finds in its 
 course thither many obstacles which impede and slacken its impulse, 
 whilst all, on the contrary, favour its return, and prevent venous 
 congestion.f Let me observe, to conclude what I have to say on the 
 circulation of the brain, that that of the eye is nearly allied to it, since 
 the ophthalmic artery is given out by the internal carotid, and the oph- 
 thalmic vein empties itself into the cavernous sinus of the dura mater. 
 Accordingly, the redness of the conjunctiva, the prominence, the 
 brightness, the moistness of the eyes, indicate a stronger determina- 
 tion of the blood towards the brain. Thus, the eyes are animated at 
 the approach of apoplexy, in the transport of a burning fever, and 
 during delirium, which is a dangerous symptom of malignant or ataxic 
 fevers. Oa this connexion of the vessels of the eye and brain depends 
 the lividity of the conjunctiva, whose veins, injected with a dark-coloured 
 blood, indicate the fulness of the brain in the generality of cases of 
 suffocation. 
 
 CXLVI. Of the connexion between the action of the brain and that 
 of the heart. It is possible, as was done by Galen, to tie both caro- 
 tids in a living animal without its appearing sensibly affected by it ; 
 but if, as has never yet been done, both Tne vertebral arteries are tied, 
 the animal drops instantly, and dies at the end of a few seconds. To 
 perform this experiment, it is necessary, after tying the carotid 
 arteries of a dog, to remove the soft parts which cover the side of the 
 neck ; then with needles, bent in a semicircular form, passed into 
 the flesh along the sides of the articulation of the cervical vertebrae, 
 to apply ligatures to the arteries which ascend along their trans- 
 verse processes. The same effect, viz. the speedy death of the animal, 
 is produced by tying the ascending aorta in an herbivorous quadruped. 
 
 * In preventing this reflux, there is no use of valves, which the jugular vein is 
 entirely without. It is sufficiently prevented by the direction in which the "blood 
 flows, and the extensibility of its coats. This great size which the vein can acquire 
 would have made useless the valvular folds, aud insufficient to stop the canal, in 
 that great augmentation of its dimensions. 
 
 f The transverse anastomoses of the arteries at the base of the braia are very 
 proper for distributing the blood in equal quantity to all parts of this viscus.
 
 ACTION OF THE LllAIX. 329 
 
 These experiments, which have been repeated a number of times, 
 decidedly prove the necessity of the action of the heart on the brain 
 in preserving life. But how does this action operate ? Is it merely 
 mechanical ? Does it consist solely in the gentle pressure which the 
 arteries of the brain exert on the substance of this viscus, or is it 
 merely to the intercepted arterial blood which the contractions of the 
 heart determine towards the brain, that death is to be attributed ? 
 The latter opinion seems to me the most probable; for if, the mo- 
 ment the vertebrals have been tied, the carotids are laid open, and 
 the pipe of a syringe adapted to them, and any fluid whatever is 
 then injected with a moderate degree of force, and at nearly the 
 same intervals as those of the circulation, the animal will not be restored 
 to life. 
 
 The heart and brain are, therefore, united to each other by the 
 strictest connexion ; the continual access of the blood flowing along 
 the arteries of the head is, indeed, absolutely necessary to the pre- 
 servation of life ; if intercepted for one moment, the animal is infallibly 
 destroyed. 
 
 The energy of the brain appears, in general, to bear a relation 
 to the quantity of arterial blood which it receives. I know a literary 
 man who, in the ardour of composition, exhibits all the symptoms of 
 a kind of brain fever. His face becomes red and animated, his eyes 
 sparkling; the carotids pulsate violently ; the jugular veins are swollen; 
 every thing indicates that the blood is carried to the brain with an 
 impetus, and in a quantity, proportioned to its degree of excitement. 
 It is, indeed, only during this kind of erection of the cerebral organ, 
 that his ideas flow without effort, and that his fruitful imagination 
 traces-, at pleasure, the most beautiful descriptions. Nothing is so 
 favourable to this condition as remaining long in a recumbent posture : 
 in this horizontal posture, the determination of the fluids towards the- 
 head is the more easy, as the limbs, which are perfectly quiescent, do 
 not divert its course. He can bring on this state by fixing his attention 
 steadfastly on one object. May not the brain, which is the seat of 
 this intellectual action, be considered as a centre of fluxion; and 
 may not the stimulus of the mind be compared, as to its effects, to 
 any other stimulus, chemical or mechanical ? 
 
 A young man of a sanguineous temperament, subject to inflamma- 
 tory fevers, which always terminate by a profuse bleeding at the nose, 
 experiences, during the febrile paroxysms, a remarkable increase of his 
 intellectual powers, and of the activity of his imagination. Authors 
 had already observed, that in certain febrile affections patients of very 
 ordinary powers of mind would sometimes rise to ideas which in a state 
 of health would have exceeded the limits of their conception. May we 
 not adduce these facts in opposition to the theory of a celebrated phy-
 
 330 THEORY OF SYNCOPE. 
 
 sician, who considers a diminution of the energy of the brain to be the 
 essential character of fever ? 
 
 It is well known that the difference of the length of the neck, and, 
 
 consequently, the greater or lesser degree of vicinity of the heart and 
 
 brain, give a tolerably just measure of the intellect of man, and of the 
 
 jnstinct of the lower animals ; the disproportionate length of the neck 
 
 *^ias ever been considered as the emblem of stupidity. 
 
 In the actual state of our knowledge, is it possible to determine in 
 what manner arterial blood acts on the brain ? Are oxygen or caloric, 
 of which it is the vehicle, separated from it by this viscus, so as to 
 become the principle of sensation and emotion ? or do they merely pre- 
 serve it in the degree of consistence necessary to the exercise of its 
 functions ? What is to be thought of the opinion of those chemists 
 who consider the brain as a mere albuminous mass, concreted by 
 oxygen, and of a consistence varying in different persons, according 
 to the age, the sex, or the state of health or disease ? Any answer 
 that one might give to these premature questions would be but a simple 
 conjecture, to which it would be difficult to assign any degree of 
 probability.* 
 
 CXLVII. Of the theory of syncope. If we consider the action of 
 
 * The connexion which exists between the functions of the heart and those of 
 the brain are not only manifest in their healthy relations, but also in their dis- 
 ordered actions. Portal, Bricheteau, and Testa, had pointed out this connexion in 
 the diseases of these organs ; and, more recently, Dr. Craigie has contended for its 
 importance, although some contemporary pathologists have denied its existence. 
 This pathologist, after stating his experience on the subject, draws the following 
 inferences from it : 
 
 " 1st, It is quite obvious that several maladies of the heart, such as ossification 
 of the left side, or of the artery connected with it ; ossification of the neutral valve ; 
 of the semi-lunar valves ; aretation of the apertures, either auriculo-veiitricular or 
 aortic ; have a tendency to terminate in extravasation within the cranium, produ- 
 cing apoplexy, paralysis, or a comatose state terminating in death. 
 
 " 2d, It is by no means difficult to see how these effects in the cerebral organ 
 result from an irregular and disordered action of the heart. The difficulty which 
 the biood experiences in passing either, 1st, through the auriculo- ventricular opeu- 
 " ing ; 2d, the aortic orifice ; 3d, along the aorta, necessarily produces a stagnation 
 and congestion, 1st, in the pulmonary veins ; 2d, in the pulmonary artery ; 3d, in 
 the right side of the heart. The effect of this is to retard or impede very remark- 
 ably the return of the blood from the cerebral veins, and consecutively either to 
 distend them, to rupture theto, or to occasion an effusion of the serous part of the 
 blood, as we find in other examples of obstructed venous circulation." (Edin. Med. 
 Jottr. No. 74.) Dr. Craigie has, however, omitted to mention the influence of 
 active enlargement of the left side of the heart in producing apoplexy, owing to the 
 increased impulse or determination of blood which is thus produced, and to which 
 the brain is most obnoxious. This, arid every other form of connexion of disease of 
 the heart with apoplexy, can only be viewed as occasional occurrences ; the former 
 states being by no means necessarily followed by the latter. J. C.
 
 THEORY OF SYNCOPE. 331 
 
 the heart on the brain, we are naturally led to admit its necessity to 
 the maintenance of life, and to deduce from its momentary suspension 
 the theory of syncope. Several authors have attempted to explain the 
 manner in which their proximate cause operates ; but as not one of 
 them has gone upon facts ascertained by experience, their explanations 
 do not all agree with what is learnt from observing the phenomena of^ 
 these diseases. tij^ 
 
 To satisfy oneself that the momentary cessation of the action of thF 
 heart and the brain is the immediate cause of syncope, one need but 
 read with attention the chapter which Cullen, in his work on the prac- 
 tice of physic, has devoted to the consideration of this kind of affection. 
 It will be readily understood, that their occasional causes, the varieties 
 of which determine their different kinds, ^xist in the heart or great 
 blood-vessels, or act on the epigastric centre, and affect the brain only 
 in a secondary manner. Thus, the kinds of syncope occasioned by 
 aneurismal dilatations of the heart and great vessels, by polypous con- 
 cretions formed in these passages, by ossification of their parietes or of 
 their valves, evidently depend on the extreme debility, or on the entire 
 cessation, of the action of the heart and arteries. Their parietes, ossi- 
 fied, dilated, adhering to the neighbouring parts, or compressed by 
 any fluid whatever, no longer act on the blood with sufficient force ; 
 or else this fluid is interrupted in its progress by some obstacle 
 within its canal, as a polypous concretion, an ossified and immov- 
 able valve. Cullen very justly termed these, idiopathic or cardiac 
 syncopes. 
 
 To the above may be added plethoric syncope, depending on a con- 
 gestion of blood in the cavities of the heart : the contractions of this 
 organ become more frequent, it struggles to part with this excess of 
 blood, which is injurious to the performance of its functions; but to 
 this unusual excitement, by which the contractility of its fibres is 
 exhausted, there succeeds a kind of paralysis, necessarily accompanied 
 by syncope. 
 
 One may, likewise, include the fainting attending copious blood- 
 letting: the rapid detraction of a certain quantity of the vivifying prin- 
 ciple deprives the heart of the stimulus necessary to keep up its action. 
 The same effect is produced by drawing off the water contained in 
 the abdomen in ascites : a considerable number of vessels cease to be 
 compressed ; the blood which they before refused to transmit is sent 
 to them in profusion ; the quantity sent to the brain by the heart is 
 lessened in the same proportion, and becomes insufficient for its ex- 
 citement. Among the syncopes called idiopathic, one may enumerate 
 those occurring in the last stage of the scurvy, the principal character 
 of which is an excessive debility of the muscles employed in the vital 
 functions and in voluntary motion. Lastly, we may add asphyxia from
 
 332 THEORY OF SYNCOPE. 
 
 strangulation, from drowning, and from the gases unfit for respira- 
 tion ; affections in which the blood being deprived of the principle 
 which enables it to determine the contractions of the heart, the cir- 
 culation becomes interrupted. If the blood loses, by slow degrees, 
 its stimulating qualities, the action of the heart, gradually weakened, 
 impels towards the brain a blood which, by its qualities, partakes of 
 the nature of venous blood, and which, like it, cannot preserve the 
 natural economy of the brain. It was thought, that by injecting a few 
 bubbles of air into the jugular vein of a dog, one might occasion in the " 
 animal immediate syncope, and that it was even sufficient to deprive it 
 of life ; but the late experiments of M. Nysten have proved, that the 
 atmospherical air produces these bad effects only when injected in a 
 quantity sufficient to distend in excess the cavities of the heart, or 
 when, by being injected into the arteries, it compresses the brain. 
 When injected only in a small quantity, the gas dissolved in the venous 
 blood 'is conveyed along with it to the lungs, and is thence exhaled in 
 respiration. 
 
 A second class of occasional causes consists of those which, by 
 acting on the epigastric centre, determine by sympathy a cessation of 
 the pulsations of the heart, and the syncope necessarily attending this 
 cessation. Such are the violent emotions of the soul, terror, an 
 excess of joy, an irresistible aversion to certain kinds of food, the 
 dread which is felt on the unexpected sight of an object, the disagree- 
 able impression occasioned by certain odours, &c. In all these cases, 
 there is felt in the region of the diaphragm an inward sensation of a 
 certain degree of emotion. From the solar plexus of the great sympa- 
 thetic nerve, which, according to the general opinion, is considered as 
 the seat of this sensation, its effects extend to the other abdominal 
 and thoracic plexuses. The heart, the greater part of whose nerves 
 arise- from the great sympathetic, is particularly affected by this sen- 
 sation. Its action is at times merely disturbed by it, and at others 
 wholly suspended. The pulse becomes insensible, the countenance 
 pale, the extremities cold, and syncope ensues. This is the course of 
 things when a narcotic or poisonous substance has been taken into 
 the stomach ; when this viscus is much debilitated in consequence of 
 long fasting, or when it contains indigestible substances ; in cholic, and 
 in hysterical affections. 
 
 This last class of occasional causes does not act directly, and pro- 
 duces syncope only at a distant period ; but the result is always the same. 
 It happens in all these cases, that as the arteries of the head no longer 
 receive as much blood as in health, the brain falls into a kind of col- 
 lapse, which occasions a momentary cessation of the intellectual facul- 
 ties, of the vital functions, and of voluntary motion. 
 
 Morgagni, in treating of diseases according to their anatomical
 
 MOTIONS OF THE BRAIN. 333 
 
 order, ranks lypothymia among the affections of the chest, because the 
 viscera contained in that cavity shew marks of organic affection in 
 persons who, during life, were subject to frequent fainting. 
 
 The compression of the brain, by a fluid effused on the dura mater, 
 in wounds of the head, does not produce real syncope, but rather a 
 state of stupor. All causes acting in this manner on the brain pro- 
 duce comatose, and even apoplectic affections. When a man, on being 
 exasperated, falls into a violent and sudden fit of passion, his face 
 becomes flushed, and he is affected with vertigo and fainting. There 
 is no loss of colour, no loss of pulse ; the latter, on the contrary, 
 generally beats with more force. This is not syncope, but the first 
 stage of apoplexy, occasioned by the mechanical pressure on the 
 brain, towards which the blood is carried suddenly and in too great a 
 quantity. 
 
 I might support this theory of syncope by additional proofs drawn 
 from the circumstances which favour the action of the causes giving 
 rise to affections of this kind. For instance, syncope comes on almost 
 always when we are in either an erect or sitting attitude, and in such a 
 case it is right to lay the patient in an horizontal posture. Patients 
 debilitated by long diseases faint the moment they attempt to rise, and 
 recover on returning to the recumbent posture. Now, how are we to 
 explain this effect of standing, in persons in whom the mass of humours 
 is much impoverished, and whose organic action is extremely languid, 
 unless by the greater difficulty to the return of the blood from the more 
 depending parts, and on the difficulty in ascending of that which the 
 contractions of the heart send towards the head ? The phenomena of 
 the circulation are, under such circumstances, more subject to the laws 
 of hydraulics than when the body is in a state of health ; the living 
 solid yields more easily to the laws of physics and mechanics ; and, 
 according to the sublime idea of the father of physic, our individual 
 nature approaches more nearly to universal nature. 
 
 CXLVIII. Of the motions of the brain. Are the alternate mo- 
 tions of elevation and depression seen, when the brain is exposed, 
 exclusively isochronous to the pulsations of the heart and arteries, or 
 do they correspond at the same time to those of respiration ? Such 
 is the physiological problem of which I am about to attempt the 
 solution. 
 
 Those authors who admit the existence of motions in the dura 
 mater do not agree as to the cause which produces them. Some, and 
 among others, Willis and Baglivi, thought they had discovered mus- 
 cular fibres, and ascribed these motions to their action : others, as 
 Fallopius and Bauhinus, attributed these motions to the pulsations of 
 the arteries of that membrane. The dura mater possesses no contrac- 
 tile power ; its firm adhesion to the inside of the skull would, besides,
 
 334 MOTIONS OF THE BRAIN*. 
 
 prevent any such motion. The motion observed in this membrane is 
 not occasioned by the action of its vessels ; for, as Lorry observes, the 
 arteries of the stomach, of the intestines, and of the bladder, do not 
 communicate any motion to the parietes of these hollow viscera, 
 and yet, in number and size, they at least equal the meningeal 
 arteries. 
 
 The motion observed in the dura' mater is communicated to it by 
 the cerebral mass which this membrane covers ; and this opinion of 
 Galen, adopted by the greater number of anatomists, has been 
 placed beyond a doubt by the experiments of Schlitting, of Lamure, 
 Haller, and Vicq-d'Azyr. They have all observed, that on removing 
 the dura mater, the brain continued to rise and fall ; and, with the 
 exception of Schlitting, they agreed that the brain, absolutely passive, 
 received from its vessel the motions in which the dura mater partook ; 
 but are these motions communicated by the arteries or by the cerebral 
 veins, and by the sinuses in which these terminate ? or, in other words, 
 are they isochronous to the beats of the pulse, or to the contraction 
 and successive dilatation of the chest, during respiration ? 
 
 Galen, in his treatise on this function, says, that the air admitted 
 into the pulmonary organ distends the diaphragm, and is conveyed 
 along the vertebral canal into the skull. According to this writer, 
 the brain rises during the enlargement of the chest, and it sinks, on 
 the contrary, when the parietes of this cavity are brought nearer 
 to its axis. Schlitting, in a memoir presented to the Academy of 
 Sciences, towards the middle of the last century, maintains that these 
 motions take place in a different order, the elevation of the brain cor- 
 responding to expiration, and its depression to inspiration. Conceiving 
 that he has determined this fact by a sufficient number of experi- 
 ments, he does not enter into any explanation, and concludes his 
 inquiry by asking whether the motions of the brain are occasioned by 
 the afflux of air or of blood towards that organ. 
 
 Haller and Lamure attempted to answer this difficulty. They both 
 performed a number of experiments on living animals, acknowledged 
 the fact observed by Schlitting, and explained it in the following 
 manner : as well as this last anatomist, Lamure believed that there 
 is a vacuum between the dura and pia mater, by means of which the 
 motions of the brain might always be performed. The existence of 
 such a vacuum is disproved by the close contact of the membranes 
 between which it is supposed to exist. 
 
 During expiration, continues Lamure, the parietes of the chest 
 close on themselves, and lessen the extent of this cavity. The lungs, 
 pressed in every direction, collapse ; the curvature of their vessels 
 increases, and the blood flows along them with difficulty. The 
 heart and great vessels thus compressed, the blood carried by the upper
 
 MOTIONS OF THE BRAIN. 335 
 
 vena cava to the right auricle cannot be freely poured into this 
 cavity, which empties itself with difficulty into the right ventricle, 
 whose blood is unable to penetrate through the pulmonary tissue. 
 On the other hand, as the lungs compress the vena cava, a re- 
 gurgitation takes place of -the blood which it was conveying to the 
 heart; forced back along the jugulars and vertebrals, it distends these 
 vessels, the sinus of the dura mater which empty themselves into 
 them, and the veins of the brain which terminate into these sinuses. 
 Their distension accounts for the elevation of the cerebral mass, an 
 elevation soon followed by depression, when, on inspiration succeed- 
 ing expiration and on the lungs dilating, the blood which fills the 
 right cavities of the heart can freely penetrate into the pulmonary sub- 
 stance, and make way for that which the vena cava is bringing from 
 the superior parts of the body. 
 
 Haller considered this reflux as very difficult, the blood having to 
 rise against its own gravity; and he admitted Lamure's explanations 
 only in the forcible acts of respiration, as in coughing, laughing, and 
 sneezing. He maintained that, in a state of health, there is to be 
 observed, during expiration, a mere stagnation of the blood in the 
 vessels which bring it from the internal parts of the skull. He further 
 admits, on the testimony of a great number of authors, another order 
 of motions depending on the pulsations of its arteries; so that, 
 according to Haller, the cerebral mass is incessantly affected by 
 motions, some of which depend on respiration, while the others are 
 quite independent of it. 
 
 Lastly, according to Vicq-d'Azyr, the brain, on being exposed, 
 presents a double motion, or rather two kinds of motion, from 
 without ; the one from the arteries, and which is least remarkable, the 
 other from the alternate motions of respiration. 
 
 CXLIX. This opposition between authors of reputation, and whose 
 theories have in general been adopted, induced me to repeat the 
 experiments which each of them brings in support of his own opinion, 
 and to perform further experiments on this subject. My investigation 
 soon convinced me, that these authors had given a statement of their 
 opinions, and not of the fact itself. Indeed, the alternate motions of 
 elevation and depression observed in the brain, are isochronous to the 
 systole and diastole of the arteries at its base. The elevation of the 
 brain corresponds to the dilatation of these vessels, its depression to 
 their contractions. The process of respiration has nothing to do with 
 this phenomenon ; and even admitting the stagnation of the re- 
 gurgitation of the blood in the jugular veins, the arrangement of the 
 veins within the skull is such, that this stagnation or reflux could not 
 produce alternate motions of the cerebral mass. 
 
 The brain receives its arteries from the carotids and vertebrals,
 
 336 MOTIONS OF THE BRAlX. 
 
 after they have entered the skull, the former along the carotid canals, 
 the latter through the foramenf magnum of the occipital bone. It 
 would be useless to describe their numerous divisions, their frequent 
 anastomoses, the arterial circle, or rather polygon, formed by these 
 anastomoses, and by means of which the carotid and vertebral arteries 
 communicate together, by the side of the sella turcica. Haller has 
 given a very correct view, and an excellent description of this part.* 
 The account of the internal carotid artery published by that great 
 anatomist is, according to Vicq-d'Azyr, a chef-d'oeuvre of learning and 
 precision ; the same encomium might be bestowed on the latter, who 
 gave a superb drawing of the same part. I shall content myself with 
 observing, that the principal arterial trunks going to the brain are 
 situated at the base of this viscus ; that the branches into which these 
 trunks divide, and the subdivisions of these branches, are likewise 
 lodged at its base in a number of depressions ; and that, in the last 
 place, the arteries of the brain do not penetrate into its substance till 
 after they have undergone in the tissue of the pia mater, which 
 appears completely vascular, very minute subdivisions. 
 
 The vessels which return the portion of blood which has not been 
 employed in the nutrition and growth of the brain, are, on the 
 contrary, situated towards its upper part, between its convex surface 
 and the arch of the cranium : each convolution contains a great vein 
 which opens into the superior longitudinal sinus. The vena Galeni, 
 which deposits into the sinus the blood brought from the choroid 
 plexus ; small veins which open into the cavernous sinuses ; others, 
 likewise very minute, which, passing through the foramina in the alae 
 rnajores of the sphenoid bone, contribute to form the venous plexus of 
 the zygomatic fossa, are the only exceptions to this general rule. 
 
 This being laid down on the arrangement of the arteries and 
 veins, let us examine what will be the effect of their action with 
 regard to this viscus. 
 
 The contractions of the heart propel the blood into the arterial 
 tubes, which experience, especially at the place of their curvatures, 
 a manifest displacement at the time of their dilatation. All the 
 arteries situated at the base of the brain experience both these effects 
 at once. Their united efforts communicate to it a motion of elevation 
 succeeded by depression, when, by their contraction, they re-act on 
 the blood which fills them. 
 
 These motions take place only as long as the skull remains entire ; 
 this cavity is too accurately filled, and there is no void space between 
 the membranes of the brain. Lorry, who, with good reason, denied 
 the existence of such a space, committed an equally serious anatomical 
 
 * Fasciculi anatomic! , f. vii. tab. ii.
 
 CAUSE OF THE BRAIN'S MOTION. 337 
 
 mistake in asserting, that as no motion could take place, on account 
 of the state of fulness of the skull, it was effected in the ventricles, 
 which he considers as real cavities ; but which, as Haller has shewn, 
 are, when in a natural state, merely surfaces in contact. No motion 
 actually takes place, except in those cases in which there is a loss of 
 substance in the parietes of the skull. 
 
 It is easy to conceive, however, that the brain, which is soft and 
 of weak consistence, yields to the gentle pressure of its arterial vessels. 
 Does not this continued action of the heart on the brain explain, in a 
 satisfactory manner, the remarkable sympathy between those two 
 organs, linked by such close connexions ? It is, besides, of very 
 manifest utility, and connected with the return of the blood distributed 
 to the cerebral mass and to its envelopes. The veins which bring it 
 back, alternately compressed against the arch of the skull, em'pty 
 themselves more easily into the sinuses of the dura mater, towards 
 which their course is retrograde, and unfavourable to the circulation of 
 the blood which they pour into them. 
 
 When any thing impedes the free passage of the blood through the 
 lungs, it stagnates in the right cavities of the heart; the superior vena 
 cava, the internal jugulars, and consequently the sinuses of the dura 
 mater, and the veins of the brain which terminate in them, are 
 gradually distended ; and if this dilatation were carried to a certain 
 degree, the veins of the brain, placed between it and the arch of the 
 skull, would tend to depress it towards the base of that cavity. If this 
 dilatation, at first sight, were carried beyond the extensibility of these 
 vessels, their rupture would occasion fatal effusions. It is in this 
 manner that some authors have explained sanguineous apoplexy. 
 
 It will be objected, perhaps, that many of the sinuses of the dura 
 mater are at the base of the skull; and that consequently their 
 dilatation must tend to raise the cerebral mass. 
 
 But the greater part of these sinuses are connected only with the 
 cerebellum and the medulla oblongata, of which it has not yet been 
 possible to ascertain the motions. These sinuses are almost all lodged 
 in the edges of the falx and of the tentorium cerebelli. The cavernous 
 sinus in which the ophthalmic vein disgorges itself, the communicating 
 sinuses which allow the blood of one of these sinuses to pass into the 
 other, are too insignificant to produce a raising of the cerebral mass. 
 Lastly, the resistance of their parietes, formed chiefly by the dura 
 mater, must set strait bounds to their dilatation ; the spungy tissue 
 which fills the interior of the cavernous sinuses makes this dila- 
 tation and the reflux of the blood still more difficult. 
 
 CL. Experiments shewing the cause of the brains motion. It is 
 not enough to prove, by reasons drawn from the disposition of parts, 
 that the motions of the brain are communicated to it by the collection
 
 338 CAUSE OF THE BRAIN'S MOTION. 
 
 of arteries at its base; the fact must yet be established upon 
 observation, and placed beyond doubt by positive experiments. The 
 following are what I have attempted for this purpose : 
 
 A. I have first repeated the observation of some authors, and 
 ascertained, as they did, that the pulsations felt on placing the finger 
 on the fontanels of the skulls of new-born infants, correspond perfectly 
 to the beatings of the heart and arteries. 
 
 B. A patient trepanned for fracture, with effusion on the dura 
 mater, enabled me to see the brain alternately rising and falling. The 
 rising corresponded with the diastole, the falling with the systole of 
 the arteries. 
 
 C. Two dogs, trepanned, exhibited the same phenomenon, in the 
 same relation to the dilatation and contraction of the arteries. 
 
 D. I removed carefully the arch of the skull from the body of an 
 adult. The dura mater, disengaged from its adhesions to the bones 
 which it lines, was preserved perfectly untouched. I afterwards laid 
 bare the main carotids, and injected them with water. At every 
 stroke of the piston the brain shewed a very sensible motion of rising, 
 especially when the injection was forced at once along the two 
 carotids. 
 
 E. I injected the internal jugular veins, the cerebral mass remained 
 motionless ; the veins of the brain only, and the sinuses of the dura 
 mater, were dilated. The injection having been kept up for some time, 
 there resulted from it a slight swelling of the brain : when driven with 
 more force, some of the veins burst, and the liquor flowed out. The 
 same injection being made with water strongly reddened, the surface of 
 the brain became coloured with an intense red. To see clearly this 
 effect, you ought, after removing the arch of the skull, to divide on 
 each side the dura mater, on a level with the circular incision of the 
 skull, then turn back the flaps towards the upper longitudinal sinus. 
 
 F. The internal jugular veins having been laid open while the 
 injection was forced along the main carotids, each time the piston was 
 pushed forward the venous blood flowed with the greatest impetus ; 
 a clear proof of the manifest influence of the motions of the brain 
 on the course of the blood in its veins, and in the sinuses of the dura 
 mater. This experiment had been already performed by other anato- 
 mists, and amongst others by Ruysch, with a view of proving the imme- 
 diate communication between the arteries and veins. This communi- 
 cation, which is at present universally acknowledged, may be proved 
 by other facts. This one is evidently any thing but conclusive. 
 
 G. In a trepanned dog, I tied successively the two carotids. The 
 motions of the brain abated, but did not cease. The anastomoses of 
 the vertebrals with the branches of the carotids account for this pheno-
 
 CAUSE OF THE BRAIN'S MOTION. 339 
 
 H. I took a rabbit, a gentle creature, easy to confine, and very 
 well adapted for difficult experiments : after laying bare the brain, 
 and observing that its motions were simultaneous to the beats of the 
 heart, I tied the trunk of the ascending aorta : the moment the blood 
 ceased rising to the head, the brain ceased moving, and the animal 
 died. 
 
 I. The tying of the internal jugular veins did not stop the motions 
 of the brain ; but its veins dilated, and its surface, bared by the re- 
 moval of a flap of the dura mater, was sensibly redder than in the 
 natural state. The dog became affected with stupor, and expired in 
 convulsions. 
 
 The opening of these veins did not hinder the continuance of the 
 motions ; they grew fainter only when the animal was weakened by 
 loss of blood. 
 
 K. The opening of the superior longitudinal sinus, the only one 
 that could easily be opened, did not weaken the motions of the brain. 
 It is observed that the blood flows out more freely from it during the 
 elevation. 
 
 L. The compression of the thorax on human bodies produces but a 
 slight reflux in the jugular veins, especially if, during this compression, 
 the trunk is kept raised. . The reflux is greater when the trunk is laid 
 flat. 
 
 These experiments might be varied and multiplied : if, for instance, 
 the injection were thrown at once along the vertebral arteries and 
 the internal carotids; but those I have stated are sufficient for my 
 purpose. 
 
 Since the first publication of this inquiry, in the Memoirs of the 
 Medical Society,* I have had many opportunities of repeating the 
 observations and experiments, which serve as a foundation to the 
 theory there detailed. Among the facts which confirm this theory, 
 there is one that appears to me worth stating : it would be sufficient 
 by itself, if it were possible to establish a theory on the observation of 
 a single fact. A woman, about fifty years of age, had an extensive 
 carious affection of the skull ; the left parietal bone was destroyed in 
 the greatest part of its extent, and left uncovered a pretty considerable 
 portion of the dura mater. Nothing was easier than to ascertain the 
 existence of a complete correspondence between the motions of the' 
 brain and the beats of the pulse. I desired the patient to cough, and 
 to suspend her respiration suddenly ; the motions continued in the same 
 relation to each other : when she coughed, the head was shaken, and 
 the general concussion, in which the brain partook, might have been 
 
 * Me moires de la Societe Medicale de Paris, troisieme annee, torn. iii. p. 197, 
 el suiv.
 
 340 MOTION OF THE BRAIM- 
 
 mistaken by a prejudiced observer for the proper motions of that organ, 
 and depending on the reflux of blood in the veins. 
 
 In experiments on dogs, the same motion takes place when the 
 animal barks ; but it is easy to perceive, that the concussion affecting 
 the brain is experienced by the whole body, and that the effort of 
 expiration in barking causes a concussion more or less violent. 
 
 The patient mentioned in the preceding observation died about 
 a month after I came to the Hospital of St. Louis, in which she had 
 been for a considerable length of time. On opening the body, the left 
 lobe of the brain was found softened and in a kind of putrid state ; the 
 ichor, which was formed in considerable quantity, flowed outwardly, 
 by a fistulous opening in the dura mater, whose tissue was rather 
 thickened. 
 
 CLI. The slight consistence of the brain, which Lorry considers 
 as favourable to the communication of the motion which its arteries 
 impart to it, appears to me to be against this transmission. In fact, 
 the dilated vessels not being able to depress the base of the skull on 
 which they rest, make their effort against the cerebral mass, and raise 
 it the more easily (the arch of the skull being removed) from its pre- 
 senting a certain resistance. If the brain were too soft, the artery 
 would merely swell into it, and would not lift it. To satisfy oneself 
 of this truth, one need only observe what happens when the posterior 
 part of the knee rests on a pillow, or on any thing of the same sort ; 
 then, the motions which the popliteal artery impresses on the limb 
 are but little apparent, but they become very visible if the ham rests 
 on any thing that offers a certain resistance, as on the knee of the 
 opposite side, for instance ; then the artery, which cannot depress it, 
 exerts its whole action in raising the lower extremity, which it does 
 the more easily from acting against a bony, resisting, and hard part. 
 This experiment completely invalidates the opinion of Lorry. The 
 want of analogy will not be objected ; it will not be said that the 
 brain is heavier than the lower extremity, nor that the sum of the 
 calibres of the internal carotid and the vertebral arteries is not greater 
 than that of the popliteal artery. 
 
 This continual tendency of the brain to rise, produces in the end, 
 on the bones of the skull which resist this motion, very marked effects. 
 Thus, the interior surface of these bones, smooth in early life, becomes 
 furrowed with depressions, the deeper as we advance in age. The 
 digital depressions and the mammillary processes, corresponding to 
 the convolutions and windings of the brain, are very evidently the 
 result of its action on the enclosing parietes. Sometimes it happens, 
 that at a very advanced age the bones of the skull are so thinned by 
 this internal action, that the pulsations of the brain become perceptible 
 through the hairy scalp.
 
 
 MOTION OF THE BKAIK. 341 
 
 No doubt the same cause hastens the destruction of the skull by 
 the fungous tumours of the dura mater. The effort from expansion of 
 the tumour, which developes itself, is further added, and makes the 
 - waste of the bones more rapid. At the end of a few months the 
 tumour projects outwardly, with pulsations plainly simultaneous to the 
 beatings of the pulse, as Louis observes in a memoir inserted among 
 those of the Academy of Surgery. 
 
 I have shewn (CXLIX.) that the disposition of the veins of the 
 brain and of the sinuses of the dura mater was adverse to the action 
 ascribed to them on this viscus. Experiment (E, L) shews that the 
 stagnation of the blood, or even its regurgitation, could produce only 
 a slow and gradual distension of the sinuses of the dura mater and veins 
 terminating in it, with a slight turgescence of the cerebral mass, if the 
 cause producing the stagnation of the blood or its reflux, prolonged 
 its action to a partial destruction of the skull. 
 
 Lastly, the alternate motions of the brain, said to correspond to 
 those of respiration, ought to be to the beats of the pulse in the ordi- 
 nary ratio of 1 to 5. On the contrary, it is easy to satisfy oneself that 
 these motions are in an inverse ratio, and perfectly simultaneous to the 
 pulsations of the heart and arteries. 
 
 The results of the experiments I have stated in that memoir, com- 
 pared to those obtained by justly celebrated inquirers, are too remark- 
 ably different not to have induced me to make some attempt at 
 investigating the cause of our disagreement. For that purpose I 
 thought it necessary to examine scrupulously all the circumstances. 
 
 The work of Lamure contains anatomical errors, which throw sus- 
 picions upon his accuracy. Haller did not himself make the experi- 
 ments of which he speaks in treating of the influence of respiration on 
 the circulation of venous blood. This article is drawn from a thesis 
 defended at Gottingen by one of his disciples. Lastly, Vicq-d'Azyr 
 attempted no confirming experiment, and seems to have had in view 
 only the reconciling all opinions. 
 
 No one of these anatomists has distinguished the motions of ele- 
 vation impressed on the cerebral mass by the impulse of its arteries, 
 from the swelling of the sinuses of the dura mater, of the veins dis- 
 tributed to it, and from the tumefaction of the brain which may be 
 caused by difficult respiration. This mistake would be the more easy, 
 as animals tortured by the knife of the anatomist breathe painfully, 
 convulsively, and at shorter intervals than in their natural state. 
 Schlitting, the first author -of these experiments, appears especially 
 to have confounded the motion of rising, the real displacement of the 
 brain, with the turgescence of this viscus. At every expiration, he 
 says, I have seen the brain rise, that is to say, swell, and at every 
 inspiration I have seen it fall, that is to say, collapse.
 
 342 ACTION OF THE NERVES, &C. 
 
 " Toties animadverti perspicud, in omni expiratione cerebrum uni- 
 versurn ascendere, id est intumescere ; atque in quavis inspiratione illud 
 dcscendere, id est detumescere." 
 
 We may therefore consider as a truth, strictly demonstrated by 
 observation, experiment, and reasoning, the following proposition: 
 
 The motions observable in the brain, when laid bare, are imparted 
 to it solely by the pulsations of the* arteries at its base, and are per- 
 fectly simultaneous to the pulsations of these vessels : further, the 
 reflux and stagnation of the venous blood are able to swell its sub- 
 stance. 
 
 CLII. Action of the nerves and brain. It is undoubtedly, asVicq- 
 d'Azyr has said, by a motion of some sort that the nerves act. Setting 
 out from this simple idea, one may admit several kinds of nervous 
 motions, the one operating from the circumference to the centre (it 
 is the motion of sensation which we are about more particularly to 
 study in this paragraph) the other acting from the centre to the cir- 
 cumference; and this motion, produced by the will, determines the 
 action of the muscular organs, &c. 
 
 In what manner are the impressions produced on the senses by the 
 bodies which surround us, transmitted, along the nerves, to the brain ? 
 Is it through the intervention of a very subtle fluid ? or can the nerves, 
 as has been stated by some physiologists, be considered as vibrating 
 cords ? This last idea is so absurd, that one cannot help wondering 
 it should so long have. been in vogue. A cord, that it may vibrate, 
 must be in a state of tension along the whole of its length, and fixed 
 at both extremities. The nerves are not in a state of tension : their 
 extremities, in no degree fixed, approach towards each other or recede, 
 according to the difference of position, the tension, the turgescence, 
 the fulness or collapse of parts, and vary constantly in their distance 
 from each other. Besides, the nervous cords, situated between pulps 
 at their origin and at their termination, cannot be extended between 
 these two points. The nervous fibre is the softest, the least elastic of 
 all the animal fibres : when a nerve is divided, its two extremities, far 
 from receding by contracting, project, on the contrary, beyond each 
 other ; the point of section shews a number of small granulations of 
 medullary and nervous substance, which flows through its minute 
 membranous canals. Surrounded by parts to which they are, to a 
 certain degree, united, the nerves could not vibrate. Lastly, admitting 
 the possibility of their being capable of vibrating, the vibration of a 
 single filament ought to bring on that of all the rest, and carry con- 
 fusion and disorder in every motion and sensation. 
 
 It is much more probable that the nerves act by means of a subtle, 
 invisible, and impalpable fluid, to which the ancients gave the name of 
 animal spirits: this fluid, unknown in its nature, and to be judged of
 
 ACTION OF THE NERVES, &CC. 343 
 
 only by its effects, must be wonderfully subtle, since it eludes all 
 our means of investigation. Does it entirely proceed from the brain, 
 or is it equally secreted by the membranous envelopes of each nervous 
 filament? (Neurilemes, Reil.) To say the truth, one can bring no 
 other proof of the existence of a nervous fluid, but the facility with 
 which, by means of it, we are enabled to explain the various pheno- 
 mena of sensation. This proof, however, may not appear completely 
 satisfactory to those who are very strict, and who do not consider as 
 proved what is merely probable. 
 
 Among the constituent principles of the atmosphere there are gene^ 
 rally diffused several fluids, such as the magnetic and electric fluids. 
 Might not these fluids, on entering with the air into the lungs, com- 
 bine with the arterial blood, and be conveyed, by means of it, to the 
 brain or to the other organs ? Does not the vital action impart to 
 them new qualities, by making them undergo unknown combinations ? 
 Do caloric and oxygen enter into these combinations which endow 
 fluids with a certain vitality, and produce on them important changes, 
 and which arc not understood ?* Have not these conjectures acquired 
 a certain degree of probability, since the analogy of galvanism to elec- 
 tricity, at first supposed by the author of this discovery, has been 
 confirmed by the very curious experiments of Volta, repeated, com- 
 mented, and explained by all the natural philosophers of the present 
 day in Europe ?f ^ 
 
 The action of the nervous fluid takes place from the extremity of 
 nerves towards the brain, so as to produce the phenomena of sensation; 
 for when the nerves are tied, the parts below the ligature lose the 
 power of sensation; while, as will be seen in the proper place, this 
 action is propagated from the brain towards the nervous extremities, 
 and from the centre to the circumference, in producing motions of 
 every kind. This double current, in contrary directions, may take 
 place in the same nerves, and it is not necessary to arrange the nerves 
 into two classes of sensation and of motion. 
 
 All the impressions received by the organs of sense and by the 
 sentient extremities of nerves, are transmitted to the cerebral mass. 
 The brain is, therefore, the centre of animal life ; all sensations are 
 carried to it ; it is the spring of all voluntary motion : this centre is to 
 the functions of relation as the heart to the functions of nutrition. 
 
 * Were it not for these changes, electricity, magnetism, and galvanism, would 
 suffice to restore life to an animal recently dead. -^ ' u :j 
 
 f Galvanism, as yet, has not realised the expectations of physiologists. Che- 
 mistry has derived the greatest advantages from it. It is, at present, with MM. 
 Davy, Thenard, and Gay-Lussac, the most powerful agent in the analysis of certain 
 bodies. 
 
 3 &*:.%&" '
 
 344 FUNCTIONS OF THE BRAIN. 
 
 One may say of the brain as of the heart, omnibus dat et ab omnibus 
 accipit, it receives from all, and gives to all.* . 
 
 The medullary mass enclosed in the cranium appears to be formed 
 of two apparatuses of a different nature. In the parts lodged at the 
 base of the cranium, and which have received from anatomists the 
 name of medulla oblongata, especially resides the nervous energy 
 which presides over muscular motions. According to recent experi- 
 ments, the principle of inspiratory motion should have its seat in that 
 part of the medulla oblongata whence proceed the eighth pair of 
 nerves. The superior portions of the medullary mass seem to be 
 especially destined to the exercise of intelligence. No part of these 
 superposed, and, I may say, superadded organs, is more fully deve- 
 loped than in man. There is no animal who has so voluminous 
 hemispheres as he, covering not only as they do all the rest of the 
 encephalic mass, but also elevating and pushing before them the ante- 
 rior portion of the cranium which surmounts the face, or rather which 
 forms its frontal region. This anterior developement of the brain seems 
 so truly characteristic of the human species, that certain philosophers 
 have not hesitated to place in it the faculty by which man forms 
 abstract ideas of the Divinity. There, according to the theory of Gall, 
 is lodged the organ of theosophy. But in what manner, or by what 
 means does the will act, in producing the various movements ? What 
 ties connect the sensations with the powers of volition ? These ques- 
 tions are unanswerable in the present state of our knowledge ; and the 
 chief desiderata of this department of physiological science are yet to 
 be supplied, namely, to determine, in a precise manner, the functions 
 which belong to the different portions of the brain and of its central 
 apparatus ; likewise, whether the nervous energy proceeds from the 
 nerves themselves, is inherent in their structures, and is the result of 
 their action ; or are they only the simple conductors and distributors 
 of it from the sources at which they derive their origin ? 
 
 The existence of a centre, to which all the sensations are carried, 
 and from which all motions spring, is necessary to the unity of a 
 thinking being, and to the harmony of the intellectual functions. But 
 is this seat of the principle of motion and of sensation circumscribed 
 within the narrow limits of a mathematical point ? or rather should it 
 not be considered as diffused over nearly the whole brain ? The latter 
 appears to me the more probable opinion : were it ptherwise, what 
 could be the use of those divisions of the organ into several internal 
 cavities ? what could be the use of those prominences, all varying in 
 their form ; and of the arrangement of the two substances which enter 
 
 * See APPENDIX, Notes II. H.
 
 OF THE UNDERSTANDING. 345 
 
 into their structure? We may conjecture, with considerable proba- 
 bility, that each perception, each class of ideas, each faculty, is 
 assigned to some peculiar part of the brain. It is, indeed, impossible 
 to determine the peculiar functions of each part of the organ ; to say 
 what purpose is served by the ventricles, what is the use of the com- 
 missures, what takes place in the peduncles ; but it is impossible to 
 study an arrangement of such combination and to believe that it is 
 without design, and that this division of the cerebral mass into so 
 many parts, so distinct, and of such various forms, is not relative 
 to the different function which each has to fill in the process of 
 thought. That ingenious comparison, mentioned in the panegyric of 
 Mery, by Fontenelle, is very applicable to the brain. " We anato- 
 mists," he once said to me, " are like the porters in Paris, who are 
 acquainted with the narrowest and most distant streets, but who know 
 nothing of what takes place in the houses." What, then, are we to 
 think of the system of Gall, and of his division of the outside of the 
 skull into several compartments, which, according to the depression or 
 projection of the osseous case, indicate the absence or the presence of 
 certain faculties, moral or intellectual ? I cannot help thinking, that 
 this physiological doctrine of the functions of the brain, resting on too 
 few well-observed facts, is frivolous ; while his anatomical discoveries 
 on the anatomy of this organ, and on the nervous system, are of the 
 highest importance and well founded. 
 
 CLIII. Analysis of the understanding . In vain were the organs 
 of sense laid open to all impressions of siirrounding objects ; in vain 
 were their nerves fitted for their transmission : these impressions were 
 to us as if they had never been, were there not provided a seat of 
 consciousness in the brain ; for it is there that every sensation is felt. 
 Light, and sound, and odour, and taste, are not felt in the organs they 
 impress ; it is the sensitive centre that sees, and hears, and smells, and 
 tastes. You have only to interrupt, by compression of the nerves, the 
 communication between the organs and the brain, and all conscious- 
 ness of the impressions of objects, all sensation is suspended. 
 
 The torturing pains of a whitlow cease if you bind the arm so 
 strongly as to compress the nerve which carries the sensation to the 
 brain. A living animal under experiments suffers nothing from the 
 most cruel laceration, if you have first cut the nerves of the parts on 
 which you are operating. To conclude, the organs of sense, and the 
 nerves which communicate between them and the brain, shall have 
 suffered no injury, shall be in a perfect state for receiving and trans- 
 mitting the sensitive impression, yet no phenomena of sensation can 
 take place if the brain be diseased when it is compressed, for in- 
 stance, by a collection of fluid, or by a splinter from the skull in a 
 wound of the head. This organ is, therefore, the immediate instru-
 
 346 SOURCES OF IDEAS. 
 
 ment of sensations, of which impressions made on the others are only 
 the occasional causes. This modification of sensibility, which serves 
 to establish the relations of the living being with objects without, 
 would be correctly denominated cerebral sensibility; but that even 
 in animals without brain, or distinct nervous system, it is very mani- 
 fest. The sensibility in virtue of which the polypus dilates his cavity 
 for the admission of his prey, and Contracts itself to retain it, is in fact 
 quite distinct from that sensibility of nutrition by which its substance 
 is enabled to take to itself nutritious juices. 
 
 The brain, as Cabanis has well expressed it, acts upon the impres- 
 sion transmitted by the nerves, as the stomach upon the aliments it 
 receives by the oesophagus : it does, in its own way, digest them ; set 
 in motion by the impulse it receives, it begins to re-act ; and that re- 
 action is the perceptive sensation, or perception. From that moment 
 the impression becomes an idea, it enters as an element into thought, 
 and becomes subject to the various combinations that are necessary to 
 the phenomena of understanding.* 
 
 CLIV. Sources of our ideas. Our sensations are nothing but 
 modifications of our being ; they are not qualities 01 the objects : no 
 body has colour to the blind from birth : the rose has lost its most 
 precious quality to him who has lost his smell ; he knows it from the 
 anemone only by its colour, its figure, &c. We perceive nothing but 
 within ourselves. It is only by habit, only by applying different senses 
 to the examination of the same object, that we are at last able to sepa- 
 rate it from our own existence ; to conceive of it as distinct from our- 
 selves, and from the other bodies with which we are acquainted ; in a 
 word, to refer to outward objects the sensations that take place within 
 ourselves. Our ideas come to us only by the senses ; there are none 
 innate, as was imagined till the time of Locke, who has allotted to the 
 refutation of this error a large part of his valuable work on the Human 
 Understanding.! The child that opens its eyes to the light is pre- 
 pared for the acquisition of ideas by this merely, that it is provided 
 with an organic apparatus susceptible of impressions from the objects 
 that surround it. 
 
 The brain pre-exists the ideas, as the eye the sensations of sight. 
 Every where the existence of the organ precedes the exercise of its 
 functions. It is thus as impossible to conceive thought without a brain 
 as vision without the organ destined to receive the impression of light. 
 
 * I ought to observe, that the terms thought and understanding are, in my 
 opinion, synonymous ; both are alike an abridged expression of the whole of the 
 operations of the sensitive centre. 
 
 f See the APPENDIX, Notes H H, for some remarks upon Locke's account of 
 the 6rigin of our ideas, and upon the manner in which he has been misunderstood, 
 or his opinions misconstrued, and CTCH perverted, by several modern writers J. C.
 
 SOURCES OF IDEAS. 347 
 
 It is inaccurate, however, to compare,' as some philosophers have 
 done, the brain of a child new-born to a blank tablet, on which are 
 to be figured all the future acts of his intelligence. If sensation came 
 only from without, if the external senses were the only organs that 
 could send impressions to the cerebral centre the understanding, at the 
 moment of birth, had indeed been nothing, and the comparison of its 
 organ to a sheet of white paper, or to a slab of Parian marble, on 
 which not a character was drawn, had been perfectly correct. But 
 we are compelled to acknowledge, with Cabanis, two sources of ideas 
 quite distinct from each other, the external senses and the internal 
 organs. These inward sensations, springing from functions that are 
 carrying on within us, are the cause of those instinctive determinations 
 by which the new-born child seizes the nipple of its mother, and 
 sucks the milk by a very complicated process ; which directs the young 
 of animals the moment after birth, and sometimes in the very act 
 of birth, while the limbs are yet engaged in the vagina, to seize upon 
 the dug of their dam. Instinct, as the author just quoted has very 
 correctly observed, springs from impressions received by the interior 
 organs, whilst reasoning is the produce of external sensations ; and 
 the etymology of the word instinct, composed of two Greek words, 
 signifying " to prick," and " within," agrees with the meaning we as- 
 sign to it. 
 
 These two parts of the understanding, reason and instinct, unite 
 and blend together to produce the intellectual system, and the various 
 determinations of mental action. But the part that each bears in the 
 generation of ideas is very different in animals, whose grosser external 
 senses allow instinct to predominate, and in man, in whom the per- 
 fection of these senses and the art of signs, which perpetuate the 
 transient thought, augment the power of reason while they enfeeble 
 instinct. It is easy to conceive that the brain, assailed by a crowd 
 of impressions from without, will regard less attentively, and therefore 
 suffer to escape, the greater part of those that result from internal 
 excitation. Instinct is more vigorous in savage man, and its relative 
 perfection is his compensation for the advantages which superior reason 
 brings to man in civilisation. The moral and intellectual system of the 
 individual, considered at different periods of life, owes more to internal 
 sensation the less it is advanced ; for instinct declines as reason is 
 strengthened and enlarged. 
 
 Thus, though all the phenomena of understanding have their source 
 in physical sensibility, this sensibility being set in action by two sorts 
 of impressions, the brain of an infant just born has already the con- 
 sciousness of those which spring from the internal motion, and it is 
 from these impressions that it executes certain spontaneous movements, 
 of which Locke and his followers could find no explanation : accord-
 
 348 OF PERCEPTION, &C- 
 
 ingly, the partisans of innate ideas looked upon them as the strongest 
 confirmation of their system. But these ideas, anterior to all action of 
 outward objects on the senses, are simple, few, and extending to a very 
 small number of wants : the child is but a few hours old, and already 
 it expresses a multitude of sensations that throng upon it from the 
 instant of its birth sensations which have passed to the brain, com- 
 bined themselves there, and entered into the action of the will with a 
 velocity which equals, if it does not surpass, that of light. 
 
 It is only after laying down between the sources of our knowledge 
 a very exact line of demarcation, after scrupulously distinguishing 
 the rational from the instinctive determinations, acknowledging that 
 age, sex, temperament, health, disease, climate, and habit, which 
 modify our physical organisation, must, by a secondary effect, modify 
 these last, that we can possibly understand the diversity of humours, 
 of opinions, of characters, and of genius. He who has well appre- 
 ciated the effect on the judgment and reason of the sensations that 
 spring from the habitual state of the internal organs, sees easily the 
 origin of those everlasting disputes on the distinction between the sen- 
 sitive and the rational soul ; why some philosophers have believed man 
 solicited for ever by a good or an evil genius spirits which they 
 have personified under the names of Oromazes and Arimanes, betwixt 
 whom they imagined eternal war ; the contest of the soul with the 
 senses, of the spirit with the flesh, of the concupiscent and irascible 
 with the intellectual principle, that contradiction which St. Paul la- 
 boured under, when he said, in his epistle to the Romans, that his 
 members were in open war with his reason. These phenomena which 
 suggest the conception of a two-fold being (homo duplex, Buffon) are 
 nothing but a necessary strife betwixt the determinations of instinct 
 and the determinations of reason between the ofteh times imperious 
 wants of the organic nature, and the judgment which keeps them 
 under, or deliberates on the means of satisfying them without offending 
 received ideas of fitness, of duty, of religion, &c.* 
 
 CLV. Of perception, attention, memory, imagination, reasoning, 
 fyc. A being absolutely destitute of sensitive organs would possess 
 only the existence of vegetation : if one sense were added, he would 
 not yet possess understanding, because, as Condillac has shewn, the 
 impressions produced on this only sense would not admit of com- 
 parison ; it would end in an inward feeling, a perception of existence, 
 and he would believe the things which affected him to be a part of his 
 being. The fundamental truth, so completely made out by modern 
 metaphysicians, is found distinctly stated in the writings of Aristotle ;f 
 
 * For some remarks on Instinct, see APPENDIX, Notes H H. 
 f Nil cst in intellectu quod non priits fucrit in sensu : Nisi intellcclus ipsc^ 
 as Leibnitz has very justly added. See APPENDIX, Notes H H.
 
 OF PERCEPTION, &C. 349 
 
 and there is room for surprise that that father of philosophy should 
 have merely recognised it, without conforming to its doctrines ; but 
 still more that it should have been for so many ages disregarded by 
 his successors. So absolutely is sensation the source of all our know- 
 ledge, that even the measure of understanding is according to the 
 number and perfection of the organs of sense ; and that by successively 
 depriving the intelligent being of them, we should lower at each step 
 his intellectual nature ; whilst the addition of a new sense to those 
 we now possess, might lead us to a multitude of unknown sensations 
 and ideas, would disclose to us in the beings we are concerned with a 
 vast variety of new relations, and would greatly enlarge the sphere of 
 our intelligence. 
 
 The impression produced on any organ by the action of an out- 
 ward body does not constitute sensation ; it is further requisite that 
 the impression be transmitted to the brain, that it be there perceived, 
 that is, felt by that organ ; the sensation then becomes perception, and 
 this first modification supposes, as is apparent, a central organ, to 
 which the impressions on the organs of sense may be carried. The 
 cerebral fibres are more or less disturbed by the sensations sent to them 
 at once from all the organs of sense; and we should acquire but 
 confused notions of the bodies from which they proceed, if one stronger 
 perception did not silence as it were the rest, and fix the attention. 
 In this concentration of the soul upon a single object, the brain is 
 feebly stirred by many sensations that leave no trace; it is thus 
 that after the attentive perusal of a book, we have lost the sen- 
 sations that were produced by the different colour of the paper and 
 the letters. 
 
 When a sensation is of short duration, our knowledge of it is so 
 slight that soon there remains no remembrance of it. It is thus that 
 we do not perceive every time we wink that we pass from light to 
 darkness, and from darkness to light. If we fix our attention on this 
 sensation, it affects us more permanently. After occupying oneself 
 for a given time with a number of things, with but moderate attention 
 to each after reading, for instance, a novel, full of events, each of 
 which in its turn has interested us, we finish it without being tired of 
 it, and are surprised at the time it has taken up. It is because 
 successive and light impressions have effaced one another, till we have 
 forgotten all but some of the principal actions. Time ought then to 
 appear to us to have passed rapidly ; for, as Locke has well said, in his 
 Essay on the Human Understanding, " We conceive the succession of 
 times only by that of our thoughts." 
 
 This faculty of occupying oneself long and exclusively with the 
 same idea, of concentrating all the intellectual faculties on one object, 
 of bestowing on the contemplation of it alone a lively and well-sup-
 
 350 OF ATTENTION AND MEMORY, &C. 
 
 ported attention, is found in greater or less strength in different minds ; 
 and some philosophers appear to me to have explained, very plausibly, 
 the different capacity of different minds and the various degrees of 
 instruction of which we are capable, by the degree of attention we are 
 able to give to the objects of our studies. 
 
 Who, more than the man of genius, pauses on the examination of 
 a single idea, considers it with more profound reflection, under 
 more aspects and relations, bestows on it, in short, more entire 
 attention. 
 
 Attention is to be considered as an act of the will, which keeps 
 the organ to one sensation, or prepares it for that sensation so as to 
 receive it more deeply. To look is to see with attention ; to listen 
 is to hear attentively ; the smell, the taste, in the same way, are fixed 
 upon an odour or a flavour, so as to receive from them the fullest 
 impression. In all these cases the sensation may be involuntary, 
 but the attention by which it is heightened is an act of the will. 
 This distinction has already been well laid down with regard to the 
 feeling, which is only the touch exerted under the direction of the 
 will. 
 
 According to the strength or faintness of the impression that a 
 sensation or an idea (which is but a sensation operated upon by the 
 cerebral organ) has produced on the Jibrej. of that organ, will be the 
 liveliness and permanence of the recollection. Thus, we may have 
 reminiscence of it or recall faintly that we have been so affected ; or 
 memory, which is a representation of the object with some of its 
 characteristic attributes, as colour, bulk, &c. 
 
 The pains that appear to be felt in limbs which we have lost have 
 not their place in the part that is left ; the brain is not deceived when 
 it refers to the foot the sufferings of which the cause is in the stump, 
 after the amputation of the leg or thigh. I have at this moment before 
 me the case of a woman and of a young man, whose leg and thigh I 
 took off for scrofulous caries, of many years standing, and incurable 
 by any other means. The wound from the operation is completely 
 cicatrised. The stump has not more sensibility than any other part 
 covered by integuments, since it may be handled without pain ; and 
 yet, both at intervals, and especially when the atmosphere is highly 
 electrified, complain of pains in the limbs which they have lost some 
 months ago : they recognise them, by certain characters, for those of 
 their disease. They, like all perceptions, are manifestly given in 
 charge to the memory, which reproduces them when the cerebral 
 organ repeats the action once occasioned by the impressions of the 
 
 Finally, if the brain is easy of excitation, and at the same time 
 faithful in preserving the impressions it has received, it will possess the
 
 OF LANGUAGE. -861 
 
 power of bringing up ideas with all their connected and collateral 
 notions of reproducing them, in some sort, by recalling the entire object, 
 whilst memory presents us with a few of its qualities only. This crea- 
 tive faculty is called imagination. If it sometimes produces monsters, 
 it is that tfie brain, by its power of associating, connecting, combining 
 ideas, reproduces them in an order not according to nature, gathers 
 them under capricious associations, and gives occasion to many erro- 
 neous judgments. 
 
 When the mind brings together two ideas, when it compares them 
 and determines on their analogy, it judges. A certain number of 
 judgments, in series, forms a reasoning. To reason, then, is only to 
 judge of the relations that exist among the ideas with which the senses 
 supply us, or which are produced by imagination. 
 
 It is with the faculties of the soul as with those of the body ; 
 when called into full exertion, the intellectual organ gains vigour; 
 it languishes in too long repose. If we exercise certain faculties 
 only, they are greatly developed, to the prejudice of the rest. It is. 
 thus that by the study of mathematics soundness of judgment and 
 precision of reasoning are acquired, to the extinction of imagination, 
 which never rises to great strength without injury to the judging and 
 reasoning powers. The descriptive sciences employ especially the me- 
 mory, and it is seldom that they much enlarge the minds of those who 
 study them exclusively. 
 
 CLV1. Of spoken signs or language. Condillac has immortalised 
 his name by being the first to discover, and by demonstrating irre- 
 fragably, that signs are as necessary to the formation as to the ex- 
 pression of ideas ; that language is not less useful for thinking than 
 for speaking ; that if we could not attach the notions once acquired 
 to received signs, they would remain always unconnected and in- 
 complete, since we should have no power to associate and compare 
 them, and to determine their relations. It is the imperfection or the 
 total want of signs for fixing their ideas, that makes the infancy of 
 the lower animals perpetual. It is this that makes it impossible for 
 them to transmit to another generation, or even to communicate one 
 with another, the acquisitions of individual experience, which ex- 
 perience is indeed, by the same cause, restrained within very narrow 
 limits, and confined to a few simple notions a few ideas, resting 
 merely on its wants and on its powers. If there were not signs to 
 preserve ideas and to connect them, memory would be nothing: all im- 
 pressions would be effaced soon after they were felt, all collections of 
 ideas would be dissolved as soon as formed (if they could be formed 
 at all) ; our ignorance would be indefinitely prolonged, and we should 
 reach aid age with a mind still in its infancy. 
 
 When we reflect on a subject, it is not directly on the ideas, but on
 
 352 OF LANGUAGE. 
 
 the words expressing them, that the mind operates ; we should never 
 have the idea of numbers if we had not assigned distinct names to 
 numbers, whether single or collected. Locke speaks of some Ameri- 
 cans who had no idea of the number thousand, because the words 
 of their language expressed nothing beyond the number twenty. 
 La Condamine informs us, in his narrative, that there are some who 
 count only to three, and the word they employ to express the number 
 is so complicated, of a pronunciation so long and difficult, that, as 
 Condillac observed, it is not surprising that, having begun with a 
 method so inconvenient, they have not been able to advance any far- 
 ther. " Deny," says this writer, " to a superior mind the use of 
 letters, how much of knowledge you put out of his reach, which an 
 ordinary capacity will attain to without difficulty. Go on, and take 
 from him the use of speech, the lot of the dumb will shew you how 
 narrow are the limits within which you confine him. Finally, take 
 from him the use of all sorts of signs, let him be unable to find 
 the least sign for the most ordinary thought, and you have an idiot."* 
 
 We are made acquainted by travellers with certain tribes, so back- 
 ward in the art of expressing their ideas by signs, that they seem to 
 serve as a link between civilised nations and certain species of animals 
 whose instinct has been perfected by education. One might even 
 assert, that there is less distance, in respect to intelligence, from man 
 in that extreme abasement to the higher animals, than there is to a man 
 of superior genius, such as Bacon, Newton, or Voltaire. 
 
 In another part of the same work, after having demonstrated that 
 languages are real analytic methods that the sciences may be reduced 
 to well-constructed languages, he shews how powerful is their influence 
 in the cultivation of the mind. But he shall speak himself with 
 that clearness of expression which is the characteristic and the charm 
 of his writings. " Languages are like the ciphers of the geometri- 
 cians; they present new views to the mind, and expand it as they are 
 brought nearer to perfection. The discoveries of Newton had been 
 prepared for him by the signs that had been already contrived and the 
 methods of calculations that had been invented. If he had arisen 
 sooner he might have been a great man to his own age, but he would 
 not have been the admiration of ours. It is the same in other de- 
 partments." 
 
 The most scanty languages have been formed in the most barren 
 countries. The savage who strays along the desert shores of New 
 Zealand needs but few signs to distinguish the small number of objects 
 that habitually impress his senses; the sky, the earth, the sea, fire, 
 shells, the fish that form his chief food, the quadrupeds, and the vege- 
 
 * Essai sur TOrigiue des Connoissances Humaines, sec. 4.
 
 OF LANGUAGE. 353 
 
 tables, which are but few in number under this severe climate, are all 
 that he has to name and to know : accordingly, his vocabulary is very 
 small ; it has been given to us by travellers in the compass of a few 
 pages. A copious language, one capable of expressing a great variety 
 of objects, of sensations, and of ideas, supposes high civilisation in the 
 people among whom it is spoken. You hear complaints of the per- 
 petual recurrence of the same expressions, the same thoughts, the 
 same images in the, poetry of Ossian ; but living amidst the barren 
 rocks of Scotland, the bards could not speak of things of which 
 nothing on the soil they inhabited could supply them with the idea. 
 The monotony of their language was involved in that of their im- 
 pressions, always produced by rocks, mists, winds, the billows of the 
 ireful ocean, the gloomy heath, and the silent pine, &c. The repetition 
 of the same expressions in the Scriptures, shews that civilisation had 
 not made the same progress among the Hebrews as among the Greeks 
 and Romans, t The connexion there is between the genius of a lan- 
 guage and the character of the people that speak it ; the influence of 
 climate, of government, and of manners, on language ; the reason why 
 the great writers in every department appear together at the very time 
 in which a language reaches its perfection and maturity, &c. ; these are 
 problems that suggest themselves, and would well merit our endeavours 
 to obtain solution, did not the investigation manifestly lead beyond the 
 limits of our inquiry. 
 
 Though Condillac has said repeatedly in his works, that all the 
 operations of the soul are merely sensation variously transformed, and 
 that all its faculties are included in the single one of sense, his analysis 
 of thought leaves still much doubt and uncertainty on the real cha- 
 racter and relative importance of each of her faculties. 
 
 The merit of dispersing the mist which covered this part of meta- 
 physics remained for M. de Tracy. His Elements of Ideology,* leave 
 nothing to be wished for on this subject. I shall extract some of its 
 main results, referring the reader for the rest to the work. 
 
 To think is only to feel ; and to feel is, for us, the same as to exist ; 
 for it is by sensation we know of our existence. Ideas or perceptions 
 are either sensations, properly so called, or recollections, or relations 
 which we perceive ; or, lastly, the desire that is occasioned in us by 
 these relations. The faculty of thought, therefore, falls into the natu- 
 ral subdivision of sensibility, properly termed memory, judgment, and 
 will. To feel, properly speaking, is to be conscious of an impression ; 
 to remember, is to be sensible of the remembrance of a past impression ; 
 to judge, is to feel relations among our perceptions ; lastly, to will, is 
 to desire something. Of these four elements, sensations, recollections, 
 
 * Elimens d" Ideologic, par M. le Comte Desfutt Tracy, Membre de rinstitut. 
 A. A
 
 354 DISORDERS OF THOUGHT. 
 
 judgments, and desires, are formed all compound ideas. Attention is 
 but an act of the will ; comparison cannot be separated from judg- 
 ment, since we cannot compare two objects without judging them ; rea- 
 soning is only a repetition of the act of judging ; to reflect, to imagine, 
 is to compose ideas, analysable into sensations, recollections, judg- 
 ments, and desires. This sort of imagination, which is only certain and 
 faithful memory, ought not to be distinguished from it. 
 
 Finally, want, uneasiness, inquietude, desire, passions, &c. are 
 either sensations or desires. There is room, therefore, to reproach 
 Condillac with having divided the human mind into understanding 
 and will only ; because the first term includes actions too unlike, 
 such as sensation, memory, judgment; and with having run into 
 the opposite extreme, in the too great multiplication of secondary 
 divisions. 
 
 CLVII. Disorders of thought. Philosophers would, undoubtedly r 
 attain to a much profounder knowledge of the intellectual faculties of 
 man, if they joined, to the study of their regular and tranquil action, 
 that of the many disordered actions to which they are liable. It is not 
 enough, if we would understand them aright, to watch their operation 
 when the soul is undisturbed and at ease ; we must follow it in its 
 perturbations and wanderings ; we must see its powers now separating 
 themselves from those with which they ought to act ; now combining 
 with them under false perceptions ; sometimes altogether drooping, 
 and sometimes starting into an extreme violence of action, of which 
 we can neither mistake the importance nor the nature ; and, as the 
 greater part of our ideas are derived from the analogies we are able to 
 discern among the objects that supply them amidst these troubles of 
 human passion and human reason, we learn to conceive more pro- 
 foundly of their nature than if we had been satisfied with observing 
 them in the calm of their natural condition. 
 
 The observation of mania is yet too imperfect in the number, variety, 
 and precision of its facts, to fix the classification of the species of men- 
 tal alienation according to the intellectual faculty that is disordered in 
 each. Professor Pinel has, nevertheless, ventured to ground his dis- 
 tinctions of the species of mania on the labours of modern psycholo- 
 gists, and has shewn that all might be referred to five kinds, which he 
 marks by the names of melancholy, of mania without delirium, mania 
 with delirium, dementia, and idiocy.* In the first four kinds there is 
 perversion of the mental faculties, which are in languid or excessive 
 action. We are not to look for the cause of these derangements in 
 vice of original conformation ; for melancholy, mania with or without 
 
 * For more ample explanation I must refer to the work, Traiti Mtdico-philoso- 
 phique sur f 'Alienation Mentals, ou la Afanie, par P. Pinel. Paris, 1800.
 
 DISORDERS OF THOUGHT. 355 
 
 delirium, and madness, scarcely ever appear before puberty. It is 
 agreed among observers, that almost all maniacs have become so 
 between twenty and forty years old ; that very few have lost their rea- 
 son either before or after this stormy period of life, wherein men, 
 yielding by turns to the torments of love and of ambition, of fear and 
 of hope ; to the sweet illusions of happiness, and the realities of suf- 
 fering ; consumed with passions for ever reviving, often repressed, and 
 rarely satisfied feel their intellectual powers impaired, annihilated, or 
 abused, by that tempest of the moral nature, which has well been com- 
 pared to the storms that, in their violence, lay desolate the flourishing 
 earth, 
 
 We are compelled to grant, that our acquaintance with the struc- 
 ture of the brain and of the nerves is too imperfect, that dissections of 
 the bodies of maniacs have been too few, and those often by physicians* 
 too little familiar with the minute structure of the sensitive organ, to 
 warrant us in asserting or denying that derangement of intellect de- 
 pends constantly on organic injury ; and though it is highly probable, 
 at least, many facts collected by observers, who, like Morgagni, deserve 
 the utmost confidence, authorise the belief, that the consistence of 
 the brain is increased in some maniacs, who are distinguished by the 
 most obstinate and unvarying adherence to their ruling ideas ; that it 
 is, on the other hand, soft, watery, and in a kind of incipient dissolu- 
 tion in some others, whose incoherent ideas, after their aptitude for 
 association and for transformation into judgments is gone, succeed one 
 another rapidly, and seem to pass away without a trace ; and that cer- 
 tain organic lesions, such as softening of the brain, the developement 
 of tumours, tubercles, encysted growths, &c. occasion necessary alter- 
 ation of the intellectual functions. 
 
 If, in the multitude of maniacs, the organ of the understanding 
 suffers only imperceptible injury, it is very remarkably changed in idiots. 
 The almost entire obliteration of the intellectual faculties, which con- 
 stitutes idiocy, when it is not brought on by some strong and sudden 
 shock, some unexpected and overwhelming emotion, breaking down at 
 once all the springs of thought when it is an original defect is 
 always connected with mal-conformation of the skull, with the con- 
 straint of the organs it encloses. These defects of organisation lie, as 
 M. Pinel observes, in the excessive smallness of the head to the whole 
 stature, or to the want of proportion among the different parts of the 
 skull. Thus, in the idiot whose head is given in his work on mania 
 (pi. ii. fig. 6), it is only the tenth of the whole height, whilst it should 
 be something more than a seventh, if we take the Apollo of Belve- 
 dere as the type of the ideal perfection of the human figure. An idiot, 
 
 * This censure is especially applicable to the researches of Dr. Greding.
 
 356 ; DISORDERS OF THOUGHT. 
 
 whom I occasionally see, has the occipital extremity of the head so 
 much contracted, that the large extremity of the oval formed by the 
 upper face, instead of being placed at the back, as in other men, is, on 
 the contrary, turned forwards, and answers to the forehead, which 
 itself slopes towards the sinciput. The vertical diameter of the skull is 
 inconsiderable. The head, thus shortened from above downwards, is 
 much flattened on the sides. The hands and feet are very small, and 
 often cold ; the genitals, on the contrary, are extremely large. 
 
 In two other children, equally idiots, and now in the hospital of 
 St. Louis, the skull, very large behind, ends in a contracted extremity, 
 and the forehead is very short, and not more than two inches and 
 a half wide, measuring from the semicircular process, which terminates 
 the temporal fossa at the upper part, to the commencement of the 
 same process on the other side. The excessive growth of the genitals 
 is not less conspicuous : they are in these two children, one ten, the 
 other twelve years old, as well as in the first of whom I spoke, who is 
 fourteen, of larger size than is commonly seen after the appearance of 
 puberty. There is nothing to indicate that this season is attained by 
 thege three idiots. 
 
 The same excess of growth is found more conspicuously among the 
 cretins of the Valais, idiots who (in consequence of a weak and degraded 
 organisation) are prone to lasciviousness and the most frequent 
 onanism. 
 
 This sort of opposition in the relative energy of the intellectual 
 organ and of the system of reproduction, in the developement of the 
 brain and that of the parts of generation, is a phenomenon which must 
 strongly interest the curiosity and engage the attention of physiologists. 
 Who is there unacquainted with that enervation of the understanding, 
 that intellectual and physical debility which indulgence in the plea- 
 sures of love brings on, if we exceed ever so little the bounds of scrupu- 
 lous moderation?-! Castration modifies the moral character of men and 
 animals, at least as powerfully as their physical organisation, as 
 M. Cabanis has shewn, in treating of the influence of the sexes on the 
 origin and growth of the moral and intellectual powers.* 
 
 CLVIII. Our physical, therefore, holds our moral nature under a 
 strict and necessary dependence ; our vices and our virtues sometimes 
 produced, and often modiHed, by social education, are frequently, too, 
 results of organisation. To the conclusive proofs which the philoso- 
 pher I have just named, who is an honour to his profession, brings for- 
 ward of the influence of the physical on the moral human being, I will 
 only add a single observation. It is not certainly the first that has 
 been made of the kind ; but none such, I believe, has yet been pub- 
 
 * Des Rapports du Physique et du Moral de 1'IIomme. 2 vols. 8vo.
 
 
 OF THE PASSIONS. 357 
 
 lished. The reader recollects, I have no doubt, the old woman of 
 whom I have spoken in treating of the motions of the brain, which an 
 enormous caries of the bones of the skull gave an opportunity of 
 observing in her. I wiped off the sanious matter which covered the 
 dura mater, and I at the same time questioned the patient on her 
 situation. As she felt no pain from the compression of the cerebral 
 mass, I pressed down lightly the pledget of lint, and on a sudden the 
 patient, who was answering my questions rationally, stopped in the 
 midst of a sentence ; but she went on breathing, and her pulse con- 
 tinued to beat : I withdrew the pledget ; she said nothing : I asked 
 her if she remembered my last question ; she said no. Seeing that 
 the experiment was without pain or danger, I repeated it three times, 
 and thrice I suspended all feeling and all intellect. 
 
 A man trepanned for a fracture of the skull, with effusion of blood 
 and pus on the dura mater, perceived his intellectual faculties going, the 
 consciousness of existence growing benumbed and threatening to cease 
 in the interval of each dressing, in proportion as the fluid collected. 
 
 There are surgical observations on wounds of the head containing 
 several facts that may be connected with the preceding observations. 
 There is no one who has had syncope of more or less continuance, but 
 knows that the state is without pain or uneasiness, and leaves no 
 consciousness of what passed whilst it lasted. It is the same after an 
 apoplexy, a fit of epilepsy, &c. 
 
 The history of temperament supplies us with too many examples of 
 the strict connexion which there is between the physical organisation 
 and the intellectual and moral faculties, to leave any necessity for 
 dwelling longer on this truth, which no one questions, but which no 
 philosopher has yet followed into all its consequences. 
 
 CLIX. Of the passions. An English writer, in a work on the his- 
 tory of mental alienation,* has traced, better than had before been 
 done, the physiological history of the passions, which he looks upon as 
 mere results of organisation, ranking them among the phenomena of 
 the animal economy, and with abstraction of any moral notion that 
 might attach to them. 
 
 All passion is directed to the preservation of the individual or the 
 reproduction of the species. They may be distinguished, therefore, like 
 the functions, into two classes.f In the second, we should find paren- 
 tal love, and all the affections that protect our kind through the help- 
 lessness of its long infancy. 
 
 But Crichton, with the greater part of metaphysicians and physio- 
 
 * An Inquiry into the Nature and Origin of Mental Derangement. London, 
 1798, 2 vols. 8vo. 
 
 f See APPENDIX, Notes H H.
 
 358 
 
 OF THE PASSIONS. 
 
 legists, appears to me not to have settled correctly the meaning that 
 should belong to the word passion. When he gives this name to hun- 
 ger, an inward painful sensation, the source of many determinations of 
 many kinds a powerful mover of savage and civilised man; to the 
 anxiety which attends the breathing an air deficient in oxygen ; to the 
 impressions of excessive heat and cold ; to the troublesome sensations 
 produced by the accumulation of urine and fsecal matter; to the feeling' 
 of weariness and fatigue that is left by violent exertions ; he confounds 
 sensation with the passions or desires which may spring from it. 
 
 It is to avoid extreme wants, of which a vigilant foresight perceives 
 afar off the possibility ; it is to satisfy all the factitious wants which 
 society and civilisation have created, that men condemn themselves 
 to those agitations, of which honour, reputation, wealth, and power, 
 are the uncertain aim. Our passions have not yet been analysed 
 with the same care as our ideas: no one has yet duly stated the 
 differences there are, in respect to their number and energy, betwixt 
 savage man and man in the midst of civilised and enlightened 
 society. 
 
 As the habitual state of the stomach, of the lungs, of the liver, and 
 internal organs, is connected with certain sets of ideas as every vivid 
 sensation of joy or distress, of pleasure or pain, brings on a feeling of 
 anxiety in the prsecordia, the ancients placed in the viscera the seat of 
 the passions of the soul : they placed courage in the heart, anger in the 
 liver, joy in the spleen, &c. Bacon and Van Helmont seated them in 
 the stomach ; Lecat in the nervous plexuses ; other physiologists in 
 the ganglions of the great sympathetic, &c. But have they not con- 
 founded the effect with the cause? the appetite with the passion to 
 which it disposes ? The appetites, out of which the passions spring, 
 reside in the organs ; they suppose only instinctive determinations, 
 whilst passion carries with it the idea of intellectual exertion. Thus, 
 the accumulation of semen in the vesiculse, which serve for its reser- 
 voirs, excites the venereal appetite, quite distinct from the passion of 
 love, though often its determining cause. Animals have scarcely more 
 than appetite, which differs as much from passion as instinct from intel- 
 ligence. However, the brain is not to be considered as the primitive 
 seat of the passions,* as is done by the greater number of philoso- 
 phers. Of all the feelings of man, the most lasting, the most sacred, 
 the most passionate, and the least susceptible of injury from all the pre- 
 judices of the social state, maternal love, is surely not the result of any 
 
 * If we analysed the passions carefully, it would be right to distinguish those 
 which are common to all men which appertain to our physical wants and to our 
 
 nature from certain caprices of the mind which have been honoured with the name 
 
 of passions, as avarice, ambition, &c. which should be referred to kinds of mental 
 derangement, and classed as species of monomania.
 
 OF THE PASSIONS. 359 
 
 intellectual combination, of any cerebral action : its source is in the 
 bowels (entrailles) ; thence it springs, and all the efforts of imagination 
 cannot attain it for those who have not been blessed with a mother's 
 name. T^^fL^^H^C^/ , ' 
 
 All passion springs from desire, and supposes a certain degree of 
 exaltation of the intellectual faculties. The shades of the passions 
 are infinite : they might all be arranged by a systematic scale ; of 
 which indifference would be the lowest gradation, and maniacal rage 
 the highest. A man without passions is as impossible to imagine as a 
 man without desires; yet we distinguish as passionate those whose 
 will rises powerfully towards one object earnestly longed for. In the 
 delirium of the passions, we are for ever making, unconsciously, false 
 judgments, of which the error is exaggeration. A man recovering 
 from a seizure of fear, laughs at the object of his terror. Look at the 
 lover ''whose passion is extinct! freed at last from the spell that 
 enthralled him, all the perfections with which his love had invested 
 its object are vanished : the illusion has passed away ; and he can 
 almost believe that it is she who is no longer the same, while himself 
 alone is changed : like those maniacs who, on their return to reason, 
 wonder at the excesses of their delirium, and listen incredulously to 
 the relation of their own actions. The ambitious man feeds on 
 imaginations of wealth and power. He who hates, exaggerates the 
 defects of the object of his hatred, and sees crimes in his slightest 
 faults. 
 
 The affections of the soul, or the passions, whether they come by 
 the senses, or some disposition of the vital organs favour their birth 
 and growth, may be ranged in two classes, according to their effects 
 on the economy. Some heighten organic activity; such are joy, 
 courage, hope, and love ; whilst others slacken the motions of life, as 
 fear, grief, and hatred. And others there are that produce the two 
 effects alternately, or together. So ambition, anger, despair, pity, 
 assuming, like the other passions, an infinite variety of shades, 
 according to the intensity of their causes, individual constitution, sex, 
 age, &c. at times increase, at times abate the vital action, and depress 
 or exalt the power of the organs. 
 
 The instances which establish the powerful influence of the 
 passions on the animal economy, are too frequent to need reciting. 
 Writers in every department furnish such as shew that excess of 
 pleasure, like excess of pain, joy too lively or too sudden, as grief too 
 deep and too unexpected, may bring on the most fatal accidents, and 
 even death. Without collecting in this place all the observations of 
 the sort with which books swarm, I shall content myself with referring 
 to those who have brought together the greatest number of facts under 
 one point of view ; as Haller, in his Physiology ; Tissot, in his Treatise
 
 360 OF SLEEPING AND WAKING. 
 
 on Diseases of the Nerves ; Lecamus, in his work on Diseases of the 
 Mind ; and Bonnefoy, in a paper on the Passions of the Soul, inserted 
 in the fifth volume of the Collection of Prizes adjudged by the Academy 
 of Surgery. 
 
 The effects of the passions are not, for their uniformity, the less 
 inexplicable. How, and why doe* anger give rise to madness, to 
 suppression of urine, to sudden death? How does fear determine 
 paralysis, convulsions, epilepsy, &c. ? Why does excessive joy a 
 sense. of pleasure carried to extremity produce effects as fatal as sad 
 and afflicting impressions? In what way can violence of laughter lead 
 to. death? Excess of laughter killed the painter Zeuxis, and the 
 philosopher Chrysippus, according to the relation of Pliny. The 
 conversion of the reformed of the Cevennes, under Louis XIV., was 
 effected by binding them on a bench, and tickling the soles of their 
 feet, till, overpowered by this torture, they abjured their creed : many 
 died in the convulsions and immoderate laughter which the tickling 
 excited.* A hundred volumes would be insufficient to detail all the 
 effects of the passions on physical man : how many would it take to 
 tell their history in moral man, from their dark origin through all their 
 stages of growth, in the infinite variety of their characters, and in all 
 their evanescent shades ! 
 
 The inquiries of Physiology are directed to the functions that are 
 carried on in physical man to the functions of life : the study of the 
 nobler parts of ourselves, of those wonderful faculties which place our 
 kind above all that have motion or life ; in a word, the knowledge of 
 moral and intellectual man, belongs to the science known by the name 
 of metaphysics, or psychology, of analysis of the understanding ; but 
 better described by that applied to it by the writers of our days, ideology, 
 or the science of ideas. On this science you may consult with advantage 
 the philosophical works of Plato and Aristotle, among the ancients ; 
 of Bacon, Hobbes, Locke, Condillac, Bonn, Smith, Reid, Dugald 
 Stewart, Brown, Cabanis, and Tracy, among the moderns. 
 
 CLX. Of sleep and waking. The causes of excitation to which 
 our organs are exposed during waking, tend to increase progressively 
 their action . the pulsations of the heart, for instance, are much more 
 frequent in the evening than in the morning; and this motion, 
 gradually accelerated, would soon be carried to a degree of activity 
 incompatible with the continuance of life, did not sleep daily temper 
 this energy, and bring it down to its due measure. Fever is occa- 
 
 * This instance, however, does not illustrate the influence of the passions on 
 the vital functions. It shews merely the effects of irritation of the extremities of 
 nerves upon the functions of other nerves, either of the same, or of a different 
 order, which effects are either produced by a direct medium of communication with 
 the nerves first affected, or then by means of the aiervous centres. J. C.
 
 OF SLEEPING AND WAKING. 361 
 
 sjoned by long-continued want of sleep ; and in all acute diseases the 
 exacerbation conies on towards evening ; the night's sleep abates again 
 the high excitation of power : but this state of the animal economy, so 
 salutary and so desirable in all sthenic affections, is more injurious than 
 useful in diseases consisting chiefly in extreme debility. Adynamia 
 shews itself almost always in the morning in putrid fevers ; and 
 petechise, a symptom of extreme weakness, break out during sleep. 
 This state is likewise favourable to the coming on a^id to the progress 
 of gangrene ; and this is a pathological fact well ascertained. In all 
 the cases I have mentioned sleep does not improve the condition of 
 the patients ; a thing easy to conceive, since it only adds to accidental 
 debility, the essential characteristic of the disease, weakness, which is 
 also its principal characteristic. 
 
 Sleep, that momentary interruption in the communication of the 
 senses with outward objects, may be defined the repose of the organs 
 of sense and of voluntary motion. During sleep, the inward or 
 assimilating functions are going on : digestion, absorption, circulation, 
 respiration, secretion, and nutrition, are carried on ; some, as absorption 
 and nutrition,* with more energy than during waking, whilst others are 
 evidently slackened. During sleep the pulse is slower and weaker, in- 
 spiration is less frequent, and insensible perspiration, urine, and all other 
 humours derived from the blood, are separated in smaller quantity. 
 Absorption is, on the contrary, very active : hence the danger of 
 falling asleep in the midst of a noxious air. It is known that the 
 marshy effluvia, which makes the Campagna di Roma so unhealthy, 
 brings on, almost inevitably, intermittent fevers, when the night is 
 passed there, whilst travellers who go through without stopping, are 
 not affected by it.f 
 
 The human body is -a tolerable representation of the centripetal 
 and centrifugal powers of ancient physics. The motion of many of 
 
 * Nutrition is evidently more active during sleep, in early life, especially in 
 childhood ; and, in many constitutions and habits of body, it appears equally active, 
 during this state, through the middle stages of life ; but as soon as the period of 
 decay approaches, absorption appears to predominate, while, on the contrary, 
 nutrition gradually languishes more and more, during sleep, as age advances. In 
 the middle periods of existence it is difficult to determine whether absorption or 
 nutrition is augmented during this state : the difference cannot always be cor- 
 rectly appreciated ; but we generally find that when the one is increased the other 
 is diminished, both functions being seldom augmented or impaired at the same 
 time J. C. 
 
 f- This is quite as much the result of the low state of the nervous or vital 
 energy of the system during sleep. The vital powers at that time are not under 
 the impression of the excitements communicated through the medium of the nerves 
 of sensation and motion ; the operations, indeed, of this part of the nervous system 
 are for a time suspended, and consequently the vital functions lose part of their 
 energy, and are open to the influence of such causes of disease as generally invade
 
 362 OF SLEEPING AND WAKING. 
 
 the systems which enter into its structure is directed from the centre to 
 the circumference : it is a real exhalation that carries out the result of 
 the perpetual destruction of the organs; such is the action of the 
 heart, of the arteries, and of all the secretory glands. Other actions, 
 on the contrary, take their direction from the circumference to the 
 centre ; and it is by their means that % we are incessantly deriving from 
 the food we take into the digestive passages, and from the air 
 which penetrates the interior of the lungs, and covers the surface 
 of the body, the elements of its growth and repair. These two 
 motions, in opposite directions, continually balance each other, pre- 
 vailing by turns, according to the age, the sex, and the state of sleep 
 or waking. During sleep the motions tend from the periphery to 
 the centre (Hipp.) ; and if the organs that connect us with outward 
 objects are in repose, the inward parts are in stronger exertion.* 
 A man, aged forty years, taken with a kind of imbecility, re- 
 mained about a year and a half at the Hospital of St. Louis, for the 
 cure of some scrofulous glands. All that long time he remained 
 constantly in bed, sleeping five-sixths of the day, tortured with 
 devouring hunger, and passing his short moments of waking in eating : 
 his digestion was always quick and easy ; he kept up his plumpness, 
 though the muscular action was extremely languid, and the pulse very 
 weak and very slow. In this man, who, to use the expression of 
 Bordeu, lived under the dominion of the stomach, the moral affections 
 were limited to the desire of food and of repose. Oppressed with 
 irresistible sloth, it was never without great difficulty that he could be 
 brought to take the slightest exercise. 
 
 Waking may be looked upon as a state of effort, and of con- 
 siderable expenditure of the sensitive and moving principle, by the 
 organs of sensation and of motion. This principle would have been 
 
 them during states of debility and exhaustion, or when they are not otherwise 
 acted on either by external or internal stimuli. 
 
 It may be justly asserted, that the operations of the system languish in a degree 
 proportionate to that in which they are deprived of their natural excitements, 
 whether these excitements are food, air, exercise, amusement, &c whether they 
 are corporeal or mental or whether they are external or internal in respect of 
 their modes of existence and their manner of operation on the body. When, 
 therefore, the system is deprived of a part of these excitements of the influences 
 of the mental operations, and of the excitements of sensation and voluntary motion, 
 as it is during sleep, its operations are necessarily more languid and weak, and 
 consequently it is more readily impressed by many of the causes of disease, especially 
 by those which are usually productive of fever, than during the waking state. 
 The condition of the night air in respect of temperature, and the concentration of 
 the moisture and of the terrestrial exhalations in the lower regions of the atmo- 
 sphere, especially in particular situations, also contribute to the effect mentioned 
 in the text J. C. 
 
 * Somnus labor viseeribus. (Hipp.)
 
 OF SLEEP. 363 
 
 soon exhausted by this uninterrupted effusion, if long intervals of 
 repose had not favoured its restoration. This interruption in the 
 exercise of the senses and of voluntary motion, is of duration cor- 
 responding to that of their exertion. I have already said, that there 
 are functions of such essential importance to life, that their organs 
 could be allowed but short moments of repose ; but that these intervals 
 are brought so close to each other, that their time is equally divided 
 between activity and repose. The functions which keep up our 
 connexion with outward objects could not be without the capacity of 
 continuing, for a certain time, in a state of equal activity ; for it is 
 easy "to see how imperfect would have been relations interrupted 
 at every moment: their repose, which constitutes sleep, is equally 
 prolonged. 
 
 The duration of sleep is from a fourth to a third of the day : few 
 sleep less than six hours, or more than eight. Children, however, 
 require longer sleep, the more the nearer they are to the period of 
 their birth. Old men, on the contrary, have short sleep, light and 
 broken; as if, says Grimaud, according to Stahl's notions, children 
 foresaw that in the long career before them, there was time enough 
 for performing at leisure all the acts of life; while old men, near to 
 their end, felt the necessity of hurrying the enjoyment of a good 
 already about to escape. 
 
 If the sleep of a child is long, and deep, and still, it is the wonderful 
 activity of the assimilating functions that makes it so, and perhaps the 
 habit itself of sleep, in which he has passed the first nine months of his 
 life, or all the time before his birth. In advanced age, the internal 
 functions grow languid ; their organs no longer engage the action of 
 the principle of life ; and the brain is, moreover, so crowded with ideas, 
 that it is almost always kept awake by them. Carnivorous animals 
 sleep longer than graminivorous, because during waking they are more 
 in motion, and, perhaps, too, because the animal substances on which 
 they subsist yielding them more nutritious particles from the same 
 bulk, they have need of less time for devouring their food and pro- 
 viding for their subsistence.* 
 
 Sleep is a state essentially different from death, to which some 
 authors have erroneously likened it.f It merely suspends that portion 
 
 * Probably, their more powerful digestion of a more nutritious food brings 
 into the system a copious and sudden accession of chyle, which oppresses them with 
 sleep, circumstances required to recruit the powers that have been exhausted by 
 the laborious quest of food, and by the long-continued endurance of hunger. 
 
 Animal food, according to the extent to which it is indulged in, or the length of 
 the intervals between its use, produces either absolute or relative vascular plethora, 
 both which states dispose to sleep J. C. 
 
 f To say that sleep is the image of death, that vegetables sleep always, is to
 
 364 OF SLEEP. 
 
 of life which serves to keep up with outward objects an intercourse 
 necessary to our existence. One may say that sleep and waking call 
 each other, and are of mutual necessity. The organs of sense and 
 motion, weary of acting, rest; but there are many circumstances 
 favouring this cessation of their activity. A continual excitation of 
 the organs of sense would keep them continually awake ; the removal 
 of the material causes of our sensations tends, therefore, to plunge 
 us into the arms of sleep : wherefore we indulge in it more voluptuously 
 in the gloom and the stillness of night.* Our organs fall asleep 
 one after the other ; the smell, the taste, and the sight, are already at 
 rest, when the hearing and the touch still send up faint impressions. 
 The perceptions, awhile confused, in the end disappear ; the internal 
 senses cease acting, as well as the muscles allotted to voluntary 
 motion, whose action is entirely subject to that of the brain. 
 
 Sleep is a state, if not altogether passive, in which at least the 
 activity of most of the organs is remarkably diminished, and that 
 of some of them is completely suspended. It is erroneously, then, 
 that some authors have viewed it as an active phenomenon, and a 
 function of the living economy : it is only a mode or manner of being. 
 It is to no purpose they have maintained that to sleep required some 
 measure of strength. Excessive fatigue hinders sleep merely by a 
 sense of pain in all the muscles, a pain that excites anew the action 
 of the brain, which it keeps awake, till it is itself overpowered by 
 sleep. 
 
 It has been attempted to shew the proximate cause of sleep. Some have 
 said that it depends on the collapse of the laminae of the cerebellum ; 
 which, as they conceive, are in a state of erection during waking; and 
 they argue from the experiment in which, by compressing the cerebellum 
 of a living animal, sleep is immediately brought on. This sleep, like 
 that produced by compression of any other part of the cerebral mass, 
 is really a state of disease, and no more natural than apoplexy. Others, 
 conceiving sleep, no doubt, analogous to this affection, ascribe it to the 
 collection of humours upon the brain during waking. This organ, say 
 they, compressed by the blood which obstructs its vessels, falls into 
 a state of real stupor; an opinion as unsupported as the other. As 
 long as the humours flow in abundance towards the brain, they keep 
 up in it an excitement which is altogether unfavourable to sleep. Do 
 we not know, that it is enough that the brain be strongly occupied by its 
 
 use an inaccurate and unmeaning expression. How can plants, without brain or 
 nerves, without organs of sense, motion, or voice, sleep, when sleep is nothing but 
 the repose of these organs ? 
 
 * The tissue of the eye-lids is not so opaque but we may distinguish through 
 them light from darkness : accordingly, a lighted torch in the room hinders us from 
 sleeping. For the same reason day succeeding to night awakens us.
 
 OF DREAMS. 365 
 
 thoughts, or vividly affected in any way, to repel sleep ? Coffee, and 
 spirituous liquors in small quantities, will produce sleeplessness, by ex- 
 citing the force of the circulation, and determining towards the brain a 
 more considerable afflux of blood. All, on the other hand, that may 
 divert this fluid towards another organ, as copious bleedings, pedilu- 
 vium, purges, digestion, copulation, severe cold, or whatever diminishes 
 the force with which the blood is driven towards the brain, as inebria- 
 tion, or general debility, tends powerfully to promote sleep. In like 
 manner, it is observed, that while sleep lasts the cerebral mass col- 
 lapses ; a sign that the flow of blood into it is remarkably lessened. 
 
 The organs of the senses, laid asleep in succession, awake in the 
 same manner. Sounds and light produce impressions, confused at 
 first, on the eyes and ears : in a little time these sensations grow dis- 
 tinct ; we smell, we taste, we judge of bodies by the touch. The 
 organs of motion prepare for entering into action, and begin to act at 
 the direction of the will.* The causes of waking operate by determin- 
 ing a greater flow of blood into the brain ; they include all that can 
 affect the senses, as the return of light and of noise, with the rising of 
 the sun : at times they act within us. Thus, urine, feecal matter, other 
 fluids accumulated in their reservoirs, irritate them, and send up to- 
 wards the brain an agitation which assists in dispelling slumber. 
 Habit, too, acts upon this phenomenon, as on all those of the nervous 
 and sensitive system, with most remarkable influence. There are many 
 that sleep soundly amidst noises which, at first, kept them painfully 
 awake. Whatever need he may have of longer repose, a man that has 
 fixed the daily hour of his awaking, will awake every morning to his 
 hour. It is as much under the controul of the will : it is enough to will 
 it strongly, and we can awake at any hour we choose. 
 
 GLXI, Of dreams and somnambulism. Although sleep implies 
 the perfect repose of the organs of sensation and of motion, some of 
 these organs persist in their activity ;f which obliges us to acknowledge 
 intermediate states between sleep and waking, real mixed situations, 
 which belong, more or less, to one or to the other. Let us suppose, 
 for instance, that the imagination reproduces in the brain sensations it 
 has formerly known ; the intellect works, associates and combines 
 ideas, often discordant, and sometimes natural ; brings forth monsters, 
 horrible, or fantastic, or ridiculous ; raises joy, hope, grief, surprise, or 
 terror ; and all these fancies, all these emotions, are recollected more 
 
 * See the Chapter on Motion, Art. CLXII. 
 
 f The individual who even enjoys the most profound sleep, seldom wakens in 
 the same position as that in which he was at the moment of falling asleep : it is 
 changed frequently during the time, owing, perhaps, to certain obscure sensations 
 giving rise to movements analogous to those of the foetus in utero, although more 
 perfect, and seemingly influenced by habit, &c.
 
 366 OF SOMNAMBULISM 
 
 or less distinctly when we are again awake, so as to allow no doubt 
 but that the brain has been really in action during the repose of the 
 organs of sense and motion. Dreams is the name given to these phe- 
 nomena.** Sometimes we speak in sleep, and this brings us a little 
 nearer to the state of waking, since, to the action of the brain, is added 
 that of the organs of speech. Finally, all the relMive functions are 
 capable of action, excepting the outward senses. The brain acts, and 
 determines the action of the organs of motion or speech, only in con- 
 sequence of former impressions ; and this state, which differs from 
 waking only by the inaction of the senses, is called somnambulism. 
 
 On this head we meet with surprising relations. Somnambulists 
 have been seen to get up, dress, go out of the house, opening and 
 shutting carefully all the doors, dig, draw water, hold rational and con- 
 nected discourse, go to bed again, and awake without any recollection 
 of what they had said and done in their sleep. This state is always 
 very perilous : for as they proceed entirely upon former impressions, 
 somnambulists have no warning fronft their senses of the dangers they 
 are near. Accordingly, they are often seen throwing themselves out 
 of a window, or falling from roofs on which they have got up, without 
 being on that account more dexterous in balancing themselves there, 
 as the vulgar believe, in their fondness for the marvellous. 
 
 Sometimes one organ of sense remains open to impression, and 
 then you can direct at pleasure the intellectual action. Thus, you 
 will make him that talks in his sleep, speak on what subject you 
 choose, and steal from him the confession of his most secret thoughts. 
 This fact may be cited in proof of the errors of the senses, and of the 
 need there is to correct them by one another. 
 
 The condition of the organs influences the subject of the dreams. 
 The superabundance of the seminal fluid provokes libidinous dreams ; 
 those labouring under pituitary cachexies will dream of objects of a hue 
 like that of their humours. The hydropic dreams of waters and foun- 
 tains ; whilst he who is suffering with an inflammatory affection, sees 
 all things tinged red, that is, of the colour of blood, the predominant 
 humour. 
 
 Difficult digestion disturbs sleep. If the stomach, over-filled with 
 food, hinders the falling of the diaphragm, the chest dilates with diffi- 
 culty, the blood, which cannot flow through the lungs, stagnates in the 
 right cavities of the heart, and a painful sensation comes on, as if an 
 enormous weight lay upon the chest, and were on the point of pro- 
 ducing suffocation : we awake with a start, to escape from such urgent 
 danger : this is what we call night-mare, an affection that may arise 
 from other causes, hydrothorax, for instance, but which always depends 
 on the difficult passage of blood through the lungs. 
 
 * See the Note on Dreaming, in the APPENDIX, Notes H. H.
 
 OF DREAMING. 367 
 
 The intellectual faculties which act in dreams, may lead us to cer- 
 tain orders of ideas which we have not been able to compass while 
 awake. 
 
 Thus mathematicians have accomplished in sleep the most com- 
 plex calculations, and resolved the most difficult problems. It is 
 easily understood how, in the sleep of the outward senses, the sen- 
 sitive centre must be given up altogether to the combination of ideas 
 in which it must work with more energy. It is seldom that the action 
 of imagination on the genital organs, during waking, goes the length 
 of producing emission : nothing is more common in sleep. 
 
 The human species is not the only one that in sleep is subject to 
 agitations, which are generally comprehended under the name of 
 dreams : they occur in animals, and most in those whose nature is 
 most irritable and sensible. Thus the dog and horse dream more than 
 the ruminating kinds, the one barks, the other neighs in sleep. Cows 
 that are suckling their calves, utter faint lowings : bulls and rams 
 seem goaded by desires, which -they express especially by peculiar 
 motions of their lips. 
 
 After what has been said of sleep and dreams, it will not be diffi- 
 cult to explain why there is so little refreshment of the powers from 
 sleep that is harassed by uneasy dreams. We often awake exceedingly 
 fatigued with the distress of imaginary dangers, and the efforts we have 
 made to escape them. 
 
 We have seen the relations of man with the external world esta- 
 blished by means of peculiar organs, which, through the intervention of 
 nerves, all centre in one, the chief and essential seat of the function of 
 which this chapter treats. As the phenomena of the sensations are 
 brought about by the intervention of an unknown agent, and as, like 
 those of electricity and magnetism, they appear not to be subject to 
 the ordinary laws of matter and motion, they have thrown open the 
 widest field to the conjectures of ignorance and the inventions of 
 quackery. It is for their explanation that the greatest abundance and 
 the wildest of theories have been devised.* 
 
 * Take, for instance, the following : On the 23d of December, it is not said in 
 what year, a physician of Lyons, M. Petetin, was called in to a young lady of 
 nineteen, sanguine and robust. She was cataleptic. The doctor employed various 
 remedies ; and, among others, one day bethought himself of pushing over the patient 
 on her pillow : he himself fell with her, half stooping upon the bed, and this led 
 him to the " discovery of the transport of the senses in the epigastrium to the 
 extremity of the fingers and of the toes." I use his own pompous and barbarous 
 expressions in announcing his discovery. Our doctor goes on to tell, with all 
 gravity, how, putting a bun on the epigastrium of the patient, she perceived the 
 taste, which was followed by motions of deglutition. If his word is to be taken, 
 hearing, smell, taste, sight, and touch, were all there ; the outward senses being for 
 the time completely laid asleep. To give an air of credibility to the matter, he
 
 368 OF VOLUNTARY" A1OTIO 
 
 JHAPTER VIII. 
 
 (.)!' VOLUNTARY MOTION 
 
 >V \J.-LJ L; 11 JL /X IV X 1U, \J A 1 \_J J.1 * 
 
 tractive and passive. CLX II I. 
 
 CLXII. Division of Motion iff* active and passive CLXTII. Of the Structure 
 and Properties of Muscles S^d Tendons.- CLXIV. Of the Phenomena of 
 Muscular Contraction. CLXV. Theory of Muscular Contraction. CLXVI. 
 
 Of the Preponderance of the Fk-xor Muscles over the Extensors CLXVII. 
 
 Pathological Physiology of Muscular Action CLXVIII. Of the Power of the 
 
 Muscles, and of the mode of estimating that Power CLXIX. Of the fixed 
 
 Point, or Fulcrum, in Muscular Actions CLXX. Of the Nature of Muscular 
 Flesh. _ CLXXI. and CLXXII. Of Galvanism. _ CLXXIII. Apparatus of 
 Volta CLXXI V. Relations and Medical Uses of Galvanism. CLXX V. Ge- 
 neral View of the Osseous System CLXXVI. Structure of the Bones 
 
 CLXXVII. Of the Uses of the Periosteum and of the Medullary Juices 
 CLXX VI II. Of the Articulations, the Articulating Cartilages, the Ligaments, 
 and the Synovial Fluid. CLXXIX. Theory of Anchylosis. CLXXX. Of 
 
 Standing, &c CLXXXI. to CLXXXV. Of the Mechanism of Standing 
 
 CLXXXVI. Of the recumbent Postures CLXXXVII. Of the Motions of 
 
 Progression. CLXXXVIII. Of Running. CLXXXIX. Of Leaping. 
 
 CXC. Of Swimming CXCL Of Flying CXCII. Of Crawling CXCIII. 
 
 Of partial Motions performed by the upper Extremities. 
 
 CLXII. Division of motions into active and passive. This chapter 
 will treat only of the motions performed by the muscles under the 
 influence of the will : they are called muscles of locomotion, as it is by 
 
 adds, that she saw the inside of her body, guessed what was in the pockets of 
 bystanders, and made no mistake in the money in their purses ; but the miracle was 
 over the moment they lapped the objects in silk, or a coat of wax, or interposed 
 any other non-conductor. Finally, to put to proof the whole power of faith in his 
 readers, M. Petetin exclaims, " Oh, prodigy beyond conception ! was a thought 
 formed in the brain, without any sign of it in words, the patient was instantly 
 acquainted with it." * Further details of so incredible a story would be altogether 
 superfluous. 
 
 I should not have disturbed the book of M. Petetin from its peaceful slumber 
 among the innumerable pamphlets which Mesmerism has brought into the world, if 
 a writer on physiology had not been the dupe of this mystification, and had not 
 proceeded, from it, to write a long chapter on metastases of sensibility. 
 
 If we should be so unfortunate as to be reproached by the lovers of the marvel, 
 lous with pushing scepticism too far, we must make answer, that M. Petetin is the 
 sole witness of his miracle ; that it is impossible, from his relation, to know when 
 or on whom the prodigy took place ; and that this zealot of magnetism might have 
 invented this story to confound the unbelievers who ventured to turn into ridicule 
 his system on the electricity of the human body. 
 
 * Electricitc Animale, 1 vol. 8vo. Lyon, 1808.
 
 STRU*:TITKE OF MUSCLES. 369 
 
 means of them that the body changes its situation, moves from one 
 spot to another, avoids or seeks surrounding objects, draws them 
 towards itself, grasps them, or repels them. The internal, involuntary, 
 and organic motions, by means of which each function is performed, 
 have already been investigated separately. 
 
 The organs of motion may be distinguished into active and passive ; 
 the former are the muscles, the latter the bones, and all the parts by 
 which they are articulated. In fact, when in consequence of an 
 impression received by the organs of sense, we wish to approach 
 towards the object that produced it, or to withdraw from it, the mus- 
 cular organs, called into action by the brain, contract ; while the bones, 
 which obey this action, perform only a secondary part, are passive, 
 and may be looked upon as levers absolutely inert. 
 
 CLXIII. Of the structure and properties of the muscles and 
 tendons. The muscles consist of bundles of fibres, always, to a cer- 
 tain degree, red in man : this colour, however, is not essential to 
 them, since it may be removed, and the muscular tissue blanched 
 by maceration or by repeated washing. 
 
 Whatever may be the situation, the length, the breadth, the thick- 
 ness, the w form, or the direction of a muscle, it is formed of a collection 
 of several fasciculi of fibres, enveloped in a cellular sheath, similar to 
 that which covers the muscle itself and separates it from the sur- 
 rounding parts. Each fasciculus is formed of the union of a multitude 
 of fibres, so delicate that anatomy cannot reduce them to their ulti- 
 mate division, and that the smallest distinguishable fibre is still formed 
 by the juxta-position of numerous fibrillse of incalculable minuteness. 
 As the last divisions of the muscular fibre completely elude our means 
 of investigation, it would be very absurd to attempt to explain their 
 minute structure, and, after the example of Muys, to write a volu- 
 minous work on this obscure part of physiology. Shall we say, with 
 the above author, that each distinguishable fibre is composed of three 
 fibrillse, progressively decreasing in size; with Leuwenhoek, that the 
 diameter of this elementary fibre is only the hundred thousandth part 
 of a grain of sand; with Swammerdam, de Heyde, Cowper, Ruysch, 
 and Borelli, that this primitive fibre consists of a series of globular, 
 rhomboidal molecules ; with Lecat, that it is nervous ; with Vieussens 
 and Willis, that it is formed by the extreme ramifications of arteries ; 
 with others, that it is cellular, tomentose, &c. ? How is it possible to 
 speak, with any degree of certainty, of the nature of the parts of a 
 whole, which, from its extreme minuteness, eludes our most accurate 
 investigations? To explain the phenomena of muscular action, it is 
 sufficient to conceive each fibre as formed of a series of molecules of a 
 peculiar nature, united together by some unknown medium, whether 
 that be oil, gluten, or any other substance, but whose cohesion is mani-
 
 370 STRUCTURE OF MUSCLES. 
 
 festly kept up by the vital power, since the muscles yield, after death, 
 to efforts by which during life they would not have been torn; and 
 such is their tenacity, that they are very seldom ruptured.* 
 
 These fibres, which, when irritated, possess in the highest degree 
 the power of shortening themselves of contracting, however minute 
 one may suppose them, are supplied with vessels and nerves. In fact, 
 though they are neither vascular no'r nervous, as may be readily ascer- 
 tained by comparing the bulk of the vessels and nerves which enter 
 into the structure of the muscles with that of these organs, and by 
 attending to the difference of their properties, each fibre receives the 
 power of contracting from the blood brought to it by the arteries, and 
 from the fluid transmitted from the brain along the nerves. A cellular 
 sheath surrounds these fibrillse (and the nerves and vessels, perhaps, 
 terminate within it);f others unite them together: the fasciculi of 
 fibres are enclosed in common sheaths, and these unite in the same 
 manner into masses varying in size, and the union of which forms the 
 muscles. Fat seldom accumulates in the cellular tissue which connects 
 together ' the smallest fasciculi ; it collects in small quantity in the 
 interstices of the more considerable fasciculi. Lastly, it is in rather 
 greater quantity around the muscle itself. A lymphatic and aqueous 
 vapour fills these cells, maintains the suppleness of the tissue, and 
 promotes the action of the organ, which a fluid of more consistence 
 would have impeded. 
 
 The greater number of muscles terminate in bodies, generally 
 round, of a brilliant white colour, that forms a striking contrast with 
 
 * M. Baiter, by the assistance of his powerful microscope, discovered muscular 
 fibres to be chains of globules, and he conceived that they may be constructed from 
 the globules of fibrine arranged in lines J. C. 
 
 f- The majority of anatomists suppose that the muscular fibre itself is beyond 
 the circuit of the circulation ; and this appears in some points of view the correct 
 opinion, if we attend to the form and size of the fibres, and to their connexions 
 with the cellular tissue ; but, although we may grant that the red globules of the 
 blood do not circulate through the muscular fibres themselves, and that these 
 globules pervade only the capillaries of the connecting cellular substance, still we 
 must allow that they are formed, and afterwards supported, either by the vessels 
 conveying red blood, assimilation taking place in the manner of a deposit from 
 them, without any continuity of taxture, or by the medium of a direct communi- 
 cation and admixture of a particular series of capillary terminations of vessels with 
 the muscular fibre, into which the red globules cannot enter, owing to the great 
 tenuity of these capillaries. If we choose the former alternative, which appears, 
 however, the least probable, we may conceive that the nervous terminations in 
 muscular parts soften into an invisible pulp, and unite intimately with the capillary 
 vessels, and with the cellular texture which connects the individual muscular fibres ; 
 and that the chain of globules, of which these fibres are composed, being acted on by 
 the influence resulting from the action of the nervous on the vascular terminations, 
 in the enveloping cellular substance, experience in consequence a contraction in pro- 
 portion to the nervous excitement. In thin case we must suppose a certain infln-
 
 SSTBUCTUKK OF Ml'srLES, &C. 371 
 
 the red colour of the muscular flesh, into which one of their extre- 
 mities is imbedded, while the other extremity is attached to the bone, 
 and is lost in the periosteum, though the tendons are quite distinct 
 from it. The tendons are formed by a collection of longitudinal and 
 parallel fibres: their structure is more compact than that of the 
 muscles; they are harder, and apparently receive neither nerves nor 
 vessels ; they consequently possess but a very inferior degree of vita- 
 lity ; hence they are frequently ruptured by the action of the muscles. 
 The muscular fibres are implanted on the surface of the tendinous 
 cords, without being continuous with the filaments forming the latter : 
 they join them in a different manner, and at angles more or less 
 obtuse. 
 
 The tendons, in penetrating into the fleshy part of the muscles, 
 expand, become thinner, and form thus the internal aponeuroses. 
 The external aponeuroses, independent of the tendons, though the 
 same in structure, differ from them only in the thinness and greater 
 surface of the planes formed by their fibres. At one time they cover 
 a portion of the muscle to which they belong ; at another, they sur- 
 round the whole limb, furnishing points of insertion to the muscles : 
 they prevent the muscles and their tendinous cords from being dis- 
 placed ; and in a manner direct their action and increase their power, 
 in the same way as a moderately tight girdle adds to the power of an. 
 athlete. 
 
 We cannot admit, with Pouteau, that the muscles of the limbs, 
 though applied to the*bones by aponeurotic coverings, can become 
 displaced, so as to form herniae. When they contract in a wrong 
 
 ence to emanate from the connecting medium to the muscular fibre, without any 
 -ether communication than that of contact or contiguity. If, on the other hand, we 
 adopt the latter alternative, and believe that an order of capillary vessels, of great 
 tenuity, enters into the structure of muscular fibres, and that the voluntary and 
 organic nerves which blend with the capillary vessels also proceed to and terminate 
 in this structure, we may farther conclude and, indeed, the conclusion will neces- 
 sarily follow that the muscular fibre is composed of a certain order of capillary ves- 
 sels, and of the terminations of the ganglial nerves (which nerves we must suppose 
 to supply, and to terminate with these capillaries, as they are found to envelope, 
 and to he distributed to the muscular and internal coats of the larger ramifications 
 or trunks of the vessels whence the capillaries are sent off,) with the extremities of 
 the voluntary nerves, which are so abundantly supplied to the muscles of loco- 
 motion. Having considered that the muscular fibre is formed from this combination, 
 we have not data whence we can farther infer its intimate nature, or the extent to 
 which each of these systems contributes to its formation in the voluntary muscle?. 
 We may suppose, however, that the functions of these textures differ according a* 
 either of the constituents which we have now assigned them predominate in their 
 constitution, (see note at p. 16). The observations of M. Bauer, we may state, 
 seem to support the view we have now offered See APPENDIX, Notes II, for 
 farther observations on this subject, and on Irritability J. C.
 
 372 OF MI7SCULAK CONTRACTION'. 
 
 position, some fibrillse are torn, and this gives rise to most of those 
 momentary and very sharp pains called cramp. I have at present 
 before me the case of a young girl, in whom the aponeurosis of the 
 leg, exposed in consequence of an extensive ulceration, exfoliated 
 from the middle and fore part of the limb to the instep. This exfo- 
 liation was accompanied by a displacement of the tibialis anticus, and 
 of the extensors of the toes ; the leg is become deformed, the motions 
 of extension of the foot and toes are performed with difficulty, and will 
 soon become impossible, when the exfoliation of the tendons follows 
 that of the aponeurosis which protected them from the air. 
 
 CLXIV. Phenomena of muscular contraction. When a muscle 
 contracts, its fibres are corrugated transversely, its extremities are 
 brought nearer to each other, then recede, and again approach towards 
 one another. These undulatory oscillations, which are very rapid, are 
 followed by a slighter degree of agitation ; the body of the muscle, 
 swollen and hardened in its decurtation, has acted on the tendon in 
 which it terminates; and the bone to which the latter is connected is set 
 in motion, unless other agents, more powerful than the muscle which 
 is in action, prevent its yielding to that impulse. Such are the pheno- 
 mena exhibited by the muscles exposed in a living animal or in man, 
 when their contractions are brought on by the application of a stimulus. 
 But these contractions, determined by external causes, are never so 
 strong or instantaneous as those which are determined by the will in 
 a powerful and sudden manner. When an athletic man, reduced by 
 illness, powerfully contracts the biceps muscle of the arm, this muscle 
 is seen to swell suddenly, to stiffen, and to continue motionless in that 
 state of contraction, as long as the cerebral influence, or the act of the 
 will, which determines it, lasts. 
 
 Though the muscles manifestly swell in contracting, and though 
 the limbs are confined by the ligatures applied round them, the whole 
 bulk of the contractile organ diminishes ; it loses in length more than 
 it gains in thickness. This is proved by Glisson's experiment, which 
 consists in immersing the arm in a vessel filled with a fluid, which 
 sinks when the muscles act. We cannot, however, estimate the dimi- 
 nution of bulk by the degree in which the fluid sinks, since that effect 
 is in part owing to the collapse of the layers of the adipose tissue, 
 which is compressed in the muscular interstices. 
 
 A sound state of the vessels and nerves distributed to muscles is 
 indispensable to their contraction. If the free circulation of the blood 
 or of the nervous fluid, is prevented by tying the arteries or nerves; if 
 the return of the blood along the veins is prevented by applying a 
 ligature to these vessels the muscles will be completely palsied. By 
 dividing or tying the nerves, the action of the muscles to which they 
 are distributed is suddenly interrupted. The same effect may be pro-
 
 OF MUSCULAll CONTRACTION.' 373 
 
 duced by intercepting the course of the arterial blood, though in a less 
 rapid and instantaneous manner ; and it is very remarkable, that it is 
 equally necessary that the veins should be as sound as the arteries to 
 enable muscular action to take place. Kaaw Boerhaave ascertained, 
 by actual experiment, that when a ligature is applied to the vena cava, 
 above the iliacs, paralysis of the lower extremities is brought on, as 
 readily as when the aorta is tied, as was clone by Steno in the same 
 situation.* And this is a further proof of what we have said elsewhere, 
 of the stupefying qualities of the blood which flows in the veins. 
 
 The irritability of the muscles destined to voluntary motions is 
 proportioned to the size and number of the nerves and arteries which 
 are distributed to their tissue.f The tongue, which of all the contrac- 
 tile organs receives the greatest number of cerebral nerves, is likewise 
 that which, of all those under the controul of the will, has most extent, 
 most freedom, and the greatest variety of motions.! The muscles of the 
 larynx and the intercostals receive nearly as many, considering the 
 smallness of these parts. || 
 
 CLXV. Theory of muscular contraction. Of all the hypotheses 
 applied to the explanation of the phenomena of muscular contraction, 
 that appears to me the most ingenious and the most probable which 
 makes it to depend on the combinations of hydrogen, of carbon, of 
 azote, and other combustible substances in the fleshy part of the muscle, 
 with the oxygen conveyed with the blood by the arteries. 
 
 * Ligature of the aorta may be conceived to produce paralysis, owing chiefly to 
 the stop it puts to the circulation of arterial blood in that part of the spinal cord, 
 and in the neurilema of the nerves, below where the ligature is placed. 
 
 j- See APPENDIX, Notes 1 1. 
 
 It is scarcely necessary to repeat, that I am not speaking of those motions, 
 more or less involuntary, performed by muscles which receive the nerves, in part or 
 wholly, from the great sympathetics. Though the particular nature of these nerves 
 has a remarkable influence on the organs to which they are distributed, we find 
 that the general rule is almost without exceptions, for the heart and diaphragm, 
 which hold the first rank among the parts endowed with irritability, receive a con- 
 siderable number of vessels and nerves. 
 
 || The disposition of the muscles to contract is different from, and even opposite 
 to, their energy of contraction. The feeble muscles of an hysterical female contract 
 so readily and so frequently from the slightest irritation, as nearly to appear invo- 
 luntary in their actions ; while, on the contrary, the powerful muscles of the athlete 
 act only from energetic stimuli and from fully expressed volition. Thus we observe 
 in feeble individuals a certain mobility of muscular parts and organs which does not 
 exist in the robust, as if the irritability of such parts was excited with a facility in 
 proportion to the deficiency of energetic action. The disposition of muscles to .con- 
 tract differs also according to the age of the animal, and it bears even some relation 
 to the organisation of the muscle itself. 
 
 See APPENDIX, Notes F F, for remarks on the period at which the voluntary 
 muscles are formed, and on their appearances and constitution at the different 
 periods of life J. C.
 
 374 OF MUSCULAH CONTRACTION. 
 
 To effect this combination it is necessary, not only that the muscle 
 be supplied with arterial blood, and that oxygen come in contact 
 with the substances which it is to oxydise, but it is required that a 
 stream of nervous fluid should penetrate through the tissue of the 
 muscle, and determine the decompositions which take place, as the 
 electrical spark gives rise to the formation of water by the combination 
 of the two gases of which it consists. '* According to this theory, first 
 proposed by Girtanner, all the changes which take place during the 
 contraction of a muscle, the turgescence, the decurtation, and the 
 induration of its tissue, and its change of temperature, depend on this 
 reciprocal action of the elements of the muscular fibre, and of the 
 oxygen of arterial blood. 
 
 Muscular flesh is harder, firmer, and more oxydised, according as 
 the animal takes much exercise. We well know what a difference there 
 is between the flesh of wild and of the domestic animals; between the 
 flesh of our common fowl and that of birds accustomed to remain long 
 on the wing : in the former it is white, tender, and delicate ; while in 
 the latter, it is tough, stringy, dark-coloured, carbonaceous, and of a 
 very strong smell. Respiration, of which the principal use is to impreg- 
 nate arterial blood* with the oxygen necessary to the contractions of the 
 muscular fibre, is more complete, and decomposes the greater quantity 
 of atmospherical air in those animals that are naturally destined to 
 most exertion. Those birds which support themselves in the air by 
 powerful and frequent motions, have likewise the most active respiration. 
 Athletes, who astonish us by the developement of their muscular 
 organs, and by the powerful efforts of which they are capable, all have 
 a very ample chest, a powerful voice, and very capacious lungs, f In 
 running, as there is a considerable consumption of the principle of 
 motion, we pant, that is, we breathe in a hurried manner, that there 
 may be the greatest possible quantity of blood oxydised to perform the 
 contractions necessary to the exercise of running. 
 
 The recent experiments of MM. Prevost and Dumas shew, that at 
 the moment when the influx of nervous influence occasions muscular 
 contraction, each muscular fibre is thrown into a zig-zag form. At each 
 point of flexion is placed a nervous filament, the direction of which is 
 perpendicular to that of the muscular fibres. But the nervous'filament 
 does not terminate there, nor unite with the muscular fibre, but merely 
 
 * See APPENDIX, Note W. 
 
 f I never saw a very strong man that had not broad shoulders, which indicates 
 a considerable developement of the cavity of respiration. .If there be individuals 
 that seem to be exceptions to this general latv, it is that by frequent exercise, and 
 by a laborious life, they have increased the natural power of their muscles. This 
 Increase is seldom universal, but almost always limited to certain parts which have 
 been most employed, as the arms, the legs, or the shoulders.
 
 01? MUSCULAR ACTION. 375 
 
 embraces it by a loop; for, after having crossed the muscular fibre 
 nearly at a right angle, the nervous filament is reflected upon itself, and 
 rejoins the branch whence it proceeded. Such being the conformation, 
 the phenomenon of muscular contraction takes place by the influence 
 of a double electric current proceeding in opposite directions, and of 
 which the nerves are the conductors. Owing to this double current, 
 and its alternating attractions and repulsions, all the muscular fibres 
 are thrown into a zig-zag form, and are shortened without any augment- 
 ation of their bulk.* 
 
 CLXVI. Of the preponderance of the flexors over the extensors. f 
 The extensor muscles are generally weaker than the flexors; hence 
 the most natural position, that in which all the powers are naturally in 
 equilibrio, that which our limbs assume during sleep, when the will 
 ceases to determine the vital influx to the parts under its control, 
 that in which we can continue longest without fatigue, is a medium 
 between flexion and extension, a real state of semi-flexion. 
 
 Attempts have been made to discover the cause of this preponder- 
 ance of the flexor muscles over their antagonists. According to Borelli, 
 the flexors being shorter than the extensors of the same articulation, 
 and contracting equally, J the former must occasion a more extensive 
 motion of the limbs, and determine them towards a state of flexion. 
 But it is, in the first place, incorrect to say that the flexors are shorter 
 than the extensors ; and in the next place, if we are to estimate by the 
 length of a muscle the extent of motion that may be produced by its 
 action, we ought not to measure the whole of the fleshy part, nor to 
 include in the calculation the tendinous cord which terminates it, but 
 to consider the length of its fibres, on which depends entirely the 
 extent of motion produced by its contractions. 
 
 The degree of decurtation of which a muscle is capable, is alwavs 
 proportioned to the length of its fleshy fibres, as is the power of con- 
 traction to the number of the fibres. Now, if the fibres of the flexors 
 are in greater number than those of the extensors, it follows, as a 
 necessary consequence, that the limbs will be brought into a state of 
 flexion when the principle of motion shall be distributed to them in an 
 equal quantity ; and 'even though the number of fibres should be the 
 same in the flexors and extensors, the limbs would still be in a state of 
 flexion, if the fibres of the former being longer, they made the parts 
 move through a greater space. 
 
 * See farther remarks on this subject in the APPENDIX, Notes 1 1. 
 
 f- The theory of the preponderance of the flexors is entirely my own, and was 
 first proposed by me in the collection of Memoirs of the Medical Society of Paris, 
 for the year 1799. 
 
 J " Musculi flexores ejusdem articuli breviores sunt extensoribus, et utrique 
 scque contrahuntur." Prop. 130, dc inotu animaltum.
 
 376 OF .MCsiTLAK ACTION'. 
 
 If we examine the different parts of the body, the articulations of 
 the limbs, and especially of the knee, the knowledge of which is of the 
 highest importance in comprehending the^ theory of standing, it will be 
 seen that the flexor muscles exceed the extensors in the number and 
 length of their fleshy fibres. If we compare the biceps cruris, the semi- 
 tendinosus, the semi-membranosus, the rectus internus, the sartorius, 
 the gemelli, the plantaris, and the popliteus, which all concur in the 
 flexion of the leg, to the triceps cruris and to the rectus, which extend 
 the leg, we shall readily understand that the fibres of these last are 
 much shorter, and in smaller number. Those of the sartorius and 
 rectus internus are the longest of all the muscles employed in voluntary 
 motion : the fibres of the posterior muscles of the limb are not inferior 
 in length to the fibres of the muscles at the fore part. 
 
 Besides, the flexor muscles are inserted into the bones -which 
 they are to move, farther from their centre of motion. In fact, if 
 the insertion of the semi-membranosus is situated nearly at the same 
 height, the sartorius, the rectus internus, the semi-tendinosus, the biceps, 
 and the popliteus, are inserted lower than the extensors of the leg. 
 But this difference is particularly observable in the plantaris and 
 geraelli, which terminate at the greatest possible distance from the 
 centre of motion, and which act witfra very long lever.* Lastly, most 
 of these muscles depart, much more than the extensors, from a parallel 
 direction to the bones of the leg. We all know the curved line of the 
 course of the sartorius, of the rectus internus, and semi-tendinosus, by 
 which the angle of their insertion becomes more favourable. 
 
 The flexor muscles which, on their being first called into action, 
 are nearly parallel to the levers which they are to move, tend to become 
 perpendicular to them ia proportion as the motion of flexion is carried 
 on. Thus, the brachialis, the biceps brachii, and the supinator longus, 
 the mean line of direction of which is nearly parallel to that of the 
 bones of the fore-arm, when the flexion of this limb commences, 
 become oblique, then perpendicular to this bone, and at last form with 
 it the angle most favourable to their action. The same applies to the 
 flexors of the leg : the angle of their insertion becomes greater the more 
 it bends on the thigh. The extensors, on the contrary, are in the most 
 favourable state for action at the moment when their contraction 
 begins : in proportion as the extension goes on, they have a tendency te 
 become parallel to the levers which they set in motion, and their action 
 even ceases before the parallelism is complete, at the elbow by the 
 
 * We may, in this respect, compare the gemelli to the snpinator longus, the use 
 of which is not limited, as was shewn by Heister, to the stipulation of the hand, 
 but which is likewise a flexor of the fore-arm, and acts the more powerfully as its 
 inferior insertion is at a greater distance from the elbow joint, and as its fibres are 
 the longest of all those of the muscles of the upper extremity.
 
 OF MUSCULAK ACTION. 377 
 
 resistance of the olecranon, and at the knee by the numerous ligaments 
 and by the tendons situated towards the posterior part of the arti- 
 culation. 
 
 The flexor muscles have, therefore, fibres of greater length, and 
 more numerous, than those of the extensors. They are inserted into 
 the bones at a greater distance from the centre of their motion, at an 
 angle less acute, and which increases in size as the limbs bend. The 
 union of these causes gives to the limbs their superior power ; and the 
 greater range of motion in these muscles is a consequence of the 
 arrangement of the articulating surfaces, which almost all incline 
 towards the side of flexion. 
 
 This preponderance of the flexor muscles varies according ip the 
 different periods of life : in the foetus, the parts are all bent very con- 
 siderably. This convolution of the young animal may be perceived from 
 the earliest period of gestation, when the embryo, of the size of a 
 French bean, and suspended by the umbilical cord, floats in the midst 
 of the liquor amnii, in a cavity of which it is more and more confined 
 as it approaches to the period of its birth. This excessive flexion of 
 the parts, which was required to enable the produce of conception to 
 accommodate itself to the elliptical shape of the uterus, concurs in 
 giving to the muscles producing it the superiority which they retain 
 during the remainder of life. 
 
 The new-born child preserves, in a very remarkable manner, the 
 habits of gestation ; but, in proportion as it grows, it straightens its 
 body, and, by frequent attempts to stretch itself, shews that a just 
 proportion is about to take place between the muscular powers. 
 When the child becomes capable of standing erect, abandoned to its 
 own powers, all its parts are in a state of semi-flexion, it staggers, 
 and is unsteady on its feet. Towards the middle of life the prepon- 
 derance of the flexors over the extensors becomes less apparent a 
 man enjoys fully and completely his power of locomotion; but, 
 as he advances in years, this power forsakes him ; the extensor 
 .muscles gradually return to the state of comparative debility of infancy, 
 and become incapable of supporting the body in a fixed and permanent 
 manner. 
 
 CLXVII. Pathological physiology of muscular action, The state 
 of our limbs during sleep approaches to that of the foetus, which, 
 according to Buflfon, may be considered to be in a profound slumber. 
 The cessation of sleep is attended in man, as well as in most animals, 
 by frequent stretchings. We extend our limbs forcibly, to give to the 
 extensors the tone which they require during the state of waking.* 
 
 * Haller thinks 'that these extensions are intended to relieve the uneasy sensa- 
 tions occasioned by a long-continued flexion. " Nunc quidem homities et animalia
 
 378 OF MUSCULAR ACTION*. 
 
 Barthez accounts in the same way for the manner in which the cock 
 announces his waking, by crowing and flapping his wings. 
 
 It may happen, in consequence of a morbid determination of the 
 vital principle, that our limbs may remain in a state of extension 
 during sleep. Hence Hippocrates recommends that the state of the 
 limbs be carefully attended to while the patient sleeps ; for, as he ob- 
 serves, the farther that condition is From the natural state, the greater 
 the danger to be apprehended of the patient's life. In certain nervous 
 diseases, characterised by a manifest aberration in the distribution of 
 the vital power, a continued state of extension must be considered a 
 symptom highly dangerous. I have had several times occasion to 
 observe, that in cases of wounds attended with convulsions and tetanus, 
 these alarming affections were announced by the permanent extension 
 of the limbs during sleep, before a difficulty of moving the jaw could 
 give rise to any apprehension of their approach. 
 
