HUMAN PHYSIOLOGY. BY HOBLEY DUKGLISON, M.D., LL.D., PROFESSOR OF THE INSTITUTES OF MEDICINR IN JEFFERSOIf MEDICAL COLLEGE, PHILADELPHIA ; VIOK-PRESLDEST OF THE AMERICAN PHILOSOPHICAL SOCIETY, ETC. ETC. 'Vastissimi studii primas quasi lineas circumscripsi." — Haller. FIVE HUNDRED AND THTRTY-TV/0 ILLUSTRATIONS EIGHTH edition:, REVISED, MODIFIED, AND ENLARGED. IN TWO YOLUMES. YOL. I. PHILADELPHIA: B L A N C H A Pv D AND LEA 78 6 -" ^ ^^^.^- Entered according to tlie Act of Congress, in the year 1841, by ROBLEY DUNGLISON, in tlie Clerk's Office of the District Court for the Eastern District of Pennsylvania. PHILADELPHIA : T. K. AND P. G. COLLIXS, PRINTERS. t"" Biomedical Ubiaiy 34- qr d4 ' \on- V 1 mi^-k \ It Si ITI Debication to t!)c £\xzi anb Scconb vEbitious. TO JAMBS MADISON, EX-PRESIDENT OF THE UNITED STATES, ETC., ETC., ALIKE DISTINGUISHED AS AN ILLUSTRIOUS BENEFACTOR OF HIS COUNTRY, A ZEALOUS PROMOTER OF SCIENCE AND LITERATURE, AND THE FRIEND OF MANKIND, Q ' INTENDED TO ILLUSTRATE THE FUNCTIONS EXECUTED BY THAT BEING, WHOSE MORAL AND POLITICAL CONDITION HAS BEEN WITH HIM AN OBJECT OP ARDENT AND SUCCESSFUL STUDY, IS, WITH HIS PERMISSION, INSCRIBED, IN TESTIMONY OF UNFEIGNED RESPECT FOR HIS TALENTS AND PHILANTHROPY, AND OF GRATITUDE FOR NUMEROUS EVIDENCES OF FRIENDSHIP, BY HIS OBEDIENT AND OBLIGED SERVANT, THE AUTHOR. PRErACE TO THE EIGHTH EDITION. The demand for another edition of this work has given occasion to a thorough revision of it by the author. There is no department, perhaps, of medicine, to which the atten- tion of so many investigators has been, and is, directed as to that of physiology ; and, as remarked in the preface to the last edition, perhaps at no time in the history of the science have observers been more energetic, and discriminating. Many modifications of fact and inference have consequently' taken place, which it has been neces- ^ sary for the author to record, and to express his views in I'elation thereto. Especially has he endeavoured to note the phenomena that have presented themselves to the most accurate observers, and to deduce from them laws which may tend to enlarge the boundaries of the science : he has not, however, felt himself at liberty to discard the results of the observations of all former anthropologists, or the opinions they had embraced in regard to the various functions. It not unfre- ijuently, indeed, happens, that in ignorance of the history of the science, views are esteemed new, which had been promulged by earlier inves- tigators. He has, therefore, in an encyclopaediac work like the pre- sent, retained many of those opinions, whilst he has laboured to do especial justice to such as have emanated from more recent inquirers. In this respect, his work differs from valuable physiological treatises that are before the public. Whilst, too, he has inserted the main results of the labours of recent histologists, especially such as are directly applicable to physiology, he has not considered it advisable to pursue the subject to such an extent as if the work were on general anatomy, to which histology properly belongs. vi PREFACE. On the wliole subject of physiology proper, as it applies to the fuuc- tious executed by the different organs, the present edition, the author flatters himself, will be found to contain the views of the most distin- guished physiologists of all periods. The contributions to the science of life have, of late years, been rich and varied ; and to collate and weigh them, and to separate the most trustworthy and valued, has been a work of no little discriminating labour, — but to the author a labour of love, inasmuch as they are subjects which he has been long accus- tomed to investigate ; and on which he has annually to treat before the class of Institutes of Medicine in the Jefferson Medical College. The rich collection of materials in the possession of his publishers has enabled him to increase greatly the list of illustrations, and to sub- stitute in many cases better ; whilst new cuts have been added, so as to make the Avhole number five hundred and thirty-two, in place of four hundred and seventy-four, as in the last edition. It has been diiR- cult in all cases to assign these to the original projectors ; but an effort has been made so to do. The author need scarcely add, that no pains have been spared by him to make the work a complete expression of the science of the day. The list of ex professo publications^ will indicate most of the numerous ' Atlee, Walter F., M. D. Notes of M. Bernard's Lectures on tlie Blood ; witli an appendix, Pkilad., 1S54. Bain, Alexander, A. M. The Senses and the Intellect, London, 1855. Beale, Lionel John. The Laws of Health in relation to Mind and Body : A series of Letters from an old Practitioner to a Patient, Amer. edit., Philad., 1851. Beclard, J. Traite Elementaire de Physiologie Humaine comprenant les Principales Notions de la Physiologie Comparee, Ouvrage accompagne de 144 Gravures iuterca- lees dans le Texte, Paris, 1855. Becquerel, M. Alf. and Rodier, M. A. Traite de Chimie Pathologique appliquee S, la Medecine Pratique, Paris, 1854. Berard, P. Cours de Physiologie, fait a la Faculte de Medecine de Paris. Tome Seme et 2 livraisons du Tome 4eme, 1851-1855. Beraud, M. J. B. Manuel de Physiologie de PHomme et des Principaux Vertebres ; repondant ^ toutes les Questions Physiologiques du Programme des Exameus de Fin d'Annee, revu par M. Ch. Robin, &c., Paris, 1853. Bernard, M. Claude. Lemons de Physiologie Experimentale appliqut-e a la Mi'decine, faites au College de France, avec 22 figures intercalees dans le Texte, Paris, 1855. , see Atlee. Bidder, Dr. F.,and Schmidt, Dr. C. Die Verdauungssafte und der Stoffwechsel. Eine Physiologisch-Chemische Untersuchung. Mit fiiuf Tafeln graphischer Darstellungen, Mitau und Leipzig, 1852. Bishop, John, F. R. S. On Articulate Sounds ; and on the Causes and Cure of Impedi- ments of Speech, London, 1851. & PREFACE. Vll distinct treatises, connected with biology, whicli he has had to consult in the preparation of the present edition. He has, moreover, industriously Bock, Dr. Carl Ernst. Lelirbucli der Pathologisclien Anatomie und Diagnostik, 2 Bd., Leipzig, 1852-1S53. Bowman, John E., F. C. S. A Practical Handbook of Medical Chemistry ; 2d Ameri- can from the third and revised London edition, with illustrations, Philad., 1855. Brachet, J. L. Physiologic Elementaire de I'Homme, 2de edit., 2 vols., Paris et Lyon, 1855. Brodie, Sir Benjamin, Bart., D. C. L., &:c. Physiological Researches, London, 1851. Brown-Sequard, Experimental Researches applied to Physiology and Pathology, New York, 1853. , Sur les Resultats de la Section et de la Galvanisation dn Nerf Grand Sympathique au Cou. (Extrait de la Gazette Medicale de Paris, Annee, 1854.) , Experimental and Clinical Researches on the Physiology and Pathology of the Spinal Cord, and some other parts of the Nervous Centres, Richmond, 1855. , Recherches Experimentales sur la Transmission Croisee des Impressions Sensitives dans la Moelle Epiniere. (Extrait de la Gazette Hebdomadaire de Mede- ciue et de Chirurgie. Tome ii., Nos. 31 and 36), Paris, 1855. , Proprietes et Fonctions de la Moelle Epiniere, Rapport sur quelques Ex- periences de M. Brown-Sequard, lu a la Societe de Biologic, le 21 Juillet, 1855, par M. Paul Broca, Professeur Agrege, &c., Paris, 1855. , Deux Memoires sur la Physiologic de la Moelle Epiniere lus a I'Academie des Sciences le 27 Aoiit et le 24 Septembre, 1855. 1. Recherches sur la Voie de Transmission des Impressions Sensitives dans la Moelle Epiniere. 2. Recherches Experimentales sur la Distribution des Fibres des Racines Posteri- eures dans la Moulle i-piuiere, et sur la Voie de Transmission des Impressions Sen- sitives dans cet Organe. (Extraits de la Gazette Medicale de Paris, Annee, 1855). [The last four memoirs — the gift of Dr. Browu-Sequard — reached the author whilst he was preparing the present list. The results at which he has arrived from his ex- periments on living animals, and published in the two memoirs presented before the Academie des Sciences, of Paris, conflict greatly with those hitherto received by phy- siologists, in regard to the functions of the vesicular and tubular portions of the spi- nal marrow. In the first of the two memoirs he concludes, — that it is not by the posterior cords of the spinal marrow, as is generally admitted in France, that the trans- mission to the encephalon of sensory impressions, received by the trunk and the limbs, is finally effected ; that such transmission is finally eflected by the gray substance of the medulla spinalis, and especially by its central portion ; — and in the latter memoir he concludes, that sensory impressions on their arrival at the medulla spinalis, pass by the posterior cords, the posterior gray cornua, and probably also by the lateral cords ; and that in these different portions of the medulla they ascend or descend ; and after a short course towards the encephalon, or in the opposite direction, quit those parts to enter into the gray central matter, in which, or by which, they are finally transmitted to the encephalon. The brilliant vivisections made by this dexterous experimenter and able physiolo- gist, in the presence of a Committee of the Societe de Biologic, composed of MM. Claude Bernard, Bouley, Broca, Giraldes, Goubaux and Vulpian, have led M. Broca — the reporter — to the sweeping conclusion, that " no known doctrine or system can live alongside the experiments of M. Brown-Sequard ; and that we must submit to make a tabula rasa of everything that has been hitherto said on the physiology of the medulla spinalis." VIU PREFACE. availed himself of multitudinous contributions to medical encyclopcedias, dictionaries, and journals, published at home and abroad; and, for the The Committee considered, that the experiments, performed in their presence, satis- factorily demonstrated — that exposure of the dura mater and of the medulla permitted sensibility and motion to persist in the posterior train ; — that such sensibility still persisted after the section of the posterior cords — called the sensitive cords of the me- dulla ; and that, consequently, these cords are not indispensable for the transmission of sensory impressions ; — that far from abolishing sensibility, the section of the sup- posed sensitive cords was accompanied by hypersesthesia of the lower limbs ; that after such section, the caudal segment of the medulla was more sensible than the cei^halic segment, and that the vesicular matter of the cord was of itself insensible. Other experiments showed, that the separate and complete section of the posterior cords neither destroyed sensibility nor motion ; but that both were destroyed when the vesicular matter was cut across ; that the integrity of the antero-lateral cords did not prevent the loss of movement, nor did that of the posterior cords prevent the loss of feeling. A work on the physiology of the spinal marrow, from the pen of Dr. Brown-Sequard, is announced. It will, doubtless, contain all the facts observed by him, as well as the important deductions to which his ample knowledge of the whole subject cannot fail to have led him.] Budd, Geo., M. D., F. R. S. On Diseases of the Liver, 2d Amer. from the last and improved London edition, with colored plates and wood-cuts, Philad., 1853. , On the Organic Diseases and Functional Disorders of the Stomach, Amer. edit., Philad., 1856. Budge, Julius. Memoranda der Speciellen Physiologie des Meuschen ; ein Leitfaden fiir Vorlesungen und zum Selbststudium, 5te verbesserte tind vermehrte Aiiflage. Mit 10 Kupfertafeln, Weimar, 1853. Bushnan, J. Stevenson, M. D. The Principles of Animal and Vegetable Physiology ; a Popular Treatise on the Functions and Phenomena of Organic Life ; to which is prefixed a general view of the great Departments of Human Knowledge, with one hundred and two Illustrations on wood. [Reprinted from vol. 1 of Orr's Circle of the Sciences, London, 1854.] Philadelphia, 1854. Carpenter, William B., M. D., F. R. S., &c. Pi-inciples of Human Physiology, with their Chief Applications to Psychology, Pathologj'-, Therapeutics, Hygiene, and Fo- rensic Medicine. A new American from the last London edition, with two hundred and sixty-one Illustrations. Edited, with additions, by Francis Gurney Smith, M. D., Professor of the Institutes of Medicine in the Medical Department of Pennsylvania College, &c., Philad., 1855. , Principles of Comparative Physiology, with three hundred and nine wood engravings. A new American from the fourth and revised London edition, Philad., 1854. Chambers, Thomas K. Digestion and its Derangements. The Principles of Rational Medicine applied to Disorders of the Alimentary Canal, London, 1856. Coste, M. Histoire Gt'nerale et Particuliere du Developpement des Corps Organises, Publie sous les Auspices de M. Villemain, Ministre de I'lnstruction Piibllque, Paris, 1847-1854. Eschricht, Dr. Daniel Friedrich. Das Physische Leben in Poi^ularen Vortriigen. Mit 208 Abbildungen, meist in Holz geschnitten, Kopenhagen, 1852. Fabius and Buys-Ballot. De Spirometro ejusque Usu. Dissertatio Inauguralis, Am- stelodam., 1853. PREFACE. IX eighth time, he ventures to place the work before a profession, which, he is proud in being permitted again to state, has already done too Fleiiry, Louis. Cours d'Hygiene fait a la Faculte de Medecine de Paris, Paris, 1852. Flourens, Prof. P. Histoire de la Decouverte de la Circulation du Sang, Paris, 1854. , De la Longevite Huniaine et de la Quantite de Vie sur le Globe, 2enie Edi- tion, Paris, 1855. Funke, Dr. Otto. Atlas der Physiologisclien Cliemie, zugleich als Supplement zu C. G. Lehmann's Lehrbuclx der Physiologisclien Chemie. Funfzelm Tafeln enthaltend 90 Abbildungen siimmtlicli nacli dem Mikroscop gezeichnet und erlautert, Leipzig, 1853. , See Giinther. , See Wagner. Gavarret, J. Physique Medicale. De la Chaleur produite par les Etres Vivants, Avec 41 figures dans le Texte, Paris, 1855. Gluge, Dr. Gottlieb. Pathologische Histologie. Mit 12 Kupfertafeln und fabellen, Jena, 1850 ; Translated, under the Title, Atlas of Pathological Histology, by Dr. Gottlieb Gluge, &c., &c., from the German, by Joseph Leidy, M. D., &c. &c., Philad.j 1853. Giinther, Dr. August Friedrich. Lehrbuch der Physiologie des Menschen fiir Aerzte und Studirende. Fortgesetzt von Dr. Otto Funke, &c. II Band. 2, 3, und 4 Abtheilung, Leipzig, 1853. Holland, (Sir; Henry, M. D., F. R. S. Chapters on Mental Physiology, London, 1852. Jochman, Dr. Paul Alex., Beobachtungen tiber die Koi-perwarme in chronischen fieberhaften Krankheiten. Mit zwei lithograiihirten Tafeln, Berlin, 1853. Jones, C. Handfield, M. B. F. R. S., and Edward H. Sieveking, M. D. A Manual of Pa- thological Anatomy. First American edition, revised, with three hundred and ninety- seven Illustrations, Philad., 1854. Keber, G. A. F. De Sjiermatozoorum Introitu in Ovula, Konigsberg, 1853. Kirkes, W. S., M. D., and Paget, James, F. R. S. Manual of Physiology, 2d Amer. edit., Philad., 1853. Kitto, John, D. D., F. S. A. The Lost Senses. Series 1. Deafness, London, 1853. Series 2. Blindness, London, 1845. Kobelt, Dr, De I'Appareil du Sens Genital des deux Sexes dans I'Espece Humaine et dans quelques Mammiferes, au point de Vue Anatomique et Physiologique. Traduit de I'AUemand par H. Kaula, D. M. Avec cinq Planches lithographiees, Strasbourg et Paris, 1851. Kolliker, Dr. A. Mikroskoi^ische Anatomic oder Gewebelehre des Menschen, 2ter Band., Leipzig, 1850-1854. , Manual of Human Histology, translated and edited by George Busk, F. R. S., and Thomas Huxley, F. R. S. Sydenham Society's edition, 2 vols., London, 1853-1854. American edition under the title. Manual of Human Microscopical Anatomy, edited with notes and additions by J. Da Costa, M. D., illustrated by three hundred and thirteen Engravings on wood, Philad., 1854. Lehmann, Prof. C. G. Lehrbuch der Physiologisclien Chemie, 2te giinzlich neu um- gearbeite Auflage,3 Bd. Leipz., 1850-1852. Translated for the Cavendish Society, by Dr. Geo. E. Day, M. D., F. R. S. Amer. edition by Prof. R. E. Rogers, M. D., with Illustrations selected from Funke's Atlas of Physiological Chemistry, and an Appendix of Plates, 2 vols, Philad., 1855. , Handbuch der Physiologischen Chemie, Leipzig, 1854, translated under X PREFACE. much honor to his efforts to be useful. His crowning desire, in all his literary undertakings connected with his profession, has been to the following Title, Manual of Cliemical Physiology, from the German of Prof. C. G. Lelimann, M. D., translated with notes and additions by J. Cheston Morris, M.D., with an Introductory Essay ou Vital Force, by Samuel Jackson, M. D., Professor of Institutes of Medicine in the University of Pennsylvania, and illustrated with forty Woodcuts, Philad., 1856. Liebig, Justus Von. Familiar Letters on Chemistry, in its relations to Physiology, Dietetics, Agriculture, Commerce, and Political Economy, 3d edition, revised and miuch enlarged, London, 1851. Longet, F. A. Traite de Physiologic, Ouvrage accompagne de figures dans le teste et de planches en taille-douce, Tom. ler, Fascicul. 3, Paris, 1852. Ludwig, C. Lehrbuch der Physiologie des Meuschen, Iste Band, Heidelberg, 1852- 1853 ; und 2ter Band, Iste Abtheilung, Leipzig und Heidelberg, 1855, 2te Abth. 1856. Mialhe, Dr. Chemie Appliquee a la Physiologie et k la Therapeutique, Paris, 1856. Moleschott, Dr. Jac. Physiologie des Stoffswechsels in Pflanzen und Thieren, ein Handbuch fiir Naturforscher, Landwirthe, und Aerzte, Erlangen, 1851. Moser, Dr. A., and Dr. J. C. Strahl. Handbuch der Physiologischen und Pathologis- chen Chemie, nach den neusten Quellen bearbeitet, Leipzig, 1851. Noble, Daniel, M. D., Elements of Psychological Medicine: An Introduction to the Prac- tical Study of Insanity, adapted for Students and Junior Practitioners, London, 1853. Oesterlen, Dr. Fr. Handbuch der Hygieine fiir den Einzelnen wie fiir eine Bevolke- rung, Tubingen, 1851. Paget, James, F. R. S. Lectures on Surgical Pathology, delivered at the Eoyal College of Surgeons of England; Hypertrophy, Atrophy, Repaii-, Inflammation, Mortification, Specific Diseases, and Tumors, Amer. edit., Philad., 1854. Prochaska. See Unzer and Prochaska. Robin, Charles. See Atlee, Walter F. ' , et F. Verdeil. Traite de Chimie Anatomique et Physiologique Normale et Pathologique ou des Principes Immediats Normaux et Morbides qui constituent le Coii^s de I'Homme et des Mammiferes, accompagne d'un Atlas de 45 Planches gra- vees, en partie coloriees, 3 vols., Paris, 1853. Segond, L. A. Traite d'Anatomie Generale : Theorie de la Structure, embrassant les Substances Organiques et les Elements, les Tissus, les Jlembraues et les Parenchymes, Paris, 1854. Sieveking, Edward H. See Jones, C. Handfield. Strahl, Dr. J. C. See Moser, Dr. A. Tardieu, Ambroise. Dictionnaire d'Hygiene Publique et de Salubrite ou Repertoire de toutes les Questions relatives a la Saute Publique, considerees dans leurs Rapports avec les Substances, les Epidemies, les Professions, les Etablissements et Institutions d'Hygiene et de Salubrite, complete par le Texte des Lois, Decrets, Arretes, Ordounances et Instructions qui s'y rattacheut, 3 vols., Paris, 1852-1854. Thomas, Dr. E. Die Physiologie des Menschen, Leipzig, 1853. Todd, Robert Bentley, M. D., F. R. S., and Bowman, Wm., F. R. S. Tlie Physiological Anatomy and Physiology of Man, Pt. iv.. Sect. 1, London, 1852, Amer. edit., Philad., 1853. Unzer and Prochaska. Tlie Principles of Physiology, by John Augustus Unzer, and A Dissertation on the Functions of the Nervous System, by George Prochaska, trans- lated and edited by Thomas Laycock, M. D. (Sydenham Society's edit.), London, 1851. PREFACE. XI facilitate the onward course of those, who are pressing forward for dis- tinction in a truly learned and difficult avocation ; and the reception, which his undertakings have met with, has abundantly satisfied him that his labours have been far from fruitless. ROBLEY DUNGLISOK IS GiEAED St. May, 1856. Wagner, Rudolph. Lelirbuch der Speciellen Pliysiologie, vierte durchgehends neu bearbeitete Aiiflage, von Dr. Otto Funke ; also under tlie title — Lelirbuch der Physi- ologic, von Dr. Otto Funke, Leipzig, 1854. Wedl, Carl, M. D. Rudiments of Pathological Histology, with 172 Illustrations on wood, translated from the German, and edited by George Busk, F. R. S. (Sydenham Society's edition), London, 1855. Wilson, Erasmus, F. R. S. Healthy Skin : A Popular Treatise on the Skin and Hnir, their Preservation and Management, 2d Amer., from the 4th and revised London edi- tion, with niustrations, Philad., 1854. CONTENTS OF YOL I PRELIMINARY OBSERVATIONS. Prolegomena. I. Natural Bodies ..... 1. Difference between Inorganic and Organized Bodies 2, Difference between Animals and Vegetables II. General Physiology of Man ... 1 . Material Composition of Man a. Organic Elements that contain nitrogen b. Organic Elements that do not contain Nitrogen c. Of tlie Solid parts of the Human Body . d. Of the Fluids of the Human Body e. Physical Properties of the Tissues 2. Functions of Man .... '33 34 39 43 43 47 53 57 62 64 69 BOOK I. NUTRITIVE FUNCTIONS, Chap. I. Chap. II. Digestion ..... 73 1. Anatomy of the Digestive Organs . 73 2. Food of Man .... 106 3. Physiology of Digestion . 120 4. Digestion of Solid Food 121 a. Hunger .... 121 b. Prehension of Food 127 c. Oral or Buccal Digestion 130 d. Deglutition .... 135 e. Chymification 139 f. Action of the Small Intestine 176 g. Action of the Large Intestine 185 5. Digestion of Liquids . 194 6. Of Eructation, Regurgitation, and Rumination 197 Absorption . . . . . 206 I. Digestive Absorption . . . , 207 a. Absorption of Chyle or Chylosis . 207 1. Anatomy of the Chyliferous Apparatus 207 2. Chyle 215 3. Physiology of Chylosis . 221 b. Absorption of Drinks 230 XIV CONTENTS. II. Absorption of Lymph or Lympliosis . 1. Anatomy of tlie Lymphatic Apparatus 2. Lymph .... 3. Physiology of Lymphosis . III. Venous Absorption 1. Physiology of Venous Absorption . IV. Internal Absoi-ption . V. Accidental Absorption . . a. Cutaneous Absorption b. Other Accidental Absorptions Chap. III. Respiration .... 1. Anatomy of the Respiratory Organs . 2. Atmospheric Air 3. Physiology of Respiration . a. Mechanical Phenomena of Respiration (1.) Inspiration (2.) Expiration (3.) Respiratory Phenomena concerned in certain Functions (4.) Respiratory Phenomena connected with Expression b. Chemical Phenomena of Respiration c. Cutaneous Respiration, &c. d. Effects of Section of the Cerebral Nerves e. Respiration of Animals Chap. IV. Circulation .... on Respiration Chap. V. VI. 1. Anatomy of the Circulatory Organs . a. Heart .... b. Arteries .... c. Intermediate, Peripheral or Capillary System d. Veins .... 2. Blood .... 3. Physiology of the Circulation a. Circulation in the heart . b. Circulation in the Arteries c. Circulation through the Capillaries d. Circulation in the Veins . e. Forces that Propel the Blood f. Accelerating and Retarding Forces g. The Pulse .... h. Uses of the Circulation i. Transfusion and Infusion . 4. Circulatory apparatus in animals Nutrition ..... Secretion ..... 1. Anatomy of the Secretory Apparatus 2. Physiology of Secretion Exhalations, or Simple Secretions A. Internal Exhalations . 1. Areolar Exhalation 2. Serous Exhalation — General and Vascular a. General b. Vascular 3. Synovial Exhalation CONTENTS. XV 4. Adipous Exhalation . a. Fat b. Marrow 5. Pigmental Exhalation 6. Ca]3sular Exhalation . B. External Exhalations 1. Exhalations of the Skin and Mncous 2. Menstrual Exhalation 3. Gaseous Exhalation . II. Follicular Secretions 1. Follicular Secretion of Mucoits Membranes 2. Follicular Secretion of the Skin 3. Secretion of the Ovaries III. Glandular Secretions . 1. Transpiratory Secretion of the Skin 2. Secretion of the Lachrymal Gland 3. Secretion of the Salivary Glands 4. Secretion of the Pancreas 6. Secretion of the Liver 6. Secretion of the Kidneys a. Connection between the Stomach 7. Secretion of the Testes 8. Secretion of the Manimse IV. Vascular or Ductless Glands o. The Sj^leen Chap. VII. Calorification . Membranes — Dermic and the Kidneys BOOK II. ANIMAL FUNCTIONS. Chap. I. Sensibility .... 1. Nervous System 2. Physiology of Sensibility a. Sensations . a. External Sensations A. Sense of Tact or Touch — Palpation 1. Anatomy of the Skin, Hair, Nails, &c 2. Physiology of Tact and Touch ^ B. Sense of Taste or Gustation 1. Anatomy of the Organs of Taste 2. Savours 3. Physiology of Taste . C. Sense of Smell or Olfaction 1. Anatomy of tlie Organ of Smell 2. Odours 3. Physiology of Olfaction LIST OF ILLUSTRATIONS IN VOL. L FIG. 1. Endosmometer, ...... 2. Diagram of the stomach and intestines to show their course, 3. Skull of the Polar bear, ..... 4. Skull of the cow, ...... 5. Salivary glands in situ, ..... 6. Cavity of the mouth, as sliown by dividing the angles and turning off the lips, ........ 7. Pharynx seen from behind, ...... 8. Longitudinal section of oesophagus, near the pharynx, seen on its inside, 9. Section of the cesophagus, ...... 10. A view of the muscles of the tongue, palate, &c., 11. Stomach seen externally, ...... 12. Vei'tical and longitudinal section of stomach and duodenum, 13. Section of a piece of stomach not far from pylorus, 14. A portion of the mucous membrane of the stomach, after Wilson, 15. Tubular follicle of pig's stomach, after Wasmann, . 16. Peptic gastric gland, after Kolliker, .... 17. Portions of one of the cseca more highly magnified, after Kolliker, . 18. Mucous gastric gland, with cylinder epithelium, after Kolliker, 19. Capillary network of lining membrane of stomach, after Kolliker, . 20. Vertical section of a stomach cell with its tubes, after Todd and Bowman 21. Mucous membrane of the stomach, Todd and Bowman, 22. Appearance of living membrane of stomach injected, Carpenter, . 23. Front view of stomach, distended by flatus, with peritoneal coat turned off, 24. Distribution of the glosso-pharyngeal, pneumogastric and spinal accessory nerves, or the eighth pair, 25. Stomach of the ox, ..... 26. Section of part of the stomach of the sheep, Flourens, 27. Digestive ajiparatus of common fowl, Edwards, 28. Gastric apparatus of the turkey, 29. Interior of the gastric apparatus of the turkey, 30. Portion of the stomach and duodenum laid open to show their interior, 31. Longitudinal section of the upper part of the jejunum extended under water, ........ 82. Muscular coat of the ileum, ...... 33. Distribution of capillaries in the villi of the intestine, after Berres, 34. Arrangement of capillaries in mucoiis membrane of large intestine, after Todd and Bowman, ....... VOL. I.— 2 PAGE G7 74 75 76 78 79 79 79 79 80 81 82 82 83 83 84 84 84 84 85 85 86 86 87 88 89 89 90 91 93 .^3 94 94 94 XVlll LIST OF ILLUSTKATIOXS, 35. Distribution of capillaries around follicles of mucous membrane, after Berres, ......... 94 36. Bloodvessels of villi of the hare, after DoUiuger, . . . .95 37. One of the glandule majores simplices of the large intestine, as seen from above, and also in a section, after Boelim, . . . .95 38. Vertical section of the mucous membrane of the duodenum in the horse, after Todd and Bowman, ....... 95 39. Portion of one of Brunner's glands from the human duodenum, after Allen Thomson, ......... 96 40. Section of the mucous membrane of the small intestine in the dog, after Todd and Bowman, . . . . . . .96 41. Transverse section of Lieberkiihn's tubes or follicles, after Todd and Bow- man, ......... 97 42. Horizontal section through the middle plane of three Peyerian glands, after Kolliker, ......... 97 43. Vertical section of two of the Peyerian glandulre, after Allen Thompson, . 98 44. A patch of Peyer's glands of the adult human subject, after Boehm, . 98 45. Section of small intestine, containing some of the glands of Peyer, as shown under the microscope, ....... 98 46. Side view of intestinal mucous membrane of a cat, after Bendz, . . 99 47. Vertical section through a patch of Peyer's glands in the dog, after Todd and Bowman, ........ 99 4S. Muscular coat of the colon, as seen after the removal of the peritoneum, . 101 49. Longitudinal section of the end of the ileum, and of the beginning of the large intestine, ........ 101 50. View of external parietes of abdomen, with the position of the lines drawn to mark off its regions, ....... 103 51. Reflections of the peritoneum, as shown in a vertical section of the body, 105 52. Action of the lower jaw in prehension, ..... 129 53. Gastric glands of the oesophagus magnified fifteen times, after Sir E. Home, 159 54. Chyliferous vessels, ........ 207 55. Chyliferous apparatus, ....... 209 56. Section of intestinal villus, after Gerlach, ...•*. 210 57. Intestinal villus with the commencement of a lacteal, after Krause, . 210 58. Extremity of intestinal villus, after Goodsir, .... 211 59. Extremity of an intestinal villus during absorption, after Kijlliker, . 211 60. Thoracic duct, after Wilson, . . . . . .213 61. Diagram of a lymphatic gland, showing the intra-glandular network, and the transition from the scale-like epithelia of the extra-glandular lym- phatics, to the nucleated cells of the intra-glandular, after Goodsir, . 213 62. Portion of the intra-glandular lymphatics, showing along the lower edge the thickness of the germinal membrane, and upon it, the thick layer of glandular epithelial cells, after Goodsir, . . . .213 63. Section of lymphatic gland, after Kolliker, ..... 214 64. Fluid from a mesenteric gland of a rabbit when white chyle was present in the lacteals, after Todd and Bowman, . . . . .217 65. Chyle corpuscles in various phases, after Kolliker, . . . 217 66. Villi of the human intestine, with their capillary plexus injected, after Kol- liker, ......... 230 67. Capillary plexus of the villi of the human small intestine, after Todd and Bowman, ......... 231 68. Vertical section of the coats of the small intestine of a dog, after Todd and Bowman, ......... 231 LIST OF ILLUSTRATIONS. XIX FIG. PAGE 69. Vessels and lymphatic glands of axilla, ..... 238 70. Lymphatic vessels and glands of the groin of the right side, . . 239 71. Bloodvessels and lymphatics from the tail of the tadpole, . . . 242 72. Lymphatic glands injected with mercury, after Mascagni, . . . 243 73. Group of blood vesicles fi-om the thyroid gland of a child, after KoUiker, . 243 74. Termination of thoracic duct, ...... 249 75. Lymph heart of python bivittatus, after Weber, .... 251 76. Anterior view of thorax, ....... 269 77. Anterior view of the thoracic viscera in situ, as shown by the removal of the anterior parietes of the thorax, ..... 270 78. Posterior view of the thoracic viscera, showing their relative positions by the removal of the posterior portion of the parietes of the thorax, . 271 79. A shaded diagram, representing the heart and great vessels, injected and in connexion with the lungs : the pericardium is removed, after Quain, 272 80. Arrangement of the capillaries of the air-cells of the human lung, after Carpenter, . . . . . . . . 273 81. Air-cells from an emphysematous lung, after Leidy, . . . 275 82. Transverse section of a portion of the pulmonary parenchyma, after Leidy, 276 83. Longitudinal section of the termination of a bronchus, after Leidy, . 276 84. Thin slice from the pleural surface of a cat's lung, after Rossignol, . 277 85. Bronchial termination in the lung of the dog, after Rossignol, . . 277 86. Air-cells of human lung, with intervening tissues, after Kolliker, . 277 87. Outline of a transverse section of the chest, showing the relative position of the pleurae to the thorax and its contents, .... 279 88. The changes of the thoracic and abdominal walls of the male during respi- ration, after Hutchinson, ...... 287 89. The respiratory movements in the female, after Hutchinson, . . 287 90. Small bronchial tube laid open, after Todd and Bowman, . . . 290 91. Heart of the dugong, ....... 331 92. Diagram of the circulatory apparatus in mammals and birds, after M. Ed- wards, ......... 331 93. Heart placed with its anterior surface upwards, and its apex turned to the right hand of the spectator. The right auricle and right ventricle are both opened, after Quain, ...... 332 94. Semilunar valves closed, ....... 333 95. Diagram of the semilunar valves of the aorta, after Morgagni, . . 333 96. Sections of aorta, to show the action of the semilunar valves, . . 334 97. Heart seen from behind, and having the left auricle and ventricle opened, after Quain, ........ 335 98. Anterior view of external muscular lnyer of the heart after removal of its serous coat, &c., . . . . . . . .336 99. Posterior view of the same, ...... 336 100. View of the heart in situ, after Pennook, ..... 338 101. Circulation in the web of the frog's foot, after Wagner, . . . 344 102. Portion of the web of the frog's foot, after Wagner, . . . 345 103. Circulation in the under surface of the tongue of the frog, after Donne, . 345 104. Capillary network of nervous centres, ..... 346 105. Cajjillary network of fungiform papilla of tongue, after Berres, . . 346 106. Capillaries of the web of the frog's foot, after Wagner, . . . 349 107. Splenic vein with its branches and ramifications, .... 350 108. Diagrams showing valves of veins, after Quain, .... 352 XX LIST OF ILLUSTRATIONS. FIG. 109. 110. 111. 112. 113. 114. 115. IIG. 117. 118. 119. 120. 121. 122. 123. 124. 125. 126. 127. 128. 129. 130. 131. 132. 133. 134. 135. 136. 137. 138. 139. 140. 141. 142. 143. 144. 145. 146. Roots, trunk, and divisions of the vena jwrta. Portal system, after Wilson, ..... Red corpuscles of liuman blood, after Donne, Blood corpuscles of rana esculenta, after Wagner, Red corpuscles of pigeon's blood, after Todd and Bowman, Red corpuscles of fishes, after Wharton Jones, White corpuscles of the blood, after Paget, Developement of human lymph and chyle corpuscles into red corpuscles of blood, after Paget, ...... Blood crystals, after Otto Funke, ..... Coagulation of normal human blood under the microscope, after Otto Funke, ........ Aggregation of corpuscles in healthy and in inflamed blood, after T. W Jones, ........ Hsemadynamometer, after Poigeuille, .... Section of a forcing pump, ...... Small venous branch, from the web of a frog's foot, magnified 350 diame ters, after Wagner, ...... Large vein of frog's foot, magnified 600 diameters, after Wagner, Vena contracta, ....... Do. do. ....... Circulation in the frog, ...... Circulation in fishes, ...... Interior of the leech, ...... Areolar tissue, after Edwards, ..... Muscular tissue, after Edwards, ..... Nei-vous tissue, after Edwards, ..... Cellules of brain, after Dutrochet, ..... Primary organic cell, showing the germinal cell, nucleus, and nucleolus after Todd and Bowman, ..... Plan representing the formation of a nucleus, and of a cell on the nucleus according to Schleiden's view, ..... Endogenous cell-growth in cells of a meliceritous tumour, after Goodsir, Tattooed head of a New Zealand chief, .... Plan of secreting membrane, after Sharpey and Quain, Plan to show augmentation of surface by formation of processes, after Sliarpey and Quain, ...... Plans of extension of secreting membrane by inversion or recession in form of cavities, after Sharpey and Quain, .... Portion of areolar tissue inflated and dried, showing the general character of its larger meshes ; magnified twenty diameters, after Todd and Bow- man. ......... Arrangement of fibres in areolar tissue, magnified 135 diameters, after Car- penter, ......... White fibrous tissue, from ligament, magnified 65 diameters, after Car- penter, ......... Yellow fibrous tissue, from ligamentum nuchae of calf, magnified 65 diame- ters, after Carpenter, ....... A small cluster of fat-cells, magnified 150 diameters, Bloodvessels of fat vesicles, after Todd and Bowman, Fat vesicles from an emaciated subject, alter Todd and Bowman, 485 485 486 486 490 490 492 LIST OF ILLUSTRATIONS. XXI FIG. 147. Sebaceous or oil glands and ceruminous glands, after Wagner, 148. Cutaneous follicles or glands of the axilla, magnified one-third, after Horner, ........ 149. Entozoa from the sebaceous follicles, after Todd and Bowman, 150. Vertical section of the sole, after Todd and Bowman, 151. Vertical section of epidermis from palm of the hand, after Todd and Bow man, ........ 152. Surface of the skin of the palm, after Todd and Bowman, 153. Lobules of the parotid gland, in the embryo of the sheep, in a more ad vanced condition, after Miiller, ..... 154. Distribution of capillaries around the follicles of parotid gland, after Berres, 155. Figure, altered from Tiedemann, in which the liver and stomach are turned up to show the duodenum, the pancreas, and the siJleen, after Quain, ........ 156. Lobules of liver, after Kiernan, ..... 157. Connexion of lobules of liver with hepatic vein, after Kiernan, 158. Transverse section of lobules of the liver, after Kiernan, 159. Horizontal section of three superficial lobules, showing the two principal systems of bloodvessels, after Kiernan, .... 160. Horizontal section of two superficial lobules, showing interlobular plexus of biliary ducts, after Kiernan, ..... 161. A small portion of a lobule highly magnified, after Leidy, . 162. Portion of a biliary tube, from a fresh human liver, very highly magnified after Leidy, ....... 163. Transverse section of a lobule of tlie human liver, after Leidy, 164. Hepatic cells gorged with fat, after Bowman, 165. Minute portal and hepatic veins and capillaries, after Budd, 166. Diagram of the arrangement of the cellular parenchyma of the liver, after Kijlliker, ........ 167. Lobules of the liver magnified, after Budd, .... 168. First stage of hepatic venous congestion, after Kiernan, 169. Second stage of hepatic venous congestion, after Kiernan, . 170. Portal venous congestion, after Kiernan, .... 171. The three coats of gall-bladder separated from each other, . 172. Gall-bladder distended with air, and with its vessels injected, 173. Crystals of cholesterin, &c., after Otto Funke, 174. Right kidney with its renal capsule, .... 175. Plan of a longitudinal section of the kidney and upper part of the ureter, through the hilus, copied from an enlarged model, 176. Portion of kidney of new-born infant, after Wagner, 177. Small portion of kidney magnified 60 diameters, after Wagner, 178. Section of the cortical substance of the human kidney, after Ecker, 1 79. Tubuli uriniferi, after Baly, ...... 180. Plan of the renal circulation, after Bowman, 181. Part of the ossa pubis and ischia, with the root of the penis attached, after Kobelt, ........ 182 Section of the spleen, ...... 183. Branch of splenic artery, the ramifications studded with Mali^ighian cor- puscles, after KiJlliker, ...... 184. Anterior view of the brain and spinal marrow, 185. Falx cerebri and sinuses of upper and back part of skull, PAGE 505 xxu LIST OF ILLUSTRATIONS. FIG. 186. Longitudinal section of the brain on the mesial line, 187. Convolutions of one side of the cerebrum, as seen from above, 188. Superior part of the lateral ventricles, coi-pora striata, septum lucidum, fornix, &c., as given by a transverse section of the cerebrum, 189. Section of the cerebrum, displaying the surfaces of the coqwra striata, and optic thalami, the cavity of the third ventricle, and the upper surface of the cerebellum, ....... 190. An under view of the cerebellum, seen from behind, 191. Posterior superior view of the pons Varolii, cerebellum, and medulla ob longata and M. spinalis, ...... 192. Analytical diagram of the encephalon — in a vertical section, after Mayo, 193. Anterior view of the medulla oblongata, showing the decussation of the pyramids, and of the upper part of the spinal cord, after Mayo, 194 Posterior view of the medulla oblongata, .... ] 95 Transverse sections of the spinal cord, Todd and Bowman, 196 Shows the under surface or base of the encephalon freed from its mem branes, ........ 107 I -,qo j Pacinian corpuscles, after Todd and Bowman, . . 199. Tactile corpuscles from the skin, after Ecker, 200. A nerve consisting of many smaller cords or funiculi wrapped up in common cellular sheath, ...... 201. A portion of the spinal marrow, showing the origin of some of the sfnnal nerves, ......... 202. Plans in outline, showing the front a, and the sides b, of the spinal cord, with the fissures upon it ; also sections of the gray and white matter, and the roots of the spinal nerves, . . . . . 203. Pioots of a dorsal sjnnal nerve, and its union with sympathetic, Todd and Bowman, ...... 204. Great sympathetic nerve, .... 205. Structure of the spinal cord, according to Stilling, . 206. Transverse section of the medulla, after Stilling, . 207. Tubular nerve-fibres, .... 208. Gelatinous nerve-fibres, .... 209. Ganglion corpuscles, after Valentin, 210. Stellate or caudate nerve-corpuscles, after Hannover, 211. Microscopic ganglion from heart of frog, after Ecker, 212. Bipolar ganglionic cells, &c., after Ecker, . 213. Connection between nerve-fibres and nerve-corpuscles, 214. Circle of Willis, ..... 215. Sinuses of the base of the skull, 216. Capillary network of nervous centres, after Berres, 217. Distribution of capillaries at the surface of the skin of the finger, after Berres, ••.... 218. Brain of squirrel, laid open, after Solly, 219. Brain of turtle, after Solly, .... 220-21. Brains of fishes, after Leuret, 222. Vertical section of epidermis, from the palm of the hand, after Wilson 223. Section of the skin, ..... 224. Papilla- of the palm, the cuticle being detached, magnified 35 diameters, 225. Sections of hair, ..... PAGE 631 631 632 LIST OF ILLUSTKATIONS. XSlll FIG. PAGE 2-16. Thin layer from tlie scalp, ....... G81 227. Magnified view of the root of the hair, Kohlrausch, . . . 681 228. Section of the skin on the end of the finger, Todd and Bowman, . . 684 229. Transverse section of a finger-nail, after Wilson, .... 684 230. A. Separated epithelium cells from mucous membrane of the mouth, b. Pavement-epithelium of the mucous membrane of the smaller bronchial tubes, ......... 685 231. Tesselated epithelium, ....... 686 232. Scales of tesselated epithelium, after Henle, .... 687 233. Cylinders of intestinal epithelium, after Henle, .... 687 234. Hand of man compared with anterior extremity of orang, after Gervais, 693 235. Capillary network at margin of lips, after Berres, .... 694 236. Front view of the upper surface of the tongue, as well as of the palatine arch, Wilson, ........ 699 237. View of a papilla of the smallest class, magnified 25 diameters, Todd and Bowman, ......... 699 238. Vei'tical section of one of the gustatory papilL-e of the largest class, show- ing its conical form, its sides, and the fissure between the diflerent papillas, Todd and Bowman, ...... 700 239. The hypoglossal ; lingual branch of fifth pair ; glosso-pharyngeal and deep- seated nerves of the neck, ...... 700 240. Vertical section of the middle part of the nasal fossae, giving a posterior view of the arrangement of the ethmoidal cells, &c., . . . 713 241. Outer wall of the nasal fossfe with the three spongy bones and meatus, after Sommering, . . . . . . . .714 242. Nerves of the septum of the nose, after Arnold, .... 714 243. A portion of the pituitary membrane of the nasal septum, magnified 9 times, showing the number, size, and arrangement of the mucous crypts, . 715 244. A portion of the pituitary membrane, with its arteries and veins injected, magnified 15 diameters, ....... 715 245. Olfactory filaments of the dog, Todd and Bowman, . . . 715 HUMAN PHYSIOLOGY. PROLEGOMENA. I. NATURAL BODIES. The extensive domain of Nature is divisible into tliree great classes : — Minerals^ Vegetables, and Anviaals. This division was universally adopted by the ancients, and still prevails, especially amongst the unscientific. When, however, we carefully examine their respective characteristics, we discover, that the animal and the vegetable resemble each other in many essential particulars. This resemblance has given occasion to the partition of all bodies into two classes : the Inorganic, or those not possessing organs or instruments adapted for the perform- ance of special actions or functions, and the Organized, or such as possess this arrangement. In all ages, philosophers have attempted to point out a " Vast chain of being, which from God began, Nature's ethereal, human, angel, man. Beast, bird, fish, insect, what no eye can see, No glass can reach — " the links of which chain they have considered to be constituted of all natural bodies; passing by insensible gradations through the inorganic and the organized, and forming a rigid and unbroken series ; and in which, they have conceived, " Each moss, Each shell, each crawling insect, holds a rank, Important in the plan of Him wlio framed This scale of beings — holds a rank which, lost, Would break the chain, and leave behind a gap Which Nature's self would rue." Crystallization has been esteemed by them as the highest link of the inorganic kingdom ; the lichen, which encrusts the stone, as but one link higher than the stone itself; the mushroom and the coral as the connecting links between the vegetable and the animal ; and the im- mense space, which separates man — the highest of the mammalia — from his Maker, they have conceived to be occupied in succession by beings of gradually increasing intelligence. If, however, we investi- gate the matter minutely, we discover that many links of the chain appear widely separated from each other; and that, in the existing VOL. I. — 3 34: NATURAL BODIES. State of our knowledge, the catenation cannot be esteemed rigidly maintained.' Let us inquire into the great characteristics of the dif- ferent kingdoms, and endeavour to describe the chief points in which living bodies differ from those that have never possessed vitality, and into the distinctions between organized bodies themselves. 1. DIFFERENCE BETWEEN INORGANIC AND ORGANIZED BODIES. Inorganic bodies possess the common properties of matter. Their elements are fixed under ordinary circumstances. Their study con- stitutes Physics, in its enlarged sense, or Natural Science. Organized bodies have properties in common with inorganic, but they have like- wise others superadded, which control the first in a singular manner. They are beings, whose elements are undergoing constant mutation, and the sciences treating of their structure and functions are Anatomy and Physiology. They differ from each other in — 1. Origin. — Inorganic bodies are not born : they do not arise from a parent : they spring from the general forces of matter, — the particles being merely in a state of aggregation, and their motions regulated by certain fixed and invariable laws. The animal and the vegetable, on the other hand, are products of generation ; they must spring from beings similar to themselves: and they possess the force of life, which controls the ordinary forces of matter. Yet it has been supposed, that they are capable of creating life; in other words, that a particular organization presupposes life. This is not the place for entering into the question of generation. It will be sufficient at present to remark, that in the upper classes of animals, the necessity of a parent cannot be contested ; the only difficulty that can possibly arise regards the very lowest classes ; and analogy warrants the conclusion, that every living being must spring from an egg or a seed. 2. Sliape. — The shape of inorganic bodies is not fixed in a deter- minate manner. It is true, that by proper management every mineral can be reduced to a primitive nucleus, which is the same in all minerals of like composition ; still, the shape of the mineral, as it presents itself to us, differs. Carbonate of lime, for example, although it may always be reduced to the same primitive nucleus, assumes various appear- ances ; — being sometimes rhoraboidal ; at others, in regular hexahedral })risms; — in solids, terminated by twelve scalene triangles, or in dode- cahedrons, whose surfaces are pentagons. In organized bodies, on the contrary, the shape is constant. Each animal and vegetable has the one that characterizes its species, so that no possible mistake can be indulged ; and this applies not only to the whole body, but to every one of its parts, numerous as they are. 3. Size. — The size of an inorganic body is by no means fixed. It may be great, or small, according to the quantity present of the parti- cles that have to form it. A crystal, for example, may be minute, or the contrary, according to the number of saline particles in the solu- tion. On the other hand, organized bodies attain a certain size, — at times by a slow, at others by a more rapid growth, — but in all cases ' Fleming's Philosophy of Zoology, i. 4. Edinburgh, 1822. INORGANIC AND ORGANIZED. 35 tlie due proportion is preserved between the various parts, — between the stem and the root, the limb and the trunk. Each vegetable and each animal has its own size, by which it is known; and although we occasionally meet with dwarf or gigantic varieties, these are unfre- quent, and mere exceptions establishing the position. 4. Chendcal character. — Great difference exists between inorganic and organized bodies in this respect. In the mineral kingdom are found all the elementary substances, or those which chemistry, at present, considers simph ; amounting to at least sixty-two. They are as follows : — Noyi-metullic ladies. Oxygen, hydrogen, nitrogen, sulphur, selenium, phosphorus, chlorine, iodine, bromine, fluorine, carbon, boron, silicon. Metals. Potassium, sodium, lithium, calcium, magnesium, barium, strontium, aluminium, glucinium, zirconium, yttrium, thorium, iron, manganese, zinc, cadmium, lead, tin, copper, bismuth, mercury, silver, gold, platinum, rhodium, palladium, osmium, iridium, nickel, cobalt, uranium, cerium, antimony, arsenic, chromium, molybdenum, tungsten, columbium, tellurium, titanium, vanadium, lautanium, didy- mium, erbium, terbium, niobium, ruthenium, norium, ilmenium, aridium (?), and donarium (?). In the organized, a few only of these elements of matter are met with, viz., oxygen, hydrogen, nitrogen, and carbon, which are always present; and sulphur, phosphorus, chlo- rine, iodine, bromine, fluorine, potassium, sodium, calcium, magnesium, silicon, aluminium, iron, manganese, titanium, and arsenic, which are usually in small proportion. The composition of inorganic bodies is more simple : several con- sist of but one element ; and, when composed of more, the combina- tion is rarely higher than ternary. Organized bodies, on the other hand, are never simple, nor even binary. They are always at least ternary or quaternary. The simplest vegetable consists of a union of oxygen, carbon, and hydrogen ; the simplest animal, of oxygen, hydrogen, carbon, and nitrogen. The composition of the mineral, again, is constant. Its elements have entirely satisfied their affinities ; and all remains at rest. In the organized kingdom, the affinities are not satisfied ; compounds are formed to be again decomposed, and this happens from the earliest period of foetal formation till the cessation of life ; all is in commo- tion, and the chemical character of the corporeal fabric is incessantly undergoing modification. This applies to every organized body; and, accordingly, change of some kind is essential to our idea of active life. In the case of the seed, which has remained unaltered for cen- turies, and subsequently vegetates under favorable circumstances, life may be considered to be dormant or suspended. It possesses vitality, or the power of being excited to active life under favoring influences. In chemical nomenclature, the term element has a different accepta- tion, according as it is applied to inorganic or organic chemistry. In the former, it means a substance, whicli, in the present state of science, does not admit of decomposition. We say, " in the present state of the science," for several bodies, now esteemed compound, were, not many years ago, classed amongst the simple or elementary. It is not much more than forty years since the alkalies were found to be com- posed of two elements. Previously, they were considered simple. In 36 NATURAL BODIES. the animal and the vegetable, we find substances, also called elements, but with the epithet organic prefixed, because they are only found in organized bodies; and are therefore the exclusive products of organi- zation and life. For example, in both animals and vegetables we meet with oxygen, hydrogen, carbon, nitrogen, and diSerent metallic sub- stances : these are chemical or inorganic elements. We further meet with albumen, gelatin, fibrin, casein, &c., substances which constitute the various organs, and have, therefore, been termed organic elements or compowub of organization ; yet they are capable of decomposition ; and in one sense, therefore, not elementary. In the inorganic body, all the elements that constitute it are formed by the agency of general chemical affinities ; but, in the organized, the formation is produced by the force that presides over the formation of the organic elements themselves — the force of life. Hence, the chemist is able to recompose many inorganic bodies ; whilst the pro- ducts of organization and life set his art at defiance. The different parts of an inorganic body enjoy an existence inde- pendent of each other ; whilst those of the organized are materially dependent. No part can, indeed, be injured without the mass and the separated portion being more or less affected. If Ave take a piece of marble, which is composed of carbonic acid and lime, and break it into a thousand fragments, each portion will be found to consist of carbonic acid and lime. The mass will be destroyed; but the pieces will not suffer from the disjunction. They will continue as fixed and unmodified as at first. Not so with an organized body. If we tear the branch from a tree, the stem itself participates more or less in the injury; the detached branch speedily undergoes striking changes; it withers ; becomes shrivelled ; and, in the case of the succulent vege- table, undergoes decomposition ; certain of its constituents, no longer lield in control by vital agency, enter into new combinations, are given off" in the form of gas, and the remainder sinks to earth. Changes, no less impressive, occur in the animal when a limb is separated from the body. The parent trunk suffers ; the system recoils at the first infiiction of the injury, but subsequently arouses itself to a re])aratory effort— at times with such energy as to destroy its own vitality. The separated limb, like the branch, is given up, uncontrolled, to new affinities ; and putrefaction soon reduces the mass to a state in which its previously admirable organization is no longer perceptible. Some of the lower classes of animals may, indeed, be divided with im|)unity ; and with no other effect than that of multiplying the ani- mal in proportion to the number of sections; but these cases are ex- ceptions ; and we may regard the destructive process— set up when parts of organized bodies are separated— as one of the best modes of distinction between the inorganic and the organized classes. 5. Textnre. — In this respect the inorganic and the organized differ considerably— a difference which has given rise to their respective ap- pellations. To the structure of the latter class only can the term texture be with propriety applied. If we examine a vegetable or animal sub- stance with attention, we find that it has a regular and determinate arrangement or structure ; and readily discover that it consists of va- rious parts ;— in the vegetable, of wood, bark, leaves, roots, flowers, INORGANIC AND ORGANIZED. 37 Sec. ; and in the animal, of muscles, nerves, vessels, &c. ; all of whicli appear to be instruments or orrjansfov special purposes in the economy. Hence, tlie body is said to be organized, and the result, as well as the process, is often called organization. Properly, organization means the process by which an organized being is formed ; organism, the result of such process, or organic structure. The particles of matter in an organized body, in many instances, constitute fibres, which interlace and intersect each other in all direc- tions, and form a spongy areolar texture or tissue, of which the various organs of the body are composed. These fibres, and indeed every organized structure, are considered by modern histologists to be formed originally from cellgerms or cytoblasts : the resulting cells assuming an arrangement appropriate to the particular tissue. "A texture," says Mr. Goodsir,' "may be considered either by itself, or in connexion with the parts which usually accompany it. These subsidiary parts may be entirely removed without interfering with the anatomical constitution of the texture. It is essentially non-vascular; — neither vessels nor nerves entering into its intimate structure. It possesses in itself those powers by which it is nourished, produces its kind, and performs the actions for which it is destined, the subsidiary or super- added parts supplying it with materials, which it appropriates by its own inherent powers, or connecting it in sympathetic and harmonious action with other parts of the organism to which it belongs. In none of the textures are these characters more distinctly seen than in the osseous. A well-macerated bone is one of the most easily made, and at the same time one of the most curious of anatomical preparations. It is a perfect example of a texture completely isolated ; the vessels, nerves, membranes, and fat, are all separated; and nothing is left but the non-vascular osseous substance." In the inorganic substance the mass is homogeneous ; the smallest particle of marble consists of carbonic acid and lime ; and all the par- ticles concur alike in its formation and preservation. Lastly, while an inorganic body, of a determinate species, has always a fixed composition, the living being, although constituting a particular species, may present individual differences, which give rise, in the ani- mal, to various tempei-aments, constitutions, &c. 6. Mode of preservation. — Preservation of the species is, in organized bodies, the effect of reproduction. As regards individual preservation, that of the mineral is dependent upon the same actions that eftected its formation; on the persistence of the affinities of cohesion and com- bination that united its various particles. The animal and the vege- table, on the other hand, are maintained by a mechanism peculiar to themselves. From the bodies surrounding them they lay hold of nu- tritious matter, which, by a process of elaboration, they assimilate to their own composition ; at the same time, they are constantly absorbing or taking up particles of their own structure, and throwing them off. The actions of composition and decomposition are constant whilst life ' Anatomical and Pathological Observations, p. 64, Edinburgh, 1845. See also Schwann, Microscopical Researches into the Accordance in the Structure and Growth of Animals and Plants ; translated by Henry Smith. Sydenham Society edit. Loud. 1847. ' S550V 38 NATURAL BODIES. persists ; althougli subject to particular modifications at different pe- riods of existence, and under different circumstances. Again : — the inorganic and organized are alike subject to changes during their existence; but the character of these changes, in the two classes, differs essentially. The mineral retains its form, unless acted upon by some mechanical or chemical force. Within, all the particles are at rest, and no internal force exists, which can subject them to modification. There is no succession of conditions tliat can be termed ages. How different is the case with organized bodies! Internally, there is no rest ; from birth till death all is in a state of activity. The plant and the animal are subject to incessant changes. Each runs through a succession of conditions or ages. We see it successively de- velope its structure and functions, attain maturity, and finall}'' decay. Characteristic differences likewise exist in the external conformation of the beings of the two divisions, as well as in their mode of increase. Inorganic bodies have no covering to defend them ; no exterior enve- lope to preserve their form ; a stone is the same at its centre as at its circumference ; whilst organized bodies are protected by an elastic and extensible covering, differing from the parts beneath, and iuservient to valuable purposes in the economy. Every change to which an inorganic body is liable must occur at its surface. It is there that the particles are added or abstracted when it experiences increase or diminution. Increase — for growth it can scarcely be termed — takes place by accretion or juxtaposition^ that is, by the successive application of fresh particles upon those that form the nucleus ; and diminution in bulk is produced by the removal of the external layers or particles. In organized substances, increase or growth is caused by particles deposited internally, and diminution by particles subtracted from within. We see them, likewise, under two conditions, to which there is nothing similar in the mineral kingdom — healthy and disease. In the former, the functions are executed with freedom and energy ; in the latter, with oppression and restraint. 7. Termination. — Every bod}-, inorganic or organized, may cease to exist, but the mode of cessation varies greatly in the two classes. The mineral is broken down by mechanical violence ; or it ceases to exist in consequence of modifications in the affinities, which held it concrete. It has no fixed duration ; and its existence may be terminated at any moment, when the circumstances, that retained it in aggregation, are destroyed. The vegetable and the animal, on the other hand, carry on their functions for a period only which is fixed and determinate for each species. For a time, new particles are deposited internally. The bulk is augmented, and the external envelope distended, until maturity or full developement is attained ; but, after this, decay commences ; the functions^ are exerted with gradually diminishing energy ; the fluids decrease in quantity; and the solids become more rigid — circumstances premonitory of the cessation of vitality. This term of duration is different in different species. Whilst many of the lower classes of animals and vegetables have but an ephemeral existence, some of the more elevated individuals of the two kingdoms outlive a century. 8. Motive forces. — Lastly, observation has satisfactorily proved, that there are certain forces, which affect matter in general, inorganic as well ANIMALS AND VEGETABLES. 89 as organized; and tliat, in addition to these, organized bodies possess a peculiar force or forces, which modify them in a remarkable manner. Hence, we have general forces ; and special or vital; the first acting upon all matter, the dead and the living, and including the forces of gravi- tation, cohesion, cJtemical affinity, &c. ; the latter appertaining exclusively to liviug beings. Such are the chief distinctions to be drawn between the two great divisions of natural bodies; the inorganic and the organized. By the comparison which has been instituted, the objects of physiology have been indicated. To inquire into the mode in which a living being is lorn, nourished, reproduced, and dies, is the legitimate object of the science. We have, however, entered only into a comparison between the inor- ganic and the organized. The two divisions constituting the latter class difter also materially from each other. Into these difi'erences we shall now inquire. 2. DIFFEEENCE BETWEEN ANIMALS AND VEGETABLES. The distinctions between the divisions of organized bodies are not so rigidly fixed, or so readily appreciated, as those between the inor- ganic and the organized. There are certain functions possessed by both ; hence called vegetative, 'plastic, or organic, — nutrition and repro- duction, for example; but vegetables are endowed with these only. All organized bodies must have the power of assimilating foreign mat- ters to their own substance, and of producing a living being similar to themselves; otherwise, the species, having a limited duration, would perish. In addition to these common functions, animals have sensation and voluntary motion ; by the possession of which they are said to be animated. Hence, they are termed animals, and the condition is called animality. This division of the functions into animal and organic has been adopted, with more or less modification, by most physiologists. Between animals and vegetables, situate high in their respective scales, no confusion can exist. The characters are obvious at sight. No one can confound the horse with the oak; the butterfly with the potato. It is on the lower confines of the two kingdoms that we are liable to be deceived. Many of the zoophytes have alternately been considered vegetable and animal; *but we are generally able to classify any doubtful substance with accuracy ; and the following are the prin- cipal points of difference. 1. Composition. — It was long supposed, that the essential difference between animal and vegetable substances consists in the former con- taining nitrogen; whilst the latter do not.' Modern researches have, however, satisfactorily shown, that the organized portions of animals and vegetables are essentially alike ; and consist of the four elements, — carbon, oxygen, hydrogen, and nitrogen ; whilst the unorganized — as the fat of the animal, and the starch of the vegetable — are composed of three elements only — carbon, oxygen, and hj'-drogen. Still, their intimate composition must vary greatly; for, when burning, the animal substance is readily known from the vegetable; — a fact, which, as Dr. Fleming^ has remarked, is interesting to the young naturalist, if uncer- ' Braehet still adheres to this distinction. Pliysiologie Llemeutaire de I'llomme, 2de edit., i. 21. Paris et Lj'on, 185.5. 2 Philosophy of Zoology, i. 41, Edinburgh, 1822. 40 NATURAL BODIES. tcain to which kingdom to refer any substance met with in his researches. The smell of a burnt sponge, of coral, or other zoophytic animal, is so peculiar, that it can scarcely be mistaken for that of a vegetable body in combustion. According to Mulder,' there is this real difference between plants and animals in composition, that cellulose (C^''H^^O^^) forms the principal part of the cellular mass in plants ; whilst in ani- mals the primary material is gelatin (C'^H'°N^O^); and to this rule, he says, no exception has yet been discovered either among animals or plants. Yet amylaceous or amyloid bodies — corpora sen corpiiscula amylacea — of microscopic size, are found in the animal body; chiefly in the human brain and spinal marrow, in the ependyma ventriculorum and its prolongations, mingled with the proper nerve elements, and having most of the chemical characters of cellulose ;^ Mr. Busk indeed affirms, that they are absolutely identical in every property, whether optical, physical, or chemical, with starch.^ 2. 'Texture. — In this respect, important differences are observable. Both animals and vegetables consist of solid and fluid parts. In the former, however, the fluids bear a large proportion : in the latter, the solids. This is the cause, why decomposition occurs so much more rapidly in the animal than in the vegetable; and in the succulent more than in the dry vegetable. If we analyze the structure of the vege- table, we cannot succeed in detecting more than one elementary tissue, which is vesicular or areolar^ or arranged in vesicles or areolae, and appears to form every organ of the body; whilst, in the animal, we ■ discover at least three of these anatomical elements, the areolar — analo- gous to that of the vegetable; — the muscular^ and the nervoxis. The vegetable again has no great splanchnic cavities containing the chief organs of the body. It has a smaller number of organs, and none that are destined for sensation or volition ; in other words, no brain, no nerves, no muscular sj'stem; and the organs of which it consists are simple, and readily convertible into each other. But these differences in organization, striking as they may appear, are not sufficient for rigid discrimination, as they are applicable only to the upper classes of each kingdom. In many vegetables, the fluids appear to preponderate over the solids ; numerous animals are devoid of muscular and nervous tissues, and ajiparently of vessels and distinct organs; whilst ]\[^[. Datrochet,'* Brachet,^ and others,® admit the exist- ence of a rudimental nervous system even in vegetables. ' Tlio Chemistry of Animal and Vegetable Physiology ; translated by Fromberg, p. 91. Kdinburgh and Ij(in(b)n, lS4t). ^ Yirchow, Arcliiv. fiir i)athnl. Anat., &c. Leipzig, 1853. Translated in Quarterly Jour- nal of Microscopic Science,. July, 1855, p. 284. — KiilUkor, Mikroskopische Anatomic, ii. 501. Leipzig, 1850. And tlie translation of the same by Messrs. Busk and Huxley, Sydenham Society edition, i. 458. London, 1853. And American edition, the same, by J. Da Costa, M. D., p. 402. I'hilailelphia, 1854.— Thos. Albert Carter, Edinb. Med. Journ., August, 1853, y. 130, On tlie Dill'usion of Starch-corpuscles in the Animal Tissues. ' Oiiarterly .Ji)unial of Microscopical Science, January 1854. ♦ Kecherches Anat<)nu(iues t>t Physiologiques sur la Structure Intime des Animaux, et des Vegetaux, et sur leur Motilite. Paris, 1824. * Recherches Experimontales sur les Fonctions du Systdme Nerveux Ganglionnaire, &c., 2de edit. Paris et Lyon. 1837. And Physioloirie l.lenunitaire de I'Ho'mme, 2de 6dit., i. (j4. Paris et Lyon, 1855. 6 Sir J. E. Smith, Introduction to Botany, 7th edit., by Sir W. J. Hooker, p. 40. London, 1833. ANIMALS AND VEGETABLES. 41 3. Sensation and voluntary motion. — There is one manifest distinction lietween animals and vegetables. Whilst the latter receive their nutri- tion from the objects around them — irresistibly and without volition, or the participation of mind; and whilst the function of reproduction is effected Avithout the union of the sexes, both volition and sensation are necessary for the nutrition of the former, and for acts that are requisite for the reproduction of the species. Hence, the necessity of two faculties or functions in the animal, that are wanting in the vege- table, — sensibility^ or the faculty of consciousness and feeling; and motility, or the pow0r of moving at will the whole body or any of its parts. Vegetables are possessed of spontaneous, but not of voluntary motion. Of the former we have numerous examples in the direction of the branches and upper surfaces of the leaves, although repeatedly disturbed, to the light; and in the unfolding and closing of flowers at stated periods of the day. This, however, is distinct from the sensi- Ijility and motility that characterize the animal. By sensibility man feels his own existence — becomes acquainted with the universe — appreciates the bodies that compose it; and experiences all the desires and inward feelings that solicit him to the performance of those ex- ternal actions, which are requisite for his preservation as an individual, and as a species ; and by motility he executes those external actions which his sensibility may suggest to him. By some naturalists it has been maintained, that those plants, which are borne about on the waves, and fructify in that situation, exhibit examples of the locomotility, which is described as charac- ■ teristic of the animal. One of the most interesting novelties in the monotonous occurrences of a voyage across the Atlantic towards the Gulf of Florida is the almost interminable quantity of Fucus natans, Florida iveed or Oulf weed, with which the surftice of the ocean is covered. But how different is this from the locomotion of animals ! It is a subtlety to conceive them identical. The weed is passively and unconsciously borne whithersoever the winds and the waves may urge it ; whilst animal locomotion requires the direct agency of voli- tion, of a nervous system that can excite, and of muscles that can act under sucli excitement. The spontaneity and percejAivity of plants must also be explained in a different manner from the elevated function of sensibility on which we shall have to dwell. These properties must be referred to the fact of certain vegetables being possessed of the faculty of contracting on the application of a stimulus, independently of sensation or conscious- ness. If we touch the leaf of the sensitive plant, Mimosa pudica, the various leaflets collapse in rapid succession. In the barberry bush, Berber is vulgar is, we have another example of the possession of this faculty. In the flower, the six stamens, spreading moderately, are sheltered under the concave tips of the petals, till some extraneous body, as the feet or trunk of an insect in search of honey, touches the inner part of each filament, near the bottom. The susceptibility of this part is such, that the filament immediately contracts, and strikes its anther, full of pollen, against the stigma. Any other part of the filament may be touched without this result, provided no concussion be given to the whole. After a while, the filament retires gradually, 42 NATURAL BODIES. and may be again stimulated ; and when each petal, with its annexed filament, has fallen to the ground, the latter, on being touched, shows as much sensibility as ever.' These singular effects are produced by the power of contractility or irritability, the nature of which will fall under consideration hereafter. It is possessed equally by animals and vegetables, and is essentially organic and vital. This power, we shall see, needs not the interven- tion of volition ; it is constantly exerted in the animal without con- sciousness, and therefore necessarily without volition. Its existence in vegetables does not, consequently, demonstraH that they are pos- sessed of consciousness, 4. Nutrition. — A great difference exists between plants and animals in this respect. The plant, being fixed to the soil, cannot search after food. It must be passive ; and obtain its supplies from the materials around, and in contact with it ; and the absorbing vessels of nutrition must necessarily open on its exterior. In the animal, on the other hand, the aliment is scarcely ever found in a state fit for absorption ; it is crude, and in general — Ehrenberg^ thinks always — requires to be received into a central organ or stomach, for the purpose of under- going changes, by a process termed digestion, which adapts it for the nutrition of the individual. The absorbing vessels of nutrition arise, in this case, from the internal or lining membrane of the alimentary tube. The analogy that exists between these two kinds of absorption is great, and had not escaped the attention of the ancients : — Qaem- admochim terra arhoribus, ita animalihus ventriculus sicut humus''^ was an aphoristic expression of universal reception. With similar feel- ings, Boerhaave asserts, that animals have their roots of nutrition in their intestines ; and Dr. Alston* has fancifully termed a plant an inverted animal. After all, however, the most essential difference consists in the steps that are preliminary to the reception of food. These, in the animal, are voluntary — requiring prehension ; often locomotion ; and always consciousness. 5. Reproduction. — In this functi(Mi we find a striking analogy be- tween animals and vegetables ; but differences exist, which must be referred to the same cause that produced many of the distinctions already pointed out, — the possession, by the animal, of sensibility and locomotility. For example, every part of the generative act, as before remarked, is, in the vegetable, without the perception or volition of the being :— the union of the sexes, fecundation, and the birth of the new individual are alike automatic. In the animal, on the other hand, the approximation of the sexes is always voluntary, and effected con- sciously :— the birth of the new individual being not only perceived, but somewhat aided by volition. Fecundation alone is involuntary and irresistible. Again, in the vegetable the sexual organs do not exist at an early period; and are not developed until reproduction is practicable. They ' Sir J. E. Smith's Introduction to Botany, p. 325. 2 Edinb. New I'liilosojihifal Journal, for Sept., 18S1 ; and Jan., 183S, p. 232. » Tirocinium Botauicum Edinburgun^^e, Svo., Edinli., 1753. MATEEIAL COMPOSITION OF MAN". 43 are capable of acting for once only, and perish after fecundation ; and if the plant be vivacious, they fall off after each reproduction, and are annually renewed. In the animal, on- the" contrary, they exist from the earliest period of foetal development, survive repeated fecundations, and continue during the life of the individual. Lastly, the possession of sensibility and locomotility leads to other characteristics of animated beings. These functions are incapable of constant, unremitting exertion. Sleep^ therefore, becomes necessary. The animal is also capable of exjiression, or of language, in a degree proportionate to the extent of his sensibility, and of his power over the beings that surround him. But these differences in function are not so discriminate as they may appear at first. There are many animals, that are as irresistibly at- tached to the soil as the vegetables themselves. Like the latter, they must, of necessity, be compelled to absorb their food in the state in which it is presented to them. Sensibility and locomotility appear, in the zoophyte, to be no more necessary than in the vegetable. No nervous, no muscular system is required ; and, accordingly, none can be traced in them ; whilst many of those spontaneous motions of the vegetable, to which allusion has been made, have been considered by some to indicate the first rudiments of sensibility and locomotility ; and Linnaeus' has regarded the closure of the flowers towards night as the sleep, and the movements of vegetables, for the approximation of the sexual organs, as the marriage, of plants. II. GENERAL PHYSIOLOGY OF MAN.2 The observations made on the differences between animals and vege- tables have anticipated many topics, that would require consideration under this head. The general properties, which man possesses along with other animals, have been referred to in a cursory manner. They will now demand a more special investigation. 1. MATERIAL COMPOSITION OF MAN. The detailed study of human organization is the province of the anatomist — of its intimate composition, that of the chemist. In ex- plaining the functions executed by the various organs, the physiologist will frequently have occasion to trench upon both. The bones, in the aggregate, form the skeleton. The base of the skeleton is a series of vertehrce, with the skull as a capital — itself re- garded as a vertebra. This base is situate on the median line through the whole trunk, and contains a cavity, in which are lodged the brain and spinal marrow. On each side of this, other bones, which by some have been called ajipendices, are arranged in pairs. Upon the skeleton are placed muscles, for moving the different parts of the body; and for changing its situation w^ith regard to the soil. The body is divided into trunk and limbs. The trunk, which is the principal portion, is composed of three splanchnic cavities, the abdomen, tliorax, and head, ' Amccnit. Academ., torn. iv. ' See, on all this suhjedt, Robiu and Vordeil, Traite do Chimie Anatomiquc et Pliy- siologi(iue, &c. Paris 1853. 44 MATEEIAL COMPOSITION OF MAN. situate one above the other. They contain the most important organs of the body — those that effect the functions of sensibility, digestion, respiration, circuhition, &;c. The liead comprises the /ace, in which are the organs of four of the senses — sight, hearing, smell, and taste, — and the cranium^ which lodges the brain — the organ of the mental manifestations, and the most elevated part of the nervous system. The thorax or chest contains the lungs — organs of respiration — and the heart, the central organ of the circulation. The abdomen contains the principal organs of digestion, and (if we include in it the pelvis), those of the urinary secretion and of generation. Of the limbs, the upjjer, suspended on each side of the thorax, are instruments of prehension ; and are terminated by the hand, the great organ of touch. The loiver are beneath the trunk ; and are agents for supporting the body, and for locomotion. Vessels, emanating from the heart, are distributed to every part — conveying to them the blood necessary for their life and nutrition : these are the arteries. Other vessels communicate with them, and convey the blood back to the heart — the veins; whilst a third set arise in the tissues, and convey into the circulation, by a particular channel, a fluid called lymp)h — whence they derive the name lymphatics. Nerves, communicating with the great central masses of the nervous system, are distributed to every part; and lastly, a membrane or layer, possessed of acute sensibility — the skin — serves as an outer envelope to the whole body. It was before observed, that two kinds of elements enter into the composition of the body — the chemical or inorganic; and the organic, which are compound, and formed only under the force of life. The chief Chemical or Inorganic Elements met with are: oxygen, hydrogen, carbon, nitrogen, phos|)horus, calcium; and, in smaller quan- tity, sulphur, iron, manganese, calcium, silicium, aluminium, chlorine ; also, sodium, magnesium, &c. &c. 1. Oxygen. — This is widely distributed in the solids and fluids ; and a constant supply of it from the atmosphere is indispensable to animal life. It is almost always found combined with other bodies; often in the form of carbonic acid, — that is, united with carbon. In a separate state it is met witli in the air-bag of fishes, in which it is found varying in quantity, according to the species, and the depth at which the fish has been caught. 2. Hydrogen. — This gas occurs universally in the animal kingdom. It is a constituent of all the fluids, and of many of the solids ; and is generall}' in a state of combination with carbon. In the human intes- tines it has been fountl pure, as well as combined with carbon and sul- phur. 3. Carbon. — This substance is met with under various forms, in both fluids and solids. It is most frequently found under that of carbonic acid. Carbonic acid has been detected in an uncorabined state in urine by Prout; and in the blood by Vogel.' It exists in the intestines of animals; but is chiefly met with in animal bodies, in combination with the alkalies or earths; and is emitted by all animals in the act of re- spiration. ' Annals of Philosophy, vii. 56. I MATERIAL COMPOSITION OF MAN. 45 4. Nitrogen. — This gas is likewise widely distributed as a component of animal substances, and especially of the tissues. It occurs in an uncorabined state, in the swimming-bladder of certain fishes. 5. Phosphorus is an essential constituent of neurine ; and is found united with oxygen, in the state of phosphoric acid, in many of the solids and fluids. It is this acid that is combined with the earthy mat- ter of bones ; and with potassa, soda, ammonia, and magnesia, in other parts. It is supposed to give rise to the luminousness of certain ani- mals — as of the fire-fly, Pyrosoma Atlanticurn, &c. — but nothing pre- cise is known on this subject. 6. Calcium. — This metal is found in the animal economy in the state of oxide — lime; and it is generally united with phosphoric or carbonic acid. It is the earth, of which the hard parts of animals are constituted. 7. Sulphur is not met with extensively in animal solids or fluids; nor is it often found free, but usually in combination with oxygen united to soda, potassa, or lime. It seems to be an invariable concomi- tant of albumen; and is found in the intestines, in the form of sulpha- retted hydrogen ; and as an emanation from fetid ulcers. 8. Iron. — This metal has been detected in the colouring matter of the blood ; in bile, and in milk. In the first of these fluids it was, for a long time, considered to be in the state of phosphate or sub-phos- phate. Berzelius^ showed, that this was not the case ; that the ashes of the colouring matter always yielded oxide of iron in the proportion of 1 -200th of the original mass. That distinguished chemist was, how- ever, unable to detect the condition in which the metal exists in the blood; and could not discover its pi'esence by any of the liquid tests. Subsequently, Engelhart showed, that the fibrin and albumen of the blood, when carefully separated from colouring particles, do not con- tain a trace of iron ; whilst he could procure it from the red corpuscles by incineration. lie also succeeded in proving its existence in the red corpuscles by liquid tests ; and his experiments were repeated, with the same results, by Eose of Berlin,^ In milk, iron seems to be in the state of phosphate, 9. Manganesium has been found in the state of oxide, along with iron, in the ashes of the hair; in bones, in gall-stones, and in the blood. 10. Copper and lead. — It was conceived by M. Devergie, that copper and lead may exist naturally in the tissues;' but MM, Flandin and Danger, and a commission of the Academic Eoyale de Mcdecine of Paris, were unable to confirm the existence of copper; and the results of the investigations of Professor F. de Cattanei di Momo,^ of Pavia, seem to j)rove the non-existence of lead also. M. Parse, however, in a paper read before the Royal Acadera}'' of Sciences of Paris, in August, 1843, states, that he found both metals in the bodies of two ' Medico-Cliinirgical Transact., vol. iii, ^ Turner's Chemistry, fifth ed., p. 963. London, 1834. 3 Bullet, de I'Academ. Royale de Medecine, 11) Fevr., 183J1, * Annali Universal! di Mediciua, Aprile, 1H40; cited in British and Foreign Medical Review, Jan., 1841, p. 220'. 46 MATERIAL COMPOSITIOX OF MAN. persons, to whom they could not have been given for poisons. The researches of Signor Cattanei di Momo appeared to prove that these metals do not exist in the bodies of new-born children or infants; and M. J. Rossignon has offered a solution as to the probable source of the copper, which he found not onl}^ in the blood and muscles of the dog, but in many articles of vegetable and animal food ; in gelatin from bones, for example, in sorrel, chocolate, bread, cofiee, succory, madder, and sugar. The ashes obtained from starch sugar yielded 4 per cent. of copper; those of gelatin, 0"03 per cent.; and those of bread, O'OOo to 0"006 per cent.' It is now generally considered to be present in the human liver,^ and M. E. Millon^ asserts, that human blood invariably contains lead, copper, silica, and manganese. 11. Silicon. — Silica is found in the hair, bones, blood, urine, and in urinary calculi. 12. Chlorine. — In combination with hydrogen, and forming chloro- hydric acid^ chlorine is met with in most of the animal fluids. It is generally united with soda. Free chlorohydric acid has also been found by Dr. Prouf in the stomach of the rabbit, hare, horse, calf, and dog; and he has discovered the same acid in the sour matter ejected from the stomachs of those labouring under indigestion. Mr. Children, and Messrs. Tiedemann and Gmelin,* made similar observations; and Professor Emmet and the author^ found it in considerable quantity in the healthy gastric secretions of man. 13. Fluorine. — This simple substance has been found combined with calcium — -Jluoride of calcium — in the enamel of the teeth, bones, and urine. 14. Sodium. — Oxide of sodium, soda^ forms part of all the fluids. It has never been discovered in a free state ; but it is united (without an acid), to albumen. Most frequently, it is combined with chlorine, and phosphoric acid ; less frequently, with lactic, carbonic, and sulphuric acids. Chloride of sodium is contained in most of the animal secre- tions; and from its decomposition may result the chlorohydric acid of the gastric juice, and a part of the soda of the bile and other fluids. 15. Potassium. — The oxide, potassa, is found in many animal fluids, but always united with acids — sulphuric, chlorohydric, phosphoric, &c. It is much more common in the vegetable kingdom; and hence one of its names — vejeiahle alkali. 10. Jfagnesium. — The oxide, viagnesia^ exists sparingly in bones, and in some other parts; but always in combination with phosphoric acid, and appears to be always associated with calcium. 17. Aluminium. — Alumina is said by Morichini to exist in the ena- mel of the teeth. Fourcroy and Yauquelin found it in the bones; and ' Lou.l. M.mI. Traz., Dec. 1, 1843, from Gazette M.^licale de Paris, and Mr. Paget, Rep. on AnatoTiiy and Physiology, 1843-4, in Brit, and For. Med. Rev., Jan., 1845, p. 249. " Kirk.-s and Patret, Manual of Physiology, 2d Amer. edit., p. 29, Philad., 1853. ' Coniptes Rcndiis, Pans, 1848. * Philiisuph. Transact, for 1824, p. 45. 6 Reelierehes KxiH-rimentales, &c., sur la Digestion, trad, par A. G. L. Jourdan. Art. 4, p. 94, Paris, 1S27. " See under the head of " Digestion,'' and tlie author's Human Health, p. 191, Phila- delphia, 1844. ORGANIC ELEMENTS. 47 Jolin, in white hairs. According to Schlossberger, it is in the flesh of fishes.' 18. Titanium. — Dr. Rees affirms, that he detected it in salts obtained from the supra-renal capsules. 19. Arsenic. — It was asserted, by M. Orfila, that arsenic exists natu- rally in the human body ; and that it is a normal constituent of human bones. Subsequent experiments, however, performed by M, Orfila himself, have shown that there was fallacy in his first observations.^ Organic Elements, proximate principles or compounds of organiza- tion., are combinations of two or more of the elementary substances, in definite proportions. Formerly, four only were admitted — gelatin, fibrin, albumen, and oil. Of late, however, organic chemistry has jtointed out others, which are divided into two classes — first, those that contain nitrogen, as albumen, gelatin, fibrin, osmazome, mucus, casein, urea, uric acid, red colouring principle of the blood, yellow colouring principle of the bile, &C. ; and secondly, those that do not contain nitro- gen — as olein, margarin, stearin, the fatty matter of the brain and nerves, acetic, oxalic, benzoic, and lactic acids, sugar of milk, sugar of diabetes, hepatic sugar, picromel, colouring principle of the bile, and that of other solids and liquids, &c. a. Organic Elements that contain Nitrogen. 1. Protein. — Modern researches have appeared to show, that the chief proximate principles of animal tissues, and those that have been regarded as highly nutritious among vegetables, have almost identi- cally the same composition ; and are modifications of a principle to which Mulder — its discoverer — gave the name Protein. If animal albumen, fibrin, or casein, be dissolved in a moderately strong solution of caustic potassa, and the solution be exposed for some time to a high temperature, these substances are decomposed. The addition of acetic acid to the solution causes, in all three, the separation of a gelatinous translucent precipitate, which has exactly the same character and com- position, from whichsoever of the solutions it is obtained. It may be procured, too, from globulin of blood, and from vegetable albumen.' The chemical relations of protein, especially in regard to oxygen, are full of interest. The products of its oxidation, binoxide and trit- oxide of protein, occur constantly in the blood. They arc formed in the lungs from fibrin ; which, in a moist state, possesses the property of absorbing oxygen. Fibrin, oxidized in the lungs, is, according to Mulder, the principal — if not the only— carrier of the oxygen of the air in the blood to the tissues ; and it is from this substance, especially, that the secretions are formed. In inflammatory conditions, a much larger quantity of protein, in an oxidized state, is contained in the ' Henle, AUgemeine Anatomie, s. 4. Leipz., 1841, or Jourdaii's translation, i. 2, Paris, 1843. ^ Rapport de I'Academie Royale de Medecine, Juillet, 1841 ; Taylor's Medical Juris- prudence, by Dr. Griffith, p. 133, Pliilada., 1845 ; and Simon, Animal Chemistry, Syden- ham Soc. edit., p. 4, Lond., 1845, or Amer. edit., Pliilad., 1845. ^ Liebig, Animal Chemistry, Gregory's and Webster's edit., p. 100. Cambridge, 1842. / 48 MATERIAL COMPOSITION OF MAX. T)lood than in healtli ; and tliis, according to Mulder, gives occasion to the bufty coat.^ The following substances may be regarded as modifications or com- binations of protein. They are composed of it and of a small quan- tity of phosphorus, or of sulphur, or botli.^ a. Albumen. — This is one of the most common organic constituents; and appears under two forms — liquid and concrete. In its purest state, the former is met with in white of egg — whence its name ; in the serum of the blood ; the lymph of the absorbents ; the serous fluid of the great splanchnic cavities and of the areolar membrane ; and in the synovial secretion. It is colorless and transparent ; without smell or taste ; and is coagulated by acids, alcohol, ether, metallic solutions, infusion of galls, and by a temperature of 158° Fahrenheit. A very dilute solution, however, does not become turbid until it is boiled. It is excreted by the kidneys in large quantities, in the disease, which, owing to its presence in the urine, has been called Albuminuria. Concrete, coagulated, or solid albumen, is white ; tasteless ; and elastic ; insoluble in water, alcohol, or oil ; but readily soluble in alkalies. Albumen is always combined with soda. It exists in abundance — both the liquid and concrete — in different parts of the animal body. Hair, nails, and horn, consist of it ; and it is, in some form or other, a constituent of many tumours. In the advanced chyliferous vessels albumen is found in quantity ; and it is probable that every proteinaceous aliment, and perhaps those that are not proteinaceous, is reduced to the form of albumen in the process of digestion, so that it becomes the nutritious constituent of whatever fluid is absorbed for the formation of tissue. Albuminose or 2-)eptone has considerable analogy with albumen and casein. Its non-coagulation by heat distinguishes it from the former ; the precipitate which it forms with acetic acid, and which redissolves in an excess of the acid, distinguishes it from the latter. It is found in the chyme from the digestion of nitrogenized matters; and passes into the blood, where it is found in the proportion of from four to six parts in the 1,OOU.^ b. Fibrin. — This proximate principle exists in the chyle ; enters into the composition of the blood ; forms the chief part of muscular flesh ; and may be looked upon as one of the most abundant animal substances. It is obtained by beating the blood with a rod, as it issues from a vein. The fibrin attaches itself to each twig in the form of red filaments, which may ^be deprived of their colour by repeated washing with cold water. Fibrin is solid; white; flexible; shghtly elastic ; insipid; in- odorous ; and heavier than water. It is neither soluble in water, alco- hol, nor acids ; dissolves in liquid potassa or soda, in the cold, without much change ; and, when warm, becomes decomposed. Fibrin constitutes the buffy coat of blood ; it is thrown out from the bloodvessels, as a secretion, in many cases of inflammation ; and becomes subsequently organized. ' Simon, Animal Cliemistrj, Sydeuliam Soc. edit., p. 12, London, 1845 ; or Ameii.'an edit., Philadelphia, 1845. * Henle, op. cit., p. 31. 3 L. A. Segond, Traite d'Anatomie GenSrale, p. 49. Paris, 1854. ORGANIC ELEMENTS. 49 There is no mode of distinguishing liquid fibrin from liquid albumen, except by the spontaneous coagulation of the former. Consequently, according to Henle,' if a liquid does not coagulate of itself, it does not contain fibrin. A very small quantity, however, of fibrin may be so dissolved in serous fluid, that it will not coagulate.^ The change of albumen to fibrin has generally been regarded as the first important step in the process of assimilation, fibrin being endowed with much higher organizable properties than albumen. This has been attributed to some influence exerted upon albuminous fluids by the living sur- faces over which they pass, but reasons have been brought forward for the belief, that it is rather in a state of transition towards the fibro- gelatinous textures than towards those of the cellulo-albuminous tj^pe; and Dr. Carpenter,^ who was a strenuous supporter of the former doc- trine, now maintains the latter: and thinks, that we seem to be justified in regarding fibrin as the special pabulum of those connective or gelatinous tissues whose physical offices in the economy are so import- ant, whilst their vital endowments are so low — a view which the author is, as yet, b}'' no means prepared to adopt. More probable is that of Mr. Simon,** that the fibrin of the blood may have arisen in it from its own decay, or have reverted to it from the waste of the tissues ; when, amongst other reasons, we consider the small quantity of fibrin in the blood, so inadequate, apparently, for the purposes of nutrition, and that its amount is not diminished by bloodletting, or by starvation ; but, on the contrary, has been observed to be greatly increased under such circumstances. The correspondence of fibrin with albumen is shown by the circum- stance, that it may be wholly dissolved in a solution of nitrate of po- tassa, and that this solution greatly resembles a solution of albumen, and is coagulable by heat. This happens, however, only to the ordi- nary fibrin of venous blood. That which is obtained from arterial blood or from the buff'y coat ; or which has been exposed for some time to the air, is not thus soluble, the difference appearing to depend upon the larger quantity of oxygen contained in the latter ; for a solution of venous fibrin in nitre, contained in a deep cylindrical jar, allows a pre- cipitate in fine flocks to fall gradually, provided the air has access to the surface ; but not if its access be prevented. This precipitate is insoluble in the solution of nitre, and possesses the properties of arterial fibrin.* Hence, Dr. Carpenter* has remarked, it might be inferred, that the fibrin of venous blood most nearly resembles albumen ; whilst that of arterial blood, and of the buffycoat, contains more oxygen, and is more highly animalized [?] ; and that the matter of the red corpuscles is not the only constituent of the blood, which undergoes a change in the respiratory process. c. Casein, Caseum, Caseous matter. — This substance exists in greatest ' Op. cit.,p. 38. 2 Dr. Buchanan, Lond. Med. Gaz. for 1836, pp. 52 and 90, and ibid, for 1845, p. G17. 3 Principles of Human Physiology, Amer. edit., p. 21(5. Philad., 1855. * Lectures on General Pathology, Amer. edit., p. 45. Philad., 1852. * Scherer, Chemisch-physiologische Untersucliungen, Annalen der Chemie, &c., Oct. 1841, cited in Graham's Chemistry, Amer. edit., p. 692. Philad., 1843. « Principles of Human Physiology, 2d edit., p. 479. Philad., 1845. VOL. I.— 4 I 50 MATERIAL COMPOSITIOISr OF MAN. abundance in milk; and is the basis of cheese. It is found also in blood, saliva, bile, pancreatic juice ; in pus, tubercular matter, &c. To obtain it, milk must be left at rest, at the ordinary temperature, until it is coagulated ; the cream that collects on the surface must be taken off; the clot well washed with water, drained upon a filter, and dried. The residuum is pure casein. It is a white, insipid, inodorous sub- stance, insoluble in water, but readily soluble in the alkalies, especially in ammonia. It possesses considerable analogy with albumen. Prout ascribes the characteristic flavor of cheese to the presence of caseate of ammonia. Until recently it was believed that vegetable albumen and fibrin difier from animal albumen and fibrin ; but Mulder showed that this is not the case ; and casein, which agrees with the others in composi- tion, has been found by Liebig in the vegetable. Legnmin is vegetable casein. Of late, the views of Mulder as to the very existence of pro- tein have, however, been combated by Liebig and Th. Fleitmann and others;' but still — as Messrs. Kirkes and Paget^have remarked — there seems sufficient probability in those views to justify the received use of the term '■'■protein comiwunds,''^ in speaking of the class, including fibrin, albumen, and others, to which the name of ^^ albuminous com- 2)ounds''^ was formerly applied. 2. Globulin. — The globulin of Berzelius consists of the envelopes of the blood corpuscles, and of the part of their contents that remains after the extraction of the hcematin. The two constitute hcemato- globulin. M. Lecanu regards globulin as identical with albumen; according to Mulder, it belongs to the combinations of protein. Simon terms it blood casein, and Henle' thinks it probable, that it is in reality only albumen with the membranes of the blood corpuscles. Berzelius considers the crystalline lens to be composed of the same substance. 3. Pepsin. — This substance, to which Eberle gave the name, was discovered by Schwann. It seems to be a modification of protein, but has not been much examined. It is contained in the gastric juice ; and its physiological properties will be described under the head of Digestion. It greatly resembles albumen ; coagulates by heat and alcohol ; and loses its solvent virtues. It is best procured by digest- ing portions of the mucous membrane of the stomach in cold water, after they have been macerated for some time in water at a tempera- ture between 80° and 100° of Fahrenheit. The warm water dissolves various substances as well as some of the pepsin; but the cold water takes up little more than the pepsin, which is obtained, by evaporating the cold solution, in the form of a grayish-bro^\^l viscid fluid. The addition of alcohol throws down the pepsin in grayish-white flocculi ; and one part of the principle thus prepared, when dissolved in even 60,000 parts of water, will digest meat and other alimentary substances. Liebig doubts the existence of pepsin as a distinct compound. Ac- ' Sclierer, in Canstatt und Eisenmann's Jaliresbericlit liber die Fortscliritte in der Biologie im Jahre, 1847, s. 82. Erlangen, 1848. " Cette substance generale," says Brachet, "adoptee en Allemagne, est encore tine probleme." Physiologie Elementaire de I'Homme, 2de edit., Paris et Lyon, 1855. 2 Manual of Physiology, 2d Amer. edit., p. 24, Philad., 1853. ' Op. cit., p. 53. \ ORGANIC ELEMENTS. 51 cording to liim — as explaiued hereafter — the solv^ent power of the gastric juice is owing to the gradual decomposition of a matter dis- solved from the lining membrane of the stomach, aided by oxygen introduced into the saliva. 4. Gelatin. — This is the chief constituent of areolar tissue, skin, tendons, ligaments, and cartilages. The membranes and bones also contain a large quantity of it. It is obtained by boiling these sub- stances for some time in water ; clarifying the concentrated solution ; allowing it to cool, and drying the substance, thus obtained, in the air. In this state it is called glue ; in a more liquid form, jelly. Gelatin dissolves readily in hot water ; is soluble in acids and alkalies ; insoluble in alcohol, ether, and in fixed and volatile oils. Alcohol precipitates it from its solution in water. It is not a compound of protein ; hence it has been concluded, that it cannot yield albumen, fibrin, or casein ; and, therefore, that blood cannot be formed of it. The animal system, it has been maintained, can convert one form of protein into another, but cannot form protein from compounds that do not contain it. This deduction — as stated hereafter — is probably too hast}^ It is admitted, that gelatin may be produced from fibrin and albumen ; since, in animals that are fed on these alone, the nutrition of the gelatinous tissues does not seem to be impaired ; and it is as easy to conceive that gelatin may go to the formation of the proteinaceous tissues. Gelatin, nearly in a pure state, forms the air-bag of different fishes, and is well known under the name of isinglass. It is used extensively in the arts, on account of its adhesive quality, under the forms of glue and size. What is called portable soup is dried jelly, seasoned with various spices. 5. Gliondrin. — This was first discovered by J. Miiller. It is obtained by boiling the cornea, the permanent cartilages, and the bones before ossification. It is a variety of gelatin. 6. Osmazome. — This is the matih-e extractive du bouillon; extractive^ and scf.jjonaceous extract of meat. — When flesh, cut into small fragments, is macerated in successive portions of cold water, the albumen, osma- zome, and salts are dissolved ; and, on boiling the solution, the albu- men is coagulated. From the liquid remaining, the osmazome may be procured in a separate state, by evaporating to the consistence of an extract, and treating with cold alcohol. This substance is of a reddish-brown colour ; and is distinguished from the other animal principles by solubility in water and alcohol — whether cold or at the boiling point — and by not forming a jelly when its solution is concen- trated by evaporation. Osmazome exists in the muscles of animals, the blood, and the brain. It gives the peculiar flavour of meat to soups ; and, according to Four- croy, the brown crust of roast meat consists of it. It is regarded as a mixture of different crystallizable and uncrystallizable principles with empyreumatic products.^ Kreatin and Kreatinin are two principles which were formerly in- cluded among the extractive or ill-defined matters of muscular tissue. ' Robin and Verdeil, Traite de Cliimie auatomique, &c., iii. 565, Paris 1853. 52 MATERIAL COMPOSITION OF MAN". They have been investigated by Liebig,' who discovered them also in urine. They appear to be like urea, mere products of the decomposi- tion of muscle. 7. Mucus. — This term has been applied to various substances ; and hence the discordant characters ascribed to it. Applying it to the fluid secreted by mucous surfaces, it varies somewhat according to the source whence it is derived. Its leading characters may be exempli- fied in that deriv^ed from the nostrils, which has the following proper- ties. It is insoluble in alcohol and water, but imbibes a little of the latter, and becomes transparent ; it is neither coagulated by heat, nor rendered horny ; but is coagulated by tannic acid. Mucus, in a liquid state, serves as a protecting covering to different parts. Hence it varies somewhat in its characters, according to the office it has to fulfil. When inspissated, it forms, according to some, the minute scales that are detached from the surface of the body by friction, corns, and the thick layers of the soles of the feet, nails, and horny parts; and it is contained in considerable quantity in hair, wool, feathers, scales of fishes, &c. 8. Urea. — This proximate principle exists in the urine of the mam- malia when they are in a state of health. In human urine it is less abundant after a meal, and it may nearly disappear in diabetes, and aSeetions of the liver. It is obtained by evaporating urine to the con- sistence of syrup. The syrup is then treated with four parts of alco- hol, which are afterwards volatilized by heating the alcoholic extract. The mass that remains is dissolved in water, or rather in alcohol, and crystallized. The purest urea that has been obtained, assumes the shape of acicu- lar prisms similar to those of the muriate of strontian. It is colourless, devoid of smell, or of action on blue vegetable colours, transparent, and somewhat hard. Its taste is cool, slightly sharp, and its specific gravity is greater than that of water. Urea is supposed by Dr. Prout to be chiefly derived from the de- composition of the gelatinous tissues; but, as Dr. Carpenter has re- marked,^ there seems to be no valid reason thus to limit the mode of its production. 9. Uric or litliic acid. — This acid is found in the urine of man, birds, serpents, tortoises, crocodiles, lizards ; in the excrements of the silk- worm, and very frequently in urinary calculi. It is obtained by dis- solving any urinary calculus which contains it, or the sediment of hu- man urine, in warm liquid potassa, and precipitating the uric acid by the chlorohydric. Pure uric acid is white, tasteless, and inodorous. It is insoluble in alcohol, and is dissolved very sparingly by cold or hot water, requiring about 10,000 times its weight of that fluid, at 60° of Fahrenheit, for solution. According to Dr. Prout, this acid is not free, but is commonly combined with ammonia; the reddening of lit- mus paper being not altogether owing to it, but to the super-phosphate of ammonia, which is likewise present in urine. In the herbivora, this acid is replaced by the hippuric. Xanthic acid^ found by Marcet in urinary calculi, seems to have been uric acid. ' Chemistry- of Food, London, 1847. » Human Physiology, § 673, Lond., 1842. OEGANIO ELEMENTS. 53 10. Colouring princijyles of the blood. — It has been already observed that Engelhart and Rose, German chemists, had detected iron in the red corpuscles of the blood, but had not found it in the other prin- ciples of that fluid. It has been considered probable, therefore, that it has something to do with the colour. Engelhart's experiments did not, however, determine the manner in which it acts, nor in what state it exists in the blood. The sulphocjanic acid which is found in the saliva forms, with peroxide of iron, a colour exactl}'' like that of venous blood ; and it is possible, that the colouring matter may be a sulphocyanate of iron. To obtain the red colouring matter, hcematin or hcematosin, allow the crassamentum or clot, cut into thin pieces, to drain as much as possible on bibulous paper, triturating it with water, and then evapo- rating the solution at a temperature not exceeding 122° of Fahren- heit. When thus prepared, the colouring particles are no longer of a bright red colour, and their nature is somewhat modified, in conse- quence of which they are insoluble in water. When half dried, they form a brownish-red, granular, friable mass; and when completely dried at a temperature between 167° and 190°, the mass is tough, hard, and brilliant. The mode in which the haematin is concerned in the coloration of the blood, will be inquired into under the head of Eespiration. A brown colouring matter, hceynaphcein, and a blue colouring matter, hcemacyanin, have been described. The former, however, it has been suggested, is nothing more than hgematin modified by an alkali ; and Simon^ never succeeded in detecting the latter. 11. Yellow colouring princijyle of the bile; — cholepyrrhin of Berze- lius, biliphcein of Simon. — This substance is present in the bile of nearly all animals. It enters into the composition of almost all gall- stones, and is deposited in the gall-bladder under the form of magma. ' It is solid; pulverulent; when dry, insipid, inodorous, and heayier than water. When decomposed by heat, it yields carbonate of am- monia, charcoal, &c. It is insoluble in water, alcohol, and the oils ; but soluble in alkalies. On the gradual addition of nitric acid to a fluid, which contains this substance in solution, a very characteristic series of tints is evolved. The fluid becomes first blue, then green, afterwards violet and red, and ultimately assumes a yellow or yellowish- brown colour. On adding an acid to a solution of biliphcein, a precipitation of green flocculi takes place : these possess all the properties of chlorophyll, or the green colouring matter of leaves. In this state it is termed bili- verdin by Berzelius ; and is a product of the metamorphosis of bili- phagin.^ These are the chief nitrogenized organic elements. b. Organic Elements that do not contain Nitrogen. 1. Olein and Stearin. — Fixed oils and fats are not pure proximate principles, as was at one time supposed. They were long presumed to consist of two substances, one of which is solid at the ordinary tem- perature of the atmosphere, and the other fluid : the former of these ' Op. cit., p. 42. * Simon, op. cit., p. 44. 5-i MATERIAL COMPOSITION OF MAX. j was called Stearin, from attap, suet ; the latter, Elain or OJein, from fXaiov, oil. Stearin is the chief ingredient of vegetable and animal suet ; of fat and butter ; and is found, although in small quantity, in fixed oils. In suety bodies, it is the cause of their solidity. Elain and stearin may be separated from each other by exposing fixed oil to a low temperature ; and pressing it, when congealed, between folds of bibulous paper. The stearin is thus obtained in a separate form ; and by pressing the bibulous paper under water, an oily matter is procured, ■which is elain in a state of purity. Modern chemistry has shown, however, that fat contained in the cells of adipose tissue is- composed of a base termed glycerin — itself hydrated oxide of glyceryl — with stearic and margaric acids. Stearin is a hi-stearate of glycerin : — olein, or elain, an oleate of glycerin. 2. Fatty matter of the Brain and Nerves. — Yauquelin^ found two varieties of fatty matter in the brain — the one white, the other red, the pro]:)erties of which have not been fully investigated. Both give rise to phosphoric acid by calcination, without there being any evidence of an acid or phosphate in their composition. They may be obtained by repeatedly boiling the cerebral substance in alcohol ; filtering each time ; mixing the various liquors, and suffering them to cool : — a lamel- lated substance is deposited, w^hich is the ivhite fatty matter. By eva- porating the alcohol, which still contains red fatty matter and osmazome, to the consistence of bouillie ; and exposing this, when cold, to the action of alcohol, the osmazome is entirely dissolved, whilst the alcohol takes up scarcely any red fatty matter. 3. Acetic acid. — This acid exists in a very sensible manner in sweat, urine, and milk — even when entirely sweet. It, or lactic acid, is formed in the stomach in indigestion ; was found by the author and his late friend. Professor Emmet, contained in the gastric secretions in health, ' and is one of the constant products of the putrid fermentation of ani- mal or vegetable substances. It is the most prevalent of the vegetable acids, and most easily formed artificially. 4. Oxalic acid. — This acid — which exists extensively in the vege- table kingdom, but always united with lime, potassa, soda, or oxide of iron — is only found, combined with lime, as an animal constituent in certain urinary calculi. 5. Benzoic acid. — Tliis acid, found in many individuals of the vege- table kingdom, is likewise met with in the urine of the horse, cow, camel, and rhinoceros ; and sometimes in that of man, especially of children. When benzoic acid is swallowed, hippuric acid is observed in the urine ; and it was supposed by Mr. A. Ure and others, that this was owing to the conversion of uric acid into hippuric; and as the hippuratcs are more soluble, it was suggested by liim, that benzoic acid might be advantageously exhibited in lithuria, and in cases of gouty depositions of lithate of soda. It has been found, however, by Drs. Keller and Garrod,^ and by Professors Booth and Boye, of Phila- delphia,^ that the administration of benzoic acid exerts no influence on the amount of uric acid in the urine. > Annales de Chim., Ixxxi. 37. * Liebig's Animal Chemistry, p. 316. 3 Proceedings of the American Philosophical Society at the Centennial Celebration in Philada., May, 1843, and Transactions of the A. P. Society, vol. ix. pt. 2, Philadelphia, 1845. OEGAXIC ELEMENTS. 65 6. Lactic acid. — Acid of milk is met with in blood, gastric juice, urine, milk, marrow, and also in muscular flesli. At times it is in a free state, but is usually united with alkalies. However much it may be concentrated, it does not crystallize, but remains under the form of syrup or extract. AVhen cold it is tasteless, but, when heated, has a sharp acid taste. According to Dr. Prout, this acid, like urea, results from the decomposition of the gelatinous parts of the system ; accord- ing to Berzelius, however, it is a general product of the spontaneous decomposition of animal matters within the body. Liebig^ formerly denied that any lactic acid is formed in the stomach in health ; and affirmed, that the property possessed by many substances, such as starch, and the. varieties of sugar, by contact with animal matters in a state of decomposition, of passing into lactic acid, had induced physiologists too hastily to assume the fact of the production of lactic acid during healthy digestion: — yet he now admits its presence. 7. Sugar of milk. — This substance, which is so called because it has a saccharine taste, and exists chiefly, if not solely, in milk, differs from ordinary sugar in not fermenting. It is obtained by evaporating whey, formed during the making of cheese, to the consistence of honey ; al- lowing the mass to cool ; dissolving ; clarifying and crystallizing. It commonly crystallizes in regular parallelopipedons, terminated by pyramids with four faces. It is white ; semitransparent ; hard, and of a slightly saccharine taste. 8. Sugar of diabetes. — In diabetes mellitus, the urine, which is often passed in enormous quantity, contains, at the expense of the economy, a large amount of peculiar saccharine matter, which, when properly purihed, appears identical in properties and composition with vegetable sugar, and approaches nearer to the sugar of grapes — glucose — than to that of the cane. It is obtained in an irregularly crystalline mass, by evaporating diabetic urine to the consistence of syrup, and keeping it in a warm place for several days. It is purified by washing in cold, or — at the most — gently heated alcohol, till the liquor comes off colour- less; and then dissolving it in hot alcohol. By repeated crystallization it is thus rendered pure.^ In the notes of two cases of diabetes mel- litus now before the author, it appears that sixteen ounces of the urine of one patient, of the specific gravity of l.OS-i, afforded a straw-co- loured extract, which, when cold and consolidated, weighed one ounce and five drachms. The same quantity of the urine of the other patient, specific gravity 1.040, yielded one ounce and seven drachms. Neither extract appeared to contain urea when nitric acid was added ; but when a portion was dissolved in water, and subjected to a temperature of 212°, traces of ammonia were manifested on the vapour being presented to the fumes of chlorohydric acid. From this a conclusion was drawn, that urea was present, as it is the only known animal matter decom- posed by the heat of boiling water. In a little more than a month, the subject of the latter case passed about four hundred and eighty pints of urine, or about seventy -five pounds troy of diabetic sugar ! 9. Hepatic sugar., liver sugar., found, by M. Bernard, to be produced in the liver, appears to resemble diabetic sugar more than it does glu- ' Op. cit., p. 107. ^ Prout, Medico-Cliirui-g. Trausact., viii. 538. 56 MATERIAL COMPOSITION OF MAN. 1 cose. Little is known, however, of its precise characters; but it is much more assimilable than glucose ; for, when injected into the veins, but little of it is detected in the urine.^ 10. Bilin or Picromel. — M. Thenard^ discovered this principle in the bile of the ox, sheep, dog, cat, and several birds ; Chevalier, in that of man. To obtain it, the acetate of lead of commerce must be added to bile until there is no longer any precipitate. By this means, the yellow matter of the bile and the whole of the fatty matter are thrown down, united with the oxide of lead ; the phosphoric acid of the phosphate of soda, and the sulphuric acid of the sulphate of soda, are likewise pre- cipitated. The picromel may then be thrown down from the filtered liquor by the subacetate of lead. The precipitate, which is a combina- tion of picromel with oxide of lead, must now be washed and dissolved in acetic acid. Through this solution, sulphuretted hydrogen is passed to separate the lead ; the solution is then filtered, and the acetic acid driven off by evaporation. Pure picromel is devoid of colour, and has the same appearance and consistence as thick turpentine. Its taste is at first acrid and bitter, but afterwards sweet. Its smell is nauseous, and specific gravity greater than that of water. When digested with resin of bile, a por- tion of the latter is dissolved, and a solution obtained, which has a bitter and a sweet taste, and yields a precipitate with the subacetate of lead and the stronger acids. This is the compound that causes the peculiar taste of the bile. 11. Gholesterin. — This is a constituent principle of the blood, bile, medullary neurine, and vernix caseosa. It is often precipitated from bile in a crystalline state : and forms of itself concretions which have an evidently laminated texture. It has been very frequently met with in morbid secretions and tissues ; in the fluid of dropsies ; in that of cysts and hydatids ; and in medullary fungus and other tumours. At times, it is dissolved; at others, swims upon the fluid in brilliant plates, or forms solid masses. It is obtained from biliary calculi by boiling in water, and dissolving them afterwards in boiling alcohol. On cool- ing, crystals of cholesterin separate. These inorganic and organic elements — with others of less moment discovered by modern chemists — variously combined and modified by the vital force, constitute the different parts of the animal fabric.^ Chemistry, in its present improved condition, enables us to separate them, and to investigate their properties ; but all the information we derive from this source relates to bodies, that have been influenced by the vital force, but are no longer so ; and in the constant mutations that occur in the system whilst life exists, and under its controlling agency, the same textures might exhibit very difterent chemical cha- ' Bernard, Le(,'ons de Physiologie Experimeutale, &c. &c., p. 209, Paris, 1855. 2 Memoir. d'Arcueil, i. 2:3, and Traite de Chimie, torn. iii. 3 See, on all this subject, Robin and Verdeil, Traite de Chimie Anatomique at Physio- logique, &.C., Paris, 1853 ; and Lehmann, Lehrbuch der Physiologischen Chemie, Leipz., 1852, or translation of the same, by Dr. Geo. E. Day: Amer. edit., by Dr. Robt. E. Rogers, Phila., 1855. Also, Report on the Progress of Animal Chemistry during the years 1852, 3 and 4, by Dr. Geo. E. Day, in the British and Foreign Medico-Chirurgical Review for April and July, 1855. SOLID PAKTS. 57 racterisfcics, could our researches be directed to tliem under tliose circumstances. "Whenever, therefore, the physiologist has to apply chemical elucidations to operations of the living machine, he must re- collect that all his analogies are drawn from dead matter, which dif- fers so widely from the living as to suggest the necessity of a wise and discriminating caution. The components of the animal body are invariably found under two forms — solids and fluids. Both are met with in every animal, the for- mer being derived from the latter; for, from the blood every part of the body is separated ; yet they are mutually dependent, for every liquid is contained in a solid. The blood itself circulates in solid vessels. Both, too, possess an analogous composition ; are in constant motion, and incessantly converted from one into the other. Every animal consists of a union of the two ; and this union is indispensable to life. Yet certain vague notions with regard to their relative pre- ];)onderance in the economy, and to their agency in the production of disease, have led to discordant doctrines of pathology, — the solidists l)elieving, that the cause of most affections is resident in the solids ; the Juimorists, that we are to look for it in the fluids. In this, as in similar cases, the mean will lead to the most satisfactory result. The causes of disease ought not to be sought in the one or the other exclu- sively. c. Of the Solid Parts of the Human Body. A solid is a body whose particles adhere to each other, so that they do not separate by their own weight ; but require the agency of some extraneous force to effect the disjunction. Anatomists reduce all the solids of the human body to twelve varieties; — hone, cartilage, muscle, ligament, vessel, nerve, ganglion, follicle, gland, membrane, areolar mem- brane, and viscus. 1. Bone is the hardest of the solids. It forms the skeleton ; the levers for the various muscles to act upon ; and serves for the protec- tion of important organs. 2. Cartilage is of a white colour, formed of very elastic tissue ; cover- ing the articular extremities of bones to facilitate their movements; sometimes added to bones to prolong them, as in the case of the ribs ; at others, placed within the articulations to act as elastic cushions; and, in the foetus, forming a substitute for bone. Hence, cartilages are divided into articular or incr'usting, cartilages ofjyrolongation, interarti- cular cartilages, and cartilages of ossification. 3. Muscles constitute the flesh of animals. They consist of fasciculi of contractile fibres, extending generally from one bone to another; and are the agents of all movements. 4. Ligaments are tough; difficult to tear; and under the form of cords or membranes, serve to connect different parts with each other, particularly bones and muscles; hence their division, by some anato- mists, into ligaments of hones — as the ligaments of the joints ; and liga- ments of muscles — as the tendons and aponeuroses. 5. Vessels are solids, having the form of canals, in which the fluids 58 MATERIAL COMPOSITION OF MAN. circulate. They are called — according to the fluid they convey — san- guineous (arterial and venous), chyUferous, lymphatic, &c. 6. Nerves are cords, consisting of numerous tubular fasciculi. These are connected with the brain, spinal marrow, or great sympathetic. They are the organs by which impressions are conveyed to the nervous centres, and by which each part receives from these its nervous influ- ence. There are three great divisions of the nerves, — the cerebro-sjnnal, true spinal, and organic. 7. Ganglions are solid knots in the course of a nerve which seem to be formed of an inextricable interlacing of nervous filaments. The term is likewise apjilied, by many modern anatomists, to similar inter- lacings of the ramifications of lymphatic vessels. Ganglions may, con- sequently, either be nervous or vascular ; and the latter, again, may be divided into cliyliferous or lymphatic, according to the kind of vessel on which they appear. Chaussier, a distinguished anatomist and physi- ologist, has given the name glandiform ganglions to certain organs whose nature and functions are unknown, but which appear to be con- cerned in lymphosis, — as the thjmius gland, the thyroid gland, &c. 8. Follicles or crypts are secretory organs, shaped — when simple — like membranous ampullas or vesicles, formed by an inversion of the outer membranes of the body — the skin and mucous surfaces — and secreting a fluid intended to lubricate them. They are often divided into the simp)h or isolated; the conglomerate ; and the conqwund, according to their size, or the manner in which they are grouped and united to- gether. 9. Glands are secretory organs not differing essentially from the last. Their organization is more complex ; and the fluid, after secretion, is poured out by means of one or more excretory ducts. 10. Ilemhrane. — This is one of the most extensive and important of the substances formed chiefly of areolar tissue. It is spread out in the shape of a web ; and, in man, serves to line cavities and reservoirs ; and to form, support, and envelope organs. Bichat divides membranes into two kinds, simple and compound, ac- cording as they are formed of one or more layers. Simp)le membranes are of three kinds, serous, mucous, and fibrous. 1st. Serous membranes constitute all the sacs or shut cavities of the body, — those of the chest and abdomen, for example. 2dly. Mucous membrcmes line all the outlets of the body, — the air- passages, alimentary canal, urinary and genital organs, &;c. Sdly. Fibrous membranes form tendon, aponeurosis, ligament, &c. Compound membranes are formed by the union of the simple, and are divided into fibro-serous, as the pericardium; sero-mucous, as the gall- bladder, at its lower part; and fibro-mucous, as the ureter. 11. Areolar, cellular or laminated tissue — to be described presentl}^ — is a sort of spongy or areolar structure, which forms the framework of the solids; fills up the spaces between them, and serves at once as a bond of union and of separation. 12. A viscus is the most complex solid of the body ; not only as re- gards intimate organization, but use. This name is given to organs contained in the splanchnic cavities, — brain, thorax, and abdomen, — and hence the viscera are termed cerebral, thoracic, and abdominal. SOLID PARTS. - 59 Every animal solid is either amorphorts or fibrous; that is, it is either without apparent arrangement, like jelly; or is disposed in minute threads, called fibres. The disposition of these threads, in different structures, is various. Sometimes, they retain the form of threads; at others, they have that of laminte, lamellas, or plates. Accordingly, "when we examine any animal solid, where the organization is percep- tible, it is found to be either amorphous, or fibrous and laminated. This circumstance led the ancients to endeavour to discover an ele- mentary fibre or filament, from which the various organs might be formed. Haller^ embraced the idea, and endeavoured to unravel every texture to this ultimate element, — which, he conceived, is to the physi- ologist what the line is to the geometer ; and, as all figures can be con- structed from the line, so every tissue and organ of the body may be built up from the filament. Haller, however, admitted that this ele- mentary fibre is not capable of demonstration, and that it is visible only to the "mind's eye," — ^Hnvisibilis ea fibra, qiuirn sold mentis acie adtingiinusP It must be regarded, indeed, as a pure abstraction ; for, as different animal substances in the mass have different proportions of carbon, hydrogen, oxygen, and nitrogen, it is fair to conclude that the elementary fibre must equally differ in the different substances. The ancients believed that the first product of the elementary fibre was areolar tissue ; and that this tissue forms every organ of the body, — the difference in the appearance of the organs arising from the dif- ferent degrees of condensation of its laminae. Anatomists, however, have been unable to reduce all animal solids to areolar tissue only. In the upper classes of animals, three primary fibres or tissues or anatomical elements are usually admitted, — the areolar, cellular or laminated; the muscular; and the nervous, pulpy or medullary. 1. The, areolar, cellular, mucous, filamentous or laminated fibre or tissue is the most simple and abundant of animal solids. It exists in every organized being; and is an element of every solid. In the ena- mel of the teeth only it has not been detected. It is formed of an assemblage of thin laminae, of delicate, whitish, extensible filaments, interlacing and leaving between each other areolae or spaces. These filaments — although possessed, like every other living tissiie, of con- tractility or the power of feeling an appropriate irritant and of moving responsive to such irritant — do not move perceptibly under the influ- ence of mechanical or chemical stimuli. They are mainly composed of concrete gelatin. — The great bulk of animal solids consists of areolar tissue, arranged as membrane. 2. Muscular fibre or tissue is a substance of peculiar nature; ar- ranged in fibres of extreme delicacy. The fibres are linear, soft, gray- ish or reddish, and manifestly possessed of contractility or irritability ; that is, they move very perceptibly under the influence of mechanical or chemical stimuli. They are composed, essentially, of fibrin. Their histology will be described hereafter. Muscular fibres, which are arranged in the form of meml^ranous expansions or muscular coats, differ from proper muscles chiefly in the mechanical disposition of the fibres. The physical and chemical ■ Elemonta Physiologire, vol. i. lib. i. sect. i. p. 7, Lausan., 1757. 60 MATERIAL COMPOSITION OF MAN. characters of both are identical. The fibres, instead of being collected into fasciculi, are in layers, and, instead of being parallel, interlace. This tissue does not exist in the zoophyte. 3. Nervous^ imlpy^ or medullary fibre or tissue^ which will be referred to hereafter, is much less distributed than the preceding. It is of a pulpy consistence ; is composed essentially of albumen united to a phosphuretted fatty matter ; and is the organ for receiving and trans- mitting impressions to and from the nervous centres. Of it, brain, cerebellum, medulla spinalis, nerves and their ganglia are composed. Professor Chaussier' added another primary fibre or tissue — the aTbugineous. It is white ; satiny ; resisting ; of a gelatinous nature ; and constitutes tendons and tendinous structures. He is, perhaps, the only anatomist that admits this tissue. Others properly regard it as a condensed variet}^ of the areolar. These various fibres or tissues, by uniting differently, constitute the first order of solids ; and these again, by union, give rise to compound solick, from which the different organs are formed. A bone, for ex- ample, is a compound of various tissues; osseous in its body; medullary in its interior ; and cartilaginous at its extremities. Bichat^ was the first anatomist who possessed clear views regarding the constituent tissues of the animal frame ; and whatever merit may accrue to after anatomists and physiologists, he is entitled to the credit of having pointed out the path, and facilitated the labours of the ana- tomical analyst. The term texture can only apply to solids ; but inasmuch as there are in suspension in certain fluids, as the blood, chyle and lymph, solid corpuscles of determinate form and organic properties, and which are not mere products or secretions of a particular organ, or confined to a particular part, such corpuscles have been looked upon as organ- ized constituents of the body, and therefore considered along with the solid tissues ; and, accordingly, the textures and other organized con- stituents have been enumerated as follows •? The blood, chyle and lymph. Bone or osseous tissue. Epidermic tissue, including epi- Muscular tissue. thelium, cuticle, nails, and Nervous tissue. hairs. Bloodvessels. "*• Pigment. Absorbent vessels and glands. Adipose tissue. Serous and synovial membranes. Cellular (areolar) tissue. ]\[ucous membranes. Fibrous tissue. Skin. Elastic tissue. Secreting glands. Cartilage and its varieties. Under the idea, now entertained, that all organized tissues are essentially composed of cells having plastic or formative powers, with an intercellular substance or blastema, the tissues have been thus arranged by Schwann, •* the great author of the cell doctrine. ' Table Synoptique des Solides Organiques. 2 Anatomic Gen., Paris, 1801, torn. i. ' Quain and Sharpey, Hnman Anatomy, Amer. edit., by Dr. Leidy, i. 39, Pliilad., 1849. * Microscopical Researches into tlie Accordance in "the Structure and Gro-wth of Animals and Plants. Sydenham Society's edit., by Henry Smith, p. 60, London, lS-i7. PRIMARY AND COMPOUND TISSUES. 61 1, Isolated, independent cells. To this class the cells in fluids pre- eminently belong : — lympli globules ; blood corpuscles. 2. Independent cells united into continuous tissues; sucli as the horny tissues and the crystalline lens. 8. Cells in which only the cell walls have coalesced — cartilage, bone, and the substantia 'proinia (ivory) of the teeth. •i. Fibre cells — cellular (areolar), fibrous and elastic tissue. 5. Cells in which both the cell walls and cell cavities have coalesced, — muscle, nerve and capillary vessels. Dr. Allen Thomson^ has proposed the following tabular view, which — he remarks — may be adopted in preference to the foregoing as com- bining similar theoretical considerations with a more immediate refer- ence to the actual form of the prevailing structural elements in the different tissues. He properly adds, however, that this classification is open — as he might have said every arrangement must be — to several objections; inasmuch as it brings together, under the same head, some parts endowed with different functions ; and separates some textures whose functions are closely related ; and it does not point out suffi- ciently the usual degree of complexity of the several textures. Some part of it, moreover, is founded on theoretical considerations not yet fully established ; and the distinctions on which it rests are based on a structural analysis of various extent in the different tex- tures. On the whole, however, it is a sufficient exponent of the exist- ing state of belief on the subject. I. Organized textures in which the cellular form of the constituent elements is apparent ; not unfrequently also presenting granules of molecular deposition. 1. Eounded simple cells, floating loose in fluid, Bloody Lymph^ Chyle and Milk Corpuscles, &c. 2. Simple cells massed together, either preserving their cellular form, and without other parts intervening, or altered in form and mixed with other solid elements : — Pigment, Fat, Cuticle, Horny tex- tures, JEJjntheUum, Crystalline lens. Cartilage. 3. Simple cells, or their contents, altered in form: — Ciliated texture, Spermatozoa. 4. Compound cells, separate or mixed with other textures: — Ovum, Ganglionic corpuscles. II. Textures exhibiting a simply fibrous structure. 1. Filamentous (areolar) texture ; formerl}^ Cellular texture. 2. Fibrous textures : — Tendon, Ligament, Fibrous membranes. Fibrous plates. 8. Elastic fibrous texture. III. Textures exhibiting a tubular structure. 1. Containing moving fluids: — Bloodvessels and Absorbent vessels. 2. Containing muscular substance : — Striated and non-striated mus- cular fibre. 3. Containing nervous matter : — Primitive nerve tubes. IV. Textures exhibiting a membranous structure. 1. Principally filamentous : — Serous and Synovial membranes. ' Outlines of Physiology for tlio U:=e of Students, pt. i. p. C8, Edinb., 1848. 62 MATERIAL COMPOSITION OF MAN. 2. Filamentous and vascular : — Mucous membranes ; True skin. 8. Membrane and cells: — Glands. 4. Membrane and bloodvessels, &c. : — Lungs. In combining to form the different structures, tlie solids are arranged in various ways. Of these, the chief are in filaments or elementary- fibres, tissues, organs apparatuses, and systems. A filament is the elementary solid. A fibre consists of a number of filaments united together. Occasionally this is called a tissue: — the term tissue usually, however, means a particular arrangement of fibres. An organ is a compound of several tissues. An apparatus is an assemblage of organs, concurring to the same end : — the digestive ajparatus consists of the organs of mastication, insalivation, and deglutition, the stomach, duo- denum, pancreas, liver, &c. These may be, and are, of very dissimilar character, both as regards their structure and functions ; but, if they concur in the same object, they form an apparatus. A system^ on the other hand, is an assemblage of organs, all of which possess the same or an analogous structure. Thus, all the muscles of the body have a common structure and function ; and form, in the aggregate, the muscular system. All the vessels of the body, and all the nerves, for like reasons, constitute, respectively, the vascular and nervous sys- tems. d. Of the Fluids of the Human Body. The positive quantity or proportion of the fluids in the human body does not admit of appreciation, as it must vary at different periods, and under different circumstances. The younger the animal, the greater is its preponderance. When we first see the embryo, it ap- pears to be almost wholly fluid. As it becomes gradually developed, the proportion of solid parts increases, until the adult age; after which it becomes less and less in the progress of life. During the whole of existence, too, the quantity of fluids in the body fluctuates. At times, there is plethora or unusual fulness of bloodvessels; at others, the blood is less in quantity. Experiments have been made for the purpose of ascertaining the relative proportion of fluids to solids. M. Kicherand says, that they are in the ratio of six to one; M. Chaussier, of nine to one. The latter professor put a dead body, weighing one hundred and twenty pounds, into a heated oven, and dried it. After desiccation, it was found to be reduced to twelve pounds. It is probable, however, that some of the more solid portions were driven oft' by the heat employed ; and hence that the estimated proportion of fluids was too high. On this account, M. Berard' thinks, that instead of estimating the proportion of liquids at nine-tenths, it would be better to take the mean result of experiments by M. Chevreul, who performed the desiccation in vacuo and with a very moderate heat. This would give the proportion of water in the human body about 6.667 parts in the 10.000. In the Egyptian mummies, which are completely deprived of fluid, the solids are extremely light, not weighing more than seven pounds ; but as we are ignorant of the original weight of the body, we cannot ' Cours de Physiologic, p. 200, Paris, 1848. FLUIDS. 63 arrive at any approximation. The dead bodies found in the arid sands of Arabia, as well as the dried preparations of the anatomical theatre, afford additional instances of reduction by desiccation. To a less ex- tent, we have the same thing exhibited in the excessive diminution in weight that occurs in disease, and occasionally in those who are ap- parently in health. Not many years ago, an Anatomie vivante was ex- hibited in London to the gaze of the curious and scientific, whose weight was not more than eighty pounds. Yet the ordinary functions were carried on, apparently unmodified. In the year 1830, a still more wonderful phenomenon was shown. A man named Calvin Edson, forty-two years old, five feet two inches high, weighed but sixty pounds. His weight had formerly been one hundred and thirty-five pounds. For sixteen years previously, he had been gradually losing flesh, without any apparent disease, having enjoyed perfect health and appetite, and eating, drinking, and sleeping as well as any one. He ■\vas properly called the " living skeleton^ It was stated in the public journals' that Dr. Edson, a brother of Calvin, was to all appearance entirely destitute of flesh. He was, in 18-17, forty -two years old ; of ordinary height — five feet six inches, and yet weighed only forty-nine pounds. He retained all his faculties apparently in full vigour. We have it also, on the authority of Captain Eiley,^ that after protracted sufferings in Africa, he was reduced from two hundred and forty pounds to below ninety [?]. The fluids are variously contained; sometimes in vessels — as the blood and lymph ; at others, in cavities — as the fluids secreted by the pleura, peritoneum, arachnoid coat of the brain, &c. : others are in minute areolae — as the fluid of the areolar membrane ; whilst others, again, are intimately combined with the solids. They differ likewise in density, — some existing in the state of halitus or vapour ; others being very thin and aqueous — as the fluid of the serous membranes ; and others of more consistence — as the secretion of the mucous mem- branes, animal oils, &c. The physical and chemical properties of the fluids will engage atten- tion when they fall individually under consideration ; and we shall find that one of them at least — the blood — exhibits certain phenomena analogous to those of the livino^ solid. The fluids have been differently classed, according to the particular views that have, from time to time, prevailed in the schools. The an- cients referred them all to four — blood, bile, phlegm or pituita, and atrabilis ; each of which was conceived to abound in one of the four ages, seasons, climates, or temperaments. Blood predominated in youth, in the spring, in cold, mountainous regions, and in the sanguine or inflammatory temperament. Pituita, or phlegm, had the mastery in old age, in winter, in low and moist countries, and in the lymphatic temperament. Bile predominated in mature age, in summer, in hot climates, and in the bilious temperament ; and atrabilis was the cha- racteristic of middle age, of autumn, of equatorial climes, and of the melancholic temperament. This was their grand humoral system, ' PhiladelpMa Public Leclger, Feb. 2, 1847. ^ Narrative of the loss of the American Brig Commerce, &c., p. 302. New York, 1817. 6-i MATERIAL COMPOSITION OF MAN. wliicli lias vanished before a better observation of facts, and more im- proved methods of pbj^sical and metaphysical investigation. The atrabilis was a creature of the imagination ; the pituitous condition is unintelligible to us; and the doctrine of the influence of the humours on the ages, temperaments, &c., irrational. Subsequent!}^, the humours were classed according to their physical and chemical properties : they were divided, for instance, into liquids, vapours, and gasek ; into acid, alkaline, and neutral ; into thick and thin ; into aqueous, mucilaginous, gelatinous, and oily; into saline, oily, saponaceous, mucous, albuminous, and fibrinous, &c. In more modern times, endeavours have been made to arrange them according to their uses in the economy into — 1, rccrementilial fluids, or those intended to be again absorbed ; 2, excrementitial, those that have to be expelled from the body ; and 3, those which participate in both purposes, and are hence termed excremento-recremetititial. Blumenbach' divided them into crude humours, blood, and secreted humours, a division which has been partly adopted by M. Adelon :^ and Chaussier, whose anatomical arrangements and nomenclature have rendered him justly celebrated, reckoned five classes : — 1, those produced by the act of digestion — chyme and chyle ; 2, the circulating fluids — lymph and blood ; 3, the perspired fluids; 4, the follicular ; and 5, the glandular. This arrange- ment has been adopted by M. Magendie,^ and, with slight modification, is perhaps as satisfactory as any that has been proposed. All these will have to engage attention under Secretion. e. Physical Properties of the Tissues. The tissues of the body possess the physical properties of matter in general. They are found to vary in consistence — some being hard, and others soft ; as well as in colour, transparency, &c. They have, also, physical properties, analogous, indeed, to what are met with in certain inorganic substances, but generally superior in degree. These axe flexibility, extensibility, and elasticity, which are variously combined and modified in the different forms of animal matter, but exist to a greater or less extent in every tissue. Elasticity is only exerted under particular circumstances : when the part, for example, is put upon the stretch or compressed, the force of elasticity restores it to its primitive state, as soon as the distending or compressing cause is with- drawn. The tissues, in which elasticity is inherent, are so disposed through the body, as to be kept in a state of distension by the mechani- cal circumstances of situation ; but as soon as these circumstances are modified, elasticity comes into play, and produces shrinking of the sub- stance. It is easy to see, that these circumstances, owing to the con- stant alteration in the relative situation of parts, must be ever varying. Elasticity is, therefore, constantly called into operation, and in many cases acts upon the tissues as a new power. The cartilages of the ribs, joints, &c,, are in this manner valuable agents in particular functions. "We have other examples of, the mode in which elasticity exhibits • Institutiones Physiologicse, Sect, ii., § 4. Getting., 1798. ^ Physiologie de PHomme, 2de edit., i. 124. Paris, 1829. 3 Precis Elementaire de Physiol., 2de edit., i. 20. Paris, 1825. PHYSICAL PROPERTIES OF TISSUES. 65 itself, when the contents of hollow parts are withdrawn, and whenever muscles are divided transversely. The gaping wound, produced by a cut across a shoulder of mutton, is familiar to all Previous to the division, the force of elasticity is kept neutralized by the mechanical circumstances of situation — or by the continuity of the parts ; but as soon as this continuity is disturbed, — in other words, as soon as the me- chanical circumstances are altered, the force of elasticity is exerted, and produces recession of the edges. This property has been described under various names, tone or tonicity^ contractilite de tissii, contractiUte par defaut d^ extension, &c. The other properties, flexibility and extensihility, vary greatly ac- cording to the structure of parts. The tendons, which are composed of areolar tissue, exhibit very little extensibility ; and this for wise purposes. They are the conductors of force developed by muscle, and were they to yield, it would be at the expense of the muscular efforts ; but they possess great flexibility. The articular ligaments are very flexible, and somewhat more extensible. On the other hand, the fibrous or ligamentous structures, which are employed to support weights, or are antagonists to muscular action — as the lifjamentuni nuchm, which passes from the spine to the head of the quadruped — are very exten- sible and elastic. Another physical property, possessed by animal substances, is a kind of contractility, accompanied with sudden corrugation and curling. This effect, which Bichat terms racornissement, is produced by heat, and by chemical agents, especially the strong mineral acids. The property is exhibited by leather when thrown into the fire. An effect, in some measure resembling this, is caused by the evapo- ration of the water that is united to animal substances. This consti- tutes what has been called the hygrometric 2^'>'0perty of animal mem- branes.^ It is characteristic of dry, membranous structures ; all of which are found to contract, more or less, by the evaporation of moist- ure, and to expand again by its reabsorption ; hence the employment of such substances as hygrometers. According to M, Chevreul,^ many of the tissues are indebted for their physical properties to the water they contain, or with which the}'" are imbibed. When deprived of this fluid, they become unfit for the purposes for which they are destined in life, and resume them as soon as they have recovered it. A most important property possessed by the tissues of organized bodies is imbibition; a property to which attention has been chiefly directed of late years. If a liquid be put in contact with any organ or tissue, in process of time the liquid will be found to have passed into the areohe of the organ or tissue, as it would enter the cells of a sponge. The length of time occupied in this imbibition will depend upon the nature of the liquid and the kind of tissue. Some parts of the body, as the serous membranes and small vessels, act as true sponges, absorbing with great promptitude; others resist imbibition fur a considerable time, — as the epidermis. ' Roget, art. Physiology, in Supplement to Encyclopsedia Britannica ; and Outlines of Physiology, with an Appendix on Phrenology. First American edition, with notes by the author of this work, p. 73, Philad., 1839. ^ Magendie, Precis Elementaire de Physiologie, 2de edit., 1825, i. 13. VOL. I. — 5 G6 MATERIAL COMPOSITION OF MAN. Liquids penetrate equally from within to without ; the process is then called transudation. Some singular facts have been observed regarding the imbibition of fluids and gases. On filling membranous expansions, as the intestine of a chicken, with milk or some dense fluid, and immersing it in water, M. Dutrochet' observed, that the milk left the intestine, and the water entered it; hence he concluded, that whenever an organized cavity, containino- a fluid, is immersed in another fluid less dense than that which is in the cavity, there is a tendency in the cavity to expel the denser and absorb the rarer fluid. This M. Dutrochet termed endos- mose or "inward impulsion;" and he conceived it to be a new power, a " physico-organic or vital action." Subsequent experiments showed, that a reverse operation could take place. If the internal fluid was rarer than the external, the transmission occurred in the opposite direction. To this reverse process, he gave the name exosmose, or ''outward impulsion." At times, the term endosmose is applied to the mutual action of two liquids when separated by a membrane;^ at others, to the passage of the liquid, that permeates the membrane in greatest quantity,^ Soon after the appearance of M. Dutrochet's essay, the experiments were repeated, with some modifications, by Dr. Faust, "• and by Dr. Togno,* of Philadelphia ; and with like results. The fact of this im- bibition and transudation was singular and impressive ; and, with so enthusiastic an individual as M. Dutrochet, could not fail to give birth to numerous and novel conceptions. The energy of the action of both endosmose and exosmose is in proportion, he asserted, to the dift'erence between the specific gravities of the two fluids ; and, independently of their gravity, their chemical nature affects their power of transmission. These effects — he at once decided — must be owing to electricity. The cavities, in which the changes take place, he conceived to be like Ley- den jars having their two surfaces charged with opposite electricities, the ultimate effect or direction of the current being determined by the excess of the one over the other. In an interesting and valuable communication by Prof. J. K. Mit- chell,^ of Philadelphia, "on the penetrativeness of fluids," many of the visionary speculations of M. Dutrochet are sensibly animadverted upon. It is there shown, that he had asserted, in the teeth of some of his most striking facts, that the current was always from a less dense to a more dense fluid; and that it was from positive to negative, dependent not on an inherent power of filtration, — a power always the same when the same membrane is concerned, — but modified at pleasure by sup- ' M6m. pour servir &, I'Histoire Anatom. et Physiol, des Animaux et des Vegetaux, Paris, 1837 ; art. Endosmosis, iu Cyclopsedia of Anatomy and Physiology, part x. p. 98, June, 1837. See, also, Vierordt, art. Transudation und Endosmose, in Wagner's Handworterbuch der Physiologie, s. 631, Braunschweig, 1848. Ludwig, Lehrbuch der Physiologie des Menschen, 1. 63, Heidelb. 1852. J. Beclard, Traite 6lementaire de Physiologie, p. 149, Paris, 1855. ^ Matteucci, Lectures on the Physical Phenomena of Living Beings ; translated by Pereira, p. 45, Amer. edit., Pbilad., 1848. » Poiseuille, Comptes Rendus, xix. 944, Paris, 1844. * Amer. Journal of the Med. Sciences, vii. 23, Philad., 1830. » Ibid., iv. 73, Philad., 1829. « Ibid., vii. 23, Philad., 1830. PHYSICAL PROPERTIES OF TISSUES. 67 posed electrical agencies. This view was subsequently abandoned by M. Dutrochet, in favour of the following principle. It is well known that porous bodies, as sugar, wood, or sponge, are capable of imbibing liquids, with which they are in contact. In such case, the liquid is not merely introduced into the pores of the solid, as it would be into an empty space; but it is forcibly absorbed, so that it will rise to a height considerably above its former level. This "osmotic force" is molecular, and is the same that we witness in the phenomena presented by the capillary tube, which affords us the simplest case of the insinuation of a liquid into a porous body. It cannot alone, however, cause the liquid to pass entirely through the body. If a capillary tube, capable of raising water to the height of six inches, be depressed, so that one inch only be above the surface, the water will rise to the top of the tube ; but no part of it will escape. Even if the tube be inserted horizon- tally into the side of the vessel containing water, the water will only pass to the end of the tube. The same thing occurs when a liquid is placed in contact with one side of a porous membrane : it enters the pores ; passes to the opposite side, and is there arrested. But if this membrane communicates with a second vessel containing a different liquid — as a saline solution, capable of mixing with the first, and affected to a different degree by capillary attraction — a new phenome- non will be presented. It will be found, that both liquids enter the pores, and pass through to the opposite side. They will not, however, be carried through with the same force : that which has the greatest power of capillary ascension, has the greatest affinity for the membrane, or will wet it more readily, — in other words, that which will rise the highest in a capillary tube, — will pass through in greater quantity, and cause an accumula- tion of liquid on the opposite side. The action is well shown by the simple instrument figured in the margin. It consists of a glass tube, the lower extremity of which, covered by bladder, is funnel-shaped. This M. Dutrochet termed an endosmometer. If an aqueous solution of either gum or sugar be poured into it, and the closed extremity be immersed in pure water, the water is found to pass con- tinually into the tube by filtration through the membrane, so that the liquid will rise in the tube, and may even flow out at the upper aperture. At the same time, a portion of the mucilaginous or saccharine solution will escape from the tube through the bladder, and become mixed with the water, but the quantity will be much less than that of the water which entered. The facts and arguments adduced by Dr. Mitchell clearly exhibit, that imbibition and transudation are dependent upon the penetrativeness of the liquid, and the penetra- bility of the membrane ; that if two liquids, of different "^LTa-n"' rates of penetrativeness, be placed on opposite sides of an animal membrane, "they will in time present the greater accumulation on the side of the less penetrant liquid, whether more or less dense ; but will, finally, thoroughly, and uniformly mix on both sides; and at length, if any pressure exist on either side, yield to that, and pass to Fig. 1. 68 MATERIAL COMPOSITION OF MAN. . I the other side."* In all such cases, there are both endosmose and exos- mose — or double imbibition ; in other words, a certain quantity of one fluid passes in, and a certain quantity of the other passes out.^ As a general rule, imbibition takes place from the rarer to the denser me- dium; from pure water or dilute solutions towards those that are more concentrated. It would appear, again, that the stronger current is always from the medium which has the strongest affinity for the sub- stance of the septum. It is well known, that in the case of a mixture of dilute alcohol covered over by a piece of bladder, the alcohol becomes concentrated, owing to the water — a denser fluid — passing more rapidly through the septum or bladder than the alcohol ; but if the same mixture be tied over with elastic gum, the contrary effect will be produced — the alcohol escaping in greater quantity.^ The general conditions of the phenomena of endosmose are: — first^ that the two liquids shall have an aflBnity for the septum or interposed membrane; and, secondly^ that they shall have an affinity for, and be miscible with each other. A portion of the communication of Dr. Mitchell relates to an ana- logous subject, to which, as M. Magendie"* has observed, little or no attention had been paid by physiologists — the permeability of mem- hranes by gases. " The lamince," M. Magendie remarks, " of which membranes are constituted, are so arranged that gases can penetrate them, as it were, without obstacle. If we take a bladder, and fill it with pure hydrogen, and afterwards leave it in contact with atmo- spheric air, in a very short time the hydrogen will have lost its purity, and be mixed with the atmospheric air, which has penetrated the bladder. This phenomenon is more rapid in proportion as the mem- brane is thinner and less dense. It presides over one of the most important acts of life — respiration ; and continues after death." Dr. Mitchell is the first individual, who directed his observation to the relative penetrativeness of different gases. This he was enabled to discriminate by the following satisfactory experiment, which we give in his own words : " Having constructed a syphon of glass, with one limb three inches long, and the other ten or twelve inches, the open end of the short leg was enlarged and formed into the shape of a funnel, over which, finally, was firmly tied a piece of thin gum elastic. By inverting this syphon, and pouring into its longer limb some clear mercury, a portion of common air was shut up in the short leg, and was in communication with the membrane. Over this end, in the mercurial trough, was placed the vessel containing the gas to be tried, and its velocity of penetration measured by the time occupied in elevating to a given degree the mercurial column in the other limb. Having thus compared the gases with conmion air, and subsequently by the same instrument, and in bottles with each other, I was able to arrange the following gases according to their relative facility of ' Amer. .Toumal of the Medical Sciences for November, 1833, p. 100. * Magendie, Lemons sur les Phenomenes Physiques de la Vie, torn. i. p. 99, Paris, 1836-38. 3 Henle, Allgem. Anat., or Jourdan's French translat., p. 210, Paris, 1843; and Wag- ner, Elements of Physiology, by Willis, p. 438, Lond., 1S42. '' Precis Elemeutaire de Physiologic, 2de edit., 1825, i. 13; and Lemons, &c., torn. i. p. 132. FUNCTIONS OF MAN. 69 transmission, beginning with the most powerful : — ammonia, sulphu- retted hydrogen, cyanogen, carbonic acid, nitrous oxide, arseniuretted hydrogen, olefiant gas, hydrogen, oxygen, carbonic oxide, and nitro- gen." He found that ammonia transmitted in one minute as much in volume as sulpJiuretted hydrogen did in two minutes and a half; cyan- ogen^ in three minutes and a quarter; carbonic acid, in five minutes and a half; nitrous oxide, in six minutes and a half; arseniuretted hydrogen, in twenty-seven minutes and a half; olefiant gas, in twenty-eight minutes ; hydrogen, in thirty-seven minutes and a half; oxygen, in one hour and fifty-three minutes ; and carbonic oxide, in two hours and forty minutes. It was found, too, that up to a pressure of sixty-three inches of mercury, equal to more than the weight of two atmospheres, the penetrative action was capable of conveying the gases — the sub- jects of the experiment — into the short leg through the gum elastic membrane. Hence, the degree of force exerted in the penetration is considerable. The experiments were all repeated with animal membranes, such as dried bladder and gold-beater's skin, moistened so as to resemble the natural state. The same results, and in the same order, followed as with the gum elastic. The more fresh the membrane, the more sjoeedy and extensive was the eflect; and in living animals the transmission was very rapid. To these experiments there will be frequent occasion to refer in the course of this work.^ All these different properties of animal solids are independent of the vital properties. They continue for some time after the total extinc- tion of life in all its phenomena, and appear to be connected either with the physical arrangement of the molecules, the chemical compo- sition of the substance in which they reside, or with peculiar proper- ties in the body that is made to act on the tissue. They do not, indeed, seem to be aft'ected, until the progress of decomposition has become sensible. Hence, many of them have been termed collectively, by Haller, vis mortua. 2. FUNCTIONS OF MAN. Having described the intimate structure of the tissues, we pass to the consideration of the functions; the character of each of which is, — that it fulfils a special and distinct office in the economy, for which it has in general an organ or instrument, or evident apparatus of organs. Physiologists have not, however, agreed on the number of distinct offices ; and hence the difference, in regard to the number and classifi- cation of the functions, that prevails amongst them. The oldest divi- ' See, connected with this subject, the ingenious papers hy Dr. Robert E. Rogers, and Dr. Draper — the former in tlie American Journal of the Medical Sciences, May, 1836, p. 13 ; and the latter in the same .Journal for August, 183(j, p. 276 ; Nov. 1837, p. 122; and Aug. 1838, p. 302: and Abstract of Experiments iipon the physical influ- ences exerted by living, organic and inorganic membranes, upon chemical substances in solution passing through them by endosmose, by Joseph Jones, A. B., in the same Journal, for April, 1855, p. 555 ; and Experimental Investigations to ascertain the action of saline solutions of diflerent densities upon living animals, and the recii)rocal action, through dead animal membranes, of serum, water, and saline solutions ; by the same. Ibid., .Jan., 1856, p. 61. 70 FUNCTIONS OF MAN. sion is into the vital^ natural., and animal; the vital functions including those of such importance as not to admit of interruption, — circulation, respiration, and innervation; the natural functions those that effect nutrition, digestion, absorption, and secretion; and the animal those possessed exclusively by animals, — sensation, locomotion, and voice. This classification, with more or less modification, prevails at the pre- sent day. The character of this work will not admit of a detail of every classi- fication which has been proposed ; that of Bichat, however, has occu- pied so large a space in the public eye, that it cannot well be passed over. It is followed by A[. Hicherancl,^ and many modern writers. Bichat includes all the functions under two heads,— /w?2dw??5 of mdri- tio7i, which concern the life of the individual^ and functions of rei'trodvc- tion, which concern the hfe of the species. Nutrition requires, that the being shall establish relations around him to obtain the materials of which he may stand in need; and, in animals, the functions that esta- blish such relations, are under the volition and perception of the being. Hence they are divided into two sets ; those that commence or precede nutrition; have external relations; are dependent upon the will, and executed with consciousness; and those that are carried on within the body spontaneously, and without consciousness. Bichat adopted this basis; and, to the first aggregate of functions, he applied the term animal life, because it comprised those that characterize animality: the latter he termed organic life^ because the functions comprised under it are common to every organized body. Animal life included sensa- tion, motion, and expression; organic life, digestion, absorption, respi- ration, circulation, nutrition, secretion, &c. In animal life, Bichat re- cognized two series of actions, antagonistic to each other; the one pro- ceeding from without and terminating in the brain, or passing from circumference to centre, and comprising the external senses; the other, commencing iu the brain, and acting on external bodies, or proceeding from centre to circumference, and including the internal senses, loco- motion, and voice. The brain, in which one series of actions terminates and the other begins, he considered the centre of animal life. In organic life, he lilcewise recognized two series of actions: the one, pro- ceeding from without to within, and effecting composition; the other passing from within to without, and effecting decomposition. In the former, he included digestion; absorption; respiration, by which the blood is formed; circulation, by which the blood is conveyed to differ- ent parts; and the functions of nutrition, and calorification. In the latter, that absorption by which parts are taken up from the body ; the circulation, which conducts those parts or materials to the secretory or depuratory organs; and the secretions, which separate them from the economy. In this kind of life, the circulation is common to the two movements of composition and decomposition ; and, as the heart is the great organ of the circulation, he considered it the centre of organic life. Lastly, as the lungs are united with animal life in the reception of air, and with organic life as the organs of sanguification, Bichat • Nouveaux EL'mens de Physiologic, 13eme edit., par M. B'rard, ainp, ^dit. Beige, p. 42, Bnixelles, 1837 ; or Amer. reprint of Copland's edit, of De Lys's translation, New- York, 1836. FUNCTIONS OF MAN. 71 regarded tliem as tlie bond of union between the two lives. Genera- tion constituted the life of the species. M. Brachet,' who gives to the sympathetic or great ganglionic nervous system a pervading influence which, it will be seen, does not properly belong to it, adopts the following classification : — METHODICAL CLASSIFICATION OF THE FUNCTIONS. First Class. — Functions of ganglionic life, common to all organized bodies, and exercised under tlie influence of the gan- glionic nervous system alone. Second Class. — Functions of cerebral life jieculiar to animals, and exercised under the influ- ence of the cerebral nervous system alone. Thikd Class. — Mixed func- tions, requiring the influence of the two nervous systems for their complete exercise. Appendix. 1. Innervation of the ganglionic nervous system. 2. Absorption. 3. Course of tlie lympb. 4. Circulation. 5. Nutrition. 6. Secretions. 1. Innervation of the cerebral nervous system. 2. Sensations. 3. Intellectual functions. 4. Locomotion. 5. Voice and speech. 1. Digestion. 2. Respiration. 3. Generation. 4. Urinary excretion. 1. Relations and connections of the functions with, each other. 2. Sympathies. 3. Modifications of the functions by, 1, age ; 2, sex; 3, temperament; 4, habit; 5, climate, diseases, and a multitude of agents. 4. Comparative physiology. The classification, adopted in this work, is essentially that embraced by M, Magendie;^ and, after him, by M. Adelon,^ who has written one of the best systems of liuman physiology that we possess. The first CLASS, or functions of relation or animal functio7%s, includes those that establish our counexion with the bodies that surround us; the sensa- tions^ voluntary motions, and expressions. The SECOND CLASS, or functions of nutrition, comprises digestion, absorption, respiration, circulation, nutri- tion, calorification, and secretion; and the THIRD CLASS, the functions of reproduction; — generation. TABLE OF FUNCTIONS. I. Functions that relate to the pi-eservation of the individual. II. Functions that relate to the preservation of the species. I. Nutritive. II. Animal or of Relation. III. Reproductive. 1. Digestion. 2. Absorption. 3. Resjairation. 4. Circulation. 5. Nutrition. 6. Calorification. 7. Secretion. 1. Sensation. 2. Mental and Moral Manifestations. 3. Muscular Motion. 4. Expression or Lan- guage. Generation. In Studying each of these functions, we shall first of all describe the organ or apparatus concerned in its production, — but so far only as is ' Physiologic Elementaire de I'Homnie, 2de edit., i. 61. Paris et Lyon, 1855. ^ Precis, &c., i. 32. * Physiologic de I'Homme, 2de edit., i. llti. Paris, 1829. 72 FUNCTIONS OF MAN. necessary in a physiological point of view ; and shall next detail what has been called the mechanism of the function, or the mode in which it is effected. In many cases, it will happen, that some external agent is concerned, — as light in vision ; sound in audition ; oclours in olfac- tion; tastes in gustation. The properties of these agents will, in all instances, be detailed in a brief manner. The difficulty of observing actions, that are carried on by the very molecules of which the organs are composed, has given rise to many hypothetical speculations, some of which are sufiiciently ingenious ; others too fanciful to be indulged for a moment ; and, as might be expected, the number of these fantasies generally bears a direct pro- portion to the difficulty and obscurity of the subject. It will not be proper to pass over the most prominent of these, but they will not be dwelt upon ; whilst the results of direct observation and experiment will be fully detailed ; and where differences exist amongst observers, such differences will be reconciled, where practicable. The functions, executed by different organs of the body, can be de- duced by direct observation; although the minute and molecular action, by which they are accomplished in the very tissue of the organ, may not admit of detection. We see blood proceeding to the liver, and the vessels that convey it ramifying in the texture of that viscus, and becoming so minute as to escape detection even when the eye is aided by a powerful microscope. We find, again, other canals in the organ becoming perceptible, gradually augmenting in size, and ultimately terminating in a larger duct, which opens into the small intestine. If we examine each of these orders of vessels in its most minute appre- ciable ramifications, we discover, in the one, always blood ; and, in the other, always a very different fluid — bile. We are hence led to the conclusion, that in the intimate tissue of the liver, and in some part communicating directly or indirectly with both these Orders of vessels, bile is separated from the blood ; or that the liver is the organ of the biliary secretion. On the other hand, functions exist, which cannot be so demonstratively referred to a special organ. We have every reason for believing that the brain is the exclusive organ of the mental and moral manifestations ; but, as few opportunities occur for seeing it in action ; and as the operation is too molecular to admit of direct observation when we do see it, we are compelled to connect the organ and function by a process of reasoning only ; yet, we shall find, that the results at which we arrive in this manner are often by no means the least satisfactory. The forces which preside over the various functions are either gene- ral — that is, physical or chemical ; or sjjecial— that is, organic or vital. Some of the organs afford us examples of purely physical instruments. We have in the eye, an eye-glass of admirable construction ; in the organ of voice, an instrument of music; in the ear, one of acoustics: the circulation is carried on through an ingenious hydraulic apparatus : and station and progression involve various laws of mechanics. In many of the functions, again, we have examples of chemical agency, whilst all in which innervation is concerned are incapable of being ex- plained on any physical or chemical principle; and we are constrained to esteem them vital. DIGESTIVE ORGANS. 73 BOOK I. NUTRITIYE FUNCTIONS. The human body, from the moment of its formation to the cessation of existence, is undergoing constant decay and renovation — decompo- sition and composition: — so that at no two periods can it be said to have exactly the same constituents. The class of functions about to engage attention embraces those that are concerned in effecting such changes. They are seven in number; — digestion^ by which the food, received into the stomach, undergoes, in that organ a,nd in the intes- tines, such conversion as fits it for the separation of its nutritious and excrementitious portions ; absorjjtion, by which this nutritious portion, as well as other matters, is conveyed into the mass of blood ;^ resjxij-atmi, ]>y which the products of absorption and venous blood are converted into arterial blood; circulation^ by which the vital fluid is distributed to every part of the system ; nutrition, by which the intimate changes of composition and decomposition are accomplished; calorification, by which the system is enabled to resist the effects of greatly elevated or depressed atmospheric temperature, and to exist in the burning regions within the tropics, or amidst the arctic snows; and secretion, by which various fluids and solids are separated from the blood ; — some to serve useful purposes in the animal economy ; others to be rejected from the body. CHAPTEE I. OF DIGESTION. The food, necessary for animal nutrition, is rarely found in such a condition as to be adapted for absorption. It has, therefore, to be subjected to various actions in the digestive organs; the object of which is to enable the nutritive matter to be separated from it. These actions constitute the function of digestion; in the investigation of which we shall commence with a brief description of the organs con- cerned in it. These are numerous, and of a somewhat complicated nature. 1. ANATOMY OF THE DIGESTIVE ORGANS. The human digestive organs consist of a long canal, varying con- siderably in its dimensions in diSerent parts, and communicating ex- ' M. Robin, under Digestion, appears to include both these acts. " La digestion est cette fonction qui introduit par endosmose les materiaiix, et satisfait h I'acte chimique de composition ou assimilutioti nutritive." Beraud, Manuel de Physiologie, p. 54, Paris, 1853. 74 DIGESTION. ternally bj two outlets, — the mouth and amis. It is usually divided into four chief portions — the mouth, jj/iar?/?Kr, oesojjhagus, stomach, and intestines. These we shall describe in succession, 1. The mouth is the first cavity of the digestive tube, and that into which the food is immediately received, and subjected to the action of the organs of mastication and Fig. 2. insalivation. Above and below, it is circumscribed by the jaws, and laterally by the cheeks; — anteriorly by the lips and their aperture, constituting the mouth proper ; and, posteriorly, it com- municates with the next portion of the tube, — the pharynx. It is invested by a mucous exhalant membrane, which is largely sup- plied with follicles; and into it the ducts from the different salivary glands pour their secretion. In all animals furnished with distinct diofestive oro;ans, means exist for comminuting the food, and enabling the stomach to act with greater facility upon it. These consist, for the most part, as in man, of the jaws, the teeth fixed into the jaws, and muscles by which the jaws are moved. Thejaus chiefly determine the shape and dimensions of the mouth; the vpper forming an es- sential part of the face, and mov- ing only with the head ; the lower, on the contrary, possessing great mobility. Each of the jaws has a prominent edge, forming a semi- circle, in which the teeth are im- planted. This edge is called the alveolar arch. The teeth are small organs, of a density superior to bone ; and covered externally by a hard sub- stance called enamel. By many, they have been regarded as bone ; but they differ from it in many essential respects, although they resemble it in hardness and chemical composition. At another opportunity we shall inquire into their origin, structure, and developement. We may merely remark, at pre- sent, that by many they are looked upon as analogous to the corneous substances, which develope themselves in the tissue of the skin. De Bluinville assimilates them to the hair; and believes, that they are Diagram of the Stomach and Intestines to show their course. 1. Stomach. 2. (E5iopliagus. 3. Left, and 4. Right end of stomach, fl, 6. Ducdenum. 7. Convolutions of jejunum. 8. Those of ileum. 9. Cjecum. 10. Ver- miform appendix. 11. A.-conding; 12. Transverse; and 1.3. descending colon. 14. Commencement of sigmoid flexure. 15. Rectum. DIGESTIVE ORGANS. 75 primarily developed in the substance of the membrane lining the mouth; and that their enclosure in the substance of the alveolar arches of the jaws occurs subsequently. The number of the teeth is sixteen in each jaw. These are divided into cla?ses, according to their shape and use. There are, in each jaw, fonr u I ciso res ; two ciispidati or canine teeth; fonr bicuspidati ; and six molares or grinders. Each tooth has three parts : — the crmvji, neck, and faiig or roof.; — the first being the part above the gum ; the second that embraced by the gum; and the third, that contained in the alveolus or socket; The crown varies in the different classes. In the incisors, it is wedge-shaped; in the canine, conical; and in the molar, cubical. In all, it is of extreme hardness, but in timiC wears away by the constant friction to which it is exposed. The incisor and canine teeth have only one root ; the molares of the lower jaw, two ; and the upper, three. In all cases, they are of a conical shape, the base of the cone corresponding to the corona, and the apex to the bottom of the alveolus. The alveolar margin of the jaws is covered by a thick, fibrous, resisting substance, called g7im. It surrounds accurately the inferior part of the crown of the tooth, adheres to it strongly, and thus adds to the solidity of the junction of the teeth with the jaws. It is capable of sustaining considerable pressure without inconvenience. — But we shall have to return to the subject of the teeth hereafter. The articulation of the lower jaw is of such a nature as to admit of depression and elevation ; of horizontal motion forwards, backwards, and laterally ; and of a semi-rotation upon one of its condyles. The muscles that move it may be thrown into two classes : — elevators and depressors. These, by a combination of their contraction, can produce every intermediate movement between elevation and depression. The raisers or levator muscles of the jaw extend from the cranium and upper jaw to the lower. They are four in number on each side, — the temporal and masseter, which are entirely concerned in the func- tion; t\xe external ptery- goid^ which, whilst it raises the jaw, carries it at the same time forward, and to one side; and the internal pterygoid^ which, ac- cording as it unites its action with the tem- poral or with the ex- ternal pterygoid, is an elevator of the jaw or a lateral motor. The depressors may be divided into immediate and mediate, according as they are, or are not, attached to the lower jaw itself. There are only three of the former class : 1, the digastricus^ the anterior fasciculus of which, or that which passes from the os hyoides to the lower jaw, depresses the latter ; 2, the genio- hyoidens; and 8, the mylo-hyoidens^ all of which concur in the formation of the floor of the mouth. The indirect or mediate depressors are all Skull of the Polar Bear. 76 DIGESTION-. those, that are situate between the trunk and the lower jaw, without being directly attached to the latter ; — as the thyro-liyoideus^ the sterno- thyroideus, and the omo-hyoideus ; the names of which indicate their origin and insertion. These, in the aggregate, form a muscular chain, which, when it makes the trunk its fixed point, depresses the lower jaw. The arrangement of the elevators and depressors is such, that the former predominate over the latter ; and hence during sleep the jaws continue applied to each other, and the mouth is consequently closed. The human organs of mastication hold an intermediate place between those of the carnivorous and herbivorous animal. In the carnivorous animal, which has to seize hold of, and retain its prey between its teeth, the jaws have considerable strength; and the movement of ele- vation is all that is practicable; or, at least, that can be effected to any extent. This is dependent upon organization. The condyle is broader from side to side, which prevents motion in that direction : the glenoid cavity is very deep, so that the head of the jaw-bone cannot pass out of it; and it is, moreover, fixed in its place by two eminences before and behind. The muscular apparatus is also so ar- ranged as to admit of energetic action on the part of the muscles that raise the jaw ; but of scarcely any in a hori- zontal direction. The deep impres- sions in the regions of the temporal and masseter muscles indicate the large size of these muscles in the purely carnivorous animal; whilst the pterygoid muscles are extremely small. The teeth, too, are charac- teristic ; the molares being compara- tively small, at the same time that they are much more pointed. On the other hand, the cuspidati are remark- able^ large, and the incisors, in general, acuminated. The herbivorous animal has an ar- rangement the reverse of this. The condyle or head of the lower jaw is rounded ; and can, therefore, be moved in all directions ; and as easily horizontally as up and down. The glenoid cavity is shallow, and yields the same facilities. The articulation, which is very close in the carnivorous animal, is here quite loose. The levator muscles are much more feeble ; the temporal fossa is less deep ; the zygomatic arch less convex; and the zygomatic fossa less extensive. On the other hand, the pterygoid fossa is ample and the muscles of the same name are largely developed. The molares are large and broad ; and their magnitude is so great as to require, that the jaw should be much elongated in order to make room for them. The joint of the lower jaw has, in man, solidity enough for the jaws Skull of the Cow. DIGESTIVE ORGANS — SALIVARY GLANDS. 77 to exert considerable pressure with impunity, and laxity enough that the lower jaw may execute horizontal movements. The action of the levator muscles is the most extensive; but the lateral or ginnding motion is practicable to the necessary extent ; and the muscles of both kinds have a medium degree of developement. The teeth, likewise, partake of the characteristics of those of the carnivorous and herbi- vorous animals ; — twelve — the canine teeth and lesser molares — cor- responding to those of the carnivorous; and twenty — the incisors and larger molares — to those of the herbivorous. The tongue must be regarded as an organ of mastication. It rests horizontally on the floor of the mouth ; is free above, anteriorly ; and, to a certain extent, beneath and at the sides. Behind, it is united to the epiglottis by three folds of the mucous membrane of the mouth; and is supported at its base by the os hyoides, with which it partici- pates in its movements. The tongue, as the organ of taste and articu- lation, is described elsewhere. We have only, therefore, to describe the OS hyoides and its attachment to that bone. The hyoid bone has, as its name imports, the shape of the Greek letter v, the convex part being before. It is situate between the tongue and larynx : and is divided into bod?/ or central jmH ; and into branches, one extremity of which is united to the body by an intermediate cartilage, that admits of slight motion ; whilst the other is free, and is called greater cornu. Above the point, at which the branch is articulated with the body, is an apophysis or process, called lesser cornu. The os hyoides is united to the neighbouring parts by fibrous organs, and muscles. The former are; — above, the stylo-hyoid ligament, which extends from the lesser cornu of the bone to the styloid process of the temporal bone; below, a fibrous membrane, called thyro-hyoid, passing between the body of the bone and the thyroid cartilage ; and two ligaments, extending from the greater cornu of the hyoid bone to the thyroid cartilage, called thyro-hyoid. Of the muscles ; some are above the hyoid bone, and raise it; — viz., ^ul\Qgenio- and mylo-hyoideus, already referred to; the stylo-hyoid, and some fibres of the viiddle constrictor of the -pharynx. Others are below, and depress it. They are the sterno-thyro-hyoideus, omo-hyoideus and sterno-thyroideus. The base of the tongue is attached to the body of the bone by a ligamentous tissue, and by the fibres of the hyoylossus muscle. Among the collateral organs of mastication are those which secrete the saliva, and the various fluids which are poured out into the mouth, — constituting together what has been termed the apparatus of insali- vation. These fluids proceed from different sources. Ihe mucous membrane of the mouth, like other mucous membranes, exhales a serous or albuminous fluid, besides a mucous fluid secreted by the numerous follicles contained in its substance. Four glands likewise exist on each side, destined to secrete the saliva, which is poured into the mouth by distinct excretory ducts. They are \he parotid, submax- illary, sublingual, and intra-liitgual or lingual. The first is situate between the ear and the jaw; and its excretory duct opens into the mouth opposite the second small molaris of the upper jaw. By press- ing upon this part of the cheek, the saliva can be made to issue into the mouth, in perceptibly increased quantity. The submaxillary DIGESTION". glaud is situate beneatli the base of the jaw; and its excretory duct opens into the mouth, at the side of the frae- nuni linguas. The sublingual gland is situate under the tongue, and its ex- cretory ducts open at the sides of that or- gan, and the intra- lingual or lingual is seated at the inferior surface of the tono;ue, where the mucous membrane forms a fringed fold. The saliva, as met with, is a compound of eve- ry secretion poured into the mouth; and it is this fluid which has been chiefly sub- and its various pro- Salivary Glands in situ. 1. Parotid gland in situ, extending from tlie zygoma above, to the angle of tlie jaw lielow. 2. Duct of" Steno. 3. Submaxillary gland. 4. Its duct. 5. Sublingual glaud. jected to analysis. The secretion of the saliva, perties, will be considered, however, hereafter. The two apertures of the mouth are the labial and 'pharyngeal. The- former, as its name imports, is formed by the lips, which consist ex- ternally of a layer of skin; are lined internally by a mucous mem- brane; and, in their substance, contain numerous muscles, elsewhere described under the head of Gestures. These muscles may be ^0,-^2,- rated into constrictors and dilators ; the orbicularis oris being the only one of the first class, and the antagonist to the others, which are eight in number, on each side — levator labii superior is alceque nasi, levator lahii snperioris proprius, levator anguli oris, zygomaticus major, zygoma- iicifs minor, huccinator, triangularis, and quadratus inenti. To the last two muscles are added some fibres of the j)latysma myoides. The pharyngeal opening is smaller than the labial, and of a quadri- lateral shape. It is bounded above by the velum palati or jjcnduJous veil of the palate ;^ below, by the base of the tongue; and laterall}', by two muscles, which form iho, jyiUars of the fauces. The pendulous veil is a musculo-membranous extension, constituting a kind of valve, at- tached to the posterior margin of the bony palate, by which all com- munication between the mouth and pharynx, or between the pharynx and nose can be prevented. To produce the first of these eftects, it becomes vertical; to produce the latter, horizontal. At its inferior and free margin, it has a nipple-like shape, and bears the name of uvula. It is composed of two mucous membranes, and of muscles. One of the membranes, — that forming its anterior surface, — is a pro- longation of the membrane lining the mouth, and contains numerous follicles; the otlier, forming its posterior surface, is an extension of the mucous membrane lining the nose, and is redder, and less pro- vided with follicles than the other. The muscles that constitute the DIGESTIVE ORGANS — CESOPHAGUS. 79 body of the velum palati are — the circumjiexus jxilati or spheno-salpingo-staj)hylinus of Chaussier; the levator pah ti or petro-salpingo-staphylinus ; and the azygos uvulce or palato-sta- jihylinus. The velum is moved by eight muscles. The two internal pterygoids raise it; the two external pjtery golds stretch it transversely; the Wo p)alaio- P'haryngei or pharyyigo-stajihy- Imi, and the two co7istrictores isthnii faiicium or glosso-staphy- Uni carry it downwards. The last four muscles form the pil- lars of the fauces ; — the first two the posterior pillars ; and the last two the anterior ; be- tween which are situate the ton- sil glands or amygdalce^ which are composed of a congeries of Fig. 6. Cavity of the Mouth, as shown by dividing the Angles and turning off the Lips. 1. Upper lip, turned \\p. 2. Its frasnum. 3. Lower lip, turned down. 4. Its frteuum. 5. Internal surface of cheeks. 6. Opening of duct of Steno. 7. Eoof of mouth. S. Anterior portion of lateral half arches. 9. Posterior portion of lateral half arches. 10. Velum pendulum palati. 11. Tonsils. 12. Tongue. mucous follicles. Fig. 7. Pharynx seen from behind. 1. A section carried transversely through base of skull. 2, 2. Walls of pharynx drawn to each side. 3, 3. Posterior nares, separated by vomer. 4. Extremity of Eustachian tube of one side. 5. Soft palate. 6. Posterior pillar of soft palate. 7. Its anterior pillar ; the tonsil seen situate in the niche between the two pillars. 8. Root of tongue, partly concealed by uvula. 9. Epiglottis over- hanging (10) opening of glottis. 11. Posterior part of larynx. 12. Opening into oesophagus. 13. External surface of (Esophagus, li. Trachea. Longitudinal Section of the Oesophagus, near the Pha- rynx, seen on its inside. 1, 1. Superior part near pha- rynx. 2, 2. Longitudinal folds of its mucous membrane. 3, 3. Prominences formed by its mu- ciparous glands. 4,4. Capilla- ry bloodvessels. 5. Shows the muscular coat after the mucous coat has been turned ofl'. 1^^ Section of the (Esophagus. n, h. Internal circular fibres. c. External lon- gitudinal fibres. 80 DIGESTION. 2. The pharynx and oesophagus constitute a muscular canal, which forms the medium of communication between the mouth and stomach, and convcj^s the food from the former of these cavities to the latter. The pharynx has the shape of an irregular funnel, — the larger open- ing of the funnel looking towards the mouth and nose; the under and smaller end terminating in the oesophagus. Into its upper part, the nasal fosste. Eustachian tubes, mouth, and larynx open. It is inservient to useful purposes in the production of voice, respiration, audition, and digestion; and extends from the basilary process of the occipital bone, to which it is attached, as far as the middle part of the neck. Its trans- verse dimensions are determined by the os hj^oides, larynx, and ptery go- maxillary apparatus, to which Fig- 10. it is attached. It is lined by a mucous membrane, less red than that which lines the mouth, but more so than that of the ossophagus, and the rest of the digestive tube; and it is remarkable for the deve- lopement of its veins, which form a very distinct network. Around this is the muscular la^^er, the circular fibres of which are often divided into three muscles — superior, mid- dle, and inferior constrictors. The longitudinal fibres form part of the stylopharyngei and pxdato-pjharyngei muscles. The pharynx is raised by the action of the last two muscles, as well as by all those that are situate between the lower jaw and os hyoides, which cannot raise the latter without, at the same time, raising the larynx and pharynx. These muscles are: — mylo-hyoideus, genio-hyoidcvs, and the anterior belly of the digastricus. The oesophagus is a continua- tion of the pharynx ; and ex- tends to the stomach, where it terminates. Its shape is cylin- drical, and it is connected with the surrounding parts by loose and extensible areolar tissue, which yields readily to its movements. On entering the abdomen, it passes between the pillars of the diaphragm, with which it is intimately united. The } A view of the Muscles of the Tongue, Palate, Larynx and Pharynx — as well as the position of the upper portion of the (Esophagus, as shown by a vertical section of the head. 1, 1. The vertical section of the head. 2. Points to the spinal canal. 3. Serticm of the hard palate. 4. Inferior spnngy bone. !>. Middle sponey hone. 6. Orifice of the right nostril. 7. Section of theinferior maxilla. S. Sec- ti.>n of the os hyoides. ft. Section of the epiglottis. 10. Section of the cricciid cartilage. 11. The trachea, covered by its lining memhi-ane. 12. Section of sternum. 13. In- side of the npper portion of the thorax. 14. Genio-hyo- glossus mu.-;cle. l.i. Its origin. 16, 17. The fan-like ex- pansion of the fibres of this mnscle. IS. Superfioialis linguse muscle. 19. Verticalis lingua; muscle. 20. Genio- liyoidons muscle. 21. Jlylo-hyoideus muscle. 22. An- terior belly of digastricus. 23. Section of platysma myoi- des. 24. Levator meuti. 2o. Orbicularis oris. 26. Orifice of Eustachian tube. 27. Levator palati. 28. Internal pterygoid. 2.0. Section of velum pendulum palati, and a/.ygos uvulaj muscle. .30. Stylo-pharyngeus. 31. Con- strictor pharyngis superior. 32. Constrictor pharyngis medins. .33. Insertion of stylo-pharyngeus. 34. Con- strictor pharyngis inferior. .35, .36, 37. Muscular coat of wsophagus. 3S. Thyreo-arytenoid muscle and ligaments, and above is the ventricle of Galen. .39. Section of aryte- noid cartilage. 40. Border of sterno-hyoideus. DIGESTIVE ORGANS — STOMACH. 81 mucous membrane lining it is pale, tliin, and smooth ; forming longi- tudinal folds, well adapted for favouring tlie dilatation of the canal. Above, it is confounded with that of the pharynx ; but below, it forms several digitations, terminated by a fringed extremity, which is free in the cavity of the stomach. It is well supplied with mucous follicles. The muscular coat is thick ; its texture is denser than that of the pharynx, — and cannot, like it, be separated into distinct muscles, but consists of circular and longitudinal fibres, the former of which are more internal, and very numerous, the latter external and less nume- rous. 3. The stomach is situate in the cavity of the abdomen, and is the most dilated portion of the digestive tube. It occupies the epigastric region, and a part of the left hypochondre. Its shape has been com- pared, not inappropriately, to that of the bag of a bag-pipe. It is capable of holding, in the adult male, when moderately distended, about three pints. The left half of the organ has always much greater Fig. 11. Stomach yeen Externiilly. A, A. Anterior surface. B. Enlargement at lower part. D. Cardiac orifice. E. Commencement of duodenum. F and C. Coronary vessels. II. Omentum. dimensions than the right. The former has been called the spJmic portion, because it rests upon the spleen ; the latter the }yylonc portion^ because it corresponds to the pylorus. The inferior border of the stomach, which is convex, is termed the (jn^at cunature or arch; the VOL. I. — 6 82 DIGESTION. superior border, tlie lesser curvat^rre or arch. The two orifices are the cesophageal^ cardiac or vj)per orifice^ formed bj the termination of the oesophagus; and the intestinal.^ pyloric or inferior orifice.^ which com- municates with the small intestine. The three coats that constitute the parietes of the stomach, are ar- ranged in a manner the most favourable for permitting variation in the size of the organ. The outermost or jjeritoneal coat consists of two laminse, which adhere but slightly to the organ, and extend beyond it, where they form the epiplooiis or omenta.^ the extent of v/hich is in an inverse ratio to the degree of distension of the stomach. The omentum majus or gastro-colic epiploon is the part that hangs down from the stomach in Fig. 11. The mucous or lining membrane is of a whitish, marbled, red appear- ance, having a number of irregular folds, situate especially along the inferior and superior margins of the organ. These folds are evident, also, at the splenic extremity ; and are more numerous and marked, the more the stomach is contracted. They are radiated towards the cardiac, — longitudinal towards the pyloric, orifice. This membrane, like every other of the kind, exhales an albuminous fluid. It contains. Fig. 12. Fig. 13. Vertical and Longitudinal Section of Stomach and Duodenum. 1. CEsophagiis ; upon its internal surface, the plicated arrangement of cuticular epithelium shown. 2. Cardiac orifice of stomach, around which the fringed border of cnticolar epithelium is seen. 3. Great end of stomach. 4. Its lesser or pyloric end. 5. Lesser curve. 6. Greater curve. 7. Dilatation at lesser end of stomach which re- ceived from Willis the name of antrum of 2?ylorus. This may be regarded as the rudiment of a second stomach. 8. Rugie of the stomach formed by mucous membrane : their longitudinal direction is shown. 9. Pylorus. 10. Oblique portion of duodenum. 11. Descending portion. 12. Pancreatic duct, and ductus communis choledochus, close to their termination. 1.3. Papilla upon which ducts open. 14. Transverse portion of duodenum. 1.5. Cora- niencement of jejunum. In interior of duodenum and jejuntim, the valvula conniventes are seen. Section of a piece of Stomach not far from Pylorus. 1. Magnified about three diameters. 2. A few of the glands with their racemiform ends distended with fluid, magnified about 20 diameters. likewise, many follicles, which are especially abundant in the pyloric portion. Several, also, exist in the vicinity of the cardiac orifice, but ia the rest of the membrane they are few in number. When examined DIGESTIVE ORGANS — STOMACH. 83 witli a magnifying glass, the internal or free surface presents a peculiar honeycomb or reticulated appearance, produced by shallow polygonal Fig. 14. Fig. 15. Ml ^-fjiMii^ A portion of the Mucous Mombrane of the Stomach magnified seventy-live times. The alveoli measured l-200th of an inch in length, by l-2.50th in breadth ; the width of the septa being 1-lOOOth of an inch. The smaller alveoli measured l-2.)0th of an inch in length, and l-300th in breadth. The trifid or quadrifid di- vision of a small artery is seen at the bottom of each alveolus, and in the depressions between the divisions of the artery, the apertures of the gastric follicles ; two, three, or four in each de- pression. Tubular Follicle of Pi Stomach. depressions or cells as represented in the marginal figures. The di- ameter of these cells varies from g^^th to 3I o^^ of ^^ inch ; but, near the pylorus, it is as much as jljjth. of an inch. In the bottom of the cells, minute openings are visible, which are the orifices of perpen- dicular glands embedded, side by side, in bundles in the substance of the mucous membrane, and composing nearly the whole structure.^ These tubular follicles vary in length from one-fourth of a line to nearly a line. They are longer and more closely set towards the py- lorus than elsewhere, their length being equal to the thickness of the mucous membrane of the stomach, which varies. The office of the tubular follicles, it has been thought, is to secrete the gastric fluid, during digestion ; for in the intervals they are at rest. They are formed by inflections of basement membrane, with cylindrical epithelium resting upon it. One of them is represented in tlie marginal figure, which exhibits the nucleated cells at the bottom of the follicle becoming more and more developed as they approach the free surface. These cells prepare the gastric fluid, and ultimately burst and discharge it to become mixed with the aliment in the stomach, the elaboration of the fluid in these cells seeming to be perfected only as they reach the surface, inasmuch as, according to M. Bernard,^ the mucous membrane is not acid a little below the surface. Professors Donders and Kcilliker are of opinion, that there are two great varieties of glands in the human stomach, — the ])eptic gastric glands^ with j)eptic stomach ov rennet cells, of the latter observer; and the simple mucous glands with cylinder epithelium, as represented in the subjoined figures from Kolliker. Thus far, however, they have only been seen in ani- ' Dr. Sprott Boyd, Edinb.'Med. and Surg. Journal, vol. slvi. ; aud E. Wilson, Lond. Med. Times and Gazette, Feb. 3, 1855. 2 Gaz. Med. de Paris, xix., Mars, 1844. 84 DIGESTION. mals.* Between the different tubular follicles blood-vessels pass up and form a vascular network, in the interspaces of which the orifices of the Fig. 16. Fig. 17. Fig. 18. Peptic Gastric Gland. a. Common trunk. b,h. Its chief branches, c.c. Terminal cseca with spheroidal gland-cells. Portions of one of the caeca more highly magnitied, as seen lungitudinnliy (a), and in transverse section (b). a. Basement membrane. 6. Large glandular celLs. c. Small epithelium-cells sur- ruunding the cavity. Fig. 19. Mucous Gastric Gland, with Cylinder-Epithelium. a. Wide trunk. 6, b. Its caecal appendages. Capillary Network of the Lining Membrane of the Stomach, with the Orifices of the Gastric Follicles. ' KiJlliker, Mikroskopische Anatomie, 2ter Band. S. 141, Leipz., 1852. Manual of Human Histology, translated by Busk and Huxley, Sydenham Society's edit., ii. 87, Lond., 1854; and American edit., by Dr. Da Costa, p. 507, Philad., 1854. DIGESTIVE ORGANS — STOMACH. 85 follicles are seen ; and Kcilliker^ observed in the villi numerous mus- cular fibre cells. Briicke^ had already pointed out a thin layer of smooth or organic muscular fibres, separated from the rest of the mus- cular membrane by connective tissue. Besides these glands or follicles, small opaque, white sacculi, re- sembling Peyer's glands, are met with, which are filled with minute cells and granules. They are situate chiefly along the lesser curvature of the stomach beneath the lining membrane ; are probably concerned Fig. 20. Vertical Section of a Gastric Follicle, with its Tubes. A. In the middle region, b. In the pyloric region. a, a. Orifices of the celLs on the inner surface of the stomach, b, b. Different depths at which the colum- nar epithelium is exchanged for glandular, c. Pylo- ric tube, or prolonged stomach cell. d. Pyloric tubes, terminating variously, and lined to their ex- tremities with sub-columnar epithelium. From the dog, after twelve hours' fasting. Magni- fied 200 diameters. Mucous Membrane of the Stomach. A. Inner surface of the stomach, showing the cells after the mucus has been washed out. — Magnified 2.5 diameters. B. Columnar epithelium of the inner surface and cells of the stomach, a. Free ends of the epithelial particles, seen on looking down upon the membrane, b. Nuclei visible at a deeper level, e. The free ends seen obliquely, d. Deep or attached ends of the same. The oval nuclei are seen near the deeper ends. From the dog. — Magnified 300 diameters. in the separation of some secretion from the blood, and, when filled, burst, like other secreting cells, and discharge their contents into the stomach.^ Dr. Neill,"* from his histological examinations of the stomach, has ' Op. cit. 2 Sitzungsbericht. der Wiener Akad., vi. 214, and Canstatt's Jaliresbericht, 1851, S. 119, WiirzWrg, 1851. 3 Kirkes and Paget, Manual of Physiology, 2d Amer. edit., p. 167, Pliilad., 1853. * Amer. Journ. of the Med. Sciences, Jan., 1851. 86 DIGESTION. described the arrangement of tlie mucous membrane as differing essen- tially in the cardiac^ middle and pyloric portions. In the first portion it is reticulated ; in the last, villous ; whilst the second is, so to speak, Fig. 22. Appearance of the Lining Membrane of the Stomach, in an injected preparation. A. From the convex surface of the rugje. b. From the neighbourhood of the pylorus, where the ori- fices of the gastric follicles occupy the interspaces of the deepest portions of the vascular network. . . * in a transition state. In the cardiac portion the blood-vessels appear to surround the orifices of the tubes ; whilst in the pyloric portion villi are distinct, but not as much so as in the small intestines. This arrange- ment would favour the idea, that secretion takes place more especially in the former situation, whilst absorption occurs more largely in the latter. The view is not, however, supported by Mr. Erasmus Wilson,^ who describes the reticular arrangement as existing over the whole of the linino; membrane, and it Fig- 23. does not accord with the observations of those who consider the follicles to be especially abundant in the pyloric portion. The 'pyhrus^ or the part at which the sto- mach terminates in the small intestine, ismarked, externally, by a manifest narroAvuess. Internally, the mucous membrane forms a circular fold, which has been called valve of the pyhriis^ be- tween the two laminae of Front View of Stomach, distended hy flatus, with Peritoneal wllich, a denSC, fibroUS tissue exists. This has 1. Antoriorface of oesophagus xtremifv- 4 Dii ^ „, „. L portion of the tliors, pvloric muscU. ar fibres of the ^m 7 i he muscular coat, which is exterior to the mucous coat, — as in the parts of the digestive tube already described, — consists of several Coat turned off. _ _ Cul-de-sac, or greater ex- 'Upp.-i ooPprl Kv qnmp nil tremity. 3. Lesser or pyloric extremity. 4. Duodenum. 5,5. uecu V..;eaI. Pneiunogastric and Spinal Accessorj' Nerves, or the Eighth Pair. 1. The inferior maxillary nerve. 2. The gustatory nerve. 3. The chorda tympani. 4. The auricular nerve. 5. Its coniniuni- Ciition with the portio dura. 6. The facial nerve coming out of tlie stylo-mastoid foramen. 7. The glosso-pharyngeal nerve. 8. Brauehe.s to tlie stylo-pharyngeus muscle. 9. Tlie pharyngeal f-, 1 /> 1 branch of the pnoumogastric nerve de.scending to form the piuiryn- bOme proceed irom tne gealplexu.s. lO. Brauche-ioftheglo.sso-pliaryngealtothepliaryn- .l ,• p geal plexus. 11. The pneumogastric nerve. 12. The pharyngeal great SympatnetlC, irOm piexus. 13. The superior laryngeal branch. 14. Branchob' to the flip or^y^r\n T^lpvna nnrl pharyngeal plexus. 15, 15. Communication of the superior and tuc uu^iicio pn..Ji.u&, aiiu. inferior laryngeal nerves. 16. Cardiac branches. 17. Cardiac branches from tlie right pneumogastric nerve. IS. Tlie left car- diac ganglion and plexus. 19. The recurrent or inferior laryngeal nerve. 20. Branches sent from the curve of the recurrent nerve to the pulmonary plexus. 21. The anterior pulmonary plexus. 22, 22. The ojsophageal plexus. nished by the pneumo- gastric or eighth pair, the two nerves of which surround the cardiac orifice like a ring. The number of the nerves, and the variety of sources whence they are derived, explain the great sympathetic influ- ence exerted upon the stomach by aft'ections of other parts of the system. It sympathizes, indeed, with every protracted morbid change coeliac plexus, accompany the arteries through all their ramifi- cations. Others are fur- 88 DIGESTION. in the individual organs ; and hence was termed, by Mr, Hunter, the centre of sympatliks. Like the teeth, the human stomach holds a medium place between that of the carnivorous and herbivorous animal. As the former makea use of aliment, which is more readily assimilated to its own nature, and more nutritious, it is not necessary that it should take food in such laro-e quantities as the lattei', or that this should remain so long in the stomach. On this account, the organ is generally of much smaller size. On the other hand, as the herbivora subsist solely upon grass, which contains but a small quantity of nutritious matter, and that not easy of assimilation, it is important that the quantity taken in should be ample; that it should remain for some time in the organ subjected to the action of its secretions ; and, in the ruminant class, be returned into the mouth, to undergo fresh mastication. In this class, the stomach is of prodigious extent. In the ox, which we may take as an example of the general structure of the organ, it consists of four separate compartments. The first stomach, A A, Fig. 25, ventriculus or paunchy is much the largest. Externally, it has two sacs or appendices ; and, internally, is slightly divided into four compartments. The second stomach is tlie reticulum^ lonnet or honey- comb hag, B, which appears to be a globular appendix to the paunch. It is situate to the right of the oesophagus, Gr, and has usually a thicker muscular coat than the paunch. Its inner surftice is arranged in irregular pentagonal cells, and is covered with fine papillaB. The third stomach, C, is the smallest, and is called omasum or manyplies. It is of a globular shape, and has a thinner muscular coat than the former. It consists of numerous broad laminte, sent off from the in- ternal coat, running in a longitudinal direction, alternately varying in breadth, and covered with small o-ra- nular papilke. The fourth stomach, D, is the abomasum, ventriculus intes- tmalis, reed, or caillette. It has a pyri- form shape, and is next in size to the paunch. It has large longitudinal rugi^, covered with villi. The mus- cular coat is still thinner than that of the former. This stomach is the only one that resembles the human organ; and, in the young of the ruminant animal, with the milk cur- dled in it, forms the runnet or rennet. The property of curdling milk is, however, possessed by all digestive stomachs. The inner surftice of the three first stomachs is covered with cuticle ; whilst that of the fourth is lined by a true mucous or secreting membrane. There is in the interior arrangement of the stomachs of the ruminant animal a sin- gular provision by which the food can be either received into the first Fi?. 25. Stoinanh of the Ox. A, A. Paunch T>. Abomasuiu. G. CEsophagus. B. Ri'ticulum. E Pylorus. F. ^. Omasnm. Buodeuuin. DIGESTIVE ORGANS OF THE RUMINANT ANIMAL. 8^ and second stomachs, or be carried on into the third, if its character be such as to be fitted at first for the action of the omasum. From the oesophagus, in Fig. 26, a gutter or demi-canal passes into the second and third stomachs. The third leads into the fourth by a narrow opening, and the fourth terminates in the duodenum, which has a pylorus at its origin. AVhen the animal eats solid food, it is, after slight mastication, passed into the paunch, and thence, by small poitions, into the second stomach. When this has become mixed with Fig. 26. Fig. 27. Section of part of the Stomach of the Sheep, to m show the demi-canal of the oesophngiis; the mucous membrane is for the most part re- " moved, to show the arrangement of the mus cular fibres. At a is seen the termination of the oesophageal tube, the cut edge of whose mucous membrane is shown at b. The lining of the first stomach is shown at e, c ; and the mucous membrane of the second stomach is seen to be raised from the sub- n P Digestive Apparatus of Common Fowl. a. OSsophagus. b. Ingluvies or crop. c. Proven- jacent fibres at (7. At e,e, tlie lips of the demi-canal triculus. rf. Gizzard, e. Liver. /.Gall-bladder, g. are seen bounding the groove, at the lower end of Pancreas, h. Duodenum, i. Small intestine, k. which is the entrance to the third stomach or many- C-eca. I. Large intestine, m, m. Ureters, n. Ovi- pUes. duct. o. Cloaca. fluid, and kept for some time at a moderately high temperature, a morsel is thrown back with velocity from the stomach into the mouth, where it is "ruminated," and then swallowed and passed on into the third stomach, — the groove or gutter being now so contracted as to form a channel for its passage through the fii'st two. In the third and fourth stomachs, more especially the latter, true digestion takes place. When the food is of such a character as not to require rumination, it can be sent on directly into the third stomach, by the arrangement just described. 90 DIGESTION. In bird tribes, we see an admirable adaptation of structure to the functions which the digestive organs have to execute. Animals of this class may be divided into the granivorous and the carnivorous. It is in the former, that we are so much impressed with the organiza- tion of this part of their economy. The grain on which they feed, although more nutritious than grass, which constitutes the aliment of the herbivorous quadruped, requires equal difficulty in being assimi- lated to the nature of the being it has to nourish. Added to this, it is in such a condition, that the juices of the digestive organs cannot readily act upon it. The bird having no masticatory apparatus within the mouth, the grain must of necessity be swallowed whole. But we find that lower Fig- 28. down in the ali- mentary tube, a powerful mastica- tory apparatus ex- ists, which has fre- quently been con- sidered as a part of the digestive sto- mach ; but really seems destined for mastication only. The following is the arrangement of their gastric appa- ratus. The oesophagus terminates at the bottom of the neck in a large sac — in- gluvies, crop or craw — which is of the same structure with the oesophagus, but thinner. On the inner side of the crop are numerous glands, with very distinct orifices in large birds, which secrete a fluid to as- sist in the solution of the food. To the crop succeeds an- other cavity, in the shape of a funnel, called proventriculus, irtpmdiljnlurii or second stomach. This is seated in the abdomen, and is generally smaller than the former. It is usually thicker than the cesophagus, partly owing to its numerous glands, which are very large and distinct in many birds. In the ostrich, they are as large as the garden-pea, and have very manifest Gastric Apparatus of the Turkey. DIGESTIVE OEGAXS OF THE GALLHSTACEA. 91 orifices. The infundibulum terminates in the ventriculus callosus, giz- zard or third stomach — the most curious of all the parts of the apparatus. Figs. 28 and 29 afford an external and internal view of the gastric apparatus of the turkey ; «, representing the oesophagus immediately below the crop, covered with cuticle ; h, the openings of the gastric glands in the second stomach, placed on a surface, that has no cuticular covering ; c, horny ridges, between the Fig- 29. gastric glands and the lining of the gizzard ; cZ, a minutely granu- lated surface between the cavity of the giz- zard and duodenum; and e, the inner sur- face of the duodenum. Fig. 28 accurately re- presents the mode in which the second sto- mach terminates in the gizzard, and the latter in the duodeuum ; the gizzard formingakind of pouch depending from the alimentary canal. The gizzard is usually of a globular figure, flattened at the sides, and is consider- ed to consist of four muscles, remarkable for their great thick- ness and streno;th ; — a large hemispherical pair at the sides, and a small pair situate at the extremities of the stomach. The gizzard is covered externally by a beautiful tendinous ex- pansion; and is lined by a thick, strong, callous coat, which appears to be epidermous in its character. On this are irregularities, adapted to each other on the opposite surfaces. The cavity of the organ is remark- ably small, when compared with its outward magnitude, and its two ori- fices, represented in ¥ig. 28, are very near each other. In the pouch formed by the small muscles at the lower part of the gizzard, numerous pebbles are contained, which seem to be indispensable to the digestion of certain tribes, by acting as substitutes for teeth. In the gizzard of the tur- key, two hundred have been found ; in that of the goose, one thousand.^ ' J. Hunter, Observations on certain parts of the Animal Economy, with Notes by Prof. Owen, Amer. edit., p. 119, Philad., 1840 ; and Roget, Animal and Vegetable Phy- siology, Amer. edit., ii. 126. Philad., 183(J. Interior of the Gastric Apparatus of the Turkey. 92 DIGESTION. The prodigious power with which the digastric muscle — as it has been termed — acts, and the callous nature of the cuticle, are strikingly mani- fested by certain experiments, instituted by the Acaclemia del Cimento^^ and by Eedi, Reaumur,^ and Spallanzani.^ They compelled geese and other birds to swallow needles and lancets, and in a few hours after- wards killed and examined them. The needles and lancets were uni- formly found broken off and blunted, without the slightest injury having been sustained by the stomach. In the carnivorous bird, the food being readily assimilated, in con- sequence of its analogy to the substance of the animal, the gastric apparatus is as simple as in the carnivorous mammalia. The oesopha- gus is of great size for receiving the large substances swallowed by these animals, and for enabling the feathers and other matters, that cannot easily be digested, to be rejected by the mouth. The stomach is a mere musculo-membranous sac ; but the secretion from it is of a potent character, so as to enable the animal to dispense with mastica- tion, and yet to admit of the stomach and intestines being disposed within a small compass, so as to give them the necessary lightness to fit them for flight. We can thus, from organization, generally form an idea of the kind of food for which an animal is naturally destined ; whether, for exam- ple, it is naturally granivorous or carnivorous. There are some strik- ing facts, however, that exhibit the signal changes exerted, even on organization, by restricting an animal to diet of a different character from that to which it has been accustomed ; or to one which is foreign to its nature. In birds of prey, the digastric muscle has the bellies, which compose it, so weak, that, according to Sir Everard Home,-* nothing but an accurate examination can determine its existence. But if a bird of this kind, from want of animal food, be compelled to live upon grain, the bellies of the muscle become so large, that they would not be recognized as belonging to the stomach of a bird of prey. Mr. Hunter kept a sea-gull for a year upon grain, when he found the strength of the muscle much augmented. This wondrous adaptation of structure to the kind of food which the animal is capable of obtain- ing, is elucidated by the South American and African ostriches. The former is the native of a more productive soil than the latter ; and, accordingly, the gastric glands are less complex and numerous; and the triturating organ is less developed.* ■i. The intestines are the lowest portion of tlie digestive apparatus; constituting a musculo-membranous canal, which extends from the pyloric orifice of the stomach to the anus. The human intestines are six or eight times longer than the body; and hence the number of con- volutions in the abdominal cavity. They are attached to the vertebral column by folds of peritoneum called mesentery ; and according to the length of these folds or duplicatures the intestine is bound down, or ' Exper, fatte nell' Acad, del Cimento, 2da ediz., Firenz., 1691. 2 Memoir de I'Acad, pour 1752, p. 2(36 and p. 46i, 3 Dissertations relative to the Natural History of Animals and Vegetables, English translation, i. 16, London, 1789. •* Lectures on Comparative Anatomy, i. 271, Lond., 1814, 5 Ibid., i. 293. See, on all this subject, Carpenter's Principles of Comparative Phy- siology, Amer, edit,, pp, 190 and 200, Philad., 1854. I DIGESTIVE ORGANS — INTESTINES. 93 Fig. 30, floats in the abdominal cavity. Their structure is nearly alike through- out: a mucous membrane lines them: immediately without this is a muscular coat; and, externally, a serous coat, formed by a prolonga- tion of the peritoneum. The mucous membrane is soft and velvety, and is the seat of a similar secretion to that of other membranes of the same class. The muscular coat is composed of two planes of fibres, so united that they cannot be separated, — the innermost consisting of circular, and the outermost of longitudinal fibres, the arrangement of which differs in the small and large intestines. The serous or peri- toneal coat receives the intestine between two of its lamince, which, in their passage to it, form the mesentery. The serous coat only comes in direct contact with the intestine at the sides and forepart. Behind, or on the mesenteric side, is a vacant space, by which the vessels and nerves reach and leave the intestine. These form their first network between the serous and muscular coats ; their second, between the muscular and mucous. Between the upper four fifths of the intestinal canal, and the lower fifth, there is a well-marked distinction ; not only as regards structure and magni- tude, but function. This has given oc- casion to a division of the canal into small and large intestine; and these, again, have been subdivided in the va- rious modes that will fall under con- sideration. As the small intestine forms so large a portion of the intestinal canal, its convolutions occupy con- siderable space in the abdominal cavity, — in the middle, umbilical, and hypogastric regions, — and terminate — in the right iliac region — in the large intestine. Its calibre differs in different parts ; but it may be regarded on the average as about one inch. It is usually divided, arbitrarily, into three parts; — duodenum^ jejunum^ and ileum. The duo- denum, is so called, in consequence of its length having been estimated at about twelve fingers' breadth. It is larger than the rest of the small intestine ; and has received, also, the name o^ second stomach, and of ventriculus siicceniuriatus. It is more firmly fixed to the body than the other intestines; and does not, like them, float loosely in the abdomen. In its course to its termination in the jejunum, it de- scribes a kind of Italic c, the concavity of which looks to the left. From this shape it has been separated into three portions; — the first situate horizontally beneath the liver: the Portion of tlie Stomach and Duodenum laid open to show their interior. 1,1. Right or pyloric extremity of stomach. 2, 2. Folds and mucous follicles of mucous coat of stomach. 3. Points into the pylorus. 4. Thickness of the pylorus. 5, 5. Rugie of the internal coatof the duodenum. 6. Open- ing of the ductus communis choledochus into the duodenum. Longitudinal Section of the Upper Part of the Jejuuum extended under water. 94 DIGESTION. second descending vertically in front of the right kidney ; and the third in the transverse mesocolon. Its mucous membrane presents a number of circular folds or rugee, very near each other, which have been called valvules conniventes. (Figs. 30 and 31.) By some anatomists, however, Fig. 32. Fie. 33. Muscular Coat of the Ileum. 1, 1. Peritoneal coat. 2. A portion of this coat turned off and showing a portion of the longitudinal fibres of the muscular coat adherent to it. 3, -t, 5. Cir- cular muscular fibres indifferent parts of the intestine. Distribution of Ciqullaries in the Villi of the Intestine. i this name is not given to the irregular rugae of its mucous coat; but to those of the lining membrane of the jejunum. The valvules are not simple rugas, passively formed by the contraction of the muscular coat. They are dependent upon the original formation of the mucous mem- Fig. 34. Fie. 35. Arrangement of the capillaries on the mucous membrane of the lari^e intestine in the human subject. — Magnified 50 diameters. Distribution of Capillaries around Follicles of JIucous Membrane. brane; and are not effaced, whatever may be the distension of the intestine. On and between these duplicatures, the difi'erent exhalant and absorbent vessels are situate, forming, in part, the villi of the intes- tine, which are from a quarter of a line to a line and two-thirds in length.^ These villi give to the membrane a veh^ety appearance, and are not simply composed of exhalants and absorbents, but of nerves ; all of which are distributed on an areolar and perhaps erectile tissue. In its healthy state, when successfully injected, the membrane appears to consist almost entirely of a cribriform intertexture of veins. It was formerly believed, that the villi are not supplied with bloodvessels. In each villus, however, there is a minute vascular plexus, the larger branches of which, when distended with blood, may be seen even by the naked eje. Marginal illustration, Fig. 36, exhibits the vessels of one of the intestinal villi of the hare, from Wagner, after an extremely J. Miiller, Elements of Pliy.siology, by Baly, 2d edit., p. 285, Lond., 1S40. DIGESTIVE OEGAlSrS — SMALL INTESTINE. 95 beautiful dry preparation by Dollinger, magnified about 45 diameters. The most obvious use of these villi is to increase the surface from which the secretion is prepared, and from which absorption is effected. Within the membrane are numerous follicles, which, with the exhalants, secrete a mucous fluid, called by Haller succus iritestmalis. Their entire number in the whole alimentary canal is esti- mated by Dr. Horner to be 4(5,900,000.^ At about four or five fingers' breadth from the py- lorus, the duodenum is perforated by the ter- mination of the biliary and pancreatic ducts, which pour bile and pancreatic fluids into it. Generally, these ducts enter the intestine by one opening; at times, they are distinct, and lie alongside each other. The structure of the duodenum is the same as that of the whole of the intestinal canal. The muscular coat is, however, thicker, and the peritoneal coat only covers its first portion, passes before the second, and is totally wanting in the third, which we have described as included in the transverse mesocolon. The other two portions of the small intestine are of considerable length; the jejunum com- mencing at the duodenum, and the ileum termi- nating, in the right iliac fossa, in the first of the great intestines — the cascum. They occupy the middle and almost the whole of the abdomen, being surrounded by the great intestine (1^'ig. 2). The jejunum is so called from being generally found empty ; and the ileum from its numerous windings. The line of demarcation, however, between the duodenum and jejunum, as well as between the latter and the ileum, is not fixed : it is an arbitrary division. Bloodvessels of Villi of the Hare. 1, 1. Veins filled with white injection. 2, 2. Arteries filled with red. A heautifnl rete of capillaries between the two. Fig. 37. Fig. 38. One of the Glanrlulfe Majores Sim- plices of the Large Intestine, as seen from above, and also in a Section. Vertical Section of the Mucous Membrane of the Duodenum in the Horse, slightly magnified. "D. Villi, h, c. Mucons membrane and submacous tis- sue, ff. Brunner's glands cut vertically, and a little spread out, showing their lobulated structure. The jejunum has, internally, the greatest number of valvulse conniventes and villi. The ileum is the lowest portion. It is of a paler colour, and ' Special Anatomy and Histology, 8th edit., ii. 51, Philad., 1851. 96 DIGESTIOISr. I has fewer valvulre conniventes. The jejunum is situate at the upper part of the umbilical region ; the ileum at the lower part, extending as far as the hypogastric and iliac regions. The mucous membrane of the jejunum and ileum resembles, in all essential respects, that of the duodenum; the valvula?. conniventes are, however, more numerous in the jejunum than in the duodenum; and, in the course of the ileum, they gradually disappear, and are replaced by simple longitudinal rugcie. The villi, too, which are chiefly destined for chylous absorp- tion, abound in the jejunum, but gradually disappear in the ileum. The mucous membrane of both is largely supplied with follicles, commonly called glands of Brunner and Lieberkiihn, which are con- cerned in secreting the succus entericus, sneezes intestinalis — a mucous fluid to which, in digestion, Haller attached great importance. M. Lelut* estimates the number of these glands in the small intestine at 40,000. Dr. Horner considers the follicles to be formed, in every in- stance, of meshes of veins; the arteries entering inconsiderably into their composition, — or in about the same proportion as they do in other erectile tissues.^ The tubular glands of the small intestine have long been known under the name o^ follicles of LieberkUlm.. These become especially evident if the mucous membrane is inflamed, when they are filled with an opaque whitish secretion, whieh is absent in the healthy state.' The true glands of Brunn or Brunner are chiefly in the duodenum. They are situate in the submucous tissue, where they form a continu- Fig. 39. Yis. 40. Portion of one of Bruntier's Glands, from the iluniua Duodenum. )a Section of the Mucous Menihrane of the Small Intestine in the Dog, showing Lieberkiihn's follicles and villi. a. Villi. &, Lieberki'.hn's follicles. coals of the intestine. c. Other ous layer of white bodies surrounding the intestine. They are not larger than a hemp-seed; each consisting of numerous minute lobules, ' Gazette Medicale, Juin, 1832. « Op. cit., ii. 54. » Boehm, cited in Brit, and For. Med, Rev., i. 621, Loud., 183ij. DIGESTIVE ORGANS — SMALL INTESTINE. 97 the ducts of which open into a common excretory duct. They a,re com- plex structures, differing from the other glands and follicles of the intes- tines. Nothing is positively known of the nature of their secretion. The glands of Peyer form large patches on the mucous membrane, when they are called glandulce agminaice and Peyer^s patches. Exa- mined in a healthy mucous membrane, they have the appearance of Fiff. 42. a, A. Transverse section of Lieber- kiihn's Tubes or F(41icles. show- iTig t)ie basement-membrane and subcolumnar epithelium of their walls, with the Areolar Tissue which connects the tubes. a. Basement-membrane and epithe- linm, constituting the wall of the tube. h. Cavity or lumen of the tube. Mag- nified 200 diameters. B. A single Lieberkiihn's highly magnifiefl. A happy accidental section in the oblique direction has served to display very distinctly the form and mode i>f packing of the epithelial particles, the cavity of the tube, and the mosaic pavement of its exterior, a. Base- ment-membrane, e. Internal surface of the wall of the tube. Magnified 200 diameters. Horizontal Section through the middle plane of three Peyerinn Glands in the Rabbit, showing the distributiou of the Bloodvessels in the interior. circular white, slightly raised spots, about a line in diameter, over which the mucous membrane is least studded with villi, and often wholly without them. On rupturing one of the white bodies a cavity is found, but it has no excretory duct. It contains a grayish-white mucous matter. There are likewise closed solitary glands in both the small and large intestines.^ At times, however, the aggregatas exhibit openings so distinct, as to have warranted the belief that such openings are the normal condition;^ yet Kcilliker considers it as quite certain, that the follicles of Peyer's patches are shut sacs [gdnzlich geschlossen?f ' Baly, Lond. Med. Gazette, Mar., 1847. '^ Allen Tliomson, in Goodsir's Annals of Anatomy and Physiology, No. 1, p. 34, Feb. 1850; and Carpenter's Principles of Human Physiology, Amer. edit., p. 153, note, Phi- lad., 1855. 3 Mikroskopische Anatomie 2ter Band. s. 187 and 528, Leipz., 1852; or Amer. edit, of Sydenham Society's edition of his Human Histology, by Dr. Da Costa, p. 523, Phi- lad., 1854. i VOL. I. — 7 98 DIGESTION. \ Fig. 43. *55' ft* -/•..: -!R The precise use of the glands of Peyer is generally considered to be unknown. Wagner' has well observed, that the intimate structure of the whole of these glandular bodies requires farther study, and is almost as little known as their individual functions. It has been conceived, that they secrete a putrescent matter from the blood, which may be concerned in giving to the excrement its peculiar odour; this matter, as in other cases, being formed by cells, which burst on the free surface of the mucous membrane, and discharge their contents to be mixed with the fteces. Such has been the view, until recently, embraced by Dr. Car- penter. Professor Brlicke,^ of Vienna, adopts a different opinion — maintain- ing, that they are always closed in their natural condition. He regards them as appendages to the lymphatic system ; as the lymphatics can be filled by injections directed from them. The contents of their areolae or cells resemble also, in appearance and character, those of the mesenteric ganglia. This view is embraced by Professors Frei, Vertical Section of two of the Peyerian Glandulse from the Ileum of the Pig, one of them closed and full, the other open and empty, with their neigh- bouring villi; magnified 15 diameters. a. Cellular contents of the vesicle; mag- nified 250 diameters. Fig. 44. Fig. 45. I A patch of Pcyer'.s Glands of the adult hu- man subject, from the lowest part of the Ileum. — After Boehm. Section of Small Intestine, containing gome of the Glands of Peyer, as shown under the microscope. These glands appear to be small lenticular ex- cavations, containing, according to Boehra, a white, milky, and rather thick fluid, with nu- merous round corpuscles of various sizes, but mostly smaller than blood globules. The meshes seen in the cut are the ordinary tripe-like folds of the mucous coat. ' Elements of Physiology, translated by R. Willis, § 137, Lond., 1842. 2 Denkrichriften der K. Akademie der Wissenachaft. Wien, 1850. 1 DIGESTIVE ORGANS — LARGE INTESTINE. 99 Kolliker/ Donders, and Gerlach,^ as well as the opinion of Professor Briicke, that they are ganglia for the elaboration of the chyle, which passes through them by the delicate chyliferous vessels, which origin- ate in the villi, on their way to the mesenteric ganglia; and Dr. Car- penter^ admits, that the results appear to prove quite conclusively, that the Peyerian glandulfe are really ap- pendages to the absorbent system, cor- responding in every respect, save their situation, to the mesenteric and lymphatic glands. The muscular coat of the small intes- tine is composed of circular and longitu- dinal fibres ; and the outer coat is formed by the prolongation of the peritoneum, which, after having surrounded the intes- tines, completes the mesentery, by which the gut floats, as it were, in the abdominal cavity. The large intestine terminates the intes- tinal canal. It is much shorter than the small, and considerably more capacious, being manifestly intended, in part, as a re- servoir. It is less loose in the abdominal cavity than the portion of the tube which we have described. It commences at the right iliac fossa (Fig. 2) ; Fig. 47. o h Side View of Intestinal Mucous Membrane of a Cat. a. A Peyer's gland, imbedded in sub- mucous tissue,/, h. A tubular follicle. c. Fossa in mucous membrane, d. Villi. e. Follicles of Lieberkiihn. Vertical Section through a patch of Peyer's Glands in the Dog. a. Villi, h. Tubes of Lieberkiihn with the apices of Peyer's glands, c. Submucous tissue with the glands of Peyer imbedded in it. d. Muscular and peritoneal coats, e. Apex of one of Peyer's glauda projecting among the tubes of Lieberkiihn. The glands are seen laid open by the section. MaguificU about 20 diameters. ' Manual of Human Microscopical Anat., Amer. edit, by Da Costa, p. 51G, note, and page 523, Philad., 1854. ^ Brit, and For. Med.-CMr. Rev., Oct., 1855, p. 527. * Op. cit. 100 DIGESTION. ascends along the riglit flank, as far as the under surface of the liver; crosses over the abdomen to gain the left flank, along which it de- scends into the left iliac region, and thence through the pelvis, along the hollow of the sacrum, to terminate at the a7ius. Like the small intestine it is divided into three portions; the ccecwn, colon, and redv.m. The ccecuni or blind gut is the part of the great intestine into which the ileum opens. It is about four fingers' breadth in length, and nearly double the diameter of the small intestine. It occupies the right iliac fossa, in which it is bound down, so as not to be able to change its position. The extremity of the ileum joins the caecum, at an angle ; and if we examine the interior of the caecum, at the point of junction, we find a valvular arrangement, which has been called valve of Tulpius, valve of Bauhm, ileo-ccecal valve, &;c. Fig, 4"J exhibits the nature of this arrangement. At the point of unioa of the two intestines, a soft eminence exists, flattened from above to below, and elliptical transversely, which is divided into two li])S. One of these seems to belong to the ileum and colon — hence called ileo-colic; the other to the ileum and crecum, and termed ileo-ccecal. From the disposition of these lips a valve results, so constituted, that the lips, which form it, separate when the feecal matters pass from the small to the large intestine; whilst they approximate, cross, and com- pletely prevent all retrogression, when the fieces tend to pass from the great intestine to the small. At the extremities of the valve are small tendons, which give it strength, and have been termed frcena or reli- nacula of the valve of Bauhin. Although this valvular arrangement prevents the ready return of the excrementitious matter into the small intestine, we have many pathological opportunities for discovering that it is not effectual in all cases. In stricture of the large intestine, stercoraceous vomiting is a frequent phenomenon, and there have been cases of substances, thrown into the rectum, having been evacuated by the mouth. At the posterior and left side of the cascum, a small process detaches itself, called, from its resemblance to a worm, ap'pendix vermifornvis ; and, from its connexion with the ccecum, appendix cceci. It is convo- luted, variable in length, and attached, by its sides, to the caecum. Its free extremity is impervious ; the other opens into the back part of the caecum. This appendage has all the characters of an intestine. Various hypotheses have been indulged regarding its uses. Some have conceived it to be a reservoir for the faeces; but its diminutive size, in the human subject, precludes this idea : others have thought, that it secretes a ferment, necessary for fascal formation ; and others, again, a mucus for preventing the induration, that might result from the deten- tion of the fieces in the caecum. The opinion — that it is a mere vestige of the useful and double casca, which exist in certain animals — is as philosophical as any. M, de Blainville,' indeed, regards it as the true CEecum; and what is named the ctecum as the commencement of the colon. It is manifestly of little importance, as it has been found wanting or obliterated in many subjects, and has been extirpated re- peatedly with impunity. The cascum is said to be wanting in all ani- ' De rOrganisation des Animaux, &c., Paris, 1S25. DIGESTIVE ORGANS — LARGE INTESTINE. 101 Muscular Coat of the Colon, as seen after the removal of the Peritoneum. 1, 1. fill res. One of its three bands of longitudinal muscular 2, 2. Circular fibres of the muscular coat. mals that hybernate. It is small in the Carnivora; very large and long in the Solidungula, Euminantia and Kodentia ; in which, — as will be seen hereafter, — there is reason to believe, that digestion of the ali- ment, which has escaped change higher up, occurs. The colon is by much the longest of the large intestines, (Fig. 2.) It is a continuation of the cascum, from which it cannot be distin- guished ; but is considered to commence at the termination of the ileum. From the right iliac fossa it ascends along the right lumbar region, over the kidney, to which it is con- nected. It is, in this part, called colon dextrum^ ascending or right lumbar colon. From the kidney it passes forwards and crosses the abdomen in the epigastric and hypochon- driac reo-ions, beinoj connected to the duodenum. This por- tion is called great arch of the colon, colon transversum. The right por- tion of the great arch is situate under the liver and gall-bladder ; and hence is found tinged yellow after death, owing to the transudation of bile. The left portion of the arch is situate under the stomach ; and, immediately below it, are the convolutions of the jejunum. In the left hypochondre, the colon turns backward under the spleen, and de- scends along the left lumbar region, anterior to the kidney, to which it is closely connected. This portion is termed colon sinistrum, descending or left lumbar colon. In the left iliac region, it forms two convolutions, which have been compared to the Greek j, or to the Roman S; and hence this part of the intestine has been designated sigmoid flexure, Ro- man S, or iliac turn of the colon. This flexure varies greatly in length in dif ferent persons, extending frequently into the hypogastric region, and, in some instances, as far as the caecum. The colon, through its whole extent, is fixed to the body by the mesocolon. The coats of the great intestine are the same in number and structure as those of the small ; but are thinner, and not as easily separable by dissec- tion. The mucous membrane is less villous and velvety. The most cha- racteristic difference, however, in their general appearance, is the pouched or Fig. 49. Longituilinal Section of the End of the Ileum, and of the Beginning of the Large Intestine. 1, 1. Portion of the ascending colon. 2, 2. C;ecuin. 3, 3. Lower portion of ileum. 4, 4. Muscular coat, covered by peritoneum. 5, 5. Areolar and mucous coats. 6, 6. Folds of mu- cous coat at this end of the colon. 7, 7. Pro- longations of areolar coat into these folds. 8, S. Ileo-colic valve. 9, 9. Union of the coats of t)ie ileum and colon. 102 DIGESTION. cellular aspect of tlie former. These pouches are reservoirs for excre- ment, and in tliem it becomes more indurated, by the absorption of the fluid portions. In torpor of this part of the intestinal canal, the f^ces are retained, at times, so long, that they form hard balls or scybala; and not unfrequently occasion the inflammation of the lining membrane of the large intestine, which constitutes dysentery. The longitudinal muscular fibres are concentrated into three ligamentous bands or fasci- culi, which run the whole length of the intestine. These being shorter than the intestine, pucker it, and are the occasion of the pouched or saccated arrangement. The inner or circular muscular fibres are, like those of the small intestine, uniformly spread over the surface, but are stronger. Lastly, on the great intestine, especially the colon, are nume- rous processes of the peritoneum containing fat, and hence called appendiculcB epi2:)loicce and appendiculce piinguedinosce. These are seen in greatest abundance on the right and left lumbar portions of the colon. The rectum terminates the intestinal canal, and extends from the end of the colon to the anus. It commences about the fifth lumbar ver- tebra, and descends vertically into the pelvis, following the concavities of the sacrum and coccyx ; and, consequently, is not straight, as its name would import. At its upper part, there are a few appendiculas epiploicas; and a small duplicature of the mesentery, called mesorectimi, attaches it to the sacrum. It differs from the other intestines in be- coming wider in its progress downwards, and in its parietes being thicker. The lower part of the mucous membrane exhibits several longitudinal folds or rugae, called " columns," which have been con- sidered as the effect of the contraction of the circular fibres of the muscular coat. At the lower ends of the wrinkles between the columns are small pouches, from two to four lines in depth, the orifices of which point upwards. They are occasionally the seat of disease, and, when enlarged, give rise to painful itching. The nature of this affection was first pointed out by Dr. Physick, and the remedy consists in slitting them open. The longitudinal fibres of the muscular coat have a dif- ferent^ arrangement from that which exists in the other portions of the large intestine. They are distributed over the whole surface, as in the small intestine, — or rather, as in the oesophagus. At the anus, an arrangement of the muscular coat prevails, which has been pointed out by Professor Horner.^ The longitudinal fibres, having reached the lower margin of the internal sphincter, turn under this margin between it and the external sphincter, and then ascend upwards for an inch or two in contact with the mucous coat, into which they are finally inserted by fasciculi, which form the base of the columns of the rectum : many of the fibres, however, terminate also between the fasciculi of the circular fibres. The circular fibres are more and more marked, as they approach the outlet, and, by circumscribing the margin of the anus, they form the sphincter ani muscle. Immediately within the anus is the widest portion of the rectum ; and, in this, accumulations of indu- rated fieces sometimes take place in old people to a surprising extent, owing to the torpor of the muscular powers concerned in the expul- ' General Anatomy and Histology, Sth edit., it. 46, Philada., 1S51. DIGESTIVE ORGANS. 103 sion of the feeces. The mucous coat of the rectum is thick and red, and abounds in follicles. Lastly ; there are a few muscles, which are concerned in the act of expelling the fceces. These require a short notice. 1. The siiihincter ani, coccygeo-anal muscle, which keeps the anus constantly closed, ex- cept during defecation. 2. The levator am", snhptibio-coccygeus, which, with the next muscle, constitutes the floor of the pelvic and abdominal cavities. It restores the anus to its place, when pushed outwards during defecation. 3. The coccygeus^ ischio-coccygeus^ which assists the levator ani in supporting or raising the lower extremity of the rec- tum; and 4. The transversus pennei, iscMo-jperineal muscle, some fibres of which unite both with the bulbo-cavernosi and with the sphincter ani muscles; and, consequently, it is asso- ciated slightly with the action of both one and the other. In regard to the intestinal canal, we find, that man holds a medium place between the carnivorous and herbivorous animal, although approximat- ing more to the latter. In the carnivorous — for reasons hereafter mentioned — it is un- necessary that the food should remain long ; accordingly, the canal is very short. In the herbivora, on the other hand, and for opposite reasons, the canal is long, and there is generally a large caecum and a pouched colon. Cuvier' has given tables of the length of the digestive tube, compared with that of the body; but Fig. 50. View of External Parietes of Abdomen, with the po- sition of the Lines drawn to mark off its Regions. 1, 1. Line drawn from the highest point of one ilium to ^ , the same point of the opposite one. 2, 2. Line drawn from wl-)p-pp tVip pnmnn-rn<5nn 1ti« Vipph '''® anterior superior spinous process to the cartilages of Wiiei e tne comparison naS Oeen the ribs. 3, 3. a similar one for the oppo.site side. 4, 4. applied to man, the length of ^'"® drawn perpendicularly to these, and touching the ,r: 1 1 1 • 1 1 1 ,r , n ii>ost prominent part of the costal cartilages, thus forminir tne body naS inCiudea that 01 nine regions. 5, 5. Right and left hypochondriac regions. th. ipc.« Tn«fp«^ fL...w lJtsri^^^:^.L''i^,:!&^^^^ Eight and left iliac regions. 11. The lower part of the hypogastric, sometimes called pubic. the legs. Instead, therefore, of the canal, in him, being con- sidered to bear the proportion of six to pne, it ought to be doubled, or be regarded as twelve to one; a proportion somewhat greater than prevails in the simias or ape tribe'. It is not, however, always in length, that the canal of the herbivorous exceeds that of the omnivorous animal ; but as a general rule, it may be aifirmed, that its capacity is much more considerable. Lejons d'Anatomie Comparee, Paris, 1799. 104 DIGESTIO:^. 5. The aldomen, in wliicL the principal digestive organs are situate, and whose parietes exert considerable influence on the digestive func- tion, requires a brief description. It is the division of the body, which is betwixt the thorax and pelvis ; is bounded, above, by the arch of the diaphragm ; behind, by the vertebral column ; laterally, and ante- riorly, by the abdominal muscles; and, below, by the ossa ilii, os pubis, and the cavity of the pelvis. To connect the knowledge of the internal parts of the abdomen with the external, it is customary to mark certain arbitrary divisions on the surface, called regio-iis. (Fig. 50.) The epirjasiric region is at the upper portion of the abdomen, under the point of the sternum, and in the angle formed by the cartilages of the ribs. The hypochondria/^ regions are covered by the cartilages of the ribs. These three regions — the epigastric, and right and left hypochondre — constitute the upper divi- sion of the abdomen, in which are seated the stomach, liver, spleen, pancreas, duodenum, and part of the arch of the colon. The space sur- rounding the umbilicus, between the epigastric region and a line drawn from the crest of one os ilii to the other, is the umbilical region. Here the small intestines are chiefly situate. This region is bounded by lines, raised perpendicularly to the spine of the ilium; and the lateral por- tions on the outside of these lines, form the iliax^ regions^ behind which, again, are the lumbar regions or loins. In these, the colon and kidneys are chiefly situate. The hypogastric is, likewise, divided into three regions, — the puhic in the middle, in which is the bladder ; and an inguinal on each side. The muscles that constitute the abdominal parietes, are, — first of all, aZ/ore, the diaphragm, which is the boundary between the thorax and abdomen, convex towards the chest, and considerably concave towards the abdominal cavity. Below, if we add the pelvic cavity, — which, as it contains the rectum, and muscles concerned in the evacuation of the faeces, it may be proper to do, — the cavity is bounded by the perineum, formed chiefly of the levatores ani and coccygei muscles. Behind, la- terally, and anteriorly, from the lumbar vertebrge round to the umbilicus, the parietes consist of planes of muscles, and aponeuroses in super- position, united at the median line, by a solid, aponeurotic band, extend- ing from the cartilago ensiformis of the sternum to the pubes, called linea alba. The abdominal muscles, properly so called, are, — reckoning tlie planes from within to without, — the greater ob'lvpie nmscle, lesstr oblique, and trausversalis, which are situate chiefly at the sides of the abdomen ; and the rectus and ^-^yramidalis, which occupy the anterior part. The greater oblique, obliquus externum, costo-abdominalis ; leaser oblique, obliquus internum, ilio-abdominalis ; and trausversalis, transversus abdominis, lumho-abdominalis, support and compress the abdominal viscera : assist in the evacuation of the fasces and urine, and in the expulsion of the fcetus; besides other uses, connected with respiration and the attitudes. The rectus, puhio-sternalis or sterno-puhialis ; and the pyramidalis or piuhio subumbilicalis, are more limited in their ac- tion, and compress the forepart of the abdomen; besides having other functions. Lastly, a serous membrane — the peri/oneum — lines the alxlomen, and gives a coat to most of the viscera. The mode, in which its vaiious DIGESTIVE ORGANS — PERITONEUM. 105 reflections are made, is singular, but easil)^ intelligible from the accom- panying figure (Fig. 51). It has neither beginning nor end, constitut- Fiff. 51. 1. Section of tlip spinal column and canal. 2. Section of the sacrum. 3. Section of the ster- num, &c. 4. Umbilicus. 5. A section of the llnea alba and abdominal muscles. 6. Mons veneris. 7. Section of the pubis. 8. Peni.s divided at the corpora cavernosa. 9. Section of the scrotum. 10. Superior right half of the dia- phragm. 11. Section of the liver. 12. Section of the stomach, showing its cavity. 13. Section of the transverse colon. 1-t. Section of the pan- creas. 15. Section of the bladder, deprived of the peritoneum. 16. Rectum cut olf, tied and turned back on the promontory of the sacrum. 17. Peritoneum covering the anterior parietes of the abdomen. IS. Peritoneum on the inferior under side of the diaphragm. 19. Peritoneum on the convex side of the diaphragm. 20. Ee- flection of peritoneum from diaphragm to liver. 21. Peritoneum on front of liver. 22. The same, on its under surface. 23. Hepato-gastric omen- tum. 21. A largo pin passed through the fora- men of Winslow into the cavity behind the omentum. 25. Anterior face of the hepato-gas- tric omentum, passing in front of the stomach. 26. The same membrane leaving the stomach to make the anterior of the four layers of the great omentum. 27, 28. Junction of the peritoneum from the front and back part of the stomach, as they turn to go up to the colon. 29. Gastro-colic, or greater omentum. 30. Separation of its layers, 80 as to cover the colon. 31. Posterior layer passing over the jejunum. 32. Peritoneum in front of the riglit kidney. 33. Jejunum cut olf and tied. 34, 31. Me.seutery cut otf from tlie email intestines. 35. Peritoneum reflected from the posterior paries of the bladder to the anterior of the rectum. 36. Cul-de-sac between the blad- der and the rectum. Reflections of the Peritoneum, a? shown in a Ver- tical Section of the Body. ing, like all serous membranes, a shut sac ; and, in reality, having no viscus within it. If we assume the diaphragm as the part at which it commences, we find it continued from the surface of that muscle over the abdominal muscles, 5 ; then reflected, as exhibited by the curved line, over the bladder, 15; and, in the female, over the uterus; thence over the rectum, 16; the kidney, enveloping the intestine, 13, and constituting, by its two laminas, the mesentery, 34; giving a coat to the liver, 11 ; and receiving the stomach, 12, between its duplicatures. The use of this membrane is to fix and support the different viscera; to constitute, for each, a pedicle, along which the vessels and nerves may reach the intestine ; and to secrete a fluid, which enables them to move readily upon each other. When we speak of the cavity of the peritoneum, we mean the inside of the sac; and when it is distended with fluid, as in ascites, the fluid is contained between the peritoneum lining the abdominal muscles, and that which forms the outer coat of the intestines. The omenta or epipha are fatty membranes, which hang over the face of the bowels; and are reflections, formed by the perito- neum after it has covered the stomach and intestines. Their names sufficiently indicate their position: — the lesser epiploon or omentum^ — the omeidum hepato-gastricum ; the greater or gastro-colic; and the appen- 106 DIGESTION". dices or appendladce epiploicce; wliicli last have already been referred to, and may be regarded as so many small epiploons. Tbe abdomen is entirely filled by tbe contained viscera. There are several apertures in it; three, above, in the diaphragm, for the passage of the oesophagus, vena cava inferior, and aorta ; one anteriorly in the course of the Tinea alba, which is closed after birth, — the umbilicus; and two anteriorly and inferiorly; the one — the abdominal^ inguinal; or sup-a-imhian ring — which gives passage to the vessels, nerves, &c., of the testicle ; and the other — the crural arch — through which the ves- sels and nerves pass to the lower extremity. Lastly, two others exist in the inferior paries, for the passage of the obturator vessels and nerves, and sciatic vessels and nerves, respectively. Such is a brief view of the various organs concerned in digestion. To this might have been added the general anatomy of the liver and pancreas, — each of which furnishes a fluid, that is a material agent in the digestive process, — and of the spleen, which has been looked upon by many as inservient, in some manner, to the same function. As, however, the physiology of tliese organs will be considered in another place, we defer their anatomy for the present. 2. FOOD OF MAN. The articles, inservient to the nourishment of man, have usually been considered to belong entirely to the animal and vegetable king- doms; but there seems to be no suf&cient reason for excluding those articles of the mineral kingdom that are necessary for the due consti- tution of the different parts of the body. Generally, the term food or aliment is applied to substances, which, when received into the digestive organs, are capable of being converted into chjde; but, from this class again, the products of the mineral kingdom — as chloride of sodium, phos- phorus, sulphur, and lime, either in combination or separately — cannot, with entire propriety, be excluded. There are numerous tribes who feed at particular seasons more especially on mineral substances. Kessler affirms, that the quarriers on the Kyffhauser, in northern Thuringia, spread a Steinbutter — "rock butter," on bread, which they eat with appetite; and Von Humboldt relates, among many other instances, that of the Ottomacs, who, during the periodical rise of the Orinoco and Meta, when the taking of fish ceases — a period of two or three mouths' duration — swallow great quantities of earth. They found piles of clay- balls in pyramidal heaps in the huts, and Humboldt was informed, that an Ottomac would eat from three-quarters of a pound to a pound and a quarter in a day. Some of this earth was analyzed by M. Vauquelin, and found to contain no organic matter. It would appear, that the practice of eating earth exists in many parts of the torrid zone, among indolent nations, who inhabit the finest and most fertile regions of the globe. But it is not confined to them ; for the same writer affirms, that in the north, by information communicated by Berzelius and Retzius, hundreds of cartloads of earth containing infusoria are annually con- sumed by the country people in the most remote parts of Sweden as bread meal, and even more as a luxury — like tobacco — than as a neces- sary. In Finland, the earth is occasionally mixed with the bread. It consists of empty shells of animalcules, so small and soft as not to FOOD OF MAN. 107 crancli perceptibly between the teeth, filling the stomach, but affording no real nutriment. Many similar cases are recorded by Humboldt.^ Animals are often characterized by the kind of food on which they subsist. The carnivoroiLs feed on flesh ; the piscivorous on fish ; the insectivorous on insects; the phytivorous on vegetables; the granivorous on seeds; the fnigivorous on fruits; the graminivorous and herbivorous on grasses; and the omnivorous on the products of both the animal and the vegetable kingdom. In antiquity, we find whole tribes designated according to the aliment they chiefly used. Thus, there were the >ZEthiopian and Asiatic ichthyoplicuji or fish-eaters; the hylopjJiagi^ who fed on the young shoots of trees; the elephantophagi^ and struthiophagi, elephant and ostrich-eaters, &c. &c. We have already shown, that the digestive apparatus of man is inter- mediate between that of the carnivorous and the herbivorous animal; that it partakes of both, and that man may, consequently, be regarded omnivorous ; that is, capable of subsisting on both the products of the animal and the vegetable kingdom ; — an important capability, seeing, that he is destined to live in arctic regions, in which vegetable food is not to be met with, as well as in the torrid zone, which is more favour- able for vegetable than animal life. The nature of the country must, to a great extent, regulate the food of its inhabitants; for although commerce can furnish articles of luxury, and many which are looked upon as necessaries, no nation is entirely indebted to it for its supplies. Besides, numerous extensive tribes of the human family are denied the advantages of commerce, and com- pelled to subsist on their own resources. This is the main cause why the Esquimaux, Samoiedes, &c., live wholly on animal food; and why the cocoa-nut, plantain, banana, sago, yam, cassava, maize and millet, form chief articles of diet with the natives of torrid regions. In certam countries, the scanty supply of the useful and edible ani- mals has given occasion to certain prohibitory dietetic rules and regu- lations, which have been made to form part of the religious creed, and, of course, are most scrupulously observed. Thus, in Ilindostan, animal food is not permitted to be eaten ; but the milk of the cow is excepted. Accordingly, to insure the necessary supply of this fluid, the cow is made sacred ; and its destruction a crime against religion. Amongst the laws of the Egyptians are similar edicts, but they seem to have been chiefly enacted for political purposes, and not in consequence of the unwholesome character of the interdicted articles. The same remark applies to many of the dietetic rules of Moses, for the regula- tion of the tables of the Hebrews. Blood was forbidden, in conse- quence, probably, of the fear entertained, that it might render the people too familiar with that fluid, and diminish the horror inculcated against shedding it; the parts of generation were excluded from the table, because the taste, if indulged, might interfere with the repro- duction of the species, &c. &c. We have said, that, in his arrangement of the digestive organs, man is intermediate between the carnivorous and the herbivorous animal. ' Ansicliten der Natur; translated under the title of Aspects of Nature, by Mrs. Sabine, Amer, edit., p. 159, Philadelphia, 1849. 108 DIGESTION". Not tlie sli.ojlitest ground is afforded by anatomy for the opinion of Rousseau, tiiat man was originally herbivorous; or for that of Hel- vetius,' that he was exclasively carnivorous. Broussonet affirms, that lie is more herbivorous than carnivorous, since, of his thirty-two teeth, twenty resemble those of the herbivorous, whilst twelve only resemble those of the carnivorous animal. Accordingly, he infers, that, in the origin of society, the diet of man must have been exclusively vege- table. Mr. Lawrence,^ too, concludes, that, whether we consider the teeth and jaws, or the immediate instruments of digestion, the human structure closely resembles that of the simiae — the great archetypes, according to Lord Monboddo-' and Rousseau, of the human race, — all of which are, in their natural state, herbivorous. Again: — a wide discrepancy between man and animals is observed in the variety of their aliments. Whilst the latter are generally re- stricted to either the animal or vegetable kingdom, and to but a small part of either, man embraces an extensive range, and by means of his culinary inventions can convert a variety of articles from both king- doms into materials of sustenance. But it has been argued by those, who are sticklers for the natural^ that man probably confined himself, primitively, like animals, to one kind of food; that he adhered to this whilst he remained in his natural state, and that his omnivorous prac- tices are a proof of his degeneracy. Independently, however, of all arguments deduced from organization, experience sufficiently shows the inaccuracy of such assertions. If we trace back nations to their state of infancy, we find, that then, as in their more advanced condition, their diet was animal, or vegetable, or both, according to circumstances. Of this fact we have some signal examples in a part of the globe where the lights of civilization have penetrated to a less extent than in most others; and where the influence of circumstances that prevailed in ancient periods has continued, almost unmodified, until the present time. Agatharchides'' describes the rude tribes, who lived on the coast of the Red Sea, and subsisted on fish, under the name ichthyophagi. Along both banks of the Astaboras, which flows on one side of Meroe, dwelt another nation, who lived on roots of reeds growing in the neigh- bouring swamps. These roots they cut to pieces with stones, formed them into a tenacious mass, and dried them in the sun. Close to them were the hylophagi, who lived on the fruits of trees, vegetables growing in the valleys, &c. To the west of these were hunting nations, who fed on wild animals, which they killed with the arrow. There were, also, other tribes, who lived on the flesh of the elephant and ostrich, — elephaatophagi and struthiophagi. Besides these, he mentions another and less populous tribe, who fed on locusts, which came in swarms from the southern and unknown districts. The mode of life, with the tribes described by Agatharchides, does not seem to have varied for the last two thousand years. Although cultivated nations are situated around them, they have made no progress themselves. Hylophagi are still to be met with. The Dobenahs, the most powerful tribe amongst ■ De rHomme, ii. 23, Londres, 1775. * Lectures on Physiology, Zoology, &c., p. 221, London, 1819. * On tlie Origin and Progress of Language, Pt. i. Book 2, Chap. 2, Edinburgh, 1773. * De Rubro Mare, in Hudson's Geograph. Minor., i. 37. FOOD OF MAN. 109 the Sliangallas, still live on the elephant ; and, farther to the west, dwells a tribe, which subsists in the summer on the locust; and, at other seasons, on the crocodile, hippopotamus, and fish.' In the infancy of society, as in his own infancy, man was perhaps almost wholly carnivorous; as the tribes least advanced in civilization are at the present day. For a time, he may, in most situations, have confined himself to the vegetable banquet prepared for him by his bounteous Maker ; but, as population increased, the means of subsist- ence would become too scattered for him, and it would be necessary to crowd together a number of nutritious vegetables into a small space, and to cultivate the earth, so as to multiply its produce; but this would imply the existence of settled habits and institutions which could only arise after society had made progress. Probably, much before this period, it would have been discovered, that certain of the beasts of the forest, and of the birds of the air, and some of the insect tribes, could minister to his wants, and form agreeable and nutritious articles of diet; and thus would arise their adoption as food. On the coasts of the ocean, animal food was perhaps employed from the period of their first settlement; as well as on the banks of the large streams which are so common in Asia, — the cradle of mankind. The fish, left upon the land after the periodical inundations of the rivers, or thrown on the sea-coast, would minister to their necessities, without the slightest eftbrt on their part ; and, hence, they would have but little incentive to mental or corporeal exertion. This is the cause of the abject con- dition of the ichthyophagous tribes of old; and of their comparatively low state of civilization at the present day.^ Again: — savages, in various parts of the globe, live by the chase or the fishery ; and must, consequently, be regarded as essentially carnivorous. It would not, however, be justifiable, to regard barbarism as the natural state of man; nor is it clear what the difi'erent writers on this point of anthro- pology have meant by the term. The Author of nature has invested him with certain prerogatives, one of which is the capability of ren- derinfj: the organized kino-dom subservient to his wishes and necessi- ties; and, by the invention of the culinary art, of converting various organized bodies into wholesome and agreeable articles of diet, which thus become as natural to him as the restriction to one species of aliment is to the animal. It has been remarked, that the exclusive or predominant use of ani- mal or of vegetable food has a manifest effect upon the physical and moral powers. Bufibn affirms, that if man were obliged to abstain from flesh in our climates, he could not exist, nor propagate his kind. Others, again, have depicted a state of ideal innocence, in the infancy of society, when he lived, as they conceive, entirely on vegetables; " His food the fruits ; liis drink the crystal well ;" unsolicitous for the future in consequence of the abundant subsistence spread before him; independent; and always at peace with his fellows, and with animals; but he gradually sacrificed his liberty to the bonds ' Bruce, Travels, 3d edit., v. 83. 2 The Author, in Amer. Med. Intelligencer, i. 99, Philad., 1838. 110 DIGESTION. of society; and cruelty, TN'ith an insatiable appetite for flesli and blood, were the first fruits of a depraved nature. Either immediately or remotely, all the physical and moral evil, by which mankind are afflicted, arose from these carnivorous practices. "The principal patrons of this twaddle, in modern times" — says Dr. Fletcher — " to say nothing of Pvthagoras and the ancients — have been Gassendi, Kousseau, AYallis, Lamb, and jSTewton ; the last of whom, in the pleni- tude of his infatuation, asserts that real men have never yet been seen, nor ever will be, till they shall be content to subsist entirely on herbs and fruits and distilled water."^ In point of fact, we find, that the inhabitants of countries, in which mankind are accustomed to be om- nivorous, or to unite animal witli vegetable diet, are those most dis- tinguished for both mental and corporeal endowments. The tribes, which feed altogether on animal food, — as the Laplanders, Samoiedes, Esquimaux, &c., — are far inferior, in both these respects, to the Euro- pean, or Europeo- American ; and the same may be said, although not to the like extent, of the various tribes in whose diet animal food pre- dominates, — as the Indian inhabitants of our own continent. A similar remark is applicable to those, who live almost exclusively on vegeta- bles, as the Hindoos, millions of whom are kept in subjection by a few Europeans.^ Attempts have frequently been made to refer the nutrient properties of all articles of diet to a particular principle of a constant character, which, alone, of all the elements, is entirely capable of assimilation. Haller^ conceived this to be jelly; — Dr. Cullen'' thought it to be oily, or saccharine, or what seemed to be a combination of the two; — Becker, Stah], Fordyce,* &c., to be mucilage; M. Dumas,^ mucus; and M. Halle, a hydro-carbonous oxide very analogous to gummi-saccharine matter V It is probable, that there is no such special principle as the one contended for ; and that, in all cases, in the formation of the chyle or reparative fluid, which is separated from it, the food is resolved into its elements. To this conclusion w*s are necessarily impelled, when we reflect, that chyle can be formed from both animal and vege- table substances. In an early part of this work, occasion was taken to mention, that all organized tissues, animal and vegetable, are reducible into nearl}'- the same ultimate elements, — oxygen, hydrogen, carbon, and nitrogen. Great light has been thrown on this subject, in recent periods, by the labours of the organic chemist. These have shown, that the chief proximate principles of animal tissues, and those that have been regarded as highly nutritious amongst vegetables, have almost identically the same composition; and are modifications of protein.^ The following tables from Liebig'* exhibit the striking ' Riirliments of Physiology, Part ii., a. p. 121, Edinb., 1S36. 2 Lawrence's Lectures, edit, cit., p. 216. '^ Elementa Phyrfiologise, Lib. xix., Sect. 3, Bernje, 1764. * Institutions of Medicine, Part i., Physiology, § 211, Edinb., 1785. ^ Treatise on the Digestion of Food, p. 84, 2d edit., Lond., 1791. ^ Principes de Physiologic, i. 187, Paris, 1806. ' Tiedemann, Pliysiologie des Menschen, iii. 95, Darmstadt, 1836. ^ See page 39. 9 Animal Chemistry, Gregory's and Webster's edit., pp. 100, 283, and 301, Cambridge, Mass., 1842. FOOD OF MAN. Ill similarity in constitution, and in the proportion of constituents, of different animal and vegetable compounds of organization. Animal proximate principles, according to Mulder, Albumen. Fibrin. Casein. Carbon, 54-84 54-56 54-96 Hj^drogen, . 7-09 6-90 7-15 Nitrogen, 15-&3 15-72 15-80 Oxygen, 21-23 22-13 21-73 Sulphur, 0-OS 0-33 0-36 Phosphorus, 0-33 0-36 100-00 100-00 100-00 Carbon, Hydrogen, Nitrogen, Oxygen, Sulphur, Phosphorus Vegetable proximate principles, according to ScJierer and Jones. Albumeu, from wheat. Fibrin. Casein or Legumin. 55-01 ! . 54-603 . . 54-138 7-23 . . 7-302 . . 7-156 15-92 . . 15-809 . . 15-672 21-84 100-00 22-286 100-000 23-034 100-000 As tlie different parts of organized bodies contain a considerable portion of nitrogen, a question has arisen regarding its source ; some believing, that it is obtained from the food, others by respiration. ]\L Magendie' instituted experiments with the view of determining the nutritive qualities of non-nitrogenized substances. They consisted in feeding animals, for the necessary time, on a diet whose chemical composition was rigidly determined. He fed a dog, three years old and in good condition, on pure white sugar and distilled water. For seven or eight days, the animal appeared to thrive well, was lively, and ate and drank with avidity. In the second week, it began to fall off, although its appetite continued good, and it ate six or eight ounces of sugar in the twenty -four hours. In the third week, it became ema- ciated, its strength diminished, its gaiety was gone, and its appetite impaired. An ulcer formed on each eye, at the centre of the cornea, which subsequently perforated it, and allowed the humours to escape. The emaciation, as well as loss of strength, went on progressively increasing; and, although the animal ate daily three or four ounces of sugar, the debility became so great, that it could neither chew, swal- low, nor execute the slightest movement. It died on the thirty-second day of the experiment. On dissection, the fat was found to have entirely disappeared ; the muscles were reduced to less than five-sixths of their ordinary size; the stomach and intestines were much dimi- nished, and powerfully contracted ; and the gall and urinary bladders filled with fluids not proper to them. These were examined by M. Chevreul, who found them to possess almost all the characters of the bile and urine of herbivorous animals. The urine, in place of being acid, as it is in the caruivora, was sensibly alkaline, and presented no trace of uric acid or phosphates. The bile contained a considerable proportion of picromel, like that of the ox and herbivora in general. ' Precis i-lementaire, 2de edit., ii. 4SS, Paris, 1825. 112 DIGESTION. The excrements contained very little nitrogen, wliicli tliej usually do in abundance, A second dog was subjected to the like regimen, and with similar results. He died on the thirty -fourth day of the experiment. A third experiment, having eventuated in the same manner, j\[. Magendie con- cluded that sugar alone is incapable of nourishing the dog. In all these cases, ulceration of the cornea occurred, but not exactly at the same period of the experiment. He next endeavoured to discover, whether these effects might not be peculiar to sugar ; or whether non- nitrogenized substances, generally considered nutritions, might not act in the same manner. He took two young and vigorous dogs, and fed them on olive oil and distilled water. For fifteen days they were appa* rently well ; but, after this, the same train of phenomena supervened as in the other cases, except that there was no ulceration of the cornea. They died about the thirty-sixth day of the experiment. Similar experiments were made with gum Arabic, and with butter — one of the animal substances that do not contain nitrogen. The results were identical. Although the character of the excrements passed by the difl'erent animals indicated that the substances were well digested, M. Magendie was desirous of establishing this in a positive manner. Accordingly, after having fed animals for several days on oil, gum, or sugar, he opened them, and found that each of these substances was reduced to a particular kind of chyme in the stomach ; and that all aflbrded an abundant supply of chyle ; that from oil being of a manifest milky appearance, and that from gum or sugar, transparent, opaline, and more aqueous than the chyle from oil ; facts which prove, that if the various substances did not nourish the animals, the circumstance could not be attributed to their not having been digested. These results, M. Ma- gendie thought, render it likely, that the nitrogen, found in different parts of the animal economy, is originally obtained from the food. This, however, is doubtful. We have no proof, that the animals died simply from privation of nitrogen. It is, indeed, probable, that it had little or no agency in the matter, for there seems to be no sufficient reason why it should not have been procured from the air in respira- tion, as well as from that contained between the particles of the sugar, where this substance was administered. It must be recollected, more- over, that the subjects of these experiments were dogs; — animals which, in their natural state, are carnivorous, and, in a domestic state, omnivorous ; and that they were restricted to a diet foreign to their nature, and one to which they had not been accustomed. Ought we, under such circumstances, to be surprised, that they should sicken, and fall oft"? In the period that elapsed between the publication of the first and second editions of his Precis Eltmentaire de Fhi/siologie, M. Magendie found that his deductions were not, perhaps, as absolute or demonstra- tive as he had at first imagined; and additional experiments induced him to conclude,— as Dr. Bostock^ afterwards did, without being aware, apparently, of his observation,— "that variety and multiplicity of ' riiysiology, 3d edit., p. 561, Lond., 1S36. FOOD OF MAN. 113 articles of food constitute an important hygienic rule." " This," M, Magendie' adds, " is indicated to us by our instinct, as well as by the changes that wait upon the seasons, as regards the nature and kind of alimentary substances." The additional facts, detailed by M. Magendie, are the following : — A dog, fed at discretion on pure wheaten bread, and drinking common water, does not live beyond fifty days ; whilst another, fed exclusively on military bread — pain de munition — seems to suffer in no respect. Eabbits or Guinea-pigs, fed on a single sub- stance, as wheat, oats, barley, cabbage, carrots, &c., commonly die, with every mark of inanition, in a fortnight; and, at times, much earlier. "When the same substances are given together, or in succession, at short intervals, the animals continue in good keeping. An ass, fed on rice, lived only fifteen days, refusing his food for the last few days ; whilst a cock was fed upon boiled rice for several months without his health suffering. Dogs, fed exclusively on cheese, and others on hard eggs, lived for a long time ; but they were feeble and lean, losing their hair, and their whole appearance indicated imperfect nutrition. The sub- stance, which, when given alone, appeared to support the rodentia^ for the greatest length of time, was muscular flesh. Lastly, M. Magendie found, that if an animal had subsisted for a certain time on a substance, which, taken alone, is incapable of nour- ishing it, — on white bread, for instance, for forty days, — it is useless, at the end of that time, to vary his nourishment, and restore him to his accustomed regimen. He will feed greedily on the new food pre- sented to him; but continues to fall off"; and dies at the same period as he would probably have done, if maintained on his exclusive regimen. That these effects are not owing to privation of nitrogen, the same ob- server' has since been amply satisfied. As chairman of a committee appointed to inquire into the nutritive properties of gelatin, he re- ported that gelatin, albumen, and fibrin — all of which are highly nitrogenized — when taken separately, nourish animals for a limited period only, and imperfectly. They generallj^ soon excite so insur- mountable a disgust that the animals would rather die than partake of them. These experiments led to the too hasty conclusion, that the gelatinous tissues are incapable of conversion into blood. " The gela- tinous substance," says Liebig,"* " is not a compound of protein ; it has no sulphur, no phosphorus, and contains more nitrogen or less carbon than protein. The compounds of protein, under the influence of the vital energy of the organs that form the blood, assume a new form, but are not altered in composition ; whilst these organs, as far as our experience reaches, do not possess the power of producing compounds of protein, by virtue of any influence, from substances that contain no protein. Animals, which were fed exclusively on gelatin, the most ' Op. citat., ii. 494. ^ The rodentia are gnawing animals, having large incisors in each jaw, with which they divide hard substances. They are the rongeurs of the French naturalists. The squirrel, mouse, rat, Guinea-pig, hare, rabbit, beaver, kangaroo, porcupine, &c., belong to this division, ' Comptes Rendus, Aout, 1841. Similar results were obtained by the Amsterdam Commission, Het Instituut, No. ii. 1843, pp. 97-114, cited by Mr. Paget, Brit, and For. Med. Rev., April, 1845, p. 563. ■* Animal Chemistry, Amer. edit., by Webster, p. 124, Cambridge, Mass., 1842. VOL. I. — b 114 DIGESTION". highly nitrogenized element of the food of carnivora, died with symp- toms of starvation." " In short," he adds, " gelatinous tissues are in- capable of conversion into blood." Such too, seems to be the opinion of Professor Berard.^ Yet it has been shown above, that fibrin and albumen — both compounds of protein — when exhibited singly to ani-' mals, nourished them as imperfectly as gelatin ; and there is some reason to believe, that it is mainly on chemical considerations that the value of gelatin as a nutriment has been much underrated. " Such persons only," says Professor Mulder,^ "as are under the influence of prejudice (making their experiments with dogs — animals which, ac- cording to the account of the gelatin committee, prefer to starve in the midst of gelatin, rather than touch it), such persons only as deny the results of innumerable observations, will refuse to gelatin its place among useful nutritive substances." And he adds : " I have thought it necessary, before closing this short account of gelatin, to express my opinion of the experiments by which pure gelatin is rejected as food: — namely, that these experiments have taught ine nothing but how ex- periments ought not to be made." It is somewhat singular, too, that most of those who deny much nutrient property to gelatin are of opinion, that the nutritious properties of different articles of vegetable food may be generally estimated by the proportion of nitrogen they contain, and on this principle tables have been formed by several ex- perienced chemists, — by Boussingault, Schlossberger, Kemp,^ and Professor Horsford,'' of Cambridge, Massachusetts. The latter gentle- man, especially, has published the results of elaborate investigations into the nature of different kinds of vegetable food, based upon the amount of nitrogen. The tables of Boussingault and Horsford are considered by Professor Frerichs,^ of value ; whilst those of Schloss- berger and Kemp are declared to be practically useless, because no regard was paid to the quantity of water in the fresh condition ; and for the strange reason, "that the nitrogen found in most of the sub- stances analyzed that contain gelatin is no measure of the quantity of the htematogenetics or blood-forming constituents !" Independently of showing the necessity of variety of food for animal sustenance, the experiments of M. Magendie exhibit some singular anomalies ; and sufficiently demonstrate, that we have j%i much to learn on the subject. A great deal, doubtless, depends on the habits of the particular animal or individual ; and on the morbid effects excited by completely changing the function of assimilation. It has been long known, that if a man, previously habituated to both animal and vege- table diet, be restricted exclusively to one or the other, he will fall off, and become scorbutic ; and yet, that he is capable of subsisting on either one or the other exclusively, provided the restriction has been enforced from early infancy, has been sufficiently shown by the refer- ' Archives Genemles de Medecine, Fevrier, 1850, p. 247. 2 The Chemistry of Vegetable and Animal Physiology, by G. J. Mulder, &c., p. 328, Edinb. and Lend., 1849. J bj , j , ,i > 3 Annal. der Chemie und Pharmacie, B. Ivi. s. 78-94 ; see also, Philosophical Maga- zine for Nov., 1845. * Philosophical Magazine, for Nov., 1846, p. 365. 5 Art. Verdauung, in Wagner's Handwurterbuch der Physiologic, 19te Liefening, s. 732, Braunschweig, 1848. FOOD OF MAN. 115 ence made to carnivorous and herbivorous tribes existing in different regions of our globe. Tlie importance of variety of diet is illustrated by the experiments made by Dr. Stark/ upon his own digestive powei^s, and to which he ultimately became a martyr. His object was to dis- cover the relative effect of various simple substances, when used exclu- sively for a long space of time as articles of food. The system, he found, was in all cases reduced to a state of extreme debility, and there was not a single aliment, that was capable, of itself, of sustaining the vigour of the body for any considei'able period. By this kind of regi- men Dr. Stark is said to have so completely ruined his own health, as to bring on premature death. It would seem, too, that for continued sustenance, a due supply of vegetable food, which is not deprived of its organic acids and salts, must be permitted ; hence the production of scurvy by the want of fresh vegetables, and its removal by a proper admixture of the same, which must either be eaten raAV, or so cooked that they may not be de- prived of their saline constituents.^ Occasionally, too, where scurvy has arisen under the exclusive use of animal diet, it has disappeared Avhen a fresh article of nitrogenized diet has been obtained. Thus, his friend Dr. Kane, of the United States Navy, informed the author that during the first expedition to the Arctic regions in search of Sir John Frank- lin, when the sailors were suffering with scorbutus, and the lesser awlz visited the region in its periodical migration, the fresh, uncooked flesh of the bird soon dispelled every symptom of the malady. In accordance with his views, that nitrogenized food is alone capable of formiog organized tissue; and that the non -nitrogenized food is inservient to respiration only, Liebig thus classifies aliments: — Nitror/enized Food or Plastic Elements of Non-nitrogenized Food or Elements of Nutrition. Respiration. Vegetable Fibrin, " Albumen, " Ccaseiu, Flesh, Blood. These views, however, are more chemical than physiological, and cer- tainly have always been considered by the author to demand proof which has not been sufficiently afforded. They are not confirmed by what is observed in chylification. In the small chyliferous vessels, more fat, which is a non-nitrogenized substance, is found than can be accounted for by the adipose matter in the food ; and of the conver- sion of the amylaceous and saccharine matters in the food to oil during the digestive function a striking example has been published by M. Ivciss.^ A workman was killed on a railroad after having eaten a full meal of bread and grapes only. On examining his body, the process of chymification was found to have been in full activity; and in those portions of the small intestine, which the chyme had reached, the mucous membrane was dotted with white points, which, on closer ' The Works of the late Wm. Stark, M. D., &c., by Dr. J. C. Smyth, Lond., 1787. ^ Britisli and Foreign Medico-Chirurg. Rev., Oct. 1848, p. 473. _ ^ Cited in London Med. Gazette, Oct., 1846. See, on this sul)ject, Moleschott, Pliy- siologie des Stoffwechsels im Pflanzen und Thieren, S. 203, Erlangen, 1851. Fat, Pectin, Starch, Bassorin, Gum, Wine, Cane Sugar, Beer, Grape Sugar, Spirits. Sugar of Milk, 116 DIGESTION". examination, were found to be owing to drops of oil in the epithelial cells surrounding the extremities of the villi. As the chyle proceeds along the lacteals, the proportion of fat becomes less and less, whilst that of the nitrogenized matters increases; hence nitrogen must have been obtained, and a conversion have taken place of non-nitrogenized into nitrogenized matters. (See Physiology of Chylosis.) The implicit believers in the views of Liebig, have affirmed, as a matter of course, that fat can only be an " element of respiration ;" yet it appears to be necessary in all cell formation ; and, in the yolk, to be an aliment destined for the formation of every tissue in the animal; as starch — an equally non-nitrogenized article — is in the case of the seed of the vegetable. Moreover, it enters largely into the composi- tion of neurine. These, and analogous considerations, have caused some of those who hastily embraced the doctrine of the distinguished chemist on this subject to pause, and even to retrace their steps;' and evidence enough seems to exist to cause it to be abandoned.^ The alimentary substances, employed by man, have generally been classed either according to the ultimate chemical elements entering into their composition; or to the chief proximate principle or com- pound of organization. In the former case, they have been grouped into : — 1, those that contain nitrogen, carbon, hydrogen, and oxygen; — 2, those that contain carbon, hydrogen, and oxygen ; and 3, those tha^ contain neither nitrogen nor carbon. The first class will comprise most animal and many vegetable substances; the second, vegetable substances chiefly ; whilst water is perhaps the only alimentary matter that belongs to the third. The division proposed by M. Magendie,^ and adopted by Dr. Paris,* is according to the proximate principles, which predominate in the aliment. 1. Amylaceous aliments; wheat, barley, oats, rice, rye, Indian corn, potato, sago^ salep, peas, haricots, lentils, &c. 2. Mucilaginous aliments ; carrot, salsify, beet, turnip, asparagus, cabbage, lettuce artichoke, melon, &c. 3. Saccharine aliments ; the different kinds of sugar, figs, dates, raisins, &c. 4. Acidulous aliments; the orange, currant, cherry, peach, raspberry, strawberr mulberry, grapes, prunes, pears, apples, tomatos, &c. 5. Oili/ and fatty; cocoa, olives, sweet almonds, hazelnuts, walnuts, animal fats, oil^ butter, &c. 6. Caseous aliments ; the different species of milk, cheese, &c. _ 7. Gelatinous aliments; the tendons, aponeuroses, skin, areolar tissue, the flesh of very young animals, &c. 8. Albuminous aliments ; the brain, nerves, eggs, &c. 9. Fibrinous aliments ; comprehending the flesh and blood of different animals. To these proximate principles gluten may be added, which has been termed the most animalized of vegetable"" principles. According to Dr. Prout,* it is separable into two portions, analogous to gelatin and albumen. It is very generally met with, although only in small pro- ' Carpenter, Principles of Human Physiology, p. 69, Amer. edit., Philad., 1855. 2 Rudolph Wagner's Lehrbuch der Specielleu Physiologie, u. s. w. von D. Otto Funke. Iste Lieferung, S. 181, Leipz., 1854. ^ Precis, &c., ii. 34. < A Treatise on Diet, 3d edit., p. 182, Lond., 1837 ; and art. Dietetics, in Cyclopjedia of Practical Medicine, Amer. edit., Philad., 1845. * Chemistry, INIeteorology, and the Function of Digestion, (Bridgewater Treatise,) Amor, edit., p. 558, Philad., 1834. FOOD OF MAN. 117 portion, in the vegetable kingdom; — in all the farinaceous seeds, in the leaves of cabbage, cress, &c.; in certain fruits, flowers, and roots, and in the green fecula of vegetables in general; but it is especially abundant in wheat, and imparts to wheaten flour the property of fer- menting and making bread. Of the nutritious properties of gluten, distinct from other principles, we know nothing precise : the superior nutritious powers of wheaten flour over those of all other farinaceous substances sufficiently attest, that, in combination with starch, it is highly nutritive. Dr. Prout' arranges alimentary principles in four great divisions — the aqueous^ saccharine^ oleaginous, and albuminous. This has been taken as the basis for a classification by Dr. Pereira,^ who admits twelve divisions : — the aqueous, mucilaginous or gummy, saccharine, amylaceous, ligneous, pectinaceous, acidulous, alcoholic, oily ov fatty, proteinaceous, gela- tinous, and saline. By the combination of these alimentary principles and simjjle aliments, our ordinary articles of food or compound aliments are formed. In this classification, the proteinaceous and gelatinous aliments are separated. The following simple arrangement is, per- haps, as little liable to objection as any : — Nitrogenized aliments, (Albuminous of Prout.) II. Non-nitro(jenized aliments, Fibrinous (Glutinous.) Albuminous. Caseinous. Gelatinous. Amylaceous. Saccharine. Oleasrinous. The second division might be still farther simplified; for amylaceous aliments are convertible into sugar during the digestive process ; and of both — as has been seen, — oleaginous matter may be formed. Milk, furnished by the parent for the use of its offspring, contains an admixture of nitrogenized and non-nitrogenized aliments, which, as remarked by Dr. Prout,^ is the true type of all food ; and the same may be said of flour. It is interesting, indeed, to compare the ingre- dients which enter into the composition of milk, wheaten flour, and blood, as given by Dr. Robert Dundas Thomson'' : — Milk. Flouk. Blood. ' Fibrin, ' Fibrin, Curd or Casein, Albumen, Casein, Albumen, Casein, Butter, ^ Gluten, Oil, Colouring matter. Fat. Sugar, Sugar, starch, Sugar. Chloride of potassium, Chloride of sodium, r Phosphate of soda. Phosphate of lime. Phosphate of magnesia, Phosphate of iron. Ditto, Ditto. ' On the Nature and Treatment of Stomach and Renal Diseases, Amer. edit., from the 4th revised London edit., ii. 354, Philad., 1843. ^ A Treatise on Food and Diet, Amer. edit, by Dr. C. A. Lee, p. 38, New York, 1843. ^ Op. cit., p. 3(32; and Chemistry, Meteorology, and the Function of Digestion, &c., Amer. edit., p. 259, Philad., 1834. ^ Experimental Researches on the Food of Animals, &c., Amer. edit., p. 43, New York, 1846. 118 DIGESTIOISr. Water forms tlie basis of all drinks ; but it frequently contains in addition other substances. These have been classed as follows : — 1. Water, of different kinds, 2. Vegetable and animal juices and infusions, as lemon-juice, orange-juice, whey, tea, coffee, &c. 3. Fermented liq^iors, as wines, beer, cider, perry, &c.; and 4. Alcoholic liquors, as brandy, alcohol, kirsch-wasser, rum, gin, whisky, arrack, &c. &c. Dr. Pereira* has proposed the following more complete classification : — 1. Mucila- ginous, farinaceous or saccharine drinks. 2. Aromatic or astringent drinks. 3. Acidulous drinks. 4. Animal broths, or drinks containing gelatin •and osmazome. 5. Emulsive or milky drinks; and 6. Alcoholic and other intoxicating drinks. Water — as has been seen — is considered by him amongst the alimentary principles. An inquiry into the different properties of these various liquids does not belong to the physiologist. It may be remarked, however, that the arguments regarding the natural have been extended to this variety of aliments; and it has been contended, that water is "the most natural drink ;" and that all others, which are the products of art, ought to be avoided. The remarks, already made on this subject, are sufficient. Water was, doubtless, at one period, the only beverage of man, as nakedness, the use of raw aliment, and the most profound ignorance of the universe, were his original condition ; but no one will be presump- tuous enough to declare, that he ought to continue naked, abjure cook- ery, and be plunged into his primitive darkness, on the plea that all these changes are so many artificial sophistications.^ Water is, un- questionably, sufficient for all his wants; but the moderate use of fermented liquors, even if habitual, except in particular constitutions, is devoid, we think, of every noxious result. They are grateful ; and many of them are even directly nutritious from the undecomposed sugar and mucilage which they contain. For this reason beer has been termed, not inaptly, " liquid bread."* With regard to distilled spirits, no evil would result from their total rejection from the table. Although they may, by their action on the digestive organs, be indirect means of nutrition, they contain no alimentary principle. They are received into the vessels of the stomach by imbibition ; and always produce undue stimulation, when taken to any amount. This may be productive of little or no mischief, provided they be only used occasionally ; but, if taken habitually and freely, serious visceral disorder may sooner or later ensue. ^ Lastly, — There are certain substances called condiments employed in diet, not simply because they are nutritive, — for many of them possess no such properties, — but because, when taken with food capable of nourishing, they promote its digestion, correct some injurious property, or add to its sapidity. Dr. Paris has divided these into saline, spicy or aromatic, and oily. It may be remarked, however, that certain articles are called, at times, aliments ; at others, condiments, according as they constitute the basis or the accessory to any dish ; — such are cream, butter, mushrooms, olives, ka. The advantage of condiments in animal • Op. cit., p. 189. \i^ 2 Sue an article by the author in the American Quarterly Review, ii. 422, Thilad., 1827; and Fletcher, op. citat., p. 121. 3 Kitchener, Invalid's Oracle, Amer. edit., p. 136, New York, 1831. FOOD OF MAN. 119 digestion is exemplified by many cases. The bitter principle, wliicli exists in grasses and other plants, appears to be essential to the diges- tion of the herbivora, — acting as a natural stimulant ; and it has been found that cattle do not thrive upon grasses which are destitute of it. Of the value of salt to the digestive function of his cattle, the agricul- turist has ample experience ; and the salt licks of our country show how grateful this natural stimulant is to the beasts of the forests. Charcoal, administered with fat, — as is done, in rural economy for fat- tening poultry, in many parts of England, — exhibits the advantage of administering a condiment ; the charcoal of itself contains no nourish- ment, bat it puts the digestive function in a condition for separating more nutritious matter from the food taken in, than it could otherwise do. A similar effect is produced by the plan, — adopted for the same purpose in certain parts of Great Britain, — of cramming the animal with walnuts, coarsely bruised, with the shell. This is asserted, by many rural economists, to be the most effectual plan for fattening poul- try speedily ; the coarse shell, in passing along the mucous membrane of the intestines, seems to stimulate it to augmented action, and a more bountiful separation of nutritious matter is the consequence. The aromatic condiments act in a similar manner. In regard to the quantity of food required for human sustenance, nothing definite can be laid down. It must differ according to habit, constitution, way of life, age, sex, &c. The diet scale of the British, navy affords a good average for the adult male in busy life, who requires more aliment than those in less active employment. It con- sists of from 31 to 35| ounces of dry nutritious matter daily; of which 26 ounces are vegetable and the rest animal, — 9^ ounces of salt meat, or 4|- ounces of fresh, being the proportion of the latter. This is found to be an ample allowance. That of the navy of the United States consists, four days in the week, of about 45 ounces ; of which about 29 ounces are vegetable, and the rest a}iimal, — the other three days, of about 40 ounces, of which about 24 ounces are vegetable,' — the vegetable matters consisting of beans or peas, biscuit, pickles, cranberries, sugar, tea, flour, dried fruit, and rice, an admixture of nitrogenized and non-nitrogenized articles, which, under ordinary cir- cumstances, is amply suflicient for full nutrition; for, true scurvy appears to be caused by a deficient supply not only of nitrogenized food, but of the organic acids or salts of fresh vegetables ; and one of the best of these, although not the most palatable, is the raw potato.^ In prisons a reduction must be made. In a convict ship, which took out 433 prisoners to New Holland, in 1802, the mortality was trifling, and the general health good, although the prisoners were allowed only 16 ounces of vegetable food, and 7| ounces of animal food per day. Whenever the allowance is more restricted, or a due admixture of ani- mal and vegetable food is not permitted, the health suffers, and signs of scorbutus appear; — a result occasionally witnessed in our public eleemosynary institutions, when under the care of ignorant and too ' The author's Diet, of Med. Science, art. Diet, 12th edit., p. 293, Philad., 1855. ^ See a good article on the causation of scurvy iu tlie Briti,^h and Foreign Medico- Cliirurgical Review, IV., 439, Loud., 1S4S. 120 DIGESTION. economical superintendents. It would seem, from the experiments of M. Chossat, tliat under such circumstances an incapabilit}^ is induced of digesting even the inadequate amount supplied. The smallest quantity of food upon which life is known to have been actively supported was in the case of Cornaro, who affirms that he took no more than 12 ounces a day, and that chiefly vegetable, for a period of sixty-eight years. Of the amount that can be eaten by the glutton, we have surprising instances on record, — the stomach acquir- ing, at times, an enormous capacity. Captain Parry relates the case of a young Esquimaux, who was permitted to devour as much as he chose. It amounted, in the twenty -four hours,, to thirty-five pounds of various kinds of aliment, including tallow candles; and a case has been published of a Hindoo, who could eat a whole sheep at a time. These few remarks on the food of man will serve as an introduction to the mode in which the various digestive processes are accomplished. The more intimate consideration of alimentary substances, with their comparative digestibility, &c., will be found in another work of the author, to which the reader is referred.^ 3. PHYSIOLOGY OF DIGESTION. The detail entered into re2:arding the various organs concerned in digestion will have led to the anticipation, that the history of the func- tion must be multiple and complex. The food is not, in the case of the animal — as it is in that of the vegetable — placed in immediate contact wdth the being to be nourished; an act of volition is, consequently, necessary to procure and to convey it to the upper orifice of the di- gestive tube. This act of volition is excited .by an internal sensation — that of hunger — which indicates the necessity for taking fresh nour- ishment into the system. The appetite and hunger, with the prehension or reception of food, must therefore be regarded as part of the digestive ojDerations. These may be enumerated and investigated in the follow- ing order: — 1st. Hunger^ or the sensation that excites us to take food. 2dly. Prehension of food, the voluntary muscular action, that introduces it into the mouth. 3rdly. Oral or buccal digestion, comprising the changes w^rought on the food in the mouth. 4:thly. Deglutition, or the part taken by the pharynx and oesophagus in digestion. 5thly. Chymi/icatio7i, or the action of the stomach on the food. 6thly. The action of the small intestine. 7thly. The action of the large intestine. And, Sthly. Defeca- tion or the exjmlsion of the fceces. All these processes are not equally concerned in the formation of chyle. It is separated in the small in- testine: the first six, therefore, belong to it; — the remainder relate only to the excrementitious part of the food. The digestion of solid food requires all the eight processes: that of liquids is more simple; com- prising only thirst, prehension, deglutition, the action of the stomach, and that of the small intestine. Fluid rarely reaches the large intestine. In inquiring into this important and interesting function, we shall first attend to the digestion of solids, and afterwards to that of liquids. ' Human Health, p. 179, Philad., 1844. For different dietaries, &c., see Pereira, Treatise on Food and Diet, Amer. edit., by Dr. C. A. Lee, p. 222, New York, 1843; and Art. Diet Scale, in tlie author's Med. Dictionary, 7th edit., Philad., 1S4S. HUNGER. 121 4. DIGESTION OF SOLID FOOD. a. Hunger. Hunger is an internal sensation, the seat of whicli is invariably re- ferred to the stomach. Like every internal sensation, it proceeds from changes in the very texture of the organ. It is not produced by any external cause; and to it are applicable all those observations, that are elsewhere made on internal sensations in o-eneral. In its slio-htest con- dition, it is merely an appetite (optlij; Germ. Esslust); but if this be not heeded, the painful sensation of hunger {Fames^ ?Ltjuo$), supervenes, which becomes more and more acute and lacerating unless food is taken. If this be the case, however, the uneasiness gradually abates; and if sufficient be eaten, a feeling of satiety is produced. The sensation usually occurs, in the healthy state, after the stomach has been for some time empty, having finished the digestion of substances taken in at the previous meal. Habit has a great effect in regulating this recur- rence ; the appetite always appearing about the time at which the sto- mach has been accustomed to receive food. This artificial desire may be checked by various causes; — by the exciting or depressing passions, the sight of a disgusting object, or any thing that occasions intense mental emotion ; or it may be appeased by filling the stomach with substances that contain no nutritious properties. As, however, the feeling of true hunger arises from the wants of the system, the natural and instinctive sensation soon appears, and cannot be long postponed by any of these means. Hence, it has been proposed to make a dis- tinction between appetite and liunger; applying the former term to the artificial, the latter to the natural, desire. In these respects, there is certainly a wide distinction between them, as well as in the capricious- ness, which occasionally characterizes the former, and gives rise to singular and fantastic preferences. The sensation of hunger varies in intensity according to different circumstances. It is more powerful in the child and youth than in one who has attained his full height. In the period of second childhood, it is urgent, — probably owing to the diminished power of assimilation requiring that more aliment should be received into the stomach. In disease, the sensation is generally suppressed, and its place often sup- plied by loathing or disgust for food : at times, again, its intensity makes it a phenomenon of disease, as in bulimia, and pica; in the latter of which, the appetite is, at times, irresistibly directed to sub- stances, which the person never before relished, or are not edible, — as chalk, earth, slate-pencil, &c., a prominent symptom of chlorotic and African cachexia. The appetite is also modified by exercise or in- activity, and other circumstances, extrinsic and intrinsic, — regular exer- cise, and the exhilarating passions ; a cold and dry atmosphere, &c., augmenting it, whilst it is blunted by opposite circumstances. Long continued exertion, with a scanty supply of nourishment, if not con- tinued so long as to injure the tone of the stomach, produces, occasion- ally, in adults, a voracious appetite and rapid digestion. Mr. Hunter has quoted, in illustration of this point, the following extract from Admiral Byron's narrative. After describing the privations he had suffered when shipwrecked on the coast of South America, the Admiral 122 DIGESTIO:^. incidentally refers to tlieir effect upon his appetite. "The governor ordered a table to be spread for us with cold bam and fowls, which only we three sat down to, and in a short time despatched more than ten men mth common appetites would have done. It is amazing, that our eating to that excess we had done from the time we first came among these kind Indians had not killed us, as we were never satisfied, and used to take all opportunities for some months after, of filling our pockets, when we were not seen, that we might get up two or three times in the night to cram ourselves."^ Authors have distinguished the local from the general phenomena of hunger; but many of their assertions on these points appear ima- ginative. We are told by M. Adelon^ and others,^ that the stomach becomes contracted, and that this change is effected by the action of its muscular coat alone; — the mucous or lining membrane beconjing wrinkled, and the peritoneal coat, externally, permitting the organ to retire between its laminae. Such, MM. Tiedemann and Gmelin^ assert, is the result of their observations. M. Magendie,^ however, afiGirms, that after twenty-four, forty-eight, and even sixty hours complete abstinence, he has never witnessed this contraction of the organ. It had always considerable dimension, especially in its splenic portion; and not until after the fourth or fifth day did it appear to him to close upon itself, diminish greatly in capacity, and slightly change its posi- tion; and these effects were not observed unless the fasting was rigor- ouslj'' maintained. At the time that the stomach changes its shape and situation, the duodenum is said to be drawn slightly towards it; its parietes appear thicker, — and the mucous follicles and nervous papillae project more into the interior. Its cavity is void of food, and contains only a little saliva, mixed with bubbles of air; a small quantity of mucus; and, according to some, a little bile and pancreatic juice, which the traction of the duodenum has caused to flow into it. Much dispute has arisen as to whether the circulation of the blood in the stomach experiences any mutation. M. Dumas^ was of opinion, that when the organ is empty, it receives less blood than when full ; either on account of the great flexion of the vessels in the former case, or on account of the compression experienced by the nerves in conse- quence of the contracted state of the organ. He thinks that, under such circumstances, a part of the blood sent to it reflows into the liver, spleen, and omentum; and he regards these organs as diverticula for the blood of the stomach, especially as the liver and spleen are then less compressed, and the omentum is more extensive, owing to the retraction of the stomach. Bichat, however, denies both the fact and its explanation. He affirms, that on opening animals suffering under hunger, he never observed the vessels of the stomach less full of blood, the mucous membrane less florid, or the vessels of the omentum more ■ Bvron's Voyage, p. 181 ; and Hunter on the Animal Economy, p. 196. ^ riiysiologie de rtlomme, ii. 39i3. 8 Riillier, Art. Paim, in Diet, de Midecine, torn, viii., Paris, 1823. ■» Die Verdauung nach. Versuclieu, u. s. w. ; or French translation, by A. J. L. Jour- dan, Paris, 1827. * Op. citat., ii. 25. 6 Principes de Pliysiologie, Paris, 1806. HUNGEK. 123 turgid. Is it not true, he adds, that the vessels of the stomach are more flexuous when the organ is empty ; being, as well as the nerves, connected with the serous coat, they are unaffected by changes of size in the organ; and besides, the retraction of the stomach could never be great enough to compress the nerves. He denies, moreover, that the liver and spleen are more free, and the omentum larger, whilst the stomach is empty, as the abdominal parietes contract in the same pro- portion as the stomach. Magendie,^ however, contests this last asser- tion of Bichat ; and affirms, on the. faith of positive experiments, that the pressure sustained by the abdominal viscera is in a ratio with the distension of the stomach. If the stomach be full, the linger, intro- duced into the cavity of the abdomen through an incision in its parie- tes, will be strongly pressed upon, and the viscera forced towards the opening; whilst, if it be empty, the pressure as well as the tendency of the viscera to escape through the opening is considerable. During the state of vacuity of the organ, he remarked that the different reser- voirs in the cavity of the abdomen, — the bladder and gall bladder, — were more easily filled by their proper fluids. With regard to the quantity of blood circulating through the stomach in the empty and full state, — he is disposed to believe, that the organ receives less in the former condition; but that in this respect it does not differ from other abdominal viscera. The general effects, said to be produced by hunger, in contradistinc- tion to the local, are; — debility and diminished action of every organ; the circulation and respiration are less frequent ; the heat of the body sinks; the secretions diminish, and all the functions are exerted with more difficulty, if we except absorption, which it is affirmed, and with much probability, is augmented. If the abstinence be so long pro- tracted as to cause death, the debility of the functions becomes real, and not sympathetic. Eespiration and circulation languish; all the animal functions totter; whilst absorption continues, and the blood is supplied by the decomposition of the different organs, — the fat, the various liquid matters and the tissues of the organs being successively subjected to its action. It is obvious, however, that, with the drain perpetually taking place, this state of affairs cannot exist long; the blood becomes diminished in quantity, and insufficient in every respect to vivify the organs; the functions of the brain are perverted, and, in many instances, furious delirium has closed the scene ; whilst, at others, the miserable sufferer has sunk passivel}'' into the sleep of death. Occasionally, again, so dreadfully painful are the sensations caused by protracted privation of food, that the most violent antipa- thies and dearest affections have been overcome; and numerous in- stances have occurred in which the sufferer has attacked his own species, friends, children, and even his own person. The horrible picture of the shipwreck, by B3aT>n,^ is not a mere romance. It is a narrative of facts that have actually occurred, expanded somewhat by the imagination of the poet. Dr. James Currie^ has related the case of a person, who died of ' Precis, &c., edit, cit., ii. 26. ^ Don Juan, canto ii. 58. ^ Medical Reports, &c., Amer. edit., Pliilad., 1808. 124 DIGESTIOX. inanition from stricture of the oesophagus, the particulars of which may exemplif}^ the phenomena presented by some of those who perish from abstinence. The records of such cases are rare. From the 17th of October to the 6tli of December, the patient was supported, without the aid of the stomach, by means of broth clysters; and was immersed in a bath of milk and water. At one period he had a parched mouth : a blister discharged only a thin, coagulable h'mph ; and the urine was scanty, extremely high-colored, and intolerably pungent. The heat of the body was natural and nearly uniform from first to last ; and the pulse was perfectly natural until the last days. His sleep was sound and refreshing; spirits even; and intellect unimpaired, until the last four days of existence, when clysters were no longer retained. Vision was deranged on the first of December, and delirium followed on the succeeding day ; yet the eye was unusually sensible, and the sense of touch remarkably acute. The surface and extremities were at times of a burning heat; at others, clammy and cold. On the fourth, the pulse became feeble and irregular, and respiration laborious; and, in ninety- six hours after all means of nutrition as well as medicine had been abandoned, he ceased to breathe. He was never much troubled by hunger. Thirst was, at first, troublesome, but it was relieved by the tepid bath. This was a case in which the patient sank tranquill}^ to death. In others, the distressing accompaniments above described are met with ; and the death is that of a furious maniac. The period at which the fatal event may occur from protracted absti- nence is dependent on many circumstances. As a general rule the young and robust will expire sooner than the older ; and this will have to be our guidance in questions of survivorship, where several indi- viduals have perished together from this cause. Tlie picture, drawn by Dante of the sufferings and death of Count Ugolino della Gherar- descha, who saw his sons successively expire before him from hunger, is in this respect true to nature. " Now when our fourth, sad morning was renew'd, Gaddo fell at my feet, outstretch'd and cold, Crying : — ' Wilt thou not, father ! give me food ?' There did he die ; and as thine eyes behold Me now. so saw I three fall, one by one, On the fifth day and sixth ; whence in that hold, I, now grown blind, over each lifeless son Stretch'd forth mine arms. Three days I called their names. Then Fast achieved what Grief not yet had done." "IxFERXO," canto xxxiii. _ In some experiments on inanition undertaken by M. Chossat,^ on pigeons and turtle doves, the following general phenomena were ob- served. Commonly, the animal remained calm during the first lialf or two-thirds of the period. It then became more or less agitated, and this state continued as long as the temperature remained elevated. On the last day of life, however, the restlessness ceased, and gave place to stupor. When set at liberty, it sometimes looked round with astonishment, without attempting to fly, and at times closed its eyes, as if in a state of sleep. Gradually, the extremities became cold, and ' Recherches Experimentales sur I'lnanition, Paris, 1343 ; noticed in Brit, and For. Med. Ilev., April, 1844, p. 347. HUNGER. 125 the limbs so weak as to be no longer able to sustain it in the standing posture. It fell over on one side, and remained in any position in ■\vhicli it might be placed, without attempting to move. Kespiration became slower and slower; the general weakness increased, and the insensibility became more profound ; the pupils dilated ; and life be- came extinct. — at times in a calm and tranquil manner ; at others, after convulsive actions, producing opisthotonic rigidity of the body. He tried to discover the effect of age in modifying the continu- ance of life during inanition, but was unable to ascertain the re- lative ages of the turtle doves, the subjects of his experiments ; he endeavoured, however, to form some estimate — although, obviously, a fallacious one — from their relative weights, classing them as "young," " middle-aged," or " adult," according as their weights were beneath 120 grammes, from 120 to 160, or above 160. The following table is interesting, 'however, by showing the duration of life, and the loss of substance during inanition, in animals of different weights. WEIGHT OF THE BODT. LOSS OF THE BODT. Duration of life. Weight at commeuce- ment. Weight at death. Entire ah.so- lute loss. Proportional less in 1000 part.s. Daily propor- tional loss. a. Young . . . h. Middle-aged c. Old .... Gram. 110-42 143-62 189-36 Gram. 82-84 91-60 101-61 Gram. 27-58 52-02 87-75 0-250 0-362 0-463 0-081 0-059 0-035 3-07 6-12 13-36 The entire absolute loss, and the proportionate loss, were much greater in the heavier animals; the daily loss was by much the most rapid in the lightest ; and it is probable, that this was owing to the more rapid waste which takes place in the young. The sensation of hunger resembles every other sensation in the mode in which it is accomplished. There must be impression, conduction, and perception. That the encephalon is the organ of the last part of the process is proved by all the arguments used in the case of the internal sensations in general. Without its intervention in this, as in every other case, no sensation can be accomplished. The stomach is the organ in which the impression is effected; and by means of the nerves this impression is conveyed to the spinal marrow and encepha- lon. The eighth pair or pneumogastric nerves have generally been regarded as the agents of this transmission ; and it has been affirmed by Baglivi, Valsalva, Haller, Dumas, Legallois, Chaussier, and others, that if they be divided in the neck, although the stomach may be favourably circumstanced, in other respects, for the developement of the impression of hunger, and the encephalon for its reception, there is no sensation; but MM. Leuret and Lassaigne,' Dr. John Eeid,^ Nasse,^ and Longet,* tleny, that such effect follows the division of these ' Recherclies Pliysiologiques et Cliiiniques pour servir a I'Histoire de la Digestion Paris, 1825. ^ Edinb. Med. and Surg. Journal, April, 1839, and art. Par Vacum, in Cj-clop. of Anat. and Physiol., Pt. xxviii. p. 899, Lond., April, 1847. " Untersuchungen zur Physiologie und Pathologie, Bonn, 1835-6. " Traite de Physiologic, ii. 342, Paris, 1850. 126 DIGESTION. nerves ; and the first gentlemen affirm, that horses have eaten as usual,! and apparently with the same appetite, after they had removed severalj inches of the pneuraogastric nerves; and even continued to eat afterj the stomach was filleft To these experiments we shall have occasion to refer hereafter. They by no means, however, exhibit that this in-| ternal sensation differs in its essence from others. A difficulty, which the physiologist has always felt, concerns thei precise nature of the action of impression. Its seat is clearly in thej stomach. This was shown incontestably by a case of fistulous open- ing into the organ, which fell under the care of Dr. Beaumont, and to which there will be frequent occasion to refer. When the subject of this case was made to fast until his appetite was urgent, it was imme- diately assuaged by feeding him through the aperture. To the sto- mach, indeed, all our feelings refer the sensation. It is dependent upon some modification occurring in the very tissue of the viscus; and in the nerves, which, as has been shown, are the sole agents in all phenomena of sensibility. These nerves are spread over the stomach, so that the precise seat of the impression cannot be as accurately de- fined as in the case of the organs of external sense. Moreover, the nerves of the stomach proceed from two essentially different sources, — ■ the eighth pair, and great sympathetic. The question consequently arises: — on which of these is the impression made? The results of the experiment of cutting the eighth pair in the neck would appear to decide in favour of the former. As to the proximate or efficient cause of hunger, we cannot expect to arrive at any satisfactor}^ conclusion. It is a sensation; and, like all sensations, inscrutable.' Theories, however, as on all obscure topics, have been numerous, and these have generally been of a me- chanical or a chemical nature. Some have attributed it to the mecha- nical friction of the parietes of the stomach against each other, in consequence of its contraction; in which state, they affirm, the mucous coat is rugous, and its papillae and follicles prominent. It is manifest, however, from the structure of the organ, that no such friction can take place. Yet this view was embraced by Haller.^ Dr. Fletcher^ ascribes it to a kind of permanent though partial contraction of the muscular fibres of the stomach ; — " not that alternate general contrac- tion and relaxation, which produces a sensible motion of this organ, nor that permanent general contraction, which would serve to dimi- nish its cavit}'', but that kind of permanent contraction, which takes place in certain fibres alone, and perhaps through a part of their length only, and by which these|^bres are, as it were, drawn away from the others, or, in other words, a minor degree of cramp." Others, again, have accounted for the sensation by the action of the gastric juice, which is supposed to have a tendency to irritate the internal mem- brane. In proof of this, they refer to a case, mentioned by ]\Ir. Hun- ter, in which the mucous membrane, in a man who died of fasting, was found corroded. The gastric j nice is, however, incapable of eroding ' J. Beclard, Traite elementaire de Physiologie, p. 26, Paris, 1855. 2 Element. Physiol., lib. xix., sect. 2, § 12, Bern., 1764. 3 Rudiments of Physiology, Part iii., by Dr. Lewins, p. 73, Edinb., 1837.- PEEHENSIOX OF FOOD. 127 living animal matter; and the numerous cases, wliicli have occurred since that of Hunter, have shown, that the corrosion and perforation, which we meet with on dissection, may be referred to an action after death, and be totally unconnected with the sensation felt during life. We have, indeed, no reason for believing, that the gastric juice can ever attain a state of acridity, and affect physically the surface by which it is secreted. It has been remarked, that it is a law of the animal economy, that no secretion acts upon the part over which it is destined to pass, provided such part be in a healthy condition. Yet Stimmering^ ascribes the pain from long-continued fasting to the action of the gastric juice; and Dr. Wilson Philip^ is manifestly induced to believe that its influence on the stomach is, in some mode or other, productive of the sensation : his remarks, however, tend simply to show, — what we have so many opportunities for observing, that the sensation can be postponed by exciting vomiting, or inducing, for the time, a morbid condition of the stomach. The unanswerable objection to all these views is the fact — repeatedly proved by Dr. Beaumont,^ and which the author had an opportunity of observing — that, in the fasting state there is little or no gastric juice in the cavity of the stomach. Dr. Beaumont thinks, that the sensation of hunger is produced by distension of the vessels, that secrete the solvent ; but such distension, if it exist — which is by no means proved — must itself be consecutive on the nervous condition that engenders the sensation: the efficient cause of such condition has still to be explained. Bichat, again, attributed it to the lassitude or fatigue of the stomach, occasioned by the contraction of its muscular coat when continued beyond a certain time. In answer to this, it may be remarked, that if any thing impedes the nutrition of the body, hunger continues, although the stomach may be distended. This happens in cases of scirrhous pylorus, where the nutritive mass cannot pass into the small intestine, to be subjected to the action of the chyliferous vessels, and the losses of the body cannot, therefore, be repaired ; — facts which would seem to show, that hunger is a sensation excited in the stomach by sympathy with the wants of the constitution ; and that it is imme- diately produced by some inappreciable alteration in the condition of the nerves of the organ. It appears, from the experiments of M. Ma- gendie,^ that when the cerebrum and a great part of the cerebellum were removed in ducks, the instinct of seeking food was lost in every instance, and the instinct of deglutition in many : food, however, in- troduced into the stomach, was found to be digested. b. Prehension of Food. The arms and mouth have been described as organs of prehension. It is scarcely necessary to say, that the hands seize the food and convey it to the mouth under ordinary circumstances ; but there are cases in ' De Corp. Hiimcan. Fabric, torn, vi., Traject. ad Moenum, 1794-1801. * Experimental Inquiry into tlie Laws of the Vital Functions, 2d edit., Lond., 1818. ^ Experiments and Observations on the Gastric Juice, and the Physiology of Diges- tion, p. 57, Plattsburg, 1833. * Precis, &c., ii. 1G8. 128 DIGESTION. wliicli the mouth is the sole or chief organ of prehension. !Mopt ani- mals are compelled to use the mouth only, "When the food is conveyed to it by the hands, it must open to receive it. The mode in which this is effected has given rise to controversy ; and, strange to say, is not yet considered determined. Whilst some physiologists have asserted, that the lower jaw alone acts in opening the mouth moderately; others have affirmed, that both the jaws separate a little; — the lower, however, moving five or six times as much as the upper. That the latter is the correct view can be proved by positive experiment. If, when the mouth is closed, we place the flat side of the blade of a knife against the teeth of both jaws; and, holding the knife immovably, separate the jaws; we find, that both jaws move on the blade; but the lower to a much greater extent than the upper. Now, as the upper jaw is fixed immovably to the head, the whole head must, of necessity, participate in this movement; and the question arises, what are the agents that produce it? Some attribute it to a slight action of the extensor muscles of the head; and affirm, that whilst the depressors of the lower jaw carry it downwards, the extensors of the head draw the head slightly backwards, and thus raise the upper jaw. MM. Magendie^ and Adelon^ assert, that when the mouth is opened moderately, the upper jaw does not participate; but, that if the motion be "forced" or extensive, it participates slightly. The experiment, however, with the knife, which is adduced by M. Adelon himself, com- pletely overthrows this notion ; and shows, that both jaws act, whenever the mouth is slightly opened. M. Magendie agrees with those who consider, that, whenever the upper jaw is raised, it must be by the head being thrown back on the vertebral column; and he properly remarks, that where there is a physical impediment to the depression of the lower jaw, the mouth must be opened solely by the retroversion of the head on the spine. M. Ferrein^ conceived, that the motion of the upper jaw is occasioned by the action of the stjdo-hyoideus muscle, and the pos- terior belly of the digastricus; and he affirms, that whilst the anterior fasciculus or belly of the digastricus depresses the lower jaw; the pos- terior belly with the stylo-hyoideus carries the head backwards, and, with it, the upper jaw. The attachments, however, of these muscles sufficiently show, that they cannot be the agents: the mastoid process, to which the posterior belly of the digastric muscle is attached, is near the articulation of the head with the atlas; whilst the styloid process, to which the stylo-hyoideus is attached, is anterior to the articulation ; and its effect ought to be to depress the upper jaw. The view of Pro- fessor Chaussier is the most probable. He ascribes the slight elevation of the upper jaw to the mechanical arrangement of the joint of the lower. The temporo-maxillary articulation is not formed by a single condyle, but by two, which are so disposed, that the lower cannot roll downwards during the depression of the lower jaw without causing the upper condyle to roll upwards, and, consequently, to elevate slightly, the upper jaw. Under ordinary circumstances, then, the jaws cannot be at all separated without both participating; but if we determine to fix the upper jaw, we can make the lower the sole agent in the movement. • Op. citat., ii. 43. 2 Qp. citat., ii. 408. ^ Memoir, de TAcad. des Sciences pour 1744. PREHENSION OF FOOD. 129 As soon as the food is introduced into tlie mouth, the jaws are closed to retain it, and subject it to mastication. Frequently, however, they assist in the act of prehension, as when we bite a fruit, to separate a portion from it ; the incisor teeth acting, in such case, like scissors. This is chiefly produced by the contraction of the muscles that raise the lower jaw ; and it is probable, that the action of the stylo-hyoideus Fiff. 52. Action of the Lower Jaw in Prehension. A. Frontal bone. B. Temporal. C. Parietal. D. Occipital. E. Coronoid process of the lower jaw, to which the temporal muscle i.s attached. F. Condyloid process or head of the lower jaw. G. Lower jaw. H. Mastoid process. I. Upper jaw. J. Cheeli bone. K. Orbit. L. Meatus auditorius externus. L*. Coronal suture. M. Squamous suture. N. Lambdoidal suture, g. Lower jaw depressed. is concerned in the movement ; drawing the head and upper jaw with it downwards and forwards. The levator muscles of the jaw act here with great disadvantage ; — the lower jaw representing a lever of the third kind; the fulcrum being in the joint; the ])Ower at the insertion of the levator muscles ; and the resistance in the substance between the teeth. The arm of the resistance is, consequently, the whole length of the lever; and we can understand why we are capable of developing so much more force, when the resistance is placed between the molares ; and why old people, — who have become toothless, and are, consequently, constrained to bite with the anterior part of the jaws, — the only por- tion that admits of contact, — cannot bite with any degree of strength. The size of the body, put between the incisor teeth, influences the degree of force that can be brought to bear upon it. AVhen small the force can be much greater, as the levator muscles are inserted perpen- VOL. I. — 9 130 DIGESTIO^^. dicularly to the lever to be moved, and the whole of their power is advantageously exerted ; but if the body be so large, that it can scarcely be received into the mouth, and be resisting withal, the incisors can scarcely penetrate it; — the insertion of the levator muscles into the jaw being rendered very oblique; and the greater part of the force they develope consequently lost. This will be readily seen by Figure 52. When the mouth is closed, or nearly so, the masseter, and temporal muscles represented respectively by the lines B E and jy, are inserted nearer the perpendicular; but when the lower jaw is depressed, so that the situation of these muscles is represented by the dotted lines B e and J A", the direction in which the muscles act will be more oblique, and, therefore, more disadvantageous. When the muscles of the jaws are incapable, of themselves, of separating the substance, as in the case of the apple, the assistance of the muscles of the hand is invoked; whilst the muscles on the posterior part of the neck, which are inserted into the head, draw it backwards; and, by these combined efforts, the sub- stance is forcibly divided. c. Oral or Buccal Digestion. The changes, effected upon the food in the mouth, are important preliminaries to the function that has to be executed in the stomach and duodenum. As soon as it enters the cavity, it is subjected to the action of the organ of taste, and its sapid qualities are appreciated. By its stay there, it also acquires nearly the temperature of the cavity. This is, however, a change of little moment, unless the food is so hot, that it would injure the stomach, if passed rapidly into it. Undei such circumstances, it is tossed about in the mouth, until it has partec with its caloric to various portions of the parietes of the cavity; an^ then, if in a fit state for the action of deglutition, it is transmitted aloni the oesophagus ; but the most important parts of oral digestion are th^ movements of mastication and insalivation by which solid food is coraJ minuted, and imbued with the secretions poured into the interior of th^ mouth, and which we have shown to be of a very compound character; Under the sense of taste, the influence of the agreeable or disagree- able character of the food upon the digestive function is expatiated upon. It is unnecessary, therefore, to do more than allude to the sub- ject here. We find that whilst a luscious aliment excites to prolonged mastication, and the salivary glands to augmented secretion, the mas- ticatory and salivary organs, by dividing and moistening the food, permit the organs of gustation to enjoy the savour by successive ap- plications. When the food is received into the mouth, if it be sufficiently soft, it is commonly swallowed immediately ; unless the flavour is delicious, when it is detained. If solid, and, especially, if of any size or density, it is divided into separate portions, or chewed, — the action constituting mastication. If the consistence of the substance be moderate, the tongue, by being pressed strongly against the bony palate, is sufilcient to effect this division; bruising it, and at the same time, expressing its fluid portions. If the consistence be greater, the action of the jaws and teeth is required. For this purpose, the lower jaw is successively depressed and elevated by the action of its depressors and levators ; ORAL DIGESTIOX. 131 and the horizontal or grinding motion is produced at pleasure by the action of the pterygoids. Whilst these muscles are acting, the tongue and cheeks are incessantl}^ moving, so as to convey the food between the teeth, and insure its comminution. Mastication is chiefly effected by the molares. There is advantage in using them, independently of their form, in consequence of the arm of the resistance being much shortened, as has already been shown. The teeth are well adapted for the service they have to perform. The incisors, as their name imports, are used for cutting; hence their coronte come to an edge; the canine teeth penetrate and lacerate, and their coronas are acuminated ; whilst the molares bruise and grind, and their touching surfaces are tuberous. The first, having usually no great eftbrt to sustain, are placed at the extremity of the lever ; the latter, for opposite reasons, are nearest the fulcrum. To preclude displacement by the eftbrts they have occasionally to sustain, they are firmly fixed in the alveoli or sockets ; and, as th'^ roots are conical, and the alveoli accurately embrace them, the force, as in the case of the wedge, is transmitted in all directions, instead of bearing perpendicularly on the jaw, which it would do, were the fangs cylindrical. The molar teeth, having the greatest efforts to sustain, are furnished with several roots; or with one that is extremely large. The gums add materially to the solidity of the junction of the teeth with the jaws. They are themselves formed of highly resisting mate- rials, so as to withstand the pressure of hard and irregular substances. Whenever they become spongy, and fall away from the teeth, the latter become loose ; and are frequently obliged to be extracted, in conse- quence of the loose tooth acting as an extraneous body, and inflaming the lining membrane of the alveolus. The arrangement of the jaw is well adapted to the function ; the lower jaw passing behind the upper at its anterior part ; but coming in close contact at the sides, where mastication is chiefly effected. During the whole time that mastication is going on, the mouth is closed ; — anteriorly, by the lips and teeth, which prevent the food from falling out of the cavity; and posteriorly by tiie velum palati, the anterior surface of which is applied to the base of the tongue. At the same time, the food is undergoing insalivation or admixture with the various fluids poured into the mouth, and particularly with the saliva, the secretion of which is augmented, not only by the presence of food, but even by the sight of it, especially if the food be desirable; — giving rise to what is called "mouth-watering." It is probable, that, inde- pendently of mental association, the action of the secretory organs is increased by the agitation of the organs themselves during the masti- catory movements. It has, indeed, been asserted, that the parotid glands are so situate, as regards the jaws, that the movement of the lower jaw presses upon them, and forces out the saliva; but MM. Bordeu and J. Cloquet have demonstrated, anatomically and by expe- riment, that this is not the case.' It has been supposed by some, that admixture with saliva commu- nicates to the food its first degree of animalization ; or in other words, ' Adelon, op. cit., ii. 418. 132 BTGESTION. its first approximation to the substance of the animal it lias to nourish. Such are the opinions of Professor Jackson' and M, Voisin.^ The former asserts, that he has ascertained positively, that the saliva exerts a very energetic operation on the food, separating, by its solvent pro- perties, some of its constituent principles, and performing a species of digestion. MM. Tiederaann and Graelin. too, think that the water, and the carbonates and acetates of potassa and soda, and the chlorides of potassium and sodium, of the saliva, contribute to soften and dissolve the food; whilst the nitrogenized materials, the salivary and albumi- nous matters, communicate to it a first degree of animalization. It is .more probable, however, that the main use of mastication and insali- vation is to give the food the necessary consistence, in order that the stomach and small intestine may exert their action upon it in the most favourable manner ; and that, consequently, the changes effected upon it in the mouth, are chiefly of a mechanical character. In the case of many substances — as sugar, salt, &p,. — a true solution takes place in the saliva ; and this probably happens to sapid bodies in general ; — the particles being separated by imbibing the fluid. Krimer,^ of Leip- zig, held in his mouth a piece of ham, weighing a drachm, for three hours. At the expiration of this time, the ham was white on its sur- face, and had increased in weight twelve grains. He believes, that the tears assist in digestion, and that they flow constantly by the posterior nares into the stomach. It would seem that an important action of the saliva is the conver- sion of starch — boiled starch — into dextrin or grape sugar. From one drachm of starch, Dr. Wright" obtained in twelve hours, at a tempera- ture of 98°, by admixture with saliva, thirty-one grains of sugar. This probably takes place by the action of some nitrogenized secretion, like pepsin in stomachal digestion. It has been affirmed, indeed, on the strength of numerous and varied experiments detailed before the French Academy of Sciences,* by MM. Bernard de Villefranche and Barreswil, that in the gastric juice, pancreatic fluid, and saliva, an organic principle or ferment exists, which is common to them all; and that it is the nature of the chemical reaction associated with it, which alone determines their power of digesting the different alimentary principles. In an alkaline fluid, all three have the power of trans- forming starch, and do not digest meat; whilst in an acid fluid they dissolve meat, but do not act on starch. Hence, they think, it appears easy to transform these fluids into each other, and to make for example an artificial gastric juice from pancreatic fluid. The action of saliva, however, is said to be less energetic, both on meat and starch, than the pancreatic fluid. For the organic compound in the saliva, M. Mialhe'* proposes the name animal diastase or diastase salivaire. It would seem, however, from the experiments of MM. Magendie^ and ' Principles of Medicine, j). 354, Philad., 1832. 2 Nouvel Aper(;u sur la Physiologie du Foie, &:c., Paris, 1833. 3 Versuch einer Physiologic des Blutes, Leipz., 1820. * Lend. Lancet, 1841-2. s Comptes Rendus. 7 Juillet, 1845. 6 Lancette Franc-aise, Avril, 1845 ; and Miallie, Chimie appliquee a la Pliysiologie et i. la Tlierapeutiqiae, p. 39, Paris, 185(i. ' Comptes Reudus, 1847, p. 117. OEAL DIGESTIO^r. 133 Bernard/ that many substances besides saliva, — as pieces of the mu- cous membrane of the mouth, bhidder, rectum, and other parts, various animal and vegetable tissues, and even morbid products effect the transformation of starch into sugar ; but that the gastric fluid does not. The part of the saliva, according to M. Bernard, which appears to be most active in this transformation, is that secreted by the small glands and the mucous membrane of the mouth ;^ but it has been properly observed, by Messrs. Kirkes and Paget,^ that if the influence of saliva in aiding the digestion of farinaceous food be admitted, we have yet to seek for the corresponding purpose served by the saliva of the car- nivora, which consume no such food; and on this point we possess at present no information. M. Bernard'* believes, that the parotid, labial and buccal glands, which secrete a more watery fluid, are aquiparous ; and more especially auxiliaries in mastication; whilst the maxillary, sublingual and palatal are muciparous, and furnish the thicker mucous matter which sur- rounds the alimentary bolus, and facilitates its onward course in the act of deglutition.* The secretion from the different glands certainly varies greatly. M. Lassaigne^ examined the fluid from the parotid andv the submaxillary in the same animal. The latter was much more viscid, and resembled mucus in consistence. It is probable that the main action of saliva is to soften the food ; for when substances are well mixed with water, they are retained in the mouth for a short time only; and, consequently, in an amylaceous solution there is no opportunity for change to be effected. Experi- ments, instituted by M. Lassaigne,'' by a committee of the Institute, and by M. Bernard^ show, that when the food is dry a considerable admixture of saliva takes place, whilst if it be so softened, that masti- cation is not needed, it absorbs scarcely any. In executing these experiments, the aliment was weighed before giving it to the animal ; the oesophagus was cut across; and the aliment, after having been chewed and insalivated, was received through the wound in the neck. jThe difference in weight indicated the quantity of saliva that had been added to it. According to Professor Berard,^ these experiments teach us: First. That dry forage absorbs about four or five times its v/eight 'of saliva and mucus. Secondly. That dry feculaceous articles (oats, starch and barley meal) absorb a little more than their weight. Thirdly. That green forage (green leaves and stalks of barley) absorb a little less than half their weight; and fourthly ; that moist feculaceous arti- cles (starch and bran) to which sufficient water has been added for the ' Canstatt und Eisenmann, Jahresbericlit iiber die Fortscliritte in der Biologie, im lahre, 1847, s. 117. ^ See, also, Frerichs, in Canstatt's Jahiesbericlit, 1850, p. 134; and art. Verdaunng, n Wagner's Handwort. der Physiologie, Bd. iii. Abth. 1, Braunscli., 184(j ; and Bidder ind Schmidt, Die Verdauungssiifte, s. 1, Mitau und Leipz., 1852. ' Manual of Pliysiology, 2d Amer, edit., p. 163, Pliilad., 1853. * Comptes Rencius, 1852, p. 236. * Beraud, Manuel de Physiologie, p. 88, Paris, 1853. ^ Journ. de Chimie Med., p. 393 ; and Scherer, in Canstatt's Jahresbericlit, 1852, s. 06. ' Journal de Chimie Medicale, p. 472, Paris, 1845. * Archives Generales de Medecine, 4e s rie, torn. xiii. p. 1. * Cours de Physiologie, p. 721, Paris, 1848. 134: DIGESTION. food to be swallowed witliout previous mastication, do not sensibly absorb any. Botli mastication and insalivation are of moment, in order that digestion shall be accomplished in perfection; and, accordingly, they who swallow food without due mastication, or waste the saliva by con- stant and profuse spitting, are more liable to attacks of dyspepsia, or imperfect digestion. It is proper, however, to add, that Dr. Trudge,* on extirpating the salivary glands in animals, did not find that they sustained the smallest apparent injury; whence he conjectures, that certain glands can act as succedanea to others, and that on the removal of the salivary glands the pancreas supplies perhaps the fluid usually secreted by the other. A table given by Dr. Robert Dundas Thomson^ as the results of ex- periments on two cows, signally exhibits the beneficial effects of a proper grinding of the food. The cows were fed on entire barley and malt steeped in hot water. They were then fed on crushed barley and malt prepared in the same manner. The influence of the finer division of the grain in increasing the quantity of milk is strikingly shown, f Browx Cow. White Cow. Milk in periods of five days. Milk in periods of five days Entire barley and grass, . . i lllilbs 97l " . 106 lbs. 94 " Entire malt and grass, . . ] r 96 " 95 " 98 " . 104 " 1151 « . 109i " Crushed barley, grass and hay, < r 105" " 110 " 97 " . 109i " . 110 " . 1061 " Crushed malt and hay, . . -l 96 " 98 " . 107i " . ml " The table exhibits, that with the entire barley, the milk diminished during the second five days of the experiment, whilst with the crushed barley it had a tendency to increase during each succeeding period. The degree of resistance, and sapidity of the food, apprise us when mastication and insalivation have been sufficiently exerted. When this is the case it is subjected to the next of the digestive processes. Some physiologists have affirmed, that the uvula is the organ which judges when the food is adapted for deglutition. M. Adelon, whose views are generally worthy of great favour and attention, asserts, " that it judges by its mode of sensibility, of the degree in which the aliment has been prepared in the mouth ; of the extent to which it has been chewed, im- pregnated with saliva, and reduced to paste; and, according to the impression it receives, it excites, sympathetically, the action of all those parts ; directs the convulsive contraction of the muscles that raise the pharynx: even keeps the stomach on the alert, and disposes it to receive favourably or to reject the food passing to it." Such a function would be anomalous. It is, indeed, inconceivable that so insignificant an organ could be possessed of those elevated attributes. Observation, also, proves, that the notion is the offspring of fancy. M. Magendie^ ' jredicinischo Zeitung, May 4, 1842; cited in British and For. Med. Rev., July, 1842, p. 221. ' i:xperimental Researches on the Food of Animals, Amer. edit., New York, 1846. 3 Op. cit., ii. 58. DEGLUTITION. 135 asserts, that lie has known several persons who had entirely lost the uvula, either by venereal ulceration or by excision, and yet he never remarked that their mastication experienced the slightest modification, or that they swallowed inopportunely. Our experience corresponds with that of M. Magendie. We know of more than one individual in whom there is not the slightest vestige of uvula ; yet they taste, chew, and swallow like other persons. d. Deglutition. The act of swallowing, although executed with extreme rapidity, and apparently simple, is the most complicated of the digestive opera- tions, and requires the action of mouth, pharynx and oesophagus. It has been well analyzed by M. Magendie, — first of all in a thesis, main- tained at the Ecole de M&lecine of Paris, in 1808, and subsequently, in his Precis EUmentaire de Physiologie} To facilitate its study, he divides it into three stages. In the first^ the food passes from the mouth into the pharynx ; in the second^ it clears the apertures of the glottis and nasal fossas, and attains the oesophagus; and, in the third^ it clears the oesophagus and enters the stomach. 1. When the food has been sufficiently masticated and imbued with saliva, it is collected by the action of the cheeks and tongue upon the upper surface of the last organ ; — the mass being more or less rounded, and hence usually termed alinierdary bolus. Mastication now stops; the tongue is raised and applied against the bony palate in succession from the tip to the root, and the alimentary bolus, having no other way of escaping from the force pressing it, is directed towards the pharynx. Previous to this, the pendulous veil of the palate had been applied to the base of the tongue. The bolus now raises it to the horizontal posi- tion : the circumflexus palati muscles render the velum tense, so that the food cannot pass into the nasal fosste ; and the muscles that constitute the pillars of the fauces— palato-pharyngei and glosso-staphylini — contribute to this eflect. By this combination of results, the food is impelled into the pharynx. The muscles, which, by their action, apply the tongue to the roof of the mouth and to the velum palati, are the proper muscles of the organ, aided by the mylo-hyoidei. In this first stage of deglutition, the motions are voluntary, except those of the velum palati. The process is not executed with rapidity, and is easily intelligible. Such is not the case with the second stage. The actions in it are complicated, and executed with so much celerity, that they have been re2;arded as a kind of convulsion. 2. The distance over which the bolus has to travel, in the second stage, is trivial ; the rapidity of its course is owing to the larynx or superior aperture of the windpipe, which opens into the pharynx having to be cleared instantaneously, otherwise respiration might be arrested, and serious effects ensue. The mode, in which the second stage is accomplished, is as follows. As soon as the alimentary bolus comes in contact with the pharynx all is activity ; the pharj^nx con- tracts, embraces, and presses the bolus ; and the velum pendulum, drawn down by the palato-pharyngei and glosso-staphylini muscles, » Edit, cit., ii. G3. 136 DIGESTIOX. fulfils a similar office. At the same time, the genio-glossus, by apply- ing the tongue to the palate, from the tip to the roof, raises the os hyoides, the larynx, and, with it, the anterior paries of the pharynx. The same effect is directly induced by the contraction of the mylo- hyoidei, and genio-hyoidei muscles ; which, instead of acting as de- pressors of the lower jaw, as they do during mastication, take the jaw as their fixed point, and are levators of the os hyoides. The larynx is thus elevated, carried forwards, and meets the b6lus to render its passage over the aperture of the larynx shorter, and, therefore, more speedy. To aid this effect, — when we make great efforts to swallow, the head is inclined forwards on the thorax. Whilst the os hyoides and the larynx are raised, they approach each other, — the upper mar- gin of the thyroid cartilage passing behind the body of the hyoid bone: the epiglottic gland is pushed backward, and the epiglottis is depressed, and inclined backwards and downwards, so as to cover the entrance to the lar^mx. The cricoid cartilage executes a rotatory motion on the inferior cornua of the thyroid cartilage, which occasions the entrance of the larynx to become oblique from above to below, and, of course, from before to behind. The bolus thus glides over its surface ; and, forced on by the veil of the palate, and by the constrictors of the pharynx, reaches the oesophagus. At one time, it was universally believed, that the epiglottis is the sole agent in preventing substances from passing into the larynx. The experiments of M. Magendie' have, however, demonstrated, that this is the combined effect of the motions of the larynx just described, and of the muscles, whose office it is to close the glottis; so that, if the laryngeal and recurrent nerves be divided in an animal, and the epiglottis be left in a state of integrity, deglutition is rendered ex- tremely difficult; — the principal cause, that prevented the introduction of aliments into the glottis, having been removed by the section. M. Magendie, and MM. Trousseau and Belloc^ refer to cases of individuals, who were totally devoid of epiglottis, and yet swallowed without any difficulty,^ and Magendie remarks, that if, in laryngeal phthisis with destruction of the epiglottis, deglutition be laboriously and imperfectly accomplished, it is owing to the carious condition of the arytenoid cartilages, and to the lips of the glottis being so much ulcerated as not to be able to close the glottis accurately. Whilst the bolus, then, is passing over the top of the larynx, respiration must be momentarily suspended, owing to closure of the glottis; and if, from distraction of any kind, we attempt to speak, laugh, or breathe, at the moment of deglutition, the glottis opens, the food enters, and cough is excited, which is not appeased until the cause is removed. This is what is called, in common language, " the food going the wrong way." As soon as the bolus has cleared the glottis, the larynx descends, the epi- glottis rises, and the glottis opens to give passage to the air. This is ' Memoire sur I'Usage de I'Epiglotte dans la Deglutition, Paris, 1813; and Precis, &c., i. (57. ^ 2 A Practical Treatise on Lar^-ngeal Phthisis, &c. &c. ; Dr. Warder's translation, p. 84, in Dunglison's American Medical Library, Philad., 1839. * A similar case is given by Targioni, in which neither deglutition nor speech was impaired ; Morgagni, xxviii, 13. DEGLUTITION", 137 owing to the relaxation of the muscles that had previously raised the larynx, and closed the glottis. M. Chaussier thinks, that the sterno- hyoidei muscles now act, and aid in producing the descent of the parts.* The author had an excellent opportunity for noticing the laryngeal phenomena of deglutition in a man, who had cut his throat, and in whom a fistulous opening remained, which permitted the infe- rior ligaments of the larynx to be seen distinctly. The glottis was observed to be firmly closed.* M. Longet,^ who has made experiments connected with this subject on animals, is disposed to think, that the displacements of the base of the tongue and epiglottis are the two most important conditions, and that the closed glottis is only the last obsta- cle set up against the passage of food into the larynx ; but he evi- dently assigns too much importance to the epiglottis. The velum pendulum, then, protects the posterior nares and the orifices of the Eustachian tube from the entrance of tlic food ; and the epiglottis, the elevation of the larynx, with the contraction of the mus- cles that close the glottis, are the great agents in preventing it from passing into the larynx. The whole of this second stage consists of rapid movements, of an entirely involuntary character, which, accord- ing to Bellingeri,'' are under the presidency of the palatine filaments of the fifth pair; but these filaments are sensory; the motor filaments being probably derived from the pneumogastric; or, according to M. Longet, from the spinal.* o. In the third stage, the pharynx, by its contraction, forces the ali- mentary bolus into the oesophagus, so as to somewhat dilate the upper part of the organ. The upper circular fibres are thus excited to action, and force the food onward. In this way, by the successive contraction of the circular fibres, it reaches the stomach. In the up]5er part of the oesophagus, the relaxation of the circular fibres speedily follows their contraction; but this is not the case in the lowest third, the cir- cular fibres remainins; contracted, for some time after the entrance of the bolus into the stomach, — probably to prevent its return into the oesophagus. The passage of the bolus along the oesophagus is by no means rapid. M. Magendie^ affirms, that he was struck, in the prose- cution of his experiments, with the slowness of its progression. At times, it was two or three minutes before reaching the stomach ; at others, it stopped repeatedly, and for some time. Occasionally, it even ascended from the inferior extremity of the oesophagus towards the neck, and subsequently descended again. When any obstacle existed to its entrance into the stomach, this movement was repeated a num- ber of times, before the food was rejected. Every one must have felt the slowness of the progression of the food through the oesophagus when a rather larger morsel than usual has been swallowed. If it stops, we are in the habit of aiding its progress by drinking some fluid, ' Adelon, op. citat., ii. 424. ^ Dunglison's American Medical Intelligencer, Oct., 1841, p. 73. ' L'Examinateur Medical, 17 Oct., 1841; and Brit, and For. Med. Rev., Jan., 1842, p. 228. ' Dissert. Inaugural., Turin, 1823 ; noticed in Ediub. Med. and Surg. Journ. for July, 1834. ' Traite de Physiologie, ii. 337, Paris, 1850. ^ Op. citat., ii. 69. 138 DIGESTION. or by swallowing a piece of bread. Occasionally, however, the pro- bang is necessary to propel it. The pain produced in these cases, according to M. Magendie, is owing to the distension of the nervous filaments, that surround the pectoral portion of the canal. In the case of a female, labouring under a disease which permitted the interior of the stomach to be seen, M. Halle noticed, that whenever a portion of food passed into the stomach, a sort of ring or hourrelet was formed at the cardiac orifice, owing to the mucous membrane of the oeso- phagus being forced into the stomach by the contraction of its circular fibres.' The mucous fluid, pressed out from the different follicles by the passage of the bolus, materially facilitates its progress. Notwithstanding the facility with which deglutition is accomplished, almost every part of it is uninfluenced by volition, being dependent upon organization, and exerted instinctively. If the alimentar}" mat- ter contained in the mouth be not sufficiently masticated ; or if it has not the shape, consistence, and dimensions, it ought to possess; or if the ordinary movements, that precede mastication, have not been executed, — whatever effort we may make, deglutition is impractica- ble. We constantly meet with persons who are unable to swallow the smallest pill; and yet can swallow a much larger mass, if certain preliminary motions be executed, which, in the case of the pill, are inadmissible, in consequence of its being usually of a nauseous character. It appears, that the involuntary parts of the function are excited by the stimulation of the aliment ; for, if we attempt to swal- low the saliva several times in succession, we find after a time, that the act is impracticable, owing to the deficiency of saliva. Every one must have experienced the difficulty of deglutition, when the mouth and fauces were not duly moistened by their secretions. The involuntary part of deglutition is under the control of the reflex system of nerves. An impression is made by the alimentary matters upon the excitor or aflerent nerves, which impression is conveyed to the gray matter of the spinal cord, and in the invertebrata to ganglia corre- sponding to it; whence it is reflected to the muscular fibres tliat have to be thrown into contraction. The portion of the spinal cord, which serves as a centre for the reception of the impression, and the point of departure for the motor influence, is the medulla oblongata; and the experiments of Dr. John Eeid* lead to the inference, that the glosso- pharyngeal, which is chiefly distributed to the mucous surface of the tongue and fauces, is the excitor nerve ; the pharyngeal branches of the pneumogastric, the motors. It would seem, however, that these nerves donot alone possess the function; for after they have been divided, the animal is still capable of imperfect deglutition. The associate excitor or afferent nerves. Dr. Reid concludes to be— the branches of the fifth pair, that are distributed to the fauces, and probably also those of the superior laryngeal distributed to the pharynx: — the associate motor or efferent nerves being branches of the hypoglossal, that are distributed to the muscles of the tongue, and to the sterno-hyoid, sterno-thyroid, and thyro-hyoid muscles ; filaments of the inferior laryngeal that ramify on the larynx ; some of the branches of the fifth pair that supply the ' Op. cit., ii. 70. 2 Ediub. Med. and Surg. Journ., vol. xlix. chymificatio:n'. 139 levator muscles of the lower jaw ; the branches of the portio dura that ramify upon the digastric and stylo-hyoid muscles, and upon the mus- cles of the lower part of the face ; and probably some of the branches of the cervical plexus, which unite themselves to the descendens noni. It must be admitted, however, that this part of the physiology of deglu- tition is obscure.* Some individuals are capable of swallowing air; and, according to M. Magendie,^ it is an art that can be attained by a little practice. He affirms it, indeed, to be a more common power than is usually sup- posed. In 100 students he has generally found eight or ten who pos- sessed it. In the stomach, the air acquires the temperature of the vis- cus, becomes rarefied, and distends the organ ; exciting, in some, a feel- ing of burning heat; in others, an inclination to vomit, or acute pain. He thinks it probable, that its chemical composition undergoes change ; bui;, on this point, nothing certain is known. The time of its stay in the stomach is variable. Commonly, it ascends into the oesophagus, and makes its exit through the mouth or nostrils. At other times, it passes through the pylorus, and diffuses itself through the whole of the intestinal canal, as far as the anus, — distending the abdominal cavity, and simulating tympanites. M. Magendie refers to the case of a young conscript, who feigned the disease in this manner. e. Chymijication. When the food has experienced changes impressed upon it by the preceding process, it reaches the cavity of the stomach, where it is re- tained for several hours, and undergoes another portion of the digestive action, being converted into a pultaceous mass, to which the term chyme has been applied ; whilst the process has been called chymification. It does not seem, that all physiologists have employed these term^in this signification; some have confounded c/iy/e with chyme ; and chyufication with chymification. The former of these processes is distinctly an in- testinal act: the latter is exclusively gastric. The aliment, as it is sent down by repeated efforts of deglutition, descends into the splenic portion of the stomach without difficulty, as regards the first mouthfuls. The stomach is but little compressed by the surrounding viscera, and its parietes readily separate to receive the food; but when it is taken in considerable quantity, the distension gradu- ally becomes more difficult, owing to the compression of the viscera and the distension of the abdominal parietes. The accumulation takes place chiefly in the splenic and middle portions. Dr. Beaumont^ ob- served, that when a piece of food was received into the stomach, the rug^B of the latter gently closed upon it ; and if it were sulffciently fluid, gradually diffused it through the cavity of the organ, but entirely ex- cluded more whilst the action continued. The contraction ceasing, another quantity of food was received in the same manner. It was found, in the subject of his experiments, that when the valvular portion of the stomach, situate at the fistulous aperture, was depressed, and ' Longet, Traite de Physiologie, ii. 334, 837, Paris, 1850. 2 Op. cit., ii. 14G. ' Expei'iiueuts, &c., on tUe Gastric Juice, p. 110. 140 DIGESTIOI!T. solid food introduced, either in large pieces or finely divided, the same gentle contraction or grasping motion, took place, and continued for fifty or eiglity seconds, and it would not allow of another quantity, until that period had elapsed : the valve could then be depressed, and more food put in. When the man was so placed, that the cardia could be seen, and was permitted to swallow a mouthful of food, the same ccm- traction of the stomach and grasping of the bolus were invariably observed to commence at the oesophageal ring. Hence, when food is swallowed too rapidly, irregular contractions of the muscular fibres of the oesophagus and stomach are produced ; the vermicular motions of the rugsa are disturbed, and the regular process of digestion is inter- rupted. Whilst the stomach is undergoing distension by food, it experiences changes in its size, situation, and connexion with the neighbouring organs. The dilatation does not afi'ect its three coats equally. T^lie two lamina3 of the peritoneal coat separate, and permit the stomach to pass farther between them. The muscular coat experiences a true dis- tension ; its fibres lengthen, but still so as to preserve the particular shape of the organ ; whilst the mucous coat yields, in those parts espe- cially where the rugae are numerous; that is, along the great curvature and splenic portion. In place, too, of being flattened at its anterior and posterior surfaces, and occup3dng only the epigastrium, and a part of the left hj'pochondrium, it assumes a rounded figure. Its great cul-de-sac descends into the left hj-pochondre and almost fills it, and the greater curvature descends towards the umbilicus, especially on the left side. The pylorus preserves its position and connexion with the surrounding parts ; — being fixed down by a fold of the peritoneum. It is chiefly forwards, upwards, and to the left side, that the dilatation occurs. The posterior surface cannot dilate on account of the resist- ance of the vertebral column, and of a ligamentous formation which prevents the stomach from pressing on the great vessels behind it. Its cardiac and pyloric portions are also fixed ; so that when it is under- going distension, a movement of rotation takes place, by which the great curvature is directed slightly forwards; the posterior surface inclined downwards, and the superior upwards. A wound received in the epigastric region, will, consequently, penetrate the stomach in a very difierent part, according as the viscus may be, at the time, full or empty. The dilatation of the organ produces changes in the condition of the abdomen and its viscera. The total size of the abdominal cavity is augmented ; the belly becomes prominent ; and the abdominal viscera are compressed, — sometimes so much as to excite a desire to evacuate the contents of the bladder or rectum. The diaphragm is crowded towards the thorax, and is depressed with difficulty; so that, not only is ordinary respiration cramped; but speaking and singing become laborious. When the distension of the organ is pushed to an enormous extent, the parietes of the abdomen may be painfully distended, and the respiration really difficult. It is in these cases of over-distension, that an energetic contraction of the oesophagus is necessary; hence the advantage of the strong muscular arrangement at its lower ])art. In proportion as the food accumulates in the stomach, the sensation of CHTMIFICATIOX. 141 hunger diminishes ; and if we go on swallowing additional portions, it entirely disappears, or is succeeded by nausea and loathing. The quantity, necessary to produce this effect, varies according to the indi- vidual, as well as to the character of the food ; a very luscious article sooner cloying than one that is less so. A due supply of liquid with solid aliment also enables us to prolong the repast with satisfaction. As the stomach, when distended, presses upon the different viscera and upon the abdominal parietes, it is obvious, that it must experience a proportionate reaction. An interesting question consequently arises; — to determine the causes, which oppose the passage of the food back along the oesophagus, as well as through the pylorus, M. Magendie^ found, in his vivisections, that the lower portion of the oesophagus experiences, continuously, an alternate motion of contraction and re- laxation. The contraction begins at the junction of the two upper thirds with the lowest third; and is j^ropagated, with some rapidity, to the termination of the oesophagus in the stomach. Its duration, when once excited, is variable ; the average being, at least, half a minute. When thus contracted, it is hard and elastic, like a cord strongly stretched. The relaxation, that succeeds the contraction, oc- curs suddenly and simultaneously in all the contracted fibres; at times, however, it appears to take place from the upper fibres towards the lower. In the state of relaxation, the oesophagus is remarkably flac- cid ; — forming a singular contrast with that of contraction. This movement of the oesophagus is, according to M. Magendie,^ under the dependence of the eighth pair of nerves. AVhen these nerves were divided in an animal, the oesophagus was no longer contracted. Still it was not relaxed. Its fibres, deprived of nervous influence, were shortened with a certain degree of force ; and the canal remained in a state intermediate between contraction and relaxation. The lower part of the oesophagus of the horse, for an extent of eight or ten inches, is not contractile in the manner of muscles. M. Magen- die^ found, when the eighth pair of nerves was irritated, or the parts were exposed to the galvanic stimulns, that no contraction was pro- duced. The oesophagus of that animal is, however, highly elastic; and its lower extremity is kept so strongly closed, that for a long time after death, it is difficult to introduce the finger; and considerable pressure is required to force air into it. M. Magendie considers this arrange- ment to be the true reason, why horses vomit with such difficulty as to occasionally rupture the stomach by their efforts. The alternate mo- tions of the oesophagus, which we have described, oppose the return of the food from the stomach. The more the organ is distended, the more intense and prolonged is the contraction, and the shorter the relaxation. The contraction commonly coincides with inspiration; the time at which the stomach is, of course, most strongly compressed. The relaxation is synchronous with expiration. The pylorus prevents the alimentary mass from passing into the duodenum. In living animals, whether the stomach be filled or empty, this aperture is constantly closed by the constriction of its fibrous ring, and the contraction of its circular fibres ; and, so accurately is it closed, ' Precis, ent has proved that such augmented secretion actually occurs. If an animal be kept fasting for some time, and then be made to swallow dry food, or even stones, and be deprived of liquid aliment, the substances swallowed will be found, — on killing it some time after- wards, — surrounded by a considerable quantity of fluid. Such is not the case with animals killed after fasting. The stomach then contains no fluid matter. The augmented secretion in the former case must, therefore, be owing to the presence of dry food in the stomach. That it is not simply the fluid passed down by deglutition, — the salivary and mucous secretions, for example, — is proved by the fact, that the same thing occurs when the oesophagus has been tied. Besides, if the sto- mach of a living animal be opened, and any stimulating substance be applied to its inner surface, a secretion is seen to issue in considerable quantity at the points of contact; and, again, if an animal be made to swallow small pieces of sponge, attached to a thread hanging out of the mouth, by means of which they can be withdrawn, they become filled with the fluids secreted by the stomach, and, on withdrawing them, a sufficient quantity can be obtained for analysis. Such experiments have been repeatedly performed by MM. Reaumur,^ Spallanzani,^ and others. In Dr. Beaumont's case^ the collection of gastric secretion was obtained by inserting an elastic gum tube through the opening: in a short time fluid enough was secreted to flow through the tube. This admixture with the fluids of the mucous membrane of the stomach, and the secretions continually sent down from the mouth by the efforts of deglutition, is the only apparent change witnessed for some time after the reception of solid food. Sooner or later, according to circumstances, the pyloric portion of the organ contracts, sending into the splenic por- tion the food it contains : to the contraction dilatation succeeds ; and this alternation of movements goes on during the whole of digestion. After this time chyme only is found in the pyloric portion mixed with a small quantity of unaltered food. This motion of contraction and relaxation has been called j^eristole; and it appears, at first, to be limited to the pyloric portion, but gradually extends to the body and splenic portion, so that, ultimately, the whole stomach participates in it. It consists in an alternate contraction and relaxation of the circular fibres; and the gentle oscillation, thus produced, not only facilitates the admix- ture of the food with the gastric secretions, but continually exposes fresh portions to their action. The experiments of Bichat satisfied him, that the peristole is more marked, the greater the fulness of the stomach. He made dogs swallow forced-meat balls, in the centre of which he placed cartilage, and found, that when the stomach was greatly charged, the cartilages were pressed out of the balls. This did not hap- pen, when the organ contained a smaller quantity of food. ' Memoir, de I'Acad. pour 1752. * Exper. sur la Digestion, Geneve, 1783. ' Experiments, &c., ou the Gastric Juice, p. 106. 144 DIGESTION. The ordinary course and direction of the revolutions of tlie food, according to Dr. Beaumont/ are as follows: — The bolus, as it enters the cardia, turns to the left; passes the aperture; descends into the splenic extremity, and follows the great curvature towards the pyloric end. It then returns in the course of the lesser curvature, and makes its appearance again at the aperture in its descent into the great curva- ture to perform similar revolutions. That these are the revolutions of the contents of the stomach, he ascertained by identifying particular portions of food; and by the fact, that when the bulb of the thermo- meter was introduced during chymification, the stem invariably indi- cated the same movements. Each revolution is completed in from one to three minutes, and the motions are slower at first than when chymi- fication has made considerable progress. In addition to these move- ments, the stomach is subjected to more or less succussion from the neighbouring organs. At each inspiration it is pressed upon by the diaphragm; and the large arterial trunks in its vicinity, as well as the arteries distributed over it, subject it to constant agitation. It has been already remarked, that t\\e peristaltic or vermicular action — j)eristole — of the stomach, — and the action extends likewise to the intestines, — is effected by the muscular coat of the organ. It is, how- ever, an involuntary contraction, and appears to be little influenced by the nervous system ; continuing, for instance, after the division of the eighth pair of nerves; becoming more active, according to ]\[. Magen- die,^ as animals are more debilitated, and even at death ; and persisting after the alimentary canal has been removed from the body. MM, Tiedemann and Gmelin,^ however, affirm, that by irritating the plexus of the eighth pair of nerves situate around the oesophagus with the point of a scalpel, or touching it with alcohol, the peristole of both stomach and intestines can be constantly excited; and Valentin and Dr. John Reid state, that distinct movements may be excited in the stomach by irritating the pneumogastric. This involuntary function, as well as that exerted by the heart and other involuntary organs, affords us a striking instance of the little nervous influence, which seems to be requisite for carrying on many of those functions that have to be exe- cuted independently of volition through the whole course of existence; and which appear to be excited at times, in a reflex manner, by the presence of appropriate excitants; — of food, in the case of the peri- staltic action of the stomach ; of blood, in that of the heart, &c. ; and yet may be carried on in the absence of all nervous influence, as in the cases of the intestinal canal, and the heart, which may contract for a long time after they have been removed from the body. In the intes- tinal canal, the movements are doubtless influenced by the spinal cord, probably through the sympathetic by means of the fibres which the canal derives from it; but although influenced by the spinal cord, they are not dependent upon it for contractility. As Dr. Carpenter has remarked, the canal is enabled to propel its contents by its inherent powers ; but — as in other instances — the nervous centres exert a gene- ral control over even the organic functions, "doubtless for the purpose ' Op. citat., p. 110. 2 Precis Elementaire, ii. 20. 3 Die Verdauung, u. s.w., or Frencli edit., Recherches sur la Digestion, Paris, 1S27. CHYMIFICATIO]^. 145 of liarraonizing them witli eacli otlier, and witli the conditions of tlie organs of animal life."^ The gentle, oscillatory or vermicular motion of the stomach, and the admixture with the fluids, secreted by its internal membrane, as well as by the different follicles, &c., in the supra-diaphragmatic portion of the alimentary canal, are probably the main agents in the digestion operated in the stomach. Much contrariety of sentiment has existed regarding the precise organs that secrete the fluid which oozes out as soon as food is placed in contact with the mucous coat of the stomach. Whilst some believe it to be exhaled from that membrane; others conceive it to be secreted by the numerous follicles, seated in the membrane as well as in that of the lower portion of the oesophagus; or by what have been termed gastric glands. The analogy of many animals, especially of birds, would render the last opinion the most probable. In them we find, in the second stomach, the cardiac or gastric glands largely developed ; and it is probable that they are the great agents of the secretion of the digestive fluid. (See Figs. 28 and 29.) MM. Tiedemann and Gmelin^ affirm, that the more liquid portion of the gastric fluid is exhaled, and that the thicker, more ropy and mucous portion is secreted by the fol- licles. Rudolphi^ assigns it a double origin; — from exhalants, and gastric glands; whilst MM. Leuret and Lassaigne^ ascribe its formation exclusively to the villi. The views of Bernard and Kolliker have been given before.* Dr. Beaumont,^ who had an excellent opportunity for experimenting on this matter, remarks, that on applying aliment, or any irritant, to the internal coat of the stomach, and observing the effect through a magnifying-glass, innumerable minute, lucid points, and very fine pa- pilke, could be seen protruding, from which a pure, limpid, colourless, slightly viscid fluid distilled, which was invariably and distinctly acid. On applying the tongue to the mucous coat in its empty, unirritated state of the stomach, no acid taste could be perceived. Although no apertures were perceptible in the papillae, even with the assistance of the best microscope that could be obtained, the points, whence the fluid issued, were clearly indicated by the gradual appearance of innumer- able very fine, lucid specks, rising through the transparent mucous coat, and seeming to burst, and discharge themselves upon the very points of the papillas, diffusing a limpid, thin fluid over the whole interior gastric surface. A like difference of opinion has prevailed regarding the chemical character of the fluids; and this has partly arisen from the difficulty of obtaining them identical. The true fluid secreted by the gastric follicles or mucous membrane can never, of course, be obtained for examination in a state of purity- It must always be mixed not only with the other secretions of the stomach, but with all those transmitted to the organ, by the constant efforts of deglutition. It is, consequently, to this mixed fluid that the term gastric juice has really been applied; ' Human Physiology, p. 151, Lond.,1842. ^ Op. citot. ' Grundriss der Physiologie, 2ter Band, 2te Abtlieilung, s. iii., Berlin, 1828. * Reclierchos surla Digestion, Paris, 1825. * Page 83. ^ Op. citat.,p. 103. VOL. I.— 10 1-16 DIGESTION. althougli it is more especially appropriated to the particular fluid, pre- sumed to be secreted by the stomach, and to be the great agent in diges- tion. To the nature of the gastric juice and its effects in the process of digestion, we shall have occasion to recur presently. It is probably owing to the quantity of fluid secreted by the stomach, that it is so largely supplied with bloodvessels; and that the mucous membrane is more injected, during the presence of food in the organ. Experiments, by Sir Benjamin Brodie^ and others, would seem to show, that the secretion is under the influence of the eighth pair of nerves. Having administered arsenic to difterent animals — on some of which he had divided these nerves, — he found, that, whilst the stomachs of those, in Avhich the nerves were entire, contained a large quantity of a thin, mucous fluid; in those, whose nerves were divided, the organ was inflamed and dry. Leuret and Lassaigne,'^ however, affirm, that divi- sion of the nerves had no influence on the secretion. But more of this presently. Before entering into the views of different physiologists on chymifi- cation, — in other words, into the theories of digestion, — it will be well to refer to the physical and chemical properties of the chyme. Whether the changes in the food be simply physical or chemical, or whether the first stage of animalization be eflected within the stomach, will be a topic for future inquiry. Chyme is a soft, homogeneous substance, of grayish colour and acid taste. Such are its most common characters: it varies, however, according to the food taken, as may be observed, by feeding animals on difierent simple alimentary substances, and killing them during digestion. This ditierence in its properties accounts for the discrepancy observable in the accounts of writers. The change wrought on aliments is, doubtless, of a chemical nature; but the new play of aflinities is controlled by circumstances inappreciable to us. In the case of a female patient at the hospital La Gharite, of Paris, who had been gored by a bull, and had a fistulous opening in the sto- mach, the fopd, during its conversion into chyme, appeared to have acquired an increase of its gelatin ; a greater proportion of chloride of sodium; phosphate of soda and phosphate of lime ; and a substance, in appearance, fibrinous.-'' It has been said, again, that the food becomes decarbonized and more nitrogenized ; that the carbon which disappears is removed by the oxy- gen of the air swallowed with the food, or by that contained in the food itself; and that the nitrogen proceeds from the secretions of the sto- mach, or predominates simply because the food is decarbonized. M. Adelon-* has properly remarked, that the fact and the explanation are here equally hypothetical. Generally, the chyme possesses acid pro- perties. MM. de Montegre,^ Magendie,'^ and Tiedemann and Gmelin,^ always observed it to be so. Haller* and Marcet found it to be neither acid nor alkaline. In the chyme examined by the latter gentleman, he detected albumen, an animal matter, and some salts, difi'ering, however, ' Philos. Trans, for 1S14., 2 Op. citat. 3 Richerand's Nouveaux Elemens de Physiologic, edit. 13eme, par Berard, aine, p. 72, Bruxelles, 1837. * Physiol, de rHomme, &c., edit, cit., torn. ii. 5 Experiences sur la Digestion, Paris, 1824. 6 Op. citat., ii. p. 87. 7 Op. cit. 8 Element. Physiol., xix. 1. CHYMIFICATIOX. 147 slightly, according as it proceeded from animal or vegetable food. In the latter case, it aflbrded four times as much carbon as in the former, but less saline matter; and this consisted of lime and an alkaline chlo- ride. MM. Leuret and Lassaigne^ analyzed the chyme from the sto- mach of an epileptic, who died suddenly in a fit, five or six hours after having eaten. It was of a white, slightly-yellowish colour; and strong, disagreeable taste. On analysis, it afforded a free acid, — the lactic ; a white, crystalline, slightly saccharine matter, analogous to the sugar of milk; albumen, soluble in water; a yellowish, fatty, acid matter, ana- logous to rancid butter; an animal matter, soluble in water, having all the properties of casein ; and a little chloride of sodium, phosphate of soda, and much phosphate of lime. Dr. Prout^ affirms, that a quantity of chlorohydric acid is present in the stomach during the process of digestion. He detected it in that of the rabbit, hare, horse, calf, and dog, and in the sour matter ejected by persons labouring under indi- gestion : — a fact which has been confirmed by Mr. Children. MM. Tiedemann and Gmelin, and Dr. Beaumont,^ affirm, that the secretion of acid commences, as soon as the stomach receives the stimulus of a foreign body, and that it consists of chlorohydric and acetic acids. The experiments of these gentlemen were not confined to the chymous mass obtained from digestible food. They examined the fluids, secreted by the mucous membrane when indigestible substances were sent into the stomach, and the acid character was equally manifested. These ex- periments, consequently, remove an objection, made by Dr. Bostock,"* regarding the detection of the chlorohydric acid by Dr. Prout; — that, as there did not appear to be any evidence of the existence of this acid before the introduction of food into the stomach, it might rather be inferred, that it is, in some way or other, developed during the process of digestion. In all Dr. Beaumont's experiments, the chyme was in- variably and distinct!}^ acid. The principal theories on chymification have been the following :* — 1. Coction^ or elixation. — This originated with Hippocrates, and was vaguely used by him to signify the maceration, and maturation expe- rienced by the food in the stomach. The doctrine was embraced by Galen and, others, Avho ascribed to the organ, an attracting, retaining, concocting, and expelling quality effected by heat.* In proof of this, they affirmed that the heat of the stomach is increased during chymi- fication ; that the process is more rapid in the warm, than cold-blooded animal; that it is aided by artificial heat, and continues even after death, if care be taken to keep up the heat of the body; that in the experi- ments on artificial digestion made by Spallanzani, heat was always necessary, and the greater the degree of heat the more easy and com- plete the digestion. It is hardly necessary to say that the heat of the stomach is totally insufficient to excite any coction or ebullition in the physical sense of ' Eecherches, &c., p. 114. * Philos. Trans, for 1824; and Bridgewater Treatise on Chemistry, &c., Amer. edit., *p. 268, Philad., 1834. ^ On the (lastric Juice, &c., p. 105. " Physiology, 3d edit., p. 569, Lend., 1836. * For different theories, ancient and modern, on chymification, see Berand, Manuel de Physiologie, p. 130, Paris, 1853. •• Boerhaav., Piselectiones Academ. Not. Adv., §86, torn, i.. Gutting., 1740-1743. 148 DIGESTION". tlie term, and this applies ])articularly to tlie cold-blooded animal, wliicli must digest, if not witli the same, with due, rapidity. 2. Putrefaction. — The next great hypothesis was that oi putrefaction, which, we are informed by Celsus,' was embraced by Plistonicus, a dis- ciple of Praxagoras of Cos, who flourished upwards of three hundred years before the birth of Christ. Of late, it has had no advocates, but appears to have been the view embraced by Cheselden,^ The reasons, urged in favour of it, have been; — the putrescible character of the ma- terials employed as food; the favourable circumstances of a heat of 98° or 100°, and of moisture; and, by some, the foetor of the excre- ments. The objections are, 1. That when the contents of the stomach are rejected, during chymification, they exhibit no evidence of putridity. 2. That in all the experiments, which have been made on the compara- tive digestibility of different substances, Avhen it has been necessary to kill the animals at different stages of the digestive process, there has not been the slightest sign of putrefaction. 8. That opportunities fre- quently occur for v/itnessing ravenous fishes and reptiles with an ani- mal or portion of an animal, — too large to be entirely swallowed, — partly in the stomach, and the remainder in the gullet and mouth. In these cases, where the food has remained in this situation some days, the part contained in the throat has been found putrid, whilst that in the stomach has been entirely sweet ; and lastly, in Spallanzani's and other experiments, to be detailed presently, it was found, when food, in a state of putridity, was taken into the stomach, or mixed with the gastric juice out of the stomach, that it recovered its sweetness. It has been already observed, that it is the custom, in some countries, to eat the gilier or game in a state of incipient putrefaction; jet the breath is not tainted by it. 3. Trituration. — The mathematical phj'siologists, — Borelli,^ Hecquet,^ Megallotti,^ Pitcairne,^ and others, — after the example of Erisistratus,^ attempted to refer the whole process of digestion to trituration, imagin- ing, that the food is subjected in the stomach to an action similar to that of the pestle and mortar of the apothecary, or of the millstone; and that the chyle is formed like an emulsion. The most plausible arguments, in favour of this view of the subject, are drawn from the presumed analogy of the granivorous bird, whose stomach is capable of exerting an astonishing degree of pressure on substances submitted to it. There is no analogy, however, between the human stomach, and the gizzard of birds. The latter is a masticatory organ, and therefore possessed of the surprising powers which we have elsewhere described; whilst mastication, in man, is accomplished by distinct organs. No comparison can be instituted between the gentle oscillatory motion of the stomach, and the forcible compression exerted by the digastric muscle of the gizzard. The simple introduction of the finger through a wound of the abdomen has shown, that the compression exerted by ' De Medicina, cura E. Milligan, edit. 2da, p. 5, Edinb., 1831. 2 Anatomy of the Human Body, &c., 8tli edit., p. 155, Lend., 17C3. * De Motu Animalium; Addit. J. Bernouillii, M. D., Medit. Math.em. MusciiL, Lusd. Bat., 1710. * Traite de la Digestion, Paris, 1710. 5 Haller, Elem. Physiol., six. 5. 6 Works, &c., Lond., 1715. '• Cels., loc. citat. CHYMIFICATIOX. 14:9 it on its contents is totally insufficient to bruise any resisting substance. Moreover, we constantly see fruits, — as raisins and currants, — passing through the whole intestinal canal unchanged ; whilst worms remain in the stomach — reside there — unhurt; and, we shall see presently, that the experiments of Eeaumur and Spallanzani proved most con- vincingly, that digestion is effected independently of all pressure. The futility, indeed, of this mode of viewing the sulDJect is signally illus- trated by the fact, that, whilst Pitcairne estimated the power of the muscular fibres of the stomach at 12,951 pounds. Hales' thought that twenty pounds would come _ nearer the truth; and Astruc^ valued its compressive force at five ounces ! 4. Fermentation. — The system of fermentation had many partisans; amongst whom may be mentioned Van Helmont,^ Sylvius,'* Willis,^ Boyle,^ Grew,^ Charleton,^ Lower,^ Easpail,^" &c. Digestion, in this view, was ascribed to the chemical reaction of the elements of the food during their stay in the stomach; — the action being excited by food that had already undergone digestion, or by a leaven secreted for the purpose by the stomach itself. In favour of this view, it was attempted to show, that air is constantly generated in the organ, and that an acid is always produced as the result of fermentation, — the formation of chyme being referred by the greater number of physiologists to the food undergoing the vinous and acetous fermentations. The objections to this doctrine of fermentation are; — that digestion ought to be totally independent of the stomach, except as regards temperature; and the food ought to be converted into chyme, exactly in the same manner, — if it were reduced to the same consistence, and placed in the same tem- perature, — out of the body ; which is not found to be the case. Bones are speedily reduced to chyme in the stomach of the dog, although they would remain unchanged for weeks, in the same temperature, out of the body. The facts of the voracious fishes before mentioned like- wise prove the insufiiciency of the hypothesis; according to which, digestion ought to be accomplished as effectually in the oesophagus as in the stomach. Yet it is found that, whilst the portion in the stomach is digested, the other may be unaltered, or be putrid. The truth is; — in healthy digestion, fermentation, in the ordinary acceptation of the term, does not occur; and, Avhenever the elements of the food react upon each other, it is an evidence of imperfect digestion ; hence, fer- mentation is one of the most common signs of dj^spepsia. 5. Chemical solution. — The theory of chemical solution, jDroposed by Spallanzani," and subjected to modifications, has met with more favour from physiologists than any of the others that have been mentioned, and may be regarded as established. According to that observer, • statical Essays, ii. 174, 4th edit,, Lond., 1769. ^ Traite de la Cause de la Digestion, &c., Toulouse, 1714; and Haller, loc. citat. ' Ortus Medicinae, &c., Amstel., 1G48. * Opera, Genev., 1781. ' Diatribae duse Medico-Pliilosopliicte, &c., Lond., 1659. ® Works, vol. ii., Lond., 1772. ^ Comp. Anat. of the Stomach, kc, Lond., 1681. * CEcou. Anim. Exerc. 2. ^ Tractatus de Corde, &c., Amstel., 1G71. '° Chimie Organique, p. 356, Paris, 1833. " Dissertations relative to the Natural History of Animals and Vegetables: sect, i., Lond., 1789. 150 DIGESTION. chymKication is owing to the solvent action of a fluid, secreted by the stomach, which accumulates in that viscus between meals and during hunger,^ and acts as a true menstruum on the substances exposed to it. This fluid, — to which he gave the name gastric juice^ — he affirmed to be peculiar in each animal, according to its kind of alimentation, — corresponding, as regards its energy, with the rest of the digestive apparatus, and differing in its source in the series of animals; in some, proceeding from the follicles of the oesophagus; in others from those of the stomach; but always identical in the same animal; generally transparent, yellowish ; of a saline taste; bitter; slightly volatile; and stronger in animals with a membranous than in those with a muscular stomach, and than in ruminant animals. To obtain tbe juice, Spallan- zani opened animals, after they had been made to fast for a time; and collected the juice that had accumulated in their stomachs; or he made them swallow tubes pierced with holes, and filled with small sponges. By withdrawing these tubes, by means of a thread attached to them and suffered to hang out of the mouth, and expressing the sponges, he obtained the fluid in quantity sufficient for examination. To determine ■whether this fluid, obtained from fasting animals, was destined to chy- mify the food, he tried the following experiments. He caused numerous animals to swallow tubes filled Avith food, but pierced with holes, so that the juices of the stomach might be able to get into their interior; and-fouud that chymification was effected, when he had taken the pre- caution to chew the substances before they were pitt into the tubes, or to triturate them; and the process was alwa3^s more readily accom- plished, the more easy the access of the fluids. On repeating these experiments on animals of various kinds, with a muscular or mem- branous, and musculo-membranous stomach ; on pullets, turkeys, ducks, pigeons, rooks, frogs, salamanders, eels, serpents, sheep, cats, &c., he obtained the same results; and hence he affirmed, that trituration can- not be the essence of chymification. Eeaumur,^ — originally a believer in the doctrine of trituration, — had previously arrived at the same con- clusion, by experiments of a similar kind. Spallanzani next repeated those experiments upon himself. Having well chewed different articles of food, he enclosed them in wooden tubes pierced with holes, and swallowed them ; but, as the tubes caused pain in the bowels, he sub- stituted small bags of linen. The substances contained in bags were digested without the bags being torn; a fact, which proved, that diges- tion must have been accomplished by means of a fluid, that penetrated them. In 1777, Dr. Stevens^ repeated these experiments. He made a person swallow balls of metal, filled with masticated food, and pierced with holes: when the balls were voided, — thirty-six or fortj^-eight hours afterwards, — they were entirely empty. Lastly. — Spallanzani was de- sirous of seeing whether this solvent juice could effect digestion out of the body. He put ^ome Avell-raasticated food in small glass tubes, and mixed gastric juice with it. These tubes he placed in his axilla, in order that they might be exposed to the same degree of heat as in the ' It has been already stated, that the experiments of Dr, Beaumont have satisfac- torily proved that no such accumulation takes place during hunger. 2 Memoir, de I'Acad. pour 1752. ^ De Alimentorum Concoctione, § 24 CHYMIFICATION". 151 stomacli ; and in the space of fifteen hours, or of two clays, — more or less, — the substances appeared to be converted into chyme. In these experiments he found it important to employ gastric juice, that had not been previously used, and to have a sufficient quantity of it. From all these experiments, Spallanzani conceived it to be demon- strated, that chymification is a true chemical solution; and he endea- voured to deduce from them the degree of digestibility of different alimentary substances. Similar experiments were instituted by Dr. Beaumont.' In all cases, solution occurred as perfectly in the artificial as in the real digestions, but they were longer in being accomplished, for reasons which appear sufficient to explain the difference. In the former, the gastric secretion is not continuous; the temperature cannot be as accurately maintained, and there is an absence of those gentle motions of the stomach, wliich are manifestly so useful in accomplish- ing real digestion. With regard to the precise nature of the gastric juice of Spallanzani, we have already observed that great contrariety of sentiment has pre- vailed; and that, in ordinary cases, it is impracticable to procure it unmixed with the other secretions of the dia-estive mucous membrane. Spallanzani affirmed, that the only properties he detected in it, were, — a slightly salt, bitterish taste; it was neither acid nor alkaline. Gosse^ found it vary according to the nature of the animal, — whether herbi- vorous or carnivorous; — and to be always acid in the former. Dyimas^ held the same sentiments, and maintained, from experiments on dogs, that it was acid or alkaline, according as the animal' had fed on vege- table or animal diet. He declared it, moreover, to be mawkish, thick, and viscid. Viridet* and others affirmed that it was always acid. Mr. Ilunter^ was not inclined to suppose, that there is any acid in the gas- tric juice as a component or essential part of it, "although an acid is very commonly discovered even when no vegetable matter has been introduced into the stomach." Scopoli^ analyzed the gastric juice of the rook, and found it to consist of water, gelatin, a saponaceous matter, muriate of ammonia, and phosphate of lime. Carminati^ describes it as salt, bitter, and frequently acid; and MM. Macquart^ and Yauquelin,' in the gastric juice of the ruminant animal, found albumen and fi-ee phosphoric acid.'° All these analyses were made on the mixed fluid, to which the term gastric juice has been applied. That such a mixed fluid does exist in the stomach at the time of chymification, and is largely concerned in the process, is proved by the facts already men- tioned, as well as by the following. M. Magendie" asserts, that one of his pupils — M. Pinel — could procure, in a short time after swallowing a little water or solid food, as much as half a pint. M. Pinel "pos- ' Op. citat., p. 139. * Experiences sur la Digestion, §81, Genev., 17S3. * Principes de Pliysiologie, Paris, 1806. * Tractatus Novus de Prima Coctione, &c., Genev., 1G91. * Observations on Certain Parts of the Animal Econoniv, with Notes by Prof. Owen, Amer. edit., p. 134, Philad., 1840. ^ In Spallanzani, § 244. ' Ricerche suUa Natura, &c., del Succo Gastrico, Milano, 1785 ; or Journal Phys., t. xxiv. ^ * Mem. de la Societe de Med., Paris, 1786. ^ Fourcroy, Elem. de Cliim., torn. iv. '° See Burdach, Die Pliysiologie als Erfahrungswissenschaft, v. 240 und 431, Leipzitr, 1835. ^ " Precis, &c., ii. 11. 152 DIGESTION. sessed the faculty of vomiting at pleasure." In tliis wa}^, he obtained from his stomach, in the morning, about three ounces of fluid, which was analyzed by M. Thdnard, who found it composed of a considerable quantity of water, a little mucus, and salts with a base of soda and lime ; but it was not sensibly acid, either to the tongue or to reagents. On another occasion, M. Pinel obtained two ounces of fluid in the same manner. This was analyzed by ]M. Chevreul, and found to contain much water, a considerable quantity of mucus, lactic acid — united to an animal matter, soluble in water, and insoluble in alcohol, — a little muriate of ammonia, chloride of potassium, and some chloride of sodium. Messrs. Tiedemann and Gmelin^ procured the gastric fluid by making animals, that had fasted, swallow indigestible substances, as flints. It always appeared to them to be produced in greater quantity, and to have a more acid character, in proportion as the alimentary matter was less digestible and less soluble ; and they assign it, as constituents, — chlorohydric acid ; acetic acid ; mucus ; no, or very little, albumen ; salivary matter; osmazome; chloride of sodium, and sulphate of soda. In the ashes, remaining after incineration, were, carbonate, phosphate, and sulphate of lime, and chloride of calcium. MM. Leuret and Las- saigne^ assign its composition, in one hundred parts, to be, — water, ninety-eight; lactic acid; muriate of ammonia; chloride of sodium; animal matter soluble in water ; mucus ; and phosphate of lime, two parts. M. Braconnot' examined the gastric juice of a dog, and found it to contain — free chlorohydric acid in great abundance ; muriate of ammonia; chloride of sodium in very great quantity; chloride of cal- cium; a trace of chloride of potassium; chloride of iron; chloride of magnesium; colourless oil of an acid taste; animal matter soluble in water and alcohol, in very considerable quantity; animal matter solu- ble in weak acids ; animal matter soluble in water, and insoluble in dlcohoi {salivary matter of Gmelin); mucus; and phosphate of lime. In the winter of 1832-3, the author was favoured by Dr. Beaumont,"* with a quantity of the gastric secretion obtained from the individual with the fistulous opening into the stomach, which was examined by himself, and his friend, the late Professor Emmet, of the University of Virginia, and found to contain free chlorohydric and acetic acids, phosphates, and chlorides, with bases of potassa, soda, magnesia, and lime, and an animal matter — probably pe/^sm — soluble in cold water, but insoluble in hot. The quantity of free chlorohydric acid was sur- j^rising : on distilling the fluid, the acids passed over, the salts and animal matter remaining in the retort: the amount of chloride of sil- ver thrown down on the addition of the nitrate of silver to the dis- tilled fluid, was astonishing. The author had many opportunities for examining the gastric secretion obtained from the case in question. At all times, when pure or unmixed except with a portion of the mucus of the lining membrane of the digestive tube, it was a transparent fluid, having a marked smell of chlorohydric acid; and of a slightly 1 Op. cit. 2 Recherc]ies,cS:c., Paris, 1825. s Journal de Chimie Medicale, torn, ii., ser. 2, 1S36, and Records of General Science, Jan., 1836. * See a letter from the author to Pr. Beaumont, in Beaumont's Experiments, &c., on the Gastric Juice, p. 77 ; and the author's Elements of Hygiene, p. 21G, Philad., 1835. CHYMIFICATIO:^-. 153 salt, and very perceptibly acid, taste. It matters not, therefore, that M. Blondlot,^ in his experiments on the gastric secretions of dogs and other animals, obtained by artificial fistulous openings made into the stomach, did not find, when distilled, that they exhibited any acid reaction, whilst the residue in the retort was always strongly acid. The results referred to by the author as regards the gastric juice of man were positive and uniform ; and established, that it always con- tains a large quantity of chlorohydric acid. Moreover, free chlorohydric acid was found in the gastric juice of animals by Enderlin,^ Hiibbenet,^ and Bidder and Schmidt.'* Funke' is of opinion that their researches leave no doubt on the subject of its presence ; and Dr. Brinton," after an inquiry into the whole matter, thinks " there seems little doubt that we ought to regard the balance of evidence as inclining decisively towards a single gastric acid," and that acid the chlorohydric. Schmidt is of opinion, that the essential gastric acid is the chlorohj^dric, and believes it to be a conjugated acid in union with pepsin — chloro-pepso-hydric acid — chlorj^epsimcosserstoff'- sdure; — the existence of which is hypothetical.'' More recently, Griinewaldt^ has had an opportunity of instituting a variet}^ of expe- riments in a case of fistulous opening into the stomach of a woman. Three analyses of the fluid obtained were made by Schmidt, who found the mean to be as follows : — Water 90.44 Solid residue . . . . . . . . . . 0.5(5 Ferment, &c 0.32 Inorganic constituents . . . • . . . . 0.24 Chloroliydric acid .......... 0.02 Chloride of potassium . . . . . . . . 0.06 " of sodium ........ 0.15 " of calcium 0.006 Phosphate of lime, magnesia, and iron . . . . . 0.013 From this analysis it is manifest, that the proportion of water is very great. It would seem, indeed, that an enormous amount of fluid is secreted from the stomach in the twenty-four hours. It has been attempted to estimate the amount by that of the albuminous matter known to be dissolved by it; but all calculations thus made must be vague and uncertain. Certain aliments are known to occasion a more copious secretion of the gastric solvent than others; and those nitro- genized substances which remain longest in the stomach will require ' Traite Analytique de la Digestion, Paris, 1844. An abstract of his views is given by Mr. Pa^et, Brit, and For. Med. Rev., Jan., 1845, p. 270 ; see, also, Gazette Medicale de Paris, 1851, No. 33, p. 526. 2 Canstatt, Jahresbericht, 1843, i. 149. ' Disquisitiones de Succo Gastrico, Dorp. Liv. 1850: and Canstatt, op. cit., 1851, s. 97, and 1852, s. 109. * Die Verdauungsafte und der Stoffwechsel, s. 46, Mitau und Leipzig, 1852. ^ Rudolph Wagner's Lehrbuch der Speciellen Physiologie, von D. Otto Funke, s. 163, Leipz., 1854. ' Art. Stomach and Intestines in Cyclop, of Anat. and Physiol., Pt. 46, p. 332, June, 1855. ' Moleschott, Physiologie des StofFwechsels, u. s.w.,s. 428, Erlangen, 1851 ; and Leh- mann, Lehrbuch der Physiologisch. Chemie, iii. 330, Leipz., 1852. * Succi Gastrici Huniani Indoles, &c., Dorpat, 1853 ; Vierordt's Archiv. fiir Physiol. Ileilkund. xiii. 459 ; and Canstatt, 1854, i. 145, Wtirzburg, 1855. Griiucwaldt found free chlorohydric acid in smaller proportion in man than in animals. 154 DIGESTION". a greater amount of fluid. Lelimanu^ estimates the daily quantity in man to be al)out four pounds; whilst Bidder and Schmidt,^ founding their deductions on experiments on dogs with gastric fistulce, infer that in that animal as much as one-tenth of its weight is daily secreted ; and Griinewaldt,' from his experiments on the woman with the gastric fistula, was led to infer that the secretion amounts to the enormous quantity of from one-fifth to one-quarter of the weight of the body daily ! Of course, a large amount of this fluid passes again into the circulation along with the products of digestion that are dissolved in it."* Still, the amount is so vast, it is difficult to imagine that there is not some error in the observation, or fallacy in the deductions. After this it seems unnecessary to examine into the statement of M. Blondlot, that the true and almost only source of the acidit}^ of healthy gastric fluid is the presence of acid phosphate salts. If, at least, we admit this to be the case in animals, it is assuredly not so in man. The remark applies equally to the experiments of i)r. K. D. Thomp- son on the gastric secretions of the sheep and pig.^ By these ob- servers, the results obtained from the examination of the gastric secre- tions in man, seem to have been passed over, and they have deduced their inferences from those of animals, which may, in part — but in part only — account for the great discrepancy in their statements.*^ The source of the chlorine or chlorohydric acid in the gastric juice, as Dr. Prout^ suggests, must be the common salt existing in the blood, which, he conceives, is decomposed by galvanic action : the soda, set free, remaining in the blood, a portion being " requisite to preserve the weak alkaline condition essential to the fluidity of the blood;" but the larger part being directed to the liver to unite with the bile. This is plausible; but, it need scarcely be added, not the less hypothetical. Drs. Purkinje and Pappenheim^ are of a similar opinion in regard to the source of the chlorohydric acid. From their galvanic experiments they think it follows, that the juices mixed with the food in the natu- ral way, saliva, mucus, the portions of chloride of sodium present therein, and still more the gastric raucous membrane itself, develope as much as is required : and that if the nervous action in the stomach be either identical w^ith, or analogous to, galvanism, it would be suffi- cient to account for the secretion of the quantity of chlorohydric acid requisite for digestion, without the assumption of a special organ of secretion.^ M, Blondlot'" denies — and Liebig'^ formerly did likewise — that in ' Lelirbaclx der Physiologischen Chemie, ii. 49, and iii. 330, 342, Leipz., 1852, or Translation by Dr. Day, Anier. edit, by Dr. R. E. Rogers, i. 448 and ii. 520, Pliilad., 1855. '^ Op. cit., s. 36. 3 Op. cit. * See on the Gastric Juice and its office in Digestion, Dalton, Amer. Journ. of the Med. Sciences, Oct., 1854, p. 317. ° Ranking's Abstract, vol. i., Pt. 2, Amer. edit., p. 271, New York, 1846. ^ Carpenter, Principles of Physiology, 4th Amer. edit., p. 494. Philad., 1850 ; and Kirkes and Paget, Manual of Physiology, 2d Amer. edit., p. 170, Philadelphia, 1853. ' Bridgewater Treatise, Amer. edit.,"!). 268, Philad., 1834. ^ Miiller's Archiv. fiir Anatomic, u. s. w. Heft 1, 1838, noticed in Brit, and For. Med. Eev., Oct., 1838, p. 529. ^ See also Dr. Brinton, loc. cit. 'O Op. cit. " Animal Chemistry, Gregory's and Webster's edit., p. 107, Cambridge, 1S42. CHYMIFICATIOISr. 155 healtli lactic acid exists in the stomach. In certain diseases, accord- ing to the latter, both it and mucilage are formed from the starch, and sugar of the food ; and he affirms, that the property possessed by these substances of passing, by contact with animal substances, in a state of decomposition, into lactic acid, has induced physiologists without far- ther inquiry, to assume that lactic acid is produced during digestion. lie now, however, admits its existence in health,' and Avith Dr. R. D. Thompson, MM. Bernard and Barreswil, Frerichs,^ J. Beclard,* and others, consider it to be an important agent in the digestive process. "With some other chemists, he denies the existence of free chloro- hydric acid in the stomach, and believes, that when it is obtained by the simple distillation of the gastric juice it is formed by the reaction of the lactic and phosphoric acids, which are present in the fluid, on the chlorides; and Lehmann'* found, when he experimented on the stomachs of dogs placed in vacuo in such a manner as to cause the vapours from the gastric juice to pass through a tube containing a so- . lution of nitrate of silver, that there was no indication of free chloro- hydric acid until the fluid had become so concentrated as to permit the action of the lactic acid on the earthy chlorides. His results would tend to confirm the later conclusions of Liebig, as well as those of MM. Bernard and Barreswil, and others, as to the nature of the acid of the gastric juice of certain animals at least.^ It is proper to remark, however, that neither Prout nor Braconnot could detect lactic acid in the gastric juice; and, moreover, it does not appear to be formed in artificial digestion ." The diversity of results obtained by chemical analysis; the difficulty of comprehending how the same fluid can digest substances of such opposite character; and the uncertainty we are in, regarding the organs concerned in its production, had led some physiologists to doubt the existence of any such gastric juice or solvent as that described by Spal- lanzani. M. Montegre,^ for example, in the year 1812, presented to the French Institute a series of experiments, from which he concluded, that the gastric juice of Spallanzani is nothing more than saliva, either in a pure state, or changed by the chymifying action of the stomach and become acid. As M. Monti^gre was able to vomit at pleasure, he obtained the gastric juice, as it had been done by previous experi- menters, in this manner, whilst fasting. He found it frothy, slightly viscid, and turbid; depositing, when at rest, some mucous flakes; and commonly acid ; so much so, indeed, as to irritate the throat, and render the teeth rough. He was desirous of proving, whether this fluid was in any manner inservient to chymification. For this purpose, he began ' Chemistry of Food, London, 1847. 2 CanstaU, Jahresbericht, 1850, Bd. i. s. 134. ' Traite Elementaire de Physiologie, p. 8(j, Paris, 1855. * Lelirbuch der Physiologischen Chemie, ii. 42, Leipz., 1852, or Amer. edit, of Dr. Day's translation by Dr. Robt. E. Rogers, i. 441, Philad. 1855. * Archiv. der Pharmacie, cited in the British and Foreign Medico-Chirurgical Re- view, p. 261, Jan., 1849. ^ A full account of the various views in regard to the gastric acid is given by Fre- richs, Art. Verdauung, Wagner's Handworterbuch der Physiologie, 21ste Lieferung, s. 780, Braunschweig, 1849 ; a"nd Berard, Cours de Physiologie, lie Livraisou, p. 97, Paris, 1849. ■^ Exper. sur la Digestion, p. 20, Paris, 1824. 156 DIGESTION". by ejecting as mneli as possible by vomiting; and, afterwards, swallowed magnesia to neutralize what remained. On eating afterwards, tlie food did not appear less cliymified, nor was it less acid; whence he con- cluded, that, instead of the fluid being the agent of chymification, it was nothing more than saliva and the mucous secretions of the stomach, changed by the chymifying action of that viscus. To confirm himself in this view, he repeated with it, Spallanzani's experiments on artificial digestion; making, at the same time, similar experiments with saliva: the results were the same in both cases. When gastric juice, not acid, was put into a tube, and placed in the axilla, — as in Spallanzani's ex- periments, — in twelve hours it was in a complete state of putrefaction. The same occurred to saliva placed in the axilla. Gastric juice, in an acid state, placed there, did not become putrid, but this seemed to be owing to its acidit}^ ; for the same thing happened to saliva, when ren- dered acid by the addition of a little vinegar ; and even to the gastric juice, — used in the experiment just referred to, — when mixed with a little vinegar. Again: — he attempted artificial digestion with the gas- tric juice, acid and not acid ; fresh and old; but they were unsuccessful. The food alwaj^s became putrid ; but sooner when the juice em^^loyed was not acid ; and, if it sometimes liquefied before becoming putrid, this was attributed to the acidity of the juice, as the same efl'ect took place, when saliva, mixed with a little vinegar, was employed. M. Montegre, moreover, observed, that the food rejected from the stomach was longer in becoming putrid, in proportion to the time it had been subjected to the chymiiying action of the stomach; and he concluded, that the fluid, which is sometimes contained in the empty stomach, instead of being a menstruum kept in reserve for chymification, is nothing more than the saliva continually sent down into that viscus, and that its purity or acidity depends upon the chymifying action of the stomach.' As regards the fluid met with in the stomach of fasting animals, M. Montegre's remarks may be true in the main; but we have too many evidences in favour of the chemical action of some secretion from the stomac-h during digestion to permit us to doubt the fact for a moment. Besides, some of M. Montegre's experiments have been re- peated with opposite results.- MM. Leuret and Lassaigne,^ and Dr. Beaumont^ performed those relating to digestion after the manner of Spallanzani, and succeeded perfectly; whilst they failed altogether in producing chymification with saliva, either in its pure state, or when acidulated with vinegar. By steeping the mucous membrane of an animal's stomach in an acid liquor, a solution is obtained, to which Eberle"* gave the name pepsin. This solution has the property of dissolving organic matter in a much higher degree than diluted acids. It dissolves coagulated albumen, muscular fibre, and animal matters in general. In an experi- ment, one grain of the digestive matter dissolved one hundred grains of coagulated white of egg. Eberle thought that all mucus has the ' Chaussior and Adelon, in Diet, des Sci. Medicales, xx. 422. * Reclierclies sur la Digestion, Paris, 1825. " Op. citat., p. 139. * Phjsiologie der Verdauung nach Versuclien, ii. s. w., Wiirzburg, 1834; Miiller, Axchiv., Heft 1, 183t), or Loudou Lancet, p. 19, Marcli 31, 1838. CHYMIFICATIOX. 157 property, when acidulated, of inducing decomposition and subsequent solution of tlie food; but it would appear, that no other mucus than that of the gastric raucous membrane, when acidulated, possesses it,^ and, consequently, that there must be a peculiar substance, j^ejjsin or gastric ferment, which may be regarded as a true digestive principle.^ This principle was not obtained by Schwann in a pure state; but M. Wasmann^ would appear to have succeeded better. A solution, con- taining only 5 Olio P^^'^ ^^ pepsin and slightly acidulated, is said to dis- solve the white of an egg in six or eight hours,'' It is not generally considered, however, to be a distinct substance — an immediate prin- ciple; but rather to be the product of an alteration of the nitrogenized matters of the parietes of the stomach/ An artificial digestive fluid is sometimes made which resembles that of the human stomach, by macerating in water portions of fresh or dried mucous membrane of the stomach of a pig or other omnivor- ous animal, or of the fourth stomach of the calf, and adding to the infusion a few drops of chlorohydric acid, about 3.3 grains to half an ounce of the mixture according to Schwann. Portions of food placed in this fluid, and the mixture kept at a temperature of about 100°, are softened and changed, much in the same manner as they would be in the stomach.^ Even were the evidence adduced less positive in favour of the exist- ence of some gastric secretion concerned in the digestive changes in that organ, the following phenomena would be overwhelming. Be- sides the fact of the most various and firm substances being reduced to chyme in the stomach, we find the secretions from its lining mem- brane possessing the power of coagulating albuminous fluids. It is upon the coagulating property of these secretions, that the method of making cheese is dependent. Eennet, employed for this purpose, is an infusion of the digestive stomach of the calf, which, on being added to milk, converts the albuminous portion into curd; and it is surprising how small a quantity is necessary to produce this effect. Messrs. For- dyce^ and Young,^ of Edinburgh, found that six or seven grains of the inner coat of a calf's stomach, infused in water, afforded a liquid, which coagulated more than one hundred ounces of milk, — that is, more than six thousand eight hundred and fifty-seven times its own weight; and yet its weight was probably but little diminished. The substance that possesses this property does not appear to be very solu- ble in water; for the inside of a calf's stomach, after having been steeped in water for six hours, and well washed, still furnishes a liquor or infusion, which coagulates milk. Liebig^ has denied, that the fresh ' Mi'iller, Elements of Physiology, by Baly, pp. 518 and 542, London, 1838. * Miiller and Schwann, in Milller's Archiv., Heft 1, 1836 ; and Miiller, op. citat. 