 Disease, and excesses of all kinds, occasion in the extensor muscles 
 a relative weakness that is very remarkable : hence we see convalescents, 
 and those who have been addicted to voluptuousness, walk with bend- 
 ing knees ; the more so as their debility is greater, and as the force of 
 the extensors is more completely exhausted. The flexion of the knees is 
 then limited by that condition in which the tendons of the extensors of 
 the leg act on the tibia, at an angle sufficiently great to make up for 
 their diminished energy. There exists a condition of the animal 
 economy in which all the muscular organs appear wearied with 
 exertion, and the limbs assume indifferently any position. In this 
 state, which is always a very serious one, as it indicates an almost 
 complete want of action in a system of organs whose functions are 
 absolutely essential to life a state to which physicians have given the 
 name of prostration* the limbs, if unsupported, fall of their own 
 weight, as if they were palsied, the trunk is motionless and supine, 
 the patient is incapable of changing his attitude, and, yielding to the 
 
 extendunt artus, quod Us fere conflexis dormiant, et ex eo perpetuo situ, in musculis 
 sensus incommodus oriatnr, quern extensione tollunt" (Phainomena expergiscen- 
 tium, Elementa Physiologic torn. v. p. 621). 
 
 * It is from a knowledge of the strength of his patient that the physician, in 
 the treatment of disease^ deduces the most instructive indications. It seems to me, 
 that we ought to endeavour to characterise by specific terms the different states of 
 animal adynamia in different diseases. Our language, less fruitful in imagery than 
 the ancient languages, will not easily furnish these characteristic denominations, 
 so useful in a science which should paint objects in their truest colours, in terms 
 most approaching to nature. It will, therefore, be necessary to have recourse to 
 the Greek and Latin languages, and perhaps to give the preference to the latter, 
 which is generally understood by those who practise the art of healing. The 
 application of this principle to the different kinds of fever will prove its utility,
 
 OF THE PQWEH OF MUSCLES, 379 
 
 weight of his body, sinks on the inclined plane formed by the bed, 
 and seems very heavy to those who may attempt to raise him, be- 
 cause, from his helplessness, he requires to be moved as an inert 
 substance. 
 
 CLXVIII. Of the power of the muscles, and of the mode of esti- 
 mating that power. The actual power of the muscles is immensely 
 great, seems to grow in proportion to the resistance which it meets 
 with, and can never be estimated with precision. Borelli was guilty of 
 a serious mistake in estimating the' force of a muscle by its weight 
 compared to that of another muscle ; for muscles may contain cellular 
 tissue, fat, tendinous parts, and aponeuroses, without being the more 
 powerful. Their strength is always proportioned to their fleshy fibres ; 
 hence Nature has multiplied those fibres in the muscles which are 
 intended for powerful action. And in order that this great number of 
 muscular fibres might not add too much to the bulk of the limbs, they 
 are made shorter, by bringing near to each other their insertions, which 
 occupy extensive surfaces, whether aponeurotic or osseous. We may, 
 
 and will doubtless be an inducement to extend it to all the classes of morbid de- 
 rangements. 
 
 In febre inflammatoria seu synocho simplici (angeiotenica) Oppressio virium. 
 
 In febre biliosa seu ardente (meningo-gastrica) Fractura virium. 
 
 In febre pituitosa seu morbo mucoso (adenomeningea) Languor virium. 
 
 In febre putrida (adynamica) Prostraiio virium. 
 
 In febribus malignis seu atactis Ataxia virium. 
 
 In febre pestilential! (adeno-nervosa) Sideratio virium. 
 
 The first term, which is easily turned into French, expresses, with much preci- 
 sion, that condition in which the living system, far from being deficient in strength, 
 is encumbered by its excess, and is oppressed by its own powers. It might, with 
 slight modifications, be applied to all the kinds of phlegmasias and active 
 haemorrhages. 
 
 The second denomination, not so easily translated, expresses the sense of general 
 contusion and bruise, of which patients labouring under bilious fever (meningo- 
 gastrica) complain all over the limbs. 
 
 This sensation is likewise, it is true, experienced in pituitary fever ; but this is 
 more particularly characterised by languor and loss of strength. The same is to be 
 observed in many patients of a phlegmatic temperament. 
 
 The prostration, which is so remarkable a character of putrid fevers, and in 
 consequence of which they are called adynamic, is easily recognised by the total 
 cessation, or by an impaired condition of all the function^ performed by mus- 
 cular organs, as voluntary motion, respiration, circulation, digestion, the excretion 
 of urine, &c. 
 
 The disordered condition of the vital powers characterises the ataxiae. There 
 is considerable irregularity in these fevers, with a very anomalous course of 
 Symptoms. In this point of view, one might compare it to several kinds of nervous 
 disorders. 
 
 Lastly, the word eyderation appears to me to express very forcibly that sudden 
 and deep stupor which overwhelms patients seized with the plague of the East.
 
 380 OF THE roWEtt OF MUSCLES. 
 
 in general, judge of the power of a muscle by the extent of the surfaces 
 to which its fleshy fibres are attached ; thus, the gemelli and the soleus 
 have short compressed fibres, and lying obliquely between two large 
 aponeuroses. 
 
 If the force with which a muscle contracts is proportioned to the 
 number of its fibres, the degree of decurtation of which it is capable, 
 and consequently the range of motions which it can communicate to 
 the limbs, are proportioned to the length of the same fibres.* Thus 
 the sartorius, whose fibres are longer than any in the human body, is 
 also capable of most contraction, and performs the most considerable 
 motions of the leg. It is impossible to fix any precise limits to the 
 decurtation of every particular muscular fibre ; for, if the greater part 
 of the long muscles of limbs lose little more than a third of their 
 length in contracting, the circular fibres of the stomach, which in its 
 greatest dilatation form circles nearly a foot in diameter, may 
 contract to such a degree, when this organ has been long empty, as to 
 form rings of scarcely an inch in circumference. In cases of extreme 
 elongation or constriction, does the change that takes place affect the 
 molecules that form the muscular fibre, or the substances which 
 connect them together ? or does it affect at once both the fibre and the 
 parts by which these fibres are united together ? 
 
 However great the power of the muscles may be, a great part of 
 this power is lost from the unfavourable disposition of our organs 
 of motion : the nuiscular powers, almost always parallel to the bones 
 which they are to move, act with the more disadvantage on these 
 levers, as the mean line of their direction is further from the per- 
 pendicular, and is nearly parallel to them. 
 
 The greater part of the muscles are, besides, inserted in the bones 
 very near their articulations, or the centre of motion, and move them 
 as levers of the third kind, that is, are always placed between the 
 fulcrum and the resistance : by multiplying thus, in the animal 
 machine, the levers of the third kind, Nature has lost in power, but 
 has gained in strength, for in this kind of lever the power moves 
 through a very small space, but makes the resistance move through 
 a very considerable, one. Moreover, the fleshy fibres, in shortening 
 themselves, do not act directly on the tendon in which the muscle 
 terminates: these fibres generally join, in an oblique direction, the 
 aponeurotic expansion formed by the tendinous cord, as it penetrates 
 
 * Besides these data, we should take into consideration the energy of the nervous 
 impulse under which voluntary muscles contract. We perceive nearly as great 
 differences in the activity, the intensity, the frequency, and in the continuance of 
 muscular contraction, result from the state of the nervous system, even in health, 
 as may be imputed to the form and size of the muscles themselves, unless the dif- 
 ference of their constitution or size be very considerable. J. C.
 
 OF THK POWKR OF MUSCLES. 381 
 
 into the muscular mass. Now their action being exerted in a direction 
 more or less oblique, is decomposed, and none is advantageously 
 employed but that which takes place in the direction of the tendon. 
 The muscles frequently pass over several articulations in their way to the 
 bone which they are to move ; and hence a part of their power is lost, in 
 the different degrees of motion on each other, of the parts on which 
 the bone into which the muscles are inserted rests. All these organic 
 imperfections are attended with an enormous misapplication of power, 
 and with a waste of the greater part of it. It has been reckoned that 
 the deltoid muscle employs a power equal to 2568 pounds to over- 
 come a resistance of 50. We are not to imagine, however, that there 
 is a loss of 2518 pounds; for the deltoid muscle acting both on the 
 shoulder and on tho arm, about one-half of its power is employed on 
 each of these parts ; hence it is said, that in estimating the whole 
 power of a muscle, one should double the effect produced by its 
 contraction, its action being employed at the same time both on the 
 weight which it raises, or on the resistance which it overcomes, and 
 on the fixed point to which its other extremity is inserted. 
 
 If the muscles were quite parallel to the bones, they would be 
 incapable of moving them in any direction. On this account Nature 
 has, as much as possible, corrected the parallelism by removing, as we 
 shall see in speaking of the osseous system, the tendons from the 
 middle line of direction of the bones, and by augmenting the angles at 
 which they are inserted into them, either by placing along their course 
 bones which alter their direction, as the patella and the sesamoid 
 bones, by increasing the size of the articular extremities of the bones, 
 or by pullies, over which the tendons or the muscles themselves are 
 reflected, more or less completely, as in the case with the circum- 
 flexus palati and the obturator internus. 
 
 Nature has not, therefore, neglected mechanical advantages as 
 much as one might be led to imagine on a slight examination of the 
 organs of motion. And if it be considered, that in the different 
 conditions of life we do not require strength so much as rapidity of 
 motion, that the power might be gained by increasing the number of 
 fibres, while it was impossible to obtain velocity by any other means 
 than by employing a particular kind of lever, and that, in short, to 
 give our limbs the most advantageous form, it was necessary that the 
 muscles should be applied to the bones, it will be confessed, that in 
 the arrangement of these organs, Nature, in frequently sacrificing 
 power to quickness of motion, has conciliated, as much as possible, 
 .these two almost irreconcileable elements. 
 
 Though the lever of the third kind is that most frequently em- 
 ployed in the animal economy, the two other kinds of lever are not 
 altogether excluded from it: there are even limbs which represent
 
 382 OF THE POWER OF MUSCLKS. 
 
 different levers, according to the muscles which set them in motion ; 
 thus, if we take the foot as an instance, it will present us with levers of 
 every kind. The foot, when raised from the ground, and held up, and 
 directed in the axis of the leg, forms a lever of the first kind ; the ful- 
 crum is in the articulation, and separates the power, which is at the heel, 
 from the resistance, which is at the tip of the foot that points down- 
 wards : if this end of the foot rest <5n the ground, and if we stand on 
 tip-toe, they are changed into levers of the second kind ; the power 
 continues at the heel, but the fulcrum is removed to the other 
 extremity of the lever, and the resistance to the middle ; and this 
 resistance is very considerable, since the whole weight of the body 
 rests on the articulation of the foot with the leg. In standing on 
 tip-toe, the muscles of the calf of the leg become prodigiously 
 fatigued, though their action is assisted by the most favourable lever,* 
 adapted to the greatest resistance which Nature can oppose to herself. 
 Lastly, the foot moves as a lever of the third kind when we bend it on 
 the leg. 
 
 CLXIX. Of the fixed point, or fulcrum, in muscular action. 
 What is called the fixed point, in the action of muscular organs, does 
 not always deserve that name. Thus, though it may be said very 
 correctly, that the greater part of the muscles of the thigh have their 
 fixed point in the bones of the pelvis, to which their upper extremity 
 is attached, and though they move the femur on the ilia, which are 
 less movable, when the thigh is fixed by the action of other muscles, 
 these move the pelvis on the thigh, and that which was the fixed 
 point becomes movable. The same applies to the other muscles of 
 the body, so that the fixed point is merely that which generally is a 
 fulcrum to the muscular action. This necessary fixed state of one of 
 the bones, to which is attached one of the extremities of a muscle 
 which we wish to contract, renders it necessary, in performing the 
 slightest motion, that several muscles should be called into action, 
 which implies a very complicated mechanism. Nothing is easier to 
 prove. Suppose a man stretched on the ground, or lying on his back, 
 if he wish to raise,his head, it will be necessary that his chest become 
 the fixed point of action of the sterno cleido mastoidei, whose office it 
 is to perform this motion. Now, in order that the pieces forming this 
 osseous structure may remain motionless, it will be required that the 
 chest should be fixed by the action of the abdominal muscles, which, 
 on the other hand, have their fixed point in the pelvis, that is itself 
 fixed in its place by the contraction of the gluteei muscles. It was on 
 this principle that Winslow first suggested, that in reducing a hernia, 
 
 * Of levers with arms of unequal length, that of the second kind is the most 
 favourable, since the arm of the power is uniformly longer than that of the 
 resistance.
 
 THE MUSCULAR FLESH. 38S 
 
 the patient should be laid in a horizontal posture, with injunctions 
 not to raise his head, that the abdominal muscles being relaxed, their 
 different openings might yield more easily to the reduction of the 
 parts. 
 
 In case the two opposite points to which the extremities of a 
 muscle are attached, are equally movable, they approach towards each 
 other during the contraction of the muscle, by making them move 
 through equal spaces. These spaces would not be equal if the 
 mobility were different. Each muscle has its antagonist, that is, 
 another muscle whose action is directly opposed to it. Thus the 
 flexors balance the action of the extensors, the adductors perform 
 motions different from those of the abductors. When two antagonising 
 muscles of equal power act, at the same time, on a part equally 
 movable in every direction, the opposite powers neutralise each other, 
 and the part remains motionless. If there is a difference in the degree 
 of contraction, the part is directed towards the muscle whose con- 
 traction is the most powerful ; if the opposition is not direct, the part 
 follows a middle direction, between the two powers which move it. 
 Thus the rectus externus muscle of the eye is not antagonised by the 
 rectus inferior : hence when these two muscles come to contract at the 
 same time, the eye is not carried downward or outward, but at once 
 downward and outward ; it is then said to move in the diagonal of a 
 parallelogram, of which the sides are represented by the muscles in 
 action. 
 
 CLXX. Of the nature of muscular flesh. I shall not speak at 
 present of the manner in which the muscles receive nourishment, by 
 retaining within the meshes of their tissue the fibrina, which the blood 
 conveys to them in such quantity, that several among the ancients and 
 moderns have called the blood, " liquid flesh;" an expression at once 
 forcible and correct, since all the organs are repaired and grow by the 
 solidification of its different parts. Haller first observed that most of 
 the muscular arteries were very tortuous in their course to the muscles. 
 This disposition, which cannot fail to slacken very considerably the 
 course of the blood, favours the formation and the secretion of the 
 fibrous element which the muscles appropriate to their own substance, 
 and to which it bears so strong an affinity. Motion influences, in a 
 very remarkable manner, this nutritive secretion. The muscles that 
 are most in action uniformly acquire the greatest size and strength ; 
 if lert in a state of complete inaction, they become exceedingly 
 reduced in size, from the suspended secretion of the fibrinous principle. 
 Muscular motion promotes very remarkably the circulation and the 
 distribution of all the fluids. The flow of venous blood, after 
 bleeding, is never copious, unless the muscles of the fore-arm are
 
 384 OF GALVANISM. 
 
 made to contract, by allowing the patient to hold the lancet case, and 
 desiring him to move it round in his hand. 
 
 The chemical nature of the muscular fibre is nearly the same as that 
 of the fibrine obtained from the blood*. Like the latter, it contains 
 a great quantity of azote, and is, consequently, very much animalised 
 and exceedingly putrescent. It was from muscular flesh that M. Ber- 
 thollet obtained, in considerable quantity, the peculiar animal acid, 
 called by that chemist the zoonic acid f. Lastly, the element of the 
 blood, fibrine, by means of which the muscular flesh is repaired, is 
 already imbued with vital properties, even while it yet flows in a state 
 of combination with the other parts of the fluid. This fibrine, ex- 
 tracted from the blood and subjected to the galvanic influence, is 
 distinctly seen to quiver and contract under that influence. At what 
 period does this substance acquire the power of contracting ? It is, 
 doubtless, at the moment when it becomes organised, in passing from 
 the liquid to the solid state. What relation does there exist between 
 the organisation of matter and the vital properties with which it is 
 endowed ? This question cannot be answered in the present state of 
 our physiological knowledge. J 
 
 CLXXI. Of galvanism. A professor of anatomy in the university 
 of Bologna, Galvani, was one day making experiments on electricity. 
 In the laboratory, not far from the machine, lay some skinned frogs, 
 of which the limbs were convulsed every time a spark was taken. 
 Galvani, struck with the phenomenon, made it a subject of inquiry, 
 and found that metals, applied to the nerves and to the muscles of 
 these animals, determined quick and strong contractions when they 
 were disposed in a certain manner. He gave the name of animal 
 electricity to this set of new phenomena, from the analogy he thought 
 he perceived between its effects and those of electricity. The discovery 
 was made public : many scientific men, chiefly those of Italy, and 
 
 * Nothing can prove, in a more complete manner, the essential difference be- 
 tween the fleshy parts of muscles and their tendinous and aponeurotic parts, than 
 the chemical analysis of these organs. The tendons and aponeuroses may be 
 completely resolved into gelatine by long boiling, which, on the contrary, parches 
 the muscular flesh, by exposing the fibrina, in consequence of the melting of the 
 fat of the cellular tissue, and of the albuminous juices in which it is enveloped. 
 See the chapter at the end of the APPENDIX, on the Chemical Constitution of the 
 Animal Textures and Secretions J. C. 
 
 f Another principle which is obtained alnindantly from muscular tissues, and 
 denominated osmazome by modern chemists, may be noticed. It appears to be a 
 species of animal extract, of a brown colour, aromatic and very nutritious. It 
 gives soup its savour, and forms a great proportion of the gravy of meat. Although 
 osmazome is an animal product, it is also found on analysis in some species of 
 mushrooms J. C. 
 
 See APPENDIX, Notes 1 1.
 
 OF GALVANISM. 385 
 
 Volta among others, were eager to make additions to the labours of 
 the inventor. The Medical Society of Edinburgh thought it right to 
 take this point of physiology as the subject of one of its annual prizes, 
 which was adjudged to the work of Professor Creve, of Mentz, in 
 which the term metallic irritation (irritamentum metallorum) is sub- 
 stituted for that of animal electricity. This new expression is essen- 
 tially bad, since it implies that irritation by metals can alone determine 
 the galvanic phenomena, when charcoal, water, and many other sub- 
 stances, produce them as well. The term of animal electricity has 
 been also laid aside, notwithstanding the great analogy between the 
 effects of electricity and those of galvanism, and this last name has 
 been preferred, which, applying equally to the whole of the phenomena, 
 immortalises the name of the first observer.* 
 
 To produce the galvanic phenomena, it is necessary to establish a 
 communication between two points of a series of nervous and muscular 
 organs. In this way there is formed a circle, of which one arc is 
 composed of the animal parts that are subjected to the experiment ; 
 while the other arc is represented by the instruments of excitation, 
 which consist commonly of several pieces, some of them placed under 
 the animal parts, and called supports, and the others by which the 
 communication with these is established, called communicators. 
 
 To form a complete galvanic circle, take the thigh of a frog stripped 
 of its skin, detach the crural nerve down to the knee, and apply it on 
 a plate of zinc ; let the muscles of the leg lie on a plate of silver, then 
 complete the arc of excitation and the galvanic circle, by establishing 
 a communication between the two supports with an iron wire, or 
 copper, tin, or lead ; at the moment of touching the two supports with 
 the conductor, a part of the animal arc formed by the muscles of the 
 leg will be convulsed. Although this arrangement of the animal parts, 
 and of the galvanic instruments, is the one most favourable to the 
 production of these phenomena, there is room for varying a good deal 
 
 * Sulzer, in the Memoirs of the Academy of Berlin, and in his " General 
 Theory of Pleasure," a work published in 1757, and inserted, in 1769, in a collec- 
 tion published by Bouillon, under the title of the " Temple du Bonheur," tome iii. 
 p. 124, had mentioned, that two plates of different metals being placed one above 
 and another below the tongue, and inclined towards each other at their extremities, 
 at the moment when they touched each other, he felt a sharp taste, which was fre- 
 quently accompanied by a peculiar faint light. Cotuqno had related, in a journal 
 published at Bologna, in 1786, that a student f>f medicine, while dissecting a living 
 mouse, was surprised to observe an electric movement of its limbs whenever the 
 scalpel touched one of the nerves. It was not until 1789 that Galvani commenced 
 his experiments. But he cannot be the less considered as the discoverer of this 
 class of phenomena, even supposing that he knew the experiments we have noticed, 
 for their authors drew no conclusion from them ; while, on the contrary, Galvani 
 repeated,'varied, and multiplied them, and was the first to contend for a species of 
 electricity in the animal economy. 
 
 C C
 
 386 OF GALVANISM. 
 
 the composition of the animal arc and the arc of excitation. Thus, 
 you obtain contractions by placing the two supports under the nerve, 
 and leaving the muscles without the galvanic circle ; which proves 
 that the nerves essentially constitute the animal arc. To conclude, the 
 galvanic circle may be entirely animal : for this purpose take a very 
 lively frog, that is to say, one enjoying strong contractility : after 
 insulating the lumbar nerves, present these nerves to the thigh of the 
 frog : at the moment of contact the limb will be convulsed. Pro- 
 fessor Aldini was the first author of this experiment, which is really one 
 of the most curious, as it leads more directly to the explanation of the 
 influence of nerves on muscular organs. 
 
 There is no need that the nerves be untouched to allow the con- 
 tractions to take place ; they are observed when the nerves are tied or 
 cut, provided there be simple contiguity between the two ends made by 
 the section. This shews that no rigorous conclusion should be drawn 
 from what happens in galvanic phenomena to what takes place in mus- 
 cular action, since it is enough that a nerve in man be cut or compressed 
 by a ligature, to take from the muscles to which it is sent the faculty 
 of moving. I have, however, observed that disorganising, by a strong 
 contusion, the nerve which forms the whole or merely a part of the 
 animal arc, interrupts, or at least greatly impedes, the galvanic current. 
 
 The epidermis obstructs galvanic action, which always is faint in 
 parts so covered. When it is moist, thin, and delicate, the interrup- 
 tion is not complete, and hence the possibility is inferred of making on 
 oneself the following experiments. 
 
 Lay upon the tongue a plute of silver, and a plate of zinc beneath ; 
 let their edges touch, and you will feel a sharp taste, with a slight 
 quivering. Apply upon the eyes two pieces of different metals ; make 
 them communicate, and you will perceive sparks. Put a piece of 
 silver in your mouth, and a piece of tin into your anus, or copper, or 
 any other metal ; connect them with an iron wire ; the long, hollow 
 muscle, which, reaching from the mouth to the anus, forms the base of 
 the digestive canal, feels a considerable shock : this has been carried 
 the length of exciting a gentle purging, accompanied with slight 
 cholic. Humboldt, after detaching the epidermis from the nape of 
 the neck and the back, by two blisters, had metals applied to the parts 
 laid bare, and felt in each sharp prickings, accompanied with a sero- 
 sanguineous excretion, at the moment of communication. 
 
 You may construct the arc of excitation with three kinds of metal, 
 or two, or even one, with alloys, amalgams, or other metallic and 
 mineral combinations, with carbonaceous substances,* &c. ; and it is 
 
 * I employed successfully, in the winter of the year 1800, pieces of ice, both as 
 supports and as communicators.
 
 OF GALVANISM. 387 
 
 observed that metals, which are in general the most powerful exciters, 
 provoke contractions with the greater success the larger surface they 
 present. The metals have more or less power of excitation : thus, it is 
 found that zinc, gold, silver and tin, hold the first rank ; then copper, 
 lead, nickel,^ antimony, &c. without any apparent relation between 
 their different degrees of exciting power and their physical properties, 
 as their weight, -malleability, &c. 
 
 Galvanic susceptibility is like muscular irritability : it is exhausted 
 by too long exertion, and returns when the parts are left for a time in 
 repose. Dipping the nerves and muscles in alcohol or opiate solutions, 
 weakens, and even will extinguish this susceptibility, in the same man- 
 ner, no doubt, as the immoderate use of the same substances benumbs 
 and paralyses 'the muscular action in the living man. Immersion 
 in oxygenated muriatic acid restores to the exhausted parts the power 
 of being affected by the stimulus. Humboldt has observed that the 
 season of spring, as well as the youth of the frog, was favourable to 
 the production of the phenomena, and that the fore feet of these 
 creatures, with which the male fixes himself on the back of the female, 
 by pressing her sides, are more excitable than the hind feet ; whilst in 
 the other sex, it is the hind feet that are the most susceptible. M. 
 Halle ascertained, by experiments made at the School of Medicine in 
 Paris, that the muscles of animals killed by repeated shocks of an 
 electrical battery, receive an increase of galvanic susceptibility; that 
 this property subsists, without alteration, in animals dead from asphyxia, 
 or killed by immersion in mercury, pure hydrogen gas, carbonated 
 hydrogen, oxygenated muriatic acid, and sulphureous acid gases, by 
 strangulation, or by privation of air in an exhausted receiver; that it is 
 weakened after suffocation by drowning, by sulphuretted hydrogen, 
 azote, and ammoniacal gas; and absolutely destroyed by suffocation in 
 the vapour of charcoal. Spring is the season in which galvanic ex- 
 periments succeed best: an excess of life seems, at that time, to animate 
 all beings ; it is, accordingly, at this epoch that the greater part of 
 them are employed in the reproduction of their kind. 
 
 CLXXII. Galvanic susceptibility disappears in the muscles of 
 warm-blooded animals as the vital warmth goes off. Sometimes even 
 when their life has ended in convulsions, their contractility is gone, 
 though there be still warmth, as if this vital property were exhausted 
 by the convulsions of death. In the cold-blooded, susceptibility is 
 more permanent : long after separation from the body, and even to the 
 moment when putrefaction begins, the thighs of frogs are affected 
 by galvanic excitation ; no doubt because in these animals irritability 
 is less intimately connected with respiration, because life is less one, 
 is more divided among different organs which have less need of action 
 on each other to produce its phenomena.
 
 388 GALVANIC SUSCEPTIBILITY. 
 
 Contractility is, tlien, as I have shewn in another work, too fleeting 
 in the human body * to enable us to derive from galvanic experiments 
 on it after death, any light on the greater or less weakening of this 
 vital property in different diseases. Those authors who have main- 
 tained that galvanic susceptibility is sooner extinct on the bodies of 
 those that die of scorbutic affections, than of those that die of inflam- 
 matory diseases, have suggested a probable conjecture, which cannot, 
 however, be established on experiment. 
 
 Dr. PfafF, professor in the university of Kiel, who, next to Hum- 
 boldt, is, of all the scientific men of Germany, he who has attended 
 most successfully to experiments on galvanism, has had the goodness 
 to communicate to me the following facts. 
 
 The galvanic chain produces sensible actions, that is to say, con- 
 tractions, only at the moment in which it is completed, by establishing 
 a communication among its parts. After the communication is made, 
 or during the time* that it remains, all appears tranquil ; yet the 
 galvanic action is not suspended. In fact, excitability appears sin- 
 gularly increased or diminished in the muscles that have been left long 
 in the galvanic chain, according to the variations of the reciprocal 
 situation of the associated metals. If the silver have been applied to 
 the nerves, and the zinc to the muscles, the irritability of these is 
 increased in proportion to the time they have remained in the chain. 
 By this means you may revivify, in some sort, frogs' thighs, which 
 will afterwards obey an influence that was no longer sufficient to 
 excite them. By allotting the metals differently, applying the zinc to 
 the nerves, and the silver to the muscles, the opposite effect takes 
 place ; the muscles, which were introduced into the chain with the 
 liveliest irritability, seem entirely paralysed, if they have remained long 
 in that situation. 
 
 This difference depends, very evidently, on the direction of the 
 galvanic fluid determined towards the nerves or towards the muscles, 
 according to the arrangement of the metals. It is of importance to 
 be known for the application of galvanism to the treatment of disease. 
 Where the object is to revive enfeebled irritability, it is better to em- 
 ploy the tranquil and permanent influence of the closed galvanic chain, 
 by distributing the silver and zinc so that the silver shall be nearest 
 to the origin of the nerves, and the zinc upon the muscles of which it 
 is wished to re-excite the torpid or suspended action, than to employ 
 that sudden influence, which in an instant excites, and is gone. Pro- 
 fessor Pfaff told me he had treated successfully a hemiplegia, by 
 placing silver within the mouth, and a plate of zinc on the paralysed 
 
 * It ceases in the foetus, and in the new-born, or very young infant, almost im- 
 mediately with life. J. C.
 
 APPARATUS OF VOLTA. 389 
 
 arm : at the end of twenty-four hours of uninterrupted communication 
 the limb could already exert some slight motions. To diminish, on 
 the other hand, the irritable energy in many spasmodic affections, you 
 must invert the application of the metals ; place the zinc as near as pos- 
 sible to the central extremity of the nerves, and the silver on their 
 superficial terminations. 
 
 CLXXIII. Apparatus ofVolta, or galvanic pile. Curious to ascer- 
 tain the relation apprehended by several natural philosophers to subsist 
 between electricity and galvanism, M. Volta invented the following ap- 
 paratus, which is described, as well as the effects it produces, in a memoir 
 presented by him to the Royal Society of London. These effects shew 
 the most striking analogy between the two orders of phenomena, as 
 will be seen by a succinct view of them. Raise a pile by laying, suc- 
 cessively, one above another, a plate of zinc, a piece of moistened paste- 
 board, and a plate of silver ; then a second plate of zinc, &c. till the pile 
 is several feet high for the effects are stronger the higher it is ; then 
 touch at once the two extremities of the pile with the same iron wire : 
 at the instant of contact a spark is seen at the extremities of the pile, 
 and often, at the same time, luminous points, at different heights, in 
 places where the zinc and silver touch. Tried by the electrometer of 
 M. Coulomb, the extremity of the pile which answers to the zinc 
 appears positively electrified ; that which is formed by the silver, 
 gives, on the contrary, indications of negative or resinous electricity. 
 
 If, after wetting both hands by dipping them in water, or, still 
 better, in a saline solution, you touch the two extremities of the pile, 
 you feel a shock in the joints of the fingers and elbow, followed by an 
 unpleasant pricking. 
 
 This effect may be felt by several persons holding hands, as in the 
 Leyden experiment : it is the more sensible, the composition of the 
 chain being in other respects the same, as the chain consists of fewer 
 people, and as they are better insulated. 
 
 Notwithstanding this great resemblance of the effects of galvanism 
 to those of electricity, it differs from it essentially in this, that the 
 voltaic pile is constantly electrifying itself spontaneously, that its 
 effects seem increased the more they are excited, and are speedily 
 renewed in greater strength ; whilst the Leyden phial, once discharged, 
 requires to be electrified anew. This loses, moreover, by damp, its 
 electrical properties, whilst those of the pile remain the same, though 
 water is running on all sides, and are quenched only by entire immer- 
 sion in that fluid. 
 
 If you introduce into a tube filled with water, and hermetically 
 closed with two corks, the extremities of two wires of the same metal, 
 which at the other extremity are in contact, one with the summit and
 
 390 GALVANIC ELECTRICITY. 
 
 the other with the base of the galvanic pile, these two ends, when 
 brought within the distance of a few lines, undergo manifest changes at 
 the moment of touching the extremities of the pile. The wire in contact 
 with the extremity which answers to the zinc, becomes covered with 
 bubbles of hydrogen gas; that which touches the extremity formed 
 by the silver, becomes oxydised. If the ends of the wire dipping into 
 the water are brought into contact, all effect ceases : there is no dis- 
 engaging of bubbles on one side, no oxydisement on the other. The 
 plates of zinc and silver become alike oxydised in the pile, but only on 
 the surfaces which touch the moistened pasteboard, and very little, 
 or not at all, on the opposite surfaces, &c. 
 
 Facts so singular could not but awaken the attention of all natural 
 philosophers. Accordingly, there was a great eagerness every where to 
 repeat and verify these first experiments, to vary and to extend them, 
 and to rectify the errors into which their authors might have fallen. 
 Lastly, it has been attempted to explain the manner in which the 
 apparatus acts in the production of hydrogen gas, and in oxydise- 
 ment. 
 
 M. Fourcroy ascribes this phenomenon to the decomposition of 
 water by the galvanic fluid, which abandons the oxygen to the wire 
 that touches the positive extremity of the apparatus, then conducts the 
 other gas, in an invisible manner, to the extremity of the other wire, 
 where it allows it to escape ; and this opinion, supported by many 
 experiments, detailed in a memoir presented to the National Institute, 
 is the most probable of all that have hitherto been suggested.* 
 
 The galvanic pile has been employed with effect to produce with 
 more energy muscular contraction. If you place in the mouth of 
 an animal fresh killed a conductor, attached to one of the poles or 
 extremities of the pile, and insert into the rectum the conductor con- 
 nected with the other extremity, you observe contractions so strong 
 that the whole body of the animal quivers and is agitated, the eyes 
 roll in their sockets, the jaws strike against each other, and the tongue 
 is thrust out. The same effects take place after decapitation of the 
 animal. These experiments have been repeated on the bodies of 
 persons executed by the guillotine: by applying to the neck the 
 head that had been separated from it, and applying to both, conductors 
 connected with the pile, effects have been produced which seemed at 
 first miraculous. There are few muscles that retain their sensibility 
 to the galvanic action longer than the diaphragm ; in the heart and the 
 intestines it is the same. I know not why the internal muscles have 
 been held by many authors to be insensible to this kind of excitation. 
 
 * It is unnecessary to refer to the brilliant discoveries which have been made iu 
 chemical science by meaiis of galvanism. J. C,
 
 
 MEDICAL USES OF GALVANISM- 391 
 
 I have seen them constantly obey it, and many experiments, made 
 publicly in my lectures, have always afforded me this result.* 
 
 CLXXIV. Nature and medical uses of galvanism. Since the pub- 
 lication of the early editions of this work, there has been an accession 
 of new facts to those already known. Volta came to Paris : he gave 
 an exposition of his doctrine in several memoirs read before the 
 National Institute of France, and he repeated before a committee 
 the principal experiments on which it is founded. They have ap- 
 peared so conclusive, that the theory of this illustrious philosopher 
 has been unanimously adopted ; and at this day all men of science 
 admit the entire identity of the phenomena of galvanism and those of 
 electricity. Certain bodies therefore in nature, and especially metals, 
 possess the property of electrifying themselves, that is to say, of 
 producing the greater part of the phenomena which denote the accu- 
 mulation of electricity in a body, such as shocks, sparks, irritations, 
 &c. merely by contact.f 
 
 It may be thought that galvanism, being only a new form of elec- 
 trical action, ought to be confined to books of natural philosophy ; 
 and in fact, in the present state of things, it belongs rather to the 
 physico-chemical sciences than to those of the animal economy. 
 However, the galvano-electric irritation produces on our organs effects 
 more decided than electricity. It seems to have more intimate rela- 
 tions with the animal economy ; accordingly, it has been endeavoured 
 to bring it into use in the treatment of disease. The experiments 
 made by MM. Halle and Thillaye prove, that the effects of the pile 
 penetrate and affect the nervous and muscular organs more deeply 
 than the common electrical apparatus ; that they provoke lively con- 
 tractions, strong sensations of pricking and burning, in parts which dis- 
 ease had rendered insensible to electrical sparks, or even shocks. A man 
 whose muscles of the left side of his face were all paralysed, found no 
 effect from the electrical shock. He was exposed to the action of a pile 
 of fifty plates, by communications through chains and metallic ex- 
 citers of the two extremities of the pile, with different points of the 
 cheek affected. At the moment of contact all the muscles of the face 
 became convulsed with heat, pain, &c. These endeavours, repeated 
 during more than six months, have, by degrees, brought back the parts 
 to their natural state. 
 
 Dr. Alibert has applied galvanism with still more decided success 
 
 * See the Note in the APPENDIX on the subject of Galvanism, for observa- 
 tions as to the effects of this agent on some of the animal textures J. C. 
 
 f- See APPENDIX, Notes K K, for an account of some recent views respecting 
 the Relations and Agencies of Galvanism, &c.
 
 392 EFFECTS OF GALVANISM. 
 
 to a priest attacked with hemiplegia. This patient, who lay in the 
 wards of the hospital of St. Louis, has recovered the use of the palsied 
 side sufficiently to walk, almost without assistance, and to use his 
 right arm as he wants it. The treatment has gone on for several 
 months: the pile employed consisted of fifty plates of zinc and copper. 
 I am trying the same apparatus upon a Swedish officer, for incom- 
 plete deafness, which has hitherto resisted all known applications 
 administered in different parts of Germany. Strong electrical shocks, 
 recommended by Hufeland, had dispelled, in great measure, the hard- 
 ness of hearing; but this amendment 'was only temporary: it ceased 
 with the application of the remedy. The first trial of galvanism was 
 attended with the same effect. The extremity of a conductor being 
 placed in the exterior auditory duct of the right side, (moistened with 
 a solution of muriate of ammonia, as well as the pieces of cloth which 
 made part of the pile,) the left hand, dipped in the same liquid, 
 touched a conductor placed at the copper pole ; immediately an irri- 
 tation, followed by painful prickings, was felt in the ear, the outer 
 part of which became very red. The brain partook in the excitement, 
 the eyes flashed, and the effect was such, that after remaining a few 
 minutes in the closed galvanic circle, the patient was taken^ with a 
 sort of inebriation. I propose to direct, as has been done at Berlin, 
 a more immediate irritation on the right ear, which is the deafest, 
 by introducing behind the velum pelati, on the guttural orifice of the 
 Eustachian tube, the button which is at the end of the conductor of 
 the zinc pole ; or else to make this extremity correspond with a de- 
 nuded surface, by a blister behind the diseased ear. 
 
 To use galvanism in paralysis of the bladder, it would be neces- 
 sary to place the conductor of the zinc pole in the rectum, that of the 
 other pole answering to a blister applied above the pubis, or else to the 
 upper part of the thigh. In women, the vagina would be preferable to 
 the rectum ; the soft tissues which perform the part of moist conductors 
 fulfilling that office the better the thinner they are. Galvanism is there- 
 fore an energetic stimulant of the vital powers ; it may be employed 
 with great advantage in all palsy, both of sensation and of motion. 
 It acts as a stimulant, reddening the skin where it is applied, by 
 determining thither the flow of blood, with heat. Monro could make 
 his nose bleed at pleasure, by applying it to the pituitary membrane. 
 I have made various experiments, having in view to establish the effi- 
 cacy of galvanism in white swelling of the joints, and in ulcers which 
 re*quire excitement, such as those which are attended with a scorbutic 
 affection, &c. : in all these cases it acts as a resolvent and as a tonic. 
 I shall communicate, in my Surgical ^osography, the results of these 
 attempts. Cases. of asphyxia are those in which the greatest good may
 
 THE OSSEOUS SYSTEM. 393 
 
 be hoped from galvanism, provided the application be made before all 
 the vital heat be extinct.* 
 
 Those who would wish fuller details on galvanism, and on its 
 possible application to the treatment of disease, will do well to consult 
 the Complete History of Galvanism, by Professor Sue ; the eulogium of 
 Galvani, by Dr. Alibert, in the beginning of the fourth volume of the 
 Memoirs of the Medical Society of Emulation ; and the work of Dr. 
 Aldini, nephew to the celebrated author of the discovery.f 
 
 CLXXV. General view of the osseous system. Man, as well as 
 the other red-blooded animals, (the mammiferse, birds, reptiles, and 
 fishes,) has an internal skeleton, formed of a great number of bones 
 articulated together, and set in motion by the muscles with which they 
 are covered. The white-blooded animals have no internal skeleton, 
 and are enveloped in hard, scaly, or stony parts, forming what is called 
 their outer skeleton. Some animals are entirely destitute of hard 
 parts : this is the case with the zoophytes, and some worms and insects. 
 The internal structure of bones is composed of nearly the same mate- 
 rials in all animals ; viz. gelatine and salts containing a calcareous 
 basis. The external skeleton of white-blooded animals bears a much 
 greater resemblance to the epidermis than to the osseous system of the 
 red-blooded animals. Like the epidermis, it undergoes changes of 
 decomposition and renovation. Thus, the lobster parts with its shell 
 every year, when the body of this crustaceous animal increases in size, 
 and it is replaced by a new envelope, which is at first very soft, and 
 which gradually acquires the same consistence as the former. Lastly, 
 the skeleton of birds differs from that of all other animals, in having 
 its principal bones pierced by openings communicating with the lungs, 
 and always filled with an air rarefied by the .vital heat, which greatly 
 assists in giving to them that specific lightness so essential to their 
 peculiar mode of existence. 
 
 The osseous system serves as a foundation to the animal machine, 
 yields a firm support to all its parts, determines the size of the body, 
 its proportion, its form, and attitude. Without the bones the body 
 would have no permanent form, and could not easily move from one 
 place to another. When, from the loss of the calcareous earth to which 
 
 * Dr. Philip is of opinion, that in those diseases in which the original cause 
 of derangement is in the nervous ramifications or spinal cord only, where the sen- 
 sorial functions are entire, and the vessels healthy, and the power of secretion is 
 alone in fault, galvanism will often prove a valuable means of relief. He has fre- 
 quently employed it in habitual asthma, " and almost uniformly with relief." He 
 also recommends this active agent in a torpid state of the biliary functions, and in 
 indigestion. See Treatise on Indigestion, third edition J. C. 
 
 -\- See APPENDIX, Notes K K, for some farther remarks respecting some of the 
 Physiological and Physical Relations of Galvanic Electricity J. C\
 
 394 OF THE BONES. 
 
 they owe their hardness, these organs become soft and the limbs de- 
 formed, standing and the different motions of progression become, after 
 a time, nearly impossible. Such are the effects of rachitis, a disease 
 of which the nature is well understood, though we are not the better 
 informed with regard to the manner in which its causes operate, or 
 as to the medicines requisite to its cure. 
 
 The vertebral column forms the truly essential and fundamental 
 part of the skeleton : it may be considered as the base of the osseous 
 edifice, as the point in which all their efforts terminate, as the centre 
 on which all the bones rest in their various motions, since every 
 effort or shock, in any way considerable, is felt there. Moreover, it 
 contains, in the-canal with which it is perforated, the cerebral prolon- 
 gation, which furnishes most of the nerves in the body. 
 
 In order that it may support all the different parts, and at the same 
 time protect the delicate organ which it contains,* and adapt itself 
 to the various attitudes required by the wants of life, it was necessary 
 that the vertebral column should possess, besides great solidity, a 
 sufficient degree of mobility : it possesses both these advantages, and 
 owes the former to the breadth of the surfaces by which its bones are 
 articulated together, to the size, the length, the direction, and the 
 strength of their processes, and to the great number of muscles and 
 ligaments connected with it ; and it owes its freedom of motion to the 
 great number of bones of which it is formed. Each single vertebra has 
 but a slight degree of motion; but as they all have the power of moving 
 at once, the sum of their individual motion added together, gives as 
 the result a general motion which is considerable, and which is esti- 
 mated by multiplying the single motion by the number of vertebrae. 
 
 The centre of the motions, by which tire spine is extended or bends 
 forward or backward, is not situated in the articulation of the oblique 
 processes, as is maintained by Winslow, in the Memoirs of the Aca- 
 demy of Sciences for the year 1730, nor in the intervertebral sub- 
 stance. The extension and flexion of the vertebree are not performed 
 on two centres of motion, the one in the intervertebral substance, 
 the other in the articulation of the articulating processes, as was 
 imagined by Cheselden and Barthez, but on an axis crossing the bone 
 between its body and its great aperture. The anterior part of the bone, 
 and its spinous process, perform, around this imaginary axis, motions 
 
 * The peculiar manner in which the vertebrae grow, is itself accommodated to 
 the delicacy of the spinal marrow ; consisting, for a considerable length of time, of 
 several pieces divided by cartilages, the circumference of the opening in these bones 
 becomes enlarged with the enlargement of the spinal marrow, as we grow older. 
 The circumference of the foramen of the occipital bone and that of the first vertebrae, 
 which correspond to the thickest part of the spinal marrow, is, on that account, 
 formed of four, distinct pieces separated by cartilages in the lirst of these bones, and 
 of live pieces in the other.
 
 OF THE BONES. 395 
 
 forming part of a circle, and which, though limited, are not the less 
 marked ; and in these motions the articulating surfaces, separated by 
 the intervertebral substance, are brought into close contact, and this 
 substance is compressed, while the oblique processes move on each 
 other, and tend to part from one another : this is what happens in 
 bending the trunk, while in straightening it, the anterior surfaces are 
 removed from each other, the posterior surfaces approach, come closer 
 and closer together, and finally touch throughout the whole of their 
 extent, when the extension of the trunk is carried as far as the spinous 
 processes will allow. 
 
 The use of the ridge of projections which arise from the posterior 
 part of the vertebree, is to limit the bending of the trunk backwards, 
 and to enable the muscles which straighten it to act with a more 
 powerful lever. When, from an habitually erect posture, these pro- 
 cesses have been prevented from growing in their natural direction, 
 the trunk may be bent backward to such a degree that the body 
 forms, in that direction, an arc of a circle. It is thus that they 
 train, from the earliest infancy, the tumblers who astonish us by the 
 prodigious suppleness of their loins, in bending backward so as to 
 change the natural direction of their spinal processes. 
 
 It was of consequence that the motions of the vertebral column 
 should take place at once in a great number of articulations, as the 
 curvatures are thus less sharp ; and hence the organisation of the 
 spinal marrow, which is very delicate, is not injured. The fibro-carti- 
 laginous substances which connect together the bodies of the vertebrse, 
 between which they lie, possess a remarkable degree of elasticity, like 
 all bodies of the same kind, and support, in a favourable manner, the 
 weight of the body. When the pressure which they experience is long 
 continued, they somewhat yield and diminish in thickness, and this 
 effect taking place at the same time in all the intervertebral substance, 
 our stature is sensibly lowered. The body is, on that account, always 
 shorter in the evening than in the morning ; and this difference may be 
 considerable, as is mentioned by Buffon to have been the case in 
 several instances. The son of one of his most zealous coadjutors, (M. 
 Gueneau de Montbeillard, to whom is due the greatest part of the 
 natural history of birds,) a young man of tall stature, five feet nine 
 inches when he had reached his complete growth, once lost an inch 
 and a half after spending a whole night at a ball. This difference in 
 the stature depends likewise on the condensation of the cellular adipose 
 tissue at the heel, which forms, along the whole of the sole of the foot, 
 a pretty thick layer. 
 
 The thigh bone is longer in man than in quadrupeds, and this 
 relative length of the thigh gives him exclusively the power of resting 
 his body by sitting.
 
 396 STRUCTURE OF BONES. 
 
 The tibia is the only bone of the leg which affords a support to 
 the body. The fibula, situated at its outer part, too thin and 
 slender to support the weight of the body, is of use merely with 
 regard to the articulation of the foot, on the outside of which it lies. 
 It supports the foot, and prevents its starting outward by too powerful 
 an abduction. The foot, in this motion, is forced against the fibula, 
 which is bent outwardly, the more so when the person is advanced in 
 years, and has, therefore, called into frequent action this force of re- 
 sistance. Animals that climb, as the squirrels, whose feet are in a con- 
 tinual state of abduction, have a very large and strongly curved 
 fibula.* 
 
 The number of the parts which form the feet, besides giving to these 
 parts a greater solidity, is further useful in preventing the foot from 
 being too violently shaken by striking the ground in our various mo- 
 tions of progression. In leaping from a height, we endeavour to fall 
 on our toes, that the force of the fall may be broken, by being com- 
 municated to the numerous articulations of the tarsus and the meta- 
 tarsus, and may not affect the trunk and head with a painful and even 
 dangerous concussion. It is well known, that when the whole sole of 
 the foot strikes against the ground in falls, fracture of the neck, of the 
 thigh bones, and concussion of the brain and other organs, is not an 
 unlikely consequence. 
 
 CLXXVI. Structure of the bones. Whatever difference there 
 may, at first sight, seem to exist between a bone and another organ, 
 their composition is the same. Its structure consists of parts that are 
 perfectly similar, with the exception of the saline inorganic matter 
 which is deposited in the cells of its tissue, giving it hardness and 
 that solidity which constitutes the most striking difference that dis- 
 tinguishes it from the soft parts. This earthy substance may be 
 separated by immersing the bone in nitric acid diluted in a sufficient 
 quantity of water. It is then found that it is a phosphate of lime, 
 which is decomposed by yielding to the nitric acid its calcareous base. 
 The bone, thus deprived of the principle to which it owes its consistence, 
 becomes soft, flexible, and resembles a cartilage, which is resolvable, 
 by long maceration, into a cejlular tissue similar to that of the other 
 
 * This curvature is well marked in the chefs-d'oouvre of antique sculpture, and 
 gives to the lower part of the leg, in our most beautiful statues, a thickness which 
 does not at all agree with our present notions of elegance of form. This seems to 
 me to prove that the beautiful is not invariable, as has been asserted by many 
 philosophers ; and that ideal perfection is not precisely the same in all ages, in 
 nations equally civilised. The truth of this observation may be proved by the 
 Apollo Belvedere : his knees are rather large and close together; and this form is 
 the most beautiful representation of Nature, which gives to the femur an obliquity 
 inwards, the knees not being perfectly straight, and without any disproportion be- 
 tween the calf and the thin part of the leg.
 
 STRUCTURE OF BONES. 397 
 
 parts. This tissue contains a pretty considerable number of arteries, 
 veins, and lymphatics. The bones are, therefore, mere cellular paren- 
 chymas, whose areolse contain a crystallised saline substance, which 
 they separate from the blood, and with which they become incrusted, 
 by a power inherent in their tissue, and peculiar to it. The same result 
 may be obtained by inverting the analysis. If a bone is exposed to 
 boiling heat, for a few hours, in Papin's digester, all its organised 
 parts become dissolved, melt, and furnish a quantity of gelatine, after 
 which there remains only an inorganic saline concretion, which may 
 likewise be obtained in a separate state by calcining the osseous part. 
 The different proportions of the saline to the organised part vary con- 
 siderably at different periods of life : the bones of the embryo are at 
 first quite gelatinous. At the period of birth, and during the first years 
 of life, the organic part of the bone is in greater proportion ; the bones 
 are less apt to break, more flexible, possessed of more vitality, and, 
 when fractured, are more speedily and more easily consolidated. In 
 youth, the two constituent parts are nearly in equal quantities; in 
 adults the calcareous earth* alone forms two thirds of the osseous 
 substance. At last, gradually increasing in quantity, it displaces in 
 old people the part that is organised; hence their bones are weaker, 
 more liable to fracture, and unite less readily. One may therefore say; 
 that the quantity of phosphate of lime deposited in the bones is in the 
 direct ratio of the age ; and that, on the contrary, the energy of the 
 vital faculties of these organs, their flexibility, their elasticity, their 
 aptitude to become consolidated when their continuity is destroyed by 
 accidents, are in an inverse ratio. 
 
 Anatomists distinguish in bones three substances, which they term 
 compact, spungy, and reticular. The first, which is the hardest, col- 
 lected in the centre of the long bones, where the greatest stress of the 
 efforts applied to their extremities rests, gives to the bone the strength 
 which it required. Its formation has been explained in various ways : 
 some have maintained that it owed its hardness to the pressure applied 
 to its middle part by the two extremities of the bone, in the same 
 manner as the stalk and the roots press against the collet^ of a plant. 
 Haller thinks it is caused by the pulsations of the nutritious arteries 
 which penetrate into the long bones at their middle part : why, then, is 
 their structure different at their extremities where they receive arteries 
 equally large and more numerous ? In the process of ossification, this 
 
 * By chemical analysis of the bones, there have been discovered several other 
 saline substances mixed with the phosphate of lime ; but as this salt alone consti- 
 tutes the greatest part of the substance which gives to the bones their hardness, it 
 has been particularly adduced. For an account of the Chemical Constitution of the 
 Osseous Texture, see the Chapter at the end of the APPENDIX. J. C. 
 
 -j- The part where the stem joins the root. T.
 
 398 STRUCTURE OF BONES- 
 
 substance appears first in the centre of the long bones ;* and this cir- 
 cumstance confirms the assertion of Kerkringius, who says, that our 
 long bones begin to ossify in those points where they have to resist the 
 greatest pressure. 
 
 The spungy substance is found within the short bones, and at the 
 extremities of the long ones, where its accumulation is attended with 
 two advantages, that of giving to the bone, without increasing its 
 weight, a considerable size, by which it may be articulated with the 
 neighbouring bones by wide surfaces, so as to give firmness to their 
 connexion : this conformation is attended with another advantage, that 
 of avoiding the parallelism of the tendons which pass over the joints, in 
 order to enlarge the angle of their insertion in the bones, and to give 
 more efficacy to muscular action. The mechanical hypotheses pro- 
 posed by Haller and Duhamel, to explain the formation of this spungy 
 substance, are very unsatisfactory, especially if it be considered, that in 
 the gelatinous bones of the embryo, the place that is to be occupied by 
 the spungy substance, viz. the extremities of the long bones, of which 
 the rudiments begin to appear, are larger than any other part. All the 
 cells of this spungy substance communicate with one another, they are 
 lined by a very fine membrane, and contain the medullary fluid. The 
 laminee, which cross each other in various directions, and which form 
 the parietes of the cells, become fewer in number, and thinner ; the 
 spungy tissue expands in approaching the middle part of the bones, 
 and forms (within the medullary canal of the compact substance) a 
 reticular tissue, the use of which is to support the membranous tube 
 containing the marrow. 
 
 These three substances, notwithstanding their unequal density, are 
 in reality but one and the same substance differently modified. The 
 reticular and spungy differ from the compact in containing less phos- 
 phate of lime, and in having a rarer and more expanded tissue. In 
 other respects, those changes in the osseous tissue which constitute the 
 laminated exostoses, the conversion of the bones by acids into a 
 flexible cartilage, which by maceration may be reduced into cellular 
 tissue, prove that these three substances are truly identical, and differ 
 from each other only by the degrees of closeness of their texture, and 
 the quantity of calcareous phosphate deposited in the meshes of their 
 tissue. 
 
 The compact substance appears to consist of concentric laminae, 
 strongly united together, and to be formed of fibres arranged longi- 
 tudinally, and in juxta-position. In proof of this arrangement, it is 
 usual to mention the exfoliation of bones exposed to the air; but these 
 laminae, detached from an exfoliating bone, merely prove that the 
 
 See APPENDIX, Notes L L.
 
 OF THE PERIOSTEUM. 399 
 
 action of the disease, the air, heat, or any other agent, by applying 
 itself successively to the different layers of bone, produces between them 
 a separation which did not exist in health, and determines their falling 
 off in succession. Certain parts, in which this lamellated structure 
 does not exist, may, in like manner, undergo the same kind of decom- 
 position. Thus, Lassone saw a piece of human skin, that had been 
 preserved for a considerable length of time in a vault, separate into 
 layers of extreme minuteness. 
 
 The vital principle which exists, in a smaller degree in the bones 
 than in other parts, seems to animate, to a certain extent, their dif- 
 ferent substances. Proportioned to the number of vessels which are 
 distributed to it, life is more active in the spungy tissue of the bones 
 than in their denser parts ; hence, in fracture of this part, fleshy gra- 
 nulations and callus form more quickly. Caries likewise advances 
 more rapidly, and it is more difficult to interrupt its progress. 
 
 CLXXVII. Of the uses of the periosteum and of the medullary 
 juices. Whatever be the situation, the size, the shape, and the com- 
 position of bones, they are all enveloped by the periosteum, a whitish, 
 fibrous, dense, and compact membrane, to which are distributed the 
 vessels which penetrate into their substance. The periosteum is a 
 membrane perfectly distinct from the other soft parts, and from the 
 bone itself, to which it adheres by means of vessels and of cellular 
 tissue, which pass from the one to the other the more closely as we are 
 more advanced in years. The cellular and vascular fibres that pene- 
 trate into the substance of the bone, establish a very close sympathetic 
 connexion between its periosteum and the very delicate membrane that 
 lines its internal cavity, which secretes the marrow, and is called the 
 internal periosteum. On destroying the internal medullary membrane, 
 by introducing a stilet within the cavity of the bone, its external layers 
 swell, are detached from the inner ones, and form, as it were, a new 
 bone around the sequestra. The new bone is not formed by the ossifi- 
 cation of the periosteum, as was maintained by Troja. This membrane 
 has no more to do with the formation of the new bone in necrosis than 
 with that of the callus in fracture.* The periosteum covering a bone 
 affected with necrosis does not become thicker, and does not acquire 
 
 * The manner in which the new bone acquires a periosteum, in cases of the 
 regeneration of this texture, is a matter of much interest and doubt. In the exa. 
 mination of some specimens, Dr. Knox observed a thin membrane covering the 
 osseous granulations ; but he knew of no facts to decide whence this membrane 
 proceeds. " It is not unlikely," he remarks, " that it is supplied by the cellular 
 texture either of the new bone or of the surrounding parts ; and that in some 
 instances it may be merely a prolongation of the old. New skin on ulcers does not 
 always grow from the surrounding healthy edges ; which fact may be applied to 
 the formation of new periosteum." J. C.
 
 400 OF THE MARROW. 
 
 more consistence ; nor is there formed around the ends of a fractured 
 bone a ring to keep them cemented, as was the opinion of Duhamel ; 
 an opinion recently brought forward in a work in which the author 
 seems to delight in reviving errors that have been abandoned for ages. 
 Destitute of nourishment, dead and v dried up in this artificial necrosis, 
 the sequestra moves in the centre of the new osseous production, from 
 which it may be extracted by a perforation made for that purpose. It 
 is owing to the same sympathy that the dull, nocturnal pains, which are 
 occasioned by the warmth of the bed, in patients in the last stages of 
 the venereal affection, and which appear to have their seat in the centre 
 of the long bones, occasion a swelling of these bones and of the peri- 
 osteum. 
 
 The use of the periosteum is to regulate the distribution of the 
 nutritious juices of bones, since, whenever it is removed, granulations 
 arise, in an irregular manner, on the spot that is bared. This quality 
 is, besides, common to all fibrous membranes, whose destruction is fol- 
 lowed by excrescences from the organs which they cover. The same 
 take place whenever trees are partially stripped of their bark. It has 
 been erroneously believed that the periosteum, in the same way as the 
 bark of plants, contributes to the growth of the bones by the successive 
 induration of its internal laminse. 
 
 The marrow which fills the central cavity of the long bones, and the 
 medullary fluid contained in the cells of the spungy substance, bear 
 the greatest analogy to adeps, both in their chemical composition and 
 in their uses (CVI.) The proportion of these two fluids is uniformly 
 relative. In very thin people, the bones contain a marrow that is thin 
 and watery ; and though this fluid always fills the internal cavities of 
 these organs, whose solid parietes cannot collapse, it contains much 
 fewer particles in the same bulk ; and its quantity, like that of the fat, 
 is in fact diminished. It is the product of arterial exhalation, and docs 
 not serve to the immediate nutrition of the bone, as was thought by the 
 ancients ; at least, it does not answer that purpose solely, for in the 
 numerous class of birds the bones contain cavities for air, and are 
 destitute of this fluid. It is difficult to determine the use of the mar- 
 row and of the medullary fluid : may they not answer the purpose of 
 filling the cavities which nature has formed in the bones, so as to 
 render them lighter? Does a part of these fluids exude through the 
 cartilages of the joints, and mix with the synovia, to increase its quan- 
 tity and to lessen the friction of the articulating surfaces? If this 
 transudation may take place after death, why might it not take place 
 when all the parts are in a state of vital warmth and expansion ?* 
 
 * The marrow of the hones is contained in the medullary memhrane. This 
 latter substance may be easily detached from the bone. Jt resembles, in some
 
 OF THE ARTICULATIONS, &C- 401 
 
 CLXXVIII. Of the articulations, the articulating cartilages and 
 ligaments, and the synovial fluid. The articulations of the different 
 parts of the skeleton are not all intended to allow of motion; several, 
 as the serrated and squamous sutures, and the gomphosis, or the junc- 
 tion by engrafting, are entirely without motion, and are, on that ac- 
 count, termed synarthrosis. All the other articulations, whether the 
 bones are in immediate contact (diarthrosis of contiguity), or whether 
 they are united by a substance interposed between them (diarthrosis 
 of continuity or amphiarthrosis), are endowed with a certain degree 
 of mobility. I shall speak merely of the movable articulations; whether 
 they allow of extensive motions, and in every direction (diarthrosis orbi- 
 cularis), or whether the bones move only in two opposite directions 
 (alternate diarthrosis or ginglymus), by forming an angle (angular 
 ginglymus, (or by executing on each other motions of rotation (lateral 
 ginglymus). ' 
 
 In all the articulations the osseous surfaces are covered by laminae 
 of a substance less hard than that of the bone. These are the articu- 
 lating cartilages, which answer the two purposes, of giving to the ends 
 
 respects, a cobweb, being pierced by a number of holes. It is formed of cellular 
 tissue and of vessels. The former is very delicate and rare, and evidently performs 
 the function of furnishing a surface for the ramification of the vessels. Some of 
 these vessels are ramified externally, proceeding directly from the medullary mem- 
 brane to the osseous texture surrounding it, and thus performing the office of an 
 internal periosteum to the bone ; others are distributed internally, and in the direc- 
 tion of the axis of the bone, to the medullary membrane itself, and to the spongy 
 extremities of the bones. The principal artery of the medullary canal is surroundei 
 by absorbent vessels at its entrance into this canal. A plexus of nerves may be 
 also observed to surround the artery in the same situation, and to dip into the bone 
 at the place nearest to the arterial trunk. 
 
 The adipose vesicles, which contain the marrow and occupy the interior of the 
 medullary membrane, are the same in kind as those of the cellular texture, although 
 less distinct. Authors have long since stated that those adipose vesicles are 
 united en grappe, and many believe that they communicate directly with each other. 
 M. Beclard considers the marrow to consist of seven parts out of eight of an olea- 
 ginous matter in fat subjects, which accords with the opinion of Grutzmacher; while 
 this substance, in a phthisical patient, was found to consist of only a fourth part of 
 fatty matter, the rest being a serous or albuminous-like fluid. 
 
 The marrow does not exist iu the foetus, and even the medullary membrane 
 itself cannot be recognised previous to ossification. As this process advances, the 
 medullary canal begins to be formed ; and at first the nutritious artery nearly fills 
 it. At a later period this artery is seen ramified on the parietes of this cavity, and 
 in the situation of the medullary membrane. The marrow becomes abundaut as 
 age advances, owing to the enlargement of the medullary cavity. 
 
 The sensibility of the marrow, which was contended for by Duverney, but since 
 denied, is considered by M. Beclard really to exist, and to be satisfactorily shewn, 
 when some time is allowed to elapse between the pain of the operation necessary to 
 expose the marrow, and the experiment to which it is to be subjected in order to 
 ascertain the fact as to its sensibility. See APPENDIX, Notes L L, for additional 
 remarks on this subject. <7. C.
 
 402 OF THE ARTICULATIONS, &C. 
 
 of the bones the degree of polish necessary to their slipping freely, and 
 to facilitating motion, by the considerable degree of elasticity which they 
 possess. Morgagni has shewn that, of all animal substances, cartilages 
 possess most elasticity : their structure is very different from that of 
 the bones, even when these are yet cartilaginous ; for these articulating 
 cartilages do not become ossified even in persons greatly advanced in 
 years.* They are formed of very short fibres, disposed according to 
 the length of the bone, strongly compressed against each other, and 
 united by other transverse fibres. This vertical direction of the greatest 
 part of cartilaginous fibres, demonstrated by Lassone, is very favour- 
 able to their elastic reaction. The capsular ligament is reflected over 
 them, becomes very thin, and is lost in their perichondrium, according 
 to Bonn, Nesbith, and other anatomists. 
 
 Besides the cartilages which surround the extremities of bones, 
 there are found, in certain articulations, fibro-cartilaginous laminae 
 lying between the articulating surfaces. These connecting ligaments 
 may be observed in the articulation of the lower jaw to the temporal 
 bones, of the femur with the tibia, and of the sternum with the clavicle; 
 and all such articulations perform a great number of motions, as is the 
 case with the jaw ; or suffer considerable pressure, as the joints of the 
 knee and sternum. The latter, which has a very slight degree of 
 motion, being the point in which terminate all the efforts of the upper 
 extremity, required this apparatus to lessen the effect on the trunk, the 
 motion that is given being in part lost in the action of the articulating 
 cartilage.f 
 
 I shall not repeat what has been already said of the secretion of 
 the fluid that lubricates the articulating surfaces, that facilitates their 
 motion, and keeps them in contact. Its quantity is in the direct ratio 
 of the extent of these surfaces, and of the membranous capsule in 
 which they are contained ; it is, likewise, proportioned to the fre- 
 quency of motion which each articulation allows. 
 
 Synovia is the name that is given to the fluid prepared by the 
 glandule-cellular bodies in the vicinity of the articulations, and secreted 
 by the membranous capsules which surround them, and are reflected 
 over the articulating extremities of the bones whose cartilages they 
 cover ; so that, as was shewn by Bonn, about the middle of the last 
 century, these extremities cannot be said to be contained within the 
 
 * Sometimes, however, these cartilages are destroyed ; the denuded bone then 
 becomes polished by friction, and as hard as ivory. 
 
 -|- The most certain proof of the organic nature of the cartilages is the serous 
 exudation which appears in the course of a few seconds after a clean division of 
 them by the knife. Cellular texture forms the mould or basis in which the carti- 
 laginous substance is deposited. The vessels of this texture carry only the colour, 
 less part of the blood into it, during its ordinary state of health ; yet it is remark, 
 able that other colouring substance", as bile and madder, give this substance their 
 respective colours. /. C.
 
 OF ANCHYLOSIS. 403 
 
 cavity of the capsule, which is closed in every direction, any more than 
 the abdominal viscera within that of the peritoneum. The synovia is 
 heavier than common water, quite colourless, and more viscid than any 
 other animal fluid. It contains a considerable quantity of albumen, 
 which, according to Margueron, who first gave a tolerably accurate 
 analysis of synovia, is found in a particular state, and much disposed 
 to concrete into filaments on the addition of acids. Besides, it con- 
 tains also muriate, carbonate, and phosphate of this secretion, which 
 substances are dissolved in the watery part of this secretion, which 
 forms about three-fourths of its weight.* 
 
 CLXXIX. Theory of anchylosis. Motion may be considered as 
 the proper stimulus of the synovial secretion ; and a movable joint, as 
 is justly observed by Grimaud, is as a centre of fluxion towards which 
 the fluids rush in every direction, in consequence of the irritation which 
 friction determines. If the joint remains long without motion, the 
 synovia is secreted in smaller quantity, and this lessens gradually : it 
 may even happen that the articulating surfaces, remaining long abso- 
 lutely motionless, lose their moisture, and, from the want of the fluid 
 which should lubricate them, bring on irritation and adhesive inflam- 
 mation in each other, either from increased action of the vessels of the 
 perichondrium, or, as is believed by Nesbith, Bonn, and others, from 
 an inflammatory state of the fold, which is reflected from the capsule 
 of the joint over the ligament. 
 
 This is the manner in which the disease termed anchylosis comes 
 on ; a disease improperly ascribed to the congestion of the soft parts, 
 and especially of the ligaments surrounding the articulations. In fact, 
 when in a fracture of the thigh or leg, about the middle of the length 
 of one of these bones, and consequently at the greatest possible dis- 
 tance from the knee-joint, the circumstances of the case require that 
 the bandages should be kept on the limb a considerable time, the joint 
 loses its power of motion, recovers it with difficulty, and sometimes not 
 at all. I have at present before me the case of a man in whom a 
 scorbutic affection has delayed to such a degree the union of the bone, 
 after a simple fracture of the femur, about its middle, that it has been 
 found necessary to continue, for seven months, the use of splints. In 
 the course of so long a state of inaction, the soft parts have lost the 
 habit of moving, and the knee is almost anchylosed. 
 
 Whenever, on account of any complaint, one has been confined to 
 bed, the first attempts to walk are painful, difficult, and attended by a 
 marked crepitus in the knee, denoting clearly the want of synovia. If 
 the joint be examined in a person who before death has been long 
 
 * See the Chapter on the Chemical Constitution of the Secretions, &c. at the 
 end of the APPENDIX.
 
 404 OF ANCHYLOSIS. 
 
 without motion, the articulating surfaces will be found rough and dry, 
 with evident marks of inflammation. Flajani mentions the case of 
 a patient who died after having been three months in bed in an almost 
 motionless state. Externally the knees did not appear to have been 
 injured, and yet he could not bend* his knee-joints. On opening 
 these joints, it was found that the articulating surfaces had grown 
 together ; the posterior part of the patella adhered to the condyles of 
 the femur, and it was necessary to use a scalpel to detach these parts 
 from each other. I have frequently observed the same appearance in 
 dissecting the knee-joint of persons who died while labouring under 
 white swelling, with or without ulceration. The anchylosis which inva- 
 riably attends this affection, evidently arises from the absolute rest of 
 the diseased joint. 
 
 Anchylosis from want of motion, and consequently from want of 
 synovia, is not always a partial affection, limited to one or two joints ; 
 sometimes it affects several at once, as in the case of the patient whose 
 skeleton was presented by M. Larrey to the museum of the School of 
 Medicine at Paris. One of the most remarkable cases of universal 
 anchylosis of the joints is that lately communicated to the National 
 Institute by M. Percy : the patient was an old cavalry officer, who was 
 subject to fits of the gout, and whose articulations, even that of the 
 lower jaw, became stiff, and completely lost all power of motion, so 
 that, towards the latter end of his wretched existence, he could not be 
 moved without feeling severe pain in his anchylosed joints. 
 
 From this explanation may be conceived the advantage of moving 
 the lower extremity, when, after a fracture of the leg, the ends of the 
 bone have become sufficiently united to prevent their being displaced. 
 These motions, which are of indispensable necessity in all fractures of 
 the femur, of the tibia, and especially of the patella, are much better 
 calculated to prevent anchylosis than the various resolvent remedies 
 which are commonly employed, as plasters of soap, vigo, cicuta, diabo- 
 tanum, diachylon, pumping, bathing, and fumigations, which, however, 
 should be used in combination with a moderate exercise of the limb, in 
 order to obtain the most complete success. 
 
 The gout affects those joints which are most subject to motion, 
 and on which there is the greatest pressure. The first attacks, as 
 Sydenham observes, come on in the joint of the great toe with the 
 first metatarsal bone ; an articulation which bears the weight of the 
 whole body, and which is most called into action in the various motions 
 of progression. 
 
 The muscles which pass over the joints give them much greater 
 security than the lateral ligaments. In fact, if the muscles become 
 palsied, the mere weight of the limb stretches the ligaments, which 
 give way, become elongated, and allow the head of the bone to escape
 
 OF STANDING. 405 
 
 from its glenoid cavity. It is in this manner that a loss of motion and 
 atrophy of the deltoid muscle are attended with a luxation of the 
 humerus : the orbicular ligament of the articulation of this bone with 
 the scapula being incapable of retaining its head within the glenoid 
 cavity. The spinal column, when dissected and deprived of all but its 
 ligamentous attachments, gives way under a weight much smaller than 
 that which it would have supported before being stripped of the 
 muscles which are connected with it. 
 
 CLXXX. Of standing, Sfc. This is the name given to the action 
 by which man holds himself upright on a solid plane. In this erect 
 position of all our parts, the perpendicular line, passing through the 
 centre of gravity* of the body, must fall on some point of the space 
 measured by the soles of the feet. Standing is most firm when, on 
 prolonging the line of the centre of gravity of the body, it falls on the 
 base of sustentation, (I call thus the space defined by the feet, whether 
 close or apart) ; but this line may tend to exceed it, without our 
 necessarily falling, the muscular action soon restoring the equilibrium, 
 which is deranged by the altered direction of this line. But if the 
 lower extremity of the line, by being prolonged, should be without the 
 limits of the base of sustentation, a fall is unavoidable on the side 
 towards which this line inclines. f 
 
 If the body is inclined backwards, so that there is a danger of a 
 fall on the occiput, the extensor muscles of the leg contract powerfully 
 .to prevent the thigh from bending, while other powers bring forward 
 the upper parts, and give to the prolonged line of the centre of gravity 
 a different direction : and if, in proportion as the extensors of the leg 
 are brought into action, its inclination be increased to such a degree 
 that nothing is capable of keeping up the body, which its own weight 
 tends to bring to the ground, these muscles, by a motion proportioned 
 to the quickness of the fall, will increase their efforts to prevent it, and 
 may be able, in that violent contraction, to snap asunder the patella, 
 as I have explained in a memoir on the fractures of that bone. 
 
 I think it useful to insist, more than has been done hitherto, on the 
 mechanism by which the human body is supported in the erect pos- 
 ture ; for a knowledge of that mechanism facilitates the explanation of 
 
 * The centre of gravity in the adult is situated between the sacrum and pubis. 
 
 -f- " Quotiescumque linea propensionis corporis humani cadit extra unius pedis 
 innixi plantam, ant extra quadrilaterum, comprehensum a duab-us plantis pedum, 
 impediri rwino, d quocumque musculorum conatu, nonpotest." BORELLI, Prop. 140. 
 
 The firmness of the attitude in standing depends in part, therefore, on the 
 breadth of the feet and on their distance ; hence it is much more tottering when 
 we stand on one foot ; and we are, under such circumstances, obliged to be perpe- 
 tually struggling to prevent the centre of gravity from falling out of the narrow 
 limits of the base of sustentation.
 
 406 OF STANDING. 
 
 the motions of progression. To walk or to run, the body must be 
 upright : now, when it is known by what power the centre of gravity 
 of the body is maintained perpendicular on the plane which supports 
 it, it will be easy to understand the different ways in which it changes 
 its place in the course of locomotion. v 
 
 Let us first inquire into the question so long agitated, whether man 
 is intended to support himself, and to walk on his four limbs, in the 
 early period of his existence after birth? 
 
 CLXXXI. Of the mechanism of standing. An upright position 
 would be to man a state of rest, if his head were in a perfect equili- 
 brium on the vertebral column; and if the latter, forming the axis of 
 the body, and supporting equally in every direction the weight of the 
 abdominal and thoracic viscera, fell perpendicularly on the pelvis 
 placed horizontally ; and, in short, if the bones of the lower extremi- 
 ties formed columns set perpendicularly under their superincumbent 
 weight; but not one of these circumstances is to be observed in the 
 human body : the articulation of the head does not correspond to its 
 centre of gravity, and the weight of the thoracic and abdominal viscera, 
 and of the parietes of the cavities in which they are contained, rests 
 almost entirely on the anterior part of the vertebral column. The 
 vertebral column is supported on an inclined base, and the bones of 
 the inferior extremities, which are connected to each other by convex 
 and slippery surfaces, are more or less inclined towards one another. 
 It is therefore necessary that an active power* watch incessantly, to 
 prevent the fall which would be the natural consequence of their 
 weight and direction. 
 
 This power resides in the extensor muscles, which keep the parts of 
 our body in a state of extension the more perfect, and which render 
 our erect posture the firmer, as they are endowed with a more 
 considerable power of antagonism, and as our parts are naturally less 
 
 * An upright posture is not in all animals, as it is in man, the consequence of an 
 effort. This is proved by the following fact, observed by M. Dumeril : the sea-fowl, 
 and especially the waders (Gra/te Linn.), as herons and storks, that are forced to 
 live in the midst of marshes and muddy waters, in which they find the fishes and rep. 
 tiles on which they feed, have long since afforded matter of surprise to naturalists 
 by the length of time they can remain motionless in an erect posture. This singular 
 power, so necessary to animals obliged to expect their prey more from chance than 
 from industry, they owe to a peculiar conformation of the articulation between the 
 leg and thigh. The articulating surface of the thigh-bone, as M. Dumeril had an 
 opportunity of observing in a stork (Ardea ciconia Linn.), contains in its centre a 
 depression, into which there is received a projection of the tibia. To enable the 
 animal to bend its leg, that projection must be disengaged from the depression into 
 which it is lodged, and this is resisted by several ligaments, which keep the leg 
 extended in standing, in flying, and other progressive motions, without the assist- 
 ance of the extensor muscles.
 
 NATURAL CURVATURES OF THE SPINE. 407 
 
 disposed to flexion; and, besides, as we have seen (CLXVL), these 
 powers are not sufficient to balance those whose action is directly 
 opposed to theirs. 
 
 The relative weakness of the extensor muscles is not the only 
 obstacle which renders impossible an erect posture at an early period 
 of life. Other causes, into which we are about to enter, concur in 
 unfitting the new born child for the exercise of that faculty. 
 
 The articulation of the head to the vertebral column being nearer 
 the occiput than the chin, and not corresponding to its centre of 
 gravity, its own weight is sufficient to make it fall on the upper part of 
 the chest. It is the more disposed to fall forward from its greater 
 bulk ; and as, in a new-born child, the head is much larger in 
 proportion than the other parts of the body, and as its extensor 
 muscles partake of the greater weakness of that set of muscles, it falls 
 on the fore part of the chest, and in its fall draws the body after it. 
 The weight of the thoracic and abdominal viscera tends to produce 
 the same effect. 
 
 Growth always proceeds from the upper to the lower parts, and 
 this law, which operates uniformly, completely eludes every kind of 
 mechanical explanation. It is otherwise with regard to the effects 
 which result from this unequal growth in respect to the erect posture. 
 The inferior limbs, which serve as a base to the whole edifice, being 
 imperfectly evolved at the period of birth, the upper parts placed on 
 these unsteady foundations, must necessarily fall and bring them down 
 with them. 
 
 The relative weight of the head, andof the thoracic and abdominal 
 viscera, tends, therefore, to bring forward the line in the direction 
 of which all the parts of the body press on the plane which supports 
 it, and this line should be exactly perpendicular to that plane to 
 enable the body to be perfectly erect. The following fact proves this 
 assertion : I have observed, that children whose heads are very large, 
 whose bellies project, and whose viscera are loaded with fat, have much 
 difficulty in learning to stand ; it is only about the end of their second 
 year that they dare trust to their own strength, and then they meet 
 with frequent falls, and have a continual tendency to go on all fours. 
 
 The vertebral column in the child does not describe, as in the 
 adult, three curves alternately placed in opposite directions. It is 
 almost straight, and yet presents in the direction of its length a slight 
 curvature, the concavity of which looks forwards. This incurvation, 
 which depends solely on the flexion of the trunk while in the womb, is 
 accordingly more marked the nearer the child is to the time of his 
 birth. 
 
 It is well known that the curvatures in opposite directions to the 
 vertebral column, add to the firmness of the erect posture, by in-
 
 408 NATURAL CURVATURES OF THE SPINE. 
 
 creasing the extent of the space within which the centre of gravity 
 may move, without being carried beyond its limits With regard to 
 that use, the vertebral column may be considered as defined by two 
 lines drawn from the anterior and posterior part of the first cervical 
 vertebra to the sacro-lumbari symphy^is. These two lines, very near 
 to each other at their upper part, and below, at a distance from each 
 other, would be the chords of arcs, and the tangents of the curves 
 formed by the vertebral column. So that this column may be 
 considered as having a fictitious thickness greatly exceeding its real 
 bulk. 
 
 In the new-born child the want of alternate curvatures not only 
 contracts the boundaries within which the centre of gravity may be 
 varied, but the direction of the only curvature which exists favours the 
 flexion of the trunk, and, consequently, the inclination forward of 
 the centre of gravity, and the tendency to fall in that direction. This 
 inflexion of the vertebral column in the foetus, and in the young child, 
 resembles that observed in several quadrupeds.* 
 
 The disadvantage resulting from the want of alternate curvatures 
 in the vertebral column of the child, is farther increased by the total 
 absence of spinous processes. It is well known that the principal use 
 of these projections is to place the power at a distance from the centre 
 of motion of the vertebrae, to increase the length of the lever by which it 
 acts in straightening the trunk, and thereby to render its action more 
 efficacious. At the period of birth the vertebrae have no spinous pro- 
 cesses ; they afterwards grow from the place at which the laminae of 
 those bones are united by means of a cartilaginous substance, which 
 completes the posterior part of the vertebral canal. The muscles 
 destined to keep the trunk erect, weakened by its constant flexion 
 during gestation, lose, besides, a great deal of their power from the 
 unfavourable manner in which they are applied to the part on which 
 they are to act. 
 
 The flexion of the head does not depend merely on its very con- 
 siderable weight, but likewise on the want of spinous processes in the 
 cervical vertebrae, since the principal motions of the neck are performed, 
 not so much by articulation with the atlas, as by the union of the other 
 cervical vertebrae. 
 
 The pelvis of the child is but imperfectly evolved, and its upper 
 
 * This curvature is very distinctly marked in swine. The hack of these animals 
 is remarkably prominent ; and this form, necessary to enable the vertebral column 
 to support the immense weight of their abdominal viscera, has a considerable in. 
 fluence on the mechanism of their motions of progression. When frightened by any 
 noise, they spring in bounds, and it is easy to perceive that, at each spring, the spine 
 becomes arc'ied and then straightens itself, and that their motion, when rapid, is 
 effected by the alternate tension and relaxation of their spinal arch.
 
 OF THE FORM OF THE FEET. 409 
 
 Outlet very oblique. The viscera, which are afterwards to be contained 
 within its cavity, are, for the greater part, situated above it. This 
 obliquity of the pelvis would require a perpetual straightening of tfee 
 vertebral column to prevent the direction of the centre of gravity from 
 obeying its natural tendency forward. On the other hand, the verte- 
 bral column, resting on a narrow pelvis, is less firmly fixed, and may 
 more readily be drawn beyond the limits of the base of sustentation. 
 Lastly, the limited extent of the pelvis, together with its obliquity, 
 causes the ill- supported abdominal viscera to fall on the anterior and 
 inferior part of the parietes of the abdomen, and favours the fall of the 
 body in the same direction. 
 
 The patella, which answers the double purpose of giving firmness 
 to the knee-joint, in front of which it is placed, and of increasing the 
 power of the muscles of the leg, by placing them at a distance from 
 the centre of motion in that articulation, and by increasing the angle 
 at which they are inserted into the tibia, as yet does not exist in new- 
 born children. The tendinous portion of the extensors of the leg, 
 where the patella is hereafter to be formed, is merely of a more con- 
 densed tissue, and of a cartilaginous hardness. 
 
 The want of a fulcrum is attended with a continual disposition in 
 the leg to bend upon the thigh, and the parallel direction of its exten- 
 sor muscles occasions a complete loss of their effective power. Then 
 their antagonising muscles induce a flexion of that limb, which is the 
 more considerable, as it is but imperfectly limited by the tendon which 
 is situated at the fore part of the knee. 
 
 The length of the os calcis, and.the extent of its projection beyond 
 the inferior extremity of the bones of the leg, tend to give firmness to 
 the erect posture, by increasing the length of the lever by which the 
 extensors of the foot act on the heel ; and as in the new-born child this 
 bone is shorter and less projecting, the power of these muscles, whose 
 insertion is very near the centre of motion of the articulation of the foot, 
 is greatly diminished. 
 
 The feet in man are broader than those of any other animal ; and 
 to this breadth of the surface of the base on which he rests, he in 
 great measure owes the advantage of being able to support the 
 weight of his body, on one leg or on both, in standing, and in the 
 different motions of progression ; while the other mammalia cannot 
 support themselves, at least only for a limited time, without resting 
 on three of their extremities. When I say that, from the extent of his 
 feet, the body of man does, of all animals, rest on the broadest surface, 
 I do not take into account the space which those parts include between 
 them when apart from each other. In fact, the space which is mea- 
 sured by the feet, is much greater in quadrupeds than in man. Nature 
 has made up for the disadvantage arising out of the smallness of their
 
 410 OF THE FORM OF THE FEET. 
 
 feet, by the distance at which they are placed ; and if that form dis- 
 ables them from standing on two feet, it gives firmness to their peculiar 
 mode of standing. 
 
 The feet of the ourang outang, which, in the general structure of 
 his organs, bears so striking an analogy to the human species, resem- 
 ble a coarsely formed hand, better fitted to climb the trees on which 
 that animal seeks his food, than to the purposes to which man applies 
 his hands. Thus the erect posture, which he at times assumes, is 
 neither the most convenient nor the most natural to him. And, 
 according to a philosopher, who speaks on the authority of several 
 travellers, if a sudden danger obliges him to make his escape, or to leap, 
 he drops on all fours, and discovers his real origin : he is reduced 
 to his own condition when he quits that unnatural attitude, and 
 discovers in himself an animal, which, like many a man, has no 
 better quality to recommend him than a specious disguise. 
 
 The feet are the parts least developed in . the new-born child ; 
 his body is insecure on that narrow basis : the prolongation of the line 
 of his centre of gravity, which so many other causes tend to carry 
 beyond that base, will be the more inclined to fall beyond it from 
 its small extent. The greater number of the differences which have 
 just been examined, depend on the mode of nutrition in the fetus. 
 The umbilical arteries bring to the mother the blood which the aorta 
 carries towards the lower parts, and only a few small branches are 
 sent to the pelvis and to the lower extremities. Thus the development, 
 which almost uniformly bears a proportion to the quantity of blood 
 sent into organs, is but imperfect in those parts at the time of birth, 
 while the head of the trunk and upper extremities are evolved much 
 more considerably. 
 
 f The new-born child, therefore, resembles quadrupeds in the phy- 
 sical arrangement of his organs. This analogy is the more marked the 
 nearer the foetus is to the period of its formation ; and it might be laid 
 down as a general proposition, that organised beings resemble one 
 another more closely the nearer to the period of incipient existence 
 they are examined. The differences which characterise them become 
 apparent in proportion to the progress of evolution, and they are more 
 and more distinct as the acts of life are repeated in the organs which 
 .it animates. 
 
 The unequal distribution of power in the muscles, and the unfa- 
 vourable disposition of the parts to which these powers are applied, 
 render it impossible for the infant to stand upright, that is, to keep the 
 mean line of direction of his body nearly perpendicular to the plane 
 which supports it. But in proportion as he advances in age, the pre- 
 ponderance of the flexors over the extensors ceases to be in excess. 
 The proportionate size of the head, and of the thoracic and abdominal
 
 THE MECHANISM OF STANDING. 44V 
 
 viscera, diminishes. The curvatures of the vertebral column begin to 
 be distinguishable, the spinous processes of the vertebrae are evolved ; 
 the breadth of the pelvis is increased, and its obliquity lessened ; the 
 patella becomes ossified, the os calcis juts out backwards, and the rela- 
 tive smallness of the feet ceases. By degrees the child learns to 
 stand, resting on both, or only on one of his feet, his eyes naturally 
 directed towards heaven a noble prerogative, which, if one might 
 believe Ovid,* is possessed by man alone of all the animals. 
 
 Man is of all animals the only one that can stand upright and walk 
 in that attitude, when his organs are sufficiently evolved. Let us now 
 point out some of the principal causes to which that privilege is to be 
 ascribed. 
 
 CLXXXII. Though the articulation of the head to the cervical 
 column does not correspond either to its centre of magnitude or to its 
 centre of gravity, and though it is nearer to the occiput than to the 
 chin, its distance from the latter is much smaller in man than in the 
 monkey and other animals, whose foramen magnum is, according to 
 Daubenton, placed nearest to the posterior extremity of the head when 
 they resemble man the least. The head, therefore, is very nearly in 
 equilibrio on the column which supports it; at least, to keep it in that 
 position, a very slight power is required ; while the head of a quadru- 
 ped, which has a constant tendency towards the ground, requires to be 
 supported by a part capable of a great and continued resistance. This 
 purpose is answered by the posterior cervical ligament, so remarkable 
 in those animals, attached to the spinous processes of the vertebrae and 
 to the protuberance of the occipital bone, which projects much more 
 in them than in the human species, in whom, instead of a posterior 
 cervical ligament, there is found a mere line of cellular substance, 
 dividing the nape of the neck into two equal parts. 
 
 The alternate curvatures of the vertebral column, the breadth of the 
 pelvis and of the feet, the great power of the extensors of the foot and 
 thigh f all these favourable conditions, observable in man, are wanting 
 in animals; but as in the latter every thing concurs to prevent their 
 being capable of standing on two feet, in man every thing is so dis- 
 posed as to render it very difficult for him to rest on his four extre- 
 mities. In fact, independently of the great inequality which there is 
 between his upper and lower limbs, a difference of length which, being 
 
 * Os homini sublime dedil, ccelumque tueri 
 Jussit, et erectos ad sidera tollere vullus. 
 
 These verses may be much more justly applied to the fish called by naturalists 
 uranoscopus. Its eyes are turned upwards, and constantly look towards the 
 heavens. 
 
 f These masses form the calf of the leg and the buttocks : in no animal are 
 these muscles of flesh more prominent than in man.
 
 412 THE MECHANISM OF STANDING. 
 
 less sensible in early life, makes it less uneasy for a child to walk on 
 his hands and feet, these four limbs are far from affording the body 
 an equally solid support. The eyes being naturally forwards, are, in 
 that attitude, directed towards the earth, and do not embrace a 
 sufficient space. 
 
 We cannot, therefore, agree with Barthez, that man during infancy 
 is naturally a quadruped, since he is then but an imperfect biped 
 (CLXXXI.) ; nor can we admit that man might walk on all fours all 
 his life, if he were not broken of the bad habit which he learns in 
 infancy. 
 
 CLXXXIII. Very little has been added to what Galen has said, 
 in his admirable work on the structure of parts, relative to the re- 
 spective advantages attending the peculiar conformation and structure 
 of the upper and lower limbs. It is easy to see, that in combining, as 
 much as possible, strength and facility of motion, nature has made the 
 former predominate in the structure of the inferior extremities, while 
 she has sacrificed strength to facility, to precision, to extent, and ra- 
 pidity of motion, in the upper extremities. 
 
 To convince oneself of the truth of what has been stated, it is 
 sufficient to compare, under the two relations* of the resistance of 
 which they are capable, and of the motions which they allow, the pelvis 
 to the shoulder, the thigh to the burner us, the leg to the fore-arm, and 
 the foot to the hand. 
 
 The inferior extremities, if examined when the bones are covered 
 with the soft parts, will present the appearance of an inverted cone or 
 pyramid, which, at first sight, appears contrary to the object which 
 nature had in view ; but if the bones be stripped of their fleshy cover- 
 ings, these solid supports will be seen to represent a pyramid, whose 
 base is at the lowest part, and formed by the foot, and which decreases 
 in breadth upward from the leg, formed by the union of two bones, 
 towards the thigh consisting of only one bone. 
 
 If it be asked why the inferior extremities are formed of several 
 pieces, detached and placed one above the other, it will be found that 
 they are thereby much more solid than if formed of one bone, since, 
 according to a theorem demonstrated by Euler, f two columns con- 
 taining the same quantity of matter, and of equal diameter, have each 
 a solidity in an inverse ratio of the squares of their height ; in other 
 
 * See the anatomical observations on the neck of the thigh bone, which I have 
 prefixed to a memoir bearing the title of Dissertation Anatomico-chirurgicale sur 
 les Fractures du Col de Femur. Paris, au VII. 
 
 f- Methodus inveniendi lineas curvas Nature has, therefore, increased the 
 number of these columns in the extremities of quadrupeds, by raising their heel, and 
 the different parts of the foot whose bones she has lengthened, to make of them 
 so many secondary legs. These numerous columns, placed above one another, are
 
 THE MECHANISM OF STANDING. 413 
 
 words, of two columns containing the same materials, of equal dia- 
 meter, and of unequal height, the smaller is the stronger. 
 
 The long bones, which by their union form the inferior extremity, 
 contain a cavity that adds to their strength ; for, according to another 
 theorem, explained by Galileo, two hollow columns of the same quan- 
 tity of matter, of the same weight and length, bear to each other a 
 proportion of strength measured by the diameter of their internal 
 excavations. 
 
 The breadth of surface of the articulations of the inferior extre- 
 mities assist materially in giving them additional strength, when, in 
 standing, these bones are in a vertical direction. No articulation ' 
 has a broader surface than that of the thigh with the leg and knee- 
 pan. Among the orbicular articulations, no one has more points of 
 contact than the joint of the thigh-bone to those of the pelvis. Pro- 
 fessor Barthez says, that when the body is erect, the head of the thigh 
 bone and the acetabulum of the os innominatum, which receives that 
 bone, come in contact in a surface of small extent. I am, on the con- 
 trary, of opinion, that in no possible case can the contact of two bones 
 be more complete. The middle line of direction of the upper part of 
 the thigh-bone is then exactly perpendicular to the surface of the 
 condyloid cavity, which embraces and touches, in nearly every point, 
 the almost spherical head of that bone. 
 
 The cervix on which the head of the bone is placed, by keeping the 
 thigh-bone at a distance from the cavity of the pelvis, increases the 
 extent of the space in which the centre of gravity may vary without 
 being carried beyond its limits. 
 
 CLXXXIV. The erect posture does not imply a perfect absence 
 of motion. It is, on the contrary, accompanied by a staggering, which 
 is the more marked in proportion as the person has less strength and 
 vigour. These perpetual oscillations, though but slightly distinct in 
 a man who stands upright, depend on the incapacity of the extensors 
 to keep up a constant state of contraction, so that they become relaxed 
 for a short time; and the intervals of rest in the extensors are frequent 
 in proportion to the weaker state of the subject. 
 
 Some physiologists have given a very inaccurate idea of standing, 
 by making that attitude depend on a general effort of the muscles : the 
 extensors only are truly active. The flexors, far from assisting, tend, 
 
 alternately inclined, and in a state of habitual flexion, in the quadrupeds remarkable 
 for swiftness in running, or for their power in leaping, as in the hare and squirrel ; 
 while in the ox, and especially in the elephant, they are all placed vertically ; so 
 that the enormous mass of the latter rests on four pillars, the different pieces of 
 which are short, and so slightly movable on one another, that, as Barthez observes, 
 Saint Basil has adopted the error of Pliny, ./Elian, and several other writers of 
 antiquity, that there are no articulations in the legs of that monstrous animal.
 
 414 THE MECHANISM OF STANDING. 
 
 on the contrary, to disturb the relation between the bones necessary to 
 render that state permanent. This explains why standing is so much 
 more fatiguing than walking, in which the extensors and flexors of the 
 limbs are in alternate action and rest. 
 
 It may be said, nevertheless, that to give the greater firmness to the 
 attitude, we sometimes contract, in a moderate degree, the flexors 
 themselves; then, that great part of the real force of the muscles, which 
 acts according to the direction of the levers which they are to set in 
 motion (CLXVL), and which is completely lost in the different mo- 
 tions which they produce, is usefully employed in drawing together the 
 articular extremities, in keeping their surfaces firmly applied to each 
 other, and in maintaining their exact superposition, which is necessary 
 to the erect posture of the body. No one that I know of had taken 
 notice of this employment of the greater portion of our muscular 
 power, which was thought completely lost by the unfavourable arrange- 
 ment of our organs of motion. 
 
 The line, according to, which all the parts of the body bear on the 
 plane which supports them, has much more tendency to fall forwards 
 than backwards;* and falls forward are the most common and the 
 easiest. Thus, nature has directed, in the same direction, the motion 
 of the hands, which we carry forward to break the force of our falls, to 
 prevent too violent shocks, and to lessen their effect. At the same 
 time she has provided means of protection towards the sides, which the 
 hands could not guard. She has given more thickness to the back 
 part of the skull ; the skin which covers the neck and back is much 
 denser than that which covers the fore part of the body ; the scapula, 
 in addition to the ribs, protects the. posterior part of the chest ; the 
 spinal column lies along the whole length of the back; and the bones 
 of the pelvis have their whole breadth turned backward. 
 
 Falls are the more serious as they occur in a more perfect state 
 of extension of the articulations : the falls of a child, whose limbs are 
 in an habitual state of flexion, are much less dangerous than those of 
 a strong and powerful adult, whose body falls in one piece, if I may 
 be allowed that expression. The falls which skaiters meet with on the 
 ice are often fatal, from fracture of the skull, which, placed at the 
 extremity of a long lever formed by the whole body, whose articula- 
 tions are on the stretch, strikes the slippery and solid ice with a 
 momentum increased by the quickness of the fall. 
 
 We have already seen, that wading fowls remain a long while 
 
 * This tendency is much less distinct in tall, slender men. It is observed that 
 they, for the most part, stoop in walking 1 , less from the habit of bending forward, 
 than to prevent the centre of gravity from falling behind. Pregnant women, drop- 
 *ical patients, all persons who have much embonpoint, throw their body back, from 
 an opposite and easily understood reason.
 
 THE MECHANISM OF STANDING. 415 
 
 standing, without effort, by means of a peculiar contrivance in the 
 articulation of the tibia to the thigh bone ; but all other birds are 
 obliged to employ muscular action when standing, except during sleep. 
 The greater part, it is well known, roost on a branch, which they grasp 
 firmly with their claws. Now this constriction, by which they cling 
 to their support, is a necessary result of the manner in which the 
 tendons of the flexors of their feet descend along their legs. These ten- 
 dons pass behind the articulation of the heel; and a muscle which arises 
 from the pubis joins them, as it passes in front of the knee, so that the 
 bird has but to give way to his weight, and the joints, becoming salient 
 on the side along which the tendons run, stretch and pull them, and 
 make them act upon the feet, so as to draw in the claws to clasp 
 tightly the branch on which he is perched. Borelli was the first who 
 understood distinctly, and explained satisfactorily, this phenomenon.* 
 
 CLXXXV. Although standing on both feet is most natural to 
 man, he is able to stand on one ; but the posture is fatiguing, from 
 the forced inclination of the body to the side of the leg which supports 
 him, and the effort of contraction required to keep up this lateral in- 
 flexion. The difficulty increases, if, instead of resting on the entire 
 sole, we choose to stand on the heel or on the toe : the base of support 
 is then so small, that no effort is sufficient to keep the centre of 
 gravity long together, in the requisite situation. 
 
 As to the degree of separation of the feet, which gives the firmest 
 possible stand, it depends upon their length. When they enclose a 
 perfect square, that is, when taking their length at nine inches, each 
 side of the quadrilateral figure is of that measure, the stand is the 
 firmest that can be conceived. Nevertheless, we are far from keeping 
 or taking this posture to prevent falls. The wrestler who wants to 
 throw his antagonist, strides much more ; but then he loses on one side 
 what he gains on another ; and if he stride thirty-six inches on the 
 transversal line, it will need much greater force to overthrow him ou 
 that side ; but it will take much less to throw him forwards, or on his 
 back. Wherefore, one of the great principles of this gymnastic art, is 
 to bring back the feet to a moderate stride, in the line of the effort 
 which is foreseen to require resistance. 
 
 There is some resemblance to standing in the attitudes of kneeling 
 and sitting. 
 
 In the first, the weight of the body bears upon the knees, and we 
 must bring back the body, to throw the centre of gravity over the middle 
 of the legs. Accordingly, if we have nothing before us to lean on, 
 this posture is extremely distressing, and we cannot long keep it on. 
 
 * De motu animalium, Prop. 150. Qtusritur quare aves stando^ ramis arborum 
 comprehensis, quiescunt et dormiunt absqne rutna. Tab. ii. fig. 7-
 
 416 OF THE HECUMBENT POSTURE. 
 
 I have said, in another work, that genuflexion rendered monks very 
 liable to hernia ; the abdominal viscera being pushed against the an- 
 terior and lower part of the abdomen, by the throwing back of the body. 
 
 In sitting, the weight of the body bearing on the tuberosities of 
 the ischia, there is much less effort required than in standing on the 
 feet. The base of support is much larger; and when the back leans, 
 almost all the extensor muscles employed in standing are in action. 
 
 CLXXXVI. Of the recumbent posture. Decubitus. All the 
 authors who, like Borelli, have treated professedly of the animal me- 
 chanism ; all the physiologists, who, like Haller, have set forth in 
 some detail the mechanism of standing and of progression, have com- 
 pletely passed over the consideration of the human body in repose, left 
 to its own weight, in lying on an horizontal plane. The intention of 
 the following observations is to fill up this gap. Let us consider, at 
 setting out, that lying on an horizontal plane is the only posture in 
 which all the locomotive muscles recover the principle of their con- 
 tractility, exhausted by exertion. Standing, without motion, has only 
 the appearance of repose ; and the unremitted contractions it requires, 
 fatigue the muscular organs more than the alternate contractions by 
 which the various motions of progression are carried into effect. 
 
 The human body, stretched on an horizontal plane, reposes in four 
 positions as it lies on the back, the belly, or one or other of the 
 sides. The Latin tongue expresses the first two situations by the 
 terms supine and prone.* It has no particular word for lying upon 
 the side, f 
 
 Lying upon the right side is the most ordinary posture of sleep, 
 in which we rest most pleasantly, and longest together. There are 
 very few, except under constraint of some faulty organisation, who lie 
 on the other side. This depends on two causes: when the body lies on 
 the left side, the liver, a bulky viscus, very heavy, and ill steadied 
 in the right hypochondrium, presses with all its weight on the stomach, 
 and draws down the diaphragm ; thence ensues an uneasiness, which 
 hinders long continuance of sleep, or disturbs it with distressing 
 dreams; then the human stomach presents a canal, in which the course 
 of its contents is obliquely directed from above downwards, and from 
 left to right : the right or pyloric orifice of the stomach is much less 
 raised than its left or cardiac orifice. Lying on the right side favours, 
 therefore, the descent of aliments, which, to pass into the intestines, 
 are not obliged to ascend against their own weight, as they must 
 in lying on the left side. These two anatomical causes exert their 
 
 * Cubitus supinus, Pl'm. Cubitus pronus, Cic. Cubare in faciem, Juven, 
 Supinus vel pronus jacere. 
 
 f Dextro vel laevo laterc cubare ; cubitus in latus. Win.
 
 OF RKCUMBEXT POSTURES. 417 
 
 influence on the generality of men ; and if there are any who fall into 
 the habit of lying on the left, one may safely conjecture some vicious 
 organisation, or some accidental cause, that determines them, as by 
 instinct, to this posture. 
 
 Let us suppose an effusion of blood, water, or pus, in the sac of the 
 pleura of the right side. The patient lies on this side, that the weight 
 of his body may not oppose the dilatation of the sound side of the 
 chest. The parietes of this cavity are not equally distant from its axis ; 
 the pressure of the body on the plane of support prevents the separa- 
 tion of the ribs, whether as a mechanical hindrance to the displace- 
 ment of these bones, or in numbing the contractility of the muscles of 
 inspiration, all being more or less compressed. Now, as the healthy 
 lung must supply the place of the diseased, nothing could be more in 
 the way than to produce, on that side, by a bad posture, a constraint 
 equal to that occasioned by disease on the other. 
 
 It has long been imagined, and it is taught still, that in thoracic 
 effusions, patients lie on the side of the effusion to hinder the effused 
 fluid from pressing on the mediastinum, and pushing it against the 
 opposite lung, of which it will constrain the developement. The fol- 
 lowing experiments shew clearly enough the error of such a sup- 
 position : ' 
 
 I have several times produced artificial hydrothorax by injecting 
 the chests of several bodies with water, through a wound in one of the 
 sides. This experiment can be made only on bodies in which the 
 lungs are free from adhesion to the parietes of the chest ; and the 
 number is smaller than might be imagined. You may introduce in this 
 way from three to four pints of water. I afterwards opened carefully 
 the opposite side of the chest : the ribs removed and the lung dis- 
 placed, gave room to see distinctly the septum of the mediastinum 
 stretched from the vertebral column to the sternum, and supporting, 
 without yielding, the weight of the liquid, whatever might be the 
 posture given to the body. 
 
 It is evidently for the sake, then, of not preventing the dilatation of 
 the sound part of the respiratory apparatus, already condemned in one 
 part to inaction, that patients in thoracic effusion lie constantly on 
 the side of the effusion. It is for the same motive, to which we may 
 add that of not increasing the pain by dragging downward the inflamed 
 pleura, that patients in pleurisy lie on the affected side. The same 
 thing happens in peripneumonies ; in a word, in all diseased affections 
 of the lungs and parietes of the chest.* 
 
 Lying on the back, which is unusual in health, is natural in many 
 
 * This is not so remarkably the case until after adhesions of the pleurae have 
 taken place J. C.
 
 418 OF RECUMBENT POSTURES. 
 
 diseases. It commonly indicates more or less weakness of the muscles 
 of inspiration. The contractile powers which perform the dilatation of 
 the chest, when affected with adynamia, in fevers of a bad character, 
 or after extreme fatigue, carry very imperfectly into effect this dilata- 
 tion. Nevertheless, a determinate .quantity of atmospherical air must 
 be admitted every moment into the lungs, and the general weakness 
 would be increased if respiration did not impregnate the blood with a 
 sufficiency of oxygen : patients choose, therefore, the posture which 
 makes the dilatation of the lungs easiest for their weakened muscles. 
 The posterior parietes of the chest, on which the body reposes when 
 lying upon the back, are almost useless in the expansion of the cavity. 
 The ribs, which have the centre of their motions in their articulations 
 with the vertebral column, are almost immovable backwards, and the 
 movableness of these bones increases with the length of the lever 
 which they represent ; so that no where is it greater than at the ante- 
 rior extremity terminating in the sternum. Thus lying on the back has 
 the double advantage, of not constraining any of the muscles of inspira- 
 tion, and of not opposing the motion of the ribs, except at that part where 
 these bones have the least play. Lying on the back is one of the cha- 
 racteristic symptoms of putrid or adynamic fever, of scurvy, and of all 
 diseases of which debility of the contractile parts forms the principal 
 feature. After the fatigue of a long march, or of any other continued 
 exertion, we take this position in lying, and change it only when sleep 
 has sufficiently replaced the loss of contractility. 
 
 Lying on the belly has effects directly the reverse. The expansion 
 of the chest is hindered exactly where the bony structure is formed for 
 the greatest play of motion; the abdominal viscera are, besides, pushed 
 up on the diaphragm, of which they resist the depression, and the 
 posture is accordingly unusual. The continuance of it during sleep 
 is possible only to the robust : others, even when they do fall asleep in 
 this posture, soon awake, from troubled and distressing dreams, under 
 the agony known by the name of the night-mare. We sometimes seek 
 this posture to constrain respiration, and so abate inward excitation ; 
 in the heighth, for instance, of a febrile paroxysm. 
 
 The different postures of lying having reference to the degrees of 
 facility of respiration, very young children, and persons advanced in 
 years, prefer lying on the back, this posture being, as was already 
 observed, the most favourable to the motions of respiration. Respiration, 
 like all the other functions of the animal economy, with the exception 
 of the circulation of the phenomena which immediately depend on it, 
 requires a kind of cultivation : it is but feebly performed fit an early 
 period of life. It is only after a certain number of years, and when 
 the muscles of respiration, at first small and weak, acquire strength 
 from the very circumstance of being called into frequent action, that
 
 OF RECUMBENT POSTURES. 4T9 
 
 the chest dilates with facility, and that the lungs enjoy the full exercise 
 of their faculties. Until that period the enlargement of the chest and 
 the dilatation of the lungs took place in an imperfect manner, and 
 the child was unable, even by spitting, to free itself of the mucus with 
 which its bronchiae are apt to get filled, and which render the pul- 
 monary catarrh, called the hooping-cough, so dangerous at an early 
 period of life. In like manner in an old man, the muscles debilitated, 
 and returned to the relative weakness of infancy, in vain strive to clear 
 the air-cells of the mucus with which they become obstructed in the 
 suffocating catarrh. The mechanical process of respiration is, therefore, 
 equally difficult in the child, from the weakness of the muscles 
 which have remained in a long-continued state of inactivity ; and in 
 the old man, from the debility of the same organs, and from the 
 induration of the cartilages. Thus, at those two distant periods of 
 life it is most natural to lie on one's back, but there is a suffi- 
 ciently remarkable difference in that respect, and which may now be 
 inquired into. 
 
 In the foregoing observations I have always spoken of the human 
 body as stretched on a perfectly horizontal plane. It is seldom, how- 
 ever, that we rest on such a surface ; almost every one, and especially 
 persons advanced in life, require that the plane should be inclined, and 
 that the head should be raised to a certain degree, else the brain 
 would become affected with a fatal congestion of blood. Children, on 
 the other hand, suffer no inconvenience from a neglect of this pre- 
 caution, whether it is that in them the vital power has more energy, 
 and thus balances better the laws of mechanics, by opposing more 
 powerfully the effects of gravitation, or whether it is that in very 
 young children the parietes of the arteries within the skull have a 
 proportionate thickness, and consequently greater power. The extreme 
 disproportion observable in adults between the cerebral arteries and 
 those of other parts of the body, in the thickness of their parietes, is 
 but trifling in children ; and may not this difference of structure, 
 which I have several times observed in the course of dissection, be con- 
 sidered as one of the principal causes which in old age bring on 
 apoplexy a disease to which the child is not liable? 
 
 It is well known, that as the enlargement of the chest is produced 
 by the depression of the diaphragm, persons who have taken a plen- 
 tiful meal, dropsical patients, and pregnant women, cannot rest without 
 lying on a very inclined plane, so that the chest being considerably 
 raised, and the patient, as it were, seated, the weight of the abdominal 
 viscera draws them towards the most depending part, that their bulk 
 may not.interfere with the depression of the diaphragm. 
 
 We might now inquire what is the posture in which the body rests 
 with least fatigue. This investigation, unimportant to the physician,
 
 420 OF PROGRESSION*. 
 
 would be of the highest value to the arts which have for their object 
 the imitation of nature. In consequence of ignorance on this subject, 
 we often see, in the works of several of our sculptors, figures in atti- 
 tudes of repose so incorrect and uneasy, that they could not main- 
 tain them without considerable effort' and fatigue. 
 
 CLXXXVII. Ofthemotions of progression. Of walking. Walk- 
 ing, running, and leaping, are so closely connected, that it is difficult 
 to distinguish them. There is, in fact, very little difference between 
 walking in a certain manner, or running ; and running is most fre- 
 quently produced by the complicated mechanism of running and leap- 
 ing. In the most natural way of walking, we, in the first instance, 
 poise the body on one foot; then, bending the opposite foot on the leg, 
 the latter on the thigh, and the thigh on the pelvis, we shorten that 
 extremity ; we at the same time carry it forward, extend its arti- 
 culations which were bent, and, when firmly applied to the ground, 
 we bend the body forward, and carry back the centre of gravity in that 
 direction ; and, performing the same motions with the limb which re- 
 mained behind, we measure the space more rapidly, cceteris paribus, 
 as the levers on which the centre of gravity alternately bears are 
 longer. The weight of the body, compared to that of the lower ex- 
 tremities, is as that of a carriage which moves, in succession, on the 
 different spokes of its wheels. 
 
 The centre of gravity does not move along a straight line, but 
 between two parallels, in which space it describes oblique lines from 
 the one parallel to the other, and forms zig-zags. The oblique direc- 
 tion of the neck of the thigh-bones accounts for the lateral oscillations 
 of the body when we walk ; the arms, which move in a different 
 direction from that of the lower extremities, serve to balance us, pre- 
 serve the equilibrium, and correct the staggering, which would be 
 much greater if the neck of the thigh-bone, instead of being oblique,, 
 had been horizontal. The impulses communicated to the trunk are 
 reciprocally balanced, and the latter moves in the diagonal of a 
 parallelogram, whose sides are represented by the line of these im- 
 pulses. We constantly deviate from the straight line in walking ; 
 and if the sight did not enable us to see, at a distance, 'the object 
 towards which we are moving, we should go widely from it. If you 
 place a man, with his eyes blindfolded, in the middle of a square 
 field, he will, in his attempt to get out, and thinking that he is moving 
 in a straight line, make for one of the corners. It is, almost always, 
 towards the left that we deviate, the right lower extremity, which is 
 the stronger, inclining the body towards the opposite side. Those who 
 are lame depart much more from a straight line, and deviate to- 
 wards the side of the shorter leg. The motions which they are obliged 
 to use, and which render their gait so remarkable, are occasioned by
 
 OF PROGRESSION. 421 
 
 the necessity of incessant and powerful efforts to prevent the body 
 from giving way to its own weight, and to the greater power of the 
 sound extremity, which inclines it towards the affected side. 
 
 The breadth of the feet, and a moderate separation of these parts, 
 give a much firmer support to the centre of gravity. Thus, in walking 
 on a moving and insecure surface, we hold apart our feet, so as to 
 include a greater base of sustentation. Those who hive long been at 
 sea, acquire such a habit of holding their feet asunder, in the way/ 
 they are obliged to do during the rolling of a ship, that they cannot 
 lose the habit even when on shore, and are easily recognised by their 
 gait. A sailor is unfit for active service till he has acquired what is - 
 called by seafaring people a seaman's foot, that is, till he is capable 
 of stepping firmly on the deck of a vessel tossed by the tempest. 
 
 The gait of a woman, frorfi her having smaller feet, is less firm ; 
 but ought we, from that circumstance, to infer, with the most eloquent 
 writer of the eighteenth century, that this diminutive size of the foot 
 is connected with the necessity of her being overtaken in flight ? The 
 concave form of the sole of the feet, by enabling them better to adapt 
 themselves to the unevenness of the soil, concurs in giving a firmer 
 footing in walking, and in other motions of progression. There is, in 
 walking, an intermediate moment, between the beginning and end of a 
 step, during which the centre of gravity is in the air : this lasts from 
 the moment when the centre of gravity is no longer in the foot which 
 remains behind, till it returns into the other foot which is carried 
 forward. 
 
 Walking is modified according as it takes place on an horizontal 
 or an inclined plane ; in the latter case we ascend or descend, and the 
 exertion is much more fatiguing. To explain the action of ascending, 
 let us suppose a man at the bottom of a flight of stairs, which he 
 wishes to go up ; he begins by bending the articulations of the limb 
 which he is desirous 'of carrying forward ; he raises it thus, and 
 shortens it to advance ; and when the foot, which is in a state of semi- 
 extension, rests on the ground, he extends the articulations of the 
 other extremity, carries thus the body upward in a vertical direction, 
 and completes this first step by contracting the extensors of the leg 
 that^were first in action, so that they may bring forward and restore to 
 it the centre of gravity, to which the posterior leg, whose foot is 
 extended, has given a vertical motion of elevation. Hence, in ascend- 
 ing, the calves of the legs and knees, especially the latter, are so much 
 fatigued; for the effort with which the extensors of the foremost leg 
 bring back again upon it the centre of gravity, is more powerful than 
 that by which the gemelli and the soleus impart to it, by extending the 
 hindmost foot, a motion of vertical elevation. 
 
 To relieve the extensors of the leg, we bend the body forward as
 
 422 OF PROGRESSION. 
 
 much as possible ; we lean back, on the contrary, in descending a 
 flight of stairs, or a rapid slope, in order to slacken the motion by 
 which the body, yielding to its own weight, falls on the leg that is 
 carried forward. 
 
 At the moment when the centre of gravity is no longer within the 
 base of sustentation, all the powers Unite in action, that it may fall as 
 little as possible from a vertical direction. The glutsei steady the 
 pelvis and straighten the thigh, and the lumbar muscles extend the trunk 
 on the pelvis ; hence, in going down a slope, the loins get so much 
 fatigued. We are less fatigued in going down hill, when the slope is 
 moderate, than in going up hill, as the force of gravitation, or the 
 weight of the body, assists considerably the descending vertical motion. 
 The motion of walking, when we take very long steps, resembles that 
 of going up hill, as the body being lowered every time the legs are 
 much apart, requires [to be elevated at each step towards the fore- 
 most leg. 
 
 At every step we take, the articulation of the leg with the foot ts 
 the principal seat of an effort, to which physiologists have not paid 
 any attention. The whole weight of the body is supported by the 
 action of the levator muscles of the heel, and the astragalus supports 
 this weight, which varies according to the corpulence of the person 
 and the burthen with which he is loaded. The weight of an adult, 
 of common stature and of moderate size, may be estimated at about 
 150 pounds, but which sometimes, in corpulent people, amounts to 
 between 4 and 500 pounds. If, then, to the weight of the body 
 there be added that of the burthens which it may support, it will 
 be conceived how immense the efforts must be which are, as it were 
 unconsciously, carried on in the articulation of the foot with the leg. 
 But how numerous the resources which nature has provided to over- 
 come this great resistance! how many the circumstances she has 
 happily combined to accomplish this without fatigue ! In the first 
 place, the foot in this action represents a lever of the second class, and 
 this lever, it is well known, is the most advantageous, the resistance 
 being always nearer to the fulcrum than the power, and the arm, by 
 which the latter acts, consisting of the whole length of the lever. If 
 you attend to the mechanism of the different parts of the skeleton, you 
 will no where find so powerful a lever applied in so favourable a 
 manner. The os calcis, by carrying the foot beyond its articulation 
 with the leg, adds likewise to the length of the lever by which the 
 power acts. Its length has considerable influence on our strength, on 
 our power of taking, without fatigue, long walks, or engaging in exer- 
 tions requiring considerable muscular force in the lower extremities. 
 The negroes, who excel in running, in dancing, and in all gymnastic 
 exercises, have a longer and more projecting heel than Europeans.
 
 OF PROGRESSION. 423 
 
 They dance best whose tendo Achillis is most detached, that is to 
 say, projecting, and at the greatest distance from the axis of the leg ; 
 which implies that its lower attachment is carried back by the prolong- 
 ation of the os calcis. 
 
 Those who have a short heel have a long and flat foot : this con- 
 formation, which when marked is faulty, is not only unfavourable to 
 beauty of form, but is, besides, remarkably injurious to the strength of 
 the lirnb as well as to freedom of motion. Men with flat feet are 
 always bad walkers ; hence this flattened form, when very consider- 
 able, is viewed as unfitting a man for military service. Lastly, the 
 term denoting this physical imperfection (pieds plats) is accounted 
 insulting in the French language, as well as in several others. But let 
 us go on with our inquiry into the advantageous disposition of the arti- 
 culation of the foot with the leg, for facility in walking, and in the 
 different motions of progression. 
 
 We have seen that the tendons are generally inserted at a very acute 
 angle into the bones on which they act : in the present instance, how- 
 ever, the insertion takes place at a right angle; the common tendon of 
 the muscles of the calf of the leg joining the os calcis at the angle 
 most favourable to their freedom of action. With the exception of the 
 muscles which move the head and lower jaw, no others are so evidently 
 disposed with this purpose. Nature has not been contented with 
 forming the foot in such a manner as to afford the most advantageous 
 lever, to which the moving powers are applied, at the greatest possible 
 distance from the fulcrum, and at the angle most favourable to their 
 action ; she has further increased the efficacy of this action, by adding 
 extraordinarily to the number of muscular fibres. There is not in the 
 body a stronger muscle than the soleus, whose short and oblique fibres 
 between the two wide aponeuroses which cover its anterior and pos- 
 terior surfaces, are more numerous than in any other muscle, as may be 
 conceived by considering the extensive surfaces to which they are 
 attached. Besides, the tendo Achillis is kept in a due degree of 
 straightness by the aponeurosis of the leg behind it. 
 
 Every thing in the powers, as well as in the levers, is formed so as to 
 overcome the resistance without difficulty ; that is, so as to raise the 
 weight of the body by the extension of the foot, the end of which rests 
 on the ground, in every motion of progression. 
 
 This immense power with which the muscles of the calf of the leg 
 act to raise the heel, and to support the whole weight of the body 
 resting on the astragalus, accounts for the possibility of transverse 
 fractures of the os calcis, and for the rupture of the tendo Achillis 
 notwithstanding its great thickness; and should lead one not to allow 
 patients, after such accidents, to walk freely for several months, the
 
 424 OF RUNNING. 
 
 substance which unites the parts being liable to rupture, as is known 
 to have been the case in several instances. This same arrangement of 
 parts likewise accounts for an accident, which physiologists have long 
 endeavoured to explain by a very unsatisfactory theory. 
 
 It not unfrequently happens that the mere effort of walking occa- 
 sions a rupture of some of the fibres 'of the gemelli and of the soleus, 
 in consequence of which there comes on pain, attended with induration 
 of the muscles, and with a certain degree of ecchymosis, occasioned 
 by the extravasation of blood. Pathologists suppose these symptoms 
 to depend on a rupture of the plantaris muscle : this rupture, however, 
 is hypothetical, has never been proved by experience to exist, and its 
 supposed symptoms are altogether idle and fallacious. 
 
 I could, if it were not out of place, bring forward several cases of 
 this affection : in all the cases which have come under my own observ- 
 ation, the use of the bath, of emollient and slightly narcotic poultices, 
 but, above all, continued rest, while the symptoms lasted, have appeared 
 to me the most appropriate remedies. 
 
 CLXXXVIII. Of running, In running, the foot that is hind- 
 most being raised before that which is foremost being firmly applied 
 to the ground, the centre of gravity is for a moment suspended, and 
 moves in the air, impelled by the force of projection, the action of 
 which principally constitutes leaping. 
 
 The mechanism of running is a compound of that of walking and 
 leaping, but resembling most the latter; hence some authors have 
 defined it to consist of a succession of low leaps. The steps are not 
 longer than in walking, but merely succeed each other with greater 
 velocity. The centre of gravity is transferred with more rapidity from 
 one leg to the other, and falls are much more apt to take place. The 
 quick repetition of the same motions in running requires a very lively 
 contractility in the muscles which move the extremities; and as the 
 energy of this vital property is proportioned to the extent of respira- 
 tion, and to the quantity of air which the blood acquires in passing 
 through the lungs, in running we pant and breathe frequently, and at 
 short intervals, without/any particular enlargement of the chest at each 
 act of respiration. It was necessary that the parietes of this cavity 
 should, in running, be remarkably fixed ; for it becomes the point on 
 which those muscles are inserted which steady the pelvis and loins, 
 and prevent their yielding an unsteady basis to the lower extremities. 
 The best runners are those who have the strongest lungs, that is, who 
 can give to the chest the greatest degree of permanent dilatation. In 
 contending for the prize in running, you may see them throw back 
 their head and shoulders, not only to obviate the propensity which 
 there is in the line of the centre of gravity to fall towards the anterior
 
 OF LEAPING. , 425 
 
 plane, but likewise that the cervical column, the scapulae, the clavicles, 
 and the humerus, being fixed, may furnish a firm attachment to the 
 auxiliary muscles of respiration. 
 
 We should run with much less speed if we applied to the ground 
 the whole sole of the foot, partly from the time which would be taken 
 up in thus applying the foot to the ground, and partly by the friction 
 which would necessarily take place. Hence in running we generally 
 touch the ground only -with the end of the foot. We run with most 
 speed when the foot is in a state of extension, the leg being moved 
 rapidly by the extensors of the knee. This accounts for the tendency 
 which there is to fall while we run, the centre of gravity obeying 
 impulses which follow each other in rapid succession, and never resting 
 but on a basis of very limited extent. Another reason why the slightest 
 unevenness of the ground is apt to occasion falls in running is, that the 
 rapid motion communicated to the body by the sudden and perpetually 
 recurring extensions of the posterior extremity, increases at every step, 
 so that it is impossible to stop suddenly, and without having previously 
 slackened one's pace, and moderated the impulse to which the body is 
 subjected. 
 
 As it is mostly forward that falls are apt to take place, in running 
 we always throw back the head, and make use of our arms to balance 
 the body, so that they may be in constant opposition to the legs ; that 
 is, that the right lower extremity, for example, being carried forward, 
 the left arm may be balanced backward. 
 
 Few animals are better formed than man to run with speed : his 
 lower limbs are in length equal to one-half of the whole length of the 
 body, and the muscles which move them are very powerful : hence 
 savages, who are in the constant habit of running, overtake the animals 
 which they make their prey ; and even in Europe there are professed 
 limners who equal in swiftness the fleetest horse. This animal, like 
 every other swift quadruped, would move much more slowly than man, 
 on account of the number of the limbs on which he rests, if he had not 
 the power of moving them in pairs, and thus reducing his legs to two, 
 as in what is called full gallop. 
 
 CLXXXIX. Of leaping. Leaping, in man, is performed princi- 
 pally by the sudden extension of the lower limbs, whose articulations 
 were in a. previous state of flexion. The alternate angles of the foot, 
 of the knee, and hip, disappear, and the extensors contract in almost a 
 convulsive manner. This straightening is not limited to the lower 
 limbs in violent leaping; it likewise affects the vertebral column, 
 which acts as a bow in unbending. Professor Barthez, who has the 
 merit of having suggested this explanation, which Borelli and Mayow 
 had very imperfectly understood, perhaps goes too far in considering
 
 426 OF LEAPING. 
 
 as imaginary a power of repulsion in the ground. This re-action, 
 admitted by Hamberger and by Haller, clearly operates when we leap 
 on an elastic floor ; it enables tumblers to rise, without much effort, on 
 the rope which bears them. But though all physiologists do not admit 
 that in leaping there is a re-action from the ground, it is universally 
 admitted that there must be a certain resistance from the ground on 
 which we tread. In fact a moving sand, yielding to the pressure of 
 the body, would, by giving way to a considerable degree, render it 
 impossible to leap. The instantaneous contraction of the extensor 
 muscles is so powerful in extending the lower extremities, and in com- 
 municating to the body a power of projection, so as to raise it, that 
 frequently during this effort the tendons of these muscles, or even the 
 bones into which they are inserted, break across. It is on this account 
 that dancers are very apt to fracture their patella. This accident hap- 
 pens at the moment when their body, in rising from the ground, is 
 powerfully (Jevated to a certain height. 
 
 If leaping consists merely in the sudden straightening of the lower 
 extremities, whose articulations are bent in alternate directions, it must 
 be more considerable according as these are longer, more bent on one 
 another, and as the muscles which straighten them contract more 
 powerfully. Hence animals that move by leaps, as the hare, the 
 squirrel, and the jerboa, have posterior extremities of considerable 
 length in proportion to their fore legs. Their different parts are, 
 besides, capable of considerable flexion. All these animals, strictly 
 speaking, are incapable of walking or running, and they move by leaps 
 or bounds succeeding each other with different degrees of rapidity. 
 Some, however, as the rabbit and the hare, are capable of running 
 when climbing up a steep place, as the slope in this case lessens the 
 effect of the impulse communicated by the extension of the posterior 
 limbs; an impulse which, from the strength and length of these extre- 
 mities, throws the whole weight of the body on the fore legs, which 
 are weaker and shorter, with such a degree of force, that the animal is 
 obliged to stiffen these and to keep them straightened, and in a state 
 of extension, to avoid striking the ground with his head while leaping 
 on an horizontal plane. Frogs, but especially grasshoppers and fleas, 
 between whose hind extremities and the rest of the body there is the 
 greatest disproportion, astonish us by the very considerable space which 
 they can clear at a leap; but the wonder ceases, when we consider that 
 powers communicate to the masses equal degrees of velocity, when pro- 
 portionate to one 1 another : now, the space gone over depending entirely 
 on the velocity, since the body that leaps loses, by a gradation which 
 nothing can lessen, that which it had acquired, these motions must be 
 nearly alike in small and in large animals.
 
 OF LEAPING. 427 
 
 Swammerdam says, that the height to which grasshoppers rise in 
 leaping is to the length of their body as 200 to 1. A flea leaps still 
 farther and more swiftly.* 
 
 The larva called the cheese maggot forms itself into a circle by 
 contracting, as much as possible, its abdominal muscular fibres : after 
 having, in this manner, brought near to each other its head and tail, it 
 suddenly extends and straightens itself, and thus springs forward a 
 considerable distance. It is by a similar mechanism that the salmon, 
 the trout, and other fishes, swim against rapid currents interrupted by 
 waterfalls. They bend their body to a considerable degree, straighten 
 it powerfully, and thus overcome the obstacle which opposes their pro- 
 gress. I believe, however, that in this particular case the leap is not 
 effected solely by the straightening of the elastic curve, as is main- 
 tained by some authors, but that it is likewise occasioned by the resist- 
 ance against the water of the tail of the fish, which strikes it power- 
 fully at the moment of raising itself; in the same manner as, in the 
 northern seas, the enormous whale strikes with so sudden and violent 
 a blow of her tail against the water, as to receive from it a fixed point, 
 and rise to the height of fifteen or twenty feet, as we are informed by 
 navigators. Lobsters leap by violently extending their tail an elastic 
 and contractile arch, which they had previously kept bent under their 
 body. 
 
 This theory of leaping would seem to be contradicted by what 
 is related by Professor Dumas, of a man without thighs, and who, 
 nevertheless, performed surprising feats of dexterity and agility. But 
 in this instance might not the pelvis, the vertebral column, and espe- 
 cially the lumbar portion of the latter, make up, by a greater mobility, 
 for the want of the longest of the three levers formed by the lower 
 extremity ? 
 
 In the act of leaping, the body, which has received the impulse, 
 may rise in one or two ways perpendicularly to the horizon, which con- 
 stitutes the vertical leap, or in a direction more or less oblique. The 
 vertical leap is always of less extent than that which takes place in an 
 inclined direction, and the latter is always greater when it has been 
 preceded by running. In running before leaping we have already 
 acquired an impulse which is added to that which the mechanism of 
 leaping may produce. 
 
 To convince ourselves of the reality of this additional power, let 
 us recollect how difficult it is to stop suddenly in the midst of a race, 
 
 * Barthez states, in his work on mechanics, that the Arabs call this little insect 
 the father of leaping; and that Roberval, a natural philosopher of considerable 
 merit, had written a work entitled De Saltu Pulicis. Such a subject, thought by 
 the ignorant to supply matter only for idle and fruitless speculation, may furnish 
 results highly interesting, when treated by an able man. In tenui labor.
 
 428 OF SWIMMING. 
 
 I 
 
 if we have not previously slackened our pace. This impulse is one of 
 the causes which makes runners fall forward when the slightest obstacle 
 meets their feet ; but whatever may be the force, the direction of leap- 
 ing, and the powers which produce it, the body by which it is executed 
 must be considered as a real projectile, that is impelled by a motion 
 counteracted by the force of gravitation. Whatever motions we may 
 perform, every thing depends on the first impulse ; as soon as the feet 
 .cease to be in contact with the plane which supports them, it is no 
 longer in our power to augment the force of the leap, or its swiftness. 
 In dancing, it is impossible to excel in cutting capers, unless one is 
 capable of rising to a certain height. I have uniformly observed, that 
 in the most celebrated public dancers the trunk, and especially the 
 lower limbs, are very muscular ; the calf of the leg, the buttocks, and 
 the back, indicate, by their bulk, a remarkable degree of energy in the 
 extensors, by whose action leaping is chiefly effected. 
 
 A dancer who rises vertically, falls back to the ground when the 
 force of gravitation exceeds the impulse which he had received: his fall 
 resembles that of a projectile in vertical motion ; it takes place accord- 
 ing to a descending line that is perfectly similar in direction and 
 height to the ascending line. 
 
 The same thing takes place in the oblique leap, except, however, 
 that the body, like a shell projected by the explosion of gunpowder, 
 describes a parabolic curve, ascending as long as the impelling power 
 exceeds the force of gravitation; descending, when the latter, which 
 increases during the progress of the leap, is equal to the force of the 
 impulse. This takes place when the body has described a curve which 
 represents the half of a parabola: from that moment the force of gravi- 
 tation goes on increasing, and the body descends in a curve corre- 
 sponding to the first.* 
 
 CXC. Of swimming. Few animals have more difficulty than 
 man in supporting themselves on the surface of a fluid ; yet the weight 
 of the human body exceeds but little that of the same bulk of water ; 
 sometimes, even when the body is loaded with much fat, its spe- 
 cific gravity and that of water are the same. Hence it is observed, 
 that corpulent men swim with less effort, but the weight is not equally 
 distributed over every point of the supporting fluid. The head, whose 
 relative weight is very considerable, is the principal difficulty in swim- 
 ming, and it requires some effort to keep it raised so as to allow the air 
 to enter freely into the lungs through the mouth and nostrils. The 
 upper and lower limbs act alternately against the water, which they 
 displace by pressing on it. In these various motions there is a succes- 
 
 * In sallu ad fiorizcntem obtigno, motus fit per lineam parabolicam projiimc 
 
 Op, cit. Prop. 17& >Vid. Galileo on the motion of projectiles;
 
 OF SWIMMING. 429 
 
 sive flexion, extension, abduction, and adduction of the limbs : most of 
 the muscles of the body are in motion, and have their fixed point of 
 action in the chest, which swimmers keep expanded by retaining, by a 
 constriction of the glottis, a considerable quantity of air within the 
 pulmonary tissue. This continuous dilatation of the chest is attended 
 with this further advantage, that it renders the body specifically 
 lighter. The force with which the swimmer is obliged to strike the 
 water, the rapidity with which the motions must succeed each other, 
 that the fluid may yield him a sufficiently fixed point of action, 
 accounts for the fatigue with which this exertion is attended. 
 
 Fishes are adapted, by their structure, to the element in which 
 they live the form of their body, bounded every where by salient 
 angles, is well calculated to separate the columns of a fluid. A 
 bladder filled with azote, which is expelled at pleasure, renders their 
 specific gravity less than that of water, according to the quantity of 
 gas it contains ; lastly, their tail, moved by powerful muscles, may be 
 considered as an oar of great strength, the motions of which impel the 
 fish forward, while the fins, like so many secondary oars, facilitate and 
 direct his motions. 
 
 The air-bladder of fishes gives to their back a sufficient degree of 
 lightness to enable it to remain upward, else this part of the body, 
 which is the heaviest, would draw after it the rest, and the animal, 
 lying on his back, would be incapable of performing any motions of 
 progression : this happens when this bladder is burst or punctured. 
 Constrictor muscles expel the gas which it contains, and force it into 
 the stomach, or oesophagus, when the animal wishes to sink. This 
 expulsion becomes impracticable, if the gas undergoes considerable 
 expansion from the application of heat, and resists the compression 
 that is applied to it. Hence, during the fry-time, fishes, after re- 
 maining long on the surface of the water, exposed to the heat of the 
 sun, become unable to sink, and are easily caught.* 
 
 As the fish is entirely surrounded by a medium which presents 
 on every side an equal resistance, the velocity which he might have 
 acquired, by striking the fluid behind with his tail, would be lost, from 
 the resistance, of the water which he would have to displace forward, 
 
 * The nature of the air contained in the air-bag of fishes was investigated by 
 Priestley and Fourcroy, and lately by M. Biot. According to the accurate and 
 extended experiments of the last-named inquirer, it would appear to consist 
 entirely of oxygen and azote. The proportion of these gases vary according to the 
 species of fish and depth at which they are caught ; that of oxygen increasing with 
 the depth of water, from an almost insensible quantity until it amounts to 87 parts 
 in a 100 of the whole air. It would appear, from the experiments of M. Biot, that 
 this air is a secretion from the sac which contains it. J. C.
 
 430 OF FLYIXG. 
 
 if, immediately after striking with his tail, he did not bring it back into 
 a straight line, so as to present to the fluid only the inconsiderable 
 breadth of his body : the velocity with which he moves is, besides, 
 very inferior to that with which he uses his tail. This part being- 
 brought into a straight line, the fish contracts it to its smallest 
 dimensions, at the same time that he brings it to the other side ; he 
 then expands it and strikes the fluid in a contrary direction, in a line 
 between the two oblique impulses which both strokes have given to it. 
 The fish turns horizontally, and directs himself towards the side he 
 chooses, by striking more powerfully, or with greater quickness, on 
 one side than on the other, or by striking only on one side. 
 
 Fishes without an air-bladder are reduced to live at the bottom of 
 the water, unless they have a flat body, and are furnished with 
 horizontal fins, so as to enable them to strike a considerable surface of 
 water, in a powerful manner, as is the case with rays, whose wide fins 
 are not inaptly termed wings ; the motion of these fishes in the water 
 precisely resembling that of birds in the air, with no other difference 
 but that of the different density of the medium in which they move, as 
 will be shewn in treating of the motions of progression peculiar to this 
 class of animals. 
 
 CXCI. Of flying. A bird, in rising or in moving in the air, has 
 to use much more force, and with much greater velocity, than a fish in 
 swimming. He has not the power, like the latter, of placing himself in 
 equilibria with the fluid in which he moves, by means of an internal 
 organ that renders his specific gravity equal to that of the medium he 
 is in. This medium, besides, presents less resistance to the powers 
 which strike it to obtain a point of support. 
 
 Though birds are incapable of becoming as light as the air, it 
 is, however, in their power to obtain a specific gravity not much 
 exceeding that of the atmosphere. Nature has rendered them very 
 light by providing them with very capacious lungs, capable of great 
 dilatation, from the remarkable mobility of the parietes of the chest, 
 and by extending the lungs into the abdomen, by means of mem- 
 branous sacs, and into the skeleton by means of canals, which 
 establish a communication of these abdominal and osseous serial 
 tubes with the pulmonary organ ; so that the whole body, distended 
 by air rarefied by a considerable degree of heat, since it is ten 
 degrees above that of other warm-blooded animals, clothed in feathers 
 almost as light as the air itself, requires but a moderate degree of 
 force to support itself in that medium. On the other hand, when the 
 wings are expanded, they present to the fluid a very extensive surface : 
 the pectoral muscles which set them in motion are, besides, sufficiently 
 strong to strike the air with a power, and to repeat the stroke with
 
 OF FLYING. 431 
 
 a rapidity and continuousness of which no other animal would be 
 capable. We know how powerful* the muscles of the wings are, even 
 in the tame fowl, which make so very little use of them. Lastly, the 
 contractility of these very powerful muscles is greater in birds than in 
 any other animal : no one possesses so much strength in so small a 
 compass. What quadruped, of the same weight as an eagle, could 
 strike with his foot so violent a blow as that bird, when, to stun his 
 prey or to defend himself, he gives repeated blows with his pinion ? 
 This muscular energy is, no doubt, connected with the extensive 
 respiratory organs, and with the highly stimulating qualities of a blood 
 that is warmer, more oxidised, more concrescible, in a word, more 
 arterialised, than that of any other animal. 
 
 Let us now inquire how birds, endowed with an organisation so 
 favourable to flying, perform that action. A bird begins by ascending 
 into the air, either by rising at once from the ground, or by allowing 
 himself to fall from a height. If on the ground, and if his wings are 
 too large to be freely spread, he has a difficulty in rising : in that case 
 he goes to an elevated spot and throws himself from it, that he may 
 have sufficient room to extend his wings and strike in the air the first 
 stroke that is to raise him. The wings expand horizontally, the 
 humerus, which forms their principal part, standing off from the body; 
 they then descend rapidly, and as the air resists the sudden effort 
 which tends to depress it, the body of the bird is elevated by a kind of 
 elastic re-action, corresponding to the leap of man, and to the 
 swimming of fishes; the impulse being given, the bird closes his wings, 
 and contracts his dimensions as much as possible, that the impulse may 
 be almost entirely employed in raising his body, and may not be 
 counteracted by the resistance of the air. This resistance of the air, 
 but particularly the weight of the bird, would soon overcome the 
 velocity that has been obtained, and he would drop, if, by again 
 striking the air, he did not again rise. If the bird strikes a second 
 time with his wings, before the impulse communicated by the first 
 
 * Birds have three pectoral muscles : the third, or lesser pectoral, is destined to 
 draw the humerus towards the body ; the great pectoral, which is attached to their 
 enormous sternum, and alone exceeds in weight all the other muscles of the bird 
 together ; and the middle pectoral, whose tendon turns over a kind of pulley, and is 
 attached to the head of the humerus, which it raises. By means of this mechanism, 
 Nature has placed an elevator muscle at the lower part of the body, so as to 
 increase the weight of this part of the bird, which f without this kind of ballast, 
 might have been upset iu the air. By these and other peculiarities in the 
 organisation of flying animals, the centre of gravity is always below the insertion of 
 the wings, and near that point on which the body is, during flight, suspended. 
 The positions, also, assumed by the head and feet, are often calculated to faci- 
 litate flight, and give to the wings every assistance in continuing progressive 
 motion J, C.
 
 432 OF CRAWLIXG. 
 
 stroke is over, he rises rapidly, but, on the contrary, descends, if this 
 motion is delayed. If he allow himself to fall only to the height 
 whence he began to rise, he may, by a continuance of equal vibrations, 
 keep at the same height. A bird sometimes ceases altogether to move 
 his wings, closes them against his sides, and falls with a precipitate 
 motion, like any other weighty body. The name of pouncing is given 
 to the rapid descent of predacious birds on their prey. Observe a 
 falcon drop suddenly on a poultry-yard : if, on the point of reaching 
 the ground he perceives danger, he immediately spreads his wings, and 
 thus saves himself from falling ; for, whatever velocity he may have 
 acquired in this rapid motion, the resistance of the air always increases 
 as the squares of the velocity : he then rises anew and takes to flight. 
 This peculiar act is called resource. 
 
 The oblique motions differ from the vertical motion which has 
 just been described, in this, that the bird rises by a series of curves, 
 which are more or less extended as the motion is more horizontal or 
 vertical. In consequence of the peculiar strength of their wings, birds 
 of prey have a very powerful horizontal motion, so that in soaring, the 
 curves which they describe are so slight that the motion seems quite 
 horizontal. 
 
 Swimming, to many birds, is a more natural mode of progression 
 than flying : these birds are very light, their body is covered with a 
 light down, and with feathers, over which the water glides very 
 readily ; their body is flattened, and rests on the fluid by a broad 
 surface; their pelvis is shaped like the keel of a ship; lastly, their 
 toes, united by webs, strike the water with a very broad surface. This 
 is the case with the numerous tribes of web-footed or water-fowl.* 
 
 They who have conceived it to be possible for man to support 
 himself in the air, by rendering his body specifically lighter, have not 
 considered that it is impossible to give to the muscles which move the 
 arms a sufficient degree of strength to enable them to moVe the 
 machines which are adapted to them ; and all who have ventured to 
 try such machines have suffered for their rashness. 
 
 CXCII. Of crawling. All the motions of progression, of which 
 man and animals are capable, may be referred to the theory of the 
 lever of the third kind. The body, in leaping as in walking, may be 
 compared to an elastic curve, since the point of support, or fulcrum, is 
 in the ground ; the force, the spring or power, in the extensor muscles ; 
 and the resistance in the weight of the body. What is running but a 
 succession of short leaps? and is not its mechanism intermediate 
 
 * The faculty of diving, &c. into a denser medium, possessed by some aquatic 
 birds, is exerted in the same manner as that of flying in the air. Swimming on the 
 surface of the water is performed entirely by means of the webbed feet of this class 
 of birds J. C.
 
 OF CRAWLING. 433 
 
 between walking and leaping? Are not flying and swimming real 
 leaps, in which the body of the animal alternately bends and unbends, 
 having its support on media of much less resistance than the ground, 
 on which walking, running, or leaping, are generally performed ? The 
 mode of progression peculiar to serpents and soft reptiles furnishes 
 an additional application of the lever of the theory of the third kind. 
 The snake, which moves by forming with its body horizontal and ver- 
 tical undulations, assumes, in the course of its length, a series of curves 
 and straight lines in succession, from the head towards the tail; but 
 sometimes likewise from the tail towards the head, in the serpents 
 called amphisbcenous, in which the scales covering the belly are equally 
 favourable to a retrograde motion as to a motion forward. 
 
 The crawling of serpents is facilitated by the length of their body, 
 by the smoothness of their scales, the immense power of their muscles, 
 and the flexibility of their vertebral column. The bones which form 
 this part of the skeleton are articulated by arthrodia, and loosely 
 jointed, so that a very slight cause destroys their union ; hence, a blow 
 with a very small stick is capable of killing the largest serpents, if 
 applied on the back. The lateral inflexions of this column are very 
 considerable ; the degree of extension is limited by the spinous pro- 
 cesses, and these are sometimes of considerable size, as in the rattle- 
 snake. Hence, notwithstanding what has been stated by several 
 authors, and_ although painters have represented serpents moving in 
 vertical curves, they move, in most instances, in horizontal curves. 
 
 A serpent, to swim, is obliged to bend and unbend his body in 
 more rapid succession : this swimming consists merely in crawling 
 faster, and in moving on a less resisting plane. 
 
 The motions of reptiles in swimming surpass in strength and 
 velocity those of reptiles which crawl on the ground, inasmuch as 
 the latter yields a more fixed point than water. If the serpent is de- 
 sirous of leaping, he suddenly, and at once, brings to a straight line 
 all his curves, resting at the same time on the extremity of that which 
 is nearest his tail ; then, as I have several times observed, he describes 
 the smallest possible number of curves, bends into three or four greater 
 arches than usual, but never into a single one, whatever the length of 
 his body may be. 
 
 Tortoises, frogs, lizards, salamanders, and all reptiles that have legs, 
 drag themselves along on their belly, being ill supported by their weak 
 limbs, which bear no proportion to the bulk of their body, and they 
 can scarcely be said to crawl by a mechanism similar to that which 
 has jiist been explained. 
 
 - Catef pillars and maggots crawl much in the same manner as ser- 
 pents. The legs of the caterpillar, too feeble to support it, or, of them- 
 selves, to carry the body forward, are used by these creatures to obtain
 
 434 OF PARTIAL MOTION'S. 
 
 a hold on the surface on which they move, by bending in arches, mostly 
 vertical, the parts situated between the legs, that are in pairs, at a 
 certain distance from one another. The caterpillars that have a scaly 
 covering crawl better, the elasticity of their scales assisting the con- 
 tractile action of their muscular fibres. Earth-worms move at times 
 in undulations as the snake, and at others by dragging themselves 
 like slugs. This last variety of crawling is performed as follows : 
 instead of forming distinct curves, the contractile fibres of the reptile 
 shorten themselves from the head, which is fixed, towards the tail, 
 which is movable, and the animal performs only slight inflexions. We 
 may compare the mode of crawling peculiar to some animals, to the 
 motion by which a man lying horizontally on his belly, moves for- 
 ward, by drawing his whole body towards his arms, which are in 
 a state of extension, and with which he has a hold of some fixed 
 object. The motion of the snail is performed almost entirely in the 
 same manner. 
 
 The snail, loaded with his shell, adheres to the surface on which 
 he moves by a viscid and glutinous fluid, which coagulates, and 
 forms on his track a shining varnish. This creature fixes itself like- 
 wise on the ground by forming a vacuum with the part of its body on 
 which it crawls, which is broad, fringed, and well adapted to answer 
 the purpose of a cupping-glass. It is by this double resource of a 
 viscid and glutinous fluid, and of a contractile exhauster, that the 
 snail fixes the fore part of his body, and then draws towards this 
 fixed part the rest of his body, loaded with the shell. This part of the 
 snail, by which it fastens itself to the ground on which it crawls, bears 
 some analogy to the tentacula which assist the progression of the 
 sepia and other cephalopodous mollusca. 
 
 CXCIII. Partial motions performed by the upper extremities. 
 These motions will furnish us additional illustrations of the elastic 
 curve, or of the third lever, to the theory of which may be referred 
 almost all the motions of man, and of the lower animals. This idea 
 simplifies and facilitates in a remarkable manner the study of animal 
 mechanics; it may be considered as a general formula, by the help 
 of which we may obtain a solution of all the problems of this in- 
 teresting part of physical science. Its application particularly distin- 
 guishes what has just been stated on motion, from what has been here- 
 tofore written on the same subject. 
 
 The upper extremities in man are not employed in motions of pro- 
 gression, at least not generally, except in a few instances, as, for 
 example, when the limbs being extended and the hands having a firm 
 hold of a body, the action of the great pectorals draws the whole body, 
 lying prone on a horizontal surface, or suspended. 
 
 We experience a difficulty in climbing, because our hands alon
 
 OF PARTIAL MOTION'S. 435 
 
 enable us to grasp the body on which this mode of progression is to 
 be effected, while the four extremities of the quadrumana and the sharp 
 claws of cats, and those of climbing birds, render this action easy 
 and natural to all these animals. 
 
 There exists so great a disproportion in point of length and 
 strength between our upper and lower extremities, that walking on all 
 fours can never be natural to the human species ; besides, as Dauben- 
 ton observed, the situation of the foramen magnum of the occipital 
 bone in man renders this attitude exceedingly uneasy. Its situation, 
 near the centre of the base of the skull, and nearly horizontal, prevents 
 the head from being raised sufficiently high to enable us to turn our 
 face forward and to see before us ; and if we bring the head downward, 
 it strikes the ground with its summit or with the forehead.* But 
 our upper or thoracic limbs, though of no use in conveying us whither 
 our wants require, are almost exclusively destined to perform motions 
 by which we act on the objects towards which we have brought our- 
 selves. 
 
 If we wish to push, or to draw towards us, or to propel afar, a 
 movable body, to compress, to elevate, or to lower it, our upper ex- 
 tremities are almost exclusively engaged in this office. 
 
 In pushing, man places himself between the obstacle and the 
 ground ; he bends his body between these two points, by bringing all 
 his limbs into a state of flexion ; he then extends them ; his whole 
 body represents a spring which is released and recovers itself, and the 
 two extremities of which, meeting two obstacles, the ground and the 
 body to which the impulse is to be communicated, exert their action 
 on the one of the two which is the more easily moved. The force is 
 equal to the contraction of the extensors, which elongate the body, 
 previously in a state of decurtation, and advance the movable obstacle 
 by the whole difference, in regard to length, of a man, whose limbs are 
 in a state of flexion, and of the same man while these parts are in a 
 state of extension. It is in the same manner, and by a similar me- 
 chanism, that, by pushing against the shore with an oar, we force a 
 boat from it. The vertebral column represents an elastic curve, that 
 straightens itself between the feet, which rest against the bottom of the 
 boat, and the end of the pole or oar, pushed against the shore or the 
 bottom of the water. 
 
 If, on the contrary, we wish to draw toward^ us a body, we seize 
 it with extended arms ; we then bend them forcibly : the spring, that 
 is in a state of tension, shortens itself, the effort is' wholly per- 
 formed by the flexors; it is less fixed, and of less duration than that 
 of the extensors, because the axes of the bones do not correspond 
 
 * Dictionnaire d'Histoire Naturelle de 1'Encyclopedie Mthodique. Introduc- 
 tion, page 21 suiv.
 
 436 OF PARTIAL MOTIONS. 
 
 to one another in a straight line, and because the action is generally 
 partial. 
 
 We can throw to a distance a projectile, the arm remaining pen- 
 dulous, and performing a mere oscillatory motion, or by a whirling 
 motion of the arm. This last action is much more powerful, because 
 the muscles which go from the trunk to the upper extremity concur in 
 it. In the former, the previous oscillations give to the arm a motion 
 which is peculiar to it, added to the force of muscular contraction, and 
 which augments the effect. 
 
 Professor Barthez was aware that the motions by which the upper 
 extremity stiffens itself, and assumes a state of extension, to project a 
 movable body, or to repel a resistance that is opposed to it, perfectly 
 resemble leaping, and are attended, like that action, with a sudden 
 extension of the joints which were previously bent. In motions applied 
 to a resistance that cannot be overcome, the body is not repelled with 
 the force communicated to it in leaping, by the abrupt extension of 
 the lower extremities. The scapula is too movable on the trunk, its 
 articulation with the humerus is too unsteady, and the action of this 
 bone is not directed, with regard to the shoulder, in a sufficiently fa- 
 vourable manner, to render the impulse equally great, even though the 
 powers should be equal, and they are far from being so. In every 
 repulsion and in every attraction, whether we bring towards us an object 
 or remove it from us, by acting upon it with our superior extremities, 
 these limbs represent an elastic arch, which is curved or straightened 
 by the action of its flexors or extensors ; and these motions, like the 
 greater number of those which we have hitherto considered, present a 
 precise application of the levers of the third kind. 
 
 The action of seizing a body with the hand, is facilitated, 1st, 
 by the action of the x radius on the ulna, which performs pronation and 
 supination, motions which belong exclusively to the hands, and of 
 which the feet are incapable; 2dly, by the mobility of the wrist, which, 
 properly speaking, is capable of flexion and extension in two directions ; 
 for the extension of the hand does not consist in merely bringing it 
 into a parallel line with the axis of the limb, but it is, besides, capable 
 of turning it round towards the back part of the fore-arm, a pheno- 
 menon not observable in any other articulation ; 3dly, by the obscure 
 motions on one another of the bones of the carpus, by which the palm 
 of the hand becomes more concave ; 4thly, by the motions of opposi- 
 tion and circumduction of the thumb and little finger ; 5thly, by the 
 great number of the phalanges: every thing in this part of the upper 
 extremity proves the excellence of its structure, and justifies all that 
 philosophers and naturalists have said of its advantages. 
 
 In applying pressure, for instance in pressing on a seal, nearly 
 the whole weight of the body bears on one of the upper extremities,
 
 OF PARTIAL MOTIONS. 437 
 
 which is powerfully extended, the shoulder resting on the arm, so that 
 the glenoid cavity of the scapula may be perpendicular to the head of 
 the humerus. 
 
 It would be a superfluous task to endeavour to describe all the 
 motions which our parts may execute : these partial motions are ex- 
 plained in anatomical works, in treating of the muscles on whose action 
 they depend. I shall content myself with having inquired into the 
 principal phenomena of animal mechanism, chiefly with a reference to 
 the human structure. Fuller details on animal mechanism would be 
 out of place in a work like this. They will be found in those works 
 which treat professedly* of this important part of physiology, the only 
 one in which it is possible to obtain, in the investigation of its objects, 
 that degree of mathematical certainty so much sought after by every 
 man of precision and of sound judgment. 
 
 Partial motions may yet further be studied as signs expressive 
 of ideas. They compose what is called the language of action, 
 and are supplemental to speech. The language of gestures, in its 
 perfection, is found sufficient even to express the most subtle ideas, 
 and the finest feeling, in the mute scenes known under the name of 
 pantomimes. The gestures with which the man of most phlegm ac- 
 companies his discourse, are a language superadded to that which he 
 speaks ; they contribute to the exposition of the thought: but what 
 force in the man of passion do they not add to his expression ! what 
 power to his language ! This eloquence of gesture, which was so often 
 employed to move and sway the assembled multitude in the public 
 place of Rome and Athens, was habitual to the orators of the antient 
 republics ; and the moment when Mark Antony uncovers and shews 
 to the Roman people the bloody corse of the first of the Caesars, is not 
 the least eloquent passage of his harangue. 
 
 Thus, although the organ of voice is that which offers us the 
 greatest abundance of resources for the expression of our ideas, for 
 communication with our fellow-creatures, though the hearing be the 
 sense to which we must address ourselves to produce in them distinct, 
 varied, and lasting impressions, we do yet address ourselves to their 
 touch and their sight when we would strongly move them by an ener- 
 getic declaration of our desires. Th^se three different languages are 
 employed at once, when we lead a man towards an object, and at the 
 same time point it out to him and bid him go there : touch and gesture 
 are then auxiliary to speech, and testify in him who makes use of them 
 a strong and resolute will. The motions of the eyes, the eye-brows, 
 
 * Consult J. A. Borelli de Motu Animalium, 4to. The "errors contained in this 
 work depend on the circumstance of the author's being more of a mathematician 
 than of an anatomist. 
 
 P. J. Barthez. Nouvelle Mcvhanifjue des Mouvemens de VHomme et des Animaunt,
 
 438 OF THE VOICE. 
 
 the eye-lids, the lips, and generally of all parts of the face, those 
 of the upper limbs, and of the trunk itself, serve to express our passions 
 as well as our ideas, are supplemental to the language of convention, 
 and often betray it by saying the reverse of what it expresses. The 
 study of gestures, of motions, and of attitudes, considered as signs of 
 ideas and passions, is the department of metaphysicians, of painters, 
 of sculptors, and physiognomists.* 
 
 CHAPTER IX. 
 
 OF VOICE AND SPEECH. 
 
 CXCIV. Of the Voice CXCV. Of Speech CXCVI. Of Singing and 
 
 Stammering. CXCVII. Dumbness and Ventriloquism. 
 
 CXCIV. Of the voice. The voice is an appreciable sound, result- 
 ing from the vibrations which the air, expelled from the lungs, meets 
 with in passing through the glottis. From this sound, articulated by 
 the motions of the tongue, the lips, and other parts of the mouth, is 
 produced speech, which mav be defined articulated voice. 
 
 All animals furnished with a pulmonary organ have a voice ; for it 
 is sufficient to the production of this sound, that air, collected in any 
 receiver, be driven out in a body with a certain force, and that it 
 meet on its passage with elastic and vibratory parts. Fish, that have 
 only trachea, utter no sound ; but this defect, which is certainly 
 an impediment to the extent and facility of their relations, is in part 
 made up by the extreme velocity of their progressive motion. 
 
 The instrument of the voice is the larynx, a sort of cartilaginous 
 box, placed at the upper end of the trachea. The thin and elastic 
 cartilages which form its parietes are united by membranes, and moved 
 on one another by many little muscles, called laryngeal. Of these five 
 cartilages, three only are concerned in the production of voice; these are 
 the arytsenoid and the thyroid. The epiglottis is of no other use than 
 to close on what we swallew the entrance of the windpipe ; whilst the 
 cricoid, situated at the lower part of the organ, serves it for a base, on 
 which the arytosnoid and the thyroid execute the motions by which the 
 opening of the glottis is contracted or enlarged, for the formation of 
 acute or grave tones. 
 
 * See Condilhic's Essay on the Origin of Human Knowledge ; Btiffon's Natunil 
 History of Man; Winkelman's, Treatise on Art; Lavater's Essays on Physiognomy, 
 with the important additions by 31. Moreau (de la Sarthe), iu the edition he has 
 just published.
 
 OF THE VOICE. 439 
 
 This slit, from ten to eleven lines long in an adult, and from two 
 to three wide where the width is greatest, is the most essential part 
 of the larynx. It is really the organ of voice, which is gone at once, 
 when, by opening the trachea or the larynx below it, the air is pre- 
 vented from passing through it. Speech only is lost when the wound 
 is above the place of the glottis ; which shews that voice and speech 
 are two distinct phenomena ; one taking place in the larynx, and the 
 other resulting from the action of divers parts of the mouth, and espe- 
 cially the lips.* 
 
 Are the different modifications of which the voice is susceptible 
 dependent on the width or narrowness of the glottis, or on the tension 
 or relaxation of the ligaments forming its sides ? Must we believe, with 
 Dodart, that the larynx is a wind instrument ; or, with Ferrein, that it 
 is a stringed instrument ? 
 
 It is very frue that the voice becomes stronger, fuller, and passes 
 from the acute to the grave, as the glottis enlarges with the progress of 
 age ; that it remains always weaker and sharper in a woman, whose 
 glottis is nearly a third smaller than a man's ; but the tension or relaxa- 
 tion of the ligaments which form the sides of the glottis, (the vocal 
 strings of Ferrein) may they not enable these ligaments to execute, in 
 a given time, vibrations more or less prolonged, and more or less rapid, 
 in such a manner, that if the air expelled from the lungs by expiration 
 strike upon them in the state of tension, produced by the action of the 
 crico-arytaenoedi postici, which carry back the arytsenoid cartilages to 
 which the ligaments of the glottis are attached, whilst the thyroid 
 cartilage, to which are attached the other extremities of the same 
 ligaments, is carried forward by a sort of tilting, occasioned by the 
 muscles connecting it with the cricoid cartilage (crico-thyroideus*), the 
 voice will be shrill, that is, clear and piercing; whereas it would be 
 grave if the arytsenoid cartilages, being brought forwards by the action 
 of the crico-arytaenoidei obliqui and thethyro-arytsenoidei muscles, the 
 vocal strings relaxed, executed less frequent vibrations ? 
 
 It has been objected to Ferrein, that to perform the office of vi- 
 brating strings, the ligaments of the glottis are neither dry, nor tense, nor 
 insulated, the three-fold condition required for the production of sound 
 in the instruments to which this anatomist has compared the larynx ; 
 but, for all the incompleteness of their resemblance to strings, the liga- 
 ments of the glottis, similar to the vibratory bodies, serving as mouth- 
 pieces to wind-instruments, such as the reed of the oboe, the mouth- 
 hole of flutes, the lips themselves in the horn, do not the less contribute 
 to the formation and varied inflexions of the vocal sound. It is the 
 
 * See APPENDIX, Notes M M. 
 
 t The arytrenoid muscle is used in the formation of acute sounds, for bringing 
 together the two arytaenoid cartilages.
 
 MO OF THE VOICE. 
 
 more difficult to set aside their influence altogether, inasmuch as their 
 state of tension coincides always with the contraction of the glottis ; 
 and, the two conditions producing the same effect, it is difficult to de- 
 termine if it be due to one rather than the other, as it is impossible to 
 decide whether it be to the enlargement of the opening, or to the 
 relaxation of the ligaments, that the' grave tones are owing. A last 
 reason, which, I think, should make the larynx be considered as serving, 
 at once the purposes of a wind and a stringed instrument, is, that the 
 ligature or section of the recurrent nerves which gives to its muscles 
 their contractility, takes away the voice; so that there is evidently 
 required some kind of action in the sides of the opening. 
 
 When we wish to speak low, we contract but slightly, or not at all, 
 the muscles of the larynx, whose action is entirely under the direction 
 of the will. The column of air meeting, then, in its passage along the 
 glottis, only relaxed parts, and little capable of vibration, the vocal 
 sound is no longer produced. The permanent extinction of the voice 
 must depend, in most cases, on palsy of the vocal or laryngeal 
 muscles. 
 
 It appears, then, that, rejecting the opposite and exclusive explana- 
 tions of Ferrein and Doclart, we are to consider the larynx as an 
 instrument combining the advantages, and exhibiting the double me- 
 chanism, of wind and stringed instruments: it is on this account that it 
 surpasses all musical instruments, by the extent, the perfection, and, 
 above all, by the inexhaustible variety of its effects. There is no one 
 that has heard, at a concert, a solo on the French horn by an able 
 performer, but has been struck with the resemblance of the sounds of this 
 instrument and those of the human voice. It is because the vibrating 
 body at the mouth-piece of the instrument is alive ; it is because the 
 lips, like the sides of the glottis, are movable, the opening of the 
 mouth dilates and contracts, and, at the same time, its edges are 
 relaxed or stiffened by the contraction of the muscles of the lips. 
 
 The modifications of the voice depend not only on the varied sizes 
 of the opening of the glottis, and of the contraction of the muscles of 
 the larynx, but, further, on the varying disposition of the parts forming 
 the pharynx, fauces, and mouth, as well as the length of the trachea. 
 The singer who runs down the whole scale of sounds, from highest to 
 lowest, visibly shortens the neck and the trachea, whilst in ascending 
 he stretches them out. 
 
 The force of the voice * depends on the volume of air that may be 
 expelled from the lungs at once, and on the degree of aptness in the 
 parietes of the canals by which it is given out. Birds, whose body is 
 
 * Sailors, and those that live on the banks of great rivers, have commonly strong 
 voices, from being obliged to overpower, with the voice, the noise of the waves, 
 which has constrained them to a great habitual exertion of its organs.
 
 ojb' SPEECH 441 
 
 all aerial, have a voice very strong for their bulk. Their trachea, 
 furnished with a double larynx, is almost entirely cartilaginous.* It is 
 especially so inv certain screaming birds, as the jay and some others ; 
 whilst it is nearly all membranous in the hedge-hog, a small quadruped, 
 whose cries are almost imperceptible. 
 
 The hissing of serpents, and the croaking of frogs, are heard to 
 some distance, because these creatures can send out a large quantity of 
 air at once from their vesicular lungs ; and in the latter, because the 
 vocal strings are completely insulated from the coats of the larynx, 
 with which in other animals they are continuous. 
 
 The voice of men is strong according to the capacity of the chest. 
 It is always weaker after meals, when the stomach and intestines, dis- 
 tended with food, push up the diaphragm and resist its descent. The 
 voice, formed by the passage of the air along the glottis, acquires 
 much force and intensity, and becomes much more sonorous, by the re- 
 verberations of the sound in the mouth and in the nasal cavities. It 
 is weakened and disagreeably impaired when a polypus of the nasal 
 canals, or of the throat, or the destruction of the roof of the mouth, 
 prevents the air from passing along the nasal canals and their various 
 sinuses. The voice is then said to be nasal, though, in truth, it suffers 
 from want of the modifications it should receive in the cavities belong- 
 ing to the nose. 
 
 CXCV. Of speech. To whisper, is to articulate very weak 
 sounds, which in truth deserve not the name of voice, since they 
 scarcely exceed the sound which always accompanies the passage of 
 air in expiration. Man only can articulate sound, and enjoys the 
 gift of speech. The particular disposition of the mouth, of the tongue, 
 and lips, makes all pronunciation impossible to quadrupeds. The 
 monkey, in whom these parts have the same conformation as in man, 
 would speak like him, if the air as it leaves the larynx were not 
 diffused into the hyothyroid cavities, which are membranous in some, 
 and cartilaginous and even bony in the howling monkey, whose cry is so 
 hoarse and melancholy. Every time that the animal would utter his 
 cry, these sacs swell, then empty themselves ; so that he is not able, at 
 will, to supply to the different parts of his mouth the sounds they 
 might articulate.* 
 
 Articulated sounds are represented by letters which express their 
 whole force. One cannot reflect on it all, without seeing what an 
 advance man made towards the perfection of his nature, when he 
 invented these signs for the preservation and transmission of his 
 thoughts. The vocal sounds are expressed by the letters called vowels^ 
 that is, to say, which the voice furnishes almost completely formed, 
 
 * Seethe Memoirs of M. Cuvier on the double larynx, and on the voice of birds, 
 f lu the ass an analogous structure is observed.
 
 442 OF SPEECH. 
 
 and which need, for their articulation, nothing more than the more or 
 less opening of the mouth, by the separation of the jaws and of the 
 lips. We pronounce, without effort, the letters A, E, I, O, U ; they 
 are the first the child utters ; they appear, besides, to cost him less 
 study than the consonants. These, which form the most numerous 
 class of the letters of the alphabet, seYve only, as their name indicates, 
 to bind together the vowels. Their pronunciation is always less 
 natural, and consequently more difficult. Accordingly, it is observed, 
 that the most harmonious languages, the most grateful to the ear, are 
 those which use fewest consonants and most vowels. It is in this point, 
 especially, that the Greek tongue surpasses all, ancient and modern ; * 
 that of dead languages, Latin holds the second place ; and, lastly, that 
 Russian, Italian, and Spanish, are more agreeable in pronunciation 
 than French, and still more than languages of Teutonic origin, as 
 English, German, Dutch, Swedish, Danish, &c. Among some 
 northern nations, all articulated sounds appear to issue from the nose 
 or the throat, and make a disagreeable pronunciation, no doubt 
 because it requires greater effort ; and he who listens sympathises in 
 the difficulty which seems to be felt by him who speaks. Would 
 it not seem that the inhabitants of cold countries have been led to use 
 consonants rather than vowels, because the pronunciation, not requir- 
 ing the same opening of the mouth, does not give the same room to 
 the continual admission of cold air into the lungs ? The gentle, pacific 
 nature of the inhabitants of Otaheite, and of the other Fortunate 
 Isles of the South Sea, is shewn in the words of their language, in 
 which are abundance of vowels ; whilst the hard and barbarous speech 
 of the Esquimaux, of the people of Labrador and New Zealand, is the 
 natural consequence of the rigour of their climate, the barrenness of 
 their soil, and their ferocious and warlike habits. 
 
 The distinction of letters into vowels and consonants has not been 
 thought sufficient ; they have been further distinguished, according to 
 the parts which are more especially engaged in the mechanism of 
 their pronunciation. Thus we mark the labial, oral, nasal, and lin- 
 gual vowels ; and semi-vowels, M, N, R, L, which bear different, 
 names, according as the tongue, in articulating them, strikes the roof 
 of the mouth, the teeth, or the lips : lastly, explosive consonants, K, 
 T, P, Q, G, D, B, P, and sibilant, H, X, Z, S, J, V, F, C, which 
 are more numerous and more frequently employed in languages of 
 more difficult pronunciation. If information on this subject could 
 be of real utility, I should explain the mechanism of the pronunciation 
 of every letter of the alphabet, at the risk of furnishing a new scene to 
 the Bourgeois Gentilhomme. 
 
 Gratis dedil ore rolundo 
 
 Mum (o</ui. HORAT.
 
 OF SINCilKG. 443 
 
 CXCVI. Of Singing.-*- Singing is nothing more than voice mo- 
 dulated, that is, running over with varying rapidity the different 
 degrees of the harmonic scale, passing from the grave' to the acute, 
 and from the acute to the grave, with expression too of the intermediate 
 tones. Though, in general, our song is spoken, speech is not necessary 
 to it. This action of the organs of the voice requires more efforts 
 and motions than speech : the glottis enlarges or contracts, the larynx 
 rises or descends, the neck stretches out, or is drawn in : inspiration is 
 accelerated, prolonged or slackened ; expiration is long, or short and 
 abrupt. Accordingly; all these parts are more fatigued than by 
 speech, and it is impossible for us to sing as long as we speak. 
 
 Whatever Rousseau may have said, in his Dictionary of Music, 
 singing may be regarded as the most natural expression of the emo- 
 tions of the soul, since the least civilised nations so use it, in their 
 songs of war and love, of joy and mourning ; and as every affection of 
 the mind modifies in some way the voice, music, which is only imitated 
 song, can by the aid of sounds paint love or rage, sadness or joy, fear 
 or desire, can produce the emotions of these different states, can thus 
 sway the course of our ideas, and direct at pleasure the operations of 
 the understanding and the acts of will.* Of all the instruments 
 which this art employs, the vocal organ of man is, indisputably, 
 the most perfect, that from which the most agreeable combinations 
 and the most varied may be obtained. Who is there that knows 
 not the property of the human voice to lend itself to all accents, and 
 to imitate all languages ? f I will observe on the occasion of song, 
 that it is especially consecrated to the expression of tender sentiments 
 or movements of passion, and that it is turning it aside from its 
 natural or primitive destination, to employ it in situations where no 
 emotion can be supposed. It is this that makes the recitative of our 
 operas so intolerably tiresome, and throws such ludicrousness over 
 dialogues where the speakers converse singing on the most indifferent 
 matters. Languages abounding in vowels are thereby fitted to song, 
 and favour the growth of musical genius. It is, perhaps, their smooth 
 and sonorous language that has given to the music of the Italians 
 its superiority over that of other countries. J Tl\e declamation of the 
 ancients was much more removed than our own from the common 
 
 * See Gretry, Essai sur la Musique, SfC. 
 
 f- See, in the Aviceptologie Fran^aise, or Art deprendre toutes sortes (TOiseauj, 
 the way in which they are drawn into snares by counterfeiting their song. 
 
 J This pre-eminence has been strongly contested, especially in France, where, 
 
 towards the middle of the last century, a war arose on the subject, in which her 
 
 - whole literature, split into two factions, fought for the superiority of Piccini and 
 
 Gluck. Out of the heaps of writings in verse and in prose with which the con-
 
 444 OF .STAMMERING AND DUMBNESS. 
 
 tone of conversation, approached nearer to music, and might be noted 
 like real song. 
 
 The pleasantness, the precision of the voice, the extent and variety 
 of inflexions of which it is capable, depend on the good conformation 
 of its organs, on the flexibility of the glottis, the elasticity of the car- 
 tilages, the particular disposition of the different parts of the mouth and 
 nasal canals, &c. It would be enough that the two halves of the 
 larynx, or the two nasal canals, were unequally developed, to prevent 
 precision and distinctness of voice. 
 
 Of stammering. Stammering is a vice of pronunciation too well 
 known to make it necessary to define it. A tongue too bulky and 
 thick, a remarkable diminution of irritability, as in drunkenness, at 
 the approach of apoplexy, and in certain fevers of a malignant kind, 
 the too great length of the frsenum of the tongue, by hindering the 
 readiness and ease of its motions, become causes of stammering ; or it 
 may be produced by the want or bad arrangement of several teeth. 
 The same causes, but especially the length of the frsenum of the tongue, 
 keep down this organ against the lower parietes of the mouth, and 
 hinder its point from striking the anterior of the roof of the mouth with 
 the quick stroke requisite for the pronunciation of the letter R. The 
 name of burr is given to the defect of speaking. 
 
 CXCVII. Of dumbness and ventriloquism. As for dumbness, 
 it may be either accidental or from birth. When by any accident, as 
 from a gun-shot wound, a cancerous tumour which has rendered 
 necessary the extirpation of part of the tongye, that organ, so far 
 destroyed, is no longer able to apply itself to the different parts of the 
 parietes of the mouth, and combine its motions with those of the 
 lips, then the person becomes dumb, that is to say, deprived of 
 speech. He has still voice, or the faculty of uttering sounds ; he may 
 even articulate, if he supply, by mechanical means, the parts of the 
 tongue, lips, or roof, the want of which hinders his pronunciation. 
 
 It is not so with the dumb from birth. Frequently all parts of the 
 mouth are perfect in their conformation, and yet the child cannot 
 attain to speech : such is the case of a little boy of three years and a 
 half old, who has been brought to me to divide his frcenum linguae. 
 Sometimes, however, the tongue adheres to the lower part of the 
 mouth, because the internal membrane of that cavity is reflected over 
 its upper surface long before it reaches the middle line of the inferior. 
 In other cases, the edges of the tongue adhere to the gums. 
 
 test was carried on, a few epigrams will be remembered, the letter of Rousseau 
 on French music, and the little work of d'Alembert on the liberty of music. Mar- 
 montel, too, has made these disputes the subject of an unpublished poem, under the 
 uanu- of Voyages de Polymnie.
 
 
 OF DUMBNESS. 445 
 
 Sometimes, also, the tongue is really paralytic : such was the case 
 of the son of Croesus, whose wonderful story is related by Herodotus.* 
 
 In the deaf and dumb from birth, the dumbness always arises from 
 the deafness : this, at least, is what M. Sicard has observed in the 
 great number of pupils committed to his care ; which has led him to 
 say, that in them the want of speech should bear the name not of 
 dumbness, but of silence. It is owing entirely to the absolute igno- 
 rance of sounds, and of their force represented by the letters of the 
 alphabet ; the organs of voice shew no trace of injury ; they are well 
 fitted for fulfilling the purposes to which they were allotted by nature ; 
 but they remain inactive because the deaf child cannot be taught to 
 use them. 
 
 It was necessary, therefore, as the ear was closed, to address to 
 other senses the speech he must endeavour to imitate. His eye must 
 be made to watch the motionsf of the lips and the tongue ; his hand 
 to feel the vibrations and the utterance of sound ; and thence he must 
 learn to use his organs of speech : this has been done. What Pereira 
 had begun, Sicard has brought to perfection ; and such command of 
 articulate sounds has been given to the deaf and dumb by birth, as has 
 enabled them to utter words and connected discourse. Even some- 
 thing of inflexion of strong and weaker tones has been taught them, by 
 using the arm as a regulator, as pedals are employed to modify the 
 touches of the piano-forte. 
 
 But instruction to the deaf and dumb must be given them by 
 another language. Written language they learn, not as a representa- 
 tive of speech, but as hieroglyphic characters for ideas ; and a manual 
 language, in which each letter is expressed by the position of the 
 fingers or hands, is used as a more convenient and rapid representation 
 of that hieroglyphic language of written characters. It is by this that 
 conversation with them is best carried on ; and it is with an ease and 
 rapidity which astonishes those who, for the first time, are witnesses to 
 the use of it. 
 
 Of ventriloquism. To conclude this chapter, I have still to speak 
 of a phenomenon, well worthy, by its singularity, of the attention of 
 physiologists. It is known under the name of ventriloquism, because 
 the voice, weak and little sonorous, appears to issue from the stomach. 
 There was at the Palais Royal, at the Coffee-house de la Grotte, a 
 man, who could carry on a dialogue so naturally, that you would think 
 
 * This is the author's solution of the story, not Herodotus's statement, who says 
 expressly the boy was deaf. But the conjecture is ingenious, and shews a possi- 
 bility in the story, which, as Herodotus tells it, is impossible J. C. 
 
 f It is known that old men, grown deaf, fix their attention very closely on the 
 motions of the lips, as well as on the varying expressions of the face, to see the 
 words as well as thoughts of those who are speaking. J. C.
 
 440 OF VENTRILOQUISM. 
 
 you were listening to the conversation of two people, at some distance 
 from one another, and quite different in voice and tone. I have 
 observed, that he was not inspiring while he spoke from his belly, but 
 that less air came from his mouth and nostrils than in his ordinary 
 speaking. Every time that he did so, .he found a swelling in the epi- 
 gastric region ; sometimes he felt wind moving lower down, and could 
 not go on long together without fatigue. 
 
 I had at first conjectured, that in this man a great part of the air 
 driven out by expiration did not issue from the mouth and nasal fossse, 
 but that being swallowed and carried down into the stomach, it struck 
 against some part of the digestive tube, and produced a real echo ; 
 but having since observed with the greatest care this curious pheno- 
 menon in M. Fitz-James, who exhibits it in the highest perfection, I 
 have satisfied myself that the name of ventriloquism no way suits it, 
 since its whole mechanism consists in a slow, gradual, attenuated expir- 
 ation, whether for that purpose the artist employ the power of the will 
 upon the muscles of the parietes of the chest, or whether he hold the 
 epiglottis slightly lowered, by means of the root of the tongue, of which 
 he scarcely brings the point beyond the dental arches. 
 
 I find this long expiration always preceded by a strong inspiration, 
 by means of which he introduces into his lungs a large quantity of air, 
 of which he afterwards husbands the use. Accordingly, repletion of 
 the stomach is a great hindrance to the action of M. Fitz-James, 
 by preventing the descent of the diaphragm which the chest would 
 require, to dilate itself for the full quantity of air the lungs should 
 receive. 
 
 By accelerating or retarding expiration, he can imitate different 
 voices, make it seem that the speakers, in a dialogue which he carries 
 on by himself, stand at different distances, and produce illusion the 
 more complete, the more perfect is his talent. No one equals M. Fitz- 
 James in the art of deceiving, in this respect, the most wary and suspi- 
 cious observer. 
 
 He can set his organ to five or six different tones, pass rapidly from 
 one to the other, as he does when he represents a very eager discussion, 
 in a popular society of the people, imitate the sound of a bell, and 
 carry on singly a conversation, in which one might think that several 
 persons, of different ages and sexes, were taking parts. But what 
 completes the illusion, and especially distinguishes the art of the ventri- 
 loquist from that of the mimic, who can only counterfeit, consists in 
 the power of so modulating his voice, that one is deceived as to the 
 distance of the speaker, in such sort, that one voice comes from the 
 street, another from a neighbouring apartment, that from one that had 
 clambered up the roof of the house, &c. It is easy to discern the 
 value of such a talent in the days of oracles.
 
 SECOND CLASS. 
 
 FUNCTIONS SUBSERVIENT TO THE PRESERVATION 
 OF THE SPECIES. 
 
 THOSE GENERATIVE FUNCTIONS WHICH APPERTAIN TO ' 
 BOTH SEXES.
 
 CHAPTER " X. 
 
 OF GENERATIO 
 
 " 
 
 V 
 
 :ON. 
 
 CXCVIII. Differences of the Sexes CXCIX. Of Hermaphrodism. CC. Of 
 
 Generation CCI. Of the Male Organs of Generation CCIL Of the Female 
 
 Organs of Generation CCIII. and CCIV. Of the Functions of the Generative 
 
 Organs. CCV. Of the Ovum and its Impregnation CCVI. Theories of 
 
 Generation. 
 
 CXCVfU. Differences of the sexes. The functions treated of in 
 this chapter are not necessary to the life of the individual ; but without 
 them the human species would soon perish, for want of the power of 
 reproduction : these functions, destined to preserve the species, are 
 intrusted to two kinds of organs, belonging to the two sexes, of which 
 they constitute the principal, though not the only difference. 
 
 Woman, in fact, does not differ from J.nan in her genital organs 
 merely, but likewise in her lower stature, in the delicacy of her organ- 
 isation, in the predominance of the lymphatic and cellular systems, 
 which softens down the projections of the muscles, and gives to all her 
 limbs those rounded and graceful forms, of which we see in the Venus 
 of Medicis the inimitable model. In woman, sensibility is also more 
 exquisite, and, with less strength, her mobility is greater. The female 
 skeleton, even, is easily distinguished from that of the male, by striking 
 differences. The asperities of the bones are less prominent, the cla- 
 vicle is less curved, the chest shorter but more expanded, the sternum 
 shorter but wider, the pelvis more capacious, the thigh-bones more 
 oblique,* &c. In a dissertation on physical beauty, read by Camper 
 to the Academy of Design, at Amsterdam, this celebrated physiologist 
 shewed, that in tracing the forms of the male and female body within 
 two elliptical areas, of equal size in both, the female pelvis would 
 extend beyond the ellipsis, and the shoulders be within ; while in man 
 the shoulders would reach beyond their ellipsis, and the pelvis be con- 
 tained within its limits. 
 
 The general characters of the sexes are so marked, that it would be 
 possible to distinguish a male merely by seeing a part of his body 
 naked, even though this part should not be covered with hairs, and 
 should have none of the principal attributes of virility. Should this 
 
 * Compare the beautiful plates of the male and female skeleton by Albinus and 
 Scemmering. 
 
 G G
 
 450 DIFFERENCE OF THE SEXES. 
 
 difference of organisation and character be ascribed to the influence of 
 the sexual organs upon the rest of the body ? Does the uterus impress 
 on the sex all its characteristic modifications, and is it just to say, with 
 Van Helmont, " Propter solum uterum mulier est, id quod est" the 
 uterus alone makes woman what she is? Though this viscus very evi- 
 dently reacts on the whole system of the female, and seems to draw 
 under its control nearly the whole of the actions and affections of 
 woman, I am, nevertheless, of opinion, that it is far from being the only 
 cause of her distinguishing characteristics, since these may be recog- 
 nised from the earliest period of life, when the uterine system is far 
 from having attained its full activity. A very singular fact, recorded 
 by Professor Caillot, in the second volume of the Memoirs of the 
 Medical Society of Paris, proves, better than all the reasoning in the 
 world, how much the character of the sex is independent of the influ- 
 ence of the uterus. A female was born and grew up with all the 
 external characteristics of her sex. At the age of twenty-one she 
 wished to yield to her desires, but found it impracticable ; there was 
 nothing beyond the vulva, in other respects well formed. A small 
 canal, between two and three lines in diameter, occupied the place of 
 the vagina, and terminated in a cul de sac, and was about an inch in 
 depth. The most accurate examinations, by introducing a sound into 
 the bladder, and the finger up the rectum, discovered nothing like the 
 uterus. With the finger in the rectum, the convexity of the sound in 
 the bladder could be distinctly felt ; so that it was evident, that 
 between the lower part of the bladder and the anterior part of the 
 rectum there lay no organ corresponding to the uterus. The young 
 woman had never been subject to the periodical evacuation which 
 accompanies or precedes the time of puberty. No haemorrhage sup- 
 plied the place of this excretion. She experienced none of the indis- 
 positions that are occasioned by the absence of menstruation ; she en- 
 joyed, on the contrary, the most perfect health ; and she was deficient in 
 none of the other characteristics of her sex, only that her breasts were 
 small. At the age of twenty-six or twenty-seven she became subject 
 to a pretty frequent evacuation of bloody urine. May not this affec- 
 tion, which recurred at irregular periods, be considered as a means by 
 which nature supplied the deficiency of the menstrual evacuation ? 
 The bladder, in that case, would fulfil the office of the uterus, and its 
 capillary vessels must have been considerably evolved. 
 
 The reproduction of the species is, in woman, the most important 
 object of life ; it is almost the only destination to which nature has 
 called her, and the only duty she has to fulfil in human society. 
 Wherever the earth is fruitful, and furnishes man with abundant means 
 of providing for his wants, he dispenses with the services of woman in 
 obtaining from it means of subsistence ; he releases her from the bur-
 
 OF HERMAPHRODISM. 451 
 
 then of social obligations. The Asiatic expects from the women he 
 maintains in his seraglio, in a state of inactivity, nothing but pleasures , 
 and children to perpetuate his race. The women of Otaheite have no 
 employment but pleasure and the duties of mothers. Among some of 
 the savage tribes of America, man, abusing the right of power, tyran- 
 nises, it is true, over woman, and, reserving to himself all the advan- 
 tages of social life, makes her bear all its weight ; but this exception 
 does not invalidate the general law deduced from observation of all 
 nations. Whatever withdraws woman from this primitive destination 
 whatever diverts her from this end, is to her injury : it is the scope of 
 all her actions and habits ; every thing in her physical organisation has 
 evident reference to it. Of all the passions in woman love has the 
 greatest sway ; it has even been said to be her only passion. It is true 
 that all the others are modified by it, and receive from it a peculiar 
 cast, which distinguishes them from those of man.* 
 
 We shall proceed no further into the examination of the general dif- 
 ferences which characterise the two sexes : no one has entered more 
 deeply into this subject, or has treated it m a more interesting manner, 
 than M. Roussel,in his work entitled, " Systeme Physique et Morale de 
 la Femme." 
 
 CXCIX. Ofhermaphrodism. Hermaphrodism, or the union of the 
 two sexes in the same individual, is impossible in man and in the nume- 
 rous class of red-blooded animals. There is on record no well-authen- 
 ticated case of such a combination ; and all the hermaphrodites that 
 have been hitherto met with were beings imperfectly formed, in whom 
 imperfect male organs, or female organs unnaturally enlarged, rendered 
 the sex dubious. None was ever found that had the power by itself of 
 begetting a similar being to itself: the greater number were incapable 
 of reproduction : the imperfection, or the faulty conformation of their 
 organs, condemned them to barrenness. Such was the case with the 
 hermaphrodite mentioned by Petit, of Namur, in the Memoirs of the 
 Academy of Sciences ; with that one whose case is related by Maret, 
 in the Memoirs of the Academy of Dijon; and with all those to be 
 found in the iccords of the Medical Society, which contain the greatest 
 number of facts of this kind. 
 
 But though in man, and in all beings that most resemble him in 
 their organisation, complet^hermaphrodism has never been met with, 
 it is a frequent occurrence among the white-blooded animals, and espe- 
 cially among the plants, that occupy the lowest part of the scale of 
 
 * Fontenelle used to say of the devotion of some women : " One may see that 
 love has been here.'" It has been said in speaking of St. Theresa : " To love God is 
 still to love." Thomas maintains that, " With women a man is mora than a 
 nation.' 1 '' " Love is but an episode in the life of man ; it is the whole history of (he 
 life of woman." MADAME DE STAEJ..
 
 452 OF bF.XKRATIOK IN MAN- 
 
 organised beings. The same is observed in polypi, in several kinds of 
 worms, in oysters, and snails. The latter present a singular variety of 
 hermaphrodism, in this, that the male and female organs being com- 
 bined in the same individual, it is still singly not capable of genera- 
 tion, but is obliged to copulate with another being, likewise an 
 hermaphrodite, so as to receive, from friction and other means of irri- 
 tation, the excitement to. the act of reproduction. 
 
 In the immense tribe of monoecia plants, the male and female organs 
 are combined on one stalk, and even sometimes within the same flower. 
 A number of stamina surround one or more pistils, shed on the stigma 
 their fertilising dust or pollen, which is conveyed along the canal of the 
 style into the ovary, there to impregnate the seeds by means of which 
 the species are perpetuated. The same vegetable species containing 
 sometimes male and female individuals, the sexes may be at consider- 
 able distances from one another; the seminal dust is in that case con- 
 veyed by the air from the male to the female. This is the case with 
 palm-trees, on which Gleditsch made his first observations on the 
 generation of plants, hemp, spinage, mercurialis, &c. 
 
 CC. Of generation in man. It is a distinction of the human spe- 
 cies, that in them the functions of generation are not under the influ- 
 ence of the seasons. The lower animals, on the contrary, draw toge- 
 ther and pair at stated periods of the year, and seem afterwards to 
 forget the enjoyments of love, that they may attend to their other 
 necessities. Thus, wolves and foxes copulate in the middle of winter, 
 deer in autumn, most birds in spring. Man alone seeks his partner at 
 all seasons of the year, and impregnates her under all latitudes and in 
 all temperatures. This privilege is not so much the consequence of his 
 peculiar constitution, as a result which he derives from his industry : 
 protected by the shelters which he constructs against the inclemency of 
 the seasons and the variations of the atmosphere, always capable of 
 gratifying his physical wants by help of the stores which his foresight 
 has led him to collect, he can at all times indulge in the enjoyments of 
 love. The domestic animals, which we have in great measure removed 
 from the influence of external causes, bring forth almost indiscrimi- 
 nately at all seasons of the year. To prove still further that it is from 
 counteracting, by the resources of his industry, the influence of nature, 
 that man has succeeded in resisting the influence of the seasons in the 
 reproduction of his species, I may observe, that this effect of tempera- 
 ture is more absolute the farther the species is from man : hence the 
 spawn of fishes and frogs is productive sooner or later, according to the 
 earliness or lateness of the seasons ; and thus a great number of insects 
 depend on the heat of the weather for their powers of reproduction, 
 and for their existence. 
 
 Aristotle, Galen, and their verbose commentators, have expressed
 
 MALE ORGANS OF GENERATION. 453 
 
 the analogy which subsists between the organs of generation in the two 
 sexes by saying, that they differ only in their position, being external in 
 man and internal in woman. There is, in fact, a considerable resem- 
 blance between the ovaria and the testicles, the Fallopian tubes and the 
 vasa deferentia, the uterus and the vesiculee seminales, the vagina, the 
 external organs of generation in women, and the male penis. The 
 former secrete the seminal fluid, and furnish in man or in woman a 
 matter essential to generation (ovaria and testicles). The Fallopian 
 tubes, like the vasa deferentia, convey this fluid into receptacles, where 
 it has to remain for some time (uterus and vesiculce seminales). These 
 contractile cavities, which serve as reservoirs to the semen or its pro- 
 duct, part with these substances when they have remained within them 
 a sufficient length of time. Lastly, the vagina and penis serve to expel 
 them. However striking such analogies may be, we are not justified 
 in inferring a perfect resemblance between the organs of generation in 
 the two sexes. Each of them fulfils, in the act of reproduction, func- 
 tions perfectly distinct, though of reciprocal necessity. 
 
 CGI. Of the male organs of generation. The prolific fluid is 
 secreted by the testicles : these organs are two in number, covered 
 by several coats, one of which, covered by the skin, and known 
 under the name of scrotum, resembles a bag, containing both these 
 organs : it contracts on the application of cold, is relaxed by heat, 
 and possesses a degree of contractility more evident than in the other 
 parts of the cutaneous tissue. The dartos forms a second cellular 
 envelope, common to each testicle. The tunica vaginalis, a serous 
 membrane, affords an immediate covering to them, and, reflecting 
 itself over their surface, is disposed with regard to them as the peri- 
 tonaeum with regard to the abdominal viscera; that is, it does not 
 contain them within its cavity. Lastly, the testicles are covered by 
 a fibrous, white, thick, and very consistent membrane : it is termed 
 tunica albuginea, from the inner surface of which there arises a consi- 
 derable number of membranous laminae, which, crossing one another 
 within its cavity, form cells containing a yellowish vascular substance. 
 This substance, contained within the tunica albuginea, has so little 
 consistence, that it would very soon be dissolved if the testicle were 
 stripped of its outer covering. It is formed by the seminiferous tubes, 
 which are small capillary vessels, extremely tortuous and coiled on 
 themselves, arising, probably, from the extremities of the spermatic 
 arteries, all directed towards the upper part of the oval formed by 
 the testicles joining in this place, and forming about ten or twelve 
 tubes, which unite into a cord situated within the tunica albuginea, 
 called the corpus Highmorianum. The ten or twelve ducts, which unite 
 into a fasciculus and form this cord, pass through the membrane within 
 which they are contained, unite into a single canal, which is convoluted, 
 and forms a substance called the epididymis. This canal, formed by
 
 454 MALE ORGANS OF GENERATION. 
 
 the union of the ducts of the corpus Highmorianum, at first convoluted 
 on itself, becomes less and less tortu6us as it approaches the lower 
 extremity of the testicle : there it bends back, and ascends, under the 
 name of vas deferens, along the spermatic cord as far as: the inguinal 
 ring, by which it enters the abdominal cavity. The vasa deferentia, 
 though of the size of a quill, have, nevertheless, a very small cavity; 
 and it is not easy to say why a capillary tube should have such thick 
 parietes, and nearly as hard as cartilage. 
 
 The semen, secreted by the testicles, is formed from the blood 
 conveyed to them by the spermatic arteries, long, slender, and very 
 tortuous vessels, arising from the aorta, at a very acute angle. This 
 fluid is filtered through the seminiferous tubes, passes into those of the 
 corpus Highmorianum, and thence into the vasa deferentia, which, 
 after they have entered the abdomen, terminate into the vesiculse semi- 
 nales, and deposit into them the spermatic fluid. The delicacy of the 
 organisation of the testicle, and the delicacy of the vessels along which 
 the semen is conveyed, account for its tendency to congestion, and for 
 the difficulty with which a resolution of this affection is obtained. 
 
 The spermatic fluid passes from the vasa deferentia into the vesi- 
 culse seminales, notwithstanding the retrograde direction of their 
 course. The cavities serving as receptacles to the semen resemble in 
 this respect the gall-bladder. Notwithstanding the unfavourable direc- 
 tion in which the ducts of the liver and of the testicles join their respec- 
 tive receptacles, they nevertheless convey their fluids into the latter ; 
 the bile, because the ductus choledochus is very much narrowed where 
 it passes through the coats of the duodenum, especially when this 
 viscus is .empty; the semen, because the duct along which it is con- 
 veyed, penetrating through the prostate gland, and opening into the 
 urethra by a very narrow orifice, flows back more readily into the 
 vesicufe seminales than from the vas deferens into the ejaculatory duct. 
 Thevesiculae seminales form two membranous receptacles, of differ- 
 ent capacity in different individuals larger in young people and adults 
 than in children and old people. Their cavity is divided into a number 
 of cells ; they are lined with a mucous membrane, which secretes, in 
 considerable quantity, a viscid humour that mingles with the semen, 
 increases its quantity, and serves as a vehicle to it. The situation of 
 the vesiculse seminales, between the rectum, the levatores ani, and the 
 posterior part of the bladder, promotes the excretion of their contents, 
 (which is chiefly brought about by the contraction of their parietes,) by 
 the compression of the levatores ani, which are in a state of convul- 
 sion at the moment of emission. Animals that are not provided with 
 these seminal receptacles, remain a considerable time in a state of co- 
 pulation, the prolific fluid necessary to impregnation having to be 
 secreted during the time that the copulation lasts, and flowing in 
 drops.
 
 FEMALE ORGANS OF GENERATION. 455 
 
 The ducts formed by the union of the vesiculee seminales with the 
 vasa deferentia, pass the prostate gland, and open, by separate orifices, 
 into the urethra, at the bottom of a lacuna, near the verumontanum. 
 The glandular body in which they are enclosed, and which contains 
 both the neck of the bladder and the beginning of the urethra, does 
 not exist in women. The mucous and whitish fluid, secreted by the 
 prostate, is conveyed by ten or twelve orifices into the urethra. This 
 prostatic fluid mingles with the semen, adds to its quantity, and is 
 perhaps emitted first, in order to lubricate the internal surface of the 
 canal, and prepare it for the passage of the seminal fluid, by rendering 
 the internal surface of the urethra more slippery. 
 
 The use of the urethra is, not only to convey the semen out of the 
 body, but likewise to serve in the excretion of the urine, and to form a 
 part of the penis. The latter, destined to convey the prolific fluid into 
 the female organs of generation, must be in a state of erection to per- 
 form this function completely. Erection being a phenomenon of 
 structure, that of the penis will be considered after the description of 
 the female organs of generation.* 
 
 CCII. Of the female organs of generation. I shall not adopt the 
 anatomical arrangement generally followed in this description, but, 
 classing in three divisions the different parts which in women are 
 subservient to the genital functions, I shall speak first of the ovaria 
 and Fallopian tubes, then of the uterus, and, in the last place, of the 
 vagina and external parts. 
 
 The ovaria, situated in the female pelvis, connected to the uterus 
 by a ligament, receive the vessels and nerves which in npnien are 
 sent to the testicles : they resemble in form the latter, but are some- 
 what smaller. Do the ovaria secrete a fluid, which, by mixing with 
 the male semen, produces the new being, or is there detached from 
 them, at the moment of conception, an ovum which the semen vivifies? 
 Whatever opinion is adopted, one is compelled to admit, that the 
 ovaria prepare a substance essential to generation, since females in 
 whom these parts have been extirpated are rendered barren. 
 
 It is, likewise, unquestionably, along these membranous tubes, 
 called Fallopian, that this substance, whatever it may be, furnished by 
 the ovaria, passes into the uterus, into which one of their extremities 
 opens ; while the other extremity, broad and fringed, lies loose in the 
 cavity of the pelvis, supported by a small duplicature of the peritonaeum, 
 but undergoes a state of erection, and applies itself to the ovarium, 
 during the act of coition, and forms a continuous canal between 
 that organ and the cavity of the uterus. The external orifice of the 
 Fallopian tube, called corpus Jimbriatum, has been found thus grasping 
 
 * See APPENDIX, Note N N.
 
 456 FEMALE ORGANS OF GENERATION. 
 
 the ovarium, in females opened immediately after coition. It may 
 happen, from a malformation of the parts, that the Fallopian tube may 
 not be able to apply itself to the ovarium. I dissected, at the Hvpital 
 de la Charite, the body of a woman who had been barren ; and found 
 the corpora fimbriata, or the expanded terminations of the Fallopian 
 tubes, adhering to the lateral parietes' of the pelvis, so that it was 
 impossible they should perform the motions required for impregnation. 
 
 The uterus, lying in the pelvis, between the rectum and bladder, is 
 a hollow viscus, in which the foetus grows till the period of birth. Its 
 internal part has been found separated into two cavities, opening in 
 some cases in the same vagina, and at others terminating in a vagina 
 that was double only in the immediate vicinity of the uterus. Valis- 
 nieri mentions the case of a woman who had a double uterus, the one 
 opening in the vagina, and the other communicating with the rectum. 
 Though the muscularity of the parietes of the uterus becomes manifest 
 in proportion as this organ enlarges during the progress of pregnancy, 
 this hollow muscle may be said to differ from other muscular organs 
 by the arrangement of its fibres, which it is difficult to discover while its 
 cavity is empty, and which it is even impossible completely to unravel 
 while it contains the foetus : its most remarkable distinguishing cha- 
 racter is its singular property of dilating and stretching itself, and, 
 at the same time, of gaining in thickness instead of becoming thinner. 
 
 The vagina is remarkable only by the soft, wrinkled, and easily 
 dilated structure of its parietes. The upper extremity of this oblique 
 canal, which is directed upward and backward, embraces the cervix 
 of the uterus, while its lower orifice is surrounded by a spongy body, 
 whose cells fill with blood and expel it, like the corpora cavernosa of 
 the penis and clitoris. It is called plexus retiforme ; its turgescence, 
 during erection, contracts the orifice of the vagina ; the contraction of 
 the constrictor muscles, which answers the purpose of the accelerator 
 urinse in man, and which lies over this plexus retiforme, surrounds, 
 like it, the entrance of the vagina, and may, in the same manner, con- 
 tract the orifice of this canal. 
 
 Besides, this external orifice is furnished, m women who have had 
 no connexion with men, with a membranous fold, varying in breadth, 
 generally semicircular, and called hymen. Its existence is considered 
 by many as the most certain sign of virginity. But all the marks by 
 which it has been attempted to obtain a certainty of the presence of 
 virginity are very equivocal.* The relaxed state of the parts,, from a 
 great quantity of mucus, in a woman subject to the fluor albus, or 
 from the blood of the menstrual discharge, may make the hymen yield, 
 and not rupture; so that a woman might seem a virgin without being 
 
 * " Attamen prima Venus debet esse crueuta." HAILEII.
 
 FUNCTION OF GENERATION. 457 
 
 such; while another woman, who has not lost her virginity, might, 
 from illness, have her hymen destroyed. There are, in the last place, 
 persons in whom the hymen is so indistinct, that several anatomists 
 have doubted its existence.* 
 
 The other external parts of generation, which are easily discovered 
 without the aid of dissection, cannot be considered as merely orna- 
 mental ; all are, as will be shewn presently, of real utility. The folds 
 of skin which form the labia and the nymphse yield during the 
 delivery of the foetus. These duplicatures not only unfold themselves, 
 but likewise undergo a degree of extension, their tissue being moister, 
 softer, and more extensible than that of the skin. The mons veneris, 
 the hairs which cover it, the clitoris, which resembles an imperfect 
 penis, seem merely organs of voluptuousness ; but is not pleasure itself 
 an element in the act by which the human species is reproduced ?f 
 
 CCIII. Of the functions of the generative organs. When a 
 chemical, mechanical, or mental irritation, excites the action of the 
 genital organs, the penis elongates itself, becomes turgid and stiff, 
 from the accumulation of blood within the cells of the corpus 
 cavernosum, and within those of the corpus spongiosum of the 
 urethra.J The turgescence of these two parts of the penis should be 
 simultaneous to render the erection complete. It has been thought 
 that this phenomenon might be accounted for by the compression of 
 the pudic veins, which are situated between the symphysis pubis and 
 the root of the penis, which, as long as the erection lasts, is compressed 
 against the bone by the erector muscles. But, far from elevating the 
 penis, the muscles of the perinseum, especially the ischio-cavernosus 
 (erectores penis) tend to depress it. The blood which distends the 
 corpora cavernosa of the penis, and the corpus spongiosum of the 
 urethra and glands, which is itself the expanded extremity of the 
 urethra, does not stagnate in their cells, only there is a greater 
 quantity of blood in them than usual ; the irritation increasing in a 
 remarkable manner the action of the arteries. Erection, always 
 proportioned to the degree of the stimulus, ceases when the cause of 
 irritation no longer acts on the penis ; in the same manner that an 
 inflammatory tumour is discussed when the cause is removed. || In 
 
 * It nevertheless always exists, but its size is very various. In some females it 
 completely closes the vagina, and in this case it causes retention of the menses. 
 In other cases, the occlusion not being complete, fecundation may take place by 
 means of a very small opening, and without introduction. 
 
 f See APPENDIX, Notes N N. 
 
 $ " Penis adest ita, constructus, ut stimulo corporeo sive mentali irritatus, 
 turgeat et obrigescat, seque erigat, postea detumescat, et collabatur." CREVE. 
 
 || The animal heat is somewhat augmented during erection as well as in 
 inflammation. The temperature of the blossoms of the arum rises several degrees 
 above that of the atmosphere at the moment of impregnation.
 
 458 FUNCTION OF GENERATION. 
 
 this voluptuous dilatation, the urethra is brought into a state of 
 erection, being put on the stretch by the penis, which is elongated, its 
 curves are straightened, the irritation is propagated from the external 
 to the internal parts, to the vesiculae seminales, and the testicles; 
 these swell, and their secretion is increased, as they receive a gentle 
 degree of motion from the action of the scrotum, which becomes 
 wrinkled, and draws them up towards the abdomen, and, by the action 
 of the cremaster muscle, whose expansion forms between the tunica 
 vaginalis and the dartos what has been improperly called the tunica 
 erythroidea, they empty themselves with the greater ease along the 
 vasa deferentia, which decrease in length as the testicles rise, and 
 which participate in the concussion affecting these organs. 
 
 The concussions of the cremaster on the testicle, or on the vasa 
 deferentia, promote in so important a manner the secretion and 
 excretion of the semen, that this little muscle is found in animals 
 whose testicles never leave the abdomen, but remain within that 
 cavity on the sides of the lumbar region, as was observed by Hunter 
 in the hedge-hog and the ram. This fact of comparative anatomy 
 shews that the cremaster is of use, not merely in suspending the 
 testicles, as its name indicates, since in the animals above mentioned 
 they return into the abdomen towards the organ on which they are 
 to act. 
 
 When irritation is carried to a certain length, it acts on the 
 vesiculee seminales, and these on the fluid which fills their cavity, 
 and they expel it by the spasmodic contraction of their membranous 
 parietes, assisted in this excretion by the levatores ani (CCI.) The 
 prostate gland, and the mucous glands of the urethra, furnish a viscid 
 substance, calculated to promote the evacuation of the seminal fluid, 
 which is emitted in jets more or less rapid. 
 
 CCIV. The human semen is never emitted in a state of purity, 
 that is, such as it is prepared by the testicles : it is even conjectured 
 that the mucous fluid of the vesiculae seminales forms the greatest part 
 of it. It is this mucus which eunuchs emit in considerable quantity. 
 The fluid secreted by the prostate gland, and by the mucous glands of 
 the urethra, affect it likewise by uniting with it. 
 
 On being received into a vessel, it exhales a peculiar smell, like that 
 of the pollen of a great number of plants ; for example, of the chestnut- 
 tree. It consists of two parts, the one thick and in clots, while the 
 other is viscid, white, and more fluid. The proportion of the fluid of 
 the semi-concrete part is greater in proportion as the person is 
 weaker, and as the emission of semen is more frequently repeated. It 
 soon liquefies, by losing part of its weight, which always exceeds that 
 of water, in which it becomes soluble, though it was not so at first. 
 On being analysed by M. Vauquelin, it was found to contain, of
 
 FUNCTION OF GENERATION. 459 
 
 water 90 centimes, of animal mucilage 6, phosphate of lime 3, soda 1 . 
 It is in consequence of this last alkali that it is enabled to turn syrup 
 of violets to a green colour. The animal mucilage is not pure 
 albumen, but rather a gelatinous mucus, on which the qualities of the 
 semen appear particularly to depend, such as its insolubility in water, 
 and spontaneous liquefaction. 
 
 On being examined with the microscope, the semen is seen to 
 contain small animalcules, with a rounded head, a tapering tail, and 
 moving with rapidity. Is the liquefaction of the glutinous and viscid 
 parts of the semen owing to the motion of these creatures ? These 
 microscopic animalcules are to be detected in the semen only at the 
 period of puberty.* It has been thought that they shunned the light : 
 authors have even gone the length of describing their ways and' their 
 diseases. The imagination has had much to do with all that 
 naturalists have fancied they saw in these creatures, which they made 
 subservient to their explanations of the mechanism of reproduction. 
 However, it must be confessed, that in all the animal fluids, and in the 
 juices of many plants, a certain number of these animalcules may be 
 detected by means of the microscope. 
 
 A spasmodic contraction affects, during the expulsion of the 
 semen, not only the organs of generation, but the whole body; 
 and the moment of emission is accompanied by a commotion of all 
 parts of the frame ; so that it should seem, says Bordeu, that in that 
 instant Nature forgot every other function, and was solely engaged 
 in collecting her strength and directing it to one organ. This general 
 spasm, this, as it were, epileptic convulsion, is followed by universal 
 depression : this physical lassitude is attended with a sensation of 
 sadness, which is net without enjoyment. Does this peculiar sen- 
 sation, which, according to Lucretius, mingles grief with the most 
 lively enjoyment of which we are capable, depend on the fatigue of 
 
 * The author states in his last edition, on the authority of one ohserver only, 
 that animalculae are not found in the semen of individuals affected with syphilis. 
 He also observes, that he has frequently had reason, in the course of his practice, to 
 impute sterility in the male to the existence of the lues venerea: this latter 
 circumstance, however, may be otherwise explained than by supposing that the 
 seminal animalculae are not generated during this disease. Indeed, the existence of 
 those animalculae is a matter of much doubt. We believe that what has been 
 usually supposed to be such, are nothing more than the minute portions of some 
 one of the very different secretions mentioned above as constituting the seminal 
 fluid, in the act of more intimate mechanical mixture, or of union, with those of the 
 others. The appearance of animalculae may be also exhibited by the secretion of any 
 single organ or part ; for, as all secreted fluids are not actually homogeneous, their 
 minuter portions, which differ in colour, consistence, &c. from the more abundant 
 and more aqueous portion, would very probably give rise to the deception in 
 question. J, C.
 
 460 FUNCTION OF GENERATION. 
 
 the organs, or, in truth, as some metaphysicians have imagined, on 
 the confused and distant notion that occurs to the soul of its own 
 dissolution ? 
 
 The penis does not enter the uterus, though the semen does. The 
 os tincae offers too small a slit, and its thick edges are, besides, in 
 contact. It would be difficult to conceive that this straight passage 
 should admit even the seminal fluid, if it were not known that in the 
 moment of copulation, the uterus, from irritation, draws together, and 
 inhales, by real suction, the semen which it craves. Plato compared 
 this organ to an animal living within another animal, controlling all the 
 actions of the living economy, burning to sate itself with the liquor of 
 the male, and digesting it to form a new individual. 
 
 The great thickness of the cervix of the uterus has given room for 
 reasonable doubt whether or no its orifice could dilate sufficiently to ad- 
 mit a fluid of the consistency of semen. Some, therefore, have thought 
 that it was not this fluid itself that penetrated into the cavity of the 
 uterus, but the subtlest of its parts, the most spiritualised, a prolific 
 vapour, to which they have given the name of aura seminalis ; but, 
 besides that the semen has been found in the uterus in animals opened 
 immediately after copulation, Spallanzani, in his experiments on the 
 fecundation of frogs, of salamanders, and toads, perceived that, to 
 enable the eggs to produce, it was not enough to expose them to the 
 vapour which rises from the seminal fluid of the male, and that 
 nothing was effected unless the fluid semen actually touched them, 
 though in ever so small a quantity. 
 
 It has been said that the uterus dilates to receive the semen, 
 constricts itself to retain it, and that this spasmodic contraction of the 
 / uterus, felt, as Galen assures us, by women who preserve enough sang- 
 froid to make observations in that situation, was the most undoubted 
 sign that could be had of the success of the copulation. It is, no 
 doubt, to ensure this retention that it is customary to throw cold 
 water on the females of some domestic animals when they go too 
 eagerly to the male. The spasm of the skin, occasioned by the cold 
 striking it, affects the uterus, and hinders the flowing back of the 
 semen which has been thrown into its cavity. 
 
 It has also seemed that women conceived more easily, for a little 
 time, after menstruation ; when the mouth of the uterus is less exactly 
 closed than usual. 
 
 The seminal fluid, thrown into the cavity of the uterus, passes 
 along the Fallopian tubes to the ovaria. It does not diffuse itself in 
 the cavity of the abdomen, because the membranous duct seizes the 
 ovarium, which corresponds to it, grasps it closely, and establishes an 
 uninterrupted canal from this organ to the uterus. The ovarium, 
 bdewed by the semen, irritated by its contact, lets a fluid escape, or
 
 OF THE OVUM. 461 
 
 perhaps a little ovum, which passes into the uterus the same way that 
 the semen reached it. All that remains to be said concerning the 
 mechanism of generation must not be delivered as real, but merely as 
 probable; such is the darkness with which Nature has chosen to 
 envelope this great mystery of the living economy.* 
 
 After distinguishing the true from the probable, an indispensable 
 duty in every science of facts and observations, like physiology, I shall 
 proceed to state the hypothesis which appears to me the likeliest on 
 the manner in which the two sexes concur in the production of the 
 new being. 
 
 CCV. Of the ovum and its impregnation. The germs pre-exist 
 in the ovaria of the females, not that they are there since the creation 
 of the world, as Bonnet believed, and all who embraced the doctrine 
 of that metaphysical naturalist ; but the ova containing the germs are 
 formed by the proper action of the ovarium which secretes them; a 
 fresh proof that all the phenomena of organised bodies, whether for the 
 preservation of the species or of the individual, are effected in the way 
 of secretions. The ovum, produced by the elaboration of the blood 
 which the spermatic vessels carry to the ovaria, contains the 
 lineaments of the new being ; but it is only the sketch or carcass of it, 
 if this may be applied to what has not yet lived. The seminal fluid 
 must bring it out of this state of inactivity, and, with something of an 
 electrical power, waken it into life. The eggs laid by a maiden hen 
 will never hatch, though there are in them the rudiments of the chick. 
 The eggs of a frog that has been kept apart from the male during the 
 whole time of spawning, putrefy in the vessel of water they are kept 
 in : if the male, on the contrary, sprinkles them with his semen, as they 
 quitted her, they will speedily shew some developement of life. Their 
 putrefaction may be prevented, and themselves animated, by shedding 
 on them the spermatic fluid, obtained by the process employed by 
 Spallanzani, in his admirable experiments on artificial impregnation. 
 
 It is especially to the labours of this able observer that we owe 
 what has been unveiled of the mystery of generation, and of the part 
 which each sex bears in this function. It is almost proved that the male 
 co-operates in this function, only by supplying the vivifying principle 
 that must animate the individuals of which the female furnishes the 
 germs; and that thus his part is the least essential. It is not so difficult 
 as may be imagined to explain upon this system the striking resem- 
 blances which are frequently seen between fathers and sons. The imper- 
 ceptible embryo has, at most, the consistency of a slightly viscous glue. 
 Such a body must be exceedingly impressible, and the semen of the 
 male, applied to its surface, must impress on it powerful modifications. 
 
 * See APPENDIX. Notes N N.
 
 462 OF IMPREGNATION. 
 
 The action of the fluid on this yet tender embryo must be like that of a 
 seal, which stamps on the soft wax its own image. The impression is 
 the deeper, the resemblance the more striking, according to the spirit 
 and energy with which the male performed the act of reproduction. 
 
 The seminal fluid of the male ra,ay not merely act on the surface 
 of the gelatinous and nearly liquid germ, and modify it externally, but 
 it may penetrate so soft a substance, and impress on it inward changes. 
 It is thus that we are able to explain, not only hereditary likeness, 
 but also hereditary diseases. Nevertheless, it does appear that the 
 interior parts are derived chiefly from the female, while the outward 
 parts are especially influenced by the male ; for, when two animals of 
 different species copulate, their mule resembles the sire outwardly, 
 and the dam within. It is difficult to shew good reason for the want 
 of the generative faculty in mules. Why are their sexual parts, so well 
 developed, altogether barren ? What secret defect frustrates their 
 action ? And why do certain mules, among birds, propagate, and 
 in the same manner hybrid plants, which are real mules, and not 
 quadrupeds ? 
 
 The impregnation of the ovum is effected in the ovarium itself, 
 to which the semen is conveyed, as has been said. The ovum, stirred 
 by the action of the semen, and of the Fallopian tube, detaches itself 
 from the organ which has produced it, and descends into the uterus, 
 by the peristaltic contractions of the Fallopian tube. This canal is 
 susceptible of a retrograde motion. It may be conceived possible that, 
 having stretched itself by a real erection, to convey the semen to the 
 ovarium, it must in its return upon itself cause a flow of the fluid 
 its cavity contains in a completely inverted direction.* This retro- 
 grade motion, as Nisbet observes, is assisted by a sort of collapse 
 succeeding the excitation which coition had produced ; for the expe- 
 riments of Darwin prove that the weakness of the vessels is the cause 
 of this mode of action in their parietes. Spongy as the urethra of 
 man, the Fallopian tube brings back the ovum from the ovarium to the 
 uterus. The extra-uterine foetations afford the proof that matters are 
 carried on in the manner we have stated. Since foetuses have been 
 found developed in the ovarium, in the Fallopian tube, and even in 
 the cavity of the abdomen, when the detached ovum has escaped from 
 the grasp of the corpus fimbriatum, f one must admit that it follows 
 the course which has been described. 
 
 * See the Notes N N in the APPENDIX on this subject. 
 
 f In extra-uterine abdominal conceptions, the ovum, which the tube could not 
 hold or seize, rolls into the hypograstic region, and there adheres to some point of the 
 peritoneum. It is found attached to the mesentery, to the colon, to the rectum, or 
 to the external part of the uterus, growing there, and developed by the vascular 
 communication which takes place at the adhesion ; but the vessels of the peritoneum
 
 OF IMPREGNATION. 463 
 
 The ovaria, like the testicles, swell and enlarge at the time of 
 puberty. They shrink and wither in some degree when the woman is 
 no longer fit for generation. On examination a few days after con- 
 ception, one of the ovaria is larger than the other, and shews a little 
 yellowish vesicle, which dries up in the course of pregnancy, so that 
 towards the end there remains nothing in place but a very small 
 cicatrix. Is this vesicle the outermost covering of the ovum, in which 
 the germ is enclosed, and which is torn to allow its escape ? The 
 observations of Haller prove that the corpus luteum is formed by the 
 remains of a vesicle that has burst at the moment of conception, and 
 allowed the fluid it contained to escape. In an ewe opened a few 
 minutes after coition, you may see, in one of the ovarn, a vesicle 
 larger than the others, torn with a little wound, of which the lips are 
 still bloody. Inflammation comes on in the torn coats of the small 
 vesicle, fleshy granulations appear, then sink, and a scar shews the 
 place where it had been. The number of these cicatrices is propor- 
 tioned to that of the foetuses. It is not known how long the germ, 
 detached from the ovarium, remains within the Fallopian tube before it 
 reaches the cavity of the uterus. Valisnieri and Haller had never 
 been able to perceive it directly in this viscus before the seventeenth 
 day. 
 
 The obstruction of the tubes, as well as the defect or diseased affec- 
 tion of the ovaria, may cause barrenness. Morgagni speaks, on this 
 head, of certain courtezans in whom the tubes were entirely obliterated 
 by the thickening of their parietes ; the consequence, evidently, of the 
 habitual orgasm in which they had been kept by too frequent excitation. 
 The structure of these parietes must make obstructions of the Fallopian 
 tubes very easy. Their tissue is spongy, vascular, and seems sus- 
 ceptible of erection, like the corpus cavernosum of the penis and of 
 the clitoris. Their internal coat (the point of union between the 
 
 are insufficient for the entire developement of the foetus, which dies for want of 
 nourishment in the first months of pregnancy. The adhesion of the ovum to the 
 peritoneum is easily accounted for, by the irritation it occasions : it may be con- 
 sidered as a foreign body, determining by its presence inflammation of the mem. 
 brane with which it lies in contact, and uniting with it because it brings to this 
 act its own share of vitality. It is really an union of two living parts, not unlike 
 to that which takes place between the bleeding lips of a wound, or between the pleura 
 pulmonalis and the pleura costalis, &c. 
 
 But as the serous membranes contain, in their tissue, capillaries so fine, that 
 when in a healthy state the blood does not shew its colour in them, their vessels 
 never develope themselves sufficiently to transmit to the ovum, which has adhered 
 to them, a due supply of this fluid. The mucous membranes receiving more blood 
 are able to supply more ; but the placenta cannot adhere to them in extra-uterine 
 conception. The membrane which lines the tube, belongs, in fact, as much to the 
 serous as to the mucous membranes ; it establishes, as is well known, the only 
 point of communication there is between the two kinds of membranes.
 
 464 OF IMPREGNATION. 
 
 serous membrane which lines the abdomen, and the mucous mem- 
 brane within the uterus) partakes in the inflammation of both. I have 
 often been consulted by young women on the cause of their sterility : 
 by a close investigation of the causes from which it might have arisen, 
 I have always found that they had had, at different periods of life, in- 
 flammation of the lower part of the abdomen. A young woman, after 
 obstinate suppression of the menses, exhibited all the symptoms of 
 inflammation of the peritoneum : a year afterwards she married, but 
 never became pregnant. A woman recovered from puerperal fever, 
 ensuing upon a very difficult first labour ; from that time, with all the 
 appearance of the stoutest health, she has never again been a mother. 
 
 Do the two testicles and the two ovaria contain the separate germs 
 of males and females ? Are the latter, as has been guessed, contained in 
 the left ovarium, and males in the right ? and may we procreate sexes 
 at pleasure, by varying the attitude of copulation ? This old opinion, 
 lately revived, besides wanting all foundation, is formally confuted by 
 facts : nothing is more common than to see men who have, from some 
 accident, lost a testicle, procreating sexes indifferently. Women, 
 with an ovarium deficient, or the Fallopian tube obliterated on one 
 side, have produced both boys and girls. Dr. Jadelot presented to 
 the Society of the School of Medicine, in Paris, a uterus wanting 
 the right tube and ovarium; and nothing indicated that they had 
 ever existed. On inquiry concerning this woman, it appeared that 
 she had been delivered of a boy and two girls. Haller quotes similar 
 cases. The cause, then, which determines the sex, altogether eludes 
 our investigation. Does that one of the two who exerts most energy 
 in the act of coition, impress its sex on the offspring ? I cannot tell ; 
 but I think I have observed that the marriage of young people, 
 where both are glowing with love and youth, most frequently pro- 
 duces daughters, whilst boys are ordinarily the consequence of the 
 union of a middle-aged or elderly man with a younger woman.* 
 
 CCVI. Theories of generation. The antique system of the mix- 
 ture of the semen in the cavity of the uterus, set forth in the writings 
 of Hippocrates and Galen, is still that of many physiologists. In this 
 system the mixed fluids may be considered as an extract from all 
 parts of the body, male or female. A generative faculty f disposes 
 them suitably for the formation of the new individual. BufFon has 
 further particularised the facts which this hypothesis requires, and 
 displays its improbability. Each part, he says, furnishes molecules, 
 which he calls organic, and these molecules, coming from the eyes, 
 
 * This opinion has not been confirmed by the observations of other physio- 
 logists J. C. 
 
 j- All that Bluraenbach has said on the force of formation (nisus formativus) 
 applies to this generative faculty ; it is only a new name given to an old idea. 
 
 *
 
 OF IMPKEGNATIOX. 465 
 
 llie ears, &c. of the man and the woman, arrange themselves round 
 an internal mould, of which he admits the existence, which mould 
 forms the basis of the edifice, and comes from the male, probably, if 
 it be a boy, from the female if a girl. Reason rejects a theory which 
 gives no explanation of the production of the placenta, and of the 
 membranes covering the foetus : it is, moreover, directly disproved by 
 the good conformation of children born of parents who, not happen- 
 ing to have certain organs and limbs, could not certainly supply the 
 proper molecules for their formation in the child. 
 
 The system of the ovarists, which at this time stands highest in 
 favour, numbers amongst its supporters Harvey, Stenon, Malpighi, 
 Valisnieri, Duhamel, Nuck, Littre, Swammerdam, Haller, Spallanzani, 
 Bonnet, &c. These admit the distinction of animals into oviparous 
 and viviparous in the sense only that these last hatch within, and 
 break their shell before they are brought forth. Lastly, Leuwenhoek, 
 Hartsoeker, Boerhaave, Mery, Werheyen, Cowper, &c. have added to 
 the opinion of the ovarists, that the seed of the male contains a mul- 
 titude of spermatic animalcules, all capable of becoming, by develope- 
 ment, beings similar to their father. These animalcules push forward, 
 along the tubes, upon the ovaria : there a general engagement takes 
 place, in which all are slain, save only one, who, master of the field of 
 battle, finds the triumph of his victory within the ovum that has been 
 prepared for him. This system, which is not the most probable in the 
 world, assigns to the male the greater part in the work of generation, 
 since the female is made to furnish merely the coverings of the foetus. 
 
 It would be to no purpose to unfold, more at large, opinions 
 hazarded on a subject so obscure. What I have said is enough to 
 shew that those parts of nature which most obstinately elude our 
 curiosity, and afford most scope to our imagination, are those which 
 men believe they know the best, and on which they speak with most 
 confidence and prolixity: so true is it, as Condillac has observed, 
 that we have never so much to say as when we set out from false 
 principles. 
 
 H H
 
 466 OF UTERINE GESTATION. 
 
 Sbcccmfc 
 
 FUNCTIONS EXCLUSIVELY BELONGING TO THE FEMALE. 
 
 CHAPTER XI. 
 
 OF THE FCETUS, PARTURITION, AND LACTATION. 
 
 CCVII. Of Uterine Gestation CCVIII. History of the Foetus CCIX. to 
 
 CCXI. Of the Circulation in the Foetus CCXII. Of the Nourishment of the 
 Foetus. CCXIII. Of Monstrous Foetuses. CCXIV. Of the Coverings of 
 
 the Foetus CCXV. Of the natural Term of Utero-gestation CCXVI. and 
 
 CCXVII. Of Parturition CCXVIII. Of Twins CCXIX. Of Superfceta- 
 
 tion CCXX. and CCXXI. Of Suckling CCXXII. Of the Physical and 
 
 Chemical Properties of Milk. CCXXIII. Of the State of the Lungs and 
 Foramen Ovale in some Infants. 
 
 CCVII. Of uterine gestation. From the moment of conception there 
 begins in woman, both in the motion of the solids and the composition 
 of the fluids, a remarkable alteration. The change that has taken 
 place shews itself in all her functions: she exhales a peculiar odour; 
 the child she suckles refuses the breast, or takes it with reluctance, 
 and soon falls away, if left in the hands of such a nurse. 
 
 Nature, occupied over her work, seems to forget every thing else 
 to bring it to perfection. It has been observed, that in times of con- 
 tagious diseases, even where the plague raged, pregnant women were 
 least exposed to infection ; but, at the same time, when they are seized 
 with affections, which in .other persons or at another season would be 
 without danger, they sink under them, because these diseases, though 
 at first very slight, easily put on a malignant character. The progress 
 of mortal diseases is retarded : a phthisical woman, and who has only 
 a few months to live, shall prolong her life through the whole term of 
 gestation. The consolidation of fractures is nothing slower, though 
 Fabricius Hildanus pretends that the state of pregnancy puts a com- 
 plete stop to it. 
 
 I have never been able to find any difference in the time of form- 
 ation of callus between pregnant women and others. M. Boyer 
 avows the same opinion.* *-Among the authors who have asserted that 
 fractures could not consolidate during pi\ pliancy, some have conjec- 
 
 * Lemons de 31. Boyer, sur les Maladies des Os, redigees en un Traitd complet 
 de ces Maladies, par A. llicherand. 2 vols. 8vo. 
 
 '
 
 OF UTERINE GESTATION. 467 
 
 tured that this depends on nature, who is busy in directing the 
 humours to the uterus, forgetting in some sort every other function, 
 and omitting to institute the process necessary to the cure. But, as 
 we shall see, whatever may be the importance of the uterus, charged 
 during pregnancy with the fruit of conception, the foetus is merely an 
 organ added to the organs of the mother, and assimilating to itself the 
 juices it receives from the uterine vessels. It does not hinder the other 
 parts from getting their nourishment : they all go on living, and se- 
 parating to themselves the juices their existence or their functions 
 require. Haller ascribes the difficulty with which the broken ends 
 unite in pregnant women, to the great quantity of earthy matter 
 which the foetus draws off from the mother. This opinion will not 
 stand; for, as I have shewn in my preliminary discourse, the phosphate 
 of lime has but little to do in the work of reunion, which chiefly goes 
 on by changes in that part of the bone which is really organic. 
 Besides, this hypothesis would imply that consolidation were as difficult 
 in nurses, whose milk carries off a large quantity of phosphate of lime. 
 Yet it has not been observed that the formation of -callus is more 
 difficult during suckling. Lastly, on this, as on all occasions, ex- 
 perience is more effectual than reasoning ; now, experience shews that 
 the time required for the formation of callus in pregnant women is not 
 sensibly longer than in their ordinary state. 
 
 Meanwhile, the uterus, imbued with prolific fluid, swells, to avail 
 myself of the expression of a modern, like a lip stung by a bee: it 
 becomes a centre of fluxion, towards which the humours tend from all 
 quarters. The diameter of its vessels increases with the thickness of 
 its parietes : these soften, and their muscular nature becomes more 
 marked.* Till the end of the third month the only appearance of 
 pregnancy is in the suspension of menstruation : the uterus, of which 
 the cervix has yet undergone no change, has concentrated itself behind 
 the pubis, but very soon it rises above the upper outlet of the pelvis, 
 pushing upwards the intestines and the rest of the abdominal viscera. 
 Towards the end of pregnancy it rises above the umbilicus, its fundus 
 comes in contact with the arch of the colon, and reaches sometimes to 
 the epigastric region. The compression it exerts on the organs of 
 digestion explains the loathings and the nausea which belong to the 
 state of pregnancy. The derangement of sensibility, by the affection of 
 the great sympathetics, accounts equally for those depraved tastes, 
 those fantastic appetites, which the ignorant think it so important to 
 gratify. When the term of pregnancy draws near, respiration is 
 
 * According to M . Lobstein, the uterus during pregnancy is analogous to an 
 organ in a state of chronic inflammation. J C.
 
 OF FTERIXE GESTATION. 
 
 oppressed, the diaphragm forced upward by the abdominal viscera, de- 
 scends with difficulty ; accordingly, nature has, as much as possible, 
 delayed this moment of oppression, by giving the lower part of the 
 abdomen a great capacity, at the expense of the chest, which in 
 woman is much shorter than in men. 
 
 If the growth of the foetus, its size, the quantity of liquor amnii, and 
 the developement of the uterus, were always the same, we might settle 
 the height to which this last organ must rise at each stage of preg- 
 nancy ; but these conditions vary so much in every individual, that 
 the terms one might assign would suit but a small number : let it 
 suffice to have spoken of the extremes. The uterus tends to rise 
 directly upwards: while enclosed within the pelvis it preserves this 
 direction ; but, as soon as it has passed the upper outlet of the pelvis, 
 it is no longer supported, and inclines forwards, backwards, or to the 
 sides. These inclinations, if they go a certain length, constitute 
 those vices of situation which accoucheurs call obliquities of the 
 uterus. Their direction is determined by the disposition of the 
 parts : accordingly, they almost always are forwards, either because 
 the upper outlet of the pelvis is naturally so inclined, and forms, 
 with the horizon, an angle of forty-five degrees, or because the 
 lumbar column, being convex, pushes the uterus against the an- 
 terior parietes, which yields the easier the more frequent pregnancy 
 has been. 
 
 The dilatation of the uterus is not the effect of a simple distension 
 of its parietes, since these, far from stretching thinner as the viscus 
 grows in size, thicken progressively, on the contrary, by the dilatation 
 of vessels of all sorts, and the afflux of humours. In this sort of vege- 
 tation the uterus is really active, and does not give way to any efforts of 
 the foetus. The cervix of this viscus, which, from its greater consist- 
 ency, had at first resisted dilatation, ends by yielding to the efforts of 
 the fibres of the fundus on the edges of the os tinese ; the edges of 
 that opening are attenuated, the cervix effaced, the orifice enlarges, 
 and you may feel through its parietes the foetus plunged in the 
 waters which its membranes contain. 
 
 Towards the term of gestation the discharge of urine is more fre- 
 quent, because the bladder, under compression, cannot contain it in 
 any quantity; the lower extremities are cedematous, and the veins of the 
 legs varicose : women are also more exposed to haemorrhoids ; and 
 these effects depend on the compression of the vessels which bring 
 back the blood and the lymph of the inferior parts, as the cramps to 
 which pregnant women are subject depend on that of the sacral nerve. 
 The groins are alike painful, and there are felt in them twitchings 
 which must be ascribed to congestion in the round ligaments of the
 
 OF THE EMBRYO. 469 
 
 uterus.* Lastly, the skin of the anterior parietes of the lower part of 
 the abdomen, distended beyond measure, cracks when that of the 
 neighbouring parts has yielded as much as it could. 
 
 Before explaining how the uterus expels the foetus and its coverings 
 at the term of gestation, let us consider a little this fruit of conception, 
 let us study its developement, let us examine the nature of the relations 
 which it holds with its mother. 
 
 CCVIII. History of the foetus. The interior of the uterus, for a 
 short period after the instant of conception, shews nothing that leads 
 to'a knowledge of the existence of its product. But at the end of a 
 few days there appears a membranous, transparent vesicle, filled with 
 a liquid, trembling jelly, discovering no trace of organisation and life. 
 But the little ovum begins to grow, parts of the gelatinous fluid assume 
 more consistence, losing at the same time their transparency : one 
 may then distinguish the first rudiments of parts an imperfect appear- 
 ance of the head, trunk, and limbs. The small ovum, free at first in 
 the cavity of the uterus, contracts adhesion to this viscus : its whole 
 exterior surface becomes shaggy, and this sort of vegetation is no 
 where more marked than in the situation to be occupied by the pla- 
 centa. Meantime, towards the seventeenth day, the parts, which 
 shewed merely a homogeneous, semi-transparent mass, discover a 
 more determinate structure. A red point appears in the spot of the 
 heart it is the heart itself, distinguishable by the pulsations of its 
 cavities, and the motions of the molecules of the red liquid that fills 
 them. Because the heart is the punctum saliens, it is not, therefore, 
 to be concluded that it is the primum vivens. All our parts are formed 
 together, all are coeval, as Charles Bonnet has said ; only they dis- 
 cover themselves earlier or later to the eye of the observer, according 
 as the nature of their organisation is adapted to the reflection of light.f 
 Were we to admit a successive order in the formation of our organs, 
 the brain and the nervous system might exist before the heart, without 
 being perceptible from their transparency. 
 
 Meanwhile, red lines, setting off from the heart, sketch the course 
 of the larger vessels, and seem agitated by the action of these tubes, 
 
 * These ligaments, as well as the uterus, manifest during gestation their mus- 
 cular character: their vessels enlarge, and their fibres become more apparent, 
 according to the observations of M. Jules Cloquet, made on the bodies of several 
 females who had died soon after child-birth. 
 
 See the Note N N, last referred to, in the APPENDIX, for the Changes which the 
 Nerves of the Uterus and its Appendages undergo during Pregnancy J. C. 
 
 -\- The opinion of Bonnet alluded to above rests on no observation that can even 
 lend it a collateral support. We have every reason, on the contrary, to infer, that 
 a successive order in the formation of our organs is observed. See some remarks on 
 this subject in the AITEKDIX, Notes OO.
 
 470 GROWTH OF THE FOETUS. 
 
 whose parietes are still semi-transparent. As the blood, or rather its 
 red part, extends from the centre to the circumference, the forms be- 
 come more determinate, the parts unfold and grow rapidly : points quite 
 opaque are seen, and the form of the fetus may be distinguished. Bent 
 upon itself, the foetus is not unlike a French bean, suspended by the 
 umbilical cord, which, as I shall mention by-and-by, formed with 
 the foetus and its coverings, proceeds in growth with them : it swims 
 amidst the liquor amnii, and changes its position the more easily as 
 the space in which it is enclosed is greater compared to its size. As it 
 grows it stretches out a little, without ceasing, however, to retain its 
 bent posture (CLXV.) : the head composes the greater part of its 
 body'; the upper limbs, like little buds, pullulate first, then the lower 
 limbs ; the feet and the hands appear immediately attached to the trunk ; 
 the fingers and toes shew themselves like little papillae. Of all the 
 organs of sense, the eyes are the first apparent : they are discernible as 
 two little black spots; and by the end of the first month the eye-lids are 
 produced, and cover them. The mouth, at first gaping, closes by the 
 drawing together of the lips, towards the end of the third month. 
 During the fourth, a reddish-coloured fat begins to be deposited in trie 
 cells of the mucous tissue, and the muscles already exert some action. 
 The growth is ever more rapid as the foetus draws nearer to its birth. 
 It is impossible to assign the weight and the length of the fetus at the 
 different stages of pregnancy, since the time of conception is never 
 very certain; and further, the progress of growth varying much, one 
 foetus at six months shall be as large as another at the full term. 
 Nevertheless, at the time of birth, the body is commonly eighteen 
 inches long, and weighs from seven to eight pounds. 
 
 The secretion of bile, like that of the fat, seems to begin towards the 
 middle of gestation, and tinges the meconium yellow, a mucus pre- 
 viously colourless, which fills the digestive tube ; a little while after 
 the hairs grow ; the nails are formed about the sixth or seventh month ; 
 and a very thin membrane which closed the pupil, tears, by what me- 
 chanism is unknown, and the pupil is seen. The kidneys, at first 
 manifold, that is to say, formed each of from seventeen to eighteen 
 separate glandular lobules, unite and form on each side a single viscus. 
 Lastly, the testicles, placed at first at the side of the lumbar column 
 and aorta, near the origin of the spermatic arteries and veins, then 
 carried along the iliac vessels to the inguinal rings, directed by a cel- 
 lular cord, (which Hunter calls the gubernaculum testis,) pass through 
 this opening, carrying along with them the portion of the peritoneum 
 which is to' form their tunica vaginalis, and the inferior fibres of the 
 smaller oblique muscle. 
 
 This covering of the testicles, furnished by the peritoneum, not only 
 covers these organs, and is reflected again over them, but also rises, 

 
 OF THE FCETAL CIRCULATION. 471 
 
 in adults, about half an inch high, along the lower part of the sper- 
 matic cord. If it do not reach, it is said, to the inguinal ring, it is 
 because the whole portion which, after birth, extended from this 
 opening to near the testicle, has been decomposed, and is reduced to 
 a cellular tissue. Upon reflecting on the causes of the spontaneous 
 decomposition of a portion of this peritoneal prolongation, it occurred 
 to me, that nothing was less proved, or more improbable; in fact, in 
 earliest life, the testicles, which have passed out from the abdomen by 
 the inguinal rings, are very little removed from this opening. The 
 portion of tunica vaginalis, which is continued upon the cord of the 
 spermatic vessels, rises up to the rings, and even extends beyond them; 
 communicating with the peritoneum, as is sometimes seen in congenital 
 bubonocele. It is only in the progress of life that the testicles 
 descend into the scrotum, still departing from the opening which gave 
 them passage ; so that in adults the prolongation covering at first the 
 whole cord, which just after birth was not more than a few lines Iong 5 
 is found to cover only its lower part when it is lengthened some inches, 
 without being decomposed ; a phenomenon which it is as difficult to 
 conceive as to explain. This opinion, suggested for the first time in 
 the first edition of this work, is now almost universally received.* 
 
 CCIX. Of the circulation in the foetus. The principal difference 
 that is found between the foetus and the new-born child, besides the 
 inactivity of the senses, and the repose of the muscles subject to voli- 
 tion, consists of the manner in which the circulation is carried on. Too 
 feeble to assimilate to its own substance foreign substances, the foetus 
 receives from its mother aliments ready prepared. The arteries of the 
 uterus receive a large supply of blood : this is not all employed for the 
 nourishment of the organ itself, but passes, in great part, from the 
 mother to the child, being poured by the uterine vessels into the cells 
 of a spongy substance, adhering on one side to the uterus, and on the 
 other to the ovum which contains the foetus. 
 
 This cellulo-vascular body, known under the name of placenta, is^ 
 as well as the covering of the foetus and the foetus itself, a product of 
 the act of generation. Though it adheres commonly to the fundus of 
 the uterus, it may adhere to any other point of its parietes ; sometimes, 
 even, it is placed on its orifice; a circumstance which always makes 
 delivery difficult. The side by which it is united to the internal face 
 of the uterus is uneven, covered with mamillary projections (cotyle- 
 dons'), which are sunk in corresponding cells of the parietes of the 
 uterus, the internal surface of which loses, as it developes itself, the 
 smoothness which it had while empty, is furrowed with depressions 
 destined to receive the placenta, and studded with projections which 
 penetrate into the cells of the latter. 
 
 * See APPENDIX, Notes O O.
 
 472 OF THE FffiTAL CIRCULATION. 
 
 The uterine arteries, which are so large and numerous in the gravid 
 uterus, that Cruickshank compares them to quills, and perhaps, like- 
 wise, the lymphatic vessels, or those conveying merely colourless blood, 
 throw out on the surface of the placenta, and within its spongy tissue, 
 the arterial blood of the mother : according to some, these vessels 
 exhale only the serous part of the blood, and, according to others, a 
 chylous, lymphatic, whitish, or milky substance.* These fluids, effused 
 within the cells of the placenta, are absorbed by the numerous minute 
 divisions of the umbilical vein, which by their union form the trunk 
 of this vessel. 
 
 The umbilical vein, arising from the interior of the placenta, by 
 numerous branches, detaches itself from it and goes towards the um- 
 bilicus of the child, enters his body at that aperture, ascends, in a fold 
 of the peritoneum, behind the recti muscles, to the anterior extremity 
 of the sulcus of the liver, and goes along the anterior of this fissure, 
 sending a number of branches to the lobes of that viscus, especially to 
 the left lobe. On reaching the right extremity of the transverse fissure, 
 where this last meets the anterior-posterior, it unites, in part, with 
 the sinus of the vena portse hepatica, while the remainder of the 
 vessel, called ductus venosus, follows the original direction, and 
 
 * A German physician, Schreger, has suggested a very ingenious opinion on the 
 mode of circulation between the mother and child. He believes that the uterine 
 arteries pour out nothing but serum into the cells of the placenta. This serum is 
 absorbed by the lymphatics, whose existence in this organ and in the umbilical cord 
 he infers from analogy; in which, however, no one has yet succeeded in injecting 
 them. These vessels convey it to the thoracic duct, whence it is poured into the 
 left suhclavian vein, and at last reaches the heart, which sends it along the aorta. 
 It returns to the placenta by the umbilical arteries, after being converted into blood 
 by the actions of the organs of the foetus. This serosity, after undergoing the pro- 
 cess of sanguification, returns to the foetus by the umbilical vein, and, following the 
 well-known course of the foetal circulation, is subservient to the nourishment of its 
 organs. The branches of the umbilical arteries and veins, ramified in the placenta 
 and communicating together in this spongy tissue, reject through their lateral pores 
 that which can no longer serve to the maintenance of the foetus. This residue of 
 nutrition, deposited in the cells of the placenta, is absorbed by the lymphatics of the 
 uterus, which carry it back into the mass of the fluids of the mother. Not to men- 
 tion the impossibility of demonstrating the presence of the lymphatics in the pla- 
 centa, or in the umbilical cord, Schreger's hypothesis is attended with two objec- 
 tions. How does the nutritious fluid, coming from the mother and sent along the 
 aorta of the foetus to every part of its body, return to the placenta, to be brought 
 back again by the umbilical vein ? Absorption scarcely goes on in the foetus : the 
 unctuous substance with which the body of the foetus is covered, prevents that 
 function from taking place on the surface of the body. It goes on with very little 
 more activity within the body; the excrementitious secretions scarcely exist before 
 birth: whatever is conveyed to the foetus is employed in the developement of its 
 organs ; hence its growth is so rapid. 
 
 See the remarks on the Function of the Placenta, Notes OO, in the APPENDIX, 
 last referred to.
 
 OF THE FffiTAL CIRCULATION. 473 
 
 opens into the ascending or inferior vena cava, very near to the spot 
 where this vein pours its contents into the right auricle of the heart. 
 
 CCX. The arterial blood, which flows along the umbilical vein, 
 acquires the properties of venous blood, and combines with hydrogen 
 and carbon, and parts with its vivifying qualities in flowing along the 
 vessels of the mother and the tortuous vessels of the placenta. It parts 
 with these principles, and again becomes vivified by circulating through 
 the liver, which, at this period of life, fulfils the function which after 
 birth is committed to the lungs. Hence the liver and brain form the 
 greatest part of the weight of a new-born child. The former alone 
 occupies the greatest part of the abdomen. It acquires this bulk by 
 assimilating to itself the hydrogen and carbon of the umbilical blood. 
 Its substance is adipose, oily, and contains these two principles in a 
 considerable proportion. The secretion of the bile, and that of the 
 fat, the only secretions that are manifestly carried on in the foetus, 
 may, besides, supply very well the want of respiration.* 
 
 The blood conveyed by the umbilical vein into the lower vena cava, 
 and deposited by that vein into the right auricle, does not unite with 
 that which is brought by the descending cava from the upper parts, 
 for, as was observed elsewhere, the orifices of these two vessels not 
 being directly opposed to each other, the columns of blood which flow 
 in them do not meet each other. That which is brought by the 
 lower cava passes through the foramen ovale, towards which the 
 mouth of that vessel is turned ; it passes into the left auricle, thence 
 into the left ventricle, without circulating through the lungs, which, 
 containing no air, and being dense and indurated, could not have 
 received it : the contractions of the left ventricle send it into the aorta, 
 and the force of its impetus is broken by striking against the great arch 
 of this artery. It enters into the vessels which arise from it, and these 
 convey it directly to the brain and upper parts. This blood is the most 
 pure, the most oxygenated, and that which comes most immediately 
 from the placenta ; it has not yet circulated in the body of the foetus, 
 with the exception of a very small quantity brought from the pelvis 
 and lower parts, for the blood which comes from the abdominal 
 viscera is purified in passing through the liver. The other parts of 
 the body receive, on the contrary, blood imperfectly oxygenated, 
 since the very inconsiderable quantity which the contractions of the 
 left ventricle and the aorta have not been able to send into the vessels 
 arising from the arch of this vessel, mixes with the venous blood 
 which is brought by the ductus arteriosus, immediately below this 
 curvature. Hence growth, which is always relative, not only in re- 
 spect to the quantity, but likewise to the vivifying qualities of arterial 
 
 * See AITENDIX, Notes O O.
 
 474 OF THE FffiTAL CIRCULATION. 
 
 blood, is much more rapid before birth in the upper parts, so that the 
 brain alone constitutes the greatest part of the body; and the shoulders, 
 the chest, and the upper extremities, are developed in a much greater 
 degree than the abdomen, and especially than the pelvis and lower 
 extremities. 
 
 The blood which is brought by the descending cava from the 
 upper parts of the body of the foetus, passes into the right ventricle, 
 which forces it into the pulmonary artery : this vessel sends only two 
 small branches to the lungs, and terminates, by a vessel called the 
 ductus arteriosus, in the aorta, immediately below the origin of the 
 left subclavian artery. The aorta, at its origin, is therefore filled with 
 arterial blood, sent towards the upper parts of the body by the con- 
 traction of the left ventricle, while the remainder of this artery con- 
 tains venous blood, which is expelled by the combined action of both 
 ventricles. 
 
 It is impossible, in this arrangement, not to recognise an evident 
 design. In fact, if the whole force of the heart had been exerted to 
 send the blood towards the brain, the delicate texture of this viscus 
 would have been injured by it; the combined action of the two ven- 
 tricles was, on the contrary, required, to enable the blood to circulate 
 along the extensive and tortuous channels of the umbilical cord and 
 placenta. The aorta, on reaching the body of the fourth or fifth lum- 
 bar vertebrae, divides into the two umbilical arteries ; these send to the 
 pelvis and to the lower parts only very insignificant branches, which 
 convey blood that contains a very small quantity of oxygen ; 
 they then bend along the sides of the bladder, incline inwards, ap- 
 proach towards the urachus, pass out of the abdomen at the umbi- 
 licus, and, joining the umbilical vein, which had entered through the 
 same opening into the body of the fostus, form with it the umbilical 
 cord. 
 
 CCXI. The length of the umbilical cord, measured from the 
 umbilicus to the placenta, is from twenty to twenty-four inches. It 
 may be not above six inches long, or may greatly exceed that length, 
 as is proved by a case of M. Baudelocque, in which the umbilical 
 cord was fifty-seven inches in length, and passed seven times round 
 the child's neck, which circumstance, by the way, shews that the foetus 
 moves in its mother's womb. Of the three vessels "which form the 
 umbilical cord, two, which are the smallest, have an arterial structure, 
 though they convey blood that is truly venous, while the umbilical 
 vein carries arterial blood to the foetus. The umbilical arteries di- 
 vide on reaching the placenta, and are lost in its substance, in a multi- 
 tude of vessels, whose extremities deposit into the areolee of its tissue 
 the blood coming from the foetus, and which is to be returned to the 
 mother. Does the course of injection from the umbilical vein into
 
 NOURISHMENT OF THE FffiTUS. 475 
 
 the arteries prove that there exists an anastomoses between the extre- 
 mities of these vessels ? 
 
 The foetus is connected to the mother by the umbilical cord and 
 placenta : the veins, or the lymphatics of the uterus, and perhaps 
 both these sets of vessels, take up, in the spongy tissue 6f the placenta, 
 the blood that has been employed in the nutrition of the foetus, and 
 return it to the mother, that, after undergoing a change by the action 
 of her^ organs, and especially by that of the atmospherical air, by 
 means of the pulmonary circulation, it may become fit for the nourish- 
 ment of the foetus. Whether we inject the uterine vessels, or whether 
 we force the wax along the umbilical vein, it never fills but a part 
 of the placenta, which has led to the division of this substance into 
 two parts, the one belonging to the mother, which has been called 
 uterine, the other, called the fcetal portion, which forms a part of the 
 umbilical cord. 
 
 The vessels of the mother do not, therefore, anastomose with those 
 of the foetus within the placenta : the circulation is not continued from 
 the one to the other. If the communication were immediate, the beats 
 of the pulse of the child ought to be simultaneous with those of 
 the mother, whereas they are much more frequent, as may be observed, 
 at the time of birth, before the division of the umbilical cord. If the veins 
 of a bitch ready to whelp are opened, the animal dies of haemorrhage, 
 and her body remains bloodless. The placenta, however, is empty 
 only in the part that adheres to the uterus ; the rest of the placenta, as 
 well as the foetus, are filled with blood, as usual. It is obvious, that if 
 the vessels of the uterus had been directly continuous with those of the 
 placenta, delivery would not have taken place without their being 
 torn : alarming haemorrhage, inflammation, and even suppuration of the 
 uterus, would have been the consequence. Lastly, the force with which 
 the heart and arteries of the mother impel the blood along her vessels, 
 would have been attended with danger to the organs of the foetus, 
 which are too soft to sustain without injury so violent a shock. Though 
 the placenta and the umbilical cord form the bond of union between 
 the foetus and the mother, it must be confessed that they belong 
 chiefly to the former, and may be considered as a continuation of its 
 body. 
 
 CCXII. Of the nourishment of the foetus. The existence of the 
 foetus is solely vegetative ; he is continually drawing from the juices 
 which the vessels of the mother send to the placenta, what is to serve 
 for his nourishment and growth. He may be considered as a new 
 organ, the product of conception, participating in general life, but 
 having a peculiar life, and, to a certain degree, independent of 
 that of the mother. Bent on himself, so as to occupy the least pos- 
 sible space, he cannot be considered as asleep ; for, not only are the
 
 476 NOURISHMENT OF THE FffiTUS- 
 
 organs of sense and of motion in a perfectly quiescent state, but, 
 besides, several of the functions of assimilation are inactive, as diges- 
 tion, respiration, and most of the secretjons. The foetus performs, in 
 the midst of the liquor amnii, spontaneous motions, which accou- 
 cheurs reckon among the signs of pregnancy. The existence of these 
 phenomena has been denied, and the displacement of the foetus has 
 been ascribed to a mere shaking of the body : this was asserted on the 
 ground of the intimate connexion between respiration and muscular 
 motion. It was said, that the blood of the foetus, not being impreg- 
 nated with oxygen in its passage through the lungs, contractility would 
 not exist. But besides that a fact may be certain without being easily 
 explained, it may be answered, that the mother fulfils this office for 
 the foetus, and sends it arterial blood, fitted to maintain the con- 
 tractility of the muscles. 
 
 As we perform no motion but in virtue of impressions previously 
 received, and as the organs of sense in the foetus are completely inac- 
 tive, it is not easy to say why it should move in the womb. The 
 touch, however, is exerted when any part of the surface of the body of 
 the foetus comes in contact with the internal part of the cavity in 
 which it is contained. Lastly, the internal impressions experienced 
 by the great sympathetics may act as an occasional cause of such 
 motions. 
 
 The foetus is nourished, like every other organ, by appropriating to 
 itself whatever is suited to its nature in the blood brought to it by the 
 vessels of the uterus. The interception of this fluid by a ligature, or 
 by compression of the umbilical cord, would occasion death, though 
 not, as has been imagined, by a sudden and quick suffocation, but the 
 action of the organs would become gradually weakened, and at last 
 cease, when the fluids of the foetus, being no longer vivified by the 
 mixture of new juices from the mother, would be completely deprived 
 of their nutritive parts. It is now well ascertained that the liquor 
 amnii does not serve to the nutrition of the foetus, whose mouth is 
 closed, whose head is bent on his breast, and whose intestinal canal 
 is filled with a fluid different from that in which the whole body is 
 immersed. Besides, may not the unctuous substance with which the 
 surface of the skin is covered, prevent the absorption which might 
 otherwise take place from the outer part of the body ?* 
 
 It was long believed that the foetus was in an upright position 
 during the first months of life, but that, towards the end of pregnancy, 
 
 * May not also this substance, which is the produce of the small sebaceous 
 glands of the skin, prevent the cuticle from being macerated in the surrounding 
 fluid, owing to its being repulsive of water, and to its being retained closely applied 
 to the cuticle by the fine downy hair, or pubescence, whicty thinly covers the skin 
 during the early periods of existence? J. C.
 
 OF MONSTROUS FffiTUSES. 477 
 
 it fell into a different position, and lay with its head downwards. This 
 erroneous opinion, believed from its antiquity, and because it was 
 admitted by several physiologists, is completely refuted in Professor 
 Baudelocque's work on midwifery. The absurdity of this hypothesis is 
 manifest, if it be considered that the head of the embryo, the most 
 bulky and weighty part of the body, must necessarily occupy the most 
 depending part. 
 
 The plumpness and the strength of the foetus do not altogether 
 depend on the strength of the mother. Corpulent and strong women 
 often bring forth puny children ; while others, who are thin and feeble, 
 bring forth children plump and healthy. Such instances, however, 
 are exceptions to the general rule, as, cateris paribus, the healthy state 
 of the fetus is to be estimated by that of the mother. The morbid 
 condition of the fluids of the mother has a considerable influence on 
 the health of the foetus, and is, perhaps, the way in which hereditary 
 diseases are transmitted, which diseases by others are ascribed to a 
 diseased state of the semen. 
 
 The foetus is subject to affections of various kinds, whether of spon- 
 taneous origin, or arising from a germ received from the mother. 
 Foetuses have been seen with cicatrices, which clearly shewed that 
 solutions of continuity of various kinds had taken place. A -child, 
 born with the loss of some limb, has met with the accident in conse- 
 quence of some affection experienced in the womb. Professor Chaus- 
 sier having been called in to a case of this kind, found the hand and a 
 portion of the fore-arm among the membranes.* 
 
 CCXIII. Of monstrous foetuses. As it is useful to study nature, 
 even in her irregularities, I shall say a few words on the subject of 
 monsters, adopting the arrangement proposed by Buffon, of dividing 
 them into three classes : the first including monsters from excess, 
 the second monsters from defect, the third including those in which 
 there is a misplacement of organs. In the first are included those 
 which have supernumerary limbs or fingers, or even two bodies joined 
 in various ways. In the second, children born with a hare-lip, or who 
 are deficient in some one part. In the last place, those monsters 
 belong to the third class in which there is a general transposition of 
 organs ; when, for example, the heart, the spleen, and the sigmoid 
 flexure of the colon, are on the right side, and the liver and ceecum on 
 the left : those born with hernise of different kinds likewise belong to 
 this class. One may reckon, among these monstrous conformations, 
 spots in the skin, the colour of which always resembles that of some 
 of our fluids, but whose various forms are purely accidental, though, 
 from prejudice one is apt to imagine some likeness to objects longed 
 
 * See the APPEVDIX, Notes O O.
 
 478 OF MONSTROUS F03TUSES. 
 
 for by pregnant women accustomed to those fantastic appetites and 
 longings so frequent during pregnancy. 
 
 Various attempts have been made to account for these unnatural 
 formations ; some, as Mallebranche, attributed them to the influence 
 of the mother's imagination on the foetus in the womb ; others, as 
 Maupertius, thought that her passions communicated to her humours 
 irregular motions, which, acting with violence on the delicate body of 
 the embryo, disturbed its structure. Disease, while the child is in 
 utero, is a much more probable cause of such affections. 
 
 If two foetuses, contained in one ovum, lie back to back, and if the 
 surfaces at which they are in contact become affected with inflamma- 
 tion, it is easy to conceive that adhesion may take place between them. 
 By placing in a confined vessel the fecundated ova of a tench or any 
 other fish, the numerous young ones which are formed, not having 
 space sufficient for their growth, adhere to each other, and fishes truly 
 monstrous in their formation are produced. 
 
 When, from disease, or from an original malformation, the body of 
 the foetus is deficient in some of its parts, the others are better nou- 
 rished, and grow to a large size. Hence, in acephalous monsters, as 
 there is no brain, the blood which should be sent to that viscus going 
 to the face, it acquires a remarkable enlargement. 
 
 One of the most curious of all the cases of monstrosities, depending 
 on an original defect in the organisation of the germs, is that which 
 was sent, a few years ago, by the Minister of the Interior, to the School 
 of Medicine at Paris. I shall give an abstract of it from a more 
 detailed account, drawn up with much accuracy and sagacity by 
 M. Dupuytren. 
 
 A young man, thirteen years of age, had complained, from his 
 infancy, of pain in the left side and lower part of the abdomen. 
 This side had been prominent and contained a tumour from the earliest 
 period of life. At the age of thirteen he was seized with fever, the 
 tumour increased in bulk, and became very painful. Some days after, 
 he voided by stool purulent and foetid matters ; at the end of three 
 months he became wasted by marasmus, he passed by stool a ball of 
 hairs, and, in the course of a few weeks, died of consumption. 
 
 On opening his body, there was found in a cavity, in contact with 
 the transverse arch of the colon, and communicating with it, some balls 
 of hairs and an organised mass. The cyst, situated in the transverse 
 mesocolon, near the colon, and externally to the digestive canal, com- 
 municated with the intestine. But this communication was recent and 
 accidental, and one could plainly see the remains of the septum between 
 these cavities. The organised mass presented in its forms a great 
 number of features of resemblance with the human foetus, and, on 
 dissection, no doubt could be entertained of its nature. There was
 
 OF MON5TUOUS FffiTUSES. 479 
 
 discovered in it the trace of some of the organs of sense, a brain, a 
 spinal marrow, very large nerves, muscles converted into a sort of 
 fibrous matter, a skeleton consisting of a vertebral column, a head and 
 pelvis, and limbs in an imperfect state ; lastly, a very short umbilical 
 cord, attached to the transverse mesocolon at the outer part of the 
 intestine, and an artery and vein, ramifying at each of their extremities, 
 where they were in contact with the fetus and with the individual 
 which contained it. This much is sufficient to establish the distinct 
 existence, as an individual, of this organised mass, though in other 
 respects destitute of organs of digestion, of respiration, of the secretion 
 of urine, and of generation. The absence, however, of a great number of 
 the organs necessary to the maintenance of life, should make it be con- 
 sidered as one of those monstrous fetuses not destined to live beyond 
 the moment of birth. This foetus was evidently contemporary with the 
 boy to whose body it was attached. Similar to the product of extra- 
 uterine conceptions, it received its nourishment from that which may 
 be considered as its brother, and whose germ had originally enclosed 
 its own. During the thirteen years of the life of Bissieu, (this was the 
 name of the subject of this singular case,) the organised mass obtained 
 from the mesocolon, by means of vessels of its own, the blood necessary 
 for its existence : this blood, propelled by the organs of circulation 
 into the body of the foetus, returned afterwards to the mesocolon of the 
 boy who had so long been to him as a mother. At last, the period 
 fixed by nature for expulsion being arrived, and this expulsion being 
 impracticable, the cyst became inflamed ; the inflammation extended 
 to the intestine, the part which separated these two cavities were 
 destroyed, and the cyst opened into the colon ; pus and hair were 
 voided by stool, and the patient died of marasmus. The drawings of 
 different parts of the body of this foetus, taken by M. Cuvier and 
 M. Jadelot, render this interesting case most complete. They will be 
 published in the first volume of the transactions of the Academical 
 Society, near the Faculty of Medicine at Paris.* 
 
 We ought not to be ready to place implicit confidence in the 
 extraordinary stories contained in the older writers, and even in some 
 of the moderns. In reading the periodical publications of the seven- 
 teenth, and even of the eighteenth century, one is apt to wonder at the 
 marvellous things which they contain. Among other strange cases, is 
 that of a girl that was born with a pig's head; another, of a woman 
 
 * Mr. Young, of London, has communicated a case of the same kind, in a valu- 
 able paper inserted in the first volume of the Medico-Chirurgical Transactions. In 
 Mr. Young's case, the fetus was contained in a cyst that seemed to answer the 
 purpose of membranes and placenta ; it was without a brain, but had imperfectly 
 formed digestive viscera, and external organs of generation. See vol. i. of the 
 Medico-Chirurgical Transactions. T.
 
 480 THE COVERINGS OF THE FOETUS. 
 
 who was delivered of an animal, in every respect like a pike. There 
 was a time, says a philosopher, when philosophy consisted merely in 
 seeing prodigies in nature. 
 
 CCXIV. Of the coverings of the foetus. The name of after-birth 
 is given to the envelopes of the foetus, because they are not expelled 
 from the uterus till after the birth of the child. The ovoid sac, which 
 contains the foetus, is formed by two membranes in contact with each 
 other. The name of chorion is given to that which, by its external and 
 shaggy surface, adheres to the inside of the uterus : the other, a con- 
 centric membrane to the former, but of less thickness, and to be 
 considered as the secretory organ of the fluid which fills the ovum, is 
 called the amnion. The third envelope, admitted by Hunter, and 
 called by that physiologist the membrana decidua, is nothing more 
 than the lanuginous tissue presented by the external part of the cho- 
 rion, after tearing the multitude of cellular and vascular filaments by 
 means of which the ovum adheres to the uterus. The placenta is itself 
 merely a thicker portion of nearly the same tissue in which the umbi- 
 lical vessels are ramified. The uterus is also thicker at the part which 
 corresponds to the placenta, because it is there that the communication 
 of the foetus with the mother is established. 
 
 The membrana decidua, a perfect epichorion, as it has been called 
 by M. Chaussier, is the result of the generative orgasm. It is formed 
 on the internal surface of the uterus from the irritation excited by the 
 act of impregnation. It serves to unite the ovum to the interior of the 
 uterus; and, although the ovum may never reach this viscus, the 
 decidua is developed, notwithstanding, on its internal surface. This 
 circumstance is always observed in extra-uterine fetation. 
 
 Recent researches into the nature of the membranous tissue, by 
 means of which the human ovum adheres to the interior of the womb, 
 particularly the inquiries of MM. Moreau and Velpeau, have shewn 
 that the deciduous membrane of Hunter, called the epichorion by 
 Professor Chaussier, is in all respects a serous membrane, contiguous 
 to itself, and adherent on one side to the interior of the uterus, on the 
 other to the exterior of the chorion. This opinion respecting the 
 medium of union between the foetus and uterus (according to which 
 the ovum may be considered as being attached to the womb in the 
 same manner as the viscera are to the abdomen) seems plausible, and, 
 besides analogy, it has several authentic observations as to the exist- 
 ence of a contiguous and moistened surface existing in the substance 
 of the decidua, in its favour. M. Desormeaux has long taught, in his 
 lectures, that the deciduous membrane is disposed after this manner, 
 namely, that itformsaduplicature or is contiguous to itself; indeed, the 
 beautiful plates of the impregnated uterus, by Dr. W. Hunter, shews 
 this conformation.
 
 THE TKKM OF UTEKO-UESTATION. 481 
 
 The liquor amnii is a serous fluid, of a sweetish odour, and insipid 
 taste, rendered slightly turbid by a milky substance which it holds 
 suspended, and somewhat heavier than distilled water, 1-004. It is 
 almost completely aqueous ; albumine, soda, muriate of soda, and phos- 
 phate of lime, were discovered in it by MM. Buniva and Vauquelin, 
 forming only 0*012 of the whole mass. It turns tincture of violets 
 of a green colour, and reddens that of turnsole ; a very remarkable 
 circumstance, as is observed by the last-mentioned philosophers, and 
 indicating the co-existence of an alkali and of an acid in a separate 
 state. The latter is in so small a quantity, so volatile, and so soluble 
 in the liquor amnii of woman, that it has never yet been obtained bv 
 itself : there is found, however, in the liquor amnii of the cow a pecu- 
 liar acid, called by MM. Buniva and Vauquelin, the amniotic acid. 
 The liquor amnii is in greater quantity in proportion to the size of the 
 fetus, according as the latter is nearer the period of its formation. It 
 is the product of arterial exhalation. Its materials are supplied by the 
 blood conveyed by the vessels of the uterus. This is proved, not 
 merely by analogy, but likewise by observing the connexion between 
 the qualities of the liquor amnii and the regimen of the mother. In a 
 woman who had used mercurial friction in the course of her pregnancy, 
 the liquor amnii was observed to whiten copper. 
 