3 Journ. de Pharmacie ; and American Journal of Pharmacy, for Oct., 1840, ]). 192. < Graham's Elements of Chemistry, Amer. edit., p. 695, Philad., 1843, and Tliomson's Animal Chemistry, p. 229, Edinb., 1843. * Robin and Verdeil, Traite de Chiniie Anatomique, &c., iii. 555, Paris, 1853; and Becquerel and Rodier, Traite de Chimie Pathologique, p. 470, Paris, 1853. * Kirkes and Paget, Manual of Physiology, 2d Amer. edit., p. 173, Philad., 1853. ' A Treatise on the Digestion of Food, p. 57, 2d edit., Lond., 1791. ^ Thomson's System of Chemistry, 6tli edit., iv. 596. ' 3 Animal Chemistry, Webster's Amer. edit., Cambridge, 1842. 158 DIGESTION. lining membrane of the stomacli of the calf, digested in weak chloro- hydric acid, gives to that fluid the power of dissolving boiled flesh or coagulated white of egg; but Dr. Pereira' affirms, that he has found, by experiment, that a digestive liquor can be prepared from the fresh Tindried stomach of a cfilf. This had, indeed, been shown on the best authority long ago. Mr. Hunter, for example, made numerous expe- riments upon the coagulating power of the secretions of the stomach, which show, that it is found in the stomachs of animals of very differ- ent classes. The lining of the fourth stomach of the calf is in com- mon use, in a dried state, for the purpose mentioned above; and it has been proved, that every part of the membrane possesses the same pro- perty. Mr. Hunter found, by experiment, that the mucus of the fourth cavity of a slink calf, made into a solution with a small quantity of water, had the power of coagulating milk ; but that found in the three first cavities possessed no such power. The former, even after it had been kept several days, and was beginning to be putrid, re- tained the property. The duodenum and jejunum, with their contents, likewise coagulated milk ; but the process was so slow as to give rise to the suggestion, that it might have occurred independently of the intestines employed for the purpose. He found, that the inner mem- brane of the fourth cavity in the calf, when old enough to be killed for veal, had t1ie same property. Portions of the cuticular, of the massy glandular part, and of the portion near the pylorus of the boar's stomach, being prepared as rennet, it was found, that no part had the effect of producing coagulation but that near the pylorus, whei'e the gastric glands of the animal are especially conspicuous. The crop and gizzard of a cock were salted, dried, and afterwards steeped in water. The solution, thus obtained, was added to milk : the portion of the crop coagulated it in two hours; that of the gizzard in half an hour. The contents of a shark's stomach and duodenum coagulated it instantaneously. Pieces of the stomach were washed clean, and steeped in water for sixteen hours. The solution coagulated milk immediately. Pieces of the duodenum produced the same effect. When the milk was heated to 96°, the coagulation took place in half an hour; when cold, in an hour and a quarter. The stomachs of the salmon and thornback, made into rennet, coagulated milk in four or five hours. But those experiments of Mr. Hunter do not inform us of the par- ticular secretions that are productive of the effect. They would, indeed, rather seem to show, that it is a general property of the whole internal membrane. To discover the exact seat of the secretion, and especially whether it be not in the gastric glands. Sir Everard Home^ selected those of the turkey ; which, from their size, are better adapted for such an experiment than those of any other bird, except the ostrich. A young turkey was kept a day without food, and then killed. The gastric glands were carefully dissected separately from the lining of the cardiac cavity; cutting off the duct of each before it pierced the membrane, so that no part but the glands themselves were removed. ' Treatise on Food and Diet, Ainer. edit., p. 36, New York, 1843. 2 Lectures on Comparative Anatomy, i. 299, Lond., 1814, and iii. 134, Lond., 1823. J CHYMIFICATIOX. 159 Forty grains, by weight, of these glands were added to two ounces of new milk ; and similar experiments were made with rennet ; with the lining of the cardiac cavity of the turkey ; and with the inner mem- brane of the fourth cavity \)f the calf's stomach. Coagulation and separation into curds and whey were first effected by the rennet. Next to this, and simultaneously, came the gastric glands, and the fresh stomach of the calf; and lastly, the cardiac membrane of the turkey. From these experiments. Sir Everard concluded, that the power of coagulation is in the secretion of the gastric glands; and that the power is communicated to other parts, by their becoming more or less impregnated with it. The marginal figure, copied from an engraving of the microscopic observations of Mr. Bauer, exhibits the gastric glands — as he regarded them — of the human oesophagus magnified fifteen times. These glands are in the lining of the lower part of the oesophagus'; and have the ap- pearance of infundibular cells, whose depth does not exceed the thickness of the membrane. This structure, although differ- ent from that of the gas- tric glands of birds, is a nearer approach to it than is to be met with in any part of the inner surface of the stomach or duode- num. It also resembles them, in the secretion which it produces coagu- lating milk, whilst none of the inspissated juices, met with in these cavities, according to Sir Everard, affect milk in the same way. Erom these facts, he thinks, there can be no longer any doubt entertained, that the gastric glands have the same situation respecting the cavity of the stomach as in birds. No histologist, however, agrees with him in this location of the gastric glands. In some experiments, undertaken by M. J. E. Simon^ with a view to determine, whether the stomach of the child possesses the same properties of coagulating milk as that of the calf, he found that cow's milk was not coagulated by it, but that, when a quantity of the colos- trum of the mother of a child, which died when five days old, was obtained, and a piece of calf's stomach was introduced into it, the milk coagulated. Another property, manifestly possessed by the secretion in question, is that of preventing putrefaction, or of obviating it in substances ex- posed to its action. Mont^gre and Thackrah^ deny it this property, but there can be no doubt of its existence. Spallanzani, Eordyce, and Gastric Glands of tho Oesophagus magnified fifteen times. ' Mailer's Archiv., Heft 1, 1839, cited in Brit, and For. Med. Rev., Oct., 1839, p. 549. ^ Lectures on Digestion and Diet, p. 14, Lond., 1824. 160 DIGESTION. others, liave ascertained, that in those animals wliich frequentl}^ take their food in a half putrid state, the first operation of the stomach is to disinfect, or remove the factor from the aliment received into it. We have already alluded to many facts elucidative of this power. Helm of Vienna,' in the case of a female who had a fistulous opening in her stomach, observed, that substances which were swallow^ed in a state of acidity or putridity, sooft lost those qualities in the stomach ; and the same power of resistuig and obviating putrefaction has been exhibited in experiments made out of the body. Nothing could be more unequivocal, as regards the possession of this property by the gastric fluid, than the experiments of Dr. Beaumont and the author,* with the secretion obtained from the subject of his varied investigations. In the presence of the author's friend, N. P. Trist, Esq. — then consul of the United States at Havana, — the odour of putrid food was as speedily removed by it as by chlorinated soda employed at the same time on other portions. The explanation of this property, as well as that of coagulation, has been a stumbling-block to the chemical phy- siologist. "We can only say concerning it," says Dr. Bostock,^ "that it is a chemical operation, the nature of which, and the successive steps by which it is produced, we find it difiicult to explain ; at the same time, that we have very little, in the way of analogy, which can assist us in referring it to any more general principle, or to any of the estab- lished laws of chemical affinity." The cases of what are termed digestion of the stomach after death afford us, likewise, remarkable examples of the presence of some powerful agent in the stomach; as well as of the resistance to chemical action, offered hj living organs. Powerful as the action of the gastric juice may be, in dissolving alimentary substances, it does not exert it upon the coats of the stomach during life. Being endowed with vitality, they effectually resist it. But when that viscus has lost its vitality, its parietes yield to the chemical power of the contained juices, and become softened, and, in part, destroyed. Mr. Hunter^ found the lining membrane of the stomach destroyed, in several parts, in 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. Since Hunter's time, numerous examples have occurred, and been recorded by Messrs. Baillie, Allan Burns, Haviland, Grimaud, Pascalis, Cheese- man, J. B. Beck, Chaussier, Yelloly, Gardner, Treviranus, Godecke, Jager, Carswell, and others.* The fact is of importance in medical jurisprudence; and, until a better acquaintance with the subject, would, doubtless, have been set down as strong corroborative evidence in cases ' Rudolplii, Griinclriss der Physiologie, 2er Band, 2te Abtheil., s. 114, Berlin, 1828. 2 See the author's Elements of Hygiene, p. 216, Philad., 1835. 3 Edit, cit.it., p. 571. * Phil. Transact., Ixii. ; and Observations on certain parts of the Animal Economy, with notes by Prof. Owen, Amer. edit., p. 144, Philad., 1840. * Beck's Medical Jurisprudence, 6th edit., ii. 311, Albany, 1838 ; Carswell's Path. Anat., No. 5, Loud., 1833; and T. Wilkinson King, Guy's Hospital Reports, vii. 139, Lond., 1842 ; and a case communicated to the author by Dr. Thomas M. Flint, in which the stomach had separated from the oesophagus, recorded in Med. Examiner, p. 715, for December, 1848 ; also, Dr. George Budd, on the Organic Diseases and Functional lOis- ' orders of the Stomach, Amer. edit., p. 19, Philad., 1856. CHYMIFICA.TION. 161 of suspected poisoning. It is now established that solution of the sto- mach may take place after death, without there being reason for sup- posing that any thing noxious had been swallowed. The experiments of Dr. Wilson Philip' and Sir Robert CarswelP are corroborative of this physiological action of the gastric juice. On opening the abdomen of rabbits, that had been killed immediately after having eaten, and allowed to lie undisturbed for some time before examination, the former found the great end of the stomach soft, eaten through, and sometimes altogether consumed; the chyme being covered only by the peritoneal coat, or lying quite bare for the space of an inch and a half in diameter: and, in this last case, a part of the contiguous intestines was also destroyed ; whilst the cabbage, which the animal had just taken, lay in the centre of the stomach unchanged, if we ex- cept the alteration that 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. Why the perforation takes place, without the food being digested, is thus explained by Dr. Philip. Soon after death, the motions of the stomach, which are constantly carrying on the most digested food towards the pylorus, cease. The food, that lies next to the surface of the stomach, thus becomes fully saturated with gastric fluid; neutralizes no more; and no new food being pre- sented to the fluid it acts on the stomach itself, now deprived of life, and equally subjected to its action with other dead animal matter. It is extremely remarkable, however, that the gastric fluid of the rab- bit, which, in its natural state, refuses animal food, should so completely digest the stomach, as not to leave a trace of the parts acted upon. Dr. Philip remarks, that he has never seen the stomach eaten through except at the larger end ; but, in other parts, the external membrane has been injured. Mr. A. Burns,^ however, affirms, that in several instances he found the forepart of the stomach perforated about an inch from the pylorus, and midway between the smaller and larger curvatures. From all these facts, then, we are justified in concluding, that the food in the stomach is subjected to the action of secretions, which alter its properties, and are the principal agents in converting it into chyme. But many physiologists, whilst they admit, that the change efl'ected in the stomach is of a chemical character, contend, that the nature of the action is unlike what takes place in any other chemical process, and is, therefore, necessarily organic and vital^ and appertaining to vital chemistry. Such are the sentiments of Messrs. Fordyce,"* Broussais,* Chaussier, and Adelon,^ and others. Dr. Prout suggests, that the sto- mach must have, within certain limits, the power of organizing and vitalizing the different alimentary substances ; so as to render them fit for being brought into more intimate union with a living body, than ' Treatise on Indigestion, Lond., 1821. ^ Ibid, and Edinb. Med. and Surg. Journal, Oct.. 1830; and art. Perforation of the Hollow Viscera, in Cyclopaedia of Practical Medicine, P. xvi. p. 272, Loud., 1833. ' Edinb. Med. and Surg. Journal, vi. 132. * On the Digestion of Food, 2d edit., Lond., 1791. * Traite de Physiologie, &c., translated by I)rs. Bell and La Roche, p. 323. * Diet, des Sciences Medicales, ix. VOL. I.— 11 162 DIGESTION. tlie crude aliments can be supposed to be. It is impossible, he con- ceives, to imagine, that this organizing agency of tlie stomach can be chemical. It is vital, and its nature completely unknown. The physi- ologist should not, however, have recourse to this explanation, until every other has failed him. It is, in truth, another method of expressing his ignorance, when he afl&rms, that any function is executed in an or- ganic or vital manner; nor is this mode of explaining the conversion of the aliment into chyme necessary; the secretion of the matters that are tlie great agents of chymification is doubtless vital; but when once secreted, the changes, effected upon the food, are probably unmodified by any vital interference, except what occurs from temperature, agita- tion, &c., which can only be regarded as auxiliaries in the function. It is in this way, that digestion is influenced by the nervous system. The effect of the diflerent emotions on the digestive function is often evinced, and has already been alluded to ; but the importance of the nervous influence to it has been elucidated, in an interesting manner to the physiologist, of late years chiefly. Baglivi,^ having tied the nerves of the eighth pair on dogs, found that they were ai&cted with nausea and vomiting, and obstinately refused food. Since Baglivi's time, the same results have been obtained by many physiologists. M. De Blain- ville, having repeated the operation on pigeons, found the vetch in their crops entirely unchanged, and chymification totally prevented. Legal- lois,^ Sir Benjamin Brodie,^ Messrs. Philip," Dupuy, Clarke Abel, Hast- ings,^ and others — on carefully repeating the experiments — announced, that, after this operation, the digestive process was entirely suspended.* The result of these experiments was, however, contested by several physiologists of eminence, who affirmed, that, after the division of the eighth pair, digestion continued nearly in the natural state, or, at most, was only slightly impeded. Mr, Broughton^ asserted, that he had made the section on eleven rabbits, one dog, and two horses ; and that diges- tion was not destroyed. M. Magendie^ expresses his belief, that the arrest of chymification, where it Avas observed, was owing to the dis- turbance of respiration caused by the division of the nerves; and he states that digestion continued when care was taken to cut the nerve within the thorax, lower down than the part which furnishes the pul- monary branch. MM. Leuret and Lassaigne assert,^ that they found chymification continue, notwithstanding the division of these nerves; and Dr. G. C. Holland'" thinks he has proved, that the suspension of the digestive function is not produced by the influence of the nerves being withdrawn from the stomach, but by the disturbance of the circulatory system; for when the natural conditions of this system were maintained, after the division of the nerves, the function of digestion still continued to be properly performed; showing that the nervous connexion between ' Opera Omnia, Lngd. Bat., 1745. 2 Sur le Principe de la Vie, p. 214, Paris, 1842. s Pliil. Trans, for 1814. * Experimental Inquiry, &c., Lond., 1817. ^ Journal of Science and Arts, vii. ix. x. xi. and xii. 6 Ley, in App. to Laryngismus Stridulus, p. 447, Lond., 1836. ' Ibid., X. 292. 8 prgcis, &c., ii. 102. ' Edinburgh Med. and Surg. Journal, sciii. 305 ; and Reoterches sur la Digestion, Paris, 1825. '" Inquiry into tlie Principles, &c., of Medicine, i. 444, Lond., 1834. CHYMIFICATION. 163 , the brain and stomach is not essential to the process of digestion, the secretion of the gastric solvent, or the possession of contractility by the muscular fibres of the stomach. In opposition to these experiments, those of M. Dupuytren may be adduced. He divided, separately, the portions of the eighth distributed to the pulmonary, circulatory, and digestive apparatuses, and always found, when the section was made below the pulmonary plexus, that chymification was suspended. But how are we to explain the discre- pancy between these results, and those of Messrs. Broughton and Ma- gendie? M. Adelon' has supposed, that as the eighth pair is not the only nerve distributed to the stomach, — the great sympathetic sending numerous filaments to it, — these filaments, in the experiments of Messrs. Broughton and Magendie, might have been sufficient to keep up for some time the chymifying action of the stomach ; and, again, he sug- gests, whether the nervous influence may not have still persisted for a time after the section of the nerve, like other nervous influences, which, he conceives, continue for some time even after death ; and, lastly, he thinks it probable, that, in the cases in which chymification continued, the experiment was badly performed. Most of these reasons, however, would apply with as much force to the experiments on the other side of the question. Why were not the agency of the great sympathetic, and the continuance of the nervous influence for some time after the section of the nerve, evidenced in the experiments of Dupuytren, Wil- son Philip, Hastings, and others? More recent experiments by Messrs. Wilson Philip,^ Breschet, Milne Edwards, and Yavasseur,^ have shown, that the mere division of the nerves, and even the retraction of the divided extremities for the space of one-fourth of an inch, does not prevent the influence from being transmitted along them to the stomach ; but that if a portion of the nerve be actually removed, or the ends folded back, chymification is wholly or partly suspended.'' Most of the experimenters agree with Sir Benjamin Brodie in the opinion, that chymification is suspended owing to the secretion of the gastric juice having been arrested by the division of the nerves under whose presidency it is accomplished. MM. Breschet and Milne Edwards, however, conceive, that the efifect is owing to paralysis of the muscular fibres of the stomach produced by the section of the nerves ; in consequence of which the different por- tions of the alimentary mass are not brought properly into contact with the coats of the stomach, so as to be exposed to the action of its secretions ; and they affirm, that when the galvanic influence is made to pass along the part of the nerve attached to the stomach, its effect is to restore the due action of the fibres ; and, that a mechanical irri- tant, applied to the lower end of the divided nerves, produces a similar kind of change on the food in the organ; from which they 'conclude, that the use of the ^ar vagum, as connected with the functions of the stomach, is to bring the alimentary mass into necessaiy contact with the gastric secretions. These experiments were repeated in London by ' Physiologie de I'Homme, &c., 2de edit., vol. ii., Paris, 1829. * Philos. Transact, for 1822. » Archives Geiierales de Med., Aout, 1823. * Ware, North. American Medical and Surgical Journal, I'hilad., lb2S. .164 DIGESTION. Mr. Cutler, under the inspection of Dr. Philip and Sir B. Brodie; but the effects of mechanical irritation of the lower part of the divided nerve did not correspond with those observed by MM. Breschet and Milne Edwards.^ The experiments of F. Arnold,^ and of MM. Bouchardat and San- dras,^ led them also to infer, that the nerves of the stomach appear to influence chvmification in so far as the process depends upon the various motions of the organ. M. Longet^ has endeavoured to reconcile these discordant results. Having opened many dogs, he ascertained, that in the greater number, irritation of the pneumogastric nerves induced contraction of the stomach. Frequently, during his experiments, he saw the stomach assume the hour-glass form. In a few dogs, the movements of the stomach, on the irritation of the nerve, were scarcely perceptible. After repeating his experiments on fort}' dogs, he recognized that the differ- ence in the results obtained depended on the condition of the stomach itself. Thus, if the animal was opened when it was full, irritation of the pneumogastric nerves caused manifest movement; but, when empty, scarcely any was excited : the movements, in fact, were feeble in pro- portion to the time that had elapsed from the period of chymification, or of filling the stomach. M. Longet thinks, that these facts account for the different results arrived at by experimentalists in regard to the influence of the pneumogastric nerves over the movements of the stomach ; for, if the same experiments were made when the stomach was in different states, they might readily lead to opposite conclusions. He was never able to excite any movement of the coats of the stomach, by irritating or galvanizing the filaments of the great sympathetic or the semilunar ganglia. On the whole, the proposition of Dr. Philip, — that if the eighth pair be divided in such a manner as to effectually intercept the passage of the nervous influence, digestion is suspended, — is generall}'^ considered to be established; although it must, we think, be admitted with Mr. Mayo,* that the rationale of the subject remains involved in great un- certainty. Like other secretions, that of the gastric juice, although capable of being modified by the nervous influence, cannot be regarded as immediately dependent upon it. The secretion, of the true acid cha- racter and solvent powers, is not always checked by the section of the nerves, and the experiments of Dr. John Peid^ and others have suffi- ciently shown, that the integrity of those nerves is not a condition absolutely necessary for secretion in the stomach, whilst at the same time they prove, that the amount of secretions usually poured into the interior of that organ may be modified in an important manner by causes * Bostock's Physiology, 3d edit., p. .'523, London, 1836. * Lelirbuch der Physiologic des Menschon, Zurich, 1836-7 > noticed in British and Foreign Medical Review for Oct., 1839, p. 478. * Annuaire de Therapeutiqiie, pour 1848, p. 283, Paris, 1848. * Comptes Rendus, Fevr., 1842. See, also, Bischolf, in Miillers Archiv., Berlin, 1843, and Prof. E. Weber, art. Muskelbewegung, in Wagner's Handworterbuch der Physio- logie, 15te Lieferung, s. 41, Braunschweig, 1846. ° Outlines of Human Physiology, 4th edit., p. 122, Lond., 1837. ^ Edinb. Med. and Surg. Journal, April, 1839 ; and art. Par Vagum, in Cyclop, of Anat. and Physiol., pt. xxviii. p. 899, Lond., April, 1847. CHYMIFICATION. 165 acting through those nerves.^ It is denied, however, by Professor J. Miiller, that galvanism has any influence in re-establishing the gastric secretion, when it has been checked by their division. Finally: — Dr. Philip found, that every diminution of the nervous influence, — the section of the medulla spinalis at the inferior part, for example, — deprives the stomach of its digestive faculty ; and MM. Edwards and Vavasseur obtained the same result by the removal of a certain portion of the hemispheres of the brain, or by the injection of opium into the veins in sufficient quantity to throw the animal into deep coma. Much must, of course, be dependent on the deranging influence of the experiments. By means of the fistulous openings into the stomachs of dogs, first instituted by M. Blondlot, (see page 153,) M. Bernard^ undertook fresh experiments on this unsettled topic. A dog's digestion was watched for eight days, and found to be well accomplished. On the ninth day, after twenty-four hours' fast, M. Bernard sponged out the stomach, which contracted on the contact of the sponge, and at once secreted a large quantity of gastric fluid. He then divided the pneumogastric nerves in the middle of the neck, and immediately the mucous membrane, which had been turgid, became pale, as if exanguious ; the movements of the stomach ceased ; the secretion of gastric fluid was instantaneously arrested, and a quantity of neutral ropy mucus was soon produced in its place. After this, digestion was not duly performed; milk was no longer coagulated ; raw meat remained unchanged; and the food, consisting of meat, milk, bread, and sugar, which the dog had before thoroughly digested, remained for a long time neutral, and at length acquired acidity only from its transforma- tion into lactic acid. In the stomachs of other dogs, after the division of the nerves, he traced the transformation of cane sugar into grape sugar in three or four hours ; and in ten or twelve hours, the trans- formation into lactic acid was complete. In others, when the food was not capable of an acid transformation, it remained neutral to the last. In no case did any part of the food pass through the peculiar changes of chymification. More recently, MM. Bouchardat and Sandras,^ from the results of a series of experiments instituted by them, believe they have established, that stomachal digestion and the movements of the organ are interrupted by the simultaneous section of both pneumogas- trics on a level with the larynx ; and farther, that intestinal digestion, and the production and absorption of a very laudable chyle persist notwithstanding such section; and M. Longet^ concludes, that the sec- tion of the pneumogastrics seriously affects chymification, chiefly by paralysing the proper movements of the stomach, but partly by dimi- nishing the secretion of the gastric solvent ; and Professor Berard,* after examining the different experiments and inferences of preceding inquirers, infers: — that "the mixed cords of the pneumogastrics and the branches furnished by the great sympathetic to the stomach beneath * Longet, Traite de Physiologie, ii. 330, Paris, 1850. * Gazette Medicale de Paris, 1 Juin, 1844. ' Bouchardat, Aimuaire de Therapeutique, de Matiere Medicale, &c., pour 1848, p. 306, Paris, 1848. f ^ ' . . i- > i' * Traite de Pliysiologie, ii. 340, Paris, 1850. ' Cours de Pliysiologie, 12o livraisou, p. 235, Paris, 1849. 166 DIGESTION. the diapTiragm, contribute to the maintenance of tlie contractility of the stomach and the secretion of the gastric jnice. A greater share, however, ought to be assigned to the cords of the pneumogastric than to the sub-diaphragmatic branches of the great sympathetic. More- over, the motor influence of the pneumogastric appears to predominate over the secretory ; in other words, the resection of the nerve paralyses the movements more than it diminishes the secretion." The experiments of Professor Bouley,' of Alfort, exhibit, that the results of dividing the pneumogastric nerves are very different in dif- ferent animals. In the horse, for example, but little absorption is effected from the mucous membrane of the stomach, whilst in the dog the contrary is the case; hence, if the pneumogastric nerves be tied in the former animal, a solution of nux vomica is retained in the stomach Tinabsorbed; whilst if they were entire, it would be sent on rapidly into the small intestine, and be immediately absorbed. In the dog, the same toxical agent, on the other hand, rapidly destroys, whether the pneumo- gastric nerves be tied or not, — because the lining membrane of the sto- mach of the dog rapidly absorbs. The experiments of Prof. Bouley were repeated by Prof Bcrard, and with identical results. It is proper, also, to remark, that there are certain toxical agents, which are not absorbed by the mucous membrane of the stomach when the nerves are entire. This appears to be the case with the curare, which can be swallowed with impunity. It has been supposed, that this is owing to some change produced in it by the gastric secretions; but such would not seem to be the case, as the poison, if digested for 24 or 48 hours in gastric juice, is as virulent as ever; and such appears to be the fact when the various intestinal secretions are added to it. The experi- ments of M^[. Bernard and Pelouze^ exhibit, that the gastro-enteric mucous membrane refuses the passage of the curare under such cir- cumstances, even when the experiment is made with a portion of the dead membrane adapted to an endosmometer. Such, too, appears to be the fact with other mucous membranes, except the pulmonary. If the poison be applied to it, absorption takes place in the same manner as when it is placed in the subcutaneous areolar tissue. "We can thus comprehend an experiment made by Professor Bernard, who gave to each of two dogs, on one of which he had divided the pneu- mogastric nerves, a dose of emulsin; and, half an hour afterwards, one of amygdalin; which are inert when taken alone, but, by mixture, pro- duce hydrocyanic acid. The dog whose nerves were cut, died in a quarter of an hour; the emulsin having been detained in the stomach until the amygdalin reached it. In the other, the emulsin was removed by absorption, so that no hydrocyanic acid could be formed when the amygdalin was taken.^ It is proper to remark, however, that the results of these distinguished observers do not exactly accord with those of Prof Brainard, of Chicago, on curare furnished to him ; and the active principle of which he believed to be the venom of serpents. Its effects ' Archives Generales de Medeoine, Juillet, 1S52, p. 357. 2 L'Union Medicale, 1850, No. 125 ; aud Brit, arrd For. Med.-Chir. Rev., April, 1851, p. 532. 3 Frericlis, art. Verdaming, in Wagner's Handworterbucli der Physiologie, S. 658, Ster Baud, Iste Abth., Braunschweig, 1846. CHYMIFICATION. 167 on animals were strikingly like those cansed by tlie venom of tlie rattlesnake, and in many cases no difference could be perceived be- tween tbem. He found, too, that like the venom of serpents it was innocuous when taken into the stomach, "except, perhaps, when used in very large quantities, or in circumstances very peculiar. This is not the case with any known vegetable poison." Dr. Brainard adds, that "it is now well known, that the poison employed by the North American Indians for their arrows is that of the rattlesnake,"^ He affirms, moreover, that the curare or woorara poison may be taken into the stomach "and absorbed without any ill effects." If this be the case, some change must be produced in the venom before or during absorption. Dr. Brainard agrees, that the gastric juice has no power over it — "at least, that there is no evidence of its possessing such a power, and that all the facts that we are acquainted with go to disprove it." If absorbed,- then, by what agency is it decomposed, for if injected into the bloodvessels it destroys rapidly? Of all these theories of chymification, that of chemical action, aided by the collateral circumstances to be mentioned presently, can alone be embraced ; yet, how difficult is it to comprehend, that any one secretion can act upon the immense variety of animal and vegetable substances employed as food ! The discovery of the chlorohydric and acetic acids and of pepsin in the secretion, aids us in solving the mystery expressed by the well-known pithy and laconic observation of Dr. William Hunter in his lectures: "Some physiologists will have it, that the stomach is a mill; others, that it is a fermenting vat; others, again, that it is a stew- pan; — but, in my view of the matter, it is neither a mill, a fermenting vat, nor a stewpan ; — but a stomach, gentlemen, a stomach." Allusion has been already made to ^^e/vsw? — an organic compound or "ferment" thrown off from the stomach — which is an active agent in digestion. It had been observed in the experiments of Eberle and Schwann, that although acids alone have little power in digesting food, they act energetically when combined with the mucus of the stomach. Eberle thought, that the acidulated mucus of any membrane would produce the effect, but J. Miiller and Schwann found it to be restricted to that of the stomach. The agency of pepsin is regarded by Liebig^ to be similar to that of diastase in the germination of seeds. Both are . bodies in a state of transformation or decomposition; the latter effecting the solution of starch by its conversion into sugar; and the former the formation of alimentary matter into chyme. The present belief amongst physiologists and chemists — from all these experiments, as well as those of Wasraann and others — is, that pepsin, by inducing a new arrange- ment of the elementary particles or atoms of alimentary matter, dis- poses it to dissolve in the gastric acids. Chlorohydric acid, indeed, dissolves white of egg by ebullition, just as it does under the influence of pepsin; so that pepsin replaces the effect of a high temperature in the stomach.^ Liebig, consequently, does not believe that the digestive ' Essay on a New Mctliod of Tre.ating Serpent Bite and other Poisoned Wounds, p. 8, Chicago, 1854. * Animal Chemistry, Gregory and Webster's edit., p. lOl), Cambridge, Mass., 1S42. * Graham's Elements of Chemistry, Amer. edit., by Dr. Bridges, p. 69(3, Fhilad., 1843. 168 DIGESTION". process is a simple solution, but a species of fermentation, not identical, however, with any of the known processes of fermentation occurring in organic matters out of the body. It differs from ordinary fermenta- tion in being unattended with the formation of carbonic acid ; in not requiring the presence of oxygen, and in not being accompanied by the reproduction of the ferment.' The deductions of MM. Bernard and Barreswil,^ from numerous and varied experiments related to the Academie Royale des Sciences, of Paris, have been referred to already. From these, it would seem, that an or- ganic compound of like nature exists in the saliva, gastric juice, and pancreatic fluid; and that its digestive powers vary according as it is associated with fluid having an acid or an alkaline reaction. Thus in the gastric juice, which is acid, it readily dissolves nitrogenized sub- stances, — fibrin, gluten, albumen, &c., whilst it is altogether without action on starch. These gentlemen affirm, that if we destroy this acid reaction, and render the gastric juice alkaline by the addition of car- bonate of soda, the active organic matter being in presence of an alka- line fluid changes its physiological action, and becomes able to modify starch rapidly, whilst it loses the power of digesting nitrogenized sub- stances. As the saliva and pancreatic juice are alkaline, it was interest- ino- to know whether a chano;e in the chemical reaction of these fluids would produce in them the same change of properties as in the case of the gastric juice. Experiment proved such to be the flict. By rendering the pancreatic fluid or saliva acid, their ordinary action was inverted: they acquired the power of dissolving meat and other nitrogenized substances, whilst they lost their influence on starch. Certain of the positions of these gentlemen received support from the investigations of M. Blondlot.^ He is of opinion — and most of the physiologists of the present day accord with him — that of all the simple alimentary substances, those that are fluid at the ordinary temperature of the stomach, and those that are readily soluble in its secretions, as fluid albumen, sugar, gum, pectin, &c., are at once absorbed by the veins. It would seem, indeed, that in cases of scirrhus of the pylorus, and where a cancerous communication has existed between the stomach and colon,"* nutritious matter must necessarily be absorbed from the stomach: except, however, in such cases, the view, that digestion can be accomplished by the gastric veins, independently of the action of any gastric secretions, can scarcely be maintained.^ It would seem,, moreover, that certain aliments, after having experienced the necessary stomachal and intestinal changes, are received by imbibition into the veins of the intestines. MM. Bouchardat and Sandras affirm, that after herbivorous animals have been fed on farinaceous substances, more -dextrin, grape sugar and lactic acid are detected in the blood of the vena porta than in that of any other bloodvessel.^ Trommer, also ' Kirkes and Paget, Manual of Physiology, 2d Amer. edit., p. 173, Philad., 1853. 2 Comptes Rendus, 9 Decemb., 1844, and 7 Juillet, 1845. ^ Traite Analytique de la Digestion, Paris, 1S44. * Such a case is given by Dr. William Waters, in Philadelphia Med. Examiner, p. 201, April, 1845. ' A Physiological Essay on Digestion, by Nathan Pi. Smith, M.D,, &c., New York, 1825. ^ Gazette Medicale de Paris, Jan., 1845. CHYMIFICATION. 169 detected grape sugar in the blood of the portal vein, but not in that of the hepatic vein in animals to which that substance had been given with their food.^ The bearing of such observations on the production of sugar bj the liver will be shown hereafter. In conclusion: — Let us inquire into the various agencies to which the food is exposed during the progress of chymification. First. It becomes mixed with the secretions, already existing in the stomach, as well as with those excited by its presence. Secondly. It is agitated by the peristaltic motion of the stomach itself, and the movement of the neighbouring organs. Thirdly. It is exposed to a temperature of at least 100° of Fahrenheit, which, during the ingestion of food, does not rise higher: exercise elevates, whilst sleep, or rest, or a recumbent posture, depresses it.^ After food has been subjected to these influ- ences, the conversion into chyme commences. This always takes place from the surface towards the centre : the nearer it lies to the surface of the stomach, the more it is acted on ; and the part that is in contact with the lining membrane is more digested than any other ; — appear- ing as if corroded by some chemical substance capable of dissolving it. Dr. Wilson Philip^ asserts, that the new food is never mixed with the old ; the former being always found in the centre, surrounded on all sides by the latter. If the old and new be of different kinds, the line of separation between them is so evident, that the former may be com- pletely removed without disturbing the latter; and if they be of differ- ent colours, the line of demarcation can frequently be distinctly traced through the parietes of the stomach before they are laid open. Dr. Beaumont,^ however, affirms, that this statement is not correct ; that, in a very short time, the food, already in the stomach, and that subse- quently eaten, become commingled. In the subject of his experi- ments, he invariably found that the old and new food, if in the same state of comminution, were readily and speedily combined. The conversion of the food into chyme, it has been conceived, com- mences in the splenic portion, is continued in the body of the viscus, and completed in the pyloric portion. On this point, the observations of Dr. Philip differ somewhat from those of M. Magendie,* the former appearing to think, that chymification is chiefly accomplished in the splenic portion and middle of the stomach ; whilst the latter affirms, that it is mainly in the pyloric portion that chyme is formed ; — the alimentary mass appearing to pass into it by little and little, and during its stay there to undergo transformation. He further affirms, that he has frequently seen chymous matter at the surface of the ali- mentary mass filling the splenic half; but that it commonly preserves its properties in this part of the organ. The precise steps of the change into chyme cannot be indicated. Some of the results, at different stages of the process, have been ob- served on animals ; and pathological cases have occasionally occurred, which enabled the physiologist to witness what was going on in the interior of the stomach ; but, with perhaps one exception, those oppor- ' Kirkes and Taget, Manual of Physiology, 2d Amer. edit., p. 194, Philad., 1853. * Beaumont, On the Gastrio Juice, p. 274. ' Exper. Inquiry, oh. vii. sect. 1 ; and Treatise on Indigestion, Lond., 1821. * Oi). dtat., p. 89. * PrGcis, &c., edit, oit., ii, 88. 170 DIGESTION", tunities have not been mncli improved. Dr. Burrows^ relates a case of fistulous opening into the organ. The subject of the case was not seen by him until twenty-seven years after the injury, at which time the man was, to all appearance, healthy ; but he was drunken, and dissipated, and the following year died. A case is related by Shenck ;* and Louis'' refers to similar cases that occurred to Foubert and Covil- lard. Helm, of Vienna,'' published a case, to which reference has already been made ; and one of an interesting character occurred at the Hospital La Gharite of Paris, which sheds some little light on the subject.* The aperture, which was more than an inch and a half long, and an inch broad, exposed the interior of the organ. At the admis- sion of the female into the hospital, she ate three times as much as ordinary persons. Three or four hours after a meal, an irresistible feeling compelled her to remove the dressings from the fistulous open- ing, so as to allow the escape of food which the stomach could no longer contain, — when the contents came out quickly, accompanied by more or less air. They possessed a faint smell, but had neither acid nor alkaline properties; and the grayish paste, of which they consisted, when diluted with distilled water, did not affect vegetable blues. Digestion was far from complete ; yet, frequently the odour of wine was destroyed ; and bread was reduced to a soft, viscid, thick sub- stance, resembling fibrin recently precipitated by acetous acid, and swimming in a stringy fluid of the colour of common soup. Experi- ments, made on this half-digested food, at the Ecole de Medecine^ showed that the changes, which it had undergone, were an increase of gelatin; the formation of a substance like fibrin ; and a considerable portion of chloride of sodium, phosphate of soda and phosphate of lime. The patient could never sleep until she had emptied her stomach, and washed it out by drinking infusion of chamomile. In the morning, it contained a small quantity of thick, frothy liquid, analogous to saliva, which did not affect vegetable blues ; with matters of greater con- sistence, and some opaque, albuminous flocculi mingled with the liquid portion. The results of chemical experiments on this liquid were similar to those obtained on the analysis of saliva. But the most interesting case in its observed phenomena is one that occurred to Dr. Beaumont,^ of the United States Army, now of Saint Louis, which the author had an opportunity of examining. To this case, reference has already been made repeatedly. A Canadian lad, Alexis San Martin, eighteen years of age, received a charge of buck- shot in his left side, which carried away integuments and muscles of the size of the hand; fracturing, and removing the anterior half of the sixth rib; fracturing the fifth; lacerating the lower portion of the left lobe of the lung and the diaphragm, and perforating the stomach. When Dr. Beaumont saw the lad, twenty-five or thirty minutes after ' Transactions of the Royal Irish Academy, vol. iv. ' Observ. Medic, liar., Nov., &c., lib. iii. I'rancof., 1609. 3 Memoir, de TAcadtmie Royale de Chirurgie, vol. iv. p. 213, Paris, 1819. * Rudolphi, Grundriss der Physiologic, 2ter Band, 2te Abtheil, s. 114, Berlin, 1828. * Richerand's Elemens de Physiologic, edit, cit., p. 72. ^ Op. citat., Introduction, p. 10 ; and the Author's Elements of Hygiene, p. 216, Philad., 1835. CHYMIFICATION". 171 the accident, lie found a portion of the lung, as large as a turkey's egg, protruding through the external wound, lacerated and burnt; and, immediately below this, another protrusion, which, on inspection, proved to be a portion of the stomach, lacerated through all its coats, and suffering the food he had taken at breakfast to escape through an aperture large enough to admit the forefinger. It need scarcely be said, that numerous untoward symptoms occurred in the cicatrization of so formidable a wound. Portions of the ribs exfoliated; abscesses formed to allow the exit of extraneous substances ; and the patient was worn down by febrile irritation. Ultimately, however, the care and attention of Dr. Beaumont were crowned with success, and the instinctive actions of the system repaired the extensive injury. The wound was received in 1822, and on the 6th of June, 1823, one year from the date of the accident, the injured parts were sound, and firmly cicatrized, with the exception of the perforation leading into the sto- mach, which was about two inches and a half in circumference. Until the winter of 1823-4, compresses and bandages were needed to pre- vent the escape of the food. At this period, a small fold or doubling of the inner coat of the stomach appeared forming at the superior margin of the orifice, slightly protruding, and increasing in size until it filled the aperture. This valvular formation adapted itself to the opening into the organ, so as to completely prevent the escape of the contents, when the stomach was full; but it could be readily depressed by the finger. Since the spring of 1824, San Martin had enjoyed general good health; he was active, athletic, and vigorous; eating and drinking like a healthy individual. From the summer of 1825, Dr. Beaumont had been engaged in the prosecution of numerous experi- ments upon him ; some of the results of which he has given to the world. In the winter of 1833, he was in Washington, when the author — at the time. Professor of Medicine in the University of Virginia — was politely invited to examine San Martin for physiological purposes. Many of the results of this examination are given by Dr. Beaumont, and have already been, or will be, referred to in the present work. Dr. Beaumont's researches into the comparative digestibility of differ- ent alimentary substances belong to another department of medical science, and have accordingly received attention from the author else- where. What, then, it may be asked, are the changes wrought on the food in the stomach by the gastric secretions ? Dr. Prout' classes them Tinder three operations ; — the reducing, converting, and organizing and vitalizing. The first of these is probably the main operation. In order to decide, whether the action of the stomach in digestion be a simple solution, or a total or partial conversion, certain compounds of organization, easy of detection — as gelatin, albumen, and fibrin — were introduced, at the author's sug^o-estion, into the stomach through the fistulous opening in the subject of Dr. Beaumont's case ; whilst other portions were digested artificially in gastric juice obtained from the same individual. The solutions presented the same appearance, and were similarly affected by reagents; and in all cases, whether the * Bridgewater Treatise, Amer. edit., p. 235, Pliilad., 1834. 172 DIGESTION. digestion was artificial or rea.l^ the proximate principles could be thrown down in tlie state of gelatin^ fibrin or albumen^ as the case might be. These experiments, so far as they went, justified the con- clusion, that the digestive process in the stomach is a simple solution or division of alimentary substances, and an admixture with the mucous secretions of that organ, and the various fluids from the supra-dia- phragmatic portion of the digestive tube. With regard to the exist- ence of the other gastric operations described by Dr. Prout, well- founded doubts may be entertained. To his proposition that, what- ever may be the nature of the food, the general composition and character of the chyle remain always the same, no objection can be urged ; but, admitting its accuracy, it by no means follows, that the conversion must be effected in the stomach, or that any organizing or vitalizing powers are exerted upon the chyme in that organ. On the contrary, it appears that the essential changes effected on solid aliment in the stomach are of a purely physical character, so as to adapt it for the separation of the chylous portion in the intestines by organs whose vital endowments and influences cannot be contested. Dr. T. J. Todd' is disposed to believe, from his experiments on artificial digestion, that the various vegetable and animal substances subjected to the action of the digestive fluids at the ordinary temperature of the atmosphere are, in all instances, reduced — not to their chymical^ but to their organic elements ; and he is of opinion, that this applies equally to digestion in the stomach,^ From what has been already shown of the close approximation to each other in chemical composition of several of the compounds of organization, it may be understood, that many vegetable principles might be converted into animal principles without any material change of composition. They might all perhaps be changed into albumen, from which, as elsewhere seen, fibrin differs but little except in its organizable power. Saccharine matters — it has been conceived — may be converted, in the digestive tube, partly into albumen, and partly into oleaginous matter, the nitrogen of the former being furnished, according to some, by the pepsin or by some highly nitrogenized sub- stance secreted in the stomach, or duodenum, or both;^ but whether such conversion really occurs there is more than questionable. The oleaginous matters themselves are absorbed by simple imbibition as an emulsion formed by their union with the alkali of the pancreatic fluid." Most physiologists now agree, that animal food is converted into a modification of albumen, called albuminose^^ which, when it enters the vessels, is more easily assimilated than albumen. AVhilst a solution of the latter, indeed, if injected into the bloodvessels, is separated by the kidney ; the former undergoes assimilation in the system of nutri- ' Brit. Annals of Medicine, Jan., 1837. ' See, on the action of the gastric juice on aliments, Beaumont, op. cit. ; and Beraud, Manuel de Physiologie, p. 134, Paris, 18r)3. * Prout, on the Stomach and Urinary Diseases, p. xxviii., note. * Matteucci, Lectures on the Physical Phenomena of Living Beings, by Pereira, Amer. edit., p. 110, Philad., 1848, and C. Bernard, Archives Ui nerales, xix. tiO, cited in Bri- tish and Foreign Medico-Chirurgical Review, p. 528, April, 1849. * See page 48. CHYMIFICATION. 173 tion. On cane sugar a similar effect appears to be induced by admixture with the gastric secretions. It is converted into glucose, which when absorbed is more readily appropriated, or a portion of it may be converted into lactic acid. On the whole, in the present state of our knowledge of this import- ant function, we are perhaps justified in concluding: — First. That by the operation of the gastric secretions the nitrogenized principles of the food, whether animal or vegetable, are dissolved in the stomach. Secondly. That amylaceous matters are converted by the buccal secre- tions into saccharine, and these last are absorbed ; or they undergo a farther change, by which they are partly converted into lactic acid, and partly into oleaginous matter [?]. Thirdly. That the oleaginous matters undergo no change in the stomach ; and Fourthly. That with the exception of certain mineral substances, matters that cannot be reduced to either of these forms are sent on into the intestinal canal, to be rejected as excrement. In proportion as the food is digested, it passes through the pylorus. After the layer, that lies next to the mucous membrane, has experi- enced the requisite change, and is propelled onwards by the muscular action of the organ, the portion lying next to it becomes subjected to the same process. The gastric fluid, at the same time, penetrates, in a greater or less degree, the entire alimentary mass, so that, when the central portion comes in contact with the surface of the stomach, its conversion is already somewhat advanced. The chyme, thus success- ively formed, does not remain in that organ, until the whole alimentary mass has undergone chymification ; but as it is completed, it is trans- mitted, by the peristaltic action, through the pylorus into the duode- num. In the early stages of digestion, the passage of the chyme from the stomach is more slow than in the later. At first, it is more mixed with the undigested portions of food, and, as Dr. Beaumont^ suggests, is probably separated with difficulty by the powers of the stomach. In the more advanced stages, as the whole mass becomes chymified, the process is more rapid, and is accelerated by the peculiar contraction of the stomach, already described. After the expulsion of the last parti- cles of chyme, the organ becomes quiescent, and no more gastric secre- tion takes place, until a fresh supply of food is received, or some me- chanical irritation is produced in its inner coat. The time, required for the complete chymification of a meal, is stated by the generality of physiologists to be about four or five hours. In Dr. Beaumont's case,^ a moderate meal of meat, with bread, &c., was digested in from three hours to three hours and a half. We believe that, in by far the majority of cases, a longer time than this is neces- sary ; and in laborious digestions, the presence of food can be distin- guished by eructations for more than double the time. It is manifest, that no fixed period can be established for the production of this effect. It must vary, according to the digestive capability of the individual ; the state of his general health ; and the relative digestibility of the ali- ments employed ; all which, as we have already seen, admit of great diversity. It would seem that the most digestible aliments should be ' On the Gastric Juice, p. 96. 2 Ibid., p. 275. 174 DIGESTION. most speedily sent on into the duodenum; yet sucli is not perhaps the case. Certain it is, that many articles pass the pylorus after having experienced little or no change ; and in cases of artificial anus, Pro- fessor Lallemand, of Montpellier, observed that the least nutritive and least digestible presented themselves first. Vegetable substances ap- peared before animal ; and totally indigestible substances — as pieces of money — are known to clear the stomach rapidly.^ During chymification only a very small quantity of air is found in the stomach; sometimes, none. "When met with, it is near the cardiaxj orifice, or at the upper part of the splenic portion. M. Magendie examined the gases in the stomach and intestines of executed crimi- i'lals, and obtained the following results : a, in the case of an individual who had taken food in moderation an hour previous to death ; 6, in the case of one who had eaten two hours previously ; and c, in the case of one who had done so four hours previous to execution. 100 volumes of the gas contained Oxygen. !From tlie stomacli, small intestines, large do. ! From the stomach, small intestines, large do. !From the stomach, small intestines, large do. From these results it appears, that when the execution occurred not longer than an hour after a meal, oxygen was found in the stomach ; and when not until two hours, it had entirely disappeared, and a large quantity of nitrogen was found in the intestines, with an entire absence of oxygen ; whence it is inferred, that the oxygen of the air is sepa- rated from the nitrogen in the stomach; and the former is employed in digestion. The view of Liebig is, that the oxygen occasions a mole- cular action in the pepsin or animal matter in the stomach, and that this intestine motion is communicated to the molecules of the albumen or protein of the food, so that the latter is rendered soluble in the gas- tric acid.^ The oxygen he refers to atmospheric air enclosed in the saliva during mastication, and in that way introduced into the stomach. The small quantity of air, discovered in the stomachs of animals, disproves the idea of M. Chaussier, that we swallow a bubble at each effort of deglutition. If so, the stomach ought to be always inflated, especially after eating, which is not the case. MM. Leuret and Las- saio-ne'* found the air, obtained from the stomach of a dog fed on meat, to consist of carbonic acid, 43 parts ; sulpliuretted hydrogen, 2 parts ; oxygen, 4 parts; nitrogen, 31 i^arts; carburetted hydrogen, 20 parts. Whence these gases proceed will be a subject of future inquiry. In a robust individual, chymification is effected without conscious- ness of the process. He finds, especially if the stomach be over-dis- • Beraud, Manuel de Physiologic, p. 148, Paris, 1853. 2 Liebig, op. cit., p. 2?9. * Ancell, Lond. Lancet, Dec. 16, 1842, p. 419. « Recherches sur la Digestion, Paris, 1825. Oxvgen. Azote. Carbonic Acid. Inflammable Gas. ll.OO 71.45 14.00 3.55 00.00 20.08 24.39 55.33 00.00 51.03 43.50 5.47 00.00 00.00 00.00 00.00 , 00.00 8.85 40.00 51.15 00.00 18.40 70.00 11.60 00.00 00.00 00.00 00.00 , 00.00 66.60 25.00 8.40 00.00 45.96 42.86 11.18' CHYMIFICATION. 175 tended, tbat the feeling of fulness and the oppression of respiration, produced bj the distension of the organ, gradually disappear. It is not uncommon, however, for slight shivering or chilliness to be felt at this time ; for the sensations, and mental and moral manifestations to be blunted; and a disposition to sleep to be experienced. "This con- centration of the whole vital activity," according to M. Adelon,^ "is so natural to the animal economy, that there is always danger in oppos- ing or crossing it by any extraneous or organic influence ; as by bath- ing, the use of medicine, violent exercise, mental emotions, intense intellectual effort, &c." Gentle exercise, however, would seem to favour digestion. Such is the conviction of Dr. Beaumont,^ from his observa- tions. In the subject of his experiment, he found the temperature of the stomach generally raised by it a degree and a half, and chymifica- tion expedited. Where digestion is imperfect, the signs, already men- tioned, will be accompanied by the disengagement of air and consequent eructations ; a sense of weight, or of heat, or of unusual distension in the epigastric region, &c. ; but these, as well as the developement of sulphuretted hydrogen, discharged by eructation, are the products of ordinary decomposition or fermentation, and appertain to the morbid condition of the function or to indigestion. Yet, as M. Magendie^ has remarked, it does not seem, that these laborious digestions are much less profitable than others. The food, habitually received into the stomach, contains far more nutritive matter than is necessary to sup- ply the wants of the system ; and, in the cases in question, enouo-h chyle is always separated in the small intestine to supply the losses, and even to add to the bulk of the body. It has been already remarked, that the chyme, first formed, does not continue in the stomach until the whole meal has undergone chymifi- cation ; but that, as soon as it has experienced the necessary changes, it passes through the pylorus into the duodenum. It would appear, that the accumulation of chyme in the pyloric portion of the stomach never exceeds four ounces at any one time. M. Magendie states, that, in the numerous experiments, in which he has had an opportunity of noticing it, he uniformly found, when the quantity amounted to about two or three ounces, it was permitted to pass through the pylorus into the duodenum. This passage of the chyme is effected by the peris- taltic action. At the commencement of digestion, the duodenum con- tracts inversely, and the pyloric portion of the stomach, at the same time, drives its contents into the sj^lenic. This movement is, however, soon followed by one in an opposite direction ; and, after a time, the inverted action ceases, and the movement is altogether in one direc- tion; — from the stomach towards the intestine. The movement by which the chyme is immediately sent into the duodenum, is thus effected : — the longitudinal fibres, which pass from the cardiac to the pyloric orifice, contract, and approximate the two orifices ; the pyloric portion then contracts, not so as to direct the chyme into the splenic portion, but towards the duodenum: in this manner, the chyme passes from the stomach : and, as fresh portions are formed, they are success- ' Pliysiologie de I'lTomme, edit, cit., ii. 433. ^ On the Gastric Juice, p. 93. " Precis, &c., ii. 104. 176 DIGESTION. ively sent onwards ; the peristaltic action becoming more and more marked and frequent, and extending over a larger portion of the organ, as clijmification approaches its termination. As the chyme is discharged into the small intestine, the stomach gradually returns to its former dimensions and situation. f. Action of the Small Intestine. The changes in the alimentary mass in the small intestine are not less important than those already considered. They consist in a farther change of the chyme into a substance, whence chyle can be ex- tracted by the action of the chyliferous vessels or lacteals. Whether chyle be separated in the intestine, in a state fit for chyliferous absorp- tion, or be formed by those vessels, will have to be canvassed hereafter. In common language, however, it is said to be separated there, and the process, by which this is accomplished, is called chylification. As the chyme proceeds into the duodenum, it readily finds space, until towards the end of chymification, when the intestine not unfre- quently experiences considerable dilatation. The presence of the alimentary mass augments the secretion from the mucous membrane; and occasions a greater flow of the biliary and pancreatic juices. IvIM. Leuret and Lassaigne' found, when \\\qj applied vinegar, diluted with water, to the external surface of the small intestine in a living animal, that a considerable quantity of serous fluid was immediately exhaled. The same application, made to the follicles of the intestine, excited the secretion of a greater quantity of mucus; and its application to the mouths of the choledoch and pancreatic ducts caused the orifices to dilate, and a greater discharge of bile and pancreatic juice. It is in this local manner that many of the cholagogue purgatives produce their effect. Calomel exerts its agency on the upper part of the intes- tinal canal more especially; and the irritation it induces in the mucous membrane at the mouth of the ductus communis choledochus is propa- gated along the biliary ducts to the liver, the secretion of which is thus augmented — but not by any specific action exerted on the organ, as has been often imagined. As the chyme is acid, it induces the same effects on the follicles as the acid employed in the experiments of MM. Leuret and Lassaigne. The chyme does not remain so long in the intestine as food does in the stomach. The successive arrival of fresh portions propels the first onwards; and the same effect is induced by the peristaltic action of the intestines — an involuntary, muscular movement of an irregular, undulatory, oscillatory or vermicular character, which consists in an alternate contraction and dilatation of the organ, proceeding generally from above to below, so as to propel the chyme downwards. When it reaches any point of the intestine, its contact excites the contraction of the circular fibres of the part; so that it is sent forwards to another portion of the canal; the circular fibres of which contract, whilst the former are relaxed; and this occurs successively through the whole tract of the intestines. The longitudinal fibres, by their contraction, shorten the intestine, and in this manner meet the chyme, so as to ' Recherclies sur la Digestion, Paris, 1825. ACTION OF THE SMALL INTESTINE. 177 facilitate its progress; but their effect cannot be considerable. When digestion is not going on, the peristaltic action occurs only at inter- vals; always slowly and irregularly; and perhaps, as has been sug- gested, only when sufficient mucous secretion has collected on the inner coat of the intestine to provoke it. During digestion, it is much more energetic and frequent, and more marked in the duodenum and small intestine than in the large; occurring not continuously, but at intervals, as the chyme arrives and excites it. When the small intes- tine is surcharged, it may take place in several parts of the canal at once ; and, at times, the action is inverted. The secretions poured into the intestinal canal lubricate it, and facilitate the progress of the chyme. This is aided by the free and floating condition of the intestine; and by the agitation of the diaphragm and abdominal muscles in respiration. Yet its course along the small intestine is slow. The chjmie is not transmitted from the stomach continuously ; and the peristaltic action of the intestines occurs only at intervals. Moreover, owing to the convolutions of the intestinal canal, the chyme must, in many cases, proceed against its own gravity; and be retarded by the numerous valvulse conniventes, which bury themselves in it, when the canal is contracted by the action of the circular fibres. All these circumstances must cause it to proceed slowly along this part of the tube — a point of some importance, when we reflect, that an essential change is effected on it through the influ- ence chiefly of the bile and pancreatic juice, and that its nutritive portion is here absorbed. In the duodenum, the course of the chyme is slow. In the jejunum it is more rapid, hence the name, which indi- cates, that it is almost always found "empty." in the ileum again it is slower on account of the greater consistence acquired by the absorp- tion of the chylous portion. Whilst the food is in progress along the small intestine, it experiences the change in its physical properties, which enables the chyle to be separated from it by absorption. These two actions have been termed respectively cUyVfication and the alsorp- tion of chyle; although by some the former term has been applied to both processes. Above the point at which the common choledoch and pancreatic ducts open into the duodenum, no change is observable in the chyme. It preserves its color, semi-fluid consistence, sour smell, and slightly acid taste; having been simply mixed with the exhaled and follicular secretions of the lining membrane ; but, immediately after it has passed the part, at which the hepatic and cystic bile and the pancreatic juice are poured into the intestine, it assumes a different appearance; its color is found to be changed; it becomes yellowish; of a bitter taste; its sour smell diminishes; and chyle can now be separated by the lac- teals. Accordingly, at this part of the canal, chyliferous vessels are first perceptible. The change effected upon the chyme in the small intestine is, — like that produced on the food in the stomach, — of an entirely phy- sical character. The chyle itself, we shall endeavour to show here- after, is formed by an action of elaboration and selection exerted by the chyliferous vessels. No difference is observable between the chylous and excrementitious portions of the chyme in any part of the VOL. I.— 12 178 DIGESTION". small intestine ; nor can it be separated by pressure or by any other physical process, M, Magendie,^ indeed, has affirmed, that if the chyme proceeds from animal or vegetable substances that contain fat or oil, irregular filaments are observed to form, here and there, on the surface, — sometimes of a flat, at others, of a round shape, — which speedily attach themselves to the surface of the valvule, and appear to be brute chyle; but this is not observed when the chyle proceeds from food, that does not contain fat. In this case, a grayish layer, of greater or less thickness, adheres to the mucous membrane, and ap- pears to contain the elements of chyle. MM. Leuret and Lassaigne^ state, that if an. animal be opened while digestion is going on, — on the surface of the chyme, between the pjdorus and the orifice of the ductus communis choledochus, a grayish-white, homogeneous, dense, fluid, and acid substance is perceived on the villi of the intestine. Neither of these, however, is chyle. It is merely the substance whence chjde is obtained by the action of the chyliferous vessels. The fact, mentioned by M. Magendie, — regarding the appearance of irregular filaments, when animal or vegetable substances, containing fat or oil, have been taken as diet, — has been the occasion of erroneous deduc- tions of a pathological character. Frank' asserts, that he was re- quested to see a prince, who was attacked with epilepsy. His phy- sician, — a respectable old practitioner, — assured Frank, that he could make his patient void thousands of filiform worms at pleasure. As he was unable to define either the genus or species of these worms, — the quantity of which, from his account, seemed to be prodigious, — Frank requested to be a witness of the phenomenon. The physician administered a dose of castor oil, which produced numerous evacua- tions, containing thousands of whitish filaments similar to small eels ; but on an attentive examination of these pretended worms, they were found to consist entirely of the castor oil, in a state of fine division. The alteration of the aliment in the small intestine is probably of a chemical nature ; yet it has been conceived to be organic and vital. The same remarks are applicable here as were indulged upon the supposed organic and vital action of the stomach exerted in the for- mation of chyme. The agents of this alteration are: — the fluids secreted from the mucous membrane of the small intestine, and the biliary and pancreatic juices, aided by the temperature of the parts, and the peristole. Haller* was of opinion, that the first of these is a principal agent. Eeflecting on the extensive surface of the small intestine, on the number of arteries distributed to the organ, and on the size of these arteries, that distinguished physiologist asserted, that the lining membrane of the intestine, at the time of chylification, secretes a juice, which he estimated at the enormous quantity of eight pounds in the twenty-four hours. To this he gave the name sulcus irdestinalis — succus entericus — and assigned it as im]:)ortant a part in chylification as he attributed to the gastric juice in chymification. It is probable, however, that the fluids secreted by the mucous mem- brane of this portion of the canal resemble those of the rest of the ' Precis, &c., ii. 111. 2 Qp. citat. ' De Curandis Homiuum Morbis Epitome, lib. vi. p. 218. '• Element. Physiol., xis. 5. ACTION OF THE SMALL INTESTINE. 179 intestinal mucous membrane; and that a main function is that of lubricating the intestine, and of still further diluting the chymous mass. MM. Leuret and Lassaigne endeavoured to procure some of them by making animals, whilst fasting, swallow small sponges, en- veloped in fine linen, and killing them twenty -four hours afterwards. Some of these sponges had not gone further than the stomach, and were filled with gastric juice ; others, which had reached the small intestine, had imbibed the succus intestmalis, which was more yellow, and manifestly less acid than the gastric secretion. On attempting to dissolve a crumb of bread in each of these juices, they discovered tliat the gastric secretion communicated a sour sjnell to the bread ; but that the intestinal secretion allowed the bread to be precipitated, and dissolved no part of it. From this experiment, it has been concluded, that the succus intestinalis is not a great agent in chylification. No weight, however, can be placed upon results obtained in so unsatis- factory a manner ; for it is obvious, that no certainty could exist as to the identity between the gastric and intestinal juices and the fluids found in the respective sponges. We have strong reason, indeed, for believing, that, even if food should escape the action of the stomach, it is capable of being digested in the small intestine. This may be owing to some of the true gastric juice passing into the intestinal canal, and impregnating it ; or it may be a similar secretion from follicles seated there. Experiments by Bidder and Schmidt on living animals have shown, that albuminous matters inserted into the ileum, when all excess of gastric juice was prevented, were acted upon in the same manner as in the stomach ; and Dr. C. 11. Jones proved the correctness of their inferences, on repeating the experiments.' The lining membrane of the small intes- tine possesses the property of coagulating milk; and pathological cases occur in which the stomach is, to all appearance, completely dis- organized ; yet patients survive so long as to compel us to presume, that digestion must have been eft'ected elsewhere than in that organ. M. Magendie^ placed a piece of raw meat in the duodenum of a healthy dog. At the expiration of an hour it had reached the rectum, and its weight was found to be but slightly diminished ; the only change ap- peared to be at its surface, which was discoloured. In another experi- ment, he fixed a piece of muscle with a thread, so that it could not pass out of the small intestine. Three hours afterwards, the animal was opened. The piece of meat had lost about half its weight. The fibrin was especially attacked; and what had resisted, which was almost all areolar tissue, was extremely fetid. In experiments by M. Voisin,^ aliment was introduced into the small intestines of animals, — in one case masticated and mixed with saliva ; in another without any preparation. In a few hours, in the first instance, and after a longer period in the second, the food was as completely chymified as if the process had taken place in the stomach. The same experiments Avere repeated upon animals whose pylorus had been secured by ligature, and with similar results. One of them lived for a month after the ' Til. K. Chambers, Brit. & For. Med.-Chir. Rev., Oct. 1855, p. 311. 2 Precis, &c., ii. 113. ^ Nourel Aper^u sur la Physiologie du Foie, etc., Paris, 1833. 180 DIGESTION. ligature, nourished for that period bj food introduced into the duo- denum. These facts sufficiently show, that a solvent action is exerted in the small intestine; and there is reason for ascribing to the mixed fluid poured into it a great power of reducing alimentary substances to a condition in which they may be absorbed. MM. CI. Bernard and De Chaniac' found it act energetically on all alimentary prin- ciples; it emulsified fatty bodies; modified albuminous substances, and transformed starch into sugar; and Bidder and Schmidt are of opinion that in addition to the succus intestinalis exerting a solvent action on albuminous substances scarcely less than that of the gastric juice, it has a power of converting starch into sugar scarcely less than that of saliva or pancreatic fluid. Dr. Ayres,^ indeed, from his "micro- chernical researches on the digestion of starch and amylaceous foods" is disposed to assign almost the whole action to the succus intestinalis, since he found the conversion into glucose to occur after the ligature of the common choledoch duct, and after the ligature of both the bile and pancreatic ducts in the same animal; and a farther proof was afforded of the activity of the intestinal mucus taken from the upper part of the duodenum, above the entrance of the pancreatic duct, after ligature of that duct and of the common bile-duct, by its capability of converting a large quantity of fresh-boiled starch into glucose out of the body. The biliary and pancreatic juices are usually esteemed great agents in chylification. It has been already remarked, that the chyliferous ves- sels do not begin to appear above the part at which these juices are poured into the duodenum ; that in the rest of the small intestine they are less and less numerous as we recede from the duodenum ; and that the chyme does not exhibit any marked change in its properties, until after its admixture with those fluids. Direct experiments have been made for the purpose of testing the use of the bile in digestion. Sir Benjamin Brodie tied the ductus communis choledochus in young cats, so as to prevent both hepatic and cj'stic bile from reaching the intes- tine. He found, that chjdification was interrupted, and there were neither traces of chyle in the intestines nor in the chyliferous vessels. The former contained onl}^ chyme, similar to that of the stomach, which became solid at the termination of the ileum ; and the latter, a trans- parent fluid, which appeared to be a mixture of l^nnph, and of the more liquid portion of the cliyme. Mr. Mayo,^ likewise, found, that when the ductus communis choledochus was tied in the cat or dog, and the animals were killed at various intervals after eating, there was no trace whatever of chyle in the lacteals. M. Magendie,'* however, repeated these experiments on adult animals, and with dissimilar results. The greater part died of the consequences of opening the abdomen, and of the operation required for tying the duct. But in two cases, in ' Art. Digestion, p. 231, in SnppL'ment au Dictionnaire des Dictionnaires de Mede- cine, par Fabre, Paris, 1S51; and Bidder and Schmidt, Die Verdauungssafte und der Stott'wechsel, S. 272, Mitau und Leipzig, 1852. See also, Lehmann, Physiological Chemistry, Amer. edit, by Dr. R. E. Rogers, i. 512, Philad., 1855. ^ Proceedings of the Royal Society ; and Quarterly Journal of Microscopical Science, April, 1855, p. 251. •* Lond.Med. and Physical Journal, Oct., 1S26; and Outlines of Physiology, 4th edit., p. 125, London, 1837. •• Op. citat., ii. 117. ACTION OF THE SMALL INTESTINE. 181 whicli they survived some days, lie discovered that digestion had per- sisted; white chyle had been formed, and stercoraceous matter pro- duced. This last had not the usual colour ; but this, as he remarks, is not surprising, as it contained no bile. The experiment was repeated by MM. Leuret and Lassaigne,^ and with results similar to those ob- tained by M. Magendie. In the duodenum and jejunum, a whitish chyme adhered to the parietes of the organ; and in the thoracic duct there was a fluid of a rosy-yellow colour, which afforded, on analysis, the same constituents as chyle ; although the subjects of the operation had been kept, for some time, without food. The experiments of Messrs. Tiedemann and Gmelin^ on this subject were marked by the usual care and accuracy of those observers. They found, that the animals were attacked with vomiting, soon after the operation, and afterwards with thirst and aversion for food ; on the second or third day, the conjunctiva became yellow, the evacuations chalky, and very fetid, and the urine yellow. Some of the animals died ; others were killed : of the latter, some had previously recovered from the jaundice, owing to a singular recuperative phenomenon, no- ticed by Dr. BlundelP and Sir B. Brodie in their experiments — to the re-establishment of the choledoch duct, by the effusion of lymph around the tied part, and the subsequent dropping off" of the ligature. Like Sir B. Brodie, Mayo, Leuret and Lassaigne, and Voisin, they observed that chymification went on as in the sound animal. The thoracic duct and chyliferous vessels, in animals fed a short time before death, always contained an abundant fluid, which was generally of a yellowish colour. It coagulated like ordinary chyle ; the crassa- mentum acquired the usual red colour; and the only difference between it and the chyle of a sound animal was, that after tying the duct it was never white. They conceived the reason of the difference to be, that the white colour is owing to fatty matter taken up from the food by the agency of the bile, which possesses the power of dissolving fat ; and may probably, therefore, aid in effecting its solution in the chyle in the radicles of the chyliferous vessels. Sir Benjamin Brodie and Mr. Mayo are considered to have been misled by the absence of the white colour, usually possessed by the chyle, but which is wanting in ordinary diges- tion, if the food does not contain fatty matter.'' The experiments of Dr. Beaumont showed, that oil undersroes but little chano;e in the sto- mach, and that bile is probably necessary to give it the requisite physical constitution, in order that chyle may be separated from it. Messrs. Tiedemann and Gmelin restrict the agency of the bile in chylification to the accomplishing of the solution of the fatty matter, and to the nitrogenizing or animalizing of food that does not contain nitrogen. The experiments of M. Voisin equally show, that the ligature of the choledoch duct does not prevent the formation of chyle, provided the passage of the pancreatic fluid is not at the same time prevented. In • Recherclies sur la Digestion, p. 147, Paris, 1825. * Recherclies Experimentales, &c., sur la Digestion, ii. 53, Paris, 1827. ^ Researches, Physiological and Pathological, London, 1825 ; and Elliotson's Physio- logy, p. 124, London, 1840. ' Edinb. Me 1. and Surg. Journal, xciii. ; ami Mayo, Outlines of Human Physiology, 4th edit., p. 130, London, 1837. 182 DIGESTION. a number of dogs, a ligature was applied so as to completel}' prevent the passage of bile into the intestine. Two lived three months after the experiment: three, six weeks ; and five died shortly after the appli- cation of the ligature. In no instance did death appear to be owing to the suspension of digestion or assimilation. Almost all the animals had begun to eat ; and, in the majority, fopd perfectly chymified was found in the duodenum ; and well elaborated chyle in the chyliferous vessels. It would appear, therefore, that the bile, although an import- ant, is not an essential 'agent in digestion in the duodenum. This is signally corroborated by the cases of two infants, four or five months old, recorded by Dr. Blundell. The hepatic ducts in both cases ter- minated blindly, so that no bile entered the intestines ; the evacuations were white like spermaceti, and the skin jaundiced. Yet they grew rapidly, and throve tolerably. No certain knowledge exists, whether any of the elements of the bile are absorbed in the form of chyle ; or whether it acts mainly as a precipitate, and is thrown off with the excrement. As elsewhere shown, however, it is largely excrementitious or depurative. As to the mode in which the biliary'- and pancreatic fluids act on the chyme, we have not had, until recently, much more than conjectures to guide us. MM. Tiedemann and Gmelin suggest, that the soda of the bile unites with the chlorohydric and acetic acids of the chyme ; and simultaneously the latter precipitates the mucus of the bile and its colouring principle and resin, which are evacuated with the excre- ments. The majority of physiologists believe, that bile is divided into two parts by the action of the chyme; the one — containing the alkali, salts, and a part of the animal matter — uniting with the chyle ; the other — containing the coagulated albumen, the coloured, concrete, acrid, and bitter oil — uniting with the faeces, to be discharged along with them. According to this view, the action of the bile would be purely chemical; a part would be recrementitial or taken up again; and a part excrementitial, giving to the excrements their smell and colour; and, according to some, the necessary stimulating property for exciting the flow of the intestinal fluids, and soliciting the peristaltic action of the intestines so as to produce their evacuation. It is more than doubtful, however, whether the bile have any such influence as the last. It is a law in the economy, that no secretion irritates the part over which it passes, or is naturally destined to pass, unless such part is in a morbid condition ; and were it otherwise, the mucous mem- brane of the intestine would be soon accustomed to the stimulation; and, the effect be null. MM. Tiedemann and Graelin further suggest, that from the abundance of highly nitrogenized principles, which the bile contains, it probably contributes to animalize those articles of food, that do not contain nitrogen; and that it may tend to prevent the putrefaction of the food in its course through the intestines, inas- much as when it is prevented from flowing into them, their contents appear much farther advanced in decay thnn in the healthy state. M. Bernard,' too, has shown experimentally, that in the living body ' Amer. Journ. of tlie Med. Sciences, Oct. 1851, p. 351. ^ ACTION OF THE SMALL INTESTINE. 183 it checks the process of fermentation, which it had been found to do out of the body. It has been held of late, that bile has the power of transforming saccharine aliments into fat ; a circumstance, which is favoured by the discovery of H. Meckel,' that when sugar is mixed with bile out of the body a part of it is converted into fatty matter. Admixture with the pancreatic juice would then render its absorption easy. (See Secretion of Bile.) We were not instructed until of late in regard to the precise uses of the pancreatic juice ; although many have been assigned to it. which, being founded in ignorance of its nature and properties, it would be a waste of time to notice. Messrs. Tiedemann and Gmelin affirm, that it yields to the chyme the richly nitrogenized principles, that enter into its composition; and, consequently, aids in assimilation. In tes- timony of this, they remark, that the pancreas is larger in herbivorous than in carnivorous animals; and that, in proportion as the chymous matter proceeds along the intestinal canal, it exhibits itself less rich in albumen and other nitrogenized matters, which have probably been abstracted from it by absorption. Dr. Marcet^ discovered in the chyme of the small intestine a notable developement of albumen, which was first perceptible a few inches from the pylorus, and did not exist in the large intestine ; and Messrs. Tiedemann and Gmelin found in the intestinal contents of animals, that had swallowed pebbles while fast- ing, more albumen than the pancreatic juice could account for. If such be the fact, albumen must be either developed from the food, or secreted from the mucous membrane. There is a striking resemblance in chemical properties between the pancreatic juice and saliva; and the views applicable to both one and the other, embraced, as the result of numerous experiments by MM. Bernard and Barreswil, have been already stated. The experiments of M. C. Bernard'' have shed important light on this matter. Ex- posure of fatty bodies to the pancreatic juice out of the body produced at once a complete emulsion, whilst no such effect was produced on such bodies by admixture with other fluids — saliva, gastric juice, or serum of the blood, for example. These experiments were frequently repeated with like results in the presence of distinguished observers — MM. Magendie, Berard, Andral, &c. When dogs to which fatty sub- stances had been given were killed during digestion, these substances were found unaltered until they came in contact with the pancreatic fluid ; and if the duct of the pancreas was tied all change was pre- vented. It would seem, therefore, that although the pancreatic fluid resembles the saliva in many respects — so much so, indeed, that the pancreas has been styled " the abdominal salivary gland," — it is pos- sessed of properties as a digestive fluid which the saliva has not. In ' Henle und Pfeuflfer, Zeitschrift fur rationelle Medicin ; cited by Mr. Paget in Report in British and Foreign Medical Review, p. 261, July, 1846. ^ Medioo-Cliirurgical Trans., vi. 618. ^ Archives Generales, xiv. ; translated in the Provincial Medical and Surgical Jour- nal for March 31, 1849. For an account of M. Bernard's investigations, see Dr. Donald- son in Amer. .Journ. of the Med. Sciences, Oct. 1851; and H. Ludlou-, Brit, and For. Med.-Chir. Rev., Jan. 1854, p. 62, 184 DIGESTION". a remark upon a subsequent memoire bj M. Bernard — the commis- sion, consisting of MM. Magendie, Milne Edwards and Dumas — do not hesitate to conclude, that M. Bernard has completely established the ]Dhysiological office of the pancreas and made known the mechanism of the digestion of fatty matters.' It has been shown, however, by the experiments and observations of Frerichs,^ Lehmann, Lenz, Herbst^ and others, that digestion of fatty matters takes place after the pan- creatic duct has been tied — sufficient time having been permitted for the evacuation of any pancreatic fluid, which may have been in the intestine prior to the operation — and even in the lower portion of the small intestine, into which these substances have been conveyed by injection after entire isolation, by means of a ligature, from the part of the canal into which the pancreatic secretion had been discharged. It would seem, too, from the results of the experiments of those ob- servers, that a mixture of ttie fluid of the pancreas with bile and the succus intestinalis has a greater emulsifying power than the first of these fluids alone. The succus intestinalis would seem, indeed, to be an important adjuvant in the action.'* The influence of the temperature of the interior of the intestine, and of the peristaltic motion, on chylification, can be looked upon as onh^ accessory and indirect. Whilst the chyme is passing through the small intestine, it is sub- jected to the action of the chyliferous vessels, which extract from it the nutritious part or chyle, — a fluid especially destined for the reno- vation of the blood. How this is accomplished will be treated of under the head of Absorption. In proportion as this absorption is effected, the chyme changes its properties. In the commencement of the jejunum, it is the same as in the duodenum; but, lower down, the grayish layer, that existed at its surface, is observed to gradually dis- appear. It assumes greater consistence; its yellow colour becomes more marked; and, in the ileum, it has a greenish or brownish tint; and from being acid becomes alkaline, until, at the lower part of the small intestine, it seems to be the useless residue of the alimentary matter, and of the various secretions from the upper portion of the digestive apparatus. It is now mere excrementitious matter or fieces, although not possessing the entire fiecal odour. Its alkaline character has generally been ascribed to admixture with the bile, pancreatic fluid, and the secretion from the intestinal glandulas. The agency of the bile was supposed to be through its free soda, or the carbonate or tribasic phosphate of soda. The bile, however, as shown elsewhere, is neutral ; and accordingly it has been suggested as more probable, that the chyme is made alkaline by the ammonia, which is one of the • Gazette Medicale, No. 9, Paris, 1849. 2 Wagner's Haudworterb. der Physiologie, art. Verdauung, 3ter Band, S. 845, Braun- schweig, 1846 ; and Bidder and Scliniidt, Die Verdauungssiifte und der StofFwechsel, S. 246, Mitau und Leipz., 1852. 3 Henle and Pfeutfer's Zeitsclirift, Bd. iii., S. 389-91; and Canstatt's Jalxresbericht, 1853, S. 148, Wiirzburg, 1854. •* Todd and Bowman, The Physiological Anatomy and Physiology of Man, Pt. iv., Sect. 1, p. 246, Lond., 1852; and Prof. S. Jackson, Amer. Jouru. of the Med. Sciences, Oct. 1854, p. 307. ACTION OF THE LARGE INTESTINE. 185 products of the spontaneous decomposition of bile in the intestines.' The pancreatic juice is certainly alkaline. During the formation of chyle, gases are almost always present in the small intestine. They were first examined by Jurine ; but chemical analysis was by no means as advanced at that day as it is now ; MM. Magendie^ and Clievreul have more recently analyzed those, which they found in the small intestines of three criminals; all young and vigorous. The results of this analysis have been given already (p. 174). The gases might originate in various ways. They might pass, for example, from the stomach with the chyme. There is this objection, however, to the view; that the air in the stomach contains oxygen and very little hydrogen ; whilst a considerable quantity of the latter gas is almost always found in the small intestine, and never oxygen. Again, they might be secreted by the mucous membrane of the intestine. So far as we know, however, carbonic acid and nitrogen are alone exhaled from the tissues. We would still have to account for the hydrogen. Lastly, they might arise from the reaction of the elements of the chyme upon each other, and this has been considered the most probable origin. M. Magendie^ has frequently seen bubbles of gas escaping from the chymous mass, between the mouth of the ductus communis choledochus and the ileum ; but never from that of the ileum, the upper part of the duodenum, or stomach; and he affirms, that Chevreul, in prosecuting some experiments, found that when the mass obtained from the small intestine was suffered to ferment for some time in a stove, at the tem- perature of the body, the same gases were obtained as those met with in the small intestine. The presence of air in the intestines has its positive advantages. It preserves the canal in a condition adapted for the ready exercise of its functions : — thus, it facilitates the progress of the contained matters, as it is more easy for the intestine, when it con- tracts, to propel substances contained in a hollow space, than in a canal whose sides are in contact.* The absorption of chyle is, doubtless, also favoured by it.* When the food has attained the lower part of the ileum, the process of chylification has been accomplished, and the residuary matter is transmitted, by the peristaltic action, into the large intestine. The movement, however, recurs irregularly and at long intervals. In the living animal it can rarely be perceived; but may be noticed in one recently killed, and appears to have no coincidence with that of the pylorus. g. Action of the Large Intestine. The large intestine acts as a reservoir and excretory canal for the faeces. The residue of the alimentary matter is sent on through the valve of Bauhin by the peristaltic action of the ileum. This valve, we have seen, is so situate at the point of union between the ileum and caecum as to permit a free passage from the former to the latter, but to ■ Valentin, Lehrbuch der Physiologie des Mensclien, i. 338, Braunschweig, 1844. 2 Precis, ii. 115. ^ Iljid., 117. ^ Berand, Manuel de Physiologie, p. 217, Paris, 1853. ^ Kornback, De Necessitate Aeris Atmosphserici ad Sorbitionem Chyli Adjuvandum, Hal., 1848 ; cited in Thomas, Die Physiologie des Menschen, p. 281, Leipzig, 1853. 186 DIGESTION. prevent return. The chymoiis mass is sufficiently soft to pass readily ; and the quantity of mucus poured out from the lining membrane facili- tates its course. When it has reached the large intestine, it first ac- cumulates in the caecum, which — being cellular or pouched like the colon — necessarily detains it for some time. In proportion, however, as the caecum becomes filled, the peristaltic action is extended from the small intestine, and the matter is sent into the colon, the cells of which are successively filled; first, those of the ascending, and then those of the transverse and descending colon, as far as the annulus or com- mencement of the rectum. The whole of its progress through the large intestine is slowly accomplished. Independently of the pouched arrangement, which retards it, a part of the colon ascends, so that the foecal matter must often proceed contrary to gravity. It becomes, moreover, more and more inspissated in its progress towards the out- let ; and the peristaltic action recurs at greater intervals than in the upper portions of the tube. The importance of such a reservoir as the large intestine is obvious. "Without it, we should be subjected to the inconvenience of evacuating the fasces incessantly. Before the excrementitious matter reaches the lower portion of the small intestine, it has not the full fiscal odour; but acquires it after having remained there for a short time. The brownish-yellow hue becomes deeper ; but its consistence, smell, and colour, vary consider- ably, according to the character of the alimentary matter ; the mode and degree in which chymification and chylification have been accom- plished ; the habit of the individual, &c. &c. The ftecal matter, as we find it, consists of the excrementitious part of the food, as well as of the juices of the upper part of the canal, that have been subjected to the digestive process ; of the secretions, poured out from the lower part of the intestine, and also, of substances, that have escaped the digestive actions of the stomach and small intestine, and are often per- ceptible in the evacuations. The peculiar fiecal impregnation is pro- bably mainly dependent upon a secretion from appropriate follicles; and we can thus understand, if we take into consideration the digestion of the different secretions, why ftecal evacuations may exist, when the individual has not eaten for some time, or taken but little nourishment. Professor Bcrard,' however, is of opinion, that it is the bile, more than any other liquid poured into the intestine, which gives the excrements their special characters, and especially the fiBcal odour, and Leuret and Lassaigne had already remarked, that if bile be heated, it gives off a faecal smell. Some phj^siologists have believed, that chylification takes place even in the large intestine, and that chylous absorption is more or less effected there. M. Viridet^ asserted, that the cxecum is a second sto- mach, in which a last effort is made to separate from the food the digestible and soluble portions it may still contain. In herbivorous animals, according to him, an acid solvent is secreted in it. MM. Tiedemann and Gmelin seem to admit the fact; and likewise tliink, that the fluid, secreted by the inner membrane of the intestine, assists ' Cours de Physiologie, ii. 373, Paris, 1S49. * Tractatus Novus de Prima Coctione, &c., Genev,, 1691. ACTION OF THE LARGE INTESTINE. 187 in the assimilation of tlie food by means of the albumen it contains, and that ftecal matter is formed there. From various experiments instituted by Professor Schultz/ of Berlin, he infers, that the food in the caecum becomes not only a second time sour, but that the acid chyme is there neutralized by the access of bile in the same way as in the duodenum. M. Blondlot,^ however, states, that in many herbi- vorous animals and granivorous birds, as sheep, goats, pigeons and chickens, the contents of the caecum were never acid unless sugar in some form had been mixed with their food. The acidity of the caecum which then ensues, he thinks is the result of that part of the starch or sugar, which had not been absorbed in the small intestine, being trans- formed into lactic acid. The fact of the separation of chyle in the caecum and colon is proved by the experiments of M. Voisin,^ which consisted in introducing food into these intestines after the ileo-caecal valve had been closed by ligature. The physical characters of the feces have been already described. When extruded, they have the shape of the large intestine, or of the aperture, through which they have been evacuated. If the form of either of these be modified, that of the excrement will be so likewise. In stricture of the colon — especially about the sigmoid flexure — and of the rectum, the fseces are squeezed through the narrowed portions, and often evacuated in the shape of ribands. The biliary secretion appears to modify the appearance of the fieces greatly. If, as in jaundice, it be prevented from flowing into the intestine, they are clay -coloured. M, Adelon'* affirms, that, under such circumstances, they are more fre- quent. This is not the result of our experience, nor does it appear to be deduced from his own; as, a few pages before, he remarks, "it is certain, that if the bile does not flow, the excrements are dry, devoid of colour, and there is constipation." On the other hand, if the bile flows in too great quantity the fa3ces are darker coloured. It is doubt- ful, whether the varying quantity of the biliary secretion have much influence on the number of evacuations, unless the canal, through which it has to pass, is in a morbid condition. Many of the appear- ances in the fasces, which are conceived to be owing to a morbid con- dition of the biliary secretion, are the effect of admixture with products of morbid changes in the stomach or intestines. In elucidation of this, it may be observed, that the green evacuations of children are often referred to some pathological condition of the biliary secretion; whereas the colour is commonly owing to unusual formation of acid in the stomach, the admixture of which with healthy bile produces the colour in question. The chemical properties of the faeces have been repeatedly inquired into. They must, of course, vary according to the nature of the food, its quantity, the kind of digestion, &c. Human fasces were examined by Eawitz* after animal and vegetable food had been taken. But few ' London Med. and Surg. Joum., Oct. 31, 1835 ; cited in American Journal of tlie Medical Sciences, Nov., 1836, p. 203. ^ Traite Analytique de la Digestion, p. 103, Paris, 1844. ^ Nouvel Aper.u sur la Physiologie du Foie, &c., Paris, 1833. ■• Op. citat. ^ Ueber die Einfaclien Nahruntrsmittel. Breslau, 1846, cited by Kirkes and Paget, Manual of Physiology, 2d Amer. edit., p. 176, Philad., 1853. 188 DIGESTION. fragments of muscular tissue were met with; but the cells of cartilage and iibro-cartilage — excepting those of fish — were found unchanged. Elastic fibres and fatty matters, which had escaped absorption, appeared to be unchanged; for fat cells were sometimes unaltered in the fieces; and crystals of cholesterin might generally be obtained from them, especially after the use of pork fat as diet. Of vegetable aliments, large quantities of cell membrane were unal- tered; and starch cells were commonly deprived of only part of their contents; the green colouring matter — chlorophyll — was unaffected, and the walls of sap vessels and spiral vessels were usually found in large quantities in the faeces, — their contents having been probably removed durino; digestion. The average quantity of faecal matter discharged by the adult in the twenty-four hours, has been estimated at about five or six ounces.' Wehsarg,^ indeed, makes it less than this. The mean of seventeen ob- served cases was not much more than four ounces ; so that if, accord- ing to the diet-scale of the Navy of the United States,^ forty-five ounces of solid food are taken in the twenty-four hours, about forty ounces must be appropriated by the system daily. The discharged five ounces of fasces consist, almost wholly, of substances that are rebellious to the action of the gastric and intestinal secretions. It is estimated, that aa much as seventy-five per cent, of the fteces is water, so that the solid matter in them is not, probably, more than an ounce, or an ounce and a half. The faeces differ in each animal species. Those of the herbivora con- tain less animal matter than those of the carnivora and omnivora; and the agriculturist is well aware, that the excrements of all animals are not equally valuable as manure. The dung of the pigeon is alkaline and caustic ; and hence has been employed in tanning for softening skins. The excrement of dogs, that have fed only on bones, is white, and appears to be almost wholly composed of the earthy matter of bone. It has not, however, been examined by modern chemists. This white excrement is the album grcecum, cynocoprus^ spodiwin Grcecoruni^ album cams or stercus caninwm album, of the older writers. It was formerly employed as a discutient in quinsies, and as an anti-epileptic agent, but is now justly discarded. M. Vauquelin,'* on comparing the nature and quantity of the earthy parts of the excrements of fowls with those of the food on which they subsisted, arrived at some results that are of interest to the physiolo- gist. He found that a hen devoured, in ten days, lilll"8-i8 grains troy of oats. These contained of phosphate of lime 136*509 grains; and of silica 219-548 grains; in the whole 356-057 grains. During these ten days she laid four eggs, the shells of which contained 98*779 grains of phosphate, and 58*191 grains of carbonate of lime; and * Todd and Bowman, Physiological Anatomy, &c. Pt. iv. Sect. i. p. 267, Lond. 1852; and Budfije, Memoranda der Speciellen Pliysiologie des Menschen, 5te Autiage, S. 99, Weimar, 1853. 2 Mikroskopische und Cliemisclie Untersuclmngen der Fseces Gesunder Erwachsener Menschen, Giessen, 1853 ; and Scherer in Canstatt's Jahresbericht, 1853, S. 121 ; see, also, Ehring, ibid. ; and Marcet, Proceedings of the Royal Society, June 15, 1854. * See page 119. * Annales de Chimie, tom. xxix. p. 3. ACTION OF THE LAEGE INTESTINE. 189 passed 185.266 grains of silica. The fixed parts, thrown out of the system during the time, consisted of: — Phosphate of lime, 274*305 grains. Carbonate of lime, ........ 511"911 Silica, 185-206 Given out, 971-482 Taken in, 356-057 Surplus, 615-425 The quantity of fixed matter, therefore, given out of the system in. ten days, exceeded the quantity taken in by this last amount. Tlie phosphate of lime, taken in, amounted to . . . 136*509 grains. That given out, to 274-305 137-796 There must, consequently, have been formed 137.796 grains of phos- phate of lime, besides 511.911 grains of the carbonate. The inferences, deduced from these experiments, were, that lime, and perhaps also phosphorus, is not a simple substance, but a compound formed of in- gredients that exist in oats, water, or air ; the only substances to which the fowl had access ; and that silica must enter into its composition, as a part had disappeared. Before, however, we adopt these conclusions, the experiments ought to be repeated more than once. The chicken should be fed on oats some time before the excrements and shells are subjected to analysis; as the carbonate of lime, and the excess of phos- phate detected on analysis, might have proceeded, not only from the food, but from earthy matters previously swallowed. Care should also be taken, that it has no access to any calcareous earth; and w^e must be certain, that it has not diminished in weight; as, in such case, the earth may have been supplied from its own body. These precautions are the more requisite, seeing, that experiments have shown, that cer- tain birds cannot produce eggs unless they have access to calcareous earth. There are some very remarkable instances of chemical changes, in mysterious actions more immediately concerned in the decomposition and renovation of the frame; or, in what has been abstractedly termed — the function of nutrition. Dr. Henry' has announced, that the following substances have been satisfactorily proved to exist in healthy urine ; — water, free phosphoric acid, phosphate of lime, phos- phate of magnesia, fluoric acid, uric acid, benzoic acid, lactic acid, urea, gelatin, albumen, lactate of ammonia, sulphate of potassa, sul- phate of soda, fluoride of calcium, chloride of sodium, phosphate of soda, phosphate of ammonia, sulphur, and silex; — yet we have no proof that these substances are obtained from any other source than the food ; and some of them are with difficulty obtained any where. Every one of them is necessary for the constitution of the urine; and many must be formed by a chemical union of their elements under the vital agency. Some are met with in the animal body exclusively. ' Elements of Chemistry, 9th edit., ii, 435, Lond., 1823. 190 DIGESTION. Berzelius^ found, in 100 parts of human fosces: — water, 73-3 ; unal- tered residue of animal and vegetable substances, 7'0 ; bile, 0*9 ; albu- men, 0*9; peculiar extractive matter, 2'7; substance, formed of altered bile, resin, animal matter, &c., 14 ; salts, 1-2. Seventeen parts of these salts contained, of carbonate of soda, 5; chloride of sodium, i; sul- phate of soda, 2 ; ammoniaco-magnesian phosphate, 2 ; phosphate of lime, 4. The excrements have likewise been examined by MM. Leuret and Lassaigne, and others ; but none of the analyses have shed much light on the physiology of digestion. Analyses of the ashes of firm human feces by Enderlin^ yielded the following results: — chloride of sodium and alkaline sulphate, 1-307; tribasic phosphate of soda, 2-633 ; phosphate of lime, and phosphate of magnesia, 81-272; phosphate of iron, 2-091 ; sulphate of lime, 4-56 ; silica, 7-97. In the large intestine, gases are met with, along with the feeces. These were examined by MM. Magendie' and Chevreul in the three criminals already referred to (page 174). The results accord with those of Jurine,^ obtained long ago, as regards the nature of the gases; but they do not correspond with what he says relating to the carbonic acid, the quantity of which, according to him, goes on decreasing from the stomach to the rectum. The analyses of MM. Magendie and Chevreul show, that the proportion instead of decreasing, increases. Concerning the origin of these gases, the remarks made on those in the small intestine are equally applicable here. Marchand made two analyses of air discharged from the rectum. These yielded carbonic acid, 44-5 and 36'5; nitrogen, 14-0 and 29-0; hydrogen, 25'8 and 13-5; carburetted hj^drogen, 15-5 and 22*0; and sulphuretted hydrogen, 1.^ When the fecal matter has accumulated to the necessary extent in the rectum, its expulsion follows ; and to this function the term defeca- tion has been assigned. The faeces collect gradually in the large intes- tine, without any consciousness on the part of the individual. Sooner or later, the desire or want to evacuate them arises. This is usually classed among the internal sensations or desires. It is, however, of a mixed character. It is not always in a ratio with the quantity of fa3ces, as is shown by the fact, that occasionally the intestine is filled without the want arising; and, if the}^ be unusually thin or irritating, the desire is developed, when an extremely small quantity is present, — as in cases of tenesmus. The period, at which the desire returns, is variable, according to the amount and character of the food employed, as well as the habit of the individual. "Whilst the generality of per- sons evacuate the bowels at least once a-day, — and this at a period often regulated by custom, — others pass a week or two without any alvine discharge, and yet may be in perfect health. Nay, some of the collectors of rare cases^ have affirmed, on the authority of Ehodius, Panarolus, Salmuth, and others, that persons may remain in health, ' Traite do Cliimie, trad, par Jourdan et Esslinger, torn, vii., and Simon's Animal Cliemistry, Sydenham Society edit., ii. 372, Lond., 184(5, or Amer. edit., Philad., 1846. 2 Annaleu der Chemie und Pharmacie, Mars, 1844, cited by Mr. Paget, Brit, and For. Med. Kev., Jan. 1S45, p. 277. 3 Precis, &c., ii. 126. * Memoir, de la Soc. Royale de Med., x. 72. " Rudolph Wagner's Lehrbuch der Speciellen Physiologic, Iste Lieferuug, S. 228, Leipz., 1854. ^ Art. Cas Rares, in Diet, des Sciences Medicales. DEFECATION". 191 with tlie bowels moved not oftener than once a month, three months, half a year, two years, and even seven years ! Sir Everard Home^ refers to the case of General Grose, who was in the Dutch service, under the Duke of Cumberland, in the Flanders war; and who for thirty years had no passage through the bowels. General Gage noticed that he ate heartily; but in two hours left the table and re- jected his meal. He was healthy, and capable of exercise like other men. Dr. Heberden^ mentions the case of a person, who had naturally an evacuation once a month only; and another who had twelve eva- cuations every day during thirty years, and then seven every day for seven years, and grew fat rather than otherwise. A young lady, re- ferred to by M. Fouteau,^ had no evacuation for upwards of eight years ; although during the last year she ate abundantly of fruit, and drank coffee, milk, tea, and broth with yolks of eggs ; but she had copious greasy sweats; — and many similar extraordinary cases have been recorded by Dr. Chapman'' of Philadelphia. TVhen the desire to evacuate has once occurred, it generally persists until the fasces are expelled. Sometimes, however, it disappears and recurs at an uncer- tain interval; and, if again resisted, may become the source of pain, and ultimately command implicit obedience. That the pressure and irritation of the fteces develope the sensation is evidenced by the fact, that the momentary relief experienced at times, when the desire is urgent, is usually accompanied by a manifest upward return of the faecal matters from the sigmoid flexure into the colon. In evacuating the fteces, the object to be accomplished is, — that the contents of the large intestine shall be pressed upon with a force supe- rior to the resistance presented by the annulus or upper extremity of the contracted rectum, and the muscles of the anus. The contraction of the rectum is generally insufficient to effect this last object, notwith- standing the great thickness of its muscular layer. In cases, however, of irritability of the rectum, the sphincter is incapable of resisting the force developed by the proper muscular fibres of the gut. Under or- dinary circumstances, the aid of the diaphragm and abdominal mus- cles is invoked, and it is chiefly through these muscles, that volition influences the act of defecation, — suspending, deferring, or accelerating it, as the case may be. After a full inspiration, the muscles that close the glottis ; and the expiratory muscles, — especially those of the ante- rior part of the abdomen, — contract simultaneously. The air cannot escape from the lungs ; the diaphragm is depressed upon the abdo- minal viscera, and the whole thorax presents a resisting body ; so that all the expiratory power of the muscles bears upon the viscera, and presses them against the vertebral column. In this way, considerable force is exerted upon the contents of the colon and rectum ; the resistance of the sphincter, — already diminished by the direct exercise of volition, — is surmounted ; it yields, and the fasces are extruded. The levator ani and ischio-coccygeus, aided by the transversus perinei muscle, support the^ anus during the expulsory efforts, and restore it ' Lect. on Comp. Anat., v. 12, Lond., 1828. 2 Commentarii, p. 14. 3 ffiuvres Posthumes, i. 27, Paris, 1783. * Lectures on the more important Diseases of the Thoracic and Abdominal Viscera, p. 294, PhiLad., 1844. 192 DIGESTION. to its place after tbe efforts have ceased. Astruc maintained, that the abdominal muscles had nothing to do with the act of defecation, which gave occasion to the jocose remark of Pitcairn/ — "Mihi videtur Astruccium nunquam cacasse alioquin sensisset musculos abdominis et se contrahere et alia exprimere posse." Whilst straining is effected by the diaphragm and abdominal mus- cles, the longitudinal muscular fibres of the rectum contract, so as to shorten the intestine, and, consequently, the space over which the fgeces have to pass. At the same time, the circular fibres contract from above to below, so as to propel the excrement downwards, and to cause the mucous membrane to extrude, and form a ring or hour- relet, like that which occurs at the cardiac orifice of the stomach, when the food is passing from the oesophagus into that organ. If this ex- trusion occurs to a great extent, it constitutes the disease called prolapsus ani. Dr. O'Beirne,^ of Ireland, guided by the following facts and argu- ments ; — that great irritation would be produced in the sphincter ani, and bladder, if the fteces descended readily into the rectum ; — that the difficulty experienced in throwing up an injection is inconsistent with the idea of the gut being open, and proves that it is firmly contracted and closed; — that when the surgeon has occasion to pass his finger up the rectum, he rarely encounters either solid or fluid fseces; — that the two sphincter muscles of the anus are weakened in certain diseases, and divided in operations, and yet it rarely happens, that the power of retaining the fieces is destroyed; — that on passing a stomach-tube to the height of half an inch up the rectum, in a number of healthy per- sons, it was found, that nothing escaped, and that the tube could be moved about freely in a space, which, on introducing the finger, was ascertained to be the pouch of the rectum ; but that from the highest part of the pouch to the upper extremity of the gut — generally a distance of from six or seven to eight inches — it could not be passed upwards without meeting with considerable resistance, and without using a degree of force to mechanically dilate the intestine, which was plainly felt to be so contracted as to leave no cavity for this extent; — ■ that when the instrument reached, in this way, the highest point of the rectum, the resistance to its passage upward was felt to be sensibly increased, until, at length, by using a proportionate degree of pressure, it passed rapidly forward, as if through a ring, into a space in which its extremity could be moved with great freedom, and as instantly a rush of flatus, of fluid fgeces, or of both, took place through the tube; — and that in every instance, where the tube presented the least appear- ance of fieces after being removed, this appearance was confined to that portion which had entered the sigmoid flexure : — guided by these and other facts. Dr. O'Beirne concluded, that in the healthy and natural state, all the part of the rectum above its pouch is at all times, with the single exqeption of a few minutes previous to the eva- cuation of the bowels, firmly contracted, and perfectly empty, at the ' Opuscula medica (Lector) Roterodam, 1714. 2 New Views of the Process of Defecation, &c., Dublin, 1833 ; reprinted in this country, Washington, 1834. DEFECATION. 193 same time that tlie poucb. itself, as well as tte sigmoid flexure of the colon, is always more or less open, and pervious, — and that the sphincter ani muscles are but subsidiary agents in retaining the faeces. When the fasces are firm, considerable muscular effort is necessary to expel them; but when they are of a softer consistence, the contraction of the rectum is sufficient. The sphincters — as elsewhere shown — afford examples of reflex action. After sensation and volition are suspended, they contract under direct irritation. Yet, like the respiratory muscles, they are of a mixed character, — partly voluntary and partly involuntary. They are involuntary, but capable of being aided or impeded by a voluntary effort. The state of gentle contraction, in which they constantly are, is evidently dependent upon their connexion with the spinal cord ; for the experiments of Dr. Marshall Hall have exhibited, that it ceases, when the connexion is destroyed. Air, contained in the intestinal canal, readily moves about from place to place, and speedily reaches the rectum by the peristaltic action alone. Its expulsion, however, is commonly accomplished by the aid of the abdominal muscles ; when it issues with noise. If dis- charged by the contraction of the rectum alone, it is generally in silence. Children are extremely subject to flatulence; in the adult it is not so common. Certain kinds of diet favour its production more than others, especially in those of weak digestive powers, of which condition its undue evolution is generally an indication. The legu- minous and succulent vegetables in general belong to this class. Where digestion is tardily accomplished, they give occasion to the copious disengagement of gas. Too often, however, the disgusting habit of constantly discharging air streperously from the bowels is encouraged, rather than repressed; and there are persons, who are capable of effecting the act almost as frequently as they attempt it. The noise, made by the air, as it passes backwards and forwards in the intestinal canal, constitutes the affection called horlorygmus. So much for the digestion of solid food. In so delicate and compli- cated an apparatus, it would seem, that mischief ought more frequently to result from the various heterogeneous substances that are received into the digestive tube. Its resistance, however, to morbific agencies is astonishing. In the Museum of the Boston Society for Medical Im- provement^ an open penknife is preserved, which was swallowed b}^ a child between three and four years of age, and passed from the bowels after the expiration of fifty-one hours; the child, in the meantime, playing about as usual, and not seeming to suffer. The story of the lunatic, under the care of Dr. Fox of Bristol, who swallowed "some inches" of a poker, which came away without any suffering, is regarded as authentic;^ and there is no question in regard to the authenticity of the case of the sailor recorded by Dr. Marcet,^ who swallowed a num- ' J. B. S. Jackson, A Descriptive Catalogue of the Anatomical Museum of the Boston Society for Medical hnprovement, p. 158, Boston, 1847. 2 Southey, The Doctor, iv. 297, Lond._, 1837. ^ Medico-Chirurgical Transactions, xii. 52, Lond., 1822. VOL. I.— 15 194 DIGESTION". ber of clasp knives witli impunity, but ultimately fell a victim to his idle temerity, — having swallowed, in the whole, thirty-seven ! 5. DIGESTIOIf OF LIQUIDS. In inquiring into the digestion of liquids, we shall follow the same order as that observed in considering the digestion of solids ; but as many of the acts are accomplished in the same manner, it will not be necessary to dwell upon them. Thirst or the desire for drink is an internal sensation ; in its essence resembling that of hunger, although not referred to the same organs. It arises from the necessities of the system ; from the constant drain of the fluid portions of the blood; and is instinctive or essentially allied to organization.' The sensation differs in different persons, and is rarely alike in the same. Usually, it consists of a feeling of dryness, constric- tion, and heat in the back part of the mouth, pharynx, oesophagus, and occasionally in the stomach; and, if prolonged, redness and tumefaction of the parts supervene, with a clammy condition of the mucous follicu- lar — and diminution and viscidity of the salivary — secretions. These phenomena are described as being accompanied by restlessness, general heat, injected eyes, disturbed mind, acceleration of the circulation, and short breathing, the mouth being frequently and largely open, so as to admit the air to come in contact with the irritated parts, and thus afford momentary relief. Thirst is a very common symptom of febrile and inflammatory dis- eases, in which fluid — especially cold fluid — is desired in consequence of the local relief it affords to the parched and heated membrane of the alimentary canal. It is also developed by extraneous circumstances, as in summer, when the body sustains considerable loss of fluid ; as well as in those diseases — dropsy, diabetes, &c. — which produce the same effect. There are many other circumstances, however, that excite it; — long speaking or singing; certain kinds of diet as the saline and spicy, — and especially the habit, acquired by some, of drinking fre- quently. Whilst individuals, thus circumstanced, may need several gallons a day to satisfy their wants ; — others, who have, by resistance, acquired the habit of using very little liquid, may be enjoying health, and not experiencing the slightest inconvenience from the privation of liquid ; so completely are M'e, as regards the character and quantity of our aliment, the creatures of habit. This privation, it is obvious, can- not be absolute or pushed beyond a certain extent. There must always be fluid enough taken to administer to the necessities of the system. As in the production of all sensations, three acts are required for accomplishing that of thirst; — impression, conduction, and perception. The last, as in every similar case, is effected by the brain ; and the second by the nerves passing between the part impressed and that organ. The act of impression — its seat and cause — will alone arrest our attention, and it will be found that we are still less instructed on these points than on the physiology of hunger. Even with regard to the seat of the impression, we are in a state of uncertainty. It appears to be chiefly in tlie back part of the mouth and fauces; but \vbether ' J. BC'clard, Traite Lleraentaire de Physiologie, p. 28, Paris, 1855. LIQUIDS. 195 primarily there, or experienced there by sympathy with the condition of the stomach, is by no means clear. The latter opinion, however, appears the more probable. In a remarkable case, published by Dr. Gairdner of Edinburgh, it was found impracticable to allay thirst by merely supplying the mouth, tongue, and fauces with fluid. A man had cut through the oesophagus. An insatiable thirst arose; several pailfuls of water were swallowed daily, and discharged through the wound Avithout removing the desire for drink; but on injecting water, mixed with a little spirit, into the stomach, it was soon quenched. That the sensation is greatly dependent upon the quantity of fluid cir- culating in the vessels is shown by the fact, mentioned by M. Dupuy- tren, that he succeeded in allaying the thirst of animals, by injecting milk, whey, water or other fluids into the veins; and M. Orfila states, that, in his toxicological experiments, he frequently allayed in this way the excessive thirst of animals, to which he had administered poison; and which were incapable of drinking, owing to the oesopha- gus having been tied. He found, also, in his experiments, that the blood of animals was more and more deprived of its watery portions as the abstinence from liquids was more prolonged.-' Like all other sensations, that of thirst arises from an inappreciable modification of the nerves of the organ: hence, all the hypotheses proposed to account for it have been mere fantasies undeserving of enumeration. The jyrehens ion of liquids differs somewhat from that of solids. The fluid may be simply poured into the mouth, or a vacuum may be formed in it: the pressure of the atmosphere then forces it in. When we drink from a vessel, the mouth is applied to the surface of the fluid; the chest is then dilated, so as to diminish the pressure of the atmo- sphere on the portion of the surface of the liquid intercepted by the lips; and the atmospheric pressure on the surface of the fluid in the vessel forces it into the mouth, to replace the air that has been drawn from the mouth by the dilatation of the thorax. In sucking^ the mouth may be compared to an ordinary syringe; the nozzle of which is repre- sented by the lips; the body by the cheeks, palate, &c., and the piston by the tongue. To put this in action, the lips are accurately adjusted around the body from which the liquid has to be extracted. The tongue is likewise applied, contracts, and is carried backwards ; so that an approach to a vacuum is formed between its upper surface and the palate. The fluid, no longer compressed equally by the atmo- sphere, is displaced, and enters the mouth. As neither mastication nor insalivation is required in the case of liquids, they do not remain long in the mouth, unless their temperature is too elevated to admit of their being passed down into the stomach immediately, or they are of so luscious a character, that their prolonged application to the organ of taste affords pleasure. Their deglutition is effected by the same mechanism as that of solids; and, as they yield readily to the slightest pressure, with less difficulty. Their accumula- tion in the stomach takes place in much the same manner. They arrive by successive mouthfuls; and, as they collect, the thirst disappears ' Adelon, Pliysiologie de I'lloiume, 2de edit., ii. 525, Paris, 1829. 196 DIGESTIOX. with all its local and general attendants. If, however, the organ be over-distended a disposition to vomiting is induced. The changes, which liquids undergo in the stomach, are of different kinds. All acquire the temperature of that viscus, and become mixed with the secretions from its internal surface, as well as from that of the supra-diaphragmatic portion of the digestive tube. Some, however, undergo the operation of chymification ; others not. To the latter class belong, — water, weak alcoholic drinks, the vegetable acids, &c. Water experiences the admixture already mentioned ; becomes turbid, and gradually disappears, without undergoing any transformation. Part passes into the small intestine ; the other is directly absorbed. When any strong alcoholic liquor is taken, the effect is different. Its stimulation causes the stomach to contract, and augments the secre- tion from the mucous membrane ; whilst, at the same time, it coagu- lates all the albuminous portions ; mixes with the watery part of the mucous and salivary fluids, and rapidly disappears by absorption ; hence, the speedy supervention of inebriety, or death, after a large quantity of alcohol has been taken into the stomach. The sub- stances, that have been coagulated by the action of the alcohol, are afterwards digested like solid food. We can thus understand the good effects of a small quantity of alcohol, taken after a substance difficult of digestion, — a custom which has existed from high antiquity, and has physiology in its favour. It is, in such cases, — to use the language of the eccentric Kitchener,' — a good "^^eris^aZ^/c j3ersz<.«(^r." Oil remains longer in the stomach than any other liquid, experiences little change there, but passes into the small intestine, where it forms an emulsion and enters the veins and chyliferous vessels. Milk, as is well known, coagulates in the stomach soon after it is swallowed, after which the clot is digested, and the whey absorbed. Yet the existence of coagula in the stomach is constantly regarded by the unprofessional as a pathological condition ! Where the liquid, aqueous or spirituous, holds in suspension the immediate principles of animals or vegetables, as gelatin, albumen, osmazome, sugar, gum, fecula, colouring matter, &c., there is reason to believe that they enter immediately into the veins of the stomach and small intestine, having become modified and rendered fit for assimilation by admixture with the gastric and intes- tinal secretions. The salts, united with these fluids, are taken up along with them. Ked wine, according to M. Magendie,^ first becomes turbid by admixture with the juices formed in, or carried into, the stomach ; the albumen of these fluids speedily undergoes coagulation, and be- comes flocculent; and, subsequently, its colouring matter — entangled, perhaps, with the mucus and albumen — is deposited on the mucous membrane of the stomach. The aqueous and alcoholic portions soon disappear. Liquids reach the small intestine in two forms; — in the state of chyme; and in their unaltered condition. In the former case, they proceed like the chyme obtained from solid food. In the latter, they ' Directions for Invigorating and Prolonging Life; or the Invalid's Oracle, &c., Amer. edit., from the 6th London, hy T. S. Barrett, New York, 1831. * Precis,4&c., ii. 143. EUMINATION. 197 undergo no essential cliange; being simply nnited with the fluids poured into the small intestine,' — the mucous secretions, bile and pancreatic juice. Their absorption goes on as they proceed, so that very little, if any, attains the large intestine. The mode in which they are expelled is the same as in the case of solids. 6. EEUCTATION, KKGUEGITATION, KUMINATIOIi, AND VOMITING. Although the contraction of the oesophagus generally prevents the return of matters from the stomach, occasionally this occurs, giving rise to eructation, regurgitation, or vomiting. a. Eructation. — Eructation or belching is the escape of gas from the stomach. If air exists in the organ, it is necessarily situate near the cardiac orifice. When the aperture relaxes, it passes out, and, unless forced back by the contraction of the oesophagus, speedily reaches the pharynx, causing the edges to vibrate, hence the sound by which it is accompanied. b. Regurgitation. — If, instead of air, liquid or solid food ascends from the stomach into the mouth, the action is called regurgitation. Of this we have an instance in the puking of the infant at the breast; and in the adult, when the stomach is surcharged. Occasionally, too, it occurs when the organ is empty, — in the morning, for example, — when it is frequently preceded by eructations, by which the air, contained in the organ, is got rid of. The mode in which it takes place is analo- gous to that of eructation. The substances, contained in the stomach become accidentally engaged in the cardiac orifice, during the open state of the orifice, and the relaxation of the lower part of the oeso- phagus, owing to the direct pressure of the stomach on its contents, and the abdominal muscles contracting and compressing that viscus. When they have once passed into the oesophagus, the latter contracts upon them but inversely, or from below to above. In this way they ascend into the pharynx, and ultimately into the mouth. Generally, regurgitation takes place in an involuntary manner; but there are some who are capable of effecting it at will; and can discharge the con- tents of their stomachs at pleasure. To accomplish this, — a deep inspi- ration is taken, by which the diaphragm is forcibly depressed upon the stomach ; the abdominal muscles are then contracted so as to compress the organ ; and this effect is occasionally aided by pressing strongly with the hands on the epigastric region. When these efforts are simul- taneous with the relaxation of the lower third of the oesophagus, the alimentary matters pass into the oesophagus. This voluntary regurgi- tation seems to be what is called vomiting at pleasure. Professor Berard^ has remarked, that when food passes from the mouth into the pharynx, in the act of deglutition, the reflex action of the second stage precipitates it into the oesophagus without any act of the will ; but when food ascends from the oesophagus into the pharynx, it can be introduced at will into the mouth, or be swallowed, c. Rumination. — Some individuals have taken advantage of this power to chew the food over again, and subject it to a second degluti- tion. The function of rumination is peculiar to certain animals ; yet ' Cours de Pliysiologie, ii. 275 (note), Paris, 1S49. "198 DIGESTION". man has occasionally possessed it. Peyer,' as well as Percy and Lau- rent,^ has given numerous examples. The wife of afrottenr or rubber of the floors, in the establishment of the then Duke of Orleans — after- wards King Louis Phihppe — could bring up a glassful of water into her mouth immediately after she had swallowed it. Dr. Copland^ ap- pears to have seen more than one instance of human rumination, and he describes it as an affection rather to be courted than shunned, so far as resrards the sensations of the individual.'* Under usual circum- stances, according to him, rumination commences from a c^uarter of an hour to an hour and a half after a meal. The process is never accom- panied with the smallest degree of nausea, pain, or disagreeable sensa- tion. The returned alimentary bolus is attended with no unpleasant flavour; is in no degree acidulous [?] ; is agreeable; and masticated with additional pleasure, and greater deliberation than at first. The whole of the food swallowed at a meal is not returned in order to undergo the process ; but chiefly the part that has been insufficiently masticated. The more fluid portions are sometimes, however, regurgitated along with the more solid; and when the stomach is distended by a copious meal the fluid contents are frequently passed up to be again swal- lowed.* d. Vomiting. — This inverted action of the stomach, preceded — as it always is — by manifest local and general disturbance, cannot properly be regarded as within the domain of physiology. In the language of Haller, vomitus totus morbosus est. It is, however, so nearly allied to the phenomena we have just considered, and has engaged so much of the time of the physiologist, as well as pathologist, that it requires mention here. From regurgitation it differs essentially, — in the sensa- tion that precedes; the retching that accompanies; and the fatigue that generally succeeds it; in short, whilst in regurgitation no indispo- sition may be felt, in vomiting it is always present to a greater or less extent. The sensation of the desire to vomit is termed nausea. It is an inde- scribable feeling of general indisposition; sometimes accompanied with one of circumgyration, either in the head or epigastric region; trembling of the lower lip, and copious flow of saliva. Along with these signs, there is manifest diminution of the powers of the vascular and nervous systems ; hence the utility of nauseating remedies when these systems are inordinately excited. The causes, which produce nausea, show that it may be either an external or internal sensation. Those, that occasion it directly or externally, are emetics ; too great distension of the stomach, or the presence of food that disagrees by its quality; morbid secretions; reflux of bile from the duodenum, &c. All these are so many immediate irritants, which develope the sensation, ' Merycologia, &c., Basil, 1685. * Art. Merycisme, in Diet, des Sciences Medicales; and Berard, Cours de Pliysiologie, 13te livraison, p. 274, Paris, 1849. 3 Edition of De Lys's translation of Richcrand's Physiology. * See also Bifraud, Manuel de Ph^^siologie, p. 152, Paris, 1853. * An interesting case of rumination is citeil from tlie London Lancet, in the Phila- delphia Med. Examiner, p. 315, for May, 1845. On the sensible phenomena of rumi- nation, see Colin, Comptes Reudus, xxxv., 130, 1852; and Scherer, Canstatt's Jahres- bericht, 1852, S. 133. VOMITING. 199 as external sensations in general are developed. In other cases, the cause acts at a distance. Between the stomach and various organs oi the body, such extensive sympathetic relations exist, that if one be long and painfully affected, the stomach sooner or later sympathizes; and nausea, or vomiting, or both are induced. In many instances, in- deed, the cause is much more remote than this ; the sight of a disgust- ing object, an offensive smell, or a nauseous taste, will as certainly pro- duce the sensation as any of the more direct agents. To this class of causes belongs the nausea produced by riding in a carriage with the back to the horses, by swinging, and particularly by sailing on the ocean. How the motion, which obviously excites the nausea in these cases, acts, has been the subject of many speculations, especially as regards sea-sickness. Darwin' refers it to an association with some affection of the organs of vision, which, in the first instance, produces vertigo; and M. Bourru, in his French translation of the work of Gil- christ, " On the utility of sea voyages in the cure of different dis- eases," — ascribes it to irritation of the optic nerves, caused by the impossibility of fixing the eyes on objects soon after embarking. The objections to these views are, that it ought to be prevented by simply covering the eyes, and that the blind ought to be exempt from it, which is not the case. Dr. Wollaston^ attempted to explain it, by some change in the distribution of the blood ; — the descending motion of the vessel causing an accumulation in the brain, as it causes the mercury to rise in the tube of a barometer. But the explanation is too physical. The mercury, in an unyielding tube, is readily influ- enced by the motions of the vessel; but the blood in the living ani- mal is circumstanced far otherwise. It is under the influence of a vital force, which interferes greatly with the action of purely physical causes. Were it otherwise, we should be liable to alarming accidents, whenever the body is exposed to the slightest concussion. The generality of pathologists consider, that the first effect is upon the brain, the sensation being produced consecutively through the in- fluence of that organ on the stomach ; and it is difficult not to accord with this view; whilst it must be admitted, that the precise mode, in which it is effected — as in the case, indeed, of every other phenome- non of the nervous system, is beyond our cognizance. In nausea, pro- duced by the sight of a disgusting object, we have this catenation of actions somewhat more clearly evidenced. The impression is mani- festly conveyed to the brain by the optic nerves, and from that organ the sensation must emanate. It is probable, too, that when emetics are injected into the veins, the first effect takes place on the brain, and the stomach is affected secondarily. When the state of nausea, howsoever induced, continues for any length of time, it is usually followed by vomiting. The rejected mat- ters are generally from the stomach ; but if the retching or violent contractile efforts of the muscles concerned be long continued, the con- tents of the small intestine also form part ; hence, we account for the universality of the presence of bile in the rejected matters after an emetic has been taken. Its presence is, therefore, in the generality of • Zoonomia. iv. 252, 3d edit., Loud., IbOl. ' Philos. Trausact. for 1810. 200 DIGESTION. cases, no evidence of the person's being wliat is termed hilioics. The contents of the small intestine are returned into the stomach by the antiperistaltic action. The longitudinal fibres take their fixed point below, and contract from above downwards; so that the chymous mass is forced towards the upper part of the canal, whilst the circular fibres contract from below to above. In cases of colica ileus or iliac j^ccssion, the inverted action extends through the whole intestinal canal ; so that fecal matters, and even substances injected into the rectum, pass the ileo-crecal valve, and are discharged by the mouth. Of old, it was universally maintained, that vomiting is caused by the sudden and convulsive inverted contraction of the stomach ; and they, who admitted that the diaphragm and abdominal muscles take part in the action, looked upon them simply as accessories. Francis Bayle,* Professor in the LTniversity of Toulouse, in 1681, appears to have been the first who suggested, that the stomach is nearly passive in the act; and that vomiting is caused almost exclusively by the pressure exerted upon that organ by the diaphragm and abdominal muscles. His reason for the belief was founded on the fact, that having introduced his finger into the abdomen of a living animal whilst it was vomiting, he could not perceive any contraction of the stomach. In 1686, M. Chirac re- peated the experiment with similar results ; after which, the views of Bayle were embraced by many of the most eminent physiologists and pathologists, — Senac, Van Swieten, and Schwartz,^ and, at a later period, by the celebrated John Hunter,^ who maintained, that the contraction of the muscular fibres of the stomach is not essential to the act. Many distinguished physiologists ranged themselves on the opposite side. M. Littre maintained, that the stomach is provided with considerable muscular bands, capable of powerful contraction; and that vomiting, as in the case of ruminant animals, is often caused without the partici- pation of the abdominal muscles. We have seen, however, that the rumination of animals more resembles regurgitation. M. Lieutaud* argued, that, according to Bayle's theory, vomiting ought to be a vo- luntary phenomenon; that the stomach is too deeply seated to be com- pressed, so as to empty it of its contents, by the neighbouring muscles; and he details the singular case of a female, who, whilst labouring under an affection, forwdiich emetics seemed to be required, resisted the action of the most powerful substances of that nature. After her death, M. Lieutaud, feeling desirous to detect the cause of this resistance, had the body opened in his presence ; the stomach was found enormously distended, but its structure unaffected. He, consequently, inferred, that the stomach had become paralyzed from over-distension, and that the effect produced was similar to that, so often met with in the bladder, when it has been long and largely distended. This case seemed to prove to him, that the stomach is most concerned in the act of vomiting, as the abdominal muscles and diaphragm appeared healthy, and no obsta- cle existed to their contraction. It is singular, however, that emetics ' Prohlemata Medico-physica ot Medica, Hagje Comitis, 1678. * Ilaller, Elemeiita Physiol., lib. xix. ^ 4, Bern., 17o4. * Observations on certain parts of the Animal Economy, with Notes by Prof. Owen, Amer. edit., p. 121, Philad., 1840. * MOmoir. de PAcad. pour 1752, p. 223. VOMITING. 201 should not have excited the contraction of the diaphragm and abdominal muscles; especially as there is reason for believing, that many of them at least, under ordinary circumstances, are taken into the bloodvessels, and affect the brain first, and through its agency the muscles con- cerned in the act of vomiting. The case seems to have been one of unusual resistance to the ordinary effects of nauseating substances, and cannot be looked upon as either favourable or unfavourable to the views of Bayle. We find, that vomiting does not follow the exhibition of the largest doses of the most powerful emetics, if the energy of the nervous system be suspended by the inordinate use of narcotics, or by violent injuries of the head. M, Lieutaud farther remarks, that according to Bayle's theory vomiting occurs at the time of inspiration ; but this cannot be, as the lower part of the oesophagus is then contracted, and if the vomited matters could reach the pharynx, they would pass into the larynx. Dr. Marshall HalP has attempted, and successfully, to show, that the larynx is closed during vomiting; and has concluded, that the act is a modification of expiration, — or that the muscles of expiration, by a sud- den and violent contraction, press upon the contents of the stomach, and project them through the oesophagus. Perhaps — as Dr. Hall has re- marked — no act affords a better illustration of the action of the excito- motory or reflex system of nerves than this. If the upper part of the throat be tickled with a feather, vomiting results; but if the feather be passed too far down, deglutition is induced and not vomiting. The ex- citor nerves, in the former case, are the glosso-pharyngeal, and perhaps the fifth pair. When vomiting is caused by an emetic, the pneumogas- tric is the excitor. When the impression is first made on the brain, the stimulus must be conveyed by the medulla oblongata and medulla spinalis to the muscles concerned. Haller^ maintained the ancient doctrine, that the stomach, alone, is competent to the operation. His views were chiefly founded on his theory of irritability, which compelled him to admit contraction wherever there are muscular fibres; and on certain experiments of Wepfer,^ who asserted, that when he produced vomiting by mineral substances, he observed the stomach contract. The Acaderaie des Sciences of Paris, unsatisfied with the results of previous observations, appointed M. Duverney'' to examine into the question, experimentally and otherwise; who — although he did not adopt the whole theory of Chirac — confirmed the accuracy of the facts on which it rested. He demonstrated, that the stomach is but little concerned in the act; and that it is chiefly de- pendent upon the contraction of the diaphragm and abdominal muscles, which enclose the stomach as in a press, so that its contents are com- pelled to return by the oesophagus. On the other hand, in 1771, M. Portal,* in his lectures at the College of France, endeavoured to show, that the stomach is the great agent. He administered to two dogs arsenic and nux vomica, which produced vomiting. The abdomen was immediately opened; and, according to Portal, the contractile move- ' .Tournal of Science and Arts, xv. 388. * Loo. citat. * Cicut?e Aquaticre Historia, &c., Basil, 1679. * Memoir de I'Academ. pour 1700, Hist., p. 27. ' Courri d'Anatomie Medicale, Paris, 1S04. 202 DIGESTION. ments of the stomacli could be both seen and felt ; and it was noticed, that instead of the vomiting being dependent upon the pressure of the diaphragm on the stomach, it occurred at the time of expiration ; and was arrested during inspiration, because the depressed diaphragm then closes the inferior extremity of the oesophagus with such strength, that the contents cannot be forced into the oesophagus when we press upon the organ with both hands. The views of Portal were confirmed by the experiments of Dr. Haighton.^ lie opened several animals during the eftbrts of vomiting ; and states that he distinctly saw the contrac- tions of the stomach. In more recent times, the physiological world has been again agitated with this question. In 1813, M. Magendie^ presented to the French Institute tlie results of a series of experiments on dogs and cats, — animals, that vomit with facility. Six grains of tartrate of antimony and potassa were given to a clog, and, when he became affected with nausea, the linea alba was divided, and the finger introduced into the abdomen to detect the state of the stomach. No contraction was felt; the organ appeared simply pressed upon by the liver and intestines crowded upon it by the contracted diaphragm and abdominal muscles. Nor was any contraction of the stomach perceptible to the eye; on the contrary, it appeared full of air, and three times its usual size. The air manifestly came from the oesophagus, as a ligature, applied round the cardia, completely shut it oK From this experiment, M, Magendie inferred, that the stomach is passive in vomiting. A solution of four grains of tartrate of antimony and potassa in two ounces of water was injected into the veins of a dog; and, as soon as nausea took place, an incision was made into the abdomen, and the stomach drawn out of the cavity. Although the retching continued, the viscus remained im- movable ; and the efforts were vain. If, on the other hand, the anterior and posterior surfaces of the stomach were pressed upon by the hands, vomiting occurred, even when no tartrate was administered, — the pres- sure provoking the contraction of the diaphragm and abdominal mus- cles, and thus exhibiting the close sympathetic connexion, existing between those acts. A slight pull at the oesophagus was attended with a similar result. In another dog, the abdomen was opened ; the vessels of the stomach tied; and the viscus extirpated. A solution of two grains of tartrate of antimony and potassa in an ounce and a half of water was then injected into the veins of the animal, when nausea and fruitless efforts to vomit supervened. The injection was repeated six times: and alwaj^s with the same results. — In another dog, the stomach was extirpated, and a hog's bladder fitted to the oesophagus in its stead, containing a pint of water, which distended but did not fill it. The whole was then put into the abdomen; the parietes of which were closed by suture. A solution of tartrate of antimony and potassa was now injected into the jugular vein: nausea — and, afterwards, vomit- ing — supervened, and the fluid was forced from the bladder. — In an- other dog, the phrenic nerves were divided ; by which three-fourths of the diaphragm were paralysed; the dorsal being the only nerves of ' MeTQ-oirs of the Lond. Med. Society, vol. ii. , * Mcnioiw sur le Vomissemeut, Paris, 1813 ; and Pr6cis El^meutaire, edit, cit., ii. 152. VOMITING. 203 motion remaining untouched. When tartrate of antimony and potassa was injected into the veins of this animal, but slight vomiting occurred; and this ceased, when the abdomen was opened, and the stomach forcibly pressed upon, — In another dog, the abdominal muscles were detached from the sides and linea alba; — the only part of the parietes remaining being the peritoneum. A solution of tartrate of antimony and potassa was now injected into the veins: nausea and vomiting supervened; and, through the peritoneum, the stomach was observed immovable; whilst the diaphragm pressed down the viscera so strongly against the peritoneum, that it gave way, and the linea alba alone resisted. — In a final experiment, he combined the last two. He cut the phrenic nerves to paralyse the diaphragm ; and removed the abdominal muscles. Yo- miting was no longer excited. From these different results, M. Magendie decided, that vomiting takes place independently of the stomach; and, on the other hand, that it cannot occur without the agency of the diaphragm and abdominal muscles; and he concluded, that the stomach is almost passive in the act; — that the diaphragm and abdominal muscles, especially the first, are the principal agents; — that air is constantly swallowed at the time of vomiting, to give the stomach the bulk which is necessary, in order that it may be compressed by those muscles; and lastly, that the dia- phragm and abdominal muscles are largely concerned in vomiting, as is indicated by their evident and powerful contractions, and by the fatigue felt in them afterwards. In corroboration of his view, M. Ma- gendie refers to cases of scirrhous pylorus, in which there is constant vomiting, although a part of the tissue of the stomach has become of cartilaginous hardness, and, consequently, incapable of contraction. Clear as the results obtained by this practiced experimenter seem to be, they have been controverted; and attempted to be overthrown by similar experiments. Soon after the appearance of his memoir, M. Maingault^ laid before the Society of the Faculte de Medccine of Paris, a series of experiments, from which he deduced very different results. In all, vomiting was produced without the aid of the diaphragm and abdominal muscles. The vomiting was excited by pinching a portion of intestine, which acts more speedily than the injection of substances into the veins. The abdomen of a dog was opened, and a ligature passed round a portion of intestine, which was returned nito the abdo- men, and the Avound closed by suture : vomiting took place. All the abdominal muscles were next extirpated, — the skin, alone, forming the parietes of the cavity. This was brought together, and the vomiting continued. On another dog, three-quarters of the diaphragm were paralysed by the section of the phrenic nerves. The abdomen was now opened, and a ligature placed round a portion of intestine. Vomit- ing occurred. Lastly ; — these two experiments were united into one. The abdominal muscles were cut crucially, and removed; the phrenic nerves divided ; and the diaphragm was cut aw^ay from its fleshy por- tion towards its tendinous centre ; leaving only a portion as broad as the finger under the sternum. The integuments were not brought together ; yet vomiting continued. ' Memoire sur le Vomissement, Paris, 1813. 204 DIGESTION. As these results were obtained on numerous repetitions of the ex- periment, M. Maingault conceived himself justified in deducing infer- ences opposite to those of M, ISragendie, namely, — that the contraction of the diaphragm and abdominal muscles is only accessory to the act of vomiting; that the action of the stomach is its principal cause; — that the latter is not a convulsive contraction, which strikes the eye, but a slow, antiperistaltic action ; and that the only convulsive move- ment is the contraction of the oesophagus, which drags the stomach upwards. He adduces, moreover, various considerations in favour of his deductions. If the stomach, he asks, be passive, why does it pos- sess nerves, vessels, and muscular fibres? Why is vomiting more energetic, when the stomach is pinched nearer to its pyloric orifice ? Why are the rugas of the mucous membrane of the stomach, during vomiting, directed in a divergent manner from the cardiac and pyloric orifices towards the middle portion of the organ? If the diaphragm does all, why do we not vomit whenever that muscle contracts for- cibly ? Why does not the diaphragm produce the discharge of urine in paralysis of the bladder? Why is vomiting not a voluntary phe- nomenon? And, lastly, how is it that it occurs in birds, which have no diaphragm ? The minds of physiologists were of course distracted by these con- flicting results. M. Kicherand^ embraced the views of M. Magendie; and affirmed, that he had never observed contraction of the stomach ; and that it seemed to him the least contractile of any part of the intestinal canal. With regard to the experiments of M. ^^laingault, he considered, that the stomach had not been wholly separated from the surrounding muscles ; that the action of the pillars of the diaphragm, and the spasmodic constriction of the hypochondres are sufficient to compress the viscus ; that nothing is more difficult to effect than the section of the phrenic nerves below their last root ; and, moreover, such section does not entirely paralyse the diaphragm, as the muscle still receives twigs from the intercostal nerves and great sympathetic; that the cardia, being more expanded than the pjdorus, the passage of substances through it is rendered easy ; and that it is incorrect to say, that the cardiac orifice, during inspiration, is closed between the pillars of the diaphragm. Again, to object that, according to the theory of M. !^[agendie, vomiting ought to be a voluntary phenomenon, is a feeble argument; for it is admitted, that the muscles, which, at the time, compress the stomach, act convulsively. If the diaphragm, in paralysis of the bladder, cannot effect the excretion of the urine, it is because that reservoir is not favourably situate as regards the muscle ; and, lastly, the arguments deduced from birds, that they are capable of vomiting, although they have no diaphragm, is equally insufficient, for it is not absolutely necessary that it should be a dia- phragm, but any muscle that can compress the stomach. When the Memoir of M, Maingault was presented to the society of the Faculle de Mklecine^ M. Legallois and Professor Bdclard were named reporters. The experiments were repeated before them by M. Maingault ; but, instead of appearing contradictory to those of Ma- ' Nouveaux Elemens de Phjsiologie, 7eme edit., Paris, 1817. \ VOMITING. 205 gendie, these gentlemen declared, that they were not sufficiently mul- tiplied, nor sufficiently various, to lead to any positive conclusion. MM, Legallois and Beclard subsequently repeated and varied them ; and instituted others, from which they deduced corollaries, entirely conformable to those of M. Magendie ;^ and lastly, M. Begin^ boldly affirms, " without fear of being contradicted by facts, that there is no direct or authentic experiment, that demonstrates the activity of the stomach during vomiting :" — and he adds, " I have repeated the greater part of the experiments of Magendie ; he has performed all in presence of a great number of spectators, of whom I was one ; and I can say, with the commissioners of the Academie des Sciences, that I have seen, examined, touched, and my conviction is full and entire." Still, many eminent physiologists have adhered to the idea, that the stomach is the main agent in vomiting ; and among these was M. Broussais.^ He manifestly, however, confounded the phenomena of regurgitation with those of vomiting; which, we have endeavoured to show, are distinct. A case of wound of the left hypochondrium with escape of the sto- mach was described to the Academie Royale de Medecine, by M. Lepine, and reported upon by MM. Lagneau, Gimelle, and Bcrard,^ which confirms the views adopted by M. Magendie. During the whole of the period, that the stomach remained out of the abdominal cavity, there was no apparent contraction of the muscular fibres of the organ, and none of its contents were expelled, although the patient made violent efforts to vomit. As soon, however, as the stomach had been returned into the abdomen, the efforts were followed by the expulsion of its contents. M. Lepine confirms the observations of Magendie in another point. After each act of vomiting, the patient appeared to swallow air. "I observed him," says M. Lupine, "execute repeated acts of deglutition, each of which was accompanied by a noise, that seemed to be owing to the passing back of air."* On the whole, we are, perhaps, justified in concluding, that the an- cient doctrine regarding vomiting is full of error, and ought to be discarded; that the inverted action of the stomach, although not ener- getic, is necessary, — that the pressure, exerted on the parietes of the stomach by the diaphragm and abdominal muscles, is a powerful cause, — and that the more or less complete paralysis of the diaphragm, or destruction of the abdominal muscles, renders vomiting more feeble and more slow in manifesting itself. The deep inspiration preceding the act of vomiting, is terminated by the closure of the glottis: after this the diaphragm cannot move without expanding or compressing the ' Bulletin de la Faculte et de la Societe de Med., 1813, No. s,, and (Euvres de Le- gallois, Paris, 1824. * Traite de Therapeiitique, Paris, 1825. ^ Traite de Physiologie, etc, translated by Drs, Bell and La Roche, p. 345, Philad., 1832. * Bulletin de I'Academie Royale de Medecine, 1844. See cases cited in Pliilad. Med. Examiner, April 20, 1844, p, 92; also a case of Wound of Abdomen, in Amer. Journ. of the Med. Sciences, Oct. 1846, p. 379. * The case described by Lepine has, a.s properly remarked by Dr. Brinton, (Cyclop, of Anat. and Physiology, art. Stomach and Intestines, Pt. 40, p, 317, Lond., 1855,) "been strangely misquoted by many English authors." See Kirkos and Paget, Manual of Physiology, 2d Amer. edit., p, 180, Philad., 1853; and Carpenter, Principles of Human Physiology, Amer. edit., p. 96, Philad,, 1855. 206 ABSORPTION. air in the lungs. It, consequently, presents a resisting surface, against which the stomach may be pressed by the contracting abdominal mus- cles. The order of the phenomena seems to be as follows. The brain is affected directly or indirectly by the cause exciting vomiting ; — through the brain and medulla, the glottis is closed, and the diaphragm and abdominal muscles are thrown into appropriate contraction, and press upon the stomach ; this organ probably contracts from the pylorus towards the cardia ; and, by the combination of efforts, the contents are propelled into the oesophagus, and out of the mouth. These efforts are repeated several times in succession, and then cease, — to reappear at times. Whilst the rejected matters pass through the pharjmx and mouth, the glottis closes; the velum palati rises and be- comes horizontal as in deglutition ; but owing to the convulsive action of the parts, these apertures are less accurately closed, and more or less of the vomited matter passes into the larynx or nasal fossae. On account of the suspension of respiration impeding the return of blood from the upper parts of the body, and partly owing to the force with which the blood is sent through the arteries, the face is flushed, or livid, the perspiration flows in abundance, and the secretion of tears is largely augmented. CHAPTER 11. ABSORPTION. In the consideration of the preceding functions, we have seen the alimentary matter subjected to various actions and alterations; and at length, in the small intestine, possessed of the necessary physical con- stitution for the chyle to be separated from it. Into the mode in which this separation, — which we shall find is not simply a secerning action, but one of vital elaboration, — is effected, we have now to inquire. It constitutes the function of absorption, and its object is to convey the nutritive fluid, formed from the food, into the current of the circula- tion. Absorption is not, however, confined to the formation of this fluid. Liquids can pass into the blood directly through the coats of the containing vessel, without having been subjected to any elabora- tion ; and the different constituents of the organs are constantly sub- jected to the absorbing action of cells, by which their decomposition is effected, and their elements conveyed into the blood; whilst antago- nizing cells elaborate from the blood, and deposit fresh particles in the place of those that have been removed. These various substances, — bone, muscle, hair, nail, as the case may be, — are never found, in their compound state, in the blood; and the inference, consequently, is that at the very radicles of the absorbents and exhalants, the substance on which absorption or exhalation has to be effected, is reduced to its constituents, and this by an action, to which we know nothing similar in physics or chemistry ; hence, it has been inferred, that the opei-ation is one of the acts of vitality. All the various absorptions may be classed under two heads: — the external and the internal ; the former including those that take place CHYLIFEROUS APPARATUS. 207 on extraneous matters from the surface of the body or its prolongation — the mucous membranes; and tlie latter, those that are effected inter- nally, on matters proceeding from the body itself, by the removal of parts already deposited. By some physiologists, the action of the air in respiration has been referred to the former of these ; and the whole function of absorption has been defined; — the aggregate of actions, by which nutritive substances— external and internal — are converted into fluids, which serve as the basis of arterial blood. The function of respi- ration will be investigated separately. Our attention will, at present, be directed to the other varieties; and, first of all to that which occurs in the digestive tube. I. DIGESTIVE ABSORPTION. The absorption, effected in the organs of digestion, is of two kinds ; according as it concerns liquids of a certain degree of tenuity, or solids. The former, it has been remarked, are subjected to no digestive action, but disappear chiefly from the stomach, and in part from the small intestine. The latter undergo conversion, before they are fitted to be taken up from the intestinal canal. a. Absorption of Chyle or Chyhsis. 1. ANATOMY OF THE CHYLIFEKOUS APPARATUS. In the lower animals, absorption is effected over the whole surface of the body, both as regards the materials necessary for nutrition and the supply of air. No distinct organs for the performance of these functions are perceptible. In the upper classes Fig- 54. of animals, how- ^~J ^~"^ ever, we find an apparatus, mani- festly intended for the absorption of chyle, and con- stituting a vas- cular communica- tion between the small intestine and left subclavian. Along this chan- nel, the chyle passes, to be emp- tied into that ve- nous trunk. The chyliferOUS Chyliferous Vessels. . apparatus consists of chyliferous vessels, mesenteric glands, and thoracic duct. The chy- liferous vessels or lacteals arise from the inner surface of the small intes- tine ; — in the villi, which are at the surface of, and between, the valvulee conniventes. Prof. E. H. Weber' has, however, seen them distributed ' Miiller's Archiv., u. s. w., s. 400, Berlin, 1847. 208 ABSORPTION". in tlie interspaces between the villi ; the lacteals and bloodvessels form- ing a close network; but he could not detect them in the parietes of the follicles of Lieberkuhn. Their origin is almost imperceptible; and, accordingly, the nature of their arrangement has given occasion to much diversity of sentiment amongst anatomists. Lieberkiihn^ affirms, that, by the microscope, it may be shown that each villus terminates in an ampullula or oval vesicle, which has its apex perforated by lateral orifices, through which the chyle enters ; and Bruch^ affirms, that there is a ceecal ampulla or excavation in the tissue at the extre- mity of each villus, in which its lacteal commences ; but he does not regard the ampulla as perforated. The doctrine of open mouths of lacteals and Ij^mphatics was embraced by Hewson,^ Sheldon,"* Cruikshank,^ Hedwig,* and Bleuland,^ and by some of the anatomists and ]3hysiologists of the present day ;' but, on the other hand, it has been contested by Mascagni,' and others ; whilst Eudolphi,^° Meckel,'^ and numerous others'^ believed, that the lacteals have not free orifices; but that in the villi, in which absorption is effected, a spongy or sort of gelatinous tissue exists, which accomplishes absorption, and, being continuous with the mouths of chyliferous ves- sels, conveys the product of absorption into them, a view not unlike that of Professor Briicke to be mentioned presently. Bich at conceived them to commence by a kind of sucker or absorbing mouth, the action of which he compared to that of the puncta lachrymalia or of a leech or cupping-glass ; and lastly, — from the observation, often made, that different coloured fluids, with which the lymphatics have been injected, have never spread themselves, either into the areolar tissue, or the parenchyma of the viscera, — M. Mojon,^-' of Genoa, affirmed, that lym- phatics have no patulous orifice, and that they take their origin from a cellular filament, which progressively becomes a villosity, an areolar spongiole, a capillary, and, at length, a Ijnnphatic trunk ; — the absorbent action of these vessels being a kind of imbibition. Professor Miiller''' affirms, that he has never perceived any opening at the extremity of the villi : in his earlier examinations, he was unable to see appearances of foramina on any part of their surface ; but he has observed, in por- tions of the intestines of the sheep and the ox, which had been exposed for some time to the action of water, that over the whole surface of ' Dissert, de Fabric. Villor. Intest. (passim.) Lugd., Bat., 1745. * Siebold and KiiUikcr's Zeitschrift, April, 1853. ' Experimental Inquiries ; edited by Falconer, Lond., 1774, 1777, and 1780, or Hew- son's Works, Sydenham Society's edit., p. 181, Lond., 184(3. * Tlie History of the Absorbent System, &c., p. 1, Lond., 1784. ^ Anatomy of the Absorbing Vessels, 2d edit., Loud., 1790. * Disquisit. AmpuU. Lieberkiihnii, Lips. 1797. " Exper. Auatom., 1784; aud Descript. Vasculor. in Intestinor. Teuuium Tunicis, Ultraj., 1797. * See Ileule, Allgemeine Anatomic, u. s. w. s. 5(59, Leipz., 1841. ^ Vasorum Lymphaticorum Corporis Humani Historia, &c., Senis, 1787 ; and Pro- dromo d'un Opera sul Sistemo de Vase Linfatice, Siena, 1784. '" Anatomisch. Physiologisch. Abhandluug., Berlin, 1802. " Handbuch, u. s. w. translated by Jourdan and Breschet, p. 179, Paris, 1805. '^ F. Arnold, Lehrbuch der Plivsioloifie des Menschen, Zurich, 1836-7 ; noticed in Brit, and For. Med. Rev., Oct., 1839, p. 479. " Journal de la Societe des Sciences Physiques, &c., Nov., 1833. " Handbuch der Physiologie, u. s. w., and Baly's translation, p. 269, Lmd., 1838. CHYLIFEEOUS APPARATUS. 209 the villi indistinct depressions were scattered, which might be regarded as oblique openings. He adds, however, that he makes this observa- tion with great hesitation and distrust. Fig. 55. Chyliferous Apparatus. A, A. A portion of the jejnnnm. h,h,h,h. Superficial lacfpals. c, c, c. Mesentery, d, d, d. First row of mesenteric glands. e,e,e. Second row. /,/. Keceptaculum chyli. g. Thoracic duct. h. Aorta, t, t. Lymphatics. In conversation with the author, in July, 1854, he expressed the same views in regard to the closed condition of the villi, and his con- sequent dissent to those promulged by Professor Briicke,' of Vienna, who affirms, that the epithelial cells covering the villi are open towards the intestine ; the apertures being covered with a mucous {scldeimig) substance ; and at the opposite surface they open into the lacteals, which he regards, at their commencement, as mere cavities in the centre of the villus without any distinct walls, the true lacteals originating from these spaces in the substance of the villi. Prof. Briicke's views are also con- ' Ueber die Cliylusgefiisse uud die Resorption des Clijlus, Wieii, 1853. VOL. I. — 14 210 ABSORPTION. tested by Kcilliker, Bruch, Henle/ and others; and if we admit, with him, that such an arrangement might enable us to explain more readily how fatty and insoluble substances pass into the circulation ; the dif- ficulty which applies to every doctrine of the open mouths of the chy- liferous vessels, as to the mode in which chylosis is accomplished, would still remain. As hereafter remarked, instead of any act of elaboration being executed, the chyle would necessarily have to be formed in the alimentary canal. Professor Briicke, it is true, states, that as the chjde in the villi surrounds the bloodvessels, an interchange of some of the elements takes place; the blood gives fibrin to the chyle; and the chyle a portion of its soluble materials to the blood.^ It has been elsewhere remarked (page 85), that numerous muscular fibre-cells have been observed in the villi, — an arrangement which accounts anatomically for the movement observed in them by difierent histologists. The marginal illustration. Fig. 57, from Krause, exhibits the appear- ance presented by the incipient chyliferous vessels in the villi of the jejunum of a young man, who had been hanged soon after taking a full meal of farinaceous food. The Fig- 57. chyliferous vessel issuing from each villus appeared to arise by several small branches, in some of which free extremities could be traced, whilst others anastomosed with each other. The arrangement of the differ- ent anatomical constituents i? well seen in Fig. 56, which re- presents an injected intestinal villus of a cat, which was killed during digestion. When they become perceptible to the eye, they are observed as in Fig. 54, communicating frequently with each other; and forming a minute network, first between the muscular and mucous mem- branes, and afterwards between the muscular and peritoneal, until they terminate in larger trunks, a, a, a, a. When they attain the point at which the peritoneal coat quits the intestine, they also leave it; creep for an inch or two in the sub- stance of the mesentery ; and enter a first row of mesenteric glands. From these they issue, of a greater size and in less number ; proceed still farther along the mesentery, and reach a second row, into which they enter. From these, again, they issue, larger and less numerous; anastomosing with each other; and proceeding towards the lumbar portion of the spine, where they terminate in a common reservoir, — ' Canstatt's Jahresliericlit, 1853, Ister Band. s. 24, Wiirzburg, 1854. 2 For an abstract of Prof. Briicke's views, see a note by Dr. I)a Costa, in his Amer. edit, of KoUiker's Manual of Unman Histology, p. 510, Pliilad., 1S54. Section of Intestinal Villus. a. Artery, b. Vein. c. Lymphatic. — Maguifiod aX) diameters. Intestinal Villus with the ccMnmenceuient of a Lacteal. CHYLIFEROUS APPARATUS. 211 the reservoir of Pecquet, receptaculura seu cisterna chyli (Figs. 55 and 60) —which is the commencemeut of the thoracic duct. This reservoir Fig. 58. , Fig. 59. Extremity of Intestinal Villus. A. During absorption, showing absorbent cells and lacteal trunks, distended with chyle. B. During interval of digestion, showing the supposed peripheral network of lacteals. is situate about the third lumbar vertebra; behind the right pillar of the diaphragm, and the right renal vessels. The chyliferous vessels generally follow the course of the arteries; but sometimes proceed in the spaces between them. They exist in the lower part of the duodenum, throughout the whole of the jeju- num, and in the upper part of the ileum. M. Yoisin^ affirms, that all, or at least the major part, of them pass through the substance of the liver, before they empty their contents into the thoracic duct. After proceeding a certain distance, they anastomose, he says, with each other, enlarge in size, and are collected to- gether so as to form a kind of plexus below the lobe of Spigelius, towards which they con- verge. From this point, they penetrate the substance of the liver, through which they ramify with great minuteness, and finally empty themselves into the receptaculum chyli. To prove, that the chyliferous vessels do pass through the liver, he put a ligature around the duct below the diaphragm, in a dog which had eaten largely, and when digestion was in full activity. The chyliferous vessels were observed to swell, and their whitish colour was distinctly perceived. They could be traced, without much difficulty, from the interior of the intestinal canal, through the mesenteric glands, as far as their entrance into the liver. The chyliferous vessels are composed of two coats; the outer of a fibrous and firm character, into whose composition muscular fibre-cells have been found, by Ktilliker, to enter largely; the inner very thin, epi- thelial, and generally considered to form, by its duplicatures, valves. These are of a semilunar form, arranged in pairs, and with the convex side towards the intestine. Their arrangement has appeared to be well adapted for permitting the chyle to flow from the intestine to the tho- Extremity of an Intestinal Vil- lus during absorption. a. Marginal layer of opithelinm- cells, b. Epitholium-colls turgid with oleaginous matter, c. Adher- ent oil-globules. ' Nouvel Apei\u sur la Physiologie du Foie, &c., Paris, 1833. 212 ABSOEPTION. racic duct, and for preventing its retrograde course; but M. Magendie* affirms, that their existence is by no means constant. These reputed valves are considered by M. Mojon^ to be true sphincters. By phicing the lymphatic vessels on a glass plate, and opening them through their entire length, he observed by the microscope, that they are formed of circular fibres, which, by diminishing the size of the vessel at different points, give rise to the nodosities observed externally. If the ends of a varicose lymphatic be drawn in a contrary direction, these nodosities disappear, as well as the supposititious valves. Mojon observed, more- over, that the fibrous membrane of the lymphatics has longitudinal, as well as oblique, filaments passing from one narrow portion to another. The longitudinal fibres have their two extremities attached to the trans- verse fibres, which, according to him, constitute the sphincters or con- tractors of the lymphatics. He explains the difficulty often experienced in attempting to inject the lymphatic vessels in a direction contrary to the course of the lymph, by the circumstance, that the little pouches formed by the sphincters, and the relaxation or distension of their pa- rietes on filling them with injected matter, diminish the calibre of the tube, and can even close it entirely. The smallest lacteals appear to be destitute of valves; but valves are perceptible in those of less than, one-third of a line in diameter, and they have the same structure as those of the veins. The minute lacteals in the villi are said to consist of a single membrane with elongated cell-nuclei, corresponding to the longitudinal fibrous membrane of the veins, but not lined by epithe- lium. Some anatomists describe an external coat, formed of condensed areolar tissue, which unites the chjdiferous vessels to the neighbouring parts. The mesenteric glands or ganglions are small, irregularly lenticular organs; varying in size from the sixth of an inch to an inch; nearly one hundred in number, and situate between the two laminae of the mesentery. Tn them, the lymphatic vessels of the abdomen terminate; and the chyliferous vessels traverse them in their course from the in- testine to the thoracic duct. Their substance is of a pale rosy colour ; and their consistence moderate. By pressure, a transparent and in- odorous fluid can be forced from them; which has never been examined chemically. Anatomists differ with regard to their structure. Accord- ing to some, they consist of a pellet of chyliferous vessels, folded a thousand times upon each other; subdividing and anastomosing almost ad infinitum; united by areolar tissue, and receiving a number of blood- vessels. In the opinion of others, again, cells exist in their interior, into which the afferent ch3diferous vessels open; and whence the efferent set out. These are filled with a milky fluid, carried thither by the lac- teals or exhaled by the bloodvessels. Notwithstanding the labours of Nuck,^ Hewson, Abernethy, Mascagni, Cruikshank, Haller,'* Beclard,* and other distinguished anatomists, the texture pf these, as well as of the lymphatic glands or ganglions in general, is not demonstrated. The ' Precis Eltmentaire, 2de edit., ii. 177, Paris, 1825. * Op. citat. and Amer. Journal, &c., for Aug. 1834, p. 465. * Adenologia, Lugd. Bat., llJt»ti. * Element. Physiol., lib. ii. §3, Lansan., 1757. * Addit. a Biciiat, p. 128, Paris, 1821. CHYLIFEROUS APPARATUS. 213 chvliferous and sanguiferous vessels become extremely minute in their substance; and the communication between the afferent and effe- rent vessels is very easy ; as mercurial injec- tions pass readily from the one to the other. According to Mr. Goodsir, the absorbent ves- sels within the chyliferous and lymphatic glands lay aside all but their internal coat; and the epithelium, instead of forming a thin lining of flat transparent scales, as in the ex- tra-glandular lymphatics, acquires an opaque granular aspect, and is converted into a thick irregular layer of spherical nucleated cor- puscles, measuring on an average 5 o'o o^-^ P^^^ of an inch in diameter, so as to suggest the idea of lymph or chyle corpuscles generated on the internal membrane after the ordinary manner of epithelium cells, and about to be thrown off into the vessel. This layer, accord- ing to Mr, Goodsir, is thickest in those lymph- atics that are situated towards the centre of Fig. 61. Diagram of a lymphatic gland, showing the intra-glandiilar net- Work, and the transition from the scale-like epithelia of the extra- glandular lymphatics, to the nucleated cells of the iutra-glandular. the gland, becomes gradually thinner towards the afferent and efferent vessels, and passes continually into the ordinary epithelium. Fig. 62. Portion of the intra-glandular lymphatic, showing along the lower edge the thickness of tlie germinal memhraue, and upon it the thick layer of glandular epithelial cells. More recently, the morphology of these glands has been investigated by Prof. Briicke and Prof. Kolliker,' who state that each gland Thoracic Duct. 1. Arch of aorta. 2. Thoracic aorta. 3. Abdominal aorta, show- ing its principal branches divided near their origin. 4. Arteria iuuo- minata, divided into right carotid and right subclavian arteries. 5. Left carotid. 6. Left subclavian. 7. Superior cava, formed by the union of 8, the two venjB innominat phosphate and carbonate of soda .... J 1-300^ Water ......... 93-987 Chyle and lymph strikingly, therefore, resemble each other ; and ac- cording to M. Millon,^ when taken from the same animal at one time, the analogy in composition is very great. AVithout impropriety they may, indeed, be termed rudimental blood.^ It is impossible to estimate the quantity of lymph contained in the body. It would seem, that notwithstanding the great capacity of the lymphatic vessels, there is, under ordinary circumstances, little fluid circulating in them. Frequently, when examined, thej have appeared ' Lond. Med. Gazette, Jan., 1841. " Proceedings of the Royal Society, Feb. 10, 1842. * Comptes Rendus des Seances et Memoires de la Societe de Biologie, Annee 1854, p. 50, Paris, 1855. * Archives Generales de Medecine, Fevr., 1850, p. 237. ^ See, on the whole subject of the lymph, Lehmann, Lehrbuch der Physiologischen Chemie, ii. 290, Leipz., 1S50, and Amer. edit, of Dr. Day's translation, by Dr. Robt. E. Rogers, ii. 31, Philad., 1855. 2-48 ABSORPTION. to be empty, or pervaded by a mere thread of Ij^mpli. M. Magendie^ endeavoured to obtain the whole of the lymph from a dog of large stature. He could collect but an ounce and a half; and it appeared to him that the quantity increased whenever the animal was kept fast- ing ; but on this point he does not seem to express himself positively. On the other hand, M. Collard de Martigny^ obtained nine grains of lymph, in ten minutes, from the thoracic duct of a rabbit which had taken no food for twenty-four hours ; and Geiger, from three to five pounds of Ijnuph daily, from the foot of a horse from which the same .quantity had been flowing several years, without injury to the health. The estimate made by Bidder has been referred to elsewhere. (Page 220). 3. PHYSIOLOGY OF LYMPHOSIS. The term lymphosis has been proposed by Chaussier for the action of elaboration by which lymph is formed, — as chylosis has been used for the formation of chyle, and hcematosis for that of the blood. In describing the organs concerned, the striking similarity — we might almost say — identity in structure and arrangement between them and the chyliferous organs will have been apparent. A part of the vascu- lar apparatus is common to both ; and they manifestly constitute one and the same system. This would be sufficient to induce us to assign them similar functions ; and it would require powerful and positive testimony to establish an opposite view. At one period, l3miph was considered to be simply the watery portion of the blood ; and the lymphatic vessels were regarded as the continuation of ultimate arte- rial ramifications. It was affirmed, that the blood, on reaching the terminal branches of the arteries, separated into two parts ; the red and thicker portion returning to the heart by the veins ; and the white, serous portion — liquor sanguinis — by the lymphatics.^ The reasons for this belief were, the great resemblance between lymph and the serum of the blood ; and the facility with which an injection passes, in the dead body, from the arterial into the lymphatic capillary vessels. M. Magendie has revived the ancient doctrine ; and, of consequence, no longer considers the lymphatics to form part of the absorbent sys- tem ; but to belong to the circulatory apparatus, and to serve the oflice of waste pipes, in case of emergency. Without canvassing this sub- ject now, we may assume it for granted, that the lymph which circulates in the lymphatic vessels is as identical in its nature, or as little subject to alteration, as the chyle ; and that, consequently, whatever may be the materials, besides the liquor sanguinis, that constitute it, an action of elaboration and selection must be exerted in its formation. It has been conceived, that many of the tissues of the body, the serous membranes, for example, do not receive red blood ; and must, consequently, be nourished by white blood. The 13'mphatics, in such cases, have been considered to be to the white arteries what the veins are to the red. Such has been presumed to be one of their offices, but it will be seen, hereafter, that all the tissues supplied with vessels receive red blood ; and hence it is unnecessary to suppose, that the lymphatics execute any venous function. ' Op. citat., ii. 192. ^ Journal de Physiologie, viii. 26G. 3 Kirkes and Paget, Manual of Physiology, 2d Amer. edit., p. 210, Philad., 1853. LYMPHOSIS. 249 Fig. 74. Assuming, for the present, that lymph is wholly obtained from materials already deposited in the body ; the next inquiry is, — the mode in which its formation and simultaneous absorption are effected. On this topic, we have no arguments to employ in addition to those adduced regarding the function of the chyliferous radicles. In every respect, they are situate identically, and to the history of the latter we must refer for an exposition of the little we know of this part of lym- phosis. The causes of the progression of the lymph in the vessels are the same as those that influence the chyle. In addition, however, to those mentioned under chyliferous ahorpiion, there is one that applies equall_f to the chyliferous and Ijmiphatic vessels: this is the mode in which the thoracic duct enters the subclavian vein. It has been already observed that it occurs at the point of junction^ be- tween the jugular and subclavian, as at D, Fig. 74, where J represents the jugu- lar, and y S the sub- clavian, in which the blood flows from V towards S, the car- diac extremity. Now, it is a phy- sical fact, that when a small tube is in- serted perpendicu- larly into the lower side of a horizontal conical pipe, in which water is flow- ing from the nar- rower to the wider portion ; and if the small vertical tube be made to dip into a vessel of water, not only will the water of the larger pipe not descend into the vessel ; but it will draw up the water through the small tube so as to empty the vessel.^ Instead of supposing the canals, in Fig. 74, to be veins and the thoracic duct; let us presume that they are rigid me- chanical tubes; and that the extremity of the tube D, which represents the thoracic duct, dips into the vessel 13. As the fluid, proceeding from J to S and V to S, is passing from the narrower portions of conical tubes to wider, it follows, that the fluid will be drawn out of the ves- sel B, simply by traction, or, by what Venturi^ terms the lateral com- munication of fluids. This would happen in whatever part of the ves- sel the tube B D terminated. But its insertion at D has another advan- tage. By the mode in which the current from J towards S unites with that from V towards S, a certain degree of diminished pressure must Termination of Thoracic Duct. ' Sir C. Bell, in Animal Mechanics, p. 41, Library of Useful Knowledge, Lond., 1829. ^ Sur la Communication Lat^rale du Mouvement dans les Fluides, Paris, 1798. 250 ABSORPTION. exist at D ; so tliat tlie atmosplieric pressure, on the surface of the water in the vessel B, will be exerted in propelling it forwards. In the progress, then, of the chyle and lymph along the thoracic duct, not only may the traction of the more forcible stream along the veins draw the fluid in the thoracic duct along with it, but, owing to the dimin- ished pressure at the mouth of the duct, atmospheric pressure may have some — although probably but little — influence, in forcing the chyle and lymph from the chyliferous and lymphatic radicles onwards. The lymphatic glands have been looked upon as small hearts for the pro- pulsion of lymph ; and Malpighi accounts for the greater number in the groin in this way ; — the lymph having to ascend to the thoracic duct against gravity : and this appears to have been somewhat the opinion of Bichat. There seems, however, to be nothing in their structure that ought to lead to this belief; and, if it be not muscular or contractile, it is manifest, that their number must have the effect of retarding rather than accelerating the flow. The most prevalent sentiment is, that they are somehow concerned in the elaboration of the lymph ; but their exact functions we know nothing definite. What has been already said of the mesenteric ganglions, and of their probable agency in the forma- tion of chyle corpuscles is equally applicable to them and their agency in the formation of lymph corpuscles. On the subject of the moving powers of the lymph, M. Adelon' has remarked, that if we admit it to be the serous portion of the blood ; and that the lymphatics are vessels of return, as the veins are, the heart might be considered to have the same influence over lymphatic, that it has been presumed to have over venous, circulation ; and whether we admit this or not, as the thoracic duct opens into the subclavian vein, the influence of the suction power of the organ on the venous blood may affect the progression of the chyle also. It cannot, how- ever, as Miiller^ remarks, be the primary cause of the motion of the chyle, for Autenrieth, Tiedemann, and Carus observed, when a ligature was applied to the thoracic duct, that the part of the duct below the ligature became distended even to bursting. We shall see hereafter, that during inspiration, absorption, it is imagined, may be facilitated by the dilatation of the chest, and the necessary diminution of pi'essure on the heart and great vessels. Professor M tiller^ discovered, that the frog, and several other am- phibious animals, are provided with large receptacles for lymph, situate immediately under the skin, and, like the heart, exhibiting distinct and regular pulsations. The use of these lymph hearts appears to be to pro- pel the lymph along the lymphatics. In the frog, four of them have been found; two posterior, behind the joint of the hip; and two anterior, on each side of the transverse process of the third vertebra, and under the posterior extremity of the scapula. The pulsations of these lymphatic hearts do not correspond with those of the sanguifer- ous heart; nor do those of the right and left sides occur synchronously. * Art. Absorption, in Diet, de Medecine, 2de edit., i. 239, Paris, 1832 ; and Plijsio- logie de rHomme, edit. cit. iii. 92. 2 Handbuch, u. s. w. ; and Baly's translation, p. 284, Lond., 1838. 3 Philos. Transact, for 1833 ; and op. cit. See, also, bis Observations on tbe Lym- phatic Hearts of Tortoises, in Miiller's Arcbiv., Heft 1, 1840. LYMPHOSIS. 251 Fig. 75. Lymph Heart of Pj-thon Bivit- tatus, Heart 9 lines long ; 4 broad. 4. External areolar coat. 5. Thick muscular coat ; four mus- cular eolumns cross the cavity, which communicates with three lymphatics — only one, 1, seen here, and two veins, 2, 2. 6. Smooth lining membrane of the cavity. 7. An appendix or auri- cle, tlie cavity of which commu- nicates with, the other. Tliej often alternate irregularly. Prof. E. H. Weber has described tliem in a larger species of serpent — pytlion hivittatus ;' and Dr. Joseph J. Allison, of Philadelphia,^ a young and zeal- ous observer, who was cut oiF early in his ca- reer, saw them in the tadpole, the frog, the sauria, ophidia, and chelonia. His researches led him to conclude : — First. That the pulsa- tions of the lymphatic organs vary in difierent specimens (frogs and tadpoles) from 60 or less to 200 per minute. Secondly. That they vary in the same individual so as sometimes to be- come double in frequency. Thirdly. That the lymphatic pulsations bear no fixed relation to those of the pulmonary heart or to respiration, the lymphatic hearts beating —on an average — with greater frequency. Professor Stannius^ has discovered lymph- atic hearts in various birds. Unlike that of the heart, the action of these lymph hearts appears to be dependent upon a certain limited portion of the spinal cord ; for Volkmann'' found, that by dividing the anterior or motor roots of the spinal nerves connected with them, the pulsations immediately ceased. The course of the lymph is by no means rapid. If a lymphatic be divided on a living individual, the lymph oozes slowly, and never with a jet. Mr. Cruikshank estimated its velocity along the vessels to be four inches per second or twenty feet per minute; but it is probably much less. M. CoUard de Martigny' obtained nine grains of lymph in ten minutes from the thoracic duct' of a rabbit, which had taken no food for twenty -four hours. Having pressed out the lymph from the prin- cipal lymphatic trunk of the neck, in a dog, the vessel filled again in seven minutes : in a second experiment it filled in eight minutes. The data for any correct evaluation of this matter are altogether inadequate, the deranging influence of all such experiments being considerable. In man and living animals, the lymphatics of the limbs, head, and neck rarely contain lymph ; their inner surface appearing to be merely lubricated by a very thin fluid. Occasionally, however, the lymph stops in different parts of the vessels; distends them; and gives them an ap- pearance very like that of varicose veins, except as to colour. Sciin- mering states, that he saw several in this condition on the top of the foot of a female; and M. Magendie one around the corona glandis of a male. In dogs, cats, and other living animals, lymphatics, filled with lymph, are frequently seen at the surface of the liver, gall-bladder, vena cava, vena porta, and at the sides of the spine. Magendie remarks, ' Muller, op. citat., p. 275. ^ American Journal of the Medical Sciences, for August, 1838. * Miiller's Archiv., 1843, Heft 5. "• Ibid., 419, Berlin, 1844; and Valentin, Lehrbucli der Physiologie des Mensclien, ii. 7G9, Braunschweig, 1844. * Journal de Physiologie, torn. viii. 252 ABSORPTION. that he lias never met with the thoracic duct empty, even when the lymphatics of the rest of the body were entirely so.' It must be recol- lected, however, that the thoracic duct must always contain the product of the digestion either of food or of secretions from the alimentary tube. The stagnation of lymph in particular vessels has given occasion to the belief, that it flows with different degrees of velocity in different parts of the system; and this notion has entered into the pathological views of writers, who have presumed, that something like determina- tions of lymph may occur, and produce lymphatic swellings. M. Bor- den,^ indeed, speaks of currents of lymph. All the phenomena of the course of the lymph negative, however, this presumption; and induce us to believe, that its progress is pretty uniform, and always slow ; and when an accumulation, or engorgement, or stagnation occurs in any vessel, it is more probably owing to increased formation by the lymph- atic radicles that communicate with the vessel in question, or to loss of tone in the parietes of the engorged lymphatics. The lymph, which proceeds by the thoracic duct, is emptied, along with the chyle, into the subclavian vein. At the confluence, a valve is placed, which does not, however, appear to be essential, as the duct opens so favourably between the two currents from the jugular and subclavian, that there is little or no tendency in the blood to reflow into it. It has been suggested, that its use may be, to moderate the instillation of the fluid from the thoracic duct into the venous blood. With regard to the question, whether the lymph is the same at the radicles of the lymphatics as in the thoracic duct, or whether it does not gradually become more and more animalized in its course towards the venous system, and especially in its progress through the lymph- atic glands, the remarks made upon this subject, as respects the chyle, apply with equal force to the lymph. , The glands of the mesentery, and lymphatics in general, seem to be concerned in some of the most serious diseases. Swelling of the lymph- atic glands of the groin may indicate the existence of a venereal sore on the penis. A wound on the foot produces tumefaction of the ingui- nal glands; one on the-hand inflames those of the axilla. Whenever, indeed, a lymphatic gland is symptomatically enlarged, the source of irritation will be found at a greater distance from the vein into which the great lymphatic trunks pour their fluid than the gland is. In plague, one of the essential phenomena is swelling of the lymphatic glands of the groin and axilla ; hence, it has been termed adeno-adynarnic fever (from ahriv^ a gland). In scrofula, the lymphatic system is generally deranged; and, in the doctrine of Broussais, a very active sympathy is affirmed to exist between the glands of the mesentery, and the mucous surface of the stomach and intestines. This discovery, we are told, belongs to the '■'■ x^husiological dodrine,^^ which has shown, that all gastro- enterites are accompanied by tumefaction of the mesenteric glands : although chyle may be loaded with acrid, irritating, or even poisonous matters, it traverses the glands with impunity, provided it does not inflame the gastro-enteric mucous surface. "Our attention," Broussais' ' Precii?, &c., ii. 224. 2 CEavros Completes, par Richerand, Paris, 1818. 3 Traite do Plivsiolotjie, &c., and Bell and La Roche's translation, 3d Amer. edit., p. 362, PMladelpliia, 1832. VENOUS. 253 adds, "has been for a long time directed to this question, and we have not observed any instance of mesenteric ganglionitis, which had not been preceded by well-evidenced gastro-enteritis." The discovery will not immortalize the "doctrine." We should as naturally look for tume- faction of the mesenteric glands or ganglia, in cases of irritation of the intestine, as for enlargement of the glands of the groin in irritation of the foot. Lastly; the lymph, from whatever source obtained — united with the chyle — is discharged into the venous system. Both, therefore, go to the composition of the body. They are entirely analogous in pro- perties ; but differ materially in quantity ; — the nutritious fluid, formed from materials obtained from without, being far more copious. A due supply of it is required for continued existence ; yet the body can live for a time, when the supply of nutriment is entirely cut otY. Under such circumstances, the necessary proportion of nutritive fluid must be obtained from the decomposition of the tissues ; but, from the per- petual drain, that takes place through the various excretions, this soon becomes insufficient, and death is the result. In a note to a recent edition of his " Principles of Human Physiology,"^ Dr. Carpenter re- marks, that at the time of the publication of the first edition of his work (1842) he was under the impression, that the view maintained by him, " that the special function of the lymphatics like that of the lacteals is nutritive absorption," was altogether novel. The author attaches little value to originality in such matters; but he thinks it well to state, that the doctrine in the text is that adopted by him in the first edition of this work (1832), and taught by him ever since he has been a teacher ; yet he is far from regarding it as original with him. We have seen, then, that both chyle and lymph are poured into the venous blood ; — itself a compound of the residue of arterial blood, and various heterogeneous absorptions. As an additional preliminary to the investigation of the agents of internal absorption, let us inquire into the nature and course of the fluid contained in the veins ; but so far only as to enable us to understand the function of absorption; the other considerations relating to the blood appertain to the function of circulation. III. VENOUS AB30KPTI0N. The apparatus of venous absorption consists of myriads of vessels called veins^ which commence in the very tissues, by what are called capillary vessels^ and thence pass to the great central organ of the cir- culation — the heart; receiving, in their course, the products of the various absorptions effected not only by themselves, but by the chy- liferous and lymphatic vessels. The anatomy of the venous system will be given under Circulation. ' Fourth American edition, p. 506, Philad., 1850. See on this suhject, Adelon, Art. Absorjition, in Diet, de Medecine, i. 117, Paris, 1821 ; and Moultrie, American Journal of the Medical Sciences for 1827, and On the Organic Functions of Animals, Charleston, 1844. 254 ABSOEPTION. 1. PHYSIOLOGY OF TEXOCS ABSORPTIOX. Whilst tlie opinion prevailed universally, that the lymphatics are the sole agents of absorption, the fluid, circulating in the veins, was considered to consist entirely of the residue of arterial blood, after it had passed through the capillary system, and been subjected to the different nutritive processes. AVe have seen, however, that drinks are absorbed by the mesenteric veins ; and we shall hereafter find, that various other substances enter the venous system. It is obvious, therefore, that venous blood cannot be simply the residue of arterial blood ; and we can thus account for the greater capacity of the venous than of the arterial system. The facts, which were referred to, when considering the absorption of fluids from the intestinal canal, may have been sufiicient to show, that veins are capable of absorbing ; as odorous and colouring properties of substances were distinctly found in the mesenteric veins. A question arises, whether any selection or elaboration is exerted, as in the case of the chyle, or whether the fluid, when it attains the interior of the vessel, is the same as without? M. Adelon,^ — who, with many of the German physiologists, believes in both venous and lymphatic absorption, and venous and chyliferous absorption, — conceives, tliat a vital action takes place at the very ex- tremities of the venous radicles, precisely similar to that which is pre- sumed to be exerted at the extremities of the lymphatic and chyliferous radicles. In his view, consequently, an action of elaboration is exerted upon the fluid, which becomes, in all cases, converted into venous blood at the very moment of absorption. On the other hand, MM. !Magendie,^ Fodera,^ and others maintain, that the substance when possessed of the necessary tenuity soaks through the vessel ; and that this act of imbibition is purely plwsical. In their view, consequently, the fluid within the vessel must be the same as without. In favour of the vital action of the veins we have none of that evi- dence, which strikes us in the case of the chyliferous and lymphatic vessels. In the last we invariably find fluids, identical — in all essen- tial respects — in physical characters ; and never containing extraneous matter, — if we make abstraction of certain salts, that have been occa- sionally met with in the thoracic duct. In the veins, on the other hand, the sensible properties of odorous and colouring substances have been frequently apparent. It may be argued, however, that the fluid, flowing in the veins, is as identical in composition as the chyle or the lymph. This is true; but it must be recollected, that the greater part of it is the residue of arterial blood; and that its hue and other sensible properties are such as to disguise any absorbed fluid, not itself possessing strong characteristics. The fact, — now indis- putable, — that various substances, placed outside the veins, have been detected in the blood Avithin, is not only a proof that the veins absorb; but that no action of elaboration is exerted on the absorbed fluid. Of this we have the most convincing proof in certain experiments by ' Art. Absorption, in Diet, cle Medecine, 2de edit., i. 239, Paris, 1832 ; and Physio- loijie de I'Homme, 2de edit., iii. 113, Paris, 1829. ^^ Precis, &c., 2de edit., ii. 271. ^ Ileclierches Experimentales sur I'Exhalation et I'Absorption, Paris, 1823. VENOUS. 255 M. Magendie.^ In exhibiting to his class the mode in which medi- cines act upon the system, he showed, on a living animal, the eflfects of introducing a quantity of water, of the temperature of 104" Fah., into the veins. In performing this experiment, it occurred to him to notice what would be the effect produced by artificial plethora on the phenomena of absorption. Having injected nearly a quart of water into the veins of a dog of middle size, he placed in the cavity of the pleura a small dose of a substance with the eflfects of which he was familiar, and was struck with the fact, that they did not exhibit them- selves for several minutes after the ordinary period. He immediately repeated the experiment, and with a like result. In several other ex- periments, the eflfects appeared at the ordinary time, but were mani- festly feebler than they ought to have been from the dose of the substance employed ; and were kept up much longer than usual. In another experiment, having introduced as much water as the ani- mal could bear without perishing, — which was about two quarts, — the effects did not occur at all. After having waited nearly half an hour for their developement, which generally required only about two min- utes, he inferred, that if the distension of the bloodvessels was the cause of the defect of absorption, if the distension were removed, absorption ought to take place. He immediately bled the animal largely in the jugular; and, to his great satisfaction, found the effects manifesting themselves as the blood flowed. He next tried whether, if the quantity of blood were diminished at the commencement of the experiment, absorption would be more rapid; and the result was as he anticipated. An animal was bled to the extent of about half a pound; and the effects, which did not ordinarily occur until after the second minute, appeared before the thirtieth second. As the results of these experi- ments seemed to show, that absorption is in an inverse ratio to the degree of vascular distension, he inferred, that it is effected physically; is dependent upon capillary attraction ; and ought to take place as well after death as during life. To prove this, he instituted the following experiments. — He took a portion of the external jugular of a dog, about an inch long and devoid of branches. Eemoving carefully the surrounding areolar tissue, he attached to each extremity a glass tube, by means of which he kept up a current of warm water within it. He then placed the vein in a slightly acid liquor, and carefully collected the fluid of the current. During the first few minutes, it exhibited no change; but, in five or six minutes, became sensibly acid. This experi- ment was repeated on veins taken from the human subject with like results; and not only on veins but on arteries. Similar experiments were next made on living animals. He took a young dog, about six weeks old, whose vessels were thin, and, conse- quently, better adapted for the success of the experiment, and exposed one of its jugular veins. From this he dissected entirely the surround- ing matter, and especially the areolar tissue, with the minute vessels that ramified upon it, and placed it upon a card, in order that there might be no point of contact between it and the surroimding parts. He then let fall upon its surface, and opposite the middle of the card, a thick ' Op. citat., ii. 273. 256 ABsoRPTioisr. watery solution of iiux vomica, — a substance, that exerts a powerful action on dogs. He took care, that no particle of the poison touched any thing but the vein and card; and that the course of the blood, within the vessel, was free. Before the expiration of three minutes, the effects he expected appeared, — at first feebly, but afterwards with so much activity, that to prevent fatal results he had to inflate the lungs. The experiment was repeated on an older animal with the same results; except that, as might have been expected, they were longer in exhibit- ing themselves, owing to the greater thickness of the parietes of the veins. Satisfied, as regarded the veins, he now directed his attention to the arteries : — the results were the same. They were, however, slower in appearing than in the case of the veins, owing to the tissue of the arte- ries being less spongy. It required upwards of a quarter of an hour for imbibition to be accomplished. In one of the rabbits, which died under the experiment, they had an opportunity of discovering, that absorption could not have been effected by any small veins, that had escaped dissection. One of the carotids, — the subject- vessel of the experiment, — was taken from the body ; and the small quantity of blood, adherent to its inner surface, was found by M. Magendie, and his friends who assisted at the experiment, to possess the extreme bit- terness that characterizes nux vomica. These experiments were suffi- cient to prove the fact of imbibition by the large vessels, both in the dead and in the living state. His attention was now directed to the smaller; which seemed, a priori^ favourable to the action, from their delicacy of organization. He took the heart of a dog, that had died the day before, and injected water, of the temperature of 86° of Fah,, into one of the coronary arteries, which readily returned by the coro- nary vein into the right auricle, whence it was allowed to flow into a vessel. Half an ounce of water, slightly acidulated, was now placed in the pericardium. At first, the injected fluid did not exhibit any signs of acidity ; but, in five or six minutes, the evidences were un- equivocal. From these facts, M. Magendie^ draws the too broad deduction, that "all bloodvessels, arterial and venous, dead or living, large or small, possess a ph3'sical property capable of accounting for the prin- cipal phenomena of absorption," AVe shall endeavour to show, that it explains only certain varieties of absorption, — those in which the vessel receives the fluid unmodified, — but that it is unable to account for other absorptions in which an action of selection and elaboration is necessary. After these experiments were performed, others were instituted by MM. Segalas^ and Fodera,-' from which the latter physiologist attempts to show, that exhalation is simply a transudation of substances from the interior of vessels to the exterior ; and absorption an imlilition or pas- sage of fluids from the exterior to the interior. The facts adduced by !M. Fodcra in support of his views will be considered under the head of Secretion. They go chiefly to show the facility Avith which sub- ' Precis, &c., ii. 283. * Magendle's Journal de Physiol., ii. 217. 