 The fundus of the bladder in quadrupeds is continuous with a 
 canal, of which the rudiments are observed in man, and which is called 
 the urachus. This canal joins the umbilical vessels, passes out with 
 them at the umbilicus, and terminates in a membranous sac between 
 the chorion and the amnion : it is called the allantois ; it is always 
 found in the fetus of the lower animals, but it is very indistinct, and 
 often does not exist in man. Some anatomists say, they have seen the 
 urachus arising from the human bladder, and which is commonly 
 ligamentous, terminate in a small vesicle, which some of them compare 
 to a melon seed ; while others say its bulk does not exceed a millet or 
 hemp seed. So small a vesicle can certainly answer no purpose ; the 
 urachus always forming a solid cord, seldom pervious, and even of very 
 small bore in the part nearest the fundus of the bladder. The exist- 
 ence of these parts furnishes an additional proof of what was stated in 
 speaking of the uses of the valve of the csecum, viz. that there are in 
 the animal body organs which answer no purpose, and which merely 
 indicate the plan which Nature has followed in the reproduction of 
 beings, and the gradations which she has uniformly observed in the 
 divisions of the species.* 
 
 CCXV. Of the natural term of utero-gestation. The fetus may 
 
 * See APPENDIX, Notei Of). 
 i )
 
 43'-' OF PAKTUUITIOX. 
 
 exist without the maternal influence, when arrived at the period oi 
 seven or eight months from the instant of conception. All accoucheurs 
 agree that it may be delivered alive at this period, and that it stays 
 two months longer in the uterus only that it may gain more strength, 
 and be better fitted to resist the new impressions which it is to expe- 
 rience on coming into the world. A child, however, has been known 
 to live, though born at the sixth month of pregnancy, in premature 
 labour ; but, in general, -the child is the more likely to live when born 
 at the usual period; that is, towards the end of the ninth solar month, 
 or of the tenth lunar. It is observed, that children bom at seven 
 months, however robust they may prove afterwards, are very feeble 
 when born, have their eyes closed, and are in a state of extreme debi- 
 lity and suffering during the two months which they ought to have 
 spent in their mother's womb : this proves how necessary it is that 
 gestation should be carried on to the end of the ninth solar month. 
 
 If the foetus may live, though separated from its mother before the 
 natural period, may it not, likewise, remain longer within the womb, 
 grow with less rapidity, and be expelled some days, weeks, and even 
 months later? How difficult therefore will it not be to assign a 
 precise term, beyond which we shall not be able to admit the 
 possibility of a late birth ! 
 
 There are said to be authentic cases of children born more than 
 ten months after -conception ; yet the laws, which cannot be founded 
 on rare exceptions, do not allow of so long a period in deciding of the 
 legitimacy of children born after the dissolution of matrimony. 
 
 CCXVI. Of parturition. When the foetus has remained suf- 
 ficiently long within its mother's womb to acquire the degree of 
 strength required for its insulated existence, it becomes separated from 
 her, carrying along with it the parts which enclosed it, and by which 
 it was connected to the uterus. Its expulsion from the uterus is 
 called delivery. The most ridiculous opinions have been entertained 
 with regard to the causes which determine the coming on of labour : 
 according to some, Fabricius of Aquapendente for instance, it is the 
 want of fresh air which makes the foetus rupture its membranes; 
 according to others, the foetus is determined to the same process by 
 the necessity of voiding the meconium, an excrementitious fluid which 
 fills the intestinal canal. It has been said, that the foetus was urged 
 to it by the want of food, or that labour depends on the re-action of 
 the fibres of the uterus, which, distended beyond measure, towards the 
 end of pregnancy close on themselves, and overcome the resistance of 
 the cervix uteri, which is thinned and gradually dilated. But if this 
 last hypothesis be correct, and it is the only one that is at present in 
 any esteem, how conies it, that in a woman whose uterus is of a
 
 OF PARTUKITIOX. 433 
 
 determinate size, labour does not come on when there are twins at the 
 end of four months and a half, by which period the same degree of 
 distension would be produced as by one child at the full time ? 
 
 It is very true, that for a fortnight, and even sometimes for a 
 month, before labour, the uterus seems to be preparing for the 
 expulsion of the foetus. This, at least, may be inferred from the 
 prominence of the cervix of the uterus, which may then, sometimes, be 
 felt ; and which is evidently produced by the membranes containing 
 the waters, which insinuate themselves within the orifice of the uterus, 
 when this organ contracts, and which collapse and recede when the 
 uterus is relaxed. 
 
 The product of conception, after a certain time, reaches a period 
 at which it may exist separated from the mother. When this period 
 is arrived, the ovum in which it is contained detaches itself from the 
 uterus by a mechanism in every respect similar to that by which the 
 stalk of a ripe fruit drops from the bough on which it hung. Then, in 
 all probability, the foetus refuses to admit the blood sent to it by die 
 umbilical vein ; the placenta becomes affected with congestion ; the 
 stagnation of the fluid extends gradually to the uterus and to the 
 neighbouring parts. Stimulated by their presence, these organs are 
 called into action ; the woman feels wandering, irregular pains, similar 
 to cholic pains, which become more acute, are attended with a feeling 
 of constriction, and act from above downwards, that is, from the 
 fundus to the cervix of the uterus. This contractile cavity, assisted by 
 the diaphragm and abdominal muscles, then acts with redoubled effort 
 to expel its contents. The pains become more acute and frequent; 
 the face red, the pulse full and accelerated ; the whole body seems to 
 partake in the affection of the uterus, and is agitate"d with convulsive 
 motions. The membranes, filled with the waters, force themselves, 
 like a wedge, through the mouth of the uterus, whose edges are much 
 weakened ; the throes of labour increase in strength and number, the 
 membranes rupture, the liquor amnii escapes, the head of the child 
 follows, and it soon clears the mouth of the uterus with most 
 excruciating pains. 
 
 These pains are particularly severe when, the sacrum not being 
 sufficiently concave, the nerves of the sacral plexus are violently 
 compressed by the head of the foetus : this part of the body almost 
 always presents first ; it passes through the upper outlet of the pelvis 
 in an oblique direction, the occiput being turned forward, and cor- 
 responding to one of the acetabula, while the face is directed backward 
 towards one of the sacro-iiiac junctions. It passes thus along the 
 greatest diameter of the pelvis ; but in descending lower down in the 
 pelvis, it describes a portion of a circle, and passes through the lower 
 outlet of the pelvis at its greatest diameter, which is from the fore to
 
 484 OF PARTURITION. 
 
 the back part. The head descends through the vagina, appears 
 outwardly, soon disengages itself, and is followed by the shoulders and 
 the rest of the body. Thus it is thai Nature, after having produced 
 fecundation by an act attended with pleasure, expels the product of 
 conception in the midst of pain. 
 
 CCXVII. The passages along which the foetus is carried out of 
 the body would be too confined, in their ordinary state, to allow 
 expulsion to take place without laceration, if, as I am going to 
 explain, Nature had not disposed every thing to facilitate labour. In 
 fact, Nature has not only formed the foetal skull of several flexible 
 pieces, separated by membranous unossified spaces, so as to allow the 
 bones to move over one another, and the whole head to be reduced in 
 size, in passing through the female pelvis; but she has, besides, 
 united the bones of the pelvis in such a manner that their articu- 
 lations become evidently relaxed towards the end of pregnancy. 
 During the progress of utero-gestation, the fluids of the mother flow, in 
 every direction, towards the pelvis and the parts which it contains ; 
 the ligamento-cartilaginous articulations of the pubes, of the sacrum, t 
 and loccyx, soaked in fluids, unite, with less firmness, the bones 
 between which they are placed. Hence, being softened and swollen, 
 they de not force them asunder like a wedge, by increasing their 
 diameters, but facilitate the separation of the bones, by the passage of 
 the head through the pelvis. It is on the relaxation of the articu- 
 lations of the pelvis that the indication for the operation of dividing 
 the symphysis pubis, rests ; an operation performed successfully by 
 Signault, and by Professor Alphonse Leroy. Analogy led very 
 naturally to this operation, as is judiciously observed by M. Thouret, 
 in the same manner that the invention and application of the forceps 
 were founded on a consideration of the means employed by Nature to 
 lessen the bulk of the child's head during the progress of labour. 
 
 The foresight of Nature is not limited to the facilitating the 
 motion on one another of the osseous parts of the skull of the foetus, 
 and of the pelvis of the mother ; her care extends to the soft parts of 
 the latter : these are soaked in mucus, so as to relax their tissue, 
 several days before parturition, and are so disposed, as was already 
 observed (CCI.). that they may, without rupture or violence, and by the 
 mere unfolding of the folds of the skin, yield to a considerable degree. 
 As the placenta and the membranes are not expelled immediately after 
 the foetus, it is customary to separate them, by dividing the umbilical 
 cord near the navel. It is unnecessary to tie this cord at the part 
 near the mother, every communication being intercepted between the 
 placenta and the uterus, so that no blood could flow but that of the 
 placenta. Not so, however, with the part nearest the foetus : though 
 the changes which take place in the circulation at the moment when
 
 OF TWINS. 485 
 
 the chest is dilated, and allows the air to distend the pulmonary tissue, 
 divert the blood from the umbilical vessels, yet these changes in the 
 circulation of the fluids might come on slowly, from the weakness 
 of the new-born child : hence it is always prudent to prevent by a liga- 
 ture a loss of blood that would increase the debility. 
 
 The human ovum is very seldom detached entire, and never so 
 without considerable danger ; that is, the fetus is not expelled with its 
 membranes, and in the liquor amnii; for these are not, in general, 
 expelled till a quarter of an hour, half an hour, or even a full houi 
 after the delivery of the foetus. When the uterus is completely 
 emptied of the placenta and the membranes, its cavity becomes obliterated 
 by the approximation of its sides; this organ, contracted on itself, 
 sinks behind the pubes, its cervix closes, and this even impedes the 
 delivery of the after-birth, when the latter is protracted too long. The 
 parietes of the uterus, imbued with fluids, are thicker than in their 
 natural condition ; but they decrease in size, in consequence of the 
 lochial discharge, and return to their wonted thickness. 
 
 When the labour is over, the uterus falls, as it were, asleep, and 
 enjoys repose after painful exertion. The humours cease to be 
 determined to that organ, towards which they are no longer di- 
 rected by any irritation, and they flow towards the mammary glands, 
 to supply the secretion of the fluid which is to nourish the new-born 
 child. 
 
 CCXVIII. Of twins. Though in the human subject the offspring 
 is generally single, it is not uncommon for a woman to bring forth two 
 children at once; it has even been calculated, that the proportion of 
 twin cases to single births was as one to eighty. Indeed, there are cases 
 of women who have brought three children at a birth. Haller calculates 
 that the number of these last, compared to those of single births, is as 
 one to seven thousand. The cases of four children at a birth are still 
 less frequent; and if three children born at once seldom live long, the 
 others, which, when born, are of the size of children at five months, 
 cannot live. Only one or two instances are known of five children 
 having been born at a birth : Haller, therefore, is guilty of ex- 
 aggeration in saying that these cases are to the ordinary cases in the 
 proportion of one to a million. I take no notice of the instances in 
 which a greater number are said to have been delivered at once, 
 because those cases are not well authenticated. In the case of twins, 
 each child has its own umbilical cord, terminating sometimes in a 
 separate, and sometimes^ in a single placenta. Both foetuses are 
 enveloped in one chorion, but each has a distinct amnion, and floats in 
 a separate liquor amnii. It would be curious to know, whether in 
 women who have had twins, as well as in animals, one should find
 
 486 OF SUFEKFffiTATiOXS 
 
 two cicatriculae, both in the same ovarium, or one in each. Twins arc; 
 generally very like one another in features and dispositions. 
 
 The multiplicity of foetuses in the same pregnancy is occasioned by 
 the presence of several vesiculae ready to be detached from the ovaria, 
 and consequently ripe for fecundation. This multiplicity of offspring 
 contributes very little to increase population, for they are in general 
 less robust and strong, and not so capable of reproduction ; they, 
 besides, exhaust the strength of the mother, and their birth is often 
 fatal to her. The number of children which a woman might bring 
 into the world, from the period of puberty to the cessation of the 
 menstrual discharge, would be much greater than it generally is, if no 
 time were lost. Some women have been known to have twenty-four, 
 thirty, thirty-nine, and even fifty-three children. A woman died in 
 North America after having had five hundred children and grand- 
 children, of whom two hundred and five survived her. 
 
 It is now well known, that the number of male children who are 
 born exceeds in general that of the females. The difference in some 
 countries is estimated at one in twenty-one, at a fourteenth, a twelfth, 
 and sometimes, though rarely, at a third. In all countries of the 
 world, polygamy is, therefore, in direct opposition to the intentions of 
 Nature and to the multiplication of the species : this is proved, in a 
 most undeniable manner, by the loss of population in those countries 
 in which this practice exists. The boys, more numerous than the 
 girls during the early part of life, exposed afterwards to the dangers 
 of war, of navigation, and occupied in laborious occupations, lead a 
 more anxious life, and die in greater numbers ; so that the equilibrium 
 is soon restored, and the least numerous portion of the human species 
 at the cradle forms about two-thirds of it in old age, since we always 
 see more women than men reach a very advanced period of life. 
 
 CCXIX. Of ~superf ostations. The cases of foetuses born with 
 unequal 'degrees of developement, are not to be considered as su- 
 perfcetations, but as twin cases. Thus, if in a case of twins, one foetus 
 is of its full size while the other is an embryo, whose size does not 
 exceed that of a foetus in the first month, it does not follow that their 
 conception took place at different and distinct periods, but merely that, 
 for some reason or other, one of the germs has been incapable of 
 growth and developement. 
 
 To settle the question of superfoetations, one should know whether 
 a woman, with a single uterus, is capable of conceiving two months 
 after effective copulation. Haller is of opinion, that the cervix of the 
 uterus is always open to the semen ; but how is the latter to reach the 
 ovaria through the adhesions of the chorion to the uterus? It 
 appears easier, where the two conceptions are. separated by a short
 
 
 Ol- SUCKLING. 4Z7 
 
 interval : thus, the American woman mentioned by Buffon, who, in the 
 course of one morning, had connexion with her husband and with a 
 negro slave, bore two children of different colours. Hence, likewise, 
 it sometimes happens, that one of twins is, by its features, a living 
 testimony of adultery. 
 
 Two children born with an interval of some months between their 
 births, cannot be considered as twins, though they may have existed 
 some time together within the mother's womb. The possibility of such 
 superfoetations is well proved ; they are ascribed to septa dividing the 
 uterus sometimes into two cavities, merely because such an arrange- 
 ment would explain, to a certain degree, how two conceptions might 
 take place at some interval from one another ; for it has never been 
 ascertained by actual dissection that any woman in whom such 
 superfoetations took place had a double uterus. 
 
 CCXX. Of suckling. Nothing is more generally known in 
 physiology than the strict sympathy which subsists between the uterus 
 and mammae ; a connexion, in consequence of which these two 
 organs are called into action at the same period of life, are evolved 
 and cease to perform their functions at the same time, when woman 
 becomes incapable of co-operating iR the reproduction of the species. 
 I shall not endeavour to account for this sympathy by ascribing it to 
 the influence of the nervous system, or to the anastomosis of the 
 epigastric with the internal mammary arteries an anastomosis which 
 is not uniform ; for, instead of inosculating with each other, these 
 vessels frequently terminate in the recti muscles of the abdomen. But 
 even though this anastomosis should exist as distinctly as it is often 
 met with in some subjects, it would not account for this sympathy ; 
 since the uterus and the mammas often receive no branches from the 
 epigastric and mammary arteries, and when they do they are ex- 
 ceedingly small. The breasts increase in size during pregnancy, 
 but they are largest after delivery. 
 
 The new-born child, on being brought in contact with the breasts, 
 applies its mouth to the nipple, and withdrawing its tongue, while 
 with its lips it compresses the edges of the nipple, he sucks in the 
 fluid, whose flow is facilitated by the erection cf the lactiferous tubes. 
 These ducts, from twelve to fifteen in number, not only become en- 
 larged when the nipple, which almost entirely consists of them, is 
 elongated by being drawn out by the child ; but, besides, being excited 
 by its touch, they become affected with a certain degree of erection, 
 and emit their fluid. This excretion, like that of other glands, is 
 expited by the touch and the motion of the hands of the child on its 
 nurse's breasts. The use of these gentle compressions is not so 
 much to express the milk mechanically, as to excite the organ to 
 excretion.
 
 488 OF SUCKLING. 
 
 The irritation produced by the child on the nipple is the most 
 powerful exciting cause of the determination of milk into the breasts; 
 this irritation, or any other of the same kind, is sufficient to excite 
 the secretion of milk, even under circumstances not provided for by 
 Nature. It is thus that virgins have been enabled to suckle another 
 mother's child ; that young girls under the age of puberty have' had so 
 complete a secretion of milk, as to furnish a pretty considerable 
 quantity of this fluid. There have been known men, in whom a 
 long continued titillation of the breasts had determined such an 
 afflux of the humours, that there oozed from them a whitish, milky, 
 and saccharine fluid, not unlike the milk of a woman. The sucking 
 of the new-born child is necessary to keep up the secretion of milk in 
 the mammae. It ceases to be formed in them when the child is com- 
 mitted to the care of a different nurse : the mammae, at first turgid, 
 soon collapse, especially if care have been taken to determine the fluids 
 downwards by exhibiting gentle laxatives. 
 
 The erection of the breasts by titillation on the nipple, the spas- 
 modic, and almost convulsive, action which follows this kind of ex- 
 citement, may be carried so far as to produce an emission of the fluid 
 to some distance. While its excretion lasts, women experience in their 
 breasts an agreeable sensation ; these parts are tense and swollen ; 
 they feel, as they express it, the milk rising ; several feel a sensation 
 of extension reaching to the axilla, to the arms and chest. The whole 
 mass of cellular substance surrounding the breasts and extending to 
 the neighbouring parts, partakes in their activity. 
 
 The breasts, themselves, consist, in great measure, of cellular sub- 
 stance ; an adipose and lymphatic layer, of a certain thickness, covers 
 the gland, which is divided into several lobes, and encloses it within its 
 substance. They receive a number of nerves, but very few blood- 
 vessels for their bulk. 
 
 Their structure appears almost wholly lymphatic : the vessels of this 
 kind, after being distributed to the neighbouring glands, and especially 
 to those of the axilla, penetrate into the breasts, in which their pro- 
 portion, compared to that of the sanguineous vessels, is as eight to one. 
 These lymphatic vessels, which enter in considerable numbers into the 
 composition of the breasts, increase greatly in size in nurses; and when 
 injected in this condition, it has been ascertained that several of them 
 joined to form larger trunks, which going towards the nipple, contri- 
 buted in forming what are called the lactiferous tubes. If the lym- 
 phatic vessels be immediately continuous with the excretory ducts of 
 the breasts, there is reason to believe that it is these vessels which 
 convey the materials of the fluid which they separate, especially if it be 
 considered how small is the number of minute arteries which are dis- 
 tributed into their tissue, and what a disproportion there is between the
 
 OF SUCKLING. 489 
 
 calibre of these small vessels and the quantity of blood which the 
 breasts supply. The opinion that the lymphatic vessels bring to the 
 breasts the materials of the secretion of milk, is not in opposition to 
 the laws of the circulation in the lymphatics : all who are acquainted 
 with these laws, know that the course of the lymph, though in general 
 from the circumference to the centre, is naturally liable to a number 
 of aberrations or deviations, facilitated by the numberless anastomoses 
 of these vessels. 
 
 CCXXI. The granulated structure is not so apparent in the 
 breasts as in the other glandular organs ; hence they bear a greater 
 resemblance to the lymphatic than to the conglomerate glands. The 
 milk which they secrete has always been considered as very like the 
 chyle, which it resembles in its white colour, its smell, and its saccha- 
 rine taste. Like the chyle, it is the least animalised fluid, the sweetest, 
 that on which the action of the organs produces the least effect, and 
 that which preserves most the characteristic qualities of the food taken 
 by the nurse. 
 
 It is well known, that instead of giving medicines to infants at the 
 breast, we most frequently administer the medicine to the nurse ; thus, 
 the milk acquires purgative qualities, and acts on the bowels of the 
 child, when the nurse has been purged.* The chyle is white and 
 opaque only in those animals which suckle their young ; in the others 
 it is as transparent as lymph. (Cuvier.) 
 
 In the last place, if the arteries carried to the breasts the materials 
 of their secretion, they ought to increase in size when these organs 
 become twice, or even three or four times larger than natural ; in 
 the same manner that in open cancer, and in other similar affec- 
 tions, in which the determination of blood being increased, the calibre 
 of the vessels is proportioned to them. Nothing, however, of the 
 same kind occurs, whatever size the breasts may acquire from the pre- 
 sence of milk : their arteries preserve their almost capillary minuteness, 
 as I had an opportunity of ascertaining, by injecting the mammae of a 
 woman twenty-nine years of age, who died in the second month of 
 suckling, and whose breasts were remarkable for their size, and by the 
 quantity of milk they were able to secrete. 
 
 Notwithstanding all these reasons, which made me formerly adopt 
 the opinion of the celebrated Haller, who considers the milk as 
 immediately extracted from the chyle, I own that it must be con- 
 sidered as hypothetical, and resting solely on probability. The im- 
 possibility of demonstrating anatomically the branches going from the 
 mesentery to the breasts without communicating with the thoracic 
 
 * This only takes place when such purgatives are used as are readily absorbed 
 into the circulation. .</. C.
 
 490 OF THK 1'llOPERTIES OF MILK. 
 
 duct, gives still greater probability to the generally received opinion, whirii 
 makes the milk, like all the other secreted fluids, with the exception 
 of the bile, to be supplied by arterial bjood. The passage of injections 
 from the arteries into the lactiferous tubes, and the circumstance of 
 blood having been drawn from an exhausted breast when the child has 
 been allowed to suck too long, and lastly, analogy, leave no doubt of 
 the true source of the fluid secreted by the mammae. 
 
 The milk does not resemble chyle in every respect, though it may 
 be considered as extracted from the food,* changed in its way to the 
 mammee by the glands through which it has passed, and especially by 
 the action of the organs themselves. This action is so evident, that, 
 as Bordeu observes, " there are women who seem to have no milk in 
 their breasts, which are flaccid and empty ; but as soon as the child 
 excites them, they become distended, and the milk comes sponta- 
 neously."' It is well known, and the same author has pointed it out, 
 that women, cows, and the females of other animals, allow themselves 
 more willingly to be sucked by a suckling that knows how to excite 
 their sensibility, and to apply due irritation to the nipple ; and that, 
 on the contrary, they retain their milk when the suckling does not 
 excite the sensation in which they feel pleasure. It is thought, in some 
 countries, that serpents know how to tickle the teats of cows, and that 
 these animals enjoy this excitement, and allow themselves to be sucked 
 by these reptiles. 
 
 CCXXII. Of the physical properties of milk, and of the chemical 
 nature of this fluid. The quantity of milk is in general proportioned 
 to that of the aliments, to the degree of their nutritious qualities, to 
 their moist and farinaceous nature. Though it equals in weight about 
 one-third of the quantity of food taken by the nurse, it may exceed 
 that proportion, or may not come up to it. Its specific gravity, even 
 when the milk is lightest, is greater than that of distilled water, and is 
 always proportioned to its consistency. The latter quality is in an in- 
 ferior degree in woman, but is greater in the cow, the goat, the ass, 
 and the ewe. Its fluidity is intermediate between that of aqueous and 
 oily liquids; its colour, its smell, and flavour, have something very 
 peculiar, and by which it is easily recognised ; in the last place, it is 
 not exactly alike at different periods of the same milking. This is 
 proved by the work of MM. Deyeux and Parmentier on milk, a work 
 abounding in valuable observations, and which may be considered as 
 the complete history of this animal fluid. They observed, that the 
 milk first drawn from the cow is serous, that its consistency gradually 
 increases, and that the richest milk is that which is obtained towards the 
 
 * " Lac utilis aliment! est superfluum." GALENUSC/C Usu Parlium, lib. vii. 
 rap. xxii.
 
 OF THE PROPERTIES OF MILK. 491 
 
 end of milking, as if the fluid contained in the udder were affected by 
 the laws of gravitation. 
 
 The milk, when exposed to the open air, in a vessel, becomes de- 
 composed like the blood, and separates into three parts ; the serum, 
 the curd or cheesy part, and the fatty part or cream. The latter, which 
 is lighter than the others, is always on the surface, and its quantity 
 depends not only on the richness of the milk, but also on the extent of 
 the surfaces by which it is in contact with the air ; and this proves, as 
 was first observed, by Fourcroy, that the oxygen of the atmosphere has 
 some influence on its separation. The caseous part, which coagulates 
 spontaneously, appears albuminous, and abounds in oxygen. MM. 
 Parmentier and Deyeux consider it as the colouring matter of milk, 
 and as giving to it its most characteristic properties. Lastly, the serum 
 or whey, which alone constitutes the greatest part of this fluid, con- 
 tains, besides a peculiar acid (the lactic acid), which is formed when 
 this substance is allowed to remain for some time, a saccharine matter, 
 which may be obtained by evaporation, and which, when crystallised 
 in rhomboidal parallelepipeds, constitutes the sugar of milk, whose purity 
 depends on the degree of care with which the process has been carried 
 on. This sugar of milk contains, as Scheele first ascertained, while 
 endeavouring, by means of the nitric acid, to convert it into the oxalic, 
 a peculiar acid, in the form of a powder, difficult of solution, and to 
 which he gave the name of saclactic acid. Milk may be considered as 
 one of the most compound of the animal fluids, whose qualities are very 
 valuable, and whose parts have but an imperfect affinity to each other ; 
 so that it is liable to spontaneous decomposition, which takes place very 
 easily. This kind of emulsion contains but a small quantity of azote, so 
 that it retains its vegetable character. Hydrogen, carbon, and "oxygen, 
 predominate in milk ; in the last place, it contains several salts, amongst 
 others, muriate of soda, muriate of potash, and phosphate of lime.* 
 
 The presence of the two last of these substances leads to the fol- 
 lowing considerations. Muriate of potash, as is observed by Rouelle, 
 does not exist in the blood ; the probability is, therefore, that it is not 
 the blood which supplies the mammae with the materials whence the 
 milk is secreted, muriate of potash being /ound in greater quantity in 
 milk than muriate of soda. These salts of potash, on the contrary, 
 are found in considerable proportions in the chyle, formed from vege- 
 table substances ; which would lead one to think that milk is furnished 
 by the absorbent system. The phosphate of lime, which is found in 
 smaller quantity in the urine of nurses, and which is wholly determined 
 towards th^ mammse, was absolutely necessary in a fluid which supplies 
 
 * See the chapter at the end of the Appendix, oil the Chemical Constitution of 
 the Secretions.
 
 492 OF THE PROPERTIES OF MILK. 
 
 nourishment to the new being, while the bones become indurated, 
 and all the parts acquire solidity. 
 
 If we now wish to inquire into the causes which render suction 
 necessary, and which subject the new-born child to this peculiar mode 
 of nutrition, these causes will be found in the general weakness of 
 its organs. The organs of digestion would have been incapable of ex- 
 tracting from the aliments their nutritive parts, these substances not 
 having undergone the due degree of trituration, from the want of teeth 
 and from the imperfect state of the other organs of mastication. It 
 was of consequence, therefore, that the mother should perform this 
 preliminary function, and that she should transmit the aliment ready 
 digested. * It is not, however, to be imagined, that the milk passes, 
 without undergoing any change, into the vessels of the child ; the 
 child digests the milk, and obtains from it in a short space of time, and 
 without effort, a considerable quantity of nutritious particles, necessary 
 to the rapidity of its growth. 
 
 The connexion between the mother and child is far from being 
 broken at the period of birth ; the relations between them, though not so 
 close, are not less indispensable. Before birth, the vital power was so 
 limited in the child, that it was necessary it should receive a fluid 
 already animalised, and in a state to yield to the function of assimilation 
 and nutrition. When the child has breathed, when its strength is 
 increased, it may be intrusted with a greater share of the process; it 
 is then sufficient that the aliment should have undergone the first 
 degree of elaboration within the digestive canal. But it is not merely 
 to assist in preparing its food, that the new-born child requires the aid 
 of the mother ; its lungs, which are delicate and imperfectly evolved, do 
 not supply a due quantity of oxygen to the blood which circulates 
 through them; the animal heat would be under what is required by 
 the wants of life, if the mother did not make up for this deficiency by 
 transmitting some of her own warmth. She folds her infant gently 
 to her bosom, warms it with her breath, and by this kind of maternal 
 incubation continues to cherish it with that calorific influence to which 
 it was fully exposed while forming a part of herself. Besides, she feels 
 for it, keeps it from dange/, foresees its wants, and understands its 
 language ; and this very interesting intercourse takes place after the 
 bonds of their physical communication are loosened, but it does not 
 tear them asunder. The infant is, therefore, detached from, the mother 
 only by degrees, since it is only in proportion as it grows older that it 
 acquires the means of an independent existence. 
 
 The secretion of milk in the breasts may be prevented by irritation 
 in the uterus. If the labour have been difficult, if the woman have 
 
 * Lac est cibus exactc confectus GALENUS de Usu Partium, lib. vii. cap. xxii.
 
 STATE OF THE I.ITNGS, &C. 493 
 
 suffered a certain degree of injury, the irritation in the parts so affected 
 prevents the determination of the fluids towards the mammae. Hence, 
 these organs collapse during puerperal fever ; not that the milk flows 
 back into the humours and becomes the cause of the complaint, but 
 that the inflammation of the uterus prevents the fluids from flowing in 
 their natural direction. 
 
 During the first few days after delivery, the parietes of the uterus 
 discharge a fluid, at first bloody, then of a reddish colour, and, in the 
 last place, mucous and whitish, termed the lochia. 
 
 CCXXIII. State of the lungs and foramen ovale in some cases, SfC. 
 All the parts of the lungs are not distended with air, in the first in- 
 spirations of the child after birth. Some of the lobes, which are 
 harder and more compact, take some time to admit this fluid, and even 
 sometimes altogether reject it. A child died twenty-one days after 
 birth ; the body was opened by Professor Boyer. On examining the 
 lungs, he found that the posterior part of these organs was as hard and 
 compact as in the foetal state. The anterior part alone was distended, 
 contained air, could be felt to crepitate, and floated in water. The 
 heart was examined, to ascertain whether its structure was connected 
 with the condition of the lungs, which depended on the want of power 
 in the respiratory functions. The foramen ovale was found pervious, 
 so that the blood could pass from the right into the left cavities of the 
 heart, without flowing through the lungs. The child had been exceed- 
 ingly languid during the whole of its short life ; its skin was at times 
 pale, at others livid. It was very difficult to keep it warm. 
 
 The child of Madame L**** died nine days after birth, with the 
 same appearances. I opened the chest, and found the upper part of 
 both lungs indurated and compact ; the foramen ovale was quite per- 
 vious. This aperture is often closed very imperfectly, so that there 
 remains, af the upper part of it, an opening, varying in size, which 
 would enable a small quantity of venous blood to pass from the right 
 into the left auricle, if these cavities did not contract at the same 
 moment, and if the fluid which they contain did not present equal 
 resistance on both sides. There are cases of persons in whom the 
 foramen ovale remained pervious, and who, nevertheless, lived to a 
 pretty advanced age. Their skin was purple and livid, all their moral 
 and physical faculties feeble and torpid. It would be interesting to 
 ascertain'hy dissection, whether in good divers, who can remain a long 
 while under water without breathing, the foramen ovale is not im- 
 perfectly closed.
 
 OF INFANCY. 
 
 CHAPTER XII. 
 
 OF THE PERIODS OF LIFE, THE TEMPERAMENTS, THE VARIE- 
 TIES, AND THE DISSOLUTION, OF THE HUMAN SPECIES. 
 
 CCXXIV. Of Infancy. CCXXV. Of Dentition. CCXXVI. Of Ossification. 
 
 CCXXVII. and CCXXVIII. Of Puberty. CCXXIX. Of Menstruation. 
 
 CCXXX. Of Manhood CCXXXI. to CCXXXVI. Of Temperaments 
 
 and Idiosyncrasies. CCXXXVII. Varieties of the Human Species 
 
 CCXXXVIII. Of Old Age and Decrepitude CCXXXIX. Of Death. 
 CCXL. Of the Period of Death, &C. CCXLI. Of the Probabilities of Hu- 
 man Life. CCXLII. Of Putrefaction, &c. 
 
 CCXXIV. Of infancy. The epidermis of the new-born babe thickens, 
 the redness of the skin grows paler, the wrinkles are effaced, the soft 
 down which covered the face falls and disappears, the buttocks swell 
 out and soon conceal the opening of the rectum. During the first 
 months of life, it seems to need nothing but nourishment and sleep. 
 In the meanwhile the understanding is beginning to form, it looks 
 fixedly at objects, and seeks to take cognisance of all the bodies that 
 surround it. Confined at first to the uneasy sensations which it ex- 
 presses by almost continual tears, its existence becomes less painful as 
 it grows accustomed to the impressions of outward things upon its 
 delicate organs. Towards the middle of the second month it becomes 
 capable of agreeable sensations. If it feels them before that time, at 
 least it is only then that it begins to express them by laughing.* 
 
 CCXXV. Of dentition. Towards the end of the seventh month, f 
 the middle incisor teeth of the upper jaw cut through the substance of 
 the gums : a little while after, the corresponding incisors of the lower jaw 
 
 * At Herculis risus praecox ille et celerrimus, ante quadragesimum diem nulli 
 datur P.LIN. Hist. Nat. praef. ad lib. viii. 
 
 + It would be very difficult to say why a tertian fever often terminates of itself 
 when it has reached its seventh paroxysm, whilst a continued fever is judged of by 
 critical evacuations, in seven, fourteen, or twenty-one days ; why delivery happens 
 at the end of nine months ; why the first teething begins at seven months old, the 
 second at seven years ; why puberty shews itself towards the fourteenth year, and 
 menstruation is repeated at determinate periods. Nature appears to subject herself, 
 in all her acts, to certain periods, which observation may ascertain without any 
 possibility of arriving at a knowledge of the causes of these phenomena, so easy to 
 establish. Because their manifestation is correlative to certain numerical terms, 
 we are not to put faith, like Pythagoras, in the power of numbers, and believe that 
 the numberS, and the numbers 7 and 9, enslave all nature to their supreme influence. 
 We find traces of this ancient error in all sciences, in all religions, even in those 
 of enlightened nations.
 
 01 DKNTITIOK. 495 
 
 shew themselves ; next, the lateral incisors of the upper jaw, afterwards 
 those of the lower, then the cuspidati, in the same order. At the age of 
 between eighteen moriths and two years, the small molar teeth appear, 
 but in reversed order, those of the lower preceding those of the upper 
 jaw. When these molar teeth have come through, the first dentition 
 is complete ; the life of the child is more secure :, it was before very 
 uncertain, since the calculations of the probable duration of human 
 life shew, that a third of the children born at any given time die before 
 the age of twenty-three months. Convulsions and diarrhoeas are the 
 most fatal accidents attending difficult dentition. To these twenty 
 teeth are added two new grinders in each jaw, when the child has 
 reached the end of his fourth year. These last will afterwards become 
 the first large grinders. They differ from those that precede them in 
 this, that they are to remain all life long, whilst the primitive or milk 
 teeth are lost at seven years old, in the same order in which they ap- 
 peared, and are replaced by new teeth, better formed and larger, 
 excepting the small grinders, and with longer and more perfect roots, 
 Towards the ninth year two new large grinders appear beyond the 
 others. The child has then twenty-eight teeth, and dentition is com- 
 plete ; though between eighteen and thirty, and sometimes much later, 
 the denies sapientiae, two to each jaw, shew themselves at the extre- 
 mities of the alveolar processes. 
 
 The order observed in the successive cutting of the teeth is not so 
 invariable but it is frequently inverted. A child ten years old, now 
 under my care, cut the four first small grinders before the canine teeth. 
 Dentition is, in this respect, like all other acts of the living economy 
 instability is its principal character. An attentive examination soon 
 shews how irregularly those phenomena proceed, whether physiological 
 or pathological, which appear the most to be subjected to calculable 
 and determinate periods.* 
 
 This double range of successive teeth ( existed in the jaws of the 
 foetus. Each alveolar process, at that age of life, contains two sets of 
 membranous vesicles, lying one over the other, ^hose which are to 
 form the primitive teeth swell the first, a calcareous matter covers their 
 surface and forms the body of the teeth, invading also the vesicle 
 by which it is secreted ; so that the growth of the tooth being 
 completed, the membranous vesicle, in the parietes of which the dental 
 vessels and nerves branch out, is found in the centre of its body, 
 and adheres to the parietes of its internal cavity. The teeth are, then, 
 secreted calcareous substances, or rather excreted by the dental vesicle : 
 the vessels ramified in the parietes of this vesicle are prolonged into 
 
 " See " Erreurs Populaires," sec. edit. chap. iv. " Des Anntes climatiriques, et 
 des Jours critiques dans les maladies."
 
 496 OF OSSIFICATION. 
 
 the osseous substance. This may at least be presumed, from the inti- 
 mate adhesion of the membrane with the osseous matter. The teeth 
 are possessed of, or participate in, the vitality of the system, and they 
 increase by intus-susceptiou, although they cannot resist the effects of 
 attrition, and are worn down by it. The primary dental germs are 
 connected with the secondary germs, or those which give origin to the 
 teeth of the second dentition, by means of membranous prolongations, 
 whfch are extended from the one set to the other, and which penetrate, 
 by small foramina, the alveolar processes. It is through these open- 
 ings, the foraminula of Soemmering, that the teeth of the second 
 dentition pass : the 'germs of these are behind those of the first denti- 
 tion, and the former are united to the latter, and pass to the alveolar 
 margin, as now stated. It is not very difficult to say why the growth 
 of the dental germs is successive ; why, in the seventh year, the pri- 
 mitive teeth are detached and are replaced by others which have 
 remained so long buried within the alveolar processes. The jaws grow 
 in every direction, and consequently the alveolar processes increase 
 their dimensions with the age of the individual. The primary teeth are 
 insufficient to furnish the dental arches, and hence nature replaces them 
 by means of a set which is of larger dimensions and more numerous. 
 Dentition is like all other phenomena of the living economy ; it is 
 subject to endless varieties in its period and duration, &c. Thus, teeth 
 of a third set have been known to be cut in very old people. There 
 are instances, but they are very scarce, of children that have come into 
 the world with two incisors in the upper jaw ;* there are often super- 
 numerary teeth, &c. 
 
 CCXXVI. Of ossification. The process which goes on in the 
 osseous system is not confined to the cutting and growth of the little 
 bones which are attached to the two jaws. All other parts of the 
 skeleton harden ; osseous nuclei are formed in the centre of the carti- 
 lages, which hold the place of the short bones of the carpus and 
 tarsus; the thickness of the cartilaginous substances which separate 
 the epiphyses of the bodies of the long bones is diminished ; the large 
 bones grow and acquire solidity from the centre to the circumference. 
 Those of the skull meet at their edges, their fibres cross and form the 
 sutures ; the cartilaginous spaces (fontanels), which were situated at 
 the meeting of their edges and angles, disappear. The urine contains 
 exceedingly little phosphate of lime, that salt being entirely taken up 
 in the solidification of the bones. 
 
 * Louis XIV. was born in this condition. Baudelocque observes, that the evo- 
 lution of some teeth before birth is not always connected with an extraordinary 
 growth of the infant, nor is it always a presage of a stronger constitution. He 
 endeavours to prove this by several examples ; these, however, may be regarded 
 as exceptions only from the general, and, we think, correct, opinion on the sub. 
 ject J.C.
 
 OF PUBERTY. 497 
 
 About the middle of the second year, the bones have already 
 acquired substance and solidity enough to support the weight of the 
 body ; the child can stand and walk. Before this time it would be 
 hurtful to allow either the one or the other to be tried : the pillars of 
 support, yet too flexible, would yield under the burden, and bend per- 
 manently in different directions. It is towards the head that the vital 
 motions tend in infancy : accordingly, this part is the principal seat of 
 the affections peculiar to this age, affections in which it is often of 
 use to procure local evacuations. 
 
 The organs of the senses, open to all sorts of impressions, receive 
 them with ease ; but if in early infancy sensation is easy, it is very 
 transient, no doubt from the want of consistence in the cerebral organ. 
 As it grows older, the mobility of the child is lessened without dimi- 
 nution of its susceptibility ; and it is during the years that precede the 
 boisterous season of puberty, that he enjoys, in the highest degree, the 
 faculty of recalling things that have affected him that his memory is 
 most distinct and extended ; but soon overpowered by imagination, 
 roused up by the powerful re-action of the sexual organs on the brain, 
 it ceases to have the same exactness. 
 
 CCXXVII. Of puberty. Sex, climate, manner of life, have great 
 influence on the earlier or later manifestation of the phenomena of 
 puberty. Women reach it one or two years before men : the inha- 
 bitants of southern long before those of northern countries. Thus, 
 in the hottest climates of Africa, Asia, and America, girls arrive at 
 puberty at ten, even at nine years old ; but in France, not till twelve, 
 fourteen, or fifteen ; whilst in Sweden, Russia, and Denmark, the 
 menstrual discharge, the most characteristic mark of puberty, is from 
 two to three years later. 
 
 The male is known to be capable of generation, and that he begins 
 to live the life of the species, by the emission of prolific semen, and the 
 change of voice, which becomes fuller, more grave, and sonorous: the 
 chin becomes covered with beard, the genitals with hair, and they 
 attain rapidly their full size. The whole body grows : the general 
 characters which distinguish the two sexes, and which are so obscure 
 before puberty that they may often be mistaken, become very decided, 
 and can no longer be confounded. 
 
 By all these signs of strength and virility, woman, urged by desires 
 which may be termed wants, recognises the being capable of gratifying 
 them. The change of voice is the most certain of the indications of 
 male puberty. It depends, as the following observations shew, on the 
 developement of the vocal organs, which constantly accompanies that 
 of the sexual parts. 
 
 K K
 
 498 OF MENSTRUATION. 
 
 CCXXVIII. A boy, aged fourteen, died in the year 1799, at the 
 Hopital de la Charite. On opening the larynx, I was surprised to see 
 it so small, and especially the glottis* which was not above five lines in 
 its anterio-posterior diameter, and about a line and a half in its trans- 
 verse diameter, where its dimensions are greatest: an observation that 
 must not be omitted is, that he was very tall, but that the develope- 
 ment of the genital organs was as backward as of the vocal. I have 
 repeated the same observation on subjects further from the age of 
 puberty I have extended my researches to those who had passed it ; 
 and I have obtained, as a general result, that between the larynx and 
 the glottis of a child of three or of twelve, the difference of size is very 
 inconsiderable, and cannot be estimated by the height of the figure. 
 
 That, at the epoch of puberty, the organ of the voice enlarges 
 rapidly, and that, in less than a year, the opening of the glottis in- 
 creases in the proportion of five to ten ; that its extent is thus doubled 
 both in length and breadth. 
 
 That these changes are less remarkable in women, whose glottis 
 increases in the proportion only of about five to seven ; that in this 
 respect they still resemble children, as the tone of their voices would 
 lead us to suppose. 
 
 These differences in the size of the glottis account for the danger 
 which, in children, accompanies the croup ; for, suppose an opening of 
 a line ahd a half in width, the edges of which are covered with a mem- 
 brane of coagulable lymph, the opening will be entirely stopped : it 
 would be only narrowed if its width were double ; a sufficient space 
 would remain free from the passage of the air. This supposition, 
 which I have employed to make myself understood, is only the expres- 
 sion of the truth, since anatomical inspection shews that the glottis in 
 adults is double the size it is before puberty. 
 
 CCXXIX. Of menstruation. The symptoms by which puberty is 
 known ;n women are not less remarkable. The swelling of the genital 
 organs straightens the opening of the canals that make part of them. 
 The breasts become enlarged, and form, at the fore-part of the thorax, 
 marked projections. Further, there comes on a discharge of blood, 
 which takes place every month, from the vessels of the womb, and 
 which is. known by the name of the menstrual discharge, or menses. 
 This periodical evacuation declares itself in most women by all the 
 symptoms that indicate fulness of blood, as, spontaneous lassitude, 
 heat, and flushings in the face ; and by others, which shew a direction 
 of the humours towards the uterus, and a local plethora of that organ, 
 as pains in the kidneys, and a certain itching of the parts. The first 
 eruption puts an end to this state, which in many may be considered
 
 OF MENSTRUATION. 499 
 
 as real disease. A pure red blood flows, in more or less abundance, 
 for some days, the general heaviness goes off, and the woman feels 
 herself relieved. 
 
 I shall not now speak of the many deviations incident to the men- 
 strual discharge, and which must be considered as real diseases. Thus, 
 the uterine discharge has been known to be supplied by bleeding from 
 the nose, haemoptysis, meleena; sometimes by unusual evacuations of 
 blood from the eyes, ears, the fore-finger, or from ulcerated surfaces 
 over different parts of the body. 
 
 It is easily conceived, that the different parts of the sanguineous 
 system may supply each other's place, and that the bloody secretion in 
 which menstruation consists, in failure of the internal surface of the 
 uterus, may be carried on by another part equally provided with capil- 
 lary vessels ; but that similar deviations may take place for the fluids 
 secreted by the conglomerate glands as urine, bile, saliva is difficult 
 to believe, notwithstanding the many testimonies and authorities that 
 may be brought in support of this opinion. 
 
 The fluids are not in existence before the work of secretion : the 
 urine, retained in the bladder and in the uterus ; the bile, accumulated 
 in the gall-bladder and the hepatic ducts, after it has been prepared 
 by the peculiar action of the liver, may, it is true, from absorption by 
 the lymphatic vessels, be carried into the blood, and produce there 
 a diseased urinary or bilious diathesis occasion an irritation and 
 derangement, after which the humour of the cutaneous perspiration 
 and of the sweat, and the saliva itself, will exhibit some of the qualities 
 of the humour retained, and introduced by the absorbents into the 
 circulation. The blood, contaminated by the admixture of a certain 
 quantity of urine, may purify itself by various emunctories, by urinous 
 vomitings and sweats ; but that urine may, like the menstrual blood, 
 come out at the eyes, the ears, or the navel, except in cases of urinary 
 umbilical fistula that one whose urinary discharge by the urethra is 
 not interrupted, may spontaneously vomit it, is what no man who has 
 any sound notions of physiology will believe ; and yet it is related, 
 with full details, in a late work, where these errors are found in the 
 midst of many interesting researches on various points of physiological 
 chemistry. I have myself seen the woman whose urine has been so 
 well analysed by Dr. Nysten, when the clinical professor of medicine at 
 Paris obliged her to submit to a severe but necessary examination, and 
 I am astonished that well-informed men should so long have given 
 credit to such gross impostures. The reader will, I hope, excuse this 
 long digression, for the sake of its importance. Literary criticism is 
 now carried on with such partiality, that no journalist, in praising 
 what is justly praiseworthy in the valuable work of Dr. Nyste'u, has 
 pointed out the imposture of which he was the dupe.
 
 500 OF MENSTRUATION. 
 
 At first irregular, the menstrual discharge assumes regularity, is 
 repeated every month, and lasts from two days to a week, with evacua- 
 tion of from three ounces to a pound of blood every time. Women of 
 sanguine temperament, robust and libidinous, are those whose menses 
 last longest and flow most copiously. The blood is arterial, red, and 
 has not, in a healthy woman, any of the pernicious qualities which 
 have been ascribed to it. 
 
 During the whole time of menstruation, women are weaker, more 
 delicate, more susceptible of impressions ; all their organs partake, 
 " more or less, in the affection of the uterus ; and it is not difficult to an 
 observer of any practice to discern the state, not merely by the state of 
 the pulse, but by the change of the countenance and tone of the voice. 
 Women then require very careful management. An improper blood- 
 letting, a purge, or any other remedy untimely administered, may sup- 
 press the discharge, and occasion the most serious affections. Climate 
 evidently influences its duration and quantity, since in Africa it flows 
 almost continually, whilst in Lapland it takes place only two or three 
 times a year. 
 
 I shall not dwell upon the different explanations that have been 
 given of this phenomenon. Some have ascribed it to the oblique posi- 
 tion of the uterus, without considering, that upon their principle men- 
 struation should take place from the soles of the feet. Richard Mead 
 believed that it depended on the influence of the moon over the female 
 system ; but why is it not then subjected to the lunar phases ? Those 
 who have found the cause of it in plethora, general or local, have, if 
 we admit their explanation, only changed~the difficulty; for then, we 
 must ask, what are the causes of this plethora? But if this opinion 
 had any ground, nervous women, with a small quantity of blood in their 
 system, ought not to menstruate; and yet they do so, plentifully. 
 Must we ascribe menstruation to an acquired habit ? 
 
 Is the problem resolved, by saying that all the secretory organs of 
 women are too weak to evacuate the superfluity of humours, which 
 would require for them a new emunctory ? But is not this taking the 
 effect for the cause ? Does not this smaller quantity of fluids proceed- 
 ing from the blood, arise from the purification which the blood under- 
 goes in the uterus? Let it be remarked, in the meantime, that this 
 periodical discharge seems to exempt the sex from many inconveniences 
 from which ours suffers, such as gout, stone, and gravel, so unfrequent 
 with them, and so common with us. Norman we avoid recognising in 
 this discharge a utility relative to conception : does it not seem to 
 dispose the uterus to that function ?* (CCIV.) Was it not requisite 
 
 * The greater part of female quadrupeds have the parts of generation bathed 
 in a reddish lymph during the time of heing in heat.
 
 
 OF THE TEMPERAMENTS. SOI 
 
 that this organ should be accustomed to receive a great quantity of 
 blood, that pregnancy, which calls for this afflux, might not be injured, 
 by bringing on a sudden change in the system and the whole of the 
 vital functions ? 
 
 Menstruation is suspended during pregnancy ; it is so during the 
 first month of suckling ; though this rule admits of many exceptions. 
 Its cessation, in our climate, is from the fortieth to the fiftieth year; 
 sometimes before, seldom later; though I have now before me the 
 instance of a woman of seventy who has not yet ceased to menstruate; 
 a fact which, after all, is nothing more surprising than that of men- 
 struation beginning at an early period of life. When menstruation 
 ceases, the breasts collapse, plumpness goes off, and the skin shrivels 
 and loses its softness, colour, and suppleness. This cessation is the 
 cause of a great many diseases which break out at this season of life, 
 called the turn of life, and are fatal to many women; but then, it is 
 observed, that when this period is past, their life is more secure, with 
 greater hope of prolonging it, than a man has at the same age. 
 
 CCXXX. Of manhood. To youth succeeds manhood, which may 
 be considered as beginning from the twenty-first to the twenty-fifth 
 year. Then all increase of the body in height is at an end. The pro- 
 cesses are completely united to the body of the bones, but still growth 
 goes on in other dimensions. All the organs acquire remarkable hard- 
 ness, solidity, and consistency. It is the same with the intellectual 
 and moral faculties. To the empire of imagination succeeds that of 
 judgment. Man is capable of fulfilling all the duties of family and 
 society. This period of life, to which we give the name of mature 
 age, extends to the fiftieth or fifty-fifth year for men : it scarcely goes 
 beyond the forty-fifth for women, with whom it begins also a little 
 sooner. During this long interval, men enjoy the whole plenitude of 
 their existence. 
 
 Although in general it is not difficult to distinguish at first sight a 
 man of twenty-five from one of fifty, the differences which mark them, 
 depending on the quantity and colour of their hair, and on their mus- 
 cular strength, are neither many nor very essential. 
 
 Let us avail ourselves of this age, during which the characters of 
 the human species, merely sketched in childhood and youth, take a 
 more defined and lasting form, to trace the features of individuals and 
 of races. 
 
 CCXXXI. Of temperaments and idiosyncrasies. We give the 
 name of temperaments .to certain physical and moral differences in 
 men, which depend on the various proportions and relations among
 
 502 OF THE TEMPERAMENTS. 
 
 the parts that make up their organisation, as well as upon different 
 degrees in the relative energy of certain organs. There is, besides, in 
 each individual, a mode of existence/ which distinguishes his tempera- 
 ment from that of any other, to whom, however, he may bear great 
 resemblance. We express by the term idiosyncrasy these individual 
 temperaments, the knowledge of which is of no small importance in 
 the practice of medicine. 
 
 The predominance of any particular system of organs modifies the 
 whole economy, impresses striking differences on the results or the 
 organisation, and has no less influence on the moral and intellectual, 
 than on the physical faculties. This predominance establishes the 
 temperament ; it is the cause, and constitutes its essence. 
 
 CCXXXII." Of the sanguine temperament. If the heart, and 
 the vessels which carry the blood through every part, are of predomi- 
 nant activity, the pulse will be sharp, frequent, regular, the com- 
 plexion ruddy, the countenance animated, the shape good, the form 
 softened though distinct, the flesh of tolerable consistence and mode- 
 rate plumpness, the hair fair and inclining to chestnut ; the nervous 
 susceptibility will be lively, and attended with rapid successibility , 
 that is to say, that being easily affected by the impressions of outward 
 objects, men of this temperament will pass rapidly from one idea to 
 another ; conception will be quick, memory prompt, the imagination 
 lively ; they will be addicted to the pleasures of the table and of love, 
 will enjoy a health seldom interrupted by disease, and all their dis- 
 eases, and these slight, modified by the temperament, will have their 
 seat principally in the circulatory system, (inflammatory fever or 
 Angeiotenique, phlegmasia, acute haemorrhage}, and will terminate, 
 when moderate, by the mere force of nature, and require the use of 
 the remedies called antiphlogistic, among which bleeding is the chief. 
 The ancients applied the name of sanguine to this disposition of body ; 
 they considered it as produced by the combination of warmth and 
 moisture, and had very correctly perceived that it existed in the young 
 of both sexes, was heightened by the spring, the season which has been 
 justly compared to youth, calling that age the spring-time of life. 
 
 That the specific characters of the temperament I have just de- 
 scribed may shew themselves in all their truth, it is requisite that the 
 moderated developement of the lymphatic system coincide with the 
 energy of the sanguineous system, so that these two sets of vascular 
 organs may be in true equipoise. The physical traits of this tempe- 
 rament are to be found in the statues of Antinous and the Apollo of 
 Belvidere. Its moral physiognomy is drawn in the lives of Mark 
 .Antony and Alcibiades. In Bacchus are found both the forms and 
 the character. But why seek amongst the illustrious men of antiquity,
 
 OF THE TEMPERAMENTS. 503 
 
 or among its gods, the model of the temperament I have been de- 
 scribing, whilst it is so easy to find it among the moderns ? No one, 
 in my opinion, exhibits a more perfect type of it than the Marshal 
 Duke of Richelieu, that man so amiable, fortunate, brave in war, light 
 and inconstant, to the end of his long and brilliant career.* 
 
 Inconstancy and levity are, in fact, the chief attribute of men of 
 this temperament : excessive variety appears to be to them a necessity 
 as much as an enjoyment : good, generous, feeling, quick, impassioned, 
 delicate in love, but fickle, disgust in them follows close upon en- 
 joyment ; meditating desertion in the midst of the most intoxicating 
 caresses, they make their escape from beauty at the very moment she 
 thought to have bound them by indissoluble chains. f In vain he 
 whom nature has endowed with a sanguine temperament will think to 
 renounce the pleasures of the senses, to take fixed and lasting likings, 
 to attain by profound meditation to the most abstract truths; mas- 
 tered by his physical dispositions, he will be for ever driven back to 
 the pleasures from which he flies, to the inconstancy which is his lot ; 
 more fitted to the brilliant productions of wit, than the sublime con- 
 ceptions of genius. J His blood, which a vast lung impregnates 
 plentifully with atmospherical oxygen, flows freely in very dilatable 
 canals ; and this facility in the distribution and course of the humour 
 is at once the cause and the image of the happy dispositions of his 
 mind. 
 
 If men of this temperament apply themselves, from circumstances, 
 to labours which greatly exert the organs of motion, the muscles, 
 plentifully supplied with nourishment, and disposed to acquire a de- 
 velopement proportioned to that of the sanguineous system, increase 
 
 * See his Memoirs, 6 vols. 8vo. 
 
 Voltaire has painted his character with superior ability in many verses addressed 
 to him : 
 
 Rival du conqurant de 1'Inde, 
 Tu bois, tn plais, tu combats, &c. 
 
 f The history of Henry IV., of Louis XIV., of Regnard, and of Mirabeau, proves 
 that, to the extreme love of pleasure, sanguine men join, when circumstances require 
 it, great elevation of thought and character ; and can bring into action the highest 
 talents in every department. 
 
 I have just met with an assertion in a gazette which is at least singular. All the 
 world knows, says the journalist, that Newton was sanguine ; and this proves clearly, 
 he adds, that temperaments have no influence on the intellectual powers. I would 
 ask the journalist where he has discovered that Newton was sanguine ? The few 
 details which biographers have preserved on the physical temperament of this 
 illustrious philosopher, lead us to believe that his temperament was the melancholic, 
 which is very frequently met with in England. I will not dare to pronounce 
 absolutely on subjects on which we can attain only a certain degree of probabilitv ; 
 but if Newton had been sanguine, he would not have carried his maidenhead with 
 him to the grave, at the age of fourscore, as it is affirmed he did.
 
 *04 OK THE TEMPERAMENTS. 
 
 in bulk, the sanguineous temperament undergoes a great modification, 
 and there results from it the muscular or athletic temperament, con- 
 spicuous by all the outward signs of vigour and strength. The head 
 is very small, the neck sunk, especially backward, the shoulders broad, 
 the chest large, the haunches solid, the intervals of the muscles deeply 
 marked. 
 
 The hands, the feet, the knees, all the articulations not covered by 
 muscles, seem very small ; the tendons are marked through the skin 
 which covers them ; the susceptibility is not great : feeling dull and 
 difficult to rouse, the athletic surmounts all resistance when he has 
 once broken from his habitual tranquillity. The Farnese Hercules 
 exhibits the model of the physical attributes of this particular consti- 
 tution of body ; and what fabulous antiquity relates of the exploits of 
 this demi-god, gives us the idea of the moral dispositions that accom- 
 pany it. In the history of his twelve labours, without calculation, 
 without reflection, and as by instinct, we see him courageous because 
 he is strong, seeking obstacles to conquer them, certain of overwhelming 
 whatever resists him; but joining to such strength so little subtlety, 
 that he is cheated by all the kings he serves, and all the women he 
 loves. It would be difficult to find in history the example of a man 
 who has combined with the physical powers which this temperament 
 implies, distinguished strength of the intellectual faculties. For ex- 
 celling in the fine arts and in the sciences, there is need of exquisite 
 sensibility, a condition absolutely at variance with much developernent 
 of the muscular masses. 
 
 CCXXXIII. Of the bilious temperament. If sensibility, which 
 is vivid and easily excited, can dwell long upon one object ; if the 
 pulse is strong, herd, and frequent, the sub-cutaneous veins prominent, 
 the skin of a brown, inclining towards yellow, the hair black, moderate 
 fulness of flesh, but firm, the muscles marked, the form harshly ex- 
 pressed the passions will be violent, the movements of the soul often 
 abrupt and impetuous, the character firm and inflexible. Bold in the 
 conception of a project, constant and indefatigable in its execution, it 
 is among men of this temperament we find those who, in different 
 ages, have governed the destinies of the world : full of courage, bold- 
 ness, and activity, all have signalised themselves by great virtues or 
 great crimes, and have been the terror or admiration of the universe. 
 Such were Alexander and Julius Ceesar, Brutus, Mahomet, Charles 
 XII., the C/ar Peter, Cromwell, Sixtus V., Cardinal Richelieu. 
 
 As love is in the sanguine, so ambition is in the bilious the governing 
 passion. Observe a man, who, born of an obscure family, long vege- 
 tates in the lower ranks. Great shocks agitate and overthrow empires : 
 at first a secondary actor in those great revolutions which are to change 
 his destiny, the ambitious man hides his designs from all, and by degrees
 
 OF THE TEMPERAMENTS. 505 
 
 raises himself to the sovereign power, employing, to preserve it, the 
 same address with which he possessed himself of it. This is, in few 
 words, the history of Cromwell, and of all usurpers.* 
 
 To attain to results of such importance, the profoundest dissimu- 
 lation and the most obstinate constancy are equally necessary ; these 
 are, further, the most eminent qualities of the bilious. No one ever 
 combined them in higher perfection than that famous pope who, 
 slowly travelling on towards the pontificate, went for twenty years 
 stooping and talking for ever of his approaching death, and who, at 
 once, proudly rearing himself, cries out, " I am pope !f" petrifying with 
 astonishment and mortification those whom his artifice had deceived 
 into his party. 
 
 Such, too, was Cardinal Richelieu, who raised himself to a rank so 
 near to the highest, and was able to maintain himself in it : feared by 
 a king whose authority he established hated by the great, whose power 
 he destroyed, haughty and implacable towards his enemies, ambitious 
 of every sort of glory, &c.J 
 
 The historians of the time inform us, that this celebrated minister 
 shewed all the customary signs of the bilious temperament. Gour- 
 ville tells us, that he was all his life subject to a very troublesome 
 hsemorrhoidal discharge. || 
 
 This temperament is further characterised by the premature de- 
 velopement of the moral faculties. Scarcely past their youth, the 
 men I have named projected and carried into execution enterprises 
 which would have been sufficient for their fame. An excessive de- 
 velopement of the liver, a remarkable superabundance of the biliary 
 juices, most commonly accompanying this constitution of body, in 
 which the vascular and sanguineous system enjoys the greatest energy, 
 to the prejudice of the cellular and lymphatic system, the ancients 
 gave the name of bilious. The diseases to which those distinguished 
 by it are subject, involve, in fact, either as their principal character- 
 istic, as accessory circumstances, or as complication, the derange- 
 ment of the action of the hepatic organs, joined to changes of com- 
 position in the bile. Among the remedies directed against this sort of 
 diseases, evacuants, and especially emetics, are the best. 
 
 If all the characteristics assigned to the bilious temperament are 
 carried to the highest degree of intensity, and to this state is added 
 great susceptibility, men are irascible, impetuous, violent on the 
 
 * Vie (TOlivier Cromwell, par Jeudy Dugour, 2 vol. 18mo. 
 f Vie de Sia-te Quint, 2 vol. in 12mo. 
 
 $ See his character, drawn with as much truth as eloquence, by Thomas, iu the 
 last edition of his Essui sur les Eloges. 
 || Mcmoires de Gourville.
 
 506 OF THE TEMPERAMENTS. 
 
 slightest occasions. Such Homer describes Achilles and some others 
 of his heroes. 
 
 CCXXXI V. Of the melancholic temperament. When to the bilious 
 temperament is added diseased obstruction of any one of the organs of 
 the abdomen, or derangement of the functions of the nervous system, 
 so that the vital functions are feebly or irregularly performed, the skin 
 takes a deeper hue, the look becomes uneasy and gloomy, the bowels 
 sluggish, all the excretions difficult, the pulse hard and habitually 
 contracted. The general uneasiness affects the mind ; the imagination 
 becomes gloomy, the disposition suspicious. The exceedingly multi- 
 plied varieties of this temperament, called by the ancients the melan- 
 cholic ; the diversity of accidents that may bring it on, such as hereditary 
 disease, long grief, excessive study, the abuse of pleasures, &c. justify 
 the opinion which Clerc has proposed in his natural history of man in 
 a state of disease, where he considers the melancholic temperament 
 less as a primitive and natural constitution, than as a diseased affection 
 hereditary or acquired. The characters of Lewis XI. and Tiberius 
 leave nothing wanting for the moral determination of this tempera- 
 ment. Read, in the Memoirs of Philip de Commines, and in the 
 Annals of Tacitus, the history of these two tyrants, fearful, perfidious, 
 mistrustful, suspicious, seeking solitude by instinct, and polluting it 
 by all the acts of the most savage atrocity and the most ungoverned 
 debauch. Distrust and fearfulness, joined to all the disorders of 
 imagination, compose the moral character of this temperament. The 
 passage in which Tacitus paints the artful conduct of Tiberius, when 
 he refuses the empire offered him after the death of Augustus, may be 
 given as the most perfect model of it.* 
 
 As Professor Pinel very justly observes, in his treatise on insanity, 
 the history of men celebrated in the sciences, letters, and arts, has 
 shewn us the melancholic under a different light: endowed with ex- 
 quisite feeling and the finest perception, devoured with an ardent 
 enthusiasm for the beautiful, capable of realising it in rich conceptions, 
 living with men in a state of reserve bordering upon distrust, analysing 
 with care all their actions, catching in sentiment its most delicate 
 shades, but ready in unfavourable interpretations, and seeing all things 
 through the dingy glass of melancholy. 
 
 It is extremely difficult to delineate this temperament in a general 
 or abstract manner. Though the ground-work of the picture remains 
 always the same, its numerous circumstances give room for an infinite 
 number of variations. It is better, therefore, to have recourse to the 
 lives of illustrious men who have exhibited it in all its force. Tasso, 
 Pascal, J. J. Rousseau, Gilbert, Zimmerman, are remarkable, among 
 
 * Versa inde ad Tibcrium prcces, <e CORN. TACIT. Annal. lib. i.
 
 OF THE TEMPERAMENTS. 507 
 
 many others, and deserve, by their just celebrity, to fix our consi- 
 deration. The first, born in the genial climate of Italy proscribed 
 and unhappy from his childhood author, at twenty-two years old, of 
 the finest epic poem the moderns can boast of was seized, in the midst 
 of the enjoyments of premature glory, with the most violent and most 
 inauspicious love for the sister of the Duke of Ferrara, at whose court 
 he lived an extravagant passion, which was the pretext for the most 
 cruel persecutions, and which followed him to his death : this took 
 place towards the thirty-second year of his age, on the eve of a tri- 
 umphal pomp which was prepared for him in the capitol. 
 
 The author of the Provincial Letters and of the Thoughts, enjoy- 
 ing, like Tasso, a premature celebrity almost on quitting childhood, 
 was led to melancholy, not, like him, by the crosses of unhappy love, 
 but by a violent and overpowering terror, which left in his imagina- 
 tion the sight of a gulf for ever open at his side an illusion which 
 left him only at his death, eight years after the accident.* 
 
 No one, perhaps, has ever shewn the melancholic temperament in 
 a higher degree of energy than the philosopher of Geneva. To be con- 
 vinced of it, it is enough to read with attention certain passages of his 
 immortal works, and especially the two last parts of his Confessions, 
 and the Reveries in the Solitary Walker : tormented with continual 
 distrusts and fears, his fruitful imagination represented to him all men as 
 enemies. If you believe him, the whole human race is in league to 
 do him mischief " kings and nations have conspired together against 
 the son of a poor watchmaker ;" children and invalids are brought in 
 to execute these dreadful plots. But let us leave him to speak for 
 himself, the most eloquent and the most unfortunate man of the 
 eighteenth century. " Here then I am, alone upon the earth, without 
 brother, neighbour, friend, without society but myself : the most so- 
 ciable and the most loving of men has been proscribed by them with 
 unanimous consent." This is the beginning of the first walk ; further 
 on he adds, " Could I believe that I should be held, without the 
 smallest doubt, for a monster, a poisoner, an assassin ; that I should 
 become the horror of the human race, and the game of the rabble ; 
 that all the salutation of those that passed by me would be to spit 
 upon me; that a whole generation would amuse itself, with unani- 
 mous consent, in burying me alive ?" It is idle to multiply quota- 
 tions in speaking of the works of a philosopher who, in spite of his 
 errors, will for ever be the delight of all those who love to read and to 
 think. 
 
 The history of J. J. Rousseau, like that of all the melancholies who 
 have distinguished themselves in literature, shews us genius struggling 
 
 * He died at 39. See his life by Condorcet.
 
 508 OF THE TEMPERAMENTS. 
 
 with misfortune ; a strong soul lodged in a feeble body ; at first gentle, 
 affectionate, open, and tender, but soured by the sense of an unhappy 
 condition, and of the injustice of men. Till the time when, impelled by 
 the desire of fame, Rousseau sprang" forward in the career of letters, 
 we see him endowed with a sanguine temperament, acting with all the 
 qualities belonging to it : gentle, loving, generous, feeling, though in- 
 constant, his fertile imagination shews him nothing but gay images, 
 and in this illusion of happiness he lives on agreeable chimeras; but 
 gradually undeceived by the hard lessons of experience afflicted, in 
 the depth of his heart, with his own wretchedness and the wrongs of 
 his fellow-creatures, his bodily vigour wastes and decays, with it his 
 moral nature changes, and he may be referred to as the most striking 
 proof of the reciprocal influence of the moral on the physical, and the 
 physical on the moral part of our being.* His history is a proof, 
 beyond reply, that the melancholic temperament is less a peculiar con- 
 stitution of the body than a real disease, of which the degrees may in- 
 finitely vary, from a mere originality of character to the most decided 
 mania. 
 
 Gilbert arrived at Paris with the germs of talents fitted for that 
 great theatre. Poor, and rebuffed by those on whom he had built his 
 hopes, he mixed in the ranks of their detractors, and soon signalised 
 himself among the most formidable, by a vigour worthy of a better 
 cause. Persecuted without respite by want, the mortifying sight 
 of the happiness which his enemies enjoyed, and to which he believed 
 himself called, Jed him on to a state of perfect madness. He believed 
 himself persecuted by the philosophers, who wanted to rob him of his 
 papers : to save them from the imagined rapacity, he locked his manu- 
 
 * I have no doubt that the influence of the physical organisation on the intel- 
 lectual faculties is so decided, that we may regard as possible the solution of the 
 following problem, analogous to that with which Condillac concludes his work on 
 the origin of human knowledge : 
 
 The physical man being given, to determine the character and extent of his 
 capacity, and to assign, consequently, not only the talents he possesses, but those he 
 is capable of acquiring. 
 
 The profound meditation of the work of Galen (quod animi mores corporis tem- 
 peramenta sequantur) ; the perusal of Plutarch's Lives of Illustrious Men, and of 
 the other biographers and historians of ancient and modern times ; of the Eulogies 
 of Fontenelle, Thomas, d'Alembert, Condorcet, Vicq-d'Ayzr, &c. ; and the study of 
 the medico-philosophical works of Haller, Cullen, Cabanis, Pinel, Halle, who have 
 modified and enriched the ancient doctrine of temperaments, will be of great avail in 
 the search after this solution. " Philosophy," cries an eloquent writer, in the noble 
 enthusiasm which seizes him at the sight of the riches accumulated by Fontana, in 
 the Anatomical Museum in Florence, " Philosophy has been in the wrong, not to 
 descend more deeply into physical man ; there it is that the moral man lies con- 
 cealed ; the outward man is only the shell of the man within." DUPATY, Thirty- 
 third Letter on Italy.
 
 OF THE TEMPERAMENTS. 509 
 
 scripts in a press, and swallowed the key. It stuck at the entrance of 
 the larynx, stopped the passage of the air, and suffocated the patient, 
 who died at the Hotel-Dieu, after three days of the most cruel suf- 
 fering.* 
 
 Zimmerman, early exhausted by study, already a physician of 
 celebrity at an early age, lived in solitude, with an ardent imagination 
 joined to the highest susceptibility : abandoned to himself, devoured 
 with the thirst of glory, he gave himself up to labour in excess, pub- 
 lished his treatise on Experience, and the work on Solitude, so deeply 
 imbued with the colouring of his soul. Forced from the solitude he 
 loved, he carried into the courts to which his reputation called him 
 an inexhaustible store of bitterness and sadness, which, political events 
 supervening, brought to greater excess : arrived, at length, gradually 
 at the last term of hypochondria, he died beset with pusillanimous 
 fears, worthy of all eulogium and all regret.f 
 
 CCXXXV. Of the pituitous or lymphatic temperament. If the 
 proportion of the fluids to the solids is too great, this superabundance 
 of the humours, which is constantly in favour of the lymphatic system, 
 gives to the whole body considerable bulk, determined by the develope- 
 ment and repletion of the cellular tissue. The flesh is soft, the coun- 
 tenance pale, the hair fair, the pulse weak, slow, and soft, the forms 
 rounded and without expression, all the vital actions more or less lan- 
 guid, the memory treacherous, the attention not continuous. Men of 
 this temperament, to which the ancients gave the name of pituitous, 
 and which we should call lymphatic, because it depends really on the 
 excessive developement of this system, have, in general, an insurmount- 
 able inclination to sloth, averse alike to labours of the mind and body : 
 accordingly, we are not to wonder if we find none of them among Plu- 
 tarch's illustrious men. Little fitted for business, they have never 
 
 * His life would have been preserved if the cause of his illness had been un- 
 derstood, which he indicated himself by repeating for ever, " the key chokes me." 
 His state of madness made this pass for the words of a madman ; but on opening 
 the body, the key was found, of which the ward part was fixed at the entrance of 
 the larynx : it would have been easy to draw it out, by putting a finger down the 
 throat. 
 
 This unfortunate young man expressed, a few days before his death, the melan- 
 choly state of his soul, in stanzas most touchingly mournful : this is one, full of 
 interest and simplicity : 
 
 Au banquet de la vie infortune convive, 
 
 Je parus un jour, et je meurs ; 
 Je meurs, et sur ma tombe, ou lentement j 'arrive, 
 
 Nul ne viendra verser des pleurs. 
 
 f See his Eulogium, by Tissot ; it is at the beginning of the last edition of the 
 Treatise on Experience in Medicine. It there appears how deeply he was affected 
 by the French revolution, of which he foresaw, with a sort of prophetic spirit, the 
 disastrous consequences to his own country.
 
 510 OF THE TEMPERAMENTS. 
 
 exercised great empire over their fellow-creatures; they have never 
 changed the face of the globe by their negotiations or tb; ir conquests. 
 One of the friends of Cicero, Pompqnius Atticus, whose history Cor- 
 nelius Nepos has left us, conciliating to himself all the factions which 
 tore the Roman republic to pieces in the civil wars of Caesar and Pom- 
 pey, may be given as the model of it. Among the moderns, the easy 
 Michel Montaigne, all of whose passions were so moderate, who reasoned 
 on every thing, even on feeling, was truly pituitous. But in him the 
 predominance of the lymphatic system was not carried so far but that 
 he joined to it a good deal of nervous susceptibility. In the pituitous, 
 from the excess of watery particles in the fluid which should carry 
 every where heat and life, the circulation goes on slowly, the imagina- 
 tion is weak, the passions languid ; and from this moderation of the 
 desires spring, on many occasions, those virtues of temperament, 
 which, to say it by-the-by, should not supply their possessors with 
 matter of quite so much self-complacency. 
 
 CCXXXVI. Of the nervous temperament. This property, by 
 which we are more or less sensible to impressions on our organs, weak 
 in the pituitous, almost nothing in athletes, moderate in those of san- 
 guine temperament, rather quick in the bilious, constitutes by its 
 excess the nervous temperament ; it is seldom natural or primitive, 
 but commonly acquired, and depending on a sedentary and too inactive 
 life, on habitual indulgence in sensuality, on the morbid action of the 
 brain, promoted by reading works of imagination, &c. This tempera- 
 ment shews itself in the emaciation, in the smallness of the muscles (which 
 are soft and, as it were, in an atrophy), in the vivacity of the sensations, 
 in the suddenness and mutability of the determinations and judgments. 
 Nervous women, whose wills are absolute but changeable, with excess 
 of sensibility, frequently exhibit it with all these characteristics. 
 Often, however, they have- something of good looks, the extreme pre- 
 ponderance of the nervous system still allowing a moderate develope- 
 ment of the lymphatic. Spasmodic affections are not uncommon 
 amongst them ; and when it is observed that, on the other hand, the 
 athletic constitution, directly opposite to the nervous temperament, 
 predisposes to tetanus, may we not say, that the two extremes meet, or 
 produce the same effects ? 
 
 Anti-spasmodics are employed with success in the treatment of 
 their diseases, which partake always, more or less, of the temperament. 
 Stimulants, on the contrary, are very suitable to those of a pituitous 
 or lymphatic temperament. The nervous temperament, like the me- 
 lancholic, is not so much a natural constitution of the body as the 
 first stage of a disease. This temperament, like the nervous affections 
 which are the result of it, has never shewn itself but among societies 
 brought to that state of civilisation in which man is the farthest possible
 
 OF THE TEMPERAMENTS. 511 
 
 from nature. The Roman ladies became subject to nervous affections 
 only in consequence of those depraved manners which, marked the 
 decline of the empire. These affections were extremely common in 
 France during the eighteenth century, and in the times preceding the 
 fall of the monarchy. Of that epoch are the works of Wytt, Raulin, 
 Lorry, Pomme, &c. on nervous affections. Tronchin, a Genevese 
 physician, acquired great wealth and reputation by the treatment 
 of these diseases. His whole secret consisted in exercising to fatigue 
 women habitually inactive, keeping up their strength at the same time 
 by simple, healthy, and plentiful food. The two most remarkable men 
 of the eighteenth century, Voltaire and the great Frederick, may be 
 given as instances of the nervous temperament ; and the history of 
 their brilliant and agitated life shews sufficiently how much the cir- 
 cumstances in which they lived contributed to develope their native 
 dispositions. 
 
 I shall finish this article on temperaments by observing, that in 
 truth we bring with us into the world these particular dispositions of 
 body ; but that from education, manner of life, climate, acquired 
 habits, they are altered or altogether changed. Further, it is exceed- 
 ingly rare to find individuals who shew in their purity the characteristics 
 assigned to the different temperaments : the descriptions given are 
 drawn from an assemblage of individuals much resembling one another. 
 Their characters are pure abstractions, which it is difficult to realise, 
 because all men are at once sanguine and bilious, sanguine and lym- 
 phatic, &c. In this instance, physiologists have imitated the artist, 
 who united in the image of the goddess of beauty a thousand perfec- 
 tions, which he saw separate in the most beautiful women of Greece.* 
 
 It is an observation, that the sanguine constitution is directly op- 
 posed to the melancholic, and never combines with it ; that it is the 
 same with the bilious and lymphatic : though it may happen that a 
 man, sanguine in youth, shall become melancholic after a lapse of 
 time ; for, as I have said before, man never remains such as he came 
 from the hands of Nature : fashioned by all that surrounds him, his 
 physical qualities, at different periods of his life, are as much changed 
 as his character. 
 
 Of all the causes that can modify the constitution of man, and which 
 will even change completely the nature of his original dispositions, there 
 is none more powerful than the long-continued action of air, water, 
 and residence, as the father of medicine has said. Climate, in fact, 
 exerts upon the temperament the most marked influence. Thus, the 
 
 * It is thus that, in the arts of imitation, the ideal grows up now from the 
 exaggeration of features, now from the union of qualities which nature has produced 
 separate.
 
 512 OF THK TEMPERAMENTS. 
 
 bilious temperament is that of the greater part of the inhabitants of 
 southern countries; the sanguine that of the nations of the north ; the 
 lymphatic constitution reigns, on .the contrary, in cold and moist 
 countries like Holland. We have seen in what manner the athletic, 
 melancholic, and nervous temperament grows out of our habits of life ; 
 let us now endeavour to appreciate the power of climate over the con- 
 stitution of the greater part of mankind. 
 
 It is known that the influence of heat in the production of bilious 
 diseases is such, that after having been extremely prevalent during 
 the summer, they disappear, or at least become much less frequent, 
 in the autumn. A notable increase of perspiration never takes place 
 without a proportional diminution in the quantity of the secretions with 
 which the alimentary mucous surfaces are moistened. Now, when the 
 gastric and intestinal juices are less abundant, the bile, being mixed 
 with a smaller quantity of these fluids, irritates more the intestinal 
 surfaces ; the digestive powers languish, and there is an approaching 
 disposition to meningo-gastric fevers. The same influences, continued 
 during the whole year in hot countries, must necessarily increase, 
 with the activity of the biliary system, its power over the other parts 
 of the economy ; and thus establish a predominance of the bilious con- 
 stitution through both health and disease. 
 
 As for the sanguine temperament, so generally met with among 
 northern nations, it is the necessary consequence of the continual and 
 very energetic re-action of the powers of circulation, against the effects 
 of external cold. It is only by the constant activity of the heart and 
 vessels that calorification can be effected with the necessary vigour. 
 Now, the effects of this redoubled action are the same to the organs of 
 circulation as to the muscles under the influence of volition ; in both, 
 exertion increases the power of the organs exerted. The diseases of 
 the nations of the north, analogous to their temperament, have, for the 
 most part, their seat in the system of sanguineous vessels : their cha- 
 racter is eminently inflammatory. 
 
 Lastly, the lymphatic state of nations living under a moist climate 
 is nothing more surprising than the aqueous nature of plants, and 
 small density of the wood in trees growing under the influence of a 
 foggy air. Animal bodies, like plants, absorb by their surfaces, and 
 become gorged with humours, the excess of which always produces a 
 remarkable slackening of activity in the organic motions. 
 
 The temperament of which the character is the predominance of 
 one organ or system of organs, departs from that ideal state where all 
 the powers are reciprocally balanced, so as to exhibit in the living 
 economy a perfect equilibrium. This latter state, which has, perhaps, 
 never been found but in the imaginations of physiologists, and which 
 was called by the ancients the temperate temperament, (tempcramentwn
 
 
 i 
 
 VARIETIES OF THE HUMAN SPECIES. 513 
 
 temperatum) being taken as the type of health, it follows that this 
 temperament is already a step -made towards disease. Yet the action 
 of the predominant system is not in such excess as to destroy all 
 equilibrium, and impede the action of life : but let the constitutional 
 dispositions be much increased, the disease is begun; and this tran- 
 sition takes place in the conversion of the lymphatic temperament into 
 scrofula.* In the scrofulous constitution there is at once ac- 
 tivity of the absorbing mouths, great facility of absorption, inertness of 
 the vessels and lymphatic glands, weakness of the absorbents, and 
 consequently a thickening and stagnation of the liquids absorbed. The 
 same thing is seen in the lymphatic temperament, characterised by the 
 activity of the inhaling mouths, and the debility of the lymphatic system, 
 as Professor Cabanis was aware, f when he refuted the opinion of those 
 who ascribe the lymphatic temperament to the excess of activity in 
 the absorbent system, though the only part of this system really 
 quickened is that which immediately performs absorption, whilst the 
 rest is in a state of perfect atony. 
 
 .. CCXXXVII. Varieties of the human species. The power of pro- 
 ducing, by copulation, individuals which are alike, is considered by 
 naturalists as the most certain test for fixing the species in red and 
 warm-blooded animals. This power of self-perpetuation, by a constant 
 succession of similar beings, is found in all the races composing the 
 human species, however different in colour, structure, and manner of 
 life. Men, then, are but one species; and the difference that appears 
 in them, according to the region of the globe they inhabit, can only 
 constitute varieties or races. I admit, with M. Lacepede, the worthy 
 continuator of Buffon, four principal races of the human species, which 
 I shall call, like him, the European Arab, the Mofyul, the Negro, and 
 the Hyperborean. We might add a fifth, the American, were it not 
 most probable that the new continent is peopled by inhabitants, who, 
 coming from the old, either by land in the austral hemisphere, or along 
 the immense archipelago of the Pacific Ocean, have been altered by 
 the influence of that climate, and the yet virgin soil, so that they are 
 to be regarded less as a distinct race than a simple variety. I 
 
 There is, in truth, this difference between varieties and races, that 
 in these last there are implied modifications more profound, more 
 
 * See Nosographie Chirurgicale, tome i. for the history of scrofulous ulcers, 
 from which this paragraph is taken entire. The author in that work has aimed at 
 introducing physiology into surgery, till then exclusively abandoned to explanations 
 of the grossest mechanism. 
 
 ( Of the Relations of the Physical and Moral Man, by G. Cabanis, Senator, 
 Professor in the School of Medicine in Paris, &c. 
 
 $ See APPENDIX, Notes P P. 
 
 L L
 
 514 VARIETIES OF THE HUMAN SPECIES. 
 
 essential differences, changes not confined to the surface, but extend- 
 ing to the very structure of the body; whereas to make a variety, no- 
 hing more is needed than the superficial influence of climate on the 
 integuments, which it colours, and on the hairs, which it makes longer or 
 shorter, lank or curled, hard or soft. An Abyssinian, scorched by the 
 heat of an almost tropical sky, is as black as the negro under the 
 equator; yet they are by no means of one race, since the Abyssinian, 
 a negro only in colour, resembles the European in the cast of his face, 
 and the proportions of all his parts. 
 
 The characteristics of the European Arab race, which takes in the 
 inhabitants, not of Europe only, but of Egypt also, Arabia, Syria, 
 Barbary, and Ethiopia, are an oval or almost oval face, in the vertical 
 direction, a long nose, a prominent skull, long and commonly lank 
 hair, a skin more or less white. These fundamental characteristics are 
 no where more decided than in the north of Europe. The inhabitants 
 of Sweden, Finland, and Poland, give the prototype of the race : 
 their stature is tall, their skin of perfect whiteness, their hair long, 
 lank, and of a light colour ; the iris generally bluish. The Rus- 
 sians, the English, the Danes, the Germans, are already removed 
 somewhat from* this primordial type : the colour of their skin is of 
 less pure white, their hair of a deeper hue. The French seem to stand 
 midway betwixt the nations of the north and those of the south of 
 Europe. Their skin is shaded with a deeper dye, their hair less 
 straight, and more of a chestnut and brown colour. The Spaniards, 
 the Italians, the Greeks, the European Turks, and the Portuguese, are 
 browner, their hair in general black. Lastly, the Arabs, the Moor?, 
 and the Abyssinians, have hair in some measure black and crisp, the 
 skin tawny ; and might serve for the step from the European Arab to 
 the Negro race, which is, however, distinguished from them by the 
 flatness of the forehead, the smallness of the skull, the slope of the 
 line measuring the height of the face, the thickness of the lips, the 
 projection of the malar bones; and further, by a darker skin, thicker, 
 greasy, and, as it were, oily, as well as by shorter, finer, curly, and 
 woolly hair. 
 
 The Mongol race has the forehead flat, the skull jutting but little, 
 the eyes looking rather obliquely outwards ; the cheeks are prominent, 
 and the oval of the face, instead of extending from the forehead to the 
 chin, is drawn between the two malar bones. The Chinese, the Tartars, 
 the inhabitants of the Peninsula, of the Ganges, and of the other 
 countries of India, of Tonquin, Cochin-china, Japan, of the kingdom 
 of Siam, &c. compose this race, which is more numerous than all 
 the others, apparently more ancient, and which is spread over a greater 
 extent of surface than the European Arab race, and yet greater than 
 the Negro race, since it reaches from the fortieth to the sixtieth
 
 VARIETIES OF THE HUMAN SPECIES. 515 
 
 parallel of latitude, occupying an arc of the meridian of nearly 75 ; 
 whilst that which measures the countries of the European race is only 
 of 50, and the Negro race lying under the equator, between the tropics 
 of Cancer and of Capricorn, is bounded within the limits of an arc of 
 from 30 to 35.* 
 
 The Hyperborean race, situated in the north of the two continents, 
 in the neighbourhood of the polar circles, composed of the Laplanders, 
 the Ostiaks, the Samoiedes, and the Greenlanders, is characterised by 
 a flat face, a squat body, and a very short stature. This degraded 
 portion of the human species evidently derives from the climate its 
 distinctive characteristics. Striving for ever with the inclemency of a 
 severe climate, and the destructive action of an icy temperature, Nature, 
 fettered in her motions, and shrunk in her dimensions, can produce 
 only beings whose physical imperfections explain their almost barbarous 
 condition. 
 
 The small progress of the Negroes in the study of the sciences and 
 in civilisation ; their decided taste and singular aptitude for all the arts 
 which require more taste and dexterity than understanding and re- 
 flection, as dancing, music, fencing, &c. ; the figure of the head, which 
 is midway between that of the European and the ourang-outang ; f the 
 existence of the intermaxillary bones at an age when with us the 
 traces of their separation are completely effaced ; the high situation 
 and small developement of the calf of the leg ; have been arguments 
 more specious than solid to those who have endeavoured to abase this 
 portion of the human species, in order to justify an iniquitous traffic 
 and a cruel tyranny reproaches of civilised men, which they must 
 wipe off by other means than a presumptuous assertion of their own 
 dignity, or a proud insult on the native character of those whom they 
 themselves have cast into degradation. 
 
 Without admitting this belief, which owes its origin to a thirst for 
 riches, we cannot help acknowledging that the differences of organisa- 
 tion draw after them a striking inequality in the developement of the 
 
 * Lace"pede, Giographie Zoologique. 
 
 } The black colour of the skin in Negroes seems owing, as I have already said, 
 to the scorching of the gelatine, which is the base of the rete mucosum of Malpighi. 
 This colour, acquired in a long succession of ages, perpetuated and transmitted by 
 generation, is become one of the characteristic features of the Negro race. M. Vol- 
 ney, in a work which should be a model to all travellers, grounds on the face of the 
 blacks a conjecture as ingenious as it is probable. He observes, that it exhibits 
 precisely that state of contraction which our face takes when it is struck by light, 
 and a strong reverberation of heat ; then, says this philosophical traveller, the 
 cheek-bones rise, the brow and the eye-lids contract, and the lips project. Must not 
 this contraction of the movable part have influenced, in course of time, the hard 
 parts, and even moulded the structure of the bones ? Voyage en Syrie et en Egypte, 
 torn. i. p. 70, sixieme edition.
 
 516 VARIETIES OF THE HUMAN SPECIES. 
 
 moral and intellectual faculties. This truth would appear in its full 
 light, if, after summarily indicating, as I have just done, the physical 
 characteristics of the races of men; I could unfold their moral differ- 
 ences as real, and not less marked, by opposing the activity, the ver- 
 satility, the restlessness, of the European, to the indolence, the phlegm, 
 the patience of the Asiatic ; examining what is the power or the cha- 
 racter of nations, the fertility of soil, serenity of sky, mildness of cli- 
 mate ; shewing by what catenation of physical and moral causes the 
 empire of custom is so powerful over the people of the East that we 
 find in India and China the same laws, manners, and religion, which 
 prevailed there long before our era; inquiring by what singularity, 
 well worthy the meditation of philosophers and politicians, these laws, 
 this worship, and these manners, have undergone no change amidst the 
 revolutions which have so often taken place among those nations, many 
 times conquered by the warlike Tartars ; shewing how, by the irre- 
 sistible ascendancy of wisdom and knowledge, ignorant and ferocious 
 conquerors have adopted the usages of the nations they have subju- 
 gated ; and proving that the stationary condition of the sciences and 
 arts among those who, so long before ourselves, were in possession of 
 the advantages of civilised society, is derived not so much from the im- 
 perfection of their organisation, as from the degrading yoke of a 
 religion loaded with absurd practices, and which makes knowledge the 
 exclusive birthright of a privileged cast.* But such an undertaking, 
 besides exceeding the limits I have prescribed myself, does not belong 
 directly to my subject. 
 
 The Albinoes of Africa, the Cdgots of the Pyrenees, and the Cretins 
 of the Valais, cannot be given as varieties of the human species. They 
 are infirm, feeble, degraded beings, incapable of reproducing an exist- 
 tence which has fallen to them in the midst of a healthy, vigorous, 
 and robust population. 
 
 We are not to believe what some travellers have written on the 
 existence of tribes of giants that have appeared on the Magellanic 
 coast. The Patagonians, concerning whose stature there is so little 
 agreement in relations, are men very well formed, and whose height 
 does not exceed ours more than nine or ten inches. The Laplanders, 
 
 * We must assign further, as a main cause of the want of progress of the Indians 
 and Chinese in the arts and sciences sprung from civilisation, the imperfection 
 of their alphabet, which, being composed of a multitude of characters, does not, 
 like ours, represent sounds, hut ideas. It belongs not to our subject to shew how 
 much signs so defective must confine the sphere, and fetter the combinations, of the 
 mind. 
 
 See, concerning the religion of the Brahmins and the Indian customs, Raynal's 
 Philosophical History ; the Asiatic Researches ; Institutes of Menu, Edin. Review, 
 xxxii. ; Ward's View of the History of the Hindoos ; Halked's Code of Gentoo 
 Laws ; Colebrooke's Digest of Hindoo Law.
 
 OLD AGE AND DECAY. 517 
 
 whose stature is the smallest, are as much below as the Patagonians 
 are above ; it does not exceed from four feet to four and a half. In 
 the midst of ourselves, individuals reach, from time to time, a stature 
 sufficient to entitle them to the name of giants ; whilst others, shrunk 
 in all their proportions, are a renewal of the pigmies. Such was Bebe, 
 the dwarf of Stanislaus, king of Poland ; Goliah, spoken of in the book 
 of Kings, (ch. xvii. v. 4.); the king Og, (Deut. ch. iii, v. 2); and 
 many others, whose stature varies from six to ten feet high. 
 
 CCXXXVIII. Of old age and decrepitude. The human body, 
 which, from the twentieth year of life, ceases to grow in height, in- 
 creases in every dimension during the twenty succeeding years. After 
 this period, far from growing, it begins to decay, and loses daily a part 
 of its strength. The decay proceeds at the same rate as the growth, 
 and is not more rapid ; since man requires from thirty to forty years in 
 reaching to his full growth, and takes about the same time in his pro- 
 gress to the grave, provided no accident hurries him to an untimely 
 end. * The whole bulk t>f the body diminishes, f the cellular tissue 
 becomes collapsed, and the skin wrinkled, especially that of the fore- 
 head and face. The hairs of the head and over the rest of the body 
 turn gray, then white ; the organic action becomes languid ; the fluids 
 become more disposed to putrefaction (Hunter) ; hence, at this period 
 of life, all diseases of debility are more frequent, and attended with 
 greater danger. 
 
 Decay succeeds old age. The sensibility of the organs is blunted ; 
 
 * The duration of life may be estimated by that of the growth. A dog ceases 
 to grow at the end of two or three years, and lives only ten or twelve ; man, whoso 
 growth requires a space of from twenty to thirty years, attains to the age of ninety 
 or a hundred. Fishes live several centuries, their developement requiring a con- 
 siderable number of years. 
 
 j- The diminution of the entire bulk of the body of aged persons frequently 
 gives place to an augmentation of size, especially of the trunk of the body. This 
 is entirely owing to the increased deposit of fat, which often supervenes at this age, 
 and which appears to depend on the energy of the system being insufficient to the 
 complete assimilation of the nutritive materials, and on the slow circulation of the 
 blood in the capillary vessels, which state of the circulation seems to give rise to the 
 predominance of hydrogen and carbon in the blood which these vessels and the veins 
 contain. The abundance of these elements in the extreme vessels being the source 
 whence the fat is so largely formed, the combination of them into that particular 
 substance is the result of the same state of the vital energies which favours their 
 predominance. This increase of bulk, owing to the augmentation of the secretion of 
 fat, in persons advanced in life, is far from being favourable to the free exercise of 
 the various functions ; for certain organs being incommoded with the weight and 
 bulk which they thus acquire, are still farther embarrassed in their organic move- 
 ments, the circulation in the extreme vessels is rendered still slower, and thus 
 the cause of the increased secretion of fat goes on increasing. This sufficiently 
 accounts for the fact, that, in general, leanness is at an advanced age more favourable 
 to long life than the opposite state.
 
 518 OLD AGE AND DECAY. 
 
 the physical and intellectual faculties undergo a gradual decay ; man 
 ceases to be impressed in the same manner by surrounding bodies. 
 His judgments are incorrect, because self-love preventing him from 
 being aware of the changes which he has undergone, he is more dis- 
 posed to ascribe to an universal degeneracy the difference which exists 
 between the sensations which he now experiences and those which he 
 experienced in his youth, (laudator temporis acti). The digestion is 
 bad, the pulse weak and slow; the absorption difficult, from the 
 almost complete obliteration of the lymphatics and the induration of 
 the conglobate glands, the languid secretion, and imperfect nutrition. 
 The old man is slow in all his actions and stiff in all his motions ; his 
 hair falls off, his teeth drop from their sockets : the cartilages ossify, 
 the bones grow irregularly and become anchylosed, their internal cavity 
 enlarges ; all the organs waste ; and the muscular fibres are indurated 
 and rigid. The bones become heavier, from the gradual accumula- 
 tion of phosphate of lime; and if, on the contrary, those of the 
 skull, as is justly observed by Soemmering, become lighter, it is that 
 they are in a manner worn out by the continued motions of the brain 
 on their internal surface. 
 
 The ossification of some of the cartilages, for example, of those of 
 the ribs and vertebrae, is productive of remarkable effects. The ribs 
 becoming- soldered in a manner to the sternum, perform very imper- 
 fectly their natural motions, (LXXI.) which contribute to the enlarge- 
 ment of the chest. This cavity dilating less fully, the pulmonary 
 combinations, which are the abundant sources of animal heat, take 
 place in a less effectual manner ; and this, joined to a want of tone and 
 energy in the lungs and in all the organs, lowers the temperature of 
 old people, as was observed by the father of physic ;* a circumstance, 
 however, which has been denied by De Haen. 
 
 Those fibro-cartilaginous laminae, with oblique fibres crossing each 
 other, which unite so firmly the bodies of the vertebrae, become indu- 
 rated, dried, and shrivelled, sink under the weight of the body, and do 
 not recover their former thickness, so that the stature is really reduced ; 
 besides, the weakened condition of the muscles which raise the trunk 
 makes the weight of the viscera bend forward the vertebral column, 
 whose different parts may remain fixed in this attitude, so that the 
 whole column, consisting of twenty-four vertebrae, may come to con- 
 sist of only seven or eight distinct bones. It should not be imagined, 
 however, that all the soft parts become more compact, for several, as 
 Haller observes, (the muscles, for instance), become softer, f and seem, 
 
 "Senibus autem modicus est calor * * * frigidum est enim ipsorum corpus." 
 Hipp oca. Aph. xiv. sect.,2. 
 
 f " Non ergo in sola rigiditate causam senii mortis oportet ponere ; nam ex 
 defectu irritabilitatis, plurimi in senibus musculi languent, mollesque pendent" 
 Elementa Physiol. torn. viii. 4 to. lib. 30.
 
 OF DEATH. 519 
 
 in losing a part of their vital properties, to draw towards a speedy dis- 
 solution ; not that death is entirely owing to the accumulation of 
 phosphate of lime, which enters into the composition of all the organs, 
 converts into ossific matter the whole osseous system, and interrupts 
 the action of the animal machine. If this ossific matter invade every 
 part of the animal system, it is because the digestive powers, gradually 
 weakened, cease to affect in a suitable manner the alimentary sub- 
 stances. The exuberance of calcareous salts is, therefore, not so much 
 the cause as the effect of the successive destruction of the vital powers. 
 
 The slowness, the rigidity, and the difficulty of moving, do not 
 depend so much as is thought on the induration of the ligaments and 
 other fibrous organs : these ligaments become softened and relaxed to 
 a considerable degree, so that luxation is more easily performed after 
 death in old people. In them, likewise, organs which in youth have a 
 degree of consistency, become flaccid and soft : this is the case with 
 the heart, which is found collapsed in old people, its cavities remain- 
 ing entire, while in young persons and in adults their parietes are firm 
 and not in close contact. 
 
 The brain becomes harder and firmer, and less soluble in alkalies; its 
 albumen appears more completely oxidised than in younger subjects ; 
 impressions are less easily made, and the motions necessary to the 
 operations of the understanding are performed with difficulty. Hence, 
 in decrepitude man returns, as far as relates to his intellectual facul- 
 ties, to a state of second childhood, limited to certain recollections, 
 which are at first confused, and in the end completely lost: incapable of 
 judgment or will, or of new impressions, sleep resumes its influence ; 
 reduced to a mere vegetative existence, he sleeps the greatest part of 
 the day, and wakens only to satisfy his physical wants and to take 
 food, which he digests very imperfectly; for, in the first place, the 
 want of teeth prevents his being able to divide sufficiently the different 
 substances ; and, in the next place, the supply of saliva, of gastric and 
 intestinal juices, is almost interrupted ; the bile and other fluids are 
 less active, and the intestinal tube is without energy. Universal 
 rigidity will be admitted as one of the principal causes of death, if it 
 be considered that women, in whom the organs are naturally softer, 
 are longer in reaching that state, are more retentive of life than men, 
 and generally live to a greater age. 
 
 The body, therefore, dies slowly and by degrees, says the eloquent 
 M. de Buffon ; life gradually becomes extinguished, and death is but 
 the last term of this series of degrees, the last shade of life. 
 
 CCXXXIX. Of death. Long, in fact, before the close of life, 
 man loses the power of reproduction ; and in the course of the agony 
 which serves as a passage between life and death, the organs of sense
 
 520 OF DEATH. 
 
 first become insensible to all sorts of impressions ; the eyes grow dim, 
 the cornea fades, the eye-lids close, the voice becomes extinct, the 
 limbs and the trunk motionless ; yet the circulation and respiration 
 continue to be carried on, but at last cease, first in the vessels furthest 
 from the heart, and then gradually in the vessels nearest that organ. 
 Respiration, gradually slackened, being entirely suspended after a 
 strong expiration,* the lungs no longer transmit the blood which the 
 veins bring from every quarter to the heart. This fluid stagnates in the 
 right cavities of the heart, and these die last, (ultimum moriens); and 
 distended by the blood which collects within them, they attain a capa- 
 city exceeding greatly that of the left cavities, which are, to a certain 
 degree, emptied. 
 
 Such is the course of natural death: the brain ceases to receive 
 from the weakened heart a sufficient quantity of blood to keep up 
 sensibility ; there remains still some degree of contractility in the 
 respiratory muscles ; it is soon exhausted, however, and the circulatory 
 motion of the blood ceases with the life of all the organs, of which this 
 fluid is one of the principal movers. 
 
 As to accidental death, it is always determined by the cessation of 
 the action of the heart and brain ; for the death of the lungs occasions 
 that of the whole body only by preventing the action of the heart, by 
 interrupting its influence on the encephalic organ. In natural death, 
 therefore, life becomes extinguished from the circumference to the 
 centre; in accidental death, on the contrary, the centre is affected 
 before the extremities. 
 
 Bichat, in his work entitled, " Recherches sur la Vie et la Mort," 
 1ms given a very complete account of the manner in which the organs 
 of the animal economy cease to act in articulo mortis ; but, like all the 
 authors who went before him, he has limited his inquiries to certain 
 functions. No one has attempted to extend them to the phenomena 
 of the action of the brain, nor has any one traced the order in which 
 the various faculties of thought and of sensation vanish. I shall endea- 
 vour faithfully to mention the results of several hundred observations 
 of my own on this subject. 
 
 The close of life is marked by phenomena similar to those with 
 which it began. The circulation first manifested itself, and ceases last. 
 The right auricle is the part first seen to pulsate in the embryo, and in 
 death is the last to retain its motion. The phenomena of nutrition, to 
 which the fetal existence is almost entirely limited, continue even 
 when the organs destined to establish a relation with the beings that 
 
 * Does this last and powerful expiration, often attended by sighing, depend on 
 the spasmodic contraction of the muscles of expiration ; or rather does it not depend 
 on the re-action of the elastic parts which form the chest a re-action which sud- 
 denly ceasea to be counterbalanced by the vital properties '*
 
 OF THE PERIOD OF DEATH- 521 
 
 surround us have long been sunk into a slumber from which they are 
 never to be roused. 
 
 The following is the order in which the intellectual faculties cease 
 and are decomposed.* Reason, the exclusive attribute of man, first 
 forsakes him. He begins by losing the faculty of associating judg- 
 ments, and then of comparing, of bringing together, and of connecting, 
 a number of ideas, so as to judge of their relations. The patient is then 
 said to have lost his consciousness, or to be delirious. This delirium 
 has generally for its subject the ideas that are most familiar to the 
 patient, and his prevailing passion is easily recognised. The miser 
 talks in the most indiscreet manner of his hidden treasures, the unbe- 
 liever dies haunted by religious apprehensions. Sweet recollections of 
 a distant native land, then it is that ye return with your all-powerful 
 energy and delight ! 
 
 After reasoning and judgment, the faculty of associating ideas is 
 next completely destroyed. The same occurs in fainting, as I once ex- 
 perienced in myself. I was conversing with one of my friends, when 
 I felt an insuperable difficulty in associating two ideas, from the 
 comparison of which I wished to form a judgment. Yet syncope 
 was not complete ; I still preserved memory and the faculty of feeling. 
 I could distinctly hear those about me say, " he is fainting," and exert 
 themselves to relieve me from this condition, which was not without 
 enjoyment. 
 
 The memory then fails. The patient who, during the early part of 
 his delirium, recognised the persons about him, no longer knows his 
 nearest and most intimate friends. 
 
 At last he ceases to feel, but his senses vanish in succession and in 
 a determinate order : the taste and smell cease to give any sign of 
 existence ; the eyes become obscured by a dark and gloomy cloud ; 
 the ear is yet sensible to sound and noise; and no doubt it was on this 
 account that the ancients, to ascertain that death had really taken 
 place, were in the habit of calling loudly to the deceased. Xv 
 
 A dying man, though no longer capable of smelling, tasting, hear- 
 ing, and seeing, still retains the sense of touch : he tosses about in his 
 bed, moves his arms in various directions, and is perpetually changing 
 his posture ; he performs, as was already said, motions similar to those 
 of the foetus within the mother's womb, 
 
 CCXL. Of the period of death. This period is nearly the same 
 with all men; whether they live near the poles or under the equator, 
 
 * I need not inform the reader that I am not here speaking of the immortal 
 soul, of that divine emanation which outlives matter, and which, freed from our 
 perishable part, returns to the Almighty. I am speaking merely of the intellectual 
 facnlties common to man, and to those animals which, like him, are provided with
 
 522 PROBABILITIES OF HUMAN LIFE- 
 
 whether they live exclusively on animal or vegetable substances, whe- 
 ther they lead an active life, or consume their existence in disgraceful 
 sloth, few live beyond a hundred. years. There are, however, cases of 
 men who have lived far beyond that period, as, for example, those 
 mentioned in the Philosophical Transactions, one of whom lived to a 
 hundred and sixty-five. 
 
 Few men, however, attain a hundred years, and death, even when 
 natural, overtakes us from the age of seventy-five to a hundred. 
 
 Difference of climate, though producing little difference in the 
 duration of life, has, however, a remarkable influence on rapidity of 
 growth. Puberty, manhood, and old age, come on much sooner in 
 warm climates than in northern countries ; but this premature deve- 
 lopement, which shortens the duration of the periods of life, augments 
 in the same proportion that of old age. 
 
 It is, however, difficult to say at what precise period old age begins. 
 Is it towards the fortieth year, when the body begins to decrease and 
 to decay ? Can the change of the colour of the hair be considered as 
 the certain sign of old age ? We daily see young men with gray hair. 
 May we determine its accession by the cessation of the functions of 
 generation and the incapacity of reproduction ? Fecundity, whose 
 term is so easily determined in woman by the cessation of the menses, 
 is in man very equivocal ; the emission of the seminal fluid is an uncer- 
 tain sign, from the difficulty of distinguishing the mucus of the vesiculse 
 seminales and of the prostate from the truly prolific semen. Erection 
 is likewise a sign not to be relied upon : this state may be occasioned 
 by sympathetic irritation, by the compression of the bladder distended 
 with urine on the vesiculee seminales. It is more difficult than is 
 imagined to determine from observation the period at which, in the 
 human species, the male is entirely deprived of the power of generation ; 
 and it may be said that, in establishing the period of from forty-five 
 to fifty-five as the beginning of old age in our climate, there will be 
 found men arrived at that state before having reached that age ; as, on 
 the other hand, others will be found after the age of fifty-five with all 
 the characters of manhood. The climacterical period of sixty-three is 
 the decided and confirmed period of old age. Whatever regimen may 
 have been followed, man at that age is truly old, and cannot but be 
 aware of it. 
 
 CCXLI. Of the probabilities of human life. Man dies at all 
 ages ; and if the duration of his life surpass that 9f the lower animals, 
 the great number of diseases to which he is liable renders it much more 
 uncertain, and is the cause why a much smaller number arrive at the 
 natural term of existence. It has been attempted to discover what are 
 the probabilities of life, that is, to ascertain from observation how
 
 PROBABILITIES OF HUMAN LIFE. 523 
 
 long a man may expect to live who has already reached a determinate 
 age. From late accurate observations of the age at which a number of 
 persons have died, and from a comparison of the deaths with tke births, 
 it has been ascertained, that about one-fourth of the children that are 
 born die within the first eleven months of life ; one-third under twenty- 
 three months ; and one-half before they reach the eighth year. Two- 
 thirds of mankind die before the thirty-ninth year, and three-fourths 
 before the fifty-first ; so that, as Buffon observes, of nine children that 
 are born, only one arrives at the age of seventy-three ; of thirty, only 
 one lives to the age of eighty; while out of two hundred and ninety- 
 one, one only lives to the age of ninety ; and, in the last place, out of 
 eleven thousand nine hundred and ninety-six, only one drags on a 
 languid existence to the age of a hundred years. 
 
 The mean term of life is, according to the same author, eight years 
 in a new-born child. As the child grows older his existence becomes 
 more secure, and after the first year he may reasonably be expected 
 to live to the age of thirty-three. Life becomes gradually firmer up to 
 the age of seven, when the child, after going through the dangers of 
 dentition, will probably live forty-two years and three months. After 
 this period, the sum of probabilities, which had gradually increased, 
 undergoes a progressive decrease ; so that a child of fourteen cannot 
 expect to live beyond thirty-seven years and five months ; a man of 
 thirty, twenty-eight years more ; and, in the last place, a man of eighty- 
 four, one year only. From the eighty-fifth to the ninetieth year, 
 probabilities remain stationary, but after this period, existence is most 
 precarious, and is painfully carried on to the end. Such is the result 
 of observation, and of calculations on the different degrees of proba- 
 bility of human life, by Halley, Graunt, Kersboom, Wargentin, Simson, 
 Deparcieux, Dupre de St. Maur, Buffon, d'Alembert, Barthez, and 
 M. Mourgues, who has just published his observations, collected at 
 Montpelier in the course of a great number of years, and with the most 
 scrupulous accuracy.* 
 
 * From the observations made during more recent periods, it would appear that 
 the mean duration of human life has experienced an increase of nearly five years in 
 the greater number of European countries. This may be in some measure owing to 
 the introduction of vaccination, but perhaps the chief causes may be found in the 
 progress of science and civilisation, giving rise to a general improvement in the 
 habits of life, particularly with regard to ventilation and cleanliness ; to better habi- 
 tations ; a more ample supply of food, clothing, and fuel ; greater sobriety ; a more 
 general cultivation of the soil, and consequent removal of the sources of several 
 diseases ; to improved management of children ; and to the advanced state of medi- 
 cal knowledge. 
 
 The same causes that conduce to longevity must of course increase the popula- 
 tion of a country. The suppression of monastic celibacy, and the more equal dis- 
 tribution of landed property, consequent on the revolution in France, have tended
 
 524 PROBABILITIES OF HUMAN LIFE- 
 
 I should enter more fully into this subject, but that it belongs 
 rather to the department of political economy than to that of phy- 
 siology. 
 
 Do the calculations on the probabilities of human life present 
 results applicable to the generality of cases, and is the mean duration 
 of existence nearly the same with all men, in all countries and climates? 
 The shepherd of the Pyrenees, who lives happy in the innocence of a 
 pastoral life, breathing the pure air of his mountains, is he, in this 
 respect, subject to the same laws as the inhabitant of populous cities, 
 exposed to the inconveniences attending numerous collections of men ; 
 inconveniences which, viewed in a philosophical point of view, or which, 
 being greatly over-rated, have so often furnished a text to the medita- 
 tions of philosophy, and to the idle declamations of oratory?* 
 
 Does life experience a progressive diminution in proportion to the 
 duration of the world; and to say nothing of the time preceding the 
 flood, when, according to the Book of Genesis, men lived several hun- 
 dred years, did the men of former times live longer than those of our 
 own? This is very improbable: among the Egyptians, the Hebrews, 
 the Greeks, and Romans, there were very few instances of persons 
 living to the age of a hundred years, and instances of longevity are 
 perhaps more frequent among the moderns. 
 
 to increase the population of that country, notwithstanding the destructive wars in 
 which she has been engaged J. C. 
 
 * In order to answer these questions in a satisfactory manner, it would be neces- 
 sary to have tables of mortality kept with care in the different countries and climates 
 of the globe. The religions and superstitions of the East, of all Africa, and of a 
 great part of America, oppose invincible obstacles to these researches, independently 
 of those resulting from the state of civilisation, and the policy of the various govern- 
 ments of these countries. Judging, however, from the results already before us, 
 the northern kingdoms of Europe appear to be those in which mankind enjoy the 
 longest term of existence. The tables of mortality of the empire of Russia for the 
 year 1811, gave, in 828,561 individuals deceased belonging to the Greek church, 
 947 who had reached a hundred years and upwards ; amongst whom were 83 of 
 115 years of age, 51 of 120, 21 of 125, 7 of 130, 1 of 135, and another who had 
 reached 140. 
 
 According to the abstract of the population returns of Great Britain in 1821 , the 
 number of individuals in England, aged from 90 to 100 years, was 9'90 in every 
 20,000 ; and of those aged 100 and upwards, 34 : the general mortality was 1 in 
 57. In Scotland, those aged from 90 to 100 was 14.13; and 100 and upwards, 1-903 
 in every 20,000. In Wales, the number of persons aged from 90 to 100 was 17'97; 
 and of those aged 100 and upwards, -50 in 20,000 : the mortality was 1 in 69. 
 
 The maximum longevity was found to be in Scotland, in the shire of Ross and 
 Cromarty. Here the proportion of individuals aged from 90 to 100 was 34-39 to the 
 20,000 ; and of those aged 100 and upwards, 9'22. In the shires of Inverness and 
 Argyle, the proportion of persons aged from 90 to 100 were 34-49 and 29-84, re- 
 spectively, to 20,000. In 1811, the population of Scotland was 1,865,900 ; in 1821 
 it was 2, 135,300.
 
 OF PUTREFACTION. <5'25 
 
 The art of providing for the wants of life making daily progress, 
 it is very probable, that far from being shortened, the term of human 
 life may be lengthened a certain number of years beyond its ordinary 
 duration. This idea is, it is true, contrary to the commonly received 
 opinion of the progressive depravity of mankind in all ages ; but the 
 golden age never existed but in the imagination of poets, and the daily 
 complaints of morose old age have their origin in motives easily under- 
 stood by the physiologist. He whose sentiment is blunted by a long 
 course of years, is affected in a very different manner by surrounding 
 objects. As to the old man, flowers have lost their scent and beauty, 
 fruits no longer retain their flavour ; the whole of nature seems dull 
 and colourless. But the cause of all these changes is within himself; 
 every thing else remains as it was. Always equally fruitful, Nature ex- 
 poses every thing to the action of her inexhaustible crucible, maintains 
 every thing in a state of everlasting youth, and preserves a freshness ever 
 renewed. Individuals die, species are renovated ; life every where 
 arises in the midst of death. The materials of organised bodies enter 
 into new combinations, and serve in forming new beings, when life 
 ceasing to animate those to which they belonged, putrefaction seizes 
 upon them and effects their destruction. 
 
 CCXLII. Of putrefaction. Here the history of life ought to 
 terminate: if, however, it be considered that the changes which bodies 
 
 The first actual enumeration of the inhabitants of England and Wales was made 
 in 1801, and gave a population of 9,168,000, and a mortality of 1 in 44'8. The 
 second was made id 1811, and gave a population of 10,502,900, and a mertality of 
 1 in 50. The third and last, which took place in 1821, has given an enumeration 
 of 12,218,500, and a mortality of 1 in 58. 
 
 It appears from these returns, that the healthiest counties in England and Wales 
 are Pembroke, Sussex, Cornwall, Cardigan, and Monmouth, the mortality in these 
 being 1 in about 71 ; and that the least salubrious are Middlesex, Kent, Surry, and 
 Warwick, the mortality being in these 1 in about 50. It is not easy to explain 
 altogether the difference in salubrity in the different counties. Locality is, doubt- 
 less, an important agent. Cities and large manufacturing towns modify greatly the 
 ratio of mortality in a particular district. This is well illustrated wich respect to 
 London. In 1700, the annual mortality of this city was 1 in 25 ; in 1750, 1 in 
 21 ; in 1821 and the four preceding years, 1 in 35 ; in 1810, 1 in 38 ; and in 1821, 
 1 in 40. 
 
 It must be evident, that the increase or diminution of the population of a dis- 
 trict, as well as the mean term of life in it, must depend upon the nature of the 
 climate and soil, its mean elevation and temperature, the state of its civilisation 
 and cultivation, pursuits of its inhabitants, and means of subsistence. The govern- 
 ment and religion of a country also exert no inconsiderable control on the mean 
 duration of human life, and increase of its population. Together with these already 
 mentioned, many other causes of a moral and physical nature may be adduced, as 
 influencing in no slight degree the extent of population, and the salubrity of a dis- 
 trict or country. J. C.
 
 526 OF PUTREFACTION. 
 
 experience after death throw a considerable light on its means, its ends, 
 and its nature, there will be an obvious necessity for shortly inquiring; 
 into the different phenomena which accompany the decomposition of 
 animal substances. And this investigation appears to me to belong to 
 the department of physiology, until the aspect of the body ceases to 
 recall the idea of its former state, and until the last lineaments of or- 
 ganisation are completely effaced. As soon as life forsakes our organs, 
 they become subject to the laws of physics operating on substances that 
 are not organised. An inward motion takes place within their sub- 
 stance, and their molecules have the greater tendency to become 
 separated from one another as their composition is more advanced. 
 Chemistry informs us, that the tendency to decomposition of bodies is 
 in direct ratio to the number of their elements ; and that a dead animal 
 body is capable of remaining unchanged, in proportion as its compo- 
 sition is more simple, and its constituent principles less numerous and 
 less volatile. 
 
 Before putrefaction can come on in the human body, it must be 
 entirely deprived of life, for the vital influence is most powerfully anti- 
 septic; and one might say that life is a continual struggle against the 
 laws of physics and chemistry. This vital resistance, alluded to by the 
 ancients when they said that the laws of the microcosm were in per- 
 petual opposition to those of the universal world, and that these in the 
 end prevailed this power which is in a state of perpetual re-action, 
 manifests itself in life : the latter, considering only the results, might 
 therefore be defined as follows the resistance opposed by organic 
 bodies to the causes incessantly tending to their destruction. By 
 attending to all these phenomena, it will be seen that all of them tend 
 to one end the preservation of the body, and that they obtain it by 
 keeping up a perpetual struggle with the laws which govern inorganic 
 substances. 
 
 It might appear singular that death should furnish a just idea of 
 life, did we not know that it is by comparing that we are enabled to 
 distinguish, to judge, and to arrive at knowledge. 
 
 Putrefaction takes place and is completed only in substances 
 deprived of life. A mortified limb loses its vitality before putrefaction 
 comes on ; and if Nature preserve sufficient energy to resist this de- 
 structive process, she draws, by a line of inflammation, the separation 
 between the dead and the living part. Life and putrefaction are, 
 therefore, two absolutely contradictory ideas; and when, in some dis- 
 eases, there is observed a tendency in the solids and fluids to sponta- 
 neous decomposition, this tendency to putrefaction should not be mis- 
 taken for putrefaction itself. 
 
 Several conditions are required to enable putrefaction to affect the
 
 OF PUTREFACTION. 527 
 
 human body after death. In the first place, a mild temperature, that 
 is, above ten decrees of Reaumur's thermometer; in the next place, a 
 certain degree of moisture ; and lastly, the presence of air. This last con- 
 dition, hcwever, is not so necessary as the two former, since substances 
 undergo putrefaction in a vacuum, though more slowly. The air con- 
 sequently promotes a decomposition only by carrying off the element, 
 which rises in vapours. On the other hand, an icy cold, or a degree 
 of heat approaching to boiling, prevents it ; the former by conden- 
 sing the parts ; the second by depriving them of moisture, the com- 
 plete absence of which accounts for the preservation of the Egyptian 
 mummies. 
 
 The phenomena of putrefaction, resulting from a series of peculiar 
 attractions, are modified in various ways according to the nature of the 
 animal substances which are subjected to it, to the media in which it 
 takes place, to the different degrees of moisture and temperature, and 
 even according to its different periods. Notwithstanding these innu- 
 merable varieties, one may say, that all exhale a certain cadaverous 
 smell, are softened, increase in bulk, acquire heat, change colour, 
 assume a greenish, then a livid and dark-brown colour : there are, 
 at the same time, disengaged a great number of gaseous substances, 
 of which ammonia is the most remarkable, either from its quantity, 
 or from being given out by animal substances from the moment when 
 decomposition begins to the period of the most complete dissolution. 
 This gas produces the pungent and putrid smell which exhales from 
 dead bodies. 
 
 Towards the termination of putrefaction, there is disengaged car- 
 bonic acid gas, which, combining with ammonia, forms a fixed and 
 crystallisable salt. Besides these products, there are given out sul- 
 phuretted and phosphoretted hydrogen, azote, carbonic acid, and all 
 the gaseous matters that may be produced by their respective com- 
 binations. In the last place, animal substances, when reduced to a 
 residue containing oils and salts of different kinds, form a mould, from 
 which plants draw the principles of a luxuriant and vigorous vege- 
 tation. The bones, those least alterable parts of the organised machine, 
 in time become dried by the slow combustion of their fibrous part, and 
 by the evaporation of their medullary juices. At last, reduced to an 
 earthy skeleton, they crumble into dust, and this dust is dissipated on 
 opening the tombs in which they were laid. 
 
 Thus, in course of time, is effaced all that could recall the idea of 
 our physical existence. 
 
 Putrefaction, considered in a philosophical point of view, is but 
 a means employed by nature to restore our organs, deprived of life, 
 to a more simple composition, in order that their elements may be
 
 528 OF PUTREFACTION. 
 
 applied to new creations (circulus aterni motus*). Nothing, there- 
 fore, is better proved, than the metempsychosis of matter ;f which 
 warrants the belief that this religious dogma, like most of the fabulous 
 worships and imaginations of antiquity, is but a veil ingeniously thrown 
 by philosophy between nature and the ignorant. 
 
 * BECCHER, Physica subterranea. 
 
 f Matter is eternal in this sense, that the molecules of bodies merely pass from 
 the one into the other ; they survive the destruction, or rather the dissolution, of 
 organic and inorganic beings, when the former, ceasing to live, restore to the inex- 
 haustible fund of Nature those elements which she lends without ever parting with 
 them. 
 
 Mancupio nulli datur, omnibus usu LUCRET. lib. iii.
 
 APPENDIX: 
 
 JAMES COPLAND, M.D. &c.
 
 i a vi
 
 ADDITIONAL NOTES 
 
 PRELIMINARY DISCOURSE. 
 
 OF LIFE. 
 
 (NOTE A. See pp. 1, 10, 41, 189.) 
 
 PHYSIOLOGISTS are divided into those admitting a principle of life, 
 and those attributing the vital phenomena to organisation solely the 
 latter class contending that life presupposes organisation, the former 
 that organisation presupposes the presence of life. An attentive 
 consideration of the phenomena presented by the whole range of 
 organised bodies, and a fair contrast instituted between these and the 
 changes which inanimate matter exhibits, will readily convince the 
 mind unbiassed by preconceived notions which of the two doctrines 
 to prefer. 
 
 Those who contend that life is the result of organisation ought to 
 explain in what manner the organisation itself took place ; they should 
 shew the means employed to produce the disposition of parts, which 
 they conceive requisite to give rise to vital phenomena. If they deny 
 the primary influence of a vital power associated with the particles of 
 matter, let them explain by what other agency the different atoms 
 can assume organic actions. All effects must have a cause, and it is 
 better to assign one according to which difficulties may be accounted 
 for, than to contend for the efficiency of properties or powers of the 
 existence of which we have no evidence, and which, even granting 
 them to exist, can only be considered as inferior agents, or peculiar 
 manifestations of a vital principle. 
 
 With respect to this class of physiologists, it may be remarked 
 generally ; 1st. That explanations of organisation which admit not 
 of the primary and controlling influence of vitality, however applicable 
 they may seem to those who look only at the gross relations of things, 
 cannot satisfactorily account for the origin and nature of the phe- 
 nomena to which they relate ; for, however terms may be substi-
 
 532 APPENDIX. 
 
 tuted, or illustrations multiplied, the changes which continually 
 tafye place in living bodies cannot be explained by means of the 
 laws and affinities which characterise the combinations of inorganised 
 matter. 
 
 2d. In order to explain the phenomena which are more justly as- 
 cribed to a vital principle, the supporters of the doctrine of organism 
 have recourse to the substitution of properties, occult qualities, im- 
 pulses, and motions ; and when required to shew wherein these 
 qualities, impulses, and properties, are different from those which we 
 observe in organised matter, and are there subjected to our experience, 
 they endeavour to get rid of the difficulty by denominating them vital ; 
 thus tacitly admitting the very principle, in the place of which such 
 insufficient properties are attempted to be substituted ; and, after all, 
 without the smallest success in preventing a recurrence to this prin- 
 ciple, of which all these properties, admitting their existence, are 
 nothing else than the results : for, however we may denominate them, 
 we merely substitute expressions which (if they convey any meaning) 
 imply only the existence of certain effects or operations which are 
 inferior agents or instruments, under the control of vitality, in the pro- 
 duction of the organic phenomena. 
 
 From this view, therefore, of the subject, it appears that the argu- 
 ment used against the existence of a vital principle is rather verbal than 
 real. The organists cannot even prove the basis of their doctrine, for 
 they cannot sl.ew that organisation came into existence before the 
 effects which they impute to it ; and while they bestow properties and 
 qualities on organised matter similar to those imputed to a vital 
 principle, and different from those which characterise inorganised 
 matter, although they cannot point out the difference otherwise than 
 by calling them vital, they virtually admit the existence of the prin- 
 ciple against which they contend : for what principle in nature, we 
 w6uld ask, can be shewn to exist, or how can its existence be ration- 
 ally inferred, but by certain properties and qualities which are pecu- 
 liar to itself, and which, moreover, as respects this principle, are 
 dissimilar and greatly superior to, and indeed hold a controlling in- 
 fluence over, all the other properties of matter with which we are 
 acquainted ? 
 
 Such, therefore, being the case, we are justified in recurring to the 
 belief in a vital principle, which, allied to matter, controls its changes 
 and forms, and to which principle the laws and affinities of matter are 
 entirely subject, whenever they are embraced within its sphere of 
 action. By means of this superior principle, we are enabled to explain 
 the phenomena of the organised creation and of the human economy ; 
 but without reference to it we are lost in the mazes of vague hypo- 
 thesis and groundless supposition.
 
 OF LIFE. 533 
 
 It has been objected to the existence of this principle, that we can- 
 not demonstrate it to the senses in any form unconnected with matter. 
 But we are not contending for the existence of a principle which is 
 material, according to the received notions respecting matter, other- 
 wise there would be at once an end of the argument. It is, therefore, 
 no evidence of the non-existence of this principle, that it does not 
 become visible to our senses in an uncombined form : it is, however, 
 sufficiently demonstrable by its effects, in alliance with matter, in which 
 state it presents proofs of its existence equal to those from which we 
 infer the existence of matter itself. 
 
 From these, and many other considerations that might be adduced, 
 we conclude that life is a first principle in nature ; that it exists in 
 various degrees of energy, and in diversified conditions and forms, 
 throughout her domains ; and that these diversified states of vital, ex- 
 istence are continued, as far as the operation of extraneous causes 
 will admit, by a specific process, which gives rise to the production of 
 similar beings by means of ova and germs. 
 
 It will be perceived, that the generation by which vegetable and 
 animal bodies are perpetuated involves the belief that the ova or 
 germs convey an emanation from the parent' of a specific portion of 
 vitality. 
 
 As, however, we can form no just conceptions of such a principle 
 but by its effects, and as we have no experience of these effects uncon- 
 nected with matter, so we are warranted in the conclusion, that the 
 vital influence is associated with the molecules of matter forming the 
 impregnating secretions and the sensible bulk of the ovum. This is 
 its lowest state v of activity or energy ; and its influence is chiefly mani- 
 fested, under such circumstances, in preserving the elements of matter 
 with which it is associated from entering into the combinations to 
 which the chemical affinities of these elements dispose them. 
 
 The hibernation of animals presents this principle also in its lowest 
 degree of activity : in either case, and indeed under every circumstance, 
 it is acted upon and excited to an exalted state of existence by 
 most of the active agents in nature. The electric fluid, heat, and 
 other powers, have this effect, while some appear to produce a con- 
 trary impression. 
 
 The manner in which several of the active agents of inorganic na- 
 ture thus influence the energy of the vital principle, appears to have 
 been the chief reason \rhy these powers have been substituted for 
 vitality itself. 
 
 We have stated that the manifestations of this principle throughout 
 the vegetable and animal kingdoms present considerable difference in 
 degree. Its character in the vegetable creation is more uniform, and 
 its phenomena more simple. We perceive in this kingdom, under
 
 534 APPENDIX. 
 
 circumstances which furnish the usual stimuli, that the vital operations 
 of digestion, circulation, respiration, and assimilation, go forward. As 
 soon, however, as the exciting causes are withdrawn, this principle 
 subsides to a state of less activity ; and the integrity of such organs 
 and textures as are necessary to the growth and propagation of the 
 species, is merely preserved by its influence until a returning impulse 
 excites its energies. 
 
 As we advance in the scale of the animal creation, the operations 
 of this principle become more distinct and numerous, and the me- 
 chanism provided for the performance of them more manifest and com- 
 plex. As they are performed in man and in the more perfect animals, 
 may be gathered from the body of the work and the notes which 
 follow. 
 
 OF THE NERVOUS SYSTEM IN THE LOWER ANIMALS. 
 
 (NOTE B. See pp. 12, 189.) 
 
 The lowest order of animals, as the polypi, &c. has usually been con- 
 sidered to be destitute of a nervous system. This, however, is not the 
 case. If we look narrowly into the structure of the lower animals, we 
 shall find that even the lowest offers traces of a nervous system ; and 
 as we rise through the scale of the animal creation, we shall find this 
 system becoming more and more perfect in its state of existence, and 
 presenting appearances of perfection in proportion to the number and 
 extent of functions which the animal is capable of exerting. Even the 
 polypus, the lowest of the animal kingdom, seems to possess a nervous 
 system in the simplest state of existence. If this apparently homo- 
 geneous animal be examined with a powerful microscope, numerous 
 globules, entirely resembling those seen in the nervous system, appear 
 disseminated throughout its structure. As a result of this simplicity of 
 conformation, it presents no perfect manifestation of sensibility and 
 contractility. It is not constituted of separate textures and organs, des- 
 tined to perform specific purposes ; and, consequently, as no relation 
 or bond of union is requisite between its parts, as in those animals 
 which have particular organs or structures executing particular offices ; 
 and as each of its individual parts performs the functions of the whole 
 animal, so its nervous system is disseminated throughout its structure, 
 without being arranged into cords of communication or centres of 
 reinforcement, as in those animals which, endowed with distinct organs 
 and perfect functions, possess both. 
 
 As we rise in the scale, on the contrary, we perceive in the more 
 perfect, and in the highest animals, the intimate texture of the nervous 
 system, arranged so as to form communicating cords between organs 
 which are distantly separated from each other; and not only are they
 
 OF THE ELEMENTARY SOLIDS. 535 
 
 provided with these, but each viscus frequently possesses, in addition, 
 a separate nervous centre, on which the functions performed by that 
 viscus depend : whilst the former arrangement is calculated to preserve 
 a reciprocity of action a mutual dependence of parts and of func- 
 tions, the latter generates a vital influence modified in kind and in 
 degree to the part which it actuates ; which influence, in conjunction 
 with what the organ may receive from a common centre, and what 
 may be generated in the nerves of its own structure, is exerted in the 
 production of the functions of which the conformation of the organ is 
 but the mechanical instrument. Thus the vital influence is furnished 
 to the different viscera in proportion to, and suitably with the nature 
 of, its expenditure in the more complex and more complete exertion of 
 the operations which each of them is destined to fulfil. 
 
 Respecting this subject, therefore, the following propositions may 
 be stated : That according to our own observations, as well as those 
 of Prochaska, the Wenzels, Bauer, and Edwards, corpuscles or globules, 
 entirely similar to those of which the nervous system is composed, are 
 found disseminated, without any regular order, throughout'the appa- 
 rently homogeneous structure of the lowest order of the animal king-/- 
 dom : that, as we rise in our observations through the scale of animals, 
 we perceive this dissemination of the nervous corpuscles existing 
 only in the mucous structures ; and, as the animal presents separate 
 organs destined to the vital operations, so these nervous corpuscles are 
 disposed into cords of communication, and we observe a distinct ner- 
 vous mass or masses, each organ possessing in addition the higher 
 that we ascend in the scale more especially a detached but de- 
 pendent nervous mass or ganglion of reinforcement, which varies in 
 form, appearance, and connexion with other organs, or with other parts 
 of the same system, according to the functions which it is destined to 
 actuate. -See the notes on Generation, and on the Developement of 
 the Textures of the Body, for some farther remarks illustrative of this 
 subject. 
 
 OF THE PRIMARY SOl-IDS AND COMPOUND TEXTURES OF 
 THE BODY. 
 
 (NOTE C. See p. 18.) 
 
 The intimate or elementary constitution of the animal textures has 
 long engaged the attention of anatomists and physiologists. As re- 
 searches respecting this subject can only be prosecuted by means of 
 the microscope, the results must, therefore, be received with some 
 degree of reservation, unless they coincide with the observations of 
 former inquirers, or be confirmed by subsequent observers. From 
 amongst those who have engaged in this species of investigation,
 
 536 APPENDIX. 
 
 J.F. Meckel is entitled to much confidence, on account of his talents 
 and industry ; and the results of his labours claim particular notice, 
 as they confirm much that has been recorded by former observers. 
 
 According to the views of this physiologist, the solids and fluids of 
 the human body may be reduced to two elementary substances : the 
 one is formed of globules, the other of a coagulable matter, which, 
 either alone or united to the former, constitutes the living fluids when 
 it is in the liquid state, and gives rise to the solid tissues when it assumes 
 the concrete form. 
 
 The globules present, in their nature and aspect, differences which 
 are relative to the situations in which they are examined. They appear 
 in the blood flattened, and composed of a central part which is solid, 
 and of an exterior portion which is hollow and vesicular. Those 
 found in the kidneys are smaller than those of the spleen, and the 
 globules of the liver are still smaller ; those contained in the sub- 
 stance of the nerves present a less volume than those observed in the 
 blood. 
 
 Globules exist not, according to Meckel, in the proper structure of 
 
 the cellular tissue, of fibrous and cartilaginous parts, and of the bones. 
 
 On the contrary, they abound in nerves and muscles, and determine 
 
 their nature and colour. Some of the fluids, also, as the urine, contain 
 
 "^ no globules, whilst they are abundant in the blood, in the chyle, the 
 
 V lymph, milk, &c. 
 
 During the first period of conception, the mucous and homogeneous 
 mass which constitutes the embryo contains no globules; it is not 
 until a more advanced period that it is composed of two substances, 
 the one fluid the other solid. These two elements seem to influence 
 the form of the fibres and plates in which animal substances are dis- 
 posed. The laminated tissues arise almost exclusively from the fluid 
 matter. The fibrous tissues may also be produced from this matter 
 alone, as in the tendons, &c. ; they are, however, more frequently 
 formed from the union of the globules with the concretive fluid, as may 
 be observed in the nervous and muscular textures. 
 
 These observations of Meckel respecting animal organisation, it 
 ought to be noticed, bear a near resemblance to the opinion enter- 
 tained by Pfaff, who considered the elementary tissues to be formed 
 from a series of molecules and globules, and to be different according 
 to the presence and influence of the latter form of matter. The idea 
 of an animal fluid, capable of concretion, is analogous to the opinion 
 of the ancients respecting the substance denominated by them gluten. 
 It is the cellular tissue, according to Meckel, which represents that 
 substance ; and, in fact, he regards this tissue as a species of concrete 
 fluid, possessed of the properties already indicated. 
 
 It must, in our opinion, be admitted, that the theory of Meckel
 
 OF THE COMPOUND SOLIDS. 537 
 
 possesses claims to a favourable notice. It is the result of observations 
 which accord with those of others ; it is also simple, and is easily to be 
 reconciled with the phenomena which living textures present. 
 
 Dr. Meyer, of Bonn,* also considers that two kinds only of ele-\ 
 men^ary textures exist in animal bodies. The one is, according to 
 him, composed chiefly of capillary vessels, and is formed from the 
 assemblage of these vessels ; under it he arranges cellular, serous, 
 fibrous, and mucous tissues : the other possesses a proper and peculiar 
 parenchyma, composed of globules, or of an organic pulp ; such are 
 the glands, the bones, muscles, nerves, the brain and spinal cord. 
 The first set of organs is a continuation, in his opinion, of the vascular 
 system ; while the second, on the contrary, is farther removed from 
 such a connexion. Foreign substances introduced into the circulation 
 pass immediately, and with rapidity, into the former textures; while 
 they either fail altogether in penetrating, or insinuate themselves much 
 more slowly, and after quite a different manner, into the parenchyma 
 of the latter organs. The one class seems to appertain in general to 
 the system of secretion ; the other class of textures neither secrete 
 from their own individual influence, nor can they of themselves add to 
 their nutrition. The first appears to be nourished by the immediate, 
 rapid, and continual access of the fluid part of the blood ; the second 
 by a slow and periodic deposition, and conversion into their proper 
 substance, of the sanguineous globules of the blood, by means of 
 the influence of the vascular extremities upon the blood which they ^ 
 contain. 
 
 The primary solids, or rather the elementaryf fibres of the human 
 body, and of the higher classes of animals, cannot be considered with 
 propriety to be more than three the cellular or laminar, the mus- 
 cular, and the nervous. 
 
 1st. The cellular fibre is the most essential to animal existence, 
 and is found in every individual of this kingdom. It consists of an 
 assemblage of minute laminae and delicate filaments. It is neither 
 sensible nor irritable, and is chiefly composed of a nearly concrete 
 gelatine. 
 
 2d. The muscular fibre is not so generally distributed throughout 
 the animal kingdom as the former, for it is not found in the zoo- 
 phytes. 
 
 3d. The nervous or medullary fibre. The nature of this tissue has 
 
 * Journ. Compltm. des Scien. Mtd. Nov. 1821. 
 
 f It should be kept in recollection, that fibre is used as signifying an elementary 
 animal substance ; tissue indicates a certain arrangement of the former a pecu- 
 liar structure of parts ; and organ signifies a compound or complex part which per- 
 forms functions peculiar to itself.
 
 538 APPENDIX. . 
 
 been the subject of much investigation. M. de Blainville thinks that 
 it originates in the muscular fibre, as this latter takes its origin in the 
 cellular substance. 
 
 To these fibres Professor Chaussier has added a fourth, namely, the 
 albuyineous fibre, which is satiny, white, and very strong; and is neither 
 sensible nor irritable. The majority of anatomists, however, consider 
 it as merely a very condensed variety of the cellular fibre. 
 
 These fibres may be called the first order of solids, as they serve 
 to form all the other tissues and organs of the body. The cellular sub- 
 stance, for instance, is spread out and condensed into membranes, or 
 rolled up in the form of vessels ; muscular fibres also assume the form 
 of membranes, concur in the formation of vessels, and constitute mus- 
 cles ; nervous fibres produce the nerves, &c. Finally, those primary 
 solids associate in various forms, and give rise to the compound solids, 
 as the bones, the glands, &c. ; and even to those of a more complex 
 nature, as several of the thoracic and abdominal viscera. Indeed, every 
 species of solid has for its base cellular substance, which is penetrated 
 by nerves and vessels. The viscera, for example, are of this nature, 
 having, moreover, membraneous envelopes. The bones also consist of 
 a similar texture, and of a deposition of phosphate of lime in their cel- 
 lular substance.* 
 
 Those primary solids, or most simple anatomical constituents, which 
 we have just now particularised, associate in various forms, giving rise 
 to compound solids or tissues, which are characterised not only by their 
 form and nature, but also by the functions which they perform. 
 
 These animal textures or compound solids were first arranged with 
 any degree of accuracy by Bichat ; and however successful future 
 researches into their ultimate nature may be, or whatever classifi- 
 cations may be proposed by future inquirers, he is still entitled to the 
 honour of having introduced a philosophical analysis into anatomical 
 and physiological science. The arrangement of the tissues which 
 this great man adopted is as follows: The exhalent, absorbent, 
 cellular, arterial, venous, nervous of animal life, nervous of organic 
 life, osseous, medullary, cartilaginous, fibro-cartilaginous, fibrous, 
 muscular of animal life, muscular of organic life, mucous, serous, 
 synovial, glandular, dermoid, epidermoid, and corneous or pilous, sys- 
 tems. The exhalent, absorbent, cellular, arterial, venous, and nervous 
 systems, he considered as being the frame-work of the body, and as. 
 generating the other structures, which he denominated the compound 
 tissues. 
 
 M. Dupuytren has lately proposed another classification, possessing 
 some advantages over that of Bichat. He has reduced the number of 
 
 " See Adelon's Physiology, vol. i. p. IOC.
 
 OF THE COMPOUND SOLIDS. 539 
 
 textures or systems to twelve, viz. the cellular ; the vascular, sub- 
 divided into arterial, venous, and lymphatic ; the nervous, divided 
 into that of the ganglions and of the brain ; the osseous, the carti- 
 laginous ; the fibrous, comprehending the fibrous proper, the fibro- 
 cartilaginous, and the dermoid ; the muscular of voluntary and in- 
 voluntary motion ; the erectile ; the mucous ; the serous ; the corneous, 
 embracing the pilous and epidermoid tissues ; and the parenchyma- 
 torn, forming the viscera, and including glandular structures. 
 
 M. Beclard* admits but ten systems : the cellular and adipose, the 
 serous and synovial, the tegumentary surfaces, comprehending the skin 
 and mucous membranes ; the vascular, the glandular, the ligamentous, 
 the osseous, the cartilaginous, the muscular, and the nervous. 
 
 J. F. Meckel f also admits but ten animal structures : the cellular 
 or mucous, the vascular, the nervous, the osseous, the cartilaginous, the 
 fibrous, the fibro-cartilaginous, the muscular, the serous, and the 
 dermoid. 
 
 M. de Blainville t considers that the animal structures amount to 
 sixteen, of which nine are produced from the cellular fibre, three from 
 the muscular fibre, and four from the nervous fibre. In the first divi- 
 sion he arranges the dermoid, mucous, fibrous, cartilaginous, osseous, 
 serous, synovial, arterial, and venous (embracing the lymphatics) 
 systems. Under the second division he places the sub-dermoid or 
 voluntary muscular system, the sub-mucous or involuntary muscular 
 system, and the heart. To the third division he assigns the pulpy 
 ganglial system, the non-pulpy ganglial system, the nervous system of 
 animal life, and the nervous system of organic life. 
 
 Professor Mayer has recently adopted a classification of the animal 
 textures or compound solids, founded on his views respecting the 
 elementary fibres or primary solids. He recognises only eight systems, 
 viz. 1st, the lamellated tissue; 2d, the cellulo-filamentous tissue; 3d, 
 the fibrous system ; 4th, the cartilaginous tissue ; 5th, the osseous 
 tissue; 6th, the muscular fibre ; 7th, the glandular structure; and 
 8th, the nervous tissue.\\ 
 
 The arrangement of solids which we would propose is nearly the 
 same as that given by us at another place. Proceeding analyti- 
 cally, we would divide the compound solids of the body into four 
 classes, viz. complex structures, particular textures, general systems, 
 and elementary fibres or solids. 
 
 * Anal. Gtnerale, p. 100, et seq. 
 
 f Manual of Descriptive, General, and Pathological Anatomy, vol. i. p. 22, 
 
 J Princip. d'Anat. Comp. t. i. p. 13, et seq. 
 || Bibliotheque Germanique, No. viii. t. 2. 
 London Medical Repository for July 1823.
 
 540 APPENDIX. 
 
 I. COMPLEX OR, ASSOCIATED STRUCTURES. 1st, the digestive 
 organs ; 2d, organs of absorption and circulation ; 3d, of respiration and 
 assimilation ; 4th, organs of secretion and excretion ; 5th, organs of 
 motion and of sensation ; and 6th, organs of generation. 
 
 II. PARTICULAR TEXTURES. This class includes, 1st, the mu- 
 cous textures ; 2d, serous textures; 3d, \hefibrous textures, embracing 
 the fibrous, the fibre-cartilaginous, and the dermoid ; 4th, the carti- 
 laginous textures ; 5th, the osseous textures ; 6th, the erectile textures ; 
 7th, the glandular textures, including the parenchyma of the viscera; 
 8th, the corneous textures, embracing A, the pilous, and D, the epider- 
 moid textures. 
 
 III. GENERAL SYSTEMS. Under this class we would arrange, 
 1st, the cellular system ; 2d, the nervous system, which comprehends 
 two orders, viz. A, the involuntary or ganglial order of nerves, or the 
 system of the great sympathetic, and B, the voluntary order of 
 nerves; 3d, the muscular system, which also embraces two orders, A, 
 the involuntary order of muscular fibres, B, the voluntary order of 
 muscular fibres ; 4th, the vascular system : this system has four orders, 
 viz. A , the arterial order of vessels ; B, the capillary order ; C, the 
 venous order ; D, the absorbent vessels, including a, the lymphatics, 
 and b, the lacteals. 
 
 IV. ELEMENTARY SOLIDS OR FIBRES. 1st, the cellular fibre ; 
 2d, the muscular fibre ; and 3d, nervous corpuscles and fibres. 
 
 Proceeding synthetically, we may arrange all the solids of which 
 the animal body is composed after the following manner: 
 
 CLASS I. ELEMENTARY ANIMAL SOLIDS. 
 
 The cellular fibre. The nervous fibre. 
 
 The muscular fibre . 
 
 CLASS II. SECONDARY OR COMPOUND ANIMAL SOLID& 
 ORDER I. GENERAL SYSTEMS. 
 
 The cellular system. The nervous system. 
 
 Including the adipose tissue. A. The involuntary or gan- 
 glial order of nerves, or 
 system of the great sym- 
 pathetic. 
 
 B. The voluntary order of 
 nerves.
 
 OF THE COMPOUND SOLIDS. 541 
 
 The muscular system. The vascular system. 
 
 A. Involuntary muscles. A. Arterial vessels. 
 
 B. Voluntary muscles. B. Venous vessels. 
 
 C. Absorbents. 
 
 a. Lymphatic absorbents. 
 
 b. Lacteal absoi bents. 
 ORDER II. PARTICULAR TEXTURES. 
 
 Mucous textures. Serous textures. 
 
 Erectile textures. Fibrous textures. 
 
 A. The fibrous. 
 
 B. Fibro-serous membranes. 
 
 C. Fibro-cartilaginous textures. 
 
 D. The dermoid textures. 
 
 Glandular textures. Corneous texture. 
 
 Cartilaginous textures. A. The epidermoid. 
 
 Osseous textures. B. The pilous. 
 
 CLASS III. ASSOCIATED OR COMPLEX ANIMAL STRUCTURES. 
 ORDER I. ORGANS OF NUTRITION. 
 
 Digestive organs. Organs of absorption and circulation. 
 
 Organs of respiration and Organs of secretion and excretion, 
 assimilation. 
 
 ORDER II. ORGANS OF RELATION. 
 Organs of sensation. Organs of voluntary motion. 
 
 ORDER III. ORGANS OF REPRODUCTION. 
 Organs of generation in both sexes. 
 
 Dr. Craigie* has lately given a different enumeration of the simple 
 tissues, which he describes in the following order: filamentous or 
 cellular tissue, including cellular and adipose membrane, artery and 
 vein, with the capillary and erectile vessels ; lymphatic vessel and gland ; 
 nerve, plexus, and ganglion ; brain ; muscle ; white fibrous system, in- 
 cluding ligament, periosteum, and fascia; yellow fibrous system, includ- 
 ing the yellow ligaments ; bone and tooth ; gristle or cartilage ; fibro- 
 cartilage ; skin ; mucous membrane ; serous membrane ; synovial 
 membrane ; compound membranes, as the fibro-mucous and fibro- 
 serous ; and the peculiar matter which forms the glandular organs, f 
 
 * Elements of General and Pathological Anatomy, Edinburgh, 1828. 
 
 -f- In the account given by Dr. Craigie of the various arrangements of the 
 animal textures proposed by anatomists, he has quoted the one proposed by us in 
 the first edition of our notes, but, by mistake, has attributed it to M . Richerand, 
 whose classification is in every respect different, if indeed it may be considered as 
 an attempt at classification at all.
 
 542 
 
 OF SENSIBILITY AND CONTRACTILITY. 
 
 (NOTE D. 'Seep. 18.) 
 
 Sensibility. The phenomena classed by the author under this 
 property of animal life, at p. 19 and 20, are evidently referrible only to 
 organic contractility, with which all classes of animals are endowed, 
 and which, in the lowest orders and in some vegetables, assume the ap- 
 pearance of sensibility. In these, however, we have no reason to infer 
 the presence of sensibility, merely because they contract under the in- 
 fluence of a stimulus ; for the contraction may take place without the 
 existence of this property, from the effect produced by the stimulus 
 upon the organisation of the contracting part. Indeed, we cannot 
 suppose that sensibility is present where the parts generally observed to 
 be instrumental in its production are not found to exist : a sensation 
 cannot be supposed to be produced where there neither is an organisation 
 suitable to receive, a channel to convey, nor an organ to perceive an 
 impression. We should, therefore, limit this term to those phenomena 
 which the author arranges under that of perceptibility. 
 
 With this limitation, sensibility may be called the function of sen- 
 sation, and a property peculiar to the animal kingdom. The sensations 
 are, derived through the medium of the senses and of the nerves, which 
 are distributed to certain parts of the body, and which communicate 
 with the encephalic centre. On this centre the existence of sensibility 
 chiefly depends ; the ramification of its nerves, or the subordinate por- 
 tions of it, being also parts of the apparatus requisite, but not giving 
 rise to this property. As we ascend in the scale of creation, and as we 
 perceive the senses and the organs of volition in more intimate relation 
 with this nervous mass the encephalon, so we find sensibility be- 
 coming more perfect, until in man it reaches an extent greatly sur- 
 passing that in which we observe it in any other animal. 
 
 In man, and perhaps in the more perfect animals, the modes of sen- 
 sibility seem to vary. These modes may, however, be divided into two 
 conditions, as they are more or less active ; namely, conscious or active 
 sensibility, and incoriscious or passive sensibility : the former relates to 
 those impressions, either from within or from without, which give rise to 
 perceptions or ideas; the latter to those that are frequently produced 
 upon the senses and upon the ramifications of the cerebral nerves, and, 
 owing either to habit or the want of due attention to them, are not per- 
 ceived by the mind. In this latter mode of sensibility, the organ re- 
 ceiving, and the channel conveying the impression, perform their offices ; 
 but the mind either is not, at the time when the impression is made, in 
 a state to receive it, or receives it so imperfectly, from its weakness or its 
 transient nature, as not to give rise to consciousness. This mode does not
 
 OF .SENSIBILITY. 543 
 
 necessarily imply a difference in the degree of sensibility, but the con- 
 dition in which this property exists, owing either to its being more ex- 
 cited by other impressions, or to its being exhausted at the time when 
 the impression is made. This condition is one to which the highest 
 manifestations of sensibility as well as the lowest may be occasionally 
 subject : it is, however, merely a relative mode of this property ; and the 
 relation subsists entirely between the state of the cerebral organ which 
 perceives, and the force and duration of the impression made upon the 
 organ of sense. Thus, when the sensibility is actively occupied with a 
 particular object, and an impression is made at the same time upon a 
 different organ from that through which the perception with which the 
 mind is engaged was conveyed, the second impression may affect the 
 senses in an evident manner, and even so as to influence volition, yet 
 we may be unconscious of its operation, and no active perception may 
 result from it. If, however, the second impression be stronger or more 
 vivid than the first, or if, from various other circumstances, it should 
 excite the cerebral functions, active sensibility or consciousness is the 
 result. 
 
 As sensibility, according to this view of the subject, is, in its active 
 state, a term merely expressive of consciousness in the wide range of 
 this very generally diffused faculty of the nervous system ; and as this 
 faculty is evidently dependent upon this system, especially on that more 
 complex part of it which holds relation with surrounding objects; and, 
 also, as we have no reason to attribute the possession of this part of the 
 nervous system to the very lowest orders of animals, particularly to the 
 class radiate, so we must conclude that, although sensibility is a 
 property of animal life, its higher grades are not possessed by all animals. 
 It may be also stated, that active sensibility, being considered as ex- 
 pressive of the consciousness of the whole class of sensations, and of all 
 the intellectual and moral operations, varies in its extent throughout 
 the animal kingdom, according as those manifestations are more or less 
 numerous and perfect. How far the passive mode of sensibility, or that 
 unattended by consciousness, may be a property of the lowest orders of 
 animals, is difficult to say. We may, however, infer, that as this con- 
 dition of sensibility may take place without an active exertion of this 
 property in the highest animals, so it may result from a less perfect 
 endowment of sensibility in the lower ; and as this mode may require a 
 less complex apparatus for its production, inasmuch as its relations are 
 more simple, so it may be possessed by animals whose organisation and 
 manifestations do not permit us to conclude that they are capable of 
 evincing sensibility in its more perfect and active conditions. The 
 relations which this form or mode of sensibility holds with the numerous 
 instincts of animals, must be evident to all who consider the subject. 
 The relations, however, which evidently subsist between that form of
 
 544 APPENDIX. 
 
 sensibility called organic sensibility by Bichat, and the animal instincts, 
 are much more numerous, more intimate, and more apparent. 
 
 Organic sensibility refers to those sensations which are produced in 
 different degrees of intensity', oWing to the existence of certain con- 
 ditions of those viscera which are immediately subservient to the preser- 
 vation of the individual and the species to nutrition and reproduction, 
 and which are not immediately subjected to the influence of volition. 
 The conditions of the parts exciting sensibility are very various, and are 
 the result of irritations arising from the presence of a stimulus, of un- 
 natural actions supervening in particular systems or textures, and of the 
 deficiency of that stimulus or influence to which particular viscera have 
 become accustomed. Many of the changes preceding this class of sen- 
 sations seem to interest, in the first instance, the ganglial class of 
 nerves; but, owing to the intimate relation subsisting between this 
 part of the nervous system and the voluntary or sentient part, the im- 
 pression or change is propagated to the brain. This is the only essential 
 difference which exists between this and the other forms of sensibility. 
 It is the brain which perceives in them all ; and although stimuli, or 
 the defect of stimuli, may give rise to certain phenomena possessing the 
 characters of the higher manifestations of this property in the organs 
 appropriated to the preservation of the organic system, independently 
 of the sensorium, consciousness, or the more perfect form of sensibility, 
 cannot form part of the results. 
 
 Organic sensibility may be active or passive it may or it may not be 
 attended with consciousness ; and even the unconscious mode of it may 
 indirectly impel to action, or give rise to many of the manifestations 
 or instincts which characterise the lower animals, owing to the ganglial 
 centres, either from their organisation or connexions, or from both, 
 performing a greater extent of function than usually falls to their share. 
 If, therefore, the passive form of organic sensibility may propel to 
 action without consciousness, or the sensorial sensibility being excited, 
 in these animals, we may also account in the same manner for many of 
 the instinctive functions being performed when we cannot trace them to 
 the influence of a cerebral organ. Of all the conditions of sensibility, 
 the active organic form is the least under the control of the mental 
 powers. It also, in all its modes of existence, more intimately interests 
 the existence of the individual than the other forms of sensibility, 
 organic sensibility involves a feeling in all its active manifestations in- 
 stinctive o"f life or death. 
 
 From this it will be readily seen how close a connexion exists be- 
 tween organic sensibility and the animal instincts : it does not belong 
 to our plan to trace the connexion in all its relations. 
 
 Of sensibility generally we may observe that, in the human species, 
 it is very variable ; in some persons it is very much exalted, in others
 
 OF CONTRACTILITY. 545 
 
 very obtuse. It is vivid in early life and in youth ; after the age of 
 manhood it gradually diminishes ; as old age advances, it decreases 
 rapidly ; and in persons who have attained a greater age, it is present 
 in the lowest grade in which we find it in the species. 
 
 Contractility is essentially a vital phenomenon, and is the result of 
 a change in the relative position of the molecules composing the solids 
 of a living body. This property may be divided into the following 
 grades, commencing with the lowest, it being the most generally dif- 
 fused throughout nature : 
 
 1. Insensible organic contractility, or that usually denominated tone 
 or tonicity. This grade of contractility is not confined to the animal 
 kingdom ; it is a property of vegetables, and of animals not possessed 
 of a heart. It is diffused throughout the tissues. The vascular system 
 possesses it in the most eminent degree; and it may be viewed as the 
 result of the vital influence with which the structures are endowed : it 
 is more or less perfect as the vital energy is perfect, and it disappears 
 with the extinction of this principle. It is a property of the tissues and 
 of the vessels, which is more or less exerted in all the vital operations 
 in the circulation, the secretions, nutrition, and absorption. The gan- 
 glial or organic class of nerves seems to be instrumental in its produc- 
 tion and preservation in the animal kingdom. 
 
 2. Sensible organic contractility or irritability is that inherent pro- 
 perty of contraction which exists in all muscular and in some other 
 textures. It is excited by the application of a variety of irritants. It 
 seems to depend upon the ultimate distribution of the nervous substance 
 to these parts, and chiefly upon the nerves proceeding from the ganglia. 
 
 Both these species of organic contractility seem to result from one 
 species of influence, with which animal bodies are endowed they are 
 the proximate result of vitality, and merely differ from each other owing 
 to the intimate structure of the parts in which they are seated, and to 
 the extent to which each of the parts evincing their presence is supplied 
 with ganglial ramifications. 
 
 3. Cerebral contractility is the contraction occasioned by the will in 
 voluntary muscles. It takes place only in such muscular parts as have 
 nerves proceeding from the encephalon, or rather from the medulla ob- 
 longata and spinal chord, terminating in their structure, and is the 
 result of this conformation and connexion with these large nervous 
 masses. 
 
 The first and second species of contractility result from the ganglial 
 distributions and influence, the third from the superaddition of the 
 nerves of voluntary motion. 
 
 Whilst, therefore, sensibility, in its more perfect grades, is the 
 
 N N
 
 546 APPENDIX. 
 
 function of the sensations, is chiefly confined to certain parts and tex- 
 tures of the body, and is dependent upon the part of the nervous 
 system of which the encephalon is the centre, contractility -exists 
 throughout the whole animal structures, although in different grades, 
 and is, with the exception of the third species or grade of its existence, 
 entirely independent of sensibility and volition ; contractility is a 
 general expression of life, sensibility of the higher functions only of 
 this principle. 
 
 OF SYMPATHY. 
 
 (NOTE E. See pp. 3234) 
 
 Baglivi attributed the sympathies to membranous connexion ; Bor- 
 deu to the cellular tissue ; Willis and Vieusens to the agency of the 
 nerves ; and Whitt and Broussais chiefly to the brain. Rega divided 
 the sympathies into those of sensibility and those of contractility a 
 division which has much to recommend it. Bichat offered some very 
 excellent observations on the relations subsisting between them and the 
 different parts of the nervous system ; but, although these observations 
 were calculated to lead to a more correct arrangement of the sympathies 
 than had been formerly offered, it has not come to our knowledge that 
 any has appeared founded on a better basis than that indicated in the 
 observations of Bichat. 
 
 Injthe note at p. 34, we suggested that the sympathies should be 
 arranged into the reflex and the direct ; the former arising through the 
 instrumentality of the sensorium, the latter taking place independently 
 of it, through the means of the ganglial nerves, and chiefly of those 
 which are distributed to the blood-vessels, and which form communicat- 
 ing chords between the viscera. 
 
 With a view to the illustration of the latter class of sympathies, viz. 
 those which are direct, and chiefly consist of the sympathetic actions of 
 organic life, we shall offer a few remarks. 
 
 When it is considered, that the ganglial nerves alone supply the 
 blood-vessels and the secreting organs and surfaces ; that they accom- 
 pany these vessels to the utmost limits of their ramifications ; that they 
 communicate very freely with each other, and with their chief centre, 
 the semilunar ganglion ; that they give rise to numerous plexuses, 
 which render the connexion between them still more intimate ; and that 
 they hold a close relation with the rest of the nervous system, through 
 means of communicating nerves; the mutual dependence of action 
 between the chief organs .of the body, in health and in disease, may be 
 easily explained. If, moreover, it be granted that the most important vital 
 phenomena, as digestion, assimilation, circulation, secretion, animal heat, 
 generation, &c. (see the Note on the functions of the ganglial system,}
 
 OF ORGANIC SYMPATHY. 547 
 
 in short, that life itself, with all those manifestations of it now particu- 
 larised, and which have been usually called organic, results from the 
 influence exerted by this part of the nervous system, through the in- 
 strumentality of the vessels upon the fluid they contain, and in some 
 measure reciprocally by this fluid upon these nerves ramified in the 
 parietes of the vessels, and upon the ganglia themselves, through 
 which it must of course circulate, the agency of this system in the 
 production of the class of sympathies under consideration must be 
 evident. From this view of the subject, and from taking into account 
 the modifying operation of similar textures, the related action of 
 various organs, and, under certain circumstances, the combined in- 
 fluence and re-action of the sensorium, the numerous relations and 
 connexions of healthy function and of disordered action may be more 
 satisfactorily traced. 
 
 When one organ or system of parts is excited to increased action, 
 or when its operations are diminished or obstructed, we perceive all the 
 other parts of the system which communicate with it through the 
 medium of the ganglial system, experiencing a modification of their 
 functions, the action of one or more organs having always an evident 
 relation to the kind and degree 'of action going on in the other. In 
 these cases the relation is sufficiently manifest; but the kind and 
 degree of it may vary very greatly between different organs. And the 
 relations may be of the following sorts, as the vital energies distributed 
 throughout the system are affected in degree or in kind, or in both 
 ways at the same time. 
 
 I. Organic sympathies, in which the vital energy of the system 
 evinces various modifications in degree and distribution, but in which 
 it is not changed in kind. + 
 
 1. Related actions may be characterised by a due proportion or a 
 healthy degree of the vital forces of the whole system ; but, owing to 
 the application of an exciting cause to one organ or part, or to two or 
 three organs, these forces may be greatly increased in them ; as, how- 
 ever, the healthy or medium quantity of the vital forces of the body is 
 not supposed to be exceeded, there consequently must be a diminution 
 of these forces throughout the other parts of the system,* in proportion 
 to the increase in the excited organs. 
 
 * When the natural functions of one organ are simply excited, without being dis- 
 eased, the functions of other organs with which it holds communication, by means of 
 the ganglial nerves, undergoes a relative degree of change, for the excitement of a 
 viscus is merely an exaltation of its vitality ; and, as we exalt the vital actions in one 
 or more departments of the entire series, we diminish them throughout the rest in 
 an equal proportion ; the excitement being frequently greater or less in some parts, 
 and the diminution more or less confined to others. 
 
 If, for the sake of illustration, we suppose the vital energies of the system to be 
 equal to 50 ; and, through means of the organic or ganglial nerves to be distributed
 
 548 API'ENDIX. 
 
 In this order of sympathies there are three relations to be observed, 
 which actually more or less obtain and constitute the essence of the 
 subject, or the actual condition of^the animal functions under consi- 
 deration : 1st, the relation may respect the increased actions subsisting 
 
 as follows ; to the stomach and intestines, 7 ; to the heart, vascular system, and 
 lungs, 8 ; to the brain and voluntary nerves, 7 ; to the liver, spleen, and pan. 
 creas, 6 ; to the generative organs, 3; to the urinary apparatus, 4 ; to the 
 surface of the body, 3 ; to the rest of the body, 1 1 ; we may consider that it is 
 duly proportioned. But if, owing to the application of certain excitants to one or 
 more organs, as to the stomach and intestines, we exalt the proportion bestowed on 
 these to 13, we shall consequently find the brain and voluntary nerves possessing 
 only 5 ; the heart, vessels, and lungs 7 ; the urinary organs 3 ; the surface of the 
 body 2 ; and tire rest of the body experiencing the loss of the remaining one. 
 If, again, we excite the vital forces distributed to the heart and vascular system 
 until they amount to 16, we shall have a febrile condition of the system in its 
 simplest form, and all the other organs will suffer a diminution in proportion : the 
 stomach will only equal 4, and so on in proportion. But the vital forces of the heart 
 and blood-vessels may equal 16 ; and, owing to the arteries of the brain experiencing 
 an undue proportion of this increase, this organ may at the same time equal 10 ; or, 
 instead of this increase falling to the lot of the cerebral vessels, those of other viscera 
 may be similarly augmented, whilst those of the remaining organs may be propor- 
 tionally diminished : in such cases we have a less simple result; but, nevertheless, 
 the increase of the circulating functions is followed by an equal diminution of the 
 secreting. Viewing the sympathetic connexion of function in another direction, we 
 shall suppose that the excited state of vital action takes place in secreting organs : in 
 this case the nutritive and other animal operations are diminished in an equal 
 degree. Or we shall suppose that the excitement commences in the capillaries of an 
 organ, from the presence of an irritating cause; that, owing to these vessels being 
 supplied with ramifications of the same order of nerves which supply the heart and 
 vascular system generally, the excitement extends more or less throughout this 
 system ; and that, in consequence of the continuity of this order of nerves, and 
 their very frequent reticulations and inosculations, not only do the heart and arteries 
 experience the excitement produced at a part of the extreme circumference, but the 
 whole body suffers a relative degree of derangement, and hence evinces all the 
 phenomena of sympathetic fever. Thus, the capillaries of a particular organ are 
 excited ; the excitement extends more or less generally throughout the vascular 
 series, and the nutritive and secreting functions are diminished in proportion as the 
 actions of the heart and arteries are increased. Many collateral views of this sub- 
 ject may be adduced, and many of its connexions traced, as well as various modifying 
 influences, both in and out of the body, appreciated all tending to establish the posi- 
 tion, that it is chiefly to the ganglial nerves we ought to attribute the manifold phe- 
 nomena of related action which we observe in the animal economy. At this place we 
 have only considered one of the genera belonging to this class of sympathies, namely, 
 that which comprehends the most simple of the related actions those which super- 
 vene in the system without an increase or diminution of the whole amount of the vital 
 energies with which the body is endowed. The other kinds of related function have 
 been pointed out in the above arrangement of this class of sympathies, and we 
 cannot farther allude to them here ; indeed, it would be much beyond our limits to 
 consider fully the different kinds of sympathy in their manifold relations ; we have 
 illustrated one more particularly, because of its importance, and of its having been 
 very generally overlooked.
 
 OF ORGANIC SYMPATHV. 349 
 
 in two or more organs ; 2d, it may be viewed between the increased 
 functions of one part and the diminished functions of another ; and 3d, 
 it may regard the diminished functions observed in those parts which 
 do not participate in the excitement ; the relation being most imme- 
 diate in the first, and least so in the third of these forms. 
 
 2. The sympathetic or related actions may be attended with a dimi- 
 nution of the sum of the vital energies throughout the system. In this 
 case the different relations pointed out above may nevertheless exist, or 
 one or two of them only may be remarkable ; the chief difference here 
 being that the sympathies of this order are generally induced by agents, 
 which, while they diminish the entire sum of vital energy, act more 
 decidedly upon particular organs or systems of parts. 
 
 3. The sympathetic operations may be characterised by a some- 
 what greater amount of the vital energies of the whole body. In this 
 order of sympathies the three relations particularised above also subsist; 
 for although the entire sum of vital actions may be greater than what is 
 usually bestowed on the system, it may be so much increased in some 
 organs as to be greatly diminished in others. This condition of func- 
 tional sympathy seldom continues long, until it subsides to the first, or, 
 from exhaustion of the vital energies, to the second order just now 
 particularised. ,-.,, 
 
 II. Organ-c sympathies in which, in addition to various modifica- 
 tions in degree and distribution, the vital energy of the system suffers 
 a change in its kind, 
 
 1. Sympathetic actions in which the general amount of the vital 
 forces is natural in degree, but vitiated or modified in kind, the relation 
 being evident 1 st, mutually between those functions which are in- 
 creased; 2d, between the actions which are augmented and those 
 which are diminished ; and 3d, between those only which are di- 
 minished. 
 
 2. Sympathies in which the entire sum of vital energy is both re- 
 duced in degree and modified in kind; the relation between its distri- 
 bution in the various organs being the same as just now pointed out. 
 
 3. Sympathies in which the amount of the whole vital energy is 
 both heightened in degree and modified in kind. In this order, the 
 distribution and the relations to which such distribution gives rise are 
 the same as already adduced. 
 
 The application of this classification, and of the views which it 
 embraces, to medicine, must appear evident.
 
 APPENDIX. 
 
 OF HABIT. 
 
 (NOTE F. .See p. 36.) 
 
 In the note at p. 36, we have said that the effects of habit upon 
 our voluntary organs are very different from those which result from its 
 influence on the viscera of organic life. This difference is, however, 
 chiefly in degree; for as "sensibility, there is every reason to suppose, 
 from its most vivid state of existence, until it merges in contractility, 
 and in its various modes of manifestation, differs chiefly in degree,- and 
 as it is bestowed in some one mode and degree to all the organs of the 
 body, although it be more particularly limited to one of their tissues, 
 and also as the influence of habit is chiefly exerted upon the sensibility 
 of the system, so it follows that it modifies more or less all the animal 
 and organic functions, although it acts in the most manifest manner on 
 those organs which are in the closest relation with the sensorium or 
 functions of the brain. Thus the stimulus which excites the action of 
 the sensorium produces a much less intense effect by repetition ; but 
 the repeated employment of the same food, or of the same purgative, 
 does not materially less excite the action of the viscera to which they 
 are respectively applied. As the influence of habit, therefore, is chiefly 
 on the sensibility of the system, so it follows, that when the organic 
 sensibility of the involuntary organs is repeatedly excited, it is then that 
 the diminished effects of the excitant upon them are most manifest 
 that the more the sensibility of our organ is called forth, the more is 
 the influence of habit remarkable. Those stimuli, however, which act 
 chiefly and the most exclusively on the contractility of the textures, 
 and those organs whose actions principally consist in the exertion of 
 this principle of life, have their operations the least impaired by re- 
 peated employment; indeed, in many instances those organs have 
 their functions increased and rendered more perfect by frequent ex- 
 ertion. Hence, independently of degree, is the chief difference in the 
 influence of habit on the voluntary and involuntary organs of the 
 body. 
 
 OF INFLAMMATION. 
 (NoTEG. Seep. 46.)' 
 
 As the author has taken occasion to give his opinion respecting the 
 proximate cause of inflammation, we shall follow his example, and 
 briefly illustrate the view which we entertained of it, and published in 
 a thesis on rheumatism in 1815, and more recently in a paper on the 
 functions of the ganglionic nerves, contained in the London Medical 
 Repository for May 1822. On these occasions we defined active in-
 
 PHYSIOLOGICAL RELATIONS OF INFLAMMATION. 551 
 
 flammation to be the result of a morbidly excited state of the ganglial 
 nerves supplying the capillaries of the affected part or a derange- 
 ment arising from the unnaturally exalted condition of these nerves, on 
 which the functions of the capillaries depend. 
 
 One of the chief inquiries respecting its nature and physiological 
 relations, is, whether this exalted or excited state of these nervous 
 fibrilse is one of simple excitement or no, whether the natural func- 
 tions of these fibrilae be merely increased above their healthy or 
 ordinary pitch, or whether or no they are also otherwise changed. In 
 the definition, we said morbidly or unnaturally excited, thereby indi- 
 cating that the functions or influence of these nerves are not only 
 simply increased, but also increased differently from what we observe 
 in a healthy part, from the application of a stimulus, both as respects 
 duration and kind of action. 
 
 1. As respects the duration of this exalted state. In the vascular 
 phenomena displayed by blushing, or by the application of a gentle 
 stimulus, the effects soon subside after the removal of the exciting cause ; 
 because the nervous influence exerted on the capillaries is simply in- 
 creased without the mode or habitude of operation being changed. 
 But before we can farther explain the duration of excitement, we must 
 secondly inquire into its kind. 
 
 2. When a stimulus or irritant is applied to a part, its action seems 
 to be first upon the ganglial fibrilae supplying the capillaries. The 
 vital influence of these fibrilee being excited, the actions of the capil- 
 laries which they supply are consequently increased. There is, how- 
 ever, every reason to suppose, that the increase of this influence is not 
 simple, that it is not only changed in degree, but also modified in 
 kind. The irritant seems to impress the nervous fibrilse of the part, or 
 of the system more generally, in such a manner as to prevent it from 
 returning to its natural state for a very considerable time, or even at 
 all ; the excited action is induced, it continues, and the longer it con- 
 tinues, the less is it disposed to return to its healthy condition. But 
 wherefore does the excitement continue? To this may we answer, 
 either because the irritating or exciting cause continues to operate by 
 its actual presence, or more frequently because the impression made by 
 it, while it changed the degree of nervous influence, also modified its 
 state of existence and kind of operation on the vessels themselves and 
 the fluids which they contain. It is, therefore, owing to the impression 
 of the causes or changes thereby produced in the kind as well as 
 degree of influence exerted by the nervous fibrilee, that we are to 
 impute, 1st, the duration of the excitement; and, 2dly, the different 
 phenomena which capillary derangements or inflammations present. 
 A few of these phenomena we shall particularise.
 
 552 APPENDIX. 
 
 1 . Uneasy sensation, from its lowest degree until it amounts to acute 
 pain. Uneasy sensation alone may be considered one of the primary 
 phenomena following the operation of the exciting cause ; or, rather, 
 one of the manifestations characteristic of that kind or state of excite- 
 ment or deranged influence of the nervous fibrilae, forming the first 
 series of the changes induced in the affected part ; and it may be far- 
 ther kept up by the subsequent changes induced in the capillaries by 
 the disordered state of the nervous influence, of which state it is itself 
 one of the manifestations. When the uneasy sensation amounts to 
 pain, it may be owing either to the degree of change with which the 
 influence of the nervous fibrilse, and through it the action of the capil- 
 laries, are imbued, or it may arise in consequence of the ganglial system 
 of nerves communicating the disordered excitement which has com- 
 menced in them to these cerebral nerves with which they are associated 
 in the textures : for, as we have already stated, the ganglial nerves 
 being plentifully distributed to the capillary vessels in every part and 
 tissue of the body, must consequently communicate freely, and come 
 closely in contact, with the sentient or voluntary class of nerves, espe- 
 cially in those textures which are abundantly supplied with them. By 
 means of ttiis connexion, the excited function of the former class is 
 very probably communicated to the sentient extremities 6f the latter 
 class, and their sensibility, being thus excited, is still farther increased 
 by the derangement of the capillaries which the former nerves induce. 
 But this phenomenon of inflammation may not result exclusively in the 
 c ne manner or in the other. It may take place in both ways in the 
 same part, or in the one or the other more or less partially. In those 
 viscera which are imperfectly supplied with the cerebro-spinal nerves, 
 the first alternative may be adopted. Indeed, in these textures very 
 considerable inflammation may exist without any other modification of 
 pain than uneasy sensation being felt; whereas in the other organs, 
 whose supply of cerebro-spinal nerves is considerable, the second ex- 
 planation may be entertained ; whilst in some viscera both modes of 
 accounting for this morbid manifestation may be resorted to. But 
 whatever manner of explanation should be adopted according to the 
 distinction just now stated, it ought not to be forgotten, that this par- 
 ticular manifestation of disease is modified throughout its manifold 
 grades by the texture of the part affected, and by the exciting and 
 other causes to which it is indebted for its existence and progress. 
 
 According to this view of the subject, it will be observed, that we 
 consider the pain of inflammation as originating in, or caused by, the 
 condition of the particular influence or function performed by the 
 fibrilse or the ganglial system of nerves, as a state of these nerves 
 producing deranged action of the capillaries to which they are distri-
 
 PHYSIOLOGICAL RELATIONS OF INFLAMMATION. 553 
 
 buted, and exciting or otherwise disturbing the sensibility and functions 
 of the other class of nerves with which they become associated in many 
 of the textures ; whereas the most acute pains, those which are not 
 necessarily attended with inflammation, and very seldom give rise to it, 
 as those accompanying tic douloureux, trismus, the various forms of 
 spasmodic diseases, and some other painful disorders which it is un- 
 necessary to designate, originate exclusively in the fibrilse of the 
 cerebro-spinal nerves. This appears to be an important and funda- 
 mental distinction in pathology, and one which we have not adopted 
 without much reflection and pathological research. It accounts for a 
 very frequent phenomenon, namely, the presence of the most violent 
 pain when there are no appearances of inflammation either during its 
 existence or after its subsidence. It shews also that, with the exception 
 of the countenance and one or two other parts, excitement commencing 
 in the cerebro-spinal or sentient nerves has but little immediate influ- 
 ence upon the capillary circulation ; and it also points out, that what- 
 ever influence these nerves may possess over the circulation and the 
 vital phenomena allied to it, it is only by means of exciting the ganglial 
 nerves distributed to the structure of the part, and to the blood-vessels 
 ramifying in it, that any such influences can be exerted. This, it might 
 be shewn, were it necessary to speculate respecting final causes, is a pro- 
 vision requisite to the preservation of the textures, and consequently of 
 the animal body; for if the circulation throughout the different tex- 
 tures and organs were immediately under the dominion of the sentient 
 nerves, and removed from that of the ganglial, we should have not only 
 all the phenomena which more strictly belong to it, but all the vital 
 manifestations of nutrition, secretion, animal heat, &c. which are under 
 the influence of the ganglionic system, subjected to continual derange- 
 ment from the various impulses of the will and the passions. As these 
 functions, on which the preservation of the individual depends, are un- 
 der the dominion of another and a less fluctuating influence, they are 
 less endangered by the numerous causes of change by which they are 
 constantly surrounded, and with which they hold frequent communica- 
 tion. But, although the functions which are immediately vital are 
 those that belong to the province of this system, they may be acted 
 upon either generally or partially, through the medium of the nervous 
 system of relation or of animal life, which system has its own particular 
 functions to perform, and these occasionally exert no mean influence 
 over those of the former class. 
 
 2. Redness, or the injection of the capillaries with red blood. This 
 phenomenon has created much discussion. It would be foreign to our 
 plan to enter at this place upon the different arguments which have 
 been entertained respecting it. We shall merely state our own opinion 
 as to its nature.
 
 554 APPENDIX. 
 
 The vital influence of the ganglia! class of nerves is, as we have 
 just now stated, morbidly increased in the affected part, especially as 
 respects these nerves distributed more directly to the capillaries. We 
 observe that on every occasion in the animal economy, when the vital 
 actions of capillary vessels are increased, the vessels themselves become 
 larger, more fully injected, and circulate a larger quantity of blood. 
 Now, if we allow that an increase in degree forms one part of the 
 change in the vital influence bestowed on the capillaries by the ganglial 
 nerves, it therefore follows that a proportionate change in the calibre of 
 the minuter vessels should result from such increase, as usually does on 
 those occasions when it supervenes in a natural manner. 
 
 In short, that one of the changes constituting the acute stage of in- 
 flammation is an excited state of the vital influence, distributed by the 
 ganglial nerves to the capillaries of the part : an excited state of this 
 influence always increases the action and calibre of the capillaries ; 
 therefore, both these conditions must be increased whenever an excited 
 state of the vital influence constitutes a part of the primary derange- 
 ment. The capillaries during -acute inflammation are in every respect 
 in a similar state to that evinced by erectile tissues when they are 
 excited. 
 
 But it has been argued, that when an inflamed capillary is viewed 
 in a microscope, the current of blood in it is slower, instead of being 
 quicker than natural. This, however, arises, as we have stated on 
 another occasion, from the inflamed capillary vessel admitting a greater 
 number of red globule?, and thus giving rise to the optical illusion of 
 their slower motion, when in fact they actually move much quicker 
 than when the vessel admits a single globule at a time, and when the 
 entire space between each globule moving in the vessel can be seen. 
 Another objection has been urged in support of the hypothesis of re- 
 laxation or debility of the vessels, namely, that the exposed capillaries 
 contract upon the application of an irritant ; but so do all irritable 
 parts, and so do all parts to a greater or less extent which are supplied 
 with the vital influence. In these experiments it has not been con- 
 sidered, because it was unfavourable to the hypothesis, that the irritant 
 acts in a two-fold capacity ; it excites irritable fibres to contraction, 
 and it constringes the structure of the part. These experiments also 
 appear generally to have been performed under circumstances of dis- 
 order, and at a period when the inflammation was passing into that 
 stage which is constituted by a greater or less exhaustion of the in- 
 creased influence which formerly actuated the capillaries. 
 
 3. Increase of the animal heat in an actively inflamed part. We 
 have contended, in another place, that animal heat is the result of the 
 vital influence of the ganglial nerves upon the vessels and the increased 
 quantity of blood circulating through them in a given time, and that
 
 PHYSIOLOGICAL RELATIONS OF INFLAMMATION. 555 
 
 the heat of the whole body or of a single part has a.n intimate relation to 
 the degree of influence which this system of nerves exerts, especially 
 that part of it supplying the blood-vessels, either as respects the body 
 generally, or as regards the part more particularly affected. If this 
 position be granted, it cannot be denied that the augmented heat in 
 inflammation is derived from the same source, namely, the increased 
 influence, on the vessels of the affected part, of that particular system of 
 nerves on which the production of animal heat chiefly depends, toge- 
 ther with the circumstance of the augmented diameter of the capillaries 
 allowing a greater quantity of blood to pass through them ; the nervous 
 influence enlarging these vessels, or occasioning an erectile state of 
 them, and this state soliciting an afflux of blood to the affected part. 
 (See the Note on the functions of the ganglionic system of nerves.) 
 
 From this it will be seen, that we consider inflammation, in its 
 various forms and stages, to originate in, and to depend upon, the 
 altered kind and degree of influence which the ganglial system of nerves 
 exerts on the capillaries of the part; that whenever this influence is 
 greater than natural, the action of the capillaries is greater than natural, 
 and whenever it is below the healthy condition, these vessels are equally 
 deficient in a requisite degree of action ; that the kind of influence is 
 changed as well as the degree of influence; and that, as inflammation 
 originates with the nerves supplying the capillaries of the diseased part, 
 it may be considered as a lesion of the functions of these nerves, affect- 
 ing the condition of the capillary vessels, and occurring more frequently 
 in those tissues which are the least supplied with an additional and a 
 compensating influence from the other parts of the nervous system : 
 hence the reason that inflammation is very seldom seen in the muscular 
 structures to which the cerebral nerves are so plentifully distributed, 
 and hence the probable cause that it so frequently attacks cellular 
 parts, or those which are essentially cellular in their nature and are 
 supplied with ganglial nerves only. 
 
 At this place we have merely considered a few of the physiological 
 relations of acute inflammation, in a brief and an imperfect manner. 
 The other points connected with this subject which might be discussed, 
 but which are more strictly pathological, are 1st, the different cha- 
 racters of acute inflammation, according to the textures in which it is 
 seated; 2d, the stages of inflammation in relation to the individual 
 tissues, down through their numerous grades until they reach the 
 lowest ; 3d, inflammations in which the influence, bestowed on the ves- 
 sels by the ganglial nerves is more or less exhausted or destroyed ; 
 4th, the state of the venous capillaries and absorbents in the different 
 stages and grades of inflammation ; 5th, the varying phenomena which 
 this species of derangement presents, according as it is modified by 
 constitutional peculiarities ; 6th, the different manifestations of in-
 
 5 5 6 APPENDIX. 
 
 flammation arising from the nature of its exciting causes, &c. These 
 and other relations of this fundamental and most important part of 
 pathology, will be considered in an extended manner on another 
 occasion. 
 
 OF THE GANGLIAL OR GREAT SYMPATHETIC SYSTEM 
 OF NERVES. 
 
 ( No T E H. See pp. 4954. ) 
 
 It would be incompatible with the limits of these notes to point out 
 the anatomical peculiarities and connexions of this important system, 
 or even to enter upon a lengthened discussion of its functions. We 
 shall therefore confine ourselves to the statement of the general propo- 
 sitions at which we arrived on the latter part of the subject, and which 
 were contained in a paper on the functions of the ganglionic system of 
 nerves, read at the Medical Society of London in 1820. 
 
 It may be proper to remark, that these inferences were deduced 
 from numerous dissections of individual subjects belonging to the dif- 
 ferent classes of animals, and from several experiments made in order 
 to ascertain the extent of function which this system of nerves performs. 
 The observations made on these occasions we shall soon have an oppor- 
 tunity of describing in a particular manner. 
 
 1. The ganglial class of nerves is to be found throughout every 
 order of the animal creation, commencing with the lowest, the Radiates, 
 and ascending to the highest. 
 
 2. The ganglial nerves are the only part of the nervous system with 
 which the lowest orders of animals are provided. 
 
 3. As we ascend the scale of creation, another class of nerves is 
 superadded, namely, the encephalic, with which the ganglial nerves are 
 connected. In the higher animals possessing only the ganglial nerves, 
 we perceive the ganglion placed on or near the oesophagus, gradually 
 assuming more and more the characters of a brain, and becoming more 
 evidently connected with organs of sense. We also observe the ner- 
 vous chords between the ganglia arranging themselves more and more 
 in the manner of a spinal marrow, as the locomotive organs become 
 more distinct from those of nutrition ; thus rendering the steps of 
 gradation between the animals provided only with the lowest or 
 simplest form of nervous ganglia, and those possessed both of ganglia 
 and of an animal or voluntary system of nerves, almost imperceptible. 
 
 4. The nerves which are given off from the encephalic mass and 
 from the spinal marrow evince different characters as soon as these 
 parts of the nervous system become distinct from the ganglia ; and 
 even in progress towards the fullest distinction which they ultimately
 
 OF THE GAXGLIAL SYSTEM OF NERVES. 557 
 
 attain, the difference between both the classes of nerves becomes still 
 more manifest. 
 
 5. In all the more perfect animals, the ganglia and their various 
 distributions, as far as they can be traced by the senses, even when 
 aided by powerful glasses and minute dissection, are entirely different 
 from the nerves derived from the brain and spinal chord, in their texture, 
 colour, consistence, mode of ramification and distribution ; and they 
 supply very different organs and textures from those to which the 
 cerebral and spinal nerves are distributed. 
 
 6. Not ojily in the lowest order of animals may the ganglial nerves 
 be traced before the voluntary or sentient class of nerves come into 
 existence, but also in the embryos of the higher animals the ganglia 
 may be distinguished before any traces pf a spinal marrow or of a brain 
 can be perceived. 
 
 7. The ganglial nerves cannot be supposed to originate in either < 
 the brain or spinal marrow 1st, because they are observed in the 
 lowest animals, which possess neither brain nor spinal chord ; 2dly, be- 
 cause they may be distinguished in embryos before either the one or 
 the other nervous mass can be traced ; and 3dly, because they are 
 never wanting in the foetal state, whereas not only have the brain and 
 spinal marrow been individually wanting, but the same foetus has been / 
 found entirely without both. 
 
 8. The difference between this class of nerves and those of animal 
 life, is not evinced only by their respective appearances, by the general 
 distribution of the former throughout the animal creation, by the history 
 of the embryal foetus, and by the phenomena exhibited by monsters; 
 but it is also apparent from the very different effects which are observed 
 in them, as respects both the living and dead subject, on the application 
 of various excitants and re-agents.* 
 
 * The difference between these nerves is very remarkable on the application of 
 galvanism; for, whilst we found that the voluntary nerves could be excited with 
 a few plates, two hundred could produce only a slightly perceptible effect upon the 
 parts more immediately supplied with fibrilae from the semilunar ganglion. When 
 galvanism was applied to this ganglion itself in the recently killed animal, but little 
 appreciable effect was produced either on the vessels with which it is so intimately 
 connected, or upon the stomach and upper portion of the small intestines. In the 
 majority of instances, however, these parts seemed to be in a more contracted state 
 while under the galvanic influence. When the influence of the battery (of two 
 hundred plates) was directed upon the semilunar ganglion of a young cat, it evinced 
 symptoms of pain and distress, and several irregular contractions of the diaphragm 
 supervened. The effects of galvanism were also tried on some of the other ganglia, 
 but they evinced no appearance of being oppressed by it in the dead subject, and in 
 the living the result was equivocal. On these occasions we experienced great 
 difficulty from the want of proper assistance. We propose, however, to repeat and 
 to extend these experiments ; and we expect eminent coadjntorship in their per- 
 formance, and the assistance of a very powerful galvanic battery.
 
 558 APPENDIX. 
 
 9. The points of dissimilarity just now instanced evidently shew 
 that the ganglia and their numerous distributions form an independent 
 system in the animal economy ; and that as one thing cannot be said 
 to form a part of another thing from which it is essentially different, so 
 the ganglia and their ramifications cannot be supposed to form a part 
 of the nervous system of animal life',* or that which presides over the 
 intellectual and locomotive functions. 
 
 10. The independence of the ganglial system may be farther de- 
 monstrated in many of the lower animals, and in the young of the 
 most perfect animals, for in these both the brain and spinal chord may 
 be destroyed gradually; and, provided the' function of respiration be 
 not entirely put a stop to, the functions of circulation and secretion 
 will still be continued. 
 
 11. That*. the independence of this system, and the extent of the 
 peculiar influence which it exerts in the animal economy, is farther 
 proven in the most perfect animals, by the effects of disease upon the 
 brain and spinal marrow, either of which may be destroyed to a very 
 great extent, and those organs only which they supply be deprived of 
 their functions, while those viscera which receive the ramifications of 
 the ganglial system will continue to perform their actions without 
 evincing much disorder, unless that part of the nervous mass which 
 actuates the contraction of the respiratory muscles become involved in 
 the disease. 
 
 12. The ganglia supply with fibrilse all the organs of digestion, 
 assimilation, circulation, and secretion. 
 
 13. The heart is chiefly supplied with nerves coming directly from 
 this class of nerves. 
 
 14. These nerves form a closely reticulated envelope around the 
 arteries of the thorax and abdomen, and around the vena portcec they 
 may be traced in the larger branches of arteries of the extremities and 
 of the head, until they reach the brain itself. 
 
 15. The arteries throughout the body, and indeed all the other 
 parts of the vascular system, receive nerves directly from no other 
 source than from the ganglia. 
 
 1 6. The same system supplies, in a demonstrable manner, all the 
 involuntary muscles, and it seems to send fibrilse to several of the 
 voluntary muscles, especially to those about the centre of the body. 
 It is also liberally distributed to all the secreting glands and sur- 
 faces.* 
 
 If, therefore, these nerves are every where demonstrable in the centre of the 
 system, and even throughout its radius, until we arrive at the superficies or 
 extreme parts of the body, where it may be supposed that they must elude, from 
 the nature of their organisation, the detection of the senses, it cannot be con- 
 trary to the uniform operations of nature, and to the many analogies she presents,
 
 OF THE FUNCTIONS OF THE GANGLIAL SYSTEM. 559 
 
 17. From the manner in which the ganglial nerves invest the arte- 
 ries proceeding into the brain, and reasoning from analogy, we infer 
 that they accompany the arteries throughout the substance of this 
 viscus, as in other organs of the body, and that they influence its 
 vascular functions in a similar manner. 
 
 18. The chief origin or centre of the ganglial system is generally 
 situated, in all the higher orders of animals especially, about the middle 
 of the body, and, under the name of the semilunar ganglion, it sends 
 off' branches which form plexuses; these present modified characters, 
 as respects their external appearance and conformation, in their course 
 to the different organs which they supply. 
 
 This central ganglion more immediately supplies the organs of 
 digestion, chylifaction, and circulation, where the expenditure of the 
 vital influence is greatest, and sends communicating branches to the 
 subordinate ganglia and plexuses. 
 
 19. The. external characters of the ganglia and of their plexuses 
 and ramifications vary considerably in different situations, both as re- 
 spects their colour, their external form, and internal structure. 
 
 20. The subordinate ganglia, while they seem to receive a reinforce- 
 ment of vital influence from the centre ganglion, modify that'tnfluence, 
 and generate an accession to it, suitable both in kind and in degree to 
 the functions of the organs which they are destined to actuate. 
 
 21. This class of nerves send off" and receive chords of communi- 
 cation between the brain and its subordinate organs, and between the 
 spinal marrow and its distributions : this seems to give rise to a reci- 
 procal communication of influence between the organs of nutrition, &c. 
 and those of relation, and a mutual dependence of function, which is 
 more intimate and apparent as we rise in the scale of creation, the 
 independence of the former class of functions becoming more evident 
 as we descend, and the younger the animal is as we ascend the 
 scale. 
 
 to infer that they are distributed to the extreme ramifications of the arteries, 
 upon whose trunks and larger branches they are readily demonstrable. And if 
 they are also shewn to exist in some voluntary muscles, may they not be considered 
 to be present in all, bestowing upon these muscles peculiar energies, the nerves of 
 animal life producing the functions which usually result from this class of nerves, 
 in addition to those arising from the involuntary influence or vital energy which / 
 these muscles derive from the ganglia and their distributions ? 
 
 It may be mentioned, that, consistently with the opinions we entertained re- 
 specting the independence of, and extent of the functions performed by, the ganglia 
 and their distributions, that we assign the terms ganglial system, organic system 
 
 of nerves, vital system of nerves, synonymously ; and we use the terms cerebro- 
 
 spiiial system of nerves, voluntary nerves, and sentient system, also synonymously. 
 To this-there may be some objections, but as we did so in the original paper, we wish 
 jiot to alter it.
 
 560 APPENDIX. 
 
 22. The extent and mode of communication between different parts 
 of the voluntary nerves and the ganglia and their distributions vary 
 very considerably. 
 
 23. As this class of nerves are so entirely different in their appear- 
 ance, structure, properties, and mode of distribution, and as they sup- 
 ply very different organs from those % which receive the encephalic class 
 of nerves, so it may be inferred that they perform essentially different 
 functions, although these functions, in the higher animals more parti- 
 cularly, are in close relation with those of the rest of the body. 
 
 24. As it is demonstrated, that the ganglial or vital nerves supply 
 the heart ; that they surround and are ramified in the arteries through- 
 out their distribution; that no part of the vascular system receives in a 
 direct manner any voluntary nerves ; and as it is reasonable to suppose 
 that this provision does not exist without accomplishing important pur- 
 poses in the animal economy, and as the fibres of involuntary muscles 
 are evidently supplied from the same source ; and, farther, as we can- 
 not suppose, 'conformably to the laws of nature, that the bare coats of 
 the vessels, and particularly of the arteries, without such a provision 
 could be possessed of any vital properties, so we infer that all the 
 vital phenomena which .the vascular system exhibits throughout the 
 body are under the direct influence of this class of nerves. 
 
 . 25. The distribution of these nerves around the arteries, and the 
 manner in which their fibrilae penetrate the coats of these vessels, seem 
 to evince that they not only impart to them whatever vital properties 
 they may possess, but that they moreover produce those changes on the 
 blood to which it is subject whilst flowing in the vessels, and many of 
 those phenomena which this fluid presents soon after it has been taken 
 from the body. 
 
 26. It is also reasonable to suppose, that the influence exerted by 
 this system on the capillaries, arrd the additional influence which its 
 ramifications bestow on the substance of the viscera, combine to pro- 
 duce the secretions in secreting organs and surfaces, and nutrition 
 throughout the textures of the body. Hence, that the varied pheno- 
 mena displayed by the blood itself, by the functions of digestion, secre- 
 tion,* assimilation, &c. result from the condition of the influence which 
 
 * No experiment instituted with the intention of shewing the influence of the 
 nerves given off from the brain and spinal chord upon secretion, can prove the reality 
 of such inriuence; because these orders of nerves are not ramified upon the vascular 
 system, nor do they even supply the capillary vessels. This is a wise provision ; 
 for if the heart and blood-vessels were directly under the influence of the voluntary 
 nerves in any of its divisions, this system would be constantly deranged by it, and 
 vascular disease be incomparatively more frequent and fatal. Such experiments, 
 were they instituted with the utmost precaution, could prove no more than has been 
 shewn by those of Dr. Phillips and M. Legallois, which, at most, evince that the
 
 OF THE FUNCTIONS OF THJK GANGLIAL SYSTEM- 561 
 
 this system, in its centre and distributions, is instrumental in generating 
 in the vessels and fluids which they contain. May not a vital influence 
 or atmosphere, as it were, be produced from the extreme fibrilse of this 
 system, or between them and the coats of the capillary vessels, which 
 influence, whatever may be its state of existence, impresses the fluid cir- 
 culating in these vessels in a manner which produces different effects, 
 according to its excess or defect, or according to other modifications to 
 which it may be subject, in health and disease, owing to the numerous 
 causes of changes to which it is exposed ? 
 
 27. The separation from the blood of the materials which supply the 
 waste of the textures, or give rise to their growth, is the office of this 
 system, which imparts its influence to, and operates through the me- 
 dium of the vascular system. 
 
 28. The vital manifestations of veins and absorbents (with the ex- 
 ception of the vena portse) arise from the distribution of the system of 
 nerves to the minute arterial capillaries supplying their parietes, and to 
 the adjoining. textures ; and, probably, from the distribution of minute 
 fibrilse to their tunics an organisation which, although it cannot*be 
 demonstrated, may nevertheless exist, and thus the vital manifestations 
 of the venous system may more readily be explained. 
 
 29. The ganglial nerves sheathe the vena portae throughout its course in 
 the liver; and from the very abundant manner in which they supply 
 this particular vein, from the conformation of the vein itself both as 
 respects its coats and connexions with the texture of the liver and 
 with the other vessels, and from the character of the blood conveyed to 
 and from it, we conclude that it is through the vital influence bestowed 
 on the vena portse by the ganglial nerves, assisted by that belonging to 
 the other vessels and the texture of this viscus, that the changes induced 
 in the blood returned from the digestive canal and its allied viscera, 
 and containing a large proportion of absorbed materials, are produced ; 
 and that the secretion of the bile results from the same influence, partly 
 
 vital functions resulting from the ganglial or vital class of nerves may be influenced, 
 in the more perfect animals, by the destruction of apart of the nervous system with 
 which they have held, and with which they always hold, a more or less intimate 
 relation ; and that the same nerves which, during health, have conveyed a natural 
 stimulus to the vital activity of particular organs, may convey an artificial one ; 
 and when the natural stimulus or excitant is removed, or the subordinate function 
 annihilated, the operations to which it is requisite, in the highest animals, must 
 languish and ultimately decay. 
 
 Indeed it is only reasonable to suppose, that the ^voluntary nerves, as they 
 communicate with the organic or vital nerves, convey a natural stimulus or in- 
 fluence to the latter, which, if they were deprived of it, after its continued and 
 uninterrupted influx, the vital functions of the organs enjoying this additional 
 ' influence would necessarily languish, or even be overturned if the privation took 
 place suddenly and completely. If, however, it were brought about gradually, it 
 might be produced to a great extent, and in many animals completely. 
 O O
 
 562 Al'PEKDIX- 
 
 as a consequence of these previous changes, and partly, as its inde- 
 pendent act, exerted both upon the extreme ramifications of the vena 
 portee and of the hepatic artery, this secretion consequently proceed- 
 ing from both the kinds of blood contained by these vessels. 
 
 30. That this system of nerves, by means of the influence derived 
 from its principal and subordinate sburces and numerous distributions, 
 and exerted upon the vascular system, generates animal heat through- 
 out the body ; and that the production of animal heat takes place in a 
 manner analogous to the processes of nutrition and secretion.* 
 
 31. The state of animal heat, like other secretions, will be greatly 
 modified by the condition, both as respects kind and degree, of the 
 vital influence of the ganglial system, and by the state of the blood on 
 which this influence is exerted, which state will have a double opera- 
 tion in modifying the result.f 
 
 32. It appears probable, from the effects of several agents upon the 
 voluntary and other muscular parts, when applied immediately to the 
 ganglial or vital system of nerves, from the general distribution of this 
 system to the capillary arteries, and from the circumstance of its sup- 
 plying and actuating the involuntary muscles, that it also bestows its 
 proper influence upon those which are voluntary, and that thus it gives 
 rise in both to the phenomenon of muscular parts usually called irrita- 
 bility ; the different manifestations of this property, as it is displayed in 
 voluntary and involuntary muscles, resulting from the accessory supply 
 of the cerebro-spinal nerves which the former class of muscles receives. I 
 
 33. That the ganglial system appears to be productive of certain 
 obscure sensations or instinctive impulses (organic sensibility) which are, 
 by means of the communicating branches of nerves between this system 
 and the cerebro-spinal masses, propagated to the latter ; and from the 
 influence thev there excite, become the causes of several manifestations, 
 which more immediately proceed from this latter part of the nervous 
 system. 
 
 34. This operation of the ganglial system on the functions of the 
 cerebro-spinal system, is more remarkable when the former is influ- 
 enced by disease or by a stimulus which is unnatural either in kind 
 or degree ; or even when a natural excitant to which this system has 
 been accustomed is withheld, whether such excitant operates either 
 directly or indirectly, or in both ways, as the supply of food, &c. 
 
 * The experiments of insulating a limb by dividing all the voluntary nerves 
 and arteries excepting one arterial trunk, performed by Mr. Brodie, in order to 
 ascertain the effects produced upon the generation of heat in the limb, prove this 
 proposition, and could not fail of giving rise to what was actually observed. For 
 the ganglial or vital nerves supplying that vessel could not be completely detached 
 as long as any of the coats of the artery remained undivided. 
 
 f See the Note on Animal Heat. J See Note 1 1. of APPENDIX.
 
 OF THE FUNCTIONS OF THE GANGLIAL, SYSTEM. 563 
 
 35. The communicating; branches of nerves between the chief gan- 
 glia of the abdominal and thoracic cavities, whilst they are the medium 
 of communication between the ganglial and cerebro-spinal systems, in- 
 tercept or moderate, by means of the subordinate ganglia placed in their 
 course, the influences proceeding from the one system to the other. 
 Thus it is that the ganglia in the neck and chest moderate the influences 
 of the functions of the brain on the heart, and that no impulse of the 
 former can reach the latter but through the medium of the ganglia ; 
 and so little are the ganglia influenced by the operations and excite- 
 ments of the brain, that organic sensibility is only slightly produced by 
 them. If, therefore, the impulses of passion and volition produce but an 
 obscure effect upon the ganglia and their chief centre, it is not to be 
 wondered at that the galvanic influence, which must be very con- 
 siderable to equal the impulses of volition, should act comparatively in 
 a very slight and almost insensible manner upon this system. 
 
 36. The ganglia on the communicating branches between the in- 
 ternal ganglia and the spinal chord, intercept the impulses proceeding 
 through this latter channel ; and while they thus moderate the opera- 
 tions of both the brain and spinal marrow upon the internal ganglia, 
 they seem to generate an influence suited to the intermediate place 
 which they hold. 
 
 37. Irritations of the ganglial system appear to act in a slight and 
 obscure manner upon the voluntary organs, through the medium of the 
 communicating or conducting branches between this system and the 
 spinal chord ; and, but for the ganglia on their course, the irritations of 
 the former, and the impulses of the latter and of the brain, would re- 
 ciprocally act in a manner that would be much more marked, and even 
 in a way that would be injurious to the whole body. 
 
 38. The influence of the ganglial on the cerebro-spinal system is more 
 marked as the developement and functions of the former system pre- 
 dominate, as in the lower animals and in the foetus of those which 
 belong to the highest orders.* 
 
 * The following outline exhibits a view of the extent of influence which we 
 .have attributed to the ganglionic system : it formed a part of the contents of a 
 treatise on the anatomy, physiology, and pathology of the ganglionic class of nerves, 
 &c. the publication of which was commenced in the London Medical Repository, 
 but was discontinued in order that it might appear in a separate and extended 
 form. 
 
 " Parti, comprehends the following sections: 1. A description of the organs 
 generally called nervous ganglia 2. An examination into the distribution of their 
 ramifications or fibrilse, as far as that has been determined, either by my own or 
 by the observations of others. 3. Reasons against the usually received opinion, that 
 they constitute a part of the cerebral and spinal nerves ; and proofs of their form- 
 ing a distinct system from the brain, spinal chord, and nerves proceeding from 
 these sources 4. An account of the connexion existing between the ganglia or
 
 564 APPENDIX. 
 
 39. As the ganglia of the great sympathetic form an independent 
 system, presiding over certain functions which are essentially vital, con- 
 sequently they may be viewed as the system and seat of organic life,, 
 and may therefore be denpminated, the vital system of nerves, whose 
 centre is the semilunar ganglion.* 
 
 their ramifications and the nervous system properly so called, and the mode by 
 which that connexion is effected. 5. An inquiry respecting what viscera and 
 textures they supply. 6. Proofs, from the history of the species, and from com- 
 parative anatomy, that they form the first effort of organisation, and are instru- 
 mental in the production of the other textures 7- Remarks respecting their 
 state during the formation, progress, and decline of the animal 8. Inferences 
 from the preceding inquiries. 
 
 " Part II. The functions of the ganglia considered 1. As they regard the 
 vascular system, on which they are chiefly ramified A. Proofs that the ganglia 
 are the primary and chief source of the heart's action. B. Their power over the 
 arterial and capillary systems inquired into, and the irritability of the latter class of 
 
 vessels contended for, and shewn to be derived from this cause C. Evidences of 
 
 their influence over the secreting viscera and textures, a. On the gastric secretions 
 and functions, b. Their control over the secretions from mucous and other sur- 
 faces, and from follicular glands, c. Over the biliary and pancreatic secretions. 
 d. Over the secretions and functions of the urinary organs. D. Their influence on 
 the mass of blood circulating through the heart and blood-vessels, a. As regards 
 the changes induced in this fluid during respiration, b. As respects the phenomena 
 which it displays after having been drawn from an artery and vein in the general 
 circulation, during various states of the system, c. The power of these organs in 
 the production of animal heat 2. The functions of these organs, viewed in con- 
 nexion with the muscular fibres of involuntary motion 3. The probability of their 
 being the chief source of irritability contended for, and the varying characters of 
 this principle explained, as it is displayed in the different muscular textures and 
 capillary vessels 4. The influence of the brain and spinal chord upon the opera- 
 tions of the organs under consideration, viewed, a. In respect to the manner 
 and extent in which the former affect the contractions of the heart, b. As they 
 (the voluntary nerves) may affect the capillary circulation of a part, and proofs of 
 their limited influence over the vascular ramifications, c. With regard to the small 
 extent of power which the brain and spinal chord can exert over the functions of 
 digestion, unless through the medium of the ganglions 5. A general view of 
 the phenomena to which the ganglial ramifications give rise, when reinforced by 
 .the nerves properly so called. 6. The manifestations to which they give rise in 
 the inferior classes of the animal creation 7- The functions of the ganglions, as 
 
 they regard the generative process, a. In the male. b. In the female 8. Their 
 
 influence in the formation and nutrition of the textures, and in the progress and 
 decay of the animal, considered 9. The effects produced on different animals by 
 
 the application of certain substances to the expansion of these organs. 10. The 
 
 consideration, that the manifestations essentially vital are the result of these organs, 
 entertained, argued for, and explained, from the inferences deduced from the fore- 
 going sections 11. A general view of the doctrines contained in this part of the 
 treatise." Lond. Med. Repos.for May 1822. 
 
 * Violent blows or contusions on the epigastric region, when they do not imme- 
 diately destroy the individual subject to them, depress in a very remarkable manner 
 the vital energies of the system. The animal heat is uncommonly diminished, the 
 surface is cold and pale, the pulse slow and scarcely perceptible, and the breathing
 
 EFFECTS OF I,OXC.-PROTRACTEJ> ABSTINENCE. 365 . 
 
 40. It seems probable, from the circumstance of a separate ganglion 
 or plexus, or both, being generally assigned to each important secreting 
 or animalising organ, that the centre or source of vital influence does 
 not supply the whole vitality distributed by the ganglial ramifications 
 to the individual organs and textures ; but that the vital influence pro- 
 ceeding from this centre is reinforced by that which is produced by the 
 subordinate ganglia, and is not only reinforced, but modified by them, 
 and by their distributions in the various organs, so as to give rise to the 
 specific difference of function which each performs ; and that the vital 
 manifestations of particular ganglia are still farther modified by the 
 communicating branches between them and the cerebro-spinal system, the 
 extent of modification being relative to the extent to which the nerves 
 of this latter system either communicate with, or contribute to supply 
 or to form, the individual subordinate ganglia.' 
 
 Lastly. The vital influence being thus produced from the centre of 
 the body, and reinforced and modified by subordinate ganglia, allotted 
 to the individual organs according to their functions, is propagated 
 along the distributions of the system, on which it depends and is in- 
 herent, throughout the whole body. 
 
 APPENDIX 
 
 CHAPTER ON DIGESTION. 
 
 THE EFFECTS OF LONG-PROTRACTED ABSTINENCE. 
 (NOTE I. See p. 82.) 
 
 THE effects of protracted abstinence on the human subject are well 
 illustrated by the following facts : During the famine which desolated 
 certain parts of France in the year 1817, especially during the months 
 of April, May, and June, when the miserable inhabitants had exhausted 
 their stock of provisions, and when they were reduced to live on her- 
 baceous vegetables only, as wild sorrel, nettles, patience, succory, 
 thistles, the tops of beans, the sprigs of young trees, &c., M. Gaspard* 
 observed that a general serous diathesis prevailed, or universal anasarca 
 of the cellular membrane, without ascites, jaundice, or any organic 
 
 feeble and very slow. An analogous effect, in some respects, is produced by con- 
 cussion of the semilunar ganglion, as that which follows concussion of the brain : 
 in the ffirmer, the vital or organic actions are either exhausted or destroyed; in the 
 latter, the animal or voluntary operations only are suspended. 
 * Journ. de Physiol. Eper. No. III.
 
 566 APPENDIX. 
 
 lesion of the liver, or of any of the abdominal viscera. Many women 
 experienced an interruption of the catamenia ; and a reference to the 
 register of births subsequently in the communes which suffered from 
 the famine, shewed that the number of conceptions was less by more 
 than one-half during the three calamitous months of that year than 
 during the same months of the preceding and following years. 
 
 During these months many assuaged their hunger by eating snails, 
 of which an incredible number was destroyed ; but those who largely 
 partook of them experienced a state of stupor, analogous to that pro- 
 duced by belladonna. 
 
 A tradesman, impelled by a succession of misfortunes, retired to a 
 sequestered spot in a forest in Germany, and there resolved to starve 
 himself to death. He put his determination in force on the 15th of 
 September, 1818; and was found eighteen days after still living, although 
 speechless, insensible, and reduced to the last stage of debility. A small 
 quantity of liquid was given him, after which he expired. By his side 
 was found a pocket-book and pencil, the former containing a daily 
 journal of bis state and sufferings up to the 29th of September, four 
 days before his death. He had constructed a little hut of bushes and 
 leaves. On the 17th of September (the second day) he complained 
 of suffering from cold ; on the 18th he mentioned having suffered from 
 intolerable thirst, to appease which he licked the dew from the surround- 
 ing vegetables. On the 20th he found a small coin, and with difficulty 
 reached an inn, where he purchased a bottle of beer ; the beer failed to 
 quench his thirst, and his strength was so reduced, that he took three 
 hours to accomplish the distance, which was about two miles. On the 
 22d he discovered a spring of water, but though tormented with thirst, 
 the agony which the cold water produced on his stomach excited vo- 
 miting and convulsions. The 25th made ten days since he had taken 
 any food but beer and a little water. During that time he had not 
 slept at all. On the 26th he complained of his feet being dead, and of 
 being distracted by thirst ; he was too weak to crawl to the spring, and 
 yet dreadfully susceptible of suffering. The 29th of September was the 
 last day on which he made a memorandum. No dissection of his body 
 was made.* 
 
 A criminal, called Viterbi, determined, on the 2d of December, to 
 starve himself to death, in the prison of Bastia, where he was confined. 
 During the three first days of the attempt, he felt himself progressively 
 tormented by hunger. He manifested no debility during these three 
 days, nor any irregular muscular movement ; his ideas continued sound, 
 and he wrote with his usual facility. From the 5th to the 6th of De- 
 cember the much more grievous suffering of thirst succeeded insensibly 
 to hunger. Thirst became so acute on the 6th, that without ever 
 
 * Journal der Practisch : Hcilkunde, &c. C. W. Hufeland, Mara, 1819.
 
 
 EFFECTS OF l.ONG-PKOTKACTED ABSTINENCE. 567 
 
 deviating from his resolution, he began 1 to moisten his lips and mouth oc- 
 casionally, and to gargle with a few drops of water, to relieve the burning 
 pain in his throat ; but he let nothing pass the organs of deglutition, being 
 desirous not to assuage the most insupportable cravings, but to mitigate 
 a pain which might have shaken his resolution. On the 6th his phy- 
 sical powers were a little weakened ; his voice was, nevertheless, still 
 sonorous, pulsation regular, and a natural heat equally extended over 
 his whole frame. From the 3d to the 6th he had continued to 
 write ; at night several hours of tranquil sleep seemed to suspend the 
 progress of his sufferings : no change was remarkable in his mental 
 faculties, and he complained of no local pain. 
 
 Until the 10th, the thirst had become more and more insupportable : 
 Viterbi, however, merely continued to gargle, without once swallowing 
 a single drop of water; but in the course of the 10th, overcome by 
 excess of pain, he seized the jug of water which was near him, and 
 drank immoderately. During the last three days, debility had made 
 sensible progress, his voice became feeble, pulsation had declined, and 
 the extremities were cold. He, however, continued to write ; and 
 sleep each night afforded him a few hours ease. 
 
 From the 10th to the 12th the symptoms made a slight progress. 
 His constancy never yielded an instant : he dictated his journal, and 
 afterwards approved and signed what had been written agreeable to 
 his dictation. During the night of the 12th the symptoms assumed a 
 more decided character; debility was extreme, pulsation scarcely 
 sensible, his voice extraordinarily feeble ; the cold had extended itself all 
 over his body, and the pangs of thirst were more acute than ever. On 
 the 13th, the unhappy man, thinking himself at the point of death, 
 again seized the jug of water and drank twice, after which the cold 
 became more severe ; and, congratulating himself at the approach of 
 death, he stretched himself on the bed, and said to the gendarmes who 
 were guarding him, " Look how well I have laid myself out." At the 
 expiration of a quarter of an hour, he asked for some brandy : the 
 keeper not having any, he called for some wine, of which he took four 
 spoonsful. When he had swallowed these, the cold suddenly ceased, 
 heat returned, and he enjoyed a sleep of four hours. 
 
 On awaking (on the morning of the 13th), and finding his powers 
 restored, he fell into a rage with the keeper. During the two following 
 days, he resisted his inclination to drink, but continued to gargle 
 occasionally with water. During the nights he suffered a little from 
 exhaustion, out in the morning found himself rather relieved. It was 
 then he composed some stanzas. On the 16th, in the morning, his 
 powers were nearly annihilated, pulsation could hardly be felt, and his 
 voice-was almost wholly inaudible ; his body was benumbed with cold, 
 and it was thought that he was upon the point of expiring. At 
 10 o'clock he began to feel better, pulsation was more sensible, his
 
 568 APPEXDIK. 
 
 voice strengthened, and heat again extended over his frame ; and in 
 this state he continued during the whole of the 17th. From that day 
 until the 20th he only became more inexorable in his resolution to die. 
 
 During the 19th, the pangs of hunger and thirst appeared more 
 grievous than ever ; so insufferable indeed were they, that, for the 
 first time, Viterbi let a few tears escape him ; but his invincible mind 
 instantly spurned this human tribute. For a moment he seemed to 
 have resumed his wonted energy, and said, in the presence of his 
 guards, " I will persist ; my mind shall be stronger than my body ; my 
 strength of mind does not vary, that of my body daily becomes more 
 weak." A little after this energetic expression, which shewed the 
 powerful influence of his moral faculties over his physical necessities, 
 an icy coldness again assailed his body, the shiverings were frequent 
 and dreadful, and his loins, in particular, were seized with a stone 
 coldness, which extended itself down his thighs. 
 
 During the 19th, a slight pain at intervals affected his heart, and, 
 for the first time, he felt a ringing sensation in his ears. At noon on 
 this day, his head became heavy; his sight, however, was perfect, and 
 he conversed almost as usual, making some signs with his hands. On 
 the 20th, he declared to the gaoler and physicians, that he would not 
 again moisten his mouth ; and feeling the approach of death, he 
 stretched himself on the bed, and said, " I am prepared to leave this 
 world." Death did not this time betray his hopes: on the 21st he 
 was no more. Until the day of his death, this man regularly kept his 
 journal. The delivery of it to his friends was refused.* 
 
 OF DIGESTION. 
 
 (NOTE K. See p. 95, et seq.) 
 
 I. Of digestion in the stomach. M. Lallemand has drawn the 
 following inferences from his observations and experiments on di- 
 gestion : 
 
 " 1. That, if it be true that alimentary substances the most per- 
 fectly animalised contain the most nutritive matter, it does not thence 
 follow that they are the most rapidly digested. 
 
 " 2. That, on the contrary, the process of digestion is more long 
 and laborious, as, in a given volume, the aliment contains more 
 nutritive matter, and vice versd, 
 
 " 3. That the aliments do not escape from the stomach in the 
 order in which they are introduced, for it is not those which are first 
 altered by digestion that pass the first: it is those, on the con- 
 trary, which, containing least alimentary matter, are most refractory 
 to the digestive powers." 
 
 Agreeably to the inferences stated, (in note H. of the App. pp. 556, 
 
 * From the Corsican Gazette.
 
 OF HUMAN RUMINATION. 569 
 
 557,) we consider, that whatever may be the order in which the in- 
 gesta pass the pylorus into the small intestines, the digestive process 
 in the stomach, and, indeed, throughout the alimentary canal, is more 
 immediately the result of the vital influence with which the stomach 
 and intestines are endowed, than of the solvent properties of the 
 gastric juice. We, however, by no means, would be understood to 
 deny that these properties are requisite to the process ; we only contend 
 that they are subordinate to the manifestation of vitality exerted by the 
 stomach, and that the vital influence of this viscus is chiefly concerned 
 in its performance. The digestive process, whether that part of it 
 which is performed in the stomach, or that which is accomplished by 
 the small intestines, appears to be essentially a vital process, whether 
 we view it in man or in any of the lower animals. Every theory, 
 therefore, which excludes its immediate operation, must be defective. 
 Conformably to this view, it must be supposed to vary in activity, 
 as, indeed, we actually find that it does, according to the state of the 
 vital influence with which the organs concerned in its accomplishment 
 are originally endowed, and according to the state and distribution of 
 this influence throughout the organs and textures at the time when 
 this process is going 'forward. We do not deny that the influence 
 which we impute to the stomach is one which is not intimately 
 connected with the gastric juices; on the contrary, we believe that 
 they are the medium through which it acts, in short, that, owing to 
 the abundant supply of nerves which this viscus receives, chiefly from 
 the ganglionic system, it possesses a considerable share of the vital 
 influence of the body; that this influence is chiefly exerted in giving 
 rise to its organic motions, and in producing its specific secretions ; 
 and that, from the circumstance of so large a proportion of its ganglial 
 nerves being distributed on its arteries, the juices which they secrete 
 or exhale are imbued with an emanation or some certain manifestation 
 of this influence, which is the principal agent in the digestive process. 
 Hence the relation between the states of this influence and the 
 quantity and-quality of the gastric juices, must be very intimate; and 
 it seems to be owing to this intimacy that the primary agent has been 
 hitherto overlooked in the more evident and grosser materials with 
 which it is allied, and by means of which it operates. The varying 
 conditions of the function of digestion in health and in disease, and 
 the close connexion between it and every manifestation of the body, 
 eminently support this view of the subject ; and, independently of the 
 direct evidence furnished by the very interesting experiments of Drs. 
 Wood and Sillar, of Liverpool, many collateral proofs may be adduced 
 in its behalf. 
 
 II. Of human rumination. The author has adverted to this
 
 570 APPENDIX. 
 
 subject in the text, (p. 101), in a very brief manner. As this affection 
 is more frequent amongst individuals apparently enjoying their usual 
 health than is generally supposed, and as many who habitually 
 ruminate consider it to be only a step of the digestive process, which 
 is certainly the truth as far as respects themselves, we shall enter 
 more fully into the subject, as it has more than once fallen under our 
 observation. 
 
 Under the usual circumstances, rumination commences from a 
 quarter of an hour to an hour and a half after a meal. Immedi- 
 ately upon the commencement of this act, a slight sensation of 
 fulness may be felt at the cardia, when the attention is particularly 
 directed to it, that leads to a deeper inspiration than usual. So soon as 
 the act of inspiration is completed, and while the muscles of the 
 glottis remain fixed, a bolus of the unchanged aliment rises rapidly 
 from the stomach with the first effort at respiration, at the moment 
 when the diaphragm has just relaxed and the re-action of the 
 abdominal muscles commenced. But expiration does not take place 
 until the alimentary ball has passed completely into the mouth, as the 
 glottis remains closed until then : upon this having taken place, 
 expiration is immediately effected ; and so rapidly does expiration 
 succeed to the regurgitation of the alimentary bolus, that the latter, 
 (unless when the attention is closely applied to the subject), appears as 
 part of the expiratory act. 
 
 The ruminating process is never accompanied at any time with the 
 smallest degree of nausea, nor any pain or disagreeable sensation. The 
 returned alimentary bolus is attended with no unpleasant flavour, is in 
 no degree acidulous, is equally agreeable, and is masticated with ad- 
 ditional pleasure, and with much greater deliberation, than when first 
 \ taken. 
 
 The whole of the aliments taken at any one meal is not returned in 
 order to undergo this process, but chiefly the part that has been 
 insufficiently masticated. 
 
 The more fluid portions are not always returned, unless along with 
 the more solid or imperfectly masticated parts. When, however, the 
 stomach is distended by a large meal, the fluid contents are frequently 
 returned, and subjected to this process. 
 
 This affection may be considered as being passively under the 
 control of the will ; and although it sometimes takes place when the 
 individual is nearly unconscious of the process, yet it never occurs 
 when the mind is incapable of being acted on by external impressions 
 received by the senses. Thus, if at any lime, from previous fatigue, 
 and the concentration of the organic nervous energy towards the 
 digestive organs, sleep be induced immediately after a full meal, this 
 affection does not take place; but flatulence, acrid eructations, &c.
 
 OF HUMAN RUMINATION. 571 
 
 usually supervene, and continue for some time, in consequence of the 
 vital energy and gastric juices being insufficient to the production of 
 the requisite changes on the ingesta retained in a state of imperfect 
 division. 
 
 With respect to the nature of human rumination, it appears 
 evident that it only takes place when the vital energy of the as- 
 similating organs is greatly diminished ; consequently, when the 
 activity of the stomach, both as it relates to its muscular action and 
 secreting functions, is equally lessened : this is apparent from the 
 circumstance, that aliments, if they be taken even in very moderate 
 quantity, are not properly digested by ruminating individuals when 
 they are retained without having been resubmitted to mastication. 
 Connected also with debility of the stomach, an increase of its 
 sensibility, which it derives from the distribution of the eighth pair of 
 nerves, seems to be present. Both these states of this organ render it 
 more necessary that the ingesta should undergo a perfect mastication 
 and thorough admixture of the salivary juices, in order to suit it to the 
 weakened functions of the stomach. 
 
 Under the circumstances of deficient vital energy of the stomach, 
 of increased sensibility, and diminished secretion, a small portion only 
 of food can be digested ; yet it is, nevertheless, generally taken in 
 considerable quantity by ruminating individuals. In this case, that 
 portion of it most favourable to the admixture having combined with 
 the gastric juices, and being, by the natural action of the stomach, 
 conveyed to the pylorus, the undigested portions, and those which 
 have been imperfectly masticated, must either remain at the cardiac 
 extremity, or be propelled there by the usual action of the viscus, 
 where they excite its organic sensibility, and, in consequence of 
 intimate nervous connexion, the co-operation of the muscles of 
 respiration, especially of the diaphragm and abdominal muscles, and 
 thus give rise to the ruminating process. 
 
 In its performance, the organic contractility of the stomach can do 
 no more than, by an elective process (soon to be explained), place the 
 aliments about to be returned in a situation, in respect to the cardia, 
 favourable to the excitation of the organic sensibility of this organ, and 
 to its ready regurgitation and propulsion along the ossophagus. As 
 soon as the demand is made upon the sensibility, by the situation of 
 the alimentary bolus, the par vagal class of nerves is excited to action, 
 and a full respiration is effected, as has been described. The in- 
 troduction of the bolus into the cardiac extremity of the resophagus 
 may be considered as effected by the ordinary contractility of the 
 stomach, perhaps sympathetically heightened at the moment by the 
 reactien of the abdominal muscles ; while, at the same time, the 
 diaphragm has just undergone relaxation, in which the cardia may,
 
 572 APPENDIX. . ' 
 
 from intimate nervous communication, also participate, and thus 
 facilitate the ascent of the alimentary ball in the oesophagus, which 
 immediately contracts behind it, from the irritation produced by its 
 passage, and the bolus is thus conveyed to the mouth. 
 
 That relaxation of both the diaphragm and cardiac extremity of the 
 oesophagus actually exists at the moment, although the glottis still re- 
 mains closed, appears confirmed, both by the period of the respiratory 
 , act at which this process, is produced, and by the circumstance that, 
 when any restraint is exercised over this affection, it is principally by 
 means of exciting the diaphragm to a frequent and continued action, 
 when the premonitory sensation is felt at the cardia. 
 
 The influence of the will appears to be requisite, since the process 
 is interrupted during sleep. But this influence is only passively en- 
 gaged in the production of the ruminating act, by bringing about the 
 ' co-operation of the respiratory organs. 
 
 The elective process exercised by the stomach in this affection is 
 similar to that which it exerts in periods of health, which may be con- 
 sidered as relative to the degree of digestive energy, and to the com- 
 parative states of comminution and insalivation in which the various 
 ingesta may enter the stomach. 
 
 During the process of digestion, contraction takes place irregularly 
 and in various situations in this organ, according as different portions of 
 the longitudinal or circular fibres may act : this operates in producing 
 a degree of arrangement in the aliments ; and the gastric juices com- 
 bine with the more soluble portion of the food, especially that situated 
 towards the mucous surface of this organ, and form the chyme, which 
 is conveyed by the varying organic contractility of the muscular coat 
 towards the pylorus ; while a successive and concentric stratum of ali- 
 ment comes in contact with this surface, and, if in a permeable state 
 from its previous comminution and admixture with the salivary juices, 
 is soon penetrated by the gastric secretions ; and even the central mass 
 not uVifrequently is obliged to yield its more fluid parts to the exterior 
 kyer, when there is a deficiency of fluids in the alimentary matters. 
 Heflce the not unusual necessity for drink that takes place as digestion 
 proceeds. In the course of this process, as it is the result of the healthy 
 functions of the organ, the chyme in contact with its mucous surface is 
 conveyed in a direction from the cardia to the pylorus. But, if the 
 propulsion of the digested contents towards this extremity of the organ 
 goes on faster than they can pass through into the duodenum, the accu- 
 mulation of chyme that consequently takes place in that direction tends 
 to throw back the less soluble portions towards the cardia ; where, ac- 
 cording to the state of the organ, they may produce cardialgia, acrid 
 eructations, or even rumination. 
 
 In the debilitated state of the stomach, and consequent deficiency
 
 OF THE PNEUMO-GASTRIC SERVES IN DIGESTION 573 
 
 of the secretions, digestion can be perfectly performed only when the 
 aliments are presented to it in small quantity, and in a favourable state 
 of complete comminution and intermixture with the salivary juices. If y 
 however, in this condition of the organ, the food is conveyed rapidly 
 into it, possessed of neither of these requisites, so as to produce sudden 
 distension, a reaction of this viscus upon its contents takes place; and 
 as the imperfectly masticated food constitutes the greater portion of 
 the ingesta, there is abundance present to be returned into the cardia and 
 to be regurgitated, while there is a deficiency of aliment in a fit state 
 to combine with, or to be operated upon by, the gastric juices ; but this 
 latter, when converted into chyme, is rapidly conveyed to the pyloric 
 extremity of the organ, by the reaction of the muscular coat, arising from 
 undue distension and the stimulus of solid contents. Thus, a double 
 effect is produced by the healthy organic contractility of this viscus, 
 when in a weakened state and yielding a diminished quantity of the usual 
 fluids, which state, indeed, may be considered as constituting this pecu- 
 liar affection, namely, the part of the aliment which is dissolved by 
 the gastric juices is conveyed towards the pylorus, whilst the tonic 
 action of the stomach, tending to diminish its capacity, pushes the less 
 comminuted and indigestible portions of food into the unresisting cardia, 
 whence they are returned, as we have described, in order to undergo a 
 second comminution and intermixture with the salivary juices ; after 
 which they are in a fit state to be conveyed to their destination' along 
 the mucous surfaces, with the juices of which they combine, and thus 
 permit a central portion of the mass to return and undergo a similar 
 process. 
 
 III. Of the influence ofthepneumo-gastric nerves in digestion. See 
 p. 113. The experiments of Dr. Philip, although they by no means war- 
 rant the inferences which he deduced from them, shew that the eighth 
 pair of nerves conveys the influence of the cerebro-spinal system J;o the 
 stomach, and reinforces and stimulates the vital energy bestowed on it 
 by the ganglial system. This conclusion is farther supported by the 
 experiments lately performed at Paris by MM. Breschet, Edwards, 
 and Vavasseur. The inferences which these physiologists have drawn 
 from their experiments are, 
 
 1st. Simple section of the two pneumo-gastric nerves in the region 
 of" the neck, without loss of substance, and without separating the cut 
 extremities, does not prevent digestion from taking place, but merely 
 retards it in an evident manner. 
 
 2dly. Section of these nerves with loss of substance diminishes con- 
 siderably, and much more than simple section, the digestive action of 
 the stomach, but it does not appear to abolish it completely.
 
 574 APPENDIX. 
 
 3dly. Section or destruction of a part of the spinal marrow, or 
 ablation of a portion of the brain, acts in the same manner on the 
 changes which the food undergoes in the stomach. 
 
 4thly. Narcotics, administered so as to produce coma, equally di- 
 minish the energy of the digestive powers. 
 
 5thly. It results, consequently, ttiat every thing which diminishes 
 the amount of nervous influence transmitted to the stomach, weakens 
 the digestive action. 
 
 6thly and finally. When digestion is almost completely suspended 
 by the section, with loss of substance, of the pneumo-gastric nerves, the 
 digestive action of the stomach may be re-established, and the food 
 contained therein be converted into chyle, by means of the galvanic in- 
 fluence, with almost as much rapidity, and as perfectly, at least in 
 appearance, as under ordinary circumstances.* 
 
 When the connexions of the different orders of nerves which supply 
 the stomach are considered, and the intimate relation consequently sub- 
 sisting between this organ and the centres to which these nerves re- 
 spectively belong, it cannot for a moment be doubted that the interrup- 
 tion of the channel through which this connexion takes place should 
 be followed by a deranged state of the functions depending thereupon. 
 Allowing that the stomach derives its chief and its more vital influence 
 from the ganglial system, and an additional and a modified influence 
 from the cerebro-spinal system, the latter exciting or otherwise in- 
 fluencing the former, and granting that respiration is requisite to the 
 energy of both, it surely cannot be for a moment doubted, that an in- 
 terruption either of the one or the other should occasion, owing both to 
 the defect of a requisite influence and to the injury done to the system 
 generally by the experiment, a very considerable derangement of the 
 functions of this organ. We perceive that slighter causes, such as those 
 mentioned at p. 113 of the text, will produce a much greater disorder 
 of the actions of the stomach than the formidable operation of division 
 of the eighth pair of nerves formidable not only as respects its effects 
 upon digestion, but as regards its influence on the function of respira- 
 tion and upon the body generally. Can it therefore be a matter of 
 surprise, that destruction of, or interruption to, a wonted and requisite 
 influence, should be followed by marked effects upon the organ which 
 such influence is destined to actuate? Because the influence conveyed 
 by the nerves from the cerebro-spinal system affects the functions of 
 the stomach, or an interruption to it disorders them, can it therefore be 
 logically concluded that this viscus derives its functions from that 
 source, and that none of them acknowledges any other origin ? Because 
 
 * Archives Generates de Mfdecine, 4out, 1823.
 
 OF THE PXEUMO-GASTKIC XERVES IX DIGESTION*. 575 
 
 these particular nerves are ready conductors of galvanism, and because 
 galvanism excites the natural actions of the digestive organs, ought it 
 therefore to be concluded, that the natural office of these nerves is to 
 convey and distribute this agent, or that the vital influence with which 
 these organs are endowed, is identically the same as it? We think 
 that no one can be justified in answering these questions in the affir- 
 mative, by the evidence which these experiments afford. 
 
 From a careful consideration of the phenomena which these experi- 
 ments furnished, and from the few experiments which we have made with 
 this active agent, we conclude, 1st. That the functions of the stomach 
 depend chiefly upon the supply of ganglial nerves, which its vessels, 
 muscular fibres, and secreting surface r receive. 2. That the pneumo- 
 gastric nerves convey the influence of the cerebro-spinal system to this 
 organ, which influence reinforces that which it receives from the gan- 
 glial system, or proves a stimulus to it. 3rd. That this latter influence 
 is more requisite to the perfect performance of the functions of the 
 stomach the older the animal is, and the higher we rise in our obser- 
 vations amongst the more perfect animals. 4th. That when this in- 
 fluence is interrupted, in a more or less complete manner, in its course 
 to the stomach, its place may be, in some measure, supplied by gal- 
 vanism, which seems to excite the proper or vital influence which the 
 organ receives from the ganglial system. 5th. That we have no proof 
 of galvanism acting otherwise in the process than as a stimulus to pro- 
 perties already possessed by the organ on which it acts, and that it acts 
 in those experiments through a medium to which the organ is habi- 
 tuated, and in a great measure dependent for a natural excitant. 6th. 
 That although galvanism excites the functions of the stomach for a time, 
 we have no evidence of its continued power in promoting them during 
 a protracted interruption of either the one species of nervous influence 
 or the other ; it even appears probable that the continued operation of 
 this agent, although, like other powerful stimuli, it at first actively 
 excites the natural functions of the part on which it acts, would, never- 
 theless, exhaust them, more especially if they were not uninterruptedly 
 supplied from their natural sources. 7th. That as we have no com- 
 parative trials of the effects of other powerful stimuli under similar 
 circumstances to those in which galvanism has been employed, con- 
 clusive inferences cannpt be drawn respecting the extent of influence 
 of that agent ; at least none that can oppugn the above positions ; 
 they may, and very probably they will, confirm them, and shew that the 
 activity of galvanism in exciting the animal operations merely results 
 from the properties of this agent enabling it to act, through channels 
 which convey a natural and a requisite influence, in a more energetic 
 ' manner than other excitants which we can employ in our experiments.
 
 576 APPEXDIX. 
 
 Reasoning, indeed, from what we already know of the properties of 
 galvanism, and from its operations upon inorganised matter, we should 
 be led to expect more energetic effects from it upon the animal system 
 than from any other agent which we have under our control. 
 
 OF VOMITING. 
 
 (NOTE L. See pp. 114116.) 
 
 Whilst we attribute the digestive process chiefly to the vital in- 
 fluence proceeding from the ganglial system, we do not overlook the 
 fact that that part of this system supplying the stomach is acted upon 
 to a certain extent, through the medium of nerves communicating 
 with, and of others given off from, the cerebro-spinal system, which 
 may reasonably be supposed to perform the functions belonging to 
 their respective sources. 
 
 It is owing to this provision, when the stomach is irritated, and 
 when its organic contractility is inordinately excited, that its sensi- 
 bility is also roused, the influence is propagated to the sensorium, 
 and contraction of the abdominal and respiratory muscles is also 
 produced, which contraction co-operates with that of the stomach 
 itself in giving rise to vomiting. 
 
 Magendie has inferred from his experiments, that it is only the 
 contraction of the abdominal muscles and diaphragm which produces 
 vomiting, and that the stomach has no share in the act. This 
 physiologist, on this, as on other occasions, has not taken into account 
 the various sources of error to which experiments on living animals are 
 liable. He has not sufficiently considered or calculated upon the 
 unnatural positions in which such experiments place the animals 
 experimented upon, and thus derange their natural operations. Stricter 
 and more comprehensive views of the subject shew, that whilst former 
 physiologists have erred in attributing the act of vomiting too ex- 
 clusively to a sudden contraction of the stomach, Magendie and his 
 disciples have been equally to blame in adopting too implicitly the 
 more tangible phenomena of some inconclusive experiments. 
 
 The steps in this process appear to be the following: An irri- 
 tating cause rouses the organic sensibility of the stomach, and gives 
 rise to a considerable contraction of its muscular coats. This exalted 
 state of its organic sensibility and contractility excites, in consequence 
 of the intimate nervous communication between the stomach on the 
 one hand, and the diaphragm and abdominal muscles on the other,* 
 
 " Through the medium of the eighth pair of nerves, and of the branches of the 
 ganglial system which join the spinal nerves.
 
 OF VOMITING. 577 
 
 the action of the latter, which, from vicinity of situation, perform so 
 important a share in the act. Hence it follows, that neither the 
 contraction of the stomach alone, nor that of the muscles only, can be 
 sufficient to give rise to the act of vomiting. It would seem, that so 
 intimately connected are inordinate irritations of the stomach with the 
 action of the diaphragm and abdominal muscles, owing to the 
 anatomical relations of the ganglial system with the eighth pair of 
 nerves and with those of the spinal chord, that the one can never 
 take place, under the ordinary state of the system, without being 
 followed by the other, and giving rise to th'e act under consideration. 
 The nausea which precedes vomiting is merely the sensible impression 
 made by the irritating cause on the nerves of the stomach, which 
 impression, if sufficiently exalted, terminates in the act in question. 
 When this step of the process is about to take place, the diaphragm is 
 the first to contract in a spasmodic manner ; indeed, the irritation of 
 the stomach having excited the diaphragm, the former is struck by the 
 latter against the abdominal muscles, and at the instant when the 
 diaphragm relaxes, the abdominal muscles re-act and impel the 
 stomach against the relaxed and ascending diaphragm, which, in 
 consequence of this state, readily allows the contents of this viscus to 
 be impelled by the concussion of the abdominal muscles, through the 
 cardia into the oesophagus. At the moment when the abdominal 
 muscles act, the glottis is closed, and thus portions of the ejected 
 contents of the stomach are prevented from falling into the larynx. 
 That the glottis is closed at the commencement of the act of ejection, 
 seems undeniable ; but it is frequently relaxed towards the close of the 
 act, so that expiration takes place very fully; and thus the matters 
 which are the last ejected from the stomach are frequently accom- 
 panied with substances from the bronchia, and hence the difficulty 
 often of stating whether certain matters excreted by vomiting have 
 actually come from the stomach or lungs. That the diaphragm is v 
 the first to contract and that it is the first to relax, are shewn by 
 attending to the steps of the process, and by the fact, that the stomach 
 could not empty itself through the cardia if the diaphragm were to 
 continue in a state of contraction. It will, therefore, appear, that the 
 action of the stomach is at its acme when the abdominal muscles 
 re-act and consummate the process ; and that, whilst the diaphragm 
 commences the operation, the abdominal muscles are chiefly efficient 
 in perfecting it. It must be kept in recollection, that both do not 
 contract at the same time. The violent action of the abdominal muscles 
 impels the stomach, and, indeed, the superior viscera of the abdomen, 
 '. so forcibly upon the relaxed diaphragm, and encroaches so much upon 
 the cavky of the thorax, that the lungs are at the time considerably \ 
 pressed upon, and this pressure is farther increased by the ascent -
 
 578 APPENDIX. 
 
 of the contents of the stomach through the oesophagus. Hence it 
 is that vomiting always promotes the discharge of secretions which 
 have accumulated in the bronchia. 
 
 OF THE INTIMATE STRUCTURE AND FUNCTIONS OF 
 THE LlVER. 
 
 (NoxEM. Seep. 119.) 
 
 The very minute researches of Dr. J. M. Mappes, of Frankfort on 
 the Maine, on the intimate structure of the liver, throw considerable 
 light on the functions and pathology of this important viscus.* " If 
 water be slowly injected into the vena portae," this physiologist remarks, 
 " it will force blood and some bile from the hepatic veins ; and ulti- 
 mately it will itself pass out of those vessels. If the liver be now 
 examined, either by dissecting off the peritonaeum, or cutting or tearing 
 the liver, two structures will be observed : the one granulated, forming 
 convolutions, now resembling those of the intestines, and now branching 
 in other forms, flattened and yet rounded, dense and of a yellow 
 colour, and about a quarter of a line in diameter ; the other a cellulo- 
 vascular structure, of a brown colour, which fills up the rounded spaces 
 or oblong fissures, of from a quarter to half a line in diameter, which 
 separate the convolutions from each other. These structures are well 
 shewn, if water in which cinnabar has been diffused be thrown into the 
 hepatic veins ; for the cinnabar is precipitated on the sides of the vessel, 
 and the water passes by the vena portse. Between the convolutions are 
 found triangular and somewhat broken openings, which communicate 
 with each other by little chinks. Some of these contain twigs of the 
 hepatic vein ; in the others, and especially where the chinks are traced 
 to a great depth, and where the vessels form larger trunks, three 
 vessels are seen together, a large one belonging to the hepatic vein, 
 and two others of a smaller diameter, belonging to the artery and the 
 hepatic duct. 
 
 " If the hepatic vein be excepled, the other vessels form branches 
 like a tree, as in the rest of the body. The artery, however, gives the 
 most branches ; apparently because they surround, like a capillary net- 
 work, the parietes of the vena portae, to which purpose they seem to be 
 particularly destined ; although some branches penetrate to the surface 
 of the liver, and are distributed on the peritonaeum, but without form- 
 ing a net-work, as in the former case. The ramifications of the hepatic 
 artery and the hepatic duct are always strictly united together ; and in 
 
 * Journal Compteme ntaire du Dictionnaire des Sciences Medicates, No. XL VI I. 
 >iai 1822.
 
 OF THE INTIMATE STRUCTURE OF THE LIVER. 579 
 
 accompanying the larger branches of the vena portae, they do not 
 intertwine at the two opposite sides of the latter vessel. 
 
 ' The large branches of the hepatic duct divide at an acute angle ; 
 but the ramifications divide at right, or even obtuse angles. It is these 
 latter short and loose twigs which form the parallel ranges of holes, 
 which are seen by cutting the liver in the direction of a branch. These 
 holes are the orifices of vessels, as is seen by injection or by dissecting 
 the twigs ; they cannot, therefore, be confounded with the little dimples 
 which are seen on the internal parietes of the largest hepatic trunks. 
 All the ramifications of the hepatic trunk, indeed, when cut, present a 
 gaping firm opening, like an artery ; whilst the cut orifices of the vena 
 portse which accompany them are always in a collapsed state. 
 
 " The duct ramifies something like the vein. The short and thick 
 trunks divide into branches, and form ,a crowd of smaller and looser 
 twigs, which embrace the grains of the granular substance above de- 
 scribed, but apparently without penetrating the substance of them. 
 Hence, these grains are somewhat separated from each other, and they 
 in some degree compress the cellulo-vascular substance, without, how- 
 ever, giving any of their colour to the latter, which is only traversed by 
 some injected vessels. 
 
 " The parietes of the artery, the vena portse, and the hepatic duct, 
 do not adhere to the substance of the liver ; but are separated from it, 
 as may be seen by the microscope, partly by an uniform gelatinous 
 matter, and partly by an extension of the cellular membrane, which 
 composes the capsule of Glisson. The hepatic vein, on the contrary,, 
 adheres intimately to the granulated substance ; it also follows, without 
 variation, the latter in its distribution, and the smallest branches pene- 
 trate between its granulations. These facts prove the intimate relation 
 which exists between the vein and the granular substance ; whilst the 
 artery and vena portse ramify together in the cellulo-vascular substance, 
 and on the surface of the principal circumvolutions of the ganulated 
 substance ; and the hepatic duct, the twigs of which are averted from 
 each other, seems to hold a relation with both orders of vessels. 
 
 " If a single hepatic vessel be injected, the injection will only pass 
 to the part to which that branch is distributed : on the contrary, water 
 passes rapidly and easily from the vena portae to the hepatic vein, and 
 vice versa. Wax, however, rarely passes, and the hepatic duct is 
 never filled either from the vena portse or hepatic vein." 
 
 From these facts, M. Mappes is led to consider the granular sub- 
 stance to be the secreting part of the liver, around which the vessels are 
 grouped as the conducting and preparatory apparatus. The more in- 
 timate connexion which it holds with the radicles of the hepatic vein, has 
 induced him to presume that the bile is more probably separated by it 
 from the blood which had actually arrived within these radicles, than
 
 580 APPENDIX. 
 
 from that which circulates in the extreme ramifications of the vena 
 portae. This particular substance appears also to M. M. to form the 
 basis of all the glands, and to be of a peculiar nature, modified accord- 
 ing to the functions which nature has imposed on it. He further sup- 
 poses, that in all glandular structures there exists an intermediate 
 substance between the extreme ramifications of both orders of vessels, 
 which holds a more intimate relation* with the changes induced in the 
 blood than the other parts through which it circulates. This substance 
 he conceives to be of a mucous character, and to form the basis of the 
 granular part of the liver and other glands in which the vessels ter- 
 minate and commence, and which, he thinks, is entirely appropriated to 
 the particular function and destination which the gland is intended to 
 fulfil. In proof of this he quotes Doellinger, who has adopted a similar 
 opinion. M. Mappes, in an analysis which he offers of Eysenhardt's 
 investigations respecting the anatomy of the kidney, concludes that the 
 intimate structure of this organ and the liver is in many respects 
 similar. 
 
 Although it is generally agreed amongst physiologists that the se- 
 cretion of the bile takes place in the granular structure of this viscus, it 
 is by no means so generally allowed that the secretion is furnished by 
 the blood of the vena portae. Bichat contended that the bile is 
 secreted from the hepatic artery, and adduced numerous analogies in 
 support of the opinion. More recently, M. Magendie has considered it 
 to be formed, at the same time, from the blood of both the portal and 
 arterial systems. The investigations of M. Mappes may, therefore, 
 be regarded as having set at rest the long-agitated question respecting 
 the vessels secreting the bile, since they shew that the terminations 
 of both the vena portae and hepatic artery meet in the granular struc- 
 ture of the liver, and that they combine to furnish materials for this 
 secretion, which is produced by the granules from which the radicles of 
 the hepatic ducts arise. 
 
 Assimilating and secreting functions of the liver. It seems to us 
 most probable, reasoning from the facts ascertained respecting absorp- 
 tion, that the blood which circulates in the vena portae, being that 
 which is possessed of the venous character in the highest degree, and 
 which, moreover, has a considerable portion of new materials the 
 products of digestion and absorption poured into it before it reaches 
 the liver, undergoes there those changes which are necessary to a per- 
 fect assimilation of these materials,* and to the future offices which the 
 blood itself has to perform in the animal economy ; and that in the 
 course of, or in addition to these changes, the blood of the vena portee 
 has certain of its elements eliminated from it, the elimination of which 
 
 * See the Note on Absorption from the Intestinal Canal.
 
 OF THE FUNCTIONS OF THE LIVER. 581 
 
 is requisite not only to the accomplishment of these changes, but also 
 to the production of a secretion which performs certain offices in the 
 process of digestion. This view of the subject is supported by the 
 following facts, 1st, that those elements of which the bile is composed 
 abound most in the blood of the vena portee, and that if they were to 
 remain in the blood circulating throughout the body, consequences 
 subversive of its healthy existence would rapidly supervene ; 2d, that 
 the portal ramifications are plentifully supplied with the ganglial nerves, 
 which we have shewn to be the source whence the blood-vessels derive 
 their vitality and functions, and the origin of those changes which the 
 fluid circulating in them experiences ; and 3d, that the divisions 
 themselves of the vena portse receive a much greater supply of arterial 
 capillaries from the arteria hepatica <than is observed with respect to 
 any other vein in the body. 
 
 From anatomical investigation, therefore, from numerous experi- 
 ments bearing indirectly on the subject, and from pathological observa- 
 tion, we infer that the blood which is returned from the digestive tube, 
 from the spleen, &c. (having been shewn to contain a considerable 
 portion of absorbed materials, some of them of a more or less heteroge- 
 neous description, others of them more or less animalised ; and, more- 
 over, that certain of the elements or constituents of the blood, requiring 
 to be eliminated from the system, are there in an increased and hurtful 
 quantity if they be allowed to remain in it,) undergoes in the liver 
 most important changes ; that these changes are of two kinds, the one 
 referring to the assimilation of the less animalised materials which the 
 blood may contain, the other to the elimination of the heterogeneous, 
 hurtful, or effete elements which may circulate in it ; that these 
 changes are produced through the medium of the vessels and granular 
 structure of the liver, by the vital influence with which both are en- 
 dowed from the ganglial nerves supplying them ; that these changes 
 are perfect or defective in proportion as that influence is perfect or 
 defective, provided that the structure of the parts, the instruments of 
 this influence, be not deranged ; and that as the vital functions of the 
 organ, depending upon the sources pointed out, may vary very greatly, 
 and as the structure of one or more of the parts constituting the organ 
 may consequently become deranged, the operations of the liver may be 
 thus disordered in a simple or more or less complex manner. * 
 
 * It seems most probable, that recently secreted bile, during the healthy function 
 of the liver, is a bland, albuminous, and alkaline fluid, its larger portion recremen- 
 titious, and combining with the nutritious portion of the chyme to form the chyle. 
 If, then, the bile is secreted in a state of comparative mildness and fluidity during 
 the healthy state of the liver, how comes it to change its characters in the gall, 
 bladder and in the liver itself ? 1st. With respect to its change in the gall-bladder : 
 this may be explained by inferring that an absorption of its more fluid parts takes
 
 582 APPENDIX. 
 
 Of the uses of the bile. Various opinions have been entertained 
 by physiologists respecting the purposes of the bile. " Some have sup- 
 posed that the secretion of the bile is merely excrementitious ; others- 
 that the bile is intended to stimulate the intestine, and to produce a 
 ready evacuation of the faeces; and another opinion has been, that the 
 bile is poured out into the duodenum that it may be blended with the 
 chyme, and by producing chemical changes in it, convert it into chyle. 
 The situation of the liver, connected as it is in every instance with the 
 upper part of the alimentary canal, is unfavourable to the first of these 
 
 place during its remora in this receptacle, and that some change supervenes in its 
 more active constituents, in consequence of which it gradually becomes possessed of 
 the properties which it evinces under such circumstances. 2dly. As to the pos- 
 session of these properties whilst yet' in the liver: this circumstance can only 
 be explained by the condition of the hepatic circulation and of the vital operations- 
 of the organ, either previously to, or co-existent with, this particular state of its 
 secretion. 
 
 In cases of torpor of the liver and languid circulation in the vena portae, and during 
 congestion of the veins of this organ, the bile is very probably secreted of a morbid or 
 vitiated character ; or, although it may not be exactly such at the time of secretion, 
 it may be more disposed to assume this quality during its passage along the ducts 
 running in the substance of the liver. In circumstances of torpor of the liver, with 
 languid circulation in the vena portae, it can scarcely be supposed that the same con- 
 dition does not extend itself to the branches of the hepatic duct. Indeed, it seems 
 more correct to infer that this slow or impeded circulation is actually attended with 
 congestion of bile in these branches ; that during this congestion the more watery 
 parts of this secretion are absorbed ; and that the bile virtually undergoes, before it 
 reaches the duodenum or gall-bladder, a similar change to that which it would have 
 experienced during its remora in this receptacle. In cases of obstructed or impeded 
 circulation, or even of congestion in the hepatic vein, a similar condition of the 
 branches of the hepatic duct may be inferred, inasmuch as they both frequently 
 depend upon the same causes, whether these causes belong to diminished energy of 
 the organ, or mechanical obstructions of their respective trunks, or of parts in- 
 fluencing the functions of these vessels. 
 
 From these remarks it will appear that we consider the bile, 1st, to be secreted 
 of a mild and bland description during the healthy condition of the liver, and 
 especially in temperate or cold climates ; 2d, that it may even possess these pro- 
 perties in a considerable degree as it flows into the duodenum ; 3d, that it becomes 
 more or less consistent, acrid, or stimulating, during its remora in the gall-bladder ; 
 4th, that owing to the condition of the blood generally, or of that portion of it circu- 
 lated by the vena portae, the bile may be secreted of a more acrid or vitiated cha- 
 racter, or it may more readily assume this character soon after its secretion, and 
 whilst yet in the branches of the hepatic duct ; 5th, that this character may often 
 arise from torpor of the vital energy of the liver, or an obstructed or impeded cir- 
 culation of the vena portae, or of the hepatic vein ; 6'th, that it is often accompanied 
 with congestion or obstruction of the hepatic ducts, similar changes taking place in 
 the bile, during its congestion in the branches of the hepatic duct, to those super- 
 vening in the galj-bladder ; and 7th, that this loaded and congested condition of 
 the branches of the hepatic ducts often exists to a very great extent, as we have 
 ascertained by frequent dissection, and that this condition may be termed congestion 
 of bile in the liver.
 
 OF THE USES OF THE BILE. 583 
 
 hypotheses ; but the last is rendered very probable by the circumstance 
 of chylification taking place just at the part where the bile flows into 
 the bowel." 
 
 In order to arrive at some satisfactory conclusion on these points, 
 Mr. Brodie applied a ligature round the choledoch duct of an animal, 
 so as completely to prevent the bile entering the intestine, and then 
 noted the effects produced on the digestion of the food which the 
 animal had swallowed, either immediately before or immediately after 
 the operation. The experiment was repeated several times, and the 
 results were uniform. Before he describes these results, he remarks, 
 that " the application of a ligature round the choledoch duct is easily 
 accomplished, and with very little suffering to the animal ; so that any 
 derangement which follows, in the functions of the viscera, cannot 
 reasonably be attributed to the mere operation. The division of the 
 stomachic ropes, or terminations of the eighth pair of nerves on the 
 cardia of the stomach, and the ligature of the whole extremity of the 
 pancreas, are operations of much greater difficulty ; yet it has been 
 ascertained that neither of these at all interfere with the conversion of 
 the food into chyme, or that of the chyme into chyle." 
 
 " When an animal," Mr. Brodie proceeds to state, " swallows solid 
 food, the first change which it undergoes is that of solution in the 
 stomach. In this state of solution it is denominated chyme. The ap- 
 pearance of the chyme varies according to the nature of the food. For 
 example, in the stomach of a cat, the lean or muscular part of animal 
 food is converted into a brown fluid, of the consistence of thin cream ; 
 while milk is first separated into its two constituent parts of coagulum 
 and whey, the former of which is afterwards redissolved, and the whole 
 converted into a fluid substance, with very minute portions of coagulum 
 floating in it. Under ordinary circumstances, the chyme, as soon as 
 it has entered the duodenum, assumes the character of chyle. The 
 latter is seen mixed with excrementitious matter in the intestine, and 
 in its pure state ascending the lacteal vessels. Nothing like chyle is 
 ever found in the stomach ; and Dr. Prout, whose attention has been 
 much directed to the chemical examination of these fluids, has ascer- 
 tained that alburren, which is the principal component part of chyle, 
 is never to be discovered higher than the pylorus. Now, in my ex-\^ 
 periments, which were made chiefly on young cats, where a ligature 
 had been applied so as to obstruct the choledoch duct, the first of these 
 processes, namely, the production of chyme in the stomach, took place 
 as usual ; but the second, namely, the conversion of the chyme into 
 chyle, was invariably and completely interrupted. Not the smallest 
 trace of chyle was perceptible either in the intestines or in the lacteals./ 
 The 'former contained a semi-fluid substance, resembling the chyme 
 found in the stomach, with this difference, however, that it became of a
 
 584 APPENDIX. 
 
 thicker consistence in proportion as it was at a greater distance 
 from the stomach ; and that as it approached the termination of 
 the ileum in the caecum, the fluid part of it had altogether disap- 
 peared, and there remained only a solid substance, differing in appear- 
 ance from ordinary fseces. The lacteals contained a transparent fluid, 
 which I suppose to have consisted partly of lymph, and partly of the 
 more fluid part of the chyme, which had become absorbed. 
 
 " I conceive that these experiments are sufficient to prove that the 
 office of the bile is to change the nutritious part of the chyme into 
 chyle, and to separate from it the excrementitious matter. An observa- 
 tion will here occur to the physiologist. If the bile be of so much im- 
 portance in the animal economy, how is it that persons occasionally 
 live for a considerable time, in whom the flow of bile into the duode- 
 num is interrupted ? On this point it may be remarked, 1st, That 
 it seldom happens that the obstruction of the choledoch duct from 
 disease is so complete as to prevent the passage of the bile altogether ; 
 and the circumstance of the evacuations being of a white colour, may 
 prove the deficiency, but does not prove the total absence of bile. 
 2dly, That in the very few authenticated cases which have occurred of 
 total obliteration of the choledoch duct in the human subject, there has 
 always been, I believe, extreme emaciation, shewing that the function 
 of nutrition was not properly performed. 3dly, That the fact of indi- 
 viduals having occasionally lived for a few weeks or months under these 
 circumstances, only proves that nutrition may take place to some extent 
 without chyle being formed. In my experiments I found that the 
 more fluid parts of the chyme had been absorbed ; and probably this 
 would have been sufficient to maintain life during a limited period of 
 time."* 
 
 Dr. Stearns, of New York, is of opinion that the gall-bladder is not 
 * passive in the reception of the bile, and that it is not a mere receptacle 
 for this fluid. He supposes that the cystic duct acts as an absorbent, 
 selecting from the bile in the hepatic duct its more active ingredients, 
 which are carried into the gall-bladder, where they remain until " some 
 peculiar irritation" of the mouth of the common duct, by the passing 
 chyme or by some other stimulating cause, solicits its discharge, in a 
 gradual manner, for the purpose of purging the intestines. In support 
 of this opinion he refers to the experiments of Dr. Douglas, of the same 
 city, who found that the bile which passed directly from the hepatic 
 duct into the intestines was bland and harmless, and was mixed with 
 the chyme, and thus seemed to aid, as shewn by the very conclusive 
 experiments of Mr. Brodie, in the formation of the chyle, and of the 
 new materials for the nourishment of the body ; whilst the bile found in 
 s the gall-bladder was always bitter, pungent, and viscid. 
 
 .* Journal of Science and the Arts, No. XXVIII.
 
 STRUCTURE AND FUNCTION^ OF THE SPLEEN- 585 
 
 These properties, however, of the cystic bile, may supervene with- 
 out any election being exerted by the cystic duct in the process ; for 
 if we suppose, what is most probable, that during the empty state of 
 the duodenum, the bile flows into the gall-bladder, where its more bland 
 and fluid portions are removed by the numerous absorbent vessels with 
 which the gall-bladder and its ducts are provided, and where, during 
 its retention, its elements combine in such a manner as to modify the 
 characters of the secretion, and to render them very different from 
 those which it evinced immediately after its formation, we have a suf- 
 ficient reason for the more pungent qualities of cystic bile. It seems 
 by no means unlikely, therefore, that the change takes place in 
 the bile itself within the gall-bladder, and that it is promoted by the 
 temperature and vital influence of the system. 
 
 In respect of Dr. Stearns' opinion, that the gradual flow of the 
 cystic bile into the intestines serves the purpose of a gentle purge or 
 stimulus to their functions, it is by no means new ; but we have no more 
 proof that it acts the part of a purge, than that it performs the office 
 of an astringent. How is it, if this opinion be correct, that diarrhoea, 
 or a lax state of the bowels, is so often observed during interruptions of 
 the biliary secretion, and especially of the cystic bile ? 
 
 After the full detail of the results of Mr. Brodie's conclusive ex- 
 periments, we need not state at a greater length modern views upon the 
 subject. In the note upon the function of respiration, we will briefly 
 notice some peculiarities connected with the functions of the liver and 
 conditions of the bile. 
 
 OF THE STRUCTURE AND FUNCTIONS OF THE SPLEEN. 
 
 (NOTE N. See pp. 120, 121.) 
 
 Although considerable attention has been paid to the physiology of 
 the spleen, yet its functions are but imperfectly understood. They 
 have, indeed, been variously explained by philosophers, but all have 
 erred, chiefly in endeavouring to assign to it one definite function only, 
 which they consider it to perform under all the circumstances that 
 influence the body. Thus, Malpighi, Haller, Blumenbach, Richerand, 
 and Fodere, imagine this organ to be subservient in its functions to 
 those of the liver. Hewson believed it to be destined to the elaboration 
 of the globules of the blood. Tiedemann and Gmelin are of opinion 
 that it is intimately connected with the absorbent system, and that it 
 assists the process of sanguification. Haighton and Moraschi consider 
 that it is subordinate to the stomach in the process of digestion ; and 
 many pathologists believe that it permits, in consequence of its peculiar 
 texture, accumulations of blood to take place within it during certain 
 stages of disease, and that it thus prevents more vital organs from
 
 586 APPENDIX. 
 
 suffering injury to which they would otherwise be liable. To us, how- 
 ever, it appears more rational, and certainly more consistent with the 
 operations which characterise the economy of the more perfect animals, 
 to view the functions of this organ as intimately relating to those 
 which the absorbent, circulating, and secreting systems perform, and 
 as including several of the operations just specified, to a greater or less 
 extent, according to the influences to which the body is subjected. 
 
 In order to learn the nature of the offices which the spleen performs 
 in the animal economy, it ought to be our first object to ascertain cor- 
 rectly its structure ; this is, however, a matter of great difficulty. The 
 attention of anatomists has lately been particularly directed to the 
 subject, and Home, Heusinger, and Hopfengaertner, have been assi- 
 duous in this investigation, without, however, determining the much- 
 disputed point, whether or no this viscus possesses a proper or glan- 
 dular structure, or is simply a minute and infinite interlacement of 
 arteries, veins, and lymphatics. Sir Everard Home concludes from 
 his researches, that" it consists of blood-vessels, between which there is 
 no cellular membrane, and the interstices are filled with serum and 
 the colouring matter of the blood, from the lateral orifices in the veins, 
 when these vessels are in a distended state, which serum is afterwards 
 removed by the numberless absorbents belonging to the organ, and car- 
 ried into the thoracic duct by a very large absorbent." Sir Everard 
 considers " the spleen, from this mechanism, to be a reservoir for the 
 superabundant serum, lymph, globules, soluble mucus, and colouring 
 matter, carried into the circulation immediately after the process of 
 digestion is completed." 
 