3 Recherclies ExiJeriment. sur I'Absorption, &c., Paris, 1&24, and Magendie's Journal, &c., iii. 35. VENOUS. 257 stances penetrate the parietes of vessels and other tissues of the body; an action which he found to be singularly accelerated by the galvanic influence. Prussiate of potassa was injected into the cavity of the pleura; and sulphate of iron introduced into that of the peritoneum in a living animal. Under ordinary circumstances, it requires five or six minutes before the two substances meet by imbibition through the dia- phragm; but the admixture is instantaneous if the diaphragm be sub- jected to a slight galvanic current. The same fact is observed, if one of the liquids be placed in the urinary bladder, and the other in the abdomen ; or the one in the lung, and the other in the cavity of the pleura. It was further found, that, according to the direction of the current, the union took place in the one or the other cavity. Dr. Bos- tock,' in commenting on these cases, thinks it must be admitted, that they "go very far to prove that membranes, perhaps even during life, and certainly after death, before their texture is visibly altered, have the power of permitting the transudation of certain fluids." That such imbibition occurs during life is indisputably proved. If the clear and decisive experiments of Magendie and Fodera Iiad been insufficient to establish it, the additional testimony, — aflbrded hy Lawrence, Coates, and Harlan ; by Dutrochet, Faust, Mitchell, Rogers, Draper, and others, — would be ample. By the difterent rates of penetrativeness of different fluids, and of permeability of different tissues, we can explain why imbibition may occur in one set of vessels and not in another ; and the constant cur- rent, established in the interior of the vessel is a sufficient reply to the suggestion, that there may not be the same tendency to transude after the fluid has entered it. M. Adelon^ is of opinion, that under the view of imbibition we ought to find substances in the arteries and lymphatics also; but a sufficient objection to this would be, — the comparative tardi- ness, with which the former admit the action ; and the selection, and, consequently, refusal, exerted by the latter; but even here evidences of adventitious imbibition are occasionally met with ; as in the case of salts, which — we have seen — have been detected in the thoracic duct, after having been introduced into the cavity of the abdomen. The two following experiments by Prof. J. K. Mitchell,^ which are analogous to numerous others, performed in the investigation of this subject, well exhibit endosmose in living tissues. A quantity of a solution of acetate of lead was thrown into the peritoneal cavity of a young cat; sulphuretted hydrogen being passed, at the same time, into the rectum. In four minutes, the poisonous gas killed the animal. Instantly on its death, the peritoneal coat of the intestines, and the parietes of the cavity in contact with them, were found lined with a metallic precipi- tate, which adhered to the surface, and was removable by nitric acid moderately diluted. It was the characteristic precipitate of sulphuretted hydrogen, when acting on lead. In another experiment on a cat, a solution of acetate of lead was placed in the thorax, and sulphuretted hydrogen in the abdomen. Almost immediately after the entrance of the sulphuretted hydrogen into the abdominal cavity, death ensued. ' rhysiology, edit, cit., p. 629. ^ Op. cit. ^ American Journal of the Medical Sciences, vii. 44, Pliilada., 1830. VOL. I. — 17 258 ABSORPTION. On inspecting- tlie thoracic side of the diaphragm, which was done as quickly as possible, the tendinous part of it exhibited the leaden appear- ance of the precipitate thrown down by sulphuretted hydrogen. The experiment of J. Miiller, referred to in a preceding page, establishes the same fact. It may be concluded, then, that all living tissues imbibe liquid mat- ters which come in contact with them ; and that the same occurs to solids, provided they are soluble in the humours, and especially in the serum of the blood. But although imbibition is doubtless effected by living tissues, too great a disposition has been manifested to refer all the vital phenomena of absorption and exhalation to it. Even dead animal membrane exerts a positive agency in respect to bodies placed on either side of it. In the early part of this work' the phenomena of imbibition were investigated, and it was there explained how endos- mose and exosmose are affected through organic membranes. A care- ful examination of those phenomena would lead to the belief, that in many cases the membrane exerts no agency except in the manner last suggested by M. Dutrochet. This is signally manifested in experi- ments with porous, inorganic substances ; and it has been ingeniously and ably confirmed by Dr, Draper,^ of New York, who found, that the phenomena were elicited, when, instead of an organic tissue, fissured glass was employed. Still, as has been demonstrated, the nature of the septum or membrane has in other cases a marked effect on endosmose. Sir David Barry,^ — in different memoirs laid before the Academie Royale de Medecine, the 'Academie Hoyale des Sciences of Paris, and the Medico- Ghirurgical Society of London, — maintained, that the whole function of external absorption is a physical result of atmospheric pres- sure ; and " that the circulation in the absorbing vessels and in the great veins depends upon this same cause in all animals possessing the power of contracting and dilating a cavity around that point to which the centripetal current of their circulation is directed," In other words, it is his opinion, that, at the time of inspiration, a tendency to a vacuum is produced in the chest by its expansion ; and as the atmospheric pressure externally thus ceases to be counterbalanced, the pressure without occasions the flow of blood towards the heart along the veins. The consideration of the forces that propel the blood will atTord us an opportunity of saying a few words on this view; at present, we may only observe, that Sir David ascribes absorption, — which he explicitly states to be, in his opinion, extra vital, — to the same cause. In proof of this, he instituted numerous experiments, in which the absorption of poisons from wounds appeared to take place, or to be suspended, according as the wounds were, as he conceived, exposed to atmospheric pressure, or freed from its influence by the application of a cupping-glass. The same quantity of poison, which, under ordinary circumstances, destroyed an animal in a few seconds, was rendered com- pletely innocuous by the exhausted glass ; and what is singular, even when the symptoms had commenced, the application of the cupping-glass ' See p. 66. 2 Amer. Journ. of the Mod. Soiences, for Aug. 1836, p. 276 ; Nov., 1837, p. 122 ; May, 1838, p. 23, and August, 1838 — more especiallj the last two. * Experimental Researches on the Influence of Atmospheric Pressure upon the Circu- lation, &c., Lond. 1826. VENOUS. - 259 had the effect of speedily and completely removing them; a fact of es- sential importance in its therapeutical relations. In commenting on the conclusions of Sir 1). Barry, Messrs. Addison and Morgan,' — who main- tain the doctrine, that all poisonous agents produce their specific eftects upon the brain, and general system, through the sentient extremities of nerves, and through the sentient extremities of nerves only ; and that, when such agents are introduced into the current of the circulation in any way, their effects result from the impression made upon the sensible structure of the bloodvessels, and not from their direct application to the brain itself, — contend, that the soft parts of the body, when covered by an exhausted cupping-glass, must necessarily, from the pressure o^ the edges of the glass, be deprived for a* time of all connexion, both nervous and vascular, with the surrounding parts; — that the nervts must be partially or altogether paralysed by compression of their trunks ; and that, from the same cause, all circulation through the veins and arteries within the area of the glass must cease ; that the rarefaction of the air within the glass being still farther increased by means of the small pump attached to it, the fluids, in the divided extremities of the vessels, are forced into the vacuum, and,' with these fluids, either, a part or the whole of the poison, which had been introduced ; and that, in such a condition of parts, tlie compression, on the one hand, and the removal of the poison from the wound on the other, will sufficientlv explain the result of the experiment, either according to the views of those who conceive the impression to be made on the nerves of the bloodvessels, or of those who think, that the agent must be carried along with the fluid of the circulation to the pail to be impressed. Thus far allusion has been made only to the passage of tenuous fluids into the veins. It has been already seen, that many albuminous and saccharine solutions after having been exposed to the gastric and in- testinal juices pass into the radicles of the portal veins to be con- veyed to the liver to undergo assimilation. Insoluble substances, too, have been detected by Professor Oesterlen^ in the mesenteric veins. On administering levigated charcoal to ani- mals for five or six days in succession, the blood of these veins exhi- bited distinctly particles of charcoal of different sizes, some of them so large, that it was a matter of surprise how they could have made their way into the blood through the mucous membrane and the walls of the bloodvessels. We have no difficulty, consequently, in compre- hending how the mild chloride and other insoluble preparations of mercury might be able to enter the bloodvessels in this manner. The observations of Oesterlen have been confirmed by Mensonides and Donders'' not only with charcoal, but with sulphur, and with starch, which is readily detected in the blood by the iodine test. The latter is inclined to think that they enter the lacteals rather than the veins, as he finds them deposited in the lungs more than the liver. It is difficult to conceive how they effect their passage. The extreme velo- city of the blood in the vessels may exert a degree of traction on them ' An Essay on the Operation of Poisonous Agents upon tlie Living Body, Lond., 1S29. * Heller's Archiv., Bd. iv. Heft 1, cited in Lond. Med. Gazette for July, 1^47. ^ Canstatt's Jahreshericht, 1851, p. 122, Wiirzburg, 1S52 ; and Ilenle uud Pfeufer's Zeitschrift, 1851, Bd. i. s. 415-27. 260 ABSORPTION. wliicli may account for tlieir entrance, when it could not be effected through dead membrane. Such would seem to be the main facts regarding the absorbent action of the veins, which rests on as strong evidence as we possess regarding any of the functions of the body ; yet, in the treatise on Animal and Vegetable Physiology by Dr. Eoget,^ we find it passed by without a comment ! We have still to inquire into the agents of internal and adventitious absorption. IV. IXTERXAL ABSOEPTIOX. On this point but few remarks will be necessary, after the exposition of the different vascular actions concerned in absorption. The term comprehends intersiitial absorjJtion, and the absorption of recrementitial fluids. l^hQ first comprises the agency by which the different textures of the body are decomposed and conveyed into the mass of blood. It will be considered more at length under the head of Nutpjtion ; the second^ that of the various fluids effused into cavities; and the thirds that which is effected on the excretions in their reservoirs or excretory ducts. All these must be accomplished by one of the two sets of vessels previously described; lymphatics, or veins, or both. Now, we have attempted to show, that an action of selection and elaboration is exerted by lymphatics; whilst we have no evidence of such action in the case of the veins. It would follow, then, that all the varieties of internal absorption, in which the substance, when received into the vessel, pos- sesses different characters from those it had when without, must be executed by lymphatics ; whilst those, in which no conversion occurs, take place by the veins. In the constant absorption, and corresponding deposition, incessantly going on in the body, the solid parts must be reduced to their elements, and a new compound be formed; inasmuch as we never find bone, muscle, cartilage, membrane, &c., existing in these states in any of the absorbed fluids ; and it is probable, therefore, that, at the radicles of the Ij^mphatic vessels, they are converted into the same fluid — the lymph — in like manner as the heterogeneous sub- stances in the intestinal canal afford to the lacteals the elements of a fluid the character of which is always identical. On the other hand, when the recrementitial fluid consists simply of the serum of the blood, more or less diluted, there can be no obstacle to the passage of its aqueous portion immediately through the coats of the veins by imbi- bition, whilst the more solid part is taken up by the lymphatic vessels. In the case of excrementitious fluids, there is reason to believe, that absorption simply removes some of their aqueous portions; and this, it is obvious, can be effected directly by the veins, through imbibition. The facts, connected with the absorption of substances from the interior of the intestine, have clearly shown, that the chjdiferous vessels alone absorb chyle, and that the drinks and adventitious substances pass into the mesenteric veins. These apply, however, to external absorption only; but similar experiments and arguments have been brought for- ward by the supporters of the two opinions, in regard to substances ' Bridgewater Treatise, Lond., 1834; Amer. edit., Pliilad., 1836. INTEKNAL. 261 placed on the peritoneal surltice of the intestine, and other parts of the . body. Whilst some aflfinn, that they have entered the lymphatics ; others have only been able to discover them in the veins. Mr. Hunter, having injected water coloured with indigo into the peritoneal cavity of animals, saw the lymphatics, a short time afterwards, filled with a liquid of a blue colour. In animals, that had died of pulmonary or abdominal hemorrhage, Mascagni found the lymphatics of the lungs and peritoneum filled with blood; and he asserts, that, having kept his feet for some hours in water, swelling of the inguinal glands supervened, with transudation of a fluid through the gland ; coryza, &c. M. Des- genettes observed the lymphatics of the liver containing a bitter, and those of the kidneys a urinous, lymph. Scimmering detected bile in the lymphatics of the liver; and milk in those of the axilla. M. Diipuy- treu relates a case, which M. Magendie conceives to be much more favourable to the doctrine of absorption by the lymphatic vessels than any of the others. A female, who had an enormous fluctuating tumour at the upper and inner part of the thigh, died at the IlOtel Dieu, of Paris, in 1810. A few days before her death, inflammation occurred in the subcutaneous areolar tissue at the inner part of the tumour. The day after dissolution, M. Dupuytren opened the body. On divid- ing the integuments, he noticed white points on the lips of the incision. Surprised at the appearance, he carefully dissected away some of the skin, and observed the subcutaneous areolar tissue overrun by whitish lines, some of which were as large as a crow's quill. These were evi- dently lymphatics filled with puriform matter. *The glands of the groin, with which these lymphatics communicated, were injected with the same matter. The lymphatics were full of the fluid, as far as the lumbar glands ; but neither the glands nor the thoracic duct presented any trace of it.' On the other hand, multiplied experiments have been instituted, by throwing coloured and odorous substances into the great cavities of the body; and these have been found always in the veins, and never in the lymphatics. To the experiments of Mr. Hunter, objections have been urged, similar to those brought against his experiments to prove the absorp- tion of milk by the lacteals; and sources of fallacy have been pointed out. The blue colour, which the lymphatics seemed to him to possess, and which was ascribed to the absorption of indigo, was noticed in the experiments of Messrs, Harlan, Lawrence, and Coates;^ but they discovered that this was an optical illusion. What they saw was the faint blue, which transparent substances assume, when placed over dark cavities. Mr. Mayo^ has also affirmed that the chyliferous lymphatics always assume a bluish tint a short time after death, even when the animal has not taken indigo. The cases of purulent matter, &c., found in the lymphatics, may be accounted for by the morbid action having produced disorganization of the vessel, so that the fluid could enter the lymphatics directly ; and, if once within, its progres- sion could be readily understood. M. Magendie" asserts, that M. Dupuytren and he performed more ' Magendie, Pi-rcis, &c., 2de edit., ii. 195, et seq. ; and Adelon, art. Absorption, Diet, de Med^, 2de edit., i, 239, and Physioloijie de rHomme, 2de edit., iii. 65, Paris, 1829. " Harlan's Physical Researches, p. 459, Pliilad., 1835. * Outlines of Human Physiology, 3d edit., Lond., 1833. * Op. cit., ii. 211. 262 ABSORPTION. .than one liundred and fifty experiments, in wliich they submitted to the absorbent action of serous membranes different fluids, and never found any of them within the lymphatic vessels. These fluids pro- duced their effects more promptly, in proportion to the rapidity with which they were capable of being absorbed. Opium exerted its nar- cotic influence; wine produced intoxication, &c., and ]\[. Magendie found, from numerous experiments, that the ligature of the thoracic duct in no respect diminished the promptitude with which these effects supervened. The partisans of lymphatic absorption, however, affirm that even if these substances are met with in the veins, it by no means follows, that absorption has been effected by them; for the lymphatics, they assert, have frequent communications with the veins; and, con- sequently, they may still absorb and convey their products into the venous system. In reply to this, it may be urged, that all the vessels — arterial, venous, and hnnphatic — appear to have intercommunica- tion ; but there is no reason to believe, that the distinct offices, per- formed by them, are, under ordinary circumstances, interfered with; and, again, where would be the necessity for these intermediate lymph- atic vessels, seeing that imbibition is so readily effected by the veins ? The axiom — quod fieri potest per pa^ca., non debet fieri i^er rnidta — is here strikingly appropriate. The lymphatics, too, as we have endeavoured to show, exert an action of selection and elaboration on substances exposed to them; but, in the case of venous absorption, there is not the slightest evidence, that any such selection exists, — odorous and coloured substances retaining, within the vessel, the properties they had without. Lastly. Where would be the use of organs of a distinct lymiphatic circulation opening into the thoracic duct, seeing that the absorbed matters might enter the various venous trunks directly through these supposititious communicating lymphatics; and ought we not occasionally to be able to detect in the lymphatic trunks some evidence of those substances, which their fellows are supposed to take up and convey into the veins? These carrier lymphatics have ob- viously been devised to support the tottering fabric of exclusive lymph- atic absorption, — undermined, as it has been, by the powerful facts and reasonings that have been adduced in favour of absorption by veins. From the whole of the preceding history of absorption, we are of opinion, that the chyliferous and lymphatic vessels form only chyle and lymph, refusing all other substances, with the exception of saline and other matters, that enter probablj^ by imbibition, — that the veins admit every liquid, which possesses the necessary tenuity ; and that whilst all the absorptions, which require the substances acted upon to be decomposed and transformed, are effected by chyliferous and lymph- atic vessels ; they that are sufficiently thin, and demand no alteration, are accomplished directly through the coats of the veins by imbibi- tion; and we shall see that such is the case with several of the transu- dations or exhalations. V. ACCIDENTAL ABSORPTION. The experiments, to which reference has been made, have shown, that many substances, adventitiously introduced into various cavities, CUTANEOUS. 263 or placed iu contact with different tissues, have been rapidly absorljed into the blood, without experiencing any transformation. Within certain limits, the external envelope of the body admits of this func- tion ; but by no means to the same extent as its prolongation, which lines the different excretory ducts. The absorption of drinks is suffi- cient evidence of the activity of the function as regards the gastro- enteric mucous membrane. The same may be said of the pulmonary mucous membrane. Through it, oxygen and nitrogen pass to reach the blood in the lungs, as well as carbonic acid in its way outwards. Aromatic substances, such as spirit of turpentine, breathed for a time, are detected in the urine; proving that their aroma has been absorbed; and it is by absorption, that contagious miasmata probably produce their pestiferous agency. Dr. Madden,^ however, thinks that the lungs do not absorb watery vapour with the rapidity, or to the extent, that has been imagined ; whilst Dr. A. Combe^ hazards the hypothesis, that owing apparently to the extensive absorption of aqueous vapour by the lungs, the inhabitants of marshy and humid districts, as the Dutch, are remarkable for the predominance of the lymphatic system. Not only do the tissues, as we have seen, suffer imbibition by fluids, but by gases also : the experiments of Chaussier and Mitchell astonish us by the rapidity and singularity of the passage of the latter through the various tissues ; — the rapidity varying according to the permea- bility of the tissue, and the penetrative power of the gas. a. Cutaneous Absorption. On the subject of cutaneous ahsorjjtion^ much difference of sentiment has prevailed ; — some asserting it to be possible to such an extent, that life may be preserved, for a time, by nourishing baths. It has also been repeatedly affirmed, that rain has calmed the thirst of shipwrecked mariners who have been, for some time, deprived of water. It is obvious, from what we know of absorption, that, in the first of these cases, the water only could be absorbed ; and even the possibility of this has been denied by many. Under ordinary circumstances, it can happen to a trifling extent only, if at all; but, in extraordinary cases, where the system has been long devoid of its usual supplies of moist- ure, and where we have reason to believe, that the energy of absorp- tion is increased, such imbibition may be possible. Sanctorius,^ Von Gorter," Keill,* Mascagni,^ Madden,' E. L. Young," Dill,^ and others believe, that this kind of absorption is not only frequent but easy. It has been affirmed, that after bathing the weight of the body has been manifestly augmented; and the last of these individuals has adduced many facts and arguments to support the position. Strong testimony has been brought forward in favour of extensive absorption of moist- ' Experimental Inquiry into the Physiology of Cutaneous Absorption, p. G4, Edinb., 1838. 2 Principles of Physiology applied to the Preservation of Health, 5th edit., p. 72, Edin., 1S3G. 3 De Static. Medic, Lugd. Bat., 1711. * De Persjiirat. Insensib., Lugd. Bat., 1736. 5 Teatamin. Medico-Physic, Lond., 1718. ^ Vas. Lymphat. Hist., Senis, 1783. ' Op. cit., p. 58. ® De Cutis lulialatione, Edinb., 1813. ^ Edinb. Medico-Chir. Transact., ii. 350. 264: ABS0RPTI03S'. ure from the atmospliere. Tliis is probably effected ratlier tlirougb the puhnouary mucous surface than the skin, A case of ovarian dropsy is referred to by Dr. Madden/ in which the patient, during eighteen days, drank 692 ounces of fluid; and discharged by urine and paracentesis 1298 ounces, being an excess of 606 ounces of fluid egesta over the fluid ingesta. I3ishop Watson, in his Chemical Essays, states, that a lad at Newmarket, having been almost starved, in order that he might be reduced to the proper weight for riding a match, was weighed at 9, and again at 10, A. M., when he was found to have gained nearly 30 ounces in weight in the interval, although he had only taken half a glass of wine. Dr. Carpenter^ gives a parallel case, which was related to him by Sir G. Ilill, Governor of St. A^incent. A jockey had been for some time in training for a race in which Sir G. Hill was much interested, and had been reduced to the proper weight. On the morning of the race, suffering much from thirst, he took "one cup of tea, and shortly afterwards his weight was found to have increased six pounds, so that he was incapacitated for riding. These cases certainly appear difficult of belief: yet the au- thority is good. Dr. Carpenter presumes, that nearly the whole of the increase in Bishop Watson's case, and at least three-fourths of it in Sir G. Hill's case, must be attributed to cutaneous absorption, which was probably stimulated by the wine that was taken in the one, and by the tea in the other. Bichat was under the impression, that, in this way he imbibed the tainted air of the dissecting room, in which he passed a large portion of his time. To avoid an objection, that might be urged against this idea, — that the miasmata might have been absorbed by the air-passages, he so contrived his experiment, as by means of a long tube, to breathe the fresh outer air ; when he found, that the evidence, which consisted in the alvine evacuations having the smell of the miasmata of the dissecting-room, continued. It is obvious, however, that such an experiment would hardly admit of satisfactory execution, and it is even doubtful, whether there was any actual relation between the assigned effect and the cause. The testi- mony of MM. Andral, Boyer, Dumcril, Dupuytren, Serres, Lallemand, Ribes, Lawrence, Parent-Duchatelet, and that afforded by the author's own observation, are by no means favourable to the great unwhole- someness of cadaveric exhalations.^ Dr. J. Bradner Stuart"* found, after bathing in infusions of madder, rhubarb, and turmeric, that the urine was tinged with these substances. A garlic plaster affected the breath, when every care was taken, by breathing through a tube connected with the exterior of the apartment, that the odour should not be received into the lungs. Dr. Thomas SewalP found the urine coloured, after bathing the feet in infusion of madder, and the hands in infusions of madder and rhubarb. Dr. Mussey'* proved, that if the body be immersed in a decoction of mad- ' Op. cit., p. 55. 2 Principles of Human Physiology, Araer. edit., p. 148, Philacl., 1855. ^ Parent-Ducliatelet, Hygiene Publicjiie, Paris, 183G ; and the remarks of the author in his Human Health, p. 77, Philad., 1844. * New York Med. Repos., vols. i. and iii. 1810-11. 5 Med. and Physical Journ., xxxi. 80, Loud., 1814. 6 Philad. Medical and Physical Journal, i. 288, Philad., 1808. ACCIDENTAL. 265 der, the substance may be detected in the urine, by using an appro- priate test. Dr. Barton found, that frogs, confined in dry glass ves- sels, became enfeebled, diminished in size, and unable to leap; but that, on the introduction of a small quantity of water, they soon acquired their wonted vigour, became plump, and as lively as usual in their motions.^ M. W. F. Edwards^ of Paris, is, also, in fiivour of absorption being carried on by the skin to a considerable extent. To deny cutaneous absorption altogether is impossible. It is a chan- nel, in fact, by which we introduce one of our most active remedial agents into the system; — and it has not unfrequently happened, where due caution has been omitted, that the noxious effects of different mine- ral and other poisons have been developed by their application to the surface, but it is by no means common or easy, when the cuticle is sound, unless the substance employed possesses unusually penetrating properties. M. Chaussier found, that to kill an animal, it is sufficient to make sulphuretted hydrogen gas act on the surface of the body, taking care that none gets into the air-passages: the researches of Prof. J. K. MitchelP have also shown that this gas is powerfully penetrant. Unless, however, the substances, in contact with the epidermis, are of such a nature as to attack its chemical composition, there is usually no extensive absorption. It is only of comparatively late years, that physiologists have ven- tured to deny, that the water of a bath, or the moisture from a damp atmosphere, is taken up under ordinary circumstances; and if, in such cases, the body appears to have increased in weight, it is affirmed, and with some appeai'ance of truth, that this may be owing to diminution of the cutaneous transpiration. It is, indeed, probable, that one great use of the epidermis is to prevent the inconveniences to which we should necessarily be liable, were such absorption easy. This is con- firmed by the fact, that if the skin be deprived of the epidermis, and the vessels that creep on the outer surface of the true skin be thus ex- posed, absorption occurs as rapidly as elsewhere. J. Miiller afffrms, that saline solutions applied to the corium penetrate the capillaries in a second of time. To insure this result in inoculation and vaccination, the matter is always placed beneath the cuticle; and, indeed, the small vessels are generally slightly wounded, so that the virus gets imme- diately into the venous blood. Yet — it is proper to remark — the lizard, whose skin is scaly, after having lost weight by exposure to air, reco- vers its weight and plumpness when placed in contact with water; and if the scaly skin of the lizard permits such absorption, M. Edwards thinks it impossible not to attribute this property to the cuticle of man. When the epidermis is reujoved, and the system is affected by substances placed in contact with the true skin, we have the endermio method of medication. M. Scguin'' instituted a series of experiments to demonstrate the ab- sorbent or non-absorbent action of the skin. His conclusion was, that '■ Klapp, Inangnral Essay on Cuticular Absorption, p. 30, Philad., 1805. * Sur rintluence des Agens Physiques ; or l)rs. Hodgkin and Fisher's translation, p. 61, and p. 187, &c., Lond., 1832. ' Anier. Journal of the Med. Sciences, vii. 44 ; and p. 68 of this work. * Annales de Chimie, xc. 185. 266 ABSORPTION. water is not absorbed, and that the epidermis is a natural obstacle to the action. To discover, whether this was the case as regarded other fluids, he experimented on individuals labouring under venereal afi'ec- tions, who immersed their feet and legs in a bath, composed of sixteen pints of water and three drachms of corrosive chloride of mercury, for an hour or two, twice a day. Thirteen, subjected to the treatment for twenty-eight days, gave no signs of absorption; the fourteenth was manifestly affected, but he had itchy excoriations on the legs ; and the same was the case with two others. As a general rule, absorption ex- hibited itself in those only whose epidermis was not in a state of inte- grity. At the temperature of 7-i° Fahrenheit, however, the sublimate was occasionally absorbed, but never the water. From other experi- ments, it appeared evident, that the most irritating substances, and those most disposed to combine with the epidermis, were partly absorbed, whilst others were apparently not. Having weighed a drachm (seventy- two grains, ^Jo/cZs de marc) of calomel, and the same quantity of camboge, scammony, salt of alembroth, and tartar emetic, M. Seguin placed an individual on his back, washed the skin of the abdomen carefully, and applied to it these substances at some distance from each other, covering each with a watch-glass, and maintaining the whole in situ by a linen roller. The heat of the room was kept at 65°. M. Seguin remained with the patient, in order that the substances should not be displaced : and he protracted the experiment for ten hours and a quarter. The glasses were then removed, and the substances carefully collected and weighed. The calomel was reduced to 71|- grains. The scammony weighed 71|; the camboge, 71; the salt of alembroth, 62 grains,^ and the tartar emetic 67 grains.^ It requires, then, in order that matters shall be absorbed b}^ the skin, that they shall be kept in contact with it, so as to penetrate its pores, or the channels by which the cutaneous transpiration exudes; or else that they shall be forced through the cuticle by friction, — the iatraliptic mode. In this way, the substance comes in contact with the cutaneous vessels, and enters them probably by imbibition. Certain it is, that mercury has been detected in the venous blood by Colson, Christison, Cantu, Autenrieth, Zeller, Schubarth, and others.^ Not long after the period that M. Seguin was engaged in his experi- ments. Dr. Eousseau,'* of Philadelphia, contested the existence of ab- sorption through the epidermis, and attempted to show, in opposition to the experiments we have detailed, that the pulmonary organs, and not tile skin, are the passages by which certain substances enter the system. By cutting off all communication with the lungs, which he effected by breathing through a tube communicating with the atmo- sphere on the outside of the chamber, he found, that although the sur- face of the body was bathed with the juice of garlic, or the spirit of turpentine, none of the qualities of these fluids could be detected, either in the urine, or the serum of the blood. From subsequent experiments, ' Several pimples were excited on the part to which it was applied. ^ Magendie's Precis, &c., ii. 262. ' The author's General Therapeutics and Materia Medica, 5th edit., i. 108, Philad., 1853. * Experimental Dissert, on Absorption, Philad., 1800. ACCIDENTAL. 267 performed by Dr. Rousseau, assisted by Dr. Samuel B. Smitb/and many of which Professor Chapman^ witnessed, the following results were de- duced. First^ That of all the substances employed, madder and rhubarb were those only that affected the urine, — the latter of the two more readily entering the system; and secondly^ that the power of absorption is limited to a ver}^ small portion of the surface of the body. The only parts, indeed, that seemed to possess it, were the spaces between the middle of the thigh and hip, and between the middle of the arm and shoulder. Topical bathing, with a decoction of rhubarb or madder, and poultices of these substances applied to the back, abdomen, sides, or shoulders, produced no change in the urine; nor did immersion of the feet and hands for several hours in a bath of the same materials afford the slightest proof of absorption. From these and other facts, sufficiently discrepant it is true, we are justified in concluding, that cuticular absorption, under ordinary cir- cumstances, is not easy; but we can readily conceive, from the facility with which water soaks through animal tissues, that if the animal body be immersed sufficiently long in it, and especially if the vessels have been previously drained, imbibition may take place to a considerable extent. This, however, would be a physical absorption, and might be effected as well in the dead as in the living body. b. Other Accidental Absorptions. Amongst the adventitious absorptions have been classed all those that are exerted upon substances retained in the excretory ducts, or situate in parts not natural to them. The bile, arrested in one of the biliary ducts, affords us, in jaundice, a familiar example of such ab- sorption by the positive existence of bile in the bloodvessels; although the yellow colour has been gratuitously supposed to be caused by an altered condition of the red globules, and not by the presence of bile. This condition of the red globules would account for some of the symptoms, — as the yellow colour of the skin, and urine, — but it does not explain the clayey appearance, which the evacuations present, and which has been properly ascribed to the absence of the biliary secre- tion. We have, moreover, examples of this kind of absorption, where blood is effused into the areolar membrane, as in the case of a common sprain, or in those accumulations of fluid in various cavities, that are found to disappear by time ; — the serous portion being taken up at first with some of the colouring matter, and, ultimately, the fibrin. In the case of accumulation of the serous fluid that naturally lubricates cavities, it is of such a character — the aqueous portion at least — as to be imbibed with facility, and probably passes into the veins, in this manner, — the functions of exhalation and absorption consisting mainly, in such case, of transudation and imbibition. But absorption is not confined to these fluids. It must, of course, be exerted on all morbid deposits ; and it is to excite the action of the absorbents, that our remedial agents are directed. This absorption — in the case of solids — is of the interstitial kind ; and, as the morbid ' Philad. Med. Museum, i. 34, Philad., 1811. 2 Elements of Therapeutics and Materia Medica, 6th edit., i. 65, Philad., 1831. 268 RESPIRATION. formation has to undergo an action of elaboration, it ouglit to be refer- red to lymphatic agency. To conclude the function of absorption : — All the products, — whether the absorption has been chyliferous, lymphatic, or venous, — are united in the venous system, and form part of venous blood. This fluid must, consequently, be variable in its composition, in proportion to the quan- tity of heterogeneous materials taken up by the veins, and the activity of chyliferous and lymphatic absorption. It is also clear, that, between the parts of the venous system into which the supra-hepatic veins, — loaded with the products of intestinal absorption of fluids, — enter, and the opening of the thoracic duct into the subclavian, the blood must differ materially from that which flows in other parts of the system. All, however, undergo admixture in their passage through the heart ; and all are converted into arterial blood by the function, that Avill next eno:a":e us. CHAPTER III. RESPIRATION. The consideration of the function of absorption has shown how the different products of nutritive absorption reach the venous blood. By simple admixture with this fluid they do not become converted into a substance, capable of supplying the losses sustained by the frame from xhe different excretions, Nothing is better established than the fact, that no being, and no part of any being, can continue its functions un less supplied with blood, that has become arterial by exposure to air It is in the lungs, that the absorbed matters undergo their final conver sion into that fluid, — by a function, which has been termed hcematosis the great object of that which we have now to investigate — Respira- tion. This conversion is occasioned by the venous blood of the pul- monary vessels coming in contact with air in the air-cells of the lungs, during which th'e blood gives to the air some of its constituents, and, in return, the air parts with its elements to the blood. To comprehend this mysterious process, we must be acquainted with the pulmonary apparatus, as well as with the properties of atmospheric air, and the mode in which the contact between it and the blood is effected. 1. ANATOMY OF TUE KESPIRATORY ORGANS. The thorax or chest contains the lungs, — the great agents of respira- tion. It is of a conical shape, the apex of the cone being formed by the neck, and the base by a muscle, which has already been referred to more than once, — the diaphragm. The osseous framework. Fig. 76, is formed, posteriorly^ of twelve dorsal vertebrse; anteriorly,^ of the sternum, originally composed of eight or nine pieces ; and laterally,, of twelve ribs on each side, passing from the vertebraa to, or towards, the sternum. Of these, the seven uppermost extend the whole distance from the spine to the breast-bone, and are called true or sternal^ and at times, vertebrosternal ribs. They EESPIEATOEY ORGANS. 269 ^^^li^ become larger as they descend, and are situate more obliquely in re- gard to the spine. The other five, called false or asternal^ do not pro- ceed as fer as the sternum ; the cartilages of three of them join that of the seventh true rib, whilst the two lowest have no union with those above them, and are, therefore, called floating ribs. These false ribs Fig. 76. become shorter and shorter as we descend ; so that the seventh true rib may be regarded as the com- mon base of two cones, formed by the true and false ribs respectively. The different bones constituting the thorax are so articulated as to admit of motion, and thus of dilata- tion and contraction of the cavity. The motion of the vertebrae on each other is described under an- other head. It is not materially concerned in the respiratory move- ments. The articulation of the ribs with the spine and sternum de- mands attention. They are articu- lated with the spine in two places, — at the capitulum or head, and at the tubercle. In the former of these, the extremity of the ribs, encrusted with cartilage, is received into a depression, similarly encrusted, at the side of the spine. One half of this depression is in the body of the upper vertebra; the other half in the one beneath it; and, conse- quently, partly in the intervertebral fibro-cartilage between the two. The joint is rendered secure by various ligaments; but it can move readily up and down on the spine. In the first, eleventh, and twelfth ribs, the articulations are with single vertebra3 respectively. In the second articulation, the tubercle of the rib, also encrusted with carti- lage, is received into a cavity in the transverse process of each cor- responding vertebra ; and the joint is rendered strong by three distinct ligaments. In the eleventh and twelfth ribs, this articulation is want- ing. The articulation of the ribs with the sternum is effected by an intermediate cartilage, which becomes gradually longer, from the first to the tenth ribs, as seen in Fig. 76. The end of the cartilage is re- ceived into a cavity at the side of the sternum; and the junction is strengthened by an anterior and a posterior ligament. This articula- tion does not admit of much motion ; but the existence of a synovial membrane shows, that it is destined for some. The cavity of the thorax is completed by muscles. In the intervals between the ribs are two planes, whose fibres pass in inverse directions, and cross each other. These are the iutercosials. The diaphragm forms the septum between the thorax and abdomen. Above, the cavity Anterior View of Thorax. 1. Superior piece of sternum. 2. Middle piece. 3. Inferior piece, or ensiform cartilage. 4. First dorsal vertebra. 5. Last dorsal vertebra. 6. Fir.st rib. 7. Its head. 8. Its neck, resting against transverse process of first dorsal vertebra. 9. Its tuberosity. 10. Seventh or last true rib. 11. Costal cartilages of true ribs. 12. Two last fal.se ribs — floating ribs, 13. Tlio groove along lower border of rib for lodgment of intercostal vessels and nerve . 270 RESPIRATION. is open ; and tlirougli tlie opening numerous vessels and nerves enter. The muscles, concerned in the respiratory function, are numerous. The most important of them is the diaphragm. It is attached, by its circumference, around the base of the chest; but its centre rises into the thorax; and, during its state of relaxation, forms an arch, the middle of which is opposite the inferior extremity of the sternum. It is tendinous in its centre, and is attached by two fasciculi, called jyillars, to the spine, — to the Fig. T7. bodies of the first two lumbar vertebrae. It has three apertures ; one before for the pas- sage of the vena cava inferior; and two be- hind, between the pil- lars, for the passage of the oesophagus and aorta. The other great muscles of respiration are the serratns posticus inferior^ serratus posti- cus superior^ levatores costarum^ intercostal muscles, infra-costales, and triangularis sterni or sterno-costalis ; but, in an excited condition of respiration, all the muscles, that raise and depress the ribs, di- rectly or indirectly, participate — as the scalejii, sterno-mastoidei, pectoralis, (major and minor,) serratus major anticus, ahdominal mus- cles, &LQ,. In the structure of the lungs, as M. Ma- gendie' has remarked, nature has resolved a Anterior View of the Thoracic Viscera in situ, as shown by the removal of the Anterior Parietes of the Thorax. 1. Superior lobe of right lung. 2. Its middle lobe. 3. Its inferior lobe. 4, 4. Lobular fissures. 5, 5. luterual layer of costal pleura forming the right side of the anterior mediastinum. 6, 6. Right dia- phragmatic portion of pleura costalis. 7, 7. Right pleura costalis on the ribs. S. Superior lobe of left lung. 9. Its inferior lobe. 10,10. Interlobular lissures. 11. Portion of pleura costalis which forms the left side of the anterior mediastinum. 12. Left diaphragmatic portion of pleura costalis. 13. Left pleura costalis. 14, 14. The middle space niCchanical problem of between the pleurse, known as the anterior mediastinum. 15. Pen- . i . cardium. 16. Fibrous partition over which the plcur;c are reflected. 17. Trachea. 18. Thyroid gland. 19. Anterior portion of thyroid cartilage. 20. Primitive carotid artery. 21. Subclavian vein. 22. Internal jugular vein. 23. Brachio-cephalic vein. 24. Abdominal aorta. 25. Xiphoid cartilage. extreme difficulty. The problem was, — to es- tablish an immense surface of contact be- tween the blood and air, in the small space occupied by the lungs. The admirable arrangement adopted consists in this, — that each of the minute vessels, in which the pulmonary artery terminates and the pul- ' Precis, &c., ii. 307. EESPIRATOEY ORGANS. 271 monary veins originate, is surrounded on every side by air. The lungs are two organs of considerable size, situate iii the lateral parts of the chest, and subdivided into lobes and lobules, the sliape and number of which cannot be readily determined. They are termed right and left^ respectively, according to the side of the cavity of the chest which they occupy. The former consists of three Fig. 78. lobes; the latter of two. Each of these exactly fills the corresponding cavity of the pleura; and they are separated from each other by a duplicature of the pleura — (the serous membrane that lines the chest, and is re- flected over the lungs) — and by the heart. The colour of the lungs is generally of a marble blue ; and the exterior is furrowed by figures of hexagonal shape. The appearance is not, however, the same at all ages, and under all circumstances. In in- fancy, they are of a pale red; in youth, of a darker colour ; and in old age, of a livid blue. The elements that compose them are ; — the ramifications of the trachea ; those of the pulmonary artery and pulmonary veins, be- sides the organic ele- ments, that appertain to every living struc- ture, — arteries, veins. Posterior View of the Thoracic Viscera, showing their relative positions by the removal of the Posterior Portion of the Pa- rietes of the Thorax. 1, 2. Upper and lower lobes of right lung. 3. Interlobular fis- sures. 4. Internal portion of pleura custalis, forming one of the sides of posterior mediastinum. 5. Twelfth rib and lesser diaphragm. 6. Reflection of the pleura over the greater muscle of the diaphragm on the right .side. 7, 7. Right pleura costalis adhering to the ribs. 8, 9. The two lobes of the left lung. 10, 10. Interlobular fissures. 11, 11. Left pleura, forming the parietesof the posterior mrdia.stinum. 12, 1.3. Its reflections over the diaphragm on this side. 1-t, 1-1. Left pleura costalis on the parietes of the chest. 1.5. Trachea. IG. Larynx. 17. Opening of the larynx and the epiglottic cartilage in situ. 18. Root and top of the tongue. 19, 19. Right and left bronchia. 20. The heart enclosed in pericardium. 21. Upper portion of diaphragm on which it rests. 22. Section of oesophagus. 2.3. Section of aorta. 21. Arteria innominata. 25. Primitive carotid arteries. 26. Subcla- 1 , . n vian arteries. 27. Internal jugular veins. 28. Second cervical ver- jymphatlCS, nerves, and. tebra. 29. Fourth lumbar. areolar tissue. The ramifications of the windpipe form the cavity of the organ of respira- tion. The trachea is continuous with the larynx, from which it re- ceives the external air conveyed to it by the mouth and nose. It passes down to the thorax, at the anterior part of the neck, and bifur- cates opposite the second dorsal vertebra, forming two large canals called bronchi or bronchia. One of these goes to each lung ; and, after 272 RESPIRATION. numerous subdivisions, becomes imperceptible ; lieuce, tlie multltiulin- ous speculations that have been indulged regarding the mode in which the bronchial ramifications terminate. Malpighi' believed, that they form vesicles, at the inner surface of which the pulmonary artery rami- fies. Reisseisen^ describes the vesicles as of a cjdindrical, and some- what rounded figure ; and states, that they do not communicate with each other. Ilelvetius,^ on the other hand, affirmed, that they end in cells, formed by the dift'erent Fig- 79. constituent elements of the lung, — the cells having no determinate shape, or regular connexion with each other; whilst M. Magendie'' asserts, that the minute bronchial division, which arrives at a lobe, does not enter it, but terminates suddenly as soon as it has reached the paren- chyma; and, he remarks, that as the bronchus does not penetrate the spongy tissue of the lung, it is not probable, that the surface of the cells, with which the air comes in contact, is lined by a prolongation of the mucous coat, which forms the inner membrane of the air-passages. Mr. Hassall,^ however, contrary to the opinion of most observers, and — as will be seen — to that of Mr. Eainey, one of the most recent of them, af- firms, that in sections of fresh lungs "it is a very easy matter not merely to determine the existence of epithelium in the air-cells, but also the fact of its cylinder and ciliated form and character," and this "fact" of the epithelium extending from the bronchial tubes into them • — he adds — would seem in itself to imply that the mucous membrane also lines them. The ramifications of the pulmonary artery are another constituent element of the lung. This vessel arises from the right ventricle of the heart, and, at a short distance from that organ, divides into two branches ; one passing to each lung. Each branch accompanies the corresponding bronchus in all its divisions ; and, at length, becomes capillary and imperceptible. Its termination, also, has given rise to ' Epist. de Pulmon., i. 133. 2 Ueber den Bau der Lungen, u. s. w., Berlin, 1822 ; also, in Latin, Berl., 1822. 3 Memoires de I'Academ. pour 1718, p. 18. * Precis, &c., ii. 309. ^ The Microscopic Anatomy of tlie Human Body in Health and Disease, part xii. p. 381, London, 1848. A shaded Diagram, representing the Heart nnd Groat Vessels, injected and in connexion with the Luugsj the Pericardium is removed. 1. Right auricle. 2. Vena cava superior. 3. Vena cava inferior. 4. Kigiit ventricle. 5. Pulmonary artery, divid- ing into two branches n, a, one for the right, the other for the left lung. 6. Point of the left auricle. 7. Part of left ventri- cle. 8. Aorta. 9, 10. Two lobes of the left lung. 11,12,13. Three lobes of the right lung, a, a. Right and left pulmo- nary arteries. 6, h. Right and left bronchi, v, v. Right and left pulmonary veins. The relative position of these three vessels is seen to ditfer on tlie two sides. RESPIRATORY ORGAN'S. 273 Arrangement of the Capillaries of the Air-cells of the Human Lung. conjecture. Malpiglii conceived it to end at the mucous surface of the bronchi in an extremely delicate network, which he called rete onirabile ; and this was, likewise, the opinion of Reisseisen. Bichat^ admitted at the extremities of the pulmonary artery, and between that artery and the veins of the same name, vessels of a more delicate charac- ter, which he conceived to be the agents of hgematosis, and called the capillary system of the lungs. This, however, is nothing more than the fine dense capillary net- work, formed by the distribution of the artery on the air-cells, from which the pidmonaj-y veins arise. Their radicles communicate freely with those of the pulmonary ar- tery. When we observe them dis- tinctly, they are found uniting to constitute larger and larger veins, until they ultimately end in four great trunks, which open into the left auricle of the heart. The pulmonary arteries do not anastomose in their course ; and according to Dr. Cammann,^ the capillaries of one lobule do not communicate with those of another: the interstitial areolar membrane even of the most minute lobules was seen entirely free from colour when a coloured injection was thrown into the vessels. In addition to these organic constituents, the lung, like other organs, receives arteries, veins, lymphatics, and nerves. It is not nourished by tlie blood of the pulmonary artery, which is not adapted for the purpose, seeing that it is venous. The hrondiial arteries are its nutritive vessels. They arise from the aorta, and are distributed to the bronchi. Around the bronchi, and near where they dip into the tissue of the lung, lymphatic glands — bronchial glands — exist, the colour of which is almost black, and with which the few lymphatic vessels, that arise from the superficial and deep-seated parts of the lung, communicate, llal- ler^ has traced the efferent vessels pf these glands into the thoracic duct. The nerves, distributed to the lungs, proceed chiefly from the eighth pair or pneumogastric. A few filaments of the great sympathetic are also sent to them. T'he eighth pair — after having given off the superior laryngeal nerves, and some twigs to the heart — interlaces with nume- rous branches of the great sympathetic, and forms an extensive nervous network, called anterior pulmonary plexus. After this, the nerve gives off the reourrents, and interlaces a second time with branches of the great sympathetic, forming another network, called posterior pulmonary plexus. It then proceeds to the stomach, where it terminates. (See Fig. 24.) From these two plexuses the nerves proceed, that are dis- tributed to the lungs. These accompany the bronchi, and are spread ' Anatomie Generale, edit, de MM. Beclard, Blandin, and Magendie, ii. 381-386, Paris, 1832. ^ New York Journal of Medicine, Jan., 1848. * Elem. Physiologiae, viii. 2, § 15, Lausann. 1764. VOL. I. — 1« 274 RESPIEATIOX. chiefly on tlie mucous membrane of the air-tubes. The lung likewise receives some nerves directly from the three cervical ganglions of the great sympathetic, and from the first thoracic ganglion. In addition to these, a distinct system of nerves — the respiratory system, described in another part of this work — is supposed by Sir Charles Bell to be distributed to the multitude of muscles, that are associated in the respiratory function in a voluntary or involuntary manner. This system includes one of the nerves just referred to — the eighth pair — and the phrenic nerves, which are distributed to the diaphragm. The various nerves composing it are intimately connected, so that, in forced or hurried respiration, in coughing, sneezing, &c., they are always asso- ciated in action. It will be seen, however, that few physiologists now admit the respiratory system of Sir Charles. Lastly ; the lungs are constituted also of areolar tissue, which has been termed interlobular tissue; but it does not differ from areolar tissue in other parts of the body. Such are the constituent elements of the pulmonary tissue ; but, with regard to the mode in which they are combined to form the intimate texture of the lung we are not wholly instructed. We find, that the lobes are divided into lobules, and these, again, seem to be subdivided almost indefinitely, forming an extremely delicate spongy tissue, the areolae of which — air-cells or lung-vesicles — can only be seen by the aid of the microscope.^ It is generally thought, that the areolae commu- nicate with each other, and that they are enveloped by the areolar tissue which separates the lobules. M. Magendie^ inflated a portion of lung, dried and cut it in slices, in order that he might examine the deep-seated cells. These appeared to him to be irregular, and to be formed by the final ramifications of the pulmonary artery, and the primary ramifications of the pulmonary veins ; the cells of one lobule communicating with each other, but not with those of another lobule. Professor Horner,^ of the University of Pennsylvania, has attempted to exhibit that this communication between the cells is lateral. After filling the pulmonary arteries and pulmonary veins with minute injec- tion, the ramifications of the bronchi, with the air-cells, were distended to their natural size by an injection of melted tallow. The latter, being permitted to cool, the lung was cut into slices and dried. The slices were subsequently immersed in spirit of turpentine, and digested at a moderate heat for several days. By this process, all the tallow was removed, and the parts, on being dried, appeared to exhibit the air-cells empty, and, seemingly, of their natural size and shape. Pre- parations, thus made, appear to show the air-cells to be generally about the twelfth of a line in diameter, and of a spherical form, the cells of each lobule communicating freely, like the cells of fine sponge, by lateral apertures. The lobules, however, only communicate by branches of the bronchi, and not by contiguous cells. This would seem to negative the presumption of some anatomists and physiologists. — as Reisseisen, Blumenbach, Cuvier, &;c., — that each air-cell is insulated, communicating only with the minute bronchus that opens into it; whilst it confirms the views of Haller, Monro (Secundus), Boyer, ' Hassall, op. cit. ^ Precis, &c., ii. 309. ' American Journal of the Medical Sciences for Feb. 1832, p. 538, and op. cit. BESPIRATORY ORGANS. 275 Sprengel, Magendie, Carpenter, and others; — but it is not easy to de- cide positively, where all is so minute. The observations of Dr. Addi- son^ led him to maintain, that the views of Eeisseisen and others are certainly true as regards the foetal lung, in which the ultimate subdi- visions of the bronchial tubes termiuate in closed extremities. But when an animal has respired, the terminations are said to experience a great change. The membrane composing them ofters but slight re- sistance to the pressure of the air, and is pushed forwards, and dis- tended laterally into rounded inflations, forming a series of cells, which are moulded by mutual pressure into various angular forms, and which communicate freely with each other by large oval apertures. The passages, thus formed, do not communicate otherwise than by their connexion with the same bronchial tube, and the bloodvessels lie be- tween the contiguous walls of each two of them, so that the blood in the capillaries is exposed to air on both sides. It would appear, also, from the researches of M. Bourgery,^ that the developement of the air-cells, — and, consequently, the capacity for forcible inspiration, — continues in man to the age of thirty, at which time the capacity is greatest. Subsequently, it decreases, especially in those who suffer from cough, — the violence of the respiratory eftbrt often causing rup- ture of the air-cells, and thus gradually producing the emphysematous state of the lungs so common in old people. After thii-ty, the capa- city for forcible inspiration diminishes one-fifth in the first twenty years; one-fifth more in the next ten; and nearly one-half in the next twenty; and this gradual decrease of capacity for forcible inspiration is true of all persons, although one may have a greater general capa- city of respiration than another of the same age. Hence the young person possesses a greater capacity of respiration, as it were, in reserve. The aged have little, and are, therefore, unfit for great exertion. The observations of Mr. Eainey,^ which have been adopted by many histologists, lead to the belief, that when the bronchi have attained the diameter of from g'^th to g'^th of an inch, they gradually lose their cylindrical form, and appear more like ir- Fig- 81. regular passages — termed by Mr. Kainey intercellular or lobular ]:)assages — through the substance of the lung. These passages are clustered with air-cells, which have the appearance of polyhedral alveolar ca- vities separated by exceedingly thin septa, and do not open into one another by auas- Air-Ceiis from an Emphysematous tomosis or lateral Communication, but com- 1 . , .""^! , ., , municate freely through the medium of 1. A group of air-cells laid open anil J <-> i • i i i exhibiting the fact that there is no late- tllC COmmOU air-paSSagC tO whicll they bc- ral iutercoinmunication. 2. Two air- , rni • i r- /tti- n-i\ cells; the one to the left exhibits its loug. i he margmal figurc [rig. 81) re- bronchiolar orifice. 3. Another group: y^pp^jp^tc. cpvprnl frrollDS of air-Cplk from to the left are represented two cells freely prCSCULS SeVCJ ai glULipb VI dll-ceiib liom communicating from the partition being r^j^ emphvSematOUS luilg, draWU the sizC ruptured by over-distensiun ; and be- I J •i-r-v/'-ii twoen the two cells to the right are ob- of uaturc jrom a preparation by JDr. (jrod- served some inflated areola; of areolar ^ i mi t ^^• oti i c).> tissue. dard. The diagrams, lugs. o2 and 80, ' Proceedings of the Royal Society, March 17, 1842; and Philos. Transact, for 1842. ^ Gazette Medieale, 16 Juillet, 1842, and Archives Generales de Med., Mars. 1843. * Medico-Chirurgical Transactions, vol. xxviii., London, 1845. Hee, also, Todd and Bowman, The Physiological Anat. and Physiology of Man, Pt. iv., p. 390, Lond. 1852. 276 RESPIRATIOISr. are given by Dr. Leidy to facilitate the understanding of the relative arrangement of the air-cells to the minute bronchial tubes^ in this view of the subject. Mr. Kainey affirms, as the result of actual ob- servation, that the mucous lining of the bronchial tube is not conti- nued along the intercellular passages and into the air-cells, a circum- stance, which, as he suggests, explains the different effects of inflam- mation of the tubes and of the air-cells ; — the latter, which are lined by fibro-areolar tissue, being accompanied by the exudation of fibrin Fig. 82. Fig. 83. Transverse Section of a portion of the Pulmonary Parenchyma. 1. The orifices of bronchioles. 2. The air-cells arranged around the bronchioles, and opening into them, but not com- municating laterally. 3. Interspaces filled with areolar tis- sue, which, when inflated, is liable to be mistaken for the true air-cells. Longitudinal Section of the termina- tion of a Bronchus. 1. The bronchiole, in which are seen the orifices (3) of the air-cells (2) ar- ranged around it and at its termina- tion. instead of mucus. Anatomists, consequently, who, by the term "air- cell," meant simply the ultimate termination of a bronchial tube ; and pathologists, who regarded bronchitis of the terminal extremities of those tubes and pneumonia as essentially alike, were nearer the truth than was generally admitted. The researches of Mr. Eainey led him to conclude — in opposition to Dr. Addison, — that the fa^us, prior to the act of respiration, possesses fully formed air-cells, which are also surrounded by capillary plexuses. M. Rossignol, who has elaborately described the minute structure of the lungs, insists on the ultimate bronchial ramifications being shaped like an inverted funnel; and hence he calls them infundibula. The cells forming a honeycomb on their interior he calls alveoli. Em- physema, according to him, seems to consist in a distension of the passages and cells, and a breaking down and obliteration of the septa, first between the cells of the same passages, and then between neigh- bouring passages, and even between contiguous lobules,^ ' Qiiain's Human Anatomy, by Quain and Sharpey, Amer. edit, by Dr. Leidy, ii. 119, Philad., 1849. ^ The Physiological Anat. and PhysioL of Man, Pt. iv. p. 391, or Amer. edit., Philad., 1853. RESPIRATORY ORGAN'S. \ 277 Kcilliker^ admits the existence of two layers in tlie air-cells — a fibrous membrane and an epithelium. The former is manifestly the much Fig. 84. Thin slice from the Pleural Surface of a Cat's Lung, considerably magnified. At the thin edge, 6 e d, alveoli are seen. In the centre (as a), where the slice is thiclier, alveoli are seen on the walls of infundCbula. attenuated mucous membrane and fibrous tunic of the bronchi entirely deprived of the smooth muscles, and consisting of a homogeneous ma- trix of connective tissue together with elastic fibres and numerous Fig. 85. Bronchial termination in the Lung of the Bog. Fig. 86. a. Tube (lobular passage) branching towards the infuudi- bula. 6. One of the infundibula. c. Septa projecting inwards ou the infundibular wall and form- ing the alveoli, or cells. iu*;-Xiat^' Air-oells of Human Lung, with intervening tissues. n. Epithelium. 6. Elastic trabeculaj. c. Membranous wall, with fine elastic fibres. ' Mikroskopische Anatomie, ii. 315, Leipz., 1852, or Amer. edit, of Sydenham So- ciety'a edition of KiJlliker's Manual of Histology, }). 579, Pliilad., 1854. 278 EESPIRATIOX. vessels. These fibres run between the air-cells in the form of trabeculre, and coalesce with the lining membrane so as to strengthen it. The epithelial la3^er is the tesselated form constituted of minute polygonal cells without cilia. Dr. Thomas Williams, " who has devoted many special examinations to this particular point, is now convinced, that a fine pavement epithelium does cover these parts," and such is the opinion of Schroder van der Kolk.^ The position is contested, how- ever, at great length by Mr. Rainey.^ The surface afforded by the air-cells is immense. Hales' supposed them to be polyhedral, and about one-hundredth part of an inch in diameter. The surface of the bronchi he estimated at 1635 square inches ; and that of the air-cells at 40,000, making the surface of the whole lungs 41,635 square inches or 289 square feet, — equal to 19 times the surface of the bodj^, which, at a medium, he computes to be 15 square feet. Keill* estimated the number of cells to be 1,744,186,015; and the surface 21,906 square inches ; and Lieberkiihn has valued it at the enormous amount of 1500 square feet.* M. Rochoux^ estimates the number of cells at 600,000,000, and that there are about 17,790 grouped around each terminal bronchus. All that we can derive from these mathematical conjectures is, that the extent of surface is surpris- ing, when we consider the small size of the lungs themselves. The diameter of the lobular passages has been estimated at from the yigth to 200^^ of an inch, and that of the cells from ^^^ to -^\^ of an inch according to the measurements of ]\[essrs. Todd and Bowman. In a preparation of the lung given them by Professor Retzius, they measured gogth; and Dr. Addison makes them from aao^^ ^^ soo^^ of an inch.'^ Weber makes their diameter from the 200*^ ^^ ^^^ to*^ of an inch ; and Kolliker and Carpenter^ agree with him, while Mole- schott estimates them at much less. Professor Horner^ has published an account of various experiments, which exhibit the ready communication between the pulmonary air- vesicles and veins. By fixing a pipe into the "human trachea, and per- mitting a column of water to pass gently, he found that the air-cells became distended with water ; and that the left side of the heart filled, and the aorta discharged water freely from its cut branches. This ex- periment he repeated on human lungs on difl'erent occasions, and with like results. A^ery little water flowed from the pulmonary artery. In ' Dr. T. Williams, art. Respiration, Organs of, in Cyclop, of Anat. and Physiol., Ft. 45, p. 271, March, 1855. ^ Brit, and For, Med.-Chir. Rev., Oct., 1855, p. 491. 3 Statical Essays, i. 242. * Tentam. Med. Phys., p. 80. 5 Blumenbach,inEiliotson's Physiology, p. 197, Lond., 1835. Mr. E. Wilson (Healthy Skin, Amer. edit., p. 52, Pliilad., 1S54) observes: "The number of air-cf^ls in the two lungs has been estimated at 1,7-14,000,000, and the extent of the skin which lines the cells and tubes together at 1500 square feet. This calculation of the number of air- cells and the extent of the lining membrane rests, I believe, on the authority of Dr. Addison, of Malvern." ! ^ Gazette Medicale, 4 Janv., 1845. 7 Todd and Bowman, Op. cit., p. 392. 8 Principles of Human Physiology, p. 285, Amer. edit., Philad., 1855. ^ Amer. Journ. of the Medical Sciences, April, 1843, p. 332; and Special Anatomy and Histology, 6th edit., ii. 163. RESPIRATORY ORGANS. 279 the sheep and the calf, however, when the experiment was practised upon them after they had been pretty thoroughly evacuated of blood, the water passed freely through both the pulmonary veins and the pul- monary arteries. Dr. Horner is disposed to infer, that his experiments exhibit a communication of the pulmonary air- vesicles by a direct route with the pulmonary bloodvessels, especially the veins ; but this may well be questioned. It is possible, that such a communication may really have been made by the force of the column of water ; and if not so, the passage of the fluid from air-cells to bloodvessels might have been effected through the pores, as in ordinary imbibition, which, we have elsewhere seen, is readily accomplished in the lungs, but not more readily perhaps than in the case of serous and other tissues under favourable circumstances. Hemorrhage by transudation occurs, we know, most rapidly at times through the coats of vessels, whose cohe- sion has, however, been diminished by disease ; and a thinner fluid would of course transude more easily. It can scarcely be doubted, from Dr. Horner's experiments, that a certain arrangement exists be- tweeen the air-vesicles and the pulmonary veins in man, which allows a more ready imbibition and transudation; but what that arrangement is admits of ques- tion. Each lung is covered by the pleura^ — a serous membrane analogous to the peritoneum, — and, in birds, a prolongation of the latter. This membrane is reflected from the adjacent sur- face of the lung to the pericar- dium which covers the heart, and is then spread over the in- terior paries of tlie half of the thorax to which it belongs ; lining the ribs and intercostal muscles, and covering the con- vex or upper surface of the diaphragm. There are, conse- quently, two pleura3, each of which is confined to its own half of the thorax, lining its cavity and covering the lung. Behind the sternum, however, they are contiguous to each other, and form the partition called mediastintim, which ex- tends between the sternum and spine. Fig. 87 exhibits the boundaries of the two cavities of the pleura. The middle space between is the mediasti- num. Within this septum, the Fig. 87. Outline of a Transverse Section of the Chest, show- ing the relative position of the Pleurse to the Thorax and its Contents. 1. Skin on the front of the chest drawn up by a hook. 2. Skin on the sides of the chest. 3. Tliat on the back. 4. Subcutaneous fat and muscles on tlie outside of the thorax. 5. Section of the muscles in the vertebral glitter, fi. Section of fifth dorsal vertebra. 7. Spinal canal. 8. Spinous process. 9, 9, 10, 10. Sections of ribs and intercostal muscles. 11. Their cartilages. 12. Sternum. 13. Division of the pulmonary artery. 1-t. Exterior surface of lungs. 1."). Posterior face of lungs. Id. Anterior face of lungs. 17. Inner face of lungs. 18. Anterior face of heart covered by pericardium. 19. Pul- monary artery. 20, 21. Its division into right and left branches. 22. Portion of right auricle. 2.3. Descending cava cut off at right auricle. 24. Section of left bron- chus. 2."). Section of right bronchus. 26. Section of ccsophagus. 27. Section of thoracic aorta. The space between figures 12 and IS and the two His is the anterior mediastiuiim, and the space which contains 26 and 27 is the posterior niedi.aslinum. These spaces are formed by the reflections of the pleurte. 280 RESPIRATION. heart, enveloped by the pericardium, is situate, and separates the pleurae considerably from each other. Anatomists generally subdivide the mediastinum into two regions ; one passing from the front of the peri- cardium to the sternum, called anterior mediastinum ; the other, from the posterior surface of the pericardium to the dorsal vertebrae, — pos- terior mediastinum; and, by some, the part which is within the circuit of the first ribs, is termed superior mediastinum. The second of these contains the most important organs, — the lower end of the trachea, cesophagus. aorta, vena azygos, thoracic duct, and pneumogastric nerves. The portion of the pleura covering each lung, is called pleura pulmonalis ; that which lines the thorax, pleura costalis. It is obvious that, as in the case of the abdomen, the viscera are not in the cavity of the pleura, but external to it ; and that there is no communication between the serous sac of one side and that of the other. The use of the pleura is to attach the lungs by their roots to their respective cavities, and to facilitate their movements. To aid this, the membrane is always lubricated by a fluid, exhaled from its surface. The other surface is attached to the lung in such a manner, that air cannot get between it and the parietes of the thorax. Dr. Stokes' admits a proper fibrous tunic of the lungs. In a healthy state, this capsule, although possessing great strength, is transparent, a circum- stance in which it difl:ers from the fibrous capsule of the pericardium,' and which, Dr. Stokes thinks, has probably led to its being overlooked. It invests the whole of both lungs ; covers a portion of the great vessels ; and the pericardium seems to be but its continuation, — endowed, in that particular situation, with a greater degree of strength, for purposes that are obvious. It covers the diaphragm where it is more opaque : in connection with the pleura, it lines the ribs ; and, turning, forms the mediastina, which are thus shown to consist of four layei's, — two serous and two fibrous. It seems, that Dr. Hart, of Dublin, had, for years, demonstrated this tunic to his class. It was, at one time, the prevalent belief, that air always exists in the cavity of the chest. Galen supported the opinion by the fact, that, having applied a bladder, filled with air, to a wound, which had penetrated the chest, the air was drawn out of the bladder at the time of inspiration. This was also maintained by Hamberger, Ilales,^ and numerous others. The case, alluded to by Galen, is insufficient to establish the position, inasmuch as we have no evidence, that the wound did not also implicate the pulmonary tissue. Since the time of Haller, who opposed the prevalent doctrine by observation and reasoning, the fact of the absence of air in the cavity of the pleura has been generally considered established. It is obvious, that its presence there would materially interfere with the dilatation of the lungs, and thus be productive of fatal consequences; besides, anatomy instructs us, that the lungs lie in pretty close contact with the pleura costalis. When the intercostal muscles are dissected off' and the ])leura costalis is exposed, the surface of the lungs is seen in contact with that trans- ' On Diseases of the Chest, Part i. p. 460, Dublin, 1837; or Dunglison's American Medical Library edition, p. 301, Philad., 1837. 2 Statical Essays, ii. 81. , ATMOSPHEKIC AIR. 281 parent membrane ; and when the pleura is punctured, the air rushes in, and the lungs retire, in proportion as the air is admitted. This occurs in cases of injuries inflicted upon the chest of the living animal. Moreover, if a dead or living body be placed under water, and the pleura be punctured, so as not to implicate the lungs, it has been found by the experiments of Brunn, Sprogel, Caldani, Sir John Floyer, Hal- ler,^ and others, that not a bubble of air escapes, — which would neces- sarily be the case, if air were in the cavity of the pleura. 2. ATMOSPHEKIC AIR. The globe is surrounded everywhere, to the height of fifteen or six- teen leagues, by a rare and transparent fluid called air ; the total mass of which constitutes the atvaospliere. Atmospheric air, although invi- sible, can be proved to j)ossess the ordinary properties of matter ; and, amongst these, weight. It also partakes of the character of a fluid, adapting itself to the form of the vessel in which it is contained, and pressing equally in all directions. As air is possessed of weight, it results, that every body on the earth's surface must be subjected to its pressure ; and as it is elastic or capable of yielding to pressure, thS part of the atmosphere near the surface must be denser than that above it. As a body, therefore, ascends, the pressure will be diminished; and this accounts for the dif- ferent feelings experienced by those who ascend lofty mountains, or voyage in balloons into the higher strata of the atmosphere. M. Ed- wards^ ascribes part, at least, of the effect produced upon the breath- ing at great elevations, to the increased evaporation which takes place from the skin and lungs ; and in many aerial voyages great inconve- nience has certainly been sustained from this cause. The pressure of the atmosphere at the level of the sea is the result of the whole weight of the atmosphere, and is capable of sustaining a column of water thirty-four feet high, or one of mercury of the height of thirty inches, as in the common barometer. This is equal to about fifteen pounds avoirdupois on every square inch of surface; so that the body of a man of ordinary stature, the surface of which Ilaller esti- mates to be fifteen square feet, sustains a pressure of 32,400 pounds. Yet, as the elasticity of the air witliin the body exactly balances or counteracts the pressure from without, he is not sensible of it. The experiments of Davy, Dalton, Gay Lussac, Humboldt, Despretz, and others, have shown, that pure atmospheric air is composed essen- tially of two gases, oxygen and nitrogen or azote^ which exist in it in the proportion of 21 of the former to 79 of the latter: according to MM. Dumas and Boussingault,^ 20-81 of the former to 79-19 of the lat- ter: Dr. T. Thomson says 20 of oxygen to 80 of nitrogen; and these proportions have generally been found to prevail in the air whence- soever taken; — whether from the summit of Mont Blanc, the top of Chimborazo, the sandy plains of Egypt, or from an altitude of 28,000 feet in the air."* It has been affirmed, indeed, that the proportion of ' Element. Physiol., viii. 2, § 3, Lausann., 1764. 2 De rinflueiice des Agens Physiques, cScc, p. 493, Paris, 1824. 3 Annales de Chimie et de Pliysique, iii. 257, Paris, 1841. ■» Art. Atmosphere, (Physical and Chemical History,) by Dr. R. M. Patterson, iu Amer. Cyclopedia of Practical Medicine and Surgery, vol. ii. p. 526, Philad., 1836. 282 RESPIEATIOX. the gases is subject to a variation of two or three parts in the thou- sand, in situations where the oxj'gen is much exposed to absorption, as over the sea, when there is no wind.^ Chemical analysis has not been able to detect the presence of any emanation from the soil of the most insalubrious regions, or from the bodies of those labouring under the most contasrious diseases, — malio;nant and 'material as such emana- tions unquestionably must be. Tlie great uniformity in the propor- tion of the oxygen to the nitrogen in the atmosphere has led to the conclusion, that as there are man}^ processes, which consume the oxygen, there must be some natural agency, by which a quantity of oxygen is produced equal to that consumed. The only source, however, by which oxygen is known to be supplied, is the process of vegetation. A healthy plant absorbs carbonic acid during the day; appropriates the carbon to its own necessities, and gives off the oxygen with which it was com- bined. This is a nutritive or digestive process; but at the same time the plant is respiring, or consuming oxygen, and giving off carbonic acid. In bright light, however, the former function is so active as to preponderate over, and mask the latter. During the night an opposite effect is produced. Digestion is almost suspended; and respiration is preponderant. Oxygen is then taken from the air, and carbonic acid given off; but the experiments of Davy and Priestley show, that plants, during the twenty-four hours, yield more oxj^gen than they consume. It seems impossible, however, to look to this as the great cause of equi- librium between the oxygen and the nitrogen. Its influence can ex- tend to a small distance only ; yet the uniformity has been found to prevail, as we have seen, in the most elevated regions, and in coun- tries whose arid sands never admit of vegetation. In addition to the oxygen and nitrogen, — the principal constituents of atmospheric air, — another gas exists in very small proportion, but is always present. This is carbonic acid. It was found by De Saus- sure on Mont Blanc, and by Von Humboldt in air brought down by Garnerin, the aeronaut, from the height of several thousand feet. The proportion is estimated by Dalton not to exceed the y-f^'p^th or y^^fj^th of its bulk. In one of the wards of La Pitie, in Paris, which had been kept shut during the night, M. Felix Leblanc^ found a larger portion of carbonic acid, nearly y (fg^^hs; and in a dormitory of La Salpetri^re, the air yielded yo^^o^^^; t^® largest proportion found by him in hospitals. In the lecture room of the Sorbonne, which is capabable of containing 1000 cubic inches of air, after a lecture an hour and a half long, and at which 900 persons were present, the oxygen was found to have lost 1 in every hundred, although two doors were open ; whilst the carbonic acid was increased in rather a greater ratio. In a ward in an institution for children, although the door was half open, and there was an open space in the roof, the air ■was found to contain y^^goths of carbonic acid, and there was a pro- portional diminution of oxj^gen. Dr. Dalton analyzed the air of a room in which 50 candles had been kept burning, and 500 people had ' Lewy, Comptes Eendiis, 1842; also, Morren, Annales de Cliimie et de Physique, xii. 5, Paris, 1844. 2 Gazette Med. de Paris, 11 Juin, 1842. ATMOSPHERIC AIR. 283 been collected for two hours, and found it to contain one per cent, of carbonic acid.^ M. Boussingault^ has made 142 analyses of large quantities of the air of Paris, whence he has drawn the generally ad- mitted conclusion, that the quantity of carbonic acid contained in the air of large towns is not above the average. The average quantity found by him was 3*97 volumes in 10,000. Although largely pro- duced where combustion is extensively going on, and where numbers of persons are congregated together, as in large cities, it becomes so speedily diffused in the atmosphere as not to excite any marked dif- ference between the air in them and in rural districts.^ These, then, may be looked upon as the constituents of atmospheric air. There are certain substances, however, which are adventitiously present in variable proportions; and which, with the constitution of the atmosphere as to density and temperature, are the causes of gene- ral or local salubrity, or the contrary. Water is one of these. The quantity, according to M. de Saussure, in a cubic foot of air, charged with moisture, at 65° Fahr., is 11 grains. Its amount in the atmo- sphere is very variable, owing to the continual change of temperature to which the air is subject, and even when the temperature is the same, the quantity of vapour is found to vary, as the air is rarely in a state of saturation. The varying condition as to moisture is indicated by the hyrjrometer. From a comparison of numerous observations, Gay Lussac affirms, that the mean hygrometric state of the atmosphere is such, that the air holds just one-half the moisture necessary for its saturation. In his celebrated aerial voyage, he found it contain but one-eighth. This is, perhaps, the greatest degree of dryness ever noticed. It has been presumed, that the hygrometric condition of the air has more agency in the production of disease than either the barometric or thermometric. It is not easy to say, which exerts the greatest influ- ence : probably all are concerned ; and when we have a union of par- ticular barometric, thermometric, hygrometric, electric, and other conditions, we have certain epidemics existing, which do not prevail under any other combination. When the air is dry, we feel a degree of elasticity and buoyancy ; whilst, if it be saturated with moisture — especially during the heat of summer, — languor, lassitude, and indis- position to mental or corporeal exertion are experienced. In addition to aqueous vapour, numerous emanations from animal and vegetable substances are generally present, especially in the lower strata of the atmosphere ; by which the salubrity of the air may be more or less affected. All living bodies, when crowded together, de- teriorate the air so much as to render it unfit for the maintenance of the healthy functions. If animals be kept crowded together in ill- ven- tilated apartments, they speedily sicken. The horse becomes attacked with glanders; fowls with pep, and sheep with a disease peculiar to them if the}'" be too closely folded. This is probably a principal cause of the insalubrity of cities compared with the country. In them, the ' London and Edinb, Philos. Magazine, xii. 405, 1838. * Annales de Chimie et de Physique, Mars, 1844. See, also, M. Lewy, loc. cit, ^ See Dr. John Reid, article Respiration, in Cyclopaedia of Anat. and Physiol., Pt. xxxii, p. 326, London, April, 1848. 284: RESPIRATION. air must necessarily be deteriorated by the impracticability of proper ventilation ; and this, with the want of due exercise, is a fruitful cause of cachexia — and of tuberculous cachexia; hence, also, it is, that in workhouses and manufactories, diseases dependent on this condition of constitution are prevalent. One of the greatest evidences we pos- sess of the positive insalubrity of towns is in the case of the young. In London, the proportion of those that die annually under five years of age to the whole number of deaths is as much as thirty-eight per cent., and under two years, twenty-eight per cent. ; in Paris, under two years of age, twenty-five per cent. ; and in Philadelphia and Baltimore, .rather less than a third. These estimates may be considered approxi- mations; the proportions varying somewhat, according to the precise year in which they have been taken. Manifest, however, as is the existence of some deleterious principle, in these cases, it has always escaped the researches of the chemist. Lastly. Air is indispensable to organic existence. No being — animal or vegetable — can continue to live without a due supply of it; nor can any other gas be substituted for it. This is proved by the fact, that all organized bodies cease to exist, if placed in vacuo. They require, likewise, renovation of the air, otherwise they die ; and if the residual air be examined, it is found diminished in quantity, and to have received a gas, which is totally unfit for life, — carbonic acid. The experiments of Hales prove this as regards vegetables ; whilst Spallan- zani and Vauquelin have confirmed it in the case of the lower animals. The necessity for the presence of air, and its due renewal, — as regards man and the upper classes of animals, — is sufficiently obvious. Not less necessary is a due supply of it to aquatic animals. They can be readily drowned, when the air in the water is consumed, if prevented from coming to the surface. If the fluid be put under the receiver of an air-pump, and the air be withdrawn, or if the vessel be placed so that the air cannot be renewed, the same changes are found to have been produced in it. Hence the necessity for making holes through the ice, where small fish-ponds are frozen over, if we are desirous of preserving the fish alive. The necessity for the renewal of air is not, however, alike imperative in all animals. Whilst the mammalia, birds, fishes, &c., speedily expire, when placed under the receiver of an air-pump, if the receiver be exhausted ; the frog is but slightly incommoded. It swells up almost to bursting, but retains its positiou, and when the air is re-admitted seems to have sustained no injury. The exception, afforded by the amphibious animal to the ordinary effects of destructive agents, we have already had occasion to refer to more than once; and it is exemplified in the fact, now indisputable, that the toad has been found alive in the substance of trees and rocks, where no access of air appeared practicable. The influence of air on mankind is interesting and important in its hygienic relations, and has accordingly been a tojiic of study since the days of Hippocrates. In other works, it has been investigated, at considerable length, by the author.^ ' Human Health, Philad., 1844; and American Cyclopaedia of Practical Medicine and Surgery, art. Atmosphere, p. 527, Philad., 183tJ. MECHANICAL PHENOMENA — RESPIRATION. 285 3. PHYSIOLOGY OF RESPIRATION. a. Mechanical Phenomena of Respiration. — Within certain limits, the function of respiration is under the influence of volition. The mus- cles, belonging to it, have consequently been termed mixed, as we can at pleasure increase or diminish their action, but cannot arrest it alto- gether, or for any great length of time. If, by a forced inspiration, we take air into the chest in large quantity, we find it impossible to keep the chest in this condition beyond a certain period. Expiration irresistibly succeeds, and the chest resumes its pristine situation. The same occurs if we expel the air as much as possible from the lungs. The expiratory effort cannot be prolonged indefinitely, and the chest expands in spite of the effort of the will. The most expert divers do not appear capable of suspending the respiratory movements longer than 95 or 100 seconds, or, at the farthest, two minutes. Dr. Lefevre^ found the average period of the Turkish divers to be 76 seconds for each man. Yet Dr. Hutchinson^ states, that a man can take from 230 to 300 cubic inches of fresh air into his lungs, and live upon it with- out inconvenience for two minutes without breathing. "It is better," he says, "to inspire and expire forcibly five or six times and then hold," with the view of removing as far as possible the old air from the lungs and filling the chest as completely as possible. "For the first fifteen seconds, a giddiness will be experienced ; but when this leaves us, we do not find the slightest inconvenience for want of air." These facts have given rise to two curious and deeply interesting topics of inquiry ; — the cause of the first inspiration in the new-born infant ; — and of the regular alternation of inspiration and expiration during the remainder of existence ? The first of these will fall under consideration when we investigate the physiology of infancy ; the lat- ter will claim some attention at present. Ilaller^ attempted to account for the phenomenon by the passage of the blood through the lungs being impeded during expiration, — a reflux of blood into the veins, and a degree of pressure upon the brain, being thus induced ; hence a painful sensation of suffocation in consequence of which the muscles of inspiration are called into action by the will, for the purpose of enlarging the chest, and, in this way, removing the impediment. The same*lineasy feelings, however, ensue from inspiration, if too long pro- tracted: the muscles cease to act, and, by their relaxation, the oppo- site state of the chest is induced. Whytf* conceived, that the passage of the blood through the pulmonary vessels is impeded by expiration, and a sense of anxiety is thus produced. The unpleasant sensation acts as a stimulus upon the nerves of the lungs and the parts con- nected with them, which arouses the energy of the sentient ])rinciple ; and this, by acting in a reflex manner, causes contraction of the dia- phragm, enlarges the chest, and removes the painful feeling. The muscles then cease to act, in consequence of the stimulus no longer ' Loudon's Magazine of Nat. Hist., p. 617, Dec, 1836 ; and Dunglison's Amer. Med. Intelligencer, p. 30, April 15, 1837. 2 Art. Thorax, Cyclop, of Anat. and Physiol., iv. 1066, London, 1852. 3 Elementa Physiologise, viii. 4, 17, Laiisann., 1764. ■* An Essay on the Vital and other Involuntary Motions of Animals, sect, viii., Edinb., 1751. 286 EESPIRATION. existing. These, and all other methods of accounting for the pheno- mena, are, however, too pathological. From the first moment of respiration the process appears to be accomplished without the slight- est difficulty, and to be as much a part of the instinctive extra-uterine actions of the frame, as circulation, digestion, or absorption. It is obviously an internal sensation, after respiration has been once esta- blished ; and, like all internal sensations, is inexplicable in our exist- ing state of knowledge. The part which developes the impression is probably the lung, through its ganglionic nerves ; and the pneumo- gastric nerves convey the impression to the brain or spinal marrow, which calls into action the muscles of inspiration. We say, that the action of impression arises in the lungs, and this, from some internal cause, connected with the office to be filled in the economy ; but in so saying we sufficiently exhibit our total want of acqiiaintance with its nature. The movements of inspiration and expiration, which, together, consti- tute the function of respiration, are entirely accomplished b}" the dilata- tion and contraction of the thorax. Air enters the chest when the latter is expanded; and is driven out when the chest is restored to its ordinary dimensions; — the thorax thus seeming to act like an ordinary pair of bellows with the valve stopped: when the sides are separated, the air enters at the nozzle, and when they are brought together, it is forced out. (1.) INSPIRATION. The augmentation of the capacity of the thorax, which constitutes inspiration, may be effected to a greater or less extent, according to the number of muscles that are thrown into action. The chest may, for example, be dilated by the diaphragm alone. This muscle, as we have seen, in its ordinary relaxed condition, is convex towards the chest. When, however, it contracts, it becomes more horizontal ; in this man- ner augmenting the cavity of the chest in a vertical direction. The sides or lateral portions of the diaphragm, which are fleshy and corre- spond to the lungs, descend more in this movement than the central tendinous portion, which is moreover kept immovable by its attachment to the sternum, and its union with the pericardium. In the gentlest of all breathing, the diaphragm appears to be the sole agent of inspiration; and in cases of inflammation of the pleura costalis, or of fractured rib, our endeavours are directed to the prevention of any elevation of the ribs by which the diseased part might be put upon the stretch. Gene- rally, however, as the diaphragm descends, the viscera of the abdomen are compressed; the abdominal muscles relaxed; the abdomen is ren- dered more prominent, and the ribs and the breast bone are raised so that the latter is protruded. When the diaphragm acts, and, in addition, , the ribs and sternum are raised, the cavity of the chest is still farther augmented. In young children, inspiration is effected almost wholly by the dia- phragm ; and as in diaphragmatic breathing the movement of the parietes of the abdomen is more marked than that of any other part, this has been termed the ahdominal mode or type of respiration. In adult men, the lower part of the chest and sternum move more I MECHANICAL PHENOMENA — INSPIRATION. 287 largely than in women; who, owing to greater mobility of the first rib, have a more extensive movement of the npper than of the lower part Fig. 88. Fig. 89. The Changes of the Thoracic and Abdominal Wails of The Respiratory Movements in the the Male during Respiration. Female. The back is supposed to be fixed in order to tlirow forward The lines indicate the same changes as the respiratory movement as much as possible. The outer in the last figure. The thickness of the black continuous line in front represents the ordinary continuous line over the sternum shows breathing movement : the anterior margin of it being the the larger extent of the ordinary breath- boundary of inspirfdion, the posterior margin the limit of iug movement over that region in the fe- expircdion. The line is thicker over the abdomen, since the male than in the male, ordinary respiratory movement is chiefly abdominal: thin over the chest, for there is less movement over that region. The dotted lino indicate.s the movement on deep inspiration, during which the sternum advances, while the abdomen re- cedes. of the chest, — an arrangement which, it has been suggested, ma}' have for its object the providing of sufficient space for respiration when the lower part of the chest is encroached upon by the pregnant uterus. The former is called by MM. Beau and Alaissiat the costo-inferior or inferior costal; the latter the costo-sn]jerior or siqjerior costal type of respiration.' From the admeasurements of Mr. Sibson^ it appears, that in health the inspiratory movement of the walls of the chest, during tranquil breathing, is only from two to six-hundredths of an inch ; whilst that of the abdomen is about three-tenths of an inch. During a deep in- spiration, the expansive motion of the walls of the chest is, in front, about one inch; and. at the sides about two-thirds of an inch; and that of the abdomen about one inch. The expansion of the two sides of the chest is nearly equal; the left side does not, however, expand quite so much as the right over the lower two-thirds, owing to the position of the heart. ' Arcliives Generales de Medecine, iii. 263, Paris, 1843 ; also, Kirkes and Paget. Manual of Physiology, 2d Amer. edit., p. 127, Philad., 1853. * Provincial Medical and Surgical Journal, Sept. 5, 1849. 288 RESPIRATIOiSr. J The mechanism, by which the ribs are elevated, has been productive of more controversy than the subject merits. Ilaller^ asserted, that the first rib is immovable, or at least admits of but trifling motion when compared with the others; and he denied that the thorax, as a whole, makes any movement of either elevation or depression; affirm- ing that the ribs are raised successively towards the top of the cavity; and this to a greater extent as they are more distant from the first. M. Magendie,^ on the other hand, denies that they are elevated in this manner ; and endeavours to show that they are all raised at the same time; that the first rib, instead of being the least movable, is the most so ; and that the disadvantage, which the lower ribs possess in the movement, by their admitting of less motion in their posterior articu- lations, is compensated by the greater length of those ribs. This com- pensation he considers to have its advantages; for as the true ribs, with their cartilages and the sternum, usually move together, and the motion of one of these parts almost always induces that of the rest, it would follow, that if the lower ribs were more movable, they could not exe- cute a more extensive movement than they do ; whilst the solidity of the thorax would be diminished. By the elevation, then, of the ribs, and the depression of the dia- phragm, the chest is augmented, and a deeper inspiration effected than, when the diaphragm acts singly. In this elevation of the ribs, we see the advantage of their obliquity as regards the spine. Had they been horizontal, or inclined obliquely upwards, any elevation would neces- sarily have contracted the thoracic cavity, and thus favoured expiration instead of inspiration. The muscles chiefly concerned in inspiration are the intercostals, and those that arise, either directly or indirectl}^ from the spine, head, or upper extremities, and that can, in any manner, elevate the thorax. Amongst these are the scaleni antici and postici, levatores costarum, the muscles of the neck, which are attached to the sternum, &c. The elasticity of the cartilages, and the weight of the osseous portions of the parietes of the chest, must afford considerable resistance to the action of the inspiratory muscles in dilating it. It is probable, how- ever, that the estimates of Dr. Hutchinson^ are far above the reality. He calculates, that the force which the muscles of inspiration have to overcome in ordinary breathing from these sources is probably at least equal to about 100 lbs.; and in deep inspiration to about 300 lbs.; and yet, in these calculations, the additional resistance from the elasticity of the lungs is not taken into the account. As no air exists in the cavity of the pleura, it necessarily happens, that when the capacity of the chest is augmented, the residuary air, contained in the air-cells of the lungs after expiration, is rarefied; and, in consequence, the denser air without enters the larynx by the mouth and nose, until the air within the lungs has attained the density, which the residuary air had. prior to inspiration, — not that of the external air, as has been affirmed.'* At the time of inspiration, the glottis opens by ' Elementa Physiologi3e, viii. 4, Lausann., 1764. ^ Precis, &c., 2de edit., ii. 316. 3 Medico-Chirurgical Transactions, xxix. 205, London, 1846. * Animal Physiology, Library of Useful Knowledge, p. 100, London, 1829. MECHANICAL PHENOMENA — INSPIRATION. 289 the relaxation of the arjtenoidei muscles, as M. Legallois' proved by experiments performed at the Ecole de Medecine of Paris. On exposing the glottis of a living animal, the aperture is found to dilate distinctly at each inspiration, and contract at each expiration. If, according to M. Magendie, the eighth pair of nerves be divided low down in the neck, and the dilator muscles of the glottis, which receive their nerves from the recurrents — branches of the eighth pair — be thus paralysed, the aperture is no longer enlarged during inspiration, whilst the con- strictors — the arytenoidei muscles, which receive their nerves from tlie superior laryngeal, — given off above the point of section, preserve their action, and close the glottis more or less completely. When air is inspired through the mouth, the velum is raised, so as to allow it to pass freely to the glottis; and, in forced inspiration, it is so horizontal as to completely expose the pharynx to view. The phy- sician takes advantage of this in examining morbid affections of those I)arts, and can often succeed much better in this way than by pressing down the tongue. On the other hand, when inspiration is effected en- tirely through the nose, the velum palati is depressed until it becomes vertical, and there are no obstacles to the free entrance of the air into the larynx. In such case, where difficulty of breathing exists, the small muscles of the alas nasi are frequently thrown into violent action, alternately dilating and contracting the apertures of the nostrils: hence this is a common symptom in pulmonary affections. Mayow^ conceived, that air enters the lungs in inspiration as it would a bladder put into a pair of bellows, and communicating with the ex- ternal air by the pipe of the instrument. The lungs, however, are not probably so passive as this view would indicate. In cases of pulmonary hernia, the extruded portion has been observed to dilate and contract in inspiration and expiration. Reisseisen believed this to be owing to muscular fibres, which Meckel and himself conceived to make the whole circuit of the bronchial ramifications. Laennec^ affirms, that he has endeavoured, without success, to verify the observations of Reisseisen; but that the manifest existence of circular fibres in branches of a mo- derate size, and the phenomena presented l)y many kinds of asthma, induce him to consider the temporary constriction and occlusion of the minute bronchial ramifications as a thing established. The muscular action of the lungs may be demonstrated by galvanizing them shortly after they have been taken from the body ; when they contract so as to lift up water placed in a tube introduced into the trachea;"* and it is affirmed by M. Longet^ and by Volkmann,^ that they may be made to contract by stimulating their nerves. The latter physiologist tied a glass tube, drawn fine at one end, into the trachea of a decapitated animal ; and when the small end was turned to the flame of a candle, ' (Euvres, p. 177, Paris, 1824. 2 Tractatus Quinque, p. 271, Oxon., 1674. * On the Diseases of the Chest, &c., 4th edit., Lond., 1834 ; rc'iirinted in this country, Philad., 1835. * C. J. B. Williams, Report of the Meeting of the British Association, in Athena-um for 1840, p. 802. * Traite de Physiologic, ii. 328, Paris, 1850. ® Art. Nervenphysiologie, in Wagner's Handwortcrbucli der Physiologic, lOte Liefe- rung, s. 58(j, Braunschweig, 1845. VOL. L— 19 290 EESPIRATION. he galvanized the trunk of the pneumogastric nerve. On each ap- plication, tlie flame was blown upon ; and once it was extinguished. In the trachea, an obvious muscular structure exists in the posterior third, where the cartilages are wanting. There it consists of a thin muscular plane, — the trachealis muscle, — the fibres of which pass transversely between the interrupted extremi- ties of the cartilaginous rings of the trachea and bronchi, to which a layer of longitudinal fibres may at times be seen superadded.-^ The use of the transverse muscular tissue, as suggested by Small Bronchial Tube j)p^ Physick,^ and after him by M. Cruveilhier and ai ope"' g^ Charles BelP, is to diminish the calibre of Showing the transverse . ' . . piexiform arrangement of the air-tubcs lu expectoratiou I SO that the air the muscular hiver, and its , . , ,i t ji ^ ^ j j.- disposition at the orifice of a haviug to pass through the contracted portion flftT.-Masnified''2 Sam*'' with greater velocity, its momentum may remove the secretions that are adherent to the mucous membrane. The explanation is ingenious and probably just. In the larger bronchi the muscles have the form of circular flattened fasciculi, which, except in old people, in whom interstices of diflerent sizes are observable, constitute a completely continuous layer, which are still perceptible in ramifications of from y'^th to i\t]i of a line in diameter.'* M. Magendie* asserts, that the lung has a constant tendency to return upon itself, and to occupy a smaller space than it fills ; and that it con- sequently exerts a degree of traction on every part of the parietes of the thorax. This traction has but little effect upon the ribs, which cannot yield ; but upon the diaphragm it is considerable. It is, in his opinion, the cause why that muscle is always tense, and drawn so as to be vaulted upwards ; when the muscle is depressed during contrac- tion, it is compelled to draw down the lungs towards the base of the chest, so that they are stretched, and by virtue of their elasticity have a powerful tendency to return upon themselves, and draw the dia- phragm upwards. If a puncture be made into the chest in one of the intercostal spaces, the air will enter the chest through the aperture, and the lung will shrink. By this experiment, the atmospheric pressure is equalized on both surfaces of the lung, and the organ assumes a bulk determined by its elasticity and weight. Owing to this resiliency of the lungs, and to their consequent tendency to recede from the pleura cosialis, there is less pressure upon all the parts against which the lungs are applied; and, accordingly, the heart is not exposed to the same degree of pressure as the parts external to the chest ; and the degree of pressure is still farther reduced, when the chest is fully dilated, the ' Goddard, in Wilson'^ Anatomist's Vade-Mecum, Amer. edit., p. 404, note, Philad., 1843. ^ Horner's Lessons in Practical Anat., p. 179, Pliilad., 1836. 3 Philos. Transact, for 1832, p. 301. * KiJlliker, Mikroskopische Anat., ii. 313, Leipz., 1852 ; or Amer. edit, of Sydenham Society's translation of Kolliker's Manual of Histology, by Dr. Da Costa, p. 578, Philad., 1854. * Precis, &c., ii. 325. MECHANICAL PHENOMENA — INSPIEATION. 291 lungs farther expanded, and their elastic resiliency increased. Dr. Carson^ states, that in his experiments on calves, sheep, and large dogs, the resiliency of the lungs was found to be balanced by a column of water, varying in height from a foot to a foot and a half; and in rabbits and cats by a column varying in height from six to ten inches. Many physiologists have pointed out three degrees of inspiration, but it is manifest that there may be innumerable shades between them: — 1. Ordinary gentle inspiration^ owing simply to the action of the dia- phragm ; or, in addition, to a slight elevation of the chest. 2. Deep inspiration, when, with the depression or contraction of the diaphragm, there is evident elevation of the thorax; and, lastly, /orcecZ inspiration, when the air is strongly drawn in by the rapid dilatation produced by the action of all the respiratory muscles that elevate the chest directly or indirectly. Trials have been instituted for determining the quantity of air taken into the lungs at an inspiration; and considerable diversity, as might be expected, exists in the evaluations of different experimenters.^ We have just remarked, that, in the same individual, the inspiration may be gentle, deep, or forced; and, in each case, the quantity of air in- spired will necessarily differ. There is, likewise, considerable diver- sity in individuals; so that an approximation can alone be attained. The following table sufficiently exhibits the discordance on this point. Many, however, of the estimates, which seem so discrepant, may pro- bably be referred to imperfection in the mode of conducting the expe- riment, as well as to the causes above mentioned : — Cubic inches Cubic inches at each at each Inspiration. Inspiration. Reil, 42 to 100 Jeffreys, Herbst, 26 24 to 30 Meuzies, Sauvages, Herholdt, .... 20 to 29 Hales, Jurine and Coathupe, 20 Haller, Kite, 17 Ellis, Allen and Pepys, . . 16^ Sprengel, T. Thomson, . . . 16 Sommering, 40 Hutchinson, 16 to 20 Chaptal J. Borelli, .... 15 to 40 Bell, Goodwin, .... 14 Monro, Valentin, .... 14 to 92 Blumenbacli, Sir H. Davy, . . . 13 to 17 Thomson, Lavoisier and Seguin, 13 Bostock, J Abcrnethy and Mojou, 12 Jurin, 35 to 38 35 Vierordt, .... Keutsch, 10 to 42 6 to 12 Fontana, Richerand and Cavallo, 30 to 40 Abildgaard, .... 3 Dalton, 30 In passing through the mouth, nasal fossae, pharynx, larynx, tra- chea, and bronchi, the inspired air acquires nearly the temperature of the body ; and, if it be cool, the same quantity by weight occupies a ■ Philosophical Transactions, for 1820, p. 42. ^ Dr. Marshall Hall has devised a pnenmatometer for this purpose. See art. Irrita- bility, in Cyclop, of Auat. and Physiol., July, 1840. 292 RESPIRATION. much larger space in the lungs, owing to its rarefaction in those organs. According to Valentin, the temperature of the expired air is y9°-5 Fahr., when breathing an atmosphere of moderate temperature. In its passage, too, it becomes mixed with the halitus, that is constantl}'- ex- haled from the mucous membrane of the air-passages : in this condi- tion, it enters the air-cells, and becomes mixed, by difiusion, with the residuary, air. It is obvious, that if we knew the exact capacity of the lungs in an individual in health, we might be able to determine the extent of solidi- fication in pulmonary affections by the diminution in their capacity. Owing, however, to our want of this requisite preliminary knowledge, the test is not of much avail. (2.) EXPIRATION. A brief interval elapses after the accomplishment of inspiration, before the reverse movements of expiration succeeds ; and tlie air is expelled from the chest. The great cause of this expulsion is the re- storation of the chest to its former dimensions ; and the elasticity of the yellow tissue composing the bronchial ramifications, which has been put upon the stretch by the air rushing into them during in- spiration. The restoration of the chest to its dimensions may be effected simply by the cessation of the contraction of the muscles, that have raised it, and the elasticity of the cartilages, that connect the bony portions of the ribs with the sternum or breast-bone. In active expiration, however, the ribs are depressed by the contraction of appropriate muscles, and the chest is still farther contracted. The chief expiratory muscles are the triangularis sterni, the broad muscles of the abdomen, rectus abdominis, sacro-lumbalis, longissimus dorsi, serratus posticus inferior, &c. Haller' conceived that the ribs, in ex- piration, are successively depressed towards the last rib ; which is first fixed by the abdominal muscles and quadratus lumborum. The in- tercostal muscles then act, and draw the ribs successively downwards. M. ]\[ao-endie^ contests the explanation of Haller ; and the truth would seem to be, that the muscles, just mentioned, participate with the inter- costals in every expiratory movement. 'By this action, the capacity of the chest is diminished ; the lungs are correspondently pressed upon, and the air issues by the glottis. It has been already remarked, that, during expiration, the arytenoidei muscles contract, and the glottis appears to close. Still, space sulTicient is left to permit the exit of the air. It has been asked : — Is the air expired precisely that which has been taken in by the previous inspiration ? Certainly not. It has expe- rienced much change. A portion of the oxygen has disappeared and carbonic acid has taken its place. The amount of the inspired air does not differ largely from that which is expired; and the quantity employed in an ordinary act of inspiration bears — as will be seen — but a small proportion to the residual air. There must be some mode consequently in which the residual air or that occupying the air-cells is changed, and this is probably effected mainly by the mutual diffu- ' Element. Physiol., viii. 4, Lausaun., 17G4. * Precis, &c., ii. 324. MECHANICAL PHENOMEKA — EXPIRATION. 293 sion of gases ; wliicli mix readily with each other when either of dif- ferent densities or different temperatures; and this admixture is doubt- less greatly favoured by the respiratory movement. The muscular fibres and the minute bronchial tubes may have an agency in the mat- ter, as suggested by Prof. Draper.' Were the parietes of the air-cells possessed of contractile fibres, they might be greatly concerned; but this is not admitted.^ Many experiments have been made to determine the change of bulk which air experiences by being respired. According to Sir Humphry Dav}^,^ it is diminished, by a single inspiration, from ^'^th to yioth part of its bulk. Cuvier makes it about g'^th ; Allen and Pepys a little more than one-half per cent. Berthollet from 0"69 to 3'70 per cent.; and Bostock s'oth, — as the average diminution. Assuming this last estimate to be correct, and forty cubic inches to be the quantity drawn into the lungs at each inspiration, it would follow, that half a cubic inch disap- pears each time we respire. This, in a day, would amount to 14:,-i()0 cubic inches, or to rather more than eight cubic feet. The experiments of M]\.[. Dulong and Despretz make the diminution considerable. The latter gentleman placed six small rabbits in forty-nine quarts of air for two hours, at the expiration of which time the air had diminished one quart. A portion of the inspired air must, consequently, be absorbed. In the ordinary respiration of men from seventeen to thirty-three years old, Valentin'* has calculated, from the watery vapour contained in the saturated expired air, that the average quantity of air expired in a minute is 400 cubic inches, — the extremes under varying circum- stances being 234: and GS^S cubic inches, and the average quantity of one ordinary expiration 31*1 cubic inches; the extremes in very tran- quil and somewhat hurried respiration 114 and 74 cubic inches. Mr. Paget,^ however, thinks that Mr. Coathupe's*^ estimate of 20 to 25 cubic inches is probably better, inasmuch as it was drawn from the results of respiration continued during a longer period and with less restraint than in the experiments of Valentin. It has long been an inquiry of interest, especially for the apprecia- tion of encroachments of pulmonary disease, to determine the amount of air expelled from the chest ; and different instruments have been devised for the purpose by Kentish, Phcibus, and others.'' Pulmo- metry is consequently not new ; but it had never been carefully inves- tigated before the interesting experiments made by Dr. Hutchinson^ with the instrument somewhat unhappily termed by him a spirometer, by which he measures the quantity of air expired in a full and forci- ble expiration, and which he esteems an index of the vital capacity, as it expresses the power which a person has of breathing in the exigen- ' Anier. Journ. of the Med. Sciences, April, 1852. 2 Kulliker, Mikroskopische Anatoinie, and Amer. edit, of his JLanual of Human His- tology, by Dr. Da Costa, p. 579, Philad., 1854. ' Researches, Clieinical and Philosophical, p. 431, Lond., 1800. * Lehrbuch der Physiologie des Menschen, i. 542, Braunschweig, 1844. s Kirkes and Paget, Manual of Physiology, 2d Amer. edit., p. 128, Philad., 1853. ^ Philos. Magazine, June, 1839. ' Pabius [et Buys-Ballot] De Spirometro. Diss, inang., Amsterdam, 1853. ^ Meilico-Chirurgical Transactions, xxix. p. 237, Lond., 184(); and art. Thorax, in Cycl. of Anat. and Physiol., iv. 10tJ8, Loud., 1852; also. Dr. John Ileid, Ibid., p. 339. 294 RESPIRATION. cies of active exercise, violence, and disease. From the results of 1923 observations made on males, he has inferred, that for every inch of height — from five feet to six — eight additional cubic inches of air at 60° Fahr. are given out by a forced expiration ; so that, he believes, from the height alone of an adult male, he can pronounce what quan- tity of air he should breathe when healthy. This is a singular result, as it is not easy to see what relation there can be between the height of a person, which is greatly regulated by the length of his legs ; and the quantity of air he is capable of respiring. Much must obviously de- pend upon the degree of nervous power or of muscular activity,^ but the diftcrence cannot be altogether accounted for in this way ; as cases are not uncommon in which men of great muscular powers are below the standard ; whilst others, by no means remarkable for such power, greatly exceed it.^ Di\ Hutchinson gives the following table of the quantity of air, expelled by the strongest expiration after the deepest inspiration, for every inch of height between five and six feet, as ascertained by actual observation with the spirometer, and as calculated by the rule of pro- "Tession referred to above. Height. From Observation. Eegular Progression Ft. in. Ft. in. Cub. in. Cub. in. 5 to 5 1 . . . . 174 . . . . 174 5 1 " 5 2 177 182 5 2 " 5 3 189 190 5 3 " 5 4 193 198 5 4 " 5 5 201 206 5 5 " 5 6 214 214 .5 (i " 5 7 229 222 5 7 " 5 8 228 230 5 8 " 5 9 237 238 5 9 " 5 10 246 24(5 5 10 " 5 11 247 254 5 11 " 6 259 262 Dr. Hutchinson found, that two other conditions influence the quan- tity of air that passes to and from the lungs in forced voluntary respi- ration, — weight, and age. The former does not affect the respiratory power of an individual of any height between five feet one inch and five feet eleven inches, until it has increased seven per cent, above the average weight of the body in persons of that height; but, beyond this, it diminishes in the ratio of one cubic inch per pound for the next 35 pounds, — the limit of his calculations. In males of the same height the respiratory power is increased from 15 to 35 years of age ; but from 35 to 65 years it decreases nearly 1| cubic inch for each year;''' and the results of the examinations are so nearly uniform, that it has been inferred, disease may be suspected in any man who cannot blow out nearly as many cubic inches as the average of those of the same height, even when by external measurement his chest appears to be of full size. The size of the chest is, indeed, stated to afford no good indication of the capacity of expiration. The only exceptions ' Prof. S. .Jackson, in Med, Examiner, .Jan., 1851, p. 51. 2 Dr. C. Radclytfe HaU, in Transact, of Prov. Med. and Surg. Assoc, 1851. 3 For the quantity of air inspired and expired in forced respiration, see Hales, Stati- cal Essays, i. 242, and Bostock, System of Pliysiology, p. 316, Lond., 1836. I MECHANICAL PHENOMENA — EXPIRATION. 295 among tlie "healtliy to the general rule of the direct proportion between the height of the body and the capacity of expiration, are in the cases of fat persons, whose capacity is always low. It was the observation — made by M. Bourgery' — that thin men have the greatest capacity of respiration, which first led Dr. Hutchinson to the experiments, that furnished the law given above. He found, that the full expiratory force of a healthy man is commonly about one-third greater than his inspiratory force; and he states, that whenever the expiratory are not stronger than the inspiratory muscles, some disease is present. In examining the results of all his experiments — 1500 in number — he found the power of the inspiratory muscles was greatest in men of five feet nine inches in height, — their inspiratory powers being equal, on an average, to a column of 2*75; and their expiratory power to one of 8*97 inches of mercury; whilst in four of the classes, composed gene- rally of active, efficient and healthy individuals, namely Firemen, Metropolitan Police, Thames Police, and Royal Horse Guards, the inspiratory power of the men of five feet seven inches was the greatest, being equal to 3"07 inches of mercury; and those of five feet eight inches to 2*96, or nearly three inches. The average power of the five feet seven inches and five feet eight inches men of all classes examined was only 2*65 inches of mercury. He infers, from all his experiments, that a healthy man of the height of five feet seven inches or five feet eight inches ought to elevate by inspiration a column of mercury of three inches. The experiments of Valentin' and Mendelssohn,^ as far as they go, confirm those of Dr. Hutchinson. Attempts have been made to estimate the quantity of air remaining in the lungs after respiration ; but the sources of discrepancy are here as numerous as in the cases of inspiration or expiration. Groodwyn'* estimated it at 109 cubic inches: Menzies^ at 179; Jurin^ at 220; Fon- tana^ at 40; and Cuvier, after a forced inspiration, at from 100 to 60. Davy^ concluded, that his lungs, after a forced expiration, still retained 41 cubic inches of air; and after a natural expiration 118 cubic inches; after a natural inspiration, 135; and after a forced inspiration, 254. Vierordt^ supposes that the residual air after the deepest expiration is about 8(3.600 cubic inches. By a full forced expiration after a forced inspiration, he expelled 190 cubic inches; after a natural inspiration, 78*5 ; and after a natural expiration, 67*5. Mr. Julius Jeflreys^° divides the air of respiration into four quantities — First, the residual air, or that which cannot be expelled from the lungs, but remains after a full and forcible expiration; which he estimates at 120 cubic inches — Secondly, the supplementary air, — reserve air of Dr. Hutchinson — or ' Arcliiv. Generales de Medecine, Mars, 1843. ^ Lelirbiich der Physiologie des Menscheii, i. 524, Braunschweig, 1844. ' Der Mechanismus der Respiration und Circulation, Berlin, 1845 ; cited by Dr. John Reid, op. cit., p. 336. * Op. citat., p. 36. ^ Op. cit., p. 31. ^ Philosoph. Trans., vol. xxx. p. 758. '' Philosoph. Trans, for 1799, p. 355. * Op. citat., p. 411. ^ Art. Respiration, in Wagner's Handworterbuch der Physiologie, \\. s. w. 12te Lie- ferung, Braunschweig, 1845. '" Views upon the Statics of the Human Chest, &c., London, 1843. 296 RESPIRATION. that wliicli can be expelled by a forcible expiration, after an ordinary outbreatbing, valued at 130 cubic inches — Thirdly^ the breath, or tidal air, — hreathiug air of Dr. Hutchinson — valued at 26 cubic inches; and Fourthhj, the complementary or complemental air, or that which can be inhaled after an ordinary inspiration, which amounts to 100 cubic inches. This estimate gives 250 cubic inches as the average volume which the chest contains after an ordinary expiration. It is impossible, from such variable data as the above, to deduce any thing like a satisfactory conclusion; but if we assume with Dr. Bostock, and Dr. Thomson' is disposed to adopt the estimate, 170 cubic inches as the quantity that may be forcibly expelled, and that 120 cubic inches will be left in the lungs, we shall have 290 cubic inches as the measure of the lungs in their natural or quiescent state ; to this quantity 40 cubic inches are added by each ordinary inspiration, giving 330 cubic inches as the measure of the lungs in their distended state. Hence it would seem, that about one-eighth of the whole contents of the lungs is changed by each respiration ; and that rather more than two-thirds can be ex- pelled by a forcible expiration. Supposing that each act of respiration occupies three seconds, or that we respire twenty times in a minute, a quantity of air, rather more than 2| times the whole contents of the lungs, will be ex]:)elled in a minute, or about four thousand times their bulk in twenty-four hours. The quantity of air respired during this period will be 1,152,000 cubic inches, about 'o'o'dh cubic feet. Such is Dr. Bostock's estimate. It is the residuary air, that gives to the lungs the property of float- ing on the surface of water, after they have once received the breath of life; and no pressure can force out the air, so as to make them sink. Hence, the chief proofs, whether a child has been born alive or dead, are deduced from the lungs. These constitute docimasia jJulmonum, Lungenprobe or Athemprobe ("Lung-proof or Eespiration-proof") of the Germans. Expiration, like inspiration, has been divided into three grades; ordi- 7iary, free, and forced; but it must necessarily admit of multitudinous shades of dift'ereuce. In ordinary passive respiration, expiration is effected solely by the relaxation of the diaphragm. In free active respiration, the muscles that raise the ribs are likewise relaxed, and there is a slight action of the direct expiratory muscles. In forced expiration, all the respiratory muscles are thrown into action. In this manner, the air makes its way along the air-passages through the mouth or nostrils, or both ; carr3dug with it a fresh portion of the halitus from the mucous membrane. This it deposits when the atmo- sphere is colder than the temperature acquired by the respired air, and if the atmosphere be sufficiently cold, as in winter, the vapour becomes condensed as it passes out, and renders expiration visible. Dr. Hutchinson'-^ measured the costal movement during ordinary respiration in healthy males, and found it not to exceed from two to four-tenths of a line. He states, that the difference between the cir- ' System of Chemistry, vol. iv. 2 iieclico-Chiiurgical Transactions, xxix. 187, Loud., 1846; and art. Thorax, in Cy- clop, of Anat. and Physiol., iv. 1080, Loud., 1852. MECHANICAL PHENOMENA — EXPIEATION. 297 cumference of an ordinary man's cbest measni'ecl over the nipples in the two states of a deep inspiration and a deep expiration amounts to three inches; and Valentin/ under the same circumstances, found the average difference in the circumference of the chest, measured over the scrobiculus cordis, in seven individuals of the male sex between IT^- and 80 years of age, to be as 1 : 8'29 of the whole circumference. In the majority of cases, perhaps, the times occupied by the murmurs of inspiration and of expiration will be nearly in the ratio of three to one. Thus, if a healthy person breathes fifteen times in a minute, or once in four seconds, the time occupied by the periods of inspiration, expiration, and repose will be nearly one and a half, a half, and two seconds, respectively. Differences will exist in healthy individuals; but the above may perhaps be esteemed the expression of the general truth. It is important to bear these facts in mind, inasmuch as, in dis- ease, the expiratory murmur is apt to become prolonged, first of all at the expense of the period of repose, and afterwards of that of inspira- tion;^ — a circumstance to which attention was first forcibly directed by Dr. James Jackson, Jun., of Boston. Budge^ does not admit, that the length of inspiration is as great when compared with that of expira- tion as is given above; and he considers the pause or period of repose to be more apparent than real. The number of respirations in a given time differs considerably in different individuals. Dr. Hales,'' Dr. Dalton,^ Mr. Coathupe,® and Dr. Bostock^ reckon them at twenty. Laennec from twelve to fifteen. A man, on whom Menzies made experiments, breathed only fourteen times in a minute. Sir Humphry Davy^ made between twenty-six and twenty- seven in a minute. Dr. Thomson,^ and Allen and Pepys, about nine- teen; and Magendie,^° fifteen. In 171-i adults of the male sex considered to be in a state of health. Dr. Hutchinson'' found, that the majority, in the sitting posture, breathed betAveen 16 and 24 in the minute; and of these a great number 20 per minute. Yierordt'^ found the number in his own person to be, on an average, ll-j'^gths when sitting and the mind disengaged ; whilst the maximum was 15, and the minimum 9. Our own average is about sixteen; and this is the average, in the adult, assumed by Giinther'^ and Berthold.'"' That, deduced from the few ob- servers, who have recorded their observations, — twenty per minute, — ' Lfthrbucli der Pliysiologie des Menschen, i. 541, Braunschweig, 1844. * Lectures on the Physical Diagnosis of the Diseases of the Lungs and Heart, by Herbert Davies, M.D., p. 69, London, 1851. ' Memoranda der speciellen Physiologic des Menschen, 5te Auflasre, S. 60, Weimar, 1853. " Statical Essays, 3d edit., i. 243. ^ Memoirs of the Literary and Philosophical Society of Manchester, 2d series, ii. 26, Manchester, 1813. ** Lond. and Edinb. Philos. Magaz., xiv. 401, 1839. ' System of Physiology, p. 321, Lond., 1836. ^ Researches chiefly concerning Nitrous Oxide, p. 434, Lond., 1800. ® System of Chemistry, iv. 604. Glasgow, 1820. '" Precis de Physiologie, 2de edit., Paris, 1825. " Op. cit., p. 226. '^ Wagner's Handworterbuch der Physiologie, art. Respiration, ii. 834, Braunschweig, 1845. '^ Lehrbuch der Physiologie des Menschen, 2ter Band, Iste Abtheil., S. 217, Leipzig, 1848. » Lehrbuch der Physiologie, 3te Aullago, 2tcr Theil, S. 227, Gutting., 1848. 298 KESPIRATIO^S". has geDerally been taken; but we are satisfied it is above the truth ; eighteen would be nearer the general average, and it has accordingly been admitted by many. Eighteen in a minute give twenty-five thou- sand nine hundred and twenty in the twenty-four hours. The number is influenced, however, by various circumstances. The child and the female, and perhaps also the aged, breathe more rapidly than the adult male. A£M. Hourmann and Dechambre' examined two hundred and fifty-five women between the ages of sixty and ninety-six, the average number of whose respirations was 21'79 per minute. According to ISi. Quetelet,^ a child breathes in the minute, on the average, — 44 times. 26 » 20 " lS-7 " 16-0 " 18.1 " At birth At 5 years ....... From 15 to 20 years ..... " 20 to 25 " " 25 to 30 " " 30 to 50 " AYe find as much variety in the respiration of men as we do in tliat of horses: whilst some are short, others are long-winded; and this last condition may be improved by appropriate training, to which the pe- destrian and the prize-fighter, equally with the horse, are subjected for some time before they are called upon to test their powers. In sleep, the respiration is generally deeper, less frequent, and appears to be per- formed greatly by the intercostals and diaphragm.^ Motion has also a sensible efiect in hurrj'ing the respiration, as well as distension of the stomach by food, certain mental emotions, &c. : it is less in the hori- zontal than in the sitting posture; and less in the sitting than in the erect. Its condition during disease becomes a subject of interesting study to the physician, and one that has been much facilitated by the acoustic method introduced by Laennec. To his instrument — the stetho- scope — allusion has already been made. By it, or by the ear applied to the chest, we are able to hear distinctly the respiratory murmur and its modifications; and thus to judge of the nature of pulmonary affections. But this is a topic that appertains more especially to pathology. (3.) EESPIKATOKY PHEXOMENA COXCERXED IX CEKTAIX FUXCTIOXS. There are certain respiratory movements, concerned in effecting other functions, that require consideration. Some of these have already been discussed. M. Adelon" has classed them into: First. Those employed in the sense of smell, either for the purpose of conveying the odorous molecules into the nasal fossse ; or to repel them and prevent their in- gress. Secondly. The inspiratory actions employed in the digestive func- tion, as in snclcijig. Thirdhj. Those connected with muscular motion when forcibly exerted ; and particularly with straining or the employ- ment of violent effort. Fourthly. Those concerned in the various ex- cretions, either voluntary, — as in defecation and spitting ; or involuntary, — as in coughing, sneezing, vomiting, accouchement, &c. ; and lastly, those that constitute phenomena of expression, — as sighing, yawning, laughing, ■ Arcliiv. Gener. de Metiecine, Nor. 1835. 2 A Treatise on Man, Chambers's Edinb. translation, p. 71, Edinb., 1842; and Vier- ordt, art. Respiration, iu Wagner's HandwiJrterbuch der Physiologie, ii. 834, Braun- schweig, 1844. * Adelou, Physiologie de rHomme, iii. 185. ■• Op. cit., p. 188. MECHANICAL PHENOMENA — SNEEZING. 299 crying^ soiling, kc. Some of these, that have already engaged attention, do not demand comment; others are topics of considerable interest, and require investigation. 1. Straining. — The state of respiration is much affected during the more active voluntary movements. Muscular exertion of whatever kind, when considerable, is preceded by a long and deep inspiration ; the glottis is closed; the diaphragm and respiratory muscles of the chest are contracted, as well as the abdominal muscles which press upon the contents of the abdomen in all directions. AVhilst the proper respira- tory muscles are exerted, tliose of the face participate, owing to their association through the medium of particular nerves. By this series of actions, the chest is rendered capacious; and the force that can be de- veloped is augmented, in consequence of the trunk being rendered immovable as regards its individual parts, — thus serving as a fixed point for the muscles that arise from it, so that they are enabled to employ their full effort.^ The physiological state of muscular action, as con- nected with the mechanical function of respiration, is happily described by Shakspeare, when he makes the fifth Harry encourage his soldiers at the siege of Harfleur, " Stiflfen 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 its full height." King Henry V. iii. 1. In the effort required for effecting the various excretions, a similar action of the respiratory muscles takes place. The organs, from wliich these excretions have to be removed, are either in the thorax or abdo- men ; and in all cases have to be compressed by the parietes of those cavities. A full inspiration is first made ; the expiratory muscles, with those that close the glottis, are then forcibly and simultaneously con- tracted, and by this means the thoracic and abdominal viscera are compressed. Some difference, however, exists, according as the viscus to be emptied is seated in the al^domen or thorax. In the evacuation of the faeces, the lungs are first filled with air ; and whilst the muscles of the larynx contract to close the glottis, those of the abdomen con- tract also; and as the lung, in consequence of the included air, resists the ascent of the diaphragm, the compression bears upon the large in- testine. The same happens in the excretion of the urine, and in ac- couchement. 2. Coughing and Sneezing. — AVhen the organs that have to be cleared are the air-passages, — as in coughing to remove mucus from them, — the same action of the muscles of the abdomen is invoked; but the glottis is open to allow the exit of the mucus. In this case, the expi- ratory muscles contract convulsively and forcibly, so that the air is driven violently from the lungs ; and, in its passage, sweeps off' the irritating matter, and conveys it out of the body. To aid this, the muscular fibres, at the posterior part of the trachea and larger bron- chial tubes, contract, so as to diminish the calibre of these canals ; and in this way expectoration is facilitated. The action differs, however, according as the expired air is sent through the nose or mouth; in the ' Op. cit., p. 190; and art. Effort, in Diet, de Med., 2de edit., xi. 197, Paris, 1835. 300 RESPIRATION. former case, constituting sneezing; in the latter, coughing. The former is more violent than the latter, and is involuntary; whilst the latter is not necessarily so. In both cases the movement is excited by some external irritant, applied directly to the mucous membrane of the wind- pipe or nose; or by some modified action in the very tissue of the part, which acts as an irritating cause. In both cases the air is driven forci- bly forwards ; and both are accompanied by sounds that cannot be mistaken. In these actions, we have striking exemplifications of the extensive association of muscles, through the medium of nerves, to which we have so often alluded. The pathologist, too, has repeated opportunities for observing the extensive sympathy between distant parts of the frame, as indicated by the actions of sneezing and cough- ing, especially of the former. If a person be exposed for a short period to the partial and irregular application of cold, so that the organic ac- tions of a part of the body are modified, as where we get the feet wet, or sit in a draught of air, a few minutes is frequently sufficient to ex- hibit sympathetic irritation in the Schneiderian membrane of the nose, and sneezing. Nor is it necessary, that the organic actions of a distant part shall be modified by the application of cold. We have had the most positive evidence, that if they be irregularly accomplished, even by the application of heat, whilst the rest of the body is receiving none, inflammation of the mucous membrane of the nasal fossas and fauces may supervene with no less certain tj^. 3. Blowing the Xose. — The substance that has to be excreted by this operation is composed of the nasal mucus, the tears sent down the ductus ad nasum, and the particles deposited on the membrane by the air in its passage through the nasal fossas. Commoidy, these secretions are only present in quantity sufficient to keep the membrane moist, the remainder being evaporated or absorbed. Frequentl}^, however, they exist in such quantity as to fall by their own gravity into the pharynx, where they are sent down into the stomach by deglutition, are thrown out at the mouth, or make their exit at the anterior nares. To prevent this last effect more especially, we have recourse to blowing the nose. This is accomplished by taking in air, and driving it out suddenly and forcibly, closing the mouth at the same time, so that the air may issue by the nasal fossee and clear them; the nose being compressed so as to make the velocity of the air greater, as well as to express all the mucus that may be forced forwards. •i. Si'itting differs somewhat according to the part in which the mucus or matter to be ejected is seated. At times, it is exclusively in the mouth ; at others, in the back part of the nose, pharjmx, or larjmx. When the mucus or saliva of the mouth has to be excreted, the muscu- lar parietes of the cavity, as well as the tongue, contract so as to eject it from the mouth ; the lips being at times approximated, so as to ren- der the passage narrow, and impel the sputa more strongly forward. The air of expiration may be, at the same time, driven forcibly through the mouth, so as to send the matter to a considerable distance. The prac- tised spitter sometimes astonishes us with the accuracy and power of propulsion of which he is capable. When the matter to be evacuated is in the nose, pharynx, or larynx, it requires to be brought, first of all, into the mouth. If in the posterior nares, the mouth is closed, and the MECHANICAL PHENOMENA — YAWNING. 801 air is drawn in forcibly throngli the nose, the pharynx being at the same time constricted so as to prevent the substances from passing down into the oesophagus. The pharynx now contracts from below to above, in an inverse direction to that required in deglutition ; and the farther excretion from the mouth is effected in the manner just described. Where the matters are situate in the air-passages, the action may consist in coughing ; or, if higher up, simply in hawking. A forcible expiration, unaccompanied by cough, is, indeed, in many cases, suffi- cient to detach the superfluous mucous secretion from even the bronchial tubes. In hawking, the expired air is sent forcibly forwards, and the parts about the fauces are suddenly contracted so as to diminish the capacity of the tube, and propel the matter onwards. The noise is produced by their discordant vibrations. Both these modes bear the general name of expectoration. AVhen these secretions are swallowed, they are subjected to the digestive process ; a part is taken up, and the remainder rejected ; so that they belong to the division of recremento-eaxrementitial fluids of some physiologists. (4.) RESPIKATORY PHENOMENA CONNECTED WITH EXPKESSION. It remains to speak of the expiratory phenomena that strictly form part of the function of expression, and depict the moral feeling of the individual who gives them utterance. 1. Sighing consists of a deep inspiration, by which a large quantity of air is received slowly and gradually into the lungs, to compensate for the deficiency in the due aeration of the blood which precedes it. The most common cause of sighing is mental uneasiness: it also occurs during languor, at the approach of sleep, or immediately after waking. In all these cases, the respiratory efforts are executed more imperfectly than under ordinary circumstances; the blood, consequently, does not circulate through the lungs in due quantity, but accumulates more or less in these organs, and in the right side of the heart ; and it is to restore the due balance, that a deep inspiration is now and then established. 2. Yaicning^ oscitancy^ oscitation or gaping^ is a full, deep, and protracted inspiration, accompanied by a wide separation of the jaws, and followed by a prolonged and sometimes sonorous expiration. It is excited by many of the same causes as sighing. It is not, however, the expression of a depressing passion, but is occasioned by any cir- cumstance that impedes the necessary aeration of the blood ; whether it be retardation of the action of the respiratory muscles, or the air being less rich in oxygen. Hence we yawn at the approach of sleep, and immediately after waking. The inspiratory muscles, fatigued from any cause, experience some difficulty in dilating the chest; the lungs are, consequently, not properl}^ traversed by the blood from the right side of the heart ; oxygenation is, therefore, not dul}'- effected, and an uneasy sensation is induced ; this is put an end to by the action of yawning, which allows the admission of a considerable quantity of air. We yawn at the approach of sleep, because the agents of respiration, becoming gradually more debilitated, require to be now and then ex- 302 EESPIRATION. cited to fresli activity, and the blood needs the requisite aeration. Yawning on waking seems to be partly for the purpose of arousing the respiratory muscles to greater activity, the respiration being always slower and deeper during sleep. It is, of course, impossible to explain why the respiratory nerves should be chiefly concerned in these respi- ratory movements of an expressive character. The fact, however, is certain ; and it is remarkably proved by the circumstance, that yawn- ing can be excited by even looking at another affected in this manner; nay, by simply looking at a sketch, and even thinking of the action. The same also applies to sighing and laughing, and especially to the latter. 3. Pandiculation or stretching is a frequent concomitant of yawning, and appears to be established instinctively to arouse the extensor mus- cles to a balance of power, when the action of the flexors has been predominant. In sleep, the flexor muscles exercise that preponderance which, in the waking state, is exerted by the extensors. This, in time, is productive of some uneasiness ; and hence, occasionally during sleep, but still more at the moment of waking, the extensor muscles are roused to action to restore the equipoise : or, perhaps, as the mus- cles of the upper extremities, and those engaged directly or indirectly in respiration, are chiefly concerned in the action, it is exerted for the purpose of exciting the respiratory muscles to increased activity. ByDr. Good,^ yawning and stretching have been regarded as morbid affections and amongst the signs of debility and lassitude : — " Every one," he remarks, " who resigns himself ingloriously to a life of lassi- tude and indolence, will be sure to catch these motions as a part of that general idleness which he covets ; and, in this manner, a natural and useful action is converted into a morbid habit ; and there are loungers to be found in the world, who, though in the prime of life, spend their days as well as their nights in a perpetual routine of these convulsive movements, over which they have no power ; who cannot rise from the sofa without stretching their limbs, nor open their mouths to answer a plain question without gaping in one's face. The disease is here idiopathic and chronic ; it may perhaps be cured by a perma- nent exertion of the will, and ridicule or hard labour will generally be found the best remedies for calling the will into action." 4. Laughing is a convulsive action of the muscles of respiration and voice, accompanied by a facial expression, which has been explained elsewhere. It consists of a succession of short, sonorous expirations. Air is first inspired so as to fill the lungs. To this succeed short, interrupted expirations, with simultaneous contractions of the muscles of the glottis, so that the aperture is slightly contracted, and the lips assume the tension necessary for the production of sound. The inter- rupted character of the expirations is caused by convulsive contrac- tions of the diaphragm, which constitute the greater part of the action. In very violent laughter, the respiratory muscles are thrown into such forcible contractions, that the hands are applied to the sides to support them. The convulsive action of the thorax likewise interferes with the circulation through the lungs; the blood, consequently, stagnates ' Study of Medicine, class 4, ord. 3, gen. 2, sp. 6. WEEPING — SOBBING. 803 in the upper part of the body ; the face becomes flushed ; the sweat trickles down the forehead, and the eyes are sufiused with tears ; but this is apparently owing in part to mechanical causes ; not to the lachrymal gland being excited to unusual action, as in weeping. At times, however, we find the latter cause in operation, also. 5. Wee2yi7ig. The action of weeping is very similar to that of laugh- ing; although the causes are so dissimilar. It consists in an inspira- tion, followed by a succession of short, sonorous expirations. The facial expression, so diametrically opposite to that of laughter, has been depicted in another place. Laughter and weeping appear to be characteristic of humanity. Animals shed tears, but the act does not seem to be accompanied by the mental emotion that characterizes crying in the sense in which we employ the term. It has, indeed, been affirmed by Steller,^ that the ])hoca ursina or ursine seal; by Pallas,^ that the camel; and by Yon Humboldt,^ that a small American monkey, shed tears when labour- ing under distressing emotions. The last scientific traveller states, that "the countenance of the titi of the Orinoco, — simia sciurea of Linnasus, — is that of a child ; the same expression of innocence ; the same smile; the same rapidity in the transition from joy to sorrow. The Indians affirm, that it weeps like man, when it experiences cha- grin; and the remark is accurate. The large eyes of the ape are suf- fused with tears, when it experiences fear or any acute suffering." Shakspeare's description of the weeping of the stag, — " Tkat from the hunter's aim had ta'en a hurt," is doubtless familiar to most of our readers. " The wretched animal heaved forth such groans, That their discliarge did stretch his leathern coat Almost to bursting ; and the big, round tears Coursed one another down his innocent nose* In piteous chase ; and thus the hairy fool, Much marked of the melancholy Jaques, Stood on th' extremest verge of the swift brook, Augmenting it witli tears." As You Like It, 11. 1. We have less evidence in favour of the laughter of animals. Le Cat,^ indeed, asserts, that he saw the chimpanzee both laugh and weep. The orang, carried to Great Britain from Batavia by Dr. Clarke Abel, never laughed ; but he was seen occasionally to weep.^ 6. /Sobbing still more resembles laughing, except that, like weeping, it is usually indicative of the depressing passions ; and generally ac- ' Nov. Comm. Academ. Scient. Petropol., ii. 353. * Sammlungen Historisch. Nachricht. iiber die Mongolischen Volkerschaften, Th. i. 177. ^ Recueil d'Observations de Zoologie, &c., i. 333. * " The alleged ' big round tears,' which ' course one another down the innocent nose' of the deer, the hare, and other animals, when hotly pursued, are in fact only sebaceous matter, which, under these circumstances, flows in profusion from a collec- tion of follicles in the hollow of the cheek." — Fletcher's Rudiments of Physiology, part ii. b. p. 50, Edinb., 183G. ^ Traite de I'Existence du Fluide des Nerfs, p. 35. ^ Lawrence, Lectures on Physiology, Zoology, and the Natural History of Man, p. 236, Lond,, 1814. 304 KESPIEATIOlSr. companies weeping. It consists of a convnlsive action of the dia- phragm; wliich is alternately raised and depressed, but to a greater extent than in laughing, and with less rapidity. It is susceptible of various degrees, and has the same physical effects upon the circulation as weeping. Dr. Wardrop^ considers laughter, crying, weeping, sob- bing, sighing, &c., as efforts made with a view to effect certain altera- tions in the quantity of blood in the lungs and heart, when the circu- lation has been disturbed by mental emotions. 7. Panting or anhelation consists in a succession of alternate, quick, and short inspirations and expirations. Its physiology, however, does not differ from that of ordinary respiration. The object is, to produce a frequent renewal of air in the lungs, in cases where the circulation is unusually rapid ; or where, owing to disease of the thoracic viscera, a more than ordinary supply of fresh air is demanded. We can, hence, undei'stand why dyspnoea should be one of the concomitants of most of the severe diseases of the chest; and why it should occur whenever the air we breathe does not contain a sufficient quantity of oxygen. The panting, produced by running, is owing to the necessity for keeping the chest as immovable as possible, that the whole effort may be exerted on the muscles of locomotion ; and thus suspending, for a time, the respiration, or admitting onl}^ of its imperfect accom- plishment. This induces an accumulation of blood in the lungs and right side of the heart ; and panting is the consequence of the aug- mented action necessary for transmitting it through the vessels. b. Chemical Phenomena of Pespiration. Having studied the mode in which air is received into, and expelled from, the lungs, we have now to inquire into the changes produced on the venous blood — containing the products of the various absorptions ■ — in the lungs; as well as on the air itself. These changes are effected by the function o^ sanguification, hcematosis, respiration in the restricted sense in which it is employed by some, arterialization, decarbonization, aeration, atmospherization, &c., of the blood. With the ancients this process was but little understood. It was generally believed to be the means of cooling the body; and, in modern times, Ilelvetius revived the notion, attributing to it the office of refrigerating the blood, — heated by its passage through the long and narrow channels of the circulation, — by the cool air constantly received into the lungs. The reasons, which led to this opinion, were: — that the air, which enters the lungs in a cool state, issues warm; and that the pulmonary veins, which convey the blood from the lungs, are of less dimension than the pulmonary arterj^, which conveys it to them. Froih this it was con- cluded, that the blood, during its progress through the lungs, must lose somewhat of its volume, or be condensed by refrigeration. The warmth of the expired air can, however, be readily accounted for; and it is not true that the pulmonar}'- veins are smaller than the pul- monary artery. The reverse is the fact ; and it is obvious, that the doctrine of Ilelvetius does not explain how we can exist in a tempera- ' On the Nature and Treatment of Diseases of the Heart, part i. p. 62, Lond., 1837. H^MATOSIS. 805 lure superior to our own; wliicli, in his liypothesis, ought to be im- practicable.' Another theory, which prevailed for some time, was; — that during inspiration the vessels of the lungs are deployed or unfolded, as it were, and that thus the passage of the blood from the right side of the heart to the left, through the lungs, is facilitated. Its progress was, indeed, conceived to be impossible during expiration, in consequence of the considerable flexures of the pulmonary vessels. The discovery of the circulation of the blood gave rise to this theory; and Haller^ attaches importance to it, when taken in connexion with the chauges effected upon the blood in the vessels. It is incorrect, however, to suppose, that the circulation of the blood througli the lungs is mecha- nically interrupted, when respiration is arrested. The experiments of Drs. Williams^ and Kay** would seem to show, that the interruption is mainly ascribable to the non-conversion of venous into arterial blood, and to the non-adaptation of the radicles of the pulmonary veins for any thing but arterial blood, owing to which causes stagnation of blood supervenes in the pulmonary radicles. Numerous other objections might be made to this view. In the first place, it supposes, that the lungs are emptied at each expiration; and, again, if a simple deploying or unfolding of the vessels were all that is required, any gas ought to be sufficient for respiration, — which is not the fact. In these different theories, the principal object of respiration is over- looked- — the conversion of the venous blood, conveyed to the lungs by the pulmonary artery, into arterial blood. This is effected by the contact of the inspired air with the venous blood ; in which they both lose certain elements, and gain others. Most physiologists have con- sidered that the whole function of h^matosis is effected in the luno;s. M. Chaussier,* however, has presumed, that some kind of elaboration is effected on the air, in passing through the cavities of the nose and mouth, and the different bronchial ramifications, by being agitated with the bronchial mucus ; similar to what he conceives is effected by the mucus on the aliment in its passage from the mouth to the sto- mach; but his view is conjectural in both one case and the other, M. Legallois,^ again, thought, that hasmatosis commences at the part, where the chyle and lymph are mixed with the venous blood, or in the subclavian vein. This admixture, he conceives, occurs more or less immediately ; is aided in the heart, and the conversion is com- pleted in the lungs. To this belief he was led by the circumstance, that when the blood quits the lungs it is manifestly arterial; and he thought, that what the products of absorption lose or gain in the lungs is too inconsiderable to account for the important and extensive change; and that therefore it must have commenced previously. Facts, however, are not exactly in accordance with the view of Legal- lois. They seem to show, that the blood of the pulmonary artery is ' Adelon, Physiologie de I'llomme, edit, cit., iii. 201. ^ Element. Physiol., lib. viii. sect, iv., Lausanu., 17(56. ^ Edinburgh Medical and Surgical Journal, vol. Ixxvii., 1823. * Edinburgh Med. and Surg. Journal, vol. xxix. ; and Physiology and Pathology, &c., of Asphyxia, Lond., 1834. ^ Adelon, Physiologie de rHomme, iii. 205. ® Annales de Chimie, iv. 115. VOL. I. — 20 306 RESPIRATION. analogous to tliat of the subclavian vein; and hence it is probable, that there is no other action exerted upon the fluid in this part of the venous system, than a more intimate admixture of the venous blood with the chyle and lymph in their passage through the heart. The changes, wrought on the air by respiration, are considerable. It is immediately deprived of a portion of both of its main consti- tuents — oxygen and nitrogen ; and it always contains, when expired, a quantity of carbonic acid greater than it had when received into the lungs, along with an aqueous and albuminous exhalation to a consi- derable amount. Oxygen is consumed in the respiration of all animals, from the largest quadruped to the most insignificant insect; and if we examine the expired air, the deficiency is manifest. Many attempts have been made to estimate the precise quantity consumed during respiration; but the results vary essentially from each other; partly owing to the fact, that the amount consumed by the same animal differs in different circumstances. Menzies' was probably the first that attempted to ascertain the quantity consumed by man in a day. According to him, 86 cubic inches are expended in a minute; consequently, 61,840 in the twenty-four hours, equal to 17,496 grains. Lavoisier^ makes it 46,048 cubic inches, or 15,541 grains. This was the result of his ear- lier experiments, and, in his last, which he was executing at the time when he fell a victim to the tyranny of Robespierre, he made it 15592*5 grains ; corresponding greatly with the results of his earlier observa- tions. The experiments of Sir Humphry Davy^ coincide greatly with those of Lavoisier. He found the quantity consumed in a mi- nute to be 31*6 cubic inches; making 45,504 cubic inches, or 15,337 grains in twenty-four hours. The results obtained by Messrs. Allen and Pepys^ make it much less. They consider the average consump- tion to be, in the twenty-four hours, under ordinary circumstances, 39,534 cubic inches, equal to 13,343 grains. If we regard the experiments of Lavoisier and Davy, between which there is the greatest coincidence, to be an approximation to the truth, it will follow, that, in a day, a man consumes rather more than 25 cubic feet of oxygen ; and as the oxygen amounts to only about one-fifth of the respired air, he must render 125 cubic feet of air unfit for support- ing combustion and respiration. The experiments of Crawford, Jurine, Lavoisier and Seguin, Prout, Fyfe, and Edwards,^ have proved, that the quantity of oxygen con- sumed varies according to the condition of the functions and the system generally. Seguin^ found, that muscular exertion increases it nearly fourfold. Dr. Prout,^ who gave much attention to the subject, was induced to conclude, from his experiments, that moderate exercise increases it; but if the exercise be continued so as to induce fatigue, a ' Dissertation on Respiration, p. 21, Edin., 170G. * Memoir, de I'Academ. des Sciences, 1789, 1790. ' Researclies, &c., p. 431. « Philos. Transact, for 1808. ^ De riufluence des Agens Phvsiques 3ur la Vie, p. 410, Paris, 1824 ; or Hodglcin and Fisher's translation. ^ Mem. de PAcadem. des Sciences, 1789 and 1790. ' Annals of Philos., ii. 330, iv. 331, and xiii 2(39. H^MATOSIS. 307 diminished consumption takes place. The exhilarating passions ap- peared to increase the quantity; whilst the depressing passions and sleep, the use of alcohol and tea, diminished it. He discovered, that the quantity of oxygen consumed is not uniformly the same during the twenty-four hours. Its maximum occurred between 10 a. m. and 2 P. M., or generally between 11 A.M. and 1 P.M.: its minimum commenced about 8| P. M., and it continued nearly uniform till about 3 J A.M. Dr. Fyfe' found, that the quantity was diminished by a course of nitric acid, by a vegetable diet, and by affecting the system with mercury. Temperature has an influence. Dr. Crawford^ found, that a Guinea-pig, confined in air at the temperature of 55°, consumed double the quantity which it did in air at 104°. He also observed, in such cases, that venous blood, when the body was exposed to a high temperature, had not its usual dark colour ; but^ by its florid hue, indicated that the full change had not taken place in its constitution in the course of circulation. The same fact is mentioned by a recent observer, who affirms, that if, when an animal is near dying from the effect of heat, an artery be opened, its blood is as black as that of a vein, and does not become bright by exposure. We may thus understand the great lassitude and yawning, induced by the hot weather of summer; and the languor and listlessness which are so characteristic of those who have long resided in torrid climes. Dr. Prout conceives, that the presence or absence of the sun alone regu- lates the variation in the consumption of oxygen which he has described ; but the deduction of Dr. Fleming^ appears to be more legitimate, — that it keeps pace with the degree of muscular action, and is dependent upon it. Consequently, a state of increased consumption is always fol- lowed b}'' an equally great decrease, in the same manner as activity is followed by fatigue. The disagreement of experimenters, as respects the removal of nitro- gen or azote from the air, during respiration, is still greater than in the case of oxygen. Priestley, Davy, Von Humboldt, Henderson, Cuvier, and Pfaff, found a less quantity exhaled than was inspired. Spallanzani, Lavoisier and Seguin, Vauquelin, Allen and Pep3^s, Ellis, Thomson, Valentin and Brunner, and Dalton, inferred that neither absorption nor exhalation takes place, — the quantity of that gas, in their opinion, undergoing no change during its passage through the air-cells of the lungs; whilst Jurine, Nysten, Berthollet, and Dulong and Despretz, on the contrary, found an increase in the bullv of the nitrogen. In this uncertainty, most physiologists have been of opinion that the nitrogen is entirely passive in the function. The facts, ascertained by M. W. F. Edwards,* of Paris, shed considerable light on the causes of this dis- crepancy amongst observers. He has satisfactorily shown that, in the respiration of the same animal, the quantity of nitrogen may be, at one time, augmented; at another, diminished; and, at a third, wholl}' un- changed. These phenomena he has traced to the influence of the sea- sons, and he suspects that other causes have a share in their produc- tion. In nearly all the lower animals that were the subjects of expe- ' Annals of Philos., iv. 334, and Bostock'b Physiol., i. 350. 2 Op_ ^it,, p. 387, 5 Philosophy of Zoology, i. 355, Edinburgh, 1S22. « Op. cit., p. 402, 308 RESPIRATION. riment, an augmentation of nitrogen was observable during summer. Sometimes, it was so slight that it might be disregarded ; but, in numerous instances, it was so great as to place the fact beyond the possibility of doubt ; and, on some occasions, it almost equalled the whole bulk of the animal. Such were the results of his observations until the close of October, when he noticed a sensible diminution in the nitrogen of the inspired air, and the same continued throughout the whole of winter and beginning of spring. M. Edwards considers it probable, that, in all cases, both exhalation and absorption of nitrogen are going on; that they are frequently accurately balanced, so as to exhibit neither excess nor deficiency of nitrogen in the expired air; whilst, in other cases, depending, as it would appear, chiefly upon tem- perature, either the absorption or the exhalation is in excess, producing a corresponding effect upon the composition of the air of expiration. MM. Regnault and Reiset,' in their experiments on animals, always observed an exhalation of nitrogen ; the proportion of which varied — as in the case of carbonic acid formed — with the nature of the food. Whilst the respired air has lost its oxygenous portion, it has received, as we have remarked, an accession of carbonic acid, and, likewise, a quantity of watery vapour. If we breathe through a tube, one end of which is inserted into a vessel of lime-water, the fluid soon becomes milky, owing to the formation of carbonate of lime, which is insoluble in water. Carbonic acid must, consequently, have been given off" from the lungs. In the case of this gas, again, it has been attempted to com- pute the quantity formed in the day. Jurine conceived, that the amount, in air once respired in natural respiration, is in the large proportion of -j'^th or y'.^th ; Menzies, that it is o'(jth ; and, from his estimate of the total quantity of air respired in the twenty-four hours, he deduced the amount of carbonic acid formed to be 61840 cubic inches, equal to 24i05"6 grains. MM. Lavoisier and St'guin,*in their first experiments, valued it at 17720"89 grains; but in the next year they reduced their estimate more than one-lialf; — to 8450.20 grains; and, in Lavoisier's last experiment, it was farther reduced to 7550*4 grains. Sir Hum- phry Davy's estimate nearly corresponds with that of the first experi- ment of MM. Lavoisier and Seguin, — i7811"3() grains; and Messrs. Allen and Fepys accord pretty nearly with him. Thcvsc gentlemen found, that air, when inspired, issued, on the succeeding expiration, charged with from 8 to 6 per cent, of carbonic acid ; but this estimate greatly exceeds that of Dr. Apjohn,^ of Dublin, who, in his experiments, found the expired air to contain only 3"6 per cent. The experiments and observations of Messrs. Crawford, Prout, Edwards, and others, to which we have referred — as regards the consumption of oxygen, under various circumstances — apply equally to the quantity of carbonic acid formed, which always bears a pretty close proportion to the oxygen consumed. These experiments also account, in some degree, for the discrepancy in the statements of individuals on this subject. The observations of Vierordt,'' at various temperatures between 38° ' Comptes Rendus, Paris, 1848. 2 Memoir, de I'Academ. des Sciences, p. 609, Paris, 1790. 3 Edinb. Med. and Surg. Journal, Jan., 1831. * Lelirbuch der Physiologisclien Chemie, iii. 386', Leipzig, 1852 ; or Amer. edit, of Dr. Day's translation, by Dr. Robert E. Rogers, ii. 443, Pliilad., 1855. H^MATOSIS. 809 and 75° Fahr., showed, that a rise equal to 10° caused a diminution of about two cubic inches in the quantity of carbonic acid exhaled per minute. Letellier/ too, found, by experiments on animals at much higher and lower temperatures than those, that the higher the tempera- ture, as far as 10-i°, the less was the amount of carbonic acid exhaled, whilst the nearer it approached zero the greater was the amount of car- bonic acid given of. The experiments of Mr. Coathupe,^ which were carefully conducted, make the amount of carbonic acid, generated in the 24 hours, about 17856 cubic inches, that is 2'616 grains or 5| ounces of solid carbon. Liebig found the proportion of carbon expired by himself to be 8^ ounces daily; by a soldier, 13| ounces; by prisoners in close confine- ment, 7 ounces; and by a boy who took considerable exercise, 9 ounces.^ Subsequently, farther experiments Avere made on the subject by com- petent observers. Professor Scharling,* of Copenhagen, found, that, at the age of 85, he exhaled 7"7 ounces avoirdupois of carbon in the twenty-four hours — seven of which were passed in sleep. A soldier, 28 years of age, exhaled 8"15 ounces; a lad of 16, 7*9 ounces; a young woman, aged 19, 5*88 ounces; a boy, 9| years old, 8'069 ounces; and a girl, 10 years old, 4*42 ounces. In the last two, the time ^spent in sleep was 9 hours. These amounts, however, were exhaled both from the luno-s and cutaneous surface. He constructed an air-tight chamber, of dimensions sufficient to permit him to remain in it for some time without inconvenience. This was connected with an apparatus by which the air was constantly renewed, and the air removed was care- fully analyzed, in order to determine the quantity of carbonic acid contained in it. Of the 7'7 ounces exhaled by himself in the twenty- four hours, we may perhaps estimate the amount from the lungs at 5'5 ounces. He infers, from all his experiments, that males exhale more carbonic acid than females; and children comparatively more than adults. . MM. Andral and Gavarret undertook a series of interesting experi- ments on the subject. Their fii-st object was to ascertain the modifying influence of age, sex, and constitution on the quantity of carbonic acid exhaled from the lungs. To determine this, their observations were made under circumstances as uniform as possible; and each experi- ment was repeated several times on the same subject. The apparatus employed was so devised as to enable the respirations to be freely per- formed; no portion of the expired air was again inspired; and the greatest care was taken to analyze the expired air with accuracy. The general results obtained by tliese observers were as follows: — 1. The quantity of carbonic acid exhaled by the lungs in a given time varies according to age, sex, and constitution. 2. In both male and female, the quantity undergoes modification, according to the agds of the indi- viduals experimented upon, quite independently of their weights. 3. In all periods of life, there is a difierence between the male and female ' Annales de Cliimie et de Physique, 1845. ^ Philosophical Magazine, Juno, 1839. ^ Graham's Elements of Chemistry, Amer. edit., p. G8G, Philad., 1843. " Annalt'S des Sciences Naturelles, Fevrier, 1843 ; cited in Brit, and For. Med. Rev. for July, 1843, p. 285. 310 RESPIRATION. in the amount of carbonic acid exhaled in a given time: cceteris paribus, man exhales a much larger quantity than woman. Between the ages of 16 and 40, the former exhales nearly twice as much as the latter. 4. In man, the quantity exhaled goes on regularly increasing from 8 to 30 years of age ; and a remarkable augmentation takes place at puberty. After 80, it begins to decrease ; and the decrease continues becoming more and more marked as the individual approaches nearer and nearer extreme old age ; so that, at this last period, it returns to the standard at which it was about the age of ten. 5. In woman the exhalation augments up to the period of puberty, according to the same law as in man; the increase then suddenly ceases, and the quan- tity continues at this low standard, with little variation so long as the catamenia appear regularly; but as soon as they cease, the exhalation of carbonic acid from the lungs undergoes a considerable augmenta- tion, after which it decreases as in man, according to the advance of age. 6. During pregnancy, the amount of carbonic acid exhaled is raised temporarily to the standard which it attains after the cessation of the catamenia. 7. In both sexes, and at all ages, the quantity of carbonic acid exhaled by the lungs is greater in proportion to the strength of the constitution, and the developement of the muscular system. The following table exhibits the amount of solid carbon calculated to be exhaled in one hour at dift'erent ages ; — the gramme is equal to about 15| grains. Male. Female. 8 years. 5 grammes. 8 years. 5 grammes. The same standard con- 15 8-7 1*2-38 . . . 6-4 tinues in women during the 16 . 10-8 38-50 . . . 8-4 whole of the menstrual pe- 18-20 11-4 50-60 . . . 7-3 riod: but if the catamenia 20-30 12-2 60-80 . . . 6-8 be temporarily suppressed, 30^0 12-2 82 . . . 6-0 or pregnancy occur, it rises 40-60 • 10-1 to the standard it attains 60-80 9-2 after their entire cessation, 102 5-9 namely, 8-4 grammes. These numbers express the averages, — the maximum amount being often considerably greater. In a young man of athletic system, and sound constitution, the quantity of carbonic acid exhaled in an hour was li"! grammes; in a man of 60, equally vigorous for his age, 13*6 grammes; and in one of 63, 124 grammes. An old man, of 92, of a remarkable degree of energy, and who had possessed unusual vigour in his youth, was found to exhale 8"8 grammes per hour; whilst the same amount appeared to be the ordinary standard in a man of 45; who, unlike the last, had a feeble system, although in equally good health. How far these variations were connected with differences in the capacity of the chest, and with the number of the respiratory movements, MM, Andral and Gavarret proposed to investigate subse- quently. This they have not done. The following table, by Dr, John Reid,' of the quantity of carbonic ' Art, Respiration, Cyclopfedia of Anat, and Physiol., Pt, xxxii, p, 345, Lond,, Aug. 1848. HiEMATOSIS. 311 acid gas in 100 parts of the expired air estimated by volume gives tlie result obtained bj recent experimenters. Difference between Average. Maximum. Minimum. Maximum and Minimum. Prout 3-45 4-10 3-30 .80 Coathupe . 4-02 7-98 1-91 6-07 Brunner and Valentin 4-380 5-495 3-299 2-196 Vierordt 4-334 6-220 3-358 2-86 Thomson . 4-ltJ 7-16 1-71 5-45 It has been a question amongst physiologists, whether the quantity of carbonic acid given out is equal in bulk to the oxygen taken in. In Dr. Priestley's experiments/ the latter had the preponderance. Menzies and Crawford found them to be equal, MM. Lavoisier and Seguin supposed the oxygen, consumed in the twenty-four hours, to be 15661"66 grains; whilst the oxygen, required for the formation of the carbonic acid given out, was no more than 1292-i grains; and Sir Humphry Davy found the oxygen consumed in the same time to be 15337 grains, whilst the carbonic acid produced was 17811"36 grains; which would contain 1282-±"18 grains of oxygen. The experiments of Messrs. Allen and Pepys seem, however, to show that the oxygen which disappears is replaced by an equal volume of carbonic acid; and hence it was supposed that the whole of it must have been em- ployed in the formation of this acid. They, consequently, accord with Menzies and Crawford; and the view is embraced by Dalton, Prout, Ellis, Henry, and other distinguished individuals. On the other hand, the view of those, who consider that the quantity of carbonic acid produced is less than that of the oxygen which has disappeared, is embraced by Dr. Thomson, and by MM. Dulong and Despretz. In the carnivorous animal, tliey found the difference as much as one- third ; in the herbivorous, on the average, only one-tenth. The expe- riments of M. Edwards have shown, that here, also, the discordance has not depended so much upon the different methods and skill of the operators, as upon a variation in the results arising from other causes; and he concludes, that the proportion of oxygen consumed to that employed in the production of carbonic acid varies from more than one-third of the volume of carbonic acid to almost nothing; that the variation depends upon the particular animal species subjected to ex- periment, its age, or some peculiarity of constitution, and that it differs considerably in the same individual at different times. According to the law of diffusion of gases, the carbonic acid given off" from the blood will, of itself, independently of the movements of respiration, have a tendency to quit the lungs by diffusing itself in the external air in which it is in less proportion ; and the oxygen of the bronchial tubes and external air will have a tendency to pass to- wards the air-cells in which its proportion is less than in the air of the tubes and the external air. Were this not the case, the air in the air- cells would be highly charged with carbonic acid, and could not fail ' Experiments, &c., on Different Kinds of Air, vol. iii., 3d edit., Lond., 1781. 312 RESPIRATION". to act injuriously, inasmucli as the respiratory movements, even when aided by the resiliency of the pulmonary tissue, can never empty the air-cells; and hence there is always — as has been shown — a quantity of reserve and residual air in the cells/ Interesting experiments by Valentin^ and Brunner, made on a large scale, seemed to demonstrate, that the chemical changes in respiration are a good deal owing to the simple diffusion of gases taking place between those of the atmosphere and of the blood. The volumes of oxygen absorbed and of carbonic acid exhaled from the blood may be, according to them, determined by the established laws of the diffusion of gases, so that, for one volume of carbonic acid exhaled, 1"17421 volume of oxygen is absorbed, — these numbers representing the pro- portionate diffusion-volumes of the two gases, calculated according to the law that they are inversely as the square roots of their specific gravities, — or, according to weight, one part of carbonic acid to 0'85163 of oxygen. One part by weight of carbonic acid contains 0'72727 of oxygen; consequently for each part of carbonic acid discharged in respiration, there is an excess of 0*12436 of oxygen, which is disposed of otherwise than in forming the carbonic acid thrown off' from the lungs, — or, by volumes, for each one of carbonic acid there is an excess of 0'17421 of oxygen. Hence if it be known how much carbonic acid has been exhaled from the lungs in a given time, we can calculate the amount of oxygen absorbed in the same time. Valentin and Brunner satisfied themselves, that in a medium temperature and atmospheric pressure, each of them, on an average of six experiments, breathed 562'929 litres of air in the hour, and, in the same time, expired 635'8565 grains of carbonic acid, containing 173'414: grains of carbon. From this and their respective diffusion-volumes, the hourly consump- tion of oxygen was calculated at 541"5 grains; — the results obtained by these gentlemen according greatly with those of MM. Andral and Gavarret. A series of apparently carefully conducted experiments in regard to the changes produced in tlie air by respiration was performed by MM. Regnault and Keiset.^ The following are the results of one on a young dog, which was confined in an appropriate apparatus for twenty- four hours and a half. Oxygen consumed, ....... 182*288 grammes. Carbonic acid produced, ...... 185'961 " Oxygen contained in the carbonic acid, . . . 135 "244 " Nitrogen given off, 0-1820 " Eepresenting the quantity of oxygen consumed at 100, the results would be as follows : — ■ en consumed, ....... 100 Oxygen in the carbonic acid, ..... 74'191 Oxygen otherwise disposed of, .... 25*809 Nitrogen disengaged, ...... 0*0549 Average quantity of oxygen consumed in an hour, . 7*44 ' Kirkes and Paget, Manual of Physiology, 2d Amer. edit., p. 131, Philad. 1853. 2 LeiirhuLli der Physiologic des Menschen, i. 547. ' Comptes Reudus, Paris, 1848. HuEMATOSIS. 813 These experiments are not confirmatory, however, of the views of Valentin and Brunner, in regard to the exchanged oxygen and car- bonic acid in respiration, being in the proportion to each other as their diffusion-volumes. Fresh observations are, indeed, needed on this subject. In the meantime it has been well remarked by Messrs. Kirkes and Paget,^ that the conditions of the gases, engaged in respi- ration, are not those in which the law of diffusion would exactly hold. The law requires, that both gases should be free and under equal pressure ; whilst in the actual case, the gas in the blood is dissolved under pressure, and separated by a membrane from that with which it has to be diffused. In their experiments on animals, MM. Eegnault and Reiset found that the nature of the diet influences the relative amount of oxygen absorbed, and of carbonic acid given out. "When animals were fed on flesh, they absorbed much more oxygen in proportion. In the case of a dog, confined exclusively to this kind of aliment, the proportion of oxygen absorbed to 100 parts of carbonic acid exhaled was lo-l:"8, much more than that which the law of diffusion of gases would indi- cate; whilst in that of a rabbit, fed wholly on vegetable food, the pro- portion was as 100 to 109-31:, or less. The difference between the relative proportions of surplus oxygen in the same animal, under these different circumstances, was as high as 62 to 104. The same experi- menters found that, when an animal was kept fasting, the relation be- tween the quantity of oxygen absorbed, and of carbonic acid exhaled, is nearly the same as when it is fed on flesh ; — " the reason evidently being," observes a recent writer,^ " that in the former case the animal's respiration is kept up at the expense of the constituents of its own body, which correspond with animal food in their composition." It must be borne in mind, however, that in such circumstances the fat would probably be most largely taken up ; and it corresponds in com- position with vegetable food. It would appear, then, that the whole of the oxygen, which respira- tion abstracts from the air, is by no means accounted for by the quan- tity of carbonic acid formed ; and that, consequently, a portion of it disappears altogether. It has been supposed by some, that a part of the watery vapour, given off' during expiration is occasioned by the union of a portion of the oxygen of the air with hydrogen from the blood in the lungs ; but the view is conjectural. This subject, with the quantity of vapour combined with the expired air, will be a matter of inquiry under the head of Secretion.^ The air likewise loses, during inspiration, certain foreign matters diffused in it. In this way, it has been attempted to convey medicines into the system. If air, charged with odorous particles, — as with those of turpentine, — be breathed for a short time, their presence in the urine can be detected ; and it is probably in this manner, that miasmata ' Op. cit., p. 137. ' Carpenter's Principles of Physiology, 4tli Amer. edit., p. 304, Pliilad., 1855. ^ See on the whole of this subject, Br. John Reid, art. Respiration, Cyclop, of Anat. and Physiol., pt. xxxii. p. 34(j, Lond., Aug., 1848 ; and Vierordt, art. Respiration, Wagner's Handworterbucli der Physiologie, 12te Lieferung, s. 828, Braunschweig, 1845. 314 RESPIRATION. produce tlieir effects on the frnme, AnjEstbetic agents act in the same way ; and all pass immediately through the coats of the pulmo- nary veins by imbibition, and thus, speedily affect the system. The changes, produced in the air during respiration, are easily shown, by placing an animal under a bell-glass, until it dies. On examining the air, it will be found to have lost a portion of its oxygen and nitrogen, and to contain carbonic acid and aqueous vapour. The expired air has alwa3's, even in greatly varying temperatures of the atmosphere, a temperature of from 97°"25 to 99°*5 Fahr., — most commonly the latter. It may now be inquired, whether the changes produced in the respired air are connected with those effected on the blood in the lungs. In its progress through the lungs, this fluid has been changed from venous into arterial. It has become of a florid red colour ; of a strons^er odour; of a higher temperature by from one to four degrees, accord- ing to some,^ but others have perceived no difference, whilst others, again, have found it of lower temperature;^ — Prof. Bernard has, indeed, established this unanswerably.'^ It is of less specific gravity, in the ratio of 1053 to 1050 on the average, according to Dr. John Davy ;* and it coagulates more speedily, according to most observers; but Mr. Thackrah' observed the contrarv. That this conversion is owins^ to the contact of air in the lungs we have many proofs. Lower® was one of the first, who clearly pointed out, that the change of colour occurs in the capillaries of the lungs. Prior to his time, the most confused notions had prevailed on the subject, and the most visionary hypo- theses been indulged. On opening the thorax of a living animal, he observed the precise point of the circulation at which the change of colour takes place ; and showed, that it is not in the heart, since the blood, when it leaves the right ventricle, continues to be purple. He then kept the lungs artificially distended, first with a regular supply of fresh air, and afterwards with the same portion of air without re- newing it. In the former case, the blood experienced the usual change of colour. In the latter, it was returned to the left side of the heart unaltered. Experiments, more or less resembling those of Lower, have been performed by Goodwyn,^ Cigna, Bichat,* Wilson Philip, and numerous others, — and with similar results. The direct experiments of Dr. Priestley^ more clearly showed, that * Magendie, Precis de Physiologie, ii. 343 ; Dr. J. Davy, in Philos. Transact, for 1814; Metcalfe on Caloric, ii. 548, Loud., 1843 ; and Becquerel and Brescliet, Annales des Sciences Naturelles, 2de serie, vii. 94, Paris, 1837. * Wagner's Elements of Physiology, by R. Willis, § 180, Lond., 1842 ; and Simon's Animal Chemistry, vol. i. p. 193, Lond., 184.5. 3 Notes of M. Bernard's Lectures on the Blood: by Walter F. Atlee, M. D., p. 140, Philad., 1854; and Gavarret, De la Chaleur Produite par les Etres Vivants, p. 110, Paris, 1855. * Physiological and Anatomical Researches, American Med. Library edit., p. 16, PhiladI, 1840. * Inquiry into the Nature and Properties of the Blood, p. 42, Lond., 1819. ^ Tractatus de Corde, &c., c. iii., Amstelod., 1761. ^ The Connection of Life with Resi^iration, &c., Lond., 1788. 8 Recherches Physiol, sur la Vie et la Mort, Semeedit., p. 238, Paris, 1805. * Experiments, &c., on Dillerent Kinds of Air, &c., Loud., 1781. H^MATOSIS. 815 the change effected on the blood was to be ascribed to the air. He found, that a clot of venous blood, confined in a small quantity of air, assumed a scarlet colour, and that the air experienced the same change as from respiration. He afterwards examined the effects produced on the blood bj the gaseous elements of the atmosphere separately, as well as by the other gaseous fluids that had been discovered in his time. The clot was reddened more rapidly by oxygen than by the air of the atmosphere, whilst it was reduced to a dark purple by nitrogen, hydrogen, and carbonic acid. Since Dr. Priestley's time, the effect of different gases on the colour of venous blood has been investigated by numerous observers. The following is the result of their observations, as given by M. Thenard.^ It must be remarked, however, that all the experiments were made on blood out of the body ; and it by no means follows, that precisely the same changes would be accomplished if it were circulating in the vessels. Gas. Colour. Remarks. Oxygen .... Rose red. The blood employed had Atmospheric air . . Do. been beaten, and, conse- Ammonia Cherry red. quently, deprived of its Gaseous oxide of carbon • Slightly violet red. fibrin. Deutoxide of azote . Do. Carburetted hydrogen Do. Azote .... Brown red. Carbonic acid . Do. Hydrogen Do.2 Protoxide of azote . Do. Arseniuretted hydrogen . Sulphuretted hydrogen . ("Deep violet, passing ■| gradually to a green- ly ish brown. Chlorohydric acid gas Maroon brown. Sulphurous acid gas Black brown. These three gases coa- f Blackish brown, pass- - gulated the blood at the Chlorine .... < ing by degress to a same time. t yellowish white. It is sufficiently manifest, then, from the disappearance of a part of the oxygen from the inspired air, and from the effects of that gas on venous blood out of the body, that it plays an essential part in the function of sanguification. But Ave have seen, that the expired air contains an unusual proportion of carbonic acid. Hence carbon, either in its simple state or united with oxygen, must have been given off from the blood in the vessels of the lungs. To account for these changes on chemical principles has been a great object with chemical physiologists at all times. At an early period, the conversion of venous into arterial blood was supposed to be a kind of combustion ; and, according to the Stahlian notion of combustion then prevalent, it was presumed to consist in the disengagement of phlogiston ; in other words, the abstraction or addition of a portion of phlogiston made the blood, it was conceived, arterial or venous ; and ' Traite de Chimie, &c., 5e edit., Paris, 1827. ^ Miiller says he agitated blood with hydrogen, but could perceive no change of colour. Handbuch, u. s. w., Baly's translation, p. 322, Lond., 1838. 316 EESPIRATION. its removal was looked upon as the principal use of respiration. This hypothesis was modified by M. Lavoisier, who proposed one of the chemical views to be now mentioned. Two chief chemical theories have been framed to explain the mode in which carbon is given off. The first is that of Black/ Priestley,* Lavoisier,^ Crawford ;•* and others ;* — that the oxygen of the inspired air attracts carbon from venous blood, and the carbonic acid is gene- rated by their union. The second, which has been supported by La Grange,* Ilassenfratz,^ Edwards,® Miiller,^ Bischoft", Magnus, and others, — that the carbonic acid is generated in the course of the circulation, and is given off" from the venous blood in the lungs, whilst oxygen gas is absorbed. The former of these views is still maintained by many chemical physiologists. It is conceived, that the oxygen, derived from the air unites with certain parts of the venous blood, — the carbon and hj^drogen, — owing to which union, carbonic acid and water are found in the expired air ; the venous blood, thus depurated of its car- bon and hydrogen, becomes arterialized ; and, in consequence of these various combinations, heat enough is disengaged to keep the body always at the due temperature. According to this theory, respiration is assimilated to combustion. The resemblance, indeed, between the two processes is striking. The presence of air is absolutely necessary for respiration ; in every variety the air is robbed of a portion of its oxygen ; hence a fresh supply is continually needed ; and respiration is always arrested before the whole of the oxygen of the air is ex- hausted; and this partly on account of the residuary nitrogen and car- bonic acid gas given oft" during expiration. Lastly, it can be continued much longer when an animal is confined in pure ox3^gen than in atmo- spheric air. All these circumstances likewise occur in combustion. Every kind requires the presence of air. A part of the oxygen is consumed ; and, unless the air is renewed, combustion is impossible. It is arrested, too, before the whole of the oxygen is consumed, owing to the residuary nitrogen, and carbonic acid formed ; and it can be longer maintained in pure oxygen than in atmospheric air. Moreover, when air has been respired, it becomes unfit for combustion. Again, the oxygen of the air, in which combustion is taking place, combines with the carbon and hydrogen of the burning body; hence the forma- tion of carbonic acid and water ; and, as in this combination, the oxy- gen passes from the state of a rare gas, or one containing a consider- able quantity of caloric between its molecules, to that of a much denser, and even of a liquid, the whole of the caloric, which the oxygen con- tained in its former state, can no longer be held in the latter, and is accordingly disengaged ; hence the increased temperature. In like manner, in respiration, the oxygen of the inspired air, it is conceived, combines with the carbon and hydrogen of the venous blood, giving ' Lectures on the Elements of Chemistry, by Robison, ii. 87, Edinb., 1803. 2 Philosoph. Transact, for 1776, p. 147. ^ Mem. de I'Acad. des Sciences, pour 1777, p. 185. * On Animal Heat, 2d edit., Lond., 17SS. ^ Metcalfe, op. cit. 6 Annales de Chimie, ix. 2(39. ' Ibid., ix. 2(J5. 8 De rinfluence des Agens Physiques, &c., p. 411, Paris, 1823 ; or Hodgkin and Fisher's translation. " Physiology, by Baly, p. 537. HiEMATOSTS. 317 rise to the formation of carbonic acid and water ; and, as in these com- binations, the oxygen passes from the state of a rare to that of a denser gas, or of a liquid, there is a considerable disengagement of caloric, which becomes the source of the high temperature maintained by the human body, M. Thenard' admits a modification of this view, — san- guification being owing, he conceives, to the combustion of the carbon- aceous parts of the venous blood, and probably of its colouring matter, by the oxj^gen of the air. This chemical theory, which originated chiefly with Lavoisier, and La Place and Scguin, was adopted by many physiologists with but little modification. Mr. Ellis, indeed, imagined, that the carbon is separated from the venous blood by a secretory process ; 'and that then, coming into direct contact with oxygen, it is converted into carbonic acid. The circumstance that led him to this opinion was his disbelief ill the possibility of oxygen being able to act upon the blood through the animal membrane or coat of the vessel in which it is confined. It is obvious, however, that to reach the blood circulating in the lungs, the oxygen must, in all cases, pass through the coats of the pulmonary vessels. These coats, indeed, offer little or no obstacle, and, conse- quently, there is no necessity for the vital or secretory action suggested by Mr. Ellis. Besides, Priestley and Hassenfratz exposed venous blood to atmospheric air and oxj^gen in a bladder, and in all cases, the parts of the blood, in contact with the gases, became of a florid colour. The experiments of Drs. Faust, Mitchell, and others (p. 68), are, in this respect, pregnant with interest. They prove the great facility with which the tissues are penetrated by gases, and confirm the facts developed by the experiments of Priestley, Hassenfratz, and others. The second theory, — that the carbonic acid is generated in the course of the circulation, — was proposed by M. La Grange, in conse- quence of the objection he saw to the former hypothesis — that the lung ought to be consumed by the perpetual disengagement of caloric within ^ it; or, if not so, that its temperature ought to be much superior to that of other parts. He accordingly suggested, that, in the lungs, the oxy- gen is simply absorbed, passes into the venous blood, circulates with it, and unites, in its course, with the carbon and hydrogen, so as to form carbonic acid and water, which circulate with the blood, and are finally exhaled from the lungs. The ingenious and apparently accurate experiments of M. Edwards' proved convincingl}'', not only that 0x3' gen is absorbed by the pulmo- nary vessels, but that carbonic acid is exhaled from them. When he confined a small animal in a large quantity of air, and continued the experiment sufficiently long, he found, that the rate of absorption was greater at the commencement than towards the termination of the experiment; and that, at the former period, there was an excess of oxygen, and at the latter an excess of carbonic acid. This proved to him, that the diminution was dependent upon the absorption of oxy- gen, not of carbonic acid. His experiments in proof of the exhalation ' Traite de Chimie, edit, citat. ^ Op. citat., p. 437, and Messrs.' Allen and Pepys, in Philos. Transactions for 1829. 318 RESPIRATION. of carbonic acid, ready formed, by tbe lungs, are decisive. Spallanzani had asserted, that when certain of the lower animals are confined in gases containing no oxygen, the production of carbonic acid is unin- terrupted. Upon the strength of this assertion, M. Edwards confined frogs in pure hydrogen for a length of time. The result indicated, that carbonic acid was produced, and in such quantity, that it could not have been derived from the residuary air in the lungs; as in some cases it was equal to the bulk of the animal. The same results, although to a less degree, were obtained with fishes and snails, — the animals on which Spallanzani's observations were made. The experiments of Edwards were extended to the mammalia. Kittens, two or three days old, were immersed in hydrogen: they remained in this situation for nearly twenty minutes without dying, and on examining the air of the vessel after death, it was found, that they had given ofi" a quantity of carbonic acid greater than could possibly have been contained in their luno-s at the commencement of the experiment. The conclusion of Dr. Edwards, from his various experiments, is, "that the carbonic acid ex- pired is an exhalation proceeding wholly or in part from the carbonic acid contained in the mass of blood." Several experiments were sub- sequently made by M. Collard de Martigny,^ who substituted nitrogen for hydrogen; and, in all cases, carbonic acid gas was given out in considerable quantity. These and other experiments would seem, then, to show, that in the lungs, carbonic acid is exhaled, and oxygen and nitrogen are absorbed. They would also seem to prove the existence of carbonic acid in venous blood, respecting which so much dissidence has existed amongst chemists, but which ought to be put at rest by the decisive observations of Magnus,^ which show, that both venous and arterial blood contain oxygen, nitrogen and carbonic acid, which they give up when the blood is placed in vacuo; and farther, that from 10 to 12J^ per cent, of oxygen, by volume, exists in arterial blood ; whilst in venous blood, there is only one-half that amount ; and on the other hand, that there is about 25 per cent., by volume, of carbonic acid in venous blood, to only 20 in arterial. Allusion has already been made to the fact, that gelatin is not met with in the blood, and to the idea of Dr. Prout,^ that its formation from albumen must be a reducing process. This process he considers to be one great source of the carbonic acid that exists in venous blood. Gelatin contains three or four per cent, less carbon than albumen; it enters into the structure of every part of the animal frame, and espe- cially of the skin; the skin, indeed, contains little else than it. He considers it, therefore, most probable, that a large part of the carbonic acid of venous blood is formed in the skin, and analogous textures. "Indeed," he adds, "we know that the skin of many animals gives oflf carbonic acid, and absorbs oxygen ; — in other words, performs all the offices of the lungs; — a function of the skin perfectly intelligible, on the supposition, that near the surface of the body the albuminous por- tions of the blood are always converted into gelatin." Gmelin and ' Journal de Physiologic, x. 111. 2 Annal. der Physik und Chemie, Ixvi. 177, Philosophical Mag., Dec. 1845, and Annales de Chemie et de Physique, Nov. 1837. 3 Bridgewater Treatise, Aiuer. edit,, p. 280, Philad., 1834. H^MATOSIS. 319 Tieclemann, Mitsclierlich/ and Stromeyer,^ affirm, on the strengtli of experiments, that the blood does not contain free carbonic acid, but that it holds a certain quantity in a state of combination, which is set free in the lungs, and commingles with the expired air. The views of Gmelin and Tiedemann, and Mitscherlich on this subject are as follows. It may be laid down as a truth, that the greater part, if not all, of the properties of secreted fluids are not dependent upon any act of the se- creting organs, but are derived from the blood, which again, must either owe them to the food, or to changes effected on it within the body. These changes are probably accomplished, in part, during the process of digestion, but are doubtless mainly effected in the lungs by the contact of the blood with the air. Now, most of the animal fluids, when exposed to the air, generate, by the absorption of oxygen, acetic or lactic acid, and this is aided by an elevated temperature, like that of the lungs. In their theory of respiration, the nitrogen of the inspired air is but sparingly absorbed, — by far the greater proportion remaining in the air-cells. The oxygen, on the other hand, penetrates the mem- branes freely ; mingles with the blood ; combines partly with the carbon and hydrogen of that fluid, and generates carbonic acid and water, which are thrown off with the expired air; the remainder combines with the organic particles of the blood, forming new compounds, of which the acetic and lactic acids are two; these unite with the carbonated alkaline salts of the blood, and set free the carbonic acid, so that it can be thrown off by the lungs. The acetate of soda — thus formed during the passage of the blood through the lungs — is deprived of its acetic acid by the several secretions, especially by those of the skin and kidneys, and the soda again combines with the carbonic acid, formed during the circula- tion of the blood through the body, by the decomposition of its organic elements. Carbonate of soda is thus regenerated, and conveyed to the lungs, to be again decomposed by the fresh formation of acids in those organs. Almost the same view is entertained by MM. Dumas and Boussingault, and it is esteemed by Professor Graham^ to be highly probable. Another view, in many respects similar, is held by Professor Arnold.* As it is more than probable, he remarks, that the carbonic acid occurs in the venous blood, united with some substance from which it is sepa- rated with greater or less rapidity by the contact of atmospheric air ; and as, further, the carbonate of protoxide of iron greedily withdraws oxygen from the atmosphere, at the same time parting with its car- bonic acid and becoming changed into a peroxide, it may be reason- ably supposed, that the carbonic acid of venous blood is united with the iron of the red colouring matter, and is set free during the act of re- spiration, by the ^-eciprocal action of the blood and air. The protoxide, by absorption of oxygen, becomes a peroxide, which, during the circu- lation of the blood through the capillaries, again parts with its oxygen. Carbon is at the same time eliminated from the blood, and unites with the liberated oxygen to form carbonic acid, which is thrown out by the ' Tiedemann und Treviranus, Zeitsehrift fiir Physiol., B. v. H. i. ^ Schweigger's Journal fiir Chimie, u. s. w., Ixiv. 105. ' Elements of Chemistry, Amer. edit., by Dr. Bridges, p. 687, Philad., 1843. * Lehrbuch der Phvsiologie des Meuschen, Ziirich, 1836-7. 820 RESPIRATION. luiifis, whilst oxvgen is again absorbed. Tliis is the view embraced by Liebig/ who has affirmed, that the amount of iron present in the bhood, if in the state of protoxide, is sufficient to furnish the means of trans- porting twice as much carbonic acid as can possibly be formed by the oxygen absorbed in the lungs. MM. Chaussier and Adelon,'* again, regard the whole process of hsematosis to be essentially organic and vital. They are of opinion, that an action of selection and elaboration is exerted both as regards the reception of ox^-gen and the elimination of carbonic acid. But their arguments on this point are unsatisfactor}^, and are negatived by the facilit}^ with which ox}' gen can be imbibed, and carbonic acid trans- udes through animal membranes. In their view, the whole process is effected in the lungs, as soon as the air comes in contact with the vessels containing venous blood. Imbibition of oxygen they look upon as a case of ordinary absorption; transudation of carbonic acid as one of exhalation; both of which they conceive to be, in all cases, tito factions, and not to be likened to any phj^sical or chemical process. Admitting that oxygen and a portion of nitrogen absolutely enter the pulmonary vessels, of which we have direct proof, are they, it has been asked, separated from the air in the air-cells, and then absorbed ; or does the air enter undecomposed into the vessels, and then furnish the proportion of each of its constituents needed by the wants of the svstem, — the excess being rejected ? Could it be shown, that such a decomposition is actually effected at the point of contact between the pulmonary vessels and the air in the lungs, it would seem, at first, to prove the notion of Mr. Ellis,^ and of Chaussier and Adelon, that a vital action of selection is exerted; but the knowledge we have attained concerning the transmission of gases through animal membranes would suggest another explanation. The rate of transmission of carbonic acid is greater than that of 0x3^ gen; of oxygen greater than that of nitrogen (see p. 69). We can hence understand, that more oxygen than nitrogen may pass through the coats of the pulmonary bloodvessels, and can comprehend the facility with which the carbonic acid, formed in the course of the circulation, may permeate the same vessels, and mix with the air in the lungs. Sir Humphry Davy is of opinion, that the whole of the air is absorbed, and that the surplus quantitj^ of each of the constituents is subsequently discharged. In favour of this view, he remarks that air has the power of acting upon the blood through a stratum of serum, and he thinks that the undecomposed air must be absorbed before it can arrive at the blood in the vessels. It is proba- ittle, however, from the ditYerent penetrating powers of the gases — oxy- gen and nitrogen, — that the proportion of those constituents cannot be the same in the interior as at the exterior of the pulmonary vessels. Professor Miiller," however, accords with Sir Humphry, and supposes that the air, on entering the lungs, is decomposed in consequence of the affinity of oxygen for the red particles of the blood ; carbonic acid ' Animal Chemistry, Webster's Amer. edit., p. 2G1, Cambridge, 1S43. ^ Pliysiologie de rHomrae, edit, cit., iii. 25-1. ' An Enquiry into the Changes induced on Atmospheric Air, &c., Ediub., 1807; and Further Enquiries, Edinb., 181(3. * Ilandbuch, u. s. w., Baly's translation, p. 334, Loud., 1838. H^MATOSIS. 321 being formed, whicli is exhaled in the gaseous form, along with tlie greater part of the nitrogen.^ It has been remarked, that when oxygen is applied to venous blood out of the bod}^, the latter assumes a florid colour. On what part of the blood, then, does the oxygen act? Doubtless, upon the red cor- puscles. Facts, hereafter stated in the description of venous blood, have appeared to some to show that these corpuscles are devoid of colour, whilst they exist in chyle and lymph ; and that in the lungs, the contact of air changes them to a florid red. The coloration of the blood is, consequently, eflected in the lungs ; but whether this change be of any importance in heematosis is doubtful. In many animals, the red colour does not exist ; and, in all, it can perhaps only be esteemed an evidence, that the other important changes have been accomplished in those organs. Of late, the opinion has been revived, that the oxy- gen of the air acts upon the iron, which Engelhart and Rose^ had detected in the colouring matter, — but how we are not instructed. It has been asserted, that if the iron be separated, the rest of the colour- ing matter, which is of a venous red colour, loses the property of becoming scarlet by the contact of oxygen ; but this, again, has been denied. Another view of arterialization has been advanced by Dr. Stevens.^ According to him, the colouring matter is naturally very dark; is rendered still darker by acids, and acquires a florid hue from the addi- tion of chloride of sodium, and from the neutral salts of the alkalies generally. The colour of ai'terial blood is ascribed by him to hema- tm reddened by the salts contained in the serum; the characters of venous blood to the presumed presence of carbonic acid, which, like other acids, darkens hematin; and the conversion of venous into arterial blood to the influence of the saline matter in the serum being restored by the separation of carbonic acid. If we take a firm clot of venous blood, cut oft" a thin slice, and soak it for an hour or two in repeatedly renewed portions of distilled water; in proportion as the serum is washed away, the colour of the clot deepens; and, when scarcely any serum remains, the colour, by reflected light, is quite black. In this state, it may be exposed to the atmosphere, or a cur- rent of air may be blown upon it, without any change of tint what- ever; whence it would follow, that when a clot of venous blood, moistened with serum, is made florid by the air, the presence of serum is essential to the phenomenon. The serum is believed, by Dr. Ste- vens, to contribute to this change by means of its saline matter; for when a dark clot of blood, which oxygen fails to redden, is immersed in a pure solution of salt, it quickly acquires the crimson tint of arte- rial blood ; and loses it again when the salt is abstracted by soaking in distilled water. The facts, detailed by Dr. Stevens, were confirmed ' See, on this subject, I>r. John Reid, art. Respiration, Cyclop, of Auat. and Physiol., Ft. xxxii. p. 3t)5, Lond., Aug., 1848. ^ Edinb. Med. and Surg. Journal for Jan., 1827. ' Observations on the Healthy and Diseased Properties of the Blood, Lond., 1832 ; and Proceedings of the Royal Society for 183-J-5, p. 334. VOL. I. — 21 322 RESPIRATION. by Mr. Prater,' and by Dr. Turner,^ of the London University. The latter gentleman, assisted by Professor Quain, of the same institution, performed the following satisfactory experiment. He collected some pei'fectly florid blood from the femoral artery of a dog ; and on the following day, when a firm coagulum had formed, several thin slices were cut from the clot with a sharp penknife, and the serum was removed from them by distilled water, which had just before been briskly boiled, and allowed to cool in a well-corked bottle. The water was gently poured on these slices, so that while the serum was dis- solving, as little as possible of the colouring matter should be lost. After the water had been poured off", and renewed four or five times, occupying in all about an hour, the moist slices were placed in a saucer at the side of the original clot, and both portions were shown to several medical friends, all of whom unhesitatingly pronounced the unwashed clot to have the perfect appearance of arterial blood, and the washed slices to be as perfectly venous. On restoring one of the slices to the serum it shortly recovered its florid colour ; and another slice, placed in a solution of bicarbonate of soda, instantly acquired a similar hue ; — yet, as we have seen, carbonate of soda is considered by Messrs. Gmelin, Tiedemann, and Mitscherlich, to exist in venous or black blood! In brightening, in this way, a dark clot by a solution of salt or a bicarbonate. Dr. Turner found the colour to be often still more florid than that of arterial blood ; but the colours were exactly alike when the salt was duly diluted. Dr. Turner remarks, that he is at a loss to draw any other inference from this experiment, than that the florid colour of arterial blood is not due to oxygen ; but, as Dr. Stevens sug- gests, to the saline matter of the serum. The arterial blood, which was used, had been duly oxygenized within the body of the animal, and should not in that state have lost its tint hy. the mere removal of its serum; and he adds, — the change from venous to arterial blood appears, contrary to the received doctrine, to consist of two parts essentially distinct; one a chemical change, essential to life, accom- panied by absorption of oxygen, and evolution of carbonic acid; the other dependent on the saline matter of the blood, which gives a florid tint to the colouring matter after it has been modified by the action of oxygen. "Such," says Dr. Turner, "appears to be a fair inference from the facts above stated; but being drawn from very limited ob- servation, it is ottered with diffidence, and requires to be confirmed or modified by future researches." But we are perhaps scarcely justified in inferring, from the experiments of Stevens, Turner, and others, more than the fact, that a florid hue is communicated to blood by sea- salt, and by the neutral salts of the alkalies in general, and indeed by admixture with sugars ; whilst acids render it still darker. The pre- cise changes that occur during the arterialization of the blood in the lungs are still unknown. Since Dr. Stevens first published his views, fhe subject has been farther investigated by Dr. William Gregory, and Mr. Irvine. They ' Experim. Inquiries in Chemical Physiology, Part i., on the Blood, Lond., 1832. * Elements of Chemistry, 5th edit., by Dr. Bache, p. 609, Pliilad., 1835. H^MATOSIS. 