 M. Beclard * has given an opinion respecting the structure of this 
 viscus, which appears to be the most correct yet offered. He considers 
 that it belongs to the class of erectile tissues, and that its structure 
 results from a peculiar arrangement of arteries and veins, similar to 
 that which is found in the penis, the clitoris, and female nipple. 
 M. B. thinks, that the spleen very nearly resembles the cavernous body 
 of the penis, both in structure and in its phenomena ; and he considers 
 it not only to consist of erectile tissue, but to be also the seat of a 
 species of erection more or less similar to that of the cavernous body. 
 This vL-cus, he argues, presents an actual motion of expansion and con- 
 traction ; and he adduces the three following circumstances under which 
 this takes place. 1st, In experiments: when the course of the blood 
 in the splenic vein is arrested in living animals, the spleen swells, but 
 returns to its former dimensions as soon as the circulation through the 
 vein is restored. 2d, In diseases : the paroxysms of intermittents are 
 accompanied with an obvious enlargement of this viscus, which sub- 
 
 * Additions to the Anal. G I HI rule of Bichat.
 
 STRUCTURE AND FUNCTIONS OF THE SPLEEN. 587 
 
 sides as soon as the paroxysm is over. 3d, A similar phenomenon takes 
 place during digestion. The lateral openings of the veins, noticed by 
 Sir Everard Home, seem to confirm the views of M. Beclard respecting 
 the dilatation and frequent inosculation of the venous radicles in this 
 viscus, which are common to it and the other erectile tissues.* 
 
 In respect of the functions of the spleen we will only adduce 
 those views which possess claims to a favourable notice. 
 
 C. H. Schmidt f considers that its vasa brevia contribute to nourish 
 and strengthen the stomach ; and that, as the blood of dogs deprived 
 of the spleen is found to run speedily to putrefaction, it is concerned 
 in the preparation and assimilation of the elements of the blood, and 
 that it performs an office to the liver analogous to that which the 
 lungs fulfil with respect to the heart. 
 
 Professors Tiedemann and GmelinJ conclude, from their investiga- 
 tions on this subject, 1st, That the spleen is an organ closely connected 
 with the lymphatic system. This is shewn by its being restricted to 
 those animals which possess a separate absorbent system, by the number 
 of its lymphatic vessels, and by the circumstance of the spleen of the 
 turtle being similar to a mesenteric gland. 2d, That a coagulating 
 fluid is secreted in it from the arterial blood, is taken up by the ab- 
 sorbents, and carried into the thoracic duct. This fluid or lymph, 
 they remark, was seen not only by them, but by Hewson; and they 
 conclude, that the formation of it is the only means by which it is 
 possible to account for the use of the great quantity of arterial blood 
 which flows into the spleen. In answer to the question, by what 
 means this coagulable lymph passes into the absorbents ? they reply, 
 either there are, in the substance of this organ, particular gland-like 
 bodies, and small spaces or cells, which several anatomists say they 
 have remarked, in which the fluid is secreted and taken up by the 
 absorbents, or the finest branches of the arteries in the spleen pass 
 immediately into the absorbents, and by this means some part of the 
 arterial blood reaches the absorbents. From a consideration of all the 
 facts obtained by themselves and former investigators, they infer that a 
 connexion subsists between the splenic arteries and absorbents, either 
 directly or indirectly, by means of cells. The secretion of this reddish 
 coagulating lymph from the arterial blood takes place, in their opinion, 
 from the nerves being excited, particularly during digestion ; and con- 
 sequently, by the plentiful secretion, the course of the blood is carried 
 forward in the spleen, which by this means is reduced in size. 3d, That 
 this secreted coagulable lymph, when conveyed into the thoracic duct, 
 
 * See the Note, in the APPENDIX, on the Organs of Generation. 
 (- Comment, de Pathol. Lienis. 
 Versuche uber die Verrichtung der Milz, <Jc.
 
 588 APPENDIX. 
 
 is intended to render the chyle similar to the blood. They consider 
 this inference to be proved by at least two circumstances: 1st, That 
 this change actually takes place, for the chyle of the thoracic duct 
 differs from the chyle of the mesenteric vessels, by a closer resemblance 
 to perfect blood ; 2d, That when this coagulable matter was by any 
 means prevented from reaching the thoracic duct, this change did not 
 take place. Amongst other proofs which Professors Tiedemann and 
 Gmelin adduce in support of these circumstances, they shew that the 
 chyle taken from the absorbents of the intestinal canal before these ves- 
 sels have passed through the mesenteric glands, is always white and has 
 no tinge of red, and either undergoes no coagulation, or does so very 
 feebly and slowly. The same fact had been previously shewn by various 
 anatomists, and similar appearances to those which are now to be 
 noticed have been remarked by Dr. Prout. Professors Tiedemann and 
 Gmelin always observed that this fluid, when it is taken from the ab- 
 sorbents which have passed out of the mesenteric glands, is redder, and 
 coagulates more easily and more firmly than the other ; and that the 
 chyle in the thoracic duct, above the entrance of the splenic absorbents, 
 and after being mixed with the reddish coagulable lymph, appears the 
 reddest, and coagulates very rapidly. The gradual change of the 
 / chyle into blood, they argue, seems, therefore, to be a consequence of 
 its passage through the mesenteric glands, and of the admixture of the 
 reddish coagulable lymph supplied by the absorbents of the spleen. 
 
 " The properties of the spleen in the foetus and in old age, support 
 this view. In the foetus, the spleen is well known to be very small, and 
 no chyle is formed in the intestinal canal in this stage of existence ; 
 the spleen, accordingly, intended to assimilate the alimentary matter 
 derived from the intestinal canal, is of no importance. After birth, 
 when the formation of chyle begins, this organ shews itself full of blood, 
 and increases in size rapidly. In old persons, the spleen is commonly 
 diminished ; it appears, therefore, like the lymphatic glands, to decrease 
 in size with age." 
 
 In order to establish the second circumstance which supports their 
 third conclusion, Professors Tiedemann and Gmelin had recourse to 
 direct experiment, which fully proved its accuracy. They conclude by 
 observing, that pathology furnishes many confirmations of their opinion; 
 and they adduce the instances of scrofula, diseases of the chylopoietic 
 viscera in general, intermittent fever, and abdominal dropsy.* 
 
 The nerves of the spleen are chiefly from the coeliac plexus, and form a reticu- 
 lum around the splenic artery, accompanying this vessel in all its distributions ; a 
 very few minute nerves also come from the par vagum^ and inosculate with those of 
 the cceliac plexus. 
 
 M. Defermon recently found, in his experiments on the abdominal circulation, 
 that the spleen is susceptible of contraction under the influence of various substances
 
 OF THE INTESTINAL CANAL, &c. 589 
 
 OF THE MUCOUS COAT OF THE DIGESTIVE CANAL, AND THE 
 FUNCTIONS OF THE SMALL AND LARGE INTESTINES. 
 
 (NOTE O. See pp. 123, 126, 129.) 
 
 The mucous membrane of the digestive tube has an amorphous 
 and spongy structure, more or less soft, and of variable thickness. The 
 free surface of this membrane presents, 1st, Valvules formed of folds 
 of this membrane, of the submucous tissue, and of muscular fibres con- 
 tained within these folds. 2d, More or less evident depressions, which 
 are generally infundibuliform, cellular, or alveolar; the follicles differ 
 but little from the alveolar depressions ; they have a narrow neck more 
 or less lengthened, and a dilated body lodged in the submucous tissue. 
 They are formed of this membrane turned back upon itself, and exte- 
 riorly surrounded by dense cellular tissue supplied with numerous capil- 
 laries : they vary greatly in number in different situations. 3d, Small 
 eminences called papillae, and villosities which are situated on the un- 
 attached surface of the membrane. These assume various forms, but 
 in general, those in the pyloric extremity of the stomach and in the 
 duodenum, being more broad than long, present a laminated appear- 
 ance ; those of the jejunum are long and straight, and are correctly 
 called villosities ; whilst towards the end of the ileum, and in the colon, 
 they re-assume the laminated character. The villosities are semi- 
 diaphanous, their surface is smooth without any appearance of a cel- 
 lular or a vascular texture, both of which have been imputed to them. 
 Professor Meckel, whilst he doubts whether or not they possess either 
 the one species of structure or the other, is inclined to believe, from 
 analogy with certain parts of some vegetables, that they consist of a, 
 continuous series of cells. 
 
 The villosities of the mucous membrane of the intestinal canal 
 appear to be a mode of structure which, as well as that of folds, gives 
 
 which act directly on the nervous system, such as strychnine, camphor, acetate of 
 morphine, &c. In dogs to which he had given strychnine, the spleen, which is 
 usually flat, rolled itself into a spiral form when absorption commenced, and pre- 
 sented very energetic contractions. The action of camphor was different : the 
 spleen under its influence became rugous, and its surface assumed a granulated 
 appearance, producing a degree of motion in the whole organ. 
 
 The influence of these agents on a viscus whose nerves are nearly exclusively 
 belonging to the ganglial system, confirms our views respecting the extent of func- 
 tion which we have attributed to this system. 
 
 As respects its structure, the spleen may be said to consist of a minute and infi- 
 nite interlacement of arteries, veins, lymphatics, and soft nerves. Its blood-vessels 
 are endowed with a faculty of dilatation under certain conditions of the system and 
 of the adjoining parts, so as to allow accumulations of blood to take place within it 
 ta a very considerable extent, without material injury to itself or to the body.
 
 .590 APPENDIX. 
 
 an increase of the extent of surface exposed to the influence of external 
 agents. " Villosities are only more minute forms of membranous folds, 
 differing somewhat from the latter in the greater proportion of the ex- 
 tent of their surface to that of their base, and thus presenting where 
 they exist, which is chiefly in the small intestines, the means by 
 which the above-mentioned purpose may be most perfectly fulfilled." 
 
 The epidermis, or epithelium,' is very manifest at the openings into 
 the digestive canal, but soon becomes much less so as we advance 
 into the cavities, until it is entirely indemonstrable. The blood- 
 vessels and absorbents of this membrane are abundant. Its nerves are 
 chiefly from the ganglial system, but at its natural openings they come 
 also from the cerebro-spinal system. 
 
 The Junctions of the mucous membrane of the digestive tube may be 
 enumerated under the following heads : 
 
 1. Absorption, of which the villosities are the most active although 
 not the only agents. 
 
 2. Secretion, which is perspiratory and follicular, and of which the 
 products, differing much according to the situation from whence they 
 issue, are generally known under the term mucosity. 
 
 3. Tonic contraction, which is promoted by the action of the mus- 
 cular fibres. 
 
 4. Sensibility, varying in all its grades and modes of manifestation. 
 The mucous membrane of the intestinal canal is next to the first, if 
 
 not the first, of the structures of the body which comes into existence. 
 Its characters are but little modified by age or sex.* 
 
 Of the digestive process in the intestines it is not necessary to say 
 much in addition to what is contained in the text. This process, as it 
 respects the whole apparatus destined for its performance, may be di- 
 vided into three stages, namely, chymifaction, chylifaction, and fseca- 
 tion; the first is performed in the stomach, the second in the small 
 intestines, and the third in the large intestines. The first has already 
 come before us, and the second was noticed when the functions of the 
 liver were under consideration. We may, however, remark, respecting 
 chylifaction, that it is by no means a chemical process, for there subsists 
 no chemical relation between the chyme and the biliary and pancreatic 
 juices, which are the materials of the new product; this process is 
 altogether a vital one, and the result is very nearly alike under every 
 circumstance. Chylifaction chiefly takes place in the duodenum and 
 jejunum, from the admixture of the juices just now mentioned with the 
 chyme. The experiments of Professor Mondini confirm the inference, 
 
 * See the Note in the Appendix, on the Developement of the Textures of the 
 FastiM.
 
 FUNCTION'S OF THE C.ECUM, &C. 591 
 
 that the duodenum is distended with the chyme when the bile is passing 
 into it. 
 
 The absorption of the chyle commences about the end of the duo- 
 denum, and goes on throughout the jejunum and the first half of the 
 ileum, and is nearly completed at the termination of this intestine; this 
 function takes place with greatest activity in the jejunum. 
 
 When the secretions poured into the duodenum are deficient or 
 excessive in quantity, or deranged in quality, it is obvious that the 
 digestive function in the small intestines must be disordered accord- 
 ingly. Such disorder is indeed of very frequent occurrence ; and the 
 observing practitioner may often be able to trace, by concurrent signs, 
 the specific cause and pathological state. On some occasions he will 
 infer, that the energies of the stomach and duodenum being exhausted, 
 the substances received into them do not undergo the requisite changes, 
 but frequently form new combinations to which their constituent ele- 
 ments are chemically prone, and which irritate and inflame the surface 
 with which they are in contact. On other occasions he will be induced 
 to conclude, from a careful comparison of symptoms, that the secretions 
 which are poured into the duodenum are deficient in quantity, or even 
 vitiated in quality, thus imperfectly performing the purposes for which 
 they are intended. At another time he will rationally infer, that the 
 bile which has been long congested in the ducts, running through the 
 liver, or pent up in the gall-bladder, has been let loose, and, owing to 
 the more acrid properties it has acquired during the term of its con- 
 gestion, is now irritating the duodenum and small intestines, exciting 
 sympathetically the stomach, owing to the nervous and vascular con- 
 nexion, and stimulating the whole canal through which it passes, and 
 even exciting the surfaces over which it flows, or with which it remains 
 for any time in contact, to inflammatory action. 
 
 Of the functions of the cacum and large intestines, or facation. 
 The caecum, both as respects its functions and its diseases, is an organ 
 which has not yet received that degree of investigation which it seems 
 to deserve. As regards its functions, certain particulars may be ad- 
 duced, which appear, both from experiment and observation, to be 
 satisfactorily made out. 
 
 The resemblance of the caecum to the stomach in most of the grami- ' 
 niferous and particularly the ruminating animals, as well as its form and 
 situation throughout all the higher classes of the animal kingdom, are 
 circumstances which sufficiently shew it to be a reservoir in which the 
 last act of digestion is performed. This was the opinion of Viridet,* 
 
 * Se.d de intestino cseco quidquam dicere praestat, cum in quibusdam animalibus 
 sit summe necessarium, nempe quibus est amplissimum, forsanqne vicem altering
 
 592 APPENDIX. 
 
 and it is fully confirmed by the able and recent researches of Tiedemann 
 and Gmelin.* 
 
 The situation of this viscus, its capacity, particularly in some ani- 
 mals, the circumstance of its contents having to advance, in opposition 
 to their gravity, and its attachment to the parietes of the abdomen, are 
 proofs of a much slower circulation of the intestinal contents through 
 it than through any other part of the canal, and confirm the view which 
 has been taken as to its being, in some respects, a reservoir, in which 
 is poured that portion of the materials remaining in the ileum, and 
 which effects the last changes in them which they are destined to UQ- 
 t dergo for the purposes of digestion and nutrition. 
 
 Besides the proofs in support of this opinion which have been now 
 adduced, it may be important to state, that this viscus is abundantly 
 supplied with large follicular glands, which, according to the experi- 
 ments of Tiedemann and Gmelin, secrete an acid, albuminous, and 
 solvent fluid, which mixes with the remaining aliments poured into it 
 from the ileum, and promotes the digestion of those portions which 
 have withstood the digestive process in the stomach and small intestines, 
 or have been insufficiently changed in their transit through them for 
 the purposes of absorption and nutrition. In order that this office may 
 be more completely performed, the materials poured into the caecum 
 remain a greater or less time ; so that Nature seems to make a last 
 effort, by means of this part of the large intestines, to obtain the re- 
 maining nourishment from the intestinal contents. 
 
 But, whilst the caecum performs the last act of digestion, it seems 
 at the same time to commence the first part offacation ; for it is only 
 in the caecum that the intestinal matters assume a feculent odour. The 
 contents of this viscus are generally of the consistence of a soft bouillie, 
 of a brown or brownish-yellow colour, with a feculent smell. This 
 odour, according to Tiedemann and Gmelin, proceeds from a volatile 
 oil, which is apparently secreted chiefly in the caecum. 
 
 During these changes which are effected by the caacum on its con- 
 tents, an acid and hydro-sulphuretted gas is disengaged from them. 
 This gas "seems to be generated only in small quantities during the 
 healthy function of this organ ; but when the vital energies of the viscus 
 are diminished, and when, consequently, more or less of remora of its 
 contents takes place beyond what they generally experience, this gas 
 
 ventriculi gerit : nam glandulis crassioribus donatur, quorum succus solutions helio- 
 tropii rubescit, et solutione sublimati albescit, suisque salibus acidis et volatilibus 
 praeditum est." De Prim& Coctione, p. 270. 
 
 Recherches Experimentales, Physiologiques, et Chimiques, sur la Digestion, 
 con&ideree dans les quatre classes d'Animaux Vertebres. Par F. Tiedemann et 
 L. Gmelin, Professeurs a 1'Universite de Heidelberg, &c. Par A. J. L. Jourdan. 
 Paris, 1826 et 1827-
 
 OF THE FUNCTIONS OF THE C.ECUM. 593 
 
 is disengaged in much greater quantities ; so that it becomes distended 
 to an extent which is injurious to its healthy tone. In many cases it 
 re-acts on the distending power ; and thus the flatus, with the other 
 materials contained in it, are propelled along the colon : but on many 
 occasions, and under particular circumstances, considerable opposition 
 is offered to their transit about the right flexure of this latter viscus ; 
 and hence it may rationally be inferred, pain and uneasiness are fre- 
 quently produced in this part of the colon, as well as in the caecum, 
 giving rise to the belief, in the minds of those who view the ailments of 
 such patients superficially, that they are labouring under hepatic dis- 
 ease. It is true that very frequently the particular condition of the 
 caecum now under consideration is sometimes complicated with chronic 
 hepatic disorder ; but the existence of such complication could not be 
 understood, unless the practitioner was already aware of the nature of 
 the former derangement. When, also, attention is not paid to the first 
 call to stool, an impediment is thus placed in the way of the passage of 
 its contents along the colon, and obstruction and distension of the 
 csecum are thus either occasioned, or increased if it previously existed. 
 
 Occasion may now be taken to observe that, under circumstances 
 which cause the remora or stagnation of those materials in the caecum 
 which are poured into it from theileum, not only is there a sulpho-car- 
 buretted hydrogen gas disengaged from them, occasioning distension 
 and other derangements ; but they experience considerable changes, 
 becoming more irritating and noxious to this viscus itself, and inducing 
 chronic inflammatory action in its mucous coat. 
 
 Under other circumstances of protracted disorder of the digestive 
 apparatus, as when acidity is generated in the >tomach and small intes- 
 tines, owing to imperfect digestion of the food ; and when the articles of 
 diet or of drink are of an irritating, or stimulating, or otherwise impro- 
 per kind or quality ; and when the secretions from the liver and pan- 
 creas, and even from the mucous surfaces of the small intestines them- 
 selves, are of an acid or an irritating nature, then the remora which 
 these materials experience in the csecum, and the time which they 
 hereby have to act upon its internal surface, are often productive of 
 disorder of its function and of its internal structure. 
 
 To the function of the larger intestines may be given the term 
 fcecation; because it is in this situation of the digestive canal that the 
 faecal matter is formed. In its course through the small intestines the 
 alimentary matters are deprived of their chyle, and of a portion of their 
 more aqueous parts : the residue is poured into the caecum, where its 
 course is more slow, and where it assumes new characters. The faecal 
 mass, according to the properties which it presents at the commence- 
 ment ofthe colon, is evidently composed, 1st, of the residue of the 
 aliments ; and 2d, of the excrementitial parts of the secretions poured
 
 594 APPENDIX. 
 
 into the superior part of the digestive tube. The faeces, when they 
 arrive in the rectum, or at the time of their expulsion from the body, 
 are greatly increased by the more solid parts of the secretions poured 
 out upon the internal surface of the caecum and colon, their more fluid 
 parts having been absorbed. It is, in some measure, owing to the 
 quantity and properties of the excrecnentitial parts of these latter secre- 
 tions, which principally proceed from the follicular apparatus of these 
 intestines, that the faeces present distinctive characters. 
 
 Gaseous substances generally are found in greater or less abundance 
 in both the small and large intestines. This gas may come from more 
 than one source : it may arise from the change which the alimentary 
 substances undergo in their course; or it may be secreted by the 
 mucous membrane of the intestines. While we would not altogether 
 deny a share in its production to the former, we contend for the 
 latter. We believe that the mucous membrane of the digestive canal 
 may both secrete gaseous substances and absorb them ; and we 
 found our belief upon the following circumstances: 1st, We have 
 proofs derived from experiment and observation that gaseous substances 
 are absorbed and given off from the mucous membrane of the respiratory 
 apparatus. 2d, Pathological facts, intimately connected with the func- 
 tions and properties of this membrane in different parts of the body, 
 support the position. We have, however, no doubt that the changes 
 which the alimentary substances undergo in the stomach occasionally 
 give rise to gaseous products; and we believe that a similar result 
 follows the remora of the excrementitial matters in the colon and rectum. 
 As to the chemical characters of the gaseous substances found in dif- 
 ferent parts of the intestinal tube, see Chapter II. of this Appendix. 
 
 OF THE FUNCTIONS OF THE KIDNEYS. 
 (NOTE P. See pp. 133 141.) 
 
 The latest, and, we think, the most correct examination of the in- 
 timate structure of the kidneys was given at p. 131. We now add the 
 latest experiments which have been made in order to ascertain the ex- 
 tent of their functions. MM. Dumas and Prevost of Geneva, and 
 afterwards M. Segalas, of Paris, found, on examining the blood of 
 living animals whose kidneys had been extirpated, that it contained 
 urea,* the quantity of which was increased in proportion to the dura- 
 tion of life after the operation ; whilst this substance could not be 
 detected in the blood of those animals in which the urinary secretion 
 was uninterrupted. The last-mentioned physiologist, moreover, having 
 injected an aqueous solution of urea into the veins of an animal, 
 
 * Five ounces of Wood contaiu one scruple of urea.
 
 OF THE FUNCTIONS OF THE KIDNEYS. / 595 
 
 observed the secretion of urine rapidly increased by it, and this 
 substance so quickly eliminated in the process, that after twenty-four 
 hours it could not be detected in the blood. It seems, therefore, not 
 improbable that the debris of the textures, being carried into the 
 circulation, is converted, by the influence of the organs and vessels 
 through which it flows, into the substance called urea, and that the 
 function of the kidneys is to eliminate it, with other materials, which 
 would be hurtful to the system. These experiments shew that urea 
 is not formed in the kidneys by their appropriate functions, as was 
 believed by some physiologists; but that it, and probably other 
 materials, which are removed from the blood by these organs, are 
 derived from other sources. 
 
 According to Berzelius's analysis of the urine,* this secretion 
 contains, in its healthy state, somewhat more than thirty parts in a 
 1000 of urea; and Dr. Prout has shewn that nearly one half of urea 
 consists of azote ;f consequently it follows, that\he injurious accumu- 
 lation of azote in the system is prevented by the action of the kidneys. 
 Hence we observe the great proportion of urea in the urine of those 
 who eat much animal food, in which nitrogen abounds. We may 
 therefore justly conclude, as, indeed, Dr. ElliotsonJ has remarked, that 
 the kidneys are the great outlet for azote, as the lungs and liver are for 
 carbon. 
 
 The following facts more closely relate to pathology than to 
 physiology. 
 
 In inflammatory fever the urine is red or deep coloured, or even a 
 deep brown, and perfectly transparent until the disease tends to a 
 termination ; it then deposits the lateritious sediment, which is of a 
 reddish colour, and consists of animal matter, phosphate of lime, 
 lithic acid, and sometimes lithate of ammonia. According to Dr. 
 Prout, lithate of soda, and purpurates of ammonia and soda, are also 
 present. In intermittents the appearance of the urine varies according 
 to the stage of the disease ; but when a paroxysm of ague is over, 
 what is then voided deposits a peculiarly red powder, which has been 
 examined by Dr. Prout, and found to be a distinct acid, which he has 
 named rosacic acid, from its colour. In typhus fevers the urine is 
 loaded with gelatine and urea. It deposits in gouty disorders, as it 
 cools, a large quantity of lithic acid, in the form of red crystals. The 
 urine in hysteria is of a very pale colour ; it contains abundance of 
 saline ingredients, but is very deficient in urea and animal matter. In 
 
 * See the Chapter at the conclusion of the APPENDIX, on the Analysis of the 
 Fluids, &c. of the body. 
 
 f Azote, 1866; oxygen, 1066; carbon, 799; hydrogen, 266, = 4000. 
 
 J Elements of Physiology, by J. F. Blumenbach, &c. Translated and 
 supplied with copious notes by John Elliotson, M.D., &c. &c.
 
 596 APPENDIX. 
 
 jaundice it is usually of a brown colour, arising from an admixture 
 of bile. In various other disorders, especially those affecting the 
 secreting function of the liver, more particularly when that function is 
 imperfectly performed, the urine very generally presents a brown and 
 muddy appearance, owing to the kidneys having assumed an action in 
 some degree vicarious to that of the 4iver, and thus removed much of 
 the carbonaceous and effete materials from the blood usually elimi- 
 nated by that viscus. A similar appearance of the urine is often met 
 with in those fevers wherein the functions of the liver are much 
 embarrassed, especially in those which are met with in warm climates. 
 
 / In ascites this fluid frequently assumes a yellowish-green colour, and is 
 extremely viscid. It deposits a copious sediment of rosacic acid, mixed 
 with lithic acid, phosphate of lime, and animal matter ; and is often 
 loaded _with albumen to such a degree, as to deposit it when heated, 
 or on the addition of concentrated sulphuric acid. Those appearances, 
 however, are not constant ; they are more generally met with in the 
 acute forms of dropsy. In some cases of rickets, the urine has been 
 
 \ found saturated to a high degree with phosphate of lime. Its cha- 
 racter in diabetes is well known. Blood is frequently found in the 
 urine ; it gives this secretion more or less of a dark colour and muddy 
 sediment. Mucus is also met with in this fluid, during diseases 
 affecting either the kidneys, the mucous membrane of the bladder, or 
 the prostate gland. 
 
 OF ABSORPTION. 
 (NOTE Q. See pp. 150, 152, 157, 159.) 
 
 I. Of absorption from the digestive canal. It appears, from the 
 experiments of Tiedemann and Gmelin on absorption, that the 
 lacteals take up the digested and dissolved portions of alimentary 
 substances, and convey them as chyle through the thoracic duct to the 
 blood-vessels; but as odoriferous, colouring, and some saline sub- 
 stances are not absorbed by them, and yet are found in the blood of 
 the vena portse and in secreted fluids, it necessarily follows, that 
 there must be some other' way than the thoracic duct, by which they 
 pass into the blood. 
 
 The following are the chief suppositions which have been offered in 
 explanation of the facts: " Either all the lacteals do not enter the 
 thoracic duct, and part of them join the veins which form the vena 
 portee, and thus transmit their contents into the blood of the vena 
 portae; or substances pass directly from the stomach and intestinal 
 canal into the veins ; or, finally, both of these suppositions may be" 
 true."
 
 OF ABSORPTION'. 597 
 
 These physiologists found, that quicksilver injected into the \ 
 absorbents of the intestinal canal easily reached the mesenteric veins 
 and the vena portae, and this communication was found to take place 
 in the mesenteric glands. By means of this communication they 
 explain the appearance of streaks of a substance like chyle, which is 
 perceived in the blood of the vena portae after taking food, a fact/ 
 which has been frequently observed by other anatomists. 
 
 Though the passage of chyle into the vena portae may be ex- 
 plained by this connexion of the absorbents with the veins of the 
 intestines, it would appear, from the experiments, that the passage of 
 odorous colouring and saline substances does not take place in the 
 same way. The presence of alcohol, gamboge, or indigo, could never be 
 detected in the lacteals or thoracic duct, though it was abundantly 
 manifest in the blood of the mesenteric veins and in the vena portae. 
 They therefore conclude, that the passage of these substances must be 
 effected through other channels, and that these channels must be the 
 radicles of the veins of the intestines. It was found, on examining 
 blood taken from a branch of the mesenteric vein of a dog, to which 
 sulphuro-prussiate of potass had been given, that no streaks of chyle 
 were present, but the saline matter was perceived. From this, and \ 
 other experiments, they conclude that the veins of the intestines 
 appear particularly to absorb heterogeneous substances, such as those 
 already particularised, whilst the lacteals take up nutritious matter; 
 and, consequently, that substances taken into the digestive canal may 
 pass into the. mass of blood 1st, through the absorbents and the 
 thoracic duct ; 2dly, through absorbents, which are united with veins in 
 the mesenteric glands ; 3dly, through the radicles, or the commencement/ 
 of the mesenteric veins, which ultimately form the vena portae. 
 
 MM. Seiler and Ficinus* have more recently repeated the experi- 
 ments of Magendie and of Tiedemann and Gmelin on this subject, and 
 confirmed most of their inferences, particularly those of the Heidelberg 
 professors. 
 
 As it seems established by these and other experimenters, that the 
 vena portae receives chyle from the absorbents and other substances which 
 are taken up from the intestinal canal by the veins themselves ; and as 
 the blood of the vena portae, into which these materials are conveyed, 
 passes through the liver, this viscus must be regarded as an organ of 
 assimilation as well as of secretion. f 
 
 * Journ. Complement. Aout 1824, p. 125, et seq. 
 
 f- See the note on the Functions of the Liver, p. 578. 
 
 Having treated of the function which has been considered as properly be- 
 . longing to the liver, we may also allude to the inquiry already made by us, 
 whether or no this important organ performs any other part in the economy. But 
 before this question can be entertained, it will be necessary briefly to consider the
 
 598 APPENDIX. 
 
 II. Of absorption in the lungs. Professor Mayer, of Bonn, infers, 
 from experiments instituted in order to ascertain to what extent ab- 
 sorption takes place from the lungs : 
 
 1. That animals support a considerable quantity of liquid injected 
 into the lungs, without experiencing mortal symptoms from them; 
 but these injections should be performed by an opening made in the 
 trachea. 
 
 2. The symptoms of suffocation, which arise from injections, are 
 not serious when we inject pure water ; but they become so when thick 
 fluids, for example oil, which obstructs the aerial passages, or some 
 chemical solutions, which inflame the bronchial surfaces, are employed 
 in this manner. 
 
 3. The fluids and solutions injected into the lungs are absorbed 
 
 important fact, that a portion of the materials absorbed from the digestive tube is 
 either removed by means of the radicles of the mesenteric veins themselves, or by 
 means of absorbents or lacteals running to these veins, or by a communication 
 existing in the mesenteric glands between the veins and absorbents. Any one of, 
 or even all, these operations may go forward ; but that some one of them actually 
 has place in the economy, cannot be disputed, since various heterogeneous matters 
 introduced into the digestive tube, as well as chyle itself, have been very satis- 
 factorily traced into the mesenteric veins, and in the blood taken from the trunk of 
 the vena portae. The fact, that a portion of the materials taken up from the 
 digestive canal is carried directly into the blood which flows into the portal system, 
 by no means ought to preclude our belief that another, and perhaps a larger, 
 portion of the absorbed materials is conveyed through the lacteal trunks to the 
 thoracic duct. This latter Channel, however, seems insufficient for the transport 
 of the whole of the chyle anti other matters carried from the digestive organs into 
 the blood ; and when viewed as the chief road by which substances received into 
 the circulation can enter, it bears no relation either to the quantity and variety of 
 these substances on the one hand, or to the numerous sources of waste existing on 
 the other, which the former is constantly called upon to supply. 
 
 Viewing, therefore, the blood carried into the liver by the vena portae as 
 containing a considerable portion of absorbed materials, some of them of a more 
 or less heterogeneous description, others of them more or less animalised, facts 
 sufficiently proved by observation and experiment, it cannot be considered as 
 stretching the inference beyond what the laws of the animal economy seem to warrant, 
 if we conclude that these materials are assimilated with the blood chiefly during 
 their circulation in the liver, and that, in addition to secretion, this organ performs 
 an assimilating function. Notwithstanding the importance, to the pathologist and 
 practitioner, of ascertaining, as far as is in his power, the real extent of function 
 which the liver performs, it seems to have been utterly neglected. This has been 
 owing to the belief, which was long entertained, as to the medium of absorption 
 of the chyle and other materials from the digestive canal. This function being long 
 sup'posed to reside in the lacteals alone, and it being considered that the only route 
 by which fluids of any description could reach the blood from the stomach and in- 
 testines was by the thoracic duct, the lungs were considered as the only assimilating 
 organ, and no part of this latter operation was imputed to the liver, although 
 every consideration derived from its situation and comparative anatomy seemed to 
 point to it as an important instrument of the process.
 
 OF ABSORPTION IN THE LUNGS. 599 
 
 more or less quickly according to their nature, and their degree of 
 concentration. 
 
 4. This absorption is in general very great, but is less in young and 
 newly born animals than in adults. 
 
 5. Absorption takes place by the pulmonary veins, for it has oc- 
 curred in the space of three minutes; the fluids injected are found in 
 the blood before they are perceived in the chyle ; they are found in the 
 left auricle and ventricle of the heart long before the least trace of 
 them can be seen in the right auricle. Lastly, absorption is carried on 
 even although the thoracic duct be tied. 
 
 6. Absorption is likewise performed by the lymphatic vessels, but 
 more slowly. 
 
 7. The veins of the stomach and intestines also absorb, but in 
 much smaller quantities. 
 
 8. The existence of fluids absorbed by the veins can be demon- 
 strated in the blood. It is easy to discover there the prussiate of potass, 
 the muriate of iron, arsenic, &c. The prussiate of potass injected into 
 the lungs can be traced, first in the arterial blood of the heart and 
 arteries; then, if the injection be continued, in the venous blood. 
 
 9. These substances can be discovered in abundance in the urine 
 in the bladder, and in that in the kidneys. The prussiate of potass 
 can be discovered in it seven minutes after the injection. 
 
 10. The prussiate of potass is likewise deposited, and even in con- 
 siderable quantity, in the serum of the pericardium, of the pleura, of the 
 peritonaeum, in the synovia, under the skin, ard in the milk. 
 
 1 1 . When the prussiate of potass is injected, it can be discovered 
 after some hours, not only in the fluids, but also in many of the solids : 
 several of these parts then become green or blue with the muriate of 
 iron, viz. the cellular tissue under the skin, and in the whole body, the 
 fat, the serous and fibrous membranes, the aponeuroses of the muscles, 
 tendons, the dura mater, periosteum, &c. 
 
 12. The membranes of the arteries and veins, even the valves of \ 
 the heart, can be thus entirely coloured blue by the same agent. 
 
 13. The parenchyma of the liver and spleen cannot be coloured 
 blue, but sometimes the cellular tissue around their great vessels. The 
 lungs, the heart, and the kidneys, can be coloured blue. 
 
 14. The substance of the bones and their marrow, the substance of 
 the muscles and that of the brain, spinal marrow, and nerves, evince no 
 change of colour with the muriate of iron. The nerves of the brain 
 and spinal marrow seem to exert a repulsive and exclusive force, on the 
 contact of fluids foreign to their nutrition. It may be concluded from 
 this, that the opinions of many physiologists, that poisons act mortally 
 when they are applied to these parts of the nervous system, are not well/ 
 founded, and are devoid of direct proofs.
 
 600 APPENDIX. 
 
 ^ 15. These experiments may also throw some light on secretion, the 
 reproduction and nourishment of bodies ; they teach, moreover, the 
 passage of liquids from the mother to the foetus. When the prussiate 
 of potass has been administered to the mother, it can be detected in the 
 water of the amnion, in that of the chorion, and of the umbilical vesicle, 
 in the liquid of the stomach, in many solid parts of the foetus, for ex- 
 ample in the kidneys, in the stomach, &c. as also in the placenta. 
 Wheh a foetus, to the mother of which prussiate of potass has been 
 given, is placed in a mixture of spirit of wine and muriate of iron, it 
 becomes blue coloured. Thus we acquire a certain proof of the passage 
 of fluids from the mother to the foetus, a proof that has been vainly 
 sought for until now : the fluids taken into the blood of the mother 
 are deposited in the tissue of the placenta, and are thence absorbed by 
 
 1 the veins of the fcetus. 
 
 III. Of the manner in which absorption is performed, and of 
 exhalation. M. Magendie* infers that the chyliferous vessels absorb 
 chyle only, and that the veins possess the faculty of absorption. He 
 has endeavoured to disprove the absorbent power of the lymphatic 
 vessels, but in this he has not succeeded. He considers also that his 
 experiments justify him in concluding, that in all cases where artificial 
 or real plethora exists, and the veins consequently are distended, no 
 absorption takes place, or only in a slight degree, and after a greater 
 length of time than under ordinary circumstances ; whilst, when the 
 original quantity of blood is diminished by venesection, absorption 
 follows in one-fourth of the time in which it is found to occur when 
 depletion has not been previously had recourse to. He considers it, 
 therefore, to follow, that absorption is influenced by the congestion and 
 calibre of the blood-vessels. 
 
 The further pursuit of these researches led M. Magendie to the 
 conclusion, that absorption is nothing more than the well-known 
 phenomenon of capillary attraction, which takes place when tubes of 
 a small calibre are immersed in fluids, a phenomenon whose energy 
 is in a direct ratio of the affinity of the fluid for the surface of the tube, 
 and in an inverse ratio with the diameter of the latter. 
 
 " It appears to me then," he adds, " beyond doubt, that all the blood- 
 vessels, venous and arterial, whether dead or living, small or great, 
 present, in their parietes, a physical property calculated to account for 
 the principal phenomena of absorption. To affirm that this property is 
 alone able to produce all the phenomena of absorption, would be to go 
 beyond what is warranted by a correct logic ; but in the present state 
 of facts on the subject, I know not any thing which weakens the 
 
 * Journal de Physiol. Experiment No. I.
 
 OF ABSORPTION AND EXHALATION. <?01 
 
 inference that I have drawn, but many which may be adduced in 
 its support. 
 
 " By this method of explaining absorption," he observes, " we solve 
 a number of other phenomena in the living system , otherwise inex- 
 plicable ; for example, the principle on which dropsies are cured, the 
 relief from congestion and inflammation produced by blood-letting, the 
 want of efficacy in medicines during those febrile states in which the 
 vascular system is greatly distended ; the propriety of that practice which 
 institutes blood-letting and purging prior to the administration of other 
 active medicinals; the rationale of both partial and general dropsies, 
 under circumstances of cardiac or pulmonary diseases; the use of liga- 
 tures upon limbs after the bite of venomous animals, in order to prevent 
 the consequences of such accidents," &c. 
 
 That absorption takes place exclusively through the medium of the 
 veins, cannot, in our opinion, be granted to any part of the body or to 
 any organ, excepting to the brain. As respects this organ, we believe 
 that sufficient proofs exist of this function being performed entirely by 
 this set of vessels.* 
 
 This very interesting subject has been further investigated by MM. 
 Segalas and Fodera.f The latter physiologist entered upon a series of 
 experiments, which, although they appear not to us fully to substantiate 
 the opinion of M Magendie, that venous absorption takes place by 
 capillary attraction, seem, nevertheless, to shew that this process, or one 
 similar to it, actually exists to a certain extent in the living body; and 
 that though it may be subordinate to more energetic influences, it 
 should not be altogether overlooked in our inquiries into the operations 
 of the animal economy. 
 
 M. Fodera's end, in his experiments, has been to demonstrate that, 
 exhalation, which he calls transudation, and absorption, which he names 
 imbibition, are similar phenomena, proceeding from the capillary attrac- 
 tion of the parietes of the different vessels, owing to their porosity ; 
 operating, in the first case, from the interior of the vessel to the exterior, 
 and in the second, from the exterior to the interior. 
 
 M. Magendie conceived he had already proved that venous absorp- 
 tion takes place by imbibition, and came to the conclusions which we 
 have now stated. One of his experiments consisted in completely iso- 
 lating a portion of vein, and placing its surface in contact with an active 
 poison : its presence was soon discovered at the internal surface of the 
 vessel. M. Fodera then inversed the experiment. He injected a 
 poisonous substance, with every proper precaution, into the interior 
 of a portion of artery comprised between two ligatures, and isolated 
 
 * See the Note on the Structure and Functions of the Brain, 
 f Jown. de Phy.iiol. April 1822 and January 1823.
 
 602 APPENDIX. 
 
 from its cellular tissue, its lymphatics, and its vasa vasorum : poisoning 
 took place. He obtained the same result by filling with poison a 
 portion of an artery, vein, or of intestine, removing and placing them 
 either at the surface of a wound made in another animal, or in the 
 abdominal cavity. In these different experiments, the rapidity of the 
 poisoning appeared to vary according to the age and kind of animal, 
 the thickness and length of the portion of vessel or intestine, its greater 
 or less distension, the more or less perfect solution of the injected 
 matter, &c. 
 
 M. Fodera has also seen gases absorbed in the same manner. He 
 placed on the peritoneal cavity of a rabbit sulphuretted hydrogen, en- 
 closed in a portion of intestine removed from another animal ; at the 
 end of some time symptoms of poisoning manifested themselves, and 
 the sulphuretted hydrogen was no longer found in the intestine. 
 
 If, in a living animal, an artery or vein is exposed, an oozing is 
 observed to take place through its parietes. This oozing augments if 
 a ligature be applied to the vessel : different dropsies may likewise be 
 produced by the ligature of the great venous trunks. 
 
 M. Fodera concludes, from these facts, that exhalation is only a 
 phenomenon of transudation through the parietes of the vessels, as 
 many physicians had thought before the exhalent vessels were imagined. 
 
 The following experiments prove that, at least on the dead body, 
 transudation of liquids may take place at the same time from the in- 
 terior to the exterior, and vice versd, through the vascular or intestinal 
 parietes. M. Fodera rilled a portion of a rabbit's intestine with a solu- 
 tion of prussiate of potass, and plunged it into a solution of hydrochlorate 
 of lime: he introduced into another portion some hydrochloric acid, 
 and surrounded it with sulphuric acid : finally, he placed a bladder, 
 filled with tincture of turnsol, in a solution of gall nuts. Some time 
 afterwards he found in the interior of these portions of the intestine and 
 of the bladder hydrochlorate of lime, sulphuric acid, and gallic acid, 
 by the tests of nitrate of silver, hydrochlorate of barytes, and sulphate 
 of iron ; and in the liquids in which they had been immersed, prussiate 
 of potass, hydrochloric acid, and tincture of turnsol, by the tests of 
 sulphate of copper, the nitrate of silver, and by the reddish colour of 
 the solution of galls being rendered bluish by the potass. 
 
 On injecting at the same time into the pulmonary vein of a sheep a 
 solution of hydrochlorate of barytes, and one of hydrocyanate of potass, 
 into the trachea, M. Fodera also found hydrocyanate of potass in the 
 pulmonary artery, and hydrochlorate of barytes in the bronchia. 
 
 Similar phenomena may be produced upon a living animal. M. Fo- 
 dera has found, for example, in the bladder or in the thorax substances 
 which had been injected into the peritonaeum ; and in the abdominal 
 cavity substances which had been introduced into the thorax or bladder.
 
 OF ABSORPTION AND EXHALATION. 603 
 
 In these experiments he employed the solution of gall and sulphate of 
 iron, or rather the latter salt and prussiate of potass. 
 
 The black or blue colour, announcing that transudation has taken 
 place, is frequently not observed until the end of more than an hour : 
 it may be rendered almost instantaneous by putting in action the 
 galvanic influence. For this purpose, this ingenious experimenter 
 injects into the bladder, or into a portion of the intestine of a living 
 rabbit, a solution of prussiate of potass, communicating with a cop- 
 per wire ; externally, he places a cloth wet with a solution of the sul- 
 phate, communicating with an iron wire: these wires are put in contact 
 with those of the pile. If the galvanic stream be directed from the 
 exterior to the interior, by making a communication between the iron 
 wire and the positive pole, and between that of copper and the negative, 
 the tissues of the organs imbibe the Prussian blue : if the stream be 
 changed, the colour appears on the cloth. 
 
 M. Fodera injected into the left cavity of the thorax of a rabbit a 
 solution of hydrocyanate of potass, and into the peritonaeum a solution 
 of sulphate of iron ; he afterwards kept the animal placed on its left 
 side for three quarters of an hour. At the end of this period the animal 
 was opened, when he found that the whole of the tendinous part of the 
 diaphragm had imbibed the blue matter : the muscular part was much 
 less tinged, and only in isolated points. The substernal lymphatic 
 glands were likewise blue. The thoracic duct contained a bluish liquid : 
 the peritoneal membrane of the stomach and duodenum was covered 
 with spots of the same colour : they were observable, but in less num- 
 ber, on the rest of the digestive canal, and on the arteries. The lym- 
 phatic glands of the mesentery, the suspensory ligament of the liver, and 
 the epiploon, were also tinged blue. Some small sub-peritoneal veins 
 presented a slight blue coloration of the liquid contained in their interior. 
 Twelve hours afterwards, the blue tint of these different parts was much 
 more intense. 
 
 The progress of the coloration may be traced, and the phenomenon 
 in some measure be seen in its different phases, by injecting a ferruret- 
 ted solution of prussiate of potass into a portion of the intestine of a 
 living animal, tying both ends, and plunging it into a bath containing 
 sulphate of iron. At first a slight coloration only is observable in the 
 parts, which gradually becomes deeper; afterwards the liquids of the 
 lymphatics and of the blood-vessels become coloured in their turn. In 
 the latter, the coloration begins by small ramifications, and afterwards 
 extends to the branches, which are observed to be filled with intervals 
 of blood and a blue liquid. In these experiments, M. Fodera discovered 
 the presence of the prussiate of iron in the lymphatic vessels, in the 
 thoracic duct, and, finally, in the portion of the inferior vena cava con- 
 tained in the chest.
 
 604 APPENDIX. 
 
 M. Fodeca concludes, from these different experiments, 1st, that 
 exhalation and absorption take place by transudation and imbibition, 
 and depend on the capillarity of the tissues ; 2dly, that this double 
 phenomenon may take place in every part, and that the liquids imbibed 
 may be conveyed equally well either by the lymphatic vessels, or bv 
 the arterial or venous. But (the author very wisely adds) the pheno- 
 mena of exhalation and absorption ought not to be considered as con- 
 nected alone with imbibition and translation : the modifications which 
 they experience from the action of surrounding agents, from the nervous 
 influence, the state of rest and motion, the energy of the circulation, the 
 affinities of the substances with the tissues, the derangements pro- 
 duced by disease, and the elaboration which the fluids undergo whilst 
 absorption and exhalation are taking place, ought likewise to be 
 studied. 
 
 M. Fodera endeavours to explain the increase of exhalation in the 
 phlegmasiae by the dilatation which the parietes of the capillary ves- 
 sels experience ; the interstices of the fibres which form these parietes 
 become at such times increased, and consequently permit a more 
 ready issue to the fluids : the serosity and the white globules, which 
 are smaller than the red, are first effused; at last the red globules 
 themselves occasionally escape. It will be seen that this mode of con- 
 ceiving the phenomenon does not explain the infinite modifications 
 which the liquids exhaled into the inflamed parts undergo. 
 
 M. Fodera notices cases in which the lymphatics or thoracic duct 
 have been said to contain different substances, which had been intro- 
 duced either into the digesti ' canal, the serous cavities, or into the 
 cellular tissue. If the effects of absorption are not manifested in the 
 experiments, where a portion of intestine, containing poison, has no 
 longer any communication with the rest of the body, except by a lym- 
 phatic vessel, we must seek for a cause in the extreme slowness of the 
 circulation of the lymph. M. Fodera inserted some liquid prussiate of 
 potass in the subcutaneous cellular tissue of the thigh and abdomen of 
 two young rabbits. In the first animal at the expiration of a few 
 minutes, and in the second at the end of half an hour, he found it in 
 the lymph of the thoracic duct, in the urine, the mucus of the intes- 
 tines, the synovia, the serum of the blood, the serosity of the pericar- 
 dium, of the pleura and of the peritonaeum, as well as in all the solid 
 parts, except in the crystalline lens, the cerebral substance, the in- 
 terior of the nerves, and the osseous tissue. In another experiment 
 the interior of the nerves presented traces of it. 
 
 Would not these experiments tend to prove that absorption in these 
 cases had taken place at the same time, both by the lymphatics and 
 blood-vessels ? 
 
 While the German physiologists have ascribed absorption to the
 
 OF ABSORPTION. 605 
 
 absorbents and veins only, MM. Magendie and Fodera have extended 
 this function to the arteries also. In this, however, we think that they 
 have been misled by fallacies which had crept into their experiments, 
 and especially by the unnatural position and deranged actions which the 
 operations and agents required by the experiments induce in the animal 
 and in the parts experimented on. From every consideration, we are 
 led to conclude, that the inferences at which Tiedemann, Gmelin, 
 and Mayer, have arrived, approach the nearest to truth. 
 
 The experiments performed by Darwin, and more recently by Wbl- 
 laston, Brand, and Marcet, tend to prove that different substances 
 introduced into the stomach are found mixed with the urine, without 
 having passed by the lymphatic or blood-vessels. 
 
 M. Fodera has repeated these experiments, and made them undergo 
 an ingenious modification, which has discovered to him phenomena 
 unobserved by former physiologists. He introduced into the bladder a 
 plugged catheter, after having tied the penis in order to prevent the 
 urine from flowing along the sides of the sound. He laid bare the 
 oesophagus at the interior part of the neck, and injected into the sto- 
 mach a solution containing some grains of the ferruretted hydrocyanate 
 of potass. This being done, he frequently removed the plug, and 
 received on filtering paper the urine which escaped. On this paper he 
 dropped a solution of sulphate of iron, and added to it a little hydro- 
 chloric acid in order to destroy the colour. In one experiment the 
 prussiate was detected in the urine ten minutes after its injection into 
 the stomach, and in another five minutes afterwards. The animals 
 were opened immediately. The salt was found in the serum of the 
 blood taken from the thoracic portion of the vena cava inferior, in the 
 right and left cavities of the heart, in the aorta, the thoracic duct, the 
 mesenteric glands, the kidneys, the joints, and the mucous membrane 
 of the bronchia. 
 
 This important experiment proves the extreme rapidity of absorp- 
 tion ; it shews also that the prussiate of potass found in the urine is 
 conveyed thither by the ordinary circulating ways. 
 
 The following experiment demonstrates the rapidity of pulmonary \ 
 absorption in particular. M. Fodera opened the thorax of a rabbit 
 and removed the heart, immediately after some prussiate of potass had 
 been injected into the trachea. This operation was performed in twenty 
 seconds : the interior of the left auricle, however, presented a bluish 
 green colour, which was more deep at the mitral valve, and less appa- 
 rent in the aorta. The absorption, therefore, seems to take place at 
 the very instant when the injection has penetrated into the subdivisions 
 of the bronchia. 
 
 - We -are of opinion, that to limit the process of absorption in every 
 part of the body, and under every combination of circumstances to
 
 606 AP1-ENDIX. 
 
 which it is subject, to one particular process, or to one particular con- 
 formation or property which the vessels, whether blood-vessels or 
 others, may possess, would, in the present state of our knowledge, be 
 to draw an inference not justified by many important facts. On the 
 contrary, it seems more probable, that not only the vital properties, but 
 those of a physical nature, are requisite to the production of the phe- 
 nomena in question ; and that the latter set of properties are under the 
 control of the former. 
 
 Instead of attempting to shew that those physical properties for 
 which MM: Magendie and Fodera have contended, are not, to a certain 
 degree, efficient in the production of the process in question, we would 
 only argue for their subordinate character, which may be proved by 
 evidence still more incontrovertible than that which M. Magendie has 
 adduced in support of his purely physical properties : but, although the 
 vital properties are chiefly predominant in the operation, yet those for 
 which they contend may have still a place to a certain extent, which 
 extent is modified by a superior influence. 
 
 Investigations into the process of absorption have also been entered 
 upon in America. Doctors Lawrence, Coates, and others, made thirty- 
 
 -^ four experiments in which the prussiate of potass was introduced into 
 the alimentary canal : from these it appears, that articles taken into the 
 stomach may be conveyed into the circulation by three channels ; 
 namely, the vena portse, the oesophageal veins, and the thoracic duct; 
 and if all these are closed, the absorbed matters are no longer conveyed 
 
 \ to the circulation or to the urine. With regard to the quantity con- 
 veyed by each, they had no accurate means of judging. As the quan- 
 tity of fluid, however, contained in the vena portarum is so much 
 greater than in the thoracic duct, it follows, that to produce a colour of 
 equal intensity, a much larger amount of the colouring matter is requi- 
 site ; and as the serum of the blood of the vena portae gave an equally 
 deep colour, the greater proportion of the materials must have been 
 absorbed through the veins contributing to this system of vessels. 
 
 In consequence of reading the experiments of Professor Mayer, of 
 Gottingen, upon absorption in the lungs, Doctors Lawrence and Coates 
 made a few with that reference. 
 
 The animals generally died in about a minute after the injection, from 
 suffocation, by the ligatures which they placed on the tracheas of most 
 of them. These experiments, we think, go to favour the idea that 
 absorption from the mucous membrane of the lungs is performed prin- 
 cipally by the pulmonary veins. They lay particular stress upon expe- 
 riments 5th and 6th. In the first, the blood from the left side of the 
 heart indicated the agent in much larger proportion than that from the 
 right side, both being examined about the same time, viz. seven minutes. 
 In the second, where the examination was made in a much shorter
 
 OF ABSORPTION. 
 
 607 
 
 period, viz. three minutes and a half, and four minutes and a half, 
 the article was distinctly found in the left side of the heart before it/ 
 had arrived in any other part of the system. 
 
 The effects of infiltration were also remarkable in these experiments. 
 
 The results of five trials of the prussiate in the cavity of the abdomen 
 are here arranged for inspection. 
 
 Animals. 
 
 Quantity. 
 
 Thoracic Duct. 
 
 Carotid 
 and Jugular. 
 
 Urine. 
 
 Kitten. 
 
 Half ounce 
 of solution. 
 
 12 & 13 m. 
 
 distinct blue. 
 
 6 m. distinct 
 blue. 
 
 19 m. no blue. 
 
 Idem. 
 
 Idem. 
 
 4 m. blue. 
 
 2 m. no 
 blue. 
 
 10 or 15m.no 
 blue ; 29 m. dis- 
 tinct blue. 
 
 Idem. 
 
 Idem 
 nearly. 
 
 3| m. blue. 
 
 2 m. no 
 blue. 
 
 5 m. blue, not 
 strongly. 
 
 Idem. 
 
 Half ounce. 
 
 3 m. blue. 
 
 4 m. strongly 
 blue. 
 
 More than 4 m. 
 doubtful. 
 
 Cat. 
 
 I 
 
 Uncertain. 
 
 9 m. blue. 
 
 6 m. no 
 blue. 
 
 More than 9^ m. 
 no blue. 
 
 The short time in which the prussiate reached the upper part of the 
 thoracic duct in the above cases, induced them to make four other 
 trials, in order to ascertain the earliest period at which that took place. 
 Half an ounce of solution was employed in each case. 
 
 In the first animal, a kitten, the salt first arrived at the spot of ob- 
 servation in four minutes, and the quantity gradually increased till 
 seven or eight minutes. In the second kitten, it appeared in two 
 minutes : the serum of this animal gave a blue tinge. In the third 
 kitten in three minutes and a half: serum of blood also blue. In the 
 cat, it first appeared in thirteen minutes. 
 
 In these cases, the thoracic duct was cut off near its insertion, and 
 the test applied there. In consequence of this interruption, previously 
 to the prussiate arriving at the upper extremity of the duct, the dis- 
 covery of the salt in the serum of the blood clearly evinces that it was 
 conveyed there by other channels. 
 
 It is mentioned by Magendie, that he has seen, on pressing the 
 lacteal branches so as to discharge their contents in the direction of 
 the trunks, that those branches would again fill themselves after the 
 animal's death. They have also witnessed these appearances ; but they 
 do not know of any similar observations to the following made on
 
 608 APPENDIX. 
 
 the lymphatics, or of any evidence of the actual chemical presence 
 of an article conveyed after death into either of these systems from 
 without. 
 
 Four kittens were bled to what is commonly considered death. 
 The blood ceased to flow from the divided carotid, and voluntary 
 motion was extinct. Prussiate of potass in solution was then thrown 
 into the abdomen. It appeared at the thoracic duct in five and a half, 
 five, fourteen, and twelve minutes, respectively. In the two last, the 
 great vessels originating at the heart were secured by a common 
 ligature. The blue colour was in every instance perfectly distinct. 
 
 In reasoning upon the subject of absorption, the question has 
 frequently arisen, whether the articles found in the living fluids exist 
 there as chemical substances, or have their chemical nature altered 
 and animalised by the action of the vessels through which they have 
 entered the system. It was, however, deemed a curious subject of 
 inquiry, whether* artificial chemical changes can take place in the 
 fluids while they continue to circulate in living vessels, and the 
 ordinary actions of life go on. With a view of ascertaining this point, 
 they commenced by throwing prussiate of potass into the abdomen, 
 and green sulphate of iron into the cellular tissue, in order to try 
 whether the well-known result of their admixture, the prussian blue, 
 would be produced in the vessels. This, however, did not take place ; 
 and they resolved to repeat it, by throwing the sulphate, as the article 
 of more difficult absorption, into the abdomen, where this process went 
 on with more facility, and the prussiate into the cellular substance. 
 On performing this, they were gratified by the striking result of a 
 distinct and beautiful blue in the thoracic trunk and its contents, and 
 in nearly the whole substance and surface of the lungs. These viscera 
 were preserved in spirits, and are now in their possession. The blood 
 threw up a coagulum of a strong blue colour, and the lymph and 
 chyle from the thoracic duct threw down a blue deposit. Thus, not 
 only a foreign, but a pulverulent substance could present its unnatural 
 stimulus, circulate through the vessels, and accumulate in the lungs, 
 without preventing the actions of life from considerable exertion, 
 and without occasioning coagulation of blood. The animal manifested 
 some difficulty of respiration before she was killed, but walked about 
 without the least difficulty, and uttered no cries, nor other signs of 
 disturbance of its powers. In another case, the urine and lungs were 
 noted as exhibiting a blue colour. The other parts similar to those 
 above enumerated, are not described as being found coloured. In a 
 third, the fluid in the thoracic duct was blue ; but not the other fluids 
 examined, nor the lungs. Two unsuccessful trials were also made. 
 In another case the thoracic duct was tied, and the same process 
 repeated. A divided bluish green was here found in the urine; but
 
 OF ABSORPTION. 609 
 
 neither the serum of the arterial blood, nor the lymph of the ductus 
 thoracicus, manifested the blue or green.* 
 
 Dr. Barry, in his ingenious researches,! has endeavoured to prove 
 that the pressure of the air exercises the chief influence in the pro- 
 duction of absorption from the external surface of the body and 
 surface of the air-passages. In proof of this position, he adduces the 
 results of his experiments, wherein absorptioh of poisonous matters 
 inserted under the cuticle was arrested by the application of cupping- 
 glasses, from which the air was exhausted. But the effect evidently 
 depends more upon the pressure occasioned by the edges of the glasses 
 upon the parts surrounding that in which the poison is inserted, than 
 upon the abstraction of the atmospheric pressure. The rapid ab- 
 
 * The attention of the author of these Notes has long been particularly directed 
 to the modus operandi of various medicinal substances upon the animal economy ; 
 and the results of his experiments and observations led him to consider that a very 
 large proportion of those substances act upon the system by their presence in the 
 mass of circulating fluids, and by their influence on the organs, eliminating them 
 from the blood after they had been absorbed into it. Conformably with this view, 
 he published in the " London Medical Repository" for May 1822, the basis for a 
 classification of the materia medica; and he stated on that occasion, that the 
 operation of medicinal substances on the animal economy may be referred to the 
 three following general heads : 
 
 " CLASS FIRST Those substances which act on the animal economy, chiefly 
 
 from the local effects which they produce upon the textures and sentient systems to 
 which they are applied, constituting the simplest class of remedies. 
 
 " CLASS SECOND Substances which are absorbed into the circulation, and in- 
 fluence the economy, owing chiefly to their presence in the general mass of the 
 circulation, and to their operation on the organs eliminating them from the blood. 
 
 " CLASS THIRD Substances which produce effects upon the body in consequence 
 of both the primary and secondary modes of action : owing both to their local or 
 primary impression, and to their subsequent presence in the circulation and opera- 
 tion upon the eliminating organs or emunctories." 
 
 These classes were divided into orders, genera, and species; 
 
 It is not owing to the actual presence only of medicinal substances in the blood, 
 that their influence on disease is produced, but also to their operation on those 
 viscera which eliminate them from the circulation, and prevent them from ac- 
 cumulating in it to a hurtful extent. Foreign substances, when introduced into 
 the mass of blood, act upon the nervous systems, the irritable textures, and the 
 various structures and organs of the body, according to the specific properties which 
 those substances possess ; and many of them, in addition to the effects which they 
 thus produce, have a more special operation, during the process of their elimination 
 by the different emunctories of the system, upon these emunctories themselves. 
 These special or consecutive effects are chiefly evident on the urinary organs, on 
 the respiratory apparatus, the cutaneous surface, the digestive mucous surface, and 
 salivary glands. This subject cannot be farther pursued at this place; but the 
 author hopes soon to have it in his power to illustrate fully his views respecting it, 
 in a work, which is in preparation for the press. 
 
 f Experimental Researches on the Influence of Atmospheric Pressure upon 
 the Blood in the Veins. By D. Barry, M.D., &c. London, 1826.
 
 610 APPENDIX. 
 
 sorption of substances from the surface or texture of the lungs, is also 
 imputed by him to the atmospheric pressure ; but it should be re- 
 collected, that the circulation of the lungs is particularly calculated to 
 promote the speedy introduction of foreign substances, in a state of 
 solution, into the blood. Matters dissolved in a moist atmosphere, or 
 floating in it, may readily be carried into the vessels, along with the 
 constituents of the air, which are continually passing into them during 
 the process of respiration ; and many substances in a state of solution, 
 owing to their penetrating qualities, and action upon the animal 
 tissues, will rapidly find their way into the blood in this part of the 
 body; for such solutions, if inserted into the cellular tissue of the 
 organ, must come in contact with divided capillaries in the seat of 
 insertion ; and if brought in contact with the surface of the air-cells, it 
 may readily be supposed that the same conformation of parts, which 
 admits of the exhalation of the acfueous and carbonaceous constituents 
 of the blood, and the introduction of the oxygen and azote of the 
 atmosphere, will also permit the imbibition of a penetrating aqueous 
 solution. Hence foreign matters may be considered as finding their 
 way rapidly into the blood circulating in the lungs, independently of 
 their being introduced through absorbent vessels, which doubtless 
 also perform their appropriate functions in this, as well as in other 
 parts of the system. 
 
 In estimating the nature of the function of absorption, as per- 
 formed by particular sets of vessels, physiologists have erred by 
 neglecting to appreciate, in relation to the early stages of this act, the 
 effects which foreign substances have upon the different textures, both 
 during life and after its extinction. Thus saline matters in a state of 
 solution, putrid animal substances, numerous vegetable products in a 
 state of fluidity, act in a most evident manner upon the animal 
 textures, when the animal to which they belong is deprived of life, and 
 whilst they yet retain their specific characters. Saline substances 
 penetrate them quickly ; putrid animal matters rapidly destroy their 
 cohesion, and reduce them to putridity, infecting speedily their whole 
 mass ; and vegetable and animal poisons also penetrate them quickly, 
 and hasten their solution. Similar effects are observed to be produced 
 upon the textures whilst under the powerful dominion of life, although 
 in a much less degree, and generally to a limited extent. We may 
 therefore conclude, that the foreign matter having thus penetrated the 
 living textures, in the seat of contact, and its vicinity, according to its 
 characteristic effects upon them, either passes into the current of the 
 fluid circulating through the absorbent vessels and veins, owing to its 
 having thus penetrated their coats, where they may be considered as 
 possessed of the greatest tenuity, or it is absorbed by the radicles of 
 the absorbents, and conveyed by them either to the thoracic duct or
 
 OF THE ACTIONS OF THE HEART AND ARTERIES. 611 
 
 to the venous branches into which they open, or it may be imbibed 
 directly by the venous pores into the veins themselves. Either of these 
 processes may take place, according to the relation which the absorbed 
 substances may have to the living structures with which it is brought 
 in contact. 
 
 To us it appears most probable, that foreign substances do not 
 readily penetrate the internal surface of the digestive tube, owing to 
 the circumstance of this surface being protected by a mucous secretion, 
 which is not readily permeated by other fluids, unless such as possess 
 very evident penetrating properties, and active chemical relations ; 
 whilst, on the other hand, substances in contact with the mucous 
 surface of the respiratory organs, especially in the smaller divisions of 
 the bronchia and in the air-cells, where this surface is not thus 
 protected, are much more readily absorbed, and produce their effects 
 with greater rapidity. Such is the constitution of the chyle, and such 
 its relation to the other living tissues, that it cannot be readily 
 absorbed, unless by vessels such as the lacteals commencing upon the 
 mucous surface, and in the villi, by open mouths or radicles, endowed 
 with erectile or vital properties ; and, accordingly, we find that it is 
 entirely by means of the lacteals that chyle is absorbed. 
 
 OF THE ACTIONS OF THE HEART AND ARTERIES. 
 (NOTE R. See pp. 161, 166, 168, 1?2, et seq.) 
 
 I. Of the heart. Seep. 161, et seq. The muscular fibres of the 
 heart are more apparent in the foetus than in the adult ; it only parti- 
 cipates in the general paleness of muscular textures at that epoch, 
 although it is deeper coloured than they. It is also entirely without 
 fat at this period. In old age the texture of the heart becomes softer 
 and more flaccid than in the young subject, and its parietes thinner; 
 its cavities enlarge, especially the right, and its surface is more charged 
 with fat. 
 
 The nerves of the heart have been a subject of interest with phy- 
 siologists. Since they were investigated by Scarpa, opinions have been 
 tolerably uniform respecting them ; and numerous observers have proved 
 the general accuracy of his researches. The cardiac nerves are chiefly 
 derived from the ganglia of the great sympathetic ; a few also come 
 from the pneumo-gastric, but these seem rather to inosculate with the 
 former, than to go directly to the texture of the organ. The cardiac 
 ganglion, situated behind this organ, seems more particularly to pre- 
 'side over its movements, or to reinforce with additional energy whatever 
 it may receive from other sources, especially from the centre of the
 
 612 APPENDIX. 
 
 ganglial system and the other ganglia in the neck and chest. These 
 ^nerves, according to pur own observations, supply the substance of the 
 ''heart in two ways : 1st, There are numerous branches which proceed 
 from the different plexuses'directly to its muscular texture, and which, 
 dipping between the fibres, give off minute fibrillse to these fibres next 
 to them in the course of their descent into the substance of the heart. 
 2d. A large portion also of the nerves of the heart form an envelope of 
 the coronary arteries. A part of these seem to follow the arteries 
 throughout their distributions ; but, before the coronary arteries have 
 ramified to a great extent, a part of the nerves surrounding them is 
 detached to the adjoining parts, so that all the nerves which surround 
 these arteries, like a reticulum or sheath, do not accompany the rami- 
 fications of the latter to their ultimate subdivisions and terminations 
 in the veins, a portion of them appearing to be detached in numerous 
 \ and minute fibrillae to the immediately adjoining fibres. Thus it will 
 be perceived, that the muscular texture of the heart receives directly 
 and mediately a very considerable portion of ganglial nerves ; whilst 
 it may be presumed, that it also receives an accession in those fibriles 
 which terminate with the nutritious capillaries in this particular 
 structure. 
 
 The functions of the heart, it may reasonably be supposed, are 
 chiefly the result of the influence which this disposition of the ganglial 
 system of nerves bestows on its structure. In addition to the support 
 which this inference derives from the conformation of the viscus and 
 its relations with the rest of this particular system of nerves, both in 
 man and the lower animals, experiments which have been performed 
 by different physiologists prove its accuracy ;* and prove it the more 
 conclusively, inasmuch as they were performed with a view of establish- 
 ing a different proposition. 
 
 But, although the heart derives its chief influence from the ganglial 
 system, (see p. 558, par. 13, et sequen.) it is acted on through the 
 
 * Willis divided the eighth pair of nerves in the neck with a view of paraly- 
 sing the action of the heart, but death did not' supervene until some hours, and, 
 in some cases, not until several days, after the operation. In the experiments 
 of M. Le"gallois and Dr. Phillips, destruction of the brain arid spinal marrow did not 
 necessarily and immediately put a stop to the action of this viscus, although, as 
 should be expected, it was greatly influenced by the privation of a necessary and 
 an accustomed influence. In experiments which we performed on several species of 
 fishes, the actions of the heart continued long after the destruction of the cerebro- 
 spinal masses, and frequently for a short time after it was removed from the body. 
 Lastly, fretuses have been born, in which the action of the heart and circulation 
 were perfect, although they wanted both brain and; spinal chord ; and many of 
 the lower classes of animals have continued to live for a very considerable time 
 after decapitation.
 
 OF THE ARTERIES. 613 
 
 medium of the nerves which communicate between this system and the v 
 cerebro-spinal, and which seem to convey an additional influence fromA 
 the latter to the ganglia and plexuses which immediately supply the 
 heart. And as this communication is more intimate in the more perfect 
 animals, and the functions of the cerebro-spinal system are more ener- 
 getic in them, so it appears to follow, that the heart's action is more 
 readily influenced either by the increase or diminution of these func- 
 tions in them ; than in the lowest orders of animals. 
 
 Another point to which it is necessary to advert, is the question as 
 to the active dilatation of the heart a function of this viscus much in-^ 
 sisted on by Hamberger, and more recently by Carson and others. We 
 doubt not that it actually exists, to some extent, in all animals provided 
 with a perfect heart; but we do not believe that it takes place with 
 great energy. If the dilatation, however, of the heart were a mere 
 result of a relaxation of its fibres, its cavities could not be so quickly 
 and perfectly filled by the mechanical pressure of the blood directed 
 towards them, as we observe that they are ; and dilatation would be 
 only the consequence of this pressure, and be proportionate to it. But 
 this is not the case; for, as far as we could judge from observing the 
 circulation in fishes, the dilatation seems to precede the flow of blood, 
 the latter appearing as a consequence of the former. 
 
 Allowing, therefore, that the dilatation of the cavities of the heart 
 takes place to a certain extent an extent which it is difficult fully to 
 determine, but which we consider much less than that contended for by 
 Hamberger and Carson, one of the causes of the flow of blood in the 
 large veins will be apparent. 
 
 The heart is perfectly insensible in its natural state. y/This was satis- ^ 
 factorily shewn in an operation performed by M. Richerand in 1813, 
 wherein he divided the ribs, and removed a portion of scirrhous pleura, 
 thus allowing the pericardium to be exposed. The patient was perfectly 
 insensible of any impression when M. Richerand touched this organ, 
 although the pericardium, the part through which it was handled, is 
 evidently the most sensible part of it during disease : in a state of 
 inflammation its organic sensibility becomes indistinctly and obscurely/ 
 developed. 
 
 II. Of the arteries, p. 172. The arteries throughout the body* 
 are surrounded by the ganglial nerves. These nerves form a reticulum 
 around them, from which reticulum very minute fibrillse are given off . 
 and dip into their fibrous or muscular tunic. 
 
 This particular disposition of the ganglial nerves on the arteries 
 ought to be kept in recollection when we inquire into the functions of 
 'the latter. How far it tends, not only to the discharge of the more 
 manifest actions which the arterial system performs, but also to those
 
 014 APPENDIX. 
 
 insensible changes which the blood undergoes in health and in disease, 
 and to the assimilation of the chyle and other absorbed materials con- 
 veyed into this fluid, we have ventured to state at another place.* 
 We shall here merely take notice of an opinion relative to the operations 
 of this class of vessels in the circulation of the blood, lately contended 
 for by M. Magendie. This physiologist has inferred from his researches 
 on the circulation : 
 
 " 1. That neither the larger nor the smaller arteries present any 
 ^ trace of irritability. 
 
 " 2. That they are dilated during the heart's systole. 
 
 " 3. That they are capable of contracting themselves with sufficient 
 force on the blood they contain, so as to propel it into the veins. 
 
 " 4. That the blood in the arteries is not alternately at rest and in 
 motion ; but that it is, on the contrary, in a continued succedaneous 
 (by little jets) "owtion in the trunks and ramifications, and uniform in 
 the smallest ramifications and divisions. 
 
 " 5. That the contraction of the left ventricle of the heart, and the 
 elasticity of the larger a^JM smaller arteries, furnish a satisfactory me- 
 chanical reason for these phenomena. 
 
 " 6. That' the contracmm of the heart and arteries has a con- 
 ,siderable influence on the clurse of the blood through the veins." 
 
 We cannot concur in trjese conclusions, especially in the sweeping 
 inference which forms M. Magendie's fifth proposition ; and we might, 
 wfere it consistent with our limits, point out various fallacies in his ex- 
 periments, to some of which, indeed, all experiments on living subjects 
 \ are more or less liable, viz. the unnatural position of the animal during 
 S^heir performance, and more particularly as respects the operations of 
 the part immediately its subject. If M. Magendie limits the process to 
 the meeH&oical means indicated above, we would ask, how he accounts 
 for the influence of mental emotions in determining the action of the 
 vessels in particular parts of the body ? How the diversified influences 
 of numerous external agents on the circulation can be explained ? 
 Wherefore so very opposite effects are produced upon the arteries when 
 one extremity is placed in a pail of ice, and another in a pail of warm 
 water ? How can he reconcile his conclusions with the very satisfactory 
 experiments performed by Sir Everard Home, Dr. Hastings, and others ? 
 and how he can account for the determinations of blood to particular 
 parts, whilst a diminished quantity is sent to other situations ? if he 
 discard the predominating or vital power which the vessels themselves;, 
 and especially their smaller ramifications, possess in virtue of the par- 
 x ticular structure already noticed. We readily grant that the larger 
 branches of arteries evince little or no contractile action, particularly in 
 
 * See pp. 597, 598.
 
 OF THE FUNCTIONS OF THE CAPILLARIES. 615 
 
 their natural state ; but we contend that it increases as we advance to- 
 wards the extreme capillaries, the action of which derives the blood to 
 them in larger proportion, and thus increases both the mechanical and 
 vital properties of the larger branches supplying them. 
 
 We allow that the properties for which M. Magendie contends have 
 an actual place in the process of arterial circulation ; but they are not 
 the only ones ; they are insufficient of themselves to accomplish the pur- 
 poses which he assigns to them ; and, moreover, they are secondary to, 
 and controlled by, a superior influence. 
 
 From these observations it may be perceived that the arteries act in 
 the process of the circulation, not by means of a contractile action 
 similar to what is performed by the heart ; nor yet by means of elasticity 
 only; but by an organic or vital operation, which is nearly imper- 
 ceptible in the larger arterial branches, but which increases as we ad- 
 vance to the extreme capillaries ; whilst, on the contrary, the elastic or 
 mechanical properties augment as we proceed in the. opposite direction. 
 
 OF THE FUNCTIONS OF THE CAPILLARIES. 
 (NOTE S. See p. 1102.) 
 
 This class of vessels may be divided into two orders, performing dis- 
 tinct functions: 1st, Those capillary vessels between the terminations 
 of the aortic arteries and the commencement of the veins of the body ; 
 and 2d, Those between the termination of the pulmonary arteries and 
 veins of the same name. The first of these orders is disposed, in dif- 
 ferent proportions, to the compound solids of the body ; the second 
 is distributed on the surface of the air-cells of the lungs only. In 
 the one are performed changes which render the blood unfit for the 
 purposes of the animal economy ; in the other takes place an elabora- 
 tive process of an opposite nature. In the first are produced those 
 organic functions which relate more directly to the nourishment of the 
 frame, as digestion, secretion, and nutrition ; in the second, those pre- 
 paratory operations on the blood which enable the sensible and con- 
 tractile textures of the body to perform their offices. Without the 
 accomplishment of the latter, the former could not be performed ; for as 
 the former depends upon the vital influence distributed to the capillaries 
 and to their respective organs, as well as upon its state in the sources 
 whence it is derived, so does this influence itself depend upon the 
 operations which take place in the latter order of capillaries. The im- 
 portance, therefore, of these operations in the animal economy must be 
 manifest, as well as the intimate bond which unites them throughout 
 the frame : without the performance of the one class of functions, the 
 other could not be discharged.
 
 616 APPENDIX. 
 
 This part of the circulation, the most interesting, perhaps, of any to 
 the physiologist and pathologist, without being independent of the 
 heart's action, is the least under its control ; the functions of the capil- 
 lary vessels continuing to a certain extent, even after the heart has 
 ceased to contract. And, as has been shewn by some experiments* 
 performed in this country, in France, and in America, these actions are 
 not limited, even then, to the mere' circulation of the fluid which they 
 contain ; for under this particular circumstance, they may also perform, 
 for a short time, the functions of absorption and secretion. 
 
 These phenomena may be readily explained when we consider two 
 circumstances; 1st, The source whence the capillaries derive their 
 functions ; and 2d, the kind of death which the animal experiences, 
 and the order in which the different organs cease to act. We cannot 
 enter here further into this topic ; we have pointed out the way, those 
 who are interested in it will be able to pursue it ; those who are not, 
 would profit little from a lengthened explanation. 
 
 Before we leave this subject we may notice an opinion which has 
 been entertained among the most eminent physiologists. This relates 
 to the existence of subordinate sets of minute and colourless arterial 
 capillaries, each devoted to a particular function ; namely, one to nu- 
 trition, another to secretion, and a third and principal set to the trans- 
 mission of the red blood, which, in consequence of the functions of the 
 former two, have become possessed of venous properties. The first and 
 second of these sets are considered to be pellucid in their natural state, 
 and, although they cannot be satisfactorily demonstrated in this state, 
 their existence seems to be rendered probable, if not proved, by many of 
 the phenomena of disease, and by artificial injections. 
 f> Dr. Alard has lately contended for the existence of a similar set of 
 colourless vessels connected in the same manner with the veins ; and 
 that whilst those of the arteries carry the fluids intended for the nu- 
 trition of the textures, for the secretions and exhalation, these belong- 
 ing to the veins perform the functions of absorption. Some of these 
 latter vessels, whose open mouths are present every where, in the most 
 intimate textures of the organs, as well as on the surfaces of the great 
 cavities, are supposed by Dr. Alard to terminate in the parietes of the 
 adjacent veins ; while others unite and form the trunks which are 
 \generally known by the name of absorbents. The discovery of Dr. 
 Fohmann, of Heidelberg, of a communication of the lymphatics of the 
 intestines with the mesenteric veins in some animals, concurs to support 
 the proposition of Dr. Alard. On this subject Dr. Hutchinson, whose 
 physiological knowledge is of the first order, has justly observed : The 
 view of Alard, that supposing the existence of minute pellucid vessels 
 
 ' * See pp. 610613.
 
 FUNCTIONS OF THE VEINS. 617 
 
 I 
 
 springing from the parietes of the small arteries ; distributed to every 
 part of the body ; conveying different fluids, and producing different 
 effects, according as their vital properties are modified ; having corre- 
 sponding vessels, which spring from the most intimate texture of the 
 organs and surfaces of the great cavities, and unite in larger tubes, 
 forming in some instances long continuous canals, denominated absorb- 
 ents, in others running to be inserted into veins, is one which is 
 qualified to explain, more plausibly than any other, the mechanism of 
 the distribution of the fluids for the purposes of the organic functions ; 
 and is, besides, capable of obviating the difficulties which have been 
 presented by the diversity of the results of the experiments of Hunter, 
 Magendie, Brodie, and others, relative to the mechanism of absorption.* 
 
 OF THE VEINS. 
 (NOTE T. See pp. 184, 186, 189.) 
 
 1. As to the precise way in which the veins commence, opinions 
 have been various. At the place where the capillaries change from 
 arteries into veins, there appears to be no reason to suppose the 
 existence of either interspace, or vesicular or spungy structure. The 
 inflected canal of the artery seems to be continuous with the vein. 
 Whilst, however, this conformation is allowed by nearly all, some con-^ 
 sider, with Mr. Ribes, that the veins have another commencement in 
 addition to this ; and that a certain proportion of their radicles com- 
 mence in open mouths or in the pores or areolse of the laminous tissues, 
 and in the substance of the organs. Others also suppose, with M. 
 Alard, f that some of their roots commence in pellucid lymphatic^ 
 absorbents. 
 
 The structure of the erectile tissues, as the penis, the clitoris, the 
 spleen, &c. seems to support the opinion of M. Ribes, (which is also 
 that of M. Meckel,) who farther supposes that one cause of the difference 
 
 * See the Note on Absorption. 
 
 Admitting fully the justness of Dr. Hutchinson's remarks, we must observe, 
 that the existence of the sets of capillaries here contended for by Dr. Alard is not 
 proved demonstratively. Indeed, we possess this species of proof in favour only of 
 one set of capillaries, namely, those which constitute the termination of the 
 arteries and commencement of veins. We know that secretion, nutrition, and ab- , 
 sorption, are functions of capillary vessels. This has always been granted, from the " 
 time of Hippocrates; but there have been various instruments allotted to the 
 process ; some physiologists insist, with Dr. Alard, upon the existence of subordinate 
 sets of capillaries allotted to each function ; whilst others contend, with M. Richerand, 
 that they take place through the medium of lateral pores in those capillaries which 
 communicate directly between the arteries and veins. These veins will come under 
 consideration in the notes in this Appendix on Secretion and Nutrition. 
 
 f See the preceding Note.
 
 618 APPENDIX. 
 
 of the appearance and functions of organs maybe ascribed to the extent 
 to which the veins originate in the particular manner for which he 
 contends. 
 
 /* The views of M. Alard derive their chief support from the phenomena 
 connected with absorption ; but, although they appear probable, they 
 cannot be fully demonstrated. 
 
 The veins receive but a small proportion of nerves, and these are 
 chiefly from the ganglia. The nerves supplying the pulmonary veins 
 come principally from the anterior pulmonary plexus. 
 
 2. The functions of the veins are, 1st, to bring back the blood 
 from the capillaries to the heart ; 2d, to receive and assist in the as- 
 similation of the fluids, which are absorbed by the lacteals and absorb- 
 ents ; and 3d, in certain situations, and under certain circumstances, 
 to co-operate in the function of absorption. 
 
 The first of these operations is performed by means of the vital 
 action with which the veins are endowed, assisted by the vis & tergo 
 proceeding from the vital action of the capillaries, by the contraction 
 of the surrounding muscles viewed in connexion with the direction of 
 valves, with which they are provided, by the pressure of the atmosphere 
 upon the surfaces of the body, and by the active dilatation of the 
 cavities of the thorax and heart, which draws the blood into the large 
 venous trunks and auricles. 
 
 The third action of the veins, or venous absorption, seems to be 
 proved by the researches already detailed.* The venous radicles, 
 either immediately or mediately, seize the absorbed materials, and con- 
 vey them into the current of the circulation. This seems to be a vital 
 or organic action, which is probably assisted, in some parts of the body, 
 and under certain circumstances, by the physical property of imbibition, 
 or capillary attraction, which all animal textures evince in a greater or 
 less degree, even during life, according to the penetrating properties of 
 the substances absorbed. It should, however, be recollected, that this 
 physical property is a very subordinate one to vitality, is entirely under 
 its control, and takes place very imperfectly when this influence is in full 
 vigour. 
 
 The second function of this class of vessels is the admixture of the 
 absorbed" vessels, and the assimilation of them. The former or me- 
 chanical part of this function is performed generally throughout the 
 body, although it takes place to a greater extent in some instances than 
 in others, as in those viscera in which the blood circulates more imme- 
 diately after it has received the chyle and lymph from the lacteal 
 absorbents and thoracic duct. Hence it chiefly takes place in the 
 heart itself, and in the liver and lungs. The latter part of this function, 
 
 See Absorption, in the APPENDIX.
 
 MECHANISM OF THE RESPIRATORY ORGANS. 619 
 
 the assimilation and animalisation of the absorbed matters, is essen- 
 tially a vital action, and appears to us to result from the vital influence 
 derived from the nerves with which the blood-vessels are provided. 
 Supposing this position to be correct, we should expect that the vessels 
 in which this process takes place would be most abundantly supplied 
 with those nerves whence we consider the assimilating influence to 
 proceed. Now this is actually the case ; the blood which is carried 
 into the portal veins contains a larger proportion of absorbed and im- 
 perfectly assimilated materials than the blood in any other organ ; and 
 this particular order of veins, whose office it is to assimilate them, and 
 to eliminate the effete elements from the circulating fluid, is provided 
 with a much greater number of ganglial nerves than any other part of 
 the venous system ; and, indeed, even more than the arteries in some 
 situations. This particular set of veins, therefore, performs a double 
 function, viz. of assimilation, and of secretion ; in the latter action, 
 however, it may only participate with the hepatic artery ; for, as the 
 hepatic vein returns the blood of both the vena portse and the artery, 
 the biliary secretion may, probably, not take place until the termin- 
 ating capillaries of both have given rise to the radicles of the vein. 
 
 . Assimilation goes on in the next degree of activity in the lungs, 
 and more or less partially in other organs of the body. 
 
 OF THE MECHANISM OF THE RESPIRATORY ORGANS. 
 (NOTE U. See pp. 196 et seq.} 
 
 I. Of the structure of the lungs. According to the observations 
 of M. Magendie, the cellules of the lungs do not appear to be arranged 
 in a methodical manner, nor to have membranous parietes. With 
 respect to the non-existence of the latter, we think that he was betrayed 
 into error by the method of investigation which he adopted.* These 
 cellules seemed to him to be formed solely by the minutest and last 
 ramifications of the pulmonary artery ; by the radicules of the veins of 
 the same name, which are a continuation of the former ; and lastly, by 
 the numerous anastomoses of all these vessels. These cellules are sepa- 
 rated into many distinct lobules, in each of which the cellules commu- 
 nicate among themselves; while between the lobules there is no com- 
 munication. 
 
 The number of cellules is in an inverse ratio to the age of the ^ 
 subject ; consequently, the older the person, the larger is each cellula, 
 or, what comes to the same thing, the fewer are the cellulse. 
 
 It follows, therefore, that the lungs become specifically lighter as 
 
 * He partially filled the lungs by insufflation after their removal from the sub- 
 ject, and allowed them to dry. When quite dry, he found this sort of preparation 
 to be nearly transparent, and readily cut into thin slices with a knife.
 
 620 APPENDIX. 
 
 '/ we advance in life ; and in support of the correctness of this inference, 
 M.M. states that he found, by actual experiment, that, in equal volumes, 
 a portion of the lungs of a man at seventy was fourteen times specifi- 
 
 \ cally lighter than that of a child a few days old. 
 
 The most accurate description of the bronchia and air-cells of the 
 
 / lungs is given by Reisseisen.* He states, 1st. That the ramifications 
 of the bronchia are more and more numerous as they decrease in 
 diameter ; and that the ultimate twigs end in close bulbous extremities, 
 or air-cells, and that these cells do not communicate with each other 
 directly, but only through the medium of the extreme twigs, of which 
 they are the terminations. 2d. That these ramifications and cells, as 
 proved by Malpighi, have no communication with the surrounding cel- 
 lular substance. 3d. That these ramifications and cells consist, 1st, of 
 mucous membrane ; 2d, of a coat of elastic white fibres, on which the 
 elastic properties of the bronchial ramification depend ; 3d, of muscular 
 fibres, placed transversely, relatively to the course of these canals. 
 4th. That the ramifications of the bronchial and pulmonary arteries 
 freely anastomose both in the air-passages and in the surface of the 
 lungs, and that the bronchial arteries chiefly run direct to the pul- 
 monary veins. 5th. That the air-passages and blood-vessels of the 
 lungs are most abundantly supplied with nerves from the par vagum, 
 whose conjunctions with the sympathetic take place externally to the 
 N lungs. 
 
 II. Of the action of the glottis. M. Bourdon f considers that the 
 glottis performs the following functions, in addition to those which are 
 requisite to the formation of the voice. 
 
 1. That it is the glottis which suspends respiration during con- 
 siderable efforts, in opposing by its closure the escape of the air con- 
 tained in the lungs. 
 
 '/ 2. Without the glottis, the action of the abdominal muscles 
 would be constantly employed in producing respiration : neither com- 
 \ pression of the viscera, nor flexure of the trunk, could be produced. 
 
 3. There exists a real consensus of action between the glottis and 
 the abdominal muscles, and, through this medium, between the glottis 
 and the different reservoirs, the bladder, the rectum, the stomach, and 
 the uterus. 
 
 4. The glottis does not confine its action to the production of the 
 voice ; but by the aid of the sympathetic connexions which unite it to 
 
 * F. D. Reisseisen, M.D., Strasburg. Uber den ban der Lungen, eine von der 
 Koniglichen Academic der Wissenshaften zu Berlin gekronte Preisschrift. Berlin, 
 1822. 
 
 f Recherches sur le Mtchanisme de la Respiration, #c. Paris, 1820.
 
 ACTIONS OF THE RESPIRATORY ORGANS. 621 
 
 the abdominal, muscles, charged to concur in, if not to preside over, 
 important functions, it excites the greatest influence on those functions 
 themselves. 
 
 5. Lastly, in the different efforts there is a tendency to expiration, 
 to the production of which the closure of the glottis is an obstacle. 
 
 III. Of the state of the lungs during respiration. According to 
 Dr. Carson, a principal part of the mechanical operation of respiration 
 is performed by the lungs themselves, and as follows : After pre- 
 mising that the substance of the lungs is possessed of elastic properties, 
 and is kept in a state of distension after birth by atmospheric pressure,* 
 Dr. C. considers that, during inspiration, the intercostal muscles raising 
 and drawing out the ribs, and the diaphragm contracting and descend- 
 ing, create a tendency to vacuum in the thoracic cavities, by enlarging 
 their capacity : but this vacuum is prevented by the rushing of the air 
 into the lungs, the pressure of the air overcoming the elasticity of the 
 organ, and causing it to fill the enlarged thorax. Inspiration is thus 
 effected. But the diaphragm and intercostal muscles having enlarged 
 the thorax, and ceasing to act, the substance of the lungs is enabled 
 to exert its elasticity, recovers its dimensions, and thus expels the 
 additional volume of air just inspired, the passive respiratory muscles 
 following the collapsing lungs, owing to the atmospheric pressure in 
 the external surface of the trunk. Expiration is thus produced. 
 
 Dr. Carson seems to err in imputing the function entirely to the 
 causes now stated, and explaining expiration by means of the elasticity 
 of the lungs only. The elastic property of the organ certainly, exists to a 
 small extent, and performs its part in the operation ; but to us it seems 
 to be merely a part, and that a small one; for the imiscular con- 
 traction of the bronchia, as instanced by Haller and Reisseisen, have 
 evidently a share in producing the phenomenon, as well as the elasti- 
 city of the cartilages, and the contractions of the abdominal muscles, 
 as contended for by those who explained the mechanism of the func- 
 tion before the time of Dr. Carson. It should, however, be stated, 
 that the cartilages of the ribs are liable to ossification, and that the 
 abdominal muscles are nearly passive, unless during forced expirations,/ 
 when the lungs are emptied to the utmost. 
 
 The experiments and opinions of Dr. Carson have had the effect of 
 directing the attention of physiologists to the state of the lungs them- 
 selves during respiration, and under the various influences to which they 
 
 * As admitted by Haller and other physiologists, and as shewn by experiments 
 on various animals, and by puncturing the walls of the thorax ; when the lungs, if 
 healthy, always collapse, the atmospheric pressure within and without the lungs 
 being then balanced.
 
 622 APPENDIX. 
 
 are usually subjected either by accident, by operations, or by disease. 
 Dr. Carson had inferred from his experiments, that it is possible to 
 collapse one of the lungs, and to retain it in that state ad libitum, by 
 keeping open the communication between the cavity of the chest and 
 the external air ; and further, that upon allowing the opening to close, 
 the lung, in a given time, will recsver its wonted function, thereby 
 rendering it practicable, when conceived necessary, to place the oppo- 
 site lung under the like discipline. In order to examine the stability of 
 these inferences, Dr. David Williams, of Liverpool, instituted several 
 experiments, in the presence of Dr. Trail and others, which con- 
 tradict some of the chief positions held by Dr. Carson. After de- 
 / tailing his experiments, Dr. Williams draws the following conclusions 
 from them : 
 
 1 . That a lung will not collapse from exposure to the atmosphere 
 as long as respiration is carried on by the opposite one, and the auxiliary 
 respiratory powers are not restrained. 
 
 2. That a lung possesses for a time, independently of the influ- 
 ence of the diaphragm and intercostal muscles, if respiration is carried 
 on by the opposite lung, a peculiar motive power, the source of which 
 I do not pretend to explain. 
 
 3. That a sound lung soon regains its full power of expansion, 
 when the pressure of the exterior air is removed. 
 
 4. That air freely and uninterruptedly admitted into both cavities 
 of the chest simultaneously, through tubes of a certain calibre, will 
 not collapse the lungs, if the auxiliary respiratory organs are un- 
 restrained. 
 
 5. That air admitted into both the cavities of the chest (of a 
 middle-sized dog) simultaneously through apertures of an inch and 
 better in length in the intercostal spaces, will not collapse the lungs, 
 provided the animal is allowed unconfined the use of his respiratory 
 organs. 
 
 6. That a sound lung never fills the bag of the pleura. 
 
 IV. Of the effects of respiration on the circulation of the blood, 
 especially through the veins. The experiments of Haller, Lamure, and 
 Lorry, and subsequently those of Cloquet and Bourdon, have shewn, 
 
 1. That, during inspiration, the blood of the vena cava, superior 
 and inferior, is drawn towards the heart. 
 
 2. That, during expiration, the blood is, on the contrary, driven in 
 the same veins towards the viscera. 
 
 3. That the arterial blood is also driven towards the viscera at the 
 time of expiration. 
 
 4. That the alternate motions of the brain are owing to the changes 
 caused by respiration in the flow of blood.
 
 ACTIONS OF THE RESPIRATORY ORGANS. 623 
 
 5. That all these changes are but little marked in ordinary respira- 
 tion ;, but that they become very evident in full respirations, and parti- 
 cularly so during great efforts. 
 
 6. Lastly, that during great efforts the glottis is firmly closed, the 
 air contained in the lungs is compressed, as well as all the pectoral and 
 abdominal viscera. 
 
 In order to ascertain the precise effects produced by respiration on 
 the venous circulation, M. Magendie instituted a set of experiments 
 from which he draws the inferences, that respiration modifies the ve- 
 nous circulation ; 1st, by the influence which it exerts on the course of 
 the arterial blood ; 2d, by its direct action on the current of blood in 
 the veins. That in profound respirations and violent efforts, the circula- 
 tion appears nearly suspended. 
 
 The six propositions given above, seem to convey a brief and cor- 
 rect statement of facts. The inferences of M. Magendie are perhaps 
 carried a little too far. The pressure of the atmosphere upon the sur- 
 faces of the body, and the actions of respiration, have been adduced by 
 Dr. Carson and Dr. Barry to explain the phenomena of the venous 
 circulation, and whatever suctive action the heart may exert. That the 
 atmospheric pressure remaining constant on the body generally, while 
 it is slightly diminished about the heart, during inspiration, produces a 
 small disturbance of the uniformity of the venous current near the 
 chest, has always been admitted, as just stated ; but that this circum- 
 stance is productive of effects such as Dr. Carson and Dr. Barry impute 
 to it, cannot be allowed. Dr. Barry considers that, in consequence of 
 the enlarged state of the thoracic parietes during inspiration, and ten- 
 dency to a vacuum, the pericardium is drawn out, and with it the 
 parietes of the venous sinuses 'of the heart, and the large veins, just 
 before they open into these situations. Hence the blood during every 
 inspiration rushes into these parts, which become the reservoir from 
 whence the cavities of the heart are replenished ; and the suctive influ- 
 ence thus occasioned in consequence of the pressure of the air being 
 thus taken off this part of the vascular circle, being the cause of both 
 the progression of the blood in the veins, and of absorption. 
 
 That some slight influence of the kind now stated may be occa- 
 sioned by the violent and forced respirations observed in the living 
 animals on which Dr. Barry performed his experiments, we will not 
 dispute ; but we believe that, during the healthy and usual state of 
 respiration, little or no effect upon the circulation beyond what was 
 already admitted, is actually produced ; for we believe that no such 
 tendency to vacuum is ordinarily occasioned in a healthy state of the 
 lungs, and whilst, from the pressure of the air within them, they are 
 e'nabled to follow the motions of the respiratory apparatus. 
 
 Upon this subject, the remarks of Dr. Arnott, in his valuable
 
 624 APPENDIX. 
 
 work,* seem to us, upon the whole, correct, although even here various 
 concomitant relations are overlooked. This author states it to be " a 
 physical impossibility, that a sucking action of the heart or chest can be 
 a cause of the blood's motion along the veins. 1st. The veins are 
 pliant tubes, free to collapse, and no pump can lift liquid through 
 such. 2d. The suction power of the chest in healthy respiration is 
 too weak to lift liquid even one inch through tubes of any kind." 
 
 In respect of the first proposition, we grant its accuracy upon the 
 main ; but it should, in justice to the exact state of the case, be re- 
 membered, that the parietes of the veins are so intimately connected to 
 the parts surrounding them, as to furnish a mechanical resistance to 
 collapse from a slight suctive influence, and that hence such influence 
 may be productive of a slight or partial effect, especially when the 
 vessels are kept full at the time of its operating by other causes, as 
 the vis a tergo, and the vital influence of the system, which latter has 
 been too much kept out of view, both by Dr. Barry and by Dr. Arnott. 
 As to the second proposition, we do not dispute its accuracy. 
 
 There are various circumstances which militate against the hypothesis 
 of Dr. Barry, besides the fundamental one now alluded to, such as the 
 circulation and absorption in the foetus, the circulation in the vena 
 portse, and the circulation in animals not possessing one distinct respi- 
 ratory cavity. 
 
 V. Of the effects of suspended respiration on the circulation.- 
 From the experiments which were made by Dr. Williams, of Liverpool, 
 on this subject, he deduces the following corollaries : 
 
 1. The blood is obstructed in its passage through the lungs, on 
 suspension of respiration, while its circulation through the other parts 
 of the body continues. 
 
 2. The obstruction of the blood in the lungs, on suspension of 
 respiration, is not occasioned by a mechanical cause. This is proved 
 by the flow of blood through the lungs being suddenly arrested, 
 without any subsidence of this organ, while the circulation was carried 
 on vigorously through the other parts of the body, in the experiments 
 detailed by the author. 
 
 3. The obstruction of blood in the lungs, on suspension of re- 
 spiration, arises from the deprivation of pure atmospheric air. 
 
 4. The blood which is found post mortem in the left auricle and 
 ventricle is the remnant after the last systole, and the subsequent 
 draining of the pulmonary veins. 
 
 / 5. The obstruction of blood in the lungs, on suspension of re- 
 
 * Elements of Physics, or Natural Philosophy, General and Medical, &c. By 
 Neil Arnott, M.D., &c. London, 1827- p. 528.
 
 OF THE .FUNCTIONS OF THE LUNGS. 625 
 
 spiration, is one of the principal causes of the vacuity after death of ^ 
 the system circulating arterial blood. 
 
 6. The immediate cause of the cessation of the action of the heart 
 is a privation of its natural stimulus, arising from the obstruction of 
 the blood in the lungs.* 
 
 OF THE CHANGES INDUCED ON THE AIR AND THE BLOOD 
 BY RESPIRATION. 
 
 (NOTES W. See pp. 205216, 222, 274.) 
 
 1. Of the production of carbonic acid during respiration. The 
 experiments of Mr. Ellis and others have led physiologists to conclude, 
 that oxygen is not absorbed by the blood in the lungs from the air 
 during respiration, but that the blood gives off its superabundant carbon 
 from the surface of the air-cells, and the carbonic acid is thus formed in 
 the lungs themselves. 
 
 This mode of accounting for the changes induced upon the air and 
 upon the blood during respiration, has been very generally adopted in 
 this country ; while the former mode of explaining the process (that 
 which is given in the text) has still been received, with various mo- 
 difications, on the continent. 
 
 It appears to us that the production of carbonic acid gas by the 
 respiratory function has been ascribed too exclusively to one of the 
 above processes ; and that it has been too generally viewed as 
 altogether a chemical phenomenon. When the theory of the ab- 
 sorption of oxygen was dismissed, in favour of that which contended 
 for the discharge of carbon from the blood, either in its pure state, or 
 in that of a hydrate, no participation in the process by which the 
 carbonic acid is formed, was allowed to the previously received 
 opinion : however, it still appears a matter of doubt how far either 
 function predominates ; for we are inclined to think that both ope- 
 rations go on simultaneously, and that, whilst a portion of the* 
 carbonic acid gas is given out from the blood, already formed, it is 
 accompanied with another portion of free carbon, or an oxide of 
 carbon, or even with a hydrate of the same substance, which 
 combines with an additional quantity of oxygen in the lungs, and thus 
 forms the whole of the carbonic acid in question ; and that, at the 
 same time, a portion of oxygen is absorbed, which combines with the 
 carbon in the blood, and there generates the carbonic acid gas, or the 
 oxide of carbon, which forms a part of the matters discharged from the 
 
 Annals of Philosophy, Sept. 1823.
 
 626 APPENDIX. 
 
 blood in the lungs. These processes may vary, and either may pre- 
 dominate, according to the state of the vital influence at the time, 
 under whose control they are immediately and completely placed. 
 
 This view of the phenomenon in question seems to be fully supported 
 by the experiments of Dr. Edwards, of Paris. They prove that the 
 carbonic acid gas does not form instantaneously in the lungs through 
 the action of the respired air ; but that it appears to be secreted to a 
 considerable extent from the blood in the respiratory organs. 
 
 As to the quantity of this gas which is formed during respiration, 
 different physiologists have estimated it differently. Godwin con- 
 sidered that for every 100 cubic inches of atmosphere respired, there 
 were given off 10 or 11 of carbonic acid. Menzies, from experiments 
 made with much accuracy, found the quantity of carbonic acid to be 
 about 5 in the 100. Dr. Murray considered it to vary from 6 to 
 6-5. Sir H. Davy from 3'95 to 4-5. Messrs. Allen and Pepys from 
 3*5 to 9'5. They estimated the mean at about 8. Dr. Prout found it 
 to be about 3-45. Dr. Fyfe about 8-5. The discrepancies which are 
 remarkable in these results of the experiments performed by these 
 physiologists, doubtless arose, in a great measure, from the different 
 proportions of this gas produced by different individuals, according to 
 the state and developement of the lungs, and according to the par- 
 ticular circumstances of the individual at the time of the experiment. 
 
 The influence which the state of the individual exerts upon the 
 function was first shewn by the experiments of Dr. Prout and 
 Dr. Fyfe. They proved that the carbonic acid gas formed during 
 respiration is liable to be very materially affected in its quantity in 
 the same individual, by various circumstances. It was formed in a 
 minimum quantity during the night ; and the maximum quantity, 
 which was generally produced about noon, exceeded the minimum about 
 one-fifth of the whole. The passions of the mind were found to have a 
 great influence over its production ; the depressing passions diminishing 
 its quantity, and those of an opposite nature the reverse ; exercise, 
 when moderate, appeared to increase in some measure the quantity, 
 but fatigue diminished it. The greatest decrease experienced was 
 from the use of alcohol and vinous liquors, especially when they were 
 taken upon an empty stomach. In short, whatever diminished the 
 powers of life, as low diet, mercurial irritation, &c. appeared, from the 
 experiments of Dr. Prout and Dr. Fyfe, to have the effect of di- 
 minishing the quantity of the carbonic acid. 
 
 Dr. Crawford found the quantity of this gas was much diminished 
 when respiration was performed in a high temperature ; and Lavoisier 
 and Seguin confirmed his observation. Nearly similar results to theirs 
 were obtained from some experiments which we performed in 1815;
 
 OF THE FUNCTIONS OF THE LUNGS. 627 
 
 and from the data thus obtained, we endeavoured* to account for 
 several of the most important diseases to which the inhabitants of warm 
 countries are liable. Similar experiments were afterwards performed 
 in an intertropical climate, where we found the diminution of the 
 quantity of carbonic acid to be considerably greater than that which 
 our experiments in an artificial temperature of equal elevation had 
 furnished. This seems to be accounted for by the depressing influence 
 upon the nervous system which the atmosphere, loaded with moisture 
 and malaria, may be reasonably expected to produce. We also 
 attribute a share of this discrepancy to the increased function of the 
 skin, which evidently co-operates in hot climates with the lungs, and 
 performs a subordinate respiratory function. In some comparative 
 experiments made by us on that occasion, both on our own respiration, 
 and on the respiration of a negro having a chest of about equal 
 capacity, we found that the quantity of carbonic acid formed during 
 respiration, in a given time, was much greater in our case than in that 
 of the negro; and that the carbonic acid formed upon the cutaneous 
 surface of his body exceeded that formed on ours in about the 
 proportion of 3 to 2. We shall not pursue this particular topic farther 
 at this place, as we propose considering it more at length on a future 
 occasion. 
 
 Reverting to the question, whether the carbonic acid is formed 
 within the vessels or without them, we must remark, that the 
 evidence on the subject is very contradictory. The experiments of 
 Dr. Edwards, already referred to, shew that the former process exists, 
 at least to some extent; and it is farther supported by the fact, 
 established by Berzelius, that blood, especially its colouring part, not 
 only absorbs oxygen very quickly, but it also retains some part of the 
 carbonic acid thereby produced ; but whether or no this absorption will 
 take place through the parietes of the capillaries, is the point at issue. 
 The evidence for the absorption of oxygen through the capillary 
 parietes, is, however, nearly on a par with that for the excretion of the 
 carbon ; if the vessels will permit the transmission of the one, they 
 may allow the transit of the other. 
 
 Those who contend for the passage of the carbon from the vessels, 
 and who, consequently, consider that the carbonic acid is formed 
 externally as respects the vessels, support their opinion by the ex- 
 periments of Mr. Ellis, who first promulgated the doctrine. His 
 experiments were, however, performed out of the body, and under 
 circumstances which entirely excluded the operation of the vital in- 
 fluence of the lungs, and of the system generally. 
 
 The' most conclusive experiments in favour of this opinion are 
 
 * These views were contained in a Latin thesis written at Edinburgh in 1815.
 
 628 APPENDIX. 
 
 .those performed by MM. Magendie and Orfila. They found that 
 phosphorus, dissolved in oil, and injected into the jugular vein of a 
 dog, was expelled by the mouth and nostrils in the form of copious 
 vapours of phosphorous acid ; which could hardly have been the case if 
 the phosphorous acid had been formed within the vessels, as in this 
 case it would have remained in solution in the blood, it not being a 
 volatile substance. It might, therefore, be supposed that the phos- 
 phorus was excreted in a state of minute division from the vessels 
 of the lungs, and meeting in this state with the oxygen of the 
 atmosphere, formed the phosphorous acid in question. If this rea- 
 soning be admitted with respect to phosphorus, it may be extended to 
 the carbon contained in the venous blood. 
 
 From the contradictory evidence on the subject ; from the nature 
 of that evidence; from the experiments of Dr. Edwards; from various 
 analogies that might be adduced, could our limits permit, from the 
 conformation of the lungs, and the extent of their excreting and 
 absorbing functions, as evinced by experiments ; and lastly, from the 
 consideration that, although respiration takes place frequently, yet a 
 very large portion of air remains for a considerable time in the chest, 
 thereby allowing the vitality of the lungs themselves to be exerted 
 upon the air contained in them, we conclude that this organ may 
 act in both the ways contended for ; and that, whether it act in one 
 manner or the other, more or less partially, the process is a vital one, 
 and whatever chemical laws may be employed in it are under the 
 control of the vital influence of the organ, and modified by the ever- 
 varying condition of this influence. 
 
 II. Of the absorption and exhalation of azote during respiration, 
 Another subject of much interest, connected with the respiratory 
 function, is that which immediately relates to the absorption in the 
 lungs of a portion of the azote contained in the respired air. On this 
 point, also, the results of experiments have been various, and opinions 
 respecting them equally so. Dr. Edwards, of Paris, who is well 
 known as a very able and intelligent physiologist, concludes, from 
 different experiments, and from the circumstance of the opposite 
 results which they give, some indicating a diminution of the azote of 
 the air, others an increase of it during respiration, that this gas is 
 absorbed into the circulation, and afterwards discharged from it; and 
 that each of these actions is regulated by the constitution, habit, and 
 circumstances of the individual, and by the influences to which he 
 may be subjected ; the absorption being to a small extent, while the 
 exhalation is considerable, and vice versd. 
 
 Independently of the satisfactory nature of the experiments whence 
 Dr. Edwards has drawn his inferences, there are many collateral proofs
 
 OF THE FUNCTIONS OF THE LUNGS. 629 
 
 that may be brought to their support, derived from the manifestations 
 of the animal economy in health and in disease ; and we have little 
 doubt, that not only azote, but that other gases, even those whose 
 presence in the respired air are accidental, may be also absorbed into, 
 and discharged from, the circulation, in a greater or less quantity, 
 according to the varying state of the vital energies of the system. 
 
 III. Of pulmonary transpiration. The mucous membrane of the 
 lungs gives off a considerable portion of the watery secretion, which 
 is carried out of the lungs, in the form of vapour, by the respired 
 air. This perspiration equally takes place when the animal breathes \ 
 a gas containing neither oxygen, hydrogen, nor azote; it there- 
 fore does not result from the combination in the lungs of the hy- 
 drogen contained in the blood with the respired air ; but is strictly an 
 aqueous vapour, slightly charged with animal matter, and is the pro- / 
 duction of a vital transpiration or secretion. 
 
 It has not been determined whether or no it be produced from the 
 bronchial or from the pulmonary arteries. The question is difficult to 
 decide, as an injection thrown into either set of arteries arrives 
 on the surface of the air-cells. Pulmonary transpiration may con- 
 tain, like secretions, foreign matters which have been conveyed into 
 the circulation ; the lungs acting as an organ eliminating them from 
 the system. This has been shewn by some experiments of M. Ma- 
 gendie ; and also in experiments which we performed, especially one, 
 in which ten drachms of the oil of turpentine were chiefly discharged 
 by the lungs from the circulation in the state of vapour, within twenty- 
 four hours.* The large quantity of the turpentine vapour evolved from 
 the lungs on that occasion, leads us to suppose that transpiration 
 takes place principally from the venous blood, about the time when 
 the changes are effected in it by respiration. This experiment also 
 seems to support the doctrine of the evolution of carbon from the / 
 blood. 
 
 IV. Of the assimilating function of the lungs. The extent of the 
 function of the lungs has been a matter of doubt. Their principal 
 office, namely, that of changing venous into arterial blood, has always 
 been admitted, although the nature of the process has been disputed. 
 Many physiologists have, in addition to this, attributed to them an as- 
 similating influence which is exerted chiefly upon the absorbed chyle 
 and lymph which the venous blood contains. This opinion appears 
 correct. But the process is purely a vital one. If the opinion of 
 
 * Fer the particulars of these experimeuts, see the Medical and Physical Jour- 
 nal, vol. xlvi.
 
 630 APPENDIX. 
 
 Dr. Edwards respecting the absorption and exhalation of azote be cor- 
 rect, this substance may be instrumental in the process. 
 
 A third function has been referred to this organ, viz. the formation 
 of animal heat. But however intimately related it may be with the 
 respiratory process, it cannot be considered a function of the lungs. 
 It must, nevertheless, be allowed, that the changes induced upon the 
 blood during respiration are preparatory to the evolution of animal 
 heat ; and although we contend that this heat is immediately the re- 
 sult of a manifestation of the vital influence of the ganglial system of 
 nerves, exerted upon the blood contained in the vessels to which these 
 nerves are distributed, yet it must be admitted, that the respiratory 
 processes are necessary to its production, inasmuch as they produce 
 on the blood a change of properties, which are requisite to excite this 
 system, and as this fluid, when thus changed, contains the materials 
 necessary to, or is otherwise in a suitable condition for, the manifesta- 
 tion of the influence which that part of this system of nerves that is 
 distributed to the blood-vessels exerts. 
 
 OF THE PRODUCTION OF ANIMAL HEAT. 
 (NOTEY. See pp. 211, 215.) 
 
 It is not necessary to add at this place much to what is contained in 
 the text, and to what we have said at page 562, and towards the 
 conclusion of the preceding note. It will there be perceived that 
 we have attributed the production of animal heat to the vital influ- 
 ence exerted by that part of the ganglial system distributed to the 
 arteries on the blood which they circulate. 
 
 Preparatory changes, however, take place in the lungs, which are 
 necessary to the exertion of this influence, and to the evolution of 
 heat ; but as it was contended that those changes are more of a vital 
 than of a chemical nature, so it is considered that the production of 
 heat is more the result of the influence which the soft nerves supplying 
 the vessels exert upon the blood, than of the change in the capacity for 
 caloric which the blood itself experiences in its passage into the venous 
 state. The difference of capacity which actually exists between venous 
 and arterial blood is not sufficient, according to the experiments of 
 Dr. Davy, to form the basis of the chemical theory formerly received ; 
 but the difference which actually does exist may be concerned in a 
 subordinate manner in the process. 
 
 Conformably with the opinion that was first maintained on an occa- 
 sion already alluded to, page 562, we infer that the various causes 
 which modify the production of animal heat act, 1st, immediately upon 
 the organic system of nerves themselves, changing the condition of their 
 influence ; 2d, upon the blood, altering the nature and composition of
 
 OF THE CUTANEOUS FUNCTION. 63t 
 
 this fluid, and thereby rendering it unfit for producing the requisite ex- 
 citement of this system of nerves, and less capable of the changes which 
 the influence of these nerves produces upon its constituent parts ; 3d, 
 immediately through the cerebro-spinal system, modifying the influence 
 which this system imparts to the ganglial. 
 
 These different ways in which the vital influence, exerted by this 
 system of nerves in the production of animal heat, is modified, might 
 have been illustrated by the results of experiments, and by reference to 
 facts in comparative physiology and in pathology, if we could have ad- 
 mitted of so great an extension of our limits. From what we have 
 said, it will be perceived, that we view the production of animal heat 
 more in the light of a vital secretion than of a chemical phenomenon ; 
 and that, like the other secretions and nutrition, it proceeds from, or is 
 controlled by, the vital influence of the ganglial system of nerves, and 
 is co-ordinate with the vital manifestations of the whole body. 
 
 OF THE CUTANEOUS FUNCTION. 
 (NOTES Z. Seep. 230.) 
 
 I. Cutaneous exhalation, or insensible transpiration. In transpira- 
 tion there appears to be two actions, a physical one, consisting of the 
 evaporation in the air of the. fluid parts of the body ; and a vital action, 
 giving rise to an excrementitial exhalation, of which the skin is the organ. 
 This view of the subject is justly contended for by Dr. Edwards; but 
 we think he has refined in an unnecessary manner in explaining it. 
 The cutaneous exhalation is doubtless an organic function, of which the 
 skin is the organ ; but we conceive that the skin must first perform 
 its office before the physical action can take place to any considerable 
 extent : in short, that as transpiration is performed, the physical law, 
 evaporation, operates, and that both go on, the latter as a consequence 
 of the former, paripassu, until an increase of the transpiration on the 
 one hand, and an uncommonly dry state of the atmosphere on the 
 other, give us different results. When the former takes place, we per- 
 ceive the formation of sweat, or the transpiration becomes sensible : 
 when the latter exists, then the phenomenon for which Dr. Edwards 
 and some others have argued, as constituting one of the actions into 
 which this function may be divided, really supervenes to some extent. 
 Thus we have witnessed, during the Harmattan wind, which occasion- 
 ally blows on the west coast of Africa, and which is remarkable for 
 its dryness, evaporation going on so rapidly as to give rise to very in- 
 convenient sensations, and even to serious disorders of the parts which 
 are usually exposed to the air. In this case the evaporation exceeds 
 the mere solution of the transpired fluid in the surrounding atmo- 
 sphere ; and the parts of the body which are subjected to its operation
 
 632 APPENDIX. 
 
 have a portion of the fluids sent to the surface carried off by it, in ad- 
 dition to what is exhaled by the natural and organic action of the vessels 
 of the skin. 
 
 S The cutaneous exhalation contains a portion of the carbonic and 
 lactic acids, and sometimes minute portions of urea and uric acid ; and, 
 according to our experiments, these are more abundant in negroes 
 
 \ and the dark-skinned races than in Europeans. 
 
 II. Of the sweat, or sensible exhalation. When we said that, if 
 the production of the halitus, or insensible transpiration from the skin, 
 exceed the evaporation of it in the atmosphere, sweat is formed, we 
 stated the source of this fluid. It is, therefore, produced from the same 
 vessels as the insensible perspiration. But although this is the case 
 / with respect to their source, there is some difference between the na- 
 ture or chemical constitution of the sensible and insensible cutaneous 
 exhalations. The former is generally less charged with carbonic acid 
 than the latter, but it abounds more with the salts usually excreted 
 \ from the system. 
 
 A careful view of the functions of the skin throughout the different 
 classes of animals leads us to conclude, that it performs operations 
 which hold an intermediate place between those of respiration and eli- 
 mination, that it partakes of the character of a respiratory and of an 
 eliminating organ. 
 
 1 . It is a respiratory organ. This is shewn by the circumstance 
 of this function being performed in the lower orders of animals on the 
 external surface of their bodies only ; by the developement of the 
 organs of respiration in the different orders ; and by the gradual 
 perfection at which the respiratory organ arrives in ascending the 
 scale of animal creation. In the higher animals the respiratory ap- 
 paratus becomes more and more distinct, and the function depend- 
 ing upon it more and more limited to appropriate organs ; how- 
 ever, the same type which characterises the lower orders, and is most 
 remarkable in them, is still preserved throughout the whole series 
 of the animal scale, although it becomes gradually, and nearly, but 
 not altogether, lost. Thus in man the lungs perform the chief respi- 
 ratory process ; but, even in him, the respiratory function of the skin 
 is remarkable. Carbonic acid gas is produced from the cutaneous sur- 
 face, transpiration also takes place there ; and this respiratory act of 
 the skin becomes more and more remarkable under circumstances 
 which diminish or partially obstruct the respiratory process of the lungs. 
 Thus we found that the quantity of carbonic acid gas formed in the 
 lungs in a given time, and in the same individual, was about one-third 
 less in a hot climate than in a cold one ; this was about the average 
 result of our experiments : whilst we observed that the respiratory 
 function of the skin, both as respects the quantity of the insensible
 
 OF THE FLUIDS- 633 
 
 transpiration and the formation of carbonic gas, was very remarkably 
 increased.* In a negro, as far as we could infer from experiments 
 performed on a single limb, the respiratory function of the external 
 surface of the body was much greater, and the quantity of carbonic acid 
 formed in his lungs much less, than in our own case, although our size 
 and weight were equal. Hence we were led to infer, that in this race 
 of the human Species the skin performs a much greater supplementary 
 function to that of the luns:s, than in the inhabitants of cold or tem- 
 perate climates. 
 
 In two cases that came under our observation, in which the lungs 
 were partly destroyed from an imposthume, and the side of the chest 
 was consequently contracted, the cutaneous functions were afterwards 
 very remarkably increased. Were it consistent with the limits of these 
 notes, many facts illustrative of this particular function of the skin, as 
 it respects the inhabitants of cold, temperate, and hot climates, might 
 be adduced. 
 
 2. The skin is an eliminating organ. M. Richerand has so fully 
 illustrated this function of the skin, and contrasted it with that per- 
 formed by the kidneys, that it is unnecessary to say any thing respecting 
 it at this place. The chemical analysis of the perspired fluid, given in 
 the next chapter of the Appendix, will shew to what extent it performs 
 an eliminating office. 
 
 OF THE FLUIDS. 
 
 (NOTES AA. See pp. 232249.) 
 
 In addition to the classifications of the fluids, noticed in the Note\ 
 at page 232, we may mention that adopted by M. Chaussier. He 
 divides the fluids into five classes : those produ ed by the digestive pro- 
 cess, the chyme and the chyle ; the circulating fluids, the lymph and 
 the blood ; the exhaled or perspired humours ; the follicular humours j / 
 and the glandular humours. i. .' 
 
 M. Adelon,f the able and eminent pupil of M. Chaussier, has pro- 
 posed another classification, which possesses some advantages over those 
 which have preceded it. It is also simpler and more natural. He di- 
 vides the organic fluids into those of absorption, the fluid specially 
 nutritive, and the secreted humours. 
 
 1. The absorbed fluids are the chyle, the lymph, and the venous 
 blood. These are taken up and conveyed by the lymphatic and venous 
 class of vessels, and ultimately become assimilated with, and indeed 
 
 * The experiments which were made in order to ascertain this, from the want of 
 the means and proper facilities, were not performed upon the whole body, they were 
 made only upon a single limb ; but the results were very decisive and remarkable. 
 
 f Physiologic de rHomme, par N. P. Adelon, D. M P. &c. vol. i.
 
 634 APPENDIX. 
 
 concur to form the fluid specifically nutritive. Thus the chyle, after a 
 longer or shorter course, mingles with the lymph, both are poured into 
 the venous blood, and when they arrive at the organs of respiration, 
 they become perfectly united, being converted into the nutritive fluid 
 by the functions of those organs. 
 
 2. The fluid especially nutritive. The three fluids constituting the 
 first class being changed in the respiratory organs into that which can 
 alone nourish the body, thus constitute the second class, which, in its 
 turn, furnishes the materials of all those embraced by the third. The 
 second class is, therefore, the arterial blood only, which, being fully 
 perfected m the lungs by the action of the atmospheric air, and cir- 
 culated throughout the body, furnishes the materials of nutrition and 
 secretion, and stimulates and contributes to preserve the functions of 
 the living solids, and, in conjunction with these solids,* produces the 
 calorification of the animal system. 
 
 3. The secreted humours. This class may be divided into three 
 orders, according to the forms of the secreting organs which produce 
 them; namely, into exhaled or perspired fluids, follicular humours, and 
 glandular humours. ^ 
 
 A. Exhaled or perspired humours. These are numerous, are pro- 
 duced in the form of vapour, and they differ from one another in their 
 physical and chemical properties, and in the purposes which they fulfil 
 in the animal economy. They are, moreover, distinguished into those 
 which are taken up by lymphatic or venous absorption, and carried 
 back into the torrent of the circulation, and into those which are en- 
 tirely thrown out of the body ; the former being usually denominated 
 reorementitial, the latter excrementitial, from these circumstances. 
 
 The recrementitial fluids are all produced in cavities or in situations 
 that have no external outlet. The following enumeration includes all 
 the fluids appertaining to this genus: 1. Serous fluids, as those which 
 are exhaled on the surface of the arachnoid, of the pleura, of the peri- 
 cardium, the peritonaeum, and the tunica vaginalis. 2. The synovia. 
 3. The serosity of luminous tissues. 4. The fat formed in the adi- 
 pose tissue. 5. The marrow, or medullary juice. 6. The colouring 
 humour of the skin, placed under the epidermis. 7. The colouring 
 humours of the iris, of the uvea, and of the choroid. 8. The three 
 humours of the eye the aqueous, crystalline, and vitreous. 9. The 
 lymph of Cotugno. 10. The humour of the lymphatic glands, a 
 gelatine-albuminous fluid, existing in the spongy tissue of these organs. 
 11. and lastly, the fluid perspired on the internal surface of all the 
 vessels, the existence of which may be doubted, as it is next to im- 
 
 * By living solids is here meant all sensitive and irritable parts, all those 
 which are influenced by an irritating cause.
 
 CLASSIFICATION OF THE FLUIDS. 635 
 
 possible to demonstrate its existence. In addition to the perspired 
 recrementitial fluids, may be added those which exist in the human 
 ovum, viz. the amniotic fluid, the water of the chorion, which exists 
 between the chorion and amnios only during the early months of preg- 
 nancy ; and the water of the umbilical vesicle, which may be compared 
 to the yolk of an egg, and which some physiologists believe destined to 
 nourish the embryo before the developement of the placenta. 
 
 The excrementitial perspired fluids are all thrown off from the ex- 
 ternal surface of the body, and from the mucous membranes, which 
 have a communication externally by means of the natural outlets, and 
 which may therefore be considered as merely forming parts of the ex- 
 ternal surface. 1. Those fluids which perspire from the skin, as the 
 cutaneous insensible perspiration, and the humour constituting the 
 sweat. 2. The fluids perspired from the respiratory apparatus; these 
 differ somewhat in different situations, as in the nasal cavities, in the 
 trachea, and bronchia. 3. The humours exhaled on the surface 
 of the digestive canal. 4. Those humours exhaled on the internal 
 surface of the urinary apparatus, viz. on the internal surface of the 
 ureters, the bladder, and urethra. ; 5..The fluids exhaled from the 
 genital organs, namely, from the internal surface of the vesiculae 
 seminales and ejaculatory conduits, in the male, and from the uterus 
 and vagina in females (the menstrual flux and the lochia). 
 
 B. The secreted follicular fluids are those formed by a particular 
 secreting organ called follicular. They are all excrementitial, and con- 
 sequently are formed on, and eliminated from, the two external surfaces 
 of the body, the skin and mucous membranes. They consist of, 1. 
 The sebaceous humour of the skin. 2. The cerumen; the humours of 
 Meibomius. 3. The humour of the caruncula lachrymalis. 4. The 
 humour secreted at the base of the glans penis in the male, and on the 
 surface of the vulva in the female. The humours secreted by the 
 follicles in the raucous surfaces are generally characterised by the 
 generic term mucus. , They are distinguished into the mucus of the 
 respiratory organs, the mucus of the digestive apparatus, of the urinary 
 apparatus, and of the genital organs. The humours formed by the 
 prostate, and by the glands of Cowper, compound and glandiform 
 follicles, are usually referred to the last mentioned in this enumeration. 
 The fluid secreted by the tonsils is generally classed with those of the 
 digestive organs. 
 
 C. Lastly The secreted glandular humours are the production of 
 glandular organs. They are, 1. The lachrymal fluid. 2. The 
 salivary fluid. 3. The pancreatic humours. 4. The bile. 5. The 
 urine. 6. The semen ; and 7. The milk. 
 
 It may be remarked generally, with respect to the humours, that the 
 degrees of 'fluidity which belong to them vary greatly from a state of
 
 636 APPENDIX. 
 
 gas or of vapour to that of semi-fluidity ; they have, moreover, all the 
 physical conditions constituting a fluid body. Their fluidity, however, 
 does not result from the general forces of matter, but from those of 
 life. Indeed, the vital influence modifies their physical form of existence, 
 in a more or less marked manner, as long as they continue subjected to 
 its operation. From this source also they are imbued with a certain 
 influence, the presence of which is indicated by the continuance, for a 
 time, of the specific characters of each. This influence, being no longer 
 renewed when they are removed from the body, soon becomes dissi- 
 pated, and the secretion which, while within the sphere of the animal 
 system, and for a short time afterwards, possessed an emanation of the 
 vital influence sufficient to give it certain characters, and to preserve it 
 from the chemical changes to which its constituents are naturally prone, 
 at last falls into a state of dissolution, as unequivocal as that evinced 
 by the textures of the body. In confirmation of this view, we need 
 only refer the physiologist and pathologist to the comparative condition 
 of the more perfectly elaborated secretions immediately after their for- 
 mation and excretion, and after periods of various duration have 
 elapsed from the time of their discharge from the body. 
 
 Finally, we may remark, that the fluids, being composed of mole- 
 cules moving with facility on each other, cannot, as the solids, be traced 
 to constituents of an elementary nature. They can only become the 
 subject of microscopic research in our endeavours to trace the nature 
 of their constitution ; by this means we can merely learn that they are 
 generally composed of globules, swimming in a fluid substance ; and 
 whatever be the fluid employed, we perceive only globules suspended 
 in an amorphous liquid. It should, however, be remarked, that, as we 
 find in some solids merely a concrete amorphous substance containing no 
 globules, as in the cellular tissue for example, so we perceive some 
 fluids destitute of globules, and formed only of an amorphous substance, 
 which is perfectly fluid. In other solids and fluids, on the contrary, 
 we find both globules and an amorphous matter, which is concrete in 
 the former, and liquid in the other. But these globules vary greatly, 
 both in solids and in fluids, and even in the same part, according to 
 age : those of the blood, for instance, are composed of a solid central 
 part, and of an external envelope which is coloured ; those of the chyle 
 appear to be the same as the central part of the former, without its 
 coloured envelope ; those of the muscular fibre seem to be the same as 
 those of the blood; those of the brain and nerves are smaller than the 
 foregoing; and those of the kidneys are smaller than those of the spleen. 
 During the first epoch of conception, the globules are not visible ; they, 
 however, soon form, and become more and more distinct.* 
 
 * See on this subject Physiologie de I'Homme, par N. P. Adelon, vol. i. 
 p. 116. 

 
 OF THE BLOOD. 637 
 
 OF THE BLOOD. 
 (NOTES B B. See pp. 233241.) 
 
 I. Of the small or colourless globules of the blood. The researches 
 of Sir Everard Home and Mr. Bauer * seem to lead to the following 
 conclusions respecting these globules. 
 
 1. That the milk-like fluid, the produce of digestion (chyle), which 
 is found in the lacteal vessels and glands, contains an infinite number 
 of white globules, chiefly of a minute size. 
 
 2. These newly discovered minute globules are -^OTT P art f an mcn 
 in diameter. 
 
 3. That the chyle contains also some white globules, of the size of 
 the red globules of the blood. 
 
 4. Mr. Bauer supposes that the full-sized globules acquire their form 
 in the lacteal glands. 
 
 5. Sir Everard Home considers that the globules of the blood 
 receive their red hue in the vessels of the lungs. 
 
 6. That lymph or fibrine, whether taken from an inflamed surface, 
 from the buff of what is commonly called inflamed blood, or from the 
 slowly formed layers of aneurismal tumours, consists of innumerable 
 white globules, much smaller than those which constitute the red 
 globules of the blood, and similar to those minute globules already 
 described. 
 
 7. That those small globules constitute the substance thrown out in 
 inflammation. 
 
 8. That they are held in solution in the serum, and consequently 
 are only brought into view in the act of coagulation. 
 
 9. That these globules, as well as those which subsequently receive 
 the red colour, are the produce of digestion, and are formed in the 
 pyloric portion of the stomach and in the duodenum, surrounded by 
 a glairy mucus, which is met with in these parts. 
 
 MM. Prevost and Dumas f agree with Sir Everard Home as to the 
 
 * Phil. Trans, for 1820. 
 
 f The microscopic observation of the blood satisfied these gentlemen that this 
 liquid, during life, was nothing else than the serum,' holding in suspension small 
 regular, and insoluble corpuscles. Those are uniformly composed of a central, 
 colourless spheroid, and of a species of membranous bag, of a red colour, surrounding 
 this spheroid, from which it is easily separable after death. The central body is 
 white, transparent, of a spherical form in animals with circular particles, of an 
 ovoid form in those with elliptical particles. Its diameter is constant in the first, 
 but it varies very perceptibly in the second. It manifests also a great disposition 
 to assume aggregates or ranges, in the form of a string of beads. 
 
 The coloured portion appears to be a kind of jelly, easily divisible, but insoluble
 
 638 APPENDIX. 
 
 form and structure of the globules of the blocd; but they do not admit 
 with him that the red globules undergo a rapid change after they 
 escape from the vessel, or that the colouring matter which envelopes 
 the central spherical body separates from the globule so soon as thirty 
 seconds after the blood has issued from the vein. They, however, 
 agree with him in saying, that these central spheres (the smaller 
 globules) unite themselves in filaments, which differ in no respect from 
 the muscular fibre. They observed also small globules in the milk, in 
 pus, and in the chyle ; and they consider that those of the former fluids 
 have been, and these of the latter are to be, surrounded by the colour- 
 ing matter of the blood. 
 
 MM. Prevost and Dumas found the globules of the blood to be 
 circular in all the mammalia ; and in their size to vary in different 
 animals : they are smallest in the goat. 
 
 The globules are elliptical in birds, and they vary considerably in 
 size in this class of animals. This variation is chiefly in the great axis 
 of the globules. They are elliptical also in all cold-blooded animals. 
 
 II. Of the coagulation of the blood, and on its vitality. On the 
 part of the subject before us we cannot enter minutely. We will merely 
 state, as briefly as we can, those inferences at which we have arrived, 
 after a careful examination of the phenomenon itself, under various 
 circumstances, and of the different opinions entertained respecting it. 
 
 in water, from which it may always be separated by repose. It is likewise trans- 
 parent, but much less so than the central corpuscle ; and the fragments arising from 
 its division are not susceptible of regular aggregation. As the attraction, which 
 keeps the red substance fixed round the white globules, ceases at the same time with 
 the movement of the liquid, these globules can then obey the force which tends to 
 unite them, and to form a net-work, in whose meshes the liberated red colouring 
 matter gets enclosed, and thus to produce the phenomenon of coagulation. If the 
 coagulum be exposed to a stream of water, the colouring matter is washed away, 
 while the aggregate formed by the white globules remains in the form of filaments, 
 in which may be recognised, by means of the microscope, the aspect and structure of 
 the muscular fibre. 
 
 Three animal substances ought, therefore, to fix our attention : these are, the 
 albumen of the blood, the white globule, and the colouring matter which envelopes 
 this. With respect to the colouring particles of the blood, these chemists suppose 
 that it is formed of an animal substance in combination with a peroxide of iron. 
 The colourless globules they considered to be coagulated albumen. They have ex- 
 amined the proportion which the white corpuscles and red matter together bear to 
 the rest of the blood, in a great variety of animals ; and they find them most 
 abundant in birds, next in the mammalia, especially the carnivorous mammalia ; 
 and they are least plentiful in cold-blooded animals. In man they constitute about 
 one hundred and twenty-nine parts by weight per thousand. They are more 
 abundant in arterial than in venous blood; one thousand parts of the arterial 
 blood of the sheep, dog, and cat, contain ten parts more of these particles than blood 
 taken from the veins. The serum is identical in both.
 
 OF THE COAGULATION OF THE BLOOD- 639 
 
 1 . According to our own observations, as well as those of Trevi- 
 ranus and Kolk, whose researches on this subject have been extended 
 and faithful, the particles or globules of the blood possess a rotatory 
 motion during life, and this motion continues until the phenomenon 
 of coagulation takes place. 
 
 2. We conceive that this motion of the globules is the cause of 
 the blood's fluidity. 
 
 3. That the motion of the globules of the blood is the consequence 
 of the vital influence emanating from the ganglial nerves distributed in 
 the parietes of the vessels in which they circulate, and endowing them 
 with vitality. (See pp. 561, 562.) 
 
 4. We therefore infer that the blood possesses vital properties, but 
 that these properties are derived from, and depending upon, the vital 
 conditions of the vessels in which, and the organs through which, it cir- 
 culates ; that it is not the source of vitality, although manifesting a 
 reciprocative vital influence ; and that manifestations of vital properties 
 may be traced in the chyle, or originate there, proceeding from the 
 admixture of the secretions contributing to its formation, and from the 
 vessels and organs through which it circulates in its course into the 
 current of the blood, vitality thus beginning to manifest itself, in its 
 lowest grades, with the formation, in the chyle, of the central globules 
 of the blood. 
 
 5. That the cause of the coagulation of the blood is not to be found x 
 in external agencies, but in the loss of that emanation (proceeding 
 from the organic nerves distributed to the coats of the vessels) of the / 
 vital influence with which the globules are endowed. 
 
 6. That the presence of the air, especially of the oxygenous portion 
 of it, promotes this phenomenon. 
 
 7. That when coagulation commences at any point of a mass of 
 blood, it is rapidly propagated throughout the whole : this may arise 
 from the cause being co-ordinate, or nearly so, throughout the whole. 
 
 8. Neither the heat of the body, nor the strength of the circulation, \ 
 are causes of the blood's fluidity : they are both results of the same cause, 
 viz. the vital energy of the vessels, and vital endowment of the globules 
 of the blood; both are co-ordinate, and both, as well as the phenomena 
 of coagulation, are dependent on this source. 
 
 9. That coagulation occurs sooner in venous than in arterial blood ; 
 and that coagulation of arterial blood is still longer delayed if it be 
 prevented from leaving the arteries. 
 
 10. That coagulation takes place the sooner after the blood is re- \ 
 moved from the vital sphere of the system, the weaker the vital energy 
 to which it was subjected whilst circulating in the system. 
 
 11. That the weaker the vital energy, and, consequently, the quicker 
 the coagulation, the more lax is the coagulum which is formed. 
 
 (. /<...< .<__^
 
 640 APPENDIX. 
 
 12. That, on the same principle, coagulation is more slow, and the 
 coagulum more firm, according as the vital influence of the vessels is 
 more energetic. 
 
 13. That the quantity of globules modifies these results; a large 
 proportion also of these globules indicates great energy, and vice versd. 
 
 14. That, as the central globules retain their coloured envelopes 
 during their circulation in the blood-vessels, and lose them soon after 
 removal beyond the sphere of the vital influence of these vessels, and 
 as this is a part, and indeed the first part, of the act of coagulation, so 
 we consider that it is in consequence of the vitality emanating from the 
 interior of the vessels into the blood, that the coloured envelopes of the 
 central globules continue to surround them ; and, consequently, that 
 the separation of the envelope from the central globule is the result of 
 the loss of the chief portion of that vitality which proceeds from the 
 containing blood-vessels ; and as this loss of vitality may be reasonably 
 supposed to be quickest where it has been originally the least, there- 
 fore the separation of the envelopes and the coagulation will be the 
 quicker, the weaker the vital energy, and rice versd ; and the coagulum 
 will be the more lax. 
 
 15. That the loss of the vitality emanating from the vessels, and 
 consequently the loss of their envelopes, disposes the central globules 
 to attract each other ; and that in the exertion of this contraction they 
 dispose themselves into reticulated fibres, which entangle the colouring 
 matter and a portion of the serum, and thus the clot is formed. 
 
 16. It would appear that the central globules continue to retain, in 
 the fibres which they form in the act of coagulation, a small portion of 
 the vital emanation with which they were endowed ; inasmuch as the 
 fibrous part of the coagulum evinces phenomena approaching to those 
 denominated irritable ; and that it is the loss of the chief part of the 
 vitality, and not the whole of it, which occasions the separation of the 
 coloured envelopes from the central globules. 
 
 17. That the firmness of the coagulum, and the irritable phenomena 
 evinced by its fibrous part, are proportionate in degree to the vital ener- 
 gies with which the vessels are endowed by the ganglial nerves distri- 
 buted in them, and to the emanation which the globules themselves 
 derive from this source. 
 
 18. That the vital emanation, proceeding from the ganglial nerves 
 distributed in the vessels, affecting the globules in this manner, and 
 giving rise to these phenomena, has been the cause of, and has coun- 
 tenanced, the hypothesis of the vitality of the blood, a vitality which 
 does not belong to it independently of these nerves, and of the vessels 
 and organs through which it circulates, which it possesses in a di- 
 minished degree, and which is an emanation from a different source 
 (Prop. 3), which source is efficient in the formation of the blood itself,
 
 OF THE COAGULATION OF THE BLOOD. 641 
 
 and bestows on it, through the medium of the vessels containing it, 
 the chief properties which this fluid evinces in health and in disease. 
 (See Prop. 4, p. 639.) 
 
 19. That when the vitality of the system, especially that of the 
 blood-vessels, is greatly diminished, as in purpura hsemorrhagica, scurvy, 
 and in other diseases, coagulation either does not at all take place, or 
 it takes place very quickly, and the coagulum is weak, lax, and re- 
 sembling cruor. Under such circumstances, the envelopes separate 
 rapidly from the central globules, because the vitality of the vessels is 
 scarcely sufficient to continue them in connexion even when circulating 
 through the vessels themselves ; coagulation takes place quickly, be- 
 cause the motion impressed upon the globules by the vital energy of the 
 vessels, owing to the defect of this energy, is soon lost, and because the 
 separation of the envelopes from the globules takes place almost in- 
 stantly ; and the coagulum which is formed is weak, or it does not form 
 at all, because the vitality of the globules is insufficient to dispose to 
 an energetic attraction, or even to any attraction between the central 
 globules. 
 
 20. In various diseases, especially in those which are malignant and 
 infectious, when the vitality of the system is much exhausted, as in 
 the advanced stages of typhoid and adynamic fevers, in the true 
 infectious puerperal fever, and puerperal mania, in the worst forms ef 
 erysipelas and diffusive inflammation of the cellular structures, and ia 
 several other diseases, particularly when epidemic, or occurring in 
 hospitals, the air of which is vitiated by crowding of the sick, and the 
 decomposition of the discharges and secretions, as in lying-in hos- 
 pitals, the blood taken from a vein will often not separate into a 
 distinct coagulum and serous fluid, but will assume the appearance 
 of a straw-coloured gelly, at the bottom of which gelly the red en- 
 velopes of the vessels~will be found forming a loose, reddish brown or 
 blackish stratum. In such cases, the blood, participating in the de- 
 ficiency of the vital energy of the body, and being also, perhaps, 
 deranged from the admixture of hurtful materials with it, which are 
 not duly eliminated by the various emunctories, evinces the lowest 
 grades of vital endowment ; the attraction between the globules of the 
 blood being so weak as not to give rise to the exclusion of the watery 
 parts, and permitting the envelopes of the globules to separate speedily, 
 and to form a loose and unadhering stratum over the bottom of the 
 vessel.* 
 
 21. Opposite phenomena to the above, result from the increased 
 
 * This appearance of the blood has generally been observed by us in cases of 
 disease characterised by unusual frequency of the heart's contractions, accompanied 
 by great loss of vascular tone, and vital resistance of the system generally. The 
 blood-letting in such cases has always been very hurtful. 
 T T
 
 642 APPENDIX. 
 
 energy of the vital functions generally, particularly of the vascular 
 system, and of the functions of the nerves which supply it. 
 
 22. If this were a suitable place, various other morbid states of the 
 blood, arising both from deficient vital energy and consequent inactivity 
 of the functions of those organs which are the emunctories of the vas- 
 cular system, and fiom the introduction of hurtful emanations and in- 
 gredients into the circulation, and occurring in the course of numerous 
 diseases, especially such as are epidemic and febrile, might be adduced. 
 
 23. We may infer as a corollary, that the appearances which the 
 blood exhibits have always an intimate relation to the vital conditions 
 of the system, and to the state of excitement which the heart and 
 blood-vessels present ; and that the buffy coat is merely one of the 
 manifestations furnished by the blood, indicating reaction of the powers 
 of life, or excitement of the vascular system. We believe that the blood 
 participates in the vitality of the body through the medium of the 
 vessels and organs in which it circulates ; that according to the degree 
 or condition of this vital endowment, coagulation and the coagulum are 
 modified in their phenomena and appearances, and the production of 
 the buffy coat promoted or altogether prevented ; and that the blood 
 gradually acquires its vital endowment from the time that the secre- 
 tions mix with the more soluble portions of the chyme and form the 
 nutritious chyle, which also generally presents the phenomena of co- 
 agulation, although in a less degree. 
 
 III. Of transfusion of blood, and injection of foreign matters into 
 it. MM. Prevost and Dumas* found that, after bleeding an animal 
 until all organic actions ceased, and injecting, within a few minutes 
 afterwards, the warm blood taken from another of the same species, 
 until a quantity equal to that taken away was restored, the animal 
 gradually revived and took nourishment, and perfectly recovered if the 
 operation was well performed. 
 
 If, however, the blood injected was taken from an animal of a dif- 
 ferent species, possessing globules of the same form, but different in 
 dimensions, the animal was very imperfectly revived, and could be 
 rarely preserved beyond six days. The pulse became in these frequent, 
 the temperature fell remarkably, if not artificially preserved, while the 
 respiration retained its natural frequency. Immediately after the ope- 
 ration the dejections became mucous and bloody, and preserved that 
 character until death. 
 
 If blood with circular globules was injected into the veins of a bird, 
 the animal generally died before, the operation was completed, in very 
 violent and rapid nervous convulsions. 
 
 * Bibliotheque Univers. Juillet 1821.
 
 OF SECRETION AND EXHALATION. 643 
 
 Transfusion of blood from the cow or sheep into the veins of the \ 
 cat or rabbit, was followed by the recovery of the animal in a number of 
 cases. 
 
 The blood of the sheep excited in the mallard duck the most 
 violent and rapid convulsions, which were immediately followed by 
 death, as was observed to follow the injection of the first syringeful in 
 land-birds.* 
 
 OF SECRETION AND EXHALATION. 
 (NOTES CC. See pp. 245255.) 
 
 Opinions have been various respecting the mechanism provided for 
 the performance of exhalation and secretion. One class of physiolo- \ 
 gists contends for a separate order of very minute capillaries, proceeding 
 from those carrying red blood, which they call exhalent or secretory 
 capillaries, and devoted to these functions, (see p. 616.) Belonging to 
 this class we may reckon Haller, Hewson, Scemmering, Bichat, Chaus- 
 sier, Alard, &c. As these vessels cannot be demonstrated, their ex- 
 istence is denied by Mascagni, Prochaska, Richerand, Magendie, and 
 others, who argue, that these functions take place in the sanguineous 
 capillaries, through the medium of organic lateral pores. The fact 
 appears to be, that the evidence for a separate set of capillaries is equal 
 to that for the existence of organic pores in the capillaries carrying red 
 blood; it is not easy to demonstrate the presence of either; whilst 
 both the one and the other may prove a sufficient medium through 
 which the processes will go on, under the influence with which the 
 capillary vessels are endowed. The existence and efficacy of this in- 
 fluence is sufficiently manifest, although the more minute instruments, 
 by means of which it operates, cannot be satisfactorily demonstrated to 
 our senses. 
 
 * Since MM. Prevost and Dumas have thus recalled the attention of the pro- 
 fession to the subject of transfusion, the operation has been performed successfully 
 by Dr. Blundell and others in this country, in cases of excessive uterine haemor- 
 rhage; and under favourable circumstances it promises to be of decided utility. 
 
 The experiments, and observations of various physiologists and pathologists have 
 also shewn that much advantage will be obtained, and a more energetic effect pro- 
 duced, by injecting immediately into the current of the circulation various medicinal 
 substances, than when such substances are exhibited in the usual way. ' The results 
 of this mode of treatment shew that a large proportion of medicinal agents act in a 
 similar manner when injected into the blood, as when exhibited through the medium 
 of the digestive organs the quantity, however, in the former case requiring to be 
 much smaller ; and, moreover, it has been shewn also, that when active substances 
 are thus introduced at once into the blood, they produce the specific effects usually 
 observed to proceed from their use in the common modes of exhibition.
 
 644 APPENDIX. 
 
 In respect of secretion, the state of opinions and of our knowledge 
 as to the manner in which it takes place, or rather the mechanism pro- 
 vided for its performance, is similar to what we have shewn to exist on 
 the subject of absorption and on that of the minute capillaries. In 
 stating the opinions on these subjects, and those lately espoused by 
 M. Alard, we gave the views of those who contend for the existence of 
 minute lymphatics running into the venous capillaries, in a similar 
 manner to that in which exhalent vessels are supposed, as stated above, 
 to proceed from the arterial capillaries. But the latter set of vessels 
 has been as little seen as the former. This, however, in a matter of this 
 nature, is not a sufficient proof against their existence. Some physio- 
 logists, on the other hand, contend that exhalation and secretion take 
 place through means of pores analogous to those which are supposed 
 to be instrumental in the phenomena of absorption ; arid that the pro- 
 cess is entirely one of transudation. But the same objection may be 
 offered against the existence of pores as to that of the exhalents or 
 secreting capillaries in question. 
 
 We believe that the precise way in which exhalation and secretion 
 take place cannot be readily demonstrated to the senses, that the one 
 apparatus may explain the process as well as the other, that secretion 
 as well as absorption are iv>t mechanical processes, although there are 
 apparatuses, or subordinate instruments, provided for their perform- 
 ance, and that they are essentially vital operations, and under the 
 control of the vital influence with which the capillaries themselves, and 
 the organs to which they belong, are endowed. 
 
 As to the question of pores, it must be granted, that the solids of 
 the body, and the parietes of the vessels, are all porous ; it is only with 
 respect to the extent and magnitude of the pores that the question 
 can be entertained. Those who contend for the existence of separate 
 and subordinate sets of capillary vessels, cannot deny the existence of 
 pores ; for if they do not exist both on the surfaces and in the textures 
 whence these capillaries are supposed to originate, how could they 
 obtain the fluids circulating in them? On the other hand, those who 
 contend for the existence and functions of pores, cannot deny the ex- 
 istence of minute absorbents or lymphatics ; for they can be demon- 
 strated to a certain extent as respects the minuter ramifications, and in 
 a satisfactory manner as regards the more considerable branches. It 
 appears to us that both species of organisation exist to a greater or less 
 extent in different textures and secreting organs. 
 
 We refer our readers to our notes at p. 249, for some remarks on 
 the fact, that each secreting viscus is supplied with a distinct ganglion, 
 plexus, or both ; that these preside over the secreting function ; and 
 that the functions of some of these ganglia are influenced by the opera-
 
 OF NUTRITION. 645 
 
 tions of the cerebro-spinal system ; as, for example, the secretion of the 
 lachrymal gland is increased by the influence which the nerves of this 
 latter system convey to the ganglion that supplies it, and is the chief 
 source of its functions. 
 
 OF NUTRITION. 
 (NOTES DD. See pp. 257 262 ; and NOTE S, p. 615.) 
 
 As we have already seen, in the Notes on the Capillary System and 
 on Secretion, the function of nutrition has been explained by one class 
 of physiologists by supposing the existence of nutritive capillaries, and 
 by another by means of organic pores, with which they endow the 
 capillary vessels circulating red blood, and to which they commit 
 the exhalent, secreting, and nutritive functions. The first of these hy- 
 potheses supposes that nutrition takes place in minute colourless vessels, 
 which proceed in a more or less tortuous direction from the arterial 
 capillaries, absorption proceeding through the medium of a similar set 
 of colourless vessels continuous with the former, which run into the 
 venous capillaries, and thus the nutritious molecules are always cir- 
 culating within colourless capillaries, which, with the nerves and larger 
 capillaries, constitute the basis of the different textures. 
 
 Mascagni supposes that the arterial capillaries, at the point where 
 they change into veins, are provided with exhalent pores, both for the 
 purposes of secretion and nutrition ; and that there every where exists 
 the orifices of minute absorbent vessels, commencing in the latter de- 
 scription of pores, in order to take up the nutritive molecules. The 
 elementary tissues consist, in his opinion, of this particular class of 
 absorbent vessels, which contain the molecules as long as they are a 
 part of the textures, and which, by their union, form the most simple 
 membranes. 
 
 These hypotheses do not differ very materially. Both contend for 
 the existence of very fine capillaries, which attract the nutritive mole- 
 cules, and contain them in a state of progressive circulation, as long as 
 they form constituents of the textures ; these molecules being afterwards 
 carried onward in succession into the branches of the absorbent lym- 
 phatics and into the veins. In the first of these hypotheses, the nutri- 
 tious particles are supposed to circulate in the finest of the vessels 
 proceeding from the arterial capillaries ; in the second, the process is 
 ascribed to the most minute radicles of the absorbents ; but both agree 
 in considering the molecules constituting the mass of the textures to be 
 contained in colourless vessels, and to be in a state of continual cir- 
 culation. v 
 
 The opinion of Bichat on this subject is somewhat different. Ac-
 
 646 APPENDIX. 
 
 cording to him, each molecule of those constituting the textures of the 
 body is placed between the orifices of two vessels : one, a nutritive ex- 
 halent orifice, which has deposited the molecule ; the other a nutritive 
 absorbent orifice, about to absorb it. 
 
 Prochaska, who conceives that the arterial capillaries are continued 
 directly into veins, considers that nutrition takes place in consequence 
 of the porosity of the capillaries, and of the general permeability of 
 the substances constituting the mass of the structures. M. Richerand 
 espouses a similar opinion ; but he seems to allow an organic property 
 to the pores which he ascribes to the, capillary vessels. 
 
 Opinions respecting the mechanism of nutrition, or the manner in 
 which it takes place, can only be theoretical. We have not the means 
 of demonstrating the existence or non-existence of either the one or the 
 other mode of organisation contended for : each may of itself be suffi- 
 cient to explain the phenomenon, as far as respects the apparatus 
 required for the process, but it is only the apparatus. The function 
 itself is purely a vital one. It presents us with a continual motion, of a 
 double nature a continual attraction and decomposition of material 
 molecules. In the most simple animals, as the polypus, these pro- 
 cesses go forward without any previous preparatory function : the 
 animal imbibes, in a direct manner, similar molecules of matter to those 
 of which it is itself formed from the surrounding medium, and again ex- 
 hales them in a manner equally direct. In these there are no vessels 
 destined for the purpose of circulation and nutrition, yet they present 
 the phenomenon of irritability ; and on examination with a microscope, 
 their structure appears almost homogeneous, with the exception of glo- 
 bules entirely similar to those which are observed in the ganglial nerves 
 of the higher animals. As these are the chief marks of internal organi- 
 sation which can be detected in the very lowest of the animal kingdom, 
 and as we must conceive that the organisation must be instrumental in 
 the nutrition and operations of animal bodies, and as, moreover, we 
 perceive that the perfection of the organisation or material apparatus is 
 commensurate with, and has an evident relation to, the extent of the 
 vital operations which it performs, so it seems reasonable to suppose 
 that this organisation, which is the only one that is detected in the 
 very lowest of animals, is the chief and indeed only instrument of the 
 limited function which they perform ; and that, as a similar but more 
 perfect organisation presides over the nutritive function of the highest 
 animals, so this presides over that of the lowest, without the assistance 
 of the complicated capillary apparatus assigned by some physiologists 
 to them ; and if a distinct set of subordinate capillary vessels be not 
 requisite to the nutritive function in the lowest class of animals, we 
 may allow that this function takes place in the highest classes, under 
 the dominion of the more perfect nervous organisation to which we
 
 OF NUTRITION. 647 
 
 have assigned it, without the existence of the complicated capillary 
 apparatus for which some contend. 
 
 Concluding, therefore, that as the nervous globules demonstrable in 
 the very lowest animals are the only internal organisation which they 
 evince, that organisation must have a determinate object or function, 
 which it performs under the control of the vitality with which it is 
 allied, and which all animals possess ; and* that nutrition and irrita- 
 bility are the only organic actions which these animals perform, so it 
 must inevitably follow, that these actions result from the vital influence 
 allied to the particular organisation in question ; and that the nervous 
 globules constituting the only marks of internal organisation possessed 
 by these animals, attract from the surrounding media, in consequence 
 of the vitality with which the globules are endowed, these molecules of 
 matter corresponding to those forming the structure of the animal, 
 which come within the sphere of their influence, and retain them for 
 an indefinite time, unassisted by either exhalent or absorbent vessels. 
 Now, as the same type, especially as respects the nutritive functions, 
 may be observed throughout the whole animal creation, and as we can 
 trace nervous chords, formed of globules similar to those already ascribed 
 to the lower, and indeed to all animals, throughout almost the whole of 
 their bodies, is it not reasonable to suppose that similar globules exist 
 in all the simple textures in a more diffused form that the globules 
 constituting the organic o ganglia! system of nerves become more dis- 
 seminated amongst the molecules of the textures in the course of their 
 distribution with the capillary vessels, and of their more direct ramifica- 
 tions and terminations in the textures themselves? If this be granted, 
 and it scarcely can be denied, for it has been demonstrated in different 
 orders of animals and as it has been shewn that these nervous globules 
 are present, in a more or less organised form, throughout the whole 
 animal creation it may consequently be inferred, that the same function 
 which we have ascribed to them in the lowest animals should be ex- 
 tended to them in the highest. This is conformable to the laws charac- 
 terising the animal economy. 
 
 As we have contended in another place, (p. 558, et seq.) conform- 
 ably with this opinion, that the ganglial nerves, in some one or other 
 of their forms of existence, are present throughout every part of the 
 body, that they preside over digestion, nutrition, secretion, &c. and are 
 more nearly allied than any other texture with the vital influence which 
 the body exhibits, so we now'conclude, that the globules constituting 
 the ganglial system, being allied with vitality, and being distributed in 
 different forms of connexion to the various textures of the body, exert, 
 in consequence of the vital influence with which they are endowed, a 
 vital attraction on those molecules of matter which come within the 
 sphere of their influence; that the force of this attraction, and the
 
 648 APPENDIX- 
 
 manner in which the material molecules are arranged in order to form 
 the different textures of the body, result in a great measure from the in- 
 fluence proceeding from the form, the number, or the condition of these 
 globules in the textures which it is their office to perpetuate ; and that 
 the chief office of the digestive, the respiratory, the animalising, and 
 the circulating processes, is to present the materials, whence the dif- 
 ferent textures are preserved and nourished in a fit state for the 
 exertion of this vital attraction ; and that the principal operation- 
 performed by the capillary vessels is to convey these materials within 
 the sphere of this attraction ; and, so that this is performed, it matters- 
 but little whether or no these vessels accomplish it by means of 
 subordinate nutritive capillaries, destined to the circulation or de- 
 position of the nutritious molecules, or by means of organic pores, with 
 which their parietes may be provided. 
 
 But, whilst we suppose that the function of nutrition may thus take 
 place in consequence of a vital attraction, resulting in the manner which 
 we have explained, and exerted exterior to and independently of the 
 vessels, and whilst we consider this explanation to be supported by the 
 nutritive actions of the lowest animals ; yet we would by no means ex- 
 clude the influence of that part of the ganglial nerves distributed to the 
 capillaries from a part in the operation, more especially in the higher 
 classes of animals. Indeed, it seems difficult to suppose which of those 
 in the higher animals namely, whether the nervous globules distributed 
 to the simple textures, and placed beyond the capillaries, or those con- 
 stituting the nervous fibrilse which surround them, are most efficient in 
 the nutritive process. An intimate view of the subject would suggest, 
 that in man and the more perfect animals the latter organisation is 
 the more active of the two in the operation in question ; and that the 
 capillary vessels, in consequence of the ultimate nervous structure which 
 surrounds them, and of the vital influence which this structure exerts, 
 secrete from the fluid circulating in them certain materials in a similar 
 manner to that in which they perform the other secretions in secreting 
 organs, and by means either of appropriate vessels or pores. 
 
 As it has been shewn that the blood consists of minute globules, or 
 corpuscles, surrounded by a coloured envelope circulating in a mass of 
 fluid, and that the simple solids of the body are constituted of similar 
 corpuscles, in a state of intimate or vital attraction, to those of the 
 blood, when they are separated from their envelopes, so it may be in- 
 ferred, that a part of the function, which the ultimate distribution of the 
 ganglial nerves performs on the capillary vessels, is to secrete similar 
 corpusctes, from the blood circulating in these vessels, to those of 
 which the texture is formed in which the operation takes place ; and 
 that this having been accomplished, the vital attraction is preserved 
 by means either of the influence with which these corpuscles are
 
 DECUSSATION OF THE OPTIC NERVES- 649 
 
 endowed, as a consequence of the previous process of animalisation 
 which they have undergone, or of the influence exerted iipon them 
 after they leave the vessels by the nervous globules and fibrilae 
 disseminated in the textures, or perhaps by both species of vital action, 
 either the one or the other acting more or less partially, according to 
 the nature of the particular texture in which the process takes place, 
 and according to inappreciable and fortuitous causes. 
 
 Hence it will be perceived that nutrition is essentially a vital opera- 
 tion, that it is placed under the control of the extreme ramifications of 
 a particular system, to which we have referred all the vegetative or 
 organic operations which characterise the animal kingdom ; that it is 
 performed in all animals, except the very lowest, through the medium of 
 circulating organs, and in the highest as a consequence of certain pre- 
 paratory processes ; that it requires in man and in the higher animals a 
 capillary circulation for its performance, but that neither of the capillary 
 apparatuses which have been contended for is sufficient of itself to 
 perform this function, although the most simple apparatus, whilst 
 under the dominion of the vital influence of that particular structure 
 which we find every where disseminated where there is life, is all that 
 is requisite as the material instrument of the process; and lastly, and 
 as a consequence of the foregoing position, that nutrition is modified, 
 controlled, increased, or even annihilated, either generally or in par- 
 ticular parts of the body, by the state of the vital influence allied to 
 the material organisation, to which we have already imputed it, ac- 
 cording as this particular organisation in its centres and ramifications 
 throughout the^animal frame is generally or locally affected. 
 
 OF THE DECUSSATION OF THE OPTIC NERVES, AND MOTIONS 
 OF THE EYES, &c. &c. 
 
 (NOTES EE. See pp. 275284.) 
 
 I. Decussation of the optic nerves. Vicq d'Azyr found, on ex- 
 amining with a microscope a horizontal section of the optic nerves of 
 the human subject, after it had been hardened in alcohol, that the me- 
 dullary fibres occupying the exterior side of the optic nerve proceed 
 in a direct manner from the optic thalamus to the eye of the same side, 
 and that the place of union presents a homogeneous tissue. The 
 Wenzels came nearly to the same conclusion from their observations ; 
 but remarked, in addition, that while the fibres of the exterior side of 
 the nerve go immediately to the eye of the same side, those fibres 
 placed in its interior side are directed obliquely towards the other 
 nerve, without, however, any crossing of fibres being manifest at the 
 point where the junction of both nerves takes place. 
 
 M. Treviranus has, in a great measure, confirmed these observa- 
 tions on, the male simia aygula. The nerves and brain were left during
 
 650 APPENDIX. 
 
 some months in alcohol, and afterwards kept some time in caustic potash 
 to soften them. Having thus prepared them, he submitted them to a 
 careful dissection, when he made out, with the aid of a microscope, that 
 the external fibres of the upper side of each were continued from their 
 cerebral extremity to that in the eye, without uniting themselves to 
 those of the other side; whilst, on the contrary, the internal and in- 
 ferior fibres of one nerve went to the other side, and united with the 
 fibres of the opposite nerve. It was difficult to determine whether any 
 of the fibres actually passed from one side to the other. He thought, 
 however, that some of the fibres did.^o. The internal fibres, thus inter- 
 lacing together, were evidently more numerous than the external fibres 
 which ran to the eye without uniting with those of the opposite nerve.* 
 M. Magendie infers from his experiments that the decussation of the 
 optic nerves is complete, f 
 
 II. Of the motions of the eye, p. 282. Mr. Charles Bell has lately 
 examined the motions of the eye, in illustration of the uses of the muscles 
 of the orbit ; and has shewn, in the first place, that there are motions per- 
 formed by this-organ not hitherto noticed. Every time the eyelids descend 
 to cover the transparent part of the eye, the eyeball ascends, or suffers 
 a revolving motion. If this were not the case, the surface of the eye 
 would not be moistened, nor freed from offensive particles. He has 
 proved, in the next place, that during sleep the eyeball is turned up, 
 and the cornea lodges secure and moistened by the tears, under cover 
 of the upper eyelid. He considers that these motions are rapid and 
 insensible, and that they are provided for the safe-guard of the eye. 
 The other motions are voluntary, and for the purpose of directing the 
 eye to objects. 
 
 Mr. Bell next examined the actions of the muscles of the eyeball, 
 and distinguished them, as usual, into the straight and oblique muscles. 
 It has been supposed, hitherto, that both these classes of muscles were 
 voluntary ; some describing the oblique as coadjutors of the recti 
 muscles, and others as opponents to the recti ; but Mr. Bell has viewed 
 the oblique as provided for the insensible motions of the eyeball, and 
 the recti for those motions which are directed by the will, and of which 
 we .are conscious. 
 
 Mr. B. has also proceeded to shew, that the consciousness of the 
 action of the recti muscles gives us the conception of the place or rela- 
 tion of objects ; and has endeavoured to prove, by observation and 
 experiment, that the actions of the straight muscles are inseparably 
 connected with th6 activity of the retina, that is, with the enjoyment 
 
 * Journal Complementaire, Oct. 1823. 
 
 f- See his Compendium of Physiology, 2d edition.
 
 OF THE ADAPTATION OF THE LENS. 651 
 
 of vision ; but that the moment the vision is unexercised, the eyeball is 
 given up to the operation of the oblique muscles, and the pupil is con- 
 sequently drawn up under the eyelid. " Hence the eyes are elevated 
 in sleep, in faintness, and on the approach of death ; and that distor- 
 tion which we compassionate as the expression of agony, is the con- 
 sequence merely of approaching insensibility."* 
 
 III. Of the connexion of the fifth pair of nerves with the function 
 of vision. The branches of the fifth pair of nerves are evidently related 
 to the functions of sensation and touch in respect of the parts to which 
 they are ramified. In a few of the lower animals in which the optic 
 nerve is wanting, the first branch of the trigeminal nerve seems to be 
 so intimately connected with the sense of vision, as to be entitled-to be 
 considered as the chief nerve of this organ, and the one on which the 
 sensation depends. It seems also, both from experiment and patho- 
 logical observation, to be subservient in the higher animals to the 
 perfection of the sense of vision ; and it supplies in an especial manner 
 some of the parts of the organ, particularly the iris, most intimately 
 associated in function with the retina. The fifth pair of nerves seems to 
 establish a kind of relation between the senses of sight, smell, taste, and 
 hearing, by means of the filaments proceeding from its three principal 
 branches to the most important parts of the organs of these senses ; 
 and whilst it contributes to their perfection generally, it is particularly 
 concerned in the production of the sense of taste. It is not a special or 
 principal nerve of sight, nor of smell, nor of hearing, in man, but it per- 
 forms an accessory part, and renders these senses more perfect. 
 
 M. Serresf records a case of disease confirmatory of these views, \ 
 which occurred in an epileptic patient in the hospital la Pitie. The 
 patient had lost the sight of the right eye, and the senses of taste and 
 smell of the same side ; hearing also was nearly lost in the right ear. 
 Upon dissection, the fifth pair on the right side, at its origin, was con- 
 verted into a yellowish gelly-like substance, and wasted to less than 
 two-thirds the size of the nerve on the opposite side. The ganglion 
 was also yellowish and diseased. The muscular fibres of the affected 
 nerve seemed healthy : mastication was not observed to have been / 
 affected. 
 
 When the first branch of the fifth pair is injured, or its functions, 
 impeded or destroyed, either by experiments, by accidents, or disease, 
 the more important parts of the eye became inflamed or otherwise 
 diseased, sometimes to an extent sufficient to destroy the organ. 
 
 IV. Of the adaptation of the lens to distinct vision. The majority 
 
 Annals of Philosophy, May 1823. 
 
 f- Archives Generates de Mtdecine, Aout 1824.
 
 652 APPENDIX. 
 
 of physiologists have considered adaptation of the crystalline lens to the 
 objects observed as a matter of fact. Haller, however, seemed to have 
 entertained a different opinion, and to have denied that any adaptation of 
 the lens obtains. This opinion has recently been ably supported by the 
 reasoning of Dr. Milligan, the learned translator of M. Magendie's 
 Compendium of Physiology. Dr. Milligan states, that " the human 
 eye is a camera obscura, and, like it, receives the image of every object 
 accurately at every distance." But although we have no satisfactory 
 proof that any adjustment of the lens actually takes place, yet we con- 
 ceive that some adaptation of the eye, particularly as respects the motions 
 of the iris, and the resulting effects upon the cornea, may be ob- 
 served. On this subject, the most exact and conclusive observations 
 which have hitherto been adduced have been made by Jean Mile, 
 professor of physiology in the University of Warsaw.* The inferences 
 at which he has arrived are as follow : - 
 
 1. The eye does not see with the same distinctness objects at all 
 distances, but only when placed within a certain distance. 2. This 
 does not proceed from external causes, such as the diminution of the 
 optic angle, and the obscuration of the object by the intermediate air : 
 for to see clearly, and to see distinctly an object, are not identical. 3. 
 The causes of distinct vision are internal, and situated in the eye itself; 
 they are two in number, one disposes the eye for continuous distinct 
 vision, the other for transient distinct vision of objects at different dis- 
 tances ; but neither of them can act but within certain limits. 4. These 
 limits are greater for the presbyote than for the myope. 5. These fa- 
 culties both depend upon the action of the iris, which acts at the same 
 time in two ways to produce two effects ; first, the contraction of its 
 aperture, and secondly, the flexion of the cornea ; the alteration in the 
 size of the pupil being only visible. 6. The adjustment of the eye for 
 continuous distinct vision of objects contained within certain limits 
 depends not upon the greater density of the vitreous humour at the 
 bottom of the eye than towards the lens ; 7, but is owing to the dis- 
 fraction of the rays of light near the edge of the aperture of the iris, in 
 consequence of which there are formed, by a single external luminous 
 point, several foci instead of one, ranged successively in a line of a 
 certain length, so that the object may change its distance within certain 
 limits, and yet one of its foci shall always fall on the bottom of the eye. 
 8. This focal length is inversely as the magnitude of the pupil. 9. The 
 circumference of indistinct objects appears radiated, and to the pheno- 
 menon of confusion are added the motion and multiplication of the 
 
 * De la Cause qui dispose Pffiil pour voir distinctement les objects places a 
 differentes distances. Traduit du Polonais. Journal de Physiologic, torn vL 
 pp. 166, \W,etseq.
 
 OF THE NERVES OF THE SENSE OF SMELL. 53 
 
 image when the edges of bodies are brought near the side of the fasci- 
 culus of rays which enter the eye ; besides, the prismatic colours also 
 appear. 10. All these phenomena, which are observed in an eye per- 
 forming its functions, may be produced by an apparatus the structure 
 of which resembles that of the eye, and even by a common lens, sub- 
 stituting for the motions of the iris diaphragms or screens of different 
 sizes. 11. The nature of all these phenomena proves, that disfraction is 
 their common origin, and they may constitute a separate kind of optical 
 illusions, proceeding from disfraction. 12. The second cause which 
 disposes the eye for the momentaneous distinct vision of objects, depends 
 neither upon the action of the external muscles of the eye, nor the 
 advancement of the bottom of the eye, nor in change of form or position 
 of the crystalline lens ; but appears to be owing rather to the change of\ 
 curvature of the cornea by the contraction of the iris, which takes place 
 when the eye adjusts itself to see very near objects, as is proved by the 
 simultaneous approximation of the pupil. 
 
 OF THE NERVES CHIEFLY CONCERNED IN THE SENSE OF 
 SMELL. 
 
 (NoTEFF. Seep. 293.) 
 
 The first pair of nerves is chiefly distributed to those parts of the 
 nasal apparatus which are principally concerned in this function ; 
 namely, the olfactory or pituitary membrane, particularly at the upper 
 parts of the nasal cavities, and where it covers the spongy and 
 convoluted bones. The nasal branches of the fifth pair are distributed 
 rather to the accessary parts of the organ, than to the pituitary 
 membrane itself; they form a circle around the expansions of the 
 olfactory nerves, in the same manner as the ciliary nerves around the 
 retina. The first pair of nerves generally presents a size and de-N^ 
 velopement in proportion to the energy of smell, in the more perfect 
 animals ; whilst, on the other hand, it must be conceded, that the fifth 
 pair is the chief nerve of smell in fishes and the cetacece. It was 
 formerly doubted by Mery,* that the first pair of nerves are actually 
 the nerves of smell; and recently M. Magendief has revived these 
 doubts, and appealed to experiments in justification of them. That 
 the first pair are most intimately connected with the function of smell, 
 seems proved by the following facts : LoderJ found the olfactory nerves 
 destroyed in a man who was entirely deprived of the sense of smell. 
 A similar fact came under the observation of Oppert ; and Cerutti|| 
 
 * Brunet, Pr ogres de la Mtdecine, 1697- 
 
 f Journ. de Physiol. Exper. torn. iv. p. 169. 
 
 J Observatio Tumoris Scirrhosi in basi Cranii reperti. Jena>, 1779. 
 
 Dissertatio de Viliis Nervorum organicis. Berlin, 1815. 
 
 || Beschreibung der Pathologischen, $c. p. 208. Leipsig, 1819.
 
 654 APPENDIX. 
 
 relates the case of a man who had never enjoyed the sense, and in 
 whom, upon dissection, the olfactory nerves were ascertained to have 
 been entirely wanting. 
 
 It should not, however, be concealed, that Mery adduced equally 
 conclusive facts, in proof of the second branch of the fifth pair being 
 the chief nerve of this sense. He opened the heads of three persons 
 who had experienced no defect of the sense of smell, and in whom the 
 first pair of nerves was changed, so as apparently to have been in- 
 capable of performing their functions. 
 
 In our speculations respecting the sense of smell, it should be 
 recollected that, in order that this function may be duly performed, the 
 pituitary membrane must be constantly moistened by a fluid mucous 
 secretion. This secretion requires a continued supply of nervous 
 influence to promote it, under the constant evaporation it is ex- 
 periencing by the currents of air passing over it ; and such influence 
 we conceive to proceed chiefly from the first pair of nerves; these 
 nerves performing, perhaps, in addition, the office of transmitting the 
 impression made upon the pituitary membrane to the brain, or being 
 assisted in this part of their functions by the second branch of the fifth 
 pair ; and, perhaps, this latter nerve may become the chief medium of 
 the sensation in those cases where the first pair of nerves has been 
 \ injured or destroyed. 
 
 It should be recollected, that impressions made upon the organ of 
 smell, owing to the odoriferous particles having in some measure 
 combined with the mucus covering the pituitary membrane, will 
 continue for some short time after they have been made, and that they 
 powerfully affect the state of the brain and of the nervous system, 
 and even also influence the amorous propensities, and the states of 
 the genital organs. 
 
 OF THE FORMATION OF THE SPINAL MARROW AND BRAIN. 
 (NOTE GG. See pp. 313, 321326.) 
 
 I. Of the formation of the spinal marrow. The researches of 
 MM. Gall, Tiedemann, the Wenzels, Doellinger, Carus, and Des- 
 moulins, have furnished us with much interesting information on this 
 subject, and which, as far as %& ae~ enabled to judge from some 
 observations made by ourselves, seems to be, upon the whole, ex- 
 tremely correct. 
 
 The soft and gelatinous state of the embryo at the earliest periods 
 of its existence, the rapidity of its metamorphosis, and the difficulty of 
 demonstrating, owing to its colour and consistency, that part of the ner- 
 vous system which, from the circumstance of its supplying those parts 
 of the embryo that are first formed, as well as from other considera-
 
 OF THE FORMATION OF THE SPINAL CHORD. 655 
 
 tions, we are led to consider as the first which assumes an organised 
 appearance, combine to render the exact origin of the spinal marrow 
 difficult, if not impossible of demonstration. Reasoning from the 
 condition of the nervous system throughout the scale of the. animal 
 kingdom, from the manner in which the different organs seem to be 
 formed, from the organisation of some monstrous foetuses, and from 
 other considerations on which we cannot enter at this place, we are 
 disposed to conclude, in opposition to the opinions of some of the 
 writers alluded to, that the spinal marrow is itself produced from the 
 ramifications of the sympathetic ganglia ; that the semilunar ganglion 
 is the first part of the nervous system to assume an organised state ; 
 and that the subordinate ganglia, the spinal marrow, and lastly the 
 brain, come successively into existence, and gradually arrive at their 
 full developement.* 
 
 It is not until about the third or fourth week that a grayish-white 
 fluid may be detected in the cavities of the head and spine. From 
 the fourth to the fifth week the medulla oblongata may be distinctly 
 seen. It is then about twice as thick as the medulla spinalis, which, 
 before the developement of the limbs, is of an equal thickness through- 
 out its whole length, and presents a slight curvature near the com- 
 mencement of the medulla oblongata, owing to the flexion of the head 
 upon the chest. The spinal marrow at this time consists of two white 
 strips of medullary matter, which offers a manifest decussation at the 
 place where it curves forwards at the margin of the inferior extremity 
 of the pyramids. It is not, however, the whole of the two cords of 
 the marrow that cross, but the middle or pyramidal fasciculi of each. 
 The spinal marrow descends from this point through the whole extent 
 of the canal to the interior of the caudal prolongation. 
 
 At the fifth week these stripes or cords form, by the junction of 
 
 * The inferences contained in the above paragraph was first published by us in 
 1820, and subsequently, in the former edition of the Appendix to this work, which 
 appeared at the commencement of 1824. We are induced to state this, because we 
 conceive ourselves entitled to whatever credit may belong to the having been the 
 first to state the above facts. Late writers, in their allusions to this subject, have 
 referred to the writings of Gall, Serres, and others, who have stated somewhat 
 similar facts and views, but at a period posterior to that at which our ob- 
 servations were made and published. The first volume of M. Serres* work, which 
 contains and illustrates some views similar to those which we had advanced, was 
 not published till late in 1824. And M. Gall's work on the functions of the brain, 
 which contains similar facts to those previously insisted upon by us, respecting the 
 gradual developement of the nervous system, we did not see until the distinguished 
 author did us the honour of presenting us with a copy of it in 1826 ; and it wa's 
 published between the years 1822 and 1826. Our examinations into this subject, 
 and into the gradual developement of the nervous system through the different 
 classes of animals, commenced as early as 1813, whilst enjoying uncommon facilities 
 for such investigations, in the northern islands of Scotland.
 
 656 APPENDIX. 
 
 their interior and anterior margins, a longitudinal gutter : their exter- 
 nal and posterior margins are then full and prominent. 
 
 At the seventh week the spinal marrow is open throughout its whole 
 length. On each side- of the fourth ventricle a straight thin lamina is 
 put forth, which inclines from without inwards, applying itself to that 
 of the opposite side, without, however, uniting with it: these are the 
 rudiments of the cerebellum, springing from the restiform bodies. The 
 cervical enlargement begins to appear, particularly its cephalic extre- 
 mity. The formation of the limbs coincides with that of the corre- 
 sponding enlargements of the cord,. The longitudinal raphe, formed 
 by the approach of the interior margins of the two cords consti- 
 tuting the marrow, is continued upwards, and separates the tubercles, 
 that is, the laminse which represent them : the optic thalami are de- 
 veloped. 
 
 At the commencement of the third month the marrow is still open 
 at its superior half, and extends from the extremity to the sacrum. The 
 tubercula quadrigemina are voluminous, hollow, and separated by the 
 median furrow : the optic thalami are full. The two cervical and lum- 
 bar prominences are a third of a line thicker than the body of the 
 marrow: M. Tiedemann has not observed the junctions of its exterior 
 margins until the end of the third month. M. Serres has seen it a fort- 
 night earlier. This junction takes place from beneath upwards. 
 
 At twelve weeks the marrow extends only to the middle of the sa- 
 crum. The tubercula quadrigemina are united and form a canal : at 
 this period the mammillary eminences and the corpora striata may be 
 seen. The internal canal, which is now formed by the junction of the 
 margins of the marrow, communicates with the fourth ventricle. Ac- 
 cording to M. Desmoulins, this canal results from a sinus, formed by 
 the fold of the pia mater, as it dips into the interior of the marrow, or 
 rather between both the cords of which the marrow is then formed. 
 The precise period at which this canal is completely obliterated, has not 
 been ascertained. M. Carus conceives that the pectoral portion of the 
 marrow is the first to close, and that the canal is obliterated along its 
 whole extent owing to the formation of the gray substance. 
 
 At the fourth month the spinal marrow reaches only to the base of 
 the sacrum ; the cervical eminence is larger than the lumbar. The 
 two contiguous cords of the marrow divide, in the medulla oblongata, 
 each into three others much smaller. The internal or pyramidal forms 
 a tolerably broad surface, as in fishes and reptiles, and evidently 
 crosses, as was already noticed, with that of the other side, about the 
 fourth or fifth week of the foetal life. The middle cord, or the corpus 
 oblivare, is placed above the former ; some of its fibres ascend to the 
 tubercula quadrigemina, and unite with those proceeding from the 
 opposite side, in order to form the vault of the aqueduct of Sylvius.
 
 OF THE FORMATION OF THE SPINAL CHORD. 657 
 
 The external or restiform cord, proceeding from the lateral and poste- 
 rior portion of the marrow, forms the prominent paries of the fourth 
 ventricle, and advances into the cerebellum. At this period the annu- 
 lar protuberance is perceptible. The interior canal of the marrow is 
 now very narrow, and still communicates with the fourth ventricle. 
 It is not until towards the end of the fourth month that the lumbar and 
 sacral nerves become elongated, and form what has been improperly 
 called the cauda equina, which at first does not exist. The pia mater, 
 which penetrates by the posterior median furrow, is observable in the 
 centre of the marrow. 
 
 At the fifth month the pyramidal 'eminences are evident : there still 
 exists a communication between the fourth ventricle and the canal of 
 the marrow. The two swellings of the cord are well marked. The 
 annular protuberance becomes more distinct, and the corpora striata 
 are large. The increased thickness of the tubercles has narrowed con- 
 siderably the cavity which they formed by their approach. The marrow 
 extends at this period no farther than the margin of the fifth lumbar 
 vertebra. 
 
 The human embryo possesses a caudal prolongation until the fourth 
 month of uterine life. At this period it disappears, and its disappear^ 
 ance coincides with the ascension of the spinal marrow in the vertebra 
 canal. If the ascension of the marrow is arrested, the human foetus is 
 born with a tail, as has been observed in several cases. The circum- 
 stance of the spinal marrow descending lower in the vertebral canal the 
 younger the foetus, has attracted the particular notice of those physio- 
 logists to whose researches we are indebted for our knowledge of the 
 subject under consideration. M. Tiedemann, who offers the most 
 rational explanation of this phenomenon, supposes that the marrow 
 descends not so far in the canal of the full-grown foetus as in that of 
 the early embryo, because the vertebral column grows more rapidly in 
 length than the nervous chord which it is destined to protect. 
 
 Towards the end of the sixth month the corpora olivaria form a 
 well-marked lateral projection. At this epoch may be seen the internal 
 and middle chords, forming the peduncles of the brain, plunging into 
 the optic thalami, which they formed by their enlargement. The fibres 
 composing them may be perceived on scraping away a thick pulpy 
 layer from their interior and superior aspect. A few fibrous portions 
 detach themselves from their internal side, and proceed outwards to the 
 mamrnillary eminence. All the other fibres continue to advance from 
 behind forwards, and from within outwards, beneath the corpora striata, 
 and proceed, in a diverging form, to the cerebral lobes. A few fibres 
 may be seen entering them. In the course of the sixth month the 
 transverse furrow separating the eminentia quadrigemina begins to 
 appear, or rather, each of these prominences becomes more developed.
 
 658 APPENDIX. 
 
 At the seventh month the length of the marrow is nearly the same. 
 The transverse fibres which compose the annular protuberance are now 
 distinct, and they may be seen interlacing with those of the pyramids. 
 This part results from the following disposition : the fibres of one lateral 
 hemisphere of the cerebellum are continued beneath the spinal marrow 
 with the fibres of the opposite hemisphere, by layers which alternate 
 with the planes of fibres proceeding obliquely from the pyramids to the 
 optic thalami. 
 
 At the eighth month the marrow reaches only to the fourth lumbar 
 vertebra, and at the ninth month it is'at the margin of the third. The 
 interior canal of the marrow still exists, and remains until from six 
 months to a year after birth. It is at the last months of gestation that 
 the disposition of the medullary fibres of the marrow may be most dis- 
 tinctly traced, and the mode of formation of the mesocephalon or pons 
 Varolii, which is only a continuation of the marrow, becomes most 
 evident. 
 
 All the white or medullary parts which are seen at the base of the 
 brain, manifestly arise from the superior part of the spinal marrow.* 
 
 II. Of the formation of the brain. The interesting results of Dr. 
 Tiedemann's researches on this subject may be reduced to the following 
 heads : 
 
 " 1. In the commencement of pregnancy, especially about the 
 second month, the earliest period at which the brain can be rendered 
 perceptible by the action of alcohol, this organ is very small in propor- 
 tion to the spinal marrow. In fact, it results from the prolongation 
 upward and forward of the two principal chords, the olivary and 
 pyramidal. All its superior part is open, or, more properly speaking, 
 forms a broad gutter, which at once comprehends the third ventricle, 
 the aqueductus Sylvii, the fourth ventricle, and calamus scriptorius. 
 This gutter is uninterruptedly continuous with the canal which traverses 
 the whole length of the marrow. 
 
 " 2. The cerebellum evidently originates from the spinal marrow ; 
 from the lateral parts of which arises on each side a small flattened 
 chord. These two, at first so distinct and separate that they may be 
 readily parted without laceration, afterwards unite so as to form the 
 roof of the fourth ventricle. Then only the brain, viewed from above, 
 ceases to represent a gutter ; and the laminse and branches of the cere- 
 bellum are formed at a much later period. 
 
 " 3. The mass which supports the tubercula quadrigemina equally 
 shews itself in its origin, under the form of two small thin membranes, 
 which arise from the olivary chords of the spinal marrow, and which, 
 
 * Ollivier sur le Dtveloppement de la Motile Epiniere.
 
 OF THE FORMATION OF THE BRAIN. 659 
 
 when they cease to be distinct, represent a vault covering a large ven- 
 tricle, whose successive contraction gives rise to the aqueductus Sylvii. 
 
 " 4. The pyramidal chords of the spinal marrow, which take a 
 direction below upward, and from behind forward, after having pro- 
 duced two swellings or ganglia, the optic thalami and corpora striata, 
 each terminate by a lamina, which, bent from before backward, and from 
 the side towards the superior and internal part, forms the commence- 
 ment of the hemisphere of the brain. These membranes and thin 
 hemispheres are so small at the second month that they scarcely cover 
 the corpora striata. In proportion as they increase they extend back- 
 ward, and cover, at the third month, the optic thalami ; at the fourth, 
 the tubercula quadrigemina ; and at the sixth or seventh, the cere- 
 bellum. The lateral ventricles result from their inversion. 
 
 " 5. The medullary fibres of the pyramidal chords, previously to the 
 formation of the tuber annulare, are immediately continuous with those 
 of the crura cerebri ; from whence the eye may readily trace them in 
 the optic thalami and corpora striata, and see them afterwards spread- 
 ing and radiating in the hemispheres. 
 
 " 6. The parietes of the hemispheres gradually increase in thick- 
 ness in proportion as new strata of cerebral substance are deposited on 
 their surface ; and convolutions are not decidedly seen till towards the 
 close of pregnancy. 
 
 " All these combined facts clearly demonstrate, in the opinion of 
 Dr. Tiedemann, that the brain and cerebellum proceed from the spinal 
 marrow; or that, to employ a modern expression, they are an efflores- 
 cence of it. In running through the scale of animals, ample confir- 
 mation may be found of the assertions here advanced. The structure 
 of the encephalon and spinal marrow becomes complicated in propor- 
 tion as we ascend from fishes to reptiles, birds, and mammalia. If the 
 contrary opinion were correct if the spinal marrow were derived from 
 the brain the cerebrum and cerebellum must necessarily be found the 
 first formed in the foetus, which is not the case. It is equally necessary 
 that, in the animal scale, where it is impossible to mistake a gradation 
 in the figure and developement of the organs, that a complete brain 
 should exist previously to any trace of a spinal marrow ; but this is 
 never observed. Comparative anatomy, on the contrary, shews that the 
 spinal marrow is very large in the inferior classes of animals, while the 
 brain forms but a small and delicate prolongation of it ; and in ascend- 
 ing from reptiles to birds and mammalia, it is seen gradually to in- 
 crease in volume and complication, as absolutely takes place in the 
 fostal encephalon."* 
 
 * Prochaska and the Wenzels conclude, from their microscopic observations, 
 that the brain is composed of a number of small globules, of a tolerably firm con-
 
 660 
 
 APPENDIX. 
 
 III. Cerebri generatim, cerebelli et cerebri spedatim, pondus, A 
 statu embryonis usque ad decrepitam hominis eetatem. (Wenzels "De 
 penitiore Cerebri Structura."*) 
 
 .ETAS. 
 
 Pondus to- 
 tius cerebri. 
 
 Pondus 
 cerebri. 
 
 Pondus 
 cerebelli. 
 
 Ratio cerebri 
 in cerebellum. 
 
 Embryo Masculus quinque fere mensium 
 Embryo Foemineus septem mensium 
 Embryo Fcemineus octo mensium 
 
 Grana. 
 720 
 2310 
 4960 
 6150 
 15240 
 13050 
 20250 
 24420 
 20940 
 21820 
 22200 
 24120 
 20490 
 20580 
 22590 
 22500 
 22620 
 19080 
 23970 
 
 Grana. 
 683 
 2160 
 4610 
 5700 
 13380 
 11490 
 17760 
 21720 
 18474 
 19040 
 19500 
 21480 
 18060 
 18270 
 20070 
 19780 
 20200 
 16500 
 21210 
 
 Grana. 
 
 37 
 150 
 350 
 450 
 1860 
 I860 
 2490 
 2700 
 2466 
 2760 
 2700 
 2640 
 2430 
 2310 
 2520 
 2720 
 2420 
 2580 
 2760 
 
 18J? : 1 
 14| : 1 
 
 13& : 1 
 12 : 1 
 
 7& : 1 
 7i&: 1 
 m : 1 
 8i 3 : 1 
 7| :1 
 
 w - 1 
 
 7& : 1 
 8' T : 1 
 78 : 1 
 
 7ti i 
 
 7fi : 1 
 m : 1 
 8&: 1 
 6&: 1 
 7gi : 1 
 
 
 
 
 
 
 Vir viginti duorum annorum 
 Vir viginti quinque annorum 
 Vir triginta unius anni 
 Vir quadraginta sex annorum 
 Vir quinquaginta quatuor annorum 
 Vir quinquaginta sex annorum 
 
 Vir septuaginta duorum annorum 
 
 Vir octogenarius .'. 
 
 
 
 * It will be perceived that the Wenzels have given these as the whole of their 
 observations, and not as the mean of numerous experiments made to ascertain the 
 medium results at each particular epoch of life. 
 
 sistence, contained in a flocculent pulp. The researches of M. Bauer into the 
 ultimate structure of this organ are more precise. He considers that the brain and 
 nerves consist of extremely delicate fibres, formed of minute globules, connected 
 together by a transparent gelatinous fluid, or viscid mucus, which is soluble in 
 water. These globules vary in dimensions, from ^ to ^ parts of an inch. " The 
 principal difference," he states, " in the appearance of the different parts of the 
 brain, consists in the proportions which the quantity of mucus and fluid bear to the 
 quantity of globular tissue, and, in some measure, in the size of the globules. The 
 cortical substance of the cerebrum and cerebellum is made up by the small globules, 
 the gelatinous fluid and mucus being very abundant. The medullary substance in 
 the cerebum and cerebellum differs from the above, in the large globules prevailing, 
 the mucus being more tenacious and less abundant. The crura cerebri and cere-
 
 OF THE CJBPHALO-SPINAL FLUID. 661 
 
 IV. Of the cephalo-spinal fluid. The recent researches of M.\ 
 Magendie* have shewn that there exists around the cerebro-spinal axis 
 a copious exhalation of a limpid fluid, contained between the pia mater 
 and the arachnoid. This fluid seems to be an additional protection to 
 the nervous masses against sudden shocks and concussions. M. Des- 
 moulins says, that it is met with more abundantly in mammiferous 
 animals than in fishes and birds. M. Magendie states, that it gradually 
 disappears after death, so that but little remains twenty-four hours after 
 this event. In experiments upon living animals it has been found in so 
 great a quantity as to be thrown out to the distance of several inches 
 when the canal has been punctured as deep as the pia mater. It is 
 most abundant in the cervical and lumbar regions, and at the height 
 of the fourth ventricle : it flows not only from the spinal canal to the 
 cranial cavity, but also from the exterior of the cerebrum into its ven- 
 tricles. According to M. Magendie, the fourth ventricle communicates 
 with the external surface of the cerebro-spinal masses, and consequently 
 
 belli resemble the medullary substance, only that the mucus and fluids are more 
 abundant, and in greater proportion than the globules. 
 
 The medulla oblongata, the corpora pyramidalia and olivaria, have nearly the 
 same structure as the medullary substance, but the mucus is very abundant. In 
 the medulla spinalis the mucus and fluid are less tenacious, but in greater quantity 
 than in any part of the brain. 
 
 Every part of the brain is pervaded by innumerable blood-vessels, which are of 
 considerable size towards the centre, and branch out to an extreme degree of minute- 
 ness ; but even then carry red blood. The arteries in the brain never anastomose, 
 and are accompanied by veins still smaller, which are supplied with valves. 
 
 This view of the structure of the cerebrum and cerebellum is calculated, in the 
 opinion of Sir Everard Home, to throw considerable light on the functions of the 
 brain. He thinks that the cortical substance is one of the most essential parts of 
 this organ, and considers it the seat of memory, from having observed that that 
 faculty is destroyed or materially diminished by any undue pressure upon the upper 
 anterior part of the brain, as in that requiring the operation of trepan. In hydro- 
 cephalus, on the other hand, where the fluid is in large quantity, and there only 
 remain the cortical part of the brain and pons Varolii, all the functions go on, and 
 the memory can retain passages of poetry. In one case, slight pressure upon the 
 sinciput produced complete derangement, and violent excesses of the passion of lust, 
 which went off by removing, by the trepan, the depressed bone. 
 
 The veins being so minute, and being supplied by valves, perform, in the opinion 
 of this physiologist, the office of absorbents, which have never been observed in the 
 brain, and carry the absorbed matter into the superior longitudinal sinus, which 
 appears more a reservoir than a vein. 
 
 The transparent mucus being not only one of the most abundant materials of 
 which the brain itself is composed, but also the medium by which the globules are 
 kept together, and serving the same purpose in the nerves, Sir E. H. thinks that 
 the communication of sensation and volition depends upon it. He concludes, from 
 all his experiments and observations, that this fluid, as well as the principal ma- 
 terials of which the body is composed, are met with in the blood. 
 
 * Journ. de Physiol. Experiment, t. vii. p. 1 ; t. viii. p. 211.
 
 662 APPENDIX. 
 
 with the external space in which this fluid is contained, by means of a 
 round opening, which he calls the aqueduct, situated between the two 
 posterior arteries of the cerebellum. This opening he calls the entrance 
 into the cerebral ventricles; and through it this fluid passes and 
 repasses into the fourth ventricle, and through this latter into the third 
 and lateral ventricles ; a flux and reflux of the fluid taking place from 
 the brain to the spinal canal, and vice versd, during the motions of the 
 \ brain occasioned by respiration, and according to the varying circum- 
 stances of the parts contained in the cranial and spinal cavities. 
 
 This fluid seems to adapt kself 19 the positions, movements, and 
 conditions of the brain and spinal chord; to be diminished when the 
 blood-vessels of the brain are congested or injected ; to preserve a cer- 
 tain degree of pressure, by becoming more abundant when the brain is 
 either less vascular or of diminished bulk ; and to protect the cerebro- 
 spinal nervous masses from the effects of concussions and external 
 injuries. In its constitution it resembles in every respect the most 
 limpid of the serous exhalations of the body. M. Magendie says, that 
 he has found it very abundant in idiots and persons of weak intellects, 
 and, on the contrary, in small quantity in those whose intellectual 
 faculties were active and fully developed : hence he is led to infer that 
 the quantity of this fluid is in an inverse ratio to the developement of 
 the mental faculties. 
 
 OF THE FUNCTIONS OF THE CEREBRO-SPINAL SYSTEM OF 
 NERVES. 
 
 (NOTES G G. See pp. 323326, et seq.) 
 
 I. General view of the nervous system through the different classes 
 of animals.* At a former part of these notes we divided the nervous 
 system into two principal orders, viz. the ganglial or vital, and the 
 cerebro-spinal. Of the former we remarked, that the globules of which 
 it is constituted are disseminated in the structure of the Zoophyta; are 
 organised into a homogeneous ganglion, but imperfectly developed, in 
 many of the orders of the Echinodermata ; and are arranged into gan- 
 glia, communicating by means of intermediate chords, in the Annelides, 
 Cirrhipedes, &c. The homogeneous nature of the ganglions disappears 
 as the animal is provided with separate organs, especially with those 
 devoted to the senses; and, with the developement of separate organs, 
 accessory or subordinate ganglions make their appearance, which latter, 
 
 * This section is reprinted verbatim as it stood in the former edition of these 
 Notes, and contains the same statements which were made public by us as early as 
 1820. But, even as late as the date of the former edition of this work, we are not 
 aware that similar sentiments had been published elsewhere.
 
 OF THE NERVOUS SYSTEM. 663 
 
 in the progressive rise in the scale of the animal kingdom, assume, in 
 the anterior part of the body of the animal, the character of the rudi- 
 ments of an encephalon. So long as there exists only simple ganglia 
 without any spinal chord, the ganglion representing the rudiments of 
 an encephalon surrounds the resophagus in the manner of a ring. This 
 encephalic ganglion is intimately connected with the ganglial functions, 
 and presides over those imperfect operations of sense with which the 
 animal is endowed, and which are those more immediately subordinate 
 to its functions of nutrition, and to its immediate preservation. 
 
 In all animals possessing no other rudiments of a cerebro-spinal 
 system than an accessory ganglion disposed around the oesophagus, the 
 manifestation of volition is by no means distinct ; their movements 
 appear to be the result- neither of reflection nor of choice. An obscure 
 instinct seems to be the actuating principle of those operations, which 
 may assume in them the nearest resemblance to those of volition. 
 
 As we rise in the scale of the animal creation, and as we perceive 
 the relation between the exterior world and the animal to be more 
 extended and intimate, owing to the extension and perfection of the 
 organs of sense and volition, so we perceive the cerebro-spinal system 
 more perfectly organised, more fully developed, and more complicated 
 in its structure. With the formation of the spinal chord, in the class 
 of fishes,* the accessory encephalic ring or ganglion disappears, and 
 the encephalon is surrounded by a protecting case, which is continued 
 over the chord itself. 
 
 The diversity and complication of the parts constituting the ence- 
 phalon increase as we rise through the four superior classes of animals. 
 In the Hymenopterce, especially in the bees, each sensorial nerve pos- 
 sesses an enlargement in the encephalon appropriated to itself, from 
 which it takes its origin ; but all these enlargements coalesce in a central 
 mass composed of two symmetrical hemispheres, the prototype of the 
 cerebral hemispheres of all the superior classes. 
 
 In another part of these notes we gave a full detail of the progres- 
 sive developement of the cerebro-spinal system of nerves in the human 
 fcetus. It will readily appear, from what we there advanced, that a 
 similar gradation (from the simplest to the most complicated and per- 
 fect state of the nervous structure) to that which we observe in ascend- 
 
 * M. Desmoulins has lately shewn that many reptiles and several fishes offer 
 not a trace of gray substance in their spinal chords, and that, on the contrary, this 
 part is entirely composed of white substances. He has also found that the sturgeon 
 is entirely without a cerebellum ; and that its fourth ventricle possesses a con- 
 siderable extent. He concludes that the dimensions and extreme developement of 
 the fourth ventricle always coincide with the extreme developement of the eighth 
 pair of nerves. The circumstance of the gray substance being wanting in the 
 spinal chord of some fishes, militates against the opinion of M. OUivier stated at a 
 subsequent page.
 
 664 APPENDIX. 
 
 ing the scale of the animal creation, may be remarked in the changes 
 which the nervous system undergoes in the progressive evolution of the 
 human embryo. In the lowest of all the animal kingdom the nervous 
 matter is not organised in a manner distinct from the tissue constituting 
 the animal ; the nervous globules are disseminated through an amor- 
 phous and pulpy mass. As we ascend the scale we perceive this 
 particular structure arranged in succession into ganglia ; then into 
 ganglia and a spinal marrow ; and, lastly, into ganglia, a spinal marrow, 
 and a brain ; each becoming more perfect as we ascend the scale, and 
 the gradation from the one to the other being nearly unappreciable in 
 the species or genera, but sufficiently remarkable in the orders. A 
 developement of the nervous system, in which a similar progression to 
 this is observed, takes place in the formation of the human foetus and 
 in that of the most perfect animals ; and a similar type to that in which 
 this system exists in the lower orders, is adopted at first in the highest, 
 and preserved, every successive state of organisation which this 
 system assumes in its progressive developement being additions to that 
 previously adopted, whilst, in the process of formation as respects the 
 entire animal, each intermediate series from the lowest, which is its first 
 state of existence in the embryo, is successively passed through, until 
 the foetus arrives at that specific condition and stage of organisation 
 bestowed on the species to which it belongs. Thus the human foetus, 
 in the progress of its formation, as respects both its nervous system and 
 other organs and textures, runs through the different grades of organi- 
 sation, from the lowest to that at the head of which it is itself placed.* 
 
 * See the further conclusions connected with this subject at which we have 
 arrived, in the Note on the Developement of the Foetus. 
 
 Sir Everard Home, MM. Geoffrey Saint Hilaire and Blainville, and Dr. 
 Schultze, consider that the skeleton of animals was intended more to prevent the 
 nervous and vascular systems from being compressed or suffering any other injury, 
 than to give form and the power of motion to the body /> The last-named physio- 
 logist (Allgemeine Encyclop'ddie fur Practische Arzte und Wundarzte, 1 theil, 
 ] band, Leip. 1820.) concludes : 
 
 1 . " That the spinal marrow and vertebral column at all times exist together, 
 even when only the slightest vestiges of the osseous system can yet be found. 
 
 2. " That the osseous and nervous systems have between them numerous inti- 
 mate relations, both physiological and pathological. 
 
 3. " That the more the exterior hard envelopement penetrates the interior of 
 the body, and approaches towards the nervous system, the more also are the pheno- 
 mena of sensibility developed, and vice versa. 
 
 4. " That the organs possess more or less importance according as they are 
 more or less protected from external influence by bones." 
 
 The blood proceeding from the mass of muscles, spine, and spinal marrow, is 
 emptied into the great spinal veins, as into a reservoir ; from whence it passes into 
 the veins placed on the sides and anterior surface of the spine, and thence into the 
 superior and inferior cavae. 
 
 ' 
 
 . . ' 
 

 
 OF THE CEREBRO-SPINAL NERVOUS SYSTEM. 665 
 
 1 1. Of the functions of distinct parts of the cerebro-spinal order of 
 the nervous system. The researches of M. Flourens into the functions 
 of the cerebro-spinal order of nerves, have lately added greatly to our 
 knowledge as to actions in which distinct portions of this part of the 
 nervous system are more particularly concerned. But before we can 
 give any account of the conclusions at which he has arrived, we must 
 briefly notice the meaning he has attached to some of the terms which 
 he employs. 
 
 The term contractility he very properly limits to the property 
 inherent in the muscular fibre only, of undergoing brisk contractions 
 under the application of stimuli ; and the term sensibility , to imply the 
 property of experiencing sensations. The word irritability he applies 
 to the property of exciting sensation and motion, without evincing or 
 experiencing them. This application of the word is by no means 
 judicious ; it must, however, be allowed, that it is not easy to find a 
 term which can convey the meaning wished to be attached to it. 
 
 The questions proposed by M. Flourens, and which he has en- 
 deavoured to ascertain by experiment, are: 1st, from what points of 
 the nervous system artificial irritation may set off to arrive at a 
 muscle ; 2d, to what points of this system an impression must be 
 propagated to produce sensation ; 3d, from what points voluntary 
 irritation descends, and what parts of this system must be influenced to 
 produce it regularly. 
 
 M. Flourens commenced with the nerves, and fully confirmed the 
 views usually entertained respecting their functions. He has shewn, 
 in a satisfactory manner, " that, in order to effect contraction, a free 
 and continued communication is requisite between the nerve and 
 muscle; and that to produce sensation, a similar communication with 
 the brain is equally necessary. Hence he concludes, that neither 
 contraction nor sensation belong to the nerve ; that these two effects 
 are distinct ; that they may take place independently of each other ; 
 and that these propositions hold good, at whatever part, and in 
 whatever branch of a nerve, the communication is interrupted. 
 
 " Employing the same method with regard to the spinal marrow, 
 he arrived at similar conclusions. When it is irritated in any given 
 point, contractions are excited in all the muscles which derive their 
 nerves from below this point, if the communication remains free ; but 
 not if the communication be intercepted. Exactly the reverse obtains 
 with regard to sensation ; and, as in the nerves, the government of the 
 
 By what power, it has been asked, is the blood which arrives in the two great 
 spinal veins, driven from them ? These veins may effect the propulsion of the 
 blood which they contain by the vital properties with which they are endowed ; 
 or the blood may be drawn out of them, owing to their proximity to the cava, by 
 the dilatation of the cavities of the heart ; or by both influences combined.
 
 666 APPENDIX. 
 
 will requires the same freedom of communication as sensation, the 
 muscles beneath the intercepted part no longer obey the animal, and 
 he has no feeling in them : in fine, if the spinal marrow be intercepted 
 at two points, the muscles which receive their nerves from this interval 
 experience contractions alone ; but the animal does not command them, 
 nor receive from them any sensation." M. F. farther inferred, from 
 his experiments respecting the functions of the spinal marrow, that 
 sensation and contraction belong no more to it than to the nerves. 
 
 He next directed his researches to the brain, in order to ascertain 
 the point whence irritation departed, and the point where sensation 
 arrives, and to determine their respective co-operation in acts of 
 volition. Advancing from the medulla oblongata towards the he- 
 mispheres, M. Flourens first examined how far it was possible to go 
 and still produce sufficient irritation on the muscular system, when he 
 arrived at a point where these irritations disappeared : " then, taking 
 the brain at the opposite part, he irritated it at points deeper and 
 deeper, as long as he did not act upon the muscles ; and when he did 
 begin to act upon them, he found himself at the same point where the 
 action had ceased in ascending. This part is also that where the 
 sensation of irritation applied to the nervous system likewise ceases : 
 above this, punctures and wounds do not excite pain. Thus M. 
 Flourens pricked the hemispheres without producing contraction of the 
 muscles, or the appearance of pain in the animal ; he removed them in 
 successive slices : he did the same with regard to the cerebellum ; he 
 removed at once the hemispheres and cerebellum. The animal re- 
 mained passive. The corpora striata and the optic lhalami were 
 attacked, and removed without any other effect : the iris was not 
 contracted, nor even paralysed. But, when he pricked the tubercula 
 quadrigemina, trembling and convulsions began, and these increased 
 in proportion as he penetrated into the medulla oblongata. Pricking 
 the tubercles, as well as the optic nerve, produced quick and continued 
 contraction of the iris. These experiments agree with those of Lorry, 
 published in the third volume of the Memoires des Savans etranyers. 
 1 Neither the irritation of the brain, nor of the corpus callosum itself, 
 produces convulsions : it may even be removed with impunity. The 
 only part among those contained in the brain which has appeared 
 uniformly and universally capable of exciting convulsions, is the 
 medulla oblongata : it is this part which produces them, to the ex- 
 clusion of every other.' They contradict the experiments of Haller 
 and Zinn, with regard to the cerebellum; but, from what M. Flourens 
 has seen and pointed out, it appears that these physiologists had 
 touched the medulla without being aware of it. He concludes that the 
 medulla oblongata and the tubercles are (in his language) irritable ; 
 which means that they are conductors of irritation, like the spinal
 
 OF THE CEREBRO-SPINAL NERVOUS SYSTEM. 667 
 
 marrow and nerves, but that neither the cerebrum nor cerebellum 
 possesses this property. The author hence concludes, likewise, that 
 these tubercles form the continuation and superior termination of the 
 spinal chord and medulla oblongata ; and this opinion is in conformity 
 with their situation and anatomical connexions." 
 
 Wounds of the brain and cerebellum do not excite pain any more 
 than convulsions. Hence M. Flourens infers, that to them. the im- 
 pression received by sensible organs must be conveyed, in order that 
 the animal may experience a sensation. He appears to have esta- 
 blished this proposition in a satisfactory manner with regard to the 
 senses of sight and hearing ; for when both lobes of the cerebrum are 
 removed, the animal becomes both blind and deaf. " Instead of 
 saying, with M. Flourens, that the cerebral lobes are the only organs 
 of sensation, we should restrict ourselves to ascertain facts, and con- 
 tent ourselves with saying that these lobes are the sole receptacle where 
 the senses of sight and hearing can be perfected, and become percep- 
 tible to the animal. If we wished to add to this, we should say that 
 they are likewise those where all the sensations take a distinct form, and 
 leave durable traces on the memory, that they serve, in a word, as the 
 seat of memory ; a property by means of which they furnish the animal 
 with materials for judgment. This conclusion, thus reduced to proper 
 terms, becomes the more probable, in that, besides the verisimilitude 
 which it receives from the structure of these lobes, and their con- 
 nexion with the rest of the system, comparative anatomy offers another 
 confirmation in the constant relation of the volume of these lobes with 
 the degree of intelligence of the animal." 
 
 M. Flourens next examined the effects which follow the extirpation 
 of the tubercula quadrigemina. " The removal of one of them, after 
 a convulsive movement, which soon ceases, produces, as a permanent 
 result, blindness of the opposite eye, and involuntary staggering ; that 
 of both tubercles renders the blindness complete, and the staggering 
 more violent and long continued. The animal, however, retains all its 
 faculties, and the iris continues contractile. The deep extirpation of 
 the tubercle, or the section of the optic nerve only, paralyses the iris : 
 from which the author infers, that the removal of the tubercle only 
 acts as the division of the nerve would do ; that this tubercle is only 
 a conductor with regard to vision ; and that the cerebral lobe alone 
 is the seat of the sensation, the point where it is consummated and 
 passes into perception." 
 
 M. F. next investigated the functions of the cerebellum, and found 
 that, during the removal of the first layers, " there appeared only a 
 slight weakness and want of harmony among the movements. At the 
 middle layers a disturbance nearly general was manifested. The 
 animal, in ntinuing to see and hear, only executed quick and irre-
 
 668 APPENDIX. 
 
 gular movements : the faculty of flying, walking, and keeping itself 
 standing, were lost by degrees. When the itfgf was cut off, this 
 faculty of performing regulated motion had entirely disappeared. 
 Placed upon the back he did not rise, but continued to see the blow 
 which menaced him ; he heard sounds, and endeavoured to shun the 
 danger which was threatened : in a word, feeling and volition were 
 retained, but the power over the muscles was lost ; scarcely could he 
 support himself with the assistance of the wings and tail. In depriving 
 the animal of the brain, it was thrown into a state resembling sleep : 
 in removing the cerebellum, it was brought to a state resembling in- 
 toxication." 
 
 The reporters to the Institute on the inquiries of M. Flourens, have 
 drawn the following conclusions " from a rigorous examination of the 
 facts which he has established : The integrity of the cerebral lobes is 
 necessary to the exercise of sight and hearing : when they are removed, 
 the will no longer manifests itself by voluntary acts. However, when 
 the animal is immediately excited, he performs regular movements, as 
 if endeavouring to avoid pain or inconvenience ; but these movements 
 do not effect his purpose, most probably because the memory, which 
 has been removed along with the lobes that constituted its seat, no 
 longer affords grounds or elements of judgment: these movements 
 have no consistency, for the same reason that the impulse which 
 caused them neither leaves any remembrance nor permanent volition. 
 The integrity of the cerebellum is necessary to the regularity of loco- 
 motion : let the brain remain, the animal will see, hear, and have 
 evident and powerful volition; but if the cerebellum be removed, .he 
 will never find the balance necessary to locomotion. As to the rest, 
 irritability remains in parts without the brain or cerebellum being ne- 
 cessary. Every irritation of a nerve brings it into play, in muscles to 
 which it is distributed : every irritation of the spinal marrow excites it in 
 all the members beneath the point of its application. It is quite at the 
 top of the medulla oblongata, at the point where the tubercula quadri- 
 gemina join it, that this faculty of receiving and propagating irritation 
 on the one hand, and pain on the other, ceases. It is this point at 
 which sensation must arrive in order to be perceived : it is from hence 
 that the mandates of the will must emanate. Thus, the continuity of 
 the nervous organ from this point to the different parts of the body is 
 requisite for voluntary motion, and for the perception of impressions, 
 whether external or internal." 
 
 Thus, then, the property of nervous irritability, or of receiving and 
 conducting sensation and irritation, is limited to the nerves, spinal chord, 
 medulla oblongata, and corpora quadrigemina ; " the integrity of the 
 optic thalami is not essential to the contractility of the iris ; the sen- 
 sations of light and of sound reside in the cerebral lobes, and there also
 
 OF THE FUNCTIONS OF THE SPINAL CHORD. 669 
 
 all other sensations acquire distinctness and durability ; the spinal chord 
 combines the muscular contractions so as to produce motion in the 
 joints ; and the cerebellum regulates these movements, and unites them 
 so as to constitute the actions of standing and locomotion. Such are 
 the discoveries of M. Flourens."* 
 
 III. Of the distinct functions of the anterior and posterior columns 
 of the spinal marrow. It is certain that the spinal marrow sends off 
 nerves engaged in the performance of two distinct functions, viz. that of 
 feeling and that of motion. From what part, we are led to ask, of 
 this organ do the nerves allotted to each of these functions proceed? 
 It is well known that the spinal marrow is formed of two substances 
 a white substance which is exterior, and a gray substance occupying 
 the interior of the chord. The continuity of the fibres composing the 
 
 * Experiments similar to those of M. Flourens were instituted in 1805, by Pro- 
 fessor Rolando, of Turin, from which he deduced inferences in some respects the 
 same as those at which M. Flourens has arrived. The experiments of the latter 
 physiologist were, however, more varied, were apparently more carefully performed, 
 and therefore were more conclusive, than those of his predecessor. They were re- 
 peated, moreover, before a commission of the Institute of France, composed of some 
 of the most eminent of that body, who approved of the conclusions which are given 
 above. The following are the inferences which M. Flourens considers that his ex. 
 periments justify : 
 
 " 1. No movement proceeds immediately from the will. The will is the exciting 
 and determining cause of certain movements ; but it is never the efficient or effective 
 cause of any. 
 
 " 2. It has been shewn that the immediate cause of muscular contraction parti- 
 cularly resides in the spinal marrow and nerves, and that the regulating cause of 
 these contractions is placed in the cerebellum. 
 
 " 3. There are, therefore, three phenomena essentially distinct in a movement 
 proceeding from volition: 1, the volition of movement, a volition which seems to 
 reside in the cerebral hemispheres ; 2, the appropriate regulation of the different 
 muscular contractions productive of motion, which resides in the cerebellum ; and 
 3, the excitation of these contractions, which has its efficient seat in the spinal mar- 
 row and its nerves. 
 
 " 4. As these three phenomena, essentially distinct, reside in three organs also 
 distinct, the possibility of abolishing any one of them, and leaving the others un- 
 injured, seems apparent ; thus the will may be destroyed, and the regulation of con- 
 traction, and contraction itself, will remain ; or both volition and the regulating 
 cause of contraction may be abolished, and contraction will alone be produced, &c. 
 
 " 5. There exists therefore in the nervous system (cerebro-spinal system), three 
 properties essentially different : one the exciter of motion ; another the regulator ; 
 and the third the wilier and perceiver. 
 
 " 6. The spinal marrow, the medulla oblongata, and the^tubercula quadrigemina, 
 alone possess the property of directly exciting muscular contraction : the cerebral 
 lobes and cerebellum do not possess it. 
 
 " 7- There are two ways of destroying vision without going beyond the cerebral 
 mass : one by the removal of the tubercula quadrigemina, producing loss of the 
 sense of sight ; the other by the removal of the cerebral lobes, causing the loss 
 of the sensation of sight.
 
 670 APPENDIX. 
 
 roots of the spinal nerves, with the gray substance of the chord, as esta- 
 blished by Keuffel and Ollivier, naturally leads us to suppose that it is 
 particularly concerned in the production of the functions of sensation 
 and voluntary motion. It may be also observed, that the fibres of the 
 anterior roots are much smaller than those of the posterior, a circum- 
 stance which, when viewed in connexion with what has been advanced 
 on the subject by Mr. Charles Bell* and M. Magendie, shews that each 
 set of fibres (posterior and anterior) is more immediately allotted to 
 the performance of a distinct function, that the posterior roots are 
 devoted to the sensibility of the psyts which these nerves supply, and 
 the anterior to the muscular contractions. But it appears, from the ex- 
 periments of M. Magendie, that one of these functions does not exclu- 
 sively belong to one order of these roots ; for when the posterior roots, 
 
 " 8. There is, therefore, in the cerebral mass, distinct organs for the senses, for 
 the sensations, for the movements. 
 
 " 9. Not only all the sensations, all the perceptions, all the volitions, all the 
 intellectual and sensitive faculties, reside exclusively in the cerebral lobes, but all 
 these faculties occupy jointly the same seat in these organs ; for if one of them 
 disappear, all disappear; and if one return, all return. The power of feeling, 
 willing, and perceiving, constitute therefore but one faculty, residing but in one 
 organ. 
 
 " 10. The cerebral lobes, the cerebellum, and the tubercula quadrigemina, may 
 lose a considerable but limited portion of their substance without losing the ex- 
 ercise of their functions ; and they may re-acquire them after being totally deprived 
 of them. 
 
 " 11. The spinal marrow and the medulla oblongata are the only parts which 
 directly affect the same side of the body with that in which they are themselves 
 affected. The tubercula quadrigemina, the cerebral lobes, and the cerebellum, alone 
 
 produce their effects upon the opposite side to that in which they are influenced : 
 
 the former act in a direct course, the latter in a cross direction." 
 
 * Mr. Bell's attention was attracted by " the difference in the distribution of 
 the nerves of the head from those of the body, and the fact that all the spinal 
 nerves arise by double roots. Observing that this form of origin was the same in 
 all animals possessing a spinal chord, and considering that the anterior column of the 
 spinal marrow was continuous with the crura of the cerebrum, and the posterior 
 with the crura of the cerebellum, he conceived that by experiments on the roots of 
 these nerves, he might discover the functions of the two columns, and perhaps 
 through them arrive at a more accurate knowledge of the relations and individual 
 uses of the cerebrum and cerebellum." Previously, however, to these experiments, 
 Mr. Bell entertained the opinion that the anterior column of the spinal chord was 
 different in function from the posterior, and that through the former the simple 
 voluntary power of moving particular parts was conveyed. He deduced this from 
 observing that the two nerves, which are generally supposed to be purely motors, 
 arise from the anterior fasciculus. The experiments which these opinions sug- 
 gested, although they were not conclusive, yet encouraged the view he had taken, 
 and gave results in some degree similar to those which Magendie subsequently 
 obtained from his experiments. To Mr. Bell, therefore, the honour of having 
 originated these views clearly belongs.
 
 OF THE FUNCTIONS OF THE SPINAL CHORD- 671 
 
 or those which more particularly belong to sensibility, are irritated, 
 contractions are occasioned in the muscles to which their nerves are 
 distributed, although the contractions are much more strong and much 
 more complete when the irritation is directly applied to the anterior 
 roots of the nerves. Slight appearances of sensibility are also occa- 
 sioned when irritation is made on the anterior roots. It must there- 
 fore be concluded, that sensibility, although chiefly, is not exclusively, 
 in the posterior roots, nor motion in the anterior. 
 
 This defect of complete isolation of these two functions may arise, as 
 M. Ollivier supposes, from the gray matter of each lateral half of the 
 marrow, which seems to be concerned in their production, being en- 
 tirely confounded at their central points of contact ; and from the 
 intimate union which takes place between both the roots, below the 
 spinal enlargements (intervertebral ganglions of the posterior roots), 
 and which must contribute still farther to combine these functions so as 
 to prevent their perfect separation. 
 
 It should be recollected that the functions of feeling and motion 
 ought not to be attributed to the roots of the nerves themselves. M. 
 Magendie found, that when these nerves were divided close to the 
 marrow, and irritation then made on their roots, no sensible effect fol- 
 lowed ; whereas, whilst their connexion with the marrow was preserved 
 the slightest irritation was productive of effect ; and the nearer that it 
 was made to the spinal chord, the more intense was the influence oc- 
 casioned by it. Hence it follows, that the gray substance of the chord, 
 whence arise the roots of the spinal nerves, is much more intimately 
 concerned in the production of the operations in question than the 
 roots of the nerves themselves; but this substance itself seems to depend 
 more upon the different parts composing the encephalic mass, for 
 whatever influence it may exert in the production of the phenomena 
 under consideration, than M. Ollivier appears to allow. He attri- 
 butes them both almost exclusively to the gray substance of the centre 
 of the chord, which he considers to be voluminous in proportion as 
 these faculties are developed. This part of the chord, although 
 altogether necessary to, and instrumental in, their production, can 
 only be viewed as one of three distinct classes of structure, but each of 
 which, as M. Flourens has stated, performs distinct actions, which by 
 their combination constitute an individual function, that could not 
 result from any one or two only of the actions composing it, but is the 
 consequence of a more or less perfect co-operation of the whole.* 
 
 * Of the distinct functions of the cerebellum numerous opinions have been \ 
 lately entertained. Dr. Gall considers it to be the seat of physical love. M. 
 Rolando, who adopts the opinion of a nervous fluid, which he regards as analogous 
 to the galvanic fluid, places the source and seat of the principle of muscular con- 
 traction in the cerebellum, which, owing to the disposition of its laminated con.
 
 672 . APPENDIX. 
 
 When we consider that the fibres of the dorsal roots of the spinal 
 nerves are larger than those of the abdominal ; that the abdominal 
 columns of the spinal chord are not altogether insensible when irritated ; 
 and that there is an intimate union between the spinal chord and the 
 ganglial nerves, by means of branches of communication running be- 
 tween them and the anterior roots of the spinal nerves, it is impossible 
 to believe that the dorsal roots are solely destined to sensation, and the 
 anterior roots to voluntary motion. To us it appears more accordant 
 with the phenomena which this part of the nervous system presents in 
 the various orders of animals, to conclude, that although these different 
 columns of the spinal chord are more especially concerned in the per- 
 formance of particular functions, yet that their functions are not strictly 
 limited to distinct portions of the chord ; and that the spinal chord is 
 not a mere conductor of sensation and voluntary motion, but that it 
 also aids in maintaining the vital energies of those parts to which its 
 nerves are distributed. 
 
 On this subject we find the opinions of Dr. Spurzheim* are agree- 
 able to our own. He conceives that the muscles or instruments of 
 motion acquire their power in part through the influence of their 
 nerves, whilst the will to make the muscles act resides in the brain. 
 
 The experiments instituted by Dr. Bellingeri,f and detailed in a 
 memoir repd before the Royal Academy of Sciences at Turin, in Fe- 
 bruary 1824, do not tend to throw any new light upon this interesting 
 subject. They confirm the idea of separate nerves of sensation and 
 motion in the spinal chord ; but they further accord motion to the 
 nerves that issue from the dorsal roots. His inferences are, 1st, 
 that the posterior roots of the lumbar and sacral nerves produce the 
 motions of extension in the lower extremities; 2d, that the posterior 
 roots alone preside over sensation ; 3d, that the anterior roots produce 
 the motions of flexion in the sacral extremities, and do not aid in 
 perceiving external impressions; 4th, that the posterior bundles of 
 the spinal chord preside over the motions of extension of the inferior 
 extremities, and have no connexion with perceptions o e touch ; 5th, 
 that the white substance of the spinal chord, and the nervous fibres 
 that arise from it, are appropriated to motion ; and 6th, that the gray 
 
 volutions, he considers to act in the manner of a voltaic pile, and to transmit, under 
 the direction of the brain, and through the channel of the spinal chord and nerves, 
 the moving principle to the muscles. M. Flourens, as we have shewn, views this 
 organ as the regulator and balancer of the muscular contractions. M. Magendie 
 regards it as requisite to the production of motion forwards : and Mr. C. Bell, 
 MM. Fod6ra, Foville, and Pinel-Grandchamp, are of opinion that it is the seat 
 of sensibility. 
 
 * The Anatomy of the Brain, with a General View of the Nervous System. 
 By G. Spurzheim, M.D., &c. Lond. 1826. 
 
 f Bulletin des Sciences Mtdicales, Juin 1825.
 
 OF THE RESPIRATORY NERVES. 673 
 
 substance of the chord, and the nervous fibres that spring from it, 
 belong to sensation. 
 
 In opposition to the last inferences here stated, namely, that the 
 spinal nerves may be divided into those which come from the white, 
 and those which proceed from the gray, substance of the chord, it may be 
 contended, that these nerves are universally implanted into the gray sub- 
 stance of the chord. Upon the whole, therefore, although we may grant 
 that the columns of the spinal chord seem concerned to a certain extent 
 in the performance of distinct functions, yet we conceive that these 
 functions have not yet been appropriated with sufficient precision to the 
 different parts of the chord and origins of its nerves, and that this 
 subject stands much in need of further investigation. 
 
 Whilst the above remarks were passing through the press, M. 
 Schoepf's experiments on the different parts of the cerebro-spinal ner- 
 vous system were made known to us. These experiments shew the 
 justice of our remarks, whilst they, upon the whole, confirm the 
 results of those performed by M. Rolando,* M. Flourens, and Dr. 
 Bellingeri: they are in opposition, however, to many of the inferences at 
 which Mr. Bell and M. Magendie have arrived. They shew, moreover, \ 
 that volition is entirely to be referred to the cerebral lobes ; that slight 
 irritation of themedulla oblongata produces convulsions, and afterwards 
 paralysis of the same side ; that more severe lesions of this part imme- 
 diately arrest the movements of the respiratory organs ; that the pos- 
 terior as well as the anterior columns of the spinal chord, and the an- 
 terior as well as the posterior roots of the spinal nerves, are concerned in 
 the function of voluntary motion ; and that the sense of touch or sen- / 
 sibility belongs neither to the one nor the other.f 
 
 IV. Of the respiratory order of nerves, fyc. All animals that 
 possess a perfect cerebro-spinal system have an intermediate order of 
 nerves which connect the vegetative functions of the ganglial system 
 with the functions of the encephalon. This order of nerves has lately 
 been very satisfactorily examined into, both as respects their dis- 
 tribution and functions, by Mr. Charles Bell. 
 
 On investigating the minute structure of the nerves which, both in 
 man and in the lower animals, arise from the spinal marrow by double 
 roots, and those which proceed from the medulla oblongata, by single 
 origins, to the organs of respiration, and those parts of the face and 
 trunk which evince an intimate relation with this important function, 
 Mr. Bell perceived that their texture and mode of distribution were 
 very different. This circumstance led him to consider that two 
 
 * Saggio sopra la vera Strutlura del Cervello, e sopra le Funzioni del Sistema 
 Nervoso. Edit. 2d. vol. ii. p. 298, et seq. 
 
 f Annali Universali di Medieina. Milano, Luglio 1828. 
 X X
 
 674 APPENDIX. 
 
 distinct orders of nerves must exist, independently of the sympathetic ; 
 the one simple and uniform, the other irregular and complex in 
 proportion to the complexity of the organisation. The former he has 
 called original or symmetrical, the latter superadded or irregular. In 
 the superadded class of nerves, which are chiefly devoted to the 
 function of respiration, Mr. Bell arranges, 1st, the par vagum; 2d, the 
 portio dura; 3d, the spinal accessory; 4th, the phrenic; 5th, the 
 external respi r atory nerves, &c. " The nerves," this physiologist 
 states, " on which the associated actions of respiration depend, and 
 which have been proved to belong to, this system, by direct experiment, 
 and the induction from anatomy, arise very nearly together. Their 
 origins are not in a bundle or fasciculus, but in a line or series, and 
 form a distinct column of the spinal marrow. Behind the corpus 
 olivare, and anterior to that process which descends from the cere- 
 bellum, the corpus restiforme, a convex slip of medullary matter, 
 may be observed ; and this convexity, or fasciculus, or virga, may be 
 traced down the spinal marrow, betwixt the sulci which give rise to 
 the anterior and posterior roots of the spinal nerves. This portion of 
 medullary matter is narrow above where the pons Varolii overhangs it. 
 It expands as it descends ; opposite to the lower part of the corpus 
 olivare it has reached its utmost convexity, after which it contracts a 
 little, and is continued down the lateral part of the spinal marrow." 
 
 From this track of medullary matter on the side of the medulla 
 oblongata, arise in succession from above downwards the portio dura, 
 the glosso-pharyngeus, the par vagum, the nervus accessorius, the 
 phrenic, and the external respiratory. These superadded nerves are 
 comparatively but little sensible ; they do not arise by double roots, as 
 the symmetrical do ; they have no ganglia on their origins ; and while 
 the other voluntary nerves have large, free, and round filaments, they 
 have a close, loose texture, resembling a minute plexus. " These are 
 the nerves which give the appearance of confusion to the dissection, 
 because they cross the others, and go to parts already plentifully 
 supplied from the symmetrical system." 
 
 From these anatomical investigations, and from experiments made 
 in order to ascertain the exact functions of this order of nerves, 
 Mr. C. Bell and Mr. Shaw have drawn some important inferences : 
 1st, They consider that the portio dura of the seventh pair " produces 
 all those motions of the nostrils, lips, or face generally, which accord 
 with the motions of the chest in respiration. When cut, the face is 
 deprived of its consent with the lungs, and all expression of emotion. 
 2d, The par vagum associates the larynx, the lungs, the heart, and the 
 stomach, with the muscular apparatus of respiration. 3d, The spinal 
 accessory controls and directs the operations of the muscles of the 
 neck and shoulder, in the offices of respiration. 4th, The phrenic
 
 OF THE FUNCTIONS OF DIFFERENT NERVES. 675 
 
 nerve has its functions sufficiently characterised in the name of internal 
 respiratory, which Mr. Bell has assigned it. 5.th, The glosso-pharyngeal 
 nerve, &c. ; and 6th, The external respiratory nerve, perform the 
 functions which those parts, to which they are distributed, have in 
 connexion with the operations of respiration." 
 
 Mr. Mayo* subsequently investigated the functions of these 
 nerves, and added much to our knowledge of them. He has shewn 
 that the portio dura of the seventh nerve, and the ganglionless portion 
 of the fifth, are simply voluntary nerves to parts which receive sen- 
 tient nerves from the larger or ganglion ic portion of the fifth, and that 
 this portion of the fifth is exclusively sentient. 
 
 Mr. Broughton has also demonstrated that the portio dura of the ~~- 
 seventh nerve, and the par vagum, are strictly nerves of motion ; and 
 he has further proved that they are entirely unconcerned in the function ^ 
 of sensation. f 
 
 It will be perceived, from some observations offered by us at 
 p. 577, that we consider that the ganglionic portion of the fifth 
 nerve is not only a sentient nerve, but that it also is engaged in 
 the functions of secretion, exerted by the parts which it supplies, 
 namely, the lachrymal secretion, the secretion of mucus in the nares, 
 and the secretions of the mouth. 
 
 As far as reliance may be placed upon a single experiment lately 
 performed by ourselves, we conceive that Mr. Broughton is perfectly 
 correct in considering the par vagum as a nerve of motion only ; and 
 that it is in no way concerned in endowing the parts to which it is 
 ramified with sensibility. We consider that the sensibility evinced by 
 those parts is bestowed upon them chiefly by the visceral-ganglial 
 nerves, which nerves are also concerned in the production of the 
 secretions of the mucous surfaces covering the organs whose motions 
 the par vagum actuates. As far as our own observation enables us to 
 form an opinion, we believe that the par vagum influences the process 
 of digestion chiefly by being concerned in the motions of the muscular 
 coats of the stomach, thereby changing the position of its contents in 
 respect of the villous surface, and propelling the digested portions 
 towards the pylorus. The secreting functions of the villous surface, we 
 believe chiefly to depend upon the ganglial nerves distributed to this 
 organ. We further consider, that the complete division of the par 
 vagum has impeded, or, to a certain extent, arrested, the process of 
 digestion, owing to the acting of the muscular coats of the stomach 
 having been thereby interrupted. 
 
 * See this author's very able work, entitled " Outlines of Human Physiology." 
 Second edition. London, 1820. Pp. 33436. 
 
 t Medical and Physical Journal for June 1823, p. 463.
 
 676 APPENDIX. 
 
 V. Principle observed in the origin of the cerebro-spinal nerves. 
 Mr. Mayo believes " that nerves of motion take their rise from the 
 same region or segment with those sentient nerves which transmit the 
 impressions by which their action is usually regulated. The correct- 
 ness of this remark, as it respects the spinal nerves, will not be dis- 
 puted. It is owing to this circumstance, that if in an animal just 
 killed, the spinal chord be divided in the neck and in the back, on 
 irritating the integument of either foot, that foot is' retracted as promptly 
 and to the same extent as if the spinal chord and medulla oblongata 
 were entire. ., 
 
 " We observe, that the smaller portion of the fifth rises from the 
 upper part of the medulla oblongata, close upon the greater portion ; 
 and we recollect, that the sense of pressure upon the teeth and gums, 
 and of muscular exertion attending it, depends upon the latter, the 
 muscular effort itself upon the former. 
 
 " We observe, that the large root of the fifth and the portio dura 
 rise together ; and we recollect that the delicate sense of touch upon 
 the eye and eyelids depends upon the first, and the action of the 
 orbicularis palpebrarum on the second ; that the sense of touch in the 
 nostrils depends upon the first, and the action of the muscles of the 
 nostrils upon the second; that feeling in the lips depends upon the 
 first, and the action of the muscles of the lips upon the second ; and, 
 finally, that the sensation of those muscles, which the second sets in 
 action, depends upon the first. 
 
 " We observe, that the portio dura rises near the portio mollis ; 
 and we recollect, that the motions of the ear depend upon the former, 
 and the sense of hearing upon the latter."* 
 
 These observations seem to us both correct and interesting; although 
 this principle will not apply to every nerve of the body, as the author 
 has candidly admitted. 
 
 VI. General remarks on the different parts composing the nervous 
 system. From what we have already advanced respecting the func- 
 tions of the ganglial system of nerves, and from what has also been 
 said respecting the other parts of the nervous system, it may be inferred 
 that the nerves present a modified state of conformation and distri- 
 bution, according to the functions which they perform. This view of 
 the subject is confirmed not only by an attentive examination of the 
 different nerves of the human body, but also by a comparative investi- 
 gation of this part of the animal economy throughout the different 
 classes of animals. In some of the lower orders, the organisation of 
 
 * Outlines of Human Physiology. By H. Mayo, F.R.S., &c. 2d Edit. Pp. 343, 
 344.
 
 . 
 
 OF THE DISTINCT FUNCTIONS OF NERVES. 677 
 
 the nervous system is intermediate between that of the visceral-ganglial 
 nerves and that of the spinal nerves ; and we accordingly find that 
 nerves proceeding from the same ganglion supply both their digestive 
 and locomotive organs. As we rise in the animal scale, nerves of an 
 appropriate or distinct organisation and mode of distribution supply 
 particular organs, and discharge specific functions. It was not until the 
 time of Winslow that this principle in the animal economy seems to 
 have been sufficiently recognised. He first distinguished between the 
 ganglial nerves and those of the cerebro-spinal system. This division 
 was afterwards adopted by Johnstone, Bichat, and some other anato- 
 mists. But a more attentive examination will shew, that the nervous 
 systems may be still further divided. The ganglial system of nerves 
 may, we conceive, be subdivided, 1st, into the ganglial nerves sup- 
 plying the viscera ; and 2dly, into the ganglial nerves of association, or 
 those which communicate between the first division, or visceral nerves, 
 and the cerebro-spinal nervous system. 
 
 This latter system may be subdivided into, 1st, the brain proper; 
 2d, the cerebellum ; 3d, the medulla oblongata and spinal chord ; 
 4th, the nerves of sensation; and 5th, the nerves of motion. 
 
 Although it seems evident, from the experiments of Mr. Bell, Mr. 
 Magendie, Mr. Mayo, Mr. Broughton, and Dr. Bellingeri, that the nerves 
 perform distinct functions, yet we conceive that those functions have 
 not been assigned with sufficient precision to their respective nerves. 
 Indeed, the imperfect state of our knowledge has not allowed this to be 
 done in a way at all accordant with well-ascertained phenomena. Many \ 
 of the nerves, also, seem to perform more functions than one: thus the 
 ophthalmic branch of the trigeminal nerve supplies the lachrymal gland, 
 and presides over its secreting functions; filaments proceeding from 
 the same branch supply the iris, are instrumental in its motions, and 
 seem to preserve the eye in a fit state for the performance of its delicate 
 functions : the nasal portion of the nerve seems to be concerned in both 
 the secretions and sensations of the organ ; and the third branch of the 
 same nerve appears to perform similar offices in respect of the organ of / 
 taste. We know that some of the ganglial nerves of the thorax and 
 abdomen are chiefly instrumental in the production of the insensible 
 motions of the contractile organs which these cavities contain, whilst 
 others of these nerves preside chiefly over the functions of the secreting 
 viscera. Yet these nerves, whether those engaged in endowing con- 
 tractile organs with the power of motion, or those presiding over the 
 functions of secretion and sanguification, &c. also possess the faculty of 
 conveying sensations, and are evidently possessed of variously modified 
 sensibilities. How far these latter properties depend upon the associating 
 ganglial nerves, or those which communicate between the cerebro-spinal
 
 678 APPENDIX. 
 
 system * and the visceral-ganglial system,f our researches have not 
 enabled us to determine: but, from the examinations we have already 
 made, we conceive that this associating order of nerves performs a very 
 important part in conveying to the visceral-ganglial system of nerves 
 the nervous energy of the spinal chord and medulla oblongata, in con- 
 necting the functions of the different nervous masses, and in transmitting 
 the peculiar sensations excited in any of the viscera of organic life to 
 the brain. 
 
 In the first edition of these Notes we stated fully our opinions as to 
 the functions which the ganglial syst.em of nerves performs in the animal 
 economy. These opinions were mistaken by one or two writers who 
 soon afterwards noticed them, and who confounded them with the 
 opinions which had been entertained respecting these nerves by previous 
 writers, especially with those of Bichat. His opinions respecting them 
 were, in many respects, the same as those espoused by Soemmering and 
 by Reil; and whoever has attentively read the " Anatomie Generate," 
 and the writings of the German anatomists, previous to perusing the 
 note on the functions of ganglial nerves, at p. 556, et seg., will per- 
 ceive in what we have differed from, or agreed with them ; and how 
 much farther our inferences have been carried than those at which 
 these great physiologists had arrived .{ 
 
 * The nervous system of sensation, volition, and of the mental manifestations. 
 
 f The nervous system of organic or vegetative life. 
 
 % We may remark, by the way, that Johiistone, Bichat; Soemmering, and Reil, 
 conceived that the ganglia of the great sympathetic interrupt the reciprocal influence 
 of the cerebro-spinal nervous system, and the viscera of the large cavities. Now, 
 this is evidently not the fact, because this nerve, through the means of its various 
 connexions, actually conveys sensations and impressions, made upon these viscera, 
 both in health and in disease, to the brain, as well as transmits the energies of the 
 brain and spinal chord of the perfect animals, to reinforce the appropriate functions 
 of the visceral-ganglial nerves. Besides, if we examine the organisation of those 
 nerves which are now proved to be chiefly engaged in the function of sensation, we 
 shall find that they all possess a soft texture, and have ganglial enlargements near 
 their origins ; so that ganglia do not interrupt the functions of sensation, although 
 they may modify the sensation, and are perhaps adapted to the conveyance of certain 
 impressions in preference to others ; and we may, moreover, add, that ganglia are 
 chiefly important in interrupting the transmission of volition, and of the impressions, 
 passions, and affections of the mind, to the viscera more immediately related with 
 life, and thus preventing the bad consequences which would result from the domi- 
 nion of the cerebro-spinal nervous system over the viscera of organic life. Indeed, 
 we perceive, that when a nerve presents a soft consistence, and is connected with a 
 ganglion, it is not a nerve of volition, or the medium through which the will 
 changes the condition or position of a part, although it may be a nerve of sensation, 
 and performing either this function alone, or that of secretion, or some other action 
 in addition.
 
 OF THE PHENOMENA OF MIND. 679 
 
 OF THE PHENOMENA OF MIND AS MANIFESTED THROUGH THE 
 INSTRUMENTALITY OF A PERFECT NERVOUS SYSTEM. 
 
 (Notes H H. See pp. 344357.) 
 
 The manifestations of mind have engaged the researches of some of 
 the most acute inquirers who have " interrogated nature" during the 
 last half century. Their progress, however, in this very interesting and 
 difficult field, has not been equal to the growing zeal with which it has 
 been cultivated. This want of success is, in our opinion, much less to 
 be imputed to the individuals who have engaged in the inquiry, than 
 to the obstacles which beset a subject that involves the mysterious union 
 of mind with matter, and which holds relations with both of the most 
 intimate nature, and under aspects of apparently the most contradictory 
 character. 
 
 The operations of a system possessing so extended a connexion 
 between the intellectual faculties on the one hand, and the corporeal 
 functions on the other, and reciprocally receiving and communicating 
 influence during health and disease, cannot be accurately traced, 
 even in the more evident phenomena, without a considerable degree of 
 patient observation and research. There, however, exist many subtle 
 relations, which require a still more laborious demonstration ; and 
 which, when admitted, are explained with greater difficulty and 
 doubt. These have always afforded materials for various and conflicting 
 hypotheses, which, while they have saved us from secure and happy 
 ignorance, have roused us to a more eager search after truth. Not- 
 withstanding the number of theories that have consequently abounded, 
 and the impulse they have given to human intellect, many humiliating 
 considerations must obtrude themselves, when we meditate upon the 
 conclusions to which some of them have led, and upon the slow pro- 
 gress that has been made towards advancing our knowledge respecting 
 the cerebral functions in relation both to the mental and corporeal ma- 
 nifestations. How little has been added to the strictly physiological de- 
 partment of this subject, to what may be found in the writings of Galen ! 
 and what has the science of mind gained, during so many centuries, 
 from the contending followers of Plato, Aristotle, and Epicurus, beyond 
 the dawn of reason which had already appeared in their discordant 
 theories ? 
 
 It certainly cannot be wondered at, that human intellect has wan- 
 dered upon an ocean of uncertainty respecting its own operations, and 
 those corporeal functions with which it holds so intimate a connexion, 
 when it is considered, that until the end of the last century but little 
 care was taken to collect and arrange a requisite number of facts, and 
 to direct the mind to a careful observation and analysis of the extent
 
 680 APPENDIX. 
 
 and nature of its faculties. Until our own times, how little anxiety 
 have the majority of philosophers shewn to ascertain the stability and 
 connexion of the data upon which they founded their doctrines ; and 
 which often led, from the neglect of that precaution, to conclusions 
 irreconcilable with common sense and the experience of our senses ! 
 
 The philosophy of Bacon, which, in this country at least, has ex- 
 tended its influence to the science of mind, promises to advance this 
 department of human knowledge ; and by teaching the necessity of 
 attending with more precision to the relations of our various mental 
 emotions, to the objects of our consciousness, and to the origin and 
 history of our ideas, whether those which are derived from our senses 
 or from reflection, to guide our speculations through an inductive chain 
 to conclusions more correct, and certainly more ennobling, as they 
 regard human nature, than many that have been adopted in modern 
 times. 
 
 The metaphysical system of Kant has tended in no small degree to 
 retard this advancement throughout a great part of the continent ; 
 and, although it is indebted to Cudworth for its better parts, it appears 
 to have given a wrong impulse to the science of mind ; and thus have 
 arisen the mystifications of Fichte and of Schelling, now so generally 
 adopted over Germany; and which, most- probably, will enjoy as short 
 a dominion as that of their predecessor. 
 
 It has been urged by all the favourers of Epicureanism, and by 
 many of the followers of Gassendi and Hobbes, but more especially 
 by Priestly, BufFon, Darwin, Maupertius, Blumenbach, Cabanis, Law- 
 rence, and by others of the modern French school of materialism, 
 that, as the manifestations of mind are never met with, unless con- 
 nected with a brain, or are suspended by compression of this organ, 
 so the phenomena generally attributed to it are the result of the 
 organisation of the nervous fabric. All these philosophers do not dis- 
 tinctly enunciate this proposition ; but the general tendency of their 
 doctrines leads to its adoption. That any combination of the mole- 
 cules of matter can produce the various powers of mind, is a paradox 
 which they generally evade, but cannot explain. If this principle 
 proceed from certain associations of organic particles, why is not some 
 probable opinion respecting this process given ? Does our experience 
 respecting the mutual influence of either the elements or the aggregate 
 of matter furnish us with resulting phenomena, that can in any degree 
 approach to the lowest manifestations of either vitality * or mind ? If 
 it be derived from the combination of these particles, or from the 
 operation of certain of their products upon each other, is it possible to 
 conceive that matter, in such a state, possesses qualities, of which the 
 
 * See NOTE A of this Appendix.
 
 OF THE MANIFESTATIONS OF MIND- 681 
 
 elements or even the individual atoms are divested ? If, on the other 
 hand, properties necessary to the generation of the mental faculties be 
 conceded to every particle entering into the formation of the ence- 
 phalon, how can the idea of the subdivision of the powers of mind, to 
 such an extent as matter, be admitted ? Can the supposition be for, a 
 moment entertained, that every molecule of this admirable organ has a 
 fractional part of mind connected with it ? * Many of the materialists, 
 in order to account for the operations of this principle, had recourse to 
 so many suppositions respecting the nature and endowments of matter, 
 either in respect of its elements or aggregate, as were tantamount to a 
 negative admission of the agency of life ; with this notable difference, 
 however, that they required the operation of more numerous agents, 
 instead of the more philosophical doctrine that referred them to states 
 of this first and noblest constituent of our nature. The genius of 
 Leibnitz saw the difficulty that stood in the way of pure materialism, 
 and in order to give his passive atoms activity, and origin to the mental 
 phenomena, he had recourse to the emAs#s<<, or spirits, of Aristotle. 
 
 * Since the above remarks were first published by us (in 1822), the doctrine of 
 materialism has been ably opposed by Dr.. Barclay, (An Inquiry into the Opinions, 
 Ancient and Modern, concerning Life and Organisation. By John Barclay, M.D. 
 &c. &c.) and by Dr. Thomas Brown, in his Lectures, which have been recently 
 printed. " In whatever manner, therefore," it has been argued by the latter able 
 metaphysician, " the materialist may profess to consider thought as material, it is 
 equally evident, that this system is irreconcilable with our very notion of thought. 
 In saying that it is material, he says nothing, unless he means that it has those 
 properties which we regard as essential to matter ; for, without this belief, he might 
 as well predicate of it any barbarous term that is absolutely unintelligible, or 
 rather might predicate of it such a barbarous term with more philosophic accuracy ; 
 since, in the one case, we should merely not know what was asserted in the 
 other case we should conceive erroneously that properties were affirmed of the 
 principle of thought, which were not intended to be affirmed of it. Matter is that 
 which resists compression, and is divisible. Mind is that which feels, remembers, 
 compares, desires. In saying of mind that it is matter, then, we must mean, if 
 we mean any thing, that the principle which thinks is hard and divisible ; and 
 that it will be not more absurd to talk of the twentieth part of an affirmation, or 
 the quarter of a hope, of the top of a remembrance, and the north and east 
 corners of a comparison, than of the twentieth part of a pound, or of the different 
 points of the compass, in reference to any part of the globe of which we may be 
 speaking. The true answer to the statement of the materialist, the answer which 
 we feel in our hearts, on the very expression of the plurality and divisibility of 
 feeling, is, that it assumes what, far from admitting, we cannot even under- 
 stand ; and that, with every effort of attention which we can give to our mental 
 analysis, we are as incapable of forming any conception of what is meant by a 
 quarter of a doubt, or the half of a belief, as forming to ourselves an image of a 
 circle without a central point, or of a square without a single angle." (See Lec- 
 tures on the Philosophy of the Human Mind. By the late Thomas Brown, M.D., 
 Professor of Moral Philosophy in the University of Edinburgh. 8vo. Edinburgh, 
 1828. pp. 646.)
 
 682 Al'PENDIX. 
 
 The French physiologists, with Cabanis at their head, adopted the 
 doctrine of organism ; and in order to supply the want of a founda- 
 tion to their structure, they seized with avidity upon the opinions of 
 Gassendi respecting the origin of our ideas. Their theory still re- 
 quired support ; and in order that it might receive such from a name 
 looked to with deference throughout Europe, they unjustly imputed 
 to Locke doctrines which were derived from the two celebrated oppo- 
 nents of Descartes already mentioned. Much of the credit which this 
 system acquired in France and in the north of Germany, arose also 
 from the neglect with which that class of our ideas derived from re- 
 flection was uniformly treated. The writings of Locke, Cudworth, 
 Price, and others, directed attention to this highest principle of our 
 nature, and, in part, gave origin to the system of Kant ; which, like the 
 physiology of Gall and Spurzheim, promulgated so soon after the philo- 
 sophy of their countryman, was indebted to some acknowledged truths, 
 mixed up with many assumptions, for the partial credit which it has 
 obtained. Indeed, the doctrines of these systematists are more closely 
 allied than has been generally supposed ; and it is not unlikely that 
 the opinions of Gall were, in a great measure, derived from the Cri- 
 tique of Pure Reason. How far these systems, especially that of Gall, 
 may lead to Spinozism, we cannot here inquire. We would recom- 
 mend the writings of Cudworth, Price, Reid, Stewart, Barclay, and 
 Brown, especially those of the three last-named authors, to those who 
 are inclined to satisfy themselves more fully as to the arguments which 
 may be adduced in proof of the independent existence of mind, and 
 who wish to guard against the seductions to Phyrronism contained 
 in the writings of Montaigne, Berkeley, and Hume. 
 
 Our remarks on this very extensive subject, were we to pursue 
 it further, could only be cursory, and therefore would necessarily 
 appear to many both desultory and unsatisfactory. We shall merely, 
 therefore, offer a classification of the manifestations of mind, com- 
 mencing with the lowest, or those most extensively disseminated 
 throughout the animal kingdom, and proceeding to the highest or 
 most perfect faculties. 
 
 CLASS I. INSTINCTIVE FEELINGS AND EMOTIONS. (Strong and 
 immediate Incentives to Action.) 
 
 ORDER I. Instinctive Feelings which tend to preserve 
 the Individual. 
 
 1. The Sensations. 2. Volitions or Desires. 3. 
 The Appetite for Food and Drink. 4. The 
 Desire of preserving the Animal Warmth. 
 5. The Desire of Repose. 6. Desire of
 
 CLASSIFICATION OF THE STATES OF MIND- 6S3 
 
 Place. 7. Desire of continued Exist- 
 ence. 8. Desire of Pleasure, and Dread 
 of Pain. 
 
 ORDER II. Instinctive Feelings which tend to perpetuate 
 
 the Species. 
 
 1. The Appetite for Procreation. 2. Pa- 
 rental and filial Affection. 3. Desire 
 of Society. 4. Social Affection, giving 
 rise to mutual support. 
 
 ORDER III. Instinctive Emotions of Mind, tending to 
 promote the chief Objects of our Ex- 
 istence ; (and, with the former orders of 
 this class, entering more or less as in- 
 gredients into all the Intellectual and 
 moral Manifestations of Mind.) 
 1. Gratitude. 2. Anger. 3. Pride, Hu- 
 mility. 4. Gladness, Regret, Sadness. 
 5. Wonder, Desire of Novelty, Mental 
 Languor. 6. Beauty and Deformity. 
 7. Sublimity and Ludicrousness. 8. 
 Sympathy. 9. Love and Hate. 10. 
 Love of Approbation. 11. Desire of 
 Knowledge. 12. Desire of Power. 
 
 CLASS II. INTELLECTUAL POWERS, OR STATES OF MIND. 
 
 ORDER I. Powers of Consciousness, or the simpler In- 
 tellectual States of Mind. 
 1. Perception. 2. Attention. 3. Conception. 
 4. Memory. 
 
 ORDER II. Powers of Intellection, or the more Active 
 
 Intellectual States of Mind. 
 1. Association of Ideas. 2. Abstraction. 
 
 3. Imagination. 4. Judgment or Rea- 
 soning. 
 
 ORDER III. Ideas of Reflection, springing from the Ex- 
 ercise of the former Orders of Powers. 
 (Rational incentives to action.) 
 1. Mental Identity. 2. Time. 3. Power. 
 
 4. Truth, Causation. 5. Right and 
 Wrong. 6. Existence of a Deity. 7. 
 Immortality of the Soul.
 
 684 APPENDIX. 
 
 GLASS III. 1 MORAL AFFECTIONS OF MIND. (In which our In- 
 stinctive Feelings and Emotions, as well as 
 our Intellectual Powers, are frequently more 
 or less engaged, and which are deliberate, 
 rational, and often strong incentives to 
 action.) 
 
 1. Duty, Rectitude, Virtue, Merit and De- 
 merit, with all our moral Obligations, 
 Emotions, and Desires, in our various 
 relations to society. &c. 2. Religious 
 Obligations, &c. 3. Duties we owe our- 
 selves, and which tend to promote our 
 Intellectual and Moral Excellence and 
 Happiness, &c. -*. 
 
 It will be perceived that the third order of ideas, into which we 
 have here arranged the intellectual powers, are chiefly derived from 
 reflection, or from the mind itself.* 
 
 The above arrangement exhibits merely a general outline of the phe- 
 nomena of the human mind. It does not contain every collateral or 
 subordinate affection, particularly several of those which belong to 
 the first and third classes, into which we have divided the mental 
 manifestations. It may be remarked generally, that sensation, and 
 volition or desire, are the most widely diffused throughout the animal 
 kingdom, of all the states of mind ; and that although we have 
 assigned perception, attention, memory, and conception, more es- 
 pecially to consciousness, we consider that this state of mind is not 
 distinct in itself, but the concomitant of these and all the other 
 manifestations of the human mind. Perception is a sensation of which 
 we are presently conscious. Memory is the suggestion of sensations 
 of which we were formerly conscious, and of whose present suggestion 
 we are now conscious. Conscientiousness is the attendant on both 
 attention and conception, in a similar manner as in respect of the 
 other two mental states; for attention is continued or repeated per- 
 ceptions, and conception is only a more definite act of memory, 
 proceeding from the influence of volition or desire upon our present or 
 our former sensations. Consciousness, although thus intimately re- 
 lated to these particular states of mind, is also the concomitant of all 
 our present mental emotions and manifestations: it is the present 
 state of mental existence, whatever that state may be ; it indicates the 
 
 * See on this subject the writings of Dugald Stewart ; the published Lectures 
 of Dr. Brown ; Dr. Barclay on Life and Organisation ; Dr. Prichard on the Ner- 
 vous System ; and the London Medical Repository, vols. xvii. and xviii.
 
 OF THE STATES OF MIND. 685 
 
 mind's unity and the mind's identity : hence it has attended on all 
 our mental feelings, actions, and passions ; does attend them ; and will 
 attend those which shall take place at a future period. 
 
 Of the instinctive principles of mind, which we have made the first, 
 because the most generally diffused, class, and especially of the first 
 and second orders placed under it, we shall merely remark, that they 
 guide the operations of animals in a uniform manner; that similar 
 instinctive actions and feelings manifest themselves uniformly in all 
 the individuals belonging to the same species ; that they lead to 
 determinate ends with unerring certainty, prior to all experience ; and 
 that they are far superior, as incentives to action, to all the ma- 
 nifestations of reason of which the lower animals are possessed. 
 Even in man, the instinctive feelings when indulged in, and strength- 
 ened by habit, become too powerful for our reason ; and although man 
 is characterised by his reason being superior to his instinctive emotions, 
 yet the latter not infrequently obtain the ascendancy, when their 
 dictates are blindly followed, and when the intellectual and moral 
 principles of our minds have not been duly cultivated. The instincts 
 of the lower animals are scarcely ever controlled by the manifestations 
 of reason which they evince ; although a few exceptions to this 
 occasionally appear in respect of a few animals which have been 
 domesticated with man. 
 
 Our limits will not permit us to controvert the opinions of Locke, 
 Berkeley, Hume, and Condillac, who denied the existence of any 
 instinctive feelings in the human mind; but it is evident, from a 
 careful analysis of the different phenomena of mind, that, in addition 
 to the instinctive feelings we possess in common with the lower 
 animals, we are originally endowed with various mental emotions of a 
 higher nature than those which they manifest, and which, inde- 
 pendently of the ideas we acquire by means of reflection, #nd the 
 numerous class of our moral emotions, desires, and duties, evince that 
 we possess a somewhat differently constituted, as well as a more 
 advanced state of mind. Of this kind are those instinctive emotions 
 which we have arranged in the third order of the first class of the 
 above classification of the mental powers, as well as the whole of our 
 moral affections.* 
 
 * We subjoin the following analysis of the physiology of mind, according to the 
 very able and original views of Dr. Thomas Brown, whose early death must be a 
 matter of regret to all lovers of metaphysical inquiries and of the belles lettres. 
 
 CLASS I. EXTERNAL AFFECTIONS OF MIND; arising from the presence of 
 
 objects external to the mind itself. 
 ORDER!. Simple External Affections of Mind. 
 
 The Sensations derived by the Organs of Smell, Taste, 
 Hearing, Seeing, Touch, Muscular Action, Plea, 
 sure, Pain, &c.
 
 686 APPENDIX. 
 
 The doctrines of Gall. The anatomy of the nervous system has 
 been greatly indebted to this very indefatigable and eminent inquirer ; 
 and to whatever credit his doctrines may be found entitled, it cannot be 
 
 ORDER II. Complex External Affections of Mind. 
 
 Sensation accompanied by simple Suggestion, is Per- 
 ception. Perception with Desire, is Attention. 
 
 CLASS II. INTERVAL AFFECTIONS or MIND; proceeding from previous 
 Change in the States of the Mind itself, in consequence of the 
 Laws of Thought and Feeling. 
 
 ORDER I. INTELLECTUAL STATES OF MIND. 
 
 GENUS I. Simple Suggestion. (Association.) 
 
 Primary Laws of. 1. Resemblance. 2. 
 Contrast. 3. Nearness in Place or 
 Time. 
 
 Secondary or Modinying Laws of. 1. 
 Duration of the original Sensation. 
 
 2. The Liveliness of the Sensation. 
 
 3. The Repetition or Renewal of the 
 Sensation. 4. The Recentness or 
 
 I Remoteness of the Feeling. 5. The 
 
 Feeling having co-existed but little 
 with other Feelings, or only with one 
 or two Feelings. 6. They vary ac- 
 cording to original Constitutional 
 Differences. 7- According to Differ- 
 ences of Temporary Emotion. 8. Ac- 
 cording to Changes produced in the 
 State of the Body. 9. According to 
 general Tendencies produced by prior 
 Habits. 
 
 Forms of Simple Suggestion. 
 
 A. Conception, merely a more special 
 
 Suggestion. 
 
 B. Memory is merely Suggestion com- 
 
 bined with the Feeling of a Relation 
 of Priority to our present Con- 
 sciousness. 
 
 a. Memory combined with Desire is 
 Recollection. 
 
 C. Imagination. 
 
 a. A Mode of simple Suggestion, or a 
 
 momentary grouping of Images, 
 independently of Choice or Desire. 
 
 b. Groups of simple Suggestion in 
 union with Desire, or Conception' 
 following Conception at Desire. 
 
 D. Habit, or the frequent Repetition of 
 
 any Action or Train of Suggestions. 
 a. As producing a greater Tendency to 
 Actions or Trains of Suggestion..
 
 OF THE STATES OF MIXD. 687 
 
 denied that the science of mind has already been somewhat benefited, 
 although indirectly, by the opinions he has promulgated, and which 
 have at least been ingeniously supported by his followers. As to the 
 
 b. As occasioning greater Facility and 
 Excellence in those particular Ac- 
 tions. 
 GENUS II. Relative Suggestion. 
 
 SPECIES I. Co-existent Relative Sugges- 
 tion, or Relations of Co-existence. A. 
 In respect of Position. B. In respect 
 of Resemblance or Difference. C. 
 Of Degree. D. Of Proportion. E. 
 Of Comprehensiveness, or the Re- 
 lation of a Whole to its separate 
 Parts. 
 
 SPECIES II. Successive Relative Sugges- 
 tions, or Relations of Succession, or 
 Relations involving the Notion of 
 Priority and Subsequence. A. 
 Casual Relations of Succession. B. 
 Invariable Antecedence or Conse- 
 quence. 
 Forms of Relative Suggestion. 
 
 A. Judgment. 
 
 B. Reasoning. 
 
 C. Abstraction. 
 ORDER II. EMOTIONS OF MIND. 
 
 When excited by External Objects, are excited only 
 indirectly and through the Medium of Sensation. 
 They differ from the Intellectual State of Mind by 
 the peculiar Vividness of Feeling accompanying 
 them. 
 GENUS I. Immediate Emotions. 
 
 SPECIES I. Immediate Emotions involving 
 no Moral Affection. A. Cheerful- 
 ness, Melancholy. B. Wonder, 
 Novelty, &c. ; Languor, from the 
 same Succession of unvaried Feelings. 
 C. Beauty, and its reverse. D. 
 Sublimity and its opposite, Lu- 
 dicrousness. 
 
 SPECIES II. Immediate Emotions, in which 
 Moral Feeling is necessarily involved. 
 A. Feelings distinctive of Vice and 
 Virtue. B. Emotions of Love and 
 Hate. C. Sympathy with the Hap- 
 piness and Sorrow of others. D. 
 Pride and Humility. 
 GENUS II. Retrospective Emotions. 
 
 SPECIES I. As they relate to Others. A. 
 Anger, Gratitude.
 
 688 APPENDIX. 
 
 doctrines themselves, we will not give any opinion : if we were inclined 
 to do so, what we could offer respecting them would not be favourable 
 to them in all their details, although we might admit that some of their 
 fundamental principles seem based on truth. The favourers of crani- 
 ology appeal to facts, assert that it is eminently a science of observation 
 and rational induction, and call upon those who oppose it to make 
 themselves acquainted with its principles and details, and then observe 
 and judge for themselves. This seems candid and rational; but, un- 
 fortunately, when their advice is followed, and facts are observed which 
 militate against their theory, they endeavour to rid themselves of the 
 difficulty by asserting that the observer is mistaken, and unacquainted 
 with its principles, thus virtually denying that any one can be ac- 
 quainted with their doctrines unless he be likewise a convert to a belief 
 in them. When, however, pressed by facts which seem irresistible, 
 they have so many ways of eluding the difficulty between their ideas 
 respecting the activity and volume of the particular organ in question, 
 or the developement and activity of controlling, of opposing, and of 
 co-operating organs, that there is an end of all argument. The nu- 
 merous treatises which have appeared upon this subject render it un- 
 necessary for us to enter more particularly into details respecting it. 
 We should, however, be guilty of a neglect of duty were we to refrain 
 from recommending to the perusal of the candid and inquisitive reader 
 the last and greatest work of the celebrated originator of the doctrine 
 in question.* We have seldom been more interested than we were by 
 
 SPECIES II. Having direct reference to 
 ourselves. 
 
 A. Simple Regret and Gladness, 
 
 arising from Events we cannot con- 
 
 trol. B. Moral Regret and Glad- 
 
 ness, arising from our own Actions. 
 
 GENUS III. Prospective Emotions; comprehending 
 
 all our Desires and Fears. Wish, Hope, 
 
 Expectation, Confidence, are different Forms 
 
 of Desire. 
 
 SPECIES I. Desire of continued Existence. 
 2. Desire of Pleasure. 3. Desire of 
 Society. 4. Desire of Knowledge. 
 5. Desire of Power. A. Direct 
 Power, as Ambition. B. Indirect 
 Power, as Avarice. 7- Desire of the 
 Affection of those around us. 8. 
 Desire of Glory. 9. Desire of the 
 Happiness of Others. 10. Desire of 
 the Unhappiness of those we hate. 
 