323 introduced portions of clot, freed b}'' ■washing from serum, into vessels containing pure hydrogen, nitrogen, and carbonic acid, placed over mercury. As soon as the strong saline solution came in contact with them, the colour of the clot, in all the gases, changed from black to bright red ; and the same change was found to take place in the Tor- ricellian vacuum. On repeating these experiments with the serum of blood, and a solution of salt in water of equal strength with the serum, no change took place until atmospheric air, or oxygen gas, was ad- mitted. Whence it appears — as properly inferred by the late Mr. Egerton A. Jennings, who published an interesting " Report on the Chemistry of the Blood as Illustrative of Pathology,'" — that though saline matter may be necessary to effect the change of colour of venous to that of arterial blood, with so dilute a saline solution as that which exists in serum, the presence of oxygen is likewise necessary. Dr. Davy^ dissents, however, from these conclusions, and is disposed to infer, from all the facts with which he is acquainted, that the colour of the blood, whether venous or arterial, — that is, dark or florid, — is inde- pendent of the saline matter in the serum, considered in relation to agency; and that, according to the commonly received view, oxygen is the cause of the bright hue of the arterial fluid, and its consump- tion and conversion into carbonic acid the cause of the dark hue of the venous, — the saline matter being negative in regard to colour; and its chief use, in his opinion, being " to preserve the red globules from injury, prevent the solution of their colouring matter, retain their forms unchanged, and to bear them in their course through the circu- lation. In the difficulty of the subject, an idea has been entertained, that the change from arterial to venous blood, and conversely, as regards colour, is dependent in a great measure on a difference in the shape of the blood corpuscles ; and is therefore owing rather to physical than to chemical changes in them. Such is the opinion of Kaltenbrunner, Schultz, Renter, Gulliver, Ilarless, Kirkes and Paget,^ Nasse, Mulder, Funke, and others. It is of course opposed to that of Liebig, already stated. Mulder'* explains the difference between the colour of arterial and venous blood as follows. Two oxides of protein are formed in the act of respiration, which have a strong plastic tendency, and soli- dify around each corpuscle, making the capsule thicker, and better qualified to reflect light. Each corpuscle of arterialized blood is then, in reality, invested with a complete envelope of buffy coat, which gra- dually contracts, and speedily forms cupped or bi-concave surfaces, which are favourable to the reflection of light. On reaching the capil- laries, the coating of the oxides of protein is removed, and the cor- puscles, losing their opaque investment, and cupped form, no longer ' Transactions of the Provincial Medical and Surgical Association, vol. iii., Worces- ter and London, 1835. ^ Researches, Physiological and Anatomical, Dunglison's Amer. Med. Lib. edit., p. 96, Philad., 1840. ^ Manual of Physiology, 2d Amer. edit., p. 59, Philad., 1853. ■■ Versuch einer Allgemeinen Physiologischen Chemie, cited by Dr. Day in Simon, Animal Chemistry, Sydenham edit., p. 193, Lond., 1845; and Chemistry of Vegetable and Animal Pliysiology, translated by Fromberg, p. 342, Lond. and Ediiib., 1849. 32-i RESPIRATION. reflect light, and tlie blood assumes the venous tint. Dr. G. 0. Rees/ however, considers this explanation to be entirely hypothetical and erroneous. He rejects the idea of a layer of plastic oxy-protein being deposited on the blood corpuscles during respiration; and instead of considering the hematin as undergoing no change, and maintaining the same condition in arterial and venous blood, he looks upon it as the cause of the change of colour in the blood by virtue of some che- mical alteration, which takes place in it, but whose nature — if there be anv such alteration — remains a mystery. He has himself advanced the following ingenious theory.^ He found by analysis, that the cor- puscles of venous blood contain fatty matter in combination with phosphorus. This does not exist in arterial blood, or, at most, is met with in it in very small quantity. During respiration the oxygen of the inspired air unites with the phosphorus and fatt}^ matter, and com- bustion takes place; of which the products are water and carbonic acid from the union of the oxygen with the elements of the fatty matter ; and phosphoric acid from the union of the oxygen with the phosphorus. The carbonic acid and water are exhaled, and appear in the expired air ; the phosphoric acid attracts the soda of the liquor sanguinis from its combination with albumen and lactic acid, and forms a tribasic phosphate of soda, — a salt, which possesses in a marked degree the property of communicating a bright colour to hematin. It is proper to add, thatBurdach, MuUer, Bruch, Marchand, Scherer, and others, have failed to detect by the microscope any difterence in the external form of the corpuscles in arterial and in venous blood. Still, Dr. John Reid^ is disposed to conclude, that the change in the blood from the venous to the arterial hue in the lungs is a physical and not a chemical action; and "that though there is pretty strong evidence in favour of the opinion, that this physical change consists in an alteration of the form of the red corpuscles, yet it is not free from doubt." The author has, indeed, always had great doubts on the matter; and must continue to have them, until such a change as is supposed to be produced in the shape of the corpuscles is demon- strated. It remains to be proved, that the blood — as Dr. Carpenter^ now maintains — "is darkened by whatever tends to distend the corpus- cles, so as to render them flat, or biconvex, whilst it is brightened by whatever tends to empty them, so as to render them more deeply bi- concave than usual. And observation of the effects of oxygen and carbonic acid, respectively, upon the form of the corpuscles, confirms the idea, that this is the mode in which these agents affect their colour, for the former causes their contraction, and renders their cell walls thick and granular so as to increase their power of reflecting light; whilst the latter, producing a dilatation of the corpuscles, thins their cell walls, and enables them to transmit light more readil3\" Recently, » Lond. Med. Gazette, 1844-5, p. 840. See, also, Mulder, op. cit., p. 341. 2 Proceedings of the Royal Society, June 3, 1847, and Lond., Edinb., and Dublin Philos. Magazine for July, 1848. 3 Art. Respiration, Cyclop, of Anat. and Physiology, Pt. xxxii. p. 361, Loudon, August, 1848. * Principles of Human Physiology, Amer. edit., p. 195, Philad. 1855. H^MATOSIS. 325 Moleschott^ and Brucli have instituted a fresh set of observations to show, that the colour of the blood is independent of the shape of the corpuscles. The former affirms, that neither oxygen, nor carbonic acid, which are concerned in the coloration of that fluid, change per- ceptibly the shape or size of the blood-corpuscles in man, the mam- malia, fowls, or frogs; and he affirms, that very dilute solutions of chloride of sodium or of sulphate of soda, which produce no change in the shape of the corpuscles sensibly redden the blood. Messrs. Todd and Bowman^ carefully examined two portions of the same blood after they had been agitated in oxygen and carljonic acid gas, and thus been rendered respectively scarlet and purple, and failed to detect any well-marked difference in shape between the corpuscles of the two specimens. Bruch^ has also given additional reasons for the belief, that the colour of the blood is independent of the shape of the corpuscles. He is of opinion, that the natural colour is probabl}'^ that of venous blood; and that the vermilion hue is communicated to arterial blood by the combination of the hematin with oxygen ."• The author has always been of opinion, that the question will have to be settled by tlie chemist rather than by the physicist ; and that the change of colour is owing to the different effects of agents — of which oxygen is the chief — on the hematin ; but as to the precise mode in which the phenomena are accomplished we are in want of information. The slight diminution, if it exist, in the specific gravity of arterial blood has been considered, but we know not on what grounds, to de- pend on the transpiration, which takes place into the air-cells, and was formerly thought to be owing to the combustion of oxygen and hydro- gen. This will engage us in another place ; — as well as the changes produced in its capacity for heat, on which several ingenious specula- tions have been founded to account for animal temperature. The other changes are at present inexplicable; and can only be understood by minute chemical analysis, and by an accurate comparison of the two kinds of blood, — venous and arterial. This has been carefully done by Simon, who infers, from his analyses, that arterial blood gene- rally contains less solid residue than venous blood; and less fat, albu- men, hematin, extractive matter, and salts ; but further experiments are demanded. The blood corpuscles of arterial blood contain less colouring matter than those of venous blood.^ It is manifest, from the preceding detail, that our knowledge regard- ing the precise changes effected on the air and the blood by respiration is by no means definite. We may, however, consider the following points established. In the first place: — the air loses a part of its oxy- gen and nitrogen; but this loss varies according to numerous circum- ' Ziir Lelire von der Blutfarbe, in Milnchn. Illustr. Med. Zeit., Mars, 1853; and Canstatt's Jahresb., 1853, i. 101, Wilrzburg, 1854. ^ Physiological Anatomy and Physiology of Man, Pt. iv., p. 298, Lond., 1852; or Amer. edit., Philad., 1853. '^ Ueber die Blutfarbe, in Siebold und Kcilliker's Zeitschr. ; and Canstatt, loc. cit. * J. Beclard, Traite Klementaire de Physiologie, p. 295, Paris, 1855. * For various analyses of the two kinds of blood, see Simon, op. cit., p. 194. 826 RESPIRATION. Stances, 2(lly. It is found to have acquired carbonic acid, the quan- tity of which is also variable. 3dly. The bulk of the air is diminished; but the extent of this likewise differs. 4thly. The blood, when it attains the left side of the heart, has a more florid colour, othly. This change appears to be caused by the contact of oxygen. 6thly. The blood in the lungs gets rid of a quantity of carbonic acid. Tthly. The oxygen taken in is more than necessary for the carbonic acid formed. 8thly. The constituents of the air pass directly through the coats of the pulmonary vessels, and certain portions of each are dis- charged or retained, according to circumstances. 9thly. A quantity of aqueous vapour is discharged from the lungs ; the expired air is indeed saturated with it. lOthly. The expired air has always a tem- perature at or near 99°; and, lastly, it would appear, from the facts stated elsewhere, that the red corpuscles are not the only constituent of the blood that undergoes a change in the respiratory process ; and that the fibrin of venous blood most nearly resembles albumen, whilst that of arterial blood contains more oxygen. c. Cutaneous Bespii-ation, d-c. A question has arisen, whether absorption and exhalation of air, and conversion of blood from venous to arterial, take place in any other part of the body than the lungs. The reasons, urged in favour of the affirmative of this question, are; — that, in the lower classes of animals, the skin is manifestly the organ for the reception of air; that the mucous membrane of the lungs evidently absorbs air, and is simply a prolongation of the skin, resembling it in texture; and, lastly, that when a limited quantity of air has been placed in contact with the skin of a living animal, it has been absorbed, and found to have experienced the same changes as are effected in the luno-s. Mr. Cruikshank' and Mr. Abernethy-^ analyzed air in which the hand or foot had been con- fined for a time ; and detected in it a considerable quantity of carbonic acid. Jurine, having placed his arm in a cylinder hermetically closed, found, after it had remained there two hours, that oxygen had disap- peared, and 0.08 of carbonic acid had been formed. These results were confirmed by Gattoni;^ and from experiments by Professor Scharling, referred to before, the amount of carbon exhaled by the skin in the twenty-four hours, has been estimated at two ounces ; but this is probably beyond the real amount. On the other hand, Drs. Priestley,"* Klapp,* and Gordon® could never perceive the least change in the air under such circumstances. Perhaps in these, as in all cases where the respectability of testimony is equal, the positive ought to be adopted rather than the negative. It is probable, however, that ab- sorption is effected with difficulty; and that the cuticle, as we have elsewhere shown, is placed on the outer surface to obviate the bad ' Experiments on the Insensible Perspiration, &c., Lond., 1795. ^ Surgical and Physiological Essays, Part ii. p. 115, Lend., 1793. 3 Diet, des Sciences Medicales, art. Peau. * Experiments and Observations on Difl'erent Kinds of Air, ii. 193, and v. 100, Lend., 1774. * Inaugural Essay on Cutieular Absorption, p. 24, Philirl,, 1S05. ^ Ellis's Imjuiry into the Changes of Atmospheric Air, &c., p. 355, Edinb., 1837. EFFECTS OF DIVIDING CERTAIN NERVES. 327 effects that would be induced by heterogeneous gaseous, miasmatic, or other absorption. We have seen that some of the deleterious gases, as sulphuretted hydrogen, are most powerfully penetrant, and, if they could enter the surface of the body with readiness, unfortunate re- sults might supervene. In those parts where the cuticle is extremely delicate, as in the lips, some conversion of venous into arterial blood may be effected, and this may be a great cause of their florid colour. According to this view, the arterialization of the blood occurs in the lungs chiefly, owing to their formation being so admirably adapted to the purpose; and it is not effected in other parts, because their arrange- ment is unfavourable for such a result. d. Effects of the Section of certain Nerves on Respiration. It remains to inquire into the effect produced on the lungs by the cerebro-spinal and spuial nerves distributed to them, — or rather, into what is the effect of depriving the respiratory organs of their nervous influence from the brain and spinal marrow. The only encephalic nerves, distributed to them, are the pneamogastric or eighth pair of Willis, which, we have seen, are sent, as their name imports, to both the lungs and stomach. The section of these nerves early suggested itself to physiologists, but it is only in recent times that the pheno- mena resulting from it have been clearly comprehended. The opera- tion appears to have been performed as long ago as the time of Eufus of Ephesus, and was afterwards repeated by Chirac, Bohn, Duverney, Vieussens, Schrader, Valsalva, Morgagni, Haller, and numerous other distinguished physiologists. It is chiefly, however, in recent times, and especially from the labours of Dupuytren, Dumas, De Blainville, Provengal, Legallois, Magendie, Breschet, Hastings, Broughton, Sir Benjamin Brodie, Wilson Philip, Longet, John Reid, and others, that the precise effects upon the respiratory and digestive functions have been appreciated. When these nerves are divided in a living animal, on both sides at once, the animal dies more or less promptly ; at times immediately after their division, but it sometimes lives for a few days; — M. Magen- die says never beyond three or four. The eftects produced upon the voice, by their division above the origin of the recurrents, will be referred to under another head. Such division, however, does not simply implicate the larynx; it necessarily aftects the lungs, as well as the stomach. As regards the larynx, the same results, according to M. Magendie,^ are produced by dividing the trunk of the pneu- mogastric above the origin of the recurrents as by the division of the recurrents themselves ; the muscles, whose function it is to dilate the glottis, are paralyzed ; and consequently, during inspiration, no dilatation takes place; Avhilst the constrictors, which receive their nerves from the superior laryngeal, preserve all their action, and close the glottis, at times so completely, that the animal dies at once from suffocation. But if the division of those nerves should not induce in- stant death in this manner, phenomena f-)llow, considerably alike in all cases, which go on until the death of the animal. These are the fol- ' Precis, &c., 2de edit., ii. 355. 328 RESPIRATION. lo\ying: — respiration is, at first, difficult; the inspiratory movements are more extensive and rapid, and the animal's attention appears to be particularlv directed to them; the locomotive movements are less frequent, and evidently fatigue; frequently, the animal remains en- tirely at rest ; the formation of arterial blood is not prevented at first, but soon, on the second day for instance, the difficulty of breatliing augments, and the inspiratory efforts become gradually greater. The arterial blood has now no longer the vermilion hue proper to it. It is darker than it ought to be: its temperature falls; respiration requires the exertion of all the respiratory powers; the body gradually becomes cold, and the animal dies. On opening the chest, the air-cells, bronchi, and frequently the trachea, are found filled by a frothy fluid, which is sometimes bloody; the substance of the lung is tumid ; the divisions and even the trunk of the pulmonary artery are greatly distended with dark, almost black, blood ; and extensive effusions of serum and even of blood are found in the parenchyma of the lungs. Experiments have, like- wise, shown that, in proportion as these phenomena appeared, the ani- mal consumed less and less oxygen, and gave off a progressively dimin- ishing amount of carbonic acid. From the phenomena that occur after the section of the nerves on both sides, it would seem to follow, that the first effect is exerted upon the tissues of the lungs, which, being deprived of nervous influence, are no longer capable of exerting their ordinary tonicity and muscu- larity. Eespiration, consequently, becomes difficult ; the blood no longer circulates freely through the capillary vessels of the lungs ; the consequence is, that transudation of its serous portions, and occa- sionally effusion of blood, owing to rupture of small vessels, takes place, filling the air-cells more or less ; until, ultimately, all com- munication is prevented between the inspired air and the bloodves- sels, and the conversion of venous into arterial blood is completely precluded. Death is then the inevitable and immediate consequence. The division of the nerve on one side affects merely the lung of the corresponding side. Life can be continued by the action of one lung only : it is, indeed, a matter of astonishment how long some indi- viduals have lived when the lungs have been almost wholly obstructed. Every morbid anatomist has had repeated opportunities of observing, that for a length of time prior to dissolution, in cases of pulmonary consumption, the process of respiration must have been carried on by a very small portion of lung. From his experiments on this subject. Sir Astley Cooper infers, that the pneumogastric nerve is most important ; — 1st, in assisting in the maintenance of the function of the lungs, by contributing to the change of venous into arterial blood; 2dly, in being necessary to the act of swallowing ; and 3dly, in being essential to the digestive process. Dr. John Reid is of opinion, that the pulmonary branches seem to be nerves concerned chiefly in transmitting to the medulla oblongata the impressions that excite respiratory movements, and are thus princi- pally afferent nerves ; but it is possible, he thinks, that they contain- motor filaments also.' ' Edinb. Med. and Surg. Joum., April, 1839 ; and art. Par Vagum in Cyclop, of Anat. and Physiol., Part sxvii. p. 896, March, 1846. OF ANIMALS. 329 The experiments of Dr. Wilson Philip' and others show, moreover, — what has been more than once inculcated, — the great similarity between the nervous and galvanic fluids. The state of dyspnoea induced by the division of the pneumogastric nerves was, in numerous cases, entirely removed by the galvanic current passed from one divided extremity to the other. The results of these experiments induced him to try gal- vanism in cases of asthma. By transmitting its influence from the nape of the neck to the pit of the stomach, he gave decided relief in every one of twenty-two cases ; four of which occurred in private prac- tice, and eighteen in the Worcester Infirmary. Sir A. Cooper^ instituted similar experiments on the phrenic nerves. As soon as they were tied, the most determined asthma was produced; breathing went on by means of the intercostal muscles ; the chest was elevated to the utmost by them ; and in expiration the chest was as remarkably drawn in. The animals did not live an hour ; but they did not die suddenly, as they do from pressure on the carotid and vertebral arteries. The lungs appeared healthy, but the chest con- tained more than its natural exhalation. He also tied the great sym- pathetic; which produced little effect; the heart appeared to beat more quickly and feebly than usual. The animal was kept seven days, when one nerve was found ulcerated through ; the other nearly so at the situation of the ligatures. On examination, no particular altera- tion of any organ was observed. Lastly, Sir Astley tied all three nerves on each side, the pneumogastric, phrenic, and great sympa- thetic: the animal lived little more than a quarter of an hour, and died of dyspnoea. From these experiments, he infers, that the sudden deatli, which he found to follow pressure on the sides of the neck, cannot be attributed to any injury of the nerves, but to an impediment to the due supply of blood to the great centres of nervous influence. The nervous centre of the respiratory movements is the vesicular neurine in the upper part of the medulla oblongata. Into it the pneu- mogastric nerves, which appear to be the chief excitors of respiration, may be traced; and from it the different motor or efferent nerves pro- ceed either directly or indirectly. Of these, the most important is the phrenic. The vesicular neurine of the medulla receives the impression of the besoin de respirer or necessity of breathing; and thence it is reflected along the appropriate nerves to the muscles concerned in inspiration.^ e. Respiration of Animals. In concluding the subject of respiration, we may briefly advert to the different modes in which the process is effected in the classes of animals, and especially in birds, — the respiratory organs of which con- stitute one of the most singular structures of the animal economy. The lungs themselves are comparatively small, and adherent to the chest, — where they seem to be placed in the intervals of the ribs. ' Experimental Inquiry into the Laws of the Vital Functions, &c., 2d edit., p. 223, Lend., 1818; also, Journal of Science and Arts, viii. 72. ^ Op. cit., p. 475. ^ See, on all this subject, Louget, Traite de Physiologie, ii. 328, Paris, 1850. 330 CIRCULATION". They are covered by the pleura on their under surface only, so that they are, in fact, on the outside of the cavity of the chest. A great part of the thorax, as well as of the abdomen, is occupied by mem- branous air-cells, into which the lungs open by considerable apertures. Besides these cells, a considerable portion of the skeleton in many birds forms receptacles for air, and if we break a long bone of a bird of flight, and blow into it when the body of the animal is immersed in water, bubbles of air will escape from the bill. The object, of course, of all this arrangement is to render the body light, and thus to facilitate its motions. Hence, the largest and most numerous bony cells are found in such birds as have the highest and most rapid flight, as the eagle. The barrels of the quills are likewise hollow, and can be filled with air, or emptied at pleasure. In addition to the uses just mentioned, these air receptacles diminish the necessity for breathing so frequently in the rapid and long-continued motions of certain birds, and in the great vocal exertions of those that sing. In fishes, in the place of lungs we find branchice or gills, which are placed behind the head on each side, and have a movable gill-cover. By the throat, which is connected with the gills, the water is conveyed to, and distributed through them: in this way, the air, contained in the water, which, according to Biot, Von Humboldt^ and Provengal, Configliachi, and Thomson,"^ is richer in oxygen than that of the atmo- sphere, having from 29 to 32 parts in the 100, instead of 20 or 21, comes in contact with the blood circulating through the gills. The water is afterwards discharged through the branchial openings, — ajjer- iurce branchiales, — and, consequently, they do not expire along the same channel as they inspire. Lastly, in the insect tribe, — in the white-blooded animal, — we find the function of respiration effected altogether by the surface of the body; at least, so far as regards the reception of air, which enters through apertures termed stigmata, the external terminations of ira- chece or air tubes, whose office it is to convey air to different parts of the sj^stem. In all these cases, we find precisely the same changes effected upon the inspired air; — and especially, that oxygen has disappeared; and that carbonic acid of a bulk nearly equal to that of the organ is met with in the residuary air.^ CHAPTEK IV. CIRCULATION". The next function to be considered is that by which the products of the various absorptions, converted into arterial blood in the lungs, are ' Memoires de la Societe d'Arcueil i. 252, and ii. 400. 2 Dr. Thomson found that 100 cubic inches of the water of the river Clyde con- tained 3-1 13 inches of air ; and that tlie air contained 29 per cent, of oxygen. Edinb. New Philosoph. Journal, xxi. 370, Edinb., 1836. 3 See Carpenter's Principles of Comparative Physiology, Amer. edit., Philad. 1854. CIRCULATORY APPARATUS. 331 Heart of the Duf D. Right auricle. E. Right ventricle. K. Left auricle. L. Left ventricle. F. Pulmonary artery. A. Aorta. distributed to every part of the body, — a Fig- SI* function most important to the physiolo- gist and the pathologist, and without a knowledge of which it is impossible for the latter to comprehend the doctrine of disease. Assuming the heart to be the great organ of the function, the circulatory fluid must set out from it, be distributed through the lungs, undergo aeration there, be sent to the opposite side of the heart, whence it is distributed to every part of the system by efferent vessels, and be re- turned by veins or afferent vessels to the right side, from which it set out, — thus performing a complete circuit. The lower classes of animals differ es- sentially, as we shall find hereafter, in their organs of circulation : whilst in some, the apparatus appears to be confounded with the digestive; in others, the blood is propelled with- out any great central organ ; and in others, again, the heart is biit a siligle organ. In man, and in the upper classes of animals, the heart is double; — consisting of two sides, or really two hearts, separated from each other by a septum. In the dugong, the two ventricles are almost entirely detached from each other. As all the blood of the body has to be emptied into this central organ, and to be subsequently sent from it ; and as its flow is continuous, two cavities are required in each heart, — the one to receive the blood, the other to propel it. The latter distinctly contracts and dilates alternately. The cavity or cham- ber of each heart, that receives the blood, is called auricle^ and the vessels that transport it thither are veins; the cavity by which the blood is projected forwards is called ventricle^ and the vessels, along which the blood is sent, are arteries. One of these hearts is entirely ap- propriated to the circulation of venous blood, and hence has been called venous hearty — also right or anterior heart, from its situation, — and pulmonary^ from the pulmonary artery arising from it. The other is for the circulation of arterial blood, and is hence called arterial heart, also left or posterior, from its situation, — aortic heart, because the aorta arises from it ; and systeynic, because the blood is sent from it to the general system. The whole of the vessels communicating ■j-l, xl • T J 1 , , • TIT sysiomic capiii Wltn the right heart contain venous blood ; collected by the veins, and earned those of the left side arterial blood. \lf^X "'" ^'"'^ '^'""'"' '^' ^'''* Diagram of the Circulating Ap- paratus in MamniaU and Birds. a. The heart, containing four cavi- ties. !>. Vena cava, delivering ve- nous blood into e, the right auricle. d. The right ventricle, propelling venous blood through e, the pulmo- nary artery, to /, the capillaries of the lungs, g. The left auricle, re- ceiving the aerated blood from the pulmonary vein, and delivering it to the left ventricle, h, which pro- pels it through the aorta, i, to the systemic capillaries, y, ivhence it Is 332 CIRCULATIOISr. If we consider the heart to be the centre, two circulations must be accomplished, before the blood, setting out from one side of the heart, performs the whole circuit. One of these consists in the transmission of the blood from the right side of the heart, through the lungs, to the left; the other, in its transmission from the left side, along the arteries, and by means of the veins, back to the right. The former is called the lesser or pulmonic, the latter the grexiter or systemic circulation. The organs, by which these are effected, will require a more detailed exa- mination. 1. AXATOMT OF THE CIRCULATORY ORGANS. The circulatory apparatus is composed of organs by which the blood is put in motion, and along which it passes during its circuit. a. Heart. To simplify the consideration of the subject we shall consider the heart double ; and that Fig. 93. Heart placed with its Anterior Surfnce upward?, and its Apex turned to the right hand of the spectator. The Right Auricle and Right Ventricle are both opened. Parts in right auricle: — h. Eutrance of vena cava superior, which is itself markeil d. Inferior cava, mai'ked r, has a prohe passed through it into the auricle, rn. The smooth part of the auricle, o. Musculi pectiuati, seen in the auricular appendix which is cut open. n. Eustachian valve placed over the mouth of the inferior cava. i. Fossa ovalis, or vestige of the foramen ovale, s. Annulus ovalis. The probe leading from s into the right ventricle passes through the auriculo-veutricular opening, v. Mouth of the coronary vein. Parts in the right ventricle, in which the other end of the probe, from s, appears: — a. Cavity of couus arteriosu.s, leading to the pulmonary artery, Jr. I. Convex septum between the ventricles, c. Anterior segment of the tricuspid valve, connected by slender cords, the chordae tendiuea, to the musculi papillares, e. /. The aorta. each system of circu- lation is composed of a heart; of arteries, through which the blood is sent from tRe heart; and of veins, by which the blood is re- turned to it. At the minute termination of each of these is a capil- lary system. We shall first describe the cen- tral oi'gan as forming two distinct hearts; and afterwards the two uni- ted. The pulmonic, right, or anterior heart, called also heart of hlach hlood, is composed of an auri- cle and a ventricle. The auricle, so termed from some resemblance to a small ear, is situate at the base of the organ, and receives the whole of the blood returned from various parts of the body by three veins; — the two vense cav^e, and the coronary. The vena cava descend- ens terminates in the auricle in the direction CIRCULATORY APPARATUS. 833 situate in the anterior Fig. 94. of the aperture by which the auricle communicates with the ventricle. The vena cava ascendens, the termination of which is directed more back- wards, has the remains of a valve which is much larger in the foetus, called valve of Eustachius. The third vein is the cardiac or coronary ; it returns the blood from the heart which has been carried thither by the coronary artery. In the septum between the right and left auricle, there is a superficial depression, about the size of the point of the finger, which is the vestige of the tbramen ovale, — an important part of the circulatory apparatus of the foetus. The opening through which the auricle projects its blood into the ventricle, is situate downwards and forwards, as seen in Fig. 93. The inner surface of the ^J^'oper auricle^ or that which more particularly resembles the ear of a quadru- ped, — the remainder being sometimes called siniis venosus or sinus vena- rum cavariim, — is distinguished by having a number of fleshy pillars in it, which, from their supposed resemblance to the teeth of a comb, are called musculi 'pectinati. They are mere varieties, however, of the columnce carneoi of the ventricles. The right ventricle or pulmonary ventricle is part of the heart; the base and apex corre- sponding to those of the heart. Its cavity is generally greater than that of the left side, and its parietes not so thick, owing to its having merely to force the blood through the lungs. It communicates with the auricle by the auri- culo-veyiti-icular opening — ostium venosum; and the only other opening into it is that which communicates with the interior of the pul- monary artery. The opening between the auricle and ventricle is furnished with a tri- partite valve, called tricuspid or trigloddn; and the pulmonary artery has three others, the sigmoid or semilunar. From the edge of the tricuspid valve, next the apex of the heart, small, round, tendinous cords^ called chordae tendineoe^ are sent oft', which are fixed, as represented in Fig. 93, to the extremities of a few strong columnar car- nece, — called musculi papillares. These tendinous cords are of such a length as to allow the valve to be laid against the sides of the ventricle, in the dilated state of that organ; and to ad- mit of its being pushed back by the blood, until a nearly complete septum is formed durino; the contraction of the ventricle. The semilunar or sigmoid valves are three in number, situate around the artery. When these fall to- gether, there must necessarily c. orifices of the coronary arteries. be a space left between them. To obviate the inconvenience that would result from the existence of such a free space, a small granular body is attached to the middle of Semilunar Valves closed. Diagram of the Semilunar Valves of the Aorta. !. Corpus Arantil on the free border. 6. Attached border. 334 CIRCULATION. tlie margin of each valve; and these, coming together, as at A, Fig. 94, when the valves are shut down, complete the diaphragm, and prevent any blood from passing back to the heart. These small bodies are termed, from their reputed discoverer, corjmscida Arantii, and also cor- puscula Morgagnii; or, from their resemblance to the seed of the sesamum, corpuscula sesamoidea. The valves, when shut, are concave towards the lungs, and convex towards the ventricle. Immediatel}'- above thern the artery bulges out, forming three sacculi or sinuses, called sinuses of Val- salva. These are often said to be partly formed by the pressure of the blood upon the sides of the vessel. The structure is doubtless ordained, and is admirably adapted for a specific purpose, — namely, to allow the free edges of the valves to be readily caught by the refluent blood, and thus facilitate their closure. Within the right ventricle, and especially Fig. 96. Sections of Aorta, to show the action of the Semilunar Valves. A. The valves, represented by the dotted lines, in contact with the arterial walls, represented by the continuous outer line. b. The arterial wall distended into three pouches (a), and drawn away from the valves, which are straightened into the form of an equilateral triangle, as represented by tlie dotted lines. r. The margins of the valves when in action: — a. Tlie pouches between the valves and the arterial wall. h. The apposed edges, c. The apposed surfaces of the valves, d. Mouths of coronary arteries, e. Cut edge of aorta. towards the apex of the heart, many strong eminences are seen, columnce carnece (Fig. 93), These run in different directions, but the strongest of them longitudinally with respect to the ventricle. They are of va- rious sizes, and form a beautifully reticulated texture. Their chief use probably is, to strengthen the ventricle, and prevent it from being over-distended; in addition to which they may tend to mix the differ- ent products of absorption. The corporeal^ left, aortic, or systemic heart, — called also heart of red hhod, — has likewise an auricle and a ventricle. The hft auricle is con- siderably thicker and stronger but smaller than the right; and it is likewise divided into simts (sinus arteriosus) and 2:)roper auricle, which form a common cavity. The columns in the latter are like those of the right, but less distinct. From the under part of the auricle, a cir- cular passage, termed ostium arteriosum or "auricular orifice," leads to the posterior part of the base of the cavity of the left ventricle. The left auricle receives the blood from the pulmonary veins. The left or aortic ventricle is situate at the posterior and left part of the heart. Its sides are three times thicker and stronger than those of the right ven- tricle, to adapt it for the much greater force it has to exert; for, whilst the right ventricle merely sends its blood to the lungs, the left ventricle transmits it to every part of the body. Its muscular force has been CIECULATORY APPARATUS. 835 Fig. 97. estimated at twice tliat of tlie right.' It is narrower and rounder, but considerably longer, than the right ventricle, and forms the apex of the heart. The internal surface of this ventricle has the same general appearance as the other; but differs from it in having larger, more nu- merous, firmer, and stronger columnse carneoe. In the aperture of communi- cation with the corresponding auri- cle, there is here, as in the opposite side of the heart, a ring or zone, from which a valve, essentially like the tricuspid, goes off". It is stronger, however, and divided into two prin- cipal portions only; the chordae tend- ine« and musculi jmjnUares, are also stronger and more numerous. This valve has been termed mitral, from some supposed resemblance to a bishop's mitre, and bicuspid. At the fore and right side of the valve, and behind the commencement of the pulmonary artery, a round opening exists, which is the mouth of the aorta. Here are three semilunar valves, with their coiyuscula Arantii; like those of the pulmonary artery, but a little stronger; and, on the outer side of the semilunar valves. Heart seen from behind, and having the Left Auricle and Ventricle opened. Parts in left auricle: — a. Smooth wall of ati- ricular septum, c, c, c. Opeaiugs of the four pulmonary veins, d. Left auricular appendage. e. Slight depression in the septum, corresponding to the fossa ovalis on the right side. A probe is seelll, which passes down into the ventricle through the auriculo-ventricular orifice. Parts in left ventricle: — i. Posterior segment of the , . - - Ti.T mitral valve, behind which is the probe passed are the sinuses of Vatsatva, a little tVom the left auricle. ■»., w. The two groups of „ • i. J.1 „ il „„ ,-P j-"U^ musculi papillares. o. Section of the thick walls more prominent than those Ot the ^f this ventricle, which may be comparod with ■nnlmnnov'sr nrtar-ir that of the walls of the right ventricle, Fig. 93. puimoil.liy aiLCiy. _ r. Entrance of inferior cava. The structure of the two hearts is the same. A serous membrane covers both. It is an extension of the inner membrane of the pericardium. The substance of the heart is essentially muscular. The fibres run in different directions, longitudinally and transversely, but most of them obliquely. Many pass over the point, from one heart to the other, and all are so involved as to render it difficult to unravel them. The cavities are lined by a thin membrane, endocardium,, which differs somewhat in the two hearts; — being in one a prolongation of the 'inner coat of the aorta, and in the other of the venae cavae. On this account, the inner coat of the left heart is but slightly extensible, more easily ruptured, and considerably disposed to ossify; that of the right heart, on the other hand, is very extensible, not readily ruptured, and but little liable to ossify. The endocardium invests all the elevations and depressions of the*^ heart, as well as the papillary muscles and their tendons, and the valves. It consists of three layers; an epithelium, an elastic layer on which the varying thickness of the endocardium in dif- ' Valentin, Lehrbucli der Physiologic des Menschen, i. 415, Braunscliweig, 1844. 536 CIECULATION. ferent situations depends, and a thin laj-er of connective tissue.^ M. Deschamps^ Las described a membrane, which is situate between the endocardium and the areolar tissue that lines the muscular structure at its inner surface, and belongs essentially to the elastic fibrous tissue. The tissue of the heart is supplied with blood by the cardiac or coro- nary arteries — the first division of the aorta ; and their blood is con- veyed back to the right auricle by the coronary veins. The nerves, which follow the ramifications of the coronary arteries, proceed chiefly from a plexus, formed by the spinal nerves and great sympathetic. Besides the large ganglia on the cardiac plexuses at the base of the organ, the nerves present minute ganglia along their course in its sub- stance ;^ and Dr. Eobert Lee^ has affirmed, that it can be clearly de- monstrated, that every artery distributed throughout the walls of the heart, and every muscular fasciculus of tlie organ, is supplied with nerves upon which ganglia are formed. The results of Dr. Lee's ob- servations, are not, however, considered by all to be established.* In both hearts, the auricles are much thinner and more capacious than the ventricles ; but they are themselves much alike in structure Fig. 98. Fig. 99. Anterior View of External Musoulnr Lnj'er of the Heart after removal of its Serous Coat, 1. Right anricle. 2. Descending vena cava. 3. Eiglit anterior pulmonary vein. 4. Horizontal band of flbre.s passing across the base of the auricles D. Left anterior pulmonary vein. 6. Muscular fibres between auricles. 7. Fringed or ring-shaped bauds of tibres at the extremity of left auricle. S. Muscu- lar fibres at the base of right auricle. !). Section of pulmonary artery, showing semilunar valves. 10, 11. Anterior bis-ventricular muscular fibres. 12, 13. Their continuation on to left ventricle. Posterior View of the same. 1. Right auricle. 2. Descending vena cava. 3. Right posterior pulmonary vein. 4. Muscu- lar fibres of left auricle. 5. Left posterior pul- monary vein. 6, 7. Arrangement of muscular fibres at the end of left auricle. 8. Orifice of great coronary vein. 9. Band of fibres between the two venje cavse. 10. Orifice of the ascend- ing vena cava ; Eustachian valve is at the end of the line. 11, 12. Muscular fibres at the base of auricle. 13, 14. Muscular fibres in the ven- tricles. and size. The observation, that the right ventricle is larger than the left, is as old as Hippocrates, and has been attempted to be accounted for in various ways. Some have ascribed it to original conformation ; ' KoUiker, Mikroskopische Anatomic, 2ter Band, s. 492, Leipzig, 1854; and Amer. edit, of his Manual of Human Histology, by Dr. Da Costa, p. 669, Philad., 1854. ^ Gazette Medicale de Paris, No. 10, and Encyclograpliie des Sciences Medicales, Avril, 1840, p. 281. 3 Remak, Kcilliker, op. cit. * Philcsophical Transactions, Part i. for 1849. * British and Foreign Medico-Chirurgical Review, p. 550, Oct. 1849. CIRCULATOEY APPAEATUS. 337 others to the bh:)od being cooled in its passage through the lurig, and therefore occupying a smaller space when it reaches the left side of the heart. Ilaller^ and MeckeP assert, that it is dependent upon the kind of death ; that if the right ventricle be usually more capacious, it is owing to the lung being one of the organs that yields first, thus occa- sioning accumulation of blood in the right cavities of the heart ; and they state that they succeeded, in their experiments, in rendering either one or the other of the ventricles more capacious, according as the cause of death arrested first the circulation in the lung or in the aorta; but the experiments of Legallois^ and Seiler,"* especially of the former, upon dogs, cats, Gruinea pigs, rabbits, the adult, the child, and the stillborn foetus, with mercury poured into the cavities, have shown that, except in the foetus, the right ventricle is more capacious, whether death has been produced by suffocation, in which the blood is accu- mulated in the right side of the heart, or by hemorrhage; and Legal- lois' thinks, that the difference is owing to the left ventricle being more muscular, and, therefore, returning more upon itself. The capa- city of each of the ventricles in the full-sized heart has been estimated at about two fluid ounces f but by Valentin^ at more than double, and by Volkmann more than treble that amount. The two hearts, united together by a median septum, form, then, one organ, which is situate in the middle of the chest, (see Fig. 79,) between the lungs, and, consequently, in the most fixed part of the thorax. Figure 100 is modified from one carefully made from nature by Dr. Penuock.^ It represents the normal position of the heai-t and great vessels. According to Carus,^ the weight of the heart compared with that of the body is as 1 to 160. M. J. Weber^° found the proportion, in one case, to be 1 to 150 ; Dr. Clendinning" that of the male to be 1 to 160; that of the female 1 to 150; and Lae'nnec considered the organ to be of a healthy size when equal to the fist of the individual. M. Cru- veilhier estimates the mean weight at six or seven ounces. M. Bouil- laud^^ weighed the hearts of thirteen subjects, in whom, from the gene- ral habit, previous state of health, and mode of death, there was every reason to believe that they were in the natural state. The mean was eight ounces and three drachms. From all his data he is led to fix the averan^e weis-ht of the heart, in the adult, from the 25th to the 60th year, at from 8 to 9 ounces. Dr. Clendinning carefully examined nearly four hundred hearts of persons of both sexes, and of all ages ' Element. PliysioL, iv. 3, 3. ^ Ilandbucli der Menschlichen Anatomie, Halle, 1817, s. 46 ; or the translation from the French version, by Dr. Doane, Philad., 1832. '■^ Diet, des Sciences Medicales, v. 440. * Art. Ilerz. in Pierer's Anat. Physiol. Real Worterh., iv. 32, Leix>z., 1821. 5 (Euvres, Paris, 1824. ^ Quain and Sharpey's edit, of Quain's Human Anatomy, Amer. edit., by Leidy, ii. 487, Philad., 1849. ■" Lehrbuch der Physiologie des Menschen, i. 415. * Medical Examiner, April 4, 1840. ^ Introduction to Comp. Anat., translated by R. T. Gore, Lond., 1827. '" Hildebrandt's llandbuch der Anatomie, von E. H. Weber, Braunschweig, 1831, Band. iii. s. 125. " Journal of the Statistical Society of London, July, 1838. '^ Traite Clinique des Maladies du Coeur, &c., Paris, 1835. VOL. I. — 22 338 CIECULATION. above puberty. The average weight was about nine ounces avoirdu- pois, — much less than that observed by Dr. John Eeid,^ who found Fiff. ]00. View of the Heart in situ. S. Outline of sternum. C, C. Clavicles. 1, 2, 3, 4, 5, 6, &c. Kib.s. 1', 2', 3', 4', 5', 6', &e. Cartilages of ribs. 4'. Right and left nipples, a. Right ventricle, h. Left ventricle, c. Septum between ventricles. d. Right auricle, e. Left auricle. /. Aorta. /'. Xeedle passing through aortic valves, g. Pulmonary artery, g'. Xeedle passing through valves of pulmonary artery, h. Vena cava descendens. i. Line of direction of mitral valve ; dotted portion posterior to the right ventricle, i. !Xeedle passed into mitral valve at its extreme left. k. Line of tricuspid valve, o. Trachea. the average weight of the male heart — of 89 weighed — to be 11 oz. and 1 dr. : and of the female heart — of 53 weighed — to be 9 oz. and J dr. The weight and dimensions of the organ, according to Lobstein and Bouillaud, are as follows: — Weight, 9 to 10 ounces; length from base to apex, 5 inches 6 lines; breadth at the base, 3 inches; thickness of walls of left ventricle, 7 lines ; do. at a finger's breadth above the apex, 4 lines ; thickness of walls of right ventricle, 2;^ lines ; do. at apex, \ a line; thickness of right auricle, 1 line; do. of left auricle, J a line. M. Bizot^ has given the following measurements, taking the average of males from 16 to 89 years. Base. Middle. Apex. Left ventricle 4^ lines 5^ 3| Right ventricle l{f If l^g ' Lond. and Edinb. Monthly Journal of Med. Science, April, 1843, p. 322. 2 For the results of M. Bizet's researches, to ascertain the dimensions of the heart and arteries, see Memoires de la Socit te M dicale d"Ol)servation, Paris, 1837 ; and Hope on the Diseases of the Heart, Amer. edit., by Dr. Pennock, p. 234, Philad., 1842. CIRCULATORY APPARATUS. 839 In the female, the average thickness is something less. Dr. Ranking^ has published the results of measurements, evidently made with accu- rac}^, of upwards of 100 hearts, — care being taken to exclude all those that exhibited any trace of organic change. The following are the mean admeasurements. Of 15 male hearts, the mean circumference was 9||ths inches; of 17 female hearts, 8i|ths inches. The mean length of the male heart was 4i|ths inches; of the female, 4||ths. The mean thickness of the left ventricle, in the male, was f gths of an inch; in the female, ffths; of the right ventricle, in the male, 4^gths ; in the female, /gths. The septum ventriculorum has, in the male, a mean thickness of ffths of an inch; in the female, ^gths. The aortic orifice, in the male, had a mean circumference of 2||ths inches; the right auriculo- ventricular orifice, 4|fths inches; the left auriculo- ven- tricular orifice, 3||ths inches. The corresponding parts of the female were relatively less. Dr. Ranking infei's, that the heart of the male is larger than that of the female, — that the length of the healthy heart is to its circumference rather less than 1 to 2, — that the thickness of the parietes of the right ventricle to the left is as 1 to 3 nearly: — that the pulmonary artery is slightly wider than the aorta; and, lastly, that the right auriculo- ventricular opening is considerably larger than the left. It need scarcely be said, that the weight and dimensions of the organ must vary according to the age, sex, &c., of the individual. M. Bizot^ found, that the influence of stature on its size was slight; and not such as might have been expected a pj-iori ; for, in individuals of the male sex above sixty inches, and in females above fifty-five inches, in height, the mean dimensions of the organ, especially its breadth, were less than in persons of a lower stature. He found the width of the shoulders furnish a better proportionate standard of its measurement, — the dis- tance between the acromial point of the clavicles, and the length and breadth of the heart increasing in a tolerably regular ratio. Numerous measurements of the organ have been made on children by MM. Rilliet and Barthez;^ whence it results: First. That its circumference does not augment in proportion to age. It is nearly the same from 15 months to five years and a half; and from the latter age it goes on increasing irregularly until puberty. Secondhj. The distance from the base to the apex is nearly one-half the total circumference at the base of the ven- tricles. Thirdly. The maximum thickness of the parietes of the right ventricle varies but little according to age. It is generally 0'078 Eng. inch to the age of six years; and after this from O'llS to 0"157. Fourthly. The maximum thickness of the left ventricle remains below 0'3yo Eng. inch, until six years of age. Later, it is habitually 0-893, or a little more. Fiftldy. The proportion between the thickness of the two ventricles is generally, as stated by ]\[. Guersant, as 3 to 1, or 4 tol, rather more than less. Sixthly. The maximum thickness of the septum is nearly the same as that of the left ventricle, a little more rather than less. Seventhly. The seat of the maximum thickness of the right ven- ' London Medical Gazette, No. xxir., 1842. * Miuioires de la Societe Medicale d'Observation de Paris, torn, lere, Paris, 1S36. ' Traite Cliniqiie et Pratique des Maladies des Eufauts, iii. GG2, Paris, lb43. 840 CIRCULATION. tricle is at the base, and near the auriculo-ventricular orifice ; that of the left ventricle one or two centimetres (in. O'SyS or 0'796) from the base; and that of the septum from two to three centimetres (in. 0.796 to 1"171). Eighihlij. The size of the right auriculo-ventricular orifice remains nearly the same until the age of 5 years ; it scarcely increases in size up to tlie age of 10 ; but then augments more manifestly. Ninthly. The left auriculo-ventricular orifice, which is always smaller than the right, increases a little more regularly than it with age, and frequently has the same dimensions as the distance from the base of the heart to its apex. Tenthhj. The aortic orifice presents but a slight augmentation from 15 months to 13 j^ears of age. Eleventhly. The pulmonary artery, on the other hand, increases notably from the age of six years to eight, so that although before this period it is equal to or scarcely greater than the aortic orifice, afterwards it is commonly much larger. They did not find any marked difl:ereuce between the male and female heart in children. The heart is surrounded by its proper capsule, called pericardhim. — a fibro-serous membrane, composed of two layers. The outermost of these is fibrous, semi-transparent, and inelastic; strongly resembling the dura mater in its texture. Its thickness is greater at the sides than below, where it rests upon the diaphragm ; or than above, w^here it passes along the great vessels which communicate with the heart. The inner layer is of a serous character, and lines the outer, giving the polish to its cardiac surface ; it is then reflected over the heart, and adheres to it by areolar substance. Like other serous membranes, it secretes a fluid, termed liquor pericardii^ to lubricate the surface of the heart. This fluid is always found in greater or less quantity after death; and a question has arisen as to the amount that should be con- sidered morbid. This must obviously vary according to circumstances. In the healthy condition, it is seldom above a tea-spoonful. When its quantity is augmented, the disease hydropericardium exists. Its great use probably is to keep the heart constantly moist by the exhalation effected from it; and, also, to restrain the movements of the organ, which, under the influence of the emotions, sometimes leaps inordi- nately. If the pericardium be divided in a living animal, the heart is found to bound, as it were, from its ordinary position; and hence the expression, — " leaping of the heart," — during emotion, is physiologi- cally accurate. b. Arteries. Arteries are solid, elastic tubes, which arise, by a single trunk, from the ventricle of each heart, and gradually divide and subdivide, until they are lost in the capillary system. The large artery, which arises from the left ventricle, and conducts the blood to every part of the bodjif, — even to the lungs, so far as regards their nutrition, — is the aorta; and that, which arises from the right ventricle and conveys venous blood to the lungs for aeration, is the pulmonary artery. Nei- ther the one nor the other is the continuation of the proper tissue of the ventricles ; the inner membrane is alone continuous — the muscu- lar structure of the heart being united to the fibrous coat of the arte- ries by means of an intermediate fibrous tissue. The aorta^ as soon CIRCULATORY APPARATUS. 341 as it quits tlie left ventricle, passes beneath the pulmonary artery, is entirely concealed by it, and ascends to form a curvature with the con- vexity upwards, the summit of which rises to within three quarters of an inch or an inch of the superior edge of the sternum. This great curvature is called the cross or arch of the aorta. The vessel then passes downwards, from the top of the thorax to nearly as far as the sacrum, Avhere it divides into two trunks, one of which proceeds to each lower extremity. In the whole of this course, it lies close to the spine, and gives off the various branches that convey arterial blood to the different parts of the body. Of the immense multitude of these ramifications an idea may be formed, when we reflect, that the finest pointed needle cannot be run into any part of the surface of the body, without blood — probably both arterial and venous — flowing. The larger arteries are situate deeply; and are thus remote from external injury. They communicate freely with each other, and their anasto- moses are more frequent as the arteries become smaller and forther from the heart. At their final terminations, they communicate with the veins and lymphatics. It has been a common, but questionable belief, that the branches of the aorta, when taken collectively, are of much greater capacity than the parent trunk, and that this excess goes on augmenting ; so that the ultimate divisions of an artery are of much greater capacity than the parent trunk. Hence, the arterial system has been considered to represent, in the aggregate, a cone, whose apex is at the heart, and base in the organs; but as all the minute arterial ramifications are not visible, it is obviously impracticable to discover the ratio between their united capacity and that of the aorta at its origin : yet the problem has been attempted. Keill, by experiments made on an injected sub- ject, considered it to be as 44:,607 to 1 : — J. C. A. Helvetius and Sylva as 500 to 1. Senac estimated, not their capacities but their diameters, and conceived the ratio of these to be as 118,490 to 90,000 ; and George Martine affirmed, that the calibre of a parent arterial trunk is equal to the cube root of the united diameters of the branches.^ It will be shown, however, hereafter, from the observations of M. Poiseuille and Mr. Ferneley, that the notion of the much greater capacity of the branches than of the parent trunk is a fallacy. The whole subject will be referred to in another place. The pulmonary artery strongly resembles the aorta. Its distribution has been already described as a part of the respiratory organs. The arteries are composed of different coats in superposition, respect- ing the number of which anatomists have not been entirely of accord. Some have admitted six ; others five; others four; but at the present day, three only are perhaps generally received ; — first, an external., areolar or cellular., called also nervous^ and cartilaginous by Yesalius, and tendinous by Ileister, which is formed of condensed areolar sub- stance, and has considerable strength and elasticity, so that if a ligature be applied tightly round the vessel, the middle and internal coats may be com|iletely cut through, whilst the outer coat may remain entire. Scarpa is not disposed to admit this as one of the coats. He considers ' Haller, Element. Pliysiolog., lib. ii., sect. 1, g 18, Lausan., 1757. 34:2 CIKCULATION. it only an exterior envelope, to retain the vessel in siiu. The next coat is the mitklle^ muscular or 'proi:)er coat, the character of which has been the subject of much discussion. It was, at one time, almost universally believed to be muscular. Such was the opinion of Mr. Hunter.^ Henle^ advances the opinion, that its structure is interme- diate between areolar and muscular tissue; its microscopic elements being broad and very flat, slightly granulated fibres or bands, which lie in rings around the internal membrane, and are about 0"003 lines in diameter. These with a system or network of dark streaks consti- tute the middle coat. In the large arteries, as the aorta and its main branches, nearly the whole thickness of this coat is composed of yel- low elastic tissue — the tissu jaune of the French anatomists: few mus- cular fibres are perceptible ; but in the smaller arteries the proportion- ate thickness of the elastic coat gradually diminishes; whilst, as a general rule, the muscular fibres increase in number, and form a layer within the elastic coat. Kolliker,^ indeed, affirms, that the middle tunic of the small arteries is purely muscular, without the slightest admixture of connective tissue and elastic elements. The muscular fibres resemble those of the intestinal tube, being of the nonstriped or nonstriated variety. They are arranged areolarly ; are pale and flat, and mingled with filaments of fine elastic tissue, Nysten,* Magendie,* and Mliller" applied the galvanic stimulus to the middle coat, which is the most sensible test of irritability, but without effect. It is proper, however, to remark, that the heart seems equally unsusceptible of the galvanic stimulus ; or at least is not affected by it like the voluntary muscles. In the cases of two exe- cuted criminals, which the author had an opportunity of observing, although all degi^ees of galvanism were applied half an hour after the drop fell, no motion whatever was perceptible ; yet the voluntary mus- cles contracted, and continued to do so for an hour and a half after execution. The same fact is recorded in the galvanic experiments of Dr. Ure, detailed in another part of this work, and is attested by Bichat, Treviranus and others. Humboldt, Pfaft", J, F, Meckel, Wedemeyer, and J, Miiller, however, affirm the contrary. The last observer states,^ that with a single pair of plates he excited con- tractions not only in a frog's heart, which had ceased to beat, but also in that of a dog, under similar circumstances. Into the subject of the cause of the heart's action, we shall, however, inquire presently. Miiller^ suggests, that in the capability to contract under the influence of cold, as exhibited in the experiments of Schwann, referred to here- after, the contractile tissue of the arteries resembles that of the dartos, ■ On the Blood, luflammatiou and Gunshot "Wounds; by Palmer, Amer. edit., p. 156, Philad., 1840. 2 Casper's Wochenschrift, May 23, 1840, cited in Brit, and For. Med. Rev., Oct. 1840, p. 551. * Mikroskopische Anatomic, 2ter Bd. s. 507, Leipz., 1854; or his Manual of Histo- logy, Sydenham Society edit., Lond., 1854; or Da Costa's Amer. edit, of the same, p. 679, Philad. ,1854. ^ Recherches de Physiologie, &c., p. 325, Paris, 1811. 5 Precis. 2de edit., ii. 387^ Paris, 1825. ^ Handbach der Physiologie, Baly's translation, p. 205, Lond., 1838. ^ Loc. cit. * Archiv. fur l8od, in Lond. Med. Gaz., May, 1837. CIRCULATORY APPARATUS. 343 and that found in many parts of tlie skin, as about the nipple and follicles, althougli the physical characters of the latter are so different from elastic tissue. The third or inner coat is smooth and polished, and a continuation of the membrane that lines the ventricles. It has an epithelial lining, resembles the serous membranes, and is lubricated by a form of serous exhalation.' The arteries receive the constituents that belong to every living part, — arteries, veins, lymphatics, and nerves. These arteries do not pro- ceed from the vessels they nourish, but from adjacent trunks, as we have remarked of the vasa vasorum^ to which class they really belong. The nerves proceed from the great sympathetic; form plexuses around the vessels, and accompany them through all their ramifications. By some anatomists, the arteries of the head, neck, thorax, and abdomen, are conceived to be supplied from the great sympathetic, whilst those of the extremities are supplied from the nerves of the spinal marrow. It is probable, however, that more accurate discrimination might trace the dispersion of twigs of the nerves of involuntary motion on all these vessels. The organization of the arteries renders them tousrh and ex- tremely elastic, both of which qualities are necessary to enable them to withstand the impulse of the blood sent from the heart, and to react upon the fluid so as to influence its course. It is by virtue of this structure, that the parietes retain their form in the dead body, — one of the points that distinguish them from the veins. The vitality of the arteries is inconsiderable. Hence their diseases are by no means numerous or frequent, — an important fact, seeing that their functions are essential, and their activity incessant. c. Intermediate^ Peripheral or Cajdllary System.. The capillary or intermediate vessels are of extreme minuteness, and are by some considered to be formed by the terminations of arteries and the commencement of veins; by others to be a distinct set of ves- sels. This system forms a plexus which is distributed over every part of the body, and constitutes, in the aggregate, what is meant by the capillary system. It admits of two great divisions, one situate at the termination of the branches given off from the aorta, and called the general capillary system ; the other at the termination of the branches of the pulmonary artery, — the 2^^'^^'>nonic capillary system. Although the capillary system of man does not admit of detection by the unaided sight, its existence is evidenced by the microscope; by injections, which develope it artificially in almost every organ ; by the application of excitants, and by inflammation. The parietes frequently cannot be distinguished from the substance of the tissues ;— -the colour of the blood, or the matter of the injection alone indicating their course. In some parts, as in the white textures, these vessels do not seem to admit the red particles of the blood, whilst others admit them always. This diversity gave rise to a distinction of the capillaries into red and ivkite; but there are probably none of the latter. It is difficult, indeed, to ' For some speculations as to the a£;ency of this secretion in the production of the buffy state of the blood, &c., see M. Kouiain Gcrardin, in Journal des Counaissances Mcdico-Chirurgicales, Mars, 183(3. BU CIRCULATION. conceive how the red particles could be arrested at tlie mouths of the white arteries — if such existed — without their preventing altogether the entrance of blood into them. The true cause of the whiteness appears to be the small quantity of blood they receive; and it is only when the network is very close, and the quantity of blood passing through them great, that a perceptible colour is produced. If a plate of red glass be reduced to a very thin pellicle, and be placed between the eye and light, its colour will be scarcely sensible. To perceive it, several of these pellicles must be placed over each other, and they must be ex- amined not by their transparency, but by causing the light to fall on their surface, or by reflection. There are certain textures, again, which receive no bloodvessels, — the corneous and epidermic, for example. They are probably nou- rished by transudation of nutritive matter from the vessels of the sur- rounding tissue. The ancients were of opinion, that arteries and veins are separated by an intermediate substance, consisting of a fluid effused from the blood, which they called, in consequence, parenchyma.^ The notion is, indeed, still entertained ; and is considered to be supported by micro- scopical observations. In the examination of delicate and transparent tissues, currents of moving globules are seen witli many spaces of ap- parently solid substances, resembling small islets, surrounded by an agitated fluid. If the tissue be irritated by thrusting a fine needle into Fig, 101. Circulation in the Web of the Frog's Foot. 1, 1. Veins. 2, 2. Arteries. it, the motion of the globules becomes more rapid; new currents arise where none wei^e previously perceptible, and the whole becomes a mass of moving particles, the general direction of which tends towards the points of irritation. But although a part of the apparatus of inter- ' Galen. Administrat. Anatom,, vi. 2. CIRCULATORY APPARATUS, 345 mediate circulation may be arranged, in this manner, there are reasons for the belief, that a more direct communication between the arteries and veins exists also. The substance of an injection passes from one set of vessels into the other, without any evidence of intermediate extravasa- tion. The blood has been seen, too, pass- ing in living animals, directly from the arteries into the veins. Leeuenhoek^ and Malpighi,^ on examining the swim-blad- ders, gills, and tails of fishes, the mesen- tery of frogs, &c. — which are transpa- rent, — observed this distinctly ; and the fact has been proved by the observations Portion of the Web of the Frog's Foot. of Cowper, Cheselden, Hales, Spallan- ^^{.^ ^Z^^ :i^;7:i^;X^ Zani, TllOmSOn, Cuvier, Configliachi, RUS- communicate, c, c. The angular unnu- coni, Dcillinger, Cams, and others. Fig. 103. cleated cells of the pai'enchyma. Circulation in the Under Surface of the Tongue of the Frog. sc, X. Venous branches uniting to form a principal vein, y. z, z. Folliclos into which a small artery- enters, whicli becomes convoluted before issuing from them. A beautiful capillary rete, and some muscular fibres are also seen. The artery and vein terminate in tAvo different ways; — at times, after the former has become extremely minute, by sending off numerous ' Select Works, containing his Microscopical Discoveries, by Samuel Hooke, p. 90, Lend., 1778. 2 Epist. do Pulmonibus, 1661, and Haller, Element. Physiol., lib. iii. sect. 3, § 20, Lausann., 1757. 346 CIRCULATION. lateral branches, as Haller states lie noticed in the swim bladders of fislies; at others, by proceeding parallel to each other, and communi- cating by a multitude of transverse branches. Fig. 101 exhibits a microscopic view of the membrane between two of the toes of the hind foot of the frog, Rana esculenta, magnified three diameters. Fig. 102 shows a portion of the web of a frog's foot magnified 45 diameters. The superficial network of capillaries is seen admitting but a single series of blood particles. All the vessels, here figured, are, according to Wagner,' furnished with distinct parietes. Fig. 103 is a beautiful representation of the circulation in the under surface of the tongue. Along the larger vessels the blood can be seen rushing with excessive velocity. It is proper, however, to state that the more the parts are magnified, the greater will be the apparent velocity. The mean real velocity, Valentin^ thinks, is one-eighth less in the capillaries than in the veins and arteries.-' These larger vessels have distinct coats ; but single files of globules are seen proceeding slowly through channels to which the author has not been able to satisfy himself that there were distinct parietes. The tongue of the frog offers by far the most satisfactory opportunity for distinctly wit- nessing the circulation ; a fact for the knowledge of which the author is indebted to M. Donne.'* Fia. 104. Fiff. 105. Capillary Network of Nervous Centres. Capillar}' Network of Fungiform Pa- pilla of the Tongue. The capillary vessels have been esteemed b}^ some to belong chiefly to the arteries, the venous radicles not arising almost imperceptibly from the capillary system, as the arteries terminate in it, but having a marked size at the part where they quit this system, which strikingly contrasts with the excessive tenuity of the capillary arterial vessels ; whilst between the capillary system and the arteries there is no distinct line of demarcation. The opinion of Bichat^ was, that this s^'stem is entirely independent of both arteries and veins; and Autenrieth* imagined, that the minute arteries unite to form trunks, which again divide before communicating with the veins, so as to represent a system analogous to that of the vena porta. The experiments of Dr. Marshall * Elements of Physiology, by R. Willis, Lond., 1842. * Lehrbuch der Fhysiologie des Menschen, i. 467, Braunschweig, 1844. 3 See also Lebert, Fhysiologie Fathologique, i. 7, Faris, 1845. * Cours de Microscopie, p. 109, Faris, 1844 ; and Atlas, planche vi., Faris, 1845. 6 Anatomic Generale, &c., edit, de MM. Blandiu et Mageudie, ii. 299, Faris, 1832. 8 Physiologic, ii. 13S. CIECULATORY APPARATUS. 847 llall^ on the batrachia, wliicTi were performed with signal care, led him to the following conclusions, which agree with those of Bichat, so far as regards the independent existence of a capillary system. The minute vessels, he says, may be considered arterial, so long as they continue to divide and subdivide into smaller and smaller branches. The minute veins are the vessels that gradually enlarge from the suc- cessive addition of small roots. The true capillary vessels are distinct from these. They do not become smaller by subdivision, or larger by conjunction, but are characterized by continual and successive union and division or anastomoses, whilst they retain a nearly uniform dia- meter. The last branches of the arterial system, and the first root of the venous, Dr. Hall remarks, may be deuoiiiinated minute, but the term " capillary" must be reserved for, and appropriated to, vessels of a distinct character and order, and of an intermediate station, carrying red globules, and perfectly visible by means of the microscope. Of late, M. Bourgery^ has maintained, that besides the interme- diate vessels, which form the direct communication between the arte- ries and veins, there is a special capillary arrangement in every tissue by which the functions of nutrition and secretion are accomplished. The diameter of these capillaries, according to M, Bourgery, is not more than one-half, one-third, or even one-fourth of that of the blood corpuscles ; and they can, consequently, convey only liquor sanguinis. But the existence of these vessels is not considered to be demonstrated ; whilst their absence in tissues — as cartilage — which they were formerly supposed to penetrate, has been established,^ The capillary arteries are distinct in structure — as they are in office — from the larger arteries. All the coats diminish in thickness and strength, as the tubes lessen in size; but this is more especially the case with the middle coat, which, according to Wedemeyer, may still be distinguished by its colour in the transverse section of any vessel whose calibre is not less than the tenth of a line ; but entirely disappears in vessels too small to receive the wave of blood in a mani- fest jet. While the coats diminish, the nervous filaments, distributed to them, increase ; the smaller and thinner the capillary, the greater the proportionate quantity of its nervous matter. The coats of the capillaries become successively thinner and thinner, and at length dis- appear altogether ; and the vessels — many of them at least — seem to terminate in membraneless canals or interstitial passages, formed in the substance of the tissues. The blood is contained — according- to O Wedemeyer, Gruithuisen, Dollinger, Cams, and others — in the differ- ent tissues in channels, which it forms in them: even under the micro- scope, the stream is seen to work out for itself, easily and rapidly, a new passage in the tissues, and it is esteemed certain, that in the figura venosa of the egg, the blood is not surrounded by vascular parietes. Most histologists of the day are disposed, however, to be- lieve, that the capillaries are provided with distinct coats. Such, as has been seen, appeared to Wagner to be the case in the frog's foot, ' A Critical and Experimental Essay on the Circulation, &o,, Lond., 1830; Amer. edit., Philad., 1835, ^ Comptes Rendus, &c., 1848, and Gazette Medicale, No. 37, 1848. * British and Foreign Medioo-Chirurgical Review, p. 527, Oct,, 1848. 3^8 CIECULATIOX. wlien magnified 45 diameters; and it has even been announced, that thej are composed of a fibrous structure, analogous to the muscular. Fig. 106. 1^ ^^:}^~P^^^^i* IT^^^^^ ^\\ ^c-- v./.^., . r\ Capillaries of the "Web of the Frog's Foot. 1. Deep venous trunk, composed of three principal branches, 2, 2, 2; and covered with a rete of smaller vessels. Fig. 106, from Wagner, exhibits the vascular rete and circulation of the web of the hind foot of a frog — Rana temjporaria — magnified 110 times: here the parietes are very distinct. In another figure in "Wagner, which represents a portion of a live newt, magnified 150 diameters, the capillaries are exceedingly delicate, and their Avails by no means as distinct. The arterial and venous trunks and the capil- laries that form the medium of communication between them are well seen, as well as the islets of the substance of the lung, in which a granular or areolar texture is indistinctly perceptible. Dr. Carpenter^ is of opinion, that the mode of origin of the capillaries refutes the supposition, that they are mere passages channeled out of the tissues through which they convey the blood. lie thinks there can be no doubt, that they are produced, in any newly forming tissue, not by the retirement of the cells, one from the other, so as to leave passages between them, but by the formation of communications among cer- tain cells, whose cavities become connected with each other, so -as to constitute a plexus of tubes, of which the original cell-walls become the parietes. Of the minute capillaries, — the diameter of which, in parts finely injected, varies from the yo'oo^^ ^^ the 4o'oo^^» ^^^ ^^^^ ^o'oo^^^ o^ ^^ inch and even more, — some, according to Wedemeyer, communicate Human Physiology, § 477, Lond., 1S42. CIKCULATOEY APPARATUS. 849 with veins ; in others, there are no visible openings or pores in the sides or ends, by which the blood can be extravasated preparatory to its being imbibed by the veins. There is nowhere apparent a sudden passage of the arterial into the venous stream; no abrupt boundary between the division of the two systems. The arterial streamlet winds through long routes before it assumes the nature, and takes the direc- tion, of a venous streamlet. The ultimate capillary rarely passes from a large arterial into a large venous branch. Many speculations have been indulged regarding the mode in which the vascular extre- mities of the capillary system are arranged. Bichat regarded it as a vast reservoir, whence originate, besides veins, vessels of a particular order, whose office it is to pour out, by their free extremity, the mate- rials of nutrition, — vessels, which had been previously imagined by Boerhaave, and are commonly known under the appellation of exlia- lants. Mascagni^ supposed that the iinal arterial terminations are pierced, towards their point of junction with the veins, by lateral pores, through which the secreted matters transude ; — but these points will farther engage attention under Nutrition and Secretion. d. Veiiis. The origin of the veins, like that of all capillary vessels, is imper- ceptible. By some they are regarded as continuous with the capillary arteries ; Malpighi^ and Leeuenhoek^ state this as the result of their microscopic observations on living animals; and it has been inferred, from the facility with which an injection passes from the arteries into the veins. According to others, cells exist between the arterial and the venous capillaries, in which the former deposit their fluid contents, and whence the latter obtain it. Others, again, substitute a spongy tissue for the cells. It has also been asked, — whether there may not be more delicate vessels communicating with their radicles, similar to the exhalants which are presumed to exist at the extremities of the arteries, and which are regarded as the agents of exhalation. All this is, however, conjectural. It has already been observed, that the me- senteric veins have been supposed by some to terminate by open mouths in the villi of the intestines ; and the same arrangement has been conceived to prevail with regard to other veins ; but there is no evidence of this. M. Eibes concludes, from the results of injecting the veins, that some of the venous capillaries are immediately conti- nuous with the minute arteries, whilst others open into the cells of the areolar tissue, and into the substance of different organs. When the veins become visible, they appear as an infinite number of extremely small tubes communicating very freely with each other; so as to form a very fine network. These vessels gradually become larger and less numerous, but still preserve their reticular arrangement; until, ultimately, all the veins of the body empty themselves into the heart by three trunks — the vena cava hiftrlor^ vena cava superior^ and coronary vein. The first of these receives the veins from the lower j^art of the ' Vasor. Lymph.. Corpor. Human. Histor., Sen. 1817; and Prodromo della Grande Anatomie, Firenz., 1819. ^ Secuuda Epistola de Pulmonibus, Opera, Loud., 16S7. 3 EpistoL 59, Opera, Lugd. Bat., 1722. 350 CIRCULATION". body, and extends from the fourth lumbar vertebra to the right auricle ; the second receives all those of the upper part of the body. It extends from the cartilage of the first rib to the right auricle. The coronary vein belongs to the heart exclusive- ly; between the superior and inferior cava a communication is formed by means of the vena azygos. Certain organs, as the spleen, ap- pear to be almost wholly composed of venous radicles. Fig. 107 repre- sents the ramifications of the splenic vein, in the substance of that organ; and if we consider, that the splenic artery has corresponding ramifica- tions, the viscus would seem to be almost wholly formed of bloodves- sels. The same may be said of the corpus cavernosum of the penis and clitoris, nipple, urethra, glans penis, &c. If an injection be thrown into one of the veins that issue from these different tissues, they are filled by the injection ; this rarely occurs, if the injection be forced into the artery. j\[. Magendie* affirms, that the communication of the cavernous tissue of the penis with the veins occurs through apertures two or three millimetres — in. 0*117 — in diameter. In their course towards the heart, particularly in the extremities, the veins are divided into two planes; — one subcutaneous or superficial; the other deep-seated, and accompanying the deep-seated arteries. Numerous anastomoses occur between these, especially when the veins become small, or are more distant from the heart. We find, that their disposition differs according to the organ. In the brain, they con- stitute, in great part, the pia mater; and enter the ventricles, where they contribute to the formation of the plexus choroides and tela cho- roidea. On leaving the organ we find them situate between the laminaa of the dura mater ; when they take the name of sinuses. In the spermatic cord, they are extremely tortuous ; anastomose repeatedly, and form the corpus paminn if orme ; around the vagina, they constitute the corpus retiforme ; in the uterus, the uterine sinuses. They have three coats in superposition, according to most anatomists; but many modern anatomists are disposed to assign them six. The outer coat is areolar; dense, and very difficult to rupture. The middle coat has been termed the proper membrane of the veins. The generality of anatomists describe it as composed of longitudinal fibres, which are more distinct in the vena cava inferior than in the vena cava superior; in the superficial veins than in the deep-seated; in the branches than Splenic Vein with its Branches and Ramifi- cations. 1. Trunk of the vein. 2. Gastric branch of this vein coming from the stomach. 3. Branches coming from the substance of the spleen. 4. Small mesenteric vein cut off. 5. Branches com- ing from external coat of the spleen. 6. Branches of lymphatic vessels of spleen. Precis, &c., ii. 238. CIRCULATORY APPARATUS. 851 in the trunks. M. Magendie^ states, that he has never been able to observe the fibres of the middle coat; but has always seen a multitude of filaments interlacing in all directions; and assuming the appearance of longitudinal fibres, when the vein is folded or wrinkled longitudi- nally, which is frequently the case in the large veins. It exhibited to him no signs of muscularity; even when the galvanic stimulus was applied ; yet M. Magendie suspected its chemical nature to be fibrinous. It was remarked, in an early part of this volume,^ that the bases of the areolar and muscular tissue are, respectively, gelatin, and fibrin ; and that the various resisting solids may all be brought to one or other of those tissues. The middle coat of the veins doubtless belongs essen- tially to the former, and is a variety of the iissn javne of the French anatomists. M. IMagendie merely states its fibrinous nature to be a suspicion; and, lii^e numerous suspicions, this may be devoid of founda- tion. Yet we have reason to believe, that it is contractile ; and, of late,^ it has been described as formed of one or two or even more layers be- tween the external and internal coats; these layers consisting of fibres, which agree, in all respects, with the white areolar tissue; and are either quite pure, or mixed in one or other of the layers with a greater or less amount of fibres, resembling those of the middle coat of the arteries in having the anatomical characters of the nonstriated or un- striped muscular fibres. The muscular fibre-cells are, however, much fewer in number, and are sometimes wanting. Kolliker'* says they do not exist in the uterine portion of the placenta, the veins of the cere- bral substance and pia mater; the sinuses of the dura mater; the veins of the bones; the venous sinuses of the corpora cavernosa of the male and female ; and probably in those of the spleen. M. Broussais^ affirms, that the contraction of the middle coat is one of the principal causes of the return of the blood to the heart. He conceives, that the alter- nate movements of contraction and relaxation are altogether similar to those of the heart ; but that they are so slight as not to have been rendered perceptible in the majority of the veins, although they are very visible in the vena cava of frogs, where it joins the right auricle. In some experiments by M. Sarlandi^re on the circulation, he observed these movements to be independent of those of the heart. After the organ was removed, and even after blood had ceased to flow,'' the con- traction and relaxation of the vein continued for many minutes in the cut extremity ; and it has been elsewhere remarked, that Mr. Wharton Jones had discovered in the veins of the bat's wing a regular rhythmi- cal contraction and dilatation. The inner coat is extremely thin and smooth at its inner surface, and has an epithelial lining. It is very extensible, and yet presents con- siderable resistance ; bearing a very tight ligature without being rup- tured. In many of the veins, parabolic folds of the inner coat exist, ' Op. cit., ii. 242. See on the researches of histologists, Mr. Paget, Brit, and For. Med. Review, July, 1842, ii. 242. ^ Page 59. ' Qiiain's Human Anatomy, by Quain and Sharpey, Amer. edit., by Leidy, i. 518, Philad., 1849. * Manual of Human Histology, Amer. edit., by Dr. Da Costa, p. 689, Philad., 1854. ' Op. citat., American trautilation, p. 391. ' See, on this subject, the remarks on the Circulation in the Veins. 352 CIRCULATION. like tliose in the lymphatics, which are inservient to a similar purpose; the free edge of these valves is directed towards the centre of the circulation, showing that their office is to permit the blood to flow in that direction, and prevent its retrogression. Thej do not seem, how- ever, in many cases, well adapted for the purpose ; inasmuch as their size is insufficient to obliterate the cavity of the vein. By most anato- mists, this arrangement is considered to depend upon primary organi- zation; but Bichat conceives it to be wholly owing to the state of con- traction, or dilatation of the veins, at the moment of death. M. Ma- gendie affirms, that he has never seen the distension of the veins exert any influence on the size of the valves; but that their shape is some- what modified by the state of contraction or dilatation ; and this he thinks probably misled Bichat.^ Moreover, they are covered by the epithelial coat and consist of tissue like that of fibrous membrane, which, as Mr. Hunter^ observed, shows, that they are not duplicatures of the lii;ing membrane. Their number varies in different veins. As a general rule, they are more numerous, where the blood proceeds against its gravity, or where the veins are very extensible, and receive but a feeble support from the circumambient parts, as in the extremi- ties. They are entirely wanting in the veins of the deep-seated vis- cera; in those of the brain and spinal marrow,'and of the lungs; in the vena porta, and in the veins of the kidneys, bladder, and uterus. They exist, however, in the spermatic veins; and, sometimes, in the internal mammary, and in the branches of the vena azygos. On the cardiac side of these valves, cavities or sinuses exist, which appear externally in the form of varices. These dilatations enable the refluent blood to catch the free edges of the valves, and thus depress them, so as to close the cavity of the vessel ; serving, in this respect, precisely the sanie functions as the sinuses of the pulmonary artery and aorta serve in regard to the semilunar valves. The valves exist in veins of less than a line in diameter. The three coats united form a solid vessel, — which, according to Bichat, is devoid of elasticit}', but in the opinion of M. Magendie^ is elastic in an eminent degree. The elasticity is certainly much less than in the arteries. The veins are nourished by vasa vasorum^ or by small arteries, that have their accompanying veins. Every vessel, indeed, in the body, if we may judge from analogy, draws its nutriment, not from the blood circulating in it, but from small arterial vessels, hence termed vasa vasorum. This applies not only to the veins, but to the The heart, for example, is not nourished by the fluid con- Fig. 108. Ditigrams showing Valves of Veins. A. Part of a vein laid open and spread out, with two pairs of valves. B. Longitu- dinal section of a vein, showing the apposi- tion of the edges of the valves in their closed state. C. Portion of a distended vein, ex- hibiting a swelling in the situation of a pair of valves. arteries. ■ Precis, &c., ii. Ml. 2 Trt^atise on the Blood, &c., by Palmer, Amer. edit., p. 216, Philad., 1840. ^ Precis, &c., ii. 243. CIRCULATORY APPARATUS. 853 stantlj passing tL rough it; but by vessels, wbich arise from the aorta, and are distributed over its surface, and in its intimate texture. The coronary arteries and their corresponding veins are, consequently, the vasa vasonmi of the heart. In like manner, the aorta and all its branches, as well as the veins, receive their vasa vasorum. There must, however, be a term to this ; and if our powers of observation were sufficient we ought to be able to discover a vessel, that must de- rive its support or nourishment exclusively from its own stores. The nerves that have been detected on the veins are branches of the great sympathetic. The capacity of the venous system is generally esteemed to be double that of the arterial. It is obvious, however, that we can only arrive Fig. 109. Fig. 110. r \ Roots, Trunk, and Divisions of the Vena Porta. 1, 1. Veins coming from intestines. 2. Trunk of vena porta. 3, 3. Branch- es distributed in the liver. Portal System. 1. Inferior mesenteric vein : traced by means of dotted lines beliind the pancreas (2) to terminate in splenic vein (3). 4. Spleen. 5. Gastric veins, opening into splenic vein. 6. Supe- rior mesenteric vein. 7. D(?scending portion of duodenum. 8. Its transverse portion vrhich is crossed by superiur mesen- teric vein and by a part of trunk of superior mesenteric artery. 9. Portal vein. 10. Hepatic artery. 11. Ductus communis cho- ledochus. 12. Divisions of duct and vessels at transverse fis- sure of liver. 13. Cystic duct leading to gall-bladder. at an approximation, and that not a very close one. The size and number of the veins are usually so much greater than those of the corresponding arteries, that when the vessels of a membranous part are injected, the veins are observed to form a plexus, and, in a great measure, to conceal the arteries; in the intestines, the number is more nearly equal. The difficulty of arriving at any exact conclusion re- garding the relative capacities of the two sj'stems is forcibly indicated VOL. I. — 23 854 CIRCULATION. by the fact, that whilst Borelli conceived the preponderance in favour of the veins to be as four to one, Sauvages estimated it at nine to four; Haller at sixteen to nine; and Keill at twentj-fivetonine.' The ratio between the capacity of individual arteries and veins is very different in different parts. Between the carotid and internal jugular it is as 196 to 441 ; the subclavian artery and vein, 3844 to 7396 ; the aorta and venaj cavse, 9 to 16; and between the splenic artery and vein, 136 to 676. There is one portion of the venous system, to which allusion has already been made, that is peculiar; — the ahdoininal venous or portal system. All the veins, that return from the digestive organs situate in the abdomen unite into a large trunk called vena j)orta. This, instead of passing into a larger vein — into the vena cava, for example — pro- ceeds to the liver, and ramifies, like an artery, in its substance. From the liver other veins, called supra-hepatic, arise, which empty themselves into the vena cava ; and correspond to the branches of the hepatic artery as w^ell as to those of the vena porta. The portal system is concerned only with the veins of the digestive organs situate in the abdomen; as the spleen, pancreas, stomach, intestines, and omenta. The veins of all the other abdominal organs, — of the kidney, suprarenal capsules, &c., are not connected with it. The first part of the vena portce is called, by some authors, vena jjorta ahdominalis sen ventralis to distinguish it from the hepatic portion, which is of great size, and has been called sinus of the vena porta. 2. BLOOD. It is not easy to ascertain the total quantity of blood circulating in both arteries and veins. Many attempts have been instituted for this purpose, but the statements are most diversified, partly owing to the erroneous direction followed by experimenters, but, still more, to the variation that must be perpetually occurring in the amount of fluid, according to age, sex, temperament, activity of secretion, &c. Harvey and the earlier experimenters formed their estimates by opening the veins and arteries freely on a living animal, collecting the blood that flowed, and comparing this with the weight of the body. The plan is, however, objectionable, as the whole of the blood can never be ob- tained in this manner, and the proportion discharged varies in differ- ent animals and circumstances. By this method, Moulins found the proportion in a sheep to be o'^d; King, in a lamb, 2^0^^) ^"^ ^ duck, ■g'gth ; and in a rabbit 3'oth. From these and other observations, Harvey concluded, that the weight of the blood of an animal is to that of the whole animal as 1 to 20. Drelincourt, however, found the pro- portion in a hog to be nearly -,-'-oth; and Moor, y'oth.^ Sir George Lefevre^ cites from Wrisberg, that from a plethoric young woman, who was beheaded, 25 pounds [?] of blood were collected ; and some recent experiments by Mr. Wanner* led to the following results : A bullock, weighing 1659 pounds imperial, yielded 69 pounds of blood, ' Elemeuta Physiologiae, lib. ii., sect. 2, § 10, Lausauu,, 1757. 2 Haller, op. cit., lib. v. sect. 1, § 2. 3 All Apology for tlio Nerves, p. 30, London, 1844. * Etliuburgli MeJ. and Surg. Juuru., July, 1845. BLOOD. 855 or in the ratio of 1 to 23*81 ; another weighing 1640 pounds, yielded 65 pounds, or in the ratio of 1 to 28*73 ; a cow, weighing 1298 pounds, yielded 59 pounds, or as 1 to 21*77; a sheep, weighing 110 pounds, yielded 5| pounds, or in the proportion of 1 to 22*72 ; another weigh- ing 88 pounds, yielded -A*-! pounds, or as 1 to 20 ; and in a rabbit, the proportion was as 1 to 25 exactly. An animal, according to Sir Astley Cooper,^ generally expires, as soon as blood, equal to about ^'gth of the weight of the body, is ab- stracted. Thus, if it weighs sixteen ounces, the loss of an ounce of blood will be sufficient to destroy it ; and, on examining the body, blood will still be found — in the small vessels especially — even although every facility may have been afforded for draining them. Experiments have, however, shown that no fixed proportion of the circulating fluid can be indicated as necessary for the maintenance of life. In the experiments of Rosa, asphyxia occurred in young calves when from three to six pounds, or from g'^d to o'gth of their weight, had been abstracted; but in older ones not until they had lost from twelve to sixteen pounds, or from j',th to ^th of their weight. In a lamb, asphyxia supervened on a loss of twenty-eight ounces, or ^'gth of its weight; and in a wether, on a loss of sixty-one ounces, or o'gd of its weight. Dr. Blundell^ found that some dogs died after losing- nine ounces, or -g'jjth of their weight; whilst others withstood the ab- straction of a pound, or y'^th of their weight ; and M. Piorry affirms, that dogs can bear the loss of -g'sth of their weight, but if a few ounces more be drawn they succumb. From all the experiments and obser- vations, Burdach^ concludes, that, on the average, death occurs when fths, or |ths, of the mass of blood is lost, although he has observed it in many cases, as in hasmoptysis, on the loss of ^th, and even of |th. The following table exhibits the computations of different physiolo- gists regarding the weight of the circulating fluid — arterial and venous. lbs. I lbs. Harvey, "1 Lister, 1 Moulins, j Abildguard, J Blumeubacli, "| Lobb, y . Lower, J Sprengel, Giinther and Bock, Weber and Lehmann, . 17^ to 19 Miiller, Burdacli and P. Berard, 20 Wagner, . . . 20 to 25 . 27 28 28 to 30 . 40 . 80 . 100 . 10 Quesnai, F. Hoflmann, Haller, . 10 to 15 15 to 20 Young, . Hambereter, Keill, \ Although the absolute estimate of Hoffmann has been regarded as below the truth, the proportion has seemed to many to be nearly accurate; but it is evidently too high. He conceives, that th^ weight of the blood is to that of the whole body as 1 to 5. Accordingly, an individual weighing one hundred and fifty pounds, will have about thirty pounds of blood;' one of two hundred pounds, forty; and so on. Of this, one-third is supposed to be contained in the arteries, and two-thirds in the veins. The estimate of Haller^ is, perhaps, near the ' Principles and Practice of Surgery, p. 33, Lee's edition, Lond., 1836. ^ Researelies, Physiological and Pathological, pp. "nne, . _ 3i''o *" uAff Jurin and Gulliver, ....... ^c'lff Blumenbach and Senac ...... s^'^tj I'-^'jor, se^n-ij Milne Edwards, jts'ojt Wagner ^^V,, Kater, >,' pv to Prevost and Dumas, -^i, Haller, Wollaston and Weber, .... Young, isss ""^ 55 as ^offir The blood of different animals is found to differ greatly in the rela- tive quantity of the red corpuscles it contains, the number seeming to bear a pretty exact ratio with the temperature of the animal. The higher the natural temperature, the greater the proportion of corpus- cles; arterial always containing a much greater proportion than ve- nous blood. In the greater part of the mammalia they have the same shape as those of man; but their size varies greatly iu different fami- lies. It would appear, from the researches of Mandl,' that of the mammalia the elephant has the largest, (y^fith of a millimetre,) and the ruminantia the smallest; that the family of camels is the only one, whose corpuscles are not round like those of the other mammalia, but ' Manuel d'Anatomie Generale, p. 248, Paris, 1843. For numerous admeasurements of the red corpuscles of the blood of man and animals, see Note by Mr. Gulliver to Hewson's Works, Sydenham Society's edit., p. 237, Lond., 184(i. BLOOD — RED CORPUSCLES. 363 Fig. 112. elliptical like those of birds, reptiles, and fishes,^ In all oviparous vertebrata, without any known ex- ception, the red corpuscles are oval. The chemical constitution of the blood corpuscles is not definitely settled. Two proximate principles have been discovered in them — hematin or hematosiyi, and ghlm- lin, — hemaioglohulin of Simon. The former, as mentioned hereafter, is the colouring matter. The latter, which differs from the globulin of Laennec, — an impure hematin mingled with some albumen, — is the main constituent of the globules, and is the same as the hlood-casein of Simon. It has not been separated ; but is presumed to differ but little in its properties from protein. It has been supposed that the red corpuscles are formed originally in the germinal membrane of the embryo : but, throughout the re- mainder of existence, in the blood from the chyle. Their origin is, however, by no means settled. Normally, they are not found outside the vessels ; and are manifestly, therefore, not inservient to nutrition ; but connected, in all probability, as shown elsewhere, with respiration Blood Corpuscles of Rana Esculenta. — Mag- nified 400 diameters. 1, 1, 1, 2 Blood corpuscles. 2. Seen edgewise. 3. Lymph corpuscle. 4. Altered by dilute acetic acid. Fig. 113. Fig. 114. ^^' (1) Red corpuscles of Pigeon's Blood, magnified 400 diameters. A. Red particles unaltered, with two or three colourless par- ticles. B. Treated with acetic acid, which develops the cell- wall and nucleus more clearly. Red Corpuscle of Fishes. a. Lamprey. 6. Skate. — After Whar- ton Junes. and calorification. It is not determined whether they are capable of reproduction, or possess independent life. Dr. Carpenter'^ thinks, that there can be no reasonable doubt, that they are to be regarded as nucleated cells, conformable in general character with the isolated cells that constitute the whole of the simplest plants; having each an independent life, and therefore the power of reproduction. Such too, is the view of Dr. Martin Barry and other microscopists. Wagner, Gulliver, and others,^ from observation of the blood of the batrachia, ascribe their origin to the colourless corpuscles to be mentioned pre- sently, which, they consider, become red blood corpuscles when fully developed ; whilst Dr. Carpenter strenuously maintained, that there is an entire functional as well as structural difterence between the red Op. citat., and Annales cles Sciences Natnrelles, 1824 and 182,5. Principlf-s of Human Physiology, 2il edit., p. 400, Loinlon, 1^44. V. Bruns, Lehrbuch dor Allgemeiuen Auatomie, s. 140, Braunschweig, 1841. 364: CIRCULATION. and the colourless corpuscles of the blood of vertebrata; but since then his views have undergone an entire change.^ Observations by Dr. G. O. Rees^ led him to infer, that they multiply by division. On ex- amining a portion of blood, kept at about its natural temperature, he observed the corpuscles assume an hour-glass form, which, increasing, eventually divided each corpuscle into two unequal-sized circular bodies. These, when treated with a strong saline solution, underwent the same exosmotic changes as are observed in common blood cor- puscles. In addition to the red, ivldte corjnisclcs are observed in the blood. These were noticed by Prof. Muller in that of frogs ; and by M. MandP in that of the mammalia. They are small, colourless corpuscles, finely granulated; insoluble in water, and strongly refracting light. Accord- ing to Mandl, they may be separated into two species, — some round, and containing two or three granules, which become more Fig. 115. evident when they are treated with acetic acid : these are ^o^ the true lymph corpuscles, described already (p. 245); the ^^ others, generally also round ; sometimes oblong ; and at A^ A others irregular ; the edges slightly notched ; and the sur- \^ ^) face finely granulated. They appear to be composed of a multitude of small molecules, from yj^'g^th to yg'gj^th of a ^^^''^1 ^'^^} millimetre in diameter : some are also found single. These the Blood, corpuscles are seen forming under the microscope, when blood, placed between two glasses, is attentively examined. They are, in Mandl's opinion, produced b}^ the coagulation of fibrin, and hence are called by him Jibrinoxs glolmks. More recently, how- ever, he has abandoned this name, "because it rests on a chemical character, that requires confirmation; and because it is not drawn from anatomical characters, which ought chiefly to fix the attention of the microscopist." He now terms them white rjranulattd corpuscles.*' These are the f/Iolnlins of M. Donne, and are considered by him^ as well as by M. Bernard,^ to be the first elements of blood corpuscles. The white cor[)uscles are much less numerous than the red. In health the proportion has been stated as 1 to 50; but in disease often as high as 1 to 10.^ Accurate observations, however, by Welcker* and Moleschott^ make the proportion much smaller. In Welcker's own blood, it was as 1 to 341, Moleschott's observations made it I to 357; or about 2'8 parts in the 1000; and Donders and K6lliker^° appear to agree with him. In certain morbid conditions, especially of the spleen and other vascular glands, an unusual number of colourless corpuscles is observed in the blood; along with a marked diminution of the red ' Principles of Human Physiology, Amer. edit., p. 178, Philad., 1855. 2 Gulstonian Lecture ; see Ranking, Half- Yearly Abstract, Jan. and July, 1845, Amer. edit., p. 251. ^ Grazette M 'dicale, 1837 ; and Manuel d'Anatomie Gen6rale, p. 252, Paris, 1S43. * Manuel d'Anatomie Gen/rale, p. 554, Paris, 1843. ^ Cours de Microscopie, p. 86, Paris, 1845. 6 W. F. Atlee, Notes on M. Bernard's Lectures on the Blood, p. 38. Philad., 1854. '' Kirkes and Paget, Manual of Physiology, 2d Amer. edit., p. 52, Philad., 1853. ^ Prager Vierteljahrschrift, iv. 11, in Canstatt, Jahresbericht, 1854, i. 44 and 1G5. ^ Wiener Wochenschrift, No. 8, in Canstatt, op. cit., S. 44. '" Mikroskopische Anatomie, ii. 577, Leipzig, 1854; and Manual of Histology, Syden- ham Society's edit. ; or Amer. edit., by Dr. Da Costa, p. 708, Philad., 1854. BLOOD — WHITE CORPUSCLES. 865 corpuscles, and an increase of the ratio of fibrin. To this condition Professor Bennett, of Edinburgh, gives the name leucocytha^mia.^ Dr. Barry and Mr. Addison think, that the colourless corpuscles, — which have generally been regarded as lymph corpuscles, — are formed from the central portion of the blood corpuscle^: they consider them to hold an intermediate position between the true red corpuscles, and the greatly modified forms of corpuscles, which, in their view, are the basis of the tissues, as well as of pus and other globules. The most probable opinion, however, is that the white corpuscles of the blood are identical with the lymph and chyle corpuscles; and all, in the opinion of Dr. Carpenter,"^ are connected with the elaboration of plastic fibrin, which must be constantly dravvn oft" by the nutritive processes, and therefore require to be reproduced. His arguments on this head are certainly forcible. It was first observed by Wagner,^ that whilst the colourless corpuscles are met with in the nutritious fluids of all animals that possess a distinct circulation, red corpuscles are restricted to the vertebrata. The truth of this has been confirmed by Dr. Carpenter, who infers from it, that the function of the colourless corpuscles must be of a general character, and intimately connected with the nutritious properties of the circulating fluid ; whilst that of the red corpuscles must be of a limited character, being only required in one division of the animal kingdom. One of the strongest arguments, however, in favour of the function of the white corpuscles mentioned above, is the connexion between the generation of white corpuscles in the blood, and the production of fibrin in the inflammatory process. This in- crease is evidently the result of the local inflammation, and is observed to commence before the occurrence of any constitutional phenomena. The microscopic observations of Messrs. Addison," Williams,^ Gulliver, and others, have established, that a great accumulation of white cor- puscles takes place in the vessels of an inflamed part, — partly owing to an attraction of the corpuscles towards the seat of inflammation, and partly, they were satisfied, by an actual reproduction of fresh corpuscles, which must have been owing either to their own power of generating themselves, or to some change in the blastema or fluid of circulation in the part, which favoured a more abundant production. Dr. Carpenter was a believer in the first mode of production ; and certainly his view, that the formation of fibrin in the blood is closely connected with the developement of white corpuscles, had strong arguments in its favour; but he does not now urge that the fibrin is formed by them. ISIessrs. Kirkes and Paget^ are firm believers in the developement of the human lymph or chyle corpuscle into the red corpuscle, — a view which appears to be the most philosophical from the phenomena recorded by difterent observers. Mr. Lane, for example, found the ruddy colour of the horse's chyle due to the presence of red corpuscles ; and he and Mr. Ancell ob- served imperfect blood corpuscles in the large lymphatics, and ascribed ' Edinb. Monthly Journ. of Med. Science, for 1851 ; and his work on Lencocythaemia, Edinb., 1851. 2 Op. cit., 2d edit., p. 506, Lond., 1844. 3 Op. cit. * Med. Gazette, Dec, 1840; Jan. and March, 1841. ^ Principles of Medicine, Anier. edit., by Dr. Clymer, pp. 214, 215, P lilad., 1844. 8 Manual of Physiology, 2d Amer. edit., p. 6G, Philad., 1853. 366 CIRCULATION. Developement of Human Lymph and Chyle Corpuscles into Red Corpuscles of Blood. A. A lymph or white blood-corpuscle. B. The same, in pro- cess of conversion into a red corpuscle, c. A lymph corpuscle, with the cell-wall raised up round it by the action of water. D. A lymph corpuscle, from which the granules have almost all disappeared, e. A lymph corpuscle, acquiring colour : a .single granule, like a nucleus, remains. i\ A red corpuscle, fully developed. the ro.se-colour of the lymph to them. Tlie thoracic duct of the horse, according to Mr. Gulliver/ often appears as a coloured tube from the number of these corpuscles in the chyle, which he gene- rally found to be smaller, more irregular and less per- fect in shape than the red corpuscles in the blood. Schultz and Gurlt^ also no- ticed the chyle of a reddish colour from the presence of blood corpuscles, of which they suppose, with Simon of Berlin,^ the formation to begin in the chyle ; and Mr. Gulliver adds, that the tran- sition of the corpuscles of the chyle or lymph into the red corpuscles of the blood, seems now to be commonly admitted in Germany; and, lono- ao-o, Mr. Hewson'' thought "it could not be denied," that the office of the thymus and lymphatic glands is to form the central particles found in the red corpuscles. It has been long observed, that crystals might form in blood,* but only recently has the subject attracted much attention; and especially since they were depicted, and investigated, by Dr.'^Otto Funke;^ who affirmed, that " the organic coloured matters, which form the essential contents of the red corpuscles" can assume, under special circumstances, the crystalline form ; and that the contents of the corpuscles, in each kind of blood have a constantly characteristic crystalline form. The essential condition for the crystallization of this hematocnjstaUin, as it has been called by Lehmann,^ or hemaioicUn^ is that it should be freed from the cells. In fishes, however, he has observed it crystallize within the cells. The crystals have a different shape in different animals, and they would seem to be a crystallization of the protein or albuminoid contents of the corpuscles ; but nothing definite has as yet been esta- blished in regard to them. When blood is drawn from a vessel, and left to itself, it exhales, so lonw. Ixiv., 105. * Tiedemann und Treviranus, Zeitschrift fiir Physiologie, B. v. H. i. ; cited in Bri- tish and Foreign Med. Review, No. 0, p. 590, April, 1836. ^ Op. cit., p. 329. "* Annales de Chimie et de Pliysi(iue, Nov., 1837, and page 318, of this volume. 368 CIRCULATION. bonic acid, arterial blood contains more than venous; and lie accounts for the failure of those, who have attempted to elicit carbonic acid from venous blood by the air-pump, to the air in the receiver not hav- ing been sufficiently rarefied. Prof. C. A. Schultz, of Berlin — who believes, that the vesicles of the blood, in a perfect state, are composed of a membranous covering, whose interior is filled with an aeriform fluid in the midst of which is found the nucleus^ — succeeded in so evident a manner by the following simple method in extracting air from the blood, " that it is impossible to doubt there exists a great quantity of air in the vesicles." He completely filled a bottle with warm blood flowing immediately from the vein of a horse, and her- metically sealed the bottle so that the cork was plunged into the blood, thus absolutely preventing the contact of air. The blood, on cooling, diminished in volume, and thus produced a perfect vacuum in the upper part of the bottle; and in proportion as this took place, bubbles of air arose from the blood and filled the vacuum. Chemical analysis of this air demonstrated that it was carbonic acid. In arterial blood, he found oxygen mixed with more or less carbonic acid.^ The experiments of Dr. Stevens,^ and of Dr. Robert E. Rogers,"' also show, that carbonic acid is contained in the blood. The latter observer found, when a portion of venous blood was placed in a bag of some membrane, and the bag was immersed in an atmosphere of gas — as of oxygen, hydrogen, or nitrogen — that carbonic acid, was pretty freely evolved.* Whilst the blood is circulating in the vessels, it consists of liquor sangvinis and red corpuscles; but during coagulation it separates into two distinct portions; — a yellowish liquid, called serum; and a red solid, known by the name of clot^ cruor, crassamentvm^ coagnhim, lyla- centcij insula and Jiepar sanguinis. The proportion of the serum to the crassamentum varies greatly in different animals, and in the same ani- mal at different times, according to the state of the system. The latter is more abundant in healthy vigorous animals, than in those that have been impoverished by depletion, low living, or disease. Sir Charles Scudamore found, by taking the mean of twelve experiments, that the crassamentum amounted to 53'307 per cent, in healthy blood. The difference between living and coagulated blood maj^ be expressed in a tabular form as follows: — • w The serum is viscous, transparent, of a slightly yellowish hue, and alkaline owing to the presence of a little free soda. Its smell and taste resemble those of the blood. Its average specific gravitj^ has been ■ Water, ■ o Various salts, Liquor Sanguinis, ■ Fatty matters, Serum, e^ Extractive do. 5' Albumen, ■ a> Fibrin. W ■ Crassamentum, o" Red Corpuscles, J 1 J P- ' London Lancet, Aucrust 10, 1839, p. 713. ^ jiji^.^ p. 714. 3 Philos. Transact., for 1834-5, p. 334. * American Journal of the iled. Sciences, August, 1836, p. 283. * See, on all this subject, Dr. John Reid, art. Respiration, Cyclop, of Anat. and Physiol., Pt. xxxii. p. 359, Lond., August, 1S4S. BLOOD — SERUM. 369 estimated at about 1-027 ; but on this point, also, observers differ. Dr. Jolin Davy' found it to vary from 1-020 to 1-031. Martine, Muschen- broek, Jurin, and Haller, from 1*022 to 1*037; Berzelius and Wagner,* from 1*027 to 1*029; Dr. Christison,^ from 1*029 to 1*031; Lauer," from 1*009 to 1*011 ; whilst Mr. Thackrali* found the extremes to be 1*001 and 1*080. At 158^^ of Fahrenheit, it coagulates; forming at the same time, numerous cells, containing a fluid, which oozes out from the coagulum of the serum, and is called serosity. It contains, accord- ing to Dr. Bostock, about g'^th of its weight of animal matter, to- gether with a little chloride of sodi um. Of this animal matter, a portion is albumen, which may be readily coagulated by means of galvanism; but a small quantity of some other principle is present, which differs from albumen and gelatin, and to which Dr. Marcet** gave the name muco-extractive matter^ and Dr..Bostock,^ uncoagidable matter of the blood — as a term expressive of its most characteristic property. Serum pre- serves its property of coagulating, even when largely diluted with water. According to Mr. Brande,^ it is almost pure liquid albumen, united with soda which keeps it fluid. Consequently, he affirms, any reagent, that takes away the soda, produces coagulation; and by the agency of caloi'ic, the soda may transform a part of the albumen into mucus. The action of the galvanic pile coagulates the serum, and forms glo- bules in it analogous to those of the blood. From the analysis of serum, by Berzelius,^ it appears to consist, in 1000 parts; — of water, 903; albumen, 80; substances soluble in alco- hol, — as lactate of soda and extractive matter, chlorides of sodium and potassium, 10; substances soluble in water, — as soda and animal matter, and phosphate of soda, 4; loss, 3. Dr. Marcet assigns it the following composition: — water, 900 parts; albumen, 86*8 ; chlorides of potassium and sodium, &Q ; muco-extractive matter, -l; carbonate of soda, 1*65 ; sulphate of potassa, 0-35, and earthy phosphates, 0*60 ; — a result, which closely corresponds with that of Berzelius, who states that the extractive matter of Dr. Marcet is lactate of soda, united with animal matter. According to M. Lecanu,^° 1000 parts contain, — water, 906 parts ; albumen, 78 ; animal matter, soluble in water and alcohol, 1*69 ; albumen combined with soda, 2*10 ; crystallizable fatty matter, 1*20; oily matter — seroUn^ 1; chlorides of sodium and potassium, 6; subcarbonate and phosphate of soda, and sulphate of potassa, 2*10 ; phosphate of lime, magnesia and iron, with subcarbonate of lime and magnesia, 0*91 ; loss, 1, A more recent analysis by Scherer," gives the following constituents : — • ' Researches, Physiological and Anatomical, Amer. Med. Lib. edit., p. 11, Philad., 1840. 2 Elements of Physiology, by R. Willis, ? 103, Lond., 1842. " On Granular Degeneration of the Kidneys, p. (Jl, Lend., 1S39 ; or American Medical Library edition, Philad., 1839. * Hecker's Annalen, xviii. 393. ^ Inquiry into the Nature and Properties of the Blood, &c., Lond., 1819. ^ Medico-Cliirurg. Transact., ii. 3«4. '' Op. cit., p. 292. « Plulosoph. Transact, for 1809, p. 373. ' Medico-Chirurg. Transactions, iii. 231. '" Journal de Pharmacie, xvii. ; and Annales de Chimie, kc, xlviii. 308. .' Canstatt and Eisenmann's .Jahresbericht liber die Fortscliritte in der Biologic im Jahre, 1848, s. 65, Erlangen, 1849. VOL. 1. — 21 370 CIRCULATION. Water ....... 910-45 Solid parts ...... 89.55 1000. Albumen ....... 7-4"15 Extractive matters ..... 5*96 Salts soluble in water ..... 8-75 Occasiouall}^, the serum presents a wliitisli hue, ^ybicll has given rise to the opinion that it contains chyle ; but it would seem that this is fatty matter, and is always present. In the serum of the blood of spirit-drinkers, Dr. Traill found a considerable portion, Avhich has been considered to favour the notion, that the human body may, by intem- perance, become preternaturally combustible ; and has been used to account for some of the strange cases of sjjontaneous combustion, or rather o1 preternatural comhustihility, whicli are on record. Dr. Christi- son has likewise met with fat mechanically diffused through the serum, like oil in an emulsion. On one occasion, he procured five per cent, of fat from milky serum, and one per cent, from serum which had the aspect of whey.^ The crassamentum or dot is a solid mass, of a reddish-brown colour, which, when geatly washed for some time under a small stream of water, separates into two portions, — colouring matter and fibrin. As soon as the blood is drawn from a vessel, the colouring matter of the red corpuscles leaves the central nucleus free ; these then unite, as we have seen, and form a network, containing some of the colouring mat- ter, and many whole corpuscles. By washing the clot in cold water, the free colouring matter and the globules can be removed, and the fibrin will alone remain. "When freed from the colouring matter, the fibrin is solid, whitish, insipid, inodorous, heavier than water, and with- out action on vegetable colours ; clastic when moist, and becoming brittle by desiccation. It yields, on distillation, much carbonate of ammonia, and a bulky coal, the ashes of which contain a considerable quantity of phosphate of lime, a little phosphate of magnesia, carbonate of lime, and carbonate of soda. One hundred parts of fibrin, according to Ber- zelius, consist of carbon, 58-360 ; oxygen, 19*685 ; hydrogen, 7"021 ; nitrogen, 19*934. Fibrin has been designated by various names: it is the gluten, coagulable lymph, and Jibre of the blood, of different writers. Its specific gravity is said to be greater than that of serum ; but the difference has not been accurately estimated, and cannot be great. The red corpuscles are manifestly, however, heavier than either, as we find them subsiding during coagulationto the lower surface of the clot, when the blood has flowed freely from the orifice in the vein. Fibrin is an important constituent of the blood. It exists in animals in which the red corpuscles are absent, and a form of it — syntonin — is the basis of muscular tissue. The colouring matter of the blood, called, by some, cniorin, hematin, hematosvi, zoo-hematin, Jiemachroin, globulin (of Lecanu), and rubrin, has been the subject of anxious investigation with the analytical chemist. It has been already remarked, that it resides in distinct particles or corpuscles, and in the fluid within the enveloping membrane. For- ' Edinb. Med. and Surg. Journal, xvii. 235, and xxxiii. 274. BLOOD — COLOURING MATTER. 371 merly, however, the opinion was universal, that the vesicular envelope is the seat of colour. The colouring principle is dissolved, by pure water, acids, alkalies, and alcohol. M. EaspaiP asserts, that the cor- puscles are entirely soluble in pure water, but MM. Donne and Boudet, who repeated his experiments, declare that they are wholly insoluble, and Muller^ is of the same opinion. Great uncertainty has always existed regarding the cause of the colour of the corpuscles. As soon as the blood was found to contain iron, the peroxide of which has a red hue, their colour was ascribed to the presence of that metal. MM. Fourcroy and Vauquelin-'' held this opinion, conceiving the iron to be in the state of subphosphate ; and they affirmed, that if this salt be dissolved in serum by means of an alkali, the colour of the solution is exactly like that of the blood. Berzelius,** however, showed, that the subphosphate of iron cannot be dissolved in serum by means of an alkali, except in very minute quantity ; and that this salt, even when rendered soluble by phosphoric acid, communicates a tint quite difi'er- ent from that of the red corpuscles. He found, that the ashes of the colouring matter always yield oxide of iron in the proportion of 200^^ of the original mass ; whence it was inferred, that iron is somehow or other concerned in the production of the colour ; but the experiments of Berzelius did not indicate the state in which that metal exists in the blood. He could not detect it by any of the liquid tests. The views of Berzelius, and the experiments on which they were founded, were not supported by the researches of Mr. Brande.^ He endeavoured to show, that the colour of the blood does not depend upon iron; for he found the indications of the presence of that metal as considerable in the parts of the blood that are devoid of colour, as in the corpuscles themselves; and in each it was present in such small quantity, that no eft'ect, as a colouring agent, could be expected from it. He supposed that the tint of the red corpuscles is produced by a peculiar, animal colouring principle, capable of combining with me- tallic oxides. Pie succeeded in obtaining a compound of the colouring matter of the blood with the oxide of tin : but its best precipitants are the nitrate of mercury and corrosive sublimate. Woollen cloths, im- pregnated with either of these compounds, and dipped in an aqueous solution of the colouring matter, acquire a permanent red dye, un- changeable by washing with soap. The conclusions of Mr. I3rande have been supported by M. Vauquelin,® but the fact of the presence of iron has been decided by many observers. Engelhart^ demonstrated, that the fibrin and albumen of the blood, when carefully separated from colouring particles, do not contain a trace of iron; whilst he pro- cured it from the red corpuscles by incineration. He also succeeded in proving the presence of iron in the colouring matter by liquid tests; for on transmitting a current of clilorine gas through a solution of red corpuscles, the colour entirely disappeared ; white flocks were thrown ' Chimie Organique, p. 368, Paris, 1833. ^ Handbucli der Physiologie, Baly's translation, p. 105, Lond., 1838. ^ System. Chym., ix. 207. * Med.-Cliir. Trans., iii. 213. * Philosophical Transactions for 1812, p. 90. ' Annales de Chimie et de Physique, toni. i. p. 0. ' Edinb. Med and Surg. Journal, Jan. 1827 ; and Turner's Chemistry, 5th Amer. edit., p. 005, Philad., 1S35. 372 CIRCULATIONS'. down, and a transparent solution remained, in which peroxide of iron was discovered by the usual reagents. The results, obtained by Engel- hart, as regards the quantity of iron, correspond with those of Berze- lius. These facts have since been confirmed by Rose,^ of Berlin; — and Wurzer,^ of Marburg, by pursuing Engelhart's method by liquid tests, detected the existence of the protoxide of manganese likewise. The proportion of iron does not appear to be more than one-half per cent.; yet, as it is contained only in the colouring matter, there is some reason for believing, that it may be concerned in the coloration of the blood, although probably in the form of oxide. Sulphocyanic acid has been detected in the saliva; and this acid, when united with peroxide of iron, forms a colour exactly like that of venous blood ; so that, it has been presumed, it may be connected with the coloration of tlie blood; but this is not probable; for Dr. Stevens found, that venous blood is darkened by sulphocyanic acid. M. Lecanu-^ has subjected the colouring matter to analysis, and found it to be com- posed of: — loss, representing the weight of the animal matter, 97*742; subcarbonate of soda, alkaline chlorides, subcarbonates of lime and magnesia, and phosphates of lime and magnesia, 1*724; peroxide of iron, 0'534. The result of his researches induces him to conclude, that the colouring matter is a compound of albumen with some co- louring substance unknown. This substance yielded on analysis : — loss, 98'26; peroxide of iron, 1*74; and M. Lecanu suggests, that it may result from the combination of some animal matter with certain ferruginous compounds analogous to cyanides. The views of Liebig in regard to the agency of the iron of the blood in respiration have been given elsewhere." After all, therefore, our ignorance on this subject is still great ; and all that we seem to know is, that peroxide of iron is contained in the colouring matter of the blood; but it can scarcely be the cause of the colour, for Scherer found, that the iron may be wholly dissolved by the agency of acids, and yet the animal matter, boiled afterwards in alcohol, colours the spirit deeply red. Dr. G. O. Eees,* however, ob- jects to this being received as a conclusive argument against the iron being essential to the formation of the red colour. The redness of the blood is one of its most obvious characteristics; and the change effected in the lungs as regards colour has been esteemed of eminent importance. It is no farther so, however, than as it indi- cates the conversion of venous into arterial blood. There is nothing essential connected with the mere coloration. In the insect, the blood is transparent ; in the caterpillar, of a greenish hue ; and in the internal vessels of the frog, yellowish. In man, it differs according to numer- ous circumstances; and the hue of the skin, which is partly dependent upon these differences, thus becomes an index of the state of indivi- dual health or disease. In 'morbus ccBrideiis^ cyanopathy or hlue disease, the whole surface is coloured blue, especially in those parts where the ' Poggendorf s Annalen, vii. 81 ; and Annales de Cliimie, &c., xxxiv. 268. 2 ychweigger's Journal, Iviii. 481. ' Annales de Chimie et de Physique, xlv. 5. * Page 320 of this volume. ^ Gulstonian Lecture; see banking's Abstract, Jan. to July, 1845, p. 251, Amer. edit., New York, 1S45. BLOOD — COAGULATION. Coagulation of Nurmal Human Blood under the Microscope. skin is delicate, as in the lips; and the appearance of the jaundiced is familiar to all. The formation of the clot, and its separation from the serum, are manifestly dependent upon the fibrin, which, by assuming the solid state, gives rise to the coagulation of the blood; — a phenomenon, that ^^S- H^. has occasioned much fruitless spe- culation and experiment; yet, if the views of M. Kaspail' were proved to be correct, it would be sufficiently simple. The alkaline character of the blood, and the production of coagulation by a dilute acid, leave no doubt, in his mind, that an alkali is the menstruum of the albumen of the blood. The alkaline matter, he thinks, is soda, but more espe- cially ammonia, of which, he says, authors take no account; but whose different salts are evident under the microscope. Now, "the carbonic acid of the atmospheric air, and the carbonic acid, that forms in the blood by its avidity for oxygen, saturate the menstruum of the albu- men, which is precipitated as a clot. The evaporation of the ammonia, and, above all, the evaporation of the water of the blood, which issues smoking from the vein, likewise set free an additional quantity of dis- solved albumen, and the mass coagulates the more quickly as the blood is less aqueous." The process of coagulation is influenced by exposure to air. Mr. Hewson affirmed, that it is promoted by such exposure, but Mr. Hunter was of an opposite opinion. If the atmospheric air be excluded, — by completely filling a bottle with recently drawn blood, and closing^ the orifice with a good stopper, — coagulation is retarded. Yet Sir C. Scu- daraore affirms, that if blood be confined within the exhausted receiver of an air-pump, coagulation is accelerated; and MM. Gmelin, Tiede- mann, and Mitscherlich^ found that, under such circumstances, both venous and arterial blood coagulated as perfectly as usual The pre- sence of air is certainly not essential to the process. Experiments have also been made on the eft'ect produced by different gases on the process of coagulation; but the results have not been such as to afford much information. It is asserted, for example, by some, that it is promoted by carbonic acid; and certain other irrespirable gases; and retarded by oxygen: by others, the reverse is aflirmed: whilst Sir Humphry Davy^" and Schroder van der Kolk" inform us, that they could not ' Chimie Organique, p. 373. 2 Tiedemanii and Treviranus, Zeitsclirift fiir PhysioL, B. v. Heft i. ^ Researches, &c., chiefly concerninsr nitrous oxide, p. 380, Lond., 1800 ; and Dr. Jolm Davy. Researches, Physiological and Anatomical, Amer. Med. Libr. edit,, p. 48, Philad., 18-40. ■ * Dissert, sisteus Sang. Coag. IIistor.,p. 81,Gruning., 1620; and Burdach, op. citat., iv. 37. 374 CIRCULATION". perceive any difference in the period of the coagulation of venous blood, when it was exposed to nitrogen, nitrous gas, oxygen, nitrous oxide, carbonic acid, hydrocarbon, or atmospheric air. The time, necessar}^ for coagulation, is affected by temperature. It is promoted by warmth; retarded, but not prevented, by cold. Mr. Hewson froze blood newly drawn from a vein, and afterwards thawed it: it first became fluid, and then coagulated as usual. Hunter made a similar experiment with the like result. It is obviously, therefore, not from simple refrigeration that the blood coagulates. Sir C. Scuda- more found, that blood, which begins to coagulate in four minutes and a half, in a temperature of 53° Fahr., undergoes the same change in two minutes and a half at 98°; and that, which coagulates in four minutes at 98° Fahr., becomes solid in one minute at 120°. On the contrary, blood, that coagulates firmly in five minutes at 60° Fahr., remains quite fluid for twenty minutes at the temperature of 40° Fahr., and requires upwards of an hour for complete coagulation. The observations of M. Olendrin^ were similar. As a general rule, it would seem, from those of Hewson,^ Schroder van der Kolk,^ and Thackrah,^ that coagulation takes place most readily at the temperature of the body. During the coagulation, a quantity of caloric is disengaged. M. Fourcroy^ relates an experiment, in which the thermometer rose no less than 11° during the process; but as certain experiments of Mr. Hunter^ appeared to show, that no elevation of temperature occurred, the observation of Fourcroy was disregarded. It was, however, confirmed by experiments of Dr. Gordon,^ of Edinburgh, in which the evolution of caloric during coagulation was rendered more manifest by moving the thermometer during the formation of the clot, first into the coagulated, and after- wards into the fluid part of the blood: ho found, that by this means he could detect a'difterence of 6°, which continued to be manifested for twenty minutes after the process had commenced. In repeating the experiment on blood taken from a person labouring under inflamma- tory fever, the thermometer was found to rise 12°. Sir C. Scudamore affirms,* that the rate at which the blood cools is distinctly slower than it would be were no caloric evolved; and that he observed the ther- mometer rise one degree at the commencement of coagulation. On the other hand. Dr. John Davy,' Mr. Thackrah, and Schroder van der Kolk,^° accord with Mr. Hunter in the belief, that the increase of tem- perature from this cause is very slight or null, whilst M. Easpail asserts that the temperature falls.'' Again we have to deplore the discordance amongst observers; and it will perhaps have struck the reader more than once, that such discordance applies as much to topics of direct ' Hist. Anatom. des Inflammations, ii. 42G, Paris, 1826. ' Experiment. Inquiries, i. 19, Lond., 1774; or Sydenham Society's edit., Lond., 1846. 3 Op. cit., p. 48. * Inquiry into the Nature, kc, of the Blood, p. 38, Lond., 1819. ^ Aniiales de Chimie, xii. 147. 6 A Treatise on the Blood, &e., p. 27, Lond., 1794. ' Annals of Pliilosophy, iv. 139. 8 An Essay on the Blood, p. 68, Lond., 1824. 9 Researches, Physiological and Anatomical, Amer. Med. Libr. edit., p. 6, Phila., 1840. '0 Miiller's Physiology, Baly's trausla|jjon, p. 98, Lond., 1838. " Chimie Organique, p. 361. BLOOD — COAGULATIO:?^. * 375 observation as to those of a theoretical character. The discrepancy regarding anatomical and physical /acte is even more glaring than that which prevails amongst physiologists in accounting for the corporeal phenomena; a circumstance, which tends to confirm the notion promul- gated by one of the most distinguished teachers of his day (Dr. James Gregory), that "there are more false facts in medicine" (and the remark might be extended to the collateral or accessory sciences) "than false theories." Tiiere are certain substances, again, which, when added to the blood, prevent or retard its coagulation. Mr. Hewson found, that sulphate of soda, chloride of sodium, and nitrate of potassa were amongst the most powerful salts in this respect. Muriate of ammonia and a solution of potassa have the same effect. On the contrary, coagulation is pro- moted by alum, and by the sulphates of zinc and copper.^ IIow these salts act on the libri)], so as to prevent its particles from coming toge- ther, it is not easy to explain. But these are not the only inscrutable circumstances that concern the coagulation of the blood. Many causes of sudden death have been considered to have this result : — lightning and electricity ; a blow upon the stomach ; injury of the brain ; bites of venomous animals ; certain narcotico-acrid vegetable poisons; ex- cessive exercise, and violent mental emotions, when they suddenly destroy, &c. Many of these affirmations, doubtless, rest on insufficient proof. For example, Sir C. Scudamore asserts that lightning has not this effect. Blood, through which electric discharges were transmitted, coagulated as quickly as that which was not electrified; and in animals killed by the discharge of a powerful galvanic battery, that in the veins was -always found in a solid state. M. Mandl has summed up the results of modern experiments on the subject as follows. First. The alkalies — potassa, soda, and ammonia — completely prevent coagu- lation : lime retards it. Secondly. The soluble alkaline salts — combi- nations of soda, potassa, ammonia, magnesia, baryta and lime, with car- bonic, acetic, nitric, phosphoric, tartaric, citric, boracic, sulphuric and cyano-hydric acid — also the chlorides, in very small quantity — favour coagulation. On the other hand, these substances in concentrated solution retard, and even prevent it entirely. The most active salts are the carbonates; the least so, combinations of chlorine, and sul- phates. 0'007 of carbonate of soda retards coagulation for several hours, whilst the sulphates do not act in the proportion of 14 per 1000. The action of a salt is more marked in proportion as it reddens more the blood; whilst combinations of chrome, chlorine and iodine do not redden it, and do not prevent its coagulation. When water is added to blood thus liquefied by a salt it coagulates again — the fibrin being precipitated. Thirdly. Metallic salts decompose the blood; some causing coagulation ; others preventing it. Fourthly. Very dilute vegetable acids favour it; when a little more concentrated, they pre- vent it; and when highly concentrated, decompose it like the mineral acids. Fifthly. The action of vegetable substances has not been suf- ficiently studied : some affirm, for instance, that narcotics prevent coagulation; others that they favour it. The same doubt exists in ' Magcndie, Lectures on the Blood, in Loud. Lancet, reprinted in Bell's Select Medi- cal Library, Pliilad., 1839. 376 CIRCULATION. regard to the action of poisons ; it is generally believed, however, that they — as well as lightning, a violent discharge of electricity, the in- stantaneous destruction of the nervous system, kc. — prevent coagula- tion. Sixthly. Very dilute solutions of gum Arabic, sugar, albumen, milk, &c., appear to act only in a mechanical manner by preventing the approximation of the coagulated particles. We shall find, hereafter, that the action of some of these agents has been considered evidence that the blood may be hilled; and, conse- quently, that it is possessed of life. All the phenomena, indeed, of coagulation, inexplicable in the present state of our knowledge, have been invoked to prove this position. The preservation of the fluid state, whilst circulating in the vessels — although agitation, ^vhen it is out of the body, does not prevent its coagulation — has been regarded of itself, sufficient evidence in favour of the doctrine. Dr. Bostock,^ indeed, asserts, that perhaps the most obvious and consistent view of the subject is, that fibrin has a natural disposition to assume the solid form, when no circumstance prevents it from exercising this inherent tendency. As it is gradually added to the blood, particle by particle, whilst that fluid is in a state of agitation in the vessels, it has no op- portunity, he conceives, of concreting; but when suffered to remain at rest, either within or without the vessels, it is liable to exercise its natural tendency. It is not our intention, at present, to enter into the subject of the vitality of the blood. The general question will be considered in a subsequent part of this work. AVe may merely observe, that, by the generality of physiologists, the blood is presumed, either to be en- dowed with a principle of vitality, or to receive from the organs, with which it comes in contact, a vital impression or influence, which, together with the constant motion, counteracts its tendency to coagu- lation.^ Even M. Magendie,^ — who is unusually and properly chary in having recourse to this method of explaining the notum per igno- tius, — affirms, that instead of referring the coagulation of the blood to any physical influence, it should be considered as essentially a vital process; or, in other words, as affording a demonstrative proof, that the blood is endowed with life; — a position, which — as will be seen hereafter — is not tenable.'* M. Vauquelin discovered in the blood a considerable quantity of fatty matter, of a soft consistence, Avhicli he, at first, regarded as fat ; but M. Chevreul,^ after careful investigation, declared it to be identical with the matter of the brain and nerves, and to form the singular compound of an azoted or nitrogenized fat. Cholesterin has been de- tected in it by Gmelin,^ and by Boudet.'' MM. Prevost and Dumas, Segalas, and others, have likewise demonstrated the existence of urea in the blood of animals, whose kidnej's had been removed. Chemical analysis is, indeed, adding daily to our stock of information on this matter; and exhibiting to us, that many of the substances, which compose the tissues, exist in the blood in the very state in which we ' Physiology, Sd edit., p. 271, Lond., 1836. 2 J. Miiller, llaudbuch, u. s. w., Baly's translation, p. 07, Lond., 1838. ' Precis, &c., ii. 234. * See Book iv., chap. 5, on Life. 8 Bostock's Physiology, p. 204. « Chimie, iv. 11(33. ' Journ. de Pharmacie, Paris, 1833, and Anuales de Chimie, lii. 337. BLOOD — ANALYSIS, 377 meet with them there. This is signally shown by the following table by Simon' of the constituents found in the blood of man, and certain mammalia. Protein compounds. Colouring matters. Extractive matters. Fats. Water. fFi])rin. Albumen. Globulin. ( Hematin. ( Hemaph?ein. Alcohol-extract. Spirit-extract. Water-extract. ' Cholesterin. Serolin. Red and white solid fats containing phosphorus. Margaric acid. [ Oleic acid. Salts. Oases. Iron (peroxide). ' Albuminate of soda. Phosphates of lime, magnesia, and soda. Sulphate of potassa. Carbonates of lime, magnesia, and soda. Chlorides of sodium and potas- s'nixn. Lactate of soda. [ Oleate and margarate of soda. Oxygen. Nitrogen. Carbonic acid. Sulphur. Phosphorus. The analyses of M. Lecanu^ are generally regarded as among the best. Blood obtained by him from two stout healthy men was found to be composed as follows : — Water, .... Fibrin, .... Albumen, .... Colouring matter (globules). Fatty crystallizable matter. Oily matter, Extractive matter soluble in water Albumen combined with soda, Chloride of sodium, potassium. Carbonates \ Phosphates > of potassa and soda Sulphates J Carbonates of lime and magnesia, 'I Phosphates of lime, magnesia, and iron, I Peroxide of iron, J Loss, ....... and alcol 780-145 785-590 2-100 3-5G5 65-090 69-415 133-000 119-626 2-430 4-300 1-310 2-270 1-790 1-920 l-2()5 2-010 1 8-370 2-100 2-400 100-000 7-304 1-414 2-586 100-000 On these analyses, Dr. Pront^ has remarked, that gelatin is never found in the blood, nor any product of glandular secretion ; and he adds, that a given weight of gelatin contains at least three or four per cent, less carbon than an equal weight of albumen. Hence, the production of gelatin from albumen, he conceives, must be a reducing process. We have seen, under the head of Respiration, what application he makes of these consideration s.'^ Researches on the ashes of human blood by Enderlin,'' in the labo- ratoiy of Giessen, give the following as the quantitative analysis in 100 parts: — - ' Animal Chemistry, Sydenham Society's edit., p. 166, Lond., 1845. ^ Annales de Chimie et de Physique, xlviii. 308, and Journal de Phai-macie, Sept., 1831. ■^ Bridgewater Treatise, Amer. edit., p. 280, Philad., 1834. * For the methods of analyzing the blood, see Simon, op. cit., p. 166. * Annalcn dor Cliemie und Pharmacie, Marz und April, 1844, cited by Mr. Paget, in Brit, and For. Med. llev., Jan., 1845, p. 255. 878 CIECULATIOX. Tribasic pliospliate of soda, 22"1 Chloride of sodium ........ 5-i"769 jx)tassium, ....... 4-416 Sulphate of soda, 2-4(Jl Phosphate of lime, ........ 3-(j3G magnesia, ....... 0-769 Oxide of iron, with some phosphate of iron, . . . 10-77 It has been inferred, from these analyses, that the albumen of the blood is not in the form of an albuminate of soda, or of a combina- tion with carbonate or bicarbonate of soda, but in combination with the alkaline tribasic phosphate, and chloride of sodium, — the former salt possessing, in a high degree, the power of dissolving protein compounds and phosphates of lime, and probably being the solvent of those con- stituents in the blood. Dr. John Davy,^ however, thinks, that even admitting the accuracy of Enderlin's results, the propriety of applying them to the condition of the alkali in liquid blood may be questioned. Carbonate of soda, he observes, is decomposed when heated with phos- phate of lime ; and when added in small quantity to blood is not to be detected in its ashes. This may account for its not having been found there. Were the opinion, referred to, correct, an acid added to blood or its serum, after the action of the air-pump, ought not on re-exhaustion to occasion a farther disengagement of air ; but Dr. Davy finds that it does. This and other results induce him to give the preference to the conclusion, that blood contains sesquicarbonate of soda, M. Dutrochet believed, that he had formed muscular fibres from albumen by the agency of galvanism ; and supposed, that the red cor- puscles of the blood formed each a pair of plates, the nucleus being negative, the envelope positive ; but A[uller^ has shown, that all the appearances, which he attributed to difterent electric properties of the blood, are explicable by the precipitation of the albumen and fibrin in consequence of the decomposition of the salts of the serum and of the oxidation of the copper wire used in the experiments, — both the decom- position of the salts and the oxidation of the copper being the usual effects of galvanic action. With the galvanometer he was unable to discover any electric current in the blood ; and he perceived no varia- tion in the needle of the rnultiplicator, when he inserted one wire into an artery of a living animal, and the other into a vein. Interesting experiments and observations on the blood were pub- lished several years ago by Dr. Benjamin G. Babington.^ The prin- cipal experiment was the following. He drew blood in a full stream into a glass vessel filled to the brim, from the vein of a person labour- ing under acute rheumatism. On close inspection, a colourless fluid was immediately perceived around the edge of the surface, and after a rest of four or five minutes, a bluish appearance was observed forming an upper layer on the blood, which was owing to the subsid- ence of the red corpuscles to a certain distance below the surface, and the consequent existence of a clear liquor between the plane of the cor- puscles and the eye. A spoon, previously moistened with water, was now immersed into the upper laj-er of liquid, by a gentle depression of ' Proceedings of the Rojal Society of Edinburgh, vol. ii. No. 26, for 1845. ^ Handbuch, u. s. w., Baly's translation, p. 133. 3 Med.-Chirurg. Transact., vol. xvi., Part 2, Lond.,1831; and art. Blood (Morbid Conditions of the) in Cyclop. Anat. and Physiol., Lond., 1S36. BLOOD — BUFFY COAT. 379 one border. The liquid was thus collected quite free from red corpus- cles, and was found to be an opalescent, and somewhat viscid solution, perfectly homogeneous in appearance. By repeating the immersion, it was collected in quantity, and transferred to another vessel. That which Dr. Babington employed was a bottle holding about 180 grains, of globular form, with a narrow neck and perforated glass stopper. The solution with which the globular bottle was filled, though quite homo- ^geneous at the time it was thus collected, was found, after a time, to separate into two parts, viz., into a clot of fibrin, which had the precise form of the bottle into which it was received ; and a clear serum, pos- sessing all the usual characters of the fluid. From this experiment. Dr. Babington inferred, that buffed blood, to which we shall have to refer under another head, consists of only two constituents, red corpuscles, and a liquid to which he gives the name liquor sanguinis — plasma of Schultz — so called by him, because he esteems it to be the true nutri- tive and plastic portion of the blood, from which all the organs of the body are formed and nourished. It has long been observed, that the blood, of inflammation is longer in coagulating than the blood of health, and that the last portion of blood drawn from an animal coagulates quickest. The immediate cause of the buffy coat is thus explained by Dr. Babington. The blood, consisting of liquor sanguinis and insoluble red corpuscles, pre- serves its fluidity long enough to permit the corpuscles, which are of greater specific gravity, to subside through the liquor sanguinis. At length, the liquor sanguinis separates, by a general coagulation and contraction, into two parts; and this phenomenon takes place uni- formly throughout the liquor. That part of it, through which the red corpuscles had time to fall, furnishes a pure fibrin or buiied crust, whilst the portion into which the red corpuscles had descended fur- nishes the coloured clot. This, in extreme cases, may be very loose at the bottom, from the great number of red corpuscles collected there, each of which has supplanted its bulk of fibrin, and consequently diminished its firmness in that part. There is, however, with this limitation, no more fibrin in one part of the blood than another. Re- searches by Mr. Gulliver^ would seem to show, that the rate at which the red corpuscles sink in a fluid may give a very incorrect measure of its tenuity, since they subside much slower in serum, or in liquor sanguinis made thinner and lighter by weak saline solutions, than in the same animal fluids made thicker and heavier by gum. The blood, too, may have its coagulation retarded, whilst it is thinned and re- duced in specific gravity ; and yet no bufty coat appear. The greater aggregation of the corpuscles, observed by Mr. T. Wharton Jones,^ and subsequently in his experiments, seemed to him to be connected with the accelerated rate of subsiding ; as it was prevented or reversed, by salts, which dispersed the corpuscles, and increased by viscid matters, which increased the aggregation. It is a well-known fact, that the shape of the vessel into which the blood is received influences the depth of the buff. The space, left by the gravitation of the red corpuscles, bears a proportion to the whole perpendicular depth of the ' Diihlin Med. Press, Dec. 11, 1844. * Ediiiburijh Med. and Surg. Juunual, Oct. 1843, p. 309. 380 CIRCULATIOX. blootl, so that in a shallow vessel scarcely any buff may appear, whilst the same blood in a deep vessel would have furnished a crust of con- siderable thickness ; but Dr. Babington asserts, that even the quantity of the crassamentum is dependent, within certain limits, on the form of the vessel. If this be shallow, the crassamentum will be abundant; if approaching the cube or sphere in form, it will be scanty. The dif- ference is owing to the greater or less distance of the coagulating par- ticles of fibrin from a common centre, which causes a more or less powerful adhesion and contraction of those particles. This is a matter of practical moment, inasmuch as blood is conceived to be thick or thin, rich or poor, in reference to the quantity of crassamentum : and pathological views are entertained in consequence of conditions, which, after all, may depend not perhaps on the blood itself, but on the ves- sel into which it is received. To remove an objection, that might be urged against a general con- clusion deduced fi'om the experiment cited, — that it was made upon blood in a diseased state, — Dr. Babington received healthy blood into a tall glass vessel half filled with oil, which enabled the red corpuscles to subside more quickly than would otherwise have been the case. This blood was found to have a layer of liquor sanguinis, which formed a buffy coat, whilst a portion of the same blood, received into a similar vessel, in which there was no oil, had no buff. Hence, it appeared, that healthy blood is similarly constituted as blood disposed to form a buff}" coat, the only difference being, that the former coagulates more quickly than the latter. Dr. J. Dav}',^ however, has observed, that inflammatory blood, in some instances, does not coagulate more slowly than health}'- blood, and as from the experiments of Professor Miiller' it would appear that the presence of fibrin in the blood favours the subsidence of the red particles, Muller was led to infer, that the forma- tion of the buffy coat may arise from the blood containing a larger quantity of fibrin, which the blood of inflammation is known to do. So that the principal causes, he thinks, of the subsidence of the red particles and the formation of the bufl^y coat in inflammatory blood, appear to be — the slow coagulation of the blood, and the increased quantity of fibrin. The most correct view, however, is, perhaps, that of M. Andral,^ that the essential condition of the buffy coat is an in- crease in the quantity of fibrin in proportion to the red corpuscles. Hence, if there be an absolute increase of fibrin, the red corpuscles remaining the same, as in inflammation; or, if there be a diminution in the proportion of the red corpuscles, the fibrin remaining the same, as in chlorosis, the buffy coat may result ; provided only there be — as there probably always is under such circumstances — a greater aggregation of the corpuscles. An interesting fact connected with this subject has been noticed by Mr. T. Wharton Jones.'* If a single drop of inflammatory blood be examined by the microscope, it Avill be seen that the red corpuscles have an unusual attraction for each other, which occasions them to coalesce in piles and masses, as in the marginal illustration, ^, Fig. 119, ' Philosopliical Transactions, for 1822. * Op. citat., p. 117. 3 Hcmatologie Patholoifique, p. 75, Paris, 1843, or Meigs's and Stille's translation, Philad., 1844. * Edinburgh Medical and Surgical Journal, Oct., 1843, p. 309. BLOOD — OF DIFFEREXT VEINS. 381 leaving wide interspaces for the fibrin, lymph-corpuscles, and serum. It is probable, too, that there is an increased attraction between the particles of the fibrin, which will account for the firmer clot of the blood of inflammation, Fig- 119. The fact of a single drop of blood being sufficient to indicate the character of the ^^ whole mass may be important in cases where " a doubt exists as to the propriety of bleeding to any extent. It is proper to remark, that the researches ^ ^ of Mulder^ have led him to infer, that the ^ ^ buff'y coat does not consist of true fibrin, but ^^^w^^^^^ is a compound of a binoxide of protein, which j g ^ ^^^ is insoluble in boiling water, and a tritoxide, ^^^^ ^- iMv^ ^^^ which is soluble. These oxides Mulder com- ^^ £"^^1^ ^^^^ -^^ prehends under the name oryprotein. ^^^p8, J^- ^'^^W^ It may, also, be remarked, that in all expe- ^4^ riments on the horse, whenever the blood Aggregntion of Corpuscles in flows from an opened vein in a continuous ^if^^^ *"*^ "^ ^''^'"^'^ stream, with a sufficiently strong iet, and is T . . 1 ii i • -ii 1. 11 (i- Healthy blood. 6. Inflamed received into a vessel that is neither too shai- biood. low nor too wide, the upper part of the clot is instantly found occupied by a white mass, which perfectly resem- bles the buff of the blood of man. Such was the result of the obser- vations of MM. Andral, Gavarret, and Delafoud.^ It need scarcely be said, that venous blood, composed as it is in part of the products of heterogeneous absorption, must differ in its character in the different veins. In its passage through the capillary or inter- mediate circulation, the arterial blood is deprived of several of its ele- ments, but this deprivation is different in different parts of the body. That, for example, which returns from the salivary glands, must vary from that which returns from the kidneys. In the blood of the abdo- minal venous system, the greatest variation is observed. Professor Schultz^ has inquired into the chemical and physiological differences between that of the vena porta and of the arteries and other veins. He found, that it is not reddened by the neutral salts, or by exposure to the atmosphere, or to oxygen; that it does not generally coagulate; contains less fibrin; proportionably more cruor, and less albumen; and has twice as much fat in its solid parts as that of the arteries and other veins ; the j^roportions being as follows : — Blood of the vena porta, 1-66 per cent. of ilie arteries, . . • . . • • 04)2 of the other veins, . . . ' . . . 0'83 Simon,'* in his researches, also found a much less proportion of fibrin and a larger of fat and of colouring matter. The flit he ascribes to the fluids produced during the act of digestion, which are conveyed into the portal vein. ' Annalen der Chemie, ii. s. w., Bd. xlviii., ITeidelb., 1843 ; cited by Mr. T. Whar- ton Jones, in Brit, and For. Med. Rev., July, 1844, p. 259. ^ Essai d'Hematologie Pathologique, p. 27, Paris, 1843. ^ Rust, Magazin fiir die cesammt. Ileilkund., Bd. 44, H. i. ; and Lond. Lancet, Aug. 10, 1839, p. 717. * Animal Chemistry, Sydenham Society's edition, p. 208, Lond., 1845. 882 CIRCULATION. M. Jules Beclard^ always found the cipher of red corpuscles in the blood of the splenic vein less than in that of the jugular; with a cor- responding augmentation in the amount of solid matters in the serum, and a constant increase of fibrin. Otto Fanke,^ however, contests the accuracy of M. Beclard's analyses, and affirms, as the result of numerous careful observations, that there is always a diminution of the fibrin in the blood of the splenic vein; and that this is the only constant article of difference between the blood that enters and that which issues from the spleen ; and Lehmann' remarks, that the investigations of Funke "afford, at all events, a proof, that the greatest caution is necessary in deducing conclusions from individual analyses, and investigations of individual fluids, without reference to the simultaneous constitution of the other animal juices. Many ingenious conclusions would no doubt have been deduced from analyses of the blood of the splenic vein, if the arterial blood had not been simultaneously compared with it." The mean of four observations of the blood of the splenic vein of a crimi- nal, by Vierordt, is said to have given the ratio of colourless corjDuscles to the coloured as 4*9 to 1. \?y The following table by Mr. Gray,* who was assisted in his chemical researches by Dr. Noad, exhibits in a tabular form the average results of 111 analyses of the aortic, jugular, and splenic venous blood of the horse : — Aortic. Jugular. Splenic. 159-50 141-00 95-12 1-04 0-86 0-71 840-50 859^00 904-88 032-5 1031-14 1032-24 7S9-14 793-42 829-81 42-00 54-40 63-00 2-26 4-15 6-32 •04 0-05 0-22 157-20 136-80 88-58 •35 •64 •30 •49 •92 2-42 1-61 3^27 6-(54 8^73 7-24 Clot, Ash in ditto, Serum, ..... Spec, gravity of ditto, Water, ..... Albumen, .... Fibrin, ..... Fat in ditto, Globules, .... Oily matters, .... Crystalline fat, Alcohol extract, Water extract, Mr. Gray considers the chief chemical peculiarities of splenic venous blood to consist in a very considerable diminution of the blood cor- puscles, an increase of the iron, albumen, and fibrin, and a deep red- dish-brown colour of the serum. The subject of the changes produced on the portal blood, more especially as regards the quantity of red corpuscles, will be referred to when considering the functions of the Spleex. The character and quantit}' of the different constituents of the blood, as well as its coagulation, vary greatly in disease ; and the investigation is one of the most important in the domain of pathology. It is one that has attracted the attention of modern pathologists, and especially of MM. Andral and Gavarret, and of Simon, and 5^1. Becquerel and Eodier, who have endeavoured to detect the changes that occur in dis- ' Arcliiv. General, de Med., Oct., 1848; and Traite Elementaire de Physiologie Hu- maine, p. 411, Paris, 1855. ^ Rudolpli Wagner's Lehrbuch der speciellen Physiologie, S. 119, Leipzig, 1854. ' Physiological Chemistry, translated from the 2d edit., by Dr. Day ; Amer. edit., by Dr. Rogei-s, i. C31, Philad., 1855. * Schmidt's Jahrbiich., x. 789, in Brit, and For. Med.-Chir. Rev., April, 1855, p. 559. = Cited by Dr. Day, in Brit, and For. Med.-Chir. Rev., July, 1855, p. 216. BLOOD — CONSTITUENTS. 383 ease in the amount of tlie organic elements of the fluid. These the author has referred to in their appropriate pLices in another work.' The usual proportions of each element, in 1000 parts of healthy blood, according to M. Lecanu, adopted by MM. Andral and Gavarret, are as follows: — Fibrin, 3 Red corpuscles, 127 Solid matter of serum, ........ 80 Water, 790 The average of analyses of the blood of nine healthy individuals — four females and five males, by Dr. Ch. Frick,^ of Baltimore, corre- sponds nearly with the above. According to Simon,^ the proportions are somewhat different, — • resulting, in a great measure, from a different method of analysis. The mean of his observations gave — Water, 795-278 Solid residue, 204-022 Fibrin, 2-104 Fat, 2-346 Albumen, 76-600 Globulin, 103-022 Hematin, 6-209 Extractive matter and salts, ...... 12-012^ The following table exhibits the mean composition of the blood, in eleven cases, as observed by MM. Becquerel and Eodier.* Density of the defibrinated blood, 1060-2 " of tbe serum, ....... 1028 Water, 779 Corpuscles, • . . . 141-1 Albiimen, 69-4 Fibrin, .......... 2-2 Extractive matters and free salts, ..... 6*8 Fatty matters, ......... 1-6 Serolin, 0-02 Fatty phospliuretted matter, 0-488 Cholesterin, 0-088 Soapy matter, 1-004 One thousand parts of calcined blood contained — • Chloride of sodium, . . . . . . . . .3-1 Soluble salts, .......... 2-5 Phosphates, 0-334 Iron, 0-565 From these numbers they draw the following deductions. First. The limits within which the composition of healthy blood varies are restrict- ed, and probably dependent on constitution, age, and diet. Secondly. The number for the corpuscles exceeds 127, which has been regarded as expressing the healthy mean. Tlurdhj. The number for the fibrin, 2"2, is below that usually admitted as the mean of that element, o. ' Practice of Medicine, 3d edit., Philad., 1848. ^ American Journal of the Medical Sciences, Jan., 1848, p. 27. ' Animal Chemistry, p. 245. ■* It is proper to remark, with Simon, that the sum of the hematin and globulin, in his analysis, can never uipresent the aljsolute quantity of blood corpuscles. In his method the nuclei and capsules of the blood corpuscles are estimated as albumen ; in that of Berzelius as fibrin ; and in that of MM. Andral and Gavarret, as appertaining to the corpuscles. * Gazette Medicale de Paris, Nos. 47, 48, 49, 50, and 51, for 1844. 1-3 8S4 CIKCULATION. The following tables have been constructed chiefly from the analyses of Denis, Lecanu, Simon, Nasse, Lehmann, Becquerel and Rodier, and Gavarret; and "are designed to combine, as far as possible, the ad- vantage of accuracy in numbers with tlie convenience of presenting at one view a list of all the constituents of the blood."^ Average proportions of the chief constituents in 1000 parts : — Water, 784 Red corpuscles, ......... 131 Albumen of serum, ......... 70 Saline matters, .......... 6-03 Extractive, fatty and other matters, ...... 6*77 Fibrin 2-2 1000- Average proportion of all the constituents of the blood in 1000 parts : — Water, 784 Albumen, ........... 70 Fibrin, 2-2 Bed coi-puscles, ......... globulin, 123-5 hematin, .......... 7'5 Fatty matters: Cholesterin, 0*08 "] Cerebrin, 0-40 Serolin, 0-02 Oleic and margaric acids, Volatile and odorous fatty acid, Fat containing phosphorus, ^ Inorganic salts: Chloride of sodium, ......... 3*6 Chloride of potassium, ........ 0'36 Tribasic jjliosphate of soda, ....... 0-2 Carbonate of soda, ......... 0*84 Sulphate of soda, ......... 0*28 Phosphates of lime and magnesia, ...... 0'25 Oxide and phosphate of iron, . . . . . . . 0*5 Extractive matter, with salivary matter, urea, biliary ) ^ ,„ colouring matter, gases and accidental substances, ) 1000- The mode in which the ratio of the various elements of the blood is estimated is detailed by MM. Andral and Gavarret, Simon, and Becquerel and Rodier, in the works referred to. A simpler method has, however, been given by M. Figuier,^ founded on the fact made known by Berzelius, that after the addition of a solution of a neutral salt to defibrinated blood, the corpuscles do not pass through bibulous paper. On the addition of two parts of a solution of sulphate of soda, of specific gravity 1*180, to one of blood, M. Figuier found, that the whole of the corpuscles remained on the surface of the filter. The following is his procedure. The fibrin is removed in the usual way by whipping ; and dried, and weighed. The weight of the corpuscles is then ascertained, and that of the albumen by coagulating the filtered solution by means of heat. The proportion of water is determined ' Kirkes and Paget, Manual of Physiology, 2d Araer. edit., p. 54, Philad., 1853. ^ Aunales de Chimie et de Physique, ii. 503, cited iu Rauking's Abstract, i. 299, Anier. edit., New York, 1845. BLOOD — CONSTITUENTS. 385 by evaporating a small known weight of the blood. The advantage of this plan consists in the facility with which the most impoitant constituents may be determined without any difficult manipulations. The proportion of fibrin, according to MM. Andral and Gavarret, may vary perhaps within the limits of health, from 2^ to 3| parts in a thousand. The quantity cannot, however, be accurately estimated, inasmuch as it is always mixed with colourless corpuscles; from which, as ]\[essrs. Kirkes and Paget^ have remarked, it cannot be separated by any mode of analysis yet invented. " In health, they may, perhaps, add too little to its weight to merit consideration ; but in many dis- eases, especially in inflammatory and other blood diseases in which the fibrin is said to be increased, these corpuscles become so numerous that a large proportion of the supposed increase of the fibrin must be due to their being weighed with it. On this account all the statements respecting the increase of fibrin in certain diseases need revision." The amount of red corpuscles appears to be subject to greater varia- tion within the limits of health than that of the fibi'in. The maximum is about 140, but this is connected with a plethoric condition : the minimum about 110. Strength of constitution contributes most to raise the corpuscles towards the maximum; whilst debility, congenital or acquired, diminishes them towards the minimum proportion. The solid matter of the serum likewise varies, but there is a certain point of diminution in health below which they do not pass.^ The analyses of MM. Becquerel and Kodier exhibit a marked differ- ence in the proportion of the constituents of the blood of the two sexes. So great is this, that in order to attain correct conclusions in regard to morbid blood, it is indispensable to contrast it with the male or female blood in healtli. The average differences between the two are seen in the followins: table: — Male. Female. Density of defibrinated blood, .... 1060-0 1057-5 Density of serum, Water, . Fibrin, . Sum of fatty mattei-s, Serolin, Phospliorized fat, Cliolesterin, Saponified fat, . Albumen, Blood corpuscles, . Extractive matters and Chloride of sodium, Other soluble salts. Earthy phosphates. Iron, salts. 1028-0 1027-4 779-0 791-1 2-2 2-2 1-GO 1-62 0-02 0-02 0-488 0-464 0-088 0-090 1-004 1-046 69-4 70-5 141-1 127-2 6-8 7-4 3-1 3-9 2-5 2-9 0-334 0-354 0-566 0-541 The main difference, consequently, between male and female blood is in the amount of water and blood corpuscles.^ ' Manual of Physiology, 2d Amer. edit., p. 56, Philad., 1853. '■^ Andral, Hematologie Pathoiogique, p. 2t), Paris, 1843. ^ For the difierences in blood, according to constitution, temperament, ^c, see Simon, Animal Chemistry, Sydenham Society's edition, p. 236, Lond., 1845, or Amer. edit., Philad., 1846. VOL. I. — 25 386 CIRCULATION". The following table by Henle/ gives the results of the analyses of different observers as regards the proportion of the organic constitu- ents of human blood, and the corresponding specific gravities of blood and serum. S. G. S. G. Blood Cor- Residue of of Blood. of Serum. Water. puscles. Serum. Fibrin. Observer. Remarks. 1 1062 1031 772 128 97 2 Popp. 1 2 1061 781 121 86 10 do. iMany colourless corpuscles. 3 1057 773 142 82 3 Few do. 4 1055 1028 799 130 75 3 Becquerel and Rodier. 5 1055 1027 793 126 78 2 do. 6 1053 771 146 78 4 Popp. 7 1053 781 140 76 2 do. 8 1051 802 117 76 5 do. 9 1050 790 114 90 5 do. Many do. 10 1049 803 120 71 5 do. do. 11 1049 806 92 96 5 do. do. 12 1048 791 128 76 2 do. 13 1048 814 104 76 5 do. Few do. 14 1048 806 124 66 4 do. 15 1048 801 107 86 5 do. Many do. 16 1048 811 95 86 8 do. A moderate num- ber of do. 17 1047 811 118 65 6 do. 18 1047 794 121 81 4 do. 19 1046 790 129 78 2 do. 20 1046 1023 831 105 54 2 Becquerel and Rodier. 21 1045 1024 78 3 do. 22 1044 827 91 71 11 Popp. 23 1044 801 100 86 12 do. 24 1044 790 115 83 11 do. A strong bufiy coat. 25 1043 826 93 72 9 do. Few colourless corpuscles. 26 1043 812 112 66 10 do. A moderate buffy coat. 27 1042 812 105 77 6 do. Few colourless corpuscles. 28 1042 821 91 84 4 do. 29 1042 828 95 74 3 do. Many colourless corpuscles. 30 1042 1022 92 2 Becquerel and Rodier. 31 1041 816 77 94 13 Popp. Strong buify coat. 32 1041 817 99 76 8 do. 33 1040 831 92 68 9 do. 34 1040 827 92 76 4 do. 35 1039 855 6S 72 6 do. Few colourless corpuscles. 36 1039 845 96 80 5 do. 37 1030 792 126 81 2 do. 38 1026 788 124 82 6 Heller. 39 1025 773 146 77 4 do. 40 1025 834 78 83 5 do. 41 1024 820 87 85 8 do. 42 1023 782 147 65 6 do. 43 1011 58 Popp. Serum rich in fat. ' Haudbuch der Ratiouellen Patliologie, 2er Band. s. 18, Braunschweig, 1847. BLOOD — ORGANIC COXSTITUENTS. 587 There is considerable difference, however, amongst observers in re- gard to the ratio of the different organic constituents of healthy blood, and this is dependent upon the different modes of evaluation adopted by them. It is advisable, therefore, in observations made on diseased blood, to follow the method employed by some one of them; and that of ^[M. Andral and Gavarret is generally chosen. To exhibit this difference the following table drawn up by Hcnle^ may be introduced : — 1000 parts of healthy venous blood contain Corpuscles. Water. Fibrin. Albumen. Extractive matters. Salts. According to Le Canu, " Becquerel and Rodier, of men, of women, " Popp, " Zimmerman, " Simon, of men, of women, " Christison, of men, of women, " Hittorf, of women. 127 141-1 127-2 120 127 112-2 106-0 153-5 120-7 126-4 790 779 791-1 790 791-9 798-6 756-2 795-2 793-0 3 2-2 2-2 2-5 3 2-0 2-2 5-2 2-5 1-4 ^ 8 7 69-4 70-5 2 8-4 9 75-6 77-6 SS 80 16-6 12-6 67-4 85-3 81-6 11-L I. II. in. 783-18 769-64 775-7 216-82 230-36 224-3 2-30 2-03 2-63 63-34 68-45 70-08 139-92 146-22 138-71 5-16 5-34 3-84 8-85 8-86 9-04 1-70 An analysis of healthy human blood by Scherer^ gives the following proportion of the various constituents : — ■ Water, Fixed parts, Fibrin, Albumen, . Blood corpuscles, Extractive matters. Soluble salts, Fat, . It may be added, that a peculiar entozoon, — i^olijsioma venarum^ liexaOiyridlum venarian, — has been found in human venous blood, especially in that of persons affected with hasmoptysis; Treutler found one in the tibial vein of a young man, who had lacerated it whilst bathing. Yogel, however, suggests, that it may have been a planaria, which had entered the vein from without;^ and Valentin several times observed minute entozoa — anguilhdce intesiinales — in the circulating blood of frogs. MM. Gruby and Delafond^ communicated to the xica- dtmie Royale des Scitnces of Paris, the discovery of filariio in the circu- lating fluid of a living dog. ' Op. cit., s. 73. * Canstatt's .Tahresbericht liber die Fortschritte in der Biologic im Jalire, 1848, s. 65, Erlangen, 1849. * The Pathological Anatomy of the Human Bodv, Ent^'lish translation hy Day, n. 467, Lond., 1847. •• Phihid. Med. Examiner, Jan. 13, 1844, from Comptes Rendus. 388 CIRCULATION. 3. PHYSIOLOGY OF TUE CIRCULATION. The blood, contained in the circulatory apparatus, is in constant motion. The venous blood, brought from every part of the body, is emptied into the right auricle; from the right auricle it passes into the corresponding ventricle; and the latter projects it into the pulmonary artery, by which it is conveyed to the lungs, passing through the capil- lary system into the pulmonary veins ; these convey it to the left auri- cle; from the left auricle it enters the corresponding ventricle ; and the left ventricle sends it into the aorta, along which it passes to the different organs and tissues of the body, through the general inter- mediate or capillary system, wliich communicates with the veins; these return it to the part whence it set out. This entire circuit includes both the lesser and the greater circulation. It was not until the commencement of the seventeenth century, that any precise ideas were entertained regarding the general circulation. In antiquity, the most erroneous notions prevailed ; the arteries being generally looked upon as tubes for the conveyance of some aerial fluid to, and from, the heart; whilst the veins conducted the blood, whither or for what precise purpose was not understood. The names, given to the principal arterial vessel — aorta — and to the arteries, sufficiently show the functions originally ascribed to them, — both being derived from the Greek", a»7P, "air," and trifynv, "to keep;" and this is farther confirmed by the fact, that the trachea or windpipe was originally termed an artery, — the aprjjpia tpaxeia of the Greek, — aspera arteria of the Latin writers.' In the time of Galen, however, the arteries were known to contain blood; and he seems to have had some notions of a circulation. He remarks, that the chyle, the product of digestion, is collected by the meseraic veins and cari-ied to the liver, where it is converted into blood; the supra-hepatic veins then carry it to the pul- monary heart; whence a part proceeds to the lungs, and the remainder to the rest of the body, passing through the median septum of the auri- cles and ventricles. This limited knowledge of the circulation con- tinued through the whole of the middle ages, — the functions of the veins being universally misapprehended; and the general notion being, that they also convey blood from the heart to the organs; from the centre to the circumference. It was not until after the middle of the sixteenth century, that the lesser circulation or that through the lungs was comprehended by Michael Servetus, — who fell a victim to the persecution and intolerance of Calvin, — and by Andrew Ccesalpinus and Kealdus Columbus. It has been imagined, that they possessed some notion of the greater circulation. Howsoever this may have been, all nations unite in awarding to Harvey the merit, if not of entire originality of at least having first clearly established it.* The honour of the discovery is, therefore, his; and Ijy it his name has been rendered immortal, — for its importance to the knowledge of the physiology and pathology of the ' " Spiritns ex pulmoue in cor recipitur et per arterias distribuitur, sanguis per venas." Cicero, De Natura Deor., Lib. ii. ^ "Lorsque Harvey parut, tout, relativement a La circulation, avait ete indique ou soupconne ; rien notait etabli." Flourens, Histoii'e de la Docouverte de la Circula- tion du Sang, p. 28, Paris, 1854. PHYSIOLOGY OF THE CIRCULATION". 389 animal fabric is overwhelming. How vague and inaccurate must have been the notions of the early pathologists regarding the doctrine of acute diseases, in which the circulation is always largely affected, — dis- eases, which, according to the estimate of some writers, constitute two- thirds of the morbid states to which mankind are liable! It was in the year 1619, that Harvey attained a full knowledge of the circulation ; but his discovery was not promulgated until the year 1628, in a tract, to which the merit of clearness, perspicuity, and de- monstration has been awarded by all.'^ Yet so strong is the force of prejudice, and so difficult is it to discard preconceived notions, that according to Hume,^ it was remarked, that no physician in IJurope, who had reached forty years of age, ever, to the end of his existence, adopted Harvey's doctrine of the circulation ; and Harvey's practice in London diminished extremely for a time from the reproach drawn upon him by that great and signal discovery. Of the truth of the course of the blood, as discovered by Harvey, we have numerous and incontestable evidences, which it is almost a work of supererogation to adduce. Of these the following are some of the most striking. First. If we open the chest of a living animal, we find the heart alternately dilating and contracting so as manifestly to receive and expel the blood in reciprocal succession. Secondly. The valves of the heart, and of the great arteries that arise from the ven- tricles, are so arranged as to allow the blood to flow in one direction, and not in another; and the same may be said of the veins, which are directed towards the heart. The tricuspid valve permits the blood to flow only from the right auricle into the corresponding ventricle ; the sigmoid valves admit it to enter the pulmonary artery, but not to return; and, as there is, in the adult, no immediate communication between the right and left sides of the heart, the blood must pass along the pulmonary artery and the pulmonary veins to the left auricle. The mitral valve, again, is so situate, that the blood can only pass in one direction from auricle to ventricle; and, at the mouth of the aorta, the same valvular arrangement exists as in the pulmonary artery, which permits the blood to proceed along the artery, but prevents its reflux. Thirdly. If an artery and vein be wounded, the blood will be observed to flow from the part of the vessel nearest the heart in the case of the artery; from the other extremity in that of a vein. The ordinary ope- ration of bloodletting at the flexui^e of the arm affords an elucidation of this. The bandage is applied above the elbow, for the purpose of com- pressing the superficial veins, but not so tightly as to compress the deep-seated artery also. The blood passes along the artery to the ex- tremity of the fingers, and returns by the veins; but its progress back to the heart by the subcutaneous veins being prevented by the ligature, they become turgid; and, if a puncture be made, it flows freely. If, however, the ligature be applied so forcibly as to compress the main artery, the blood no longer flows to the extremity of the fingers; there is none, consequently, to be returned by the veins ; they do not rise properly ; and if a puncture be made no blood flows. This is not an ' Exercitat. Anatom, de Motu Cordis et Sanguinis, Francof., 1028, Glasgure, 1751. * History of England, vol. vii. chap, Ixii. p. 347, Loudon, 17S2. 890 CIRCULATION unfrequent cause of the failure of au inexperienced pblebotomist. If the baiidage, under such circumstances, be slackened, the blood resumes its course along the artery, and a copious stream issues from the orifice, ■which did not previously transmit a drop. This operation, then, exhibits the fact of the flow of blood along the arteries from the heart, and of its return by the veins. From what has been said, too, it will be obvious, that if a ligature be applied to both vessels, the artery will become turgid above the ligature, the vein below it. Fourthly. The microscopical experiments of Leeuenhoek, Malpighi, Spallanzani, and others have exhibited to the eye the passage of the blood in suc- cessive waves by the arteries towards the veins, and its return by the latter. Lasth/. The fact is forther demonstrated by the effect of trans- fusion of blood, and of the injection of substances into the vessels; both of which operations will be alluded to in another place. In tracing the physiological action of the different parts of the cir- culatory apparatus, we shall follow the order observed in the anatomi- cal sketch ; and describe, in succession, the circulation in the heart, arteries, capillary vessels, and veins ; on all which points there has been interesting diversity of opinion, and much room for ingenious speculation, and farther improvement. a. Circulation in the Heart. It has been already observed, that when the heart of a living ani- mal is exposed, it is remarked to undergo alternate contraction and dilatation. The mode, in which the circulation through the organ is accomplished is generally considered to be as follows. — The blood is received into the two auricles at the same time, and is transmitted into the two great arteries synchronously. In order that the heart shall receive blood, it is necessary that the auricle should be dilated. This movement is partly effected by virtue of the elasticity which it pos- sesses in its structure. Let us suppose it to be once filled ; the stimulus of the blood excites it to contraction, and the blood is sent into the corresponding ventricle. As soon, however, as it has emptied itself, the stimulus is withdrawn ; and, by virtue of its elasticity the muscular structure returns to the state in which it was prior to its contraction. An approach to a vacuum is thus formed in the cavity, and the blood from the veins is solicited towards it, until it is again filled, and its contraction renewed. When the right auricle contracts there are four channels by which the blood might be presumed to pass from it, — the two terminations of the venj© cavse ; the coronary vein, and the auri- culo-ventricular opening. The constant flow of blood from every part of the body prevents it from readily returning by the venae cavse, whilst the small quantity, which, under other circumstances, might have entered the coronary vein, is prevented by its valve. To the flow of the blood through the aperture into the ventricle, which is in a state of dilatation, there is no obstacle, and accordingly it takes this course, raising the tricuspid valves. It may be remarked, that physiologists are not entirely of accord regarding the reflux of blood into the venas cava?. Some think, that this always occurs to a slight extent; others, never in the healthy state. Its existence is unequivocal, where an obstacle occurs to the IN THE HEAET. 391 dae discharge of tlie blood into tlie ventricle. For example, if there is any impediment to the flow of blood along the pulmonary artery, either owing to mechanical obstruction or to diminished force of the ventricle, the reflux is manifested by a kind of pulsation in the veins, which Haller has called venous pulse. The blood having attained the right ventricle by the effort exerted by the contraction of the auricle, and by the aspiration exerted by the dilatation of the cavity through the agency of its elastic structure, the ventricle contracts. Into it there are but two apertures, the auriculo- ventricular, and the mouth of the pulmonary artery. By the former, much of the blood cannot escape, owing to the tricuspid valve, Avhich acts like the sail of a ship,^ — the blood distending it as the wind does a sail, and the chordas tendinece retaining it in position, so that the greater part of the blood is precluded from reflowing into the auricle. This auriculo-ventricular valve is not, however, as perfect as that of the left heart. The observations of Mr, T. W. King^ show, that whilst the structure of the mitral valve is adapted to close completely all commu- nication between the left auricle and left ventricle during the contrac- tion of the latter, that of the tricuspid valve is designedly calculated to permit, when closed, the flow of a certain quantity of blood into the auricle. The comparatively imperfect valvular function of the tricuspid was shown by various experiments on recent hearts, in which it was found, that fluids, injected through the aorta into the left ven- tricle, were perfectly retained in that cavity by the closing of the mitral valve; but when the right ventricle was similarly injected through the pulmonary artery, the tricuspid valves generally allowed the escape of the fluid in streams more or less copious, in consequence of the incom- plete apposition of their margins. This peculiarity of structure in the tricuspid Mr. King regards as an express provision against the mis- chiefs, that might result from an excessive afflux of blood to the lungs, — thus acting as a safety valve, and being more especially ad- vantageous in incipient morbid enlargements of the right ventricle. The only other way the blood can escape from the right ventricle is by the pulmonary artery, the sigmoid valves of which it raises. These had been closed like flood-gates, during the dilatation of the ventricle ; but they are readily pushed outwards by the columns transmitted from the ventricle. Such is the circulation through one heart, — the ^jw/wonz'c. The same explanation is applicable to the other, — the sysleitnic ; and hence it is, that the structure, as well as the functions of the heart, is so much better comprehended, by conceiving it to be constituted of two essen- tially similar organs. The above description is that which is usually given of the circula- tion through the heart. There is great reason, however, for the belief, that too much importance has been assigned to the distinct contraction of the auricles. If we examine their anatomical arrangement we dis- cover, that there are no valves at the mouths of the great veins which open into them, and that although in the proper auricle or dog's ear ' Sir C. Bell, Animal Mechanics — Library of Useful Knowledge, p. 36. ^ Guy's Hospital Reports, No. iv. for April, 1837. 892 CIRCULATION portion muscular fibres and columns exist, — somewhat analogous to those of the columnas carnea3 of the ventricles, and probably destined for similar uses, — the parietes of the main portions of the auricles, — those that constitute the venous sinuses are but little adapted for ener- getic contraction. In experiments on living animals observation shows, that the rhythmic acts of dilatation and contraction are more signally exhibited by the ventricle, and, moreover, in some monsters the auri- cles are wanting, and in birds very small. M. d'Espine considers the auricles, in receiving or transmitting blood, to have only ar vermicular motion, not one of contraction ; and in a case of monstrosity, described by Dr. T, Eobinson,' of Petersburg, Virginia, no distinct systole and diastole of the auricles could be detected. Besides, if we admit both an active power of dilatation and contraction in the ventricles, any similar action of the auricles would seem to be superfluous. In the state of active dilatation of the ventricles, the blood is drawn into their cavities; and as soon as they enter into contraction, the auriculo- ventricular valves prevent the farther entrance into them of blood arriving in the auricles by the large veins ; and give occasion to the distension of the auricles; in this way, the dilatation of the auricles, sjmchronous with the contraction of the ventricles, is accounted for. As soon as the ventricle has emptied itself of its blood, it dilates actively ; the blood then passes suddenly from the auricle into its cavity through the auriculo- ventricular opening. From careful experiments instituted by Drs. Pennock and Moore,' they drew the following conclusions, which have been confirmed by the observations of others, and merit universal assent. The ventricles contract and the auricles dilate at the same time, occupying about one- half of the whole time required for contraction, diastole, and repose. Immediately at the termination of the systole of the ventricle, its diastole occurs, occupying about one-fourth of the whole time, syn- chronously with which the auricle diminishes, by emptying a portion of its blood into the ventricle, but without muscular contraction. The remaining fourth is devoted to the repose of the ventricles, near the termination of which the auricle contracts actively, with a short, quick motion, thus distending the ventricles with an additional quantity of blood : this motion is propagated immediately to the ventricles, and their systole follows so rapidly as to make the contraction of auricle and ventricle almost continuous. From the termination of their dias- tole to the commencement of the s_ystole, the ventricles are in a state of perfect repose ; their cavities remaining full but not distended ; whilst those of the auricles are partially so, during the whole time. It appears probable, that the great use of the auricles — in Avhich we include the sinuses — is to act as true gulfs for the reception of the blood proceed- ing from every part of the body ; and that little effect is produced on the circulation by their varying condition.^ ' American Journal of the Medical Sciences, No. xxii. for February, 1833. ^ Medical Examiner, Nov. 2, 1839, and American Medical Intelligencer, Dec. 16,1839, p. 277. " See, on tliis subject, Elliotson's Human Physiology, p. 174, Lond., 1840, and Hiffel- sheiui, Comptes Rendus et Mcmoires de la Societe de Biologic, Annee 1854, p. 273. IN THE HEART — SOUNDS. 893 The state of tlie heart in which the ventricles are dilated is termed Diastole ; that, in which they are contracted, Systole. Since the valuable improvement, introduced by Laennec in the dis- crimination of diseases of the chest by audible evidences, it has been discovered, that the heart is not in a state of incessant activity, but has, like other muscles, its intervals of repose. If we apply tlie ear or the stethoscope to the precordial region, we hear, first, a dull, length- ened sound, which, according to Laennec,' is synchronous with the arterial pulse, and is produced by the contraction of the ventricles. This is instantly succeeded by a sharp, quick sound, like that of the valve of a bellows, or the lapping of a dog. To convey a notion of these sounds, Dr C. J. B. Williams employs the word luhb-dup or luhh- tuh ; — the first word of the compound expressing the protracted first sound, and the latter the short second sound. The latter sound corre- sponds to the interval between two pulsations, and, according to Laen- nec, is owing to the contraction of the auricles. The space of time, that elapses between this and the sound of the contraction of the ventricles, is the period of repose. The relative duration of these periods is as follows : — one-half, or somewhat less, for the contraction of the ventricles ; a quarter, or somewhat more, for the contraction of the auricles ; and the remaining quarter for the period of total cessa- tion from labour. So that in the twenty four hours the ventricles work twelve hours, and rest twelve ; and the auricles work six, and rest eighteen. The following table by Messrs. Kirkes and Paget^ exhibits the difibr- ent actions of the heart, and their coincidence with the sounds and impulse of the organ. It presumes, that the period from the com- mencement of one pulsation to that of another — or that occupied by a complete set of the heart's actions — is divided into eight parts ; and if the case of a person, whose pulse beats sixty times in a minute, be assumed, each of these joarts will represent the eighth part of a second. EIGHTHS OF A SECOND. Last part of the pause, . 1. Auricles contracting: Ventricles distended. First sound and impulse, . 4. Ventricles contracting : Auricles dilating. Second sound, . . .2. Ventricles dilating: Auricles dilating. Pause, . . . .1. Ventricles dilating: Auricles distended. Or it may be better exhibited in the following table. A series of the heart's actions {rhytlim)] — Time = 4. First or inferior sound. Second or superior sound. Interval or pause. Time = 2. Time = 1 . Time = 1 . Ventricular contraction and First stage of ventricular dila- Short repose, followed by auricular dilatation. tatiou. contraction of auricles. Impulse. Second stage of ventri- cular dilatation. The view of Laennec in regard to the second sound is manifestly erroneous. Ocular observation on living animals, as Dr. Alison-' has ' A Treatise on the Diseases of the Chest, translated by Dr. Forbes, 4th edit., Lond., 1834. ^ Manual of Physiology, 2d Amer. edit., p. 75, Loud., 1853. * Outlines of Physiology, Loud., 1831. 394 CIRCULATION" remarked, shows that the emptying of the auricle precedes that of the ventricle, and that the interval of rest is between the contraction of the ventricle and the next emptying of the auricle : between the contrac- tion of the auricle and that of the ventricle, there is no appreciable in- terval. PucheltHhinks it most probable, that the first sound is caused by the impulse of the blood against the walls of the ventricle daring the contraction of the auricles, and the second by the impulse of the blood against the commencement of the arteries during the contraction of the ventricles. In regard to the first sound, M.Beau'^ — and M. Val- leix^ accords with him — agrees pretty nearly with Puchelt. He ascribes it to the wave of blood striking against the parietes of the ventricles during the ventricular diastole. The second sound he ascribes, how- ever, to the shock of the column of blood arriving by the veins against the parietes of the auricles. M. d'Espine thinks, that the first sound is produced by the contraction of the ventricles, and that the second is owino; to their dilatation.'' Our knowledge of the causes of the sounds of the heart is, indeed, sufficiently imprecise ; as is farther proved by the circumstance, that M. Magendie ascribed the first sound to the shock or impulsion of the apex of the heart during its diastole, and the second to the impulsion of the base of the heart during its systole; but the results of more recent experiments^ led him to infer, that the first sound is owing to the contraction of the ventricles, and the impulse of the apex of the heart against the ribs; and the second to a similar impulse of the anterior part of the heart, produced by their dilatation. Dr. Billing^ and M. Eouanet^ ascribe the first or dull sound to the shock or impulse of the tricuspid and mitral valves against the auriculo- ventricular orifices; and the second or clear sound to the succussion of the blood in the dis- tended aorta and pulmonary artery backwards against the semilunar valves, during the dilatation of the ventricles; and a similar opinion is entertained by Dr. Hope and by Messrs. Mayo* and Bouillaud.^ In evidence that the first sound is due to the tension of the auriculo-ven- tricular valves, M. Valentin^" states, that if a portion of a horse's intes- tine tied at one end be moderately filled with water, without any admixture of air, and have a syringe containing water adapted to the other end, the first sound of the heart will be exactly represented by forcing more water in. It may be distinctly heard with the stethoscope applied near the tied extremity of the intestine, at the instant the water from the syringe renders it tense. Mr. Carlisle^^ and Dr. Williams^^ ' System der Medicin., th. i. Auflage 2te, s. 149, Heidelb., 1S35. 2 Archiv. General, de Med., Dec, 1835, Janvier, 1839, Juillet, 1841. ^ Guide du Medecin Praticien, torn. iii. p. 34, Paris, 1843. * Revue Medicale, Oct., 1831. ^ Annales des Sciences Naturelles, 1834. . ^ Lancet, May 19, 1832. See, also, First Principles of Medicine, 5th Eng. edit., p. xx., Lond., 1849,or 2d Amer. edit., Philad.,1851 ; and Practical Observations ou Diseases of the Lungs and Heart, p. 11, Lond., 1852. ' Ibid., No. xcvii. ; and Journal Hebdomadaire, Sept., 1832. ^ Outlines of Human Pathology, p. 465, Lond., 1836. 9 Journal Hebdomad., No. ix., 1834. '" Lehrbuch der Physiologie des Menschen, i. 427, Braunschweig, 1844. " Report of the Third Meeting of the British Association for the Advancement of Science; and Amer. Journal of the Med. Sciences, p. 477, for Feb., 1835. '^ A Rational Exposition of the Physical Signs of Diseases of the Lungs and Pleura, Amer. edit., Philad., 1830. IN THE HEART — SOUNDS. 395 refer tlie first sound, with Laennec, to the systole of the ventricles, and the second to the obstacle presented by the semilunar valves to the return of the blood from the arteries into the heart, — and Messrs. Corrigan,^ Pigeaux,^ Stokes,^ and Mackintosh," think the first sound is owing to tlie systole of the venous sinuses, and the second to the systole of the ventricles — an opinion, which Burdach^ thinks is best founded, but which, as we have seen, is manifestly erroneous. In a case of ectopia cordis, described by M. Cruveilhier,^ a distinct vibratory thrill was perceived, by applying the finger to the origin of the pulmonary artery, which corresponded with the ventricular systole; but no such thrill could be felt when the finger was applied to any part of the base of the ventricles. He inferred, therefore, that the first sound cannot be dependent upon the action of the auriculo-ventricular valves. The greatest intensity of the first sound was, indeed, in the same situ- ation as the greatest intensity of the second — that is, at the origin of the large arteries. Dr. Carpenter'^ thinks the results of these observations of Cruveilliier clearly establish, that the principal cause of the first sound exists at the entrances to the arterial trunks ; and it does not seem to him, that any other reason can be assigned for it than the pro- longed rush of blood through their orifices, and the throwing back of the semilunar valves, which, in suddenly flapping down again, produce the second sound. M. Cruveilliier states it, in his opinion, to be a uni- form occurrence, that disease of the semilunar valves modifies both sounds; — a fact, which the author has long noticed. Without express- ing an opinion as to the validity of M. Cruveilhier's conclusion re- specting the two sounds of the heart. Dr. Forbes evidently regards it with favour, under the view long maintained by him, that although characteristically difi:erent, the two sounds have so great a similarity, and are so allied in time and place, that he could not readily bring his mind to believe, that they do not both depend upon one and the same cause slightly modified ; or at least on the different play of the same parts.^ Drs. Pennock and Moore,^ who agree in the main with Dr. Hope, found the first sound, the impulse, and the systole of the ventricles to be synchronous ; and the second sound to be synchronous with the diastole of the ventricles. The first sound, they suggest, may be a combination of that caused by the contraction of the ventricles, the flapping of the auriculo-ventricular valves, the rush of blood from the ventricles, and the sound of muscular contraction. In four of their experiments, when the heart was removed from the body, the ventri- cles cut open and emptied of their contents, and the auriculo-ventricular valves elevated, a sound resembling the first was still heard, which ' Dublin Med. Trans., vol. i., New Series. ^ Bulletin des Sciences Medicales, par Ferussac, xxv. 272. ^ Edinb. Med. and Surg. Journal, vol. xxxiv. * Princi^jles of Pathology, &.C., 2d Amer. edit., ii. 6, Pliilad., 1837. ^ Die Physiologic als Erfahrungswissenschaft, iv. 219, Leipz., 1832. ^ Gazette Med. de Paris, 7 Aout, 1841, p. 535 ; or Brit, and For. Med. Review, Oct. 1841, p. 535. ^ Human Physiology, § 486, Loud., 1842, and 5th Amer. edit., p. 477, Philad., 1853. * Translation of Laennec, 4th edit. ; and Brit, and For, Med. Review, loc. cit. * Ox>. citat. 896 CIECULATION' they attributed chiefly to muscular contraction. The second sound they referred exclusively to the closure of the semilunar valves by the refluent blood from the aorta and pulmonary artery. " This," they remark, " is proved by the greater intensity of this sound over the aorta than elsewhere, the blood having a strong tendency to return through the valvular opening; by the greater feebleness of the sound over the pulmonary artery, which is short, and soon distributes its blood through the lungs, thus producing but slight impulse upon the valves in the attempt to regurgitate; by the disappearance of the sound when the heart becomes congested and contracts feebly; and finally, on account of its entire extinction when the valve of the aorta was elevated." The main results of the experiments of Drs. Pennock and Moore accord closely with what the author has entertained and taught on this subject; but the views of M. Cruveilhier are well worthy of attention. The whole matter is still open for further investigation. A case of thoracic ectopia has been published by M. Monod,^ in which the maxi- mum intensity of the first sound did not occur at the base of the ven- tricles, but at the middle of their fleshy walls; and M. Monod thinks, that it was caused by the shock of the walls of the ventricles against the internal fleshy columns at the moment of contraction. As to the second sound, he is of opinion, that it was owing to the return of the wave of blood against the semilunar valves. The mechanism by which the valves of the heart are closed, and its sounds produced, has been subjected to fresh investigation by Baum- garten, and subsequently by Hamernjk,^ and others. According to them, there is, during the systole of the auricles, very little regurgi- tation into the venous trunks, owing, in part, to an arrangement of circular muscular fibres surrounding their openings into the auricles, as well as to the other causes generally admitted. The auriculo-ven- tricular valves — they conceive — are closed by the counterpressure of the ventricular blood, such counterpressure being suddenly developed by the contraction of the auricles. The cavities of the auricles and ventricles, during the diastole of the heart, are distended by the contin- uous current from the veins; and at this period the valves are floating in the blood in the form of a funnel. The object of the auriculo-ven- tricular systole is to induce such a degree of tension in the contents of the Ventricles, and of necessity in the blood surrounding the funnel- shaped arrangement of the valves, as to cause their rapid closure and prevent regurgitation. Such closure is not due to the contraction of the musculi papillares, but is much facilitated by the small specific gravity of the valves, which enables them to float on the surface of the blood. The mechanism, by which the valves of the arteries are closed, is similar to that of the auriculo-ventricular valves. Immediately on the contraction of the ventricles, the pressure of the blood, contained in the large arterial trunks, acting equally in all directions, produces ' Ballet, del. Academ. Royale de Med., 7 Fevrier, 1843; cited in Edinb. Med. and Surg. Journal, July, 1843. ^ Edinburgh Monthly Journal for .Tan., 1840, cited from Prager Vierteljalirschrift, 1847 and 3 848 ; see also Schmidt's Jahrbiicher, No. 1, S. 10, Jahrgang 1848, and No. 5, S. 151, Jahrgang 1849. IN THE HEART — SOUNDS. 897 tlie closure of the semilunar valves, — their complete closure occurring synchronously with the end of the ventricular systole. When the diastole of the ventricle commences, the arterial retraction begins, and the refluent blood from the large arteries falls on the valves already closed, and causes the second sound; but there is no regurgitation, as there necessarily would be — M. llamernjk maintains — 'Were t]]e valve shut out by the returning wave of blood. The first sound, according to this view, is occasioned by the vibration of the tense auriculo-ven- tricular valves, caused by the blood forced against them in the systole of the ventricles, and the vibration of the chordas tendineie. In like manner, the second sound is produced by the impulse of the blood on tlie semilunar valves already shut, and not by their closure, as usually supposed. The following table, compiled in part by ISIM. Barth and Roger,' — to which additions have been made by M. Berard^ and the author — affords at a glance the discordant opinions entertained by observers in regard to this important topic of physiology, — an accurate knowledge of which is essential to the correct understanding: of cardiac diseases. Laennec,' TCKNEE," corrigan,^ Makc D'Espixe,^ PlGEAUX,' 1830, PlGEAUX,^ 1839, H0PE,9 1831, Hope,'" 1839, Billing," Ror- ANET,'^ AND Bi,CLAED,"* FIRST SOUNB CAUSED BY Ventricular contraction. Do. Sliock of the blood against the ventricular parietes during the diastole. Ventricular contraction. Shock of the blood against the ventricular parietes at the moment of the diastole. Friction of the blood against the parietes of the ventri- cles, the orifices and parietes of the great vessels, at the moment of the systole. Molecular collision of the blood in the systole. Sound of tension of the auricn- lo-ventricular valves, sound of muscular extension, ro- tatory sound in the systole. Clacking of the auriculo-ven- tricular valves in the systole. SECOND SOUND CAUSED BY Auricular contraction. Shock of the heart falling back upon the pericardium during the diastole. Reciprocal shock of the internal surface of the opposite pa- rietes of the ventricles during the systole. Ventiicular dilatation. Shock of the blood against the Ijarietes of the aorta and pul- monary artery at the moment of the systole. ' Friction of the blood against the parietes of tlie auricles, the au- riculo-ventricular orifices, and the cavity of the ventricles, at the moment of the diastole. ( Molecular collision of the blood ( in the diastole. (Clacking of the semilunar valves in the diastole. Do. ' Traite Pratique d'Auscultation, &c., 2de edit., p. 359, Paris, 1844. ^ Cours de Physiologic, iii. (5(57, Paris, 1851. 3 Auscultation Mediate, ii. 399, Paris, lS2(j. ■» Edinburgh Medico-Chirurgical Transactions, iii. 205. ^ Dublin Medical Transactions, New Series, i. 151, Dublin, 1830. ® Journ. Hebdomad, de Med., iv. 115, Paris, 1831. ' Ibid., iii. 238, and v. 187, Paris, 1831. s Traite des Maladies du Coeur, p. 49, Paris, 1839. ^ A Treatise on Diseases of the Heart, 1st edit., Lond., 1831. '0 Ibid., 3d edit., Lond., 1839 ; or 2d Amer. edit., Philad., 1846. " Op. cit. '2 Theses de Paris, 1832, No. 252. '3 Traite Elementuire de Physiologic, p. ISS, Paris, 1855. 398 CIRCULATION PlOEEY,' PltDAGXEL,^ Carlisle,' Magexdie,* BCEDACH,'' bocillacd,^ Gexdrix,'' Ckcyeilhier,^ Skoda,' Beau,'" C.J. B.Williams," DrBLiN COJIMITTEE,'^ FIRST SOrXD CAUSED BY Friction of the molecules of the blood agaiust each other, and against the parietes of the ventricles, the orifices, and the valves, during the sys- tole of the left ventricle. Contraction of the left ventri- cle. Irruption of the blood into the arteries during the systole. Shock of the apex of the heart agaiust the thorax at the moment of the systole. Irruption of the blood into the ventricles containing air (.'') at the moment of the con- traction of the auricles. Sudden tension (redrcssement) and shock of the opposed sur- faces of the auriculo-ven- tricular valves, and sudden depression of the semilunar valves during the systole. Vibrations resulting from the collision of the blood in the systole. Sudden tension (redressement) of the semilunar valves by the systole. First ventricidar sound. Shock of the blood against the au- riculo-ventricular valves ; impulsion of the aj^ex of the heart against the thorax. First arterial sound. Shock of the blood against the parie- tes of the aorta, and of the pulmonary artery in the systole. Shock of the •wave of blood against the parietes of the ventricles in the systole of the auricles. Muscular contraction of the ventricles during the sys- tole. Friction of the blood against the parietes of the ventri- cles, and muscular contrac- tion during the systole. SECOND SOUND CAUSED BY Passage of the blood into the right cavities. Into what parts ? At what moment ? Contraction of the right ventii- cle. Clacking of the semilunar valves iu the diastole. Shock of the anterior surface of the heart at the moment of the diastole. Projection of the blood into the arteries containing air (?) at the moment of the systole. Tension {redressement) of the semilunar valves, and shock of their opjwsed surfaces, and sudden depression of the au- riculo-ventricular valves at the moment of the diastole. Percussion of the blood against the parietes of the ventricles at the moment of the diastole. Depression of these valves at the moment of the diastole. Second ventricular sound. Shock of the column of blood against the parietes of the ventricles in the diastole. Second arterial sou7id. Retro- grade shock of the column of blood upon the semilunar valves. Shock of the column of. blood, arriving by the veins against the parietes of the auricles. Keturn shock of the columns of blood against the semilunar valves during the diastole. Tension of the semilunar valves, and return shock of the co- lumns of blood during the diastole. ' Archives Generales de Medecine, 2de serie, v. 245. 2 L'Union Medicale, p. 588, Paris, 1849. "' Dublin Journal of Medical Science, iv. 84, Dublin, 1834. "■ Mem. de TAcad. des Sciences, xiv. 155, Paris, 1838. ^ Die Physiologic als Erfahrungswissenschaft, iv. 219, Leipzig, 1S32. « Traite Clinique des Maladies du Cceur, i. 115. ' Le ons sur les Maladies du Coeur, i. 54. ** Gaz. Medicale, p. 497, Paris, 1841. 8 Medicinisch. Jahrbiich. des Oester. Staat., xxii. 227. '0 Archiv. Gen. de M 'd., 2de sJrie, ix. 389. " Edinb. Med. and Surg. Journ., xxxii. 297, and xxxiii. 333. See, also, his Lectures on the Physiology and Diseases of the Chest, Amer. edit., Philad., 1839; and A Prac- tical Treatise on the Diseases of the Respiratory Organs, edited by Dr. Clymer, p. 73, Philad., 1845. '^ Dublin Journal of Medical Science, viii. 154. IN THE HEAET — SOUNDS. 399 London Committee,' Pennock and MOORE,^ Earth and ROGER,^ Baumgarten and Hamernjk* FIRST SOUND CAUSED BY Sudden muscular tension of the ventricles in the sys- tole, and shock of the heart against the thorax. Muscular contraction of the ventricles and clacking of the auriculo-ventricular valves during the systole. Contraction of the ventricles : shock at the inferior surface of the semilunar valves, and at the base of the aortic and pulmonary columns of blood ; clacking of the au- riculo-ventricular valves ; and impulse of the heart against the chest. C The vibration of the tense auriculo-ventricular valves acted on by the blood sent against them during the systole of the ventricles, and the vibration of the chordae tendineae. SECOND SOUND CAUSED BY Sudden occlusion of the semi- lunar valves by the arterial columns of blood. Occlusion of the semilunar valves by the return shock of the arterial columns of blood. Tension of the semilunar valves ; and return shock of the blood on their concave surface. The impulse of the blood on the semilunar valves already shut, not by their closure. It has been a question with physiologists, whether the cavities of the heart completely empty themselves at each contraction. Senac/ and Thomas Bartholine,'' from their experiments, were long ago led to answer the question negatively. On the other hand, Haller^ enter- tained an opposite opinion, — suggested, he remarks, by his experi- ments; but, perhaps, notwithstanding all his candour, connected, in some manner, with his doctrine of irritability, which could not easily admit the presence of an irritant in a cavity that had ceased to con- tract. It has been remarked by M. Magendie,^ that if we notice the heart of a living animal, whilst it is in a state of action, it is obvious, that the extent of the contractions cannot have the effect of completely emptying the ventricles; but it must, at the same time, be admitted, that such experiments are inconclusive, inasmuch as they exhibit to us the action of the organ under powerfully deranging influences, and such as could be readily conceived to modify materially the extent of the contractions. The same may be said of a case of monstrous foetus observed by Dr. Thomas K. Mitchell.^ After each contraction of the ventricle he was able to make blood pass into the aorta. If the heart of a frog be examined by cutting out the lower portion of the sternum, owing to the transparency of tlie parietes of the heart, it can be ob- served that the ventricle completel}^ empties itself at each contraction; but Dr. Mitchell is decidedly of opinion, that the frog is not a fit sub- ject from which to draw a conclusion, and agrees with Mr. Carlisle, that the cavities empty themselves more completely in the lower order of animals than in the higher. These observations, however, are in- ' Lond. Med. Gaz., xix. 360. ^ Am. Joum. of the Med. Sci., xxv. 415. 3 Op. cit. ■* Op. cit. ^ Traiti de la Structure du Coeur, &c., 2de 6dit., Paris, 1774. ^ Dissertat. de Corde, Hafn., 1648. '' Element. Physiol.,' lib. iv. sect. 4, §7, Lausann., 1757. ^ Precis, &c., torn. ii. ^ Dublin Journal of Medical Science, Nov., 1844, p. 275. '400 CIRCULATION sufficient to prove, that whilst an animal is in a normal condition, the auricles and veutricles are not emptied of their contents by their con- traction. The objection urged against the opposite view, that there would always be stagnant blood in the cavities of the heart, is not valid. The experiments of Venturi^ have shown, that even in an ordinary hydraulic apparatus, the motion of a stream passing through a vessel of water is commuuicated to the fluid at rest in the vessel, so that an incessant change is produced. During the systole of the heart, the organ is suddenly carried for- ward; and although it appears to be rendered shorter, its point or apex is generally considered to strike the left side of the chest opposite the interval between the fifth and seventh true ribs; producing what is called the "beating or impulse of the heart." The cause of this phe- nomenon was, at one period, a topic of warm controversy. Borelli,^ Wiuslow, and others, affirmed, that it was owing to the organ being elongated during contraction; but to this it was replied by Bassuel,^ that if such elongation took place, the tricuspid and mitral valves, kept down by the columnte carnea3, could not possibly close the openings between the corresponding auricles and ventricles. Experiments by Drs. Pennock and Moore" exhibited to them, that the expulsion of the blood from the ventricles was effected by an approximation of the sides of the heart, and not by a contraction of the apex towards the base ; and that, during the systole, the heart performs a spiral movement, and becomes elongated. Senac^ ascribed the beating of the heart to three causes, and his views have been adopted by most physiologists: — 1, to the dilatation of the auricles, Avhich occurs during the contraction of the ventricles; 2, to the dilatation of the aorta and pulmonary arteiy by the introduction of blood sent into them by the ventricles; and '6, to the straightening of the arch of the aorta, owing to the blood being forced against it by the contraction of the left ventricle. Dr. William Hunter® considered the last cause quite sufficient to explain the phe- nomenon, and many physiologists have assented to his view. Sir David Barry^ instituted some experiments upon this subject. He opened the thorax of a living animal, and by passing his hand into the cavity, endeavoured to ascertain the actual condition of the heart and great vessels, as to distension and relative position. He performed seven experiments of this kind, from which he concluded, that the vena cava is considerably increased in size during inspiration, which he ascribes, as will be better understood hereafter, to the partial vacuum formed in the chest. He supposes that the force exerted by the venous blood on entering the heart, in consequence of the expansion of the chest and the great vessels behind the heart, pushes the organ forwards, and thus causes it to strike against the ribs. Dr. Corrigan thinks, ' Sur la Communication Laterale du Jlouvement dans les Fluides, Paris, 1798 ; and Sir C. Bell, Animal Mechanics, p. 35, Library of Useful Knowledge, Lond., 1829. ^ De Motu Animalium, Lugd. Bat., 1710. ^ Magendie, Precis, &c., ii. 395. * Med. Examiner, Nov. 2, 1839. * Traite de la Structure du Coeur, &c., Paris, 1749. " .John Hunter, Treatise on the Blood, p. 146, Lond., 1794. '' Exper. Researches on the Influence of Atuiosiiheric Pressure upon the Circulation, Lond., 1826. IN THE HEART — IMPULSE. 401 that tlie apex of the heart has nothing to do with the impulse. He is of opinion that the heart acts like any other muscle, — that as soon as the ventricles contract, it is shortened from below upwards, and by this shortening becomes thickened in the middle, in a similar manner to the thickening of the belly of the biceps muscle, which, wlien it contracts, gives rise to an evident impulse, plainly perceptible to the hand applied to it; and that in like manner the heart's impulse is owing to the body of the ventricles, and not to the apex, striking against the ribs. Dr. Corrigan's view is considered by l)r. T. E. Mitchell,' to be confirmed by the phenomena observed by him on a foetus born with the left side of the thorax wanting; and in which the action of the heart could be closely observed. Drs. Pennock and Moore,^ however, in their experi- ments, found that the impulse was synchronous with and caused by the contraction of the ventricles, and when felt externally, arose from the striking of the apex against the thorax. In the celebrated case, too, of the son of Yiscount Montgomery, detailed by Harvey,^ where there was an opportunity of inspecting the movements of the heart, it was particularly observed, "that in the diastole thef organ was re- tracted and withdrawn ; whilst, in the systole, it emerged and protruded ; and the systole of the heart took place at the moment the diastole or pulse in the wrist was perceived : to conclude, the heart struck the walls of the chest, and became prominent at the time it bounded up- wards and underwent contraction on itself." To show, how^ever, that this apparently simple matter cannot be considered settled. Professor Miiller'' thinks that great uncertainty rests as to whether the impulse is produced during the contraction or the dilatation of the ventricles; yet it certainly cannot occur during the first stage of ventricular diastole. In proof, however, that the impulse of the heart is dependent on the contraction of the muscular fibres of the ventricles, the experiments of Valentin* may be cited. He cut off the apex of the heart in several cases, so that the resistance of the blood and the great vessels, and the supposed consequent recoil, were prevented; yet the tilting movement was observed as much as when the heart was entire. It has even been supposed that the impulse is produced by the blood sent into the ven- tricles by the contraction of the auricles, but it must be borne in mind, in the inquiry, that there is no appreciable interval between the con- traction of the auricles, and that of the ventricles; and that, therefore, both may be concerned.^ The systole of the heart is admitted by all to be active. Some are disposed to think the diastole passive, — that is, the efi'ect of relaxation of the fibres, or the cessation of contraction. Pechlin, Perrault, Ham- berger, d'Espine, Alison, and numerous others, have supported an oppo- site view; — affirming that direct experiment on living animals shows, that positive eflbrt is exerted at the time of the dilatation of the cavi- ' Dublin Journal of Med. Science, Nov., 1844, p. 271. ^ Op. citat. ^ The works of William Harvey, M. D., &c.,p. 384, Sydenham Society's edit., Loud. 1847. * Handbuch, u. s. w., Baly's translation, p. 175, Lond., 1838. ' Lehrbuch der Physiologie des Menschen, i. 427. ® See, in favour of the view, that the impulse is attributable to the diastole of the ventricle. Hardy and Behier, Pathologic Interne, i. 326, Paris, 1844 ; and Dr. A. Stille, Amer. Journ. of tlie Medical Sciences, July, 1846, p. 174. VOL. I. — 2(5 402 CIRCULATION ties; — a view confirmed by the case of monstrosity related by Dr. Eobinson,^ His opinion is, that the force of the diastole was in that case equal to, if not greater than, that of the systole. In the case, too, observed by M. Cruveilhier, the diastole had the rapidity and energy of a very active movement, overcoming pressure made upon the heart, so that the hand, closed upon it when it was contracted, was opened with violence. It has been suggested, that if the course of all the fibres composing the muscular parietes of the organ were better known, this apparent anomaly might, perhaps, be as easily explained as in the ordinar}^ case of antagonist muscles. It is probable, however, that the active force exerted in the dilatation of these cavities is that of elasti- city ; and when the contraction of the muscular fibres has ceased, this is aroused to action, and promptly restores the organ to its previously dilated condition. According to this view, the natural state would be that of dilatation. In treating of this subject. Dr. Carpenter^ suggests whether there may not exist in muscle an active force of elongation, as well as an active force of contraction, arising from the mutual re- pulsion of particles whose mutual attraction is the occasioning of the shortening.p] The cause of the heart's action has been a deeply interesting ques- tion to the physiologist, and, in the obscurity of the subject, has given rise to many and warm controversies. From the first moment of foetal existence, at which the organ becomes perceptible, till the cessation of vitality it continues to move. By many of the ancients this was sup- posed to be owing to an inherent pulsijic virtue,'^ which enabled it to contract and dilate alternately, — a mode of expression, which, in the infanc}'' of physical science, was frequently employed to cover ignorance, and has been properly and severely castigated by Moliere : — " Mihi a docto doctore Domaudatur causani et rationem quare Opium facit dormire. A quoi respondeo ; Quia est in eo Virtus clormitiva, Cujus est natura Seusus assoupire." Le Malade Imaginaiee, Intermede iii. It was in ridicule of the same failing that Swift represented the action of a smokejack to be depending on a meat-roasting power.'' Descartes* imagined that an explosion took place in the ventricles as sudden as that of gunpowder. With equal nescience, the phenomenon was as- cribed by Yan Ilelmont^ to his imaginary archa^us ; and by Stahl,' and the rest of the aniniists, to the anima^ soul or intelligent principle, which he supposed to preside over all the mental and corporeal phe- nomena. Stahl was one of the first that attempted any rational expla- nation of the heart's action. Its muscular tissue; the similarity of its ' Amer. Journal of the Medical Sciences, No. xxii., Feb., 1833. * Principles of Human Physiology, Amer. edit., page 24.9, Philad., 1855. * Haller, Elementa Physiologise, lib. iv. sect. v. § 1. « Fletcher, Rudiments of Physiology, P. ii. a., p. 52, Edinb., 1836. 5 Ti-act. de Homiue, p. 1()7, Amst., 1677. * Ortus Medicin. &c., Amstel., 1648. ' Theoria vera Medica, Hal., 1737. IN THE HEART. 403 contractions to tliose of ordinary muscles, with the exception of their not being voluntary ; the fact of its action being modified by the pas- sions, &c., led him to liken its movements to those of muscles. He admitted, that, generally, we possess neither perception of, nor power over, its motions; but he affirmed, that habit alone had rendered them involuntary ; in the^ same manner as certain muscular twitchings or tics^ which are at first voluntary, may become irresistible by habit. A strong confirmation of this opinion was drawn from the celebrated case of the honourable Colonel Townshend, (called by M. Adelon^ and other French writers, Captain Towson,) who. was able, (not all his life, as Adelon asserts, but a short time before his death,) to suspend the movements of his heart at pleasure. This case is of so singular a cha- racter, in a physiological as well as pathological point of view, that we shall give it in the woi^ds of Dr. George Cheyne,^ one of tho physicians who attended him, and whose character for veracity is beyond suspicion. "Colonel Townshend, a gentleman of excellent natural parts, and of great honour and integrity, had, for many years, been afilicted with constant vomitings, which had made his lite painful and miserable. During the whole time of his illness he had observed the strictest re- gimen, living on the softest vegetables and lightest animal food; drinking asses' milk daily, even in the camp ; and foi' common drink Bristol water, which, the summer before his death, he had drunk on 'the spot. But his illness increasing, and his strength decaying, he came from Bristol to Bath in a litter, in autumn, and lay at the Bell Inn. Dr. Baynard, who is since dead, and I were called to him, and attended twice a day for about the space of a week : but, his vomit- ings continuing still incessant, and obstinate against all remedies, we despaired of his recovery. While he was in this condition, he sent for us early one morning; we waited on him with Mr. Skrine, his apo- thecary (since dead also); we found his senses clear, and his mind calm ; his nurse and several servants were about him. Ue had made his will and settled his aliairs. He told us he had sent for us to give him some account of an odd sensation he had for some time observed and felt in himself, which was that, composing himself, he could die or expire when he pleased, and yet by an effort, or somehow, he could come to life again; which it seems he had sometimes tried before he had sent for us. We heard this with surprise ; but as it was not to be accounted for from tried common principles, we could hardly be- lieve the fact as he related it, much less give any account of it ; unless he should please to make the experiment before us, which we were unwilling he should do, lest, in his weak condition, he might carry it too far. lie continued to talk very distinctly and sensibly above a quarter of an hour, about this (to him) surprising sensation, and in- sisted so much on our seeing the trial made, that we were at last forced to comply. We all three felt his pulse first; it was distinct, though small and thready ; and his heart had its usual beating. He composed himself on his back, and lay in a still posture some time. While I held his right hand, Dr. B. laid his hand on his heart, and ' Physiol, de I'Homme, edit, cit., iii. 302. * The English Malady, or Treatise of Nervous Diseases, p. 307, Loud., 1734. 40-1 CIRCULATION Mr. S. held a clean looking-glass to his mouth. I found his pulse sink gradually, till at last I could not feel any, bj the most exact and nice touch. Dr. Baynard could not feel the least motion in his heart, nor Mr. Skrine the least soil of breath on the bright mirror he held to his mouth. Then each of us, by turn, examined his arm, heart and breath, but could not by the nicest scrutiny discover the least symptom of life in him. We reasoned a long time about this odd appearance as well as we could; and all of us judging it inexplicable and unac- countable; and finding he still continued in that condition, we began to conclude indeed that he had carried the experiment too far, and at last were satisfied that he was actually dead, and were just ready to leave him. This continued about half an hour, by nine o'clock in the morning, in autumn. As we were going away, we observed some motion about the body, and upon examination found his pulse and the motion of his heart gradually returning; he began to breathe gently, and speak softly ; we were all astonished, to the last degree, at this unexpected change, and after some fuj'ther conversation with him, and among ourselves, went away fully satisfied as to all the par- ticulars of this fact, but confounded and puzzled, and not able to form any rational scheme, that might account for it. He afterwards called for his attorney, added a codicil to his will, settled legacies on his ser- vants, received the sacrament, and calmly and composedly expired about five or six o'clock that evening." Dr. Cleghorn, of Glasgow, knew an individual who could feign death, and had so completely the power of suspending, or at least of diminishing the action of the heart, that its pulsations were imper- ceptible; and the singular cases of the Fakeers, of India, which will be referred to hereafter, indicate — if they are to be credited at all — that somatic life may be scarcely or not at all distinguishable, whilst molecular life may persist; as is witnessed during the hibernation of animals. It is manifest that these cases — unaccountable as they are, in many respects — can add no weight to the views of the Stahlians. They are as strange, as they are inexplicable. The opinion, with them, that the heart's action is a muscular function was accurate. The error lay in placing it amongst the voluntary functions. It belongs to the involuntary class, equally with many of the muscles concerned in deglutition, and those of the stomach and intestines ; and how well is it for us, as Sir Charles Bell has remarked, that its action as well as that of other organs directly instrumental to the organic functions is placed out of our control! "A doubt — a moment's pause of irresolution — a forget- fulness of a single action at its appointed time — would otherwise have terminated our existence." The doctrine of Haller' on the heart's action rested upon the vis insita or irrilability to which he referred all muscular contractions, voluntary and involuntary. This property, as stated in another ])lace, he conceived to be possessed by muscles as muscles, independently of all nervous influence. The heart, being a muscle, enjoyed it of neces- sity: and the irritant, which incessantly developed it, was the blood, ' Op. citat. % IN THE HEART. 405 In evidence of this, he observes, that its contractions are always more forcible and rapid, when the blood is more abundant; and that they occur successively in the cavities of the heart as the blood reaches them. So wholly did Ilaller assign the heart's action to this irritability, that he denied the nerves any influence over it; resting his belief on the admitted facts, — that it will continue to beat after decapitation ; after the division of the spinal marrow in the neck ; and of the nerves dis- tributed to the organ ; and, even after it has been entirely removed from the body. How far the opinions of this great man are correct, respecting the power of contraction residing in the heart, as he con- ceived it to do in other muscles, we shall inquire presently. It is, doubtless, indirectly under the nervous influence. We see it affected in the various emotions; sometimes augmenting violently, at others, retarding its action. These circumstances have led some to adopt a kind of intermediate opinion, and to regard the nervous influence as one of the conditions necessary for all muscular contraction, just as the due circulation of blood is: and to admit, at the same time, the separate existence of a vis insita. Sommering^ and Behrends^ have, indeed, asserted that the cardiac nerves are not distributed to the tissue of the heart, but merely to the ramifications of the coronary arteries ; and hence, that these nerves are not concerned in the motions of the organ, but only in its nutrition: but this special distribution is denied by Scarpa,-'' and the generality of anatomists. Although the emotions manifestly affect the heart, direct experi- ments exhibit but little influence over it on the part of the nerves. This, indeed, we have seen, is one of the grounds for the doctrine of Haller. Willis'' divided the eighth pair of nerves ; yet the action of the heart persisted for days. Similar results followed the section of the great sympathetic. M. Magendie^ states, that he removed, on several occasions, the cervical ganglions, and the first thoracic; but was unable to determine anything satisfactory from the operation, in consequence of the immediate death of the animal from such extensive injury. He observed, however, no direct influence on the heart.^ We have numerous examples of the comparative independence of the organ as regards the encephalon. Decapitated reptiles have lived for months; and anencephalous infants, or those born with part of the brain only, have vegetated during the whole period of pregnancy, and for some days after birth. M. Legallois^ kept several decapitated mam- malia alive ; and maintained the heart in action, (having taken the precaution to tie the vessels of the neck for the purpose of preventing hemorrhage,) by employing artificial respiration, so as to keep up the conversion of venous into arterial blood, and thus insure to the heart a supply of its appropriate fluid. We find, too, that in fracture of the skull, in apoplexy, and congenerous aftisctions, the functions of the ' Corpor. Human. Fabric, iii. § 32. ^ Dissert, qua Demoustrat. Cor Nervis Carere, Mogunt., 1792; and in Ludwigii Script. Neurol. Min., i. 1. ^ Tabulae Neurologicae, &c., Ticin., 1794. * Cerebri Anat., cap. xxiv. in Oper., Uenev., 177G. * Precis, &c., ii. 401. ^ Brachet, Physiologie Elementaire de rHomme, 2de edit., i. 142, Paris et Lyon, 1855. > ' 1 J , ' Sur le Principe de la Vie, p. 138. i 406 CIRCULATION heart are the last to be arrested. The result of his own experiments led Legallois to infer, that the power of the heart is altogether derived from the spinal marrow ; and he conceived, that through the cardiac nerves it is influenced by that portion of the cerebro-spinal axis, and is liable to be atfected by the passions because the spinal marrow is itself influenced by the brain. Dr. Wilson Philip' has, however, shown, that the facts do not warrant the conclusions; and has exhibited, by direct experiment, that the brain has as much influence as the spinal marrow over the motions of the heart, when the circumstances of the experiment are precisely the same. The removal of the spinal marrow, like that of the brain, if the experiment be performed cautiously and slowly, does not sensibly affect the motion of the organ, — the animal having been previously deprived of sensibility. In these experiments, the circulation ceased quite as soon without, as with, the destruction of the spinal marrow. Loss of blood appeared to be the chief cause of its cessation; and pain would have contributed to the same effect, if the animal had been operated on, without having been previously ren- dered insensible. Sir Benjamin Brodie'^ inferred, from his experiments, that the influ- ence of the, brain is not directly necessarj^ to the action of the heart; and that " when the brain is injured or removed, the action of the heart ceases only because respiration is under its influence, and if under these circumstances respiration be artificially produced, the circulation will still continue." Eespiration is however only indirectly under the influence of the brain; the nervous centre of that function being seated in the medulla oblongata. Mr. Clift,^ the former conservator of the Museum of the Royal Col- lege of Surgeons of London, made a series of experiments to ascertain the influence of the spinal marrow on the action of the heart in fishes, and found, that it continues long after the brain and spinal marrow are destroyed, and still longer when the brain is removed without injury to its substance. Similar results were obtained by Treviranus on the frog, and by Saviole on the chick in ovo. Zinn and Ent, too, found, that after the destruction of the cerebellum, to which Willis ascribed its action, it continued to beat. All these facts plainly exhibit, that, although the heart is indirectly influenced by the brain or spinal marrow, it is not directly acted upon by either one or the other, and that its action can be maintained for some time after the destruction of one or both, provided artificial respiration be kept up; and even this is unnecessary : it will continue to beat after it has been removed from the body. Dr. Dowler, of New Orleans,"* saw the heart of the alligator beat for seven hours when its " annexing vessels" had been separated. In the case of the rattlesnake, Dr. Harlan* observed it, torn from the body, continue its contractions for ten or twelve hours; and in the monstrous foetus, described by Dr. ' An Experimental Inquiry into the Laws of the Vital Functions, &c., p. 62, Lend., 1817. * Philosophical Transactions for 1811, and Physiological Researches, p. 15, Lond., 1851. 3 Philosoph. Transact, for 1S15. * Contrihutions to Physiology, p. 17, New Orleans, 1849. * Medical and Physical Researches, p. 103, Philad., 1835. IN THE HEART. 407 T. Eobinson/ its motion continued for some time after the auricles and ventricles had been laid open; the organ roughly handled, and thrown into a basin of cold water. "We are compelled, then, if we do not admit the whole of the Hallerian doctrine of irritability, to presume, that there is something inherent in the structure of the heart, which enables it to contract and dilate, when appropriately stimulated : and it is not even necessary that this should be by the fluid to which it is habituated. It is certain, that the organ, when separated from the body, may be stimulated to contraction, by being immersed in warm water, or pricked with a sharp-pointed instrument ; yet it is not pos- sessed of ordinary sensibility. In Harvey's celebrated case, before referred to, the subject of Avhich was presented to Charles IT., the ven- tricles were touched ; and " his most excellent majesty" — Harvey loy- ally observes — "as well as myself acknowledged that the heart was without the sense of touch; for the youth never knew when we touched his heart, except by the sight or the sensation he had through the external integument,"^ A similar experiment was made by Eicherand on a physician from whom he had removed a portion of the pleura and several ribs. In a case, too, of ectopia cordis in a calf, Hering was able to knead the heart, as it were, {mcdaxer le cceur,) without occasion- ing any apparent uneasiness to the animal,^ In some experiments by Sir B, Brodie,* the heart was emptied of its blood, and still contracted and relaxed alternately. Similar experi- ments were instituted by Mr. Mayo,^and with like results, — from which he concludes, that the alternations of contraction and relaxation of the heart depend upon something in its structure. The conclusion seems, indeed, irrefutable, if we add to these evidences the results of certain experiments of Dr. J. AViltbank,^ and of Dr. J, K, Mitchell, After the brain and medulla spinalis of the Testudo serpentana, snaj^ping -turtle or snapp)er had been destroyed, the heart continued to beat for thirty-two hours and upwards. In 1823, Dr, Mitchell,^ being engaged in dissect- ing a sturgeon — Aapenser hrevirostrum ? — took out its heart and laid it on the ground. After a time, it ceased to beat and was inflated with the breath, for the purpose of being dried. Hung up in this state, it began again to move, and continued for ten hours to pulsate regularly, though more and more slowly; and when last observed in motion, the auricles had become so dry as to rustle when they contracted and dilated. He subsequently repeated the experiment with the heart of a Testudo serpentaria, and found it to beat well under the influence of oxygen, hydrogen, carbonic acid, and nitrogen, throAvn into it in suc- cession. Water also stimulated it, — perhaps more strongly, — but made its sabstance look pale and hydropic, and, in one minvte, destroyed ac- tion beyond recovery. A few years ago, (1845,) Dr. ]\Iitchell repeated ' Amer. Journ. of the Med. Sciences, No. xxii., Feb., 1833. * The Works of William Harvey, M. D., Sydenham Society's edit., p. 384. ' Berard, Cours de Physiologie, iii. 652, Paris, 1851. * Cooke's Treatise on Nervous Diseases, lutrod., p. 61, Lond., 1820-23, Amer. edit., Boston, 1824. ^ Outlines of Human Physiology, 4th edit., p. 4G, Lond., 1837. * The Pliiladelphia Journal of tlie Medical and Physical Sciences, ix. 3G1 ; Philad., 1824. ' American Journal of the Medical Sciences, vii. 58, Philad., 1830. 408 CIRCULATION the experiment with the sturgeon, with the like results ; and soon after- wards, Dr. F. G. Smith, junior,' experimented on the hearts of the stur- geon, frog, and snapping-turtle. The heart of one sturgeon contracted for twenty-two hours after its removal from the body; of another twelve hours; of the frog thirteen hours; and of the snapping-turtle 25f hours. The contractions of the last were arrested by putting the organ in Avarra water with the hope of increasing them. The heart of a sturgeon inflated by Dr. Smith, and kindly sent by him to the author, hung up in his library and kept moist, contracted and dilated for up- wards of twenty hours. It has been supposed, that when the heart is empty of blood, the contact of air with its cavities is the stimulus by which its irritability is excited, but Dr. John Keid^ found — as Caldani, Wernlein and Ktirsch- ner had already done — when he placed a frog's heart in a state of activity under the receiver of an air-pump, that its action still continued after the receiver had been exhausted. Experiments, however, by F. Tiedemann^ do not accord, in their results, with those of Dr. Reid; but confirm those of Fontana. He placed the heart, immediately after it was removed from a living frog, under the receiver of an air-pump, from which he exhausted the air: the pulsations of the heart became weaker and slower, and in thirty seconds ceased. After five minutes, the air was readmitted, and the pulsations were resumed ; and this alter- nation was repeated several times; whilst another heart suspended in air continued in uninterrupted action for an hour. These experiments were repeated at the request of the author during the winter of 1849-50, by Drs. S. Weir Mitchell, and T. H. Bache, with analogous results. Whether these phenomena indicate that some change is produced phy- sically in the organ by the altered density of the air; or that the pre- sence of oxygen is necessary for its contraction may admit of a ques- tion. Dr. Brown -Sequard^ has suggested that the action of the heart may be owing to the presence of carbonic acid in the blood. He admits, however, that if a frog be put under a receiver containing oxy- gen at 40° or 50° Fahr., after its nervous centres have been destroyed, its heart will continue to beat for a long time; whilst if it be placed in carbonic acid at the same temperature, the heart will beat very quickly at first, but soon cease. CastelP found, from numerous observations on the duration of the heart's action in different gases, that when frogs were placed in carbonic acid it ceased speedily, or in about six minutes; whilst in moist air, it continued for three hours, and when the air was exhausted, the pulsations could not be distinguished after ten minutes. When the density of the air was augmented under the receiver, M. Tiedemann found, that the pulsations became quicker and stronger. The heart is the a:enerator of one of the forces that move the blood. This force has been the subject of much calculation, but the results have been so discordant as to throw discredit upon all mathematical 'Letter to the author, in Philadelphia Medical Examiner, for July, 1845, p. o93. * Cyclop, of Anat. and Physiol., ii. 611, Lond., 1839. ' Miiller's Ai-chiv. fiir Aniitomie. u. s. w., s. 490, Berlin, 1847. •* Experimental Researche:? applied to Physiology and Pathology, "^evr York, 1853. ^ Miiller's Archiv., 1854, s. 22'j ; and Canstatt's Jahresbericht, 1854, Iter Bd., s.151, Wiirzburg, 1855. IN THE HEART. 409 investigations on living organs; a circumstance, whicli renders it un- necessary to state the different plans that have been pursued in these estimations. Many of them are given in the elaborate work of Haller,' to which the reader, who may be desirous of examining them, is referred. Borelli^ conceived the force exerted by the left ventricle to be equiva- lent to 180,000 pounds ; Senac^ to 40 ; Hales^ to 51-5 pounds ; Jurin* to 15 pounds 4 ounces; whilst KeilP conceived it not to exceed from 5 to 8 ounces! The mode adopted by Hales has always been regarded the most satisfactory. By inserting a glass tube into the carotid of various animals, he noticed how high the blood rose in the tube. This he found to be, in the dog, 6 feet 8 inches ; in the ram, 6 feet 5| inches; in the horse, 9 feet 8 inches; and he estimated that in man it would rise as high as 7| feet. Now, a tube, whose area is one inch square and two feet long, holds nearly a pound of water. AVe may therefore reckon the weight, pressing on each square inch of the ventricle, on a rough estimate, at three pounds and three-quarters, or four pounds; and if we consider with Michelotti, the surface of the left ven- tricle to be fifteen square inches, it will exert a force, during its con- traction, capable of raising sixty pounds. Its extent is more frequently, however, estimated at 10 square inches, and the force developed would therefore, be forty pounds;^ but this is, of course, a rude approxima- tion. In such a deranging experiment, the force of the heart cannot fail to be modified ; and it is so much affected by age, sex, tempera- ment, idiosyncrasy, &c., that the attainment of accurate knowledge on the subject is impracticable. The indefinite character of our informa- tion on this matter is indeed sufficiently shown by the investigations of M. Poiseuille,^ which led him to suppose, that the force with which the organ propels the blood into the human aorta is about 4 pounds, 3 ounces, and 43 grains; and if Valentin's estimate of the muscular force of the right ventricle being one-half that of the left be taken, it must propel the blood into the lungs with a force only equal to about two pounds, two ounces. By means of an instrument, which, from its use, he terms lice.raa- dyncmiomeier^ M. Poiseuille has endeavoured to show, that the blood is urged forward with as great a momentum in a small artery, far from the heart, as in any important branch near it. In other words, that there is a uniform amount of pressure exerted by the blood upon the coats of the arteries in every part of the body; — those in the im- mediate vicinity of the heart being distended by an equal force with those most remote from it. M. Poiseuille^ n)ade the experiment on the carotid, and muscular branch of the thigh of the horse, and notwith- standing the very great dissimilarity in the diameter of the two tubes, and in their distance from the heart, the displacement of the mercury ' Elementa Physiologic, lib. i. sect. iv. § 42, Latisann., 1757. 2 De Motii Aniuialium, jjars ii., Lugd. Bat., 1710. * Traite de la Structure du Coeur, Paris, 1749. ■» Statical Essays, &c., ii. 40, Lond., 1733. * Philosophical Transactions for 1718 and 1719. ^ Tentamina Medico-Ph,ysica, &o., Lond., 1718. 7 Arnott's Elements of Physics, Amer. edit., pp. 447 and 461, Philad., 1841. 8 Magendie's Journal de Physiologie, x. 241. 8 Ibid., ix. 46. 410 CIRCULATION Fig. 120. was exactly the same in both. This inference, if correct, — and the experiments have been repeated by M. Magendie' and others with cor- responding resnlts, — is important in a thera- peutical point of view, as it leads to the be- lief, that if it be desirable to lessen the quan- tity of the circulating fluid, it is of little consequence what vessel is opened. The experiments of Poiseuille and Magendie have not, however, been canfirmed by Volk- mann, and they do not appear to be in ac- cordance with obvious hydrodynamic facts.^ The haemadynamometer employed by M. Poiseuille, consists of a bent glass tube, of the form represented in the marginal figure, filled with mercury in the lower bent part, a, (/, e. The horizontal part b, provided with a brass head, is fitted into the artery, and a small quantity of a solution of carbonate of soda is interposed between the mercury and the blood, which is allowed to enter the tube with the view of preventing coagidation. "When the blood is permitted to press upon the fluid in the horizontal limb, the rise of the mercury towards e, measured from the level to which it has fallen towards d, gives the pressure under which the blood moves. Estimates by Valentin^ as to the force of the heart make it even less than those of M. Poiseuille. He states, that in man and thehio;her mammalia, the abso- lute force exerted by the left ventricle is equal to g'oth of the weight of the body; and that by the right ventricle equal to j^^th of the same. During the diastole of the ventricles, the pressure, as indicated by the instrument, is somewhat diminished. It was observed by Hales,** that the column of blood in a tube inserted into an artery fell after each pulsation. The pressure must obviously be augmented or dimin- ished by anything that adds to or detracts from the heart's action; and it will be seen afterwards, that it is materially modified by the respira- tory movements.* b. Circulation in the Arteries. The blood, propelled from the heart by the series of actions we have described, enters the two great bloodvessels; — the pulmonary artery from the right ventricle, and the aorta from the left ; the former of which sends it to the lungs, the latter to every part of the system ; and, ' Legons sur le Sang, &c., or translation in Lond. Lancet, Sept., 1638 to March, 1839 ; and in Bell's Select Medical Library, p. 57, Philad., 1839. 2 Todd and Bowman, Tlie Physiological Anatomy and Physiology of Man, Pt. iv. p. 361, Lond., 1852, or Amer. edit., Phifad., 1853. 3 Lehrbuch der Physiologie des Menschen, i. 415, Braunsch\yeig, 1844. •• Op. cit., ii. 2. * Ludwig, in Miiller's Archiy. fiir Anatomie, u. s. \y., Heft iy. s. 242, Berlin, 1847. Haemadynamometer. IN THE AKTERIES. 411 in both vessels, it is prevented from returning into the corresponding ventricles by the depression of the semilunar valves. We have now to inquire into the circumstances, that act upon it in the arteries, and whether it be the contraction of the ventricle, which is alone concerned in its progression. Harvey' and all the mechanical physiologists regarded the arteries as entirely passive in the circulation, and as acting like so many lifeless tubes; the heart being, in their view, the sole agent. We have, how- ever, numerous reasons for believing that the arteries are concerned to a certain degree in the progression of the blood. If we open a large artery in a living animal, the blood flows in distinct pulses; but this effect gi'adually diminishes as the artery recedes from the heart, and ultimately ceases in the smallest ramifications ; — seeming to show, that the force, exerted by the heart, is not the only one concerned. It is manifest, too, that if such was the case, the blood ought to flow out of the aperture, when the artery is opened, at intervals coinciding with the contractions of the organ; and that during the diastole of the artery no blood ought to issue.. This, however, is not the case, not- withstanding the authority of Bichat and some others is in its favour. The flow is uninterrupted ; but in jets or pulses, coinciding with the contractions of the ventricles. Again, if two ligatures be put round an arterial trunk, at some distance from each other, and a puncture be made between the ligatures, the blood flows with a jet, — indicating that compression is exerted upon it ; and if the diameter of the artery be measured with a pair of compasses, before and after puncturing the vessel, it will be found manifestly smaller in the latter case ; — an ex- periment which shows the fallacy of a remark of Bichat, — that the force with which the arteries return upon themselves is insufficient to expel the blood they contain. An experiment of M. Magendie^ exhibits this more clearly. He exposed the crural artery and vein in a dog, and passed a ligature behind the vessels, tying it strongly at the posterior part of the thigh, so that the blood could only pass to the limb by the artery, and return by the vein. He then measured, with a pair of compasses, the diameter of the artery ; and on pressing the vessel be- tween his fingers, to intercept the course of blood, it was observed to diminish perceptibly in size below the part compressed, and to empty itself of its blood. On readmitting the blood, by removing the fingers, the artery became gradually distended at each contraction of the heart, and resumed its previous dimensions. These facts prove, that the arteries contract ; but the kind of con- traction has given occasion to discussion. Under the idea that their middle coat is muscular, it was conceived formerly, that they exert a similar action on the blood to that of the heart ; dilating to receive it from that organ, and contracting to propel it forwards ; — their systole being synchronous with that of the auricles and the diastole of the ventricles, and their diastole with that of the auricles and the systole of the ventricles. The principal reasons urged in favour of this view are ; — the fact of the circulation being effected solely by the arteries in ' Exercitatio Anat. De Motu Cordis et Sanguinis, &c., Rotterd., 1G48. ^ Journal de Physiologie, i. Ill ; and Precis, &c., ii. 386. 412 CIRCULATION acardiac foetuses, and iu animals that have no heart; — the assertion of MM. Lainure and Lafosse, that they noticed, in an experiment on the carotid arterj'', similar to that described above, that the vessel continued to beat between the ligatures; — the affirmations of Verschuir,^ Bikker, Giulio, and Rossi,^ Thomson,^ Parry,'' Hastings,* Wedemeyer, and nu- merous others, that when they irritated arteries with the point of a scalpel, or subjected them to the electrical and galvanic influences, they exhibited manifest contractility ; and lastly, the fact, that the pulse is not perfectly synchronous in different parts of the body, which ought to be the case, were the arteries not possessed of distinct action. The chief objection to the views founded on the muscularity of the middle coat was the want of evidence of the fact. In the anatomical proem to the function of the circulation it was stated, that this coat had not seemed to anatomists to consist of fibrous or muscular tissue ; and that the experiments of MM. Magendie, Nysten, and others, had not been able to exhibit any contraction, on the application to it of the ordinary excitants of muscular irritability. The chemical analyses of Berzelius^ and Young^ also appeared to show, that the transverse fibres differ essentially from those of proper muscles. It has been suggested, however, that the older analyses may have been made on the largest arteries in which muscular fibres scarcely exist f for histologists — as elsewhere shown — are now agreed, that, in the smaller arteries, more especially, the middle coat is partly composed of nonstriated or un- striped muscular tissue. Moreover, if any doubt existed in regard to the contractile action of the smaller arteries, it ought to be removed by the experiments of MM. E. and E. H. Weber,^ accurate observers, which were made with the rotating magneto-electric apparatus upon the arteries of the mesentery of frogs between 4th and y'^yth of a Fans line in diameter. When vessels between these dimensions were ex- posed to the electric stream, they did not immediately respond to the irritation ; but in a few seconds they began to contract, so that in from five to ten seconds their diameter was diminished one-third. If the stimulus was continued, the diminution of size went on until the dia- meter was reduced to one-third or even one-sixth of what it was ori- ginally, so that only a single row of blood-corpuscles could pass along the vessel, and at last became completely closed unless the stimulus was removed. They found, however, no change produced in tha capillaries when the magneto-electric current was applied to them; but it appeared to cause an unusual adhesion of the corpuscles to each other, and to tlie parietes of the vessels, and a consequent stagnation of the circulating fluid in them. Nor did the larger arteries exhibit ' De Arteriar. et Venar. Vi Irritabili, &c., Gri3ning., 1766. 2 Elemens de Medec. Operat., Turin, 1806. 3 Lectures on Inflammation, p. 83, Edinb., 1813 ; also, 2d Amer. edit., PliiLad., 1831. * On tlie Arterial Pulse, p. 52, Bath, 1816. 5 On Inflammation of the Mucous Membrane of the Lungs, p. 20, Lond., 1820. s View of the Progress of Animal Chemistry, p. 25, Loud., 1813. "^ An Introduction to Medical Literature, p. 501, Lond., 1813. 8 Kirkes and Paget, Manual of Physiology, p. 91, 2d Amer. edit., Philad., 1853. 9 Miiller's Archiv. fiir Anatomie, u. s. w., H. ii. s. 232, Jahrgang, 1847. IN THE AKTERIES. 413 any signs of contraction when the stream was directed to them. Similar results were obtained in analogous experiments by Kcilliker.^ If an artery be exposed in a living animal, we observe none of that contraction and dihitation which is perceptible in the heart; although a manifest pulsation is communicated to the tinger placed over it. The phenomena of the pulse will engage attention speedily. We may merely remark, at present, that the pulsations are manifestly more dependent upon the action of the heart than upon that of the arteries. In syncope, they entirely cease ; and whilst they continue beneath an aneurismal tumour, because the continuity of the vessel is not destroyed, they completely cease beneath a ligature so applied around an artery as to cut off' the flow of blood. Bichat attached an inert tube to the carotid artery of a living animal, so that the blood could flow through it: the same kind of pulsation was observed in it as in the artery. To this he adapted a bag of gummed taffeta, so as to simulate an aneurismal tumour : the pulsations were evidenced in the bag. If, again, arterial blood be passed into a vein, the latter vessel, which has ordinarily no pulsation, begins to beat; whilst, if blood from a vein be directed into an artery, the latter ceases to beat.^ Another class of physiologists have reduced the whole of the arte- rial action to simple elasticity; a property, which the yellow tissue that composes the proper membrane of the artery seems to possess in an unusual degree. Such is the opinion of M. Magendie.' " Admit- ting it to be certain," he remarks, " that contraction and dilatation occur in arteries, I am far from thinking, with some authors of the last century, that they dilate of themselves, and contract in the manner of muscular fibres. On the contrary, I am certain, that they are passive in both cases, — that is, that their dilata- tion and contraction are the simple effect of the elasticity of their parietes, put in action by the blood, which the heart sends incessantly into their ca- vity," — and he farther remarks, that there is no difference, in this respect, between the large and small arteries. As regards the larger arteries, it is pro- bable that this elasticity is the prin- cipal but not the only action exerted ; and that it is the cause why the blood flows in a continuous, though pulsa- tory, stream, when an opening is made into them ; thus acting like the reser- voir of air in certain pumps. In the pump A B, represented in the margi- nal figure, were there no air-vessel C, section of a Forcing Pump. ' Killliker and Siebold's Zeitschrift, 1849 ; and Brit, and For. Med.-Cliir. Rev July 1850, p. 241. ' ^' ^ Adelon, art. Circulation, in Diet, de M decine, lere edit., v. 321, Paris, 1822, and Physiol, de I'Homme, edit, cit., iii. 380. ^ Precis, &c., edit, cit., ii. 387 Fig. 121. 414 CIRCULATION tlie water would flow tlirougli the pipe E at each stroke of the piston, but the stream would be interrupted. By means of the air-vessel this is remedied. The water, at each stroke, is sent into the vessel ; the air contained in the air-vessel is thus compressed, and its elasticity thereby augmented ; so that it keeps up a constant pressure on the surface of the water, and forces it out of the vessel through the pipe D in a nearly uniform stream. — Now, ia the heart, tlie contraction of the ventricle acts like the depression of the piston ; the blood is pro- pelled into the artery in an interrupted manner, but the elasticity of the bloodvessel presses upon the blood, in the same manner as the air in the air-vessel presses upon the water within it; and the blood flows along the vessel in an uninterrupted, although pulsatorj^, stream.^ There are many difficulties, however, in the way of admitting the whole of the action of the arteries in the circulation to be dependent upon simple elasticity. The heart of a salamander was opened by Spallanzani f the blood continued to flow through the vessels for twelve minutes after the operation. The heart of a tadpole was cut out ; the circulation was maintained for some time in several of the vascular ramifications of the tail. The heart of the chick in ovo was destroyed immediately after contraction; the arterial blood took a retrograde direction, and the momentum of the venous blood was re- doubled. The circulation continued in this manner for eighteen minutes. Dr. Wilson Philip^ states, that he distinctly saw the circu- lation in the smaller vessels, for some time after the heart had been removed from the body, and a similar observation was made by Dr. Hastings." The last gentleman aflirms, that in the large arterial trunks, and even in the veins, he has noticed, in the clearest manner, their contraction on the application of various stimulants, both che- mical and mechanical. It is, moreover, well known, that if a small living artery be cut across, it soon contracts so as to arrest the hemor- rhage ; — that whilst an animal is bleeding to death the arteries will accommodate themselves to the decreasing quantity of blood in the vessels, and contract beyond the degree to which their elasticity could be presumed to carry them ; and that after death they will again relax. Dr. Parry found, that an artery of a living animal, if exposed to the air, sometimes contracts in a few minutes to a great extent ; in such case, only a single fibre of the artery may be aft'ected, narrowing the channel in the same way as if a thread were tied round it. The experiments that have been instituted for the purpose of disco- vering the dependence of the arterial action on the nervous system have likewise afforded evidences of their capability of assuming a con- tractile action, and have led to a better comprehension of cases of what have been called local detcrviinations of blood. Dr. Philip found, that the motion of the blood in the capillaries is influenced by stimulants ' Haller, Elmnenta Physiologise, ii. 212, Lavisan., 1760; Hales. Htemastatics, p. 22, § 26, Lond., 1733 ; Hunter on the Blood, by J. F. Palmer, Amer. edit., p. 162, Pliilad., 1840 ; Sir C. Bell, Animal Mechanics, Library of Useful Knowledge, p. 44 ; and Todd and Bowman, The Physiological Anatomy and Physiology of Man, Pt. iv. p. 352, Loud., 1852; or Amer. edit.,'Philad., 1853. '^ Experiments on the Circulation, &c., translated by R. Hall, Lond., 1801. ^ An Experimental hKiuiry into the Laws of the Vital Functions, Lond., 1817 ; and Lond. Med. Gazette, for March 25th, 1837, p. 952. « Op. citat., p. 51. IN THE ARTERIES. 415 applied to the central parts of tte nervous system, wliicli must be owing to these vessels, possessing a power of contractility, capable of being aroused to action by the nervous influence. The experiments of Sir Everard Home^ are, however, more applicable, as they were directed to the larger arteries, respecting which the greatest doubts have been entertained. The carotid artery of a dog was laid bare ; the par vagum and great sympathetic, which, in that animal, form one bundle, were separated from it by a flattened probe for one-tenth of an inch in length ; the head and neck of the dog were then placed in an easy position, and the pulsations of the carotid artery were attended to by all present for two minutes, in order that the eye might be accustomed to their force in a natural state. The nerve passing over the probe was then slightly touched with caustic potassa. In a minute and a half, the pulsations of the exposed artery became more distinct. In two minutes, the beats were stronger; in four minutes, their vio- lence was lessened; and in five minutes the action was restored to its natural state. The experiment was repeated with analogous results upon a rabbit. The par vagum was separated from the intercostal nerve; and when the former nerve alone was irritated no increase took place in the force of the action of the artery. " The carotid artery," says Sir Everard, "was chosen as the only artery in the body of suf- ficient size, that can be readily exposed, to which the nervous branches, supplying it, can be traced from their trunk. This experiment was repeated three different times, so as to leave no doubts respecting the result." These experiments demonstrate, that, under the nervous influence, an increase or a diminution may take place in the contraction of an artery ; and they aid us in the explanation of cases, in which the circulation has been accomplished where the heart has been altogether wanting or com- pletely defective in structure. Sir Everard instituted farther experi- ments, with the view of determining whether heat or cold has the greater agency in stimulating the nerves to produce this efiect upon the artery. The wrist of one arm was surrounded by bladders filled with ice ; and after it had remained in that state for five minutes, the pulse of the two wrists was felt at the same time. The beats in that which had been cooled were found to be manifestly stronger. A similar experiment was now made with water, heated to from 120° to 130° of Fahrenheit. The pulse was found to be softer and feebler in the heated arm. When one wrist was cooled and the other heated, the stroke of the pulse of the cooled arm had much greater force than that of the heated one. These experiments were re])eated upon the wrists of several young men and young women of different ages, with uniform results. Lastly, we have remarked, and shall have occasion to refer to the matter again, that certain animals, that have no heart, have circulating vessels in which contraction and dilatation arc perceptible. This is the case with the class vermes of Cuvier, and distinctly so in the lum- hricus marmus or lug^ the leech^ &c. The fact has been invoked both by the believers in the muscular contractility of arteries, and by those who conceive the contractility to be peculiar; but our acquaintance ' Lectures on Comparative Anatomy, iii. 57, Lond., 1823. 416 CIRCULATIOIT wifh. the intimate structure of tlie coats of the vessels in those animals is too imperfect for us to assert more than that they are manifestly contractile. In an interesting case of acardiac fcetus examined by Br. Houston, of Dublin, it seemed impossible that the heart of a twin foetus could have occasioned the movement of blood in the acardiac one; and hence that there must have been some power in the vessels of the lat- ter — general, or capillary, or both — to effect the circulation through it. In most or all of these cases, however, a perfect twin foetus exists, whoso placenta is in some degree united with that of the imperfect one; and the circulation in the latter has usually been attributed to the influence of the heart of the former propagated through the pla- cental vessels. From these and other considerations, the majority of phj^siologists have admitted a contractile action, in perhaps all except the larger arterial trunks ; and, at the present day, the most general and satis- factory opinion appears to be, that, in addition to the highly elastic property possessed by the middle coat, it is capable of being thrown into contraction through the organic muscular fibres, which exist in greater quantity in the small arteries than in the large; that, consequently in the larger vessels this contraction-* is little evidenced, the action of the artery being mainly produced by its elasticity; but that, in the smaller arterial ramifications, the contractility is more manifest; its great object being to regulate the quantity of blood to be distributed to a part; or to adjust the vessel to the amount of fluid circulating in it. To this contractility, necessarily connected with the life of the vessel, and which he considered to differ from both muscular contrac- tility and simple elasticity, Dr. Parry^ gave the name tonicity. c. Ci)xuIatio)i through the Capillaries. The agency of the capillary vessels in the circulation has been a subject of contention. The opinion of Harvey, embraced by J. Miil- ler,^ was, that the action of the heart alone is sufficient to send the blood through the whole circuit ; but we have seen, that, even when aided by the elasticity and contractility of the arterial trunks, the pul- sations of that organ become imperceptible in the smaller arteries ; and, hence, there is some show of reason for the belief, that in the capillary vessels the force may be entirely spent. Were we, indeed, to admit that the force of the heart is sufficient to send the blood through a single capillary circulation, it would be difficult to admit that it could send it through two — as in the portal circulation. Still, we can by no means accord with Professor Draper,^ of New York, that " it is now on all hands conceded," that this powerful muscular organ — the heart — discharges " a very subsidiary duty." Bichat regarded the capillaries as organs of propulsion, and alone concerned in returning the blood to the heart through the veins. Dr. Marshall Hall,'* on the other hand, denies, that we have any proof of ' On the Arterial Pulse, p. 52, Bath, 1816. 2 Handbuch, u. s. w., Baly's translation, p. 220, Lond., 1838. 3 A Text-Book on Chemistry, p. 392, New York, 184(J. * A Critical and Experimental Essay on the Circulation, &c., p. 78, Lond., 1831, reprinted in this country, Philad., 1835. IN THE CAPILLARIES. 417 irritability in the true capillaries ; and Magendie^ conceives the con- traction of the heart to be the principal cause of the passage of the blood through those vessels. In support of this view he adduces the following experiment. Having passed a ligature round the thigh of a dog, so as not to compress the crural artery or vein, he tied the latter near the groin, and made a small opening into the vessel. The blood immediately issued with a considerable jet. He then pressed the artery between the fingers, so as to prevent the arterial blood from passing to the limb. The jet of venous blood did not, however, stop. It continued for some moments, but went on diminishing, and the flow was arrested, although the vein was filled through its whole extent. When the artery was examined during these occurrences, it was ob- served to contract gradually, and at length became completely empty when the course of the blood in the vein ceased. At this stage of the experiment, the compression was removed from the artery; the blood immediately passed into the vessel, and, as soon as it had reached the final divisions, began to flow again through the opening in the vein, and the jet was gradually restored. On compressing the artery again until it was emptied, and afterwards allowing the arterial blood to pass slowly along the vessel, the discharge from the vein took place, but without any jet: the jet was resumed, however, as soon as the artery was entirely free. This experiment is not so convincing to us as it appears to have been to M. Magendie. The chief fact, which it exhibits, is the elastic, and probably contractile, power of the arteries. It might have been expected, a priori., under any hypothesis, that the quantity of blood discharged from the vein would hold a i^atio to that sent by the artery; and, consequently, the experiment appears to us to bear but little on the question regarding the separate contractile action of the capillaries. It is difficult, indeed, to believe that such an action does not exist. In addition to the circumstance, already mentioned, of the absence of pul- sation in the smaller arteries, almost every writer on the theory of in- flammation has considered the fact of a distinct action of the capillaries established, and leaves to the physiologist the by no means easy task of proving it. Dr. Wilson Philip^ placed the web of a frog's foot under the microscope, and distinctly saw the capillaries contract on the application of those stimulants that produce contraction of the mus- cular fibre. The results of Dr. Thomson's^ experiments in investi- gating inflammation, as well as those of Dr. Hastings,^ were the same. The facts, already referred to, regarding the continuance of the circu- lation in the minute vessels after the heart had been removed, as well as the observation of Dr. Philip, that the blood in the capillaries is influenced by stimulants applied to the central parts of the nervous system, are confirmator}^ of the same point. The experiments of Drs. Thomson, Philip, and Hastings, were repeated by Wedemeyer,* with ' Precis, &c., ii. 390. ^ A Treatise on Febrile Diseases, 3d edit.,ii. 17, London, 1813; and Medico-Cliirurg. Transact., vol. xii. p. 401. * Lectures on Intiammation, p. 83, Edinb., 1813. '' Op. citat. ^ Untersuch. tiber die Kreislauf, u. s. w., Hannover, 1828 ; cited in Edinb. Med. and Surg. Journ., vol. xxxii. VOL. I.— 27 418 CIRCULATION great care. The circulation in the mesentery of the frog, and in the web of its foot, being observed through the microscope, it was evident, that no change occurred in the diameter of the small arteries, or in that of the capillaries, so long as the circulation was allowed to go on in its natural state ; but as soon as excitants were applied to them, an alteration of their calibre was perceptible. Alcohol arrested the flow of blood without inducing much apparent contraction of the vessels. Chloride of sodium, in the course of three or four minutes, caused them to contract one-fifth of their calibre, which was followed by their dila- tation, and a gradual retardation and stoppage of the blood. In a space of time varying from ten to thirty seconds, and sometimes im- mediately after the application of the galvanic circle, they contracted, some one-fourth, others one-half, and others three-fourths of their calibre. The contraction at times continued for a considerable period, occasionally for several hours; in other instances it ceased in ten minutes, and the vessels resumed their natural diameter. A second application of galvanism to the same capillaries seldom caused any material contraction. Schwann' likewise found, that when cold water was poured on the vessels of a frog, which had been previously in a warm atmosphere, the capillaries immediately contracted, but after a time regained their diameter. Farther, Mr. Hunter^ found, on ex- posing arteries to the air, that they contracted so much as to occasion obliteration of their cavities; and it is well known, that when arteries — ■ as the temporal — are divided, the hemorrhage is arrested by the spon- taneous contraction of the divided vessel, — a contraction, which, as remarked by Dr. Carpenter, is much greater than could be accounted for by simple elasticity of tissue, and is more marked in small than in large vessels.^ All these facts prove the existence of a vital power in the capillaries, capable of modifying, to a considerable extent, the flow of blood through them. Again : — the phenomena of local inflammation have been considered to favour this view of an independent action of the capillaries, in which there may be increased flow or retardation of the blood in a part, without the general circulation exhibiting augmented action or excite- ment. In the natural state, the vessels of the tunica conjunctiva covering the white of the eye receive little blood ; but if any cause of irritation exists, as a grain of sand entering between the eyelids, blood is rapidly sent into them, giving the appearance that has been not inappropriately termed " blood-shot.""' In the experiments of Kalten- brunner,* which were fully confirmed on repetition, the blood in inflammation was at first observed streaming to the irritated part, in consequence of which the capillary vessels became distended ; after- wards ii'regularity of circulation occurred in the gorged capillary » Miillers Arcliiv., 1836, and Lond. Med. Gazette, May, 1837. * A Treatise on the Blood, luflammation, and Gunshot Wounds, Amer. edit., ii. 156, Philad., 1840. * Principles of Human Physiology, Amer. edit., p. 259, Philad.. 1855. * Thomson's Lectures on Inflammation, Edinb., 1813. * Experimenta circa Statum Sanguinis et Vasorum in Inflammatione, p. 23, Monach., 1826. IN THE CAPILLARIES. 419 system ; and subsequently complete arrest of the flow, and disorgani- zation. These phenomena are of themselves sufficient to prove the existence of a separate action of the capillaries, and, taken in con- junction with other facts, are overwhelming. The blush of modesty, and the paleness of guilt, the hectic glow, and the translucency of congelation are circumstances that go to establish the same point. The contractile power of the capillaries is doubtless modified by the condition of the nerves distributed to them, which, as we have seen, are observed to increase as the size of the vessels and the thickness of their coats diminish. Their influence is strikingly evinced in actions, that are altogether ne?vous, as in the flushed countenance occasioned by sudden mental emotion. By some, however, the whole capillary circulation has been ascribed to a motive faculty inherent in the cor- puscles of the blood; whilst others, again, have asserted, that the "electro-galvanic power," — or in other words — the nervous power, generated in the nervous system, and acting on the blood corpuscles through the parietes of the capillaries, is the immediate agent that directs the circulation in the capillaries. All this, however, enters into the inscrutable question, — what is the cause of life in the tissues. — a question to be agitated, but not solved, in a subsequent part of this volume. But, not only has a vital power of contraction been conceded to the capillaries; it has been imagined, that they possess what the Germans call a Lehenstnr go r {turgor vilalis) or \itixl property of expansi- bility or turgescence. Such is the opinion of Hebenstreit' and of Prus f and it has been embraced, in this country, by Professor Smith of Yale College; by his son. Professor N. K. Smith of Baltimore, in his excellent work on the " Arteries,"^ and by Professor Hodge," of Philadelphia. The idea has been esteemed to be confirmed by the fact of excitants having been seen under the microscope, by Hastings, Wede- meyer, and others, to occasion not only contraction but dilatation of the capillaries. The phenomena observed in the erectile tissues have likewise been considered to favour the hypothesis ; but in answer to these arguments it may be replied, that the irregular excitation, pro- duced in the parts by the application of powerful stimulants, might readily give occasion to an appearance of expansibility under the mi- croscope, without our being justified in inferring, that these vessels pos- sess an innate vital property of expansibility; and, in many of the cases, in which ammonia and galvanism were applied by Thomson, Hastings, Wedemeyer, and others, the action of contraction ought rather to be esteemed physical or chemical than vital. The results of the applica- tion of such excitants, as diluted alcohol, dilute solutions of ammonia and chloride of sodium, can alone be adduced as evidences of such vital action on the part of those vessels. The dilatation of the capillary system and of the smaller arteries, which has been remarked on the ' Dissert, de Turgore Vitali, Lips., 1795 ; Hildebrandt's Pliysiologie, Auflag. 5, § 84; and Tiedemann's Physiologie, trad, par Jourdan, p. 625, Paris, 1831. * De rirritation, &c., Paris, 1825. ' Surgical Anatomy of the Arteries, 2d edit., Baltimore, 1835. * North Amer. Med. and Surg. Journal, June, 1828. 420 CIRCULATION" contact of those agents, is not, as Oesterreicber^ has remarked, the primary effect : it is the consequence of the afllux of blood to the irri- tated part, as was demonstrated, also, in the experiments of Kalten- brunner on inflammation, to which allusion has been made. Lastly, attentive observation of the phenomena presented by the erectile tissues must lead to the conclusion, that turgescence of vessels is not the first link in the chain of phenomena; excitation is first induced in the nerves of the part, — generally through the influence of the brain, and thence, perhaps, through the sympathetic nerve, — and the afflux of fluid supervenes on this. The vital expansibility of the capillaries cannot, we think, be regarded as proved, or proSable. Professor Draper, of New York, maintains, that the great agency in the circulation of the blood is of a physical character; and is dependent upon the chemical relations of that fluid to the tissues with which it is brought in contact. On the principles of capillary attraction — he says — a liquid will readily flow through a porous body for which it has a chemical affinity ; but it will refuse to flow through it, if it has no affinity for it. On this principle he explains why the arterial blood presses the venous before it in the systemic circulation, and why the reverse takes place in the pulmonic. "The systemic circulation takes place because arterial blood lias a high affinity for the tissues, and venous blood little or none. The pulmonary circulation takes place because venous blood has a high affinity for atmospheric oxygen, which it finds in the air cells of the lungs ; and arterial blood little or none. On the same principle we may explain the rise of sap in trees, the cir- culatory movements in the different animal tribes, and the minor circulations of the human system."^ Dr. Dowler,^ of New Orleans, whilst he earnestly combats the views of Professor Draper, is a strong advocate for the distinct action of the capillary vessels, and he adduces a number of striking experiments to establish his position. In perhaps' one-fourth of the dissections which he records, the bodies were carried to the dissecting-room a few minutes after death. The external veins, chiefly those of the arms and neck, sometimes became distended ; and when they were opened, the blood often flowed in a good stream, and was, at times, projected to the distance of a foot or more. In some cases, by putting a ligature around the arm, or by grasping it above the elbow, the blood was made to flow more freely, and by moving the muscles, as is done in ordinary bloodletting, the blood shot forth for some distance. Punctures in the middle of the subclavian discharged blood, which arose in a full stream, against gravity, two or three inches; sometimes forming an arch as it fell. The coronary veins discharged blood rapidly and " with surprising force." These dissections are con- sidered by Dr. Dowler to show conclusively the independent action of the capillaries ; "which in yellow fever, and other acute fevers, probably survives respiration and the heart's action ; and when it ceases cada- veric hyperaemia takes place." Such is doubtless the fact ; but it ' Versuch einer Darstellmig der Lelire vom Kreislaiif des Blutes, Niirnberg, 1826. 2 A Text-Book of Chemistiy, p. 392, New York, lS4(i; and On the Forces which Pro- duce the Organization of Plants, chap. iii. 3 Researches, Critical and Experimental, on the Capillary Circulation. (Reprinted from the New Orleans Medical and Surgical Journal.) January, 1849. IN THE CAPILLAEIES. 421 Fig. 122. may still be questioned, whether anything more than the physical capillarity invoked by Professor Draper is concerned in the pheno- menon. In a case observed by the author, and referred to elsewhere, blood flowed freely from the vessels of the brain, and coagulated fifteen hours after the cessation of respiration and circulation ; and many similar cases are on record. The circulation through the capillaries has long been an interesting topic of microscopic research. According to Wagner,^ a magnifying power of from two to three hundred diameters is required to make out the particular details. The blood in mass, or in the larger channels, he says, is seen to flow more rapidly than in the smaller. Here the blood corpuscles advance with great rapid- ity, especially in the arteries, and with a whirling motion, and form a closely crowded stream in the middle of the vessel, without ever touching its parietes. With a little attention, a narrower and clearer, but always very distinct space is seen to remain between the great middle current of blood corpuscles and the walls of the vessel, in which a few white corpus- cles, or what Wagner considers to be lymph corpuscles, are moved on- wards, but at a much slower rate. These white corpuscles swim in smaller numbers in the transparent liquor sanguinis, and glide slowly, and in general smoothly, though they sometimes advance by fits and starts more rapidly, but with intervening pauses ; and, as a general rule, at least ten or twelve times more slowly than the corpuscles of the central stream. The clear space, filled with liquor sanguinis and white corpuscles, is obvious in all the larger capillaries, whether arte- rial or venous, but ceases to be apparent in the smaller intermediate vessels which admit but one or two rows of blood corpuscles (Fig. 102). In these vessels, two sets of corpuscles proceed pari passu ; but, accord- ing to Wagner, it is easy to see, that the blood corpuscles glide more readily onwards, — the white corpuscles seeming often to be detained at the bendings of vessels, and at the angles, where anastomosing branches are given off; here they remain adherent for an instant, and then sud- denly proceed onwards. These phenomena are observed in every part of the peripheral systemic circulation; but an exception appears to exist in the pulmonic circulation ; the capillaries there being filled with both kinds of corpuscles to their very walls. It is in this — the intermediate — part of the sanguiferous system, that most important functions take place. In the smallest artery we find Small Venous Branch, from the Web of a Frog's Foot, magnified 350 diameters. 6, h. Cells of pavement epithelium, containing nuclei. In the space betwetm the current of oval blood corpuscles, and the walls of the vessel, the round transparent lymph globules (?) are seen. ' Elements of PLiysiology, translated by R. Willis, § 122, Lond., 1842. 422 CIRCULATION" Fig. 123. Large Vein of Frog's Foot, magnified 600 diameters. 6, c. Blood corpuscles, a, a. Lymph corpuscles (?) principally conspicuous in the clear space near the pa- rietes of the vessel. arterial blood ; and in the smallest vein communicating with it blood always possessing venous properties. Between those points, a change must have occurred, the reverse of that which happens in the lungs. It is here, too — in the tissues — that nutrition, secre- tion, and calorification are effected. In the explanation of these functions, we shall find it impossible not to sup- pose a distinct and elective agency in the tissues concern- ed; and as it is by such agency, that the varying activity of the different functions is regu- lated, we are constrained to believe, that the capillary ves- sels may be able to exert a controlling influence over the quantity and velocity of the blood circulating in them. In disease, the agency of this sys- tem of vessels is an object of attentive study with the patho- logist. To its influence in in- flammation we have already alluded ; but it is no less exemplified in the more general diseases of the frame, — as in the cold, hot, and sweating stages of an intermittent. Local, irregular capillary action is, indeed, one of the most common causes or effects of acute diseases, and this generally occurs in some organ at a distance from the seat of the deranging influence. It is a common and just observation, that getting the feet wet, and sitting in a draught of air, are more certain causes of catarrh than sudden atmo- spheric vicissitudes that apply to the whole body; and so extensive is the sympathy between the various portions of the system of nutrition, that the most diversified effects are produced in different individuals exposed to the same common cause ; one may have inflammatory sore throat; another, ordinary catarrh; another, inflammation of the bowels; according to the precise predisposition, existing in the individual at the time, to have one structure morbidly affected rather than another; — but these are interesting topics, which belong more strictly to the pathologist.' By the united action, then, of the heart, arteries, and capillary or intermediate system of vessels, the blood attains the veins. We have now to consider the circulation in these vessels. d. Circulation in the Veins. It has been already observed, that Harvey considered the force of the heart to be of itself sufficient to return the blood, sent from the left ' See, on the Capillary Circulation, William S. Savory, in Brit, and For. Med.-Chir, Rev., Jan., 1855, p. 390, and July, 1S55, p. 12. ^ IN THE VEINS. 423 ventricle, to the heart; whilst Bichat conceived the whole propulsorj effort to be lost in the capillaries, and the transmission of the blood along the veins to be entirely effected by the agency of the capillary system. It is singular, that an individual of such distinguished powers of discrimination should have been led into an error of this magaitude. It is a well-known principle in hydrostatics, that although water, when unconfined, can never rise above its level at any point, and can never move upwards ; yet, by being confined in pipes or close channels of any kind, it will rise to the height from which it came. Hence the blood in the right auricle would stand at the same height as that in the left ventricle, — were they inanimate tubes. We need be at no loss, therefore, in understanding how the blood might attain the right auri- cle, when the body is erect, by this hydrostatic principle alone ; but we have seen, that the force exerted by the heart, arteries, and capil- lary system is superadded to this, so that the blood would rise much higher than the right auricle, and consequently exert a manifest effort to enter it. It may be remarked, also, that the left ventricle is not the true height of the source, but the top of the arch of the aorta, which is more elevated by several inches than the right auricle. A similar view is embraced by Dr. Billing;^ but Dr. Carpenter^ — in commenting on the author's observations on this subject — suggests, that the influence of this hydrostatic force would scarcely be felt through the plexus of capillary vessels; "for the interposition of a system of tubes even of much larger calibre would be, by the friction created between the fluid and their walls, an effectual obstacle to the rapid ascent of a current, which had so slight an impetus as that derived from its previous ffill." The author did not mean, however, to say more than that the blood "might attain" the right auricle by the hydrostatic force alone; he did not wish to convey the idea, that the circulation could be carried on without the aid of an additional force ; but that a slight effort only on the part of the heart, arteries, and capillaries might be needed to enable the blood to perform its entire circuit. It is proper to add, that in the last editions of his valuable work, Dr. Carpenter has omitted those comments on the observations of the author. Are we then to regard the veins as simple elastic tubes ? This is the prevalent belief. Their elasticity is, however, much less than that of the arteries. Some physiologists have conceived them to possess contractile properties also. Such is the opinion of M. Broussais,^ who founds it, in part, upon certain experiments by M. Sarlandiere, already referred to, in which contraction and relaxation of the vence cavee of the frog were seen for many minutes after the heart was removed from the body. These pulsations of the vena3 cavas, and of the pul- monary veins in their natural state, have been seen by numerous observers — by Steno, Lower, Wepfer, Borrachius, Whytt, Haller, Lancisi, MUller, Marshall Hall, Flourens, J. J. Allison, and others.* ' First Principles of Medicine, Amer. edit., p. 36, Philad., 1842; 2d Amer. edit., Pliilad., 1851. ^ Human Physiology, § 516, Lond., 1842. 3 Traite de Physiol., &c., translat. by Drs. Bell and La Roche, p. 391, Philad., 1832. * See the experiments of the last named gentleman, proving the existence of a ve- nous pulse independent of the Heart and Nervous System, in Amer. Journal of the Medical Sciences, Feb., 1839, p. 306. 424: CIRCULATION. The experiments of Dr. Allison, in reference to tlie veuas cavas and pulmonary veins, appeared to him to prove ; — that they pulsate near the heart in the four classes of the vertebrata ; — that in dying animals they pulsate long after the auricle and ventricle have ceased ; — that they also beat even in quadrupeds for hours after they have been separated from the heart and from the body ; — and that they can be stimulated to contract, either in or out of the body, b}'' mechanical and galvanic agenc}^, especially by the latter, after all motion has ceased for some time. Tt has been deemed doubtful, however, whether the veins generally possess any contraction like that of the venai cava3 and the pulmonary veins near the heart, for although irritated by galvanic and mechanical stimuli by Haller, Nysten, Muller, J. J. Allison, and others, no motion whatever could be detected in them. It has been before shown, how- ever, that non-striated muscular fibres enter into their composition, and Gerber affirms, that the fibres of their middle coat bear a stronger resemblance to those of muscular tissue than do those of the corre- sponding coat of the arteries, which more resemble ordinary elastic fibres. In the veins of the bat's wing Mr. Wharton Jones' observed rhythmical contractions and dilatations, and that the}' were provided with valves, some of which completely, and others only partially, opposed the regurgitation of the blood. During the contraction the flow of blood in the vein was accelerated, and on the cessation of con- traction the flow was checked, and there was a tendency to regurgita- tion. The action of the heart appeared to maintain the onward flow of blood during the dilatation of the vein, whilst the contraction of the vein was added to the action of the heart, and occasioned the acceleration. In the experiments of Dr. Marshall HalP on the circulation in the web of the frog's foot, he was almost invariably able to detect, with a good microscope, a degree of pulsatory acceleration of the blood in the arteries at each contraction of the heart ; and he is disposed to con- clude, that the natural circulation is rapid, and entirely pulsatory in the minute arteries, and slow and equable in the capillary and venous systems. But whenever the circulation was in the slightest degree impeded, the pulsatory movement became very manifest at each sys- tole of the heart, and it was seen in all the three systems — arterial, capillary, and venous. He observed, that in the arteries there was generally an alternate, more or less rapid flow of the corpuscles at each systole and diastole of the ventricle ; and that in the capillaries and veins the blood was often completely arrested during the diastole, and again propelled by a pulsatory movement during the systole ; — all which he esteems conclusive proof, that the power and influence of the heart extend through the arteries to the capillaries, and through these to the veins, even in the extreme parts of the body. The ex- periments of Valentin^ would seem, however, to show, that but little of the force of the left ventricle remains to propel the blood in the veins. lie found, that the pressure of the blood in the jugular vein ' Philosophical Transactions, 1852, p. 158. 2 Essay on the Circulation, ch. i.. Lend., 1831, and Philad., 1835. ^ Lehrbuch der Physiologic des Menschen, i. 477, Braunschweig, 1844. FORCES THAT PROPEL THE BLOOD — SUCTION" POWER, 425 of a clog, as estimated by the h^emadynamometer of Poiseuille, was not more than y'j- th or ^'oth of that in the carotid artery. In the upper part of the vena cava inferior, he could scarcely detect any pressure ; almost the whole force of the heart having been apparently consumed during the passage of the blood through the capillaries :^ still — as Messrs. Kirkes and Paget^ suggest — slight as this remanent force might be, it would be enough to complete the circulation, inasmuch as although the spontaneous dilatation of the auricles and ventricles may not be forcible enough to assist the movement of blood in them, it is adapted to present no obstacle to the movement. That the veins are possessed of elasticity is proved by the operation of bloodletting, in which a part of the jet, on puncturing the vein, is owing to the over-distended vessel returning upon itself; but that this property exists to a trifling extern only is shown by the varicose state of the vessels, which is so frequently seen in the lower extremities. e. Forces that j^Topel the Blood. From the inquiry into the agency of the different circulatory organs in propelling the blood, it is manifest, that the action of the heart, the elasticity of the arteries, and a certain degree of contractile action in the smaller vessels more especially, a distinct action of the capillary vessels, and a slight elastic and perhaps contractile action on the part of the veins, may be esteemed the efficient motors. Of these, the action of the heart and capillaries, and the contraction of the arteries and veins, can alone be regarded as sources of motion, the elasticity of the vessels being simple directors, not generators of force. But there is another agency, which is probably more efficient than has been generally conceived. This is the suction power of the heart, or deriva- tion as it has been termed, to which attention has been chiefly directed by Haller,^ Wilson,^ Carson,* Zugenbiihler, Schubarth, Platner, Blu- menbach,^ and others ; but which is not assented to by Oesterreicher,' Mliller,^ and othei's.^ It is presumed, that the muscular fibres of the heart are mixed up with a large quantity of areolar tissue ; and that whilst the contraction of the cavities is effected by the action of the muscular fibres, dilatation is produced by the relaxation of the contracted fibres, and the elasticity of the areolar tissue ; so that when the heart has contracted, and sent its blood onwards, its elasticity instantly restores it to its dilated condition ; a vacuum is formed, and the blood rushes in to fill it. This action has been compared by Dr. Bostock,^" and by Dr. Southwood Smith," Prof. Turner,'^ and others, to ' Magendie, Lemons sur les Phenomenes Physiques de la Vie, iii. 152, Paris, 1837. 2 Manual of Physiology, 2d Amer. edit,, p. 112, Philad., 1853. ' Elem. Physiol., ii. lib. vi. * Enquiry into the Moving Powers employed in the Circulation of the Blood, Lond., 1784. ^ Inquiry into the Causes of the Motion of the Blood, 2d edit., Lend., 1833. * Institutiones Physiol ogicse, § 12G, Gotthig., 1798. ^ Lehre vom Kreislauf des Bhites, Nlirnberg, 1826. ® Handbuch, u. s. w., Baly's translation, p. 173. ^ Burdach, Physiologie als Erfahrungswissenschaft, iv. 270, Leipz., 1832. '" Physiology, 3d edit., p. 251, Lond. ^1830. " Animal Physiology, (Library of Useful Knowledge,) j). 83, Loud., 1829. '^ Edinb. Medico-Chirurg. Transact,, iii. 225. 426 CIRCULATION. that of an elastic gum bottle, wliich, when filled with water, and com- pressed by the hand, allows the fluid to be driven from its mouth with a velocity proportionate to the compressing force ; but the instant the pressure is removed elasticity begins to operate, and if the mouth of the bottle be now immersed in water, a considerable quantity of that fluid will be drawn up into the bottle, in consequence of the vacuum formed within it. This power of elasticity in the tissues composing the parietes of the heart is the only one whose existence has been ad- mitted as concerned in the phenomenon. Dr. Carpenter,' however — as before remarked — has suggested, whether there may not exist in muscle an active force of elongation, as well as an active force of con- traction — arising from the mutual repulsion of particles whose natural contraction is the occasion of the shortening. The suggestion — it need scarcely be said — is altogether hypothetical. The existence of this force is confirmed by Dollinger,^ — who, when examining the embryos of birds, saw the blood advance along the veins, and the venous trunks pour it into the auricles at the moment they dilated to receive it; as well as by Dr. T. Robinson,^ and M. Cruveil- hier," who were forcibly struck with the activity with which the diastole was effected, in the cases of monstrosity more than once referred to. Dr. Carpenter* thinks it very doubtful "how far the auricles have such a power of active dilatation as would be required for this purpose;" but the question need not regard the auricles. It is but necessary to suppose, that an action or power of dilatation exists in the ventricles; and this is now generally admitted. He farther remarks, that it has been shown experimentally by Dr. Arnott and others, that no suction power exerted at the farther end of a long tube, whose walls are as deficient in firmness as those of the veins are, can occasion any accele- ration in a current of fluid transmitted through it; for the effect of the suction is destroyed at no great distance from the point at which it is applied by the flapping together of the sides of the vessel ; but in answer to this it may be observed, that it remains to be shown, that such flapping of the sides would necessarily occur in the veins, which are living vessels, and constantly receiving blood from the capillaries under the action of vital forces. Another accessory force, that has been invoked, is the suction power of the chest or inspiration of venous blood, as it has been termed. This is conceived to be effected by the same mechanism as that which draws air into the chest. The chest is dilated during inspiration; an approach to a vacuum occurs in it; and the blood, as well as the air, is forcibly drawn towards that cavity. On the other hand, during ex- piration, all the thoracic viscera are compressed ; the venous blood is repelled from the chest, and the arterial blood reaches its destination with greater celerity, owing to the action of the expiratory muscles ' Principles of Human Physiology, Anier. edit., p. 249, (note), Philad., 1855. * Denkschriften der Kiinigl. Akademie der Wisseuschaft. zu Miinchen, vii. 217; and Burdacli, op. citat., p. 272. ^ American Journal of the Medical Sciences, No. xxii. * Gazette Medicale de Paris, 7 Aout, 1841, p. 535 ; cited in Brit, and Foreign Medical Review, Oct., 1841, p. 535. s Ibid., p. 270. FOKCES THAT PROPEL THE BLOOD — RESPIRATION. 427 being added to that of the left ventricle. Haller,^ Lamure,^ and Lorrj,* had observed, that the blood in the external jugular vein moves under manifestly different influences during inspiration and expiration. Gene- rally, when the chest is dilated in inspiration, the vein empties itself briskly ; becomes flat, and its sides are occasionally accurately applied against each other; — but during expiration it rises, and becomes filled with blood; — effects, which are more evident, when the respiratory movements are extensive. The explanation of this phenomenon by Haller and Lorry is the one given above. To discover whether the same thing happens to the venaB cav£e, M. Magendie introduced a gum elastic catheter into the jugular vein, so as to penetrate the vena cava and even the right auricle : — the blood was observed to flow from the extremity of the tube at the time of expira- tion only. During inspiration, air was rapidly drawn into the heart, giving rise to the symptoms, elsewhere mentioned, which attend the reception of air into that organ. Similar results were obtained, when the tube was introduced into the crural vein in the direction of the abdomen. So far as regards the larger venous trunks, therefore, the influence of respiration on the circulation is sufficiently evidenced.'' It can be easily shown, by opening an artery of the limbs, that expi- ration — especially forced expiration, and violent efforts — manifestly accelerate the motion of arterial blood. In animals subjected to expe- riment, it is impracticable to excite either the forced expiration or vio- lent effort at pleasure; but we can, as a substitute, compress the sides of the chest with the hands, according to the plan recommended by Lamure ; when the *blood will be found to flow more or less copiously in proportion to the pressure exerted. It occurred to M. Magendie, that this effect of respiration on the course of the blood in the arteries might influence the flow along the veins. To prove this, he passed a ligature around one of the jugular veins of a dog. The vessel emptied itself beneath the ligature, and became turgid above it. He then made a slight puncture with the lancet in the distended portion; and in this way obtained a jet of blood, which was not sensibly modified by the ordinary respiratory movements, but became of triple or quadruple the size, when the animal struggled. As it might be objected to this expe- riment, that the effect of respiration was not transmitted by the arteries to the open vein, but rather by the veins that had remained free, which might have conveyed the blood repelled from the vena cava towards the tied vein by means of anastomoses, the experiment was varied. The dog has not, like man, large internal jugular veins, which receive the blood from the interior of the head. The circulation from the head and neck is, in it, almost wholly confined to the external jugular veins, which are extremely large ; the internal jugulars being little more than vestiges. By tying both of these veins at once, M. Magendie made sure of obviating, in great part, the reflux in question ; but, in- stead of this double ligature diminishing the phenomenon under con- sideration, the jet became more closely connected with the respiratory ' Elementa Physiologife, torn. ii. lib. vi. sect. iv. § 8, Lausann., 1760. * Mem. de I'Acad. des Sciences, pour 1749. ^ Magendie, Precis, &c., ii. 416. * Poiseuille, in Magendie's Journal de Physiologie, viii, 272. 428 ' CIRCULATION. movement; for it was manifestly modified even by ordinary respira- tion, which was not the case when a single ligature was employed. From these and other experiments, he properly concluded that the tur- gescence of the veins must not be ascribed, with Haller, Lamure, and Lorry, simply to the reflux of the blood of the venae cavas into the branches opening directly or indirectly into them; but partly to the blood being sent in larger quantity into the veins from the arteries.* In the same manner are explained, — the rising and sinking of the brain, which, as will be observed in an after part of this volume, are synchronous with expiration and inspiration. During expira- tion, the thoracic and abdominal viscera are compressed- the blood is driven more into the branches of the ascending aorta, and is, at the same time, prevented from returning by the veins: owing to the com- bination of these causes, the brain is raised during expiration. In in- spiration, all this pressure is removed ; the blood is free to pass equally by the descending and ascending aorta ; the return by the veins is ready, and the brain therefore sinks.^ "We can thus, also, explain why the face is red and swollen during crying, running, straining, and the violent emotions ; and why pain is augmented in local inflammation of an extremity, — as in cases of whitlow; and when respiration is hur- ried or impeded by running, crying, &c. The blood accumulates in the part, owing to the compound efi:ect of increased flow by the arte- ries, and impeded return by the veins. The same explanation applies to the production of hemorrhage by any violent exertion ; and M. Bourdon^ affirms, that he has always seen hemorrhage from the nose largely augmented during expiration ; diminished at the time of in- spiration; and arrested by prolonged inspiration; — a therapeutical fact of some interest. Experiments with the haemadynamometer by Poiseuille, and Ludwig,^ confirm those mentioned above: — the column of mercury having been found to rise at each expiration, and to sink dui'ing inspiration. It has often been remarked, too, that in forced and deep inspiration the force of the heart becomes so much diminished, that the pulse is very slow and feeble, and in some cases cannot be felt.* This pheno- menon had attracted the attention of Weber® and Bonders ;^ and has been the subject of numerous experiments by Dr. S. W. Mitchell.^ All admit that an accumulation of blood takes place in the right side of the heart under such circumstances ; and that such is the fact was de- monstrated in the subject of a remarkable case of congenital absence ' Precis, &c., ii. 421. 2 This motion of the hrain must not he confounded with that which is synchronous with the contraction of the left ventricle ; and is owing to the pulsation of the arteries at the base of the brain. * Recherches sur la Meclianisme de la Respiration et sur la Circulation du Santr. Paris, 1820 : see, also, Longet, Anatomic et Physiologie du Systeme Nerveux, pp. 777 and 779. •• Miiller's Archiv. fiir Anatomie, u. s. w., Heft. iv. s. 242, Berlin, 1847. 5 J. xMiiller, Lehrbuch der Physioloc;., i. 198 ; and Todd and Bowman, The Physiolo- gical Anatomy and Physiology of Man, Pt. iv. p. 363, Loud., 1S52, or Amer. edit., Philad., 1853. 6 Miiller s Archiv., 1851, p. 88 ; and Canstatt's Jahresbericht, 1851, s. 124. ' Henle and Pfeuffer's Zeitschrift, B. iii. and iv. ; and Funke's Wagner's Lehrbuch der Ph3^siologie, s. 296, Leipz., 1854. * American Journal of the Med. Sciences, April, 1854, j). 387. FORCES THAT PROPEL THE BLOOD — RESPIRATION. 429 of the sterniTiTi, in wliicli the movements of the heart were visible. It was distinctly seen, that when the young man held his breath the right auricle was made once and a half larger, and thns became engorged.' In prolonged and deep inspiration the flow of blood to the heart by the veins — as has been shown — is greatly promoted, whilst its export by the arteries is correspondingly diminished; and it is probable that the temporary cessation of the heart's action is the result of the conse- quent engorgement. These experiments sufficiently show, that a power exists of suspending the heart's action momentarily ; and they throw some light on the extraordinary cases of suspended animation referred to elsewhere, (p. 403.) It is manifest, then, that the circulation is modified by the move- ments of inspiration and expiration,^ — the former facilitating the flow of blood to the heart by the veins, and the latter encouraging the flow from it by the arteries; and we shall see hereafter, that the dilatation of the chest, — which constitutes the first inspiration of the new-torn child, — is the cause of the establishment of the new circulation ; the same dila- tation, which causes the entrance of air into the air-cells, soliciting the flow of blood, or the " inspiration of venous blood," as M. Magendie^ has termed it. In a paper read before the Eoyal Society of London, in June, 1835, Dr. Wardrop,'' — after remarking, that he considers in- spiration as an auxiliary to the venous, and expiration to the arterial, circulation, — attempts, on this principle, to explain the influence exerted on the circulation, and on the action of the heart, by various modes of respiration, whether voluntary or involuntary, under different circum- stances. Laughing, crying, weeping, sobbing, and sighing, he regards as efforts made with a view to effect certain alterations in the quantity of blood in the lungs and heart, when the circulation has been dis- turbed by mental emotions. The influence of ordinary respiration can, however, be trifling ; yet it has been brought forward by Sir David Barry* as the efficient cause of venous circulation. His reasons for this belief are, — the facts just mentioned, regarding the influence of in- spiration on the flow of blood towards the heart; and certain ingeni- ously modified experiments, tending to the elucidation of the same result. He introduced one end of a spirally convoluted tube into the jugular vein of an animal,— the vein being tied above the point where the tube was inserted, — and plunged the other into a vessel filled with a coloured fluid. During inspiration, the fluid passed from the vessel into the vein : during expiration, it remained stationary in the tube, or was repelled into the vessel. Dr. Bostock^ remarks, that he was pre- sent at some experiments, which were performed by Sir David at the Veterinary College in London, and it appeared sufficiently obvious, that when one end of a glass tube was inserted either into the large ' Lancet, June 23, 1855; and Anier. Journ. of the Med. Sciences, Oct., 1855, p. 483. * Dr. Clendinning's Report to the Brit. Association, 1839-40, in Lond. Med. Gazette, Nov. 13, 1840, p. 270. 3 Precis, &c., ii. 416. * On the Nature and Treatment of the Diseases of the Heart ; with some new views of the Physiology of the Circulation, Lond., 1837. * Experimental Researches on the Influence of Atmospheric Pressure upon the Circulation of the Blood, &c., Lond., 182(3. « Physiology, 3d edit., p. 330, note, Lond., 1836. 430 CIRCULATION. veins, into the cavity of tlie thorax, or into the pericardium, — the other end being plunged into a vessel of coloured water, — the water rose up the tube during inspiration, and descended during expiration. The conclusion of Sir David from these experiments is most compre- hensive ; — that "the circulation in the great veins depends upon atmo- spheric pressure in all animals possessing the power of contracting and dilating a cavity around that point, to which the centripetal cur- rent of their circulation is directed ; and he conceives, that as, during inspiration, a vacuum is formed around the heart, the equilibrium of pressure is destroyed, and the atmos])here acts upon the superficial veins, propelling their contents onwards to supply the vacuum; but in- dependently of other objections, there are a few that appear convincing against the sole agency of ordinary respiration in effecting venous cir- culation. According to Sir David's hypothesis, blood ought to arrive at the heart at the time of inspiration onl}^ ; and as there are, on the average, seventj^-two contractions of the heart for every eighteen in- spirations; or four contractions, or — what is the same thing — four dilatations of the auricle for each respiration; one of these only ought to be concerned in the propulsion of blood, whilst the rest should be bloodless; yet we feel no ditlerence in the strength of the four pulsations. It is clear, too, if we adopt Sir David's reasoning, that, of the four pulsations, two, and consequently two dilatations must occur during expiration, at which time the capacity of the chest is actually dimi- nished; and, again, the respiratory influence cannot be invoked to ex- plain the circulation in the foetus or in aquatic animals. At the most, therefore, respiration can only be regarded as a feeble auxiliary in the circulation. In favour of his opinion of the efficiency of atmospheric pressure in causing the return of the blood by the veins. Sir David adduces the fact, — already referred to, under the head of Absorption, — that the application of an exhausted vessel over a poisoned wound prevents the absorption of the poison ; but this, as we have seen, ap- pears to be a physical efiect, which would apply equally to any view of the subject. In all these cases, the elastic resilience of the lungs, b}^ contributing to diminish the atmospheric pressure from the outer surface of the auricles, may likewise, as suggested by Dr. Carson,^ have some agency in soliciting the blood into these cavities; but the agency cannot be great. It has recently been suggested by Liebig,^ that the fluids of the body, in consequence of the cutaneous and pulmonary transpira- tion, acquire a motion towards the skin and lungs ; but it is not easy to see that this could have any important eft'ect on the circulation. There is another circumstance of a purely physical nature, which may exert some influence upon the flow of the blood along the veins; the expanded termination of the venas cavee in the right auricle. To explain this, it is necessary to premise a detail of a few hydraulic facts. If an aperture A, Fig. 12-i, exist in a cistern X, the water will not issue at the aperture by a stream of uniform size; but, at a short distance ' Pliilosopliical Transactions for 1820, and An Inquiry into the Causes of Resjiiration, &c., 3d edit., Liverpool, 1833. 2 Researches on the Motion of the Juices in the Animal Body, by W. Gregory, M. D., p. 74, London, 1848. FORCES THAT PROPEL THE BLOOD — VENA CONTRACTA, 431 from the reservoir, it will be contracted Fig. 124. as at B, constituting what has been termed the vena contracta. Now, it has been found, that if a tube technically called an adjutage be attached to this aperture, so as to accurately fit the stream, as at A B, Fig. 125, as much fluid will flow from the reservoir as if the aperture alone existed. Again, if the pipe B C be attached to the adjutage A B, the expanded ex- tremity at A will occasion the flow of water from the reservoir to be greater than it would be if no such expanded extremity existed, in the ratio, accord- Vena Contracta. ing to Venturi, of 12"1 to 10; and if to the tube B C, a truncated conical tube C D be attached, the length of which is nearly nine times the diameter of C ; and the diameter of C to that of D be as 1 to8; the flow of Fig. 125. water will be aug- mented in the pro- portion of 24 to 12*1; so that, by the two adjutages A B and C D, the ex- penditure through the pipe B C is in- creased in the ratio of 24 to 10. This Vena Contracta. fact, — the result of direct experiment, and so important to those who contract to supply water by means of pipes, — was known to the Komans. Private per- sons, according to Frontinus,' were in the habit of purchasing the right of delivering water in their houses from the public reservoirs, but the law prohibited them from making the conducting pipe larger than the opening allowed them in the reservoir, within the distance of fifty feet. The Roman legislature must, therefore, have been aware of the fact, that an adjutage with an expanded orifice, would increase the flow of water ; but they were ignorant that the same effect would be induced beyond the fifty feet. A case — "The Schuylkill Navigation Company agaiiist Moore" — was tried in March term, 1837, before the Supreme Court in Pennsylvania, in which these hydraulic principles were in- volved. The defendant had conveyed to him by the plaintifts a certain lot of ground, together with the privilege of drawing from the Schuyl- kill canal as much water as would pass through two metallic apertures of a size mentioned. He applied, however, to the aperture a conical tube or adjutage by which the flow of water was proved to have been ' De Aquseductibus Urbis Romse Commentarius, 190, 37, Patav., 1722. 432 CIRCULATION. greatly augmented. It was decided, that lie had no right to increase the flow by such agency/ Let us apply this law of hj^draulics to the circulation. In the first place, at the origin of the pulmonary artery and aorta, there is a mani- fest narrowness, formed b}^ the ring at the base of the semilunar valves: this might be conceived unfavourable to the flow of the blood along those vessels during the sj^stole of the ventricles ; but from the law, which has been laid down, the narrowness would occupy the natural situation of the vena contracta, and, therefore, little or no effect would be induced. The discharge would be the same as if no such narrow- ness existed. We have seen, again, that the vena cava becomes of larger calibre as it approaches the right auricle, and finally terminates in that cavity by an expanded aperture. This may have a similar effect with the expanded tube D, Fig. 125, which doubles the expenditure.* In making these conjectures, — some of which have been adduced by Sir Charles Bell, — it is proper to observe, that, in the opinion of some natural philosophers, the effect of the adjutage is entirely due to atmo- spheric pressure, and that no such acceleration occurs, provided the experiment be repeated in vacuo. Sir Charles BelP conceives, that " the weight of the descending column in the reservoir being the force, and this operating as a vis a tergo^ it is like the water propelled, from the^e^ cTeau^ and the gradual expansion of the tube permits the stream from behind to force itself between the filaments, and disperses them, without producing that pressure on the sides of the tube, which must take place, where it is of uniform calibre." It is on this latter view only, that these hydrostatic facts can be applied to the doctrine of the circulation. In addition to the movements impressed on the blood by the parietes of the cavities in which it moves, it has been considered by many phy- siologists, — as by Ilarvey, Glisson, Bohn, Albinus, Rosa, Tiedemann, G. R.. Treviranus,^ Rogerson,^ Alison,^ and others, — to possess a power of automatic or self-motion. M. Broussais^ asserts, that he has seen experiments, — originally performed by M. P. A. Fabre, which showed, that the blood, in the capillary system, frequentl}^ moves in an oppo- site direction to that given it by the heart, — repeated by M. Sarlan- diere on the mesentery of the frog. In these, the blood was seen to rush for some moments towards the point irritated ; and, when a con- gestion had taken place there, they remarked, that the corpuscles took a different direction, and traversed vessels which conveyed them in an opposite course; and, a few seconds afterwards, they were again ob- served to return with equal rapidit}'' to the point from which they had been repelled. Tiedemann" has collected the testimonies of various ' Reports of Cases adjudged in the Supreme Court of Pennsylvania, in the Eastern District, by Thomas I. Wharton, voL ii. p. 477, PhiLndelphia, 1837. ^ Ventui'i, Sur la Communication Laterale du Mouvement dans les Fluides, Paris, 179S. 3 Animal Mechanics, p. 40, in Library of Useful Knowledge, Lond., 1829. ■• Tietleniann, Traite Complet de Physiologic de I'Homme, traduit par Jourdan, i. 348, Paris, 1831. ^ A Treatise on Inflammation, &c., Lond., 1832. ^ Edinburgh Med. and Surg. Journal for Jan., 1836. '' Traite de Physiologie, &c., translated by Drs. Bell and La Roche, 3d edit., p. 374, Philad., 1832. » Op. citat. FORCES THAT PROPEL THE BLOOD — AUTOMATIC POWER. 433 individuals on this ]-)oint. Ilaller/ Spallanzani,^ Wilson Philip,^ Gr. R. Treviranns," and others, have remarked, by the aid of the microscope, that the blood continued to move in the vessels of different animals, but chiefly of frogs, for some time after the great vessels had been tied, or the heart itself removed ; — a fact which Tiedemann, also, often wit- nessed. C. F. Wolff"^ Rolando,'^ Dollinger and Pander,^ Provost and Dumas,* Von Baer,^ and others,^" saw blood corpuscles in motion in the incubated egg, before the formation of either vessels or heart ; and Hunter, Gruithuisen, and Kaltenbrunner observed, — in the midst of the areolar tissue of inflamed parts, in tissues undergoing regeneration, and during the cicatrization of wounds, — bloody points placed suc- cessively in contact with each other, forming small currents, which represented new vessels, and united to those already existing. The fact, indeed, that the embryo forms its own vessels, and that blood in motion can be detected before vessels are m esse, is a sufficient proof, — were there no other, — that the corpuscles of the blood possess the faculty of motion, either in themselves, or by virtue of an attraction exerted upon them by the solid parietes in which they move. Miiller^^ thinks the idea of spontaneous motion in a fluid, independently of attraction or repulsion from the sides of another object, is inconceiv- able ; and as Tiedemann'^ has remarked, if we admit this faculty in animals provided witli a heart, the progression of the blood must be mainly owing to that viscus ; for, after the heart ceases to act, the cir- culation is soon arrested. The blood, too, only remains fluid, and possesses the faculty of motion, whilst it is in connexion with the living body. When taken from the vessel in which it circulates, it soon coagulates, and loses its motive power. This motion has, by some, — and, according to Brand t,^'^ not without grounds, — been presumed to be owing to electro-chemical agency. Burdach^^ has properly observed, that the ^Id but perfectly correct saying, " ubi stimulus ibi affiuxus,^'' means nothing more than that where the vital activity of an organ is augmented, more blood will be drawn to it ; whence it naturally follows, that the progression of blood in the capillaries must be, in some measure, dependent on the activity of the vital manifestations in the tissue. It has been already shown, that if the capillary action be excited by stimulants, a greater flow of blood takes place into that system of vessels; and as the functions of ' Oper. Minor., i. 115, sect. 8. ^ Exper. on the Circulation, &c., in Eng. by R. Hall, Lond., 1801. * Pliilos. Transact., 1815 ; and Medico-Chirurg. Trans., vol. xii. * Vermischte Scliriften, i. 102. ^ Tlieoria Generationis, Hal., 1759. ^ Dizionario Periodico di Medicina, Torino, 1822-1823. ' Dissert, sist. Hist. Metamorijhoseos quam Ovum Incubatum prioribus quinque Diebus subit, Wirceb., 1817. * Annales des Sciences Naturelles, torn. xii. p. 415, Dec, 1827. ^ Ueber die Entwickelungsgeschiclite der Thiere, u. s. w., Th. i. KiJnigsberg, 1828. '" Allen Thomson, On the Formation of New Bloodvessels, Edinb., 1832; and art. Circulation, in Cyclopajdia of Anat. and Ph3^siology, p. 7, Lond., 183G. " Handbuch, u. s. w., Baly's translation, p. 224, Lond., 1838. '^ Op. cit., p. 349. " Art. Blut, in Encyclopiid. Worterb. der Medicinisch. Wissenschaft. v. 596, Berlin, 1830. '* Die Physiologie als Erfalirungswissenschaft, &c., Band, iv., Leipz., 1832. VOL. I. — 28 434 CITvCULATION. nutrition and secretion are accomplished by that sj^stem, it is olDvious, that any increase in the activity of those functions must attract a harger afflux of fluids, and, in this manner, modify the circulation independ- entl}^ of the heart and larger vessels. But this, again, can have but a subordinate influence on the general circulation. Lastly, M. RaspaiP resolves the whole of the circulation, as h^ does other functions, into a double action of aspiration and expiration by the tissues concerned. As the blood is the bearer of life to every part of the organism, and of nourishment and reparation to the organs, — to prevent its destination being annulled, a part of the fluid, he says, must be absorbed by the surfaces, which it bathes: these surfaces must attract nutritive juices from the blood, and they must return to the blood the refuse of their elaboration, — in other words, they must aspire and expire. Now, this double function cannot take place without the fluid being set in motion, and this motion must be the more constant and uniform as the double function is inherent in every molecule of the surface of the vessels. In this way he accounts for the mercur}'', placed in a tube communicating with an artery, being kept at the same height near to, or at a distance from, the heart ; because, he says, it is not the action of the heart which supports it, but the action of the parietes of the vessels. Every surface, which aspires, provided it is flexible, must be, in its turn, he conceives, attracted by the substance aspired, and, consequently, by the act of aspiration alone, the motions of systole and fcliastole of the heart and arteries may be explained. When their inner parietes aspire — or assimilate the fluid, — the heart will contract; when, on the contrary, they expire, — owing to the mutual repulsion between the heart and the fluid, the former dilates; and, as the movements of the heart are energetic on account of its size, its movements will add to the velocity of the circulation in the arte- ries, which will, therefore, besides their proper actions of aspiration and expiration, present movements isochronous with the pulsations of the heart. " Add to this accessory cause of arterial pulsations the movements impressed by the aerial aspiration, which takes place in the lungs, and the circulation of the blood will no longer present in- surmountable problems." All this, it need scarcely be said, is ingenious; but nothing more. f. Accelerating and Retarding Forces. The above are the chief accelerating causes of the circulation. There are others, that at times accelerate, and at times retard ; and others, again, that must always be regarded as impeding influences. All these are of a physical character, and applicable as well to inert hydraulic machines as to the pipes of the human body. 1. Friction always acts as a retarding force. That which occurs between a solid and the surface on which it moves, can be subjected to calculation, but not so with a fluid, inasmuch as all its particles do not move equally : whilst one part is moving i-apidly, another may be stationary, moving slowly, or even in a contrary direction, as is seen in rivers, where the middle of the stream always flows with greater velo- ' Chimie Organique, p. 364, Paris, 1833. ACCELERATING AND RETAEDING FORCES — CURVATURES. 435 city than the sides. The same thing happens to water flowing through pipes; the water, which is in contact with the sides of the pipe, moves more slowly than that at the centre. This retarding force is much diminished by the polished state of the inner surface of the bloodves- sels, as is proved by the circumstance, that if we introduce an inert tube into an artery, the blood will jiot flow through it for any length of time. M. Poiseuille^ infers, from his investigations, that a still layer of serum lines the interior of the capillary vessels, which may have some effect in retarding the blood globules in their progress through the intermediate system. Yet the viscosity of the blood, within certain limits, would seem to be important to enable it to pass through the capillary system. M. Magendie, indeed, pronounces it to be an indis- pensable condition for its free circulation through the capillaries.^ 2. Gravity may either be an active or retarding force, and is always exerting itself, in both ways, on different sets of vessels. If, for ex- ample, the flow of blood to the lower extremity by the arteries is aided in the erect attitude b}^ the force of gravity, its return by the veins is retarded by the same cause. The pulse of a person in health beats slower when he is in the recumbent, than in the erect, attitude. This is owing to there being no necessity for the heart to make use of un- usual exertions for the purpose of forcing the blood, against gravity, towards the upper part of the body. In therapeutics, the physician finds great advantage from bearing this influence in mind; and, hence, in diseases of the head, — as in inflammation of the brain, in apoplectic tendency, ophthalmia, &c., — he directs the patient's head to be kept raised; whilst in uterine affections the horizontal posture, or one in which the lower part of the body is raised even higher than the head, is inculcated ; and in ulcers or inflammatory diseases of the lower extremities, the leg is recommended to be kept elevated. Every one, who has had the misfortune to suffer from whitlow, has experienced the essential difference in the degree of pain produced by position. If the finger be held down, gravity aids the flow of blood by the arteries, and retards its return by the veins: the consequence is turgescence and painful distension ; but if it be held higher than the centre of the cir- culation, the flow by the arteries is impeded, whilst its return by the veins is accelerated, and hence the marked relief afforded. 8. Curvatures. — Besides friction, the existence of curvatures has con- sic|prablc effect on the velocity and quantity of the fluid passing through pipes. A jet does not rise as high from the pipe or adjutage of a reser- voir, if there be an angular turn in it, as if the bend were a gradual curve or sweep. The expense of force, produced by such curvatures in arteries, is seen at each contraction of the ventricle, — the tendency in the artery to become straight producing an evident movement, which has been called locomotion of the artery^ and has been looked upon, by some, as the principal cause of the pulse. This motion is, of course, more perceptible the nearer to the heart, and the greater the vessel ; hence it is more obvious at the arch of the aorta; and we can now understand why this arch should be so gradual. There is a good ex- ' Biblioth. Universelle, Nov., 1835. 2 Lectures on the Blood, edit, cit., p. 102, Philad., 1839. 436 CIRCULATIOX. ample of the force used in this effort at straightening the arterj^, in the case of the popliteal artery, when the legs are crossed, and a curvature is thus produced. The force is sufficient to raise a weight of upwards of iifty pounds at each contraction of the ventricle, notwithstanding it acts at the extremity of so long a lever. This fact is sufficient to exhibit the inaccuracy of the notion of MM. Bichat and Bricheteau,^ that the curvatures in the arteries can have no effect in retarding the flow of blood. Such could only be the case, Bichat thinks, if the ves- sels were empty at each systole. 4. Anastomoses. — The anastomoses of vessels have, doubtless, also some influence on the course of the blood ; but it is impossible to ap- preciate it. The superficial veins are especially liable to have the circulation impeded by compression in the different postures of the body ; but by means of the numerous anastomoses if the blood cannot pass by one channel, it is diverted into others. Although, however, a forcible compression may arrest or retard the flow by those vessels, a slight degree of support prevents the vein from being dilated by the force of the blood passing into it, and thus favours its motion. The constant pressure of the skin hence facilitates the circulation through the subcutaneous veins, and if, by any means, the pressure be dimin- ished, especially in those parts in which the blood has to make its way against gravity — as in the lower extremities — varices or dilatations of the vessels supervene, which are remedied b}^ the mechanical compres- sion of an appropriate bandage. Attempts have been made to calculate the velocity with which the blood proceeds in its course ; and how long it would take for a blood corpuscle, setting out from the left side of the heart, to attain the riglit side. It is clear, that the data are, in the first place, totally insuffi- cient for any approximation. We know not the exact quantity of blood contained in the vessels ; — the amount sent into the artery at each contraction of the ventricle; the relative velocity of the arterial, venous, and capillary circulations; — and, if we knew them at any one moment, they are liable to incessant fluctuations, which would preclude any accurate average from being deduced. Were these circumstances insufficient to exhibit the inanity of such researches, the varying esti- mates of difi'erent observers would establish it. These assign the time occupied in the circulation from two minutes to fifteen or twenty hours ! Moreover, the distances which the corpuscles have to traverse must be various. In the heart, the passage from one side to the other by the coronary vessels is very short ; whilst if the blood has to proceed to a remote part of the body, the distance is considerable. Were we to regard the vascular system as forming a single tube; — by knowing the weight of the blood and the quantity which the left ventricle is capable of sending forward at each contraction, we could calculate with facility the period that must elapse before an amount equal to the whole mass is distributed. Thus, if we estimate, with many physiologists, the quantity propelled forward at each contraction of the ventricle to be two ounces ; and the whole mass of blood to be ' Clinique Medicale, p. 145, Paris, 1835 ; or the author's transLition in his American Medical Library, Philad., 1837. VELOCITY OF THE CIECULATION. 437 30 pounds, it will require, on an average, about 240 beats of the heart to send it onAvards; which can be accomplished in little more than 3 minutes, yet, notwithstanding the absence of the requisite data, a modern writer has gone so far as to affirm the average velocity of the blood in the aorta to be about eight inches per second; whilst "the velocity in the extreme capillaries is found to be often less tban one inch per minute!" A similar estimate was made by Dr. Young:' Hales^ estimated the velocity of the blood, leaving the heart at 149'2 feet per minute, and the quantity of blood passing through the organ every hour at twenty times the weight of the blood in the body; but the judicious phj^siologist knows well, that in all operations, which are, in part, of a vital character, the results of every kind of calcula- tion must be received with caution. In the larger animals, as the whale, the quantity of the fluid circulating in the aorta must be pro- digious. Dr. Hunter, in his account of the dissection of a whale, states that the aorta was a foot in diameter, and that ten or fifteen gallons of blood were probably thrown out of the heart at each stroke; so that this vessel is, in .the whale, actually larger than the main pipe of the old water- works at London Bridge; and the water, rushing through the pipe, it has been conceived, had less impetus and velocity than that gushing from the heart of this leviathan.^ But the highest of these estimates, as to the velocity of the circula- tory current, is probably far beneath the truth, inasmuch as experi- ments have shown, that substances introduced into the venous circula- tion may be detected in the remotest parts of the arterial circulation in animals larger even than man in less than thirty seconds. Ten seconds after having injected a solution of nitrate of baryta into the jugular vein of a horse, Dr. Blake,'* formerly of Saint Louis, drew blood from the carotid of the opposite side: after allowing this to flow for five seconds, he received the blood that flowed during the next five seconds into another vessel; and that which flowed after the twentieth second, by which time the action of the lieart had stopped, was re- ceived into a third vessel. No trace of baryta could be detected in the blood that flowed between the tenth and fifteenth seconds ; but it was discovered in that which flowed between the fifteenth and twenti- eth. In a dog, the poisonous effects of strychnia on the nervous sys- tem appeared in twelve seconds after injection into the jugular vein; in a fowl in six and a half seconds; and in a rabbit in four and a half seconds, — the interval being in an inverse ratio to the velocity of their respective circulations. From the results of these and other experi- ments, Dr. Carpenter thought it difficult to resist the conclusion, that some other force than the contractions of the heart must have a share in producing the movement of the blood through the vessels.^ If, however, we adopt the estimate of the average quantity of blood dis- ' An Introduction to Med. Literature, p. G09, Lond., 1813. * Statical Essays, vol. ii. p. 40, Lond., 1733. ' Paley's Natural Theology, and Animal Physiology, p. 75, Library of Useful Know- ledge, Lond., 1829. '' Edinb. Med. and Surg. Journal, Oct., 1841 ; St. Louis Medical and Surgical Journal, Nov. and Dec, 1848 ; and American Journal of the Medical Sciences, p. lOU, July, 1841. " Human Physiologj^, § 491, Lond., 1842. 438 CIRCULATIOZS". charged by tbe left ventricle at each contraction, as given bj^ Valentin,' — (oz. 5'o,) and still more that given by Volkmann (oz. (3'2) — a part of the difficulty is removed. According to the data of the former thirty pounds of blood would require 90 contractions of the ventricle, which would be accomplished in about a minute and a third, — Mr. Paget says in from -ISf to 62f seconds, — the discordance being owing to the varying estimates as to the quantity of blood in the body. If we take the estimate of the amount of blood by Dr. Blake (page 357), it could be accomplished in from 58 to 60 contractions of the ventricle, or in from 44 to 50 seconds. Valentin's estimate of the quantity sent out at each contraction is probably, however, too high: — three ounces may be nearer the mark. With this velocity of the general circulation, it seems at first diffi- cult to comprehend its slowness of progression in the capillary vessels, which in the frog, according to Valentin,^ from many careful micro- metric examinations, is from 0'938 to l'-4 English inch per minute. In the small veins, he says, it is about |th faster. These velocities, as Mr. Paget'^ remarks, agree nearly with those of Hales,^ who estimated the velocity at an inch in a minute and a half; and more nearly still with those of Weber, who found it 1|: inch per minute. On examin- ing with the microscope the circulation in the tongue of the frog, the blood is observed streaming with immense velocity through the larger vessels, whilst in those that admit but a single file of red corpuscles, the motion is as slow as described by those observers. It has been well remarked by Messrs. Kirkes and Paget,* that the speed at which the blood may be seen moving in transparent parts is not opposed to the calculations of Valentin and others; inasmuch as, although the movement through certain capillaries may be very slow, the length of capillary through which any portion of blood has to pass is very small. " If we estimate that length at the tenth of an inch, and suppose the velocity of the blood therein to be only one inch per minute, then each portion of blood may traverse its own dis- tance of the capillar}^ system in about six seconds. There would thus be plenty of time left for the blood to travel through its circuit in the larger vessels, in which the greatest length of tube that it can have to traverse in the human subject does not exceed ten feet." The obser- vations of Volkmann,^ on the mesenteric arteries of the dog make the rate of flow about 'OS inch per second or 1'8 per minute; and com- paring this with the rate in the larger arteries, which appeared to be, on the average, 11 '8 inches per second, it is calculated by him, that the aggregate area of the capillaries must be nearly four hundred times that of the arterial trunks, which supply them. The instrument with which he measured the velocity of the current in the vessels and to which he gave the name hcemodrometer consists of a glass tube, fifty- two inches long, bent into the form of a hair pin, and containing water, which he substituted for a segment of the bloodvessel, the velo- city of whose blood current he was desirous of estimating. The ' Lehrbncli der Physiologie des Menschen, i. 415, Bramisoliweig, 1844. 2 Op. cit. ' " ' Loc. cit. ^ Op. citat., ii. 68. 5 Maimal of Physioloey, 2d Amer. edit., p. 117, Pliilad., 1853. *■ Haemodjnamik, s. 184, 204, and Carpenter, Principles of Human Physiol., Amer. edit., p. 269, Pliilad., 1855. VELOCITY OF THE CIRCULATION. 439 columii of blood from the heart pushes the column of water before it, without much admixture of the fluids taking place; and the distance through which it passes in a given time is a measure of its velocity.^ The velocity of the circulating fluid in the smaller arterial vessels is generally thought to be less than in the larger ; and their united cali- bres to be much greater than that of the trunk with which they com- municate. Were this the case, the diminution of velocity would be in accordance with a law of hydrodynamics ; — that when a liquid flows through a full pipe, the quantity which traverses the different sections of the pipe in a given time must be every where the same ; so that where the pipe is wider the velocity diminishes : and, on the contrary, where it is narrower the velocity increases. This would not seem, however, to be consistent with the calculations of Dr. T. Young, and Weber, and the experiments of M. Poiseuille, already referred to, which Drs. Spengler^ and Valentin^ concur in, but Yolkmann and Ludwig oppose,'' which show, that the pressure exerted on the blood in different parts of the body — as measured by the column of mer- cury, which the blood in different arteries will sustain — is almost exactly the same. The cause of error in the common belief, — that the capacity of the arterial tubes increases in proportion to their distance from the heart, — has been explained by Mr. Ferneley^ and others. It is true, he ob- serves, that the sum of the diameters of the branches is considerably greater than that of the trunk. Thus a trunk, 7 lines across, may divide into two branches of 5 lines each; or a trunk of 17 into three branches of 10, 10, and 9|-; but when their areas are compared, which is the only mode of arriving at their calibres, the correspondence is as close as can be reasonably expected, when the nature of the measure- ment is taken into account. In the first case, the area of the trunk is represented by the square of 7 — that is 49 ; whilst the area of each branch will be 25, and the sum of the two will be 50. In the second instance, the area of the trunk will be 17 squared, or 289 ; whilst that of the branches is the sum of 100, 100, and 90^, making 290|. This will be more strikingly seen from the following table of measurements of the mesenteric artery of the sheep by Mr. Ferneley. Trunks. Branches Diameter. Square of Diameter. Diameter. Sum of S(£uares o )iameter. I. 9 81 7-5 + 5 81-25 n. 7-2 51-64 6-f 4 52 TIL 3-5 12-25 3+2 13 IV. 7-0 49 5+5 50 V. 17 289 10 + 10 + 9-5 290-25 VI. 10 100 7+7 + 2 102 VII. 4-5 20-25 3-5 + 3 21-25 VIII. 8 64 4+7 65 ' Todd and Bowman's Physiological Anatomy, &c., Pt. iv. p. 3G5, Lond. 1852, or Amer. edit., Philad., 1853. ^ Miiller's Archiv., 1844, Heft i. ^ Op. cit., p. 456. * Carpenter, Op. cit., p. 266; Todd and Bowman, Op. cit., Pt. iv. p. 361, Lend., 1852, or Amer. edit., Philad., 1853; and Funke's Wagner's Lehrbuch der specielleu Physiologie, s. 85, Leipzig, 1854. " Loudon Medical Gazette, Dec. 7, 1839. 440 CIRCULATION. It will be observed, that the sum of the squares of the diameters of the branches is in every case slightly more than the square of the diameter of the trunk. The discrepancy was found to be somewhat greater in subsequent experiments made by Mr. Paget.^ The follow- ing table gives the ratio of the area of each arterial trunk to the joint area of its branches, as observed by him :— - Trunk. Branches. Arch of the aorta ...... 1 Innominata ....... 1 Common carotid ...... 1 External do. ....... 1 Subclavian ....... 1 Abdominal aorta to the last lumbar arteries . 1 just before dividing . . 1 Common iliac ....... 1 External iliac ....... 1 1-055 1-147 1-013 1-19 1-055 1-183 •893 -982 1-15 Analogous experiments by actual admeasurement, made by Mr. Erskine Hazard,^ of Philadelphia, lead to a similar conclusion. In many of them, however, the area of the trunks was found to be greater than that of the branches near them. It would appear, that where the aorta divides into the common iliacs, or at the division next lower down, the stream is always contracted ; the effect of which must necessarily be to accelerate the circulation not only in the iliacs them- selves, but in the arteries given oft" from the trunk above them, — as the mesenteric and the renal. From what has been said regarding the curvatures and angles of vessels, it will be understood, that the blood must proceed to different organs with different velocities. The renal artery is extremely short, straight, and large, and must transmit the blood very differently to the kidney, from what the tortuous carotid does to the brain; or the spermatic artery to the testicle. A different impulse must, conse- quently, be made on the corresponding organs by these different ves- sels. A great portion, however, of the impulse of the heart must fail to reach the kidney, short as the renal artery is, owing to its passing off from the aorta at a right angle ; and, hence, the impulse of the blood on that organ may not be as great as might be imagined at first. The tortuosity of the carotid arteries is such as to greatly destroy the impetus of the blood; so that but trifling hemorrhage takes place when the brain is sliced away on a living animal, although it is pre- sumed, that one-eighth of the whole quantity of blood is sent to the encephalon. Dr. Push supposed, that the use of the thyroid body is to break the afflux of blood to the brain ; for which its situation be- tween the heart and head appeared to him to adapt it; and he adduced, as farther arguments, — firsts the number of arteries it receives, although effecting no secretion ; secondly^ the effect on the brain, which he con- ceived to be caused by disease, and extirpation, of the thyroid ; the operation having actually occasioned, in his opinion, in one case, in- flammation of the brain, rapidly terminating fatally ; and, thirdly^ the fact that goitre is often accompanied by idiotism. The opinion, how- ' London Medical Gazette, July 8, 1842. * Horner, Special Anatomy and Histology, 8th edit., ii. 167, Philad., 1851. VELOCITY OF THE CIRCULATION — DIVERTICULA. 441 ever, is so entirely conjectural, and some of the fads, on whicli it rests, so questionable, that it does not demand serious examination. This leads us to remark, that the thyroid body as well as other organs, with Avhose precise functions we are not well acquainted, — as the thymus, spleen, and supra-renal capsules, — have been conceived to serve as diverticula or temporary reservoirs to the blood, when, owing to special circumstances, that fluid cannot circulate properly in other parts of the frame. M. Lieutaud having observed, that the spleen is always larger when the stomach is empty than when full, considered that the blood, when digestion is not going on, reflows into the spleen, and that thus this organ becomes a diverticulum to the stomach. The opinion has been indulged bj many, with more or less modification. Dr. Rush's view was more comprehensive. He regarded the organ as a diverticulum, not simply to the stomach, but to the whole system, when the circulation is greatly excited, as in passion, or in violent mus- cular eftbrts, at which times there is danger of sanguineous congestion in different organs; and in support of this view, he invoked its spongy nature ; the frequency of its distension ; the large quantity of blood distributed to it ; its vicinity to the centre of the circulation ; and the sensation referred to it, in running^aughing, &c. M. Broussais' has still farther extended the notion of i|&verticula. He affirms, that they always exist in the vicinity of organs, whose functions are manifestly intermittent. In the foetus, the blood does not circulate through the lungs as when respiration has been established: hence, diverticula are necessary: these are the thymus and thyroid glands. The kidneys do not act in utcro ; hence the use of the supra-renal capsules as diver- ticula. At birth, these organs are either wholly obliterated, if the organs to which they previously served as diverticula have continuous functions ; or they are partly obliterated, if the functions be intermit- tent. Thus, the spleen continues as a diverticulum to the stomach, because its functions are intermittent through life; and the thj^mus disappears when respiration is established: the liver and the portal system he regards as a reservoir for the reception of blood in cases of impediment to the circulation in different parts of the body. These notions are entirely hypothetical. We shall see, hereafter, that our ignorance of the offices of the spleen, thymus, &c., is great ; and we have already shown, that much more probable uses can be assigned to the portal system. The insufficiency of M. BrouSsais's doc- trine of diverticula is strikingly evidenced by the fact, that whilst the thymus gland disappears gradually in the progress of age, the thyroid remains, as well as the supra-renal capsules.^ The nature of the circulation in the brain, as well as the advantages of the tortuous arrangement of the carotids, which convey a great por- tion of the blood to it, has been referred to before.^ From the mode in which its vessels — arterial and venous — are distributed to it, a uniform supply of blood is secured; and it has been presumed, that this uni- formity exists to such a degree, that no augmented quantity of blood ' Commentaires des Propositions de Pathologie, &c., Paris, 1829; or translation, p. 214, Philad.,1832. ^ Adelon, Phvsiologie de I'llomme, torn. iii. 328, 2de Odit., Paris, 1829. » VoL i. p. 1U7. 4:4:2 CIRCULATION. can exist in it so as to exert undue pressure on the cerebral neurine. Resting chiellj on the recorded results of certain experiments by Dr. Ivellie/ of Leith, many modern physiologists and therapeutists have maintained, that the quantity of blood in the cranium never varies; and that the brain is incompressible. Under this notion, Dr. Clutter- buck^ affirmed, that no additional quantity of blood can be admitted into the vessels of the brain, the cavity of the skull being already filled by its contents. "A plethoric state or overfulness of the cerebral ves- sels altogether, though often talked of, can have no real existence; nor on the other hand can the quantity of blood ^Yithin the vessels of the brain be diminished ; no abstraction of blood, therefore, whether it be from the arm, or other part of the general system, or from the jugular veins (and still less from the temporal arteries), can have any effect on the bloodvessels of the brain, so as to lessen the absolute quantity of blood contained in them." Similar views were maintained by Monro Secundus,^ Dr. Abercrombie," — and it is affirmed by Dr. J. Hughes Bennett to be still the doctrine of "the Edinburgh school,"' — and they seemed to be supported by the experiments of Dr. Kellie, who inferred that, "in animals bled to death, whilst all the other organs of the body are nearly emptied of blood, the vessels of the brain contain the usual quantit}^; but that if, previous to'bleeding an animal, a hole be made in its cranium, and the brain be thus exposed, equally with other or- gans, to atmospheric pressure, its vessels, like those of other parts of the body, will be emptied as the animal bleeds to death." It was im- portant to establish the truth or inaccuracy of these views — influencing, as they were calculated to do, and have done, in so essential a manner, the therapeutics of encephalic affections; and this has been conclusively accomplished by Dr. Burrows.^ The experiments of Dr. Kellie were repeated by him, but with opiMsite results; and he concludes, that it is not a fallacy, as some suppose, that bleeding diminishes the actual quan- tity of blood in the cerebral vessels ; — that by it we not only diminish the momentum of the blood in the cerebral arteries and the Cjuautity supplied to the brain in a given time, but actually diminish the amount of blood in these vessels. "Whether," — he remarks — "the vacated place is replaced by serum or resiliency of the cerebral substance under diminished pressure, is a question into which I will not enter." Dr. Burrows farther investigated, whether position can affect the quantity of blood in the vessels of the encephalon, — the opinion of Dr. Kellie from the results of his experiments having been in the negative. Two full grown rabbits were killed by hydrocyanic acid, and whilst their hearts still pulsated, one was suspended by the ears; the other by the hind legs. In this manner, they were left for twenty-four hours; and before they were taken down for examination, a tight ligature was placed around the throat of each, to prevent, as effectually as possible, ' Medico-Cliirurgical Transactions of Edinburgh, i. 2. 2 Art. Apoplexy, Cyclopsedia of Practical Sledicine, American edit., by the author, Philad., 1844. * Observations on the Structure and Functions of the Nervous System, Edinb., 1783. * Pathological and Practical Researches on Diseases of the Brain and the Spinal Cord, Edinb., 183(!, or Amer. edit., Philad. * Lectures on Clinical Medicine, p. 143. 6 On Disorders of the Cerebral Circulation, Amer. edit., Philad., 1848. VELOCITY OF THE CIRCULATION — ERECTILE TISSUES, 443 any farther flow of blood to or from the head, after they were removed from their respective positions. The contrast in the appearance of the two animals was striking. The one presented a most complete state of antemia of the internal as well as the external parts of the cranium ; the other a most intense hyperemia or congestion of the same parts; and these opposite conditions induced solely by posture, and the gravitation of the blood. Like results were obtained expe- rimentally under the direction of Professor Donders. A portion of the skull of a rabbit was removed, the corresponding piece of the dura mater cut out, an accurately fitting portion of a watch-glass let into the opening, and the junction made air tight with gum. When by com- pressing the nose and mouth respiration was interrupted, within ten seconds the increased redness of the pia mater could be seen with the naked eye. This condition was made still more evident by the micro- scope; and some minutes always elapsed before the hyperaimia again diminished. A dependent position of the head also increased the hy- pera3mia; whilst rapid abstraction of blood very distinctly diminished the diameter of the vessels.' The erectile tissues offer a variety in the circulation, which requires some comment. Examples of these occur in the corpora cavernosa of the penis and clitoris; and in the nipple. They appear, according to Gerber,^ to consist of a plexus or rete of varicose veins enclosed in a fibrous envelope, with relatively minute interspaces, which are occu- ])ied and traversed in all directions by arteries, nerves, contractile fibres, and by elastic, fibrous and areolar tissue. The fibrous enve- lope, and trabeculge, according to Kolliker,-^ contain a considerable amount of unstriped muscular fibre. Of the particular arrangement of vessels in the corpora cavernosa of the generative organs mention will be made hereafter: the mode of termination of the arteries in the erectile tissues has not been suffi- ciently studied, nor are views uniform in regard to their mode of action; some being of opinion, that they aft'ord examples of vital ex- pansibility ; but as before remarked (page 420), excitation is fii'st induced in the nerves of the part — generally through the influence of the brain — and the turgescence of vessels is a consequence. Kcilliker maintains, that the office of the muscular fibres, which pass in every direction amongst the dilated veins is to keep them compressed in the intervals of erection; and that the excitant influence to erection, which is exerted on the nervous system, either directly or tlirough the influence of the brain, instead of causing contraction produces relaxation of the fibres, so as to admit of free distension of the cavern- ous vessels. It is not easy to see, however, how the nerve power sent to a muscle can cause it to become relaxed. The arrangement of the portal system of the liver is also peculiar, and has been given already (p. 354). ' Cited in Brit, and For. Med.-Chir. Rev., April, 1855, p. 352. * Elements of General Anatomy, by Gulliver, p. 298, Lond., 1842. * Mikroskopisclie Anatomie, 2ter Bd. S. 414, Leipz., 1854 ; or Sydenliam Society's edition of his Manual of Human Histology, or Amer. edit, of the same by Dr. Da Costa, p. U37, Philad., 1854. d-i-i CIRCULATION. g. The Pulse. "We Lave had occasion, more than once,- to refer to the subject of the pulse, or to the beat felt by the finger when applied over any of the larger arteries. Opinions have varied essentially regarding its cause. AVhilst most physiologists have believed it to be owing to distension of the arteries, caused by each contraction of the left ventricle; some have admitted a systole and diastole of the vessel itself; others, as Bichat and Weitbrecht,^ have thought that it is owing to the locomo- tion of the artery ; others, that the impulse of the heart's contraction is transmitted through the fluid blood, as through a solid body ; and others, as Dr. Young^ and Dr. Parry,^ that it is owing to the sudden rush forward of the blood in the artery without distension. Bichat was one of the first, who was disposed to doubt, whether the dilatation of the artery, which was almost universally admitted, really existed; or if it did, whether it was sufiicieut to explain the phenome- non; and, since his time, numerous experiments have been made by Dr. Parry, the result of which satisfied him, that not the smallest dila- tation can be detected in the larger arteries, when they are laid bare during life ; nor does he believe, that there is such a degree of loco- motion of the vessel as can account for the eft'ect produced upon the finger. He ascribes the pulse to " impulse of distension from the sys- tole of the left ventricle, given by the blood, as it passes through any part of an artery contracted within its natural diameter." Dr. Bos- tock'' appears to coincide with Dr. Parry, if we understand him rightly, or at all. " According to this doctrine," he remarks, " we must regard the artery as an elastic and distensible tube, which is at all times filled, although with the contained fluid not in an equally condensed state, and that the effect produced upon the finger depends upon the amount of this condensation, or upon the pressure which it exercises upon the vessel, as determined by the degree in which it is capable of being compressed. Where there is no resistance to the flow of the blood along the arteries, there is no variation, it is conceived, in their dia- meter, and it is only the pressure of the finger or some other substance against the side of an artery that produces its pulse." Most of the theories of the pulse take the contractility of the artery too little into account. In pathology, where we have an opportunity for observing the pulse in various phases, we meet with sensations, communicated to the finger, which it is difficult to explain upon any theory, except that of the compound action of the heart and arteries. The impulse is obviously that of the heart, and although the fact of distension escaped the observation of Bichat, Parry, Weitbrecht, La- mure, Dollinger, Rudolphi,* Jager,^ and others, we ought not to con- ' Comment. Acad. Imper. Scient. Petropol. ad An. 1734 and 1735, Petrop., 1740. * Croonian Lectures, in Pliilos. Transact, for 1809, part i. 3 An Experimental Inquiry into the Nature, Causes, and Varieties of the Arterial Pulse, by Caleb Hillier Parry, London, 1816; also, Additional Experiments on the Arteries of Warm-blooded Animals, &c., by Charles Henry Parry, M. D., &c., Loudon, 1819. * Physiology, 3d edit., p. 246, Lond., 1836. s Grundris's der Physiologie, 2ter Band. 2te Abtheil., s. 301, Berlin, 1828. '' Tractatus Anatomico-physiologicus de Arteriarum Pulsu., Virceb., 1830. PULSE. 445 elude, that it does not occur. It is, indeed, difficult for us to believe, that such an impulse can be communicated to a fluid filling an elastic vessel without pulsator}^ distension supervening. In opposition, too, to the negative observations of Bichat and Parr}^, we have the positive averment of Dr. Hastings, and of Poiseuille/ Oesterreicher, Segalas, and Wedemeyer, that the alternate contraction and dilatation of the larger arteries were clearly seen.^ M. Flourens encircled a large artery with a thin elastic metallic ring cleft at one point. At the mo- ment of pulsation the cleft part became perceptibly widened.^ The pulsations of the different arteries are pretty nearly sj'nchronous with that of the left ventricle. Those of the vessels near the heart may be regarded as almost wholly so; but an appreciable interval exists in the pulsations of the more remote. We have remarked, that the arterial system is manifestly more or less affected by the nerves distributed to it ; that it may be stimulated by irritants, applied to the great nervous centres, or to the nerves pass- ing to it ; and this is, doubtless, the cause of many of the modifications of arterial tension, noticed in disease. Inflammation cannot affect a part of the system, for any length of time, without both heart and arteries participating, and affording unequivocal evidence of it. This, however, is a subject that belongs more especially to pathology. The ordinary number of pulsations, per minute, in the healthy adult male, is from seventy to seventy-five; but this varies greatly according to temperament, habit of life, position, — whether lying, sitting, or stand- ing, kc. Dr. Guy,'' from numerous observations, found the pulse, in healthy males, of the mean age of 27 years, in a state of rest, 79 when standing; 70, sitting, and 67, lying; the difference between standing and sitting being 9 beats; between sitting and lying, 3 beats; and be- tween standing and lying, 12 beats. When all exceptions to the general rule were excluded, the numbers were; — standing, 81; sitting, 71; lying, 66; — the difference between standing and sitting being 10 beats; between sitting and lying, 5 beats ; and between standing and lying, 15 beats. The effect, produced, upon the pulse by change of posture. Dr. Guy ascribes to muscular contraction, whetlier employed to change the position of the bodj^, or to maintain it in the same position. In children, the difference between the pulse in the sitting and lying pos- ture is often very marked. In a boy, six years of age, observed by the author, it amounted to fifteen beats ; and Dr. Evanson^ states, that he has often found the pulse — which at night (during sleep) was 80, full and steady — up to 100 or even 120 during the day, small and hur- ried, — and this in children six or seven years of age, and in perfect health. In some individuals in health, the number of beats is singularly few. ' Repertoire generale d'Anatomle, &c., par Brescliet, 1829, torn. vi. and vii., and Magendie's Journal de Physiol., viii. and ix, ^ For a mode of estimating the arterial distension, see Poiseuille, in Magendie's Journal de Physiologic, ix. 44, and Jules Herison's description of an instrument — Splii/ginometer — which makes the action of the arteries apparent to the eye. '^ Kirkes and Paget, Manual of Physiology, 2d Amer. edit., p. 98, Philad., 1853. * Guy's Hospital Reports, No. vi., April, 1838, x>- 92. ^ Practical Treatise on the Management and Diseases of Children, by Messrs. Evan- son and Maunsell: Amer. edit., by Dr. Condie, p. 19, Philad., 1843. 446 CIRCULATION". The pulse of a person known to the author was on the average thirtj- six per minute; and Lizzari' affirms, that he knew a person in whom it was not more than ten. It is not improbable, liowever, that in these cases, obscure beats may have taken place intermediately, and yet not have been detected. In a case of pericarditis, in which the author felt great interest, the pulse exhibited a decided intermission every few beats, yet the heart beat its due number of times ; the intermission of the pulse at the wrist consisting in the loss of one of the beats of the heart. It was not improbable but that in this case the contractility of the aorta wus unusually developed by the inflammatory condition of the heart; and that the flow of blood from the ventricle was thus occasionally spasmodically diminished or entirely impeded. On the other hand, the natural pulse is, at times, far above the average, — 100 and upwards in the minute. It is affirmed that the pulse of Sir William Congreve'^ — the inventor of the well-known Congreve rockets — when he was in apparently good health never fell below one hundred and twenty- eight beats per minute. The quickest pulse, which Dr. Elliotson^ ever felt, was 208, counted easily, he says, at the heart; though not at the wrist. The pulse of the adult female is usually from ten to fourteen beats in a minute quicker than that of the male. In infancy, it is generally irregular, intermitting, and always rapid, and it gradually becomes slower in the progress of age. It is, of course, impossible to arrive at any accurate estimate of its comparative frequency at different pei'iods of life, but the following average by Ileberden,"* Somniering, and Mliller,* have generally been received. They are inaccurate, however, in regard to old age, more especially. Ages. Number of beats per minute, according to Ileberdeu. Siimmering. | Muller. In the embryo. At birth, . One month, One year. Two years. Three years, . Seven years, . Twelve years, . Puberty, . Adult, . Old age, . 130 to 140 120 120 to 108 108 to 90 90 to 80 72 70 120 no 90 80 70 60 150 Do. 115 to 130 100 to 115 90 to 100 85 to 90 80 to 85 70 to 75 50 to 05 A nearer approximation is given by Dr. Guy in the following table : — ' Raccolta D'Opusculi Scientific, p. 205 ; and Good's Study of Medicine, Physiolo- gical I'niern to class iii. II;ematica. See Cases of Slowness of Pulse, by Mr. Mayo, Lond. Med. Gaz., May 5, 1838, p. 232. 2 Adventures and Recollections of Colonel Landmann, late of the Corps of Royal Engineers, i. 12, London, 1852. ^ Human Physiology, p. 215, London, 1840. * Med. Transact., ii. 21. * Handbuch der Pliysiologie, Baly's translation, p. 171, London, 1838. PULSE — ACCOEDIXG TO AGE AXD SEX. 447 j Age. 1 Slaxinuim. Minimum. Mean. Range. 1 2to 5 128 80 105 48 5 to 10 124 72 93 52 10 to 15 120 68 88 52 15 to 20 108 56 77 52 20 to 25 124 56 78 68 25 to 30 100 53 74 47 30 to 35 94 58 73 36 35 to 40 100 56 73 44 40 to 45 104 50 75 54 45 to 50 100 49 71 51 1 50 to 55 88 55 74 33 55 to 60 108 48 74 60 60 to 65 100 54 72 46 65 to 70 96 52 75 44 70 to 75 104 54 74 50 75 to 80 94 50 72 44 80 and upwards, 98 63 79 35 Dr. Guy^ lays down the following as a near approximation to the average numbers at the several leacliDg periods of life. It must be borne in mind, that, as in all similar cases, such averages can never apply to special examples. At birth, 140 Adult age, 75 In infancy, 120 Old age, 70 Childhood, 100 Decrepitude, . . . 75 — 80 Youth, 90 Researches by MM. Hourmann and Dechambre,^do not accord with the estimates in respect to the smaller number of pulsations in the acred. MM. Leuret and Mitivie had suspected an error in this matter from an examination of 71 of the aged inmates of the Bicetre and La Salpe- tri^re. MM. Hourmann and Dechambre examined 255 women be- tween the ages of 60 and 96, and found the average number of the pulse to be 82-29. M. Rochoux,^ however, still believes— from the results of his own observations as well as those of others — that, as a general rule, the frequency of the pulse diminishes in the progress of age. The attention of Dr. Pennock,^ of Philadelphia, has more recently been directed to the subject ; and the author has great confidence in the authenticity of results recorded by him. In 170 males, and 203 females, of the average age of about 67, the average frequency of the pulse was 75. The difference between the pulse of the male and female continues to be well marked in advanced life. MM. Leuret and ]\Iitivie found the average frequency in 27 aged men, 73 ; and in 3-1 aged women, 79. The average obtained by Dr. Pen nock was 72 for the former ; 78 for the latter. Dr. Gorham* assigns 130 as the mean number of the pulse from five months to two years old; and 107-63 from two to four years, whence the number continues almost the same up to the tenth 3'ear. ' Art. Pulse, Cyclop, of Anat. and Physiol., Pt. xsxi. p. 183, Lond., May, 1848. * Archiv. Grenerales de Med. pour 1835. ^ Art. Pulse, in Diet, de Med., 2de edit., xxv. 619, Paris, 1842. * Amer. Journ. of the Medical Sciences, July, 1S47, i>. 68. * Lond. Med. Gaz., Nov. 25, 1837. 44:8 CIRCULATION. nis estimates, however, are much higher than those of ^l. Yalleix.^ M. Trousseau,^ from repeated observations, infers, that but little stress ought to be laid on the pulse in the diagnosis of disease in infants. lie found, that daring the first two weeks, it may vary from 78 to 150; during the second fortnight, from 120 to 164; from one to two months, from 96 to 132 ; two to six months, 100 to 162; six to twelve months, 100 to 160; and from twelve to twenty-one months, 96 to 1-10. From the observations of MM. Billard, Valleix, and others, it would seem, that the pulse of the fcjetus at the moment it is expelled from the uterus often falls to 83 in the minute, and, in some minutes afterwards, rises to 160. In the course of the first day, it falls again to 127, and con- tinues to diminish during the first ten days, the average being then from 87 to 90. These are, however, only averages : the variations are very great. Sex appeared to have some influence. In infants, from eight days to six months old, the average number of pulsations for boys was 131; for girls, 134; from six to twenty-one months, the average for boys was 113; for girls, 126. The state of sleeping or waking had a greater influence. In infants from fifteen days to six months old, the average of the pulse was 140 during waking; 121 during sleep. He has known it rise from 112 to 160 and 180, when the child cried or struggled. On the whole, M. Trousseau concludes, that the pulse of children at the breast varies from 100 to 150. After the first two months, it is a little more frequent in females than in males; and is about 20 higher in the waking than in the sleeping state. Strange to say, it may be wholly absent, without the health seem- ing to be interfered with. A case of the kind is referred to by Prof. S. Jackson,^ as having occurred in the mother of a physician of Phila- delphia. The pulse disappeared during an attack of acute rheuma- tism, and could never again be observed. Yet she was active in body and mind, and possessed unusual health. In no part of the body could a pulse be detected. Dr. Jackson attended her during a part of her last illness — inflammation of the intestines ; no pulse existed. She died whilst he was absent from the city, and no examination of the body was made. Between the number of pulsations and respirations there would not appear to be any fixed relation. In many persons the ratio in health is 4 to l,"* but in disease it varies greatl3\* Dr. Elliotson^ alludes to a case of nervous disease in a female at the time in no danger whose respiration was 106, and pulse 104. ' Memoires de la Societe Medicale d'Observation de Paris, torn, ii., Paris, 1844. * Jouro. des Connaiss. Med.-Chir., .Juillet & Aout, 1841 ; cited in Amer. Journ. of the Med. Sciences, Oct., 1841, p. 458, and Jan., 1842, p. 199. '^ The Principles of Medicine, founded on the Structure and Functions of the Animal Organism, p. 492, Pliilad., 1832. A case of complete disappearance of the beating of the heart is in Gazette Medicale, 21 Nov., 1836 ; and analogous cases are given in Parry on the Pulse, Bath, 1816, and in Medico-Chirurg. Review, xix. 285, and April, 1836. ■• Quetelet, Sur L'Homme, p. 87 ; also, Guy, Pennock, &c., in Art. Pulse, op. cit., and Dr. John Reid, art. Respiration, ibid., pt. xxxii. p. 338, Lond., 1848. - P. A. Jochmanu, Beobachtungen iiber die KorperwUrme in Chronischen Fieber- haften Krankheiten, s. 82, Berlin, 1853. s Human Physiology, p. 215, Lond., 1835. See, also, Dr. Ch. Hooker, of New Haven, Conn., in Boston Medical and Surgical Journal, for May 16, 23, &c., 1838. . USES. 449 Dr. Knox^ has made some observations on the pulsations of the heart, and on its diurnal revolution and excitability, from which he infers: 1, The velocity of the heart's action is in a direct ratio with the age of the individual,— being quickest in young persons, slowest in the aged. There may be exceptions to this, but they do not affect the general law. 2. There are no data to determine the question of an average pulse for all ages. 3. There is a morning acceleration and an evening retardation in the number of the pulsations independently of any stimulation by food, &c. 4. The excitability of the heart un- dergoes a daily revolution ; — that is, food and exercise affect its action most in the morning and during the forenoon ; less in the afternoon, and least of all in the evening. Hence it might be inferred, that the pernicious use of spirituous liquors must be greatly aggravated in those who drink before dinner. 5. Sleep does not farther affect the heart's action than through the cessation of all voluntary motion, and a recumbent position. (5. In weak persons, muscular action excites that of the heart more powerfully than in the strong and healthy ; but this does not apply to other stimulants, — Avine and spirituous liquors, for example. 7. The effect of the position of the body in increasing or diminishing the number of pulsations is solely attributable to the muscular exertion required to maintain the body in the sitting or erect posture ; the debility may be measured by altering the position of the person from a recumbent to a sitting or erect one. 8. The most powerful stimulant to the heart's action is muscular exertion. The febrile pulse never equals this.^ h. Uses of the Circulation. The chief uses of the circulation are, — to transmit to the lungs the products of absorption, in order that they may be converted into arte- rial blood ; and to convey to the organs such arterial blood, which is not only necessary for their vitality, but is the fluid by which the different processes of nutrition, calorification, and secretion are effected. The vessels are the mere carriers of pabulum to the tissues ; the cells of which obtain from the blood the materials that are necessary for building up each tissue. It is therefore outside of the vessel, that every formative act is accomplished. Mr. Paget^ properly animad- verts on the error and confusion, which result from speaking of the "action of vessels," as if the vessels really made and unmade the parts. " We have no knowledge" — he adds — "of the vessels as anything but carriers of the materials of nutrition to and fro. These materials ma}'-, indeed, undergo some change as they pass through the vessels' walls; but that change is not an assuming of definite shape; the ves- sels only convey and emit the 'raw material;' it is made up in the parts, and in each after its proper fashion. The real process of forma- tion of tissues is altogether extra-vascular, even, sometimes, very far extra- vascular ; and its tissue depends in all cases chiefly, and in some ' Edinburgh Medical and Surgical Journal, April, 1837. ^ The article on the Pulse, by Dr. Guy, in Cyclop, of Anat. and Physiology, is an excellent rcsuw' of the whole subject. See also Berard, Cours de Physiologic, 3ie livrai- son, p. 101, Paris, 1855. * Lectures on Surgical Pathology, Amer. edit., p. 40, Pliilad., 1854. VOL. I.— 29 450 CIRCULATION. entirely, on the affinities (if we may so call tliem) between tlie part to be nourished and the nutritive fluid." It may be remarked in conclusion, that the agency of the blood, as the cause of health or disease, has had greater importance assigned to it than it merits ; and that although the blood may be the medium, by which the source of disease is conveyed to other organs, we cannot look to it as the seat of those taints that are commonly referred to it. " Upon the whole," says Dr. Good,^ " we cannot but regard the blood as, in many respects, the most important fluid of the animal machine : from it all the solids are derived and nourished, and all the other fluids are secreted ; and it is hence the basis or common pabulum of every part. And as it is the source of general health, so is it also of general disease. In inflammation, it takes a considerable share, and evinces a peculiar appearance. The miasms of fevers and exanthems are harmless to every part of the system, and only become mischiev- ous when they reach the blood ; and emetic tartar, when introduced into the jugular vein, will vomit in one or two minutes, although it might require perhaps half an hour if thrown into the stomach, and in fact it does not vomit till it has reached the circulation. And the same is true of opium, jalap, and most of the poisons, animal, mineral, and vegetable. If imperfectly elaborated, or with a disproportion of some of its constituent principles to the rest, the whole system par- takes of the evil, and a dysthesis or morbid habit is the certain conse- quence; whence tabes, atrophy, scurvy, and various species of gan- grene. And if it becomes once impregnated with a peculiar taint, it is wonderful to remark the tenacity with which it retains it, though often in a state of dormancy and inactivity for years, or even entire generations. For as every germ and fibre of every other part is formed and regenerated from the blood, there is no other part of the systera that we can so well look to as the seat of such taints, or the predisposing cause of the disorders I am now alluding to ; often cor- poreal, as gout, struma, phthisis: sometimes mental, as madness; and occasionally both, as cretinism." This picture is largely overdrawn. Setting aside the erroneous pathological notions that assign to the blood what properly belongs to cell life in the system of nutrition, how can we suppose a taint to con- tinue for years, or even entire generations, in a fluid which is perpetu- ally undergoing mutation ; and, at any distant interval, cannot be presumed to have one of its quondam particles remaining? Were all hereditary diseases derived from the mother, we could better compre- hend this doctrine of taints ; inasmuch as, during the whole of foetal existence, she transmits the pabulum for the support of her offspring. The child is, however, equally liable to receive the taint from the father, who supplies no pabulum, but merely a secretion from the blood at a fecundating copulation, and from that moment can exert no influence on the character of the progeny. The impulse to this or that organization or conformation must be given from the moment of union of the particles, furnished by each parent at a fecundating inter- course; and it is probable, that no material influence is exerted sub- ' Op. cit. TBANSFUSION AND INFUSION. 451 sequently even by the motlier, except througli the pabuhim she fur- nishes. The embryo accomplishes its own construction, as independ- ently of the parents as the chick in ovo. i. Transfusion and Infusion. The operation of Transfusion, — as well as of Infusion of medicinal agents, — was referred to in an early part of this chapter, to prove the course of the circulation to be from the arteries into the veins. Both these operations were suggested by the discovery of Harvey. The former, more especially, was looked upon as a means of curing all dis- eases, and of renovating the aged ad libitum. The cause of every disease and decay was presumed to reside in the blood, and, conse- quently, all that was necessary was to remove the faulty fluid, and substitute pure blood obtained from a healthy animal in its place. As a therapeutical agency, the history of this operation does not' belong to physiology. The detail of the fluctuation of opinions re- garding it, and its total disuse, are given at some length in the Histo- ries of Medicine, to which we must refer the reader.^ It appears to have been first performed on man in France by Denis and Emmerets in 1666; and in the following year it was practised in England by Drs, Lower and King.^ Before this, however, many experiments had been made on animals. In his " Diary" under the date of the 14th of November, 1666, Pepys^ has the following entry: — "Dr. Croone told me, that at the meeting of Gresham College to-night, which, it seems, they now have every Wednesday again, there was a pretty experi- ment of the blood of one dog let out, till he died, into the body of another on one side, while all his own run out on the other side. The first died upon the place, and the other very well, and likely to do well. This did give occasion to many pretty wishes, as of the blood of a Quaker to be let into an Archbishop, and such like ; but, as Dr. Croone says, may, if it takes, be of mighty use to man's health, for the amending of bad blood by borrowing from a better body." There are some interesting physiological facts, connected with trans- fusion, that cannot be passed over. MM. Prevost and Dumas found that the vivifying power of the blood does not reside so much in the serum as in the red particles. An animal bled to S3mcope was not revived by the injection of water or of pure serum at a proper tem- perature ; but if blood of one of the same species was used, the animal seemed to acquire fresh life at every stroke of the piston, and was at length restored. The operation was revived by Dr. Blundell,'* and by MM. Prevost and Dumas;* the first of whom employed it with safety, and he thinks with happy eftects, in exhausting uterine hemorrhage. All these gen- ' K. Sprengel, Histoire de Medecine, par Jourdan, iv. 120, Paris, 1815. * J. P. Kay, art. Transfusion, Cyclopsedia of Practical Medicine, Amer. edit., bj tlie author, iv., 468, Philad., 1845 ; and The Physiology, &c. of Asphyxia, p. 254, Lond., 1834. * Diary and Correspondence of Samuel Pepys, F. R. S., by Lord Braybrooke, 3d edit., iii. 336, London, 1848. * Medico-Chirurgical Transactions, ix. 56 ; and x. 296 ; and Researches, physiological and pathological, p. 63, London, 1825. ^ Bibliotheque Uuiverselle, xvii. 215. 452 CIRCULATIOX. tlemen remark, that it can only be adopted with perfect safety in ani- mals of like kinds, or in those the corpuscles of whose blood are of similar configuration. MM. Prevost and Dumas, Dieflfenbach,^ and Bischoff,^ agree as to the deadly influence of the blood of the mam- malia Avhen injected into the veins of birds. This influence, according to Miiller,^ is in some way connected with the fibrin of the blood, as when blood deprived of fibrin was injected into the vessels, the animal appeared to suffer no inconvenience. The introduction of the practice of infusing medicinal agents into the blood was coeval with that of transfusion. It appears to have been first subjected to a philosophical examination by Sir Christopher Wren, who practised it on a malefactor in IQb'o.* It is a singular fact, that in cases of infusion, medicinal substances are found to exert their specific actions upon certain parts of the body, precisely in the same manner as if they had been received into the sto- mach. Tartar emetic, for example, vomits, and castor oil purges not only as certainly, but with much greater speed; for, whilst the former, as before remarked, requires to be in the stomach for fifteen or twenty minutes, before vomiting is excited, it produces its effect in one or two minutes, when thrown into the veins. Dr. E. Hale, of Boston, has published an interesting pamphlet on this subject.^ In it he traces the history of the operation, detailing several interesting experiments upon animals; and one upon himself, which consisted in the introduction of a quantity of castor oil into the veins. In this experiment, he did not feel much inconvenience immediately after the iujection ; but very speedily experienced an oily taste, which continued for a length of time, and the medicine occasioned much gastric and intestinal dis- turbance, but did not act as a cathartic. Considerable difficulty was experienced in the introduction of the oil, to wliich circumstance M. Magendie" ascribes Dr. Hale's safety; for it is found, by experiments on animals, that viscid fluids, such as oil, are unable to pass through the pulmonary capillaries, in consequence of which the circulation is arrested, and death follows. Such, also, appears to have been the result of the experiments of Dr. Hale with })owdered substances. The injection of medicines into the veins has been largely practised at the Veterinary School of Copenhagen, and with complete success — the action of the medicine being incomparably more speedy, and the dose required much less. It is rarely employed by the physician, ex- cept in experiments on animals; but it is obvious, that it might be had recourse to with happy effects, where narcotic and other poisons have been taken, and where the mechanical means for their removal are not at hand. ' Die Transfusion des Blutes, Berlin, 1828. ' Miiller's Archiy., 1835; cited in Baly's translation of J. Miiller's Handbuch, u. s. w. 3 Handbuch der Physiol ogie, Baly's translation, i. 141, London, 1838. See, on the different efl'ects of transfusion of arterial and venous blood on animals, Bischoif, in Miil- ler's Archiv., Heft iv. 1838, cited in Brit, and For. Med. Rev., April, 1839, p. 548. * Chelius, System of Surgery, translated by South, Ampr.edit.,iii. 62tj, Pliilad., 1847. * Boylston Medical Prize Dissertations for the years 1819 and 1821, p. 100, Boston, 1821. 6 Precis, &c., ii. 430. IN" ANIMALS. 453 4. CIRCULATORY APPARATUS IN ANIMALS. In concluding tliis subject, a brief allusion to the circulatory appa- ratus of other parts of the animal kingdom may be interesting and instructive. In the mammalia in general, the inner structure of the heart is the same as in man; but its situation differs materially; and in some of them, as in the stag and pig, two small flat bones, called hones of the hearty exist, where the aorta arises from the left ventricle. In the amphibious mammalia and the cetacea, it has been supposed, that the foramen ovale in the septum between the auricles is open as in the human foetus, to allow them to pass a considerable time under water without breathing; but the observations of Blumenbach, Cuvier, and others seem to show, that it is almost always closed. Sir Everard Home found it open in the sea otter, in two instances; but these are regarded by naturalists as exceptions to the general rule. In several of the web- footed mammalia and cetacea, as in the common otter, sea otter, and dolphin, particular vessels are always greatly enlarged and tortuous; — a structure which has been chiefly noticed in the vena cava inferior, and is supposed to serve the purpose of a diverticulum, whilst the animal is under water; or to receive a part of the returning blood, and retain it until respiration can be resumed. In hirds^ the structure of the heart universally possesses a singular peculiarity. Instead of the right ventricle having a membranous valve, as in the left, and as in all the mammalia, it is provided with a strong, tense, and nearly triangular muscle, which aids in the propulsion of the blood from the right side of the heart into the lungs. Tliis is pre- sumed to be necessary, in consequence of their lungs not admitting of expansion like those of the mammalia, and of their being connected with numerous air-cells. The heart of reptiles or amphibia in general con- sists either of only one ventricle, or of two, which freely communicate, so as to constitute essentially but one. The number of auricles always corre- sponds with that of the ventricles. That the cavi- ties — auricular and ventricular — are, however, single, although apparently double, is confirmed by the fact, that, in all, there is only a single artery proceeding from the heart, which serves both for the pulmonic and systemic circulations. After this vessel has left the heart, it divides into 1 two branches, by one of which a part only of the blood is conveyed to the lungs, whilst the other proceeds to different parts of the body. Those two portions are united in the heart, and after being mixed together are sent again through the great artery. In these animals, therefore, aeration is less extensive than in the higher; and we can thus understand many of their peculiarities; — how, for example, the circulation may continue, when the animal is so situate as to be incapable, for a time, of respiration; as well as the great Fig. 126. Circulation in the Frog. 454 CIRCULATION. Circulation in Fishes Fig. 128. Fig- 127. resistance to ordinary deranging influences, bj which they are characterized. Fig. 126 represents the circulatory apparatus of the frog; in which E is the ventricle and D the \\Jl'( //^^'^s ^^^l^ auricle. From the former arises the aorta F, ^V ({ W _ .'';'/u/ which soon divides into two trunks. These, after sending branches to the head and neck, turn downwards (O and P), and unite in the single trunk A. This vessel sends arteries to the body and limbs, which ultimately termi- nate in veins, and unite to form the vena cava C. From each of the trunks into which the aorta bifurcates at its origin arise the arteries F. These are distributed to the lungs, and communicate with the pulmonary veins, which return the blood to the auricle, D, where it becomes mixed with the blood of the systemic circulation. In the tadpole state, the circulation is branchial, as in fishes. The heart then sends the whole of its blood to the hranchice or gills, and it is returned by veins following the course of the dotted lines M and N (Fig. 126), which unite to form the descending aorta. As the lunofs undergo their developement, small arterial branches arise from the aorta and are distributed to those organs; and in proportion as these arteries enlarge, the original branchial arteries diminish, until ulti- mately they are obliterated, and the blood flows wholly through the enlarged lateral trunks, O and P, which, by their union, form the descending aorta. In Jishes, the heart is extremely small, in propor- tion to the body; and its structure is simple; con- sisting of a single auricle and ventricle, D and E (Fig. 127). From the ventricle E an arterial trunk arises, which, in most fishes, is expanded into a kind of bulb, F, as it leaves the heart, and proceeds straight forward to the hranchice or giUs^ G and H. From these, the blood passes into a large artery, A, analogous to the aorta, which proceeds along the spine, and conveys the blood to the various parts of the system; and, by the vena cava, C, the blood is returned to the auricle. This is, consequently, a case of single circulation. Insects appear to be devoid of bloodvessels. Cuvier examined all the organs in them, which, in red-blooded animals, are most vascular, without discovering the least appearance of a bloodvessel, although extremel}^ minute ramifications of the trachea were obvious in every part. Insects, how- ever, both in their perfect and larve state, have a membranous tube running along the back, in which alternate dilatations and contractions are perceptible, and which has been considered as their Interior uf the Leech. a, a. Respiratory cells, ft, 6. Two large arteries. c, c. Mucous glands, d, d. Glands connected with the testicles, e, e. Testicles. /. Penis, g. Uterus. KUTRITION. 455 heart ; but it is closed at both ends, and no vessels can be perceived originating from it. To this the innumerable ramifications of the trachea convey the air, and thus, as Cuvier has remarked, "le sang ne pouvant aller chercher I'air, c'est I'air qui va chercher le sang" ("the blood not being able to go in search of the air — the air seeks the blood"). Carus, however, discovered a continuous circulation through arteries and veins in a few of the perfect insects, and especially in some larves. Lastly : in many genera of the class vermes, particularly amongst molluscous animals, there is a manifest heart, which is sometimes of a singular structure. Some of the bivalves — it is affirmed — have as many as four auricles; whilst many animals, — as the leech and Lumhricus vmrivus, — have no heart ; but circulating vessels exist, in which contraction and dilatation are perceptible. The marginal figure (Fig. 128), of the interior of a leech, given by Sir Everard Home, exhibits the mode of circulation and respiration in that animal. There is no heart, but a large vessel exists on each side. The water is received, through openings in the belly, into the cells or respiratory organs, and passes out through the same. CHAPTER Y. NUTRITION. The investigation of the phenomena of the circulation has exhibited the mode in which arterial blood is distributed over the body in minute vessels, not appreciable by the naked eye, and often not even with the microscope, and so numerous, that it is impossible for the finest-pointed instrument to be forced through the skin without penetrating one, and perhaps several. It has been seen, likewise, that in the capillary system of vessels, this arterial blood is changed into venous ; and it was ob- served, that in the same system, parts are deposited or separated from the blood, and certain phenomena occur, into the nature of which we have now to inquire; beginning with those of nutrition, which comprise the incessant changes that are taking place in the body, both of absorp- tion and deposition for the decomposition and renovation of each organ. Nutrition is well defined by M. Adelon^ as the action, by which every part of the body, on the one hand, appropriates or assimilates to itself a portion of the blood distributed to it; and, on the other, yields to the absorbing vessels a portion of the materials that previously composed it. The precise character of the apparatus, by which this important function is accomplished, we have no exact means of knowing. All admit that the old matter must be taken up by absorbents, and the new be deposited by arteries, or by vessels continuous with them. As the precise arrangement of these minute vessels is not perceptible by the eye, even when aided by powerful instruments, their arrangement has given rise to controversy. Whilst some have imagined lateral pores in the capillaries, for the transudation of nutritive deposits; others have presumed, that inconceivably small vessels are given oft" from the capil- ' Physiologie de rHomme, torn. iii. p. 359, 2de edit., Paris, 1829. 456 KUTRITION. lary system, which constitute a distinct order, and whose function is to exhale the nutritive substance, — an idea, which, as has been said else- where, has been revived by M. Bourger3^ Hence, they have been termed exhalanis or nutritive exhaJants ; but the anatomical and physio- logical student must bear in mind, that whenever the term is used by writers, they do not always pledge themselves to the existence of any distinct set of vessels, but merely mean the minute vessel, whatever may be its nature, which is the agent of nutrition, and conveys the pabulum to the different tissues. In investigating the ph3^siology of nutrition, two antagonistic pro- cesses demand attention; 1st. Decomposition^ by which the tissue yields to the absorbing vessels a portion of its constituents ; and 2dly. Com- position^ by which it assimilates a part of the arterial blood that enters it, and supplies the loss it had sustained by the previous act of decom- position. The former of these actions obviously belongs to the function of absorption ; but its consideration was deferred, in consequence of its close application to the function we are about to investigate. It com- prises what is meant by interstitial^ organic, or decomposing absorption, and does not require many comments, after the long investigation of the general phenomena of absorption into which we entered. The conclusion then arrived at, was, — that the chyliferous and lymphatic vessels form chjde and lymph, respectively, refusing the admission of most other substances ; — but that they and the veins admit every liquid which possesses the necessary tenuity ; and that whilst all the absorp- tions, — which require the substance acted upon to be decomposed and transformed, — are eflected by the chyliferous and lymphatic vessels, those that demand no alteration are chiefly accomplished through the coats of the veins by imbibition. It is easy, then, to deduce the agents to which we refer the absorption of decomposition. As it is exerted on solids, and as these cannot pass through the coats of the vessel in their solid condition, it follows that other ao-ents than the veins must accomplish the process; and, again, as we never find in the lymphatic vessels any thing but lymph, and have ever}^ reason to believe, that an action of selection is exerted at their extremities, similar to that of the chyliferous vessels on the heterogeneous substances exposed to them, we naturally look to the lymphatics as the main, if not the sole, organs concerned in the absorption of solids. It appears manifest that the different tissues are endowed with a vital attractive and elective force, which they exert upon the blood; — that each tissue attracts only those materials of which it is itself composed; and thus, that the whole function of nutrition is an affair of elective affinity; yet this cannot be the force that presides over the original formation of the tissues in the embryo. An attraction cannot be ex- erted by parts not yet in existence. To account for this, it has been imagined, that a peculiar force is destined to preside over formation and nutrition, and various names have been assigned to it. B}'' most of the ancients it was termed facuUas formatrix, nutrix, auctrix ; by Van Hel- mout,' Bias alleiativam; and by Bacon, ^ //'iOi'ws assimilationis. It is the ' Opera, pars i. ^ Novum Orgauum, lib. ii. aplior. 48. AGENTS OF NUTRITION. 457 facuJtas vegetativa of Harvey/ the anima vegetativa of Stahl;^ the jmis- sance da moule interieur of Buffou;' the vis essentialis of C. F. Wolff ;■• and the Bildungstrieb or nisiis formativus oi JMnvaQwhsich and most German writers.* This force is meant, when writers speak of genn force, 2^l(istic force, force of nutrition, force of formation, and force of vege- tation. AVhatever difference there may be in the terms selected, all appear to regard it as charged with maintaining, for a certain length of time, living bodies and all their parts, in the possession of their due composition, organization, and vital properties; and of putting them in a condition, during a certain period of their existence, to produce beings of the same kind as themselves. It is obvious, however, that none of these terms elucidate the intricate phenomena of nutrition, and none express more than — that living bodies possess a vital force^ under the action of which, formation and nutrition are accomplished. The important — indispensable — actions that constitute nutrition occur in the tissues supplied by the intermediate or capillary system of vessels; but not in those vessels themselves. Their function — as before remarked — is to convey to the system of nutrition the pabulum from which the tissues are formed; but tlie formation of the tissues takes place on the outside of the vessel; and the organic cells are the imme- diate agents. It is not, however, the whole of the circulating fluid that constitutes such pabulum. The blood corpuscles — excepting in a single case, menstruation — are not found outside the vessels in the exercise of the healthy functions. The liquor sanguinis alone transudes, and is the material on which the nucleated cell exerts its plastic power." Under the idea that all the vessels of the capillary system are possessed of coats, it is not so easy to comprehend how either nutri- tion or secretion can be accomplished. Were we to adopt the opinion, before referred to, that many of the vessels of the capillary system consist of merabraneless or coatless tubes, it would be more readily understood, that by the elective and attractive forces possessed by the tissues and exerted by them on the blood, materials may be obtained from that fluid as it passes through the intermediate system of vessels, which may be inservient to the nutrition of the tissues bathed by it. The mode in which the blood is distributed through the tissues may be likened to the distribution of the water of a river through a marsh, which conveys to the animal and vegetable bodies that flourish in it the materials for their nutrition. To adopt the language of an intelligent and philosophical writer,^ "In every part of the body, in. the brain, the heart, the lung, the muscle, the membrane, the bone, each tissue attracts only those constituents of which it is itself com- posed. Thus, the common current, rich in all the proximate constituents of the tissues, flows out to each. As the current approaches the tissue, ' De Generatione Animaliiim, Lond., 1G51, p. 170. ^ Theoria Medica Vera. Hal., 1708. ' Histoire Naturelle, torn. ii. * De Generatione, Hal., 1759. ^ Comment. Societ. Getting., torn. viii. ; and Institutionos Pliysiologic?e, § 31, Got ting., 1798. ^ Mulder, The Chemistry of Vegetable and x\nimal Physiology, translated by From- berg, p. 597, Edinburgh and London, 1849. See, also, on this subject, Paget, Surgical Pathology, Anier. edit., p. 140, Philad., 1854. ' The Philosophy of Health, by Dr. Southwood Smith, vol. i. p. 405, London, 1835. 458 NUTRITION. the particles appropriate to the tissue feel its attractive force, obey it, quit the stream, mingle with the substance of the tissue, become iden- tified with it, and are changed into its own true and proper nature. Meantime, the particles which are not appropriate to that particular tissue, not being attracted by it, do not quit the current, but, passing on, are borne by other capillaries to other tissues, to which they are appropriate, and by which they are apprehended and assimilated. When it has given to the tissues the constituents with which it abounded, and received from them particles no longer useful, and which would become noxious, the blood flows into the veins, to be re- turned by the pulmonic heart to the lung, where, parting with the use- less and noxious matter it has accumulated, and replenished with new proximate principles, it returns to the systemic heart, by which it is again sent back to the tissues." Particles of blood are seen to quit the current and mingle with the tissues; particles are seen to quit the tissues, and mingle with the cur- rent; but allthat we can see, as Dr. Smith has remarked, with the best aid we can get, does but bring us to the confines of grand operations, of which we are altogether ignorant. It is not necessary, however, for the nutrition of certain parts, that they should receive capillary vessels. There are tissues, commonly termed extra-vascular, in the substance of which neither injection nor the microscope has exhibited the existence of bloodvessels, and which would seem to derive their nourishment by imbibition from blood flowing in the vessels of adjacent tissues. To these belong the crystalline body, epidermis and epithelium, hair, nails, enamel of the teeth, &c., &c. We have said that the main, if not the sole, agents of the absorption of solids are the lymphatics. Almost all admit, that they receive the products of the absorption of solids ; but all do not admit, that the action of taking up solid parts is accomplished immediately by the absorbents. They who think, that a kind of spongy tissue or " paren- chyma" exists at the radicles of the absorbent vessels, believe that this sponge possesses a vital action of absorption, when bodies, possess- ing the requisite constitution and consistence, are put in contact with it ; but they maintain, that the solid parts are broken down by the same agents — the extreme arteries — which secreted them, and that, when reduced to the proper fluid condition, they are imbibed by the paren- chyma, and conveyed into the lymphatics. But if the existence of this sponge were demonstrated, the above explanation would scarcely be admissible, for it could not be conceived to do more than imbibe; it could not break down solids, and reduce them to lymph — the only fluid which, as we have seen, is ever met with in lymphatics. Its existence is, however, altogether supposititious. Besides, the arrangement has not been invoked in favour of thecli3diferous vessels, which are so analogous in their organization and functions to the lymphatics. It has not been contended, that the arteries of the intestinal canal form the chyle from the alimentary matters in the small intestine, and that the office of the chyliferous vessels is restricted to the reception of this chyle, imbibed and brought in contact with their radicles by the ideal sponge or parenchyma. We have before shown, that there is every reason for the belief, that AGENTS OF NUTRITION". 459 a vital action of selection and elaboration exists at the very origin of the chyliferous vessels ; and the same may be inferred of the lymphatics. The great difficulty has been to understand how either exhaling artery or absorbing lymphatic can reduce the solid matter — of bone, for ex- ample — to the constitution and consistence requisite for entering the lymphatics; but we might conceive, that the latter as readily as the former, by virtue of its vital properties — for the operation must be admitted by all to be vital — and by means of its contained fluid, might soften the solid so as to admit of its being received into the vessel. We should still, however, have to explain the mysterious operation by which those absorbents are enabled to reduce to their elements, bone, muscle, tendon, &c., and to recompose them into the form of lymph. Dr. Bostock' fancifully suggests, that the first step in this series of operations is the death of the part ; by which expression he means, that it is no longer under the influence of arterial action. "It therefore ceases to receive the supply of matter which is essential to the support of all vital parts, and the process of decomposition necessarily com- mences." The whole of his remarks on this subject are eminently gratuitous, and appear to be suggested by an extreme unwillingness to ascribe the process to any thing but physical caiises. If there be, how- ever, any one phenomenon of the animal economy, which is more mani- festly referable to vital action than another, it is the function of nutri- tion, both as regards the absorption of parts already deposited, and the exhalation of new. We know that the blood contains most of the principles that are necessary for the nutrition of organs, and that it must contain the elements of all. Fibrin, albumen, fat, salts, &c., exist in it, and these are deposited, as the blood traverses the tissues; but why one of these should be selected by one set of vessels, and an- other by another set, and in what manner the elements of those, not already formed in the blood, are brought together, is nnknown to us. Blood has been 'designated as "liquid flesh," — chair coulante^ — but something more than simple transudation through vessels is necessary to form it into flesh, and to give it the compound organization of fibrin, gelatin, osmazome, &c. — in the form of muscular fibre and areolar membrane — as we observe in the muscle. Nothing, perhaps, has more clearly exhibited the want of knowledge on this subject than the fol- lowing vague attempt at solving the mystery by one of the most dis- tinguished physiologists of the age. " Some immediate principles, that enter into the composition of the organs or of the fluids, are not found in the blood, — such as gelatin, uric acid, &c. They are consequently formed at the expense of other principles, in the parenchyma of the organs, and by a chemical action, the nature of which is unknown to us, but which is not the less real, and must necessarily have the effect of developing heat and electricity." The views of recent histologists have approximated us more to a true knowledge of this mysterious action. They have not been con- tent with endeavouring to reduce the different organized textures to primary fibres and filaments, but, by the aid of the microscope, have attempted to discover the particular arrangement and mode of forma- ' System of Physiology, edit. cit.,p. 625. 460 NUTRITION. tion of the constituent corpuscles. The discovery of that valuable instrument gave the impulse ; and very soon the scientific world was presented with the results obtained by numerous observers. These observations have been, fi-om time to time, continued until the present da}'. It is, however, to be regretted, that, until recently, our informa- tion, derived from this source, was not as accurate as was desirable. From different quarters, the most discordant statements were presented, exhibiting clearly, either that the narrators employed instruments of very different powers, or that they were blinded, or had the vision depraved, by preconceived theories or hj^potheses. One of the very first effects of the discovery of the microscope was the detection by Leeuenhoek,^ of a globular structure of the primi- tive tissues of the body, an announcement which gave rise to much controversy, and engaged the attention particularly of Prochaska,* Foutana,^ Sir Everard Home, Mr. Bauer, the brothers Wenzel,"* M. Milne Edwards, MM. Prevost and Dumas,* Dutrochet, Hodgkin,** Raspail, and others.'' The observations and experiments of Dr. Ed- wards, more especially, occasioned at the time much interesting specu- lation and inquiry. They may perhaps be taken Fig. 129. as the foundation on which the believers in the globular structure of later years rested their opi- nions. His views were first published in 1828, in a communication, entitled '■'' Memoire sur la Stnicture elementaire des ^5?-wic2):>awa; Tissues Or- ganiques des Animanx f^ and in a second article in the Annales des Sciences Naturelles^ for Decem- ber, 1826, entitled ^^ Recherches ■microscopiques sur la Structure intime des Tissues Or ganiques des Ani- mauxy He examined all the principal textures of the body, the areolar tissue, membranes, tea- , ^. dons, muscular fibre, nervous tissue, skin, coats Arcoliir Xissu6 . of the bloodvessels, &c. When the areolar tissue was viewed through a powerful lens, it seemed to consist of cylinders; but, by using still higher magnifying powers, these cylinders were found to be formed of rows of globules of the same size, that is, about the ^ JQj5th or gfj'o^jth of an inch in diameter (Fig. 129); separated from each other, and lying in various directions; crossing and interlacing; some of the rows straight; others bent, and some twisted, forming irregular layers united by a kind of network. The membranes, which consist of areolar tissue, were found to present exactly the same kind of arrangement. The muscular fibre, when examined in like manner, was found to be formed of globules, also ggoo^^ P^^^ of ^^ ^^^*^^^ ^'^ diameter. Here, however, the rows of globules are always parallel. The fibres uev^er intersect each other like those of areolar tissue, and ' Opera Omnia, Lugdun. Batav., 1722. ^ j>q Structure Nervorum, Viiul.,lT79. " Sur les Poisons, ii. 18. '' De Structura Cerebri, Tubing., 1S12. * Bibliotheque Universelle des Sciences et Arts, t. xvii. ^ In Drs. Hodgkin's and Fisher's translation of W. Edwards, Sur les Agens Phy- siques, Loud., 1832. ' Klencke, Ueber das Physiolodsche uud Pathologische Leben der Mikroskopischen Zellen, .Jena, 1844. AGENTS OF NUTRITION". 461 Fiff. 130. Muscular Tissue. Fig. 131. this is the only discenuble difference, — the form and size of the glo- bules being alike. The size of the globules, and the linear arrange- ment they assume, seemed to be the same in all animals that possess a muscular structure. (Fig. 130.) The nervous structure had, by almost all observers, been esteemed globular. The examination of M. Edwards yielded similar results.-' It seemed to be composed of lines of globules of the same size as those that form the areolar membrane and muscles; but holding an intermediate place as to the regularity of their arrangement, and having a fatty matter interposed between the rows. In regard to the size of the globules, however, M. Ed- wards difi'ered materially from an accurate and expe- rienced microscopic observer, Mr. Bauer,^ who asserted that the cerebral globules are of various sizes. (Fig. 181.) From the results of his own diversified ob- servations M. Edwards concluded, that "spherical corpuscles, of the diameter of g^gth of a millimetre, constitute by their aggregation all the organic tex- tures, whatever may be the properties, in other re- spects, of those parts, and the functions for which they are destined." The harmony and simplicity, which would thus seem to reign through the structures of the animal body, attracted great attention to the labours of M. Edwards. The vegetable king- dom was subjected to equal scrutiny; and — what seemed still more astounding — it was affirmed, that the microscope proved it also to be consti- tuted of globules precisely like those of the ani- mal, and of the same magnitude, gg'^^th of an inch in diameter; hence, it was assumed, that all organized bodies possess the same elementary structure, and of necessity, that the animal and the vegetable are readily convertible into each other under favourable circumstances, and differ only in the greater or less complexity of their organization. Independently of all other objec- tions, however, the animal differs, as we have seen, from the vegetable, in composition; and this difference must exist not only in the whole, but in its parts; so that, even were it de- monstrated that the globules of the beings of the two kingdoms are alike in size, it would by no means follow that they should be identical in intimate composition. The discordance, which we have deplored, is strikingly applicable to the case before us. The appearance of the memoir of Dr. Edwards excited the attention of M. Dutrochet, and in the following year his '■'' Recherclies'^ on the subject were published, in which he asserts, that the globules, which compose the different structures of invertebrated ' See, also, Calori, in Bulletino delle Scienze Medich. di Bologna, Sett., 1836, p. 152. ^ Philosoph. Transact, for 1818 ; and Sir E. Home, Lectures on Comparative Ana- tomy, vol. iii. lect. 3, Lond., 1823. Xervous Tissue. 462 NUTRITION. animals, are considerably larger than those of the vertebrated ; that the former appear to consist of cells, containing other globules still smaller ; and hence he infers, that the globules of vertebrated animals are likewise cellular, and contain series of still smaller globules. Dr. Edwards, in his experiments, found, that the globules of the nervous tissue, whether examined in the brain, in the spinal cord, ganglia, or nerves, have the same shape and diameter, and that no difference in them can be distinguished from whatever animal the tissue is taken. M. Dutrochet, on the other hand, considers, with Sir Everard Home, and the brothers Wenzel, that the globules of the brain are cellules of extreme minuteness, containing a medullary or nervous substance, which is capable of becoming concrete by the action of heat and acids. This structure, he remarks, is strikingly evidenced in Fig. 132. certain molluscous animals ; and he instances the small pulpy nucleus, which forms the cerebral hemisphere of Umax rufus^ and helix pomatia, and is composed of globular, agglomerated cellules, on the parietes of which a considerable number of globular or ovoid cor- puscles are perceptible. (Fig. 132.) Cellules of Brain. M. Dutrochet, again, did not find the structure of the nerves to correspond with that of the brain. He asserted, that the elementary fibres, which enter into their composi- tion, do not consist simply of rows of globules, according to the opi- nion of M. Edwards and others, but that they are cylinders of a diaphanous substance, the surface of which is studded with globular corpuscles ; and that, as these cover the whole surface of the cylinder, we are led to believe that they are in the interior also. After detail- ing this difference of structure between the brain and the nerves, the former consisting chiefly of nervous corpuscles, the latter chiefly of cylinders or fibres, M. Dutrochet announced the hypothesis, which ex- hibits too many indications of having been formed prior to his micro- scopic investigations, — that these cerebral corpuscles are destined for the production of the nerve power, and that the nervous fibres are tubes, filled with a peculiar fluid, by the agency of which nervimoiion is effected. For further developements of the views of M. Dutrochet, the reader is referred to the work itself, which exhibits all the author's ingenuity and enthusiasm, but can scarcely be considered historical. The beautiful superstructure of M. Edwards, and the ingenuity of M. Dutrochet, were, however, most fatally assailed by subsequent ex- periments of Dr. Hodgkin with a microscope of unusual power. The globular structure of the animal tissues, so often asserted, and appa- rently so clearly and satisfactorily established by M. Edwards, was, we are told by Dr. Hodgkin,^ a mere deception ; and the most minute parts of the areolar membrane, muscles, and nerves, were again re- ferred to the striated or fibrous arrangement. A part of the discre- pancy between MM. Edwards and Dutrochet may be explained by the fact of the former using an instrument of greater magnifying power than the latter, who employed the simple microscope only ; and it was observed, that when the former used an ordinary lens, the arrangement ' Op. citat., p. 46G. AGENCY OF CELLS IN NUTRITION. 463 of a tissue appeared cylindrical, wliich, witli tlie compound microscope, was distinctly globular. The discordance between Messrs. Edwards and Hodgkin was reconcilable with more difficulty. On the whole subject, indeed, minds were kept in a state of doubt, and the rational physiologist waited for ulterior developements. MM. Prevost and Dumas, and M. Edwards, farther affirmed, that all the proximate prin- ciples — albumen, fibrin, gelatin, &c., — assume a globular form, when- ever they change from the fluid to the solid state, whatever may be the cause producing such conversion. M. EaspaiP — a wayward genius, who has quitted the sober pursuit of science, for the uncertainty and turmoil of politics, from which he has suffered greatly — ranged him- self among those who considered, that the ultimate structure of all organic textures is vesicular, and that the organic molecule, in its simplest form, is an imperforate vesicle, endowed with the faculty of inspiring gaseous and liquid substances, and of expiring again such of their elements as it cannot assimilate ; — properties, which he conceived it to possess under the influence of vitality. His views contain, per- haps, the germ of those that follow, and that have since occupied so much the minds of observers. The microscopical researches of Schwann and Schleiden^ led them to affirm, that the new-forming tissues of vegeta- bles originate from a liquid gum or vegetable mucus, and those of animals probably from the liquor sanguinis, after transudation from the ca- pillary vessels. This matrix^ in a state fully pre- pared for the formation of the tissue, is termed by them intercellular substance and cytohlastema. In the first instance, it exhibits minute granular points, which grow and become more regular and defined from the agglomeration of minuter granules around Primary Organic Cell, the larger, constituting nuclei or cytohlasts or cell- showing the germinal germs, and having, when fully formed, and in fact Nucleolus." ^"^' ^° formed before them, one or more well-defined bodies within, called nucleoli. From the c^^toblasts, cells — primordial or germinal cells — are formed. A transparent vesicle grows over each, and becomes filled with fluid; this gradually extends and becomes so Fig. 134. large that the cytoblast appears like a small body within its walls, and • © ^ hence the cell is said to be nucleated. The form of the cells is at first irre- p-nlnr tliPTi mnrp rpo-nlqr qnrl thpv PI"" representing the formation of a Nu- guiar, tneu more regular, ana iney ^j^^^^ ^^^ ^^ ^ ^^^^ ^^ ^^^ Nucleus, ac- are alternately flattened by pressure cording to Schieideu's view, against each other, so as to assume different forms in different tissues. Such is the description of Schwann and Schleiden of the vegetable cells from which all the tissues of ' Op. citat., § 126. * Mikroskopische Untersuchungen iiber die TJebereinstimmuiig in der Struktur und dem Wachstum der Thiere und Ptlanzen, von Dr. Th. Schwann und Dr. Schleiden, in Miiller's Archiv., p. 137, 1838 ; and Microscopical Researches into the Accordance and Growth of Animals and Plants, translated by Henry Smith, Sydenham Society's edition, London, 1847. 464 NUTRITION. plants take their origin. In like manner, the tissues of animals are formed from a fluid, in which nncleoli, nvclei or cytohlasts — and cells, are successively developed. The globules of lymph, pus, and mucus, are cells with their walls distinct and isolated from each other; horny tissues are cells with distinct walls, but united into coherent tissues ; bone, cartilage, &c., are formed of cells whose walls have coalesced ; areolar tissue, tendon, &c., are cells which have split into fibres ; and muscles, nerves, and capillary vessels are cells whose walls and cavi- ties have coalesced. These cells seem to possess an independent and limited life, which has no immediate connexion with that of the organism; the decompo- sition constantly taking place in the living body being connected with the death of the cells of which the several parts are constructed ; and for the reintroduction of which into the circulating fluid, the lymphatic system appears to be specially destined. By virtue of this vital power, they not only attract but change the substances brought in contact with them, or have a power of self-nutrition; and that this is probably independent of the nervous system is shown by an experiment of Dr. Sharpey, in which the reproduction of a portion of the tail of a sala- mander took place, although it was cut off after the organ had been completely paralyzed by dissecting out at its root a portion of the spinal cord, together with the arches of the vertebrae. To the doctrine of cell formation. Professor Goodsir,^ of Edinburgh, has, of late years, made several important additions. Amongst other observations, he states, that besides all organs and tissues having their origin in and consisting essentially of simple or developed cells possessed of a spe- cial independent vitalit}'-, the com- ponent cells are divided into nu- merous departments, each of which consists of several cells arranged round one central or capital cell, which latter is the source whence all the other cells in its own de- partment derived their origin. To each of these several central nu- cleated cells he gives the name nutritive centre or germinal spot. Plach nutritive centre possesses the power of absorbing materials of nourishment from the surround- ing vessels, and of generating, by means of its nucleus, successive Endogenous Cell-growth in Cells of a Melice- rous Tumour. a. Cells presenting nuclei in various stages of de- i i n i ^„„„^11~. velopement into a Sew generation. 6. Parent-cell brOOds OI yOUUg eUClOgenOUS CClls, filled with a new generation of young cells, -n-hicli have originated from the granules of the nucleus. which from time to time fill the cavity of the parent cell, and, carry- ino- with them its cell-wall, pass ofi' in certain directions, and under ' Anatomical and Pathological Observations, p. 1, Edinb., 1845. AGENCY OF CELLS IN NUTEITION. 465 various forms, according to the texture or organ of which the parent forms a part. There are two kinds of nutritive centres, — those pecu- liar to the textures, and those belonging to organs. The former are in general permanent ; the latter peculiar mostly to the embryonic state, and ultimately disappearing; but there is one form in which the nutri- tive centres are arranged both in healthy and morbid parts, which con- stitutes what Mr. Goodsir calls a germinal membrane. It is only met with on the free surface of organs or parts. It is a fine transparent membrane, consisting of cells arranged at equal and variable distances within it. The centres of these component cells are flattened, so that their walls form the membrane by cohering at their edges, and their nuclei remain in its substance as germinal centres. One surface of the membrane is attached to that of the organ or part, and is, therefore, applied upon a more or less richly vascular tissue ; the other is free, and it is to it only that the developed or secondary cells of its germinal spots are attached. These secondary cells, whilst fjrming, are contained between the two layers of the germinal membrane; but as they become developed, they carry forward the anterior laj^er, and become attached to the free surface, whilst the nuclei are left in the substance of the pos- terior layer in close contact with the bloodvessels, from which they derive the materials for the formation of new cells. The doctrine of the developement of all the organic tissues from cells is now embraced by almost all histological inquirers; yet there are some who doubt it ; and others, who by no means regard it as applicable to all the tissues. Thus M. Mandl' objects to the term cytoblastema as applicable to the matrix or organizing material of the tissues, because it necessarily involves the supposition that it gives origin to cells. According to him, the elements, that are developed in the blastema — as he prefers to call it — do not generally deserve the name of cells, inasmuch as they may either liquefy as in the glands; consolidate as in the amorphous membranes; or become transformed directly into fibres, as in the areolar tissue. Mr. Gulliver,^ too, has inferred from his observations, that the mere extension of the parietes of cells is not essential to the formation of all tissues, since fine fibres or fibrils are found in fibrin that has coagulated even out of the body. He has given several figures to exhibit the analogy of structure between false membranes and fibrin coagulated after death, or after the removal of the blood from the body. iSchwann, on the other hand, lays down the rule, which he considers of universal application, that all organic tissues, however different they may be, have one common principle of developement as their basis, the formation of cells; — that is to say, nature never unites molecules immediately into a fibre, tube, &c. ; but, always, in the first instance, forms a round cell; or changes, when it is requisite, the cells into the various primary tissues, as they present themselves in the adult state; but "how," says Mr. Gulliver,^ " is the origin of the fibrils, which I have depicted in so many varieties of fibrin, to be reconciled with this doctrine ? and what is tlie proof that ' Manuel d'Anatomie Generale, p. 549, Paris, 1843. ^ Appendix to Gerber's Anatomy, Atlas, p. 60, and Figs. 244-6, Lond., 1842. ^ Lond. and Edinburgh Philosoph. Magazine, Oct., 1842. VOL. I. — yu 466 NUTRITION, these fibrils may not be the primordial fibres of animal textures? I could never see any satisfactory evidence, that the fibrils of fibrin are changed cells ; and, indeed, in many cases, the fibrils are formed so quickly after coagulation, that their production, according to the views of the eminent physiologist just quoted [Schwann], would hardly seem possible. Nor have I been able to see, that these fibrils arise from the interior of the blood-disks, like certain fibres delineated in the last interesting researches of Dr. Barry." Mr. T. Wharton Jones,^ also, has considered the notion entertained by Dr. Barry,^that a fibre exists in the interior of the blood corpuscles, and that these fibres, after their escape from them, constitute the fibres which are formed by the con- solidation of the fibrin of the liquor sanguinis, to be erroneous. He regards the appearance as altogether illusive. Dr. Carpenter,^ in re- marking on Mr. Gulliver's figures, all of which, as he properly observes, clearly show, that a small portion of coagulated fibrin contains a far larger number of fibres than we can imagine to be contained in the number of blood-disks that would fill the same space, states, that he has discovered a very interesting example of a membrane composed almost entirely of matted fibres, which so strongly resembles the deline- ations of fibrous coagula given by Mr. Gulliver, that he cannot but believe in the identity of the process by which they are produced. This is the membrane enclosing the white of the egg, and forming the animal basis of the shell. If the shell be treated with dilute acid, a tough membrane remains, exactly resembling that which lines it; and if the hen has not been supplied with lime, there is no difierence between the two membranes even without the action of acid on the outer one. Each of them consists of numerous laminasof most beauti- fully matted fibres intermixed with round bodies exactly resembling exudation cells. It is in the interstices of these fibres, that the calca- reous particles are deposited, which give density to the shell. These membranes, according to Dr. Carpenter, are formed around the albu- men, which is deposited on the surface of tlie ovary during its passage along; the oviduct, from the interior of which the fibrinous exudation must take ])lace. It is clear, then, that this doctrine of the origin of all the tissues from cells cannot be considered established." Nor can ideas be esteemed more fixed in regard to the character of the matrix or blastema. M. MandP afl&rms that we know not whether it is the albumen or fibrin of the blood. Others, and perhaps the majority of the present day, ascribe it to fibrin, between which, as we have elsewhere seen, and albumen, there is, according to Alulder, Liebig, and others, an almost itleutity of chemical composition. Fibrin has been considered — but, as is remarked ' Proceedings of tlie Royal Society, No. 56. ^ phjios. Trans, for 1842. 3 Origin and Functions of Cells, in Brit, and For. Med. Rev. for Jan., 1843, p. 277. See alao The Cell: its Physiology, Pathology, and Philosophy, by Waldo J. Burnett, M. D., in Transactions of the American Medical Association, vi. 64.5, Philad., 1853; and T. H. Huxlev ou the Cell Theory, in Brit, and For. Med.-Cliirurg. Rev. for Oct., 1853, p. 285. * "Cette pierre angulaire de la physiologie microscopique" — says a recent writer — • " est done une veritable pomme de discorde. Cela est vraiment douimage ; car cette doctrine est si non convain^ante du moins fort amusante." .1. L. Braclict, Physiologie Elementaire de rilomme, 2de edit., i. 25, Paris and Lyons, 1855. * Op. cit., p. 548. AGENCY OF CELLS IN NUTRITION. 467 elsewhere, on insufficient grounds — to possess higher properties; and the change of albumen into fibrin has been esteemed the first important step in the process of assimilation. In the chyliferous vessels, the pro- portion of fibrin increases as the chyle and lymph proceed onwards in the vessels; whilst that of the albumen diminishes. Such, however, is not rigorously the fact, for on refeiTing to the table slightly modified from that of Gerber, which has been given elsewhere (p. 227), it will be seen, that in the afferent lacteals between the intestines and mesen- teric glands, the albumen has been found in minimum quantity; in the efferent or central lacteals, from the mesenteric glands to the thoracic duct, in maximum quantity ; and in the thoracic duct in medium quan- tity ; whilst the fibrin goes on progressively increasing as the chyle and lymph proceed onwards. On the other hand, the fat was found to diminish progressively; so that there appears to be more probability that the fibrin is formed from the fat, directly or indirectly, than from the albumen. It would seem not improbable, — as before remarked,' — that some nitrogenized material like pepsin, or diastase in plants, is secreted from the parietes of the chyliferous vessels, which occasions a change in the constituents of the chyle ; and the view is somewhat confirmed by the fact to which attention has been drawn by Mr. G. Ross,^ that the con- stituents of fatty matter, added to those of uric acid, would very nearly give the atomic constituents of albumen ; whence, as Dr. Carpenter^ has remarked, it might be surmised, that when there is a demand for proteinaceous compounds in the system, nitrogenized matter, which would otherwise be thrown out of the system, may be united with non- nitrogenized cpmpounds taken as food, in order to supply its wants. That there is an essential physiological difference, however, between fibrin and albumen, notwithstanding their affirmed similarity in chemi- cal composition, is shown by the fact, that effused fibrin has a tendency to spontaneous coagulation, whilst albumen requires the agency of heat. This difference in properties would necessarily induce the belief, that the two substances differ more perhaps in chemical composition than the results of the analyses of Mulder, Liebig, and others, would seem to indicate ; and such appears to be proved by those of MM. Dumas and Cahours, which have been conducted on a very extensive scale ; and show, that the proportion of carbon is seven per cent, less in fibrin than in albumen; whilst that of nitrogen is from eight to nine per cent, more. A correct idea, these gentlemen think, may be formed of the elementary composition of fibrin by considering it a compound of casein, albumen, and annnonia.'' It lias been previously shown, ^ that there is great reason to doubt, that fibrin is the main material employed in nutrition; and that argu- ments have been brought forward to establish, that it is rather the product of a retrograde change of the albuminous matters. The com- paratively small quantity in which it is present in the liquor sanguinis does not favour the view, that it alone is the pabulum for the higher nutritive acts. A view is entertained by many, that nothing but proteinaceous com- ' Pa-e 22(1. 2 Lancet, 1842-3, vol. i. " Op. cit., p. 492. " Meu. E.viiuiiner, October 14, 1843, p. 232. » Page 49. 468 NUTRITION. pounds can serve for the nutrition of the tissues; and that gelatin is not adapted for this purpose. Liebig suggests, that it may be inservient to the nutrition of the gelatinous tissues; and Dr. Carpenter^ says, there is no doubt, that it is incapable of being applied to the reconstruction of any but those tissues; and that it seems questionable, whether, even in those, it exists in a condition that can rightly be termed organized: yet it appears to the author, that no doubt ought to be entertained on the matter. The inconclusiveness of the experiments made on gelatin as an article of food has been animadverted on elsewhere (p. 113). Although not a proteinaceous compound, it is one that is highly nitro- genized. When used as an aliment, it is not capable of being detected in the chyle or blood, and hence must have undergone a metamorphosis, probably into an albuminous compound; and it is certainly as difficult to comprehend how, under such circumstances, gelatin can be inservient to the nutrition of gelatinous tissues when no gelatin is present in the blood, as to comprehend that it may be converted into albumen. How gelatinous aliment, in other words, is formed into chyle and blood in which gelatin is not discoverable, and from these again gelatinous tissues are re-formed, is as incomprehensible as that any of the proteinaceous tissues should be constituted from the same pabulum ; or that oleagi- nous aliments — as is admitted by some, who deu}^ the same power to the gelatinous — should be convertible into proteinaceous compounds. Such is the state of uncertainty in wliich we are compelled to rest in regard to this important function. None of the views can be esteemed established. They are in a state of transition ; and all, perhaps, that we are justified in deducing hjqjothetically is, that the vital force, which exists in the blastema furnished by tlie parents at a fecundating union, gives occasion to the formation of cells, and that the tissues are farther developed through the agency of cell-life^ so as to constitute most of the textures of which the body is composed. It is the action of nutrition, that occasions the constant fluctuations in the weight and size of the body, from the earliest embryo condition till advanced life. The cause of the growth of organs and of the body generally, as well as of the limit accurately assigned to such growth, according to the animal or vegetable species, is dependent upon vital laws that are unfathomable. Nor are we able to detect the precise mode in which the growth of paits is effected. It cannot be simple extension, for the obvious reason that the body and its various compartments augment in weight as well as in dimension. The rapidity with which certain growths are effected is astonishing. The Bovisia giganieum has been known to increase, in a single night, from a mere point to the size of a large gourd, estimated to contain -18,000,000,000 of cellules; and supposing twelve hours to have been necessary for its growth, the cells in it must have been produced at the rate of 4,000,000,000 an hour, or more than 6(3,000,000 a minute, — the greater part of the elements neces- sary for this astonishing Ibrmution being obtained from the air.' But ' Principles of Human Physiology, 2d edit., p. 47(3, London, 1844. In the last edition of his work {]>. tj4. Philad.. 1855) he doubts, wliether it can even go to the nutrition of the gelatinous tissues ; and expresses the opinion, doubtless — the author thinks — to be equally abandoned hereafter, that its alimentary value "must be limited to its calorific power." ^ Truman, Food and its InHuence on Health and Disease, &c., p. 229, Lond., 1842. NUTRITION. 469 these rapid growths possess little vitality, and their decay is almost as rapid as their production. Analogous growths — but not to the like ex- tent — occur in the human body, aud the same remark applies to them. In the large trees of our forests we find a fresh layer or ring added each year to the stem, until the full period of developement ; and it has been supposed that the growth of the animal body may be effected in a similar manner, both as regards its soft and harder materials, — that is, by layers deposited externally. That the long bones lengthen at their extremities is proved by an experiment of Mr. Hunter.^ Having ex- posed the tibia of a pig, he bored a hole into each extremity of the shaft, aud inserted a shot. The distance between the shots was then accurately taken. Some months afterwards, the same bone was exa- mined, and the shots were found at precisely their original distance from each other; but the extremities of the bone had extended much beyond their first distance from them. The flat bones also increase by a deposition at their margins ; and the long bones by a similar depo- sition at their periphery, — additional circumstances strongly exhibiting the analogy between the successive developement of animals and vege- tables. Exercise or rest; freedom from, or the existence of, pressure, produces augmentation of the size of organs, or the contrary; and there are certain medicines, as iodine, which are said to occasion emaciation of particular organs only — as of the female mammas. The efiect of disease is likewise, in this respect, familiar and striking.^ The ancients had noticed the changes effected upon the body by the function we are considering, and attempted to estimate the period at which a thorough conversion might be accomplished, so that not one of its quondam constituents should be present. By sortie, this was held to be seven years; by others, three. It is hardly necessar}^ to say, that in such a calculation we have nothing but conjecture to guide us. The nutrition of the body and its parts varies, indeed, according to numerous circumstances. It is not the same during the period of growth as sub- sequently, when absorption and deposition are balanced, — so far, at least, as concerns the augmentation of the body in one direction. Par- ticular organs have, likewise, their period of developement, at which time the nutrition of such parts must necessarily be more active, — the organs of generation, for example, at the period of pubert}^; the enlargement of the mammas in the female; the appearance of the beard and the amplification of the larynx in the male, &m. All these changes occur after a determinate plan. The activity of nutrition appears to be increased by exercise, at least in muscular organs ; hence the well-marked muscles of the arm in the prize-fighter, of the legs in the dancer, &c. The muscles of the male are, in general, much more clearly defined; but the difference between those of the hard-working female and the inactive male may not be very apparent. The most active parts in their nutrition are the glands, muscles, and skin, whicli alter their character — as to size, colour, and consistence — ' Observations on Ce>rtain Parts of the Animal Economy, with notes, by Prof. Owen, Amer. edit., ]). 321, Pliihid., 1840, ^ The autlior's l^eneral Therajientics and Mat. Med,, 5th edit,, Philad,, 1853; aud his Practice of Medicine, 3d edit,, Philad,, 1848. 470 NUTRITION. Tattooed Head of a New Zealand Chief. with great rapidity ; whilst the tendons, fibrous membranes, bones, &;c., are much less so, and are altered more slowly by the efi'ect of dis- ease. A practice, which prevails Fig. 136. amongst certain professions and people, would seem, at first sight, to show that the nutrition of the skin cannot be energetic. Sailors are in the habit of forcing gun- powder through the cuticle with a pointed instrument, and of figuring the initials of their names upon the arm in this man- ner : the particles of the gunpow- der are thus driven into the cutis vera, and remain for life. The operation of tattooing^ or of punc- turing and staining the skin, pre- vails in many parts of the globe, and especially in Polynesia, where it is looked upon as greatly orna- mental. The art is said to be carried to its greatest perfection in the Washington or New Mar- quesas Islands ;^ where the wealthy are often covered with various de- signs from head to foot ; subjecting themselves to a most painful ope- ration for this strange kind of personal decoration. The operation consists in puncturing the skin with some rude instrument, according to figures previously traced upon it, and rubbing into the punctures a thick dye, frequently composed of the ashes of the plant that fur- nishes the colouring matter. The marks, thus made, are indelible. M. Magendie^ asks: — "How can we reconcile this phenomenon with the renovation, which, according to authors," (and he might have added, according to himself,) "happens to the skin?" It does not seem to us to be in any manner connected with the nutrition of the skin. The colouring matter is an extraneous substance, which takes no part in the changes constantly going on in the tissue in which it is embedded; and the circumstance seems to afford a negative argument in flivour of venous absorption. Had the substance possessed the necessary tenuity, it would have entered the veins like other colouring matters ; but the particles are too gross for this, and hence remain free from all absorbing influence. Like the other organic functions, nutrition does not require the presence of a nervous system. The beautiful products of the vege- table kingdom sufficiently demonstrate that it can be accom])lished witliout one; and in the jtrimordial cell, from which the new being in man and animals is formed, Ave may in vain look for anj^thing resem- bling a nervous system. Generally by those who believe in the necessity of a nervous system for the execution of this as well of eveTj other or- ' Lawrenre, Lectures on Physiology, &c., p. 411, LouJ., 1S19. * Precis, &c., edit. cit.. ii. 483. SECRETION. 471 ganic act, the action of the sympathetic is invoked ; others have assigned great influence to the spinal marrow, M. Brown-Sequard/ however, found that birds are able to live for months after the destruction of the spinal cord from the fifth costal vertebra to its termination; and if the operation has been performed on a young bird, it will continue to grow well. He succeeded in keeping alive a young cat from the 8th of April until the 4th of July, after that part of the cord, which ex- tends from the 11th or 12th costal vertebra to the sacrum had been destroyed. Although paraplegic, the palsied parts had grown in length proportionately as much as the sound parts; and they had ac- quired more than double the length which they had at the time of the operation. The functions of organic life appeared to be carried on without any apparent disturbance, and the nutritive reparation was so powerful, that the portions of the vertebral column which had been cut off' were reproduced. In birds on which the operation had been practised he found that the secretion of quills and nails continued to take place. Yet although nutrition can be accomplished without a nervous sys- tem ; its intensity can be materially modified in man and animals by nervous influence; and in this way we must account for the effects occasionally induced on tumours by the efforts of the animal raag- netizer, for example. CHAPTER VI. SECRETION. We have next to describe an important and multiple function, wliich also takes place in the intermediate system — in the very tissue of our organs — and separates from the blood the various humours. This is the function of secretion, — a terra literally signifying separation — and which has been applied both to operation and product. Thus, the liver is said to separate the bile from the blood by an action of secre- tion, and the bile is said to be a secretion. The organs that execute the various secretory operations differ greatly from each other. They have, however, been grouped by ana- tomists into three classes, each of which will require a general notice, 1, ANATOMY OF THE SECKETOBY APPARATUS, The secretory organs have been divided into the exhalant, follicular, and glandular. The remarks made respecting the exlialmd vessels under the head of Nutrition render it unnecessary to allude, in this place, to any of the apocr3q3hal descriptions of them, especially as their very existence is supposititious. A simp]e/o///c/e or crtjpt has the form of an ampulla or vesicle, and is situate in tlie substance of the skin and mucous membranes; secret- ing a fluid for the purjDose of lubricating them. In the capillary ves- ' Med. Examiner, May, 1S52, p. 321, and August, 1852, p. 495, 472 SECRETION. sel, tlie secreted fluid passes immediately from the bloodvessel, without being received iuto any excretory duct; and, in the simplest follicle, there is essentially no duct specially destined for the excretion of the humour. It is membranous and vascular, having an internal cavity into Avhich the secretion is poured ; and the product is excreted upon the surface beneath which it is situate, either by a central aperture, or by a very short duct — if duct it can be called — generally termed a lacuna. Many of the so called follicles are, however, more complicated, and consist, like the Meibomian, of various cul-de-sacs^ with separate ducts which open into one; so that the distinction between a compound follicle and a gland is not easily made ; and physiologically no difference can be considered to exist. The gland is of a more complex structure than the simple follicle. It consists of an artery which conveys blood to it; of an intermediate body, — the gland^ properly so called, — and of an excretory duct to carry off the secreted fluid, and to pour it on the surface of the skin or mucous membrane. The bloodvessel, that conveys to the gland the material from which the secretion has to be effected, enters the organ, — at times, by various branches ; at others, by a single trunk ; and ramifies in the tissue of 4he gland; communicating at its extremi- ties with the origins of the veins and indirectly with the excretory ducts. These ducts arise b}^ fine radicles at the part w^here the arte- rial ramifications terminate; and they unite to form larger and less numerous canals, until they end in one large duct, as in the pancreas ; or in several, as in the lachrymal gland, — the duct generally leaving the gland at the part where the bloodvessel enters. Of this there is a good exemplification in the kidney. The pavement and the cylinder epithelium, as well as all the inter- mediate forms, are met with in the difterent glands. These are not necessarily a continuation of the epithelium of the cutaneous system; on the contrary, that of the latter is often seen changing its form at its entrance into the gland. Besides the vessels above mentioned, veins exist, which communicate with the bloodvessels that convey blood to the gland, both for the for- mation of the humour and the nutrition of the organ; and which return the residuary blood to the heart. Lymphatic vessels are likewise there; and nerves, — proceeding from the ganglionic sj^stem, — form a network around the secreting arteries, accompany them into the interior of the organ, and terminate, like them, invisibly. Bordeu^ was of opinion, that the glands, judging from the parotid, are largely supplied Avith nerves. They do not, however, all belong to it, some merely crossing it in their course to other parts. Bichat,^ from the small number sent to the liver, was induced to draw opposite conclusions to those of Bordeu. These mav be looked upon as the great components of the glandular structure. They are bound together by areolar tissue, and have gene- rally an outer envelope. The intimate texture of these organs has been a topic of much speculation. It is generally considered, that the final ' Sur les Glaniles, in ffiiivres Completes, par M. Rieherand, Paris, 1S18. ^ Auat. Gi.neral., torn. ii. SECRETORY APPARATUS. 473 ramifications of the arterial vessels, with the radicles of the veins and excretory ducts, and the final ramifications of the lymphatic vessels and nerves, form so many small lobules, composed of minute granular masses. Such, indeed is the appearance the texture presents when examined by the naked eye. Each lobule is conceived to contain a final ramification of the vessel or vessels that convey blood to the organ, a nerve, a vein, a l3miphatic, and an excretory duct, — with areolar tissue binding them together. When the organ has an external membrane, it usually forms a sheath to the various vessels. The lobated structure is not equally apparent in all the glands. It is well seen in the pan- creas, salivary and lachrymal. The precise mode in which the vessel, from the blood of which the secretion is effected, communicates with the excretory duct, does not admit of detection. Professor Mliller' maintains, that the glandular structure consists essentially of a duct with a blind extremity, on whose parietes plexuses of bloodvessels ramify, from which the secretions are immediately made, — a view which was confirmed by the pathological appearances, in a case of disease of the portal system that fell under the author's observation, and is referred to hereafter. The opinion of Mal- pighi^ was similar. He affirmed that such glands as the liver are com- posed of very minute -bodies, called acini from their resemblance to the stones of grapes; — that these acini are hollow internally, Fit?. 137. and covered externally by a network of bloodvessels; and that these minute blood-' vessels pour into the cavities of the acini the secreted fluid, from which it is sub- ,;„„,, composed of secretin, sequently taken up by the I'^t bloodvessels. excretory ducts. Euysch,^ however, held, that the acini of Malpighi are merely con- voluted vessels, continuous with the excretory ducts. In Malpighi's view, the se- cretory organ is a mere collection of follicles; in Euysch's, simply an exha- lant membrane, variously convoluted. "The chief, if not the only difference," says a popular writer,^ "between the secret- ing structure of glands and that of simple surfaces, api:)ears to consist in the different number and the different arrangement of their capillary vessels. The actual secreting organ is in both cases the same, — capil- ' De Glandular. Secernent. Structura Penition,&c., Lips., 1830; or the English edit, hy Mr. SoUv, Lond., 1839. 2 Opera Omnia, &c., p. 300, Lugd. Batav., 1G87. '^ Epist. Anatom. qua respondet Viro Clarissimo Hermann. Boorhaav., p. 45, Lugd. Batav., 1722. •• ISouthwood Smith, in Animal Physiology, p. 115; Library of Useful Knowledge, Loud., 1829. Plan of a Secreting Membrane. Memhrana propria or basement membrane, h. Epithe- nucleated cells, c. La yer of capil- Fig. 138. Plan to show augmentation of Surfiice by formation of Processef. a, h, c. As in preceding figure. ■ subdivided processes. d. Simple, and e, /, branched 474 SECRETION. lary bloodvessel; and it is uncertain whether either its peculiar ar- rangement, or greater extent in glandular texture, is productive of any other effect than that of Fig- 139. furnishing the largest quan- tity of bloodvessels within the smallest space. Thus convoluted and packed up, secreting organ may be pro- cured to any amount that may be required, without the inconvenience of bulk and weight." It is manifest, that the sim- plest form of the secretory apparatus consists of simple capillary vessel, and animal membrane; and that the follicles and glands are structures of a more com- plex organization, but still essentially identical ; — all perhaps — as will be seen presently — executing their functions by means of cell agency. Or, to use the views and lansjuagje of the day, every secreting organ possesses, as essential parts of its structure, a simple and apparently anhistous or tex- tureless membrane, called pnmay-y or haseTiient mem- bnvie ; cells and hlondvessels; and by some, all the various modes in which these three structural elements are ar- ranged have been classed under one or other of two principal divisions — mem- branes, and (jlands} Some of the glands, as the lacteal and salivary, are granular in their arrangement; others, as the spermatic and urinary, consist of convo- luted tubes; but all may be regarded as a prolongation of the skin ; and the essential difference between the various secretory organs is in the extent occasionally of e version but generally of inversion and con- volution of the secretory membrane. This is well represented in the marginal figures.^ The morphology of the secretory apparatus has ' Kirkes and Paget, Manual of Physiology, Amer. edit., p. 23S, Philad., 1P40. * Quain's Human Anatomy by Quain and Sharpey, Amer. edit, by Leidy, ii. 99, riiilad., 1849. Plans of extension of Secreting Membrane, by inversion or recession in form of cavities. A. Simple glands, viz., g, straight tube, h, sac, i, coiled tube. B. JIultilocular crypts, k, oftubular form, Z, saccular. c. Racemose or vesicular compound glands, m. Entire gland, showing branched duct and lobular structure, n. A lobule, dotaclied with o, branch of duct proceeding from it. D. Com- pound tubular gland. PHYSIOLOGY OF SECRETION. 475 been carefully investigated ; but here — as elsewhere — we remain igno- rant of the vital processes concerned. " We must not," — says Liebig^ — " forget that anatomy alone, from the days of Aristotle to Leenen- hoek's time, has thrown but a partial light upon the laws of the phe- nomena of life. As a knowledge of the apparatus of distillation does not instruct us alone concerning its uses ; so in many processes, as in distillation, he who understands the nature of fire, the laws of the dif- fusion of heat, and of evaporation, the construction of the still, and the products of distillation, — knows infinitely more of the process of dis- tillation than the smith himself who made the apparatus. Each new discovery in anatomy has added acuteness, exactitude, and extent to its descriptions; unwearied investigation has almost penetrated to the inmost cell, from whence a new road of inquiry must be opened." 2. FUYSIOLOGY OF SECRETION. The uncertainty which has rested on the intimate structure of secret- ino- or2:ans, and on the mode in which the different bloodvessels com- municate with the commencement of the excretory duct, has enveloped the function, executed by those parts, in obscurity. We see the pan- creatic artery pass to the pancreas; ramify in its tissues; become capillary, and escape detection; and other vessels becoming larger and larger, and emptying themselves into vessels of greater magnitude, until, ultimately, all the secreted humour is contained in one large duct, which passes onwards, and discharges its fluid into the small intestine. Yet if we follow the pancreatic artery as far back as the eye can carry us, even when aided by glasses of considerable magnifying power, or if we trace back the pancreatic duct, we fiiul, in the former vessel, always arterial blood, and in the latter, always pancreatic fluid. It must, con- sequently, be between the part at which the artery ceases to be visible, and at which the pancreatic duct becomes so, that secretion is effected. Conjecture, in the absence of positive knowledge, has been busy, at all times, in attempting to explain the mysterious agency by which such various humours are separated from the same fluid; and, according as chemical, or mechanical, or exclusively vital doctrines have prevailed in physiology, the function has been referred to one or other of those agencies. The general belief amongst the physiologists of the sixteenth and seventeenth centuries was, that each gland possesses a peculiar kind of fermentation, which assimilates to its own nature the blood passing through it. Tlie notion of fermentation was, indeed, applied to most of the vital phenomena. It is now totally abandoned, owing to its being purely imaginary, and inconsistent with all our ideas of the vital operations. When tliis notion had passed av/ay, and the fashion of accounting for physiological phenomena on mechanical principles took its ])lace, the o|)inion ju'evailed, that the secretions are eflected through the glands as through filters. To admit of this mechanical result, it was maintained, that all the secreted fluids exist ready formed in the blood, and that, wdien they arrive at the different secretory organs, they pass through, and are received by, the excretory ducts. 184o Chemistry and Physics iu relation to Physiology and Pathology, p. 105, Loud., 476 SECRETION". Des Cartes' and Leibnitz^ were warm supporters of this mechanical doc- trine, although their views differed materially with regard to the precise nature of the operation. Des Cartes supposed, that the particles of the various humours are of different shapes, and that the pores of the glands have a corresponding figure; so that each gland permits those particles only to pass through it which have the shape of its pores. Leibnitz, on the other hand, likened the glands to filters, which had their pores saturated with their own peculiar substance, so that they admitted it to pass through them, and excluded all others, — as paper, saturated with oil, prevents the filtration of water. Tlie mechanical doctrine of secretion was taught by IMalpighi and Boerhaave,^ and con- tinued to prevail until the time of Haller. All the secretions were con- ceived to be ready formed in the blood, and the glands were loolscd upon as sieves or strainers to convey off the appropriate fluids or humours. In this view of the subject, all secretion was a transudation througli the coats of the vessels, — particles of various sizes passing through pores respectively adapted for them."* The mechanical doctrine of transudation, in this shape, is founded upon supposititious data ; and the whole facts and argum^snts are so manifestly defective, that it is now abandoned. ]\IM. ]\fagendie and Fodera have, however, revived the mechanical view of late years ; but under an essentially different form, and one especially applicable to the exhalations. The former gentleman,* believing that many of these exist ready formed in the blood, thinks that the character of the exhaled fluid is dependent upon the physical arrangement of the small vessels, and his views repose upon the following experiments. If, in the dead body, Ave inject warm water into an artery passing to a serous membrane, as soon as the current is established from the artery to the vein, a multitude of minute drops may be observed ooziug through the membrane, which speedily evaporate. If, again, a solution of gelatin, coloured with vermilion, be injected into the vessels, it will often hap- pen, that the gelatin is deposited around the cerebral convolutions, and in the anfractuosities, without the colouring matter escaping from the vessels, whilst the latter is spread over the external and internal sur- faces of the choroid. If, again, linseed oil, also coloured with vermi- lion, form the matter of the injection, the oil, devoid of colouring matter, is deposited in the articulations which are furnished with large synovial capsules ; and no transudation takes place at the surface of the brain, or in the interior of the eye, M, Mageudie asks, if these be not instances of true secretion taking place post viortem^ and evidently dependent upon the phj^sical arrangement of the small vessels ; and whether it be not highly probable, that the same arrangement must, in part at least, preside over exhalation during life. M. Fodera,* to whose experiments on the imbibition of tissues we had occasion to allude under the head of Absorption, embraces the views of M. Ma- ' De Hoinine, p. 11, Lugd. Bat., 1664, ^ Haller, Element, Physiol,, vli, 3, * Piwleetiones Academics, &c,, edit. A. Haller, § 253, Gottlu., 1740-1743. * Mascagni, Nova per Poros hiorgauicoa Secretioiiem Theoria., Rom,, 1793, torn, ii, ^ Precis, &c,, edit, cit., ii. 444, ^ Magendie's Journal de Physiologie, iii. 35 ; and Reclierclies, &c., siir TAbsori^tion et PExkalatiou, Pai-is, 1824. PHYSIOLOGY OF SECRETION. 477 gendie, and so does Valentin.^ If the vessels of a dead body, M. Fodcra remarks, be injected, the substance of the injection is seen oozing through them ; and if an artery and a vein be exposed on a living animal, a similar oozing through the parietes is observable. This is more manifest if the trunk, whence the artery originates, be tied, — the fluid being occasionally bloody. If the jugular veins be tied, not only does oedema occur in the parts above the ligatures, but there is an increase of the salivary secretion. It is not necessary to refer to the various experiments of Fodcra relating to this topic, or to those of Harlan, Lawrence and Coates, Dutrochet, Fanst, Mitchell, and others. They are of the same character as those previously alluded to when treating of the imbibition of tissues; for transudation is only imbibition or soaking from within to without. MM. Magendie and Fodera, indeed, conclude, that imbibition is a primary physical cause of exhalation as it is of absorption. Another phj^sical cause, adduced by M. Magendie, is the pressure experienced by the blood in the circulatory system, which, he thinks, contributes powerfully to cause the more aqueous part to pass through the coats of the vessels. If water be forcibly injected through a syringe into an artery, all the surfaces, to which the vessel is distri- buted, as well as the larger branches and the trunk itself, exhibit the injected fluid oozing in greater abundance according to the force ex- erted in the injection. He farther remarks, that if Avater be injected into the veins of an animal, in sufficient quantity to double or treble the natural amount of circulating fluid, a considerable distension of the circulatory organs is produced, and the pressure is largely augmented. If any serous membrane be now examined, — as the peritoneum, — a watery fluid is observed issuing rapidly from it, which accumulates in the cavity, and produces a true dropsy under the eye of the experi- menter; and, occasionally, the colouring part of the blood transudes at the surface of certain organs, as the liver, spleen, &c. Hamberger, again, broached the untenable physical hypothesis, that each secreted humour is deposited in its proper secretory organ by virtue of its specific gravity,^ — but all these speculations proceed upon the belief, that the exhalations exist ready formed in the blood ; and that, consequently, the act of secretion, so far as concerns them, is one of separation or secerning, — not of fresh formation. That this is the case with the more aqueous secretions is probable, and not impossible with regard to the rest. Organic chemistry is subject to more diffi- culties in the way of analysis than inorganic ; and it can be under- stood, that in a fluid so heterogeneous as the blood the discovery of any distinct humour may be impracticable. Of course, the elements of every fluid, as well as solid, must be contained in it; and we have already seen, that not merely the inorganic elements, but the organic or compounds of organization have been detected in it by the labours of Chevreul and others. There are indeed, some singular facts con- nected with this subject. MM. Prevost and Dumas,^ having removed ' Lelirbudi der Pliysiologie des Menscheii, Bd. 1, s. 601, Braunscliweig, 1844. 2 Adelon, Physiologie del'Homme, 2de edit., iii. 455, Paris, 1821). ^ Anuales de Chimie, torn. xxii. and xxxiii. 90. 478 SECRETION. tlie kidneys in cats and clogs, and afterwards analyzed the blood, found urea in it — the characteristic element of urine. This principle was contained in greater quantity, the longer the period that had. elapsed after the operation ; whilst it could not be detected in the blood, when the kidneys were present. The experiment was soon afterwards repeated by MM. Vauquelin and Segalas^ with the same results. The latter introduced urea into the veins of an animal whose kidneys were untouched; he was unable to detect the principle in the blood ; but the urinary secretion was largely augmented after the in- jection ; whence he concludes, that urea is an excellent diuretic. Sub- sequentl}'-, MM. Gmelin and Tiedemann, iu association with JNl. Mits- cherlich,^ arrived, experimentally, at the same conclusions as M^[. Prevost and Dumas. The existence of urea in the fluid ejected from the stomach of the animal was rendered probable, but there were no traces of it in the fteces or bile. The animal died the day after the extirpation of the second kidney. They were totally unable to detect either urea or sugar of milk in the healthy blood of the cow. These circumstances would favour the idea, that certain of the se- cretions may be formed in the blood, and may simply require the intervention of a secreting organ to separate them;^ but the mode in which such separation is effected is entirely inexplicable under the doctrine of simple mechanical filtration or transudation. It is unlike any physical process that can be imagined. The doctrine of filtration and transudation can apply only to those exhalations iu which the humour has undergone no apparent change ; and it is obviously im- possible to specify these, in the imperfect state of our means of analy- sis. In the ordinary aqueous secretions, simple transudation may embrace the whole process; and, therefore, it is unnecessary to have recourse to any other explanation ; especially after the experiments instituted by M. Magendie, supported by pathological observations in which there has been partial oedema of the legs, accompanied by more or less complete obliteration of the veins of the infiltrated part, — the vessels being obstructed by fibrinous coagula, or compressed by cir- cumjacent tumours. Thus, ascites or dropsy of the peritoneum may be occasioned by obstruction of the portal circulation in the liver, and in this way we may account for the frequency with which we find a union of hydropic and hepatic afi:ections in the same individual. The like pathological doctrine, founded on direct observation, has been extended to phlegmasia dolens or swelled leg; an affection occurring iu the puerperal state, and oiten found connected with obstruction in the great veins that convey the blood back from the lower extremity. It may not, consequently, be wide of the truth — if not wholly accu- rate — to consider certain of the secretions, with Dr. Billing,'' to be "vital transudations from the capillaries into the excretory ducts of the glands, by pores invisible to our senses, even when aided by the most perfect optical instruments." ' Magendie, Precis, &c.. ii. 478. 2 Tieilemann and Treviranus, Zeitt;clirift fiir Physiol., B. v. Heft i. ; cited in Brit, and Foreit^n Med. Review, p. .')y2, fur April, 183G. 3 Dr. W. Philip, in Lond. Med. Gazette for March 25th, 1837, p. 952. * First Principles of Medicine, Anier. edit., p. 55, Philad., 1842; 2d Anier. edit., Philad., 1S51. THE0KIE9. 479 The generality of physiologists have regarded the more complex secretions — the follicular and glandular — as the results of chemical action ; and under the view, that these secretions do not exist ready formed in the blood, and that their elements alone are contained in that fluid, it is impossible not to admit that chemical agency must be exerted. In support of the chemical hypothesis, which has appeared under various forms, — some, as Keill,^ presuming that the secretions are formed in the blood, before they arrive at the place appointed for secretion; others, that the change is effected in the glands themselves, — the fact of the formation of a number of substances from a very few elements, provided these be united in different proportions, has been urged. Take, for example, the elementary bodies, oxygen and nitro- gen. These, in one proportion, form atmospheric air; in another, nitrous oxide ; in another, nitric oxide ; in a fourth, hyponitrous acid ; in a fifth, nitrous acid ; in a sixth, nitric acid, &c., compounds which differ as much as the various secretions differ from each other and from the blood. Many of the compounds of organization likewise exhibit, by their elementary constitution, that but a slight change is necessary, in order that they may be converted into each other. Dr. Prout^ has exhibited the close alliance between three substances — urea, lithic acid, and sugar, — and has shown how they may be converted into each, other, by the addition or subtraction of single elements of their con- stituents. Urea is composed of two atoms of hj^drogen, and one of carbt)n, oxygen, and nitrogen respectively ; by removing one of the atoms of hydrogen and the atom of nitrogen, it is converted into sugar; by adding to it an additional atom of carbon, into lithic or uric acid. Dr. Bostock,^ — who is disposed to push the application of chemistry to tlie explanation of the functions as far as possible, — to aid us in con- ceiving how a variety of substances may be produced from a single compound, by the intervention of physical causes alone, supposes the case of a quantity of materials adapted for the vinous fermentation being allowed to flow from a reservoir through tubes of various dia- meters, and with various degrees of velocity. "If we were to draw oft' portions of this fluid in different parts of its course, or from tubes, which differed in their capacity, we should, in tlie first instance, obtain a portion of uufermented syrup; in the next, we should have a fluid in a state of incipient fermentation; in a third, the complete vinous liquor; while, in a fourth, we might have acetous acid." Any expla- nation, however, founded upon this loose analogy, is manifestly too physical. Dr. Bostock admits this, for he subsequently remarks, that " if we adopt the chemical theory of secretion, we must conceive of it as originating in the vital action of the vessels, which enables them to transmit the blood, or certain parts of it, to the various organs or structures of the body, where it is subjected to the action of those re- agents which are necessary to the production of these changes.'' The admission of such vital agency, in some shape, is indispensable. Attempts have been made to establish secretion as a nervous action ' Tentamina Medico-Physica, iv. ; and Ilaller, Element. Physiol. , &c., lib. vii. sect. 3. ■^ Me'lico-Chirurg. Transact., viii. 540. ^ Physiol., 3d edit., p. 510, Lond., 183G. 480 SECRETION. and numerous arguments and experiments have been brought forward in support of the position. That many of the secretions are affected by the condition of the mind is known to aU. The act of crying, in evidence of joy or sorrow; the augmented secretion of the salivary glands at the sight of pleasant food; of the kidney during fear or anxiet}^; and the experimental confirmation, by Mr. Hunter, of the truth of the common assertion — that the she-ass gives milk no longer than the impression of the foal is on Ler mind, — the skin of the foal, thrown over the back of another, and frecjuently brought near her, being sufficient to renew the secretion, — sufficiently indicate, that the organs of secretion can be influenced through the nervous system in the same manner as the functions of nutrition and calorification.^ The discovery of galvanism naturally suggested it as an important agent in the process, — or rather that the nervous fluid strongly resem- bles the galvanic. This conjecture seems to have been first hazarded by Berzelius, and Sir Everard Home ;^ and, about the same time, an experiment was made by Dr. Wollaston,^ which, he conceived, threw light on the process. He took a glass tube, two inches high, and three-quarters of an inch in diameter; and closed it at one extremity with a piece of bladder. He then poured into the tube a little water, containing 540^^ ^^ ^^^ weight of chloride of sodium, moistened the bladder on the outside, and placed it upon a piece of silver. On curving a zinc wire so that one of its extremities touched the piece of metal, and the other dipped into the liquid to the depth of an inch, the outer surface of the bladder immediately indicated the presence of pure soda ; so that, under this feeble electric influence, the chloride of sodium was decomposed, and the oxide of sodium — soda — passed through the bladder. M. Fodcra'* performed a similar experiment, and found, that whilst ordinary transudation frequently required an hour before it was evidenced, it was instantaneously exhibited under the galvanic influence. On putting a solution of cyanuret of potassium into the bladder of a rabbit, forming a communication with the solution by means of a copper wire; and placing on the outside a cloth soaked in a solution of sulphate of iron, to which an iron wire was attached ; he found, by bringing these wires into communication with the gal- vanic pile, that the bladder or the cloth was suddenly coloured blue, according as the galvanic current set from without to within, or from within to without; — that is, according as the iron wire was made to communicate with the positive pole, and the copper wire with the negative, or conversely. But it is not necessary, that there should be communication with the galvanic pile. If an animal membrane, as a bladder, containing iron filings, be immersed in a solution of sulphate of co'pper, the sulphuric acid will penetrate the membrane to reach the iron, with which it forms a sulphate, and the metallic copper will ' For examples of the same kind, see Fletcher's Rudiments of Physiology, part ii. b, p. 10, Edinb., 183(); Biirdafh, Physiologie, ii. s. w., § 522; Dr. A. Combe, on Infancy, Amer. edit., chap, v., Philad., 1840; and Carpenter, Principles of Human Physiology, Amer. edit., by Dr. F. G. Smith, p. 740, Philad., 18,55. ^ Lectures on Comp. Anat., iii. 16, London, 1810; and v. 154, London, 1828. 3 Philosoph. Mag., xxxiii. 438. * Magendie"s Journal de Physiologie, iii. 35; and Recherches, &c., sur I'Absorption et I'Exhalation, Paris, 1824. THEORIES OF SECRETION". 481 be deposited on the lower surface of the membrane; the animal mem- brane, in such case, offering no obstacle to the action of the ordinary chemical affinities. With some of the chemical physiologists, there has been a disposition to resolve secretion into a mere play of electric affinities. Thus, M. Donne^ affirms, that from the whole cutaneous surface an acid humour is secreted, whilst the digestive tube, except in the stomach, secretes an alkaline mucus: hence, he infers, that the external acid^ and the internal alkaline membi^anes of the human body, represent the two poles of a pile, the electrical effects of which are appreciable b}^ the galvanometer. On placing one of the conductors of the instrument in contact with the mucous membrane of the mouth, and the other with the skin, the magnetic needle deviated fifteen, twenty, and even thirty degrees, according to its sensibility ; and its direction indicated, that the mucous or alkaline membrane took negative, and the cutaneous membrane, positive electricity. Pie further asserts, that, between the acid stomach and tlie aJkaline liver, extremely powerful electrical cur- rents are formed. These experiments do not, however, aid us mate- rially in our solution of the phenomena of secretion. They exhibit merely electrical phenomena depeudent upon diffei^ence of chemical composition. This is, indeed, corroborated by the experiments of M. Donne himself on the secretions of vegetables. He observed electrical phenomena of the same kind in them; but, he says, electrical currents in vegetables are not produced by the acid or alkaline conditions of the parts as in animals, the juice of fruits being always more or less acid. Experiments of M. Biot, however, show, that the juices, which arrive by the pedicle, are modified in some part of the fruit, and M. Donnu thinks it is perhaps to this difference in the chemical compo- sition of the juices of the two extremities, that the electrical phenomena are to be attributed. The effects of the section of the pneumogastric nerves on the func- tions of digestion and respiration have been given elsewhere, at some length. It was then stated, that when digestion was suspended by their division, Dr. Wilson Philip'^ was led to ascribe it to the secretion of the gastric juice having been arrested; an opinion, which Sir B. Brodie had been induced to form previously, from the results of experiments, which showed that the secretion of urine is suspended by the removal or de- struction of the brain; and that when an animal is destroyed by arsenic, after the division of the |:)neumogastric nerves, all the usual symptoms are produced, except the peculiar secretion from the stomach. ISir B. Brodie did not draw the conclusion, that the nervous influence is abso- lutely necessary to secretion, but that it is a step in the process; and the experiments of M. Magendie-'' on the effect of division of the nerve of the filth pair on the nutritive secretion of; the cornea, confirm the position. We have, indeed, numerous evidences, that the nervous system cannot be indispensable to secretion. In all animals, this power must exist; yet there are some in which no nervous system is apparent. Dr. Bostock* has given references to cases of monstrous or deformed ' Aiinales de Cliimie, &c., Ivii. 400 ; and .Journal Hebdomad., Fev., 1834. ^ London Medical Grazette, March 18 and March 25, ]837. 3 Precis, &c.,ii. 489. * Physiology, edit, cit., p. 525, Lend., 1836. VOL. I. — oi 482 SECRETioisr. foetuses, born witli many of their organs fully developed, yet in which there was apparently no nervous system. It may be said, however, that, in all these cases, a rudi mental nervous system may and must have existed; but setting aside the case of animals, secretion is equally effected in the vegetable, in which there is no nervous system^ yet the function is accomplished as perfectly, and perhaps in as multiple a manner, as in animals. It is manifest, therefore, that this is one of the vital actions occurring in the very tissue of organs, of which we have no more knowledge than we have of the nutritive actions in general. All that we know is, that in special organs various humours are secreted from the blood, some of which can be detected in that fluid; others not. The doctrine of developement by cells was an important step in this inquiry. It has been elsewhere shown how cells are considered to effect the work of absorption ; and secretion is probably accomplished in a similar manner. It is essentially a function of nucleated cells, — such cells possessing a peculiar organic power by virtue of wdiich they can draw into their interior certain kinds of materials, varying according to the nature of the fluid they are destined to secrete.'' Some cells have merely to separate certain ingredients from the surrounding medium; others have to elaborate within themselves matters that do not exist as such in the nutritive medium. Although secreting cells thus differ in the nature of the fluid which they secrete, their structure seems to be nearly the same in all cases, — each consisting, like other primitive cells, of a nucleus, cell-wall, and cavity. The nucleus appears to be both the reproductive organ by which new cells are generated, and the agent for separating and preparing the secreted material. The cell-cavity seems chiefly destined to contain the secreted fluid until ready to be discharged; at which time the cell, then matured, bursts and discharges its contents into the inter-cellular space on which it is situate, or upon a free surface, as the case may be. The mode of secretion in glands, of which Professor Goodsir takes the testicle of the squalus cornuhicus as a type, appeared to him to be as follows. Around the extremities of the minute ducts of the glands are developed acini or primary nucleated cells, each of which, as it increases in size, has generated, within it, secondary cells — the product of its nucleus. The cavity of the parent cell does not communicate with the duct on which it is situate until its contents are fully matured, at which time the cell-wall bursts or dissolves away, and its contents are discharged into the duct. From this constant succession of growth and solution of cells it results, that the whole parenchyma of a gland is continually passing through stages of developement, maturity'-, and atrophy, — the rapidity of the process being in proportion to the acti- vity of the secretion. There seems, consequently, in this view of the subject, to be no essentifil difference between the process of secretion, and the growth of a gland : the same cells are the agents b}^ which both are effected. The parenchj^ma of glands is chiefly made up of a mass of cells in all stages of developement: as these cells individually increase in size, and so constitute their own growth as well as that of the common glandular mass, they are at the same time elaborating ' Professor Goodsir, Transactions of the Royal Society of Edinburgli, 1842; and Ana- tomical and Pathological Observations, Ediulb., 1845. THEORIES. 483 within themselves the material of secretion, which, when matured, they discharge by dissolving away. There are numerous germinal spots or centres in a gland, from which acini or primary cells are de- veloped. The true fluid of secretion, in Mr. Goodsir's opinion, is not the product of the ])arent cell of the acinus, but of its included mass of secondary cells, which themselves become primary secreting cells, and form the material of secretion in their cavities. In some cases, these secondary cells pass out entire from the parent cell, constituting a form of secretion in which the cells possess the power of becoming more fully developed after being discharged and cast into the duct or cavity of the gland. He considers growth and secretion to be identi- cal — the same process under different circumstances,— a view which had indeed been already embraced by others, and which ought to be universal. It must be recollected, that bloodvessels, like absorb- ents, are shut sacs; and, therefore, the materials for nutrition and secretion must pass either through them in the maimer suggested by Mr. Goodsir, or by transudation. Transudation, however, would seem to be mainly, if not wholly, applicable to tenuous fluids only; whilst every solid in the body must l3e nourished by materials obtained from the blood. The agency of cells in nutrition and secretion may, there- fore, be regarded as established. Mr. Addison^ has suggested, that these cells are not developed in the organs of nutrition and secretion at the expense of materials supplied by the blood; that they are neither more nor less than the colourless corpuscles of the blood, which elaborate those products whilst still floating in its current, and. then escape from the vessels. It is not easy, however, to comj^rehend, that corpuscles, apparently identical, should exist in the blood charged with the different properties of separating bile, urine, saliva, &c., irom the fluid; or that they could escape through the parietes of the contain- ing bloodvessels, and then penetrate the parietes of the excretory ducts to take their place — it has been supposed — as epithelium cells on the lining membrane of these outlets. Moreover, as has been shown else- where, there is reason to believe, that the office of the white corpuscles of the blood is of a different character.^ In cases of vicarious secretion, we have the singular phenomenon of organs assuming an action for which they were not destined. If the secretion from the kidney, for example, be arrested, urine is occasion- ally found in the ventricles of the brain, and, at other times, a urinous fluid has been discharged by vomiting or by cutaneous transpiration : the secreting cells of those parts must, consequently, have assumed the functions of the kidney, and to this they were excited by the presence of urea, or the elements of the urinary secretion in the blood, — a fa«;t, which exhibits the important influence that the condition of the blood must exert on the secretions, and, indeed, on nutrition in general.^ It is thus that many of our remedial agents, alkalies, — the preparations of iodine, &c., — produce their efl'ects. They flrst enter the mass of blood, ' The Actual Process of Nutrition on tlie Living Structure demonstrated Ly tlie Microscope, &c., Loud., 1844. ^ See p. 3(!4 of this volume. " An interesting case of vicarious secretion of milk has been recorded in liulletino delle Scienze Mediche, April, 1839; cited in Brit, and For. Med. Rev. for Jan. 184(i; and another by Dr. S. W. Mitchell, in Amer. Journ. of the Med. Sciences for July, 1855, which will be noticed under Lactation. 484 SECRETION. and, by circulating in the capillary system, induce a modification of the function of nutrition. There are other cases, again, in which the condition of the blood being natural, the cells of nutrition may assume morbid action. Of this we have examples in the ossification of organs, which, in the healthy condition, have no bony constituent; in the de- position of fat in cases of diseased ovaria ; and in the altered secre- tions produced by any source of irritation in a secreting orgau.^ In describing the physiology of the difierent secretions, one of three arrangements has usually been adopted; either according to the nature of the secreting organ, the function of the secreted fluid, or its chemi- cal character. The first of these has been followed by MM. Bichat and jSfagendie,^ who have adopted a division into exhaled^ follicular, and glandular secretions. It is the one followed by M. Lepelletier, except that he substitutes the term j^ersjyiratonj for exhaled. According to the second, embraced by MM. Boyer,^ Sabatier," and Adelon,* they are divided into recj-ementilial, or such as are taken up by internal ab- sorption and re-enter the circulation; and excrementitia I, or such as are evacuated from the body, and constitute the excretions. Some physiologists add a third, — the recremento-excrementitial, — in which a part of the humour is absorbed and the remainder ejected. Lastly, the division accoi'ding to chemical character has been followed, with more or less modification, by Plenck,^ Richerand,' Blumenbach,^ Young,^ and Bostock ;^° the last of whom has eight classes; the aque- ous, albuminous, mucous, gelatinous, fihriyious, oleaginous, resinous, and saline. To all of these classifications cogent objections might be made. The one we shall follow is the anatomical, — not because it is the most perfect, but because it is the course that has been usually adopted throughout this worlc. Defective, too, as it is, it will enable us to take a survey of every one of the numerous secretions classified in the fol- io wins TABLE OF THE SECRETIONS. I. Exhalations OR Simple Secketioxs. A. Internal. B. External. c. Internal and external. 1. Areolar. 2. Serous. \ General and vascular. 3. Synovial 4. Adipous. \ 5. Pigmental. 6. Capsular. 1. Dermic 2. Menstrual. Gaseous Fat. Marrow. ic i^^i"- I Mucous membranes. ' See Dr. W. B. Carpenter, art. Secretion, in Cyclop, of Anat. and Phvsiol., iv. 439, Lond., 1852. ^ Precis de Physiologic, 2de edit., ii. 243, Paris, 1825. 3 Axiaiomie, 2de edit., i. 8, Paris, 1803. * Traite Coniplet d'Anatomie, Paris, 1791. ^ Physiologic de T Homme, edit, cit., iii. 438. ^ The Chemico-Physiological Doctrine of the Fluids, &:c., translated by Dr. llooiJer, Lond,., 1797. ^ Elemeiis de Physiologie, 13eme edit., chap, vi., Bnixelles, 1837. 8 Phvj^iology. by'EUiotson, 4th edit., Lond., 1828. ^ lutioduction to Medical Literature, p. 104, Lond., 1813. '0 Physiology, 3d edit., p. 48, Lond., 1836. EXHALATI02TS. 485 II. Follicular Secretions. 1. Of mucous membranes. III. Glandular Secretions. 2. Of 3. Of f 1. Of 2. Of 3. Of 4. Of 5. Of 6. Of 7. Of 8. Of the skin. , Sebaceous. Meibomian. Ceruminous. , Preputial. Odoriferous, the ovaries, the skin. the lachrymal gland, the salivary glands, the pancreas, the liver, the kidneys, the testes. the mammae. Gastro-pulmo- nary, genito- urinary, &c. I. EXHALATIONS OR SIMPLE SECRETIONS. All tbe exhalations take place into the areolae and internal cavities of the body, — or from the skin and mucous membranes; — hence such division into internal and external. The former are recrementitiaJ., the latter recremento-excremerititial. To the class of internal exhalations belong: 1. The areolar exhalation. 2. The serous exhalation. 3. The synovial exhalation. 4. The adipous exhalation. 5. The pigmental exhalation. 6. The exhalation of the areolar capsules. To the class of external exhalations belong: 1. The exhalation of the mucous mem- branes. 2. The menstrual exhalation. The gaseous exhalations may be either external or internal. A. INTERNAL EXHALATIONS. 1. Areolar Exhalatiori. A brief view of the nature of the primary areolar^ cellular, fihro- cellular, or connective membrane or tissue was given in an early part of this work. As we observe it, it is not properly cellular, but is corn- Fig. 140. Fig. 141. Portion of Areolar Tissue inflnted and rlrieil, showin;^ the general chnraoter of its larger meshes ; magnified twenty diameters. Arrangement of FiVires in Areolar Tipsue. Magnified 135 diamoters. 486 SECRETION. ]iosed of a network of fibres, and lamellre formed by tbc adhesion of fibres laid side by side; and these interw^oven so as to leave nninerous interstices and areola? amongst them, which have a tolerably free com- munication with each other/ Two kinds of fibrous tissue — the ichite and the yellow — may be de- tected in it, — the white presenting itself in the form of inelastic bands, the largest 5,^0^^^ ^^ ^^ moh in breadth, somewhat wavy in their direction, marked longitudinally by numerous streaks, and being en- tirely resolved into gelatin by long boiling; and the yellow existing in the form of long, single, elastic, branched filaments, with a dark decided border, and disposed to curl when not put upon the stretch. Tiiese interlace with the others, but seem to have no continuity of sub- stance with them. They are, for the most part, between the g o'oo^^^ ^^^^ T(5c)oo^^"^ of an inch in thickness; but are often met with both larger and smaller. It is not much changed by prolonged boiling; and appears to be mainly albuminous in its character. The interstices in the areolar membrane, wherever existing, are kept moist by a serous fluid, analogous to that exhaled from serous mem- branes, and which appears to have the same uses, — that of facilitating the motion of the lamelke, or fibres on each other, and, consequently, Fi^. 142. Fig. 143 1) ^^^'xiMm^^^k ^ \^M)Mi\l^'i<^. White FiVirous Tissue, from Ligniuent. — Magnified 65 diameters. Yellow Fibrous Tissue, from Lisramentum Nuchae of Calf. — Mareg- nancy. Pallas' has described a variety of sheep — ovis stentopyga or "fat buttocked" — which is reared in immense flocks by the pastoral tribes of Asia. In it, a large mass of fat covers the nates and occu- pies the place of the tail. The protuberance is smooth beneath, and resembles a double hemisphere, when viewed behind, — the os coccygis or rump-bone being perceptible to the touch in the notch between the two. They consist merely of fat; and, when very large, shake in walking like the buttocks of the female Bosjesman. Mr. Lawrence^ remarks, that there are herds of sheep in Persia, Syria, Palestine, and some parts of Africa, in which the tail is not wanting as in ovis stea- topyrja^ but retains its usual length, and becomes loaded with fat. According to Liebig,^ the abnormous condition, which causes an undue deposition of fat in the animal body, depends on a dispropor- tion between the quantity of carbon in the food, and that of the oxy- gen absorbed by the skin and lungs. In the normal condition, the ' Human Physiology, London, 1841, P. i. 331. 2 Fletcher, Kudimeiits of Physiology, by Dr. Lewins, pt. 3, p. 71, Edinb., 1837. 3 Travels into tlie interior of Southern Africa, p. 281, London, 1801. * Medico-Chirurgieal Transactions, vii. 157. * Spicilea;ia Zoologica, fasc. xi. p. 63. Also, Erman, Travels in Siberia, Amer. edit., Philad., 1850. •> Lectures on Physiology, Zoology, &c., p. 427, London, 1819. ^ Animal Chemistry, Webster's edit., p. 85, Cambridge, Mass., 1842. OF THE ADIPOUS MEMBRANE. 495 quanti'ty of carbon given out is exactly equal to that which is taken in the food, and the body experiences no increase of weight from the accumulation of substances containing much carbon and no nitrogen ; but if the supply of highly carbonized food be increased, then the normal state can only be preserved by exercise and labour, through which the waste of the body is increased, and the supply of oxygen accumulated in the same proportion. The production of fat, Liebig maintains, is always a consequence of a deficient supply of oxygen ; for oxygen is absolutely indispensable for the dissipation of the excess of carbon in the food. "This excess of carbon, deposited in the form of fat, is never seen in the Bedouin or in the Arab of the desert, who exhibits with pride to the traveller his lean, muscular, sinewy limbs, altogether free from fat; but in prisons and jails it appears as a pufh- ness in the inmates, fed, as they are, on a poor and scanty diet: it appears in the sedentary females of oriental countries ; and is produced under the well-known conditions of fattening of domestic animals." In accordance, too, with his views of animal temperature, already referred to, Liebig considers that in the formation of fat there is a new source of heat. The oxygen set free in the action is given out in combination with carbon and hydrogen; and whether this carbon and hydrogen proceed from the substance that yields the oxygen, or from other compounds, still there must have been generated by the forma- tion of carbonic acid or water as much heat as if an equal weight of carbon or hydrogen had been burned in air or in oxygen gas. Whether the view of Liebig be admitted or not, it is certain that the circumstances, which favour obesity, are absence of activity and ex- citement of all kinds ; hence, for the purpose of fattening animals in rural economy, they are kept in entire darkness, to deprive them of the stimulus of light, and encourage sleep and muscular inactivity. Castration — by abolishing one kind of excitability — and the time of life at which the generative functions cease to be exerted, especially in the female, are favourable to the same result, h. Marrow. A fluid, essentially resembling fat, is found in the cavity of long bones, in the spongy tissue of short bones, and in the areohe of bones of every kind. This is the marrow — -medulla ossium. The secretory organ is the very delicate membrane, which is perceptible in the inte- rior of the long bones, lining the medullary cavity, and sending pro- longations into the compact substance, and others internally, which form septa and spaces for the reception of the marrow. The cells, thus formed, are distinct from each other. From the observations of Mr. Howship,' it would seem probable, that the oil of bones is depo- sited in longitudinal canals, that pass through the solid substance of the bone, and through which its vessels are transmitted. This oil of hones is the marrow of the compact structure, the latter term being generally restricted to the secretion when contained in the cavities of long bones ; that which exists in the spongy substance being termed, by some writers, the medullary juice. The medullary membrane, called ' Medico-Cliirurg. Trans., vii. 393. 496 SECRETION. also tlie internal periostenm, consists chiefly of bloodvessels ramifying on an extremely delicate areolar tissue, in which nerves may likewise be traced. Marrow is seen in two forms, one yellow and the other red. The former which is found principally in the long bones, is a semifluid substance, and was examined by Berzelius as obtained from the hume- rus of an ox. He found it to consist of the following constituents: — pure adipous matter, 96; skins and bloodvessels, 1; albumen, gelatin, extractive, peculiar matter, and water, 3, The latter is found in the processes, and in flat and short bones ; in the bodies of the vertebrae, basis cranii, sternum, &c. That of the diploe was examined by Ber- zelius, and found to contain 75.0 water, and 25-0 solid matters — as albumen, fibrin, extractive and salts.' The marrow is one of the corporeal components, of whose use we can scarcely offer a plausible conjecture. It has been supposed to render the bones less brittle ; but this is not correct, as those of the fcetus, which contain little or no marrow, are less so than those of the adult; whilst those of old persons, in whom the medullary cavity is large, are more brittle than those of the adult. It is possible that it may be placed in the cavities of bones, — which would otherwise be so many vacant spaces, — to serve the general purposes of flit, when required by the system. The other hypotheses that have been enter- tained on the subject are not deserving of notice. 5. Pigmental Exhalation. The nature of the exhalation, which constitutes the colouring matter of the skin, will engage attention, when treating of the skin under the Sexse of Touch. It is presumed to be exhaled by the vessels of the skin, and to be deposited beneath the cuticle, so as' to communicate the colours that characterize the different races. Such is regarded as the secretory arrangement by most anatomists and physiologists ; but M. Gaultier,^ whose researches into the intimate constitution of the skin have gained him much celebrity, is of opinion, that it is furnished by the bulbs of the hair; and he assigns, as reasons for this belief, that the negro, in whom it is abundant, has short hair; that the female, whose hair is more beautiful and abundant than that of the male, has the fairest skin; and that when he applied blisters to the skin of the negro, he saw the colouring matter oozing from the bulbs and depo- sited at the surface of the rete mucosum. But the views of modern anatomists on the corpus mucosum are given elsewhere. The composition ofl-his pigment cannot be determined with pre- cision, owing to its quantity being too small to admit of examination. Chlorine deprives it of its black hue, and renders it yellow. A negro, by keeping his foot for some time in water impregnated with this gas, deprived it of its colour, and rendered it nearly white; but in a few days the black colour returned with its former intensity. The experi- ' Moser and Stralil, Handbucli der Pliysiologischen and Patliologischeii Clieniie, s. 334, Leipz., 1851. 2 Rechorcdics sur rOrc;auisation do la Peau de rHoiiime, &c., Paris. 1S09 and 1811. OF MUCOUS MEMBRANES — DERMIC. 497 ment was made with similar results on the fingers. Blumenbach^ thought, that the mucous pigment was formed chiefly of carbon ; and the notion has received favour with many. The colour, according to Henle and others, is owing to pigment cells, of which the pigmentum nigrum of the eye is wholly composed. On the choroid coat they form a kind of pavement, and have somewhat of a polyhedral shape. In the human skin, they are scattered through the ordinary epidermic cells, and the colour of the skin is determined by that of their contents. Krause,^ however, denies that the colour of the cuticle of the Ethiopian depends on pigment cells like those of the pigmentum nigrum. It is oAving chiefly, he says, to the colour of the proper nuclei and cells of the epidermis. There are, indeed, some few pigment cells mingled with the proper cells of the middle and super- ficial layers of the epidermis; but they are distinguishable from those of the pigmentum nigrum by containing far fewer pigment granules, and by having always a dark, not a clear, nucleus. The colour depends especially on the dark or almost black-brown colour of the nuclei, whe- ther free in the deep layers of epidermis or surrounded by cells. They have dark nucleoli and sharp outlines; appear only very obscurely granular, and cannot be broken into smaller pigment granules. The cells surrounding them may be seen in the deeper layers : they, also, are uniformly dark, although less so than the nuclei. In the middle and superficial layers, the nuclei, as long as they can be seen, are still dark; the cells are much paler, but brownish and darker than in the corre- sponding layers in uncoloured persons. Pigment granules are amongst the most minute structures of the body, being not more than 2000 o^^^ of an inch in their largest diame- ter, and about one-fourth as much in thickness. The uses of the pigment of the skin — as well as of that which lines the choroid coat of the eye, the posterior surface of the iris, and the ciliary processes — are detailed in other places. 6, Capsular Exhalation. Under this term, M. Adelon^ has included different recrementitial secretions effected within the organs of sense, or in parenchymatous structures, — as the aqueous, crystalline, and vitreous humours of the eye, and the liquor of Cotugno, all of which have ali-eady engaged attention ; the exhalation of a kind of albuminous, reddish, or whitish fluid into the interior of the lymphatic ganglions, and into the organs, called by M. Chaussier, glandiform ganglions^ and by M. Beclard, san- guineous ganglions; — namely, the thymus, thyroid, supra-renal capsules, and spleen. We know but little, however, of the fluids formed in these parts; and of their uses we are, in the main, ignorant. B. EXTERNAL EXHALATIONS. 1. Exltalations of the Shin and Mucous Membranes — Dermic. The mucous membranes, like the skin, which they so strongly re- semble in their structure, functions, and diseases, exhale a similar tran- ' Instit. Physiol., § 274; and Elliotson's translation, 4th edit., Lond., 1828. ^ Art. Haut, in Wagner's Handworterlnich der I'hjsiologie, 7te Lief., S. 108, Braun- schwoit;, 1S44. ^ Physiologic de I'llomme, 2de edit., toni. iii. 483, Paris, 1829. VOL. I.— 32 498 SECRETION. spiratory fluid. This lias not been subjected to chemical examination. It is, indeed, almost impracticable to separate it from the follicular secretions of the same membrane; and from the extraneous substances almost always in contact with it. It is, probably, however, similar to the fluid of the cutaneous and pulmonary depurations, both in character and use. The pulmonary transpiration, to which allusion has so often been made, bears a striking analogy to the cutaneous. Sir B. Brodie and M. Magendie, from the examination of cases of fistulous opening into the trachea, deny that it comes from the lungs, believing it to be formed by the moist .mucous lining of the nose, throat, &c.; but this view has been disproved by Paoli and Regnoli, in the case of a young female, whose trachea had been opened, and in whom, at the temperature of 39° Fahr., watery vapour was distinctly expired, through the cauula. Mojon' strangely supposes the vapour of the breath to be a watery fluid secreted by the thyroid gland, and suspended in the respired air, its volatilit}^ being caused by the presence of caloric. At one time, it was universally believed to be owing to the combustion of the hydrogen and carbon given oft" from the lungs; but we have elsewhere shown, that no such combustion occurs there; and besides, the exhalation takes place when gases containing no oxygen are respired by animals. It is now almost universally admitted to be exhaled into the air-cells of the lungs from the pulmonary artery chiefly ; but partly from the bron- chial arteries distributed to the mucous membrane of the air-passages.' Much of the vapour, Dr. Prout conceives, is deriv'ed fz'om the chyle in its passage through the lungs; and tlius, he considers, the weak and delicate albumen of the chyle is converted into the strong and perfect albumen of the blood. The air of expiration, according to Valentin^ and Brunner appears saturated with it, so that, as they have remarked, the quantity of vapour exhaled may be estimated by subtracting the quantity contained in the atmospheric air expired from the quantity, which, at the same barometric pressure, would saturate the same atmospheric air at the temperature of 99"5° — the general temperature of the air of expiration. On the other hand, if the quantity of watery vapour in the expired air be esti- mated, the quantity of the air itself may thence be accurately deter- mined — being as much as that quantity of water}^ vapour would satu- rate at the ascertained temperature and barometric pressure. It has not been established, however, that the expired air is saturated with moisture." Sundry interesting experiments have been made on this exhalation by Magendie, Milne Edwards, Breschet, and others. If water be in- jected into the pulmonary arterj^, it passes into the air-cells in mj^riads of almost imperceptible drops, and mixes with the air contained in them. M. Magendie* found, that its quantity might be augmented at ' Leggi Fisiologiclie, &c., translated by Skene, p. 76, Lond., 1827. * Sir B. Brodie, riiilosojjhical Transactious for lc?12, and Plijsioloyical Researches, p. 19, Lond., 1851. ^ Lehrbuch der Physiologic des Menschen, i. 547, Braunschweig, 1844. * Dr. John Reid, art. Rusj^iration, Cyclop, of Auat. and Phys., pt. xxxii. p. 345, Lond-, Aug., 1848. = Precis, &c., ii. 346. OF MUCOUS MEMBRANES — PULMONARY. 499 pleasure on living animals, by injecting distilled water, at a tempera- ture approaching that of the body, into the venous system. He injected into the veins of a small dog a considerable amount of water. The animal was at first in a state of real plethora — the vessels being so much distended that it could scarcely move; but in a few minutes the respiration became manifestly huiTied, and a large quantity of fluid was discharged from the mouth, the source of which appeared evidently to be the pulmonary transpiration greatly augmented. But not only is the aqueous portion of the blood exhaled in this manner, experiment shows, that many substances introduced into the veins by absorption, or by direct injection, issue from the lungs. Weak alcohol, a solution of camphor, ether, and other odorous substances, when thrown into the cavity of the peritoneum or elsewhere, were found, by M. Magendie, to be speedily absorbed by the veins, and con- veyed to the lungs, where they transuded into the bronchial cells, and were recognised in the expired air by their smell. Phosphorus, when injected, exhibited this transmission in a singular and evident manner. M. Magendie,^ on the suggestion of M. Armand de Montgarny, "a young physician," he remarks, "of much merit," now no more, in- jected into the crural vein of a dog half an ounce of oil, in which phosphorus had been dissolved: scarcely had he finished the injection, before the animal sent through the nostrils clouds of a thick white vapour, which was phosphoric acid. When the experiment was made in the dark, these clouds were luminous. M. Tiedemann^ injected a drachm of the expressed juice of garlic into a vein of the thigh of a middle-sized dog; in the space of three seconds the breath smelt strongly of garlic. When spirit of wine was injected, the exhaled vapour was, recognised when the injection was scarcely over. MM. Breschet and Milne Edwards^ made several experiments for the purpose of discovering why the pulmonary transpiration expels so promptly the different gases and liquid substances received into the blood. Considering propei'ly, that exhalation differs only from absorp- tion in taking place in an inverse direction, these gentlemen conjec- tured, that it ouglit to be accelerated by every force, that would attract the fluids from within to witliout; and such a force they conceive inspi- ration to be, which, in their view, solicits the fluids of the economy to. the lungs, in the same mechanical manner as it occasions the entrance of air into the air-cells. In support of this view they adduce the fol- lowing experiments. To the trachea of a dog a pipe, communicating with a bellows, was adapted, and the thorax was largely opened.. Natural respiration was immediately suspended; but artificial respira- tion was kept up by means of the bellows. The surface of the air-cells^ was, in this way, constantly subjected to the same pressui'e, there being no longer diminislied pressure during inspiration, as when the thorax is sound, and the animal breathing naturally. Six grains of" camphorated spirit were now injected into the peritoneum; and, at the same time, a similar quantity in another dog, whose respiration wasv ' Precis, &o., ii. 348. ^ Tiedemanii and Trcviranns, Zeitschrift ftir Pliysiologie, Band. v. II. ii. ; cited ini. British and Foreign Medical Review, i. 241, Lond., 1836. * ^ Recherches Experinientales sur rExhalation Puluioiiaire, Paris, 1S2(). 500 SECRETION. natural. In tlie course of from three to six minutes, the odorous sub- stance was detected in the puhnonarj transpiration of the latter; but in the other it was never manifested. They now exposed in the first animal a part of the muscles of the abdomen, and applied a cupping- glass to it; when the smell of the camphor speedily appeared at the cupped surface. Their conclusion was, that the pulmonary surface, having ceased to be subjected to the suction force of the chest during inspiration, exhalation was arrested, whilst that of the skin was deve- loped as soon as an action of aspiration was exerted upon it by the cupping-glass. Into the crural veins of two dogs, — one of which breathed naturally, and the other was circumstanced as in the last experiment, — they injected essential oil of turpentine. In the first of these, the substance was soon apparent in the pulmonary transpiration; and, on opening the body, it was discovered, that the turpentine had impregnated the lung and pleura much more strongly than the other tissues. In the other animal, on the contrary, the odour of the turpentine was scarcely apparent in the vapour of the lungs; and on dissection, it was not found in greater quantity in the lungs than in other tissues; — in the pleura, for instance, than in the peritoneum. From the results of these experiments, MM. Breschet and Edwards conckide, that each inspiratory movement constitutes a kind of suction, which attracts the blood to the lungs ; and causes the ejection of the liquid and gaseous substances which are mingled with that fluid, through the pulmonary surface, more than through the other exhalant surfaces of the body. In their experiments, these gentlemen did not find, that exhalation was effected with equal readiness in every part of the surface, when the cupping-glass was applied in the mode that has been mentioned. The skin of the thigh, for example, did not indi- cate the odour of camphorated alcohol as did that of the region of the stomach. The chemical composition of the pulmonary transpiration appears to be water, holding in solution, perhaps, some saline and albuminous matter; but our information on this subject, derived from the chemist, is not precise. M. Collard de Martigny's' experiments make it consist, in 1000 parts, — of water 907, carbonic acid 90; animal matter — the nature of which he was unable to determine — o. M. Chaussier found, that by keeping a portion of it in a close vessel exposed to an elevated temperature, a very evident putrid odour was exhaled on opening the vessel. This could only have arisen from the existence of nitrogeuized matter in it. The pulmonary transpiration being liable to all the modifications which affect the cutaneous, it is not surprising, that we should meet with so much discordance in the estimates of diiTerent individuals, re- garding its quantity in a given time. Ilales^ valued it at 20 ounces in the twenty -four hours: Sanctorius,^ Alenzies," and Dr. AVilliam Wood,* ' Magendie's Journal de Pliysiologie, x. 111. ^ Statical Essays, ii. 322, Lond., 1767. ^ Medicina Statica, Aplior. v. * Dissertation on Respiration, p. 54, Edinb., 1796. * Essay on the Structure, &c., of the Skin, Edinb., 1832. MENSTRUAL — GASEOUS. 501 at 6 ounces; Mr. Abernetliy' at 9 ounces; MM. Lavoisier and Scguin^ at 17| ounces poids de marc; Dr. Thomson^ at 19 ounces, Dr. Dulton at from 1 pound 8| ounces,^ to 20| ounces avoirdupois,^ Dr. Carpen- ter^ at from 16 to 20 ounces, and Kirkes and Paget^ at from 6 to 27 ounces. The uses it serves in the animal economy are identical with those of the cutaneous transpiration. It is essentially depuratory. Experiments, some of which have been detailed, have sufficiently shown, that volatile substances introduced in any way into the circulatory sy^item, if not adapted for the formation of arterial blood, are rapidly exhaled into the bronchial tubes. Independently, therefore, of the lungs being the great organs of respiration, they play a most important part in the economy, by throwing oil" those substances, that might be injurious, if retained. 2. Menstrual Exhalation. The secretion of the menstrual fluid, which is mainly a sanguineous exhalation from the vessels of the uterus, will fall more appropriately under consideration when treating of the functions of reproduction. 3. Gaseous Exlialation. The secretion of air from the bloodvessels is not so manifest as in the case of the exhalations thus far considered; but if we regard, with many, the separation of carbonic acid from the blood as a secretion, it is one of the most extensive and important in the animal economy. Gases are perpetually received into the vessels of the lungs, and to a certain degree elsewhere, whilst under the function of Respiration it has been seen, that carbonic acid is constantly exhaled. Moreover, in the swim-bladders of fishes an unequivocal case of gaseous secretion is presented; for many of these have no communication whatever, by duct or otherwise, with any outlet of the body. In the order Pharyn- gognatJu of Miiller, which includes the fiimily of the saury pike and others ; in Anacanthini, including the cod and plaice ; in Acantlwjjteri, including the perch, gurnard, mullet, mackerel, and others ; in the Pleciognathi of Cuvier, including the globe fish ; and in Lopliohranclm of the same naturalist, which includes the sea horse and pipe fish, — a characteristic is the possession of a swim bladder without an air duct. In these cases, there can be no question of the secretion of air; and accordingly such a secretion has been admitted by physiologists.^ It may account for the copious developement of air in the intestinal canal, as has been suggested elsewhere ;^ and for the production of many of the pneumatoses, which are so difficult of explanation under any other ' Surgical and Physiol. Essays, p. 141, Loud., 1793. 2 Mini, de la Societe Royale de Medecine, pour 1782-3; Annal. de Cliimie, v. 264; and Mem. de I'Acad. des Sciences, pour 1789. ^ System of Chemistry, vol. iv. " Manchester- Memoirs, 2d series, ii. 29. ^ Ibid., vol. V. ^ Human Physiology, § 549, Loud., 1842. ' Manual of Physiology, 2d Amer. edit., p. 139, Philad., 1853. * John Hunter, Observations on Certain Parts of the Animal Economy, with Notes by Prof. Owen, Amer. edit., p. 127, Philad., 1840. J. Vogel, The Pathological Anato- my of the Human Body, by Dr. Day, ]). 31, London, 1847; and Prof. Owen, Lectures on the Comparative Anatomy and Physiology of the Vertebrate Animals, p. 272, Lond., 184(1. ** Page 185. 502 SECRETION. view. The last subject lias, however, received the author's attention in another work.^ II. FOLLICULAR SECRETIONS. Follicular secretions are effected from the skin or the mucous mem- branes. Thej may be divided into two great classes; — 1st, the follicu- lar secretions of mucous membranes ; and 2dly, i\\Q follicular secretions of the skin. 1. Follicular Secretion of Mucous Membranes. Tlie whole extent of the mucous membranes lining the alimentary canal, air-passages, and urinary and genital organs, is the seat of a secretion, the product of which has received, in the abstract, the name of mucus ; although it differs somewhat according to the situation and character of the particular follicles whence it proceeds. Still, essen- tially, the structure, functions, and products of all mucous membranes are the same.^ Such is the general sentiment. M. Donne,^ however, ranges the different mucous membranes in three great divisions — ac- cording to their microscopical characters, the chemical reaction of their mucus, and the structure of the epithelium. His first division comprises those membranes that are analogous to the skin, — in other words, that secrete an acid fluid, which contains, under the form of pel- licles, or scales, the product of the desquamation of the epidermis. They are, in reality, reflections of the outer skin, and in no respect deserve the name of mucous membranes. The vaginal mucous mem- brane is one of these, being a mere reflection of the outer skin, and possessing its principal properties. It secretes a mucus, which is always acid; strongly reddening litmus paper, and filled with soft, flattened lamellie, or rather cells, like the epidermic vesicles of the skin. In regard to its physiological properties, this membrane, like the skin, is endowed with exquisite sensibility ; it is scarcely ever the seat of hemorrhage, and ulcerates less readily than raucous membranes properly so called. The membranes with acid mucus and epidermic vesicles never, he says, exhibit any epidermic cells. The second divi- sion comprises the " true raucous membranes." They differ from the skin in every respect, — both by the nature of their epithelium, and the chemical reaction of their secretion, which is always alkaline. It is viscid, and, instead of exhibiting under the microscope the epidermic lamelkie or cellules, mentioned above, it presents only mucous globules, whose structure, properties, and origin are entirely different. These membranes, of which the bronchial raucous membrane may be taken as the type, ulcerate readily; are the seat of hemorrhages, and do not possess tactile sensibility like the skin. To these belong the vibratile organs or cilia. These two orders of membranes, according to M. Donne, are found approximated, and almost confounded, although still preserving their distinct characters, in the vagina and neck of the uterus, — the one secreting a creamy, not ropy, always acid mucus; and presenting, ' Practice of Medicine, 3d edit., i. 172, Pliilad., 1848. ^ See Mucous Membranes, under the Sense of Touch. '^ Cours de Microscopie, p. 143, Paris, 1844. FOLLICULAE, OF MUCOUS MEMBEANES. 503 under tlae microscope, large epidermic cellules; tlie other furnisliing a glairy, ropy mucus, constantly alkaline, and containing mucous glo- bules much smaller than epidermic cells, and of a structure and com- position wholly different. The third division comprises a class inter- mediate between the two others, constituted by parts which participate in the organization of skin and mucous membranes, through surfaces which have not yet entirely lost the qualities of the external mem- brane, and already possess some of those of the internal or true mu- cous membranes. Such are the orifices where the skin does not ter- minate suddenly, but becomes gradually transformed into mucous membrane, as at the mouth, nose, anus, &c. These parts secrete a mucus, which M. Donne terms mixed: in this are found combined the characters of the two already mentioned, with a predominance of the one or the other, according as the properties of the skin, or those of the mucous membranes, prevail. The mucus of the mouth he regards as an example of the intermediate species.^ In the history of the different functions, in which certain of the mucous membranes are concerned, the uses of the secretion have been detailed; and in those functions, that will hereafter have to engage attention, in which other mucous membranes are concerned, its uses will fall more conveniently under notice. But few points will, there- fore, require explanation at present. The mucus secreted by the nasal follicles seems alone to have been subjected to chemical analysis. MM. Fourcroy and Vauquelin^ found it composed of the same ingredients as tears. According to the analy- sis of Berzelius,^ its contents are as follows : — water, 933'7 ; mucin o3"3 ; chlorides of potassium and sodium, 5"6 ; lactate of soda with animal matter, 3"0 ; soda, 0*9 ; albumen and animal matter, soluble in water, but insoluble in alcohol, with a trace of phosphate of soda, 3*5. Dr. G. O. Eees'' considers mucus to be a compound of albumen in a state of close combination with alkaline salts, and probably free alkali; and he affirms, that the artificial compound formed by the addition of alkalies and neutral salts to albuminous matter is essentially the same as mucus. According to M. Easpail,^ mucus is the product of the healthy and daily disorganization or wear and tear of mucous membranes. Every mucous membrane, he affirms, exfoliates in organized layers, and is thrown off, more or less, in this form ; but the serous membranes either do not exfoliate, or their exfoliation [excoriation) is reduced to a liquid state to be again absorbed by the organs. When examined by a microscope of high magnifying power, mucus presents here and there, appearances of shreds similar to those described by M. Kaspail. These have been considered by recent histologists detached epithelium cells, with granulated globular particles, which are esteemed to be ' See, on the structure, relations, and offices of the Mucous Memhrnnos, Mr. Bow- man, art. Mucous Membrane, in Cyclop, of Anat. and Physiol., Parts xxiii. and xxiv., Lond., 1842. ^ Journal de Physique, xxxix. 359. ^ Medico-Chirurg. Transactions, torn. iii. ; also, Thomson, Chemistry of Animal Bodies, p. 507, Eilinb., 1843. ■• Cyclop, of Anat. and Physiol., P. xxiii. p. 484, April, 1842. * Ciximie Organiiiue, p. 24(J, and p. 504, Paris, 1832. 504 SECRETION". cliaracteristic of the secretion from the surface of mucous membranes.^ It is never free from ejjithelium of the mucous membrane whence it originated; and, according to Lehmann,^ may be said to consist almost entirely of epithelium, which seems to be held together only hj means of a pellucid juice. Although mucus is classed as a follicular secretion, it would seem to be formed in mucous membranes in which no follicles can be detected, as in those lining the frontal and other sinuses of the cranium. M. Mandl,^ — who first stated the belief in the identity in structure of the globules of mucus and pus and the red corpuscles of the blood, — describes mucus as composed of a viscid liquid in which are swim- ming, besides lamellae of epithelium, special elements, which he calls globules of mucus. These are of two kinds, — the one consisting of mammillated corpuscles, 0-005 to 0'006 of a rnillimHre in diameter ; the other, from 0*01 to 0"02 of a millim^re in diameter, — the latter being true cells, composed of an envelope and a nucleus. The great use of mucus, wherever met with, is to lubricate the sur- face on which it is poured. Experiments, however, by Oesterlen'' have proved the influence of the layer of mucus, which lines the digestive canal, in retarding both the imbibition of fluids inclosed within the canal, and the permeation of fluids by endosmose. The passage of fluid into, or through, the mucous membrane of the intes- tines was, in many cases, more than twice as rapid when the mucus had been removed as when still adherent. 2. Follicular Secretion of the /Skin. This is the sebaceous and micaceous humour, observed in the skin of the cranium, and in that of the pavilion of the ear. It is, also, the humour, which occasionally presents the appearance of small worms beneath the skin of the face, when it is forced through the external aperture of the follicle; and when exposed to the air causes the black spots sometimes observable on the face. The following were found by Esenbeck^ to be its constituents : fat, 24-2 ; osmazome, with traces of oil, 12'6 ; watery extractive matters, 11-6; albumen and casein, 24-2; carbonate of lime, 2-1; phosphate of lime 20'0; carbonate of magnesia, 1*6; acetate of soda, and chloride of sodium, traces. The cutaneous or miliary follicles or glands are referred to elsewhere, in describing the anatomy of the common integument. At times, they are simple crypts, formed merely by an inversion of the common inte- gument ; at others, more complicated but still a like inversion ; and they usually open into channels by which the hairs issue. (Fig. 147, 2.) In certain parts of the skin, they are more numerous than in others. !Mr. Eainey was unable to detect them in the palms of the hands and ' For the different forms of mucus, see Donne, op. cit., p. 145. 2 Lehrbueli der Fhysiologisclien Cliemie, ii. 3(51, Leipz., 1850 ; or Amer. edit, of Dr. Day's translation by Dr. R. E. Rogers, ii. 85, Philad., 1S55. ' Manuel d'Anatomie Generale, p. 478, Paris, 1843. ^ Beitrilse zur Plivsioloifie des Gesuuden und Kranken Organismus, S. 245, Jena, 1-43. * V. Bruiis, Lelirbuch der Allgemeineu Anatomic, S. 353, Braunscliweig, 1841. FOLLICULAE, OF THE SKIN. 605 soles of the feet. Fig- 147. Their appearance ill the axilla of the negro has been described by Professor Hor- ner.' Their gran- ular or composite character in the axilla, he thinks, is sufficiently evi- dent ; but the point is yet to be settled, whether their excretory ducts have the tortuous arrange- ment of those of the ceruminous glands, o r whether they be branched and racemose, like those of the sali- vary. Mr. Has- salP afiirms, that they are similar in organization to the sudoriparous glands, but much larger. The secretion from the dift'erent cutaneous folli- cles differs, pro- bably, according to the different character and ar- rangement of ani- mal membrane from which the cells that form it are developed. There is, certain- ly, a marked dif- ference between the fluids secreted in the axilla, groin, prepuce, feet, &c., each appearing to have its characteristic odour; Sebaceous or Oil Glands and Ceruminous Glands. 1. S'^cfion of skin, magnified three diameters. 2, 2. Hairs. 3, 3. Superfi- cial sebaceous glauds. 1, 1. Larger and deeper-seated glands by which the cerumen appears to be secreted. 3. A ceruminous ghmd m,ore largely mag- nified, formed of convoluted tube 1, forming excretory duct 2. 3. A small vessel, and its branches. 3. A hair from meatus auditorius, perforating epi- dermis at 3, and at 4, contained within its double follicle, o, 5. 1, 1. Seba- ceous follicles of hair with their excretory ducts. Fis. 14S. Cutaneous Follicles or Glands of tho Axilla, magnified one-third. ' American Journal of the Medical Sciences, for January, 1846, p. 13. * The Micro.scopic Anatomy of the Iluman Body, Part xiii. p. 42tj, Lond., 1848. 506 SECRETION". although a part of this may be owing to changes occurring in the mat- ter of secretion by retention in parts to which the free access of air is prevented. The cutaneous or miliary glands, depicted by Dr. Horner, are considered by him to be the glandulce odoriferoe. of the axilla. Id many animals odorous secretions of a similar character are formed by special organs; but whether the scent peculiar to animals and to races is thus secreted is canvassed elsewhere, and must be regarded as some- what unsettled. The cerumen is a follicular secretion, as well as the whitish, odorous and fatty matter — smegma — which forms under the prepuce of the male, and in the external parts of the female, where cleanliness is disregarded. The Jiumour of Meihomius is also follicular, as well as that of the carun- cula lacrymalis, of the crypts around the base of the nipple, &c. The use of these secretions is to favour the functions of the parts over which they are distributed. Fig. 149. That which is secreted from the skin is spread over the epider- mis, hair, &c., giving suppleness and elasticity to the parts ; ren- dering the surface smooth and polished, and thus obviating the evils of abrasion that might otherwise arise. It is also con- ceived, that its unctuous nature may render the parts less per- meable to humidity. In the ducts of the sebaceous follicles, a parasite was discover- ed by M. Simon, of Berlin ;' which has been minutely de- scribed by Mr. Erasmus Wil- Entozoa from the Sebaceous Follicles. SOn,^ ProfcSSOr Yogel,' McSSrS. Tocld and Bowman,^ and Pro- fessor Owen.* It is the ylca?-ws folUculorum of Simon, Demodex foUicuhrum of Owen, and Steatozoon. follicuhrum of Mr. Wilson. By him two chief varieties of the adult animal are depicted. These are mainly distinguished by their length — the one measuring from the yi^th to the -^\t\ the other from the yjj^th to the y^^th of an inch. The marginal figure represents them as found by Messrs. Todd and Bowman in a sebaceous follicle of the scalp. They do not appear to be of any physiological or pathological importance. * Miiller's Archiv., s. 218, 1842. 2 On Diseases of tlie Skin, 2d Amer. edit., p. 424, Philad., 1847 ; and in Pliiloso- pliical Transactions for 1844. * The Pathological Anatomy of the Human Body ; translated by Dr. Day, p. 453, Lond., 1847. * The Physiological Anatomy and Physiology of Man, p. 42.5, Lond., 1845. * Lectures on the Comparative Anatomy and Physiology of the Inveilebrate Animals, p. 251, Loud., 1843. a. Two seen in their ordinary position in the orifice of one of the sebaceous follicles of the scalp, b. Short variety, c. Long variety. TEANSPIRATORY, OF THE SKIN. 507 3. Secretion of the Ovaries. The secretion of the ovaria — the formation of ova — is accomplished in the follicles of De Graaf. They are devoid of outlet ; and the secre- tion has to make its way to the surface of the ovary and be discharged, — the Fallopian tube receiving it, and acting as an excretory duct. The mode in which this is accomplished falls more appropriately under consideration, when the functions of Eeproduction are inves- tigated. III. GLAXDULAK SECRETIONS. The glandular secretions are seven in number; the transpiration, tears, saliva, pancreatic juice, bile, urine, sperm, and milk. 1. Transpiratory Secretion of the Skin. A transparent fluid is constantly exhoaled from the skin, which is generally invisible in consequence of its being converted into vapour as soon as it reaches the surface ; but, at other times, owing to augmen- tation of the secretion, or to the air being loaded with humidity, it is apparent on the surface of the body. When invisible, it is called in- sensible transpiration or perspiration ; when perceptible, siceat. In the state of health, according to M. Thenard,^ this fluid reddens litmus paper; yet the taste is rather saline — resembling that of common salt — than acid. AVagner,^ indeed, affirms that it generally shows alka- line reaction ; and, at other times, does not affect vegetable blues ; but the sweat of many parts of the body, — the armpits for example, — is said always to react like an alkali. Allusion has already been made to the views of M. Doniic,'^ who considers, that the external, and the internal alkaline membranes of the human body represent the two poles of a pile, the electrical effects of which are appreciable by the galva- nometer. The smell of the perspiration is peculiar, and when concentrated, and especially when subjected to distillation, becomes almost insup- portable. The fluid is composed, according to M. Thcnard, of much water, a small quantity of acetic acid, chloride of sodium, and perhaps of potassium, a very little eartliy phosphate, a trace of oxide of iron, and an inappreciable quantity of animal matter. Berzelius'* regards it as water holding in solution chlorides of potassium and sodium, lactic acid, lactate of soda, and a little animal matter; Anselmino,'' as con- sisting of a solution of osmazome, chlorides of sodium and calcium, acetic acid, and an alkaline acetate, salivary matter, sulphates of soda and potassa, and calcareous salts, with mucus, albumen, sebaceous humour, and gelatin in variable proportions; and M. EaspaiP looks upon it as an acid product of the disorganization of the skin. The solid constituents, according to Simon, ^ are a mixture of salts and ex- ' Trait*', de Cliimie, torn. iii. 2 Elements of Physiology, by R. Willis, § 204, Loud., 1842. * Journal Hebdomad., Fevrier, 1834. * Medico-Chir. Trans., iii. 256. * Lepelletier, Physiologie M' dicale et Pliilosopliique, ii. 452, Paris, 1832. ^ Chimie Organique, p. 505, Paris, 1832. ' Animal Chemistry, Sydenham Society's edit., ii. 101, Lond., 1846. 508 SECRETION. Fi£j. 150. tractive matters, of wliicli tlie latter preponderate: the principal ingre- dient of the salts is chloride of sodium. From what he admits to be superficial and merely qualitative investigations, he considers he has established the existence in normal sweat, of — First. Substances soluble in ether ; traces of fat, sometimes including butyric acid. Secondbj. Substances soluble in alcohol ; al- cohol extract; free lactic or acetic acid ; chlo- ride of sodium ; lactates and acetates of po- tassa and soda; lactate or chlorohydrate of ammonia. Thirdly. Substances soluble in water ; water extract ; phosphate of lime, and occasionally an alkaline sulphate ; and, fourtldy. Substances insoluble in water; de- squamated epithelium; and — after the re- moval of the free lactic acid by alcohol — phosphate of lime with a little peroxide of iron. In the solid matter urea was detected by Landerer,^ and also by M. Favre,^ — whose researches are more complete and exact than any perhaps that had been before under- taken. He found the constituents of hum;in sweat to be as follows: chloride of sodium, 2"2305 ; chloride of potassium, 0"2i37; alka- line sulphates, 0'0115; phosphoric acid, traces; earthy phosphate, traces; calcareous salts, traces; alkaline albuminate, 0-0050; epithe- lium, lactates of potassa, traces; and soda, O-ain ; hydrotates,^ 1-5623 ; urea, 0-0428 ; fat, 0-0136; water, 995-5733. Schottin,'' however, was unable to detect either urea or ammonia in the matter of perspiration. After evaporation upon a clean glass plal ;.', fragments of epidermic cells are generally ob- served in it, and crystals are left behind, which are those of its contained salts. With great care to avoid admixture, Krause^ collected a small quantity of pure cutaneous perspiration from the palm of the hand, where there are no sebaceous follicles. The fluid yielded, with boiling ether, some small globules of oil and crystals of margarin. It was acid, but alter twenty -four hours became alkaline by the developement of ammonia. ' Gr. 0. Rees, art. Sweat, Cyclopedia of Anatomy and Physiology, pt. xxxvii. p. 844, Lond., October, 1849. 2 Comptes Rendiis, xxxv. 721 ; Arcliives Uenerales de Med., Juillet, 1853 ; and Bec- querel and Rodier, Traite de Cliimie Pathologique, p. 525, Paris, 1854. 3 M. Favre affirms that he discovered a new nitrogenous acid in the sweat, which he calls the hydrotic or sudoric. * Canstatt, Ibid., S. 120. ^ Art. llaut, in Wagner's Handworterbuch der Physiologie, 7te Lieferung, S. 108. Vertical Section of the Skin of. the Sole. a. Cuticle; the deep layers (rete mucosum) more coloured than the upper, and their particles rounded; the superficial layers more and more scaly. 6. Papillary struc- ture, c. Cutis, d. Sweat-gland, lying in a cavity on the deep sur- face of the skin, and Imbedded in globules of fat. Its duct is seen passing to the surface. Magnified 40 diameters. TRANSPIEATOEY, OF THE SKIN". 509 In another experiment, lie found, that the tissue of the epidermis con- tains a fatty substance independently of the fatty matter secreted on its surfice. In a memoir presented to the Academic Royale des Sciences of Paris, MM. Breschet and Koussel de Vauzeme first clearly showed, that there exists in the skin an apparatus for the secretion of the sweat, consisting of a glandular parenchyma, which secretes the liquid, and of ducts, which pour it on the surface of the body. These ducts are arranged spirally, and open very obliquely under the scale of the epidermis. To this apparatus they applied the epithet ^^ diajmogenous f^ and called the ducts ^^sudoriferous or hidrophorousP^ Each sudoriparous gland consists of a coil or excretory duct sur- rounded by bloodvessels, and imbedded in fat vesicles. Thence the duct passes in the manner represented in the marginal figure, towards the surface, and opens on the epidermis by an oblique valve-like aper- ture. The excretory duct is lined by epithelium, which is a prolonga- tion of the epidermis. These glands are numerously distributed; but especially so in the palms of the hand, and soles of the foot. In the Fig. 151. Fiff. 152. Vertical Section of Epiderniit!, from Palm of the Hand. a. Outer portion, composed of flattened scales. h. Inner portion, consisting of nucleated cells. c. Tortuous perspiratory tube, cut across by the section higher up. — Magnified lOJ diameters. Surface of the Skin of the Palm, showing the Riilf^es, Furrows, Cross-grooves, and Orifices of the Sweat-ducts. The scaly texture of the cuticle is indicated by the irregular lines on the surface. — Magnified 20 diame- ters. former situation they amount, according to Professor Krause,^ to 2736 in every square inch ; and in the latter, to 2685. Mr. K. AVilson^ ' Op. cit., s. 131. 2 Bresobet, Nouvelles Reclierches sur la Structure de la Peau, Paris, 1835. "' Healthy Skin, p. 42, Lond., 1845 ; or Auicr. edit., p. OS, PLilad., 1854. 510 SECRETION. counted the perspiratory pores on the palm of the hand, and found 3528 in a square inch; and each of these pores being the aperture of a little tube of about a quarter of an inch long, it follows, that in a square inch of skin, on the palm of the hand, there exists a length of tube equal to 882 inches, or 73| feet. To obtain an estimate of the length of tube of the perspiratory system of the whole surface of the body, he thinks that 2800 might be taken as a fair average of the number of pores in the square inch; and 700, consequentlj^, of the number of inches in length. "Now the number of square inches of surface in a man of ordinary height and bulk is 2500 ; the number of pores, therefore, 7,000,000, and the number of inches of perspiratory tube, 1,750,000; that is, li5,83o feet or 48,600 yards, or nearly 28 miles!" Numerous experiments have been instituted for the purpose of dis- covering the quantity of transpiration in a given time. Of these, the earliest were by Sanctorius, — for which he is more celebrated than for any of his other labours, — after whom the cutaneous transpiration was called Perspirahile Sanctorianiirn} For thirty years, this indefatigable experimentalist weighed daily, with the greatest care, his solid and liquid ingesta and egesta, and his body, with the view of deducing the loss sustained by the cutaneous and pulmonary exhalations. He found, that every twenty-four hours his body returned to the same weight, and that he lost the whole of the ingesta ; — five-eighths by transpira- tion, and three-eighths by the ordinary excretions. For eight pounds of ingesta there were only three pounds of sensible egesta, which con- sisted of forty-four ounces of urine, and four of feces. It is lamentable to reflect, that so much time Avas occupied in the attainment of such insignificant results. The self-devotion of Sanctorius gave occasion, however, to the institution of numerous experiments of the same kind ; as well as to discover the variations in the exhalation, according to age, climate, &c. The results of these have been collected by Ilaller,^ but they afford little instruction ; especially as they were directed to the transpiration in general, without affording any data from v/hich to calculate the proportion exhaled from the lungs compared with that constantly given off by the cutaneous surface. Bye,^ who dwelt in Cork, lat. 51° 54', found, in the three winter months — December, Janu- ary, and February — that the quantity of urine was 3937 ounces; of perspiration, 4797; in the spring months — March, April, and ^lay — the urine amounted to 3558 ; the perspiration to 5405 ; in the summer months — June, July, and August — the former amounted to 3352 ; the latter to 5719; and in the three autumnal months — September, October, and November — the quantity of urine was 3369; of perspiration, 4471. The daily average estimate in ounces was as follows: — Urine. Perspiration. Winter 42,^5 53 Spring, 40 60 yummer, ......... 37 63 Autumn, ......... 37 50 Thus making the avei'age daily excretion of urine, throughout the ' Ars Sanctorii de Statica Medicina, cum Comment. Martini Lister, Lugd. Bat., 1711. 2 Elem. Physiol., xii. 2, 10. ' Rogers on Epidem. Diseases, Appendix, Dubl., 1734. TRAXSPIRATORY, OF THE SKIN. 511 year, to be a little more than 39 ounces; and of the transpiration, 56 ounces. Keill/ on the other hand, makes the average daily perspira- tion, 31 ounces; that of the urine, 38; the weight of the feeces being 5 ounces, and of the solid and liquid ingesta, 75. His experiments were made at Northampton, England, lat. 52° 11'. Bryan liobinson^ found, as the result of his observations in Ireland, that the ratio of the perspiration to urine was, in summer, 5 to 3; in winter, 2 to 3; whilst in April, May, October, November, and December, they were nearly equal. In youth, the ratio of the perspiration to urine was 1340 to 1000; in the aged, 967 to 1000. Hartmann, when the solid and liquid ingesta amounted to 80 ounces, found the urine discharged 28 ounces; the fasces, 6 or 7 ounces; and the perspirable matter, -15 or 46 ounces. De Gorter,^ in Holland, when the ingesta were 91 ounces, found the perspiration amount to 49 ounces; the urine to 36; and the fasces to 8. Dodart^ asserts, that, in France, the ratio of the perspiration to the fasces is as 7 to 1 ; and the whole ,egesta 15 to 12 or 10. The average per- spiration in the twenty-four hours, he estimates at 33 ounces and two drachms; and Sauvages, in the south of France, found, that when the ingesta were 60 ounces in the day, the transpiration amounted to 33 ounces; the urine to 22 ; and the faeces to 5. But most of these esti- mates were obtained in the cooler climates, — the ^Wegiones loreales,''^ — as Ilaller-' has, not very happily, termed them. According to Lining,^ whose experiments were made in South Caro- lina, lat. 32° 47', the perspiration exceeded the urine in the warm months; but in the cold, the latter had the preponderance. The fol- lowing table, quoted by Haller, gives the average daily proportion of urine and perspiration, for each month of the year, in ounces. Urine. Perspiration. December, 70-81 42-55 January, 72-43 39-97 February, 77-86 37*45 March, 70-59 43-23 April, 59-17 47-72 May, 56-15 58-11 June, 52-90 71-39 July, 43-77 86-41 August, 55-41 70-91 September, 40-60 ^ 77-09 October, 47-67 40-78 November, 63-16 40-97 After the period at which Haller wrote, no experiments of any moment were made for appreciating the transpiration. Whenever trials were instituted, the exhalation from both the skin and lungs was included in the result, and no satisfactory means were adopted for separating them, until MM. Lavoisier and Scguin^ made their cele- brated experiments. M. Seguin enclosed himself in a bag of gummed taffeta, which was tied above the head, and had an aperture the edges ' Tentamina Medico-Phys., Appendix, Lond., 1718. ^ Dissertation on tlie Food and Discharges of Human Bodies, Dublin, 1748. " De Perspiratione Insensibili, Lugd. Bat., 1736. * Memoir, de I'Acad. des Sciences, ii. 276. ^ Op. cit. ^ Philos. Transact, for 1743 and 1745. ' Memoir, de I'Acad. des Sciences de Paris, Paris, 1777 and 1790. 512 SECRETION". of which were fixed firound the mouth by a mixture of turpentine and pitch. By means of this arrangement, the puhnonary transpiration, alone escaped into the air. To estimate its quantity, it was merely necessary for M. Seguin to weigh himself in the sac by a very delicate balance, at the commencement and termination of the experiment, By repeating it out of the sac, he determined the total quantity of transpired fluid; so that, by deducting from this the quantity of fluid exhaled from the lungs, he obtained the amount of cutaneous tran- spiration. He, moreover, kept an account of the food which he took; of the solid and liquid egesta; and, as far as he was able, of every cir cumstance that could influence the transpiration. The results — as applicable to Paris, at which MM. Lavoisier and Seguin arrived, by a series of well-devised and well-conducted experi- ments — were the following: — First. Whatever may be the quantity of food taken, or the variations in the state of the atmosphere, the same individual, after having increased in weight by the whole quantity of nourishment taken, returns daily, after the lapse of twenty-four hours, to nearly the same weight as the day before ; — provided he is in good health; his digestion perfect ; not fattening nor growing; and avoids all kinds of excess. Secondly. If, when all other circumstances are identical, the amount of food varies; or if — the amount of food being the same — the efl'ects of transpiration differ, the quantity of the excre- ments augments or diminishes, so that every day at the same hour we return nearly to the same weight ; proving, that when digestion goes on well, the causes, that concur in the loss or excretion of the food taken in, afford each other mutual assistance, — in the state of health one charging itself with what the other is unable to accomplish. Thirdly. Defective digestion is one of the most direct causes of dimi- nution of transpiration. Fourthly. When digestion goes on well, and the other causes are equal, the quantity of food has but little eft'cet on the transpiration. M. Seguin affirms, that he has very frequently taken at dmner two pounds and a half of solid and liquid food; and at other times four pounds; yet the results in the two cases differed but little, — provided only the quantity of fluid did not vary materially in the two cases. Fifthly. Immediately after dinner, the transpiration is at its minimum. Sixthly. When all other circumstances are equal, the loss of weight induced by insensible transpiration is at its maximum during digestion. The increase of transpiration during digestion compared with the loss sustained when fasting, is, on an average, 2f^ grains per minute. Seventhly. AVhen circumstances are most favourable, the greatest loss of weight caused by insensible transpiration was, accord- ing to their observations, 82 grains per minute; consequently, 8 ounces, 2 drachms and 48 grains poids de marc, per hour; and 5 pounds in twenty-four hours, under the calculation, that the loss is alike at all hours of the day, which is not, however, the fact. ' Eighthly. When all the accessory circumstances are least favourable, provided only that digestion is properly accomplished, the smallest loss of weight is 11 grains per minute; consequently, 1 ounce, 1 drachm and 12 grains per hour; and 1 pound, 11 ounces and 4 drachms in the twenty -four hours. Nirdlily. Immediately after eating, the loss of weight caused by the insensible perspiration is 10^ grains per minute during the time at i TRANSPIRATORY, OF THE SKIN. 513 •whicli all tlie extraneous causes are most unfavourable to transpiration; and ISi'g grains per minute wlien these causes are most favourable, and the internal causes are alike. "These differences," says M. Seguin, "in the transpiration after a meal, according as the causes influencing it are more or less favourable, are not in the same ratio with the differences observed at any other time when the other circumstances are equal; but we know not how to account for the phenomenon." Terdhhj. The cutaneous transpiration is immediately dependent both on the solvent virtue of the circumambient air, and the power possessed by the ex- halants of conveying the perspirable fluid as far as the surface of the skin. Eleventhly. From the average of all the experiments it seems, that the loss of weight caused by the insensible transpiration is 18 grains per minute; and that, of these 18 grains, 11, on the average, belong to the cutaneous transpiration, 7 to the pulmonary. Twelfthly. The pulmonary transpiration, compared with the volume of the lungs, is much more considerable than the cutaneous, compared with that of the surface of the skin. Thirteenthly. AVhen all other circumstances are equal, the pulmonary transpiration is nearly the same before and immediately after a meal; and if, on an average, it is 11 \ grains per minute before dinner, it is VI ^^ grains after dinner. Lastly. All in- trinsic circumstances being equal, the weight of the solid excrements is least during winter. Although these results are probably fairly deduced from the experi- ments ; and the experiments themselves almost as well conceived as the subject admits of, we cannot regard the estimates as more than approximations. Independently of the fact, that the envelope of taffeta must necessarily have retarded the exhalation, by shutting off' the air, and causing more to pass off by pulmonary transpiration, the perspi- ration must incessantly vary, according to circumstances within and without the system : some individuals, too, perspire more readily than others ; and the amount exhaled is dependent, as we have seen, upon climate and season, — and likewise upon the quantity of fluid received into the digestive organs. From these and other causes, Bichat was led to observe, that the endeavour to determine the quantity of the cutaneous transpiration is as vain as to endeavour to specify what quantity of water is evapo- rated every hour on a fire, the intensity of which is varying every instant. To attempt, however, the solution of the problem, experi- ments were undertaken by Cruikshank,' and by Abernethy. Their plan consisted in confining the hand, for an hour, in an air-tight glass jar, and collecting the transpired moisture. Mr. Abernethy, having weighed the fluid collected in the glass, multiplied its quantity by 88J, the number of times he conceived the surface of the hand and wrist to be contained in the wdiole cutaneous surface. This gave 2J pounds, as the amount exhaled from the skin in the twenty four hours, on the supposition, that the whole surface perspires to an equal ex- tent. These experiments have been repeated by Dr. William Wood,'' of Newport, England, with some modifications. He pasted around the ' Experiments on the Insensible Perspiration, p. 5, Lond., 1795. ^ An Essay on the Structure and Functions of the Skin, &€., Edinb., 1832. VOL. I. — 33 514 SECRETION, mouth of a jar one extremity of a bladder the ends of whicli were cut away, and the hand being passed through the bLadder into the jar, the other extremity was bound to the wrist with a ligature, not so tight, however, as to interfere, in any degree, with the circulation. The exact weight of the jar and bladder had previously been ascertained. During the experiment, cold water was applied to the outer surface of the jar, to cause the deposition of the fluid accumulated within. The result of his experiments was as follows : — :p. Time of day. Temperature in Piilse per Fluid collected in apartment. minute. an hour. 1 Noon. 66° 84 32 grs. 2 Do. . , 66 78 32 3 Do. 66 78 26 4 Do. 61 84 32 5 9 P.M. 62 80 26 6 Do. 62 75 23 Mean 63-8 79-8 28-5 The next thing was to estimate the proportion, which the surface of the hand and wrist bears to the whole surface of the body. Mr. Aber- nethy reckoned it as 1 to 38J, and Mr. Cruikshank as 1 to 60! Dr. Wood does not adopt the estimate of either. He thinks, however, that the estimate of the former as regards the surface of the hand and wrist, which he makes seventy square inches, is near the truth, having found it correspond both with his own measurements and the reports of glovers. Mr. Abernethy's estimate of the superficial area of the whole body — 2700 square inches, or above eighteen square feet, he regards as too high. Perhaps the most general opinion is, that it amounts to sixteen square feet, or 2304 square inches ; but Haller did not think it exceeded thirteen square feet, or 2160 square inches. Dr. Wood adopts the former of these estimates, and is disposed to think, that the proportion of the surface of the hand and fingers, taken to the extremity of the bones of the arm, does not fall short of 1 to 2, which if we adopt the ratio of the quantity, he found transpired per hour, gives, for the whole body, about forty-five ounces, or nearly four pounds troy in the twenty -four hours. This is considerably above the result of the experiments of either S^guiu or Abernethy ; yet, on re- viewing the experiments, Dr. Wood is not disposed to think it far from the truth. Dr. Dalton, of Manchester, undertook a series of experiments similar to those of Sanctorius, Keill, Hartmann and Dodart.' The first he made upon himself in the month of March, for fourteen days in suc- cession. The aggregate of the articles of food consumed in this time was as follows, — bread, 168 ounces avoirdupois; oaten cake, 79 ounces; oatmeal, 12 ounces; butcher's meat, 5-1 J ounces; potatoes, 130 ounces; pastry, 55 ounces; cheese, 32 ounces: — Total of solid food, 525| ounces; averaging 38 ounces daily: — of milk, 435 J ounces; beer, 230 ounces; tea, 76 ounces; — Total of liquid food, 741|, averaging 53 ounces of fluid daily. The daily consumption was, consequently, 91 ounces ; or nearly six pounds. During the same period, the total quantity of ■ Manchester Memoirs, vol. v. TRANSPIRATOEY, OF THE SKIN. 515 urine passed was 680 ounces; of faeces, 68 ounces — the daily average being, — of urine, 48 J ounces; of faeces, 5 ounces: making 53 J ounces. If we subtract these egesta from the ingesta, there will remain 37| ounces, which must have been exhaled by the cutaneous and pulmo- nary transpirations, on the supposition that the weight of the body remained stationary. To test the influence of difference of seasons, Dr. Dalton resumed his investigations in the month of June of the same year. The results were as might have been anticipated, — a less consumption of solids and a greater of fluids; a diminution in the evacuations and an increase in the insensible perspiration. The ave- rage of solids consumed per day was 84 ounces ; of fluids, 56 ounces; — total, 90 ounces; the daily average of the evacuations — urine, 42 ounces; faeces, 4J, — leaving a balance of nearly 44 ounces for the daily loss by perspiration, or one-sixth more than during the cooler season. He next varied the process, with the view of obtaining the quantity of perspiration, and the circumstances attendant upon it more directly. He procured a weighing beam, that would turn with one ounce. Dividing the day into periods of four hours in the forenoon, four or five in the afternoon, and nine in the night — or from ten o'clock at night to seven in the morning — he endeavoured to find the perspi- ration corresponding to these periods respectively. He weighed him- self directly after breakfast, and again before dinner, observing neither to take, nor part with, any thing in the interval, except what was lost by perspiration. The difference in weight indicated such loss. The same course was followed in the afternoon and night. This train of experiments was continued for three weeks in November. The mean hourly losses by transpiration were; — in the morning, 1'8 ounce avoir- dupois; — afternoon, 1-67 ounce; night, 1-5. During twelve days of this period he kept an account of urine corresponding in time with perspiration. The ratio was as 46 to 33. From the whole of his in- vestigations on this subject. Dr. Dalton concludes; — that of six pounds of aliment taken in the day, there appears to be nearly one pound of carbon and nitrogen together; the remaining five pounds are chiefly water, which seems necessary as a vehicle to introduce the other two elements into the circulation, and also to supply the lungs and mem- branes with moisture; — that very nearly the whole quantity of food enters the circulation, for the fasces constitute only y'gth part, and of these a part — bile — must have been secreted; — tliat one great portion is thrown off' by the kidneys, namely, about half of the whole Aveight taken, but probably more or less according to climate, season, &c, ; — that another great portion is thrown oft' by means of insensible per- spiration, which may be subdivided into two parts, one of which passes oft' by the skin — amounting to one-sixth part, and the other five-sixths are discharged from the lungs in the form of carbonic acid, and water or aqueous vapour. M. Edwards' instituted experiments with the view of illustrating the eft'ect produced upon cutaneous transpiration by various circum- stances to which the body is subjected, flis first trials were made on cold-blooded animals, in which the cutaneous transpiration can be ' Sur rinfluence des Agens Physiques, Paris, 1822 ; or translation by Hodgkiu and Fisher, Loud., 1832. 516 SECRETION, readily separated from the pulmonary, owing to the length of time they are capable of living without respiring. All that was necessary was to weigh the animal before and after the experiment, and to make allowance for the ingesta and egesta. In this way he discovered, that the body loses successively less and less in equal portions of time; — that the transpiration proceeds more rapidly in dry than in moist air; in the extreme states nearly in the proportion of 10 to 1 ; — that tem- perature has, also, considerable influence, — the transpiration at 6S° of Fahrenheit, being twice as much ; and at 10-i°, seven times as much as at 82°, He likewise found, that frogs transpire, whilst they are in water, as is shown by the diminution they experience while immersed in that fluid, and by the appearance of the water itself, which becomes perceptibly impregnated with the matter excreted by the skin. In warm-blooded animals, as in the cold-blooded, the transpiration became less and less in proportion to the quantity of fluid evaporated from the body ; and he observed the same difference between the eflects of moist and dry air, as between a high and a low temperature. The effects of these agents were essentially the same on man as on animals. He found, that the transpiration was more copious during the early than the latter part of the day, and after taking food; and, on the whole, it appeared to be increased during sleep. Whenever the fluid, which constitutes the insensible transpiration, does not evaporate, owing to causes referred to at the commencement of this article, it appears on the surface in the form o'l sensible per sjnr a- tion or sweat. It has been supposed by some physiologists, that the insensible and sensible perspirations are two distinct functions. Such appears to be the opinion of Haller, and of M. Edwards, who regards the former as a physical evaporation^ — the latter as a vital transudation or secretion; but no sufficient reason seems to exist, why we should not regard them as different degrees of the same function. It has been maintained, indeed, by Mr. Eainey,^ as the results of careful histolo- gical inquir}^, that there are no glands but the sudoriparous in the integument of the hands and feet, and hence it is inferred by him, that these glands furnish the oily or sebaceous matter with which these parts are anointed; and in place of regarding the sweat as an increase of the insensible perspiration, he esteems it an increased secretion of glands, which, in their less active state, secrete sebaceous matter, and, in their more active, the fluid of transpiration. It has been affirmed, that the sweat is generally less charged with carbonic acid than the vapour of transpiration; and that it is richer in salts, which are deposited on the skin, and are sometimes seen in the form of white flocculi; but our knowledge on this matter is vague. There can be no doubt, however, that a large portion of the transpira- tion — pulmonary and cutaneous — consists of the fluid of evaporation, — the smaller portion, which is the true matter of perspiration, being the secretion of sudoriferous glands. To establish the amount of the fluids of evaporation and secretion, Krause^ endeavoured both to num- ' Proceerlincrs of the Royal Medical and Chirurgical Society, June 22, 1849, and London Med. Gaz., .July 20, 1849. ^ Art. Haut, in Wagner's Handworterbuch der Physiologic, 7te Lieferung, S. 108, Braunschweig, 1844. TRANSPIRATOKY, OF THE SKIN. 617 ber and measure these glands. On an average, lie says, in each super- ficial square inch of the body there are 1000 orifices and glands of ^th of a line in diameter; the greatest and least numbers in this space being, in the palm, 2736; in the sole, 2685; in the cheek, 548 ; in the neck, back, and nates, 417. The whole number, excluding the axilla, in which they are peculiarly large and thickset, is estimated at about 2,381,248. Adopting these numbers, and supposing each gland to be occupied by a column of fluid presenting at the orifice a hemispherical surface g'gth of a line in diameter — the size, which Krause found by admeasurement of some drops in a warm and moist, but not sweating skin — the whole of the glands would present an evaporating surface of 7896 square inches. Krause, therefore, considers it probable — ac- cording to ascertained laws of evaporation, and experiments instituted for the purpose — that only a portion of the fluid discharged by cuta- neous transpiration is furnished by these glands; inasmuch as there could not be more than 3365 grains evaporated in the twenty-four hours from such a surface under ftivourable circumstances, whereas the experiments of MM. Lavoisier and Seguin — as has been shown — gave an average of 11 grains per minute, or 15,840 grains in the twenty-four hours, — leaving 12,475 grains to be accounted for proba- bly by evaporation. But these are, of course, mere approximations to the truth. Careful examinations have been made by Valentin' on his own per- son, in regard to the amount of both cutaneous and pulmonary tran- spiration. Taking three days of ordinary life in September, weighing himself naked fifteen times a day, and all his ingesta and sensible ex- cretions, he found the averages of three days to be: — nutritive matter taken, 45325*5 grains; excrement, 2956*3 grains; urine, 22439*3 grains; perspiration, 19327*4 grains. The ingesta being as 1, the excrement was '065, the urine, *503 ; and the perspiration, *422. There were dif- ferences, however, in the days ; — in the first, the proportion of the in- gesta to the excretions was as 1*097 to 1 ; in the second, as 1*028 to 1 ; in the third, as 1 to 1*090. The hourl}^ amount of transpiration was occasionally 4| times as much as at others ; the greatest dift'erence being caused by whatever excited sweating, or perceptible moisture of the skin. For instance, on the same day, the hourly amount, after taking two cups of coffee, and during gentle perspiration, was 1213*65 grains; in the forenoon, in pretty active exercise and sweating, 1402*75 grains; and in the evening, during copious sweating from exercise, 2056*85 grains; but whilst writing quietly in the forenoon of the same day it fell to 858*7 grains, and three or four hours after dinner, it was only 509*95 grains. Nothing influenced the transpiration so much as rest and bodily exertion. Even when the latter did not produce manifest sweating, the effect was considerable. After eating, also, transpiration was generally increased, and its minimum was observed during fasting, and whilst at rest in a cool temperature. During the night and in sleep, the transpiration was diminished; but not more than in rest during the day. Mental exertion had no obvious in- fluence. ' Lelirbucli der Pliysiologie des Mensclieii, B. i. S. 582; and Krause, op. cit., S. 140. 518 SECRETIO^r, Particular parts of the body perspire more freely, and sweat more readily than others. The forehead, armpits, groins, hands, feet, &c., exhibit evidences of this most frequently ; some of them perhaps, owing to the fluid, when exhaled, not evaporating readily, — the contact of air being impeded. It is presumed, likewise, that the sweat has not every where the same composition. Its odour certainly varies in dif- ferent parts. In the armpits and feet it is generally considered to be more acid; but M. Donne^ affirms, that there, as well as around the genital organs and between the toes, and wherever it is most odorous, it is alkaline, restoring the blue of litmus paper which had been pre- viously reddened by an acid. He properly suggests, however, that this may be owing to admixture with the secretion of the follicles. In the violent sweats that accompany acute rheumatism, its acidity always attracts attention ; and in the groins, its odour is strong and rank. It diifers greatly, too, in individuals, and especially in races. In the red-haired, it is said to be unusually strong; and in the negro, during the heat of summer, alliaceous and overwhelming. By clean- liness, the red-haired can obviate the unpleasant effect in a great mea- sure by preventing undue accumulation in the axillae, groins, &c. ; but no ablution can remove the odour of the negro, although cleanliness detracts from its intensity. Each race appears to have its characteristic odour : and, according to Humboldt, the Peruvian Indian, whose smell is highly developed by education, can distinguish the European, Ame- rican Indian, and negro, in the middle of the night, by this sense alone. Certain anatomists and physiologists — as has been seen (p. 556) — have doubted, whether this special odorous matter of the skin belongs pro- perly to the perspiration, and have presumed it to be the product of special organs. This is, however, by no rneans established ; and the experiments of M. Thenard, as well as the facts just mentioned, would rather seem to show, that the matter of sweat itself has, within it, the peculiar odour. Simon,^ too, affirms, that on evaporating his own sweat, the peculiar smell of the axilla was observed, and an odour of ammonia was developed : and allusion has been made to the recent view of Mr. Rainey, that the same glands may in one condition of activity furnish the matter of transpiration, and in another the ordinary secretion of sebaceous follicles. The fact of the dog tracing its mas- ter to an immense distance, and discovering him in a crowd, has in- duced a belief, that the scent may be distinct from the sweat; but the supposition is not necessary, if we admit the matter of perspiration to be itself odorous. There can be no doubt, however, that certain odorous secretions are formed by cutaneous follicles. The singular fact has been stated, that by mixing fresh blood with one-third or one-half its bulk of strong sulphuric acid, and stirring the mixture with a glass rod, a peculiar odour is evolved, which ditfers in the blood of man and animals, and in the blood of the two sexes. This odour resembles that of the cutaneous perspiration of the animal. " They have hereby pretended to determine," says a modern medico- legal writer,^ " whether any given specimen of blood had belonged to ' Cours de Microscopie, p. 207, Paris, 1844. * Animal C'hemi.stry, Sydenham Society's edition, ii. 102. Lond., 184(). '^ Taylor, Medical Jurisprudence, Amer. edit., by Dr. Griffith, p. 275, Philad., 1845. TRANSPIKATORY, OF THE SKIIT. 519 a man, a woman, a horse, sheep, or fish. Others pretend, that they have been able to identify the blood of frogs and fleas!" The first person who directed attention to this point was M, Barruel ;^ who was of opinion that a knowledge of the fact might be important in a medico-legal relation, with the view of determining the source of spots of blood on linen for example; but even admitting the fact, as stated by MM. Barruel, Devergie,^ and others, it is obvious, that so much must depend upon the power of olfactory discrimination of the ob- server, that the evidence in any doubtful case could scarcely be deserving of much weight. Mr. Taylor, indeed, affirms, that there is probably not one individual among a thousand, whose sense of smell could be so acute as to allow him to state, with undeniable certainty, from what animal the unknown blood had really been taken. Besides the causes before referred to, the quantity of perspiration is greatly augmented by running or violent exertion of any kind ; es- pecially if the temperature of the air be elevated. The amount will vary, however, according to the cjuantity of moisture already present in the air. If it be slight, a large quantity will pass off in the form of insensible perspiration ; if the hygrometric conditioa be high, less will be exhaled in the insensible form, and more in the sensible. Experi- ments were made by Dr. Southwood Smith,^ on eight of the workmen, employed at the Phoenix Gas Works in drawing and charging the retorts and making up the fires. They were weighed in their clothes immediately before they began, and after they had finished their labour ; and in the interval between the first and second weighings they were not permitted to take any solids or liquids ; nor to pass urine or fajces. Two men on a bright clear day worked in an unusu- ally hot place for 70 minutes ; the loss of weight of one of them was 4 lbs. 1-i oz.; and of the other 5 lbs. 2 oz. Warm fluids favour perspiration greatly; hence their use, alone or combined with sudorifics, when this class of medicines is indicated. M. Magendie" conceives, that being readily absorbed they are readily exhaled. This may be true ; but the perspiration breaks out too rapidly to admit of this explanation. When ice-cold drinks are taken in hot weather, the cutaneous transpiration is instantaneously excited. The effect, consequently, must be produced by the refrigerant influ- ence of the cold medium on the lining membrane of the stomach, — this influence being propagated, by sympathy, to every part of the capillary system. The same explanation is applicable to warm drinks; but the hot exert a sympathetic efl'ect on the skin by virtue of their stimulant action on the mucous membrane. With regard to the uses of the insensible transpiration, it has been supposed to preserve the surface supple, and thus favour the exercise of touch ; and also, by undergoing evaporation, to aid in the refrigera- tion of the body. It is probable, however, that these are secondary uses under ordinary circumstances ; and that the great office performed by it is to remove a certain quantity of fluid from the blood: hence it has been properly termed the cutaneous de'imralion. In this respect, ' Annales d'Hygiene, i. 267. * Medecine Legale, 2de edit., iii. 761, Paris, 1S40. » Philosophy of Health, 11. 391-396. * Precis de Physiologie, 2de edit., ii. 455. 520 SECRETION it bears a striking analogy to the urine, wliicli is the only other depu- ratory secretion, with the exception of the piihiionary transpiration, which we shall find essentially resembles the cutaneous. Being depu- ratory, it has been conceived, that any interruption to transpiration must be followed by serious consequences ; accordingl}' most diseases have, from time to time, been ascribed to this cause. There is, how- ever, so great a compensation existing between the urinary and cuta- neous depurations, that if one be augmented, the other is decreased, — and conversely. Besides, it is well known, that disease is more apt to be induced by partial and irregular application of cold than by frigo- rific influences of a more general character. The Eussian vapour- bath exemplifies this; the bather frequently passing with impunity from a temperature of 130° into cold water. The morbific effect — in these cases of fancied check given to perspiration — is derangement of the apjtaratus engaged in the important functions of nutrition, calori- fication, and secretion, and the extension of this derangement to every part of the organism. As the sensible transpiration or stoeat is probably only the insensible perspiration in increased quantity, with the addition of saline, and other matters that are not evaporable, its uses demand no special notice. 2. Secretion of the Lachrymal Gland. The lachrymal apparatus, being a part of that accessory to vision, is described under another head. The tears, as we meet with them, are not simply the secretion of the lachrymal gland, but of the conjunctiva, and occasionally of the carun- cula lacrymalis and follicles of Meibomius. ~ It has been presumed, too, by several modern ophthalmologists — by Wardrop, Eosas, Jhng- ken, for example — that a portion of them — Eognetta' says the prin- cipal portion — consists of the aqueous humour, which passes through the cornea by endosmose ; but although such endosmose mat/ exist, it can assuredly furnish but little towards the composition of the tears.^ They have a saline taste ; mix freely with water ; and, owing to the presence of free soda, communicate a green tint to blue infusion of violets. Their chief salts are chloride of sodium, and phosphate of soda. According to MM. Fourcroy and Vauquelin,^ the animal matter of the tears is mucus ; but it is presumed, by some, to be albumen or an analogous principle — dacryolin. They found them to consist of water, mucus, chloride of sodium, soda, phosphate of lime and phos- phate of soda. The following is the result of analyses by Professor Frerichs:^ — I. II. Water, 99-06 98-70 Solid constituents, 0-94 1-30 ^ Epithelium, 0-14 0-32 Albumen, 0-08 0-10 Chloride of Sodium — Alkaline Phosphates, Earthy- Phosphates, Mucus, Fat, .... 0-72 0-88 ' Traite Philosophique et Clinique d'Ophthalmologie, p. 705, Paris, 1844, 2 Frerichs, Art. Thriinensecretion, in Wagner's Handwiirterbuch der Physiologie, 19te Lieferung, S. 621, Braunschweig, 1848. * Journal de Physique, xxxix. 256. ^ Op. cit., S. 618. OF THE SALIVARY GLANDS. 521 When tears are examined with the microscope, globules of mucus, and debris of the epidermis are seen in them. This secretion is more influenced by the emotions than any other ; and hence it is concerned in the expressions of lively joy or sorrow, especially the latter. 3. Secretion of the Salivary Glands. The salivary apparatus has likewise engaged attention elsewhere. It consists of a -parotid gland on each side, situate in front of the ear, and ])ehiud the neck and ramus of the jaw; a submaxillarrj, beneath the body of the bone; a sublingual^ situ- ate immediately beneath the tongue ; — and an intralingual or lingual^ seated at the inferior surface of the tongue ; — the parotids and submax- illary glands having each but one excretory duct, — the sublingual se- veral.-^ The racemose granular struc- ture of the salivary glands in man greatly resembles that of the mam- mary glands. The marginal figure exhibits their structure in the sheep. All these glands pour their respect- ive fluids into the mouth, where it collects, and becomes mixed with the exhalation of the mucous mem- brane of the mouth, and the secre- tion from its follicles. It is this mixed fluid that has generally been analyzed by the chemist. When collected without the action of suck- ing, it is of a specific gravity varying from 1*004 to 1*009 ; accord- ing to Mitscherlich, from l-b061 to 1-0088. In the dog, Prof. Ber- nard^ found that of the parotid to be from 1"0036 to 1*0011, whilst Jacubowitsch noted it in the same animal from 1*0010 to 1*0017. In the horse, Lehmann^ found it to be from 1*0051 to 1*0071. It is trans- lucent ; slightly opaque ; very frothy ; and ultimately deposits a ne- bulous sediment. Even in the purest saliva there are always found )nixed a few epithelial cells, derived from the mucous lining of the mouth, or from the excretory ducts of the secreting glands. It usually contains free alkali : in rare cases, during meals. Professor Schultz,* of Berlin, found it acid; and during fasting, it is occasionally neutral. iMitscherlich,^ indeed, affirms, that it is acid whilst fasting ; but becomes alkaline during eating, — the alkaline character disappearing, at times, ' Page 77. 2 Gazette Med., 1853, No. 7, 11, 22 and 23 ; and Scherer, in Canstatt's Jaliresbericht, 1853, S. 118. * Lehrbuch der Physiologisclien Chemie, ii. 14, Leipz., 1850 ; or Amer. edit, of Dr. Day's translation by Dr. R. E. Rogers, i. 415, Philad., 1855. ■• Becker's Wissenschaftliclie Annalen, B. ii. H. i. § 32, 1835. ^ Rullier and Raige-Delorme, art. Digestion, Diet, de Medecine, 2de edit., x. 300, Paris, 1835. Lobules of the Parotid Gland, in the Em- bryo of the Sheep. 522 SECRETION" witli tlie first moutliful of food. The average amount of the secretion in the twenty-four hours has not been considered to exceed four ounces. Messrs. Bidder and Schmidt/ however, estimate the probable amount for an adult at 140 kilogramme or between three and four pounds in the twenty-four hours. According to Berzelius,^ its constituents are — water, 992'2 ; peculiar animal matter, 2*9 ; mucus, I'-i ; chlorides of potassium and sodium, 1'7 ; lactate of soda, and animal matter, 0"9 ; soda, 0*2. Di's. Bostock^ and Thomas Thomson" think that the "mucus" of Berzelius resembles coagulated albumen in its properties. In the tartar of the teeth, which seems to be a sediment from the saliva, Berzelius found 79 parts of earthy phosphate; 12*5 of undecomposed mucus; 1 part of a matter peculiar to the saliva, and 7'8 of an animal matter soluble in chlorohydric acid. This animal matter, according to the microscopic experiments of M. Raspail,* is composed of deciduous fragments from the mucous membrane of the cavity of the mouth; and he considers, that the saliva is nothing more than an albuminous solution, mixed with different salts, that are capable of modifying more or less its solubility in water, and of shreds or layers of tissue. MM. Leuret and Las- saigne*^ analyzed p?■ ...... . 5*509 " iron, J Still more recently, human saliva has been analyzed by Jacubowitsch'^ and found to be composed as follows : — Water, 999*16 Fixed residue, .......... 4*84 Epithelium, .......... 1*62 Organic matters, ......... 1*34 Sulphocyanide of potassium, ....... 0*06 Salts, 1*82 The salts consisted of phosphate of soda, 0"91:; lime, 0"03; magnesia, O'Ol; chlorides of potassium and sodium, 0*81.^ M. Lassaignc^ examined the secretion from the parotid gland; and that from the submaxillary of the same animal. Both were transparent fluids, and possessed a slight alkaline reaction. That of the submax- illary was more viscid, and similar to mucus in consistence. The fol- lowing was the quantitative analysis of the two. That of the parotid of the cow contained water, 990*74; mucus and soluble organic matters, 0*1:4; alkaline carbonates, 3'38 ; alkaline chlorides, 2'S5 ; alkaline phosphates, 2"49; phosphate of lime, 0*10. That of the sub- maxillary contained water, 991'14; mucus, 1"73; soluble animal mat- ters, 1'80; alkaline carbonates, 0*10; alkaline chlorides, 5*02; alkaline phosphate, O'lo; phosphate of lime, O'OB.* Messrs, Tiedemann and Gmelin, and M, Donne," found the saliva invariably alkaline, when the functions of the stomach were well executed. The last gentleman considered acidity of the saliva a diagnostic symptom of gastritis; and Dr, Eobt. Thomson^ observed the acid reaction in all cases of inflammation of the mucous and serous ' Annalen der Chemie und Pharmacie, Marz., 1844. 2 De Saliva, Dissert, inaugur, Med. Univers. Dorpatens. ; cited by Scherer, in Can- statt and Eisenmaun's .Jahresbericlit iiber die Forstchritte der Biologie im Jahre 1848, Erlang., 1849, ^ Gr, Owen Rees, Art, Saliva, in Cyclop, of Anat. and Physiol., iv, 415, Lond,, 1852. '• Journal de Chimie Medicale, p. 393 ; and Scherer, in Canstatt's Jahresbericht, S. 106, 1852, ^ See on the whole subject of the Saliva, Bidder & Schmidt, Die Verdauungssafte u. s. w, S, 1, Mitau und Leipzic, 1852. ** Archives Ui uerales, Mai & Juin, 1835 ; and Histoire Physiologique et Pathologique de la Salive, Paris, 1836. ' Ilecords of General Science, Dec, 1836. 524 SECRETION membranes. With the view of testing these points, Mr. Laycock* instituted numerous experiments, and tabulated the results of no less than 567 observations. His deductions do not accord with those of M. Donne. They are as follows : — 1. The saliva may be acid witliout apparent disease of the stomach, and when the person is in good health. 2. It is alkaline during difl'erent degrees of gastric derangement, as indicated by the tongue. 3. It may be alkaline, acid and neutral, when the gastric phenomena are the same; and, consequently, acidity of the saliva is not a diagnostic mark of gastric derangement ; and, lastly, in general it is alkaline in the morning, and acid in the evening. In a more recent work M. Donne^ accounts for the varying testimony of different observers in regard to the chemical reaction of the saliva, by the greater or less proportion of the mucus of the mouth contained in the specimens subjected to examination. In the normal state, he affirms, it is alkaline; but the mucus secreted by the mucous mem- brane of the mouth being acid, the mixed fluid, to which the name saliva is given, must necessarily vary according to the proportion of each. When saliva is examined by the microscope, it presents, besides a considerable number of lamelhe of epithelium, globules in variable quantity, which, according to M. Mandl,^ proceed partly from the mu- ciparous glands of the mouth, and partly from the salivary glands. They cannot, however, be distinguished from each other. As the salivary secretion forms a part in the processes preparatory to stomachal digestion, its uses have been detailed in the first volume of this work, to which the reader is referred. The view of MM. Ber- nard and Barreswil, and of Mialhe, that the saliva contains an active principle, analogous in its physical and chemical characters to diastase, as well as* its action on amylaceous substances, is there described. A soft, whitish or yellowish matter, of greater or less thickness, is constantly deposited on the teeth, which, unless attention is paid, ac- cumulates, and sometimes adheres to them with great force, constitut- ing hard and dry concretions, known — as already remarked — under the name of tartar or tartar of the teeth. Different views have existed in regard to its origin. Some have supposed it to be a secretion, others a deposition from the saliva, which is the most probable opinion ; and others that it is an exhalation from the capillary vessels, to which the mucous membi'ane of diseased gums is liable. It has been affirmed by ]\r. Mandl** to be a collection of calcareous skeletons of infusoria, agglutinated by means of dried mucus. 4. Secretion of the Pancreas. The -pancreas or sweetbread, (Fig- 1^5, A, t, ?',) secretes a juice or hu- mour called succus j^ci^^creaticus, 2)ancreatic juice. Its texture resembles that of the salivary glands ; and hence it has been called by some the abdominal salivary gland. It is situate transversel}' in the abdomen; ' Lond. Med. Gazette, Oct. 7, 1S37. See, for a detailed account of tlie saliva, Dr. S. Wright, op. cit. 2 Cours de Microscopie, p. 208, Paris, 1844. ^ Manuel d'Anatomie Generale, p. 488, Paris, 1843. * Gazette des Hopitaux, 8 Aoiit, 1843, p. 3tJ3. OF THE PANCREAS. 525 behind tlie stomach ; towards the concavit}^ of the duodenum ; is about six inches in length, and between three and four ounces in weight. From the results of SIX examinations, Dr. Gross' gives the following as its mean weight and dimen- sions : — Weight 2|- ounces; length, 7 inches; breadth at the body and splenic extremity, 16 J lines; breadth at the neck, 12 lines; at the head, 2 inches and 8 lines; thickness at the body, neck, and splenic extremity, 4 lines ; thickness at the head, 8 lines. M. Becourt found the average length Fig. 155. In this figure, which is altered from Tiedemann, the Liver and Stomach are turned up to show the Duodenum, the Pancreas, and the Spleen. I. The under surface of the liver, .cr. Gall-bladder. /. The common f\P tliir+tT- fnr/-v +rk \^a ^^le-duct, formed by the union of a duct from the gall-bladder, called Ol iniliy-lWO lO Oe the cystic duct, and of the hepatic duct coming from the liver, o. The cardiac end of the stomach, where the oesophagus enters, s. Under surface of the stomach, p. Pyloric end of stomach, d. DuDdenum. h. Head of pancreas ; (, tail ; and i, body of that gland. The sub.stance of the pancreas is removed in front, to show the pancreatic duct (e) and its branches, r. The spleen, v. The hilus, at which the bloodvessels enter. c. Crura of diaphragm. 71. Superior mesenteric artery, a. Aorta. 8 inches; and the weight between 3 and 4 ounces.^ It is of a reddish-white colour, and firm con- sistence. Its excretory ducts terminate in one, — called duct of Wir- sung, — which opens into the duodenum, at times separately from the ductus communis choledochus, but close to it; at others, confounded with, or opening into, it.^ In the rabbit it opens several inches — 35 centimetres — below it. According to M. Beraud-* there are at all times two pancreatic ducts — the larger that already mentioned; the smaller proceeding from the summit of the head of the gland, and opening into the duodenum above the choledoch duct in man. This fact — he says — has been demonstrated by his own researches, as well as by those of M.Bernard, and is seen in the preparations in the museum of the ^'•Ecole de Iledecine,^^ made by MM. Verneuil, Boulard, Fano and himself. The amount of fluid secreted by the pancreas does not seem to be considerable. M. Magendie, in his experiments, was struck with the small quantity discharged. Frequently, scarcely a drop issued in half an hour; and, occasionally, a much longer time elapsed. Nor did he find that the flow, according to common opinion, and to probability, was more rapid whilst digestion was going on. It will be readily * Elements of Pathological Anatomy, ii. 357, Boston, 1839. * Recherches sur le Pancroas, ses Fonctions et ses Alterations Organiques, Tliese Strasbourg, 1830, cited by Mondiere, Archives (K'norales de Medecine, Mai, 1836. * Magendie, Precis Jib mentaire, i. 462; and .J. P. Mondiere, op. cit. * Manuel de Physiologie de rHomrae, p. 173, Paris, 1853. 526 SECRETION understood, therefore, that it cannot be an easy task to collect it. De Graaf^ affirms, that he succeeded, by introducing into the intestinal end of the excretory duct a small quill, terminating in a phial fixed under the belly of the animal. M. Magendie^ states, that he tried this plan several times, but without success; and he believes it to be im- practicable. The plan he adopts is to expose the intestinal orifice of the duct; to wipe the surrounding mucous membrane with a fine cloth, and as soon as a drop of the fluid oozes to suck it up by means of a "pipette or small glass tube. In this way, he collected a few drops, but never sufficient to undertake a satisfactory analysis. Messrs. Tiede- mann and Gmelin^ made an incision into the abdomen; drew out the duodenum, and a part of the pancreas; and, opening the excretory duct, inserted a tube into it; and a similar plan was adopted successfully on a horse by MM. Leuret and Lassaigne.'' M. Bernard's plan is to make an incision into the right hypochondrium, draw out the duode- num with a part of the pancreas, pass a double ligature around the duct, and fix into it a silver tube, the extremity of which, outside the abdomen, is attached to a small India-rubber bag, into which the fluid flows in large pearl-shaped drops.-' The difficulty experienced in collecting any quantity is a probable cause of some of the discrepancy amongst observers, regarding its sen- sible and chemical properties. Certain of the older physiologists affirm that it is acidulous and saline; others, that it is alkaline.** The majority of those of the present day compare it with saliva, and affirm it to be inodorous, insipid, viscid, limpid, and of a bluish white colour. The latest experimenters by no means agree with each other. According to ]\L Magendie, it is of a slightly yellowish hue, saline taste, devoid of smell, occasionally alkaline, and partly coagulable by heat. MM. Leuret and Lassaigne found that of the horse — of which they obtained three ounces, — to be alkaline, and composed of 991 parts of water in 1000; an animal matter, soluble in alcohol; another, soluble in water; traces of albumen and mucus; free soda; chloride of sodium; chloride of potassium; and phosphate of lime. In their view, consequently, the pancreatic juice strongly resembles saliva. Messrs. Tiedemann and Gmelin succeeded in obtaining upwards of two drachms of the juice in four hours; and, in 100 parts, found from five to eight of solid parts. These consisted of osmazome; a matter which became red by chlorine; another analogous to casein, and probably associated with salivary matter ; much albumen ; a little free acid, probably acetic ; acetate, phosphate, and sulphate of soda, with a little potassa; chloride of potas- sium, and carbonate and phosphate of lime; — so that, according to these gentlemen, the pancreatic juice differs from saliva in containing a little free acid, whilst saliva is alkaline; much albumen, and matter resembling casein ; but little mucus and salivary matter, and no sulpho- cyanate of potassa. In an examination by M. Bloudlot' of three or ' Tract, de Pancreat., Ludg. Bat., 17(31; and Haller, Elem. PlijsioL, lib. xxii. sect. S. Bern., 17v>^ •,^',«v^ ■!■■ 'Mb It is from this arrangement of the bloodvessels and biliary ducts, that Mr. Kiernan infers that bile must be secreted from the portal vessels; — the intralobular ramifications of the hepatic veins conveying back to the heart the blood which has been inservient to the secretion. The views of Mr. Kiernan have Fig. 160. been generally adopted by ana- .^2 2 .. tomists. Wagner, however, whilst he resjards the beautiful figures and descriptions of Mr. Kiernan as the best he has seen, asserts, that they very certainly also include many mistakes; Avhilst Krause "combats the views of Kiernan. holding them to be hypothetical;''' and E. H. Weber-^and Krukenberg oppose them. The chief point, accord- ing to Mr. Paget, in which these gentlemen difter from Mr. Kiernan, is in denying that the component parts of the liver are ar- ranged in lobules. They, with Henle and Mr. Bowman, describe the capillary networks as solid, — that is as extending uniformly through the liver. They, also, deny the existence of fibro-cellular partitions dividing the liver into lobules as maintained by Mr. Kiernan and J. Miiller;^ and even the existence of more fibro-areolar tissue than serves to invest the larger vessels, &c., of the organ. They likewise deny ' Wagner, Elements of Phvsioloev, by R. Willis, § 195, Loud., 1842. 2 Miiller's Arcliiv., 1844, Heft 3 and 4. =» Ibid. .j^^ Horizontal Section of two Superficial Lobules, showing Interlobular Plexus of Biliary Ducts. OF THE LIVER. 531 that there are an}^ such interlobuLar veins and fissures as Mr. Kiernan describes, and state, that the smaller branches of these veins commu- nicate by branches only just larger, if at all larger, than capillaries.' Fig. 161. Fig. 162. .<^^ \j:j: A small portion of a Lobulo highly magnified. The secreting cells are seen witbin the tubes, and in the interspaces of the latter the fibrous tissue is repre- sented. Portion of a Biliar}' Tube, from a fresh Human Liver, very highly magnified. The secreting cells may be noticed to he polygonal from mutual pressure. Histologically considered, the liver may be regarded as consisting ^ of ramifications of excretory Fig. 163. ducts, surrounded by bloodves- sels, which aftbrd the materials for secretion, — and of cells which elaborate it, but as respects the precise arrangement of the cells Fig. 164. ■^^^ -i Transverse section of a Lobule of the Human Liver, Showing the reticular arrangomont of its parenchy- ma, with some of the branches of the hepatic vein in the centre, and those of the portal vein at the peri- pliery. Hepatic Cells gorged with Fat. a. Atrophied nucleus, b. Adipose globules. anatomists are not wholly in ac- cordance. Dr. Leidy^ affirms, that they line the inner surface of the tubuli that form the biliary plexus of Kiernan ; that they are irregularly angular or of a poly- gonal shape, owing to their pressing upon each other ; and contain a fine granular matter, oil giotjules, a granular nucleus and transparent nucleolus, — the oil globules, under special circumstances of diet and ' See, on all this subject, Professor Tlieile, art. Leber, Wagner's ILindworterbuch der Fhysiologie, 9te Lieferung, S. 308, Braunschweig, 1845. ^ American Journal of tlie Medical Sciences, p. 1, Jan., 184S ; and Quain's edition of Quain and Sharpey's Human Anatomy, ii. 487, Philad., 1849. 582 SECRETION" disease, experiencins; considerable increase. Dr. C. Hand field Joues^ lias, however, maintained, that the raiiiitications of the hepatic ducts Fi£T. 165. i%k»tu Minute Portal and Hepatic Veins and Capillaries. a, a. Twigs of the portal vein. d. Twig of the hepatic vein. b. latermediate capillaries. Fig. 166. Diagram of the arrangement of the cellular parenchyma, 5, 6, of the human liver, with reference to tlie radicle.s of the interlobular ducts, ortions. C. Intra- E. Con- lobules; F, nncongested portions. Iii Fig. 170, the lobules are in a state of iJorUd venous congestion; not a common occurrence. It lias been seen by Mr. Kiernan in children only. The view of Mr. Kiernan has been held to explain also the diver- sity of the statement of anatomists as to the relative position of the o-ed and yellow substances, which have been considered to compose the liver : the red is the congested portion of the lobules, whilst the yellow is the non-congested portion in which the biliary plexus appears more or less distinctly. The liver has two coats; — the outer, derived from the peritoneum, which is very thin, transparent, easily lacerable, and vascular, and is the seat of the secretion effected by serous membranes in general. It docs not cover the posterior part, or the excavation for the gall-blad- der, the vena cava, or the fissures in the concave surface of the liver. The inner coat is the proper membrane of the liver. It is thin,^ but not easily torn, and covers not only every part of the surface of the liver, but the large vessels that are proper to the organ. The condensed areolar sub- stance, — which unites the sinus of the vena porta and its two great branches, the hepatic artery, common bili- ary duct, lymphatic glands, lymphatic vessels, and nerves in the transverse fossa or fis- sure of the liver, — was de- scribed by Glisson as a cap- sule ; and hence has been called capsule of Glisson. It connects the various anato- mical elements of the liver together. The (jall-hl adder is a small membranous pouch of a py- riform shape, situate at the inferior and concave surface of the liver to which it is attached; and above thy co- lon and duodenum. A quan- tity of bile is usually found in it. It is not met with in all animals*, is wanting in the elephant, horse, stag, camel, rhinoceros, and goat ; Fig. 171. The three coats of Gall-bladtler separated from each other. 1. External or peritoneal coat. 2. Areolar coat ■«-ith its vessels injected. 3. SIucuus coat covered with wrinkles. ■t, 4. Valves, formed by tliis coat in the neck of gall-bladder. 5, ;j. Orifices of mucous follicles at this point. 536 SECRETION Fig. 172. Gall-bladder distended with Air, and with its Vessels injected. 1. Cystic arterr. 2. Branches of it which supply the peritoneal coat of the liver. 3. Branch of the hepatic ar- tery which goes to gall-bladder. 4. Lymphatics of gall- bladder. in certain of the cetacea ; in some birds, as the ostrich, pigeon, and parrot; and is occasionally so in man. Xo traces of it are met with in the invertebrata. It may be looked upon as a dilata- tion of the gall -ducts, and adapted for the reception and retention of bile. Its largest yjart or fundus is turned forwards: and, when filled, frequently projects beyond the anterior margin of the liver. Its narrowest portion, cervix or neck, is turned backwards, and ter- minates in the cystic duct. Externally, it is partly co- vered by the peritoneum, which attaches it to the liver, and to which it is, moreover, adherent by areolar tissue and ves- sels. Internally, it is rugous; the folds being reticulated, and appear- ing somewhat like the cells of a honeycomb. Anatomists have differed with regard to the number of coats proper to the gall-bladder. Some have described two only ; — the peritoneal and mucous; others have added an intermediate areolar coat; whilst others have reckoned four; — a peritoneal, — a thin stratum of muscular fibres passing in different directions, and of a pale colour, — an areolar coat, in which a number of bloodvessels is situate, and an internal mucous coat. The existence of the muscular coat has been denied by perhaps the generality of anatomists; but there is reason for believing in its existence. Kcilliker^ affirms, that there is, between its peritoneal covering and the abundant subserous connective tissue, a delicate layer of muscles, whose fibre cells take more particularly a longitudinal and a transverse direction and present only indistinct nuclei. Amussat saw muscular fibres distinctly in a gall-bladder dilated by calculi; and Dr. Monro (Tertius),^ Professor of Anatomy in the University of Edin- burgh, asserts, that he has seen it contract, in a living animal, for half an hour, under mechanical irritation, and assume the shape of an hour- glass. The mucous coat forms the rugge to which we have already alluded. In the neck, and beginning of the cystic duct, there are from three to seven — sometimes twelve — semilunar duplicatures, which re- tard the flow of au}^ fluids inwards or outwards. These are sometimes arranged spirally, so as to f(jrm a kind of valve, according to M. Amussat.^ On the inner surface of the gall-bladder, especially near its neck, numerous follicles exist, the secretion from which is said to fill the gall-bladder, when that of the bile has been interrupted by disease, as in yellow-fever, scirrhus of the liver, &c. The hepatic duct is the coin- ' Miki'oskopiselie Anatomie, ii. 230, Leipzig, 1852 ; and Amer. edit, by Dr. Da Costa, p. 538, Philad., 1854. * Elements of the Anatomy of the Human Body, Edinb., 1825. ^ Mageudie, Precis, &c,, ii. 4li4. OF THE LIVER. 537 mon trunk of all the excretory vessels of tLe liver ; and makes its exit from that organ by the transverse fissure. It is an inch and a half in length, and about the diameter of an ordinary writing-quill. It is joined, at a very acute angle, by the duct from the gall bladder — q/stic dud — to form the ductus communis choledochus. The cystic duct is about the same length as the hepatic. The ductus communis choledochus is about three, or three and a half inches long. It descends behind the right extremity of the pancreas, through its substance; passes for an inch obliquely between the coats of the duodenum, dimi- nishing in diameter; and ultimately terminates by a yet more con- tracted orifice on the inner surface of the intestine, at the distance of three or four inches from the stomach. The structure of all these ducts is the same. The external coat is thick, dense, strong, and gene- rally supposed to be of an areolar character ; the inner is a mucous membrane, like that which lines the gall-bladder. A fibrous and a mucous layer, according to Kolliker,^ can be readily distinguished in the ductus communis choledochus and the cystic duct; the mucous layer containing a few muscular fibre-cells; but, on the whole, so sparingly, that these ducts cannot — he considers — be said to possess any special muscular coat. The secretion of bile is probably effected like that of other glandular organs; modified, of course, by the peculiar structure of the liver. We have seen, that the organ differs from every other secretory appa- ratus, in having two kinds of blood distributed to it ; — arterial by the hepatic artery ; and venous by the vena porta. A question has con- sequently arisen — from which of these is the bile formed? Anato- mical inspection does not positively settle the question; for whilst — as has been seen — it is maintained by Muller and others, that the ulti- mate termination of the capillaries is in the hepatic veins; others, with Kiernan, believe that they communicate with the portal system; and if this arrangement were demonstrated, we should be compelled to ascribe the secretion to the mixed blood, which flows in the inter- lobular veins. But this point of hepatic histology is not determined. Argument is all that can be adduced on one side or the other. The most common and the oldest opinion is, that the bile is separated from the blood of the vena porta ; and the chief reasons brought forward in favour of the belief, are the following: First. The blood of the por- tal sj^stem is better adapted than arterial blood for the formation of bile, on account of its having, like all venous blood, more carbon and hydrogen, which are necessary for the production of a humour as fat and oily as the bile; and, as the experiments of Schultz^ and others have proved, that portal blood contains more fat than that of other veins and arteries, it has been imagined, by some, that the blood, in crossing the omentum, becomes loaded with fat. Secondly. The vena porta ramifies in the liver after the manner of an artery, and evidently communicates with the secretory ves-sels of the bile, lliirdlij. It is larger than the hepatic artery ; and more in proportion to the size of the liver; the hepatic artery seeming to be merely for the nutrition of the liver, as the bronchial artery is for that of the lung. ' Op. cit. ^ Rust's Magazine, B. xliv. ; or Gazette Medicale, Aug. 15, 1835. 538 SECRETIOX In answer to these positions, it has been argned. First. That there seems to be no more reason why the bile should be formed from venous blood than other fatty and oleaginous humours, — marrow and f;it for example, — which are derived from arterial blood. It is asked, too, whether, in point of fact, the blood of the vena porta is more rich in carbon and hydrogen? and whether there be a closer chemical relation between bile and tlie blood of the vena porta, than between fat and. arterial blood ? Tlie notion of the absorption of fat from the omentum, it is properly urged, is totally gratuitous. Secondly. The vena porta does not exist in the invertebrated animals; and yet, in a number of them, there is an hepatic apparatus, and a secretion of bile. TJiirdly. Admitting that the vena porta is distributed to the liver after the manner of an artery ; is it clear, it has been asked, that it is inservient to the biliary secretion? Fourthly. If the vena porta be more in pro- portion to the size of the liver than the hepatic artery, the latter ap- pears to bear a better ratio to the quantity of bile secreted: and, Lastly. It is clear, as has been shown in another place, that the liver has other important functions connected with the portal system, as the admixture of heterogeneous liquids absorbed from the intestinal canal, and their assimilation. In the absence of accurate knowledge derived from direct experi- ment, physiologists have usually embraced one or other of these exclu- sive views. The generality, as we have remarked, assign the function tt5 the vena porta. Bichat, J. Miiller, and others, ascribe it to the hepatic artery. M. Broussais^ thinks it probable, that the blood of the vena porta is not foreign to the formation of bile, since it is confounded with that of the hepatic artery in the parenchyma of the liver; "but to say with the older writers, that the bile can only be formed from venous blood, is, in our opinion," he remarks, "to advance too bold a position, since the hepatic arteries send branches to each of the gland- ular acini, that compose the liver." M. Magendie likewise concludes, that nothing militates against tlie idea of both kinds of blood partici- pating in the secretion; and that it is supported by anatomy, as injec- tions prove, that all the vessels of the liver, — arterial, venous, lymphatic, and excretory, — communicate with each other. Mr. Kiernan, as we have seen, considers that the blood of the hepatic artery, after having nourished the liver, is inservient to the secretion, but not until it has become venous, and entered the portal veins. He, — with all those that coincide v/ith him in the morphological arrangement of the liver, — denies that there is any communication between the ducts and blood- vessels; and asserts, that if injections pass between them, it is owing to the rupture of the coats of the vessels. Experiments on pigeons, by M. Simon,^ of Metz, showed, that when the hepatic artery was tied, the secretion of bile continued, but that if the portal and hepatic veins were tied, no trace of bile was subsequently found in the liver. It would thence appear, that in these animals the secretion of bile takes place from venous blood. But inferences from the ligature of those vessels have been very discordant. In two cases, in which ]Mr. Phillips ' Traite de Phj'siologie, &:c., translation by Drs. Bell and La Roche, 3d edit., p. 45(5, Philad.. 1832. ^ Edinburgh Medical and Surgical Journal, xc. 229. OF THE LIVEE. 539 tied the hepatic artery, the secretion of bile was uiiinterru]:)tecl, jct the same thing was observed in three other cases, in which the ligature was applied to the trunk of the vena porta. The view, that ascribes the bile to the hepatic artery, has always appeared to the author the most probable. It has all analogy in its favour. There has been no disputed origin as regards the other secre- tions, excepting, of late, in the case of the urinary. All proceed from arterial blood ; and function sufficient, we have seen, can be assigned to the portal system, without conceiving it to be concerned in the formation of bile. We have, moreover, morbid cases, which would seem to show that bile can be formed from the blood of the hepatic artery. Mr. Abernethy^ met with an instance, in which the trunk of the vena porta terminated in the vena cava; yet bile was found in the biliary ducts. A similar case is given by Mr. Lawrence f and Professor Monro^ details a case communicated to him by the late Mr, Wilson, then of the Windmill Street School, in which there was reason to suppose, that the greater part of the bile had been derived from the hepatic artery. The patient, a female, thirteen years old, died from the effects of an injury of the head. On dissection, Mr. Wilson found a large swelling at the root of the mesentery, consisting of several absorbent glands in a scrofulous state. Upon cutting into the mass, he acci- dentally observed a large vein passing directly from it into the vena cava inferior, which, on dissection, proved to be the vena porta; and on tracing the vessels entering into it, one proved to be the inferior mesenteric vein: and another, which came directly to meet it, from behind the stomach, proved to be a branch of the splenic vein, but somewhat larger, which ran upwards by the side of the vena cava in- ferior, and entered that vein immediately before it passes behind the liver. Mr. Wilson traced the branches of the trunk of the vessel cor- responding to the vena porta sufliciently far in the mesentery and mesocolon to be convinced, that it was the only vessel that returned the blood from the small intestines, and from the c^cum and colon of the large intestines. lie could trace no vein passing into the liver at the cavity of the porta ; but a small one descended from the little epiploon, and soon joined one of the larger branches of the splenic vein. The hepatic artery came off in a distinct trunk from the aorta, and ran directly to the liver. It was much larger than usual. The greater size of the hepatic artery, in this case, would favour the idea, that the arterial blood had to execute some office, that ordinarily be- longs to the vena porta. Was this the formation of bile? The case seems, too, to show, that bile can be formed from the blood of the hepatic artery. Professor Gintrac" has published a case in which there was ossifica- tion with obliteration of the vena porta. The patient died of ascites. The liver was pale or whitish, and irregularly wrinkled or mammil- lated on its surface. The gall-bladder contained a medium quantity of thickish yellow bile. The biliary ducts were normal. The vena porta ' PhiLisopliical Transactions, vol. Ixxxiii. 2 Medico-Cliirurgical Transactions, iv. 174. ^ Elements of Anatomy, Edinliurizli, 1825. * Citetl iu American .Journal of tlie Medical Sciences, Oct., 1844, p. 47u. 540 SECRETION" above the junction of the splenic and superior mesenteric veins was completely filled bj an old clot, which adhered to the inner membrane. The clot was solid, and of a deepish black colour. At the same part of the vein several osseous plates were observed many lines in diame- ter, which were situate between the inner and middle coats of the vein, without having much adherence to either. All the abdominal veins that ended in these vessels were gorged with blood, and varicose. Professor Gintrac ascribed the ascites to the obliteration and ossification of the vena porta, and he considered the case to prove, that although oblite- ration of that vessel probably modified the secretion of bile, it did not prevent it altogether; but interfered materially with the nutrition of the liver. Hence, he inferred, that the blood of the vena porta contributes to the nutrition of the liver; but is not indispensable to the secretion of bile. In Professor HaH's patient,* the vena porta and its bifurcation were completely filled with encephaloid matter, so that no blood could pass through it to the liver; the secretion of bile could not, consequently, have been etYected through its agency. It lias been presumed, however, that, in such cases, portal blood might still enter the liver through the extensive anastomoses, which Professor Ketzius,^ of Stockholm, found to exist between the abdominal veins. That gentleman observed, when he tied the vena porta near the liver, and threw a coloured injection into the portion below the ligature, that branches were filled, some of which, proceeding from the duodenum, terminated in the vena cava ; whilst others, arising from the colon, terminated in the left emulgent vein. In subsequent investigations, he observed an extensive plexus of minute veins ramifying in the areolar tissue on the outer surface of the peritoneum, part of which was connected with the vena porta, whilst the other terminated in the system of the vena cava. In a successful injection, these veins were seen anastomosing very freely in the pos- terior part of the abdomen, with the colic veins, as well as with those of the kidneys, pelvis, and even the vena cava. The arrangement, pointed out by Retzius, accounts for the mode in which the blood of the abdominal venous system reaches the cava, when the vena porta is obliterated from any cause; and it shows the possibility of portal blood reaching the liver so as to be inservient to the biliary secretion, but does not, we think, exhibit the prohabi lily . Since then, cases of obliteration of the vena porta have been re- corded, in which the nutrition of the liver was materially impaired, so that the organ had become atrophied, whilst the secretion of bile per- sisted. Such a case is given by M. Eaikem,^ of Brussels. In this, the vein was entirely obliterated by clots of blood intimately adherent to its inner surface. The liver was smaller than usual; the gall-bladder contained a large quantity of serous bile of a yellowish and orange colour, and the cystic and hepatic ducts were filled with it. The trunk of the hepatic artery was three lines in diameter, and contained no clots ' Page 528. 2 Ais Berilttelse af Setterblad, 1S35, S. 9 ; cited in Zeitschrift fiir die Gesammte Heilkiuide, Feb., 1837, S. 251. ^ ]\leiiioires de I'Acadi uiie Royale de Medecine de Belsriqne, torn, i., Bruxelles, 1848; translated in tlie Ediub. Med. and iSurg. Journal, Ajjnl, isuU, p. 350. OF THE LIVER. 541 of blood ; and such was the case with the supra-hepatic veins. Whence j\f, Raikem concludes, that in the present state of physiological know- ledge, there are reasons sufficiently conclusive for the opinion, that the hepatic artery is capable alone of furnishing to the liver the materials necessary for the secretion of bile, when the vena porta is obliterated to so great a degree as not to allow the blood to be conveyed through it to the organ; and, he asks, as the result of observations of numerous pathological cases, whether "it is indeed proved, as is generally be- lieved, that tlie hepatic artery is alone charged with the function of nourishing the liver to the exclusion of the portal vein," when " we observe that the liver is atrophied, in those in whom the portal vein has been entirely obliterated for a long time?" An additional case of the kind has been detailed by Dr. Craigie.' In this, the vein was found completely filled and distended by firm, yet compressible, elastic matter, as if the vessel had been injected, so that its diameter was fully one inch. Of the effects of this obliteration, the most remarkable,, again, was the atro]ihy of the liver, which was not more than one-third of its usual size. A small quantity of light coloured bile was found in the gall-bladder, and during life the fasces had ithe usual colour. "M. Eaikem," says Dr. Craigie, " has adverted to the notion so much favoured, by various physiological speculators, that thediepatic artery is employed in maintaining the nutrition of the liver, while to the portal vein be- longs the function of conveying to the gland the materials from which bile is to be prepared; and, to show its incompetency, has adduced several conclusive arguments. It is scarcely possible to conceive a stronger argument against it than is furnished by the facts of this case. The portal vein was completely obstructed, and no blood must for a long time have been conveyed through its branches into the gland. The liver is likewise very much reduced in size, not, indeed, uniformly and equally in all its parts, but still so much and so generally atrophied,, that it is difficult to ascribe the diminution and wasting of parts to any other cause. The two circumstances, therefore, appear to stand in the relation of cause and effect." It is to be regretted that the history of this case is rendered imperfect by the circumstance, that " the state of the hepatic artery was not ascertained." It would seem, then, that the portal system is not absolutely neces- sary to the formation of bile; yet a modern writer^ considers it "a most puerile question" to ask whether the secretion can be effected from venous blood ! "Had not," he adds, " secretion been destined to take ])lace from the blood of the vena portarum, nature would not have been at the pains to distribute, it through the liver; the peculiar ar- rangement is already an answer to the question; the end of it is, as I have said, to economise arterial blood." As before remarked, however, a sufficient function can be assigned to the portal system without sup- posing that it has any agency in the secretion of bile. Still, there is nothing inconsistent with the idea, that both kinds of blood may be iuservient to the secretion. Mention has been made elsewhere, that ' Edinb. Me v circumference of the kidney; is about two lines in ^■%i'wh~ thickness; of less consistence than the other; of a t^^'--^-'^ ^ pale red colour; and receives almost entirely the ■> ^;%'i;' ramifications of the renal artery. The other and in- C^U ' ^ nermost is the tubular, medullary, iiriniferous, conoidal ^ ^ \ ;^, or radiated substance. It is more dense than the other; \kl>)j less red; and seems to be formed of numerous minute \M tubes, which unite in conical bundles of unequal size \-A ■ — pyramids of Malpiyhi — the base of which is turned v\ towards the cortical portion, — the apices forming the Portion of Kidney of pjapiUce or mammillary processes, and facing the pelvis of New-born infant, the kidney. The papillee vary in number from five to a. Natural size. b. • 1, "^ D n • 1 1 ^ ^^ • • i ^ small portion of a eighteen; are of a norid colour; and upon their points magnified, i, i. cor- or apices are terminations of uriniferous tubes large tuwu urfufi^l-r*' ^' ' Lond. cand Edinb. Montlily Journal of Med. Science, April, 1843, p. 323. ^ Eucyclop. Anatom., traduit jaar Jourdan, v. 321, Paris, 1845. Ill 554 SECRETION enough to be distinguislied by the naked eye. Around tbe root of each papilla, a mem- Fig. 177. branous tube arises 3 , a .3 called ca?ia: or infundi- bulum ; this receives the urine from the pa- pilla, and conveys it into the pelvis of the kidney, which may be regarded as the com- mencement of the ureter. The cortical part of the kidney is the most vascular; and the plexus formed by the tubuli uriniferi appears to come there in closest relation with that form- ed by the renal capil- laries. The corpora Malpigkiana or Mal- pighian bodies appear as points in the cortical substance. They are scattered through the plexus formed by the bloodvessels and urini- ferous tubes. Each one, when examined by a high magnifying power, is found to con- sist of a convoluted mass of minute blood- vessels. In them — it was at one time sup- posed — the uriniferous tubes originate ; but the examinations of Miiller and Iluschke have seemed to show, that they are only capa- ble of injection from the arteries or veins. They are found in the kidneys of most, if not all, of the vertebrata. In the cortical sub- stance, according to "Wagner,^ the tubuli can be traced, although with Small Portion of Kidney magnified 60 diameters. 1. Csecal extremity of a tubulus. 2, 2. Loops of tubuli. 3, 3. Bifur eated tubuli. 4, .'5, 6. Tubuli converging towards the papillse. 7, 7, 7 Corpora Malpigkiana. 8. Arterial trunk. ' Elements of Physiology, by R. Willis, § 193, Lond., 1842. OF THE KIDNEYS. 555 difficulty, winding among the vascular plexuses or skeins, mostly looped towards the margin of the organ, and running into one another, or having blind or cascal extremities; more rarely enlarged and club- shaped, and occasionally cleft. The entire cortical substance, according to Wagner, consists of convolutions of the uriniferous tubes, which present a nearly uniform diameter, on an average, from about the 60th to the 50th of a line. Professor Goodsir,^ however, without denying Section of the Cortical Substance of the Human Kidney. A, A. Tubnli nriniferi divided transversely, showing the spheroidal epithelium in their interior, b. Malpighian capsule, a. Its afferent branch of the renal artery, b. Its glomerulus of capillaries, c, c. Secreting plexus, formed by its efferent vessels, d, d. Fibrous stroma. the existence of occasional blind extremities of the tubuli uriniferi — the result probably, he thinks, of arrested developement — states, that he has never seen the ducts terminate in this way. He has described a fibro-areolar framework, which, per- vading every part of the gland, and particularly its cortical portion, per- forms the same office in the kidney as the capsule of Glisson does in the liver, — being a basis of support to the delicate structure of the gland, conducting the bloodvessels through the organ, and constituting small chambers in the cortical portion, in each of which a single ultimate coil or loop of the uriniferous ducts is lodged. Mr. Goodsir believes, that the urine is formed at first within the epithelium cells of the ducts, and that these burst, dissolve, and throw out their contents, and are succeeded by others, which perform the same func- tions. The urine of man has not been detected by Mr. Goodsir within the cells, that line the ducts, but he has submitted to the Royal Society Tubuli Uriniferi. A. Portion of a secreting canal from the cor- tical substance of the kidney, b. The epithe- lium or gland-cells, more highly magnified (700 times), c. Portion of a canal from tho medul- lary substance of the kidney. At one part the basement membrane has no epithelium lining it. ' Lond. and Edinb. Monthly Journ. of Med. Science, May, 1842. 556 SECRETION Fis:. ISO. of Eclinburgli a memoir, already referred to, in which he has endea- voured to show, that urine, bile, and milk, as well as the other more important secretions in the lower animals, are formed within the nucleated cells of the ducts themselves; and he is of opinion, that the urine of man is poured at first into the cavities of the nucleated cells of the human kidney. Mr. Bowman^ describes the kidney as furnished with a true portal system, and is of opinion that the urine, like the bile, is secreted — in part at least — from blood, traversing a second set of capillaries. Accord- ing to him, each of the exceedingly tortuous and convoluted urinary conduits terminates, at its final extremity, by a contracted neck, which leads into a little chamber or cyst, — capsule of Malpighi — in which is contained the true glandule, corpuscle or ghmerule of Malpighi. This consists of a tuft or coil of capillary bloodvessels, totally naked, which originates in one of the ulti- mate branches of the renal artery, and ter- minates in an efi'erent vessel. Several of these latter form, by their anastomosing ramifications, the plexus that surrounds each urinary conduit and tubule , the uri- nary conduits being lined by thick epithe- lium, and their necks furnished with vi- bratile cilia. All the blood of the renal artery, according to Mr. Bowman, — with the exception of a small quantity distri- o/severr.L^pthVarr4r7rrt? l^^ted to the capsule, surrounding fat, and ferent twig to the capillary tuft contain- the coats of the larger vcsscls, — cutcrs the ed in the Malpighiaa body, ni; from the .,, „ pi a r i • - • Malpighian body the uriniferous tube Is Capillary tUltS Ot tUC COrpOra Malpighiana; seen taking its tortuous course to (. 2,2. .1 ' 1. ±.\ •^^ ^ „ Efferent veins; that which proceeds from theUCC paSSeS lUtO thc CapillarV plCXUS '^^!^^:^i^:^7!^^ surrounding the uriniferous tubes, and capillary venous piexus,jamifying upon finally Icavcs the Organ through the branches of the renal vein. According to this view, there are in the kidney two perfectly distinct systems of capillary ves- sels; \he first, i}i2ii inserted into the dilated extremities of the urinifer- ous tubes, and in immediate connexion with the arteries — the Mal])i- ghian bodies; — the second, that enveloping the convolutions of the tubes, and communicating directly with the veins. The efferent vessels of the Malpighian bodies, that carry the blood between these two systems, are termed by Mr. Bowman the fjorial system of the liidney. The views of Mr. Bowman have been embraced by man}^ histologists,^ whilst every one of them has been strenuously denied by others. In regard to the precise arrangement of the Malpighian bodies, histologists are by no means in accordance, Gerlach for example, found, that instead of the flask-like dilatation being placed, as maintained by ^[r. Bow- Plan of the Renal Circulation. the uriniferous tube. This plexus re- ceives its blood from the efferent veins, 2, 2, and transmits it to the branch of the renal vein, u. ' Proceedinss of the Royal Society, No. lii., Feb. 3, 1842; and Philos. Transactions, Pt. 1, p. 57, Lond., 1842. ^ See on the whole subject Dr. Geo. Johnson, in the article Ren, Cyclopaedia of Ana- tomy and Physiolosiy, Pt. xxxii. p. 244, Lond., August, 1848; Gerlach, Handbuch der Gewebelehre, S. 301, Mainz, 1849 ; and A. H. Hassall, The Microscopic Anatomy of the Human Body, Pt. xiii. p. 427, Loud., 1848. OF THE KIDNEYS. 557 man, at the extremity of a nriniferous tube, it may be, and is formed by offsets from the sides of the tube; so that the capsules maybe either terminal or lateral.' In the quadruped, each kidney is made up of numerous lobes, which are more or less intimately united according to the species. In birds, the kidney consists of a double row of distinct, but connected, glandu- lar bodies, placed on both sides the lumbar vertebra. The ureter is a membranous duct, which extends from the kidney to the bladder. It is about the size of a goosequill ; descends through the lumbar region ; dips into the pelvis by crossing in front of the primi- tive iliac vessels and the internal iliac ; crosses the vas deferens at the back of the bladder; and, penetrating that viscus obliquely, terminates by an orifice ten or twelve lines behind that of the neck of the bladder. At first, it penetrates two of the coats only of that viscus; running for the space of an inch between the mucous and muscular, and then enter- ing the cavity. The ureters have three coats. The outermost is a dense fibrous membrane; the second a smooth muscular layer, which is very distinct, with external longitudinal, and internal transverse fibres, to which, towards the bladder, internal longitudinal fibres are added. In the pelvis of the kidney the two muscular layers are as thick as in the ureter; but in the calices they become thinner and thinner, and cease where the latter are inserted into the papillee.^ The innermost coat is a thin mucous layer, which is continuous at its lower extremity with the inner coat of the bladder ; and, at the upper end, supposed by some to be reflected over the papillo3, and even to pass for some distance into the tubuli uriniferi. Sie bladder is a musculo-membranous sac, situate in the pelvis ; nor to the rectum, and behind the pubes. Its superior end is called upper fundus; and the lower end, inferior fundus or has fond ; the lody being between the two. The part where it joins the urethra is the nech. The shape and situation of the organ are influenced by age and sex. In very young infants, it is cylindroid, and rises almost wholly into the abdomen. In the adult female, who has borne many children, it is nearly spherical ; has its greatest diameter transverse, and is more capacious than in the male. Like the other hollow viscera, the bladder consists of several coats. 1. The peritoneal^ which covers only the fundus and back part. Towards the lower portion the organ is invested by areolar membrane, which takes the place of the peritoneal coat of the fundus. This tissue is very loose, and permits the distension and contraction of the bladder. 2. The muscular coat is very strong; so much so, that it has been classed amongst the distinct muscles, under the name detrusor wince. The fibres are pale, uustriped, and pass in various directions. Towards the lower part of the bladder, they are particularly strong; arranged in fasciculi, and form a kind of network of muscles enclosing the bladder. In cases of stricture of the urethra, where much efibrt is necessary to expel the urine, these fasciculi acquire ' Gerlach, op. cit., and in Miiller's Archiv. fiir Anatomic, S. 378, 1845 ; and Ibid., S. 102, 1848. ^ Kolliker, Mikroskopische Anatomic, 2ter Band. S. 365, Leipzig, 1854; and Amer. edit, of Svdenham Society's edit, of his Manual of Human Histology, by Dr. Da Costa, p. 607, Piiilad., Ib54. 558 SECRETION considerable thickness and strength. 3. The mncous or villous coat is the lining membrane, which is continuous with that of the ureters and urethra, and is generally rugous in consequence of its being more exten- sive than the muscular coat without. It is furnished with numerous follicles, which secrete a fluid to lubricate it. Towards the neck of the organ, it is thin and white, although reddish in the rest of its extent, A fourth coat, called the cellular or areolar has been reckoned by most anatomists, but it is nothing more than areolar tissue uniting the mucous and muscular coats. The part of the internal surface of the bladder, situate immediately behind and below its neck, and occupying the space between it and the orifices of the ureters, is called vesical triangle^ tri- gonus Lieutaucli or trigone vesical. The anterior angle of the triangle looks into the orifice of the urethra, and is generally so prominent, that it has obtained the name uvula vesicce. It is merely a projection of the mucous membrane, dependent upon the subjacent third lobe of the prostate gland, which, in old people, is frequently enlarged, and occa- sions difficulty in passing the catheter. The neck of the bladder pene- trates the prostate; but, at its commencement, it is surrounded by loose areolar tissue, containing a very large and abundant plexus of veins. The internal layer of muscular fibres is here transverse ; and they cross and intermix with each other in different directions, forming a close, compact tissue, which has the effect of a particular apparatus for retain- ing the urine, and has been called the sphincter. Anatomists have not usually esteemed this structure to be distinct from the muscular coat at large; but Sir Charles Bell' asserts, that if we begin the dissection by taking off the inner membrane of the bladder from around the orifice of the urethra, a set of fibres will be discovered on the lower htfalf of the orifice, which, being carefully dissected, will be found to run m a semicircular form around the urethra. These fibres make a band of about half an inch in breadth, particularly strong on the lower part of the opening; and having ascended a little above the orifice on each side, they dispose of a portion of their fibres in the substance of the bladder. A smaller and somewhat weaker set of fibres will be seen to complete their course, surrounding the orifice on the upper part. The arteries of the bladder proceed from various sources, but chiefly from the umbilical and common pudic. The veins return the blood into the internal iliacs. They form a plexus of considerable size upon each side of the bladder, particularly about its neck. The lymphatics accompany the principal veins of the bladder, and, at the under part and sides, pass into the iliac glands. The nerves are from the great sympathetic and sacral. The urethra is the excretory duct of the bladder. It extends, in the male, from the neck of the bladder to the extremity of the glans; and is from seven to ten inches in length. In the female it is much shorter. The male urethra, in the state of flaccidity of the penis, has several cur- vatures; but is straight or nearly so, if the penis be drawn forwards and upwards, and the rectum be empty. The first portion of this canal, which traverses the prostate gland, is called the prostatic portion. Into it open, — on each side of a caruncle, called verumontanum, cajmt galli- ' Anatomy and Physiol., 5th Amer. edit, by Dr. Godman, ii. 375, New York, 1829. I i OF THE KIDNEYS. 559 naginis or crista urethralis, — the two ejaculatory ducts, those of the prostate, and a little lower, the orifice of Cowper's glands. Between the prostate and the bulb is the memhranons part of the urethra, which is eight or ten lines long. The remainder of the canal is called corpus spongiosum or spongy portion^ because surrounded by an erectile spongy tissue. It is situate beneath the corpora cavernosa, and passes forward to terminate in the glans, the structure of which will be considered under Generation. At the commencement of this portion of the urethra is the bulb, the structure of which resembles that of the corpora caver- nosa of the penis — to be described hereafter. The dimensions of the canal are various. At the neck of the bladder it is considerable ; be- hind the caput gallinaginis it contracts, and immediately enlarges in the forepart of the prostate. The membranous portion is narrower; and in the bulb the channel enlarges. In the body of the penis, it dimi- nishes successively, till near the glans, when it is so much increased in size as to have acquired the name fossa navicularis. At the apex of the glans it terminates by a short vertical slit. Mr. Shaw^ has described a set of vessels, immediately on the outside of the internal membrane of the urethra, which, when empty, are very similar in appearance to muscular fibres. These vessels, he remarks, form an internal spongy body, which passes down to the membranous part of the urethra, and forms even a small bulb there. Dr. Horner,^ however, says, that this appeared to him to be rather the areolar membrane connecting the canal of the urethra with the corpus spongiosum. The whole of the urethra is lined by a very vascular and sensible mucous membrane, which is continuous with the inner coat of the bladder. It has, apparently, a certain degree of contractility ; and therefore, by some anatomists, is conceived to possess muscular fibres. Sir Everard Home, from the results of his microscopical observations, is disposed to be of this opinion. This is, however, so contrary to analogy, that it is probable the fibres may be seated in the tissue surrounding it. The membrane contains numerous follicles, and several lacunae, one or two of which, near the extremity of the penis, are so large as occasionally to obstruct the catheter, and convey the impression that a stricture exists. The prostate and glands of Cowper, being more concerned in gene- ration, will be described hereafter. There are certain muscles of the perineum, that are engaged in the expulsion of the urine from the urethra ; and some of them in defeca- tion, and the evacuation of sperm likewise; — as the acceleratores urince or bulbo-urethrales, which propel the urine or semen forward ;^ the transversus perinei or ischio-perinealis, which dilates the bulb for the reception of the urine or sperm; the sp)hincter ani, which draws down the bulb, and aids in their ejection ; and the levator ain, which sur- rounds the extremity of the rectum, the neck of the bladder, the mem- branous portion of the urethra, the prostate gland, and a part of the vesiculae seminales, and assists in the evacuation of the bladder, vesi- culie seminales, and prostate. A part of the levator, which arises ' Manual of Anatomy, ii. 118, Lond., 1822. ^ Lessons in Practical Anatomy, 3d edit., p. 272, Philad., 1836. ' For Dr. Horner's views on the origin of the acceleratores urinse, see his Special Anatomy and Histology, 8th edit., Philad., 1851. 560 SECRETIOlSr, from the pubis and assists in inclosing the prostate, is called by Scira- mering compi-essor prostatce. Between the membranous part of the urethra, and that portion of the levator ani which arises from the inner side of the symphysis pubis, a Fig. 181. reddish, areolar, and very vascu- lar substance exists, which closely surrounds the canal, has been de- scribed by Mr. Wilson^ under the name compressor urethrce, and is termed, by some of the French anatomists, muscle de Wilson. By many, however, it is con- sidered to be a part of the leva- tor ani. M. Amussat asserts, that the membranous part of the ure- thra is formed externally of mus- cular fibres, which are suscepti- ble of energetic contraction ; and M, Magendie^ confirms his asser- tion. With regard to the urinary or- gans of the female: — the kidnej'S and ureters have the same situa- tion and structure as those of the male. The bladder, also, holds the same place behind the pubis; but rises higher when distended. It is proportionally larger than that of the male, and is broader from side to side, thus permit- ting the greater retention to which females are often necessitated. The urethra is much " shorter, being onlj^ about an inch and a half, or two inches long; and it is straighter than in the male, having only a slight curve downwards between its extremities, and passing almost horizontally under the symphysis pubis. It has no prostate gland, but is furnished, as in the male, with follicles and lacunae, which provide a mucus to lubricate it. In birds in general, and in many reptiles and fishes, the urine, prior to expulsion, is mixed with the excrement in the cloaca. Nothing analogous to the urinary organs has been detected in the lowest classes of animals, although in the dung of the caterpillars of certain insects, traces of urea have been met with. The urine is formed from the blood in the kidneys ; and it has, until recently, been the universal belief, that it is secreted from arterial blood; Mr. Bowman, however, in accordance with views on the the Part of the Ossa Pubis and Ischia, with Root of the Penis attached.' a, a. Accelerator urinae muscle, embracing the bull} of the urethra, -which is slightly notched in the middle line, e, behind, h, h. Anterior slips of the accelerator muscle, which pass round to the dorsum of the penis, e, c. Crura of the penis, rf, d. Erectores penis muscles lying on the crura. /. The corpus spongiosum urethrae. g, to g. Enlargement of the crus, named the bulb of the corpus caverno- sum. 1 ' Kobelt, De I'Appareil du Sens Genital des deux Sexes, traduit de I'Allemand, par H. Kaula, D. M., Strasbourg, 1851. ^ Lectures on the Structure and Physiology of the Urinary and Genital Organs, Loud., 1821. i» Precis, kc, ii. 472. OF THE KIDNEYS. 561 minute anatomy of the kidney already given, has attempted to show, that it is separated from venous blood. His main conclusions are as follows : — First. The epithelium lining the tubes is the proper organ that secretes the characteristic products of urine from the blood ; and it does this by first assimilating them into its own substance, and afterwards pouring them upon its free surface. Secondly. These pro- per urinous products require for their solution a large quantity of water. Tldrdly. This water is furnished by the Malpighian tufts of capillaries, placed at the extremity of the uriniferous tubes ; and Fourthly. A farther use of the Malpighian bodies seems to be that of sharing in regulating the amount of water in the body. He thus makes a striking analogy between the liver and the kidney both in structure and function ; and expresses his belief, — Jirst^ that diuretic medicines act specially on the Malpighian bodies, and that many sub- stances, particularly salts, which, when taken into the S3'stem, have a tendency to pass off by the kidneys with rapidity, in reality escape through the Malpighian bodies : secondly^ that certain morbid products occasionally found in the urine, such as sugar, albumen, and the red particles of the blood, in all probability, pass oft' through this bare system of capillaries. The discovery, however, by Gerlach,^ and others, that the proper Malpighian capsule is invariably lined by in- numerable granular cells, naturally suggested, that the Malpighian body is destined for some action of elaboration, and that it is as much concerned in the proper urinary secretion as the uriniferous tubes; and on these grounds Mr. Hassall expresses the belief, that urine is formed in every part of the tubular and Malpighian surface of the kidney ; and he thus dissents from the opinion of Mr. Bowman, that the Malpighian body is an apparatus destined for the simple separa- tion of the watery parts of the urine; whilst he agrees with him, that the greater portion of the more watery parts proceed from the Malpig- hian bodies; — which is probable. It is not so easy to accord with him, that the last action is not "effected by an act of simple separation but by one of secretion." A simple physical act of endosmose — -it need scarcely be said — is alone needed in the case of a tenuous fluid ; and cell agency is only required where an action of elaboration has to be exerted. According to M. Raspail,^ the urine is a kind of caput mortuum^ ejected into the urinary bladder by the kidneys. They separate car- bon and nitrogen in the form of cyanogen, which unites with oxygen to produce cyanic acid; and this combines with ammonia — itself a compound of nitrogen and hydrogen — to form urea, which is the cha- racteristic element of the urinary secretion. They separate also, and excrete superfluous fluid from the bod}^ The proofs of such separa- tion are easy and satisfactory ; but with regard to the mode in which the operation is effected, we are in the same darkness that hangs over glandular secretions in general. The transformation doubtless occurs mainly in the cortical part of the organ, and essentially in the same manner as other secretions are formed from the blood; — the action of ' Op. cit. 2 Chimie Organique, p. 505, Paris, 1833. VOL. I. — 36 562 SECEETION I elaboration taking place through the agency of cells, which burst and discharge the proper urinary matter into the uriniferous tubes. The urinary secretion takes place continuously. If a catheter be left in the bladder, the urine drops constantly ; and in cases of exstro- pkia of that organ — a faulty conformation, in which a red mucous surface, formed by the inner coat of the bladder, is seen in the hypo- gastric region on which two prominences are visible, corresponding to the openings of the ureters, the urine is observed to be constantly oozing from the openings.-^ A case of the kind the author has had repeated opportunities of exhibiting to his class in the Jefferson Me- dical College. After the secretion has been effected in the cortical substance, it flows through the tubular, and issues guttatim through the apices of the papillas into the pelvis of the kidney, whence it proceeds along the ureter to the bladder. If the uriniferous cones be slightly compressed, urine issues in greater quantity; but, instead of being limpid, as when it flows naturally, it is thick and troubled. Hence a conclusion has been drawn, that it is really filtered through the hollow fibres of the medullary or tubular portion. If this were the case, what must become of the separated thick portion? Ought not the tubes to become clogged up with it? And is it not more probable, that compression, in this case, forces out with the urine some of the blood that is concerned in the nutrition of the organ? The fresh secretion constantly taking place in the kidney causes the urine to flow along the tubuli uriniferi to the pelvis of the organ, whence, in the erect attitude, it proceeds along the ureter, by virtue of its gravity: the fluid, too, continually secreted from the kidney, pushes on that before it: moreover, it is now proved, that a contractile action is exerted by the ureters themselves; although, as in the case of the excretory ducts in general, such a power had been denied them. These, with the cilia of the lining membrane,^ are the chief causes of the progression of the urine into the bladder, which is aided by the pressure of the abdominal contents and muscles; and, it is supposed, by the pulsation of the renal and iliac arteries ; but the agency of these must be trivial. The orifices of the ureters form the posterior angles of the trigone vesical^ and are contracted somewhat below the size of the ducts them- selves. They are said by Sir Charles BelP to be furnished with a small fasciculus of muscular fibres, which runs backwards from the orifice of the urethra, immediately behind the lateral margins of the triangle ; and, when it contracts, stretches the orifice of the ureter so as to permit the urine to enter the bladder with facility. As the urine passes in, it gradually distends the organ until the quantity has attained a certain amount. It cannot reflow by the ureters, on account of the smallness of their orifices and their obliquity ; and as the blad- der becomes filled, — owing to the duct passing for some distance be- ' A case of this kind is detailed by the author, in Amer. Med. Intelligencer, i. 137 ; and another by Dr. Pancoast, ibid., p. 147, Philad., 1838. ^ On the Ciliarv Motion of the Tubes, see Dr. George Johnson, art. Ren, snpra cit., p. 253. ^ Anatomy and Physiology, 5th American edition, by Godman, ii. 381, Ne\y York, 1827. OF THE KIDNEYS. 563 tween the muscular and mucous coats, — the sides are pressed against each other, so that the cavity is obliterated. As, however, the ureters have a tendency to lose this obliquity of insertion, in proportion as the bladder is emptied, the two bands of muscular fibres, which run from the back of the prostate gland to the orifices of the ureters, not only assist in emptying the bladder, but, at the same time, pull down the orifices of the ureters, and thus tend to preserve the obliquity. Moreover, when we are in the erect attitude, the urine would have to enter the ureters against gravity. These obstacles are so effective, that if an injection be thrown forcibly and copiously through the ure- thra into the bladder, it does not enter the ureters. On the other hand, equally powerful impediments exist to its being discharged through the urethra. The inferior fundus of the bladder is situate lower than the neck ; and the sphincter presents a degree of resist- ance, which requires the bladder to contract forcibly on its contents, aided by the abdominal muscles to overcome it. Magendie^ considers the contraction of the levatores ani to be the most efficient cause of the retention of the urine; the fibres which pass around the urethra pressing its sides against each other, and thus closing it. In a case of exstrophy of the bladder, Mr. Erichsen^ had an opportunity of mark- ing several interesting phenomena connected with the excretion of urine. The orifice of each ureter in the bladder appeared, when closed, as a small irregularly oval depression, about a line in diameter, situate on a conical papilla of the mucous membrane. A probe might be passed up the ureters for several inches without any sensible incon- venience being sustained. In regard to the phenomena attending the passage of the urine from the ureters into the bladder, it appeared, that in the first place a drop collected within the papillary termination of the ureter, which became somewhat distended ; the orifice of the canal then opened to an extent of from two to three lines in diameter, and, as soon as it had allowed the drop of urine to pass, it contracted with a sphincter-like action. The distension of the lower end of the ureter, before the drop of urine escaped, was very distinct; and the relaxation of the orifice of the canal had the appearance of being occa- sioned by the accumulation of the drop of fluid that collected above it. The closure of the vesical termination of the ureter, after the escape of the drop of urine, was accompanied by a slight retraction of the pa- pillary bulging of the mucous membrane on which it terminated, and the whole process resembled an ordinary sphincter action. The two ureters did not open at the same time, but with an irregularly alter- nating action. During the periods of fasting, they opened on an ave- rage about three times in a minute; consequently, the quantity of urine discharged from both might be estimated at about three large drops in the same S])ace of time; but although this might be taken as the average rate of discharge, the action of the ureters was by no means regular, inasmuch as two or three drops would some- times flow in rapid succession, whilst, at other times, a comparatively long interval would elapse between the escape of any two. When the patient lay upon his back, the discharge was slow and gentle, being ' Precis, &c., edit, cit., ii. 473. ^ London Medical Gazette, 1S45. 564 SECRETION unattended with the distinct opening and shutting of the end of the tube noticed when in the upright position. During a deep inspira- tion, as in yawning or coughing, or whilst straining at stool, the flow of urine was suddenly increased, and the fluid escaped in a small stream, or in several large drops in rapid succession. The urine itself was invariably acid, and often highly so, whilst the mucous membrane of the bladder possessed a highly alkaline reaction. It was covered by a viscid glairy mucus, and was extremely sensitive to the touch. Urine accumulates in the bladder until the desire arises to expel it: the number of times that a person in health and in the middle period of life discharges it in the twenty-four hours, varies : some evacuate the bladder but twice, others may be compelled to do so as many as twelve or fourteen times. Nine times, according to Dr. Thomas Thom- son,' is a common number. The quantity discharged at a time varies. The greatest observed by Dr. Thomson was 25 J cubic inches or some- what less than a pint; the most common from seven to nine cubic inches. During its stay in the bladder, it is believed to be deprived of some of its more aqueous portions by absorption, and to become of greater specific gravity, and more coloured: it is here that depositions are apt to take place, which constitute calculi; although they are met with in the kidneys and ureters also. As in every excretion, a sensation first arises, in consequence of which the muscles required for the ejection of the secreted matter are called into action. This sensation occurs whenever the urine has accumulated to the necessary extent, or when it possesses irritating qualities, owing to extraneous substances being contained in, or deposited from, it; or if the bladder be unus'ially irritable from any morbid cause, the sensation may be repeatedly — nay, almost incessantly^ — experienced. The remarks that have been made on the sensations accompanying the other excretions are equally applicable here. The impression takes place in the bladder; whence it is conveyed to the brain, which accom- plishes the sensation; and, consecutively, the muscles, concerned in the excretion, are called into action by volition. Physiologists have difibred regarding the power of volition over the bladder. Some have affirmed, that it is as much under cerebral control as the muscles of locomotion ; and they have urged, in support of this view, that the bladder receives spinal nerves, which are voluntary; that it is paralysed in affections of the spinal marrow, like the muscles of the limbs; and that a sensation, which seems destined to arouse the will, is always the precursor of its action. Others again have denied, that the muscular fibres are con- tractile under the will; and they adduce the case of other reservoirs, — the stomach and rectum, for example, — whose influence in excretion we have seen to be involuntary; as well as the fact that we feel the contraction of the bladder no more than we do that of the stomach or intestines; and they affirm, that the action of the bladder itself has been confounded with that of the accessory muscles, which are mani- festly under the influence of the will, and are important agents in the expulsion of fluid from the bladder. The views last expressed appear to be most accurate, and the catenation of phenomena seems to be as ' BritisL. Annals of Medicine, p. 6, Jan., 1837. OF THE KIDNEYS. 565 follows: — the sensation to expel the urine arises; the abdominal mnscles are thrown into contraction by volition ; the viscera are thus pressed down upon the pelvis; the muscular coat of the bladder is, at the same time, stimulated by reflex action to contraction; the levatores ani and the sphincter fibres are relaxed, so that the resistance of the neck of the organ is diminished, and the urine is forced out through the whole extent of the urethra, being aided in its course, especially towards the termination, by the contractile action of the urethra itself, as well as by the levatores ani and acceleratores urinse muscles. These expel the last drops by giving a slight succussion to the organ, and directing it upwards and forwards ; an effect which is aided by shaking it to remove the drops that may exist in the part of the canal near its extremity. The gradually diminishing jet, which we notice as the bladder is be- coming empty, indicates the contraction of the muscular coat of the organ; whilst the kind of intermittent jet, coincident with voluntary muscular exertion, indicates the contraction of the urethral muscles. When we feel the inclination to evacuate the bladder, and do not wish to obey it, the same muscles, — levatores ani, acceleratores urinas, and the fibres around the membranous portion of the urethra and neck of the bladder, — are thrown into contraction, and resist that of the bladder. Such is the ordinary mechanism of the excretion of urine. The con- traction of the bladder is, however, of itself sufficient to expel its con- tents. M. Magendie^ affirms, that he has frequently seen dogs pass urine when the abdomen was opened, and the bladder removed from the influence of the abdominal muscles ; and he further states, that if, in a male dog, the bladder, with the prostate and a small portion of the membranous part of the urethra, be removed from the body, the blad- der will contract after a few moments, and project the urine, with an evident jet, until it is entirely expelled. Urine, voided in the morning — urina sanguinis — by a person who has eaten heartily, and taken no more liquid than sufficient to allay thirst, is a transparent, limpid fluid, of an amber colour, saline taste, and peculiar odour. Its specific gravity is estimated by M. Chossat at from 1-001 to 1-038 ; by Cruikshank, Wagner,^ and Gregory, from 1-005 to 1-033 ; by Prout, from 1-015 to 1-025 ; by Christison,^ on the average, 1-024 or 1-025 ; by F. d'Arcet, from 1*001 to 1-060 [?] ■* by Eayer,* and Donne,® on the average, TOIS : by Dr. Bostock, M. Martin Solon,^ and J. Vogel, 1-020; by Dr. Routh,« 1-021 ; by Becquerel and Eodier,^ in man, 1-018*900; in woman, 1-015-120; general average, 1-017-010; by Dr. Elliotson,^° from 1-015 to 1-025; by Simon, 1012; and ' Precis, ii. 474. ^ Elements of Physiology, by R. Willis, § 200, Lond., 1842. ' On GianuLar Degeneration of the Kidneys, p. 34, Edinb., 1S39 ; or Amer. Med. Library edit., Philad!', 183i>. ■* L'Experience, No. Iv., Aug., 1838. ^ Traite des Maladies des Reins, &c., torn, i., Paris, 1839. ^ Cours de Microscopie, p. 226, Paris, 1844. ^ De PAlbuminurie on Hydropisie Causee par Maladie des Reins, Paris, 1838! 8 Lond. Med. Graz., Sept., 1850. See, also, Geo. Johnson, on the Diseases of the Kidney, p. 43, Lond., 1852. ^ Traite de Chimie Pathologique Applique a la Medecine Pratique, p. 270, Paris, 1854. ■0 Human Physiology, p. 293, Lend., 1835. 566 SECRETION Dr. Thomson^ found it in an individual, from 50 to 60 years of age and in perfect health, on the average, 1-013 ; the lowest specific gravity, during ten days, being 1*001; and the highest, 1-026. Dr. Thomson has published tables^ showing the quantity of urine passed at dift'erent times during ten days by the individual in question, and the specific gravity of each portion. They do not accord with the opinion gene- rally but erroneously entertained, that the heaviest urine is voided on rising in the morning, — urina sanguinis. No generalization can, indeed, be made on the subject. The temperature of the urine, w^hen recently passed, varied in one case from 92° to 95°. Dr. Brown-Sequard, how- ever, found its ordinary degree to be 102°-5.' Urine, when first passed, is slightly acid, for it reddens vegetable blues. Although at first transparent, it deposits an insoluble matter on standing; so that that which is passed at bed-time, is found to have a light cloud — encp.orema — floating in it by the following morning. This substance consists, in part, of mucus from the urinary passages ; and, in part, of the super-lithate of ammonia, which is much more soluble in warm than in cold water. Urine is extremely prone to decompo- sition. When kept for a few days it acquires a strong smell, which, being sv.i generis^ has been called urinovs ; and as the decomposition proceeds, it becomes extremely disagreeable. As soon as these changes commence, it ceases to have an acid reaction. In a short time, a free alkali makes its appearance; and a large quantity of carbonate of ammonia is generated, and earthy phosphates are deposited. These phenomena are owing to the decomposition of urea, which is almost wholly resolved into carbonate of ammonia. Dr. Golding Bird," states, that three distinct varieties of iirinarv se- cretion may be recognised. First. That passed some little time after drinking freely of fluids, which is generally pale, and of low specific gravity — 1"003 to 1-009 — urina potiis. Secondly. That secreted after the digestion of a full meal, varying much in physical characters, and of considerable density — 1-020 to 1*028, or even 1-030 — urina chyli sen cihi. Thirdhj. That secreted from the blood independently of the immediate stimulus of food and drink, as that passed after a night's rest — urina sanguinis^ which is usually of average density — 1-015 to 1-025 — and presents in perfection the essential characters of the fluid. According to VogeV a healthy man may, by very copious water drinking, reduce the specific gravity of his urine to 1-000-5; and by ab- staining from fluids, and by taking such violent exercise as to induce free perspiration may raise it to 1*033, and even more. The following table, drawn up, as far as 1032, by M. Becquerel, and completed from the observations of the last mentioned inquirer,^ ex- hibits at a single inspection the amount of solids and water present in 1000 grains of urine of any particular density ; so that from the quan- ' British Annals of Medicine, p. 5, Jan., 1837. ^ Op. citat., p. 6. 3 Med. Examiner for Sept., 1852, p. 556. * Urinary Deposits, 2d Amer. edit.. \>. 31, Philad., 1851. * Archiv. d. Vereins fiir Gemeinschaftlicli. Arbt'iten, Bd. 1, Heft 1, Giittingen, 1853 ; cited by Dr. Geo. E. Day, in Brit, and For. Med.-Chir. Rev., July, 1855, p. 73. 6 Lond, Med. Gazette, Feb. 10, 1843, p. (J78. OF THE KIDNEYS. 567 tity of urine passed in twenty-four hours it is easy to calculate how much solid matter the patient is parting with in that period. Water in 1000 Solids in 1000 Water in 1000 Solids in 1000 Density. grains. grains. Density. grains. grains. 1 1001 998-35 1-65 1029 960-4 39-6 I 1002 996-7 3-3 1 1026 957-1 42-9 1004 993-4 6-6 1028 953-8 46-2 1006 990-1 9-9 1030 950-5 49-5 1008 986-8 13-2 1032 947-2 52-8 1010 983-5 16-5 1034 943-9 56-1 1012 980-2 19-8 1036 940-6 59-4 1014 976-9 23-1 1038 937-3 62-7 1016 973-6 26-4 1040 934- 66- 1018 970-3 29-7 ; 1042 930-7 69-3 1020 967- 33- 1044 927-4 72-6 1022 963-7 36-3 1046 924-1 75-9 The appearances presented by the urine under the microscope have, of late years, given rise to numerous investigations: these of course vary, according to the modifications it exhibits in health and disease. In the latter condition, much information has been collected, so that, according to M. Donne, the study of the urine may be said to be "the triumph of the microscope."^ The morbid appearances, however, which it presents, do not belong to a work on physiology. Dr. Ilenry^ affirms, that the following substances have been satis- factorily proved to exist in healthy urine, — water, free phosphoric acid, phosphate of lime, phosphate of magnesia, fluoric acid, uric acid, benzoic acid, lactic acid, urea, gelatin, albumen, lactate of ammonia, sulphate of potassa, sulphate of soda, fluoride of calcium, chloride of sodium, phosphate of soda, phosphate of ammonia, sulphur and silex. One of the most elaborate analyses has been given by Berzelius.^ He states it to consist — in 1000 parts — of water, 933-00; urea, 30-10; sulphate of potassa, 3-71 ; sulphate of soda, 3-16 ; phosphate of soda, 2-94; chloride of sodium, 4'45 ; phosphate of ammonia, 1'65 ; muriate of ammonia, 1*50 ; free lactic acid ; lactate of ammonia ; animal matter soluble in alcohol, and urea not separable from the preceding, 17'1'±; earthy phos- phates, with a trace of fluoride of calcium, 1*00 ; lithic acid, 1*00 ; mucus of the bladder, 0-32 ; silex, 0-03. Dr. Prout" found 100 parts to consist of lithic acid, 90-16; potassa, 3'45; ammonia, 1'70; sulphate of potassa, with a trace of chloride of sodium, '95; phosphate of lime, carbonate of lime, and magnesia, "80; and animal matter, consisting of mucus and a little colouring matter, 2-94. M. RaspaiP thinlcs it "pos- sible" that uric acid is merely a mixture of organic matter (albumen) with an acid cyanide of ammonia ; so that the results of analysis may differ according as the analyzed substances may have been more or less ' Cours de Microscopie, p. 213, Paris, 1844. 2 Elements of Experimental Chemistry, 9th edit., vol. ii. p. 435, Lond., 1823. ^ Med.-Chirurg. Transact., vol. iii. ; Annals of Philos., ii.423 ; and The Kidneys and Urine, by J. J. Berzelius, translated from the German, by M. H. Boye, and F. Learning, M.D.,'p. 97, Philad., 1843. •» Annals of Philos., v. 415. ^ Op. citat., p. 507. 568 SECRETION ij separated from the organic matter. The physical and chemical charac- ters of true uric acid, he thinks, accord very well with this hypothesis. Elaborate researches have been undertaken by Liebig,^ as regards the constitution of the urine, — whence he derives the following infer- ences. First. Neither lactic acid nor any lactate exists in healthy urine. Secondly. Hippuric acid is a constant constituent. Thirdly. The acid reaction of healthy urine is due to the presence of acid phosphate of soda. Fourthly. The acidity of urine is maintained and increased by the following changes. The urine of man and the carnivora has a large quantity of sulphates; but their food does not contain either those salts ready formed, or any oxygen compound of sulphur. The sulphur which it does contain, or which amounts to the same thing, the sulphur of the transformed tissues must, therefore, combine with oxygen in the body; and the sulphuric acid thus formed, uniting with part of the alkali of the alkaline phosphates, forms acid phosphates. Lastly. It follows, that whether the urine be acid or not depends upon the nature and quantity of the bases taken with the food. If the amount be sufiicient to neutralize the uric, hippuric, and sulphuric acids formed by the organism, and the acids supplied by the food, the urine must be neutral; if the amount be more than enough, the urine must be alkaline; if less, acid. Hence no physiological or pathological inference can be drawn from an examination of the urine, unless an account be taken of the inorganic acids, salts, and bases taken with the food. Some experiments have been made on the variations of the acidity of the urine in health by Dr. H. Bence Jones.^ When a mixed diet was employed, the acidity of the urine was found to decrease soon after taking food, and to attain its lowest limit from three to five hours after meals. It then gradually increased, and attained its highest limit just before taking food. AVhen animal food only was taken, the dimi- nution of acidity was more marked and more lasting; but the acidity before food did not rise quite so high as it did with the animal diet. When vegetable food was alone taken, the decrease in acidity was not to the same degree. Notwithstanding the view of Liebig, that the uric acid of the urine is held in solution by the phosphate of soda, combining with a part of the base, and setting free a portion of the phosphoric acid. Dr. Golding Bird'' adheres to the opinion of Dr. Prout, that uric acid is combined with ammonia. "Uric acid," he says, "at the moment of separation from the blood, meets the double phosphate of soda and ammonia de- rived from the food, and forms urate of ammonia, evolving phosphoric acid, which thus produces the natural acid reaction of the urine." Healthy urine has been analyzed by Becquerel, Lehmann, Simon, Marchard, Day, and others. The analyses of Lehmann and Marchard approximate that of Berzelius; whilst those of Becquerel, Simon, and Day, agree pretty closely with each other.'' The following are two of Simon's analyses: — ' Annalon der Cliemie land Pharmacie, Mai, cited in London Lancet, June 1-8, 1844. 2 IMiilosopliical Transactions for 1849, Ft. 2. ' Urinary Deposits, p. 48. '' Dr. Day's Report on Physiological and Pathological Chemistry, in Ranking's Ab- stract, Part i. p. 283, Amer. edit., New York, 1845. OF THE KIDNEYS. I. Water, 963-00 11. 956-000 Solid constituents, 36-20 44-00 Urea, .... 12-46 14-578 Uric acid, .... 0-52 0-710 Alcohol extract and lactic acid, 5-10 4-800 Spi)-it extract. 2-60 5-593 Water extract and mucus, . 1-00 2-550 Lactate of ammonia. 1-03 Chloride of ammonium. 0-41 Chloride of sodium. 5-20 7-280 Sulphate of potassa, 3-00 3-508 Phosphate of soda, 2-41 2-330 Earthy phosphates, 0-58 0-654 Silica, .... a trace a trace 569 M. Becquerel's analysis,^ whicli has been adopted by Dr. Prout, by Dr. Golding Bird,^ is as follows : — and Water, Urea, Uric acid, . Colouring matter. Mucus and animal extractive matter, r Salts. Sulphates, Biphosphates, inseparable from each other, 1 ( Soda, ( Potash, (Lime, Soda, Magnesia, Ammonia, f Sodium, ( Potassium, Chlorides, Hippurate of soda, , Fluoride of potassium, Silica, . 967 14-230 •468 10-167 8-135 traces 1000-000' The yellowisli-red incrustation, deposited on the sides of chamber utensils, is chiefly urate of ammonia. This is the basis of one of the varieties of calculi. The following is the proportion, which each principal constituent bears to 100 of solid residuum, accordino- to dilYerent observers.* Berzelius. Lelinianu. Simon. Marcliard Urea, 45-10 49-68 33-80 48-91 Uric acid, 1-50 1-61 1-40 1-59 Extractive matter, ammonia salts and chloride of sodium. 36-30 28-95 42-60 32-49 Alkaline sulphates, . 10-30 11-58 11-14 10-18 Alkaline phosphates. 6-88 5-96 6-50 4-57 Phosphates of lime and magnesia, 1-50 1-97 1-59 1-81 ' Semeiotique des Urines, p. 7, Paris, 1841. An analysis of tlie urine of the two sexes is given by him in his Traite de Cliimie Pathologique Ajiplitjuee a la Medecine, p. 270, Paris, 1854; and an elaborate analysis after M. Robin is given in Beraud, Manuel de Physiologic de I'Homme, p. 232, Paris, 1853. ^ On the Nature and Treatment of Stomach and Renal Diseases, 4th edit., Amer. edit., p. 404, Philad., 1843. ^ Urinary Deposits, Amer. edit., p. 44, Philad., 1845. * See art. Urine, by Dr. Geo. Rees, in Cycl. of Anat. and Phys., iv. 1272, Lond., 1852. ^ Carpenter, Principles of Human Physiology, Amer. edit., p. 391, Philad., 1854. 570 SECRETION The quantity of urine passed in the twenty-four hours is variable. Boissier states it at 22 ounces; Hartmann at 28; Dr. Robert Willis' at from 30 to 40 ; Prout at about 30 in summer, and 40 in winter ; Robinson at 35; Von Gorter at 36; Keill at 38; Rye at 39; Bostock at 40; Sanctorius at 44; Stark at 46; Dalton at 48 J; Haller at 49 ; Christison .at from 35 to 50; Becquerel at about 46; Dr. Thomas Thomson at 53; Vogel at about 54, and Lining at from 56 to 59 ounces. On the average, it may be estimated perhaps at two pounds and a-half ; hence the cause of the great size of the renal artery, which, according to the estimate of Haller, conveys to the kidney a sixth or eighth part of the whole blood. Its quantity and character differ according to age, and, to a certain extent, according to sex. We have already seen, under the head of cutaneoiLs exhalation^ how it varies, according to climate and season; and it is inflaenced by the serous, pulmonary, and areolar exhalations likewise : one of the almost inva- riable concomitants of dropsy is diminution of the renal secretion. Its character, too, is modified by the nature of the substances received into the blood. Rhubarb, turpentine, and asparagus, for example, alter its physical properties ; whilst certain articles stimulate the kidney to augmented secretion, or are " diuretics." The renal secretion may be considered as arising from different sources. When much fluid is taken, the amount of the urine is largely augmented, so that it is manifestly intended to remove superfluous fluid from the blood. It is also, as just shown, materially modified by certain ingesta; and not unfrequently the character of the food taken may be detected in it; hence, it has been conceived, the kidneys may have the duty of removing from the system any crude or undigested elements of the food, which had been absorbed whilst traversing the small intestine, and entered the circidating mass; and of excreting the often noxious results of imperfect or unhealthy assimilation. Leh- mann^ instituted a series of experiments on himself, which afforded interesting information in regard to the varying composition of the urine, according as an animal, a vegetable, a mixed, or a non-nitro- genized diet was employed. On the mixed diet he lived fifteen days; ate and drank moderately ; and abstained from all fermented liquors. He took an exclusively animal diet for twelve days, consuming thirt}'- two eggs each day. A purely vegetable diet was also continued for twelve days; but the non-nitrogenized was only taken for two days. In the following table the quantities of solid matter passed daily are represented by grammes (about 15|- grains troy each); and also the proportional amount of salts and animal matter in that quantity of solid matter. Extractive Solid matter. Urea. TJric acid. Uric salts. matters. Mixed diet . . 67-82 32-41)8 1-183 2-257 10-489 Animal diet . . 87-44 53-198 1-478 2-167 5-145 Vegetable diet . . 59-24 22-481 1-021 2-669 16-499 Nou-nitrogenized diet 41-68 15-408 0-735 5-276 11-854 ' Urinary Diseases and tlieir Treatment, Bell's Library edit., p. 14, Philad., 1839. ^ L'Experience, 7 Dec, 1843; cited in Edinb. Med. and Surg. Journal, April, 1844, and Art. Harn, Handworterbuch der Physiologie, 7te Liel'erung, S. 16, Braunscliweig, 1844; and Lelirbuch der Physiolog. Cliemie, ii. 447, Leipzig, 1850; or Amer. edit, of Dr. Day's translation by Dr. Robt. E. Rogers, ii. 163, Philad., 1855. OF THE KIDNEYS. 571 Lelimann's results certainly show; — first^ that animal food increases the solid matters in the urine, whilst vegetable substances, and espe- cially non-nitrogen ized aliments, diminish them: — secondly^ that the proportion of nitrogen in the urine depends in part upon the kind of food taken, — food rich in nitrogen greatly increasing its amount. In his experiments, the proportion of urea to the other solid matters was as 100 to 116 under a mixed diet; as 100 to 63 under an ammal diet; as 100 to 156 under a vegetable diet; and as 100 to 170 under a non-nitrogenized diet: thirdly^ that the proportion of uric acid in the urine did not appear to have reference to the kind of food : — -fourthly^ that the urine contained quantities of sulphates and phosphates pro- portioned to the quantity of nitrogenized matters that had been ab- sorbed : and, fifthly^ that under an animal diet the quantity of extractive matters diminishes ; whilst it is increased by the use of vegetable diet. These extractive matters contained, according to the researches of Liebig,' krealine and kreatinine^ two substances presumed to be derived from the metamorphosis of muscular tissues, and also a peculiar colouring matter derived probably from the hematin of the blood. Experiments by Dr. H. Bence Jones^ confirm those of Lehmann in certain respects. They show, that all food causes an increase in the amount of uric acid excreted ; but that there is no great difference between animal and vegetable food in the production of such increase. The urine does not appear to be intended for any local function. Its use seems to be restricted to the removal from the blood of the elements of the substances of which it is composed ; hence, it is solely depuratory and decomposing. IIow this decomposition is accom- plished we know not. We have already referred to the experiments, performed by MM. Prevost and Dumas, Segalas, Gmelin, Tiedemann and Mitscherlich, in which urea was found in the blood of animals whose kidneys had been extirpated: an inquiry has consequently arisen — how it exists there? Prior to these experiments, it was uni- versally believed, that its formation is one of the mysterious functions executed in the intimate tissue of the kidney. It is proper to add, however, that neither MM. Prevost and Dumas, Tiedemann and Gmelin, nor M. Lecanu^ could detect the smallest trace of this substance in the blood of animals placed under ordinary circumstances. It is now, however, admitted, that it exists there normally, but in very small quantity. It is, according to Wohler and Easpail, a cyanate of ammonia, and contains a very large proportion of nitrogen. The kidney is the outlet for an excess of nitrogen in the system in the same manner as the lungs and liver are outlets for superfluous carbon. The quantity of nitrogen, discharged in the form of urea, is so great, even in those animals whose food does not essentially con- tain this element, that it has been conceived a necessary ingredient in the nutrition of parts, and especially in the formation of fibrin, which is a chief constituent of the blood, and of every muscular organ. The remarks made on the absorption of nitrogen during respiration indi- cate one mode in which it is received into the system ; and it has been ' Chemistry of Food, Lond., 1847. 2 Philosophical Transactions, Pt. 2, for 1849. ^ Etudes Cliiuiiciues sur le Sang Humam, Paris, 1837. 572 SECRETION, presumed, tliat the superfluous portion is thrown off in the form of urea. There are three great modes in which the nitrogen thrown off by the urine may be obtained: first^ from the air of respiration; se- condly^ from the food; for compounds of protein are absorbed from the intestinal canal ; and the nitrogen which is not required for the wants of the system is thrown off from the kidneys in the form of urea and uric acid; and thirdly^ in the disintegration of the tissues constantly occurring in the system of nutrition. Whilst certain of the elements that are superfluous are thrown off' by the lungs and liver, the kidneys separate and throw off the superfluous nitrogen. From the results of Dr. Lehmann's experiments, it has been inferred, that so long as the iugesta contain no nitrogen, the whole of that element in the urine must be attributed to the disintegration or waste of the tis- sues, and may fairly be taken as a measure of its amount. This, how- ever, is by no means established. We have no positive proof that the nitrogen received into the circulation in respiration is foreign to the formation of the nitrogenized compounds contained in the urine. It has been found in the urine of man after long fasting ; and in that of reptiles, which had not taken food for months. Besides serving as an outlet for the superfluous nitrogen, there is no question, that the ex- cess of the sulphur and phosphorus, which have become oxidized in the organism, and converted into sulphates and phosphates by a union with bases, is removed from the system through the urinary secretion. The whole subject of the urine in its chemical and chemico-ph}sio- logical, and chemico-pathological history is full of interest ; and hence the attention paid to it at this time everywhere by the chemists espe- cially, who have sufficiently shown that the determination of its exact constitution is one of the most abstruse subjects of organic chemistry.'^ The removal of the constituents of the urinary secretion from the blood is all-important. Experiments on animals have shown, that if it be suppressed by any cause for about three da^^s, death usually supervenes, and the dangers to man are equally imminent. Yet there are some strange cases of protracted suppression on record. Haller mentions a case in which no urine had been secreted for twenty-two weeks ; and Dr. liichardson,^ one of a lad of seventeen, who had never made any, and yet felt no inconvenience. a. Connexion heticeen the Stomach and Kidneys. In consequence of the rapidity with which fluids received into the stomach are sometimes voided by the urinary organs, it has been ima- gined, either that vessels exist, which communicate directly between ' For the recent investigations of R. Bunsen, Millon, Marcliard, Allan and Hensch, "nard and Barreswil, Strahl and N. Lioberkuhn, WiJliler and Frerichs, &c., see ver, in Canstatt and Eisenniann's Jaliresbericht iiber die Forts cliritte in der Bio- i^^ie im Jalire, 1848, S. 88 ; W. Mareet, in a Notice of tlie Traite de Chiniie Anato- mique, &c., of Robin and Verdeil, in Brit, and For. Medico-Cliir. Rev., April, 1853, p. 358; and for the investigations of Prof. J. Vogel, Dr. Fr. Beneke and others'; see Gerber, Ibid., for July, 1855, p. 71 ; Becquerel and Rodier, Traite de Cliiinie Fatholo- gique, &c., p. 267, Paris, 1854, and Lehniann, Lehrbuch der Physiolopisclien C'hemie, S. 387, Leipz., 1850; or Amer. edit, of Dr. Day's translation by Dr. Robt. E. Rogers, ii. 106, Philad., 1855. ' Philos. Transact, for 1713. CONNEXION BETWEEN THE STOMACH AND KIDNEYS. 573 the stomacli and bladder, or tliat the fluid passes through the interme- diate areolar tissue, or through the anastomoses of lymphatics. Ex- periments of Mr. Erichsen,^ which consisted in introducing certain substances, that are readily detected by appropriate tests, into the stomach, and noting their appearance in the urine, signally exhibit the rapidity of this transmission. The earliest period at which prus- siate of potassa was detected was about one minute after being swal- lowed; and the longest, thirty-nine minutes, — the difference aippearing to depend upon the presence or absence of food in the stomach at the time. When it was empty, the salt was discovered in from one to two and a half minutes; whilst soon after a meal it required from six and a half to thirty-nine minutes. In support of the opinion, that a more direct passage exists, the assertion of M. Chirac, — that he saw the urinary bladder become filled with urine when the ureters were tied, and that he excited urinous vomiting by tying the renal arteries, — is brought forward. It has been farther affirmed, that the oil, composing a glyster, has been found in the bladder. Dr. Darwin,^ having administered to a friend a few grains of nitrate of potassa, collected his urine at the expiration of half an hour, and had him bled. The salt was found in the urine, but not in the blood. Mr. Brande made similar experiments with prus- siate of potassa, from which he inferred, that the circulation is not the only medium of communication between the stomach and urinary organs, without, however, indicating the nature of the supposed me- dium; and this view is embraced by Sir Everard Home,^ and Drs. Wollaston, Marcet, and others. Lippi,"* of Florence, thinks he_ has found an anatomical explanation of the fact. According to him, the chyliferous vessels have not only numerous inosculations with the mesenteric veins, either before their entrance into the mesenteric glands, or whilst they traverse those organs ; but, when they attain the last of them, some proceed to open directly into the renal veins, and into the pelves of the kidneys. At this place, according to him, the chyliferous vessels divide into two sets ; the one, ascending, and conveying the chyle into the thoracic duct ; the other, descending, and carrying drinks into the renal veins and pelves of the kidneys. He affirms, that the distinction between the two sets is so marked, that an injection sent into the former goes exclusively into the thoracic duct, whilst if it be thrown into the latter it passes exclusively to the kid- neys. These direct vessels Lippi calls vasa chylopoietica urinifera. A kindred and equally inconceivable view has been recently main- tained by M. C. Bernard,^ who affirms, that when he introduced prus- siate of potassa into the intestine of an animal, he recognized it sooner in the renal vein than in the renal arter}'. To account for this he insti- tuted a series of researches, from which he concludes, that liquids ' Dublin Medical Press, July 0, 1845, aud Raiiking's Abstract, Part ii. p. 241, Amer. edit., New York, 184(j. ^ Zoonomia, xxix. 3. * Philosophical Transactions, xcviii. 51, and ci. 163, for 1808 and 1811 ; and Lec- tures on Comparative Anatomy, i. 221, Lond., 1814 ; and iii. 138, Lond., 1823. * lUustrazioni Fisiologiche e Patologiche del Sistema Linfatico-Chilifero, &c.,Firenz, 1825. * Union Medicale, No. 116, cited in British and Foreign Medico-Chirurgical Review, for Jan., 1850, p. 246. 674 SECRETION. absorbed from the intestines, after passing through the portal system and arriving in the vena cava, instead of ascending towards the heart, descend into the renal veins, which conve}'- them to the renal capilla- ries; so that a considerable portion of them is eliminated without pass- ing into the general current of the circulation. In regard to the assertions of Lippi, were they anatomical facts, it would obviously be difficult to doubt some of the deductions; other anatomists have not, however, been so fortunate as he ; and, con- sequently, it may be well to make a few comments. Yet — as has been elsewhere seen — the communication between the abdominal lymphatics and veins has been maintained by Dr. Nuhn.' Some of these chylopoietica urinifera, Lippi affirms, open into the renal veins. This arrangement, it is obvious, cannot be invoked to account for the shorter route — the royal road to the kidney. The renal vessel conveys the blood back/ro77i the kidney, and every thing that reaches it from the intestines must necessarily pass intp the vena cava, and ultimately attain the kidney through the renal artery. The vessels, therefore, that end in the renal veins, must be put entirely out of the question, so far as regards the topic in dispute; and attention be con- centrated upon those that terminate in the pelvis of the kidney. Were this termination proved, we should be compelled, as we have remarked, to bow to facts ; but not having been so, it may be stated as seem- ino-ly improbable, that the ducts in question should take the circuitous course to the pelvis of the kidney, instead of the direct one to the bladder. We know, then, nothing anatomically of any canal between the sto- mach and bladder ; and have not the slightest evidence — positive or relative — in favour of the opinion, that there is any transmission of fluid through the intermediate areolar tissue. There is, indeed, absolute testimony against it. ]SOI. Tiedemann and Gmelin having examined the lymphatics and areolar tissue of the abdomen, in cases where they had administered indigo and essence of turpentine to animals, discovered no traces whatever of them, whilst they could be detected in the kidney. The fcvcts^ again, referred to by Chirac, are doubtful. If the renal arteries be tied, the secretion cannot be effected; yet, as we have seen, in the case of extirpated kidneys, urea may exist in the blood, and, consequently, urinous vomiting be possible. If the ureters be tied, the secretion being practicable, death will occur if the suppression be pro- tracted; and, in such case, the secreted fluid may pass into the vessels, and readily give a urinous character to the perspiration, vomited mat- ters, &c,, &c. The experiments of Darwin, Brande, Wollaston, and others only demonstrate, that these gentlemen were unable to detect in the blood that which they found in the urine. Against the negative results attained by these gentlemen, we may adduce the positive testi- mony of M. Fodera,^ an experimentalist of weight, especially on those matters. lie introduced into the bladder of a rabbit a plugged cathe- ter, and tied the penis upon the instrument to prevent the urine from flowing along its sides. He then injected into the stomach a solution ' Page 241. 2 Reclierclies Experimentales sur TAbsorption et I'Exlialation, Paris, 1824. VASCULAK OR DUCTLESS GLANDS. 575 of ferrocyanuret of potassium. This being done, he frequently re- moved the plug of the catheter, and received the drops of urine on filter- ing paper. As soon as indications of the presence of the salt appeared in the urine by the appropriate tests, — which usually required from five to ten minutes after its reception into the stomach, — the animal was killed; and on examining the blood, the salt was found in the serum taken from the thoracic portion of the vena cava inferior, right and left cavities of the heart, aorta, thoracic duct, mesenteric glands, kidneys, joints, and mucous membrane of the bronchia. M. Magendie,^ too, states, as the result of his experiments, — First. That whenever prus- siate of potassa is injected into the veins, or is exposed to absorption in the intestinal canal, or in a serous cavity, it speedily passes into the bladder, where it can be readily recognised in the urine. Secondly. That if the quantity of prussiate injected be considerable it can be detected in the blood by reagents; but if it be small, it is impossible to discover it by the ordinary means. Thirdly. That the same thing happens if the prussiate of potassa be mixed with the blood out of the body. Fourthly. That the salt can be detected in the urine in every proportion. We may conclude, therefore, with Dr. Hale,^ who has written an interesting paper on this subject, that the existence of any more direct route from the stomach to the bladder than the circulatory S3'stem and the kidneys is disproved; and we must consider the absorption of fluids to be effected through the vessels described under Absorption of Drinks, The facts, referred to elsewhere, (p. 487,) which show the extreme rapidity of the circulation, materially facilitate our comprehension of these cases. Such are the glandular secretions to be considered in this place. There are still two important secretions — 7. Secretion of the Testes^ and 8. Secretion of the Mammce^ which will be investigated under the Functions of Eeproduction, IV. VASCULAR OR DUCTLESS GLANDS. There are several organs, — as the spleen, thyroid, thymus, and supra- renal capsules, — which are termed glands — vascular glands^ bloody or ductless glands^ by many anatomists; but by M. Chaussier glandiform ganglions. Of the uses of these we know little. Yet it is necessary that the nature of the organs and their presumed functions should meet with notice. The offices of the thyroid, thymus, and supra-renal cap- sules, — being chiefly confined to foetal existence, — will not require consideration here. Although they have no ducts, their minute ar- rangement greatly resembles that of the true glands; and they are all perhaps concerned, in some manner, in hoematosis or the due elabo- ration of the circulating fluid.^ It has been elsewhere seen, that the ' Precis, &c., ii, 477. 2 Boylston Prize Dissertation for the years 1819 and 1821, Boston, 1821, ' See, on the vvliole subject of the vascular glands, Ecker's elaborate article Blutgefiiss- driisen, in Wagner's Handworterbuch der Physiologie, iv, 1U7, Braunschweig. 1853. 576 VASCULAR OR DUCTLESS GLANDS. glands of Peycr may be classed under this head ; and Ecker adds the pituitary gland of the brain,' a. The Spleen. The spleen is a viscus of considerable size, situate in the left hypo- chondriac region (Fig. 155), beneath the diaphragm, above the left kidney, and to the left of the stomach. Its medium length is about four and a half inches; its thickness two and a half, and its weight about eight ounces.^ Its absolute weight, and its weight in proportion to that of the whole body, increases rapidly, according to Huschke, after birth; and its proportionate weight soon attains its highest stand- ard, so that, in the adult, it has not a decidedly greater proportion to the body than at birth; and in some cases even decreases. It varies between 1 to 235 and 1 to 240.^ Its relation to the weight of the liver is proportionally greater in the adult than in the infant. It is of a soft texture, somewhat spongy to the feel, and easily torn ; and in a very recent subject is of a grayish-blue colour; which, in a few hours, changes to purple, so that it resembles a mass of clotted blood. At its inner surface, or that which faces the stomach and kidney, a fissure exists, by which the vessels, nerves, &c., enter or issue from the organ. The histology of the spleen has been much investigated of late. Its main anatomical elements have been considered to be: — 1, The spdeydc artery^ which arises from the coeliac, and after having given off branches to the pancreas and the left gastro-epiploic artery divides into several branches, which enter the spleen at the fissure, and ramify in the tissue of the organ; so that it seems to be exclusively formed by them. Whilst the branches of the artery are still in the duplicature of the gastro- splenic omentum, and before they ramify in the spleen, they furnish the vasa brevia to the stomach. The precise mode of termination of the arteries in the spleen is unknown : their communication with the veins does not, however, appear to be as free as in other parts of the body, nor the anastomoses between the minute arteries as numerous. If, according to Assolant,'' one of the branches of the splenic artery be tied, the portion of the spleen to which it is distributed dies; and if air be injected into one of these branches, it does not pass into the other; so that the spleen would appear to be a congeries of several distinct lobes; and in certain animals the lobes are so separated as to constitute several spleens. A similar appearance is occasional!}^ seen in the human subject. 2. The splenic vein arises by numerous radicles in the tissue of the spleen : these become gradually larger, and less numerous, and leave the fissure of the spleen by three or four trunks, which ultimately unite with veins from the stomach and pancreas to form one, that opens into the vena porta. It is without valves, and its parietes are thin. These are the chief constituents. 8. Lympihaiic vessels, which are large and numerous. 4. Nerves, proceeding from the coeliac plexus: they creep along the coats of the splenic artery — upon which they form an ' Op. cit., S. 160. 2 Gross, Elements of Pathological Anatomy, 2d edit., p. 674, Philad., 1845. 3 The French translation of Jourdan says between 1 to 235 and 1 to 400, — Encyclop. Anatom., v. 172, Paris, 1845. •* llecherches sur la Rate, Pai'is, 1801. SPLEEN. 577 Fig. 182. intricate plexus — into the substance of the spleen. 5. Areolar tissue, which serves as a bond of union between these various parts ; but is in extremely small quantity, 6. A j^roper memhrcme, which envelopes the organ externall}^; adheres closely to it, and furnishes fibrous sheaths to the ramifications of the artery and vein; keeping the ramifications separated from the tissue of the organ, and sending prolongations into the parenchyma, which gives it more of a reticulated than a spongy aspect. 7. Of hhod^ according to many anatomists; but blood differing from that of both the splenic artery and vein, — houe splenique, contain- ing, according to M. Vauquelin, less colouring matter and fibrin, and more albumen and gelatin, than any other kind of blood. This, by stagnating in the organ, is conceived to form an integrant part of it, Malpighi^ believed it to be contained in cells; but others have supposed it to be situate in a capillary system intermediate between the splenic artery and vein, Assolant and Meckel' believe, that the blood is in a peculiar state of combination and of intimate union with the other organic elements of the viscus, and with a large quantity of albumen ; and that this com- bination of the blood forms the dark brown pulpy substance, contained in the cells formed by the proper coat, and which can be easily demon- strated by tearing or cutting the spleen, and scraping it with the handle of a knife. These cells and the character of the tissue of the spleen are exhibited in the marginal figure (Fig, 182). In addition to the pulp, there is an abund- ance of rounded corpuscles, varying in size from an almost imperceptible mag- nitude to a line or more in diameter. By Malpighi, these were conceived to be granular corpuscles, and, by Ruysch,^ simply convoluted vessels, M, AndraP affirms, that by repeated washings the spleen is shown to consist of an infinite number of cells, which communicate with each other, and with the splenic veins. The latter, when the inner surface of the large subdivisions of the splenic veins are examined, appear to have a great number of perforations, through which a probe passes directly into the cells of the organ. The farther the subdivisions of the vein examined are from the trunk, the larger are these perforations ; and still farther on, the coats of the vein are not a continuous surface, bat are split into filaments, which do not differ from those forming the cells, and are continuous with them. M. Bour- Section of the Spleen. ' Op. Omnia, jmrs ii., Loud., 1(587 ; and Op. Postlium., p. 42, Lond., 1097. 2 llandbuch, &c., traduit par Jourdan, iii. 47li, Paris, 1825. ^ Meckel, op. citat. * Precis d'Anatouiie Pathologique, torn. ii. part i. p. 416, Paris, 1832. VOL. L — '61 578 VASCULAR OR DUCTLESS GLAXDS. gery has maintained, that the fibrous envelope of the spleen sends off a multitude of lamellte, which penetrate its interior, forming irregular spaces of unequal dimensions. These short spaces he calls splew'c vesi- cles. In the septa, a number of lymphatic glands exists. The capillaries of the arteries communicate directly with those of the veins; but, accord- ing to M. Bourgery, there are, in addition, veins with patulous orifices. The interior of the vesicles is filled with a soft substance of a deep red colour, in which the small white corpuscles, discovered by Malpighi, are suspended. M. MandP suggests, that the white corpuscles may be analogous to the intestinal villi, in which the lymphatics originate by a ca^cal extremity. The minute structure of the spleen has been intimately investigated by Dr. Evans,^ and by Professor Kolliker,'' and still more recently by Dr. Sanders,-* Mr. Wharton Jones,* Mr. Huxley,^ Mr. Gray,^ Giins- burg, Fiihrer,* and others. The organ, according to Ktilliker, is essen- tially composed of a fibrous membrane, formed of white fibrous tissue, and in many of the lower animals having unstriped muscular fibres intermixed,^ which constitutes its exterior envelope, and sends trabe- cular prolongations in all directions across its interior, so as to divide it into a number of irregularly shaped splenic cells, communicating freely with each other and with the splenic vein, and lined by a mem- brane continuous with that of the vein, which is so reflected upon itself as to leave oval or circular foramina, by which each cell com- municates with the others and the vein. The diameter of these cells is estimated at from one-third to half a line, and they are generally traversed by filaments of elastic tissue, imbedded in which a minute artery and vein may frequently be observed. Over these filaments the lining membrane is reflected in folds; so that each cell is thus in- completely divided into two or more small compartments. No direct communication exists between the splenic artery and the interior of the cells; but its branches are distributed through the intercellular parenchyma, and the small veins, which collect the blood from the arterial capillaries of the organ, carry it into the cells whence it is con- veyed away by the splenic vein. The cells may be readily injected from the vein with either air or liquid, provided they are not filled ' Manuel d'Anatomie Generale, p. 518, Paris, 1843. 2 Lancet, April 6, 1844. ' Mittlieilungen der Ziiricher Naturforsclienden Gesellschaft vora Jahre 1847 ; Art. Spleen, Cyclopredia of Anatomy and Physiology, pts. xxxvi. and xxxvii., June and October, 1849; and Kolliker, Mikroskopisclie Anatomife, ii. 253. Leipzig, 1852; or Anier. edit, of the translation of his Manual of Histology, by Dr. Da Costa, p. 551, Philad., 1854. ■* Goodsir's Annals of Anatomy and Physiology, No. 1, p. 49, Feb., 1850. 5 Brit, and For. Med.-Chir. Rev., Jan., 1853, p. 275. ® Quarterly Journal of Microscopical Science, ii. 74, London, 1854; and Kijlliker's Manual of Histology, Amer. edit, by Dr. Da Costa, p. 786, Philad., 1854. ' Th(; Structure and Use of the Spleen, Loud., 1854. 8 Cited in Canstatt's Jahresbericht, im Jahre 1854, ler Bd. S. 72. 9 Sharpey, in Quain and Shai-pey's edition of Quain's Human Anatomy, by Leidy, ii. 498, Pliilad., 1849, Kolliker, op. citat. ; and Ecker, art. Blutgefassdriisen, Wagner's Handwilrterbuch der Physiologie, 23ste Lieferung, S. 132, Braunschweig, 1849. Ma- zoun states tlaat the covering and trabecular tissue of the organ in man contain mus- cular fibre. — Miiller's Archiv., i. 25, Berlin, 1854; and J. W. Ogle, Report on Micro- logy in Brit, and For. Med.-Chir. Rev., Oct., 1855, p. 530. SPLEEN. 579 Avith coagulated blood; and they are so distensible — as has been long- known — that the organ may be made, with very little force, to dilate to many times its original size. The cells of the spleen, according to Dr. Evans, never contain any thing but blood; and a frequent appear- ance after death is that of firmly coagulated blood filling them, and giving a granular aspect to the organ, which is sometimes described as morbid. The partitions between the cells are formed by the mem- branes already mentioned, and by the proper parenchyma of the spleen. To the eye it has a semi-fluid appearance, but when an attempt is made to tear it, considerable resistance is experienced, in consequence of its being intersected by what seem to be minute fibres. When a small portion is pressed, a liquid exudes — liquor Uenis or splenic blood — which is usually described as filling the cells of the spleen; but ac- cording to Dr. Evans this is erroneous. This liquid, when diluted with serum, and examined under the microscope, is found to contain two kinds of corpuscles, — one apparently identical with ordinary blood corpuscles — the other with the corpuscles characteristic of lymph, and abundant in the lymphatic ganglions. The remaining fibrous sabstance consists wholly of capillary bloodvessels and lymphatics with minute corpuscles, much smaller than blood corpuscles, varying in size from about gy'^Qth to ^^^'g^th of an inch, of spherical form, and usually corrugated on the surface. These lie in great numbers in the meshes of the sanguiferous capillaries; and the minute lymphatics are described by Dr. Evans as connected with the splenic corpuscles, and apparently arising from them. Lying in the midst of the parenchyma is a large number of bodies, of about a third of a line in diameter, which are evidently in close connexion with the vascular system. These are the Malpighian bodies of the spleen or splenic corpuscles. According to Dr. Evans, they, in all respects, resemble mesenteric or lymphatic ganglions in miniature — consisting, as they do, of convo- luted masses of bloodvessels and lymphatics, united together by elastic tissue, so as to possess considerable firmness ; and they farther corre- spond with them in this, — that the lymph they contain, which is quite transparent in the ailerent vessels, becomes somewhat milky, from containing a large number of lymph corpuscles. Professor Kolliker describes the spaces left by the trabecular })ro- longations as of irregular form and size, and occupied by the peculiar splenic or Mal'pighian corpuscles^ and the splenic parenchyma. These corpuscles, according to him, are whitish spherical bodies, imbedded in the parenchyma of the spleen, but connected with the smaller arte- ries by short peduncles in a racemose manner. They are seldom seen in the human subject, owing to the rapid changes they undergo after death ; but Professor Kolliker has no doubt of their being invarial)ly present in health. lie affirms, that they have no relation to the lymphatics; but are closed capsules, resembling the elementary cells of glands before the rupture of their walls. The red spleen substance, spleen pulp ot parenchyma of the spleen, consists in great part of cells, which correspond in appearance with those of the Malpighian corpuscles. Two other kinds, however, occur in it seldom met with in the latter ; and numerous free nuclei are also present. Of these, one set bears a strong resemblance to red blood corpuscles; the others are pale with 580 VASCULAR OPw DUCTLESS GLANDS. one or two nuclei, or colourless granule cells. A considerable part of the pulp appears to consist of blood corpuscles in various stages of metamorphosis, as was first taught bj Professor Kolliker. "The blood globules'" — he remarks — "first become at once smaller and darker, whilst the elliptical cor- Fig. 183. puscles of the lower vertebrata also become rounder; then, in connection with some blood plas- ma, they become aggregated into small round heaps ; which heaps, by the appearance of an interior nucleus and of an outer mem- brane, experience a transition into spherical cells containing blood corpuscles. These are from 5-lOOOths to 15-lOOOths of a line in size, and contain from one to twenty blood corpuscles. During this time, the blood cor- puscles arecontinuall}^ diminish- ing in size; and, assuming a golden }^llow, brownish red or dark colour, they undergo, either immediately, or after a previous dissolution, a complete transi- tion into pigment granules. So that these cells themselves are changed into pigmentary granule cells; and finally, by a gradual loss of colour of their granules, they form themselves into completely colourless cells."^ These are found in the blood, especially of the splenic vein, vena porta and inferior cava. It is not, however, easy to see how the corpuscles can leave the splenic arteries, unless they have a direct open communication with the splenic pulp, which is not admitted. Professor Kolliker describes the arterial branches as ramifying in the red spleen substance, where each twig subdivides into smaller and smaller arteries, and, when they become capillary, constitute a close and beautiful network in the splenic pulp. Gieskei',^ however, considers that the pulp consists of nothing but the minutest arteries and veins united by fibrous tissue. The whole subject, however, of splenic histology appears to the author to be far from determined, and to demand fresh investigations. Besides the proper membrane, the spleen receives also a peritoneal coat; and, between the stomach and it, the peritoneum forms the gas- tro-s2')Ien'c ep/plooji or . Pyramid, r. Uvula, n, n. Amygdalie. s. Nodule, or laminated tubercle, x. Posterior velum, partly seen. ?«. Eight and left hemispheres of cerebellum. 3 to 7. Nerves. 3, .3. Motores oculorum. ,5. Trigeminal. 6. Abducent nerve. 7. Facial and auditory nerves. Fig. 191. Posterior Superior View of the Pons Varolii, Cere- bellum, and Medulla Oblongata and M. Spinalis. 1, 1. Crura cerebri. 2. Pons Varolii or tuber annulare. 3. Its middle fossa. 4. Oblique band of medullary matter seen passing from its side. 5. External surface of the crus cerebelli. 6. Same portion deprived of outer layer. 7. Nervous matter which unites it to \. S. Trigeminus or fifth pair of nerves. 9. Portion of the auditory nerve. The white neurine seen passing from the oblique band which comes from the corpus restiforme to the trigeminus nerve in front, and the auditory nerve behind. 10, 11. Superior portion of the hemispheres of the cereliellum. 12. Lobulus amygdaloides. 13. Corpus olivare. 14. Corpus pyramidale. 15. Medulla spinalis. pass downwards to the motor tract of the the commissural fibres, which establish rious parts of the periphery, and of the below the fornix, is another cavity — the third ventncle. Its bottom is very near the base of the brain, and is fornisd by the nervous layer which unites the peduncles of the brain with the eminentiae mammillares. At the sides, it has the thalami nervorum opticorum. In the lateral ventricles, situate on each side of the corpus callosum, some j^arts exist which demand atten- tion. In the upper or ante- rior half, commonly called anterior cornu, and in the an- terior part of this, two pyri- form eminences are seen, (^f a brownish-gray colour, which, owing to their being formed of an assemblage of alternate layers of white and gray sub- stance, are called coiyora stri- ata, the anterior cerebral gan- glio7is of Mr. Solly. Behind these, are two whitish medul- lary bodies called thalami nervorum opticorum — posterior cerebral ganglions — which are situate before the corpora quadrigemina, and envelope the anterior extremities of the crura cerebri. Three main sets of fibres may be distinguished in the medullary substance, of which the great mass of the cere- brum is composed. First, the ascending fibres, which pro- ceed from the sensory tract of the medulla spinalis, and diverge from the thalami op- tici to the periphery of the brain; secondly, the descend- ing fibres, which converge from the periphery towards the corpora striata, and then medulla spinalis; and, thirdly^ a connexion between the va- substance of the brain. The CEREBELLUM. 635 bulk of the human brain, and of that of the higher animals, is greatly dependent upon the large proportion borne by these last fibres to the rest.* The cerebellum occupies the lower occipital foss£e, or the whole of the cavity of the cranium beneath the tentorium cerebelli. It consists of two lateral hemispheres or lobes, composed of a peculiar arrangement of vesicular and tubular substance ; and of a central lobe, composed also of these substances, and known by the name of the icorm or vermiform process. Its size and weight, like those of the brain, differ according to the individual, and the age of the subject under examination. We do Fig. 192. Analytical Diagram of the Encephalon — it) a Vertical Section. S. Spinal cord. r. Restiform bodies passing to c, tlie cerebellum, d. Corpus dentatum of the cerebel- lum, o. Olivary body. /. Columns continuous -with the olivary bodies and central part of the medulla oblongata, and ascending to the tubercula quadrigemina and optic thalami. p. Anterior pyramids, v. Pons Varolii, n, h. Tubercula quadrigemina. g. Geniculate body of the optic thalamus, t. Processus cerebelli ad testes, a. Anterior lobe of the brain, q. Posterior lobe of the brain. not observe convolutions in it. It appears rather to consist of laminas in superposition, separated from each other by furrows. We shall see, ' Carpenter, Human Physiology, p. 215, Lond., 1842. 636 SENSIBILITY. hereafter, that the number of cerebral convolutions has been esteemed, in some respects, to accord with the intellect of the individual; and Malacarne asserts, that he has observed a similar correspondence, as regards the number of laminte composing the cerebellum; that he found only three hundred and twenty-four in the cerebellum of an insane in- dividual; whilst in others he had counted upwards of eight hundred. From the medullary part of the cerebellum, two large white cords pass to the pons Varolii, having the same disposition as the crura cerebri. They are the crura cerebelli. Owing to the peculiar arrangement of the white and gray cerebral substances, when one of the hemispheres of the cerebellum is divided vertically, an arborescent appearance is presented, — the trunks of the arborization being white, the surrounding substance gray. This ap- pearance is called nrhor vitce. The part where all these arborizations meet, near the centre of the cerebellum, is called corpus denticulatum seu rhomho'idaJe. Gall was of opinion, that this body has great agency in the production of the cerebellum. Lastly, the cerebellum covers the posterior part of the medulla oblongata, and forms with it a cavity, Cdlledi fourth ventricle. The medulla oblongata is so called, because it is the continuation of the medulla spinalis in the cavity of the cranium. It is likewise termed mesocephale^ from its being continuous with the spinal marrow in one direction, and sending towards the brain strong prolongations — crura Fig. 193. Fig. 194. Anterior View of the Medulla Oblongata. p, p Pyramidal bodies, dfcussating at d. o, 0. Olivary bodies, r, r. Restiform bodies. a, a. Arciform fibres, v. Lower fibres of the pons Varolii. Posterior View of the Medulla Oblongata. p, p. Posterior pyramids, separated by the posterior fissure, r, r. Restiform bodies, composed of c, c, poste- rior columns, and d,d, lateral part of the antero-lateral columns of the cord, a, a. Olivary columns, as seen on the floor of the fourth ventricle, separated by *, the me- dian fissure, and crossed by some fibres of origin of n, n, the seventh pair of nerves. cerebri; and to the cerebellum similar prolongations — crura cerebelli; so that it appears to be the bond of union between these various parts. In its lower portion, it seems to be merely a continuation of the me- MEDULLA OBLONGATA. 637 dulla spinalis, except tliat it is more expanded superiorly where it joins the pons Varolii. This portion of the medulla oblongata is called, by some, tail of the medulla oblongata; by others, the racliidian bulb; and, by others again it is regarded as the medulla oblongata. Its lower sur- face rests on the basilary gutter of the occipital bone, and exhibits a groove which divides the spinal cord into two portions. On each side of this furrow are two oblong eminences, the innermost of which is called coiyus 'pyramidale^ the outermost, corjms olivare. These oval bodies are surrounded by a superficial groove, which, in some instances, is partially interrupted by arciform fibres, which cross it at its lower part. At the lower third of the medulla oblongata, fibres of the ante- rior pyramids decussate, and form an anatomical demarcation between the medulla oblongata and the spinal cord. The decussation takes place by from three to five bundles of fibres from each pyramidal body. This decussation, as will be seen hereafter, is interesting in regard to the cross effect induced by certain diseases of the brain. On the posterior surface of the medulla oblongata, the posterior fasciculi separate to form the fourth ventricle: at the sides of this ventricle are the corpora restiformia^ or inferior peduncles of the cerebellum^ — so called because they seem to aid in the formation of that part of the encepha- lon ; and on the inner side of each corpus restiforme is the small body — i\iQ posterior pyramid. Again, in addition to the corpora pyramidalia and olivaria — which derive their origin from, or are continuous with, the anterior and lateral ftisciculi of the spinal cord, and are destined, according to some, to form the brain, — and the corpora restiformia, which are continuations of the posterior fasciculi, and are destined to form the cerebellum, there exist, according to some anatomists, other fasciculi in the rachidian bulb. All these are interesting points of anatomy, but are not of so much importance physiologically; notwith- standing even the views promulgated by Sir Charles Bell.^ lie con- siders that a column exists between the corpora olivaria and corpora restiformia, which extends below through the whole spine, but above does not proceed farther than the point where the rachidian bulb joins the tuber annulare ; and that this column gives origin to a particular oi'der of nerves — the respiratory. The corpora olivaria, and the pos- terior corpora pyramidalia, are regarded by Mr. Solly'^ as ganglia; — the former of the function of respiration, the latter of the sense of hearing. The anterior and upper half of the medulla oblongata bears the names pons Varolii^ tuber annulare^ and nodus cerebri; and to this are attached, superiorly, the corpora or tubercula quadrigemina. In the very centre of the pons, the crura cerebri bury themselves; and by many they are considered to decussate; by others, to be prolongations of the anterior column of the spinal marrow. Sir C. Bell thinks, that the pons Varolii stands in the same relation to the lateral portions of the cere- bellum, that the corpus callosum does to the cerebrum; — that it is the great commissure of the cerebellum, uniting its lateral parts, and asso- ciating the two organs. ' Thf Nervous System of the Human Borly, fiom Transactions of the Royal Society from 1821 to 1829, London, 1830; reprinted in this country, Washingtcm, 1833. * The Human Brain, its Configuration, Structure, Devehiimient, and Physiology, &c., p. 147, London, 1836. See, on this suhject. Dr. John Reid, On the Anatomy of the Me- dulla Oblongata, in Ediub. Med. and Surg. Journ., .Jan., 1841, p. 12. S38 SENSIBILITY. The medulla oblongata consists chiefly of the centres of the nerves of respiration and deglutition, which, as elsewhere shown, are strictly reflex in their action. 2. The spinal marrow extends, in the vertebral canal, from the fora- men magnum of the occipital bone above to the first or second lumbar vertebra, where it terminates in the cauda equina. Fig. 195. It is chiefly composed of medullary matter, but not P _ entirely so. Within, the cineritious substance is ranged irregularly, but has a crucial form when a section is made. The marginal illustrations exhibit sections of the spinal cord of man at different points; and the proportion of gray and white matter at each. From the calamus scriptorius in the fourth ventricle, and the rima formed by the corpora pyramidalia before, two fissures extend downwards, which divide the spinal marrow into lateral portions. The two lateral portions are divided by some into an anterior and a posterior, so that the cord is considered to have four distinct portions. It is generally, how- ever, described as consisting of three columns — an anterior^ a posterior, and a uniddle or lateral. The an- tero-lateral column, as seen in Fig. 192, is traceable through the medulla oblongata and pons Varolii to the corpora striata; and the postero-lateral to the thalami nervorum opticorum. The vertebral canal is lined by a strong liga- mentous sheath, running down its whole length. The dura mater likewise envelopes the medulla at the occipital foramen, being firmly united to the ligaments; but farther down it constitutes a separate tube. The tunica arachnoidea from the brain ad- heres loosely to the cord, having the cephalo-spinal fluid within it ; and the pia mater closely em- braces it. 3. Nerves. — The nerves are cords of the same nerv- ous substance as that which composes the encepha- lon and spinal marrow; extending from these parts, and distributed to the various organs of the body, ramids. 'b^'ai middle^ of many of them interlacing in their course, and form- between cervicaTandium^- ing plexuses: others having knots or ganglions, and buib.^"F,''Aii Tnch'ii'owen almost all vanishing in the parts to which they are F. Very near the lower distributed. The generality of English anatomists end. a. Anterior surface. . '-' p "^ . '-' p , p. Posterior surface. The rcckou thirty-nme or lorty pairs or nerves; the CruerLTudTosterior Frcuch, with morc propriety, forty-two. Of these, Iiso\e°en""' '^'^'^^''^ "^^^ uiuc, accordiug to the English — twelve, according to the French — draw their origin from, or are con- nected with, the encephalon; and are hence called encephalic nerves; and thirty or thirty-one from the medulla spinalis; and hence termed spinal. The encephalic nerves emerge from the cranium by means of foramina at its base. They are — proceeding from before to behind — the first pair or olfactory, distributed to the organ of smell: the second pair or Transverse Sections of the Spinal Cord. A. Immediately below the decussation of the py- NERVES. 639 optic^ tlie expansion of which forms the retina; the third pair, motores oculi or common oculo-m>(scidar, which send fiLaments to most of the muscles of the eye ; the fourth pair, trochleares^ ^^S- ^^^• pathetici or internal ocv,- lo-muscular, distributed to the greater oblique muscle of the eye ; the ffth p>air^ trifacial, tri- gemini or symmetri- cal nerve of the head, (Bell,) which send their branches to the eye, nose, and tongue ; the sixth pair, ahducentes or external oculo-muscular, which are distributed to the abductor or rec- tus externus oculi ; the facial nerve, portio dura of the seventh pair, nervus commimicans fa- ciei or respiratory nerve of the face, distributed to the muscles of the face; the acoustic nerve, auditory nerve or portio mollis of the seventh pair, which passes to the organ of hearing; the eiyJdh pair, p)neu- mogastric, par vagum or middle sympathetic, which is dispersed par- ticularly on the larynx, lungs, heart, and sto- mach ; the ghsso-pha- ryngeal, often consider- ed as part of the last, and whose name indicates its distribution to the tongue and pharynx ; the great hypoglossal, rdnth 2^air or lingual nerve distributed to the tongue; and the spinal accessory of Willis, which arises from the spinal cord in the cervical region ; ascends into the cranium, and issues by one of the foramina to be distributed to the muscles of the neck. All these proceed, perhaps, from the medulla oblongata ; — the brain and cerebellum not furnishing one. The thirty or thirty-one spinal nerves on each side make their exit by the intervertebral foramina, and are divided into eight cervical^ twelve dorsal, five lumhar, and five or six sacral. The encephalic nerves are irregular in their formation, and, with the exception of the fifth pair, originate from one root. Each of the Shows the under Surface or Base of the Encephalon freed from its Membranes. A, anterior, b, middle, and c, posterior lobe of cerebrum. — a. The fore part of the great longitudinal fissure, b. Notch between hemi- spheres of the cerebellum, c. Optic commissure, d. Left peduncle of cerebrum, e. Posterior perforated space, e to i. Intorpeduncular space. /, /'. Convolution of Sylvian fissure, h. Termination of gyrus fornicatus behind the Sylvian fissure, i. Infundibulum. I. Kight middle crus or peduncle of cerebellum, m, to. Hemispheres of cerebellum, n. Corpora albicantia. o. Pons Varolii, continuous at each side with middle crura of cerebellum, p. Anterior perfo- rated space, q'. Horizontal fissure of cerebellum, r. Tuber cine- reum. s, s'. Sylvian fissure, t. Left peduncle or crus of cerebrum. u, u. Optic tracts, v. Medulla oblongata, x. Marginal convolution of the longitudinal fissure.— 1 to 9 indicate the several pairs of cere- bral nerves, numbered according to the usual notation, viz., 1. Ol- factory nerve. 2. Optic. 3. Motor nerve of eye. 4. Pathetic. 6. Trifacial. 6. Abducent nerve of eye. 7. Auditory, and 7'. FaciaL 8. Glosso-pharyngeal, S'. Vagus, and 8". Spinal accessory nerve. 640 SENSIBILITY. spinal nerves arises from two fasciculi, the one anterior, and the other posterior : these roots are separated from each other by the ligamentum deniiciilare ; but they unite beyond this ligament, and near the inter- vertebral foramen present one of those knots, known under the name of ganglions or ganglia, in the formation of which the posterior root is alone concerned. When the nerves have made their exit from the cranium and spine, they proceed to the organs to which they have to be distributed; ramifying more and more, until they are ultimately lost sight of, even when vision is aided by a powerful microscope. It is not positively decided, whether the nervous fibres have any distinct terminations either in the nervous centres, or in the organs to which they are dis- tributed. In the gray matter of the brain of the vertebrata, they have been considered to form a kind of plexus of loops ; and the ultimate fibres do not seem to anastomose. The following has been described as the mode in which the nervous fibres are generally distributed to the peripheral organs. The trunks subdivide into small fasciculi, each of which consists of from two to six fibres, and these form plex- uses, whose arrangement bears a general resemblance to that of the elements of the tissue in which they are placed. The primitive fibres then separate ; and each, after passing over several elementary parts of the containing tissue, or after forming a single narrow loop, as in the sensory papillie, returns to the same or to an adjoining plexus, and pursues its way to the nervous centre from which it set out. Ac- cording to this view, there is no more a termination of nerves, than there is of bloodvessels. Both form circles. More recent observa- tions seem, however, to have demonstrated, that in different situations the loop-like appearance is fallacious ; and that the ultimate fibres divide into fibrils, the terminations of which are lost in the tissues. It is probable, indeed, that this may be the general mode of termi- nation. Investigations by Henle and Kolliker' show, that some of the peri- pheral nervous fibrils terminate in small bodies, seated especially in the nerves of the fingers and toes, which have been called Pacinian or Vateriari corpuscles ; but of whose uses little can be said. They have not been observed on any motor nerves, so that they would not seem to have anything to do with motion. They exist in many nerves of the sympathetic class, and are not present on many sensitive nerves; so that, it has been properly inferred, they are probably not connected with acuteness of sensation. Another example of the termination of a nerve is in the so-called tactile or touch corpuscles, axile bodies, composed of a horizontally lami- nated mass of areolar tissue, which are found in the papilla? of parts endowed with great tactile sensibility, and into which the nerves of touch enter. ' Uiiber (lie Pacinischen Korperclien an den Nerven des Mensclien und der Sauge- thiere, Ziirifli, 18-t4; reviewed in Brit, and For. Med. Rev., January, 1845, p. 78; Todd and Bowman, Physiological Anat. and Physiology of Man, i. 3y5, London, 1845, or Anier. edit., Pliilad., 1850; and W. Bowman, Cyclopaedia of Anat. and Physiol., by Dr. Todd, })t. xxvii. p. 87t), Lond., Mar., 1840. See, on their discovery by Vater, Strahl, in Miiller's Areliiv. fiir Anatomie, ii. s. w., Berlin, 1848 ; and the Author's Medical Dictionary, art. Corpuscles, Pacinian, 13th edit., Philad., 185(j. NERVES. 641 Fig. 197. Fig. 198. Fig. 199. Pacinian Corpuscles. A. Nerve from the finger, natural size; showing the Pacinian corpuscles. B. Unusual form, from the mesentery of the cat ; showing two included in a common envelope : — a, h are the two nerve-tubes be- longing to them. Tactile Corpuscles from the Skin of the Palmar Sur- face of the Forefinger. A, in the natural state ; b, treated with acetic acid. ^fe% Of the encephalic nerves, the olfactory, auditory, and acoustic — nerves of special sensibility — clearly pass on to their destination, with- out communicating with any other nerve. The spinal nerves, at their exit from the intervertebral foramina, divide into two branches, an anterior and a posterior, one being sent to each aspect of the body. The anterior branches of the four superior cervical pairs form the cer- vical "plexus^ from which all the nerves of the neck arise; the last four cervical pairs and the first dorsal form the hrachial plexus, Fig- 200. whence proceed the nerves of the upper extremities ; whilst the branches of the five lum- bar nerves, and the five sacral form the lumbar and sciatic plexuses; the former of which gives rise to the nerves dis- tributed to the parts within the pelvis; the second to those of the lower limbs. The an- terior branches, moreover, at a little distance from the exit of the nerve from the vertebral canal, communicate with an important and unique portion of the nervous system, the great sympathetic. Each nerve consists of numerous fasciculi surrounded by areolar membrane; and, according to KeiV of an external envelope, called neurilemma, which, in the opinion of most anatomists, is nothing more than a fibro-areolar envelope, similar to that which surrounds the vessels and muscular fibres. A Nerve consisting of many smaller Cords or Funi- culi wrapped up in a common areolar Sheath. A. The nerve, the rest. B. A single funiculus drawn out from VOL. I. — 41 ' De Structura Nervorum, Hal., 1796. 642 SENSIBILITY. Fig. 201. 1. Anterior or motor root of a spinal nerve. 2. Posterior or sensory root. 3. Ganglion connected with the latter. Fig. 202. Until of late years, tlie nerves were universally divided, according to their origin, into encephalic and spinal; but, more recently, anato- mical divisions have been proposed, based upon the uses they appear to fulfil in the economy. For one of the most beautiful of this kind we are mainly in- debted to Sir Charles Bell. It has been already seen, that the encephalic nerves are connected with the encephalon by one root, whilst the spinal nerves arise from two ; the one connected with the anterior tract of the spinal marrow; the other with the posterior. If these dif- ferent roots be experimented on, we meet A portion of the Spinal Marrow, siiow- w^ith rcsults varying Considerably. If ing the Origin of some of the Spinal ^q divide the anterior Toot, the part to which the nerve is distributed is de- prived of motion; if the posterior root be cut, the part is deprived of sensibility. We conclude, therefore, that each of the spinal nerves consists of filaments destined for both motion and sen- sation ; that the encephalic nerves, which have but one root, are des- tined for one of these exclusively, and that they are either nerves of motion, or of sensation, according as their roots arise from the anterior or the posterior tract of the medulla. It has already been remarked, that the medulla oblongata, according to some anatomists, is composed of three fasciculi or columns on each side ; — an anterior, a middle^ and a. posterior; and it has been affirmed by Sir Charles Bell, that whilst the anterior column gives origin to nerves of motion; and the posterior to nerves of sensation ; the middle gives rise to a third order, having the function of presiding over the respiratory move- ments; and which Sir Charles, accord- ingly, calls respiratory nerves. To this third order belong, — the accessory nerve of Willis or superior respiratory; the vagus ; the ghsso-pliaryngeal ; the facial, called by him the respiratory nerve of the face; the phrenic; and another having the same origin — the external respiratory. Sir Charles's views, if admitted, lead, consequently, to the belief, that there are at least three sets of nerves, — one destined for sensation; another for motion ; and a third for a particu- lar kind of motion — the respiratory ; and that every nerve of motion Plans in outline, showing the Front A, and the Side b, of the Spinal Cord, with the Fissures upon it ; also sec- tions of the Gray and White Mat- ter, and the Roots of the Spinal Nerves. a, a. Anterior, p.p. Posterior fissure. h. Posterior, and c. Anterior horn of gray matter, t. Gray commissure, a, e, c. Anterior white column, c, e., h. Lateral columns, a, e, b. Antero-lateral column. b, e, p. Posterior columns, r. Anterior, aud s. Posterior roots of a spinal nerve. SIR CHARLES BELL's DIVISION OF NERVES. 643 communicates to the muscles, to wliich it is distributed, the power of aiding, or taking part in, motions of one kind or another; so that a muscle may be paralyzed, as regards certain movements, by the sec- tion of one nerve, and yet be capable of others of a different kind, by means of the nerves that are uninjured. Yet this division is now by no means generally admitted; and even by some who are of opinion, that the sensory and motor filaments arise from distinct tracts of the spinal cord, it is denied that this is the case with those that originate from the upper part of the cord ; there being in ]the medulla oblongata a blending of the sensory and motor tracts which cannot easily be explained. Pathological cases, too, occa- sionally occur, which throw great difficulty on this matter. Two of the kind have been related by Mr. Stanley and Dr. Budd,' ih which there was disease confined to the posterior column ; yet sensation re- mained unimpaired, whilst the power of motion in the lower extremi- ties was lost. Much evidently remains to be accomplished, before the precise arrangement of the columns of the spinal cord, and of the relations of the nerves connected with them, can be esteemed establislied. Sir Charles Bell,^ indeed, subsequently renounced his first opinion, that the posterior roots of the spinal nerves proceed from the posterior column, and described them as arising from the middle or lateral column; affirming, at the same time, that it is not impossible that the posterior column may be connected with the sensory roots of the spinal nerves, although he has not hitherto succeeded in tracing it. Messrs. Grainger and Swan maintain, that both sets are connected with the lateral columns only; the anterior and posterior lateral fissures defi- nitely limiting the two roots. Perhaps, as has been suggested,^ both these statements may be too exclusive. The anterior roots would seem to have a connexion with both the anterior and lateral columns; and the posterior cannot be said to be restricted to the lateral column, some of their fibres entering the posterior division of the cord. Most physiologists are now of opinion, both from experiment and reflection, that there is no special column destined for respiration, and that there appears to be nothing so peculiar in the action of the respi- ratory muscles, that they should require a distinct set of nerves."* Sir C. Bell proposed a further arrangement of the nerves, more natural and philosophical than the unmeaning numeration according to the system of Willis, and better adapted to facilitate the com- prehension of this intricate portion of anatomy. According to this, all the nerves of the body may be referred to two great classes — the original^ "priraiiive or syrtimelrical^ — and the irregular or superadded. It has been already remarked, that a division of the spinal cord' has been presumed to correspond to the cerebrum; and another to the cere- bellum. Now, every regularnerve has two roots, one from the anterior of these columns, and another from the posterior. Such are the filth pair; the sub-occipital; the seven cervical; the twelve dorsal; the five ' Medico-Cliirurgical Transactions, vol. xxiii., Lond., 1840. * Nervous System, &c., 3d edit., p. 234, London, 1836. ' Carpenter, Principles of Human Physiology, 2d Anier. edit., p. 125, Philad., 1845. ♦ Dr. Reid, op. cit., Jan., 1838, p. 175. 644 SENSIBILITY. lumbar; and the five or six sacral, — that is, thirty-one or thirtj-two per- fect, regular, or double nerves, — including, to state more briefly, all the spinal nerves, and one encephalic — the fifth pair. The fifth pair is found to arise from the encephalon by two roots, and to have a ganglion upon the posterior root. It is, accordingly, classed with the spinal nerves ; and, like them, according to Sir Charles Bell, conveys both motion and sen- sibility to the parts to which it is distributed. These regular nerves are common to all animals, from the zoophyte to man. They run out laterally ; or in a direction perpendicular to the longitudinal division of the body ; and never take a course parallel to it. The other class is called irregular or swperadded. The different nervous cords, proceeding from it, are distinguished by a simple fasciculus or single root. All these are simple in their origins ; irregular in their distribution; and deficient in that symmetry which characterizes those of the first class. They are superadded to the original class ; and correspond to the number and complication of the superadded organs. Of these, there are the ihird^ fourth^ and sixth^ distributed to the eye; the seventh, to the face; the ?m^^A, to the tongue; the glosso-pharyngeal, to the pha- rynx; the vagvs, to the larynx, heart, lungs, and stomach ; the phrenic, to the diaphragm ; the spinal accessory, to the muscles of the shoulders; and the external respiratory, to the Fig. 203, Roots of a Dorsal Spinal Nerve, and its union with the Sympathetic. c, c. Anterior fissure of the spinal cord. a. Ante- rior root. p. Posterior root, with its ganglion, a'. Anterior branch, p'. Posterior branch, s. Sympa- thetic, e. Its double junction with the anterior branch of the spinal nurve by a white and a gray fila- ment. outside of the chest. The reason of the seeming confusion in this latter class is to be looked for in the complication of the superadd- ed apparatus of respiration, and in the variety of offices it has to perform in the higher classes of animals. 4, Great Sympathetic. — This nerve, called also trisplanchnic, splanchnic, ganglionic, great inter- costal, vegetative, and organic is constituted of a series of gan- glions, joined to each other by a nervous trunk, and extending down the side of the spine, from the base of the cranium to the OS coccygis or lowest bone. It communicates with each of the spinal nerves, and with several of the encephalic ; and from the ganglions, formed by such com- munication, sends ofl' nerves, which accompany the arteries, and are distributed particularly to the organs of involuntary functions. At its upper part, it is situate in the carotid canal, where it appears under the form of a ganglionic plexus; two fila- GEEAT SYMPATHETIC. 645 merits of wliicli proceed to join Fig. 204. the sixth pair of encephalic nerves, and another to meet the Vidian twig of the fifth pair. By means of the fifth pair, it communicates also with the oph- thalmic ganglion, which Bichat considered to belong to it. On issuing from the carotid canal, the nerve passes downwards, along the side of the spine, to the sacrum; presenting a series of ganglions; — three in the neck, — the sujperior^ middle^ and in- ferior cervical; twelve in the back, — the thoracic; five in the loins, — the lumbar; and three or four in the sacrum, — the sa- cral. When it reaches the coc- cyx, it terminates by a small ganglion, called coccygeal; or by uniting with the great sympa- thetic of the opposite side. The ganglions are of an irre- gular, but generally roundish, shape. They consist of nervous filaments, surrounded by a red- dish-gray, pulpy, albuminous, or gelatinous substance, which dif- fers from the gray matter of the brain. Sir E. Home' considers their structure to be intermediate between that of brain and nerves ; the brain being composed of small globules suspended in a transparent elastic jelly ; the nerves made up of single rows of globules, and the ganglions con- sisting of a congeries of nervous fibres compacted together.^ Volk- Great Sympathetic Nerve. 1. Plexus on the carotid artery in tlie carotid foramen. 2. Sixth nerve (motor externus). 3. First branch of the fifth, or ophthalmic nerve. 4. A branch on the septum narium going to the inci.sive fora- men. 5. Recurrent branch or Vidian nerve dividing into the carotid and petrosal branches. 6. Poste- rior palatine branches. 7. Lingual nerve joined by the chorda tympani. 8. Portio dura of the seventh pair. 9. Superior cervical ganglion. 10 Middle cervical ganglion. 11. Inferior cervical ganglion. 12. Roots of the great splanchnic nerve arising from the dorsal ganglia. 13. Lesser splanchnic nerve. 14. Renal plexus. 15. Solar plexus. 16. Mesenteric plexus. 17. Lumbar ganglia. 18. Sacral ganglia. 19. Vesical plexus. 20. Rectal plexus. 21. Lumbar plexus (cerebro-spinal). 22. Rectum. 2.3. Bladder. 24. Pubis. 2.5. Crest of the ilium. 26. Kidney. 27. Aorta. 28. Diaphragm. 29. Heart. .30. Larynx. 3l! Submaxillary gland. 32. Incisor teeth. 33. Nasal septum. 34. Globe of the eye. 3o, 36. Cavity of the cranium. ' Lect. on Comp. Anat., v. 194, Lond., 1828. '^ See, on the Histology of the Organic or Sympathetic Nervous Fibres, Mr. Paget, Brit, and For. Med. Rev., July, 1842, p. 279. QiQ SENSIBILITY. man and Bidder, and Reichert/ consider the sympathetic nerve-fibres to be distinct in size and strncture from the cerebro-spinal ; but Valen- tin and others maintain there is no difterence. Authors are by no means agreed with regard to the uses of these ganglions. Willis,^ Haller,^ and others, considered them to be small brains for the secretion of the nervous fluid or animal spirits; an opinion, which was embraced by Richerand,'' and Cuvier;* the latter of whom remarks, that the ganglia are larger and more numerous when the brain is deficient in size. Lancisi,^ and Vicq d'Azyr, re- garded them as a kind of heart for the propulsion of these spirits, or as reservoirs for keeping them in deposit. Scarpa^ treats them as synonymous with plexuses; but plexuses with the filaments in close approximation; and plexuses he regards as ganglions, the filaments of which are more separated. He consequently believes, with many physiologists, that their office is to commingle and unite various nervous filaments with each other. Dr. Wilson Philip* thinks, that they are secondary sources of nervous influence ; that they receive supplies of it from all parts of the brain and spinal marrow, and trans- mit the united influence to the organs to which the nerves are distri- buted; whilst some conceive, that at least one office is to communicate irritability to the tissues.^ Johnstone, '° Reil," Bichat,'^ and others, are of opinion that their use is to render the oi'gans, which derive their nerves from them, independent of the will. These views are sufficiently discordant; and well indicate the intrin- sic obscurity of the subject. That of Dr. Philip is the most probable. Containing the vesicular or gray matter, which seems to be everywhere, perhaps, concerned in the production of nerve-power, the ganglia may be regarded as agents of nervous reinforcement; although we may remain uncertain as to the mode in which their office is executed," It is affirmed by M. Robin, in a communication made by him to the Acadcmie des Sciences, of Paris, in June, 18-i7, that the ganglia of the great sympathetic and of the cerebro-spinal nerves enclose the same ' ISIuUer's Archiv., 1844, cited bvMr. Paf water, as when it is suggested to the patient to drink. The author has been in the habit of offering as an example of the same kind, vomiting induced by the sight of a disgusting object. Here the im- pression is first made upon the brain through an organ of sense, and the reflex motor phenomena concerned in vomiting are instantaneously excited; — facts, which at least prove, that although the gray matter of the spinal marrow may continue to execute its functions, when those of the cerebro-spinal nervous system are suspended, — as during sleep or an attack of epilepsy, — it is capable of being excited to action by impressions made through the latter, in the same manner as by im- pressions made on the afferent spinal nerves themselves. From all that has been said, it will be understood, that each nerve as it issues from the spinal canal must be composed of various fasci- culi : — one, sensory or of sensation, connected with the posterior me- dullary tract, and continuous with the medullary matter of the brain; another, connected with the anterior medullary tract, and conveying the influence of volition from the brain along the spinal cord and nerves to the muscles ; a third, consisting of excitor fibres, terminating ' Human Physiology, 4th Amer. edit., p. 320, Philad., 1850, and new edit., p. 488, Philad., 1855. ^ British and Foreign Medical Review, Jan., 1845, p. 298 ; see also an interesting essay by him on the Functions of the Brain, iu Brit, and For. Med.-Cliir. Rev., July, 1855, p. 155. SPINAL NERVES. 653 Fig. 205. in tlie gray or ganglionic matter of the cord, and conve3n'ng impres- sions to it; and a fourth, consisting of motor fibres, arising from the gray matter of the cord, and conveying the nervous influence reflected to the muscles. It would appear that a part of each root enters the gray matter of the cord; whilst a part is continuous with the white or medul- lary matter; and Dr. Stilling^ affirms — as the result of his researches — that of the fibres of the posterior roots some form loops in the gray matter, and become continuous with those of the anterior roots of the same side; whilst others cross the gray matter, and be- come continuous with those of the anterior roots of the opposite side. It has been Fig. 206. Transverse Section of the Medulla. The transverse gray fibres are the continuation of the roots of the nerves ; the longitudinal white and gray fibres are indi- cated by points. Structure of the Spinal Cord, ac- cording to Stilling. A. Posterior fibres continuous with the anterior of the same side, through the nucleus of the cord. B. Posterior fibres continuous with the anterior of the opposite side. shown, too, by Mr. Newport,^ that there are other fibres, which pass from the posterior into the anterior roots of other nerves, above and below, both on the same and the opposite side. It has been a matter of daily observation, that hemorrhage into one hemisphere of the brain produces loss of sensation in the opposite side of the body ; and the decussation of the sensory fibres has generally, perhaps, been considered to take place in the medulla oblongata ; whilst some physiologists have referred it to the pons varolii, tubercula quad- rigemina, and crura cerebri. Dr. Brown-Sequard,-^ however, found, from experiments on guinea-pigs, dogs, cats, sheep and rabbits, that in the case of a lesion of one side of the spinal cord, a diminution or loss of sensibility is produced on the opposite side of the body, whence he infers, that most of the impressions made on one side of the body are transmitted to the sensorium by the opposite side of the spinal cord. This is the reverse of what occurs in regard to motion ;. for a lesion of the right side of the spinal cord causes a loss or diminution of voluntary movements in the same side of the body; and this is explained by the ' Untersucliungen iiber die Textur des Riickenmarks, von Dr. B. Stilling und Dr. J. Wallach, S. 51, Leipz., 1842. 2 Pliilosopliical Transactions, 1843, and Dr. Carpenter, 2d Amer. edit., p. 125, Philad., 1845. * Medical Examiner, Nov. 1852, p. 708, and his Experimental and Clinical Re- searches on the Physiology and Pathology of the Spinal Cord and some other parts of the nervous centres, Richmond, 1855. 654 SEXSIBILITY. motor fibres decussating in the medulla oblongata only ; whilst the decussation of the sensorj^ occurs in every part of the spinal cord. Much, doubtless, still remains to be accomplished, before we can consider views in regard to the nervous system established. Like many important questions of physiology, they may be regarded as in a tran- sition state; but the zeal and activity of physiological inquirers are dail}^ throwing light upon many points ; and of these there are none sur- rounded with more obscurity than those that appertain to this subject. All the parts described as constituting the nervous system — brain, cerebellum, medulla spinalis, and nerves — are formed of the primary nervous fibre, the nature of which has been already described. The neurine or substance of which they are constituted is soft and pulpy; but the consistence varies in different portions, and, in the whole, at different ages. In the foetus it is almost fluid ; in youth of greater firmness; and in the adult still more so. This softness of structure in the encephalon of the foetus is by no means inutile. It admits of the pressure, which takes place, to a greater or less extent in all cases of parturition, whilst the head is passing through the pelvis, without the child sustaining any injury. On examining, however, the consistence of different brains, it is necessary to inquire into the period that has elapsed since the death of the individual, as the brain loses its firm- ness by being kept; and ultimately becomes semi-fluid. It is likewise rendered fluid by disease, constituting ramollissement du cerveau or moUescence of the brain, to which the attention of pathologists has been directed of comparatively late years, but without much important advantage to science. When the encephalon is fresh, it has a faint, spermatic, and some- what tenacious smell. This, according to M. Chaussier, has persisted for years in brains that have been dried. Neurine has been subjected to analysis by M. Yauquelin,' and found to contain, water, 80'00 ; white fatty matter, 4*58 ; red fatty matter, called cerebrin, O'TO ; osmazome, 1"12 ; albumen, 7*00 ; phosphorus, 1*50 ; sulphur, and acid phosphates of potassa, lime, and magnesia, 5"15. M. Couerbe's analysis of that of the brain^ gives, 1. A pulverulent yellow fat, stearconote ; 2. An elastic yellow fat, cerancephahte ; 3. A reddish -yellow oil, eleancephol ; 4. A white fatty matter, cerebrate, the white fatty Tyiatter of Vauquelin, the wyelocone of Klihn ; 5. Cerebral cholesterin — cholesterote; and the salts found b}'- Vauquelin, — lactic acid, sulphur, and phosphorus, which form a part of the fats above mentioned.^ In the spinal cord, there is more fatty matter, and less osmazome, albumen, and water. In the nerves, albumen predominates, and fatty matters are less in quantity. Eesearches by M. Lassaigne show, that water constitutes ^Qths of the nerves ; and -^^t\\& of the brain ; whilst the proportion of albumen in the former is ,^0^0^^^ ! i^ the latter, y^^ths. He found the neurine of different parts of the brain to be compcjsed as follows: ' Annales de Cliim., Ixxxi. 37 ; and Annals of Philosophy, i. 332. * Annales de Chimie et de Physique, Ivi. 160. ' For John's Analysis of the white and gray cerebral matter, see Journal de Chimie Medicale, Aout, 1835. See, also, Simon's Medical Chemistry, p. 81, Lond., Is45 ; or Amer. edit., Philad., 1846. NERVOUS TISSUE • 65 The whole B rain. White portion. Gray portion. Water, 77-0 73-0 '85-0 Albumen, 9-6 9-9 7-5 White fatty matter, 7-2 13-9 1-0 Red fatty matter, 3-1 0-9 3-7 Osmazome, lactic acid, and salts, 2*0 1-0 1-4 Earthy phosphate, 1-1 1-3 1-2 100-0 100-0 100-0' M. EaspaiP has pointed out two other differences. First^ when a nerve is left upon a plate of glass in dry air, it becomes dry, without putrefying, whilst cerebral neurine putrefies in twenty-four hours; and secondly^ the dried nerve has all the physical characters of the corneous substances, — nails, hair, and other analogous bodies ; and in their chemical relations, these bodies do not differ sufficiently to repel the analogy. Neither the chemical analysis of neurine, nor inquiry into its minute structure by the aid of the microscope, has, however, thrown light upon the wonderful functions executed by this elevated part of the organism. It would seem, that neurine is, in composition, intermediate between fat and the compounds of protein ; it contains nitrogen, which is not present in fats, but in smaller proportion than in protein ; and, on the other hand, it is much richer in carbon than protein or its compounds. Phosphorus, too, is an essential ingredient. According to researches by M. Fremy, there is in cerebral neurine a peculiar acid, analogous to the fatty acids, which he calls cerehric acid, and which contains nitro- gen and phosphorus ; this is mixed with an albuminous substance; with an oily acid — oleo-phosphoric ; with cholesterin ; and with small quantities of olein and margarin, and oleic and margaric acids.^ As Lehmann,'' however, has remarked, the analysis of the nervous tissue is still very imperfect.* To the naked eye, neurine appears under two forms; — the one gray and of a softer consistence; the other white, and more compact. The former is called the vesicular, gray, cortical, cirieritious, or puljyy sub- stance; the latter, the tubnlar, white, Tnedullary, or fibrous, called "tubular" in consequence of its consisting of tubes of great minute- ness, which are filled with a kind of granular albuminous pith that can be squeezed from them, — a view adopted by most histologists. Dr. James Stark has,^ however, affirmed, as the result of his examination, — and Mulder and Bonders accord with him — that the matter which fills the tubes is of an oily nature, differing, in no essential respect, from butter or soft fat, and remaining of a fluid consistence during the ' Journal de Chim. Medic. ; and Pharmaceutisches Central Blatt, Nov. 19, 1836, S. 765. ^ Cliiraie Organique, p. 217, Paris, 1833. ' Journ. des Coiniais. Med.-Chir., Jan., 1841; also Turuer and Liebig's Chemistry, 7th edit., p. 1195, Lend., 1842. '' Lehrbuch der Physiologischen Chemie, iii. 123, Leipzig, 1851 ; and Amer. edit, of Dr. Day's translation, by Dr. Robert E. Rogers, ii. 266, Pliilad., 1855. ^ For the recent analyses of the neurine of man and the mammalia, by Von Bibra, Schlossberger, and others, see an excellent resume by Dr. Dav, in Brit, and For. Med.- Chir. Rev., July, 1855, p. 223. ^ Proceedings of the Royal Society, No. 56, Lond., 1843. 656 SENSIBILITY. life of the animal, or whilst it retains its natural temperature ; but be- coming granular or solid when the animal dies. Lehmann' is of opinion, that although it is difficult to obtain direct proof from microscopical observations, or rather to form a judgment from them, the descriptions of the alterations experienced by the me- dulla or nerve-pulp on the addition of different reagents — in becoming coarsely or finely granular or crystalline — seem to indicate, that the nerve-pulp contains a soluble protein substance, in the closest admix- ture' with a fat dissolved by easily decomposable soaps, and that the visibility of the pulp is owing less to the coagulation of this albuminous body than to the separation of the fat from the decomposing soaps and the albuminous substance. The pitli that fills the tubes or the axis cylinder he regards as a protein substance presenting many resem- blances to the sub- Fig. 207. stance of the muscu- lar fibrils — syntonin ; and he dissents, there- fore, from the view of those — as Mulder and Bonders — who regard it to be composed of fat, or at all events of a very fatty substance. The tubular nervous matter, wherever it is found, seems to consist of fibres, which have a definite arrangement. Two kinds of primi- tive fibre, according to the researches of Messrs. Todd and Bowman,^ are present in the nervous sys- tem, which they dis- tinguish as the tubular A. Tubular nerve-fibres, showing the sinuous outline and double Jlbre OT lierve tubc, and contours. B. Diagram to show the parts of a tubular fibre, viz. : 1, 1. Mem- branous ttiAe. 2,2. White sitbstance or medullary sheath. Z. Axis ox primitive band. c. Figure (imaginary) intended to represent the appearances occa- sionally seen in the tubular fibres. 1, 1. Membrane of the tube seen at parts where the wliite substance has separated from it. 2. A part where the white substance is interrupted. 3. Axis projecting beyond r»Viipfl\;- in tliA Qirmnri the broken end of the tube. i. Part of the contents of the tube es- '-'"i^^J ^" ''^« by mpd- caped. thetic system. The tubular fibres vary in diameter from i-s'stj^^ even to toooo^^i of an inch; but their average width is from ao'ootl^ to 4o'o?)th of an inch. The gelatinous fibre is devoid of the whiteness that characterizes the tubular fibre; and the gray colour of certain nerves, it has been thought, is dependent chiefly ' Op. cit. * Dr. Todd, Art. Nervous Centres, in Cyclop, of Anat. and Pliys., Pt. xxvi., p. 707 ; and The Physiological Anatomy and Physiology of Man, p. 208, Loudon, 1845. Tubular Nerve-fibres. the gelatinous fibre, — the former infinitely the more numerous, and the latter found CIRCULATIOISr IN THE ENCEPHALON. 657 Gelatinous Nerve-fibres. a and ftmagnifiod 340 diameters, after Han- nover : c and d after Kemak. upon the presence of a large proportion of gelatinous fibres. Hence they have been sometimes termed gray fibres. These are in general smaller than the tubular fibres, — their average diameter ranging between the gjj'ofjth and the 4o'oo^^^ of an inch.^ The central portion of each nerve- fibre dii^ers from the peripheral : the former has been termed by Rosenthal and Purkinje the axis-cylinder; the latter is the medullary or loliite sub- stance of Schwann, and to it the white colour of the cerebro-spinal nerves is chiefly due. The researches of histologists have shown that vesicles or cells containing nuclei and nucleoli, and called also 7ierve corpuscles and globules and gnn- glion corpuscles and globules, are the es- sential elements of gray or vesicular matter. These are found in the nervous centres, mingled with nerve-fibres, and imbedded in a dimly shaded or granular substance. They give to the ganglia and to certain parts of the brain and spinal cord the peculiar urayish or reddish-gray appearance by which they are characterized. They are large nucleated cells, filled with a finely granular material; some of which is often dark, like pigment; — the nucleus, which is vesicular, contain- ing a nucleolus. The marginal figure (Fig. 209) represents some that have a regular outline. Others, as in Fig, 210, are caudate or stellate, and have tubular processes issu- ing from them, filled with the same kind of granular matter as is contained in the corpuscle. The gray substance is not always at the exterior, nor the medullary in the interior. Ill the medulla spinalis, their situation is the reverse of what it is in the brain. In the invertebrata, the gray matter forms the nuclei of the ganglia, which are the centres of the nervous system ; and the true spinal system, which occupies the interior of the spinal cord, has been regarded as a chain of similar ganglia. It is the organ, as already shown, of the spinal excito-motory nervous function. Ruyscjh considered, that the gray portion owes its colour to the bloodvessels that enter it;^ and, in this opinion, Haller, Adelon,^ and others," concur ; but this is not pro- bable, and it has not been by any means demonstrated, nor has the ' See on the disputes in regard to the two sets of nerve fibres, and especially on the so called fibres of Remak or gelatinous fibres, Dr. J. Drummond, Art. Sympathetic Nerve, in Cyclop, of Anat, and Physiol,, Ft. xlvii. p. 433, London, August, 1855. ^ bper., Amstel., 1727. 3 Physiologie de I'llomme, 2de edit., i. 208, Paris, 1829. * Carpenter, Human Physiology, p. 81, Lond,, 1842. VOL. I. — 42 Ganglion Corpuscles. In one a second nucleus is visible. The nucleus of several contains one or two nucleoli. 658 SENSIBILITY. 210. nature of the pigmental matter been detected.^ The medullary portion has the appearance of being fibrous ; and it has been so regarded by Leeuenhoek,^ Yieussens, Steno, and Gall and Spurzheim.^ Mal- pighi'' believed the gray cortical substance to be an assemblage of small follicles, intended to secrete the nervous fluid; and the white medullary sub- stance to be composed of the excretory vessels of these follicles ; and an analogous view is entertained by many physiologists of the present day, — the gray matter at least being regarded as the generator of the nervous in- fluence; the white matter as chiefly concerned in its con- duction. Gall and Spurz- heim conjecture, that the use of the gray matter is to be the source or nourisher of the white fibres. The facts, on which they support their view, are, that the nerves appear to be enlarged when they pass through a mass of gray matter, and that masses of this substance are dej^osit- ed in all parts of the spinal cord where it sends out nerves; but Tiedemann* has remarked, that in the foetus the medullary is developed before the cortical portion, and he conceives the use of the latter to be — to convey arterial blood, which may be needed by the medullary portion for the due execution of its functions. After all, however, it must be admitted with Dr. Allen Thomson,^ that the general conclusion deducible from all the facts would seem to be, that whilst the gray fibres predominate in the organic or sympathetic nerves, and the tubu- lar fibres in the cerebro-spiual nerves, these two elements are mixed, in various proportions, in the great divisions of the nervous system; and that, therefore, these divisions, although, in a great measure, struc- turally different, are not altogether distinct from, or independent of, each other. "But" — he properly adds — "in regard to the whole sub- ject of the structures and nature of the different varieties of the nerv- Stellate or Caudate Xerve Corpuscles. a, a. From the deeper part of the gray matter of the con- volutions of the cerebellum. The larger processes are di- rected towards the surface of the organ. 6. Another from the cerebellum, c, d. Others from the post-horn of gray matter of the dorsal region of the cord. These contain pig- ment, which surrounds the nucleus in c. In all the speci- mens the processes are more or less broken. Magnified 200 diameters. ' Todd, Cvclop. of Anat. and Thysiol., Pt. xxv. p. 647, Lond., 1844. 2 Philo.-?. Transact., 1677, p. 899. ^ Recherches sur le Systeme Nerveux en general, et sur celui du Cerveau en parti- culier, avec figures, Paris, 1809. * Oper. Malpighii, and Mangeti Bibl. Anat., i. 321. * Anatomie und Bildungsgeschichte des Gehirns, mit Tafeln, Niimberg, 1816. 6 Outlines of Physiology, Pt. i. p. 155, Edinb., 1848. CIRCULATION IN THE ENCEPHALON. 659 ous texture, it is unquestionable that mucli still remains to be ascer- tained by laborious investigation." Of the mode in which the tubular neurine communicates with the Fig. 211. Fig. 212. Microscopic Ganglion from Heart of Frog. Bipolar Ganglionic Cells and Nerve-fibres from Unipolar Ganglionic Cell. ganglion of 5th Pair in Lamprey. vesicular we know nothing, as yet, that is very definite; that a direct communication must exist appears to be evident. Histologists have Fig. 213. Connection between nerve-fibres and nerve corpuscles ; from the roots of a spinal nerve of the ray. A. A nerve-corpuscle, escaped by pressure from the capsule formed around it by the dilated slieath of the nerve-tubule; it shows also the gradual disappearance of the outer portion of the substance of the nerve as it comes into relation with tJie corpuscles, b. A nerve-corpuscle inclosed within a dilated por- tion of the sheath of a nerve: part of the granular material of the corpuscle is continuous with the cen- tral substance of the nerve in the course of which it is inserted. detected it, and it has been noticed, that a vesicle or cell gives off at times, a single prolongation, in which case the ganglionic cell is termed — unipolar ; whilst at others, a ganglion cell seems to be con- tained in a nerve-tube, having each of its extremities prolonged into a fibre or tubule, when the cell is termed — bipolar. The former is said to be more common in man and the higher vertebrata, — the latter in fishes. In certain parts of the nervous centres of man, stellate gan- glionic cells send out radiating prolongations, some of which luive been observed communicating with the axis cylinder of nerve tubes.' Bidder noticed the transition of primitive fibre cells of the roots of the spinal nerves, as well as the longitudinal fibres of the white substance ' Ecker, in Carpenter's Principles of Human Physiology, Amer. edit., p. 431, Philad. 1855. 660 SENSIBILITY. into cells of the gray, in great abundance.' Vesicles or corpuscles are seen, however, that do not seem to be immediately connected with nerves.^ Sir Charles BelP affirms, that he has found, at different times, all the internal parts of the brain Fig- 214. diseased, without loss of sense; but he has never seen disease general on the surface of the hemispheres without derange- ment or oppression of mind during the patient's life ; and hence he concludes, that the vesicular matter of the brain is the seat of the intellect, and the tubular of the subservient parts.^ A similar use has been ascribed to the vesicular por- tion, from pathological ob- servations, by MM. Foville and Pinel Grandchamp.* This view would afford consider- able support to the opinions of Gall, Spurzheim, and others, who consider the organs of the cerebral faculties to be con- stituted of expansions of the columns of the spinal marrow and medulla oblongata, and to Circle of Willis. terminate by radiating fibres 1. Vertebral arteries. 2. Two anterior spinal branches qjj t,he periphery of the brain ; uniting to form a single vessel. 3. One of the posterior r / -i "^ n ->•- -r>. spinal arteries. 4. Posterior meningeal. 5. Interior cere- aS Weli aS tO tllOSC Ol iVl. JJCo- bellar. 6. Basilar arterygiving off its transverse branches ^ _,,! • q <> nnrl nthpTS who TH- to either .side. 7. Superior cerebellar artery. 8. Posterior mOUlins, aUQ OlUClhWIlO i O- cerebral. 9. Po.sterior communicating branch of the in- g-ard thc COUVOlutioUS aS the ternal carotid. 10. Internal carotid, showing the curva- S"^^ „ ■, . i ttt i tures it makes within the skull. 11. Ophthalmic artery gg^t of the UllUd. We haVC, divided across. 12. Middle cerebral artery. 13. Anterior J 4.1 4. cerebral arteries connected by, l-l. Anterior communicat- nOWCVCr, CaSCS OU TeCOrQ, lUat ^"s '^''•''■y- signally conflict with this view of the subject; in which the cortical substance has been destroyed, and yet the moral and intellectual manifestations have been little, if at all, injured. Many years ago, the author dissected the brain of an indi- vidual of rank in the British army of India, in the anterior lobes of which neither medullary nor cortical portion could be distinguished, — both one and the other appearing to be broken down into a semi-puru- ' Dr. J. W. Ogle, Report of Micrology, in Brit, and For. Med.-Chir. Rev., Oct., 1855, T) 525. "* See, on all this subject, KoUiker, Mikroskopische Anatomie, ii. 508, Leipzic, 1850, or Amer. edit, of Sydenham Society's edition of his Manual of Histology, p. 35ti, Phila- delphia, 1854; and" Drumniond, Cyclop, of Anat. and riiysiol., loc. cit. 3 Anatomy and Physiology, 5th Amer. edit., by J. D. (Jodman, p. 29, New York, 1827 < See two interesting pathological cases, confirming this view of the function of the gray matter, by Dr. Cowan, in Provincial Medical and Surgical Journal, April 16, 1845. * Sur le Systeme Nerveux, Paris, 1820. _ 6 Anatomie des Systemes Nerveux des Animaux a Vertebres, p. 599, Pans, 1825. CIRCULATION IN THE BRAIN. 661 lent, amorphous substance ; yet tlie intellectual faculties had been nearly unimpaired, although the morbid process must have been of some duration. The encephalon affords many striking instances of the different effects produced by sudden, and by gradual interference with its func- tions. Whilst a depressed portion of bone or an extravasation of blood may suddenly give rise to the abolition of the intellectual and moral faculties, gradual compression by a tumour may scarcely interfere with any of its manifestations. The circulation of blood in the encephalon requires i|otice. The arteries are four in number, — two i7iternal carotids, and two vertehrals : to these may be added the spinal or middle artery of the dura water, — arteria meningcea media. The carotid arteries enter the head through the carotid canals, which open on each side of the sella turcica, or of the chiasma of the optic nerves. The vertebral arteries enter the head through the foramen magnum of the occipital bone ; unite on the medulla oblongata to form the basilary artery, which passes forward along the middle of the pons Varolii ; and, at the anterior part of the pons, gives off lateral branches, which inosculate with corresponding branches of the carotids, and form a kind of circle at the base of the brain, which has been called circulus arteriosus of Willis. The passage of the bloodvessels is extremely tortuous, so that the blood does not enter the brain with great impetus; and they become capillary before they penetrate the organ, — an arrangement of importance, when we regard the large amount of blood sent to it. This has been estimated as high as one-eighth of the whole fluid transmitted from the heart. The amount does not admit of accurate appreciation, but it is consider- able. It of course varies according to circumstances. In hypertro- phy of the heart, the quantity is sometimes increased; as well as in ordinary cases of what are called determinations of blood to the head. Here, too large an amount is sent by the arterial vessels; but an equal accumulation may occur, if the return of the blood from the head by the veins be in any manner impeded, — as when we stoop, or compress the veins of the neck, by a tight cravat, or by keeping the head turned for a length of time. Congestion or accumulation of blood may there- fore arise from very different causes. Sir Astley Cooper' found by experiment, that the vertebral arteries are more important vessels as regards the encephalon and its functions in certain animals, as the rabbit, than the carotids. The nervous power is lessened by tying them ; and, in his experiments, the animals did not, in any case, survive the operation more than a fortnight. In the dog, he tied the carotids with little effect, but the ligature of the verte- hrals had a great influence. The effect of the operation was to render the breathing immediately difficult and laborious ; owing, in Sir Astley's opinion, to the supply of blood to the phrenic nerves, and the whole tradus respiratorius of Sir Charles Bell, being cut off". The animal became dull, and indisposed to make use of exertion ; or to take food. Compression of the carotids and the vertebrals at the same moment, in the rabbit, destroyed the nervous functions immediately. This was effected by the application of the thumbs to both sides of the neck, the ' Guy's Hospital Reports, i. 472, London, 1836. 662 SENSIBILITY. Fig. 215. trachea remaining free from pressure. Eespiration ceased entirely, witli the exception of a few convulsive gasps. The same fact was evinced in a clearer and more satisfactory manner by the application of ligatures to the four vessels, all of which were tightened at the same instant. Stoppage of respiration and death immediately ensued. The cerebral, like other arteries, are accompanied by branches of the great sympathetic. The researches of of Purkinje,^ Volkmann,^ and Kainey,^ have shown the existence of a large num- ber of nerves in connection with the en- cephalic and spinal arachnoid. They do not seem to communicate with the roots of the spinal nerves, but belong exclusively to the sympathetic* The encephalic veins are disposed as already described, termi- nating in sinuses formed by the dura mater, and conveying their blood to the heart by means of the lateral sinuses and internal jugulars; but of the peculiarities of the circulation in the encephalon, mention will be made in the appropriate place. No lymphatic vessels have been detected in the encephalon ; yet, that absorbents exist there is proved by the dissection of apo- plectic and paralytic individuals. In these cases, when blood has been effused, the red particles are gradually taken up, with a portion of the fibrinous part of the blood, leaving a cavity called an apoplectic cell, which is at the same time the evidence of previous extravasation and subsequent absorption. The whole of the nervous system is well supplied with bloodvessels. In the vesi- cular neuriue of the nervous centres, the capillaries surround the ganglion cells or bules; and in the tubular they pass een the nerve-tubes, being connected ntervals by transverse branches, hen the skull of the new-born infant, hich, at the fontanelles, consists of mern- e only — or the head of any one who has received an injury, that exposes the brain — is examined, two distinct move- ments are perceptible. One, which is generally obscure, is synchronous with the pulsation of the heart and Sinuses of the Base of the Skull. 1. Ophthalmic veins. 2. Cavernous sinus of one side. .3. Circular sinus : the figure occupies the position of the pituitary gland in the sella turcica. 4. Inferior petrosal sinus. 5. Transverse or anterior occipital sinus. 6. Superior petrosal sinus. 7. Internal jugular vein. 8. Foramen magnum. 9. Occipital si- nuses. 10. Torcular Herophili. 11, 11. Lateral sinuses. Fiff. 216. Capillary Network of Xervoas Centres. ' Miiller's Arcliiv. fiir Anatomie, p. 281, Berlin, 1845. 2 Art. Nerveuphysiologie, Wagner's Hand\r6rterbnch der Physiologie, lOte Lieferung, S. 494, Braunschweig, 1845. ^ Meiiico-Chirurgical Transactions for the ye^r 1845. •• Brinton, Art. Serous and Synovial Meiubraues, in Cyclop, of Anat. and Physiol., Pt. xxxiv. p. 525, Loud., Jan., 1849. CEPHALO-SPINAL FLUID. 663 arteries; the otlier, much more apparent, is connected with respiration, the organ seeming to sink at the time of inspiration, and to rise during expiration. This phenomenon is not confined to the cerebrum, but exists likewise in the cerebellum and spinal marrow. The motion of the encephalon, synchronous with that of the heart, admits of easy explanation. It is owing to the pulsation of the circle of arteries at the base of the brain elevating the organ at each sj^stoie of the heart. The other movement is not so readily intelligible. It has been attri- buted to the resistance, experienced by the blood in its passage through the lungs during expiration, owing to which an accumulation of blood takes place in the right side of the heart ; this extends to the veins and to the cerebral sinuses, and an augmentation of bulk is thus occasioned. It has been elsewhere remarked, that one of the forces conceived to pro- pel the blood along the vessels is atmospheric pressure. According to that view, the sinking down of the brain during inspiration is expli- cable ; the blood is rapidly drawn to the heart ; the quantity in the veins is consequently diminished ; and sinking of the brain succeeds. On dissection, we find that the encephalon fills the cavity of the cra- nium; during life, therefore, it must be pressed upon, more or less, by the blood in the vessels, and by the serous fluid exhaled by the pia mater into the subarachnoid tissue. Thence it penetrates into the ventricles, — according to M. Magendie, at the lower end of the fourth ventricle, at the calamus scriptorius. The quantity varies according to the age and size of the patient, and usually bears an inverse propor- tion to the size of the encephalon. It is seldom, however, less than two ounces, and often amounts to five. M. Magendie is of opinion, that the fluid is secreted by the pia mater, and states, that it may be seen transuding from it in the living animal. The results of chemical analysis appear to show, that it differs from mere serum. It is ob- viously, however, almost impracticable — if not wholly so — to separate the consideration of this fluid from that met with in the cavity of the arachnoid. The spinal marrow does not, as we have seen, fill the vertebral canal; the cephalo-spinal fluid exerts upon it the necessary pressure; added to which, the pia mater seems to press more upon this organ than upon the rest of the cerebro-spinal system. A certain degree of pressure appears, indeed, necessary for the due performance of its functions ; and if this be either suddenly and considerably augmented, or diminished, derangement of function is the result. M. Magendie,^ however, asserts, that he has known animals, from which the fluid had been removed, survive without any sensible derangement of the nervous functions. It is this fluid, which is drawn ofl" by the surgeon when he punctures in a case of spina bifida. When the brain is examined in the living body, it exhibits proper- ties, which, some years ago, it would have been esteemed the height of hardihood and ignorance to ascribe to it. The opinion has universally prevailed, that all nerves are exquisitely sensible. Many opportuni- ' Precis El mentaire, secoiide i^dit., i. 192; and Rocherclies Physiologiques et Cliiiiques sur le Liquide Cei>lialo-racliidieii ou Cerebro spinal, Paris, 1842. Dr. Todd, Cyclopajdia of AnatouiV and Physiology, Pt. xxv. p. (531), London, 1844 ; and Foltz, Schmidt's Jahrb, xxxvi. 292, and Brit, and For. Med.-Chir. Rev., Jan., 1850, p. 234. 664 SENSIBILITY. ties will occur for showing, that this sentiment is not founded on fact; even the encephalon itself, — the organ in which perception takes place, — is insensible, in the common acceptation of the term; that is, we may prick, lacerate, cut, and even cauterize it, yet no painful im- pression will be produced. Experiment leaves no doubt regarding the truth of this, and we find the fact frequently confirmed by patho- logical cases. Portions of brain may be discharged from a wound in the skull, and yet no pain be evinced. In his " Anatomy and Phy- siology," Sir C. BelP remarks, that he cannot resist stating, that on the morning on which he was writing, he had had his finger deep in the anterior lobes of the brain; when the patient, being at the time acutely sensible, and capable of expressing himself, complained only of the integument. A pistol-ball had passed through the head, and Sir Charles, having ascertained, that it had penetrated the dura mater by forcing his finger into the wound, trephined on the opposite side of the head, and extracted it. By the experiments, instituted by M^f. Magendie,' Flourens and others, it has been shown, that an animal may live days, and even weeks, after the hemispheres have been removed; nay, that in certain animals, as reptiles, no change is produced in their habitudes by such abstraction. They move about as if unhurt. Injuries of the surfiice of the cerebellum exhibit, that it also is not sensible; but deeper wounds, and especially such as interest the peduncles, have singular results, — to be mentioned hereafter. The spinal cord is not exactly circumstanced in this manner. Its sensibility is exquisite on the pos- terior surface; much less on the anterior, and almost null at the centre. Considerable sensibility is also found within, and at the sides of, the fourth ventricle; but this diminishes as we proceed towards the ante- rior part of the medulla oblongata, and is very feeble in the tabercula quadrigemina of the mammalia. It has been shown, that the spinal nerves, by means of their poste- rior roots, convey general sensibility to the parts to which they are distributed. But there are other nerves, which, like the brain, are themselves entirely devoid of general sensibility. This has given occasion to a distinction of nerves into those of general and of specinl sensibility. Of nerves, which must be considered insensible or devoid of general sensibility, we may instance the optic, olfactory, and audi- tory. Each of these has, however, a special seiisihility; and although it may exhibit no pain when irritated, it is capable of being impressed by appropriate stimuli — by light, in the case of the optic nerve; by odours, in that of the olfactory ; and by sound, in that of the auditory. Yet we shall find, that most of the nerves of special sensibility seem to require the influence of a nerve of general sensibility, — the fifth pair. Many nerves appear devoid of sensibility, as the third, fourth, and sixth pairs; the portio dura of the seventh ; the ninth pair of encephalic nerves; and, as has been shown, all the anterior roots of the spinal nerves. The parts of the encephalon, concerned in muscular motion, will fall under consideration hereafter. ' Fifth Anier. edit, by J. D. Godman, ii. 6, New York, 1827. * Precis Elementaire, i. 325. SENSATIONS. 665 2. PHYSIOLOGY OF SENSIBILITY. Animal sensibility we have defined to be — the function by which we experience feeling, or have the perception of an impression. It in- cludes two oTeat sets of phenomena; the sensations^ properly so called, and the intelkctunl and moral manifestations. These we shall investi- gate in succession. a. Sensations. A sensation is the perception of an impression made on a living tissue; — or, in the language of Gall, it is the perception of an irrita- tion. By the sensations we receive a knowledge of what is passing within or without the body; and, in this way, our notions or ideas of them are obtained. When these ideas are reflected upon, and com- pared with each other, we exert thouglit and judgment; and they can be recalled with more or less vividness and accuracy by the exercise of mem.ory. The sensations are numerous, but they may all be comprised in two divisions, — the external and the internal. Vision and audition afford us examples of the former, in which the impression made upon the organ is external to the part impressed. Hunger and thirst are instances of the latter, the cause being internal, necessary, and depending upon influences seated in the economy itself. Let us endeavour to discover in what they resemble each other. In the first place, every sensation, whatever may be its nature, — ex- ternal, or internal, — requires the intervention of the encephalon. The distant organ — as the eye or ear — may receive the impression, but it is not until this irnpression has been communicated to the encephalon, that sensation is effected. The proofs of this are easy and satisfactory. If we cut the nerve proceeding to any sensible part, put a ligature around it, or compress it in any manner, — it matters not that the object, which ordinarily excites a sensible impression, is applied to the part, — no sensation is experienced. Again, if the brain, the organ of percep- tion, be prevented in any way from acting, it matters not that the part impressed, and the nerve communicating with it, are in a condition necessary for the due performance of the function, sensation is not effected. We see this in numerous instances. In pressure on the brain, occasioned by fracture of the skull; or in apoplexy, a disease generally dependent upon pressure, we find all sensation, all mental manifestation, lost; and they are not regained until the compressing cause has been removed. The same thing occurs if the brain be stupefied by opium; and, to a less degree, in sleep, or when the brain is engaged in intel- lectual meditations. Who has not found, that in a state of reverie or brown study, he has succeeded in threading his way through a crowded street, carefully avoiding every obstacle, yet so little impressed by the objects around as not to retain the slightest recollection of them! On the other hand, how vivid are the sensations when attention is directed to them! Again, we have numerous cases in which the brain itself engenders the sensation, as in dreams, and in insanity. In the former, we see, hear, speak, use every one of our senses apparently; yet there has been no impression from without. Although we may behold in 666 SENSIBILITY. our dreams the figure of a friend long since dead, tliere can obviously be no impression made on the retina from without.^ Such are called subjective sensations, to distinguish them from those caused by impres- sions made by objects on the peripheral extremities of the nerves of sense, and hence termed objective sensations. The whole history of spectral illusions, morbid hallucinations, and maniacal phantasies, is to be accounted for in this manner. Whether, in such cases, the brain reacts upon the nerves of sense, and produces an impression upon them from within, similar to what they experience from without during the production of a sensation, will form a subject for future inquiry. Pathology also affords several instances where the brain engenders the sensation, most of which are precursory signs of cerebral derangement. The appearance of spots flying before the eyes, of spangles, depravations of vision, hearing, &c., and a sense of numb- ness in the extremities, are referable to this cause; as well as the singu- lar fact well known to the operative surgeon, that pain is often felt in the stump of a limb, months after it has been removed from the body. These facts prove, that every sensation, although referred to some organ, must be perfected in the brain. The impression is made upon the nerve of the part, but the appreciation takes place in the common sensorium. There are few organs which could be regarded insensible, were we aware of the precise circumstances under which their sensibility is elicited. The old doctrine — as old indeed as Hippocrates^ — was, that the tendons and other membranous parts are among the most sensible of the body. This opinion was implicitly credited by Boerhaave, and his follower Van Swieten;^ and in many cases had a decided influence on surgical practice more especially. As the bladder consists princi- pally of membrane, it was agreed for ages by lithotomists, that it would be improper to cut or divide it; and, therefore, to extract the stone di- lating instruments were used, which caused the most painful lacerations of the parts. Haller"* considered tendons, ligaments, periosteum, bones, meninges of the brain, different serous membranes, arteries and veins, entirely insensible; yet we know, that they are exquisitely sensible when attacked with inflammation. One of the most painful affections to which man is liable is the variety of whitlow that implicates the periosteum; and in all affections of the bone which inflame or press forcibly upon that membrane, there is excessive sensibility. It would appear, that the possession of vessels or vascularity is a necessary con- dition of the sensibility of any tissue. Many parts, too, are affected by special irritants; and, after they have appeared insensible to a multitude of agents, show great sensibility when a particular irritant is applied. Bichat endeavoured to elicit the sensibility of ligaments in a thousand ways, without succes-;; but when he subjected them to distension or twisting, they immediately gave evidence of it. It is obvious, that before we determine that a part is insensible, it must have been submitted to every kind of irritation. ' Adelon, .art. Encepliale (Physiolostie), in Diet, de Med., vii. 514, Paris, 1823 ; and Physiol, de rHomme, torn. 1. p. 239, 2de edit., Paris, 1829. ^ Foesii fficonom. Ilippocr. "NsLpsv." ^ Aphorism. 1(34 and 1G5, and Comment. ' * Oper. Minor., torn. i. SENSATIONS ACCOMPLISHED IN THE ENCEPHALON. 667 M. Adelon affirms, that there is no part but what may become painful by disease. From this assertion the cuticle might be excepted. If we are right, indeed, in our view of its origin and uses, as described here- after, sensibility would be of no advantage to it; but the contrary. In the present state, then, of our knowledge, we are justified in asserting, that bones, cartilages, and membranes are not sensible to ordinary ex- ternal irritants, when in a state of health, — or in other words, that we are not aware of the irritants, which are adapted to elicit their sensibility. That sensibility is due to the nerves distributed to a part is so gene- rally admitted as not to require comment. Dr. Todd' has affirmed, that the anatomical condition necessary for the developement of the greater or less sensibility of an organ or tissue is the distribution in it of a greater or less number of sensitive nerves; and that the anatomist can determine the degree to which this property is enjoyed by any tissue or organ by the amount of nervous supply, which his research discloses. It may well be doubted, however, whether sach sensibility be by any means in proportion to the number of nerves received by a part. Nay, some parts are acutely sensible in disease into which nerves cannot be traced. To explain these cases, Reil'^ supposed that each nerve is sur- rounded at its termination by a nervous atmosphere, by which its action is extended beyond the part in which it is seated. This opinion is a mere creation of the imagination. We have no evidence of any such atmosphere; and it is more philosophical to presume, that the reason we do not discover nerves may be owing to the imperfection of our vision. We may conclude, that the action of impression occurs in the nerves of the part to which the sensation is referred. As to the mode in which this impression affects them we are ignorant. Microscopic ex- amination of the nerves connected with sensory organs would seem to show, that they come into relation with a substance very analogous to the gray mat- ter of the encephalon, although its elements are somewhat differently arranged. The nervous fibres, too, appear to terminate in close approximation with a vascular plexus ; and a granular structure is present, which — as in the vesicular portion of the brain — seems to be intermediate. This point has been regarded as the origin of the afferent fibres; and as the seat of changes made by i»'^';;'""i';." "'' ^:'piiia,ies at .ho ' . , ^ "^ surface ol the skiu ol the linger. external impressions.^ The facts mentioned show, that the action of perception takes place in the encephalon; and that the nerve is merely the conductor of the impression between the part impressed and that organ. If a ligature be put round a nerve, sensation is lost below the ligature; but it is uninjured above it. If two ligatures be applied, sensibility is lost in the portion included between the ligatures ; but it is restored if the upper ligature be removed. The spinal marrow is sensible along the whole of its posterior column, but it also acts only as a conductor of ' Art. Sensation, Cycloprpdia of Anat. and Physiology, pt. xxxiv. p. 511, Jan., 1849. * Exercitat. Anatom. Fascic, i. p. 28; and Archiv. filr die Physiologie, B. lit. ' Carpenter, Human Physiology, p. 85, Loud., 1842. 668 SENSIBILITY. tlie impression. M. Flourens destroyed tlie spinal cord from below, by slicing it away ; and found, tliat sensibility was gradually extinguished in the parts corresponding to the destroyed medulla, but that the parts above evidently continued to feel. Perception, therefore, occurs in the encephalon ; and not in the whole, but in some of its parts. Many physiologists — Haller, Lorr}^, Rolando, and Flourens' — sliced away the brain, and found that the sensations continued until the knife reached the level of the corpora quadrigemina ; and, again, it has been found, that if the spinal cord be sliced away from below upwards, the sensa- tions persist until we reach the medulla oblongata. It is, then, between these parts, that we must place the cerebral organs of the senses, and it is with this part of the cephalo-spinal axis, tliat the nerves of the senses are actually found to communicate. Mr. Lawrence^ saw a child with no more encephalon than a bulb, which was a continuation of the medulla spinalis, for about an inch above the foramen magnum, and with which all the nerves from the fifth to the ninth pair were connected. The child's breathing and temperature were natural ; it discharged urine and fseces ; took food, and at first moved very briskly. It lived four days. If we divide the posterior roots of the spinal nerves and the fifth pair, general sensibility is lost ; but if we divide the nerves of the senses, we destroy only their functions. We can thus understand why, after decapitation, sensibility may remain for a time in the head. It is instantly destroyed in the trunk, owing to the removal of all com- munication with the encephalon ; but the fifth pair is entire, as well as the nerves of the organs of the senses. Death must of course follow almost instantaneously from loss of blood; but there is doubtless an appreciable interval during which the head may continue to feel; or, in other words, during which the external senses may act.^ M. Julia Fontanelle'* has indeed concluded, from a review of all the observa- tions made on this matter, that, contrary to the common opinion, death by the guillotine is one of the most painful ; that the pains of decolla- tion are horrible, and endure even until there is an entire extinction of animal heat ! It need scarcely be said, that all these inferences are imaginative, and perhaps equally fabulous with the oft-told story of Charlotte Corday scowling at the executioner, after her head was removed from her body by the guillotine ; and this conclusion is strongly confirmed by the results of experiments on a robber — who was beheaded with the sword — by Drs. Bischoff", Heerman, and Jolly, who inferred that consciousness must have ceased instantaneousl3^* But if such be the case with man, it most assuredly is not so with the inferior animals. Ample evidence will be aflbrded hereafter to show, that both sensation and volition may persist, apparently, in the rattle- ' Rolaniio, Saggio sopra la vera Struttura del Cervello, Sassari, 1809 ; and Flourens, Recherclies Experimentales sur les Proprietes et les Fonctions du Systeme Nerveux, &c., 2de edit., Paris, 1842. * Medico-Chirurg. Transact., v. 166. ' Berard, Rapports du Phvsique et du Moral, p. 93, Paris, 1823. * Plicebus, Art. Enthauptung, in Encyclopad. Woilerb. der Medicin. Wissenchaft. xi. 204, Berlin, 1835. ^ A condensed account of Dr. Bischoff 's Remarks, from Miiller's Archiv., by S. L. L. Bigger, is in the Dublin Journal of Medical Science, Sept., 1839, p. 1. SENSOKY GANGLIA. 669 snake and alligator, long after the head has been removed from the body,. Singular facts in regard to the latter animal have been recorded by Dr. Leconte,' and by Dr. Dowler,^ of New Orleans. It has been remarked, that the cerebral hemispheres may be sliced away without abolishing the senses. The experiments of Eolando and Flourens, which have been repeated by M, Magendie, show, however, that the sight is an exception ; — that it is lost by their removal. If the right hemisphere be sliced away, the sight of the left eye is lost; and conversely ; — one of the facts that prove the decussation of the optic nerves. The experiments of these gentlemen show, that vision, more than the other senses, requires a connection with the organ of the intel- lectual faculties — the cerebral hemispheres ; and this, as M. Magendie has ingeniously remarked, because vision rarely consists in a single impression made by light, but is connected with an intellectual process, by which we judge of the distance, size, shape, &c., of bodies. It has been well suggested and maintained by Dr. Carpenter,^ that whilst the cerebral ganglia Fig. 218. are the organs of the higher intellectual and moral acts ; there is a series of ganglia, con- nected with the reception of impressions from without, which are seated near the base of the brain, and are hence termed by him sensory ganglia. As we descend in the ani- mal scale, these gangl ia become more marked; whilst the cerebral hemispheres become less and less ; until ultimately the animal appears to have its encephalic organs limited almost wholly to those that are concerned in the reception of impressions from without, and the originating of motor impulsioiis from Brain of Squirrel, laid open. within. These ganglia are seated at the The hemispheres, b, drawn to T o ,^ 1 • (• ,1 • • o .^ either side to show the subjacent base or the bram, Irom the origm of the parts, c. The optic lobes. d. cere- auditory nerves to those of the olfactory, colpu'^stttatum!'''"""'"^""''- '*• Dr. Carpenter is disposed to regard the optic thalami as ganglia for the reception of tactile impressions, and the corpora striata as ganglia connected with motion. He esteems them to be, moreover, the centre of consensual or instinctive movements, or of automatic movements involving sensation. Having arrived at a knowledge that in man and the upper class of animals perception is eftected in a part of the encephalon. our acquaint- ance with this mysterious process ends. We know not, and we proba- bly never shall know, the action of the brain in accomplishing it. It is certainly not allied to any physical phenomenon ; and if we are ever justified in referring functions to the class of organic and vital, it may be those, that belong to the elevated phenomena, which have to be considered under the head of animal functions. We know them ' New York Journal of Medicine, for Nov., 1845, p. 335, and Sir Charles Lyell, Travels in North America, Amer. edit., i. 237. New York, 1849. 2 Contributions to Physiology, New Orleans, 1849, from New Orleans Journal of Me- dicine. " Principles of Human Physiology, Amer. edit., p. 437, Philad., 1855. 670 SENSIBILITY. only by their results ; yet we are little better acquainted with many topics of physical inquiry ; — with the nature of the electric fluid for example. Fig. 219. Fig. 220. Pike. Fig. 221. Cod. J : ■:§: Brain of Turtle. A. Olfactive ganglia, b. Cerebral hemi- spheres, c. Optic gauglia. d. Cerebellum. Brains of Fishes. A. Olfactive lobes or ganglia, b. Cerebral hemi- sphere.s. c. Optic lobes. D. Cerebellum. The organs, then, that form the media of communication between the parts impressed and the brain, are the nerves and spinal marrow. M. Broussais,Mndeed, affirmed, that every stimulation capable of causing perception in the brain, runs through the whole of the nervous system of relation; and is repeated in the mucous membranes, whence it is again returned to the centre of perception, which judges of it according to the view of the viscus to which the mucous membrane belongs ; and adapts its action as it perceives pleasure or pain. AVe are totally unacquainted with the mattrial character of the fluid, which passes M"ith the rapidity of lightning along nervous cords; and it is as impossible to describe its mode of transmission, as it is to depict that of the electric fluid along a conducting wire. As in the last case, we are aware of such transmission only by the result. Still, hypotheses, as on every obscure matter of inquiry, have not been wanting.^ Of these, three are chiefly deserving of notice. The y?rs^, of greatest anti- quity, is, that the brain secretes a subtile fluid, which circulates through the nerves, called onimaJ spirits^ and Avhich is the medium of commu- nication between the dilYerent parts of the nervous system; the second regards the nerves as cords, and the transmission as efi'ected by means of the vibrations or oscillations of these cords ; whilst the third ascribes it to the operation of electricity. 1. The hj'potheses of animal spirits has prevailed most extensively. It was the doctrine of llippocrates, Galen, the Arabians, and of most ' Trrate de Physiolocie, &c., Paris, 1822 ; or translation bv Drs. Bell and La Roche, 3d Amer. edit., p. 63, Philad., 1832. ' Fletcher's Rudiments of Physiology, P. ii. b. p. 68, Edinb., 1836. INNERVATION — HYPOTHESIS OF VIBRATIONS. 671 of the physicians of the last centuries. Des Cartes' adopted it energe- tically; and was the cause of its more extensive diffusion. The great grounds assigned for the belief were ; — first^ that as the brain receives so much more blood than is necessary for its own nutrition, it must be an organ of secretion; secondly^ that the nerves seem to be a continua- tion of the tubular matter of the brain ; and it has already been re- marked, that Malpighi considered the cortical neurine to be follicular, and the medullary to consist of secretory tubes. It was not unnatural, therefore, to regard the nerves as vessels for the transmission of these spirits. As, however, the animal spirits had never been met with in a tangible shape, ingenuity was largely invoked in surmises regarding their nature; and, generally, opinions settled down into the belief that they were of an ethereal character. For the various views that have been held upon the subject, the reader is referred to Haller,^ who was himself an ardent believer in their existence, and has wasted much time and space in an unprofitable inquiry into their nature. The truth is, that we have not sufficient evidence, direct or indirect, of the existence of any nervous fluid of the kind described. Allusion has been already made to the views, in regard to the tubular structure of the white neu- rine, admitted by most observers ; Berres' affirms that the forms, which the nervous substance assumes under the magnifying glass, can only be compared to those of canals and vesicles; but whether they be hollow he does not attempt to decide. M. RaspaiP has concluded, that the opinion of their being hollow, and containing a fluid, is unsupported by facts ; for although he admits, that M. Bogros succeeded in inject- ing the nerves with mercury, he thinks that the passage of the metal along them was owing to its having forced its way by gravity. Modern histologists accord with great unanimity as to the tubular structure of the medullary neurine ; but we have no reason for considering the brain the organ of any ponderable secretion. Yet the term "animal spirits," although their existence is not now believed, is retained in popular language. We speak of a man who has a great flow of animal spirits, but without regarding the hypothesis whence the expression originated. The term nervous fluid is still used by phj^siologists. By this, how- ever, they simply mean the medium of communication or of convey- ance, by which the nervous influence is carried with the rapidity of lightning from one part of the system to another ; but without com- mitting themselves as to its character ; — so that, after all, the idea of animal spirits is in part retained, although the term, as applied to the nervous fluid, is generally exploded. Dr. Good^ directly admits them under the more modern title; Mr. J. W. Earle^ firmly believes in the existence of a circulation in the nervous sj^stem, — and it is not easy to conceive, that the brain does not possess the function of elaborating ' Tractatus de Homine, p. 17, Lugd. Bat., 16C4. * Elementa Physiologite, x. 8. '^ Oesterreicli. Med. Jahrbuch., B. ix., cited in Brit, and Foreign Med. Review, Janu- ary, 1838, p. 219. * Chimie Organique, p. 218, Paris, 1833. ^ Study of Medicine, witli Notes by S. Cooper, Doane's Amer. edit., vol. ii., in Proem to Class iv. Neurotica, New York, 1835. * New Exposition of tlie Functions of the Nerves, Part I., London, 1833. 672 SENSIBILITY. some fluid, — galvanoid or other, — whicli is tbe great agent in the nervous function. 2. The hypothesis of vibrations is ancient, but has been by no means as generally admitted as the last. Among the moderns, it has received the support of Condillac,' Hartley,^ Blumenbach,^ and others; some supposing, that the nervous matter itself is thrown into vibra- tions; others, that an invisible and subtile ether is diffused through it, which acts the sole or chief part. As the latter is conceived, by many, to be the mode in which electricity is transmitted along conducting wires, it is not liable to the same objections as the former. Simple inspection of a nerve at once exhibits, that it is incapable of being thrown into vibrations. It is soft; never tense; always pressed upon in its course; and, as it consists of filaments destined for very differ- ent functions, — sensation, voluntar}^ and involuntary motion, &c. — we cannot conceive how one of these filaments can be thrown into vibra- tion without the effect being extended laterally to others ; and great confusion being thus induced. The view of Dr. James Stark,** in re- gard to the structure of the tubes of the nerves, has led him to adopt a modification of the theory of vibrations. Believing, that the matter which fills the tubes is of an oily nature, — and as oily substances are known to be non-conductors of electricity; and farther, as the nerves have been shown by the experiments of Bischoff' to be amongst the worst possible conductors of electricity, — he contends, that the nerv- ous energy can be neither electricity nor galvanism, nor any property related to them; and he conceives, that the phenomena are best ex- plained on the hypothesis of undulations or vibrations propagated along the course of the tubes by the oily globules which as before remarked — he considers they contain. Others, as Dr. Brown Sequard^ — who observed, in experiments on animals, that nerve fibres acted nearly as well when their contents were coagulated as when they were still liquid — are of opinion, that the communication is through the sheath of the nerve, — the membranous tube (Fig. 207). 3. The last hypothesis is of later date, — subsequent to the disco- veries in animal electricity. The rapidity with which sensation and volition are communicated alonsr the nerves could not fail to suorgest a resemblance to the mode in which the electric and galvanic fluids fly along conducting wires. Yet the great support of the opinion was in the experiments of Dr. Wilson Philij)'' and others, from which it ap- peared, that if the nerve proceeding to a ])art be destroyed, — and the secretion, which ordinarily takes place in the part be thus arrested, — the secretion may be restored by causing the galvanic fluid to pass from one divided extremity of the nerve to the other. The experi- ments, connected with secretion, will be noticed more at length here- after. It will likewise be shown, that in the effect of galvanism upon ' ffiuvres, Paris, 1822. ^ ^ Observations on Man, &c., chap. i. sect. 1. London, 1791. ^ Institntiones Physiologicfle, ?; 22(J. * Proceedings of the Royal Society, No. 56, Lond., 1S43. ^ Medical Examiner, April, 1852, p. 564. ^ Philosoph. Traus. for 1815, and Lond. Med. Gazette for March 18, and March 25, 1837. EXTERNAL SENSATIONS. 673 the muscles, there is a like analogy ; — that the muscles may be made to contract for a length of time after the death of the animal, and even when a limb is removed from the body, on the application of the galvanic stimulus ; and that comparative anatomy exhibits to us great development of nervous structure in electrical animals, which astonish us by the intensity of the electric shocks they are capable of commu- nicating. Physiologists of the present day generally, we think, accord with the electrical hypothesis. The late Dr. Young,* so celebrated for his knowledge in numerous departments of science, adopted it prior to the interesting experiments of Dr. Philip ; and Mr. Abernethy,^ whilst he is strongly opposing the doctrines of materialism, goes so far as to consider some subtile fluid, not merely as the agent of nervous trans- mission but as forming the essence of life itself. By putting a liga- ture, however, around a nervous trunk, its functions, as a conductor of nervous influence, are paralyzed, whilst it is still capable of convey- ing electricity ; and, moreover, when wires are inserted into an ex- posed nerve, and their opposite extremities are attached to the galva- nometer, no movement of the needle has been observed by Person, Miiller, Matteucci, Todd and Bowman,^ and others. Dr. Bostock,** too, has remarked, that before the electrical hypothesis can be con- sidered proved, two points must be demonstrated; first, that every function of the nervous system may be peiformed by the substitution of electricity for the action of nerves ; and secondly, that all nerves admit of this substitution. This is true as concerns the belief in the identity of the nervous and electrical fluids ; but we have, even now, evidence sufficient to show their similarity; and that we are justified in considering the nervous fluid to be electroid or galvanoid in its na- ture, emanating from the brain by some action unknown to us, and transmitted to the different parts of the system to supply the expendi- ture, which must be constantly taking place. ReiV Senac,'' Prochaska, Scarpa,^ and others are of opinion, that the nervous agency is generated throughout the nervous system; and that every part derives sensation and motion from its own nerves. We have satisfactorily shown, however, that a communication with the nervous centres is absolutely necessary in all cases, and that we can immediately cut off sensation in the portion of a nerve included be- tween two ligatures, and as instantly restore it by removing the upper ligature, and renewing the communication with the brain. a. External Sensations. The external sensations are those perceptions which are occasioned by the impressions of bodies external to the part impressed. They are not confined to impressions made by objects external to us. The hand ' Med. Literature, p. 93. Lond., J813. ^ Physiological Lectures, exhibiting a view of Mr. Hunter's Physiology, &c. Lond., 1817. " The Physiological Anatomy and Physiology of Man, p. 242. Lond., 1845. * Aw Elementary System of Physiology, 3d edit., p. 148. Lond., 183(5. * De Structura Nervorum, Hal., 17915. * Traite de la Structure du Cceur, &c., liv. iv. chap. 8. Paris, 1749. ' Tabulfe Neurologicse. Ticin., 1794, § 22. VOL. I. — 43 674 SENSIBILITY. applied to any part of the body ; any two of its parts brought into contact ; or the presence of its own secretions or excretions may equally excite them. M. Adelon/ has divided them into two orders — first^ the senses^ properly so called, by the aid of which the mind acquires its notion of external bodies, and of their different qualities ; and secondly^ those sensations which are still caused by the contact of some body, and yet afford no information to the mind. It is by the external senses, that we become acquainted with the bodies that surround us. They are the instruments by which the brain receives its knowledge of the universe ; but they are only instruments, and cannot be considered as the sole regulators of the intellectual sphere of the individual. This we shall see is dependent upon another and still higher nervous organ, — the brain. The external senses are generally considered to be five in number; for, although others have been reckoned, they may perhaps be reduced to some modification of these five, — tact or touchy taste, smell, hearing, and vision. All these have some properties in common. They are situate at the surface of the body, so as to be capable of being acted upon with due facility by external bodies. They all consist of two parts; — the one, physical, which modifies the action of the body, that causes the impression ; the other nervous or vital, which receives the impression, and conveys it to the brain. In the e3'e and the ear, we have better exemplifications of this distinction than in the other senses. The physical portion of the eye is a true optical instrument, which modifies the light, before it impinges upon the retina. A similar modi- fication is produced by the physical portion of the ear on the sonorous vibrations before they reach the auditory nerve ; whilst, in the other senses, the physical portion forms a part of the common tegument in which the nervovis portion is seated, and cannot be easily distinguished. Some of them, again, as the skin, tongue, and nose, are symmetrical, that is, composed of two separate and similar halves, united at a median line. Others, as the eye and ear, are in pairs ; and this, partly per- haps, to euable the distances of external objects to be appreciated. We shall find, at least, that there are certain cases, in which both the organs are necessary for accurate appreciation. Two of the senses — vision and audition — have, respectively, a nerve of special sensibility; and, until of late years, the smell was universally believed to be similarly situate. In the present state of our knowledge, we cannot decide upon the precise nerve of taste, although it will be seen that a plausible opinion may be indulged on the subject. The general sense of touch or feeling is certainly seated in the nerves of general sensibility connected with the posterior roots of the spinal nerves, and the fifth encephalic pair ; and according to some,^ in the glosso-pharyngeal and pneumogastric nerves. The other senses seem intimately connected with one nerve of general sensibility, — the fifth pair. This is especiall}^ the case with those senses that possess nerves ' of special sensibility ; for, if the fifth pair be cut, the function is abo- lished or impaired, although the nerve of special sensibility may remain entire. ' Pliysiologie de I'llomme, torn. i. p. 250, 2de edit. Paris, 1829. * Louget, Traite de Physiologie, ii. 17tJ, uote. Paris, 1850. EXTERNAL SENSATIONS. 675 Being instruments by which the mind becomes acquainted with external bodies, it is manifestly of importance, that the senses should be influenced by volition. Most of them are so. The touch has the pliable upper extremity, admirably adapted for the purpose. The tongue is movable in almost every direction. The eye can be turned by its own immediate muscles towards objects in almost all positions. The ear and the nose possess the least individual motion ; but the last four, being seated in the head, are capable of being assisted by the muscles adapted for its movements. All the senses may be exercised passively and actively. By directing the attention, we can render the impression more vivid ; and hence the difference between simply seeing or passive vision, and looking atten- tively ; between hearing and listening; smelling and snuffing; touching and feeling closely. It is to the active exercise of the senses, that we are indebted for many of the pleasures and comforts of social existence. Yet, to preserve the senses in the vigour and delicacy, which they are capable of acquiring by attention, the impressions must not be too constantly or too strongly made. The occasional use of the sense of smell, under the guidance of volition, may be the test on which the chemist, perfumer, or wine-merchant, may rely in the discrimination of the numerous odorous characteristics of bodies ; but, if the olfactory nerves be constantly, or too frequently, stimulated by excitants, of this or any other kind, dependence can no longer be placed upon them as a means of discrimination. The maxim that "habit blunts feeling,"' is true only in such dases as the last. Education can, indeed, render it extremely acute.' Volition, on the other hand, enables us to deaden the force of sensations. By corrugating the eyebrows, and approxi- mating the eyelids, we can diminish the quantity of light when it is too powerful. We can breathe through the mouth, when a disagree- able odour is exhaled around us ; or, with the aid of the upper ex- tremity, can completely shut off its passage by the nostrils. Over the hearing we have less command as regards its individual action: the upper extremity is here always called into service, when we desire to diminish the intensity of any sonorous impression. Lastly. It is a common observation, that the loss of one sense occa- sions greater vividness in others. This is only true as regards tlie senses that administer chiefly to the intellect, — those of touch, audition, and vision, for example. Those of smell and taste may be destroyed; and yet the more intellectual senses may be uninfluenced. In the singular condition of artificial somnambulism or hypnotism, the author has seen the various senses rendered astonishingly acute. The cause of the superiority of the remaining intellectual senses, when one has been lost, is not owing to any superior organization in those senses; but is another example of the influence of education. The remaining senses are exerted attentively to compensate for the privation ; and they become surprisingly delicate. "We proceed to the consideration of the separate senses, beginning with that of tact or toucli^ because it is most generally distributed, and ' Burard, Rapport du Physique et du Moral, p. 245 ; Pans, 1823. 676 * SENSIBILITY. may be regarded as that from whicli the others are derived. They are all, indeed, modifications of the sense of touch. In the taste, the sapid body; in the smell, the odorous particle; in the hearing, the sonorous vibration ; and in the sight, the particle of light, must impinge upon or touch the nervous part of the organ, before sensation can, in any of the cases, be effected. A. SENSE OF TACT OR TOUCH— PALPATION. The sense of tact or touch is the general feeling or sensibility, pos- sessed by the skin especially, which instructs us regarding the tempe- rature and general qualities of bodies. By some, touch is restricted to the sense of resistance alone; and hence they have conceived it necessary to raise into a distinct sense one of the attributes of tact or touch. The sense of heat, for example, has been separated from tact ; but although the appreciation of external bodies by tact or touch diflers — as will be seen — in some respects from our appreciation of their temperature, its consideration properly belongs to the sense we are considering, in the acceptation here given to it, and adopted by all the French physiologists. According to them, tact is spread generally in the organs, and especially in the cutaneous and mucous surfaces. It exists in all animals; whilst touch is exercised only by parts evidently destined for that purpose, and is not present in every animal. It is nothing more than tact joined to muscular contraction and directed by volition. So that, in the exercise of tact, we may be esteemed jjas- sive ; in that of touch, active. The organs concerned in touch, execute other functions besides; and in this respect touch differs from the other senses. Its chief organ, however, is the skin; and hence it is necessary to inquire into its struc- ture, so far as is requisite for our purpose. 1. ANATOMY OF THE SKIN, HAIR, NAILS, ETC. The upper classes of animals agree in possessing an outer envelope or skin, through which the insensible perspiration passes ; a slight de- gree of absorption takes place; the parts beneath are protected ; and the sense of touch is accomplished. In man, the skin is generally considered to consist of four parts, — the cuticle, rete mucosuin, corpus papillare, and corium; but when reduced to its simplest expression, the whole of the integument, with the mucous membrane, which is an ex- tension of it, may be regarded as a continuous membrane, more or less involuted, more or less modified by the elementary tissues which com- pose it or are in connexion with it, and within which all the rest of the animal is contained. It consists of two elements — a hasement tksue or inemhrane, composed of simple membrane, uninterrupted, homo- geneous, and transparent; covered by an epithelium or pavement of nucleated particles.' 1. The epidermis or cuticle is the outermost layer. It is a dry, mem- branous structure, devoid of vessels and nerves; yet it is described by some modern investigators as a tissue of a somewhat complex organiza- ' Todd and Bowman, Tlie Physiological Anatomy and Physiology of Man, p. 404, London, 1845. ORGANS OF TOUCH. * 677 tion, connected with the functions of exhalation and absorption; but its vitality is regarded to be on a par with that of vegetables. The absence of nerves proper to it renders it insensible; it is coloured; and exhales and absorbs in the manner of vegetables. It is, so far as we know, entirely insensible; resists putrefaction for a long time, and may be easily obtained in a separate state from the other layers by maceration in water. It is the thin pellicle raised by a blister. The cuticle is probably a secretion or exudation from the true skin, which concretes on the surface ; becomes dried, and aftbrds an efi&cient protection to the corpus papillare beneath. It is composed, according to some, of concrete albumen ; according to others, of mucus ; and is j^erced by oblique pores for the passage of hairs, and for the orifices of exhalant and absorbent vessels. MM. Breschet and Roassel de Vau- zeme^ affirm, that there is a special '"'' hlennogenous or mucijic apparatus''' for the secretion of this mucous matter, composed of a glandular paren- chyma or organ of secretion situate in the substance of the derma, and of excretory ducts, which issue from the organ, and deposit the mucous matter between the papillce ; but such an apparatus is not admitted. It is probable, that the cuticle is placed at the surface of the body, not simply to protect the corpus papillare; but to prevent the constant imbibition and transudation that might take place did no such envelope exist. It exfoliates, in the form of scales, from the head; and in large pieces, from every part of the body, after certain cutaneous diseases. M. Flourens,^ who has closely and accurately investigated the ana- tomy of the cutaneous envelope, considers that the skin of the coloured races has an apparatus, which is wanting in the white variety of the species. This apparatus he names pigmental, — appareil pigmental. It is composed of a layer {lame) or membrane which bears the pigment, and of the pigment itself. Above it are two cuticles. In the white variety the pigmental apparatus is wanting, and consequently the skin is more simple than that of the coloured races. The skin of the white variety approaches that of the coloured in some remarkable points. First. — The superficial layer or lame of the derma is everywhere of a peculiar appearance, which is different from that of the rest of the derma. Secondly. — Around the nipple of the white woman, the super- ficial layer of the derma presents the same granular appearance as the pigmental memlrarte of the coloured races. And tliirdly. — The pAgmental layer around the nipple of the white woman is placed, as in the coloured races, under the two cuticles. Modern histologists consider the epidermis to be composed of a series of flattened, scale-lilce cells, epidermic cells^ which, when first formed, are of a spheroidal shape; but gradually dry up. These form various layers. According to M. Kaspail,^ it consists of a collection of vesicles deprived of their contents, closely applied together, dried and thrown off' in the form of branny scales. He regards it as the outer layer of the corium. The epidermoid tissues have the simplest structure of any solids. Analysis has shown, that the chemical constitution of the mem- ' Nouvelles Reclierches sur la Structure de la Peau, par M. Breschet, Paris, 1835. ^ Anatomic Generale de la Peau et d(^s Membraiied Muqueuses, p. 34, Paris, 1843. ' Chimie Orgauique, p. 245, Paris, 1833. 678 SENSIBILITY Fig. 222. Scrotum of a Negro. a. Deep cells, loaded with pigment, h. Cells at a higher level, paler and nrnre flattened, c. Cells at the surface, scalv and oolourles.s as in the white races. — Magnified 300 diameters. ==^^=.- branous epidermis of tbe sole of the foot is the same as that of the compact horny matter of which nails, hair, and wool are composed. 2. The corpus or rete mncosum, rete Jfalpic/hn, mucous web, is generally reorarded as constituting? the next layer. It was considered by Mal- pighi to be mucus, secreted by the papillas, and spread on the surface of the corpus papillare, to preserve Vertical Section of the Cuticle, from the it ill the State of SUppleueSS UeCCS- """' ' sary for the performance of its func- tions. In this rete mucosum, the colouring matter of the dark races seems to exist. It is black in the African, or rather in the Ethiopian ; and copper-coloured in the mulatto.' Gaultier^ considers it to be composed of four layers; but this notion is not admitted by anatomists, and scarcely concerns the present inquiry. M. Breschet affirmed, that there is a spe- cial ^^ chromalogenous or colorific appn- ratus,''^ for producing the colouring matter, composed of a glandular or secreting parenchyma, situate a little below the papilhis, and presenting special excretory ducts, which pour out the colouring matter on the sur- face of the derma. Modern observers deny, that there is any such distinct layer. Some regard it as the deepest or most recently formed part of the cuticle. M. Flourens'' considers, that the term corpus mucosum ought to be replaced by that of pigmental apparatus, — appareil pigmental ; and s seen in the palm" of the hand or 'sole Jf that thc tCrm TCte OT COriJUS Veticulave nt; they are CDniposed of minute conical . , . . „ . „ -' . , ^■ ---^ .■^■fl Section of the Skin. 1. Cuticle, showing the oblique laminjE of ■which it i.s composed, and the imbricated dispo- sition of the ridges upon its surface. 2. Rete mu- cusum. 3. Two of the quadrilateral papillary masses the foo,, ...._, „ ,,„..,. ., ^ ... . . .„ . „ . , papilla;. 4. Deeper layer of the cutis, the corium. m the Signification of a SpCCial net r>. Adipose vesicles; showing their appearance i -^ j n ^ ,i i i beneath the microscope. 6. Perspiratory gland WOrlC SltUatC bCtWeen the dcrma aUQ with its s])iral duct, as seen in the palni of the +l-,p f^^ pntiplpd nno-lit tr> Kp> 'hnniQliPfl hand or sole of the foot. 7. Another perspiratory ^^le IWO OUllCitS, OU g ni 10 DC OaUlbnea giandwith astraighterduct.suchasseeniuthe from auatomv. The naturc of the scalp. 8. Two hairs from the scalp, enclosed in . -n i pit p their follicles; their relative depth in the skin pigment Will DC rCierred tO hereaiter, preserved. 9, A pair of.sebaceous glands open- ^^^^^^^ SECRETION. The rete mucosum is considered to be the last formed portion of the cuticle. 3. The corpus piajjillare, or what M. Breschet calls the ^'■neurothelic or mammillary nervous apparatus,^^ \s seated next below the rete mucosum. It consists of a collection of small papillae, formed by the extremities ing by short duets into the follicle of the hair. ' Sir E. Home, Lect. on Comp. Anat., v. 278. '^ Recherches Anatomiques sur le Systeme Cutani^ de rHomme, Paris, 1811. ' Op. cit., p. 38. ORGANS OF TOUCH. • 679 of nerves and vessels, winch, after having passed through the corium beneath, are grouped in small pencils or villi on a spongy, erectile tissue. These pencils are disposed in pairs, and, when not in action, are relaxed, but become Fig. 224. erect when employed in the sense of touch. They are very readily seen, when the cutis vera is exposed by the action of a blister; and are always evident at the palmar surface of the hand, and especially at the tips of the fingers, i-^^Mp^'^-^'^T;-)^ where they have a concentric arrangement. — -— -_j--j These villi are sometimes called vamllce. They rnpiHasof thePaim.the Cu- ,. , . nil- 1 tide being detached. — Mag- are, m reality, prolongations ot the skm; and nified 35 diameters. consequently — as M. Flourens^ has remarked — "the pretended corjms pajnllare^ taken as a body, apart and distinct from the derma, is but an idle name." In parts that are endowed with much tactile sensibility, the cutaneous nerve fibres — as of the papillae of the palm of the hand — terminate in the corpuscles of touch already mentioned.^ 4. The corium^ cutis vera^ derma or true slan, is the innermost layer of the skin. It consists of a collection of dense fibres, intersecting each other in various directions; and leaving between them holes for the pafisage of vessels and nerves. It forms a firm stratum, giving the whole skin the necessary solidity for accomplishing its various ends; and consists chiefly of gelatin; — hence it is used in the manufacture of glue. Gelatin, when united with tannic acid, forms a substance which is insoluble in water; and it is to this combination that leather owes the properties it possesses. The hide is first macerated in lime-water to remove the cuticle and hairs, and leave the corium or gelatin. This is then placed in an infusion of oak bark, which contains tannic acid. The tannic acid and the skin unite; and leather is the product. These four strata constitute the skin, as it is commonly called; yet all are comprised in the thickness of two or three lines. The cutis vera is united to the structures below by areolar tissue; and this, with the layers external to it, forms the common integument. In certain parts of the body, and in animals more particularly, the cutis vera is ad- herent to muscular fibres, inserted more or less obliquely. These form the muscular weh, mantle, or pannicuhis carnosus. The layer is well seen in the hedgehog and porcupine, in which it rolls up the body, and erects the spines; and in birds raises the feathers. In man, it can hardly be said to exist. Some muscles, however, execute a similar function. By the occipito-frontalis, many persons can move the hairy scalp ; and by the dartos the skin of the scrotum can be corrugated. These two parts, therefore, act as pariniculi carnosi. The skin itself also possesses smooth muscular fibres, which give occasion to its contractility, as seen in the corrugation of the scrotum, the erection of the nipple, and the phenomena of the cutis anserina. ' Op. cit., p. 38. 2 Page t)40. Seo, on the nature of these bodies, Wagner, in Miiller's Archiv., 1852, Heft 4; Kolliker, Mikioskopische Anatomie, Bd. ii. S. 24; and Amer. edit, of Sy- denham Society':* edition of his Human Histology, by Dr. Ua Costa, p. 129, Philad., 1854; and Mr. Huxley, Quarterly Journal of Microscopical Science, ii. 1. 680 SENSIBILITY. These have been found by Froriep, Brown-Sequard, and Kcilliker to contract on the application of electricity.-' The cutis anserina consists in local contractions of the portions of the skin around the hair fol- licles, by which their apertures are protruded conically, by muscular fibres discovered by Kcilliker, which pass obliquely from the super- ficial part of the cutis down to the follicles, and, when they contract, protrude the follicles, and retract those portions of the skin whence they arise. In the skin are situate numerous sebaceous follicles or crypts, which separate an oily fluid from the blood, and pour it over the surface to lubricate and defend it from the action of moisture. They are most abundant, where there are folds of the skin, or hairs, or where the sur- face is exposed to friction. We can generally see them on the pavilion of the ear, and their situation is often indicated by small dark spots on the surface, which, when pressed between Fig- 225. the fingers, may be forced out along with the sebaceous secretion, in the form of small worms. By the vulgar, indeed, they are considered to be worms. The follicular secretions have engaged atten- tion elsewhere. The consideration of the hair belongs naturally to that of the slcin. The roots are in the form of bulbs ; taking their origin in small follicles or open sacs, hair follicles, formed by the inversion of the cutis, and lined by a reflexion of the epidermis. Around each bulb there are two capsules, the innermost of which is vascular and a continuation of the co- rium. The hair itself consists of a horny, external covering, and a central part, called medulla or pith. When we take hold of a hair by the base, with the thumb and forefinger,- and draw it through them from tlie root towards the point, it feels smooth to the touch ; but if we draw it through from the point to the root, we feel the surface rough; and it offers con- siderable resistance. It is, therefore, concluded, that the hair is bristled, im- bricated, or consists of eminences point- Sections of Hair. a. Transverse section of a hair of the head, sliowing the exterior cortex, the meilulla or pith with its scattered pigment, and a cen- tral space filled with pigment, b. A similar section of a hair, at a point where no aggre- gation of pigment in the axis exists. c. Longitudinal section, without a central ca- vity, showing the imbrication of the cortex, and the arrangement of the pigment in the Hbrous part. d. Surface showing the sinu- ous transverse lines formed by the edges of the cortical scales, d'. A portion of the margin, showing their imbrication. — Mag- nified 150 diameters. ing towards its outer extremity, and it is upon this structure, that the o{)eration of felting is dependent — the hairs being mechanically entangled and retained in that state by the » ' Ki'iUiker, Experiments, &c., on the Body of an Executed Criminal, in Goodsir's Annals of Anatomy and Patholosiy, for Maj^ 1852, No. 2, p. 109 ; and Mikroskopische Anato- niie ; or Amer. edit., by Dr. Da Co.sta, of Sydenham Society's edition of his Manual of Hiatology, by Messrs. 13usk and Huxley, p. 1'66, Philad., 1854. TOUCH — HAIR. 681 inequalities of tlieir surface. Certain observers have, however, failed in detecting this striated appearance by the aid of the microscope; and Dr. Bostock' affirms, that he had an opportunity of viewing the human Fig. 227. Thin Layer from the Scalp. a, a. Sebaceous with its follicle, c. glands. 6. Hair, Magnified view of the Root of the Hair. a. Stem or shaft of hair cut across, h. Inner, and c, outer layer of the epidermic lining of the hair follicle, called also the root-sheath, d. Dermic or external coat of the hair follicle, shown in part. e. Imbricated scales about to form a cortical layer on the surface of the hair. hair, and the hair of various kinds of animals, with the excellent micro- scope of Mr. Bauer, but without being able to observe it. Bichat,^ however, and more recently. Dr. Goring,^ and most histologists, have assigned this as their structure; and the author has had repeated op- portunities for confirming it. Modern observers believe, that, as in other structures, growth takes place from cells, which are a modification of those of the epidermis. The primary cells become elongated, and generate within themselves fasciculi of fibres or secondary cells, which interlace to form the hair cylinder. The walls of these fibre-cells are at first soft and permeable; and the lower part of the hair, which is composed of them, seems to admit the passage of fluid without much difficulty. At a short dis- tance from the base, the horny character of the hair, caused by the deposit of horny matter in the interior of the fibres, becomes appa- rent. "There is then, at the base, a continual formation of soft fibrous tissue, by which the length of the cylinder is increased; whilst at a short distance above it, there is a continual consolidation of this (as it progressively arrives at that point) by the deposit of a peculiar secre- tion in its substance."* The shape of the hair is different in different races. It is described Pliysiology, p. 52, 3d edit., Lond., 183G". .Tournal of Science, New Series, vol. i. 433. 2 Anat. General., torn. iv. § 2. * Carpenter, Human Physiology, § (537. Lond., 1842. 682 SENSIBILITY. as cylindrical in the American Indian; oval in the white man, and eccentrically elliptical or flat in the negro.^ Its colour also differs in different races and individuals. By some, this is considered to depend upon the fluids contained in the pith. M. Vauquelin^ analyzed the hair attentively, and found it to consist chiefly of an animal matter, united to a portion of oil, which appeared to contribute to its flexi- bility and cohesion. Besides this, there is another substance, of an oily nature, from which he considers the colour of the hair is derived. The animal matter, according to that chemist, is a species of mucus; but other chemists believe it to be chiefly albumen. Vauquelin found, that the colouring matter is destroj^ed by acids; and he suggests, that when it has suddenly changed colour and become gray, in consequence of any mental agitation, this may be owing to the production of an acid in the system, which acts upon the colouring matter. The expla- nation is hypothetical, and is considered, and characterized as such by Dr. Bostock ; but it must be admitted, that the same objection applies to the view he has substituted for it. He conceives it " more probable that the effect depends upon a sudden stagnation in the vessels, which secrete the colouring matter; while the absorbents continue to act, and remove that which already exists." There is, however, no more real evidence of " stagnation of vessels" than there is of the formation of an acid. Our knowledge is limited to the fact, that a sudden and decided change in the whole pileous system may occur after great or prolonged mental agitation. " My hair is gray, but not with years, Nor grew it white in a single night, As men's have grown from sudden fears." Byron's ^'Prisoner of Chillon." " Danger, long travail, want and wo, Soon change the form that best we know : For deadly fear can time outgo, And blanch at once the hair. Hard toil can roughen form and face, And want can quench the eye's bright grace, Nor does old age a wrinkle trace Moi-e deeply than despair." Scott's '■'■Mannion." It is stated,^ that such a change occurred in a single night to the queen of Louis the 16th — the unfortunate Marie Antoinette — when the royal party was arrested at Varennes, in 1791.'' But a similar, though more gradual change is produced by age. We find some persons entirely gray at a very early period of life ; and, in old age, the change happens universally. It is not then dif- ficult to suppose, that some alteration in the nutrition of the hair may ' P. A. Browne, The Classification of Mankind by the Hair and Wool of their Heads, p. 4, Philad., 1850, and Trichologia Mammaliura, p. 51. Philad., 1853. ^ Annales de Chiinie, tom. Iviii. p. 41, Paris, 1806. 3 " La reine ne dormit pas. Toutes ses passions, de femme, de mere, de reine, la colere, la terreur, la desespoir, se livrerent un tel assaut dans son a,me, que ses che- veux, blonds la vieille, furent blancs le lendemaiu." — De Lamartine, Histoire des Girondins, i. 116. Paris, 1847. * Several cases are recorded in Mr. Erasmus Wilson, Healthy Skin, Amer. edit., p. 114, Philad., 1854. TOUCH — HAIR. 683 supervene, resembling that whicli occurs in the progress of life. Dr. Bostock doubts the fact of such sudden conversions; but the instances are too numerous for us to consider them entirely fabulous. Still, it is difficult to comprehend how parts, which, like the extremities of the hair, are foreign to nutrition, can change so rapidly. M. Lepelletier^ ascribes it to two very different causes. First^ to defective secretion of the colouring fluid, without any privation of nutrition. In this case, the hairs may live and retain their hold, as we observe in young individuals: — and secondly^ to the canals, which convey the fluid into the hair being obliterated, as in old age. The same cause, acting on the nutritious vessels of the bulb, produces successively, privation of colour, death, and loss of those epidermoid productions. A case re- lated by M. Faget^ — and which he esteems authentic — is, as he pro- perly remarks, in near relation to those in which the hair grows quickly gray in mental anguish. A lady, who is subject to attacks of what are called nervous headaches, always finds in the morning, after one of them, that some patches of her hair are white, as if powdered with starch. " The change is effected in a night, and in a few days after, the hairs gradually regain their dark brownish colour." According to other physiologists, the seat of colour is in the horny covering of the hair ; and in the largest hairs or spines of the porcu- pine this seems to be the case, the pith being white, and the horny covering coloured. There is often an intimate relationship observed between the colour of the hair and that of the skin. A fair complex- ion is accompanied with light hair ; a swarthy with dark ; — and we see the connexion still more signally displayed in those animals that are spotted, — the colour of the hair being variegated like that of the skin. Hairs differ materially according to the part of the body on which they grow. In some parts they are short, as in the armpits ; whilst on the head it is not easy to say what would be the precise limit to the growth, were they left entirely to nature. In the Malay, it is by no means uncommon to see them touch the ground. The hair has various names assigned to it, according to the part on which it appears, — heard, ivhislcers, mustachios, eyebrows, eyelashes, &c. In many animals it is long and straight; in others crisped, when it is called luool. If stiff", it is termed a bristle; if inflexible, a spine. It is entirely insensible, and, excepting in the bulbous portion, is not liable to disease. Dr. Bostock affirms, that under certain circumstances hairs are subject to a species of inflammation, when vessels may be detected, at least in some of them, and they become acutely sensitive. Their sensibility under 'any known circumstance may be doubted. They appear to be anorganic, except at the root ; and, like the cuticle, resist putrefaction for a length of time. The parts that do not receive vessels are nourished by transudation from those that do. Bichat and Gaultier were of the opinion of Di\ Bostock, — misled, apparently, by erroneous reports concerning plica polonica ; but Baron Larrey^ has ' Traits de Physiologie MMioale et Philosophiqiie, torn. iii. p. 42, Paris, 1832. 2 Lectures on Surgical Pathology, Amer. edit., ]>. 44, Philad., 1854. ' Memoires de Chirurgie Militaire, t, iii. 108, Paris, 1812. 684 SENSIBILITY. satisfactorily shown that plica is confined to the bulbs : the hairs them- selves continue devoid of sensibility. It is diffiofilt to assign a plausible use for the hair. That of the head has already engaged attention ; but the hair, which appears on certain parts at the age of puberty and not till then, and that on the chin and upper lip of the male sex only, set our ingenuity at defiance. In this respect, the hair is not unique. Many physiologists regard certain parts, which exist in one animal, apparently without function, but which answer useful purposes in another, to be vestiges indicating the harmony that reigns through nature's works. The generally use- less nipple and mamma of one sex might be looked upon in this light; but the tufts of hair on various parts cannot, in any way, be assimi- lated to the hairy coating that envelopes the bodies of animals ; and is, in them, manifestly intended as a protection against cold. There is another class of bodies connected with the skin, and ana- logous in nature to the last described, — the nails. These serve a useful purpose in touch, and consequently require notice here. In Fig. 229. Section of the Skin on the end of the Finger. The cuticle and nail, n, detached from the cutis and matrix, m. A transverse Section of a Finger-Nail, showing the manner in which it is connected with the sensitive skin by its under surface. a. The nail laminated in texture, h 6. The vor- tical plates of its under surface, c e. The sensitive skin, which sends up folds hetween the plates of the nail. d. A small bloodvessel supplying the sensitive skin and its folds. the system of De Blainville, they constitute a subdivision of the haii'.s, which he distinguishes into simple and com.poi(7id, — simple, when eae-h bulb is separated, and has a distinct hair ; — compound, when several pileous bulbs are agglomerated, so that the different hairs, as they are formed, are cemented together to constitute a solid body of greater or less size, — nail, scale, horn, &c. In man, the nail alone exists ; the chief and obvious use of which is to support the pulp of the finger, whilst it is exercising touch. Animals are provided with horns, beaks, hoofs, nails, spurs, scales, &c. All these, like the hair, gi-ow from roots; and are considered to be analogous in their physical and vital properties. Meckel, De Blainville, Bonn, Walther, Lavagna, and others, are of opinion, that the teeth are of the same class; and that they belong, originally, to the skin of the mouth. The nails, near their origin, are seen, under the microscope, to con- sist of primary cells, almost identical with those of the epidermis ; these gradually dry into scales; and the growth of the nail appears to be effected by the constant generation of cells at its root and under sur- face; and as successive layers are pushed forward, each cell becomes TOUCH — MUCOUS MEMBRANES. 685 larger, flatter, and drier, and more firmly fixed than those around it.^ The chemical composition of the epidermis and the nails is similar to that of the hair: yet according to Mulder,^ there are material differ- ences in their properties; — the latter, being almost insoluble in strong acetic acid, in which the other two are readily soluble: hence — he infers — the composition of hair and of horn and whalebone must differ materially ; and, that, accordingly, Scherer's conclusion, that they are all identical is incorrect. The following are the results of the analysis of each of these bodies. Epidermis. Horn. Whalebone. Hair. c. 50-28 ■ 51-03 51-86 50-65 H. 6-76 6-80 6-87 6-36 N. 17-21 16-24 15-70 17-14 0. 25-01 22-51 ■21-97 20-85 s. 0-74 3-42 3-60 5-00 For physiological purposes, the above description is sufficient. Mucous Memhranes. — A few words will be necessary regarding the mucous membranes, which resemble the skin so much in their properties, as to be, with propriety, termed dermoid. If we trace the skin into the various outlets, we find, that a continuous, soft, velvety membrane exists through their whole extent ; and, if the channel has two outlets, as in the alimentary canal, this membrane, at each outlet, commingles with the skin ; and appears to differ but slightly from it. So much, indeed, do they seem to form part of the same organ, that physiologists have described the absorption, that takes place from the intestinal mucous membrane, as external. They cannot, however, in the higher order of animals, be considered com- pletely identical ; nor is the same membrane alike in its whole extent. They have all been referred to two great surfaces; — the gastro-'pulmo- nary — comprising the membranes of the outer surface of the eye, ductus ad nasum, nose, mouth, and respiratory and digestive passages; and the geniio-urinary — which line the whole of the genital and uri- nary apparatuses. In addition to these, a membrane of similar cha- racter lines the meatus auditorius externus, and the excretory ducts of the mammae. A Fig. 230. B Separated Epitheliurn Cell? from mucous membrane of mouth. h. With nuclei, c. And nucleoli. Pavement-Epithelium of the Mucous Membrane of the sm.iller bronchinl tubes. a. Nuclei with double nucleoli. The analogy between the skin and mucous membranes is farther shown by the fact, that if we invert the polypus, the mucous membrane ' Henle, edit, cit., i. 289, Paris, 1843. * The Chemistry of Vegetable and Animal Physiology, translated by Fromberg, p. 527. Edinb. and Loudon, 1849. 686 SENSIBILITY. gradually assumes the cliaracters of skin ; and the same circumstance is observed in habitual descents of the rectum and uterus. In the mucous membranes — especially at their extremities, which appear to be alone concerned in the sense of touch — the same super- position of strata is generally considered to exist as in the skin — viz., epidermis or epithelium, rete mucosum, corpus papillare, and cutis vera. They have, likewise, similar follicles, called mucous ; but nothing analogous to the hairs ; unless we regard the teeth to be so, in correspondence with the views of Meckel, De Blainville, and others. The attention of anatomists has been closely directed to the ultimate structure of the mucous system. In the*mucous tissues two structures have been separately described, — especially by Mr. Bowman,^ who has thrown much light on the subject. These are the hasement membrane — as he terms it — and the epithelium. The former is a simple, homoge- neous expansion, transparent, colourless, and of extreme tenuity, situate on its parenchymal surface, and giving it shape and strength. This serves as a foundation on which the epithelium rests. It may fre- quently be demonstrated with very little trouble in the tubuli of the glands, especially of the kidney, which are but very slightly adherent, by their external surface, to the surrounding tissue. M. Flourens^ considers that every mucous membrane is composed of three laminas or layers, — the derma, epidermis, and corpus mucosum situate between the derma and epidermis. The corpus mucosum of mucous membranes is continuous at all the outlets of the body, and is identical with the second epidermis ; differing, therefore, from the corpus mucosum of the skin, a term which — as elsev/here remarked — he thinks ought to be abolished. Histological examination exhibits the epithelium to consist of cells, which are termed epithelial^ and have various shapes. The two chief are tesselated or pjavenient epithelium^ and cylinder or cortical epithelium. Epithelium is not, however, confined to mucous membranes, but, of late years, has been found to exist elsewhere ; it is always in contact with fluids, and of a soft, pliant character. Tesselated epithelium covers the serous and synovial membranes, the lining membrane of the blood-vessels, and the mucous membranes, except where cylinder epithelium exists. It is spread over the mouth, pharynx and oesophagus, conjunctiva, vagina, and en- trance of the female urethra. The cells com- posing it are usually polj^gonal; and are well seen in the marginal figure. Cylinder epithelium v^'"^ is found in the intestinal canal, beyond the car- Tesseiated Epithelium. diac orificc, in the larger ducts of the salivary Extremity of one of the tu- glauds, in the ductus couimunis choledochus, bun unniten, from the kidney <-' ' _^ i ^ ^ ■ ^ • i of an adult ; ^huwing its tes- prostatc, Cowpcr s glands, vesicula3 seminales, selated epithelium. — Magnified ^ ^ c i. i t . . ,, . -■ ■, r . i 2oo diameters. vas deiereus, tuDuli urmiien, and urethra oi the male ; and lines the urinary passages of the female from the orifice of the urethra to the beginning of the tubuli ' Cyclopaedia of Anat. and Plivsioloffv, pt. xxiii. p. 486, April, 1842. ^ Op. cit.,p. 80. PHYSIOLOGY OF TOUCH. •687 uriniferi of the kidnej. In all these situations, it is continuous with tesselated epithelium, which lines the more delicate ducts of the various Fig. 232. Scales of Tesselated Epithelium. A. Section of epithelium of conjunctiva with some scales loosened, b. Scales from surface of cheek, c. The more deeply seated scales from the human conjunctiva. glands. The cells have the form of long cylinders or truncated cones, arranged side by side, the apices attached to the mucous membrane or to flat epithelial cells lying upon it ; the base being free. Each cell, nearly midway between the base and apex, encloses a flat nucleus with Fig. 233. / Cylinders of Intestinal Epithelium, (After Henle.) A. From the cardiac region of the human stomach. B. From jejunum, c. Cylinders seen when look- ing on their free extremities, d. Ditto, as seen in a transverse section of a villus. » nucleoli. Epithelium is sometimes furnished with cilia^ or is said to be ciliated. The nature and uses of these cilia, as well as the different varieties of mucous membrane, will be described hereafter. 2. PHYSIOLOGY OF TACT AND TOUCH. In describing the physiology of the sense of touch, it will be conve- nient to revert to the distinction already made between the sense when passively and actively exerted ; or between tod, and touch. The mode, however, in which the impression is made is in each case alike, and equally simple. It is merely necessary, that the substance, which causes it, should be brought in contact with what may be termed the physical part of the organ — the cuticle ; the nervous part is seated in the corpus papillare, for if the nerves proceeding to this layer of the skin be cut, the sense is destroyed. In the exercise of touch, each of the layers seems to have its appropriate office: the corium, the inner- most layer, the base on which the others rest, offers the necessary resistance, when bodies are applied to the surface ; the rete mucosum is unconcerned in the function : the erectile tissue, on which the papillas are grouped, probably aids them in their appreciation of bodies ; and the epidermis modifies the tactile impression which might become too intense, or be painful, did this anorganic envelope not exist. The degree of perfection of the sense is greatly influenced by the state of 688 SENSIBILITY. the cuticle. Where thin — as upon the lips, glans penis, clitoris, &c. — the sense is very acute ; where thick and hard, it is obtuse ; and where removed — as by blistering — the contact of bodies gives pain, but does not occasion the appropriate impression of touch. Professors Weber^ and