 * Sur les Fonctions du Cerveau. Par F. J. Gall. torn. 4, 8vo. Paris, 1825.
 
 THE DOCTRINES OF GALL. DREAMING. 689 
 
 the perusal of this work, although it failed of converting us to a belief 
 of the doctrines which it inculcated. 
 
 In order to give the reader an idea of the opinions of this able 
 author in as succinct a manner as possible, we need only quote the 
 following condensed translation contained in the learned notes of 
 Dr. Elliotson, one of the most learned and indefatigable supporters 
 of craniology in this country. 
 
 " The exact situation of the organs can be learnt from drawings or 
 marked heads only. I shall, therefore, confine myself to remarking :- 
 1st, That the organs of the faculties or qualities common to man and 
 brutes are placed in parts of the brain common to man and brutes, 
 at the inferior-posterior, the posterior-inferior, and inferior-anterior 
 parts of the brain ; v. c. of the instinct of propagation, the love of 
 offspring, the instinct of self-defence, of appropriating, of stratagem, &c. 
 2dly, Those which belong to man exclusively, and form the barrier 
 between man and brutes, are placed in parts of the brain not possessed 
 by brutes, viz. the anterior-superior and superior of the front ; v. c. of 
 comparative sagacity, causuality, wit, poetic talent, and the disposition 
 to religious feelings. 3dly, The more indispensable a quality or faculty, 
 the nearer are its organs placed to the base of the brain or median 
 line. The first and most indispensable, the instinct of propagation, 
 lies nearest the base ; that of love of offspring follows. The organ of 
 the sense of localities is more indispensable than that of the sense of 
 tones or numbers ; accordingly, the former is situated nearer the median 
 line than the two latter. 4thly, The organs of the fundamental quali- 
 ties and faculties which mutually assist each other, are placed near to 
 each other; v. c. the love of propagation and of offspring, of self-defence 
 and the instinct to destroy life, of tones and of numbers. 5thly, The 
 organs of analogous fundamental qualities and faculties are equally 
 placed near each other ; v. c. the organs of the relations of places, 
 colours, tones, and numbers, are placed in the same line, as well as the 
 organs of the superior faculties, and the organs of the inferior pro- 
 pensities."* 
 
 Of Dreaming. Mr. A. Carmichael has lately adopted and illus- 
 trated the theory of dreaming proposed by Dr. Spurzheim, that dreams 
 are caused by certain isolated portions or organs of the brain continuing 
 awake, while the remainder of it is in a temporary paralysis from sleep. 
 " According to this view, the particular dream will be fashioned by the 
 part or parts which are not under the dominion of sleep ; and the irra- 
 tionality of our sleeping thoughts is accounted for by one or more parts 
 
 * Gall sur les Fonctions du Cerveau, torn. iii. p. 208 et seq. : and Dr. Elliotson's 
 Notes to his Translation of Blumenbach's Physiology, p. 209.
 
 690 APPENDIX. 
 
 or organs thus acting without co-operation or correction from the other 
 parts of the encephalon." 
 
 Mr. C. enumerates no fewer than seven different states of sleeping and 
 waking : When the entire brain and nervous system are buried in 
 sleep, then there is a total exemption from dreaming. 2. When some 
 of the mental organs are awake and all the senses are asleep, then 
 dreams occur, and seem to be realities. 3. When the above condition 
 exists, and the nerves of voluntary motion are also in a state of wake- 
 fulness, then may occur the rare phenomenon of somnambulism. 
 
 4. When one of the senses is awake, .with some of the mental organs, 
 then we may be conscious, during our dream, of its illusory nature. 
 
 5. When some of the mental organs are asleep, and two or more 
 senses awake, then we can attend to external impressions, and notice 
 the gradual departure v of our slumbers. 6. When we are totally 
 awa#,~nd in full poss^teipn of our faculties and powers. 7. When, 
 under these' circumstance^ .Vie are so occupied with mental operations 
 as not to attend to the impressions of external objects; and then our 
 
 , ' jcevery deludes us4ike a 
 
 OF THE FORMATION ^W DEVELOPEMENT OF THE MUSCULAR 
 STRUCTURE, AJJJD OF THE SOURCE OF IRRITABILITY. 
 
 /'"*. 
 Xt>96*l 1 1. See pp. 370375, 385.) 
 
 In the"y lowest orders of animals, a muscular structure does not 
 exist 4n a distinct state. Their partial movements are performed by 
 means of the cellular tissue of which they are composed. In the lowest 
 of the series possessing a muscular texture, it moves only the integu- 
 ments to which it is attached, and of which it even forms a part. In 
 all animals possessed of a heart the muscular tissue constitutes an im- 
 portant part. In all the vertebrated animals a small number only of 
 the muscles are attached to the mucous surfaces, to the skin and its 
 appendages; whilst the greatest proportion is connected with the 
 skeleton, for the purposes of progression. 
 
 According to the researches of Dr. Isenflamm, of Dorpat, into the 
 progressive developement of the muscular structure in the human foetus, 
 this tissue is formed from the mucous and gelatinous fluid of which 
 the embryo is at first composed. 
 
 From this mucous fluid the involuntary muscles are first developed, 
 and afterwards the voluntary. During the first three months the vo- 
 luntary muscles present the appearance of viscous layers, with a slight 
 yellowish tint. At the end of the third month the tendons make their
 
 OF THE SOURCE OF IRRITABILITY. 691 
 
 appearance. During the fourth and fifth months the muscles become 
 redder, more fibrous, and more easily to be distinguished from their 
 tendons. In the sixth month, although very soft, they are still more 
 perfect. At the full term of utero-gestation the muscles are formed, 
 but they are pale, yet vascular; they are soft, and their bulk much 
 greater in proportion to the tendinous and aponeurotic substances than 
 in the adult. 
 
 As age advances, the voluntary muscles become redder and more 
 fully developed ; and towards the decline of life, more rigid, less capable 
 of quick and extensive contraction, and comparatively of less bulk than 
 their aponeurotic and tendinous connexions. 
 
 The microscopic observations of Mr. Bauer, Sir .Everard Home, 
 MM. Prevost, Dumas, and Beclard, seem to prove that the ultimate 
 muscular fibre is composed of corpuscles (arranged like a string of 
 beads) in every respect similar to those in the centre of the red glo- 
 bules of the blood. However, to obtain a correct idea of the ultimate 
 conformation of the muscular fibre, researches ought to be made with 
 this view on the raw and unprepared muscle ; for the action of heat, of 
 alcohol, and acids, evidently produces changes in the fibre, and coagu- 
 lates the albumen which enters into its composition. 
 
 The voluntary nerves dip into the texture of the voluntary muscles 
 at different points, and divide into numerous minute fibriles, which 
 abruptly escape demonstration. This sudden manner of disappearing 
 is owing to the extreme fibriles having become soft and diaphanous, 
 and deprived of their proper envelopes, so that their medullary substance 
 is diffused, as it were, into the mucous tissue, connecting the muscular 
 fibres. 
 
 The cerebro-spinal nerves, although they are numerous and large 
 in the voluntary muscles, disappear in the manner just pointed out, 
 long before their divisions become sufficiently numerous to be dis- 
 tributed to each muscular fibre. This being the case, how can the 
 action of these nerves oh all the fibres be explained? They cannot be 
 the direct cause of the muscular contraction, but must act in pro- 
 ducing it through the medium of another and a more general confor- 
 mation. What this formation appears to us to be, we will now en- 
 deavour briefly to shew. 
 
 It has been stated that all the involuntary muscles are supplied 
 with the ganglial or soft nerves only ; that they surround the arteries 
 throughout their ramifications, and consequently are thus present in 
 the voluntary muscles and in all vascular parts ; that the voluntary 
 nerves themselves, whether we trace the process of their formation in 
 the human embryo, or observe them in the lower orders of animals, 
 seem to originate from the ganglial, the cerebro-spinal masses being the
 
 692 APPENDIX. 
 
 perfection of the nervous conformation, and the last part of it which 
 becomes completely developed ; and that the cerebro-spinal nerves are 
 destined to the performance of functions distinct from those to which 
 the other and more generally diffused class is allotted. As irritability 
 is present in parts which do not receive voluntary nerves, and in 
 animals which do not possess this part of the nervous system, this pro- 
 perty cannot be attributed to it. To what other species of organisation 
 can we refer this property ? We find it, in the more perfect animals, 
 chiefly displayed by the muscular structure. Is it from this circum- 
 stance an attribute of muscular parts, -and the pure result of their con- 
 formation ? One class of physiologists answer this question in the 
 affirmative. But irritability is displayed by the lowest orders of the 
 animal creation, wherein a muscular structure cannot be detected, 
 even in the parts themselves which furnish the phenomenon; therefore, 
 although a property of the muscular fibre, it is neither altogether re- 
 stricted to it, nor is it strictly the result of the organisation of the fibre 
 itself. We must, consequently, refer this property to a conformation 
 still more general than the muscular tissue, both as respects the whole 
 scale of the animal creation and the organisation of individual species ; 
 allowing, at the same time, that a particular structure is requisite to the 
 full and perfect developement of this property, but that this structure 
 depends upon a different source than itself for t^e property which it 
 displays.* t 
 
 Having arrived at the conclusion, that irritability, although a pro- 
 perty of muscular parts, is not the result of muscular organisation, but 
 is derived from a different and more general system, supplying the 
 muscular structure as well as other structures, we must next inquire 
 what this system is. It has been already inferred, from various con- 
 siderations, that the ganglial class of nerves is distributed in different 
 proportions to the various textures and organs of the body ; that these 
 nerves are similarly distributed throughout all the individuals composing 
 the animal kingdom ; that in some of its orders they constitute the only 
 nervous system which the animal possesses : it has also been demon- 
 strated that this class of nerves, in a more or less perfect state of 
 
 * We have perceived, as the above sheet was passing through the press, that the 
 identical opinions which have been insisted upon by us, both in the former edition 
 of these Notes, and in several numbers of the Medical Repository for 1822, re- 
 specting the functions of the ganglial nerves, have been recently espoused by M. 
 Adelon in his System of Physiology. Our opinions on these subjects will be found 
 stated succinctly in the copious notes contained at pp. 556565 and p. 630 of the 
 present impression, and without the smallest addition to, or alteration from, what 
 is to be found in the first edition of this Appendix, which was published in the begin- 
 ning of 1824. For M. Addon's observations on these subjects, we refer to his Phy- 
 siologic de rifomme, tome iv. (the first edition of which volume appeared at the 
 commencement of 1825,) seconde edition, p. \46,etseq. Paris, 1829.
 
 OF THE SOURCE OF IRRITABILITY. 693 
 
 organisation, is present wherever irritability is manifested ; that these 
 nerves are the most generally diffused of any of the animal tissues ; 
 that no other structure exists but this which can be shewn tj> be 
 present in every species of irritable parts, in all orders of animals; and, 
 consequently, that to no other source but this can the property of 
 irritability be assigned. 
 
 Having inferred that the muscular fibre is only the instrument of 
 contraction in its more perfect condition, that it performs this function 
 in consequence of a certain conformation, and owing to that confor- 
 mation being endowed by means of another still more generally diffused 
 than itself, and that this property is derived from the ganglial or soft 
 nerves, which proceed, either directly or as an envelope to the arteries, 
 to all the tissues of the body, we are led farther to infer that the 
 cerebro-spinal nerves are distributed to muscular parts for specific pur- 
 poses, but that these parts do not derive their innate properties from 
 these latter nerves these nerves merely excite them, or rather are con- 
 ductors of a stimulus acting on properties which proceed from a dif- 
 ferent source. We have contended that these properties are not innate, 
 or the consequence of the conformation of the muscular fibre itself; 
 but are derived from a conformation still more general, which surrounds 
 or is otherwise connected with the muscular fibriles, and that this more 
 general conformation is the ramifications of the ganglial class of nerves. 
 Conceiving, therefore, that these nerves in their state of ultimate dis- 
 tribution and dissemination in the texture of the muscle, whether in the 
 form of unarranged globules, or of minute and variously arranged 
 fibriles resulting from the regular distribution of these globules, are 
 the chief source of the property evinced by muscular parts of every 
 denomination, we further conclude that the voluntary or cerebro-spinal 
 nerves do not produce their specific effects on the muscular fibres, 
 owing to a nervous fibrile being ramified to each muscular fibrile, for 
 this does not take place ; nor do these effects proceed from the direct 
 influence of these nerves upon the muscular fibrile, for the muscular 
 fibre derives its property or faculty of contraction from a source 
 different from itself and from the voluntary nerves which occasionally 
 excite its contractions; but that these nerves seem to act directly 
 upon the ultimate distribution of the ganglial nerves of the muscle, 
 which latter nerves bestow on it the faculty of, or the disposition to, 
 active contraction, on the application of a stimulus, which faculty all 
 muscular parts possess, the former class of nerves conveying to some 
 of these parts only the natural stimulus which induces contraction, or 
 which excites the active exertion of this faculty bestowed on these 
 parts from a different source, namely, from the ganglial system. The 
 mode of termination which the voluntary nerves observe in muscular 
 parts, also favours the opinion which we have now given. These
 
 694 APPENDIX. 
 
 nerves terminate, as we have already noticed, in such a manner as leads 
 us to infer, that they become, in the textures which they supply, 
 gradually identified, as it were, or amalgamated, with the ultimate dis- 
 tributions of the ganglial nerves : and the history of the embryo, and 
 the progressive developement of the nervous system in the lower 
 animals, dispose us to believe that the voluntary nerves originate in the 
 textures which they supply ; that they proceed from the ganglial system ; 
 and that their larger branches, the spinal marrow, and encephalon, 
 are successively formed.* 
 
 OF GALVANIC ELECTRICITY. 
 (NOTE K K. See pp. 391393.) 
 
 The phenomena of electricity have been long known to philosophers; 
 but science has been chiefly indebted, in our own times, to the re- 
 searches of Davy, Woollaston, Biot, Coulomb, JPoisson, Oersted, and 
 Becquerel, for a knowledge of the laws by which it is characterised. 
 The observations and experiments of these successful inquirers appear 
 fully to warrant the conclusion, that this very active agent of nature re- 
 sults from two distinct fluids universally diffused through every species 
 of matter. During their circulation, in their electro-motive capacity, 
 through the corpuscles of matter forming the crust of this planet, they 
 accumulate in their free and uncombined state upon its external surface, 
 in consequence of the imperfectly conducting property of the envelop- 
 ing atmosphere. 
 
 The electricities "are thus confined on the superficies of the globe, 
 and indeed of all bodies placed on its exterior, not merely by the non- 
 conducting faculty of the air, but also by a species of mechanical pres- 
 sure which the air exercises." Hence arise the electrical phenomena 
 which so frequently become the objects of observation. 
 
 .In elevated situations, in experiments where the density of the air is 
 exhausted and the aerial particles rendered fewer in number, and in 
 other favourable circumstances of the atmosphere, as in its humid state, 
 the electric power emanates with rapidity from the electrised ball. 
 
 Such is the mode of existence of this fluid upon the surface of the 
 earth. But there also exists a continual condensation of the electrical 
 agencies in the substance of the different matters composing the crust of 
 this planet ; and the galvanic, chemical, and other phenomena, clearly 
 shew that although such condensation of the electricities takes place 
 under particular circumstances of matter, yet a continuous circulation 
 of it is also evident under other relations. This, indeed, is observed to 
 occur during every manifestation of the galvanic influence. 
 
 * See the Note on the developement of the nervous system of the human 
 foetus, contained in the APPENDIX, also the note at p. 370.
 
 OF GALVANIC ELECTRICITY. 695 
 
 Such then being the case, and as it is now generally believed that 
 the circulation of the electricities through the atoms of matter, or the 
 electro-motive state, as it has with propriety been called, gives rise to 
 the phenomena of galvanism,* which, within these few years, has led 
 to the most splendid discoveries in the physical world, is it not reason- 
 able to suppose that similar operations to those with which galvanic 
 experiments make us acquainted, are continually taking place in the 
 elements of nature ? As it has been shewn that every species of matter 
 possesses a certain proportion of the electricities, may it not be allowed 
 that, under circumstances similar to those with which experiment and 
 observation make us acquainted, a continuous current of the different 
 electricities is produced, the rapidity and sensible effects of which vary 
 according to the accidental disposition and situation of the different 
 material bodies, and their natural states of electricity. This opinion is 
 calculated to account for many of the changes which are continually 
 taking place on the face of our globe ; and although many may not feel 
 inclined to consider these fluids as the chief agents, no one can deny 
 them a share, in producing the effects which are so frequently observed 
 upon its surface. 
 
 The laws of electricity, whether they have been observed in con- 
 nexion with its free and uncombined state, or in its form of conti- 
 guous circulation, as displayed in the various galvanic processes, have 
 been lately very closely marked and reduced even to precise calcula- 
 tion. From among these we may adopt the following general law, 
 which has been clearly established by M. Biot, namely, that " each of 
 the two electrical principles is a fluid, whose particles, perfectly 
 movable, mutually repel each other, and attract those of the other 
 principle, with forces reciprocal as the square of the distance. Also, 
 at equal distances the attractive power is equal to the repulsive." 
 
 This therefore being an established law which characterises the 
 actions of these fluids, is it not reasonable to explain the material phe- 
 nomena of the universe by its assistance, especially when such an 
 
 * The galvanic or electro-motive apparatus may be considered, " as producing, 
 by the mutual contact of the heterogeneous bodies which compose it, a developement 
 of electricity, which is propagated and distributed through its interior, by means of 
 the conductors interposed between its metallic elements (plates). If we form a com. 
 munication between its two poles, the discharge which follows, overturning the 
 state of electrical equilibrium, in the series of bodies super-imposed on each other," 
 (and forming the voltaic pile,) " causes them to be recharged, according to the con- 
 ditions of this equilibrium, either at the expense of the ground, or by the decora- 
 position of their natural electricities. The repetition, then, of such discharges, or 
 rather their continuation, must occasion in the apparatus a continued electric 
 current, the energy and the quantity of which depend as well on the magnitude 
 and the nature of the metallic elements in contact with each other, as on the greater 
 or less facility which the conducting parts of the apparatus present to the trans- 
 mission of electricity." BIOT.
 
 696 APPENDIX. 
 
 explanation may be conducted in accordance with the known laws of 
 matter, and supported by the conviction that the atoms of every ma- 
 terial substance possess certain electrical states ? 
 
 Another very important law, which regards the electric fluids chiefly 
 
 with respect to the atoms of matter with which they are associated, 
 
 must not be overlooked, viz. " that a mutual attraction exists between 
 
 the electric fluid and all material substances, when they are in their 
 
 * natural state of electricity." But this is a mere extension of the former 
 
 law as regards the connexion of these fluids with the atoms of matter, 
 
 ' and is entirely the result of the electrical influence with which these 
 
 atoms are endowed, as we can have* no idea of matter devoid of its 
 
 natural electricity. 
 
 Proceeding, therefore, upon the established laws of electricity, and 
 upon these which, it is presumed, the particles of matter obey, it may 
 be concluded, that the cohesion which exists between the atoms of un- 
 organised substances results from the attraction existing between the 
 opposite electricities. Whether we conceive the particles of matter to 
 exist innately, endowed with certain electrical states, or surrounded 
 with one or other of these fluids, according to their reciprocal affinity, 
 still the attraction between the atoms of matter must be equally the 
 result of opposite states of this universally diffused agent. 
 
 But it may be contended, that as the particles of matter mutually 
 repel each other, they therefore are either altogether devoid of any kind 
 of electrical influence, or are endowed with the property of mutual re- 
 pulsion, which they exert notwithstanding the electrical agency. But 
 this objection is by no means valid ; for it may be shewn that, even 
 granting them to possess the property of mutual repulsion, the suppo- 
 sition is favourable to the theory, and serves, moreover, to account for 
 the varied phenomena to which the different particles of matter and the 
 electrical fluids give rise. 
 
 As, however, we have just supposed that the attraction of matter 
 results from the atoms being endowed with the opposite state of elec- 
 tricity, it is as reasonable to suppose that an opposite condition to 
 attraction must take place when homogeneous particles, or those pos- 
 sessing the same kind of electrical energy, are brought within the sphere 
 of action. 
 
 From this consideration we are led to the conclusion, that attraction 
 and repulsion between the particles of matter arise as a necessary con- 
 sequence of the electrical states of these particles. The various ano- 
 malies or peculiar conditions of material substances can be easily sup- 
 posed to result from certain degrees of electrical saturation, or neutral- 
 isation, to which these substances are subjected. 
 
 From the consideration of corpuscular attraction and repulsion, 
 the transition to chemical affinity becomes evident.
 
 OF GALVANIC ELECTRICITY. 697 
 
 It may be shewn by direct experiment, that repulsion can be pro- 
 duced between two bodies, by giving one of them an electrical state 
 different from that which it naturally possesses, that is, by bringing it 
 artificially into a condition similar to the other ; so chemical attraction 
 between two bodies may be increased by exalting the energy of the 
 electrical states which they naturally possess. 
 
 As chemical affinities are the result of attraction or repulsion be- 
 tween the particles of matter, owing to their electrical conditions, so 
 these affinities will be simple or compound, according to the electric 
 states of the different materials which are brought into mutual action, 
 and according to the various energies of these states. 
 
 Having endeavoured to establish the proposition of different ma- 
 terial atoms possessing different electrical states, both as regards the 
 negative or positive modes of existence of this agent, and as respects 
 the energy of each mode; and having considered such relations sufficient 
 to account for the phenomena of repulsion and gravitation, it becomes 
 unnecessary to point the application of the doctrine to the various 
 chemical changes which take place. However, that such changes 
 actually do occur, after the manner which ci priori reasoning would 
 lead us to expect, is a general inference which presents very few 
 exceptions. But our knowledge respecting the abstract state of those 
 substances which present the presumed exceptions, is as yet so very im- 
 perfect, that no conclusive argument can be adduced that their chemical 
 combination is not the result of the electrical states of their atoms, or 
 of these fluids during their continuous circulation through them.* 
 
 The excitement of electricity by means of friction, by compres- 
 sion, by the fusion of inflammable bodies, by evaporation, by the dis- 
 engagement of gas, by the disruption of a solid body, by the contact 
 of dissimilar substances, and lastly by chemical decomposition all 
 combine in establishing the intimate connexion for which we contend. 
 
 Whenever bodies, brought by artificial means into high states of 
 opposite electricity, are allowed to restore the electricity, heat and 
 light are the consequences. (Davy.) 
 
 These effects take place in the same manner if performed in a 
 vacuum. The light thus produced appears, from the experiments which 
 
 * The celebrated botanist Mr. Brown has lately ascertained that the molecules 
 of both organised and inorganisgdjmatter are in a constant state of motion. May 
 not this motion be, in the^ftffmfer class of bodies, the consequence of the electrical 
 states of these particles, for which states we have contended above, or, in other 
 words, a sensible phenomenon of their electro-motive conditions ? The motion 
 presented by organised bodies must doubtless be ascribed to their vitality, and its 
 concomitant changes. Motion in dead organised bodies is to be referred to the che- 
 mical changes which take place, when these changes are no longer restrained from 
 supervening by the controlling influence of life, which changes, as argued for 
 above, are merely the results of electro-motive agencies.
 
 698 APPENDIX. 
 
 have been related, to be of the same nature with the solar beam, and 
 to be divisible into the prismatic colours. The light exhibited by 
 phosphorescent bodies, and by matter under its various conditions, 
 gives similar results. Therefore, from taking a survey of the elec- 
 trical phenomena, of those displayed by chemical combinations, and 
 of other manifestations of nature, we are inclined to adopt the belief 
 that light and caloric (as they exist in the solar rays, and as they are 
 otherwise produced) are the result of the combination and neutralisa- 
 tion of the opposite electricities\ whether taking place in a direct man- 
 ner and in their free state of existence, or through the medium of the 
 particles of matter which they endow ; light being more or less perfect 
 according as the neutralisation is more or less complete, and the caloric 
 resulting from the intensity of their action. 
 
 Before leaving the consideration of the action of the electric fluids 
 upon each other and upon the molecules of matter, it is necessary to 
 remark respecting a property which the molecules of matter appear to 
 possess under certain circumstances, of arranging themselves in de- 
 finite directions; this has generally been called the polarisation of 
 matter a phenomenon observed in the crystallisation of numerous 
 substances, and in different chemical actions. The polarisation of the 
 atoms of matter seems to result from the electrical states which they 
 acquire from the electricities circulating around them, and to arise 
 from a property with which the electricities are themselves endowed, 
 or from their mutual action independently of their connexion with the 
 molecules of matter. According to this view of the subject, we should 
 be led to expect, that the electricities, as they exist in the solar beam, 
 unconnected with matter, would give rise to the phenomenon of 
 polarisation, in a similar manner as when their action is exerted 
 through the medium of the atoms of matter: this conclusion is 
 supported by the experiments of Dr. Brewster, Biot, and others, on 
 the polarisation of light. 
 
 The intimate connexion which exists between the electrical agencies 
 and the magnetical attractions, is a subject which has lately in- 
 terested scientific inquirers throughout Europe. It would almost 
 seem, from their observations, that manifestations of the magnetic 
 power result from the electrised state of the atoms of the magnet, and 
 their consequent polarisation ; and from the continuous circulation of 
 the electric fluids either through its substance or upon its surface.* 
 
 * In the annual oration delivered" to the Medical Society of London in March 
 1822, we endeavoured to shew that the phenomena of attraction or gravitation, che- 
 mical affinity, combustion, crystallisation, magnetism, light and heat, (both as they 
 exist in the solar rays, and as they are otherwise produced), in short, that all the 
 phenomena of the inorganised world and of the solar systems, may be explained by 
 i of the agency of two universally diffused electricities.
 
 OF GALVANIC ET.ECTEICITY. 699 
 
 Since the discovery of Galvani, several physiologists have at- 
 tempted to explain the phenomena of the animal world by imputing 
 the functions of the nervous system to the electro-motive energy, 
 generated or developed by the cerebro-spinal masses. Amongst those 
 who have espoused this opinion, we may mention Sprengel, Reil, 
 Prochaska, Wilson Philip, Lenhossek, &c. There can be no doubt 
 that the electricities circulate through animal bodies in different 
 conditions, and give rise to subordinate offices in the animal economy, 
 under the superior dominion of a vital influence ; and, moreover, that 
 they (or one of them at least) are a stimulus to this influence. The 
 experiments of the physiologists just named, especially those of 
 Dr. Philip, shew this, but nothing more than this. They refer to 
 the electrical apparatus which certain fishes possess, and the power 
 they have of giving electrical shocks, in farther proof of the justness of 
 their inference : but it may be asked, if the nervous influence be the 
 same as electricity, why should these animals possess an apparatus 
 distinct from the nervous system, and under its control, for the 
 production of the electrical phenomena? The existence of this 
 apparatus confirms the proposition we have just now stated ; and its 
 office is evidently that of accumulating within itself, in consequence of 
 the vital function with which it is endowed, the electricities circulating 
 in the body, so that they may be discharged according to the wants of 
 the animal : but the electricities which the animal thus accumulates 
 and discharges, cannot be said, from the evidence which we as yet 
 possess on the subject, to be identical with its nervous influence, nor 
 with the vitality of its system, more than oxygen, nitrogen, hydrogen, 
 or any other fluid constantly present in, circulating through, and com- 
 bining with the constituents of the body, may be considered to be the 
 source of its numerous manifestations. The one fluid may accumulate 
 in the system as well as the other, by means of the vital operations of 
 the organ in which the accumulation takes place, and it may be again 
 discharged in consequence either of an operation determined by the 
 nervous influence, or of some other process, and, in fact, we find such 
 a phenomenon actually taking place ; but are we to infer on that 
 account, that either the one or the other of these fluids constitutes the 
 vitality of the system, or even that they are the source of vitality, when 
 it can only be shewn to be a single function from amongst the many 
 which the animal exhibits ? We find that electricity is accumulated in, 
 and discharged from, the electrical apparatus of some fishes ; and we 
 also perceive that oxygen and nitrogen are, in like manner, accumu- 
 lated in, and discharged from, the swimming bladders of other fishes; 
 but these circumstances do not warrant us to infer that electricity is the 
 nervous influence of the former, any more than that oxygen is the nervous
 
 700 APPENDIX. 
 
 influence of the latter ; or that the vitality of the one is electricity, of 
 the other it is oxygen. 
 
 But, although the agency of the electricities has been extended 
 farther, as respects the animal kingdom, by some physiologists, than 
 well-ascertained facts can warrant, it must be allowed, from the 
 evidence which has been adduced, that they give rise to very important 
 phenomena when they are brought to operate on some of the animal 
 textures. It is these effects, or rather the stimulus which electricity 
 imparts to the sensible and contractile parts of the body, that constitute 
 the chief physiological relations of electricity, and give a degree of 
 plausibility to the doctrines of those who consider that all the animal 
 functions are discharged by the electricities in their electro-motive con- 
 dition. These circumstances require that we should notice at farther 
 length the effects of this agent on the animal system.* 
 
 " According to Ritter, the electricity of the positive pole augments, 
 while the negative diminishes, the actions of life. Tumefaction of parts 
 is produced by the former, depression by the latter. The pulse of the 
 hand, he says, held a few minutes in contact with the positive pole, is 
 strengthened; that of the one in contact with the negative is enfeebled: 
 the former is accompanied with a sense of heat, the latter with a feeling 
 of^coldness. Objects appear to a positively electrified eye, larger, 
 brighter, and red ; while to one negatively electrified they seem smaller, 
 less distinct, and bluish, colours indicating opposite extremes of the 
 prismatic spectrum." 
 
 An electrical practitioner referred to by Dr. Ure, from whom the 
 above paragraph is quoted, considers that his experience in the appli- 
 cation of this agent in disease warrants him in referring its operation to 
 three distinct heads : " first, the form of radii, when projected from a 
 point positively electrified ; secondly, that of a star, or the negative 
 fire concentrated on a brass ball ; thirdly, the Leyden explosion." 
 
 The first acts, he considers, as a sedative ; the second as a stimulant ; 
 
 * Amongst the living tissues, the nervous is the best conductor of electricity ; 
 therefore when an electrical current is established through the body, it is trans- 
 mitted by this texture. If the electrical current consists only of one of the elec- 
 tricities, the molecules composing the nervous texture tend to propel each other, 
 or to disunite ; and if the electrical action is very intense, they are actually decom- 
 posed, and confounded with the fatty matter which isolates the nervous fibres ; 
 all the functions of the nerves are instantly destroyed, the irritability of the muscles 
 dissipated, and life is immediately terminated. These effects are frequently wit- 
 nessed from lightning. They are not confined, however, to the nervous and mus- 
 cular systems, all the soft parts are more or less Effected ; the blood does not 
 coagulate, owing to the dissipation of the vital influence giving rise to the pheno- 
 menon of coagulation (see p. 641); and all tissues fall quickly into a state of 
 putrefaction.
 
 OF GALVANIC ELECTRICITY. 701 
 
 and the last has a deobstruent operation. Dr. lire has found that the 
 negative pole of a voltaic battery gives more poignant sensations than 
 the positive. 
 
 The experiments of Dr. Philip with voltaic electricity have led him 
 to infer that the nervous influence is nothing else than this agent. This 
 proposition has already been noticed, and it will be again referred to ; 
 we shall only observe at this place, that his experiments appear to shew 
 the extent to which the electro-motive agency, transmitted through 
 their voluntary nerves, may prove a stimulus to particular organs, and 
 enable them to perform their functions when these functions have been 
 impeded by the removal of a natural and requisite stimulus. We have 
 at another place endeavoured to shew that the functions which Dr. 
 Philip has imputed to the cerebro-spinal nerves are actually derived 
 from another source ; that the operations of these nerves (with the ex- 
 ception of the nerves of sense) are chiefly confined to the transmission 
 of the cerebro-spinal influence, which is the natural stimulus to the vital 
 endowment that the organs receive from a different system the gan- 
 glial ; but that this stimulus cannot be considered to be galvanism, merely 
 because galvanism is a stimulus, and acts in a manner which we have 
 every reason to suppose other stimuli would act, if they were capable of 
 being transmitted through, and be present in, every part of the body 
 on which they are disposed to operate. It is the particular constitution 
 of this agent, its properties, and its relations with the solids and fluids 
 of the body, that give rise to its active operation, and to phenomena 
 liable to be confounded with those of the nervous system, or even with 
 those of life itself. 
 
 What we have just now adduced has a stricter reference to the 
 opinions of those who consider that the nervous influence and galvanism 
 are the same; we shall now refer more particularly to the notion of the 
 identity of this agent and life itself; and here we cannot do better than 
 quote the very acute, conclusive, and unanswerable observations of Dr. 
 Pring* on this subject. " We observe that electricity is related with 
 life, and acts upon it ; this is no proof of identity. We observe also 
 that electricity will substitute in some instances the properties derived 
 from a nervous centre ; in this respect there is an identical property 
 common to it and life, which is also possessed by many other substances. 
 We observe also, that the formation of heat, and the faculty of gene- 
 rating electricity, belong to animals, and are dependent upon their life. 
 The faculty of generating electricity in animals does not prove that 
 electricity is even a constituent part of their life ; it proves that it is a 
 
 * Principles of Pathology. We recommend the physiologist to study closely 
 the physiological and pathological writings of this most acute and philosophical 
 writer.
 
 702 APPENDIX. 
 
 phenomenon of their life ; but that it is a part of it, is no more to be 
 concluded on this account, than that urine or mucus, &c. is a part of 
 life, because these are also products of it. 
 
 " We have made out, then, only one point of resemblance between 
 life and electricity, which is, that electricity will in some cases substitute 
 a property otherwise derived from a nervous centre ; which property, 
 applied to the stomach, will aid digestion, in which respect it has not 
 yet been found that more common stimuli resemble it : applied to the 
 voluntary muscles, it will produce their contraction ; and in this respect 
 the property is a common one to many other substances, which no one 
 ever thought of identifying with life. But even the properties which 
 are said to depend upon a nervous centre are not all of them 'substi- 
 tuted by electricity, which will stimulate muscular contraction, like 
 many other substances, but, like those substances also, it is incapable of 
 conferring sensibility; or if electrical influence ever excites sensation in 
 paralytic limbs, it is only because their sensibility is not totally extinct, 
 and will therefore admit of sensation under the application of this, or 
 of any other stimulus of a powerful kind. 
 
 " We have seen that electricity can do a very little which is also 
 done by life ; there is then analogy in one property, but to be the same 
 identity, there must be analogy in all; or to approach to such identity, 
 there must be at least a general analogy. The living principle main- 
 tains itself by assimilation from exposure to its elements ; electricity is 
 not capable of maintaining itself from its elements, but must be pro- 
 duced from them. Muscular power in the animal system is related 
 with mind, and directed by volition ; we have no evidence that mind, 
 or volition independently of the properties which distinguish the living 
 state, can so ally itself with electricity. Animal life confers sensibility 
 on structures ; electricity can merely excite sensation in common with 
 chemical and mechanical stimuli. The organic life produces from a 
 common material, arranges, and renovates, in the muscular system, the 
 particles which compose muscle ; in the tendons, those of tendon ; in 
 the membranes, those of membrane ; in the bones, the constituents of 
 these structures ; and of all others, with all their circumstances, how- 
 ever diversified. Now if electricity were capable of doing all this, there 
 would then be established only a general resemblance with life ; analo- 
 gies would afterwards be sought for, corresponding with those powers 
 exhibited by the relation of properties of life in different seats, and 
 more especially among the phenomena of disease. But until the pre- 
 tensions of electricity to an identity with life shall be established by 
 rather a more extensive analogy, it is superfluous to inquire how far the 
 phenomena of electricity resemble those of dyspepsia, diarrhoea, con- 
 sumption, abscess, or gout. If, perchance, electricity should be en- 
 dowed with the properties engaged in these phenomena, it will be
 
 OF OSSIFICATION. 703 
 
 greatly indebted to its friends for bestowing upon it attributes which it 
 has never displayed. In the mean time, it is to be wished that experimen- 
 talists will go on multiplying their facts, and that they will abstain from 
 reasoning upon them : they will not, however, err to any great extent in 
 this way, if they will take the trouble to remember that so far as things 
 are proved to be alike, they are alike ; and where they are not proved 
 to be alike, it is possible that they may be different. 
 
 " The identity of life and electricity or galvanism has been inferred, 
 as appears from the preceding account, from very slender premises ; 
 but the arguments just considered are among the best that have been 
 proposed in favour of the sameness of the two principles, or substances, 
 if they are substances." 
 
 OF OSSIFICATION. . , 
 
 (No TE L L. See pp. 398401.) 
 
 The bones are at first of a mucous or gelatinous consistence in the 
 embryo. They next become cartilaginous, and some of them fibro- 
 cartilaginous : they are lastly perfectly ossified. At the early period 
 of the embryal state the bones gradually increase, without any apparent 
 division into separate parts. The cartilaginous bones, or the temporary 
 cartilages, do not appear before two months have elapsed from the 
 period of conception, and then this process towards ossification only 
 commences in those bones, or in the parts of bones, which are ossified at 
 a later period. It appears doubtful whether or not those bones which 
 ossify the first, or those parts of bones in which the process takes place 
 at an early period, pass through an intermediate or cartilaginous state. 
 It seems most probable, from the observations of MM. Beclard and 
 Serres, that in them the ossific deposit is made in the first or mucous 
 state of their existence ; whilst, in those bones which are perfected at a 
 remoter period, the cartilaginous or intermediate state which they 
 assume is rather a provisional function than a state of ossification^a 
 temporary condition of structure, for the purpose of performing the 
 offices of bone, and not a requisite antecedent to the ossific process. 
 
 Ossification commences successively in the different bones, from 
 about a month after impregnation, in those which are the first formed, 
 until ten or twelve years .after birth, in those which ossify at a later 
 period ; and in certain subordinate parts of bones, the ossific process 
 does not commence until the fifteenth or eighteenth year. The clavicle 
 and maxillary bones are amongst the first developed ; the sternum, the 
 bones of the pelvis, and those of the extremities, are the latest. It may 
 be considered as a general proposition, that those bones which are 
 nearest the nervous and sanguineous centres are the first to be formed, 
 as if their more immediate developement were required to protect these
 
 704 APPENDIX. 
 
 important systems : hence we perceive that the vertebrae and ribs ossify 
 at an early period. 
 
 At the end of the first month ossification commences in the clavicle, 
 and successively in the inferior maxilla, in the femur, tibia, humerus, 
 superior maxilla, and bones of the fore-arm, where it begins about the 
 thirty-fifth day. About the fortieth day this process commences in the 
 fibula, scapulum, the palatine bones ; and during the following days, in 
 the occipital and frontal bones, in the arches of the first vertebrae, and 
 in their sides, in the sphenoid, the zygomatic apophysis, the phalanges 
 of the fingers, the bxpnes of the vertebrae, the nasal and zygomatic 
 bones, the ilium, thBhetacarpal "bones, the condyles of the occipital 
 bones, in the squamous portion of the temporal bone, the parietal, and 
 in the vomer : in all these, ossification begins about the middle of the 
 seventh week. In the course of the same week it appears also in 
 the orbitar process of the sphenoid; and, about the end of the week, in 
 the metatarsal bones and phalanges of the fingers and toes. During 
 the ten following days it begins in the first sacral vertebrae, and around 
 the tympanum. During the subsequent weeks and months it com- 
 mences in the bones of the ear, in the pubis, in the processes of many 
 of the already-mentioned bones, in the small bones of the extre- 
 mities, &c. 
 
 Ossification does not always result, as we have already noticed, 
 from the transformation of cartilage into bone. The diaphysis of the 
 long bones, and the centre of the large bones, which are amongst those 
 first formed, pass immediately from a mucous to an osseous state. The 
 other parts of this structure have an intermediate cartilaginous con- 
 dition : and it is in these parts that the successive stages of ossification 
 may be best observed. 
 
 The cartilage which, for a longer or shorter period, supplies the 
 place of bone, becomes at first hollowed into irregular cavities, after- 
 wards into canals lined with a vascular membrane and filled by a muci- 
 laginous and viscid liquid ; these canals become red, the cartilage now 
 assumes an opaque appearance, and ossification commences towards its 
 centre. The first point of ossification is always in the centre of the 
 cartilage, and never at its surface. This point is surrounded by a 
 reddish cartilage, and that part which is nearest it is opaque and pierced 
 with canals still farther than the opacity reaches. 
 
 The osseous point augments progressively by means of additions on 
 its surface, as well as by an interstitial deposit in its substance. The 
 cartilage gradually becomes hollowed by cavities and canals, lined by 
 a vascular sheath, diminishes as the ossification extends, and disappears 
 altogether when the process is completed. 
 
 With respect to the state in which the osseous matter is formed, we 
 are inclined to agree with M. Beclard in the opinion, that the earthy
 
 OF VOICE VENTRILOQUISM. -~; <.* 
 
 -matter is deposited in a fluid condition, and at the same time witi* 
 animal matter, 'in the organised tissue which secretes it. Its subse- 
 quent solidification arises either from the deposition of a larger pro- 
 portion of earthy matter, or from the absorption .-of the vehicle which 
 gives it the fluid condition ; or from the joint ofjferation of both these 
 causes. | % fcj 
 
 I r. * 
 
 OF VOICE. 
 (NOTE M M. See p. 439. 
 
 The cricoid cartilage, which supports the tv^ttayterioid cartilages, 
 is not immovable at the inferior part of the larynxS \ The trachea, to 
 which it is attached by its inferior margin, yields and elpngates itself 
 in order to allow it motion. The muscles of the larynx do not contri- 
 bute to the production of the voice solely by means of the action which 
 they exercise on the sides of the glottis ; several of them, and particu- 
 larly the thyro-arytenoids, may be considered as forming a part of the 
 parietes of this opening. These small muscles give rise to acute 
 sounds, by drawing closer the two arytenoid cartilages, and when in a 
 state of contraction they also seem susceptible of a vibratory motion, 
 varying in degree according to the degree of contraction : by the as- 
 sistance, therefore, of the muscular fibres covering its sides, the glottis 
 is susceptible of vibrations analogous to that of the lips applied to the 
 opening of a French horn. The production of sound is owing to the 
 action of the muscles of the larynx on its cartilages during expiration; 
 and whatever impedes the functions of the nerves actuating these 
 muscles, puts a stop to the utterance of sound. 
 
 Of ventriloquism, (p. 445.) Various attempts have been made to 
 explain the manner in which the ventriloquist is enabled to modify his 
 articulations into the semblance of distinct voices. Dr. Good considers 
 ventriloquism " to be an imitative art, founded in a close attention to 
 the almost infinite variety of tones, articulations, and inflexions, which 
 the glottis is capable of producing in its own region alone, when long 
 and dexterously practised upon ; and a skilful modification of these 
 vocal sounds, thus limited to the glottis, into mimic speech, passed 
 for the most part, and whenever necessary, through the cavity of the 
 nostrils, instead of through the mouth." He farther supposes that 
 " some peculiarity in the structure of the glottis, and particularly in 
 respect to its muscles and cartilages," is requisite to carry this art 
 to perfection. The explanation which Magendie offers on this sub- 
 ject appears to us to be more correct, although perhaps not sufficiently 
 so. This physiologist asserts that ventriloquism consists in certain 
 modifications of sounds or speech, produced by a larynx of the com-
 
 706 APPENDIX. 
 
 mon formation, with a strict attention to the different effects of sound 
 thrown at different distances, and through different modes of convey- 
 ance. We cannot agree with Dr. Good, that the ventriloquist performs 
 articulation by means of the larynx only, although we may concede 
 some share in the process to this organ ; nor can it be granted that 
 any " addition to the muscular organism of the glottis" is enjoyed by 
 those who have perfectly acquired this imitative art. 
 
 OF THE GENERATIVE ORGANS, AND THEIR FUNCTIONS. 
 
 (NOTES N N. See pp. '454, 457, 461469.) 
 
 I. Of the male organs of generation. The cellular structure of the 
 corpora cavernosa penis, according to the microscopic examinations of 
 M. Bauer, appears to be made up of an infinite number of thin mem- 
 branous plates, exceedingly elastic, so connected together as to form a 
 trellis-work, the edge of which is firmly attached to the strong elastic 
 ligamentous substance which surrounds the whole, and also forms the 
 septum pectiniforme. This substance has an admixture of muscular 
 fibres. The cells are generally larger, or rather the trellis-work is more 
 loose, in the middle portion of each corpus cavernosum. 
 
 Arterial ramifications are supported by this reticular structure, and 
 they are distributed every where throughout the cavernous part of this 
 organ. In the usual state of the penis, the blood is not poured into 
 the cells, but returns by the veins, and it remains flaccid ; but when a 
 person is under the influence of particular impressions, the minute 
 arterial branches, which before had their orifices closed, now have their 
 action suddenly increased, and pour from their open mouths the blood 
 into these cells, so as to overcome the elastic power that under ordi- 
 nary circumstances keeps them collapsed. 
 
 The corpus spongiosum penis appears, from the observations of the 
 same physiologist, to consist of the same kind of structure as that ob- 
 served in the corpora cavernosa, but on a less scale. Its structure is 
 also more regular throughout ; without, however, having any muscu- 
 lar fibres mixed with the trellis-work, these being confined to the outer 
 surface of the inner membrane of the urethra. The erection of this 
 part is supposed to take place after the same manner as that of the 
 corpora cavernosa, namely, from a vital expansion taking place in the 
 extremities of the arterial capillaries, and thus allowing the blood to 
 flow from them into the cells of both structures. 
 
 We may state, moreover, that the arteries of the -penis are sur- 
 rounded by a larger proportion of nerves than in most of the other 
 tissues of the body. The veins form very numerous anastomoses. It 
 is the division, on dissection, of these numerous veins, and of their 
 numerous roots, anastomoses, and plexuses, which, in the opinion of
 
 OF THE tlENKRATlVE OKGAXS, &C. 707 
 
 M. Beclard, gives the appearance of cells, the existence of which he 
 denies. Erection of this texture is the result of the influence of the 
 nerves upon the arteries and veins belonging to it. By this influence 
 the action of the arteries is increased, whilst the diameter of the veins 
 returning the blood is diminished by the tonic contractility which these 
 nerves exert on the coats of the veins. 
 
 P. 454. The vesiculee seminales may, under particular circum- 
 stances, more likely to occur in the human species than in the lower 
 animals, be employed as reservoirs ; although their ordinary use may 
 be to secrete a fluid which, mixing with the semen in coitu, may 
 render the act more perfect, and more likely, therefore, to produce 
 fecundation . 
 
 P. 459. MM. Prevost and Dumas have both examined the sper- 
 matic animalculae. They seem to vary in form in different animals, 
 and to be the product of a real secretion. These physiologists con- 
 clude, " 1st, that spermatic animalculae have nothing in common with 
 infusory ones, except in their microscopic size ; 2d, that they are pro- 
 duced in the testes alone, but do not appear in these organs till the age 
 of puberty ; and 3d, that they seem to be the active principle or agent 
 of the semen." 
 
 II. Of the female organs of generation. P. 457. The uterus, the 
 ovaria, and the Fallopiap tubes, receive their nerves from the abdominal 
 portion of the trisplanchnic nerves, branches of which unite variously 
 with each other, and form six plexuses. The first, which M. Tiede- 
 mann calls spermatic, or the plexus common to the ovaria and tubes, 
 is situated on the anterior surface of the abdominal aorta, and on the 
 origin of the internal spermatic artery. It is formed of a number of 
 branches which come from the renal ganglia. Its filaments descend, 
 surrounding the arteries of the ovaria, between the membranes which 
 form the broad ligaments of the uterus, and arrive at the ovaria and 
 tubes, in which they are ramified ; a few filaments reach the fundus of 
 the uterus. 
 
 The second plexus, which is the largest, M. Tiedemann calls the 
 superior lumbar plexus, or common uterine. It is formed of branches 
 which proceed from the superior lumbar and renal ganglions; and is 
 placed on the body of the fifth lumbar vertebra, and on the promon- 
 tory of the sacrum, between the iliac arteries. On its entrance into the 
 pelvic basin, it divides itself into two considerable plexuses, which M.T. 
 calls the hypogastric or lateral uterine plexuses. These are placed 
 on the trunks of the iliac arteries, and anastomose with the first and 
 second sacral ganglions. A great many filaments proceed from these 
 plexuses, forming a reticulum around the arteries of the uterus, with
 
 708 APPENDIX. 
 
 the ramifications of which they penetrate into the texture of the organ, 
 chiefly its posterior and lateral aspects. 
 
 Several branches proceed from the superior lateral or hypograstric 
 plexus to the vagina, at the point of its union with the neck of the 
 uterus, and there unite with the anterior branches of the third and 
 fourth sacral nerves, and form a large plexus, which M.Tiedemann 
 calls the inferior lateral hypogastric, and which interweaves with and 
 embraces small ganglia. This gangliform plexus gives origin to a great 
 many branches, chiefly to the vagina, to the uterus, and also to the 
 bladder and rectum. These nerves, as well as those belonging to the 
 other plexuses, always closely embrace the arteries in the form of a 
 net- work. 
 
 It appears, therefore, that the womb and its appendages are sur- 
 rounded by important nervous plexuses. These nerves are soft, small, 
 reddish-gray, and in every respect similar to the other portions of the 
 great sympathetic nerves. Of their appearance and character we have 
 had several opportunities of satisfying ourselves, when making re- 
 searches respecting this grand organic system ; and we can bear testi- 
 mony to the correctness of the observations of M. Tiedemann. 
 
 M. Tiedemann states, that the number and size of the uterine 
 nerves vary according to the age of the female ; that they are small 
 and apparently few in girls large and numerous in adults and very 
 small in old women. He has observed another fact, confirmatory of 
 their functions, which indeed was previously noticed by Dr. W. Hunter 
 and Professor Chaussier, that these nerves become larger and more 
 numerous during gestation, a fact which we have verified on several 
 occasions. 
 
 III. Of impregnation. P. 464. Several opinions have been enter- 
 tained respecting the impregnating process. Some physiologists suppose 
 that the actual contact of the ovum and semen are requisite ; others 
 that the aura seminalis is all that is requisite. Of the former class of 
 physiologists, some suppose that the semen is absorbed into the uterus, 
 where the ovum, having descended through the Fallopian tubes, meets it ; 
 others consider that the semen is conveyed by a peristaltic-like action 
 of the vagina, uterus, and tubes, to the ovarium, and they adduce in 
 support of their opinion the occurrence of extra-uterine fetation ; a 
 third party belonging to this class conceives that the semen is con- 
 veyed to the ovum itself, in its situation in the ovarium, by means of 
 absorption, through a set of vessels allotted to this specific purpose. 
 Dr. Dewees, of Philadelphia, has argued strenuously for this last doc- 
 trine ; it has also been adopted by other physiologists ; and it seems 
 to have received support from the labours of Dr. Gartner, of Copen-
 
 OF IMPREGNATION, &C. 709 
 
 hagen, who has discovered, in some animals, a duct leading from the 
 ovary to the vagina. The occurrence of ovarian fetation wherein the 
 fetus is lodged within the enveloping membrane of the ovarium, can 
 be most satisfactorily explained by means of this doctrine. Two cases 
 of this description have lately been detailed by Dr. Granville and 
 Mr. Painter. It must, however, be allowed, that the latter class of 
 physiologists, or those who contend for the impregnating influence of 
 the aura seminalis, have it in their power to adduce strong arguments 
 in behalf of their opinion. It has even been asserted, very recently, 
 by some continental physiologists, that the impregnating power of the 
 aura, seminalis may be proved by experiment performed on rabbits, in 
 the following manner : Let the semen be received in a cup, over 
 which is to be immediately placed an inverted funnel; and let the 
 apex of this funnel be introduced into the vagina. If this experiment 
 be performed immediately after the seminal emission, they say that 
 impregnation will be the result. 
 
 It has been argued, that the venereal desire is present in neither 
 sex before the developement of the testes and ovaria. This, however, 
 is not the case. The venereal appetite makes its appearance in both 
 girls and boys long before the generative organs are developed. It 
 has been frequently observed in them both, in temperate climates, as 
 early as the sixth or seventh year. It has also been supposed, that 
 the venereal appetite disappears soon after the menses have ceased to 
 flow ; this also is not the case. 
 
 With respect to the assertion, that the venereal orgasm on the part 
 of the female is necessary to impregnation, we may observe, that 
 although it may be requisite in some females, it is by no means so in 
 others ; for many women conceive who are indifferent during the 
 venereal congress ; there are others who conceive, notwithstanding 
 their successful endeavours to suppress their orgasm; and some are 
 impregnated, when, owing to disease, as procidentia uteri, &c. they 
 cannot be supposed to enjoy much pleasure from the act.* 
 
 Sir Everard Home (Phil. Trans. 1818,) states that corpora lutea are never ' 
 met with before puberty. They are formed in the loose structure of the ovarium 
 previous to, and independent of, sexual intercourse ; and when they have fulfilled 
 their office of forming ova, they are afterwards removed, by absorption, whether 
 the ova be impregnated or not. It seems that the ovum too, with its amnion and 
 chorion, is formed in the virgin after puberty. This was found to be the case in a 
 woman of twenty years of age, who had a perfect hymen. " The Fallopian tube of 
 that side was fuller than the opposite. The fimbriae were spread out, and 
 unusually vascular." We know that animals part with their eggs whether there be 
 sexual intercourse or not ; and this is done with such force during coition, that the 
 cavity of the corpus luteum is absolutely inverted, so that the ovum is exposed 
 completely to the emission of the male. Extravasation of blood follows the rupture 
 of the ovum frequently to so great a degree, that blood occasionally passes out
 
 710 APPENDIX. 
 
 , Dr. Blundell found, in his experiments, that when only one of the 
 uteri of a rabbit was divided, or rendered impervious at its neck, or 
 when the passage to both was obstructed by tying the vagina, and 
 afterwards freely admitted to the male, that the obstructed uterus, or 
 uteri, did not become impregnated; but he found, in those whose 
 vagina was tied, that, notwithstanding, the ovaries, Fallopian tubes, and 
 womb, were excited by coition ; and in those who admitted the male 
 frequently, the abdomen acquired a large size, and in some cases 
 exceeded the bulk of mature gestation. These enlargements arose 
 from an accumulation of a humour in the womb, which, at a 
 temperature below boiling, formed albuminous concretions. In its 
 appearance it was various, but generally fluid, pale, and turbid. In 
 those who had only one uterus obstructed, the sound one became 
 filled with foetuses, and the barren one with the humour described. 
 The formation of the lutea, the developement of the womb, and the 
 repeated accumulations of fluid, in consequence of coition, in these 
 v experiments, seem to indicate the descent of the rudimental material. 
 
 Thus, although the passage to the uterus was completely in- 
 terrupted, the tubes were excited by the venereal orgasm, they really 
 conveyed the rudiments to the womb, and these rudiments engendered 
 the watery accumulations there, in the abortive attempts at generation. 
 This appears to confirm the supposition, and indeed to establish it, 
 that even in viviparous animals, generation may be carried to a certain 
 extent, although the access of the semen to the rudiments is in- 
 terrupted : under these circumstances, the young animal cannot be 
 formed, it is true, but corpora lutea may be generated, the womb may 
 be developed, and the rudiments may even be transferred to the 
 uterine cavity by the play of the Fallopian tubes. This opinion 
 receives countenance from the generation of oviparous animals, in 
 most of whom the rudiments may be discharged, independently of 
 preceding impregnation.* 
 
 Dr. Blundell supposes that the vagina and womb perform a 
 peristaltic motion, from the stimulus of the semen, both in the human 
 subject and lower animals ; and that this motion conveys the semen to 
 the rudiments. 
 
 From these experiments it would appear, that the presence of 
 corpora lutea cannot be relied upon as a proof that impregnation had 
 taken place. There is evidence that they may be produced even 
 
 through the vagina. In nine months after impregnation the corpus luteum is 
 nearly absorbed, but a new one is usually found in a state of forwardness in the 
 other ovarium. All preparations of corpora lutea, which are made from women 
 who have died in child-bed, belong, in Sir E.'s opinion, to ova which were to 
 succeed, not to the ovum of the child which had been born. 
 * Med. Chirug. Trans, vol. x.
 
 OF THE DEVELOPEMENT OF THE FffiTL'S. 711 
 
 independently of the sexual intercourse, from the mere excitement of 
 desire in a high degree. Dr. Blundell has in his possession a pre- 
 paration of the ovaria of a young woman who died of chorea, under 
 seventeen years of age, in which the hymen was unbroken, and nearly 
 closed the entrance of the vagina. In these ovaries the corpora lutea 
 are no fewer than four two rather obscure, the other two perfectly 
 distinct. 
 
 As Dr. Blundell's experiments go to prove that impregnation 
 cannot take place without the semen coming in contact with the 
 rudiments, he therefore supposes, that when the ovary lodges either 
 in the tubes, the peritoneal cavity, or in the ovary itself, and there 
 impregnated, that the semen must be conveyed to those situations. 
 Or, that the rudiments in their descent meet the semen in its ascent, and 
 that the transfer of the semen beyond the womb may be the cause of 
 extra-uterine pregnancy. 
 
 IV. Of Superf (station. M. de Bouillon* has adduced an instance 
 of superfoetation in a negress. At the end of her pregnancy she was 
 delivered of two male children, full-grown, and of the same pro- 
 portions, but the one a negro and the other a mulatto. The mother, 
 after a long resistance, confessed that she had connexion the same 
 evening with a white and a negro. Similar instances have lately been 
 detailed in the American journals, of which we shall only instance the 
 following : A white woman, near Philadelphia, is said by Dr. Dewees 
 to have been delivered of twins, one of whom was perfectly white, the 
 other black. The latter of these had all the characteristics of the 
 African, whilst the former was delicate, fair-skinned, light-haired, and 
 blue-eyed. Similar cases have been detailed by Dr. Elliotson, and 
 Drs. Norton and Stearns, of New York. 
 
 Superfoatation, in our opinion, can only take place under circum- 
 stances similar to those which produced it in the foregoing instances : 
 in them, it would seem, that there had been connexion with different 
 individuals within a short space of time. We conceive that, when the 
 decidua is thrown out, and the ovum has formed its connexions, 
 superfoetation is then impossible, unless in the case of a double uterus. 
 
 OF THE DEVELOPEMENT OF THE TEXTURES AND ORGANS 
 OF THE FCETUS. 
 
 (NOTE O O. See pp. 469481.) 
 
 It was our intention to have illustrated this subject at considerable 
 length ; but we have so far exceeded our limits, that we must now be 
 brief. 
 
 Bulletfn de la Faculte et de la Societe de Midecine, No. 3.
 
 712 APPENDIX. 
 
 I. Of the developement of the foetus. At first the embryo appears 
 to be only a semi-liquid vesicle, and to consist of minute globules 
 disseminated through a more fluid medium, which presents an oval or 
 spheroid form.* As the embryo advances, the proportion of solid 
 matter increases, and continues to increase to the termination of the 
 life of the individual. The first stage of its existence resembles that of 
 the polypus ; and the globules which may be observed in its otherwise 
 homogeneous texture closely resemble those which are observed in the 
 nervous system. At first the embryo is colourless ; it afterwards 
 presents a gradual developement of colour, and at last a coloured fluid 
 may be discerned. From a state of organisation consisting merely of 
 disseminated globules fibres, membranes, and vessels, come suc- 
 cessively into existence. The organs, as we have already said, are not 
 formed at once; they are gradually developed. Even particular 
 systems do not assume at once their form of organisation, but are 
 developed by degrees, and run through the same stages of organisation 
 as may be remarked in the animal scale. This is particularly re- 
 markable as respects the developement of the nervous system.f (See 
 the note on this subject, p. 662.) 
 
 The exterior form of the fetus seems to be assumed before its 
 tissues attain any considerable degree of consistence. The glandular 
 viscera are at first formed in isolated parts. The globules of the 
 nervous system first appear; these become united into chords and 
 ganglia. The vessels commence in isolated vesicles, which become 
 elongated, and connected in regular series. The intestinal tube seems 
 to be the viscus which first presents a definite conformation. It is at 
 first straight, and afterwards it curves forwards, and is embraced by 
 the umbilical chord : it thus forms an angle, and descends into the 
 abdominal cavity, which is open at its anterior aspect, and apparently 
 - continuous with the short and imperfectly developed chord. This 
 turn of the intestinal canal, and its retention in the chord, seems to 
 form the umbilical vesicle ; and the subsequent strangulation of the 
 
 * Mr. Bauer says that he has detected the human ovum on the eighth day from 
 coition. It consisted of two membranes: the external one open throughout its 
 length, but with its edges turned inwards, like the shells of the genus valuta ; 
 the internal membrane pointed at one end, and obtuse at the other, slightly con- 
 tracted in the middle, and containing a slimy fluid and two vesicles. 
 
 f It would appear, that, in the process of the growth of the embryo even of 
 man, during the first days of its existence the nervous system can only be 
 traced as it exists in the polypi ; its globules seem dispersed through the embryal 
 structure : as the ovum advances, the ganglial branches, and the ganglia them- 
 selves, make their appearance, the nerves of sensation and voluntary motion, the 
 spinal chord, and the brain, being successively formed. See the remarks on the 
 Developement of the Nervous System.
 
 OF THE DEVELOPEMENT OF THE NERVOUS SYSTEM. 713 
 
 intestine, by the constriction and elongation of the chord, first gives 
 rise to an isolated appearance of this vesicle ; subsequently, to its entire 
 disappearance ; and lastly, to the separation of the intestines ; the ,, 
 vermiform appendix remaining as a type of the original conformation. 
 
 About the same time that the intestinal tube curves into the 
 umbilical chord, the urinary bladder seems to be also prolonged into 
 the chord, between the chorion and amnion, forming the allantois and 
 urachus, the former of which disappears as the foetus is developed and 
 the chord lengthened, the urachus only remaining at the time of birth, 
 shewing the nature and type of the original conformation, and the 
 communication formerly existing between the allantois and bladder. 
 
 We have already said, that all the phases through which the 
 human embryo passes until its conformation is perfected, correspond 
 with the different stages of permanent organisation which characterise 
 the animal scale. Since these observations were first published by 
 us, we perceive that a similar opinion has been entertained, by J. F. 
 Meckel, and adopted by M. Beclard in his excellent work on 
 General Anatomy. Many proofs may be adduced in support of this 
 doctrine : so evident indeed is the analogy, that a very close parallel 
 may be drawn between the stages of developement through which the 
 human fetus passes, and the degrees of animal organisation. 
 
 The human embryo is at first an imperfectly formed vesicle : such 
 are the polypi and others of the zoophytes. At a remoter period it 
 consists of a small vermiform body, without a distinct head or limbs : 
 such are the echinodermata and the annelides. At a still later 
 period its limbs are equally developed, and its tail is prominent : such 
 are the quadrupeds. 
 
 As respects the nervous system, the ganglial or vital nerves first 
 appear with their ganglions : such is the , nervous structure of the 
 invertebrated animals. As the embryo advances, the ganglial nerves 
 give rise to two thin strips of medullary matter, in the situation of the 
 spinal canal, these increase, coalesce, form the spinal and cervical 
 marrow (medulla oblongata), and the tubercles of the latter, whence 
 are produced the brain and cerebellum : we observe the same con- 
 formation in reptiles, fishes, &c. 
 
 The human fetus is remarkable for the rapidity with which it runs 
 through the early grades of the scale of organisation. It is this 
 circumstance that renders the early changes which it experiences so 
 difficult to be recognised. 
 
 II. Of the developement of the nervous system. -Viewing the 
 nervous system throughout the numerous classes of animals, and tracing 
 the process of its formation from the embryo up to the period of 
 perfect fetal existence in the perfect animals, especially in man, we
 
 714 APPENDIX. 
 
 are led to infer that this system is not originally formed from the centre 
 towards the circumference, but that the origin of its ramifications 
 commences in the mucous or cellular tissue, when the embryo is yet 
 but in an apparently homogeneous state; and that as the textures 
 become, in the process of foetal growth, more and more developed, so 
 the globules composing the nervous system, and chiefly those of the 
 ganglial system of nerves, are arranged into chords of communication, 
 chiefly in the course of the vessels, for the purpose of preserving a 
 connexion between the organs, and reinforcing each of the tex- 
 tures with the influence which they generate in their perfect state of 
 developement. As the process of foetal growth proceeds, the nervous 
 ramifications advance towards centres, which vary in their characters 
 according to the species of the animal ; in those which are more 
 perfect, those centres are numerous, and almost each differs in a more 
 or less sensible manner from the other, both as to appearance and 
 function. 
 
 At an early period of foetal life the ganglial ramifications and 
 centres are first formed, and afterwards the ramifications and centres 
 of the voluntary nerves. In the more perfect animals, even that part 
 of the nervous system which is general throughout the animal creation, 
 and which the lowest orders of it possess, is the first formed ; and that 
 part which is destined to perform the highest functions, and which the 
 perfect animals only possess, is produced the last. 
 
 III. Of the developement of the heart and lungs. J. F. Meckel 
 has concluded from his observations, 1st, The heart is relatively larger, 
 the younger the embryo. For in his observations he found, at the first 
 period at which the heart could be distinguished, that it filled com- 
 pletely the thoracic cavity. 
 
 2d, The heart is more symmetrical with respect to situation and 
 form, soon after its formation, than at a more remote period. 
 
 3d, The form of the heart undergoes various changes during the 
 growth of the foetus. 
 
 A . The proportion between the arterial and venous portions of the 
 heart is not always the same. The auricles surpass the ventricles in 
 capacity, in proportion as the embryo is younger. 
 
 B. The relative volume of the two sides of the heart is not always 
 the same at all periods. In the adult the right side always more or 
 less exceeds the left ; but in very young embryos the two ventricles are 
 equally capacious, but that of the right side increases rapidly. The 
 right auricle surpasses the left in size in the foetus, and it is only by 
 degrees that the left becomes equal to the right. 
 
 C. The right ventricle is unquestionably smaller than the left at 
 first.
 
 OF THE DEVELOPMENT OF THE HEART AND LUNGS. 715 
 
 D. The thickness of the parietes of the heart is much more con- 
 siderable at first. The two halves of the heart equally present this 
 difference, but the right ventricle always appears a little thicker than 
 the left. This is, however, less, the younger the foetus. 
 
 E. The two ventricles communicate with each other at an early 
 period, and, according to all appearances, continue to do so until the 
 end of the second month, by means of an opening in their interior 
 aspects, situated at their base, and immediately beneath the origin of 
 the great vessels. 
 
 F. The interior disposition of the auricles with respect to their com- 
 munication, either with one another, or with the venous trunks, under- 
 goes considerable changes. These turn chiefly on the form and size of 
 the oval hole, the situation of the orifice of the vena cava inferior, the 
 situation, the form, the extent, and relations of the valve of Eustachius, 
 and that of the foramen ovale. Here M. Meckel's researches confirm 
 those of Sebatier and Wolff. 
 
 4th, The disposition of the aorta and of the pulmonary artery offers 
 several considerable changes in succession, of which the following are 
 the chief: 
 
 A. At first there exists only an aorta. A pulmonary artery is formed 
 at a remoter period. It is not until after the seventh week that the pulmo- 
 nary artery begins to appear, and then it is only a second aortic trunk, 
 as yet without branches a right aorta, proceeding in the direction of 
 the bangs, which are very distant, and extremely small. 
 
 The disposition of the large arteries at this period (seventh week) 
 nearly resembles what it continues to be, in reptiles, during the whole 
 life of the animal. 
 
 B. It is in the course of the eighth week only, that the branches 
 of the pulmonary artery can be discovered. They are then much 
 smaller, when compared to the trunk of the artery and to the arterial 
 canal, the younger the embryo. At five months they become equal id 
 this canal, and afterwards they surpass it, frequently so far, that when 
 the foetus has completed the ninth month, each principal branch of the 
 pulmonary artery is as large as it is, or even larger. 
 
 The venous canal presents similar appearances. It is during the 
 first periods of the existence of the foetus that it offers, proportionally, 
 the greatest amplitude. All the observations which M. Meckel has 
 made, confirm the law, which is the more important, as it throws con- 
 siderable light on the functions of this canal. Indeed it is probable 
 that this conformation is only the remains of a disposition which may 
 be seen at the epoch when the liver has not come into existence, when 
 the vena porta and the vena cava inferior form but one trunk, as the 
 pulmonary artery forms, at the early stage of its existence, only one with 
 the aorta. This conjecture respecting the origin of the venous canal
 
 716 APPENDIX. 
 
 is confirmed by the organisation of the acephalous class of animals, in 
 which the veins of the intestinal canal, and consequently the venaporta, 
 also open immediately into the vena cava inferior. 
 
 5th, The lungs are not formed until a more advanced period. 
 
 In man, manifest traces of them cannot be seen before the sixth or 
 seventh week. Then they advance beneath the heart, at the two sides 
 of the inferior extremity of the pectoral portion of the aorta. At the 
 period of their appearance, and even for some time afterwards, they are 
 so small, in proportion to the heart and the other organs, that it re- 
 quires the greatest attention in following their progressive develope- 
 ment, to be convinced that they aVe in reality the rudiments of the 
 respiratory organ. 
 
 At first the lungs closely approach one another : they are flat and 
 of a whitish colour. Their surface is perfectly united ; but on their 
 external border may be observed, at an early period, indentations, 
 which are the traces of the approaching separation of the lobes, notwith- 
 standing that these lobes are not yet in existence. At a farther advanced 
 period the lobes appear to be composed of lobules. These latter are 
 at first larger and much less numerous, in proportion, than at subse- 
 quent periods, but they separate by degrees into others much smaller. 
 At the period when they are first observed, they are as much more ap- 
 parent, and as much less intimately united, by cellular tissue, as the 
 embryo itself is younger. 
 
 6th, As the lungs become developed, in the reptiles and leeches, in 
 the form of an empty sac, it is natural to suppose that their production 
 in animals of a higher order takes place according to the same manner 
 and law. M. Meckel endeavoured to ascertain whether or o this was 
 actually the case. But, under whatever aspect he viewed the lungs at 
 the early stages of their formation, even with the assistance of the 
 microscope, he always found the slices which were removed from 
 them completely solid : if they are really so during this epoch, it would 
 seem as if they had some analogy of structure with the branchiae of 
 fishes. 
 
 7th, The branches of the pulmonary artery, which proceed from 
 the right or pulmonary aorta, are at first certainly wanting. It must 
 therefore be admitted, that at this epoch their places are supplied by the 
 bronchial arteries, especially by the inferior, since the lungs are at first 
 placed low in the inferior part of the chest. Moreover, this depending 
 situation of the respiratory organ, at the commencement of itsdevelope- 
 ment, is remarkable under two points of view : 
 
 A. Since, amongst reptiles, and many of the mammiferi, the lungs 
 are placed much lower than in man, and below the heart, in every re- 
 spect like the fishes, the swimming bladder is placed below this organ. 
 
 JB. Because it seems that the lungs and the thymus gland corre-
 
 OF THE CIRCULATION OF THE FffiTUS. 717 
 
 spond in their functions, the developement of the one being in direct 
 proportion to the decrease of the other. 
 
 J. F. Meckel concludes from the researches of which we have given 
 an abrfdged outline, that the general results confirm it to be a grand 
 law of the animal economy, that the embryo, from the instant of its 
 formation until that of its maturity, rises successively through many in- 
 ferior grades of organisation, and that the principal monstrosities of the 
 heart and large blood-vessels depend upon these organs being arrested 
 at some one grade or degree of organisation, instead of following the 
 progress of the others towards perfection. 
 
 IV. Of the circulation of the placenta and nutrition of the foztus. 
 There are abundant facts to prove that the circulation of the foetus is 
 independent of that of the mother ; that the blood of the former flows 
 from the umbilical arteries into the vein of the same name, and not 
 from the uterine arteries into that vein ; that the foatal blood is fabri- 
 cated by the foetus itself from the juices furnished by the mother to the 
 placenta, and absorbed by the radicles of the umbilical vein ; and, con- 
 sequently, that the foetus does not receive one drop ready formed from 
 this organ.* 
 
 In proof of the correctness of this opinion, we may refer to the ex- 
 periments performed by M. Gaspard,f in order to ascertain this point; 
 to the formation of the blood in the impregnated egg on the second 
 or third day after incubation ; and to the fact that, in the numerous 
 tribe of oviparous animals, the foetuses are insulated from the mother, 
 and are the real manufacturers of their own blood. 
 
 Admitting, therefore, that the foetus is the fabricator of its own 
 blood, from the nutritive juices derived from the placenta, by what 
 organs, it may be asked, is the sanguifying process performed ? The 
 great size of the liver during foetal existence, the early formation of this 
 viscus, and the large quantity of blood which is conveyed to it by 
 the umbilical vein, would suggest it as the chief organ of sangui- 
 fication. We have already referred \ a sanguifying function to the liver 
 as well as to the lungs, during extra-uterine life, and we believe 
 that this function, which cannot be performed by the lungs during 
 foetal existence, is chiefly accomplished by the liver. Some authors 
 
 * D. F. Lavagna concludes that the menstrual blood differs from common 
 blood only in containing no fibrin ; also, that the blood in the umbilical arteries of 
 the funis contains scarcely any fibrin, whilst that in the umbilical vein forms a 
 tenacious jelly : hence he infers that the blood acquires fibrin in the circulation 
 in the placenta, which it parts with in its passage through the foetus. Annali di 
 Medicina di Milano, No. 17- 
 
 f Journ. de Physiol. Experiment. No. 3. 
 
 J See Appendix, Note M. p. 580.
 
 718 
 
 conceive, particularly M. Geoffrey St. Hilaire and Dr. R. Lee, that 
 the blood circulating; in the liver of the foetus supplies an abundant 
 bilious secretion, of a mild or albuminous character, which, when 
 poured into the alimentary canal, and mixed with the mucous secre- 
 tion of the bowels, is there digested and converted into chyle, and car- 
 ried into the foetal circulation for its nourishment. This opinion 
 seems very probable. The sanguifying process of the liver appears to 
 us intimately connected with a secreting function, the former in a 
 great measure depending upon the latter ; or, in other words, the 
 secretions performed by this orgaq being the elimination of matters 
 from the blood, the discharge of which is necessary to the perfect 
 state of sanguification. It should, however, be recollected that a very 
 large part of the bile secreted during extra-uterine life is actually 
 recrementitious ; and wherefore may it not be altogether so during the 
 comparatively short period of foetal existence ? 
 
 Other peculiarities of the foetus are adduced in the different sec- 
 tions of this Note; but on these, and various other subjects, many 
 of which we could not even enter upon, our limits have obliged us to 
 be extremely brief. 
 
 V. Respiration of the foetus. The thymus gland appears to assist 
 the placenta, the liver, and the secretion of fat, in the respiration of the 
 fcetus, or rather in-purifying the blood of the fetus. It seems to form 
 a nidus for the reception of those elements of the blood, carbon and 
 hydrogen, which are secreted in a state approaching to fat, and which, 
 if too abundant in this fluid, would endanger the existence of the foetus. 
 These materials on the commencement of active respiration are again 
 absorbed, to be discharged from the economy by the lungs, liver, or 
 intestinal canal. The thymus gland in the human foetus, in the ninth 
 month, generally weighs from 160 to 180 grains ; at twenty-eight years 
 of age , only 90 grains. 
 
 In the calf it weighs sixteen ounces, in the cow nine ounces. 
 
 " Etenim placenta, hepar, adipis aucta secretio respiration!, sed 
 aliud alio modo, inserviunt. Quae naturae institutio, ut in foetu organon 
 alterum alterius vices obtinere possit, pulcherrima et prsestantissima; 
 quo fit, ut foetus vita nondum autonomica, a noxiis quibuscunque 
 momentis, quae vim in ipsum habere possunt, tueatur conservetur- 
 que, donee ex asylo matris in lucem aeremque editus vim innatara 
 exerceat. 
 
 " Vena umbilicalis illo principio (oxygenio) gravida partim in hepar, 
 partim in venam cavam inferiorem sanguinem reducit a partibus 
 phlogisticis liberatum. Itaque vena cava inferior, postquam sanguinis 
 partem ex vena umbilicali et venis hepaticis excepit, praeter sanguinem 
 oxydatum, venosum quoque sanguinem ex corporis partibus reducem
 
 OF THE VARIKTIKS OF THE HUMAN SPECIES. 719 
 
 continet, cujus tamen pars satis magna, sanguis lienalis ac meseraicus, 
 in hepate jam carbone relicto, mera existit. Quoniam vero vena cava 
 inferior prima vitse foetalis parte magis in sinistrum quam in dextrum 
 cordis atrium aperitur, sanguis autem venae cavse superioris, nil minus 
 quam oxygenium ducens ex dextro cordis atrio per arteriam pulmona- 
 lem, hinc per ductum Botallicum, demum, postquam jam arteriee su- 
 periorum partium ex aorta excreverunt, in ipsam perfunditur ; sequi- 
 tur caput atque extremitates superiores sanguinem magis oxydatum, 
 seu, si mavis, dephlogisticatum, in atrio sinistro ventriculoque conges- 
 tum, accipere ; aortam vero descendentem sanguinem ex vena cava 
 superior! phlogisticum nee oxydatum in abdomen atque extremitates 
 inferiores perducere, quo fit, ut superiores corporis partes, exceptis pul- 
 monibus, qni sanguinem ex vena cava superiori venientem venosum acci- 
 piunt, primo graviditatis tempore magis vigeant polleantque." P. 215. 
 
 " Placenta oxygenium afferente, hepate carbonium submovente, 
 quse functiones in adulto in uno pulmone conjunctae sunt."* P. 216. 
 
 M. Geoffrey St. Hilaire, proceeding on the principle that there 
 cannot be organisation without the combination of a nutritious fluid, 
 nor yet assimilation without oxygenation or previous respiration, en- 
 deavours to shew : 1st, That a respirable gas is present in the amniotic 
 fluid, as shewn by the experiments of MM. Chevreuil and Lassaigne ; 
 2d, That the foetus, by means of its pores, as by so many tnacheas, in 
 the same manner as aquatic insects, is enabled to consume the air con- 
 tained in the surrounding fluid, owing to the air being thus brought in 
 contact with the venous bjood which fills the capillaries of the skin ; 
 3d, That the contraction of the womb and of the abdominal muscles 
 keeps up a certain degree of pressure, which is as requisite to the per- 
 fect performance of this process as to the ordinary act of respiration, f '' 
 
 OF THE VARIETIES OF THE HUMAN SPECIES. 
 (NOTES P P. See p. 513.) 
 
 Buffon, Blumenbach, Prichard, Gavoty and Touluzan, Cuvier, and 
 others, have proposed classifications of the varieties of the human 
 species : of these we prefer that of Cuvier. The following is an outline 
 of it : 
 
 1st, The fair, or Caucasian variety; 2d, the yellow, or Mongolian; 
 3d, the negro, or Ethiopian. 
 
 1st, CAUCASIAN. Characters. The beautiful form of the head, the 
 variable shades of complexion, and colour of the hair. 
 
 Principal Branches. 1. The Syrian, whence have proceeded the 
 
 * Joannis Mueller de Respiratione Foetus Commentatio Physiologica, in Aca- 
 demia Borussica Rhenana preemio ornata. Lipsite, 1823. P. 159. 
 f Rev. Mtd. Dec. 1823.
 
 720 APPENDIX. 
 
 Assyrians, the Chaldeans, the Arabs, Phoenicians, Jews, the Abys- 
 sinians, Arabian colonies, and ancient Egyptians. 2. The Indian, 
 German, or Pelasgic branch was early subdivided into the Sanscrit, the 
 Pelasgi, the Teutonic, and Slavonian. 3. The Scythian or Tartarian 
 branch. 
 
 2d, MONGOLIAN. Characters. Prominent cheek-bones; flat 
 visage ; narrow and oblique eyes ; straight and black hair ; scanty 
 beard, and olive complexion. Its civilisation has always remained 
 stationary. 
 
 3d, The NEGRO. Characters. -^Black complexion ; woolly hair; 
 compressed cranium, and flattish nose. 
 
 " It is very difficult to refer the Malays, or the Papuas, to any 
 one of the three great varieties of mankind already described. It is a 
 question, however, whether the former people can be accurately distin- 
 guished from their neighbours on either side ; the Caucasian Hindoos 
 on the one, and the Mongolian Chinese on the other. 
 
 " The Americans themselves have not yet been properly referred to 
 either of the other races, nor have they characters precise and constant 
 enough to constitute a fourth variety. Their copper-coloured com- 
 plexion is not sufficient. The black lank hair and scanty beard would 
 seem to approximate them to the Mongoles, if their well-defined fea- 
 tures and prominent noses did not oppose such a classification : their 
 languages are likewise as innumerable as their tribes, and no mutual 
 analogy has yet been ascertained between them, nor any affinity with 
 the dialects of the ancient world." * 
 
 We are inclined to infer that America was peopled by the Mongoles 
 from Asia; and that, subsequently, it had been visited by Phoenician 
 navigators, the greater part of whom settled in it, particularly in 
 Mexico ; and that the imperfect navigation of that era prevented many 
 of the adventurers, if not all of them, from returning. 
 
 OF THE MORTALITY OF FEMALES AT THE CHANGE OF LIFE. 
 (NoTEQQ. See j). 522.) 
 
 From the bills of mortality of both sexes, collected in Provence, 
 Switzerland, Paris, Berlin, Sweden, and Petersburgh, it would seem, 
 1st, that from 30 to 70, no other increase takes place in the mortality 
 of females than what naturally results from the progress of age; 2d, 
 that at all periods of the life of man, from 30 to 70, a greater mor- 
 tality occurs than in women, but especially from 40 to 50.f 
 
 " Griffith's Trans, of the Rtgne Animal. 
 
 f M. B6noiston de Chateauneuf on the Mortality of Females from 40 to 50 years 
 of age. Paris, 1822.
 
 APPENDIX, No. II. 
 
 CHEMICAL CONSTITUTION OF THE SOLIDS AND FLUIDS OF 
 THE HUMAN BODY. 
 
 I. SIMPLE SUBSTANCES ENTERING INTO THE CONSTITUTION 
 OF THE DIFFERENT ANIMAL PRINCIPLES OR CONSTITUENTS OF 
 THE HUMAN BODY. 
 
 The following simple substances are variously combined, in order 
 to produce the constituent parts of the body: 
 
 1 Azote. 6 Lime. 11 Magnesia (Magnesium). 
 
 2 Carbon. 7 Sulphur. 12 Silica. 
 
 3 Hydrogen. 8 Soda (Sodium). 13 Iron. 
 
 4 Oxygen. 9 Potass (Potassium). 14 Manganese. 
 
 5 Phosphorus. 10 Muriatic Acid. 
 
 Of these, magnesia and silica may be considered as foreign bodies, 
 they being seldom found, and in exceeding small quantities. The 
 principal elementary ingredients are the first six : animal substances 
 may be considered as chiefly composed of them. The first four con- 
 stitute almost entirely the soft parts, and the other two form the basis 
 of the hard parts. 
 
 II. ANIMAL CONSTITUENTS OR PRINCIPLES. 
 
 I. GELATIN consists of carbon, 47*88 ; hydrogen, 27-20; oxygen, 
 27-20; azote, 17-00; or, of 15, 14, 6, 2 atoms respectively, con- 
 tained in skin, bone, tendons, &c. Test, Tannin. 
 
 II. ALBUMEN. Corrosive sublimate detects -j^ir P art ^ e we 'ght 
 of the water containing it. COMP. : Carbon, 52-883 ; oxygen, 23-872; 
 hydrogen, 7-540; azote, 15*705, in 100 parts. Dr. Prout found it to 
 consist of 15 atoms of carbon, 6 of oxygen, 14 hydrogen, 2 azote, ac- 
 cording to the analysis quoted. 
 
 III. FIBRIN varies in its species in the different classes of animals. 
 COMP.: Carbon, 53-360; oxygen, 19 685; hydrogen, 7-021; azote, 
 19-934. Consists of carb. 18 atoms, oxyg. 5, hydrog. 14, azote 3. 
 
 IV. COLOURING MATTER OF THE BLOOD. Berzelius found it 
 possessed of nearly the same properties as fibrin. It is soluble in water 
 at a low temperature, and in all the acids except the muriatic : contains 
 iron. * 
 
 * Berzelius, vol. iii. Med. Chirurg. Trans. 
 3 A
 
 722 
 
 APPENDIX. 
 
 V. UREA or NEPHRIN, soluble in water and in alcohol. Pre- 
 cipitated in pearly crystals by nitric acids and oxalic acid. Dis- 
 solved by a solution of potass or soda. Constituents according to 
 Dr. Prout: 
 
 Oxygen ....:.39-5~l 2 atoms Hydrogen 0-25 6-66 
 
 Azote 32-5 I 1 Carbon 0'75 20-00 
 
 Carbon 147 f 1 Oxygen 1-00 26-66 
 
 Hydrogen ...13-sJ 1 Azote 1*75 46-66 
 
 100 3-75 100 
 
 Gelatin is insoluble in cold water ? albumen is insoluble in hot, and 
 
 fibrin is insoluble in both cold and hot. 
 
 The constituents of these three bodies, and of nephrin, according to 
 
 the best analysis of them hitherto made, are as follow : 
 
 Carbon. Oxygen. Hydrogen. Azote. 
 
 Gelatin atoms 15 6 14 2 
 
 Albumen 17 6 13 2 
 
 Fibrin 18 5 14 3 
 
 Nephrin 1 1 2 1 
 
 The colouring- matter of the blood approaches albumen in many of 
 its properties ; but it seems entirely destitute of azote. 
 
 VI. Mucus. Insoluble in water, transparent when evaporated 
 to dryness, and, like gum, soluble in the acids. Not soluble in alcohol 
 or ether does not coagulate by heat nor is precipitated by cor- 
 rosive sublimate or by galls. Is precipitated by the acetates of lead, 
 and by nit. argenti. Found in the epidermis, in nails, feathers, &c.* 
 
 VII. OSMAZOME is, probably, only an altered state of fibrin. 
 Soluble in water and alcohol does not gelatinise. Precipitated by 
 nit. argenti, nit. hydrarg., and acet. and nit. of lead. 
 
 VIII. PICROMEL. Found principally in bile; resembles inspis- 
 sated bile in its appearance ; soluble in water and in alcohol : 
 
 5 atoms Carbon 3'75 54-53 
 
 1 Hydrogen 125 1-82 
 
 3 Oxygen 3-000 43-65. f 
 
 IX. SUGAR OF MILK, according to Berzelius, consists of oxygen, 
 53-359; carbon, 39-474 ; hydrogen, 7-1 67. t 
 
 Dr. Thomson gives the table of the atomic analysis as follows : 
 
 4 atoms Oxygen 4 48-4 
 
 5 Carbon 3'75 45-4 
 
 4 Hydrogen 0-50 6-2 
 
 8-25 100-0 
 
 " Bostock, in Nicholson's Journal, vol. xi. p. 251. 
 f Dr. Thomson, An. Ph. vol. xiv. p. 69. 
 % Annals of Philos. vol. v. p. 266.
 
 CONSTITUENTS OF BONE, &c. 
 
 723 
 
 X. OILS are fixed. Fat Cholesterine. The former is composed 
 of oxygen, hydrogen, and carbon. The latter, according to Saussure, 
 consists of 84-068 of carbon, 12-672 of hydrogen, and 3-914 of 
 oxygen ; and differs little from the other fixed animal oils, excepting 
 that it contains more carbon and less oxygen than they. 
 
 XI. ACIDS. The acids found constituting and ready formed m 
 animal bodies, are the following : 
 
 1 Phosphoric. 
 
 2 Sulphuric. 
 
 3 Muriatic. 
 
 4 Carbonic. 
 
 5 Benzoic. 
 
 6 Uric. 
 
 *7 Rosacic. 
 
 8 Amniotic. 
 
 9 Oxalic. 
 10 Formic. 
 
 11 Acetic. 
 
 12 Malic. 
 
 13 Lactic. 
 
 14 Silica. 
 
 It may be remarked, that the whole of the soft parts of animals 
 consists chiefly of albumen, fibrin, and oils; and the hard parts of 
 phosphate of lime. The other animal principles are only in small 
 quantities, and in particular textures. The oils seldom enter into the 
 structure of the organs of animals ; they serve rather to lubricate the 
 different parts, and to fill up interstices. 
 
 III. INDIVIDUAL TEXTURES AND FLUIDS OF THE HUMAN 
 BODY (FORMED OF TWO OR MORE OF THE FOREGOING CON- 
 STITUENTS). 
 
 The Constituents of the BONES and TEETH of some of the Mammalia, 
 according to the Analyses of Berzelius and other Chemists. 
 
 
 iii 
 
 II 
 
 | 
 
 I 
 
 i 
 
 1 
 
 Substances analysed. 
 
 fill 
 
 M 
 
 Is 
 
 s 
 
 % 
 
 1 
 
 g 
 s 
 
 fi 
 
 
 - JHtw fl) 
 
 e 
 
 Si 
 
 G* 
 
 1 
 
 
 
 
 ^1 
 
 II 
 
 1 
 
 
 
 E 
 
 * 
 
 Human bones recently dried 
 
 33-3 
 
 1-2 
 
 11-3 
 
 51-4 
 
 2- 
 
 1-16 
 
 Bullock's bones recently dried . . 
 
 33-3 
 
 2-45 
 
 3-85 
 
 55-45 
 
 2-9 
 
 2-05 
 
 Osseous parts of human teeth . . 
 
 28-0 
 
 1-4 
 
 5-3 
 
 61-95 
 
 2-1 
 
 1-25 
 
 Osseous parts of bullock's teeth. . 
 
 31-0 
 
 2-4 
 
 1-38 
 
 57-46 
 
 5-69 
 
 2-07 
 
 The enamel of human teeth 
 
 2-0 
 
 
 8-0 
 
 85-3 
 
 3-2 
 
 1-5 
 
 The enamel of bullock's teeth . . 
 
 3-56 
 
 1-4 
 
 7-1 
 
 81-0 
 
 4-2 
 
 3-0 
 
 Forms the lateritious sediment in fevers, &c.
 
 724 
 
 The compact and cellular substances of human bones are, according 
 to Berzelius, of the same composition. 
 
 
 
 s 
 
 i 
 
 *, 
 
 8 
 
 i 
 
 
 Substances submitted 
 . to analysis. 
 
 1 
 
 S3 
 
 
 
 Iphateofl 
 
 ji 
 
 Carbonate 
 lime. 
 
 i 
 
 i 
 
 
 
 
 
 3 
 
 
 
 w 
 
 
 
 
 
 
 
 
 
 Vauquelin 
 
 Recent bullock's bones... 
 
 51-0 
 
 1-3 
 
 
 37-7 
 
 10-0 
 
 
 and 
 
 
 
 
 
 
 
 
 Fourcroy. 
 
 
 
 
 a 
 
 
 
 
 
 A child's first teeth 
 
 20-0 
 
 
 
 62-0 
 
 6-0 
 
 12 
 
 
 Teeth of an adult 
 
 20*0 
 
 
 
 64-0 
 
 6-0 
 
 10 
 
 
 
 
 
 
 
 
 
 Pepys. 
 
 The roots of the teeth ... 
 
 28-0 
 
 
 
 58-0 
 
 4-0 
 
 10 
 
 
 The enamel of teeth 
 
 
 
 ... 
 
 78-0 
 
 6-0 
 
 16 
 
 
 The spine softened by \ 
 disease f 
 
 79-75 
 
 0-82 
 
 4-7 
 
 13-6 
 
 1-13 
 
 
 Bostock. 
 
 Fourcroy and Vauquelin could not discover the fluate of calcium 
 either in the enamel of the teeth or in recent ivory. 
 
 Boiling water extracts slowly the cartilage of bone in the form of 
 gelatin. Cold hydrochloric acid dissolves the salts which have lime 
 for their base, leaving nearly altogether untouched the whole of the 
 cartilage. Ammonia precipitates the phosphate of lime from its solu- 
 tion in warm hydrochloric acid ; the phosphate of lime, however, thus 
 obtained, is accompanied with a considerable proportion of gelatin. 
 Bones submitted to dry distillation, give gelatin, and, as a residue, the 
 carbon of bones, which is a compound of animal charcoal and the salts, 
 with potash for their base : exposed to the air, the charcoal of bones 
 passes into the state of ashes. 
 
 Tophus, found in the articulations of the arm, consists of animal 
 matter, with traces of adipocire, 56-2 ; carbonate, phosphate, and 
 hydrochlorate of potash, 3*2 ; carbonate of lime, with traces of the 
 carbonate of magnesia, 12-5 ; phosphate of lime, 28-1. Another spe- 
 cimen contained animal matter, with unctuous and fatty matter, and a 
 little soda, 73-0; carbonate of lime, 10; phosphate of lime, 17.* 
 
 John, En-its < 'him. torn. v. p. 104.
 
 CONSTITUENTS OF SYNOVIA, &C. 725 
 
 The concretions found in persons subject to the gout are composed 
 of the urate of ammonia. * 
 
 The marrow of bones. The medulla of the cylindrical bones of 
 the bullock contain, membranes and vessels, 1 ; fat, 96 ; a reddish 
 serum, 3. 
 
 The medulla of the lower part of the radius, and of the tibia, 
 contains a very liquid fat, and neither coloured vessels nor membranes; 
 
 The diploe of the extremities of the long bones contain fatty matter 
 and a reddish serum, in very variable proportions. 
 
 The vertebrae of the dorsal column contain a deep brown serum, 
 partly concrete, soluble in water, and rarely a trace of fat.f 
 
 The cartilages dissolve in water kept for a considerable time at the 
 boiling point, and form a jelly. 
 
 The SYNOVIA of the human subject consists of a yellowish fat, 
 albumen, which constitutes its chief ingredient, an uncoagulable animal 
 matter, soda, chlorate of potassium and of sodium; and the ashes fur- 
 nish carbonate and phosphate of lime.}: 
 
 The synovia of the articulations of the knees of a man was found 
 to consist of a flocculent substance, which coagulated at the tem- 
 perature of boiling water, and was precipitated by the chlorate of 
 mercury.^ 
 
 Gout appears to change, in some degree, the secretion in the 
 joints affected. Dr. Wollaston, Dr. Pearson, and Mr. Tennant, found 
 the chalk-stones formed in this disease composed of urate of soda. 
 Fourcroy has confirmed this analysis; he therefore conjectures that 
 synovia contains uric acid.|| 
 
 Synovia of a horse. A. From an articulation which was in a 
 healthy state: soluble albumen, 6-4; animal matter, which did not 
 become concrete with the carbonate and the hydrochlorate of soda, 
 0'6 ; phosphate of lime, 0'15; traces of an ammoniacal salt, and of 
 phosphate of soda; water, 9'28. B. From a joint anchylosed in con- 
 sequence of a wound : insoluble, fibrous albumen ; soluble albumen ; 
 free phosphoric acid ; the same salts as mentioned above. IF 
 
 Synovia of an elephant. Reddish, filamentous, of a slightly saline 
 and insipid taste ; when warmed or heated by mineral acids it coagu- 
 lated. It contained a soluble albumen of animal matter precipitated 
 by tannin, and which did not become concrete in a small quantity ; 
 soda and hydrochlorate of potash.** 
 
 . * Wollaston. f Berzelius, Nouv. Journ. de Gehl. torn. ii. p. 287. 
 
 $ Lassaigne and Boissel, Journ. de Pharm. torn. viii. p. 306. 
 Bostock. || Fourcroy, torn. ix. p. 224. 
 
 J[ John, Ecrits China, torn. vi. p. 146. 
 ** Vauqueliu, Ann. de Chim. et de Phys. vi. p. 399.
 
 726 APPENDIX. 
 
 The periosteum approaches the chemical properties of cartilage, 
 and yields a small proportion of gelatin. 
 
 The ligaments resist for a very long time the action of boiling 
 water, but dissolve at last, in part, like gelatin. 
 
 The membranes, as the serous (the pia-mater, arachnoid, pericar- 
 dium, pleura, peritonaeum, &c.) and the skin, dissolve in boiling water, 
 and pass to the state of gelatin. 
 
 INTEGUMENT. Cutis vera formed of fibres interwoven like a felt. 
 It yields little gelatin on maceration in cold water ; by long boiling 
 in water it becomes gelatinous, and dissolves completely, and by evapo- 
 ration it becomes glue. Hence it appears to be a peculiar modifica- 
 tion of gelatin. By tannin, and the extractive of oak-bark com- 
 bining with it, leather is formed. 
 
 Rete mucosum " is a mucous membrane, situated between the 
 cutis vera and the epidermis. The black colour of negroes is said to 
 depend upon a black pigment situated in this substance ; but it seems 
 to us to be situated in the inner or flocculent surface of the epidermis. 
 Chlorine deprives it of its black colour, and renders it yellow. A negro, 
 by keeping his foot for some time in water impregnated with that gas, 
 deprived it of its colour, and rendered it nearly white ; but in a few 
 days the black colour returned again with its former intensity.* This 
 experiment was first made by Dr. Beddoes on the fingers of anegro."t 
 
 The epidermis possesses the same properties as horn. The inter- 
 nal surface of the epidermis seems to be the seat of the black colour of 
 the negro, and not the rete mucosum. The human epidermis consists 
 of fatty matter, 0'5 ; animal matters soluble in water, 5-0 ; concrete 
 albumen, 93 to 95 ; lactic acid, lactate, phosphate, and hydrochlorate of 
 potash, sulphate, and phosphate of lime, an ammoniacal salt, and 
 traces of iron, l.J The nails of the fingers and toes present an 
 analogous constitution. 
 
 HUMAN HAIR may be regarded as fine tubes of a substance similar 
 in all its properties to horn, covered by a white adipocire, (probably 
 furnished by the sebaceous glands of the scalp, and filled with an 
 oily matter, which is either of a greenish black colour, red, yellow, or 
 nearly colourless, according as the hair is black, red, yellow, or white. 
 The ashes of human hair is composed of the hydrochlorate of soda ; 
 of the carbonate, sulphate, and phosphate of lime, (and the phosphate 
 of magnesia in that which is white) a considerable portion of silica, 
 oxide of iron in a very marked proportion in black hair, but scarcely 
 to be recognised in that which is white ; and a very small quantity of 
 the oxide of manganese. 
 
 * Fourcroy, torn. ix. p. 259. -f- Beddoes on Factitious Airs, p. 45. 
 
 J John, Ecrits Chim. torn. vi. p. 92.
 
 -CONSTITUENTS OF MUSCI/K, BRAIN, NERVE, &C. 727 
 
 The sulphur, which is undoubtedly combined in the organisation of 
 the corneous or horny substance, is found more abundantly in the red 
 and light-coloured hair than in the black. 
 
 The MUSCULAR FLESH. The muscular substance is probably 
 composed of very little more than fibrin, traversed by cellular tissue 
 containing fat, by the aponeuroses and tendons, by vessels containing 
 blood, by lymphatics containing lymph, and by nerves. It is, how- 
 ever, very probable that osmazome, lactic acid, the hydrochlorate and 
 phosphate of soda, and the phosphate of lime, particularly belong to 
 muscular flesh, although they are also found in the blood. Cold 
 water extracts of the muscular substance the red colouring matter of 
 the blood, the albumen, the osmazome, and the salts of the blood : 
 boiling water takes up the cellular tissue reduced to gelatin, and the 
 fat which swims on its surface ; the residuum consists of fibrin, a little 
 altered by the boiling, and which yields the phosphate of lime by 
 incineration. The muscular substance of beef gives, by incineration, 
 more lime than that of veal.* 
 
 According to Berzelius, the muscular texture contains fibrin, ves- 
 sels, and nerves, 15 - 8; cellular substance, 1 '9 ; albumen, 2-2 ; osma- 
 zome, with thelactate and hydrochlorate of soda, 1-8 ; mucous matter, 
 0-15; phosphate of soda, 0'9; phosphate of lime, containing a por- 
 tion of albumen, GO'S ; water and loss, 77-17. 
 
 Bullock's heart. Osmazome, 7'57; albumen and cruor, 2'76; 
 fibrin, with vessels, nerves, cellular tissue, fat, and phosphate of lime, 
 18' 19 ; an ammoniacal salt and a free acid, in an indeterminate quan- 
 tity; lactate of potash, 0-19; phosphate of potash, 0-15; chloruret 
 of potassium, 0-12 ; water, 77'04.f 
 
 An ossification found in the human heart. It contained a cartila- 
 ginous matter and phosphate of lime in nearly equal proportions, with 
 a little carbonate of lime.t 
 
 An ossification found in the veins of the human uterus. Mem- 
 branous substance and phosphate of lime, in nearly equal quantities, 
 with a little of the carbonate of lime and traces of the hydrochlorates. 
 
 BRAIN and NERVES. The hemispheres of the human brain : a 
 reddish-brown liquid fat, leaving phosphoric acid by combustion, 0'7 ; 
 a white fat, becoming blacker by fusion, and giving rise to much 
 phosphoric acid by combustion, 4.53 ; phosphorus contained in these 
 fatty substances, 1-5; osmazome, 1'12; albumen, 7- ; phosphate of 
 potash, muriate of soda, phosphate of lime, and phosphate of magne- 
 sia, 5-15; water, 80. 
 
 The human cerebellum gave the same results. 
 
 * Hatchett. f Braconnot, Ann. de Chim. et de Phys. xvii. p. 388. 
 
 J John, Ecrits Chim. torn. v. p. 159. Ibid. torn. v. p. 126.
 
 728 APPENDIX. 
 
 Medulla oblongata and spinal chord have the same constituent 
 principles, but they contain more of the fatty matter, and less albumen, 
 osmazome, and water. 
 
 The nerves of tlie human subject contain less of the liquid and 
 crystallisable kinds of fatty matter, but more of the fatty substance 
 which resembles adipocire, and much more albumen than the brain.* 
 
 The gray substance of the brain of a calf: albumen insoluble in 
 water, 1OO; an unctuous incrystallisable fat, osmazome, phosphate of 
 ammonia, phosphate of soda, phosphate of lime, phosphate of mag- 
 nesia, hydrochlorate of soda, and traces of iron, 15'0 to 10-0; water, 
 75 to 80. 
 
 The white substance of the brain of a calf contained more fatty 
 matter than the gray ; it presented traces of silica. The cerebellum 
 of the calf gave the same products as the cineritious substance. 
 
 The optic thalami, the medulla oblongata, spinal marrow, and the 
 nerves of the calf, gave results similar to those furnished by the white 
 substance of the brain, excepting that they contained more albumen, 
 and less water. 
 
 The brain of a bullock contained also phosphate of ammonia, a 
 more solid albumen, a reddish-coloured fat, and a crystallisable fat. 
 The composition of the brain of the stag was similar.f 
 
 The lymph found in the ventricles of the human brain : gelatin 
 (osmazome ?), 0-9 ; mucus (salivary matter ?), 0-3 ; albumen, 0-6 ; 
 hydrochlorate of soda, and a little of the phosphate of soda, 1-5; 
 water, 96-5 ; loss, 0-2.J 
 
 A soft concretion found encysted in the cerebral pulp of a subject 
 who was afflicted with mental alienation : white grease, 6 ; semi- 
 concrete albumen, 17*0; cartilaginous substance, insoluble in potash, 
 18-0; salts, with ammonia, potash, soda, and lime for their base, about 
 2-0; water, 57. 
 
 See 4he note at pp. 272 and 273, for the composition of the 
 humours and textures of the eye. The pigmentum nigrum is mixed 
 with mucus. 
 
 Mucus. The nasal mucus of the human subject contains: 
 mucus, 5'33 ; albumen and salivary matter, with a trace of phosphate 
 of soda, 0-35; osmazome, with lactate of soda, 0-3; soda, 0'09 ; 
 hydrochlorate of potash and of soda, 0*56; water, 93-37. || The 
 mucus of the trachea, according to Berzelius, is similar in its com- 
 position. 
 
 Vauquelin, Ann. de Chim. Ixxxi. p. 37. 
 
 f John, Ecrits Chim. torn. iv. p. 249 ; torn. v. p. 162. 
 
 J Haldat, Ann. de Chim. ex. p. 175. John, Ecrits Chim. torn. v. p. 102. 
 
 || Berzelius, Fourcroy, and Vauquelin.
 
 CONSTITUENTS OF THE SECRETIONS. 729 
 
 SALIVA has a strong affinity for oxygen, absorbs it readily 
 from the air, and gives it out again to other bodies. The human 
 saliva consists of salivary matter, 0'29; mucus, - 14; osmazome, 
 with lactate of soda, 0*09; soda, 0-02; hydrochlorate of potash and 
 hydrochlorate of soda, 0-17 ; water, 99-29.* 
 
 Salivary calculi are formed of a membranous substance, containing 
 phosphate of lime. 
 
 The tartar of the teeth. Mucus, 1-25; salivary matter, 1-0; 
 animal matter, soluble in hydrochloric acid, 7-5; phosphate of lime 
 and phosphate of magnesia, 7-90.f 
 
 The LACHRYMAL FLUID. Animal matter, soda, hydrochlorate 
 and phosphate of soda, and phosphate of lime, 1-0; water, 99-0. 
 The calculi of the lachrymal gland are formed of the phosphate of 
 lime.t 
 
 The GASTRIC JUICE. The gastric juice ejected by vomiting, 
 after fasting for some time, resembled, according to Montegre, the 
 saliva ; it contained flocculi of mucus, and underwent putrefaction as 
 rapidly as the saliva ; but sometimes it was acid, and then it did not 
 undergo putrefaction. 
 
 LYMPH. The liquor found in the thoracic duct of animals which 
 have not taken nourishment for twenty-hours, is as limpid as water, 
 does not affect the vegetable colours, and does not coagulate either by 
 heat or by acids ; it becomes slightly turbid from alcohol, leaves a very 
 small residuum when submitted to evaporation, and consequently 
 appears to centain but very little matter, and only a small quantity of 
 the hydrochlorate of soda. 
 
 The lymph of a horse taken from the thoracic duct towards the 
 inguinal region and meso-colon, was of a greenish yellow, translucid, 
 and concreted in twelve minutes into a clear gelatin ; the coagulum, 
 which hardly amounted to T , was similar to fibrin, the fluid con- 
 tained about 0-04 of albumen, muriate of soda, with a little soda and 
 phosphate of soda. 
 
 CHYLE. The chyle taken from the thoracic duct. of a dog, three 
 hours after a vegetable diet, resembled clear milk, and deposited a 
 reddish-white coagulum : this coagulum, which had the appearance of 
 fibrin, was to the serum at first in the proportion of 48 to 100; but 
 after being left longer to itself it increased considerably. The specific 
 weight of the serum was 1-018; it did not coagulate at the tem- 
 perature of boiling water, but became turbid; after some weeks it 
 became a little sour, without undergoing putrefaction : in 100 parts it 
 
 * Berzelius, Bostock, Thomson, John. 
 
 -) Berzelius. J Vauquelin. 
 
 8 RBUHS and Emmert, Journ. de Scherer, torn. v. p. 681.
 
 730 APPENDIX. 
 
 contained from 4-8 to 7-3 of solid matter, which consisted of 0'9 of 
 soluble albumen and salts ; it contained neither gelatine, nor phosphate 
 of lime, nor any ammoniacal salt. 
 
 The chyle of a dog, collected three hours after having eaten meat, 
 had the appearance of cream : its coagulum, a little red, was to the 
 serum at first as 46-5 to 100, but this quantity diminished gradually : 
 the serum became much more turbid by heat, and by the addition of 
 acids, than that produced from vegetable food ; it underwent putre- 
 faction in three days; it deposited, when allowed to stand, a white 
 and greasy cream, and furnished from 7 to 9-5 per cent of solid 
 matter, consisting of soluble albumen, without any gelatin. Brande 
 observed a substance analogous to the sugar of milk in the serum.* 
 
 Chyle, " when drawn from the thoracic duct, about five hours 
 after the animal has taken food, is an opaque liquid, of a white colour ; 
 without smell, and having a slightly acid taste, accompanied by a 
 perceptible sweetness. The presence of a free alkali is indicated. 
 About ten minutes after it is drawn from the animal it coagulates into 
 a stiff jelly, which in the course of twenty-four hours gradually 
 separates into two parts, producing a firm contracted coagulum, 
 surrounded by a colourless fluid." 
 
 1st. " The coagulum, as appears from the experiments of Vauquelin,f 
 is an intermediate substance between albumen and fibrin. He con- 
 siders it albumen on its way to assume the nature of fibrin. It is 
 not so stiff nor of so fibrous a texture as fibrin; it is more 
 easily acted on and dissolved by caustic alkalies ; it is insoluble in 
 alcohol and ether, readily dissolved by sulphuric acid, very dilute; 
 nitric acid converts it into adipocire. When burnt, it leaves a char- 
 coal containing common salt, phosphate of lime, and gives traces 
 of iron. "| 
 
 2d. The liquid portion separates albumen on boiling, and contains 
 sugar and a very small portion of a fatty matter, similar to that found 
 in brain. The same salts as in other animal fluids. 
 
 BLOOD. Taste slightly saline, smell peculiar, specific gravity 
 1-0527. As soon as the vital influence of the vessels ceases to act on 
 the blood, it separates into the coagulum or cruor, and serum. The 
 common proportion is one part of cruor to three of serum. The 
 proportion, however, varies from 1*2 to 1*4. If the separation of 
 fibrin, giving rise to the coagulation, takes place in repose, the fibrin 
 entangles the red particles of the blood ; but if the blood be kept in 
 motion, the red particles escape into the serum, and the fibrin is 
 separated into threads. 
 
 * Marcet, Vauquelin, Brande, &c. 
 
 f- Ann. de Cbim. xxxi. p. 113. % Thomson.
 
 CONSTITUENTS OF THE BLOOD, &c. 731 
 
 1st. Serum. Possesses the taste and smell of the blood ; specific 
 gravity is about -1-0287. 
 
 Berzelius found that the serum of human blood was composed as 
 follows: water, 905-00; albumen, 80-00; muriates of potash and 
 soda, 6-00 ; lactate of soda, with animal matter, 4-00 ; soda, phos- 
 phate of soda, with animal matter, 4-10; loss, 0-90=1000-00.* 
 
 " Dr. Marcet found the constituents of serum as follows: water, 
 900-00 ; albumen, 86-80 ; muriates of potash and soda, 6-60 ; muco- 
 extractive matter, 4-00; sub-carbonate of soda, 1-65; sulphate of 
 potash, 0-35; earthy phosphates, 0-60=1000."f 
 
 " The muco-extractive matter was, doubtless, impure lactate of 
 soda." " Berzelius is of opinion, that the sulphate of potash, and the 
 earthy phosphates which were found by Dr. Marcet in the ashes of 
 serum, were formed during the incineration; for phosphorus, sulphur, 
 and the basis of lime and magnesia, exist, according to him, as 
 constituents of albumen." 
 
 " Gelatin was considered as a constituent of serum until Dr. 
 Bostock and Professor Berzelius proved that the opinion of its ex- 
 istence in blood was not well founded." 
 
 2. The cruor, or the clot. Specific gravity about 1-245. Is 
 separated into two portions by ablution in water. 1st, a white, solid, 
 elastic substance, which has all the properties of fibrin ; 2d, the 
 portion held in solution by the water is the colouring matter, with a 
 portion of serum. 
 
 " Berzelius and Brande have shewn that this clot is a compound 
 of fibrin, albumen, and colouring matter of blood. According to the 
 analysis of Berzelius, it consists of colouring matter, 64 ; fibrin and 
 albumen, 36= 100." 
 
 " When the colouring matter is incinerated, about one-third of a 
 per cent of oxide of iron may be extracted from its ashes. This 
 portion of iron is a constituent of the colouring matter, and perhaps 
 the cause of its red colour.! But in what way it is united to the 
 albuminous portion of the colouring matter, remains unknown. When 
 incinerated, the colouring matter leaves -g^th of its weight of ashes, 
 consisting, according to the analysis of Berzelius (which appears to be 
 the most to be depended on), of the following ingredients : oxide of 
 iron, 50-0; sub-phosphate of iron, 7-5; phosphate of lime, with traces 
 of magnesia, 6'0; pure lime, 20-0; carbonic acid and loss, 16-5= 
 100-0."- 
 
 Berzelius is of opinion that none of these bodies existed in the 
 
 * Annals of Philosophy, vol. ii. p. 202. 
 
 f Medico. -Chirurg. Soc. Trans, vol. ii. p. 376. Thorn, vol. iv. p. 492.
 
 732 APPENDIX. 
 
 colouring matter; but merely their bases, iron, phosphorus, calcium, 
 &c. ; and that they are formed during the incineration. 
 
 " The albumen of blood leaves the same quantity of ashes as the 
 colouring matter ; but these ashes contain no traces of iron." 
 
 " Dr. Gordon has made it appear probable, that during the coagu- 
 lation of blood a little heat is evolved."* 
 
 Rouelle has obtained nearly the same ingredients, only in different 
 proportions, from the blood of a great variety of animals. 
 
 Festal blood. " Fourcroy made some experiments on the blood of 
 the foetus. He found that it differed from the blood of the adult in 
 three things: 1st, Its colouring matter is darker, and seems to be 
 more abundant. 2d, It contains no fibrin, but probably a greater 
 proportion of gelatin (?) than blood of adults. 3d, It contains no 
 phosphoric acid."f 
 
 Diseased blood. 1st. " Deyeux and ParmentierJ: ascertained 
 that the buffy coat consists of the fibrin. The cruor, deprived of this 
 substance, is much softer than usual; and almost totally soluble in 
 water. 
 
 2. " The blood drawn from several patients labouring under sea 
 scurvy, afforded scarcely any remarkable properties to these chemists, 
 except a peculiar smell, and an albumen which was not so easily 
 coagulated as usual." 
 
 3. The blood of patients in putrid fevers gave no sensible alteration 
 in its properties to the examinations of these chemists. 
 
 4. " The blood of diabetic patients : the serum of the blood, 
 according to the experiments of Dobson and Rollo, assumes the 
 appearance of whey. Dr. Wollaston has shewn that it contains 
 no perceptible quantity of sugar, even when the urine is loaded 
 with it." 
 
 MILK separates into cream, curd, and whey. 1st, Cream is 
 composed of a peculiar oil, curd, and serum. Cream of the specific 
 gravity of 1-0244, was analysed by Berzelius, who found it composed 
 of butter, 4-5; cheese, 3-5; whey, 92-0=100-0. 
 
 2d. Curd may be precipitated by rennet, or the acids: alkalies 
 dissolve it easily. The constituents of curd, according to the 
 analysis of Gay Lusac and Thenard, are as follows : 
 
 Carbon 59-781 
 
 Oxygen 11-409 
 
 Hydrogen J-429 
 
 Azote.. 21-381 = 100-000 
 
 * Annals of Philosophy, vol. iv. p. 139. 
 } Four., Ann. de Chim. torn. vii. p. 162. 
 Juurn. de Phys. torn. xliv. p. 454.
 
 CONSTITUENTS OF MILK, &C. 733 
 
 Dr. Thomson's application of this analysis to the atomic theory. 
 
 1 atoms Carbon 5-25 60-87 f By doubling the 1 14 atoms Carbon 10'5 
 
 1 Oxygen 1-00 11-60 number of atoms, I 2 Oxygen 2-0 
 5 _ Hydro. 0-625 7'24 J it may be compared 1 10 Hydrog. 1-25 
 
 1 _ Azote 1-75 20-29 1 with gelatin, albu- | 2 Azote 3-5 
 
 I men, and fibrin. I 
 
 8-625 100-00 I J 28 l?-25 
 
 Proust has found in cheese an acid, which he calls the cascic acid, 
 to which he ascribes several of the peculiar properties of cheese.* 
 
 The coagulation of curd probably depends upon the same cause as 
 that of albumen. 
 
 3. Whey still possesses some curd: on evaporation it deposits 
 crystals of sugar of milk. Towards the end of the evaporation, some 
 crystals of muriate of potash and of muriate of soda make their 
 appearance. f According to Scheele it contains also a little phosphate 
 of lime.t Fourcroy and Vanquelin, Thenard, Bouillon, la Grange, and 
 Berzelius, have analysed whey. The latter chemist gives the following 
 as the ingredients of milk deprived of its cream : 
 
 *i : ' . 
 
 Water 928-75 
 
 Curd, with a little cream .... 28-00 
 
 Sugar of milk 35-00 
 
 Muriate of potash 1'70 Milk may ^ made to afforda liqn ^. 
 
 Phosphate of potash 0-25 resemb i ing wine or beer, from which 
 
 Lactic acid, acetate of potash,) alcohol may be separated by distillation. 
 
 witH a trace of lactate of iron / The Tartars obtained all their spirituous 
 
 Earthy phosphates 0-30 li qu0 rs from mare's milk. 
 
 1000-00 
 
 It has been ascertained that milk is incapable of being converted 
 into wine till it has become sour ; after this, nothing is necessary but 
 to place it in the proper temperature ; the fermentation begins of its 
 own accord, and continues till the formation of wine be completed. 
 A great quantity of carbonic acid is extricated during the fermentation 
 of milk. || Milk is fermented and kfcpt for many months, or even years, 
 in the Orkney and Shetland Islands ; but, along with a small portion of 
 alcohol which is formed, the acidity is considerable. 
 
 The ingredients of the milk of most animals are nearly the same; 
 the proportion only differs. 
 
 The human milk differs from cow's milk 1st, in containing a 
 much smaller quantity of curd ; 2d, its oil is so intimately combined 
 
 * Journ. de Phys. Ixiv. p. 107- 
 
 f Parmentier, Journ. de Phys. xxxviii. p. 417- $ Scheele, vol. ii. p. 61. 
 
 Parmentier, Journ. de Phys. xxxviii. p. 365. || Scheele, vol. ii. p. 66.
 
 734 >X%f APPENDIX. 
 
 4' '--- 
 
 with its curd^lhat it does not yield bolter ; 3d, it contains rather more 
 sugar of milk. 
 
 Parroentier and Deyeux ascertained, that the quantity of curd in 
 woman's milk increases in proportion to 'the time after delivery.* 
 
 None, of the methods by which cow's milk is coagulated succeed in 
 producing the coagulation of the human milk.f 
 
 BILE (human). The following is the analysis of bile, according to 
 Berzelius: water, 908-4; picromel, 80-0; albumen, 3-0; soda, 4-1 ; 
 phosphate of lime, O'l; common salt, 3-4; phosphate of soda, with 
 some lime, 1-0 = 1000. 
 
 Biliafy calculi are formed either entirely of cholesteriue, or they 
 also contain a yellow concrete mucus, picromel, and rarely phosphate 
 of lime or carbonate of lime. These latter ingredients frequently almost 
 entirely replace the cholesterine.J 
 
 CERUMEN OF THE EAR. Vauquelin considers it composed of the 
 following substances. 1st, Albumen. 2d, An inspissated oil. 3d, A 
 colouring matter: 4th, Soda. 5th, Phosphate of lime. 
 
 TEARS. According to the analysis of Fourcroy and Vauquelin, || 
 they are composed 'of the following ingredients: 1st, Water. 2d, 
 Mucus. 3d, Muriate of soda. 4th, Soda. 5th, Phosphate of lime. 
 6th, Phosphate of soda. 
 
 " The saline parts amount only to about 0-01 of the whole. The 
 mucus contained in the tears has the property of absorbing oxygen 
 gradually from the atmosphere, and of becoming thick and viscid, and 
 of a yellow colour. This property of acquiring new qualities from the 
 absorption of oxygen, explains the changes which take place in tears in 
 some diseases of the eye." 
 
 SWEAT contains salivary mucus, osmazome, lactic acid, lactate of 
 soda, and hydrochlorate of potass and soda.lF 
 
 Thenard found it composed of an animal substance analogous to 
 gelatin, acetic acid, hydrochlorate of soda, phosphate of lime, phos- 
 phate of iron, and water. 
 
 According to Dr. Anselmino,** the sweat consists of 0'02 of cal- 
 careous salts; 0-21 of animal matter with the sulphates; 0'48 of 
 osmazome, and the chlorurets of soda and of lime ; and of - 29 parts of 
 osmazome, combined with the acetates and free acetic acid. 
 
 URINE. The human urine, in a state of health, has a specific 
 gravity of 1-02. It contains urea, 3'01 ; a matter analogous to saliva, 
 osmazome, lactic acid, lactate of ammonia, and a little urea, 1 '724 ; 
 
 Journ. de Phys. torn, xxxviii. p. 422. f Clarke, Irish Trans, vol. ii. p. 175. 
 
 J Gren. Orfila. Fourcroy, torn. ix. p. 3?3. 
 
 || Journ. de Phys. torn, xxxix. p. 236. ^[ Berzelius. 
 
 ** Zeitschriftfiir die Physiologic von Fr. Tiedemann, $c. torn. xi. 2d cah. 1827-
 
 CONSTITUENTS OF VARIOUS SECRETIONS. 735 
 
 mucus, 0-032; uric acid, 0-10; phosphate of ammonia, 0-150; sul- 
 phate of potassa, 0-371 : sulphate of soda, 0-316; hydrochlorate of 
 soda, 0'445 ; phosphate of soda, 0-294; phosphate of lime, with a little 
 phosphate of magnesia, and a trace of the fluate of calcium, 0-1 ; silica, 
 0-003; water, 93-3.* 
 
 Besides the constituents of healthy urine, as determined by Ber- 
 zelius, the following have been occasionally detected in it: albumen, 
 resin with ulmine, acetic acid, benzoic acid (in infants), carbonic acid, 
 sulphur, chloruret of potassium, and iron. 
 
 Urine which is excreted in the morning generally contains more of 
 the saline and solid ingredients. Uric acid abounds most in the urine 
 of individuals who live on animal diet. Urine absorbs oxygen from 
 the atmosphere, and passes into a state of putrid fermentation. This 
 is more or less rapid according to the elevation of the temperature; 
 and the quantity of mucus and albumen present in the urine is con- 
 siderable. 
 
 The urine in diabetes mellitus has a specific gravity of from 1-026 to 
 1-05. It generally contains no urea sometimes a minute quantity of 
 it. It is remarkable for its quantity, and for the saccharine matter 
 which it holds in solution ; the saline ingredients are generally present, 
 but in smaller proportions. As the quantity of sugar diminishes, that 
 of albumen increases, and this latter is replaced, as the disease dis- 
 appears, by urea and uric acid. The chief difference between this urine 
 and that secreted in diabetes insipidus, consists in the absence of sac- 
 charine matter from the latter. 
 
 Icteric urine is frequently yellow and bitter, and contains the prin- 
 ciples of bile. 
 
 In acute dropsy the urine is generally charged with albumen. When 
 dropsy results from disease of the liver, the urine is brown, and deposits 
 a brown sediment. 
 
 SEMEN, when ejected, is the product of two different glands, the 
 one fluid and milky, supposed to be secreted by the prostate gland ; 
 the other a thick mucilaginous substance, considered to be secreted by 
 the testes, and in which numerous white shining filaments may be dis- 
 covered : it has a slightly disagreeable odour, an acrid, irritating taste, 
 and is of a greater specific gravity than water. As this liquid cools, 
 the mucilaginous parts become transparent, and acquire a greater con- 
 sistency ; but in about twenty minutes after its emission the whole 
 becomes perfectly liquid. 
 
 This change supervenes without any absorption of moisture from the 
 air, and without its action, taking place equally in close vessels. Semen 
 is insoluble in water before this spontaneous liquefaction, but readily so 
 
 * Berzelius.
 
 736 API'KXDIX. 
 
 afterwards.* When semen is kept in a moist air, at about 77% it 
 acquires a yellow colour, like the yolk of an egg ; it exhales the odour 
 of putrid fish, and its surface is covered by the byssus septica. Ac- 
 cording to Vauquelin, semen is composed -of water, 90 ; mucilage, 6 ; 
 phosphate of lime, 3; soda, 1 = 100. 
 
 The OVA. from the ovaria of the human subject : gelatin, albumen, 
 phosphate with an alkaline base in excess. t 
 
 AMNIOTIC FLUID, which surrounds the foetus, in the human species 
 is of a slightly milky colour, owing to a curdy matter suspended in it, 
 of a weak, pleasant odour, and saltish taste ; specific gravity 1-005 ; is 
 composed of water, about 98-8 ; albumen, muriate of soda, soda, 
 phosphate of lime, lime, 1-2 = lOO'O. J A curdy-like matter is depo- 
 sited on the surface of the foetus, evidently from the liquor of the am- 
 nios. Vauquelin and Buniva have shewn that it is different from any 
 thing contained in this fluid ; and that it has in its chemical relations a 
 great resemblance to fat. They conjecture that it is formed from the 
 albumen of this liquid, which has undergone some unknown changes. 
 It appears to be of service in preserving the skin of the foetus from 
 being acted on by the liquor of the amnios, and to facilitate its passage 
 in parturition. 
 
 Pus. Its taste is insipid, and it has no smell when cold. Before 
 the microscope it exhibits the appearance of white globules swimming 
 in a transparent fluid; specific gravity from 1-031 to 1-033. When in- 
 cinerated, the ashes give traces of iron. || It produces no change on 
 vegetable blues. Alcohol thickens pus, but does not dissolve it ; nor 
 does it unite with oils. Soluble in sulphuric acid, but separated on 
 the addition of water. The same is the case with nitric acid. Mu- 
 riatic acid also dissolves it when heated, and it is again separated by 
 water. 
 
 The fixed alkaline leys form with it a whitish, ropy fluid, which is 
 decomposed by water, the pus being precipitated. Corrosive sublimate, 
 nitrate of mercury, and nitrate of silver, give a whitish precipitate from 
 its solution, indicating an analogy with albumen. 
 
 Expectorated matter yields traces of sulphur, and perhaps also of 
 phosphorus; and it contains the following saline substances: 1st, 
 Muriate of soda, varying from 1^ to 2^ in the 1000 of expectorated 
 matter. 2d, Phosphate of lime, half a part in the 1000. 3d, Am- 
 monia, united probably to phosphoric acid. 4th, A phosphate, probably 
 of magnesia. 5th, Carbonate of lime. 6th, A sulphate. 7th, Vitri- 
 
 * Vauquelin, Ann. de Chim. ix. p. 70. 
 
 f John's Chemical Writings, vol. vi. p. 158. 
 
 J Vauquelin and Buniva, Ann. de Chim. xxxiii. pp. 270, 274. 
 
 || Gren's Handbuck, torn. ii. p. 426.
 
 CONSTITUENTS OF F.ECES, &C. 
 
 737 
 
 fiable matter, probably silica. 8th, Oxide, of iron. The whole of 
 these last six substances scarcely amount to one part in the 1000 of 
 expectorated matter. 
 
 The proportion of saline matter and of albumen present in expec- 
 torated matter varies much in different circumstances. The thicker it 
 is, in general the smaller is the quantity of the saline matter; whereas, 
 when very thin it is often impregnated with salts, especially with the 
 muriate of soda, to a great degree, and tastes distinctly salt and hot. 
 
 Liquor of the pericardium. Dr. Bostock * considers it to be com- 
 posed of water, 92-0; albumen, 5-5; mucus, 2-0; muriate of soda, 
 0-5=100-0. 
 
 Liquor of dropsy. Dr. Bostock found the liquid formed in " spina 
 bifida" to be composed as follows : water, 97-8 ; muriate of soda, 1-0 ; 
 albumen, 0-5 ; mucus, 0'5 ; gelatin, 0'2 ; lime, a trace, t 
 
 The same kind of fluid obtained from the head of a child of ten 
 years was examined by Dr. Prout. It faintly reddened litmus paper. 
 Its constituents were as follow : water, 987-18 ; albumen, precipitated 
 by nitric acid and heat, 1-66 ; substances soluble in alcohol, (fatty 
 adipocirous matter, lactate of soda,) 1-65 ; substances soluble in water, 
 9-51 viz. muriates of potash and soda, 6 % 80 ; sulphate of soda, and 
 some animal matter not coagulated by heat, 2-71 = 1000-00.1 
 
 Liquor of blisters. The analysis of Macqueron gives it nearly the 
 same constituents as the serum of the blood: from 200 parts he 
 obtained albumen, 36; muriate of soda, 4; carbonate of soda, 2 ; 
 phosphate of lime, 2 ; water, 156=200. 
 
 HUMAN FAECES. Their colour seems to depend upon the bile 
 mixed with the food in the digestive canal : when too Irght, it is sup- 
 posed to denote a deficiency of bile ; when too dark, there is thought 
 to be a redundancy of that secretion. The following table shews the 
 analysis of Berzelius: 1| 
 
 Water ?3'3 
 
 Vegetable and animal remains .... ^0 
 
 Bile 0-9 
 
 Albumen 0'9 
 
 Peculiar and extractive matter, -j 
 
 supposed to be formed from I 2 7 
 
 picromel J 
 
 Salts (a) 1-2 
 
 Slimy matter, consisting of pio 
 
 cromel, peculiar animal mat- > 14'0 
 
 ter, and insoluble residue J 
 
 (a) The salts, their relative proportions. 
 
 Carbonate of soda 35 
 
 Muriate of soda . 4 
 
 Sulphate of soda ... . 2 
 
 Amm. phosphate of magnesia 2 
 
 Phosphate of lime 4 
 
 100-0 
 
 * Nicholson's Journ. vol. xiv. p. 147. 
 $ Ann. of Phil. vol. xvi. p. 151. 
 || Gehlin's Journ. vol. vi. p. 536. 
 
 3B 
 
 f- Ibid. voL xiv. p. 145. 
 
 Ann. de Chim. vol. xiv. p. 225.
 
 738 
 
 APPENDIX. 
 
 GASES EXISTING IN THE INTESTINAL CANAL. These may be 
 ascribed to three sources : 1st, from the common air swallowed with 
 food ; 2d, from the decomposition of the intestinal contents ; and 3d, 
 from the occasional secretion of gas from the mucous surface of the 
 tube. 
 
 The gases from the first source are found chiefly in the superior 
 portions of the canal ; those from the second source in the lower part ; 
 and those, from the third are by no means limited in their situation. 
 It is reasonable to suppose that a large proportion of the azote and car- 
 bonic acid is derived from this last source. 
 
 From the experiments of Magendie and Chevreul, who examined, 
 very soon after death, the gaseous contents of the stomach and intes- 
 tines of four criminals executed at Paris, the following appear to be the 
 proportions and the relative quantities in the different portions of the 
 canal : * 
 
 1. Gases in the Stomach. 
 Oxygenf 11-00 
 
 .... 14-00 
 
 3-55 
 
 Azote 71-45 
 
 Carbonic acid. 
 Hydrogen 
 
 100-00 
 
 2. Gases in the small Intestines.-^ 
 
 Oxygen OO'OO OO'OO OO'O 
 
 Carb. acid ... 24-39 40-00 25-0 
 Hydrogen ... 55-53 51-15 8-4 
 
 Azote 20-08 88-5 66-6 
 
 100-00 100-00 100-0 
 
 3. Gases in the large Intestines. 
 
 Carbonicacid 43-50 70'0 
 
 Hydrogen and carburetted hydrogen 54-7 11-6 
 
 Azote , 51-03 = 100-00 18-4 = 100*0 
 
 4. Gases in the C&cum . 
 
 Carbonic acid 'l2-5 
 
 Hydrogen ...... '. 7*5 
 
 Carburetted hydrogen 12-5 
 
 Azote 67-5 
 
 100-0 
 
 5. Gases in the Rectum. 
 
 Carbonic acid 42-86 
 
 Carburetted hydrogen 11-18, 
 
 Azote .... ... 45-96 
 
 100-00 
 
 * Ann. de Chim. et Phys. torn. ii. p. 292. 
 
 t The oxygen seems to be absorbed by the blood before it reaches the small 
 intestines. $ Results in the different individuals. 
 
 THE END. 
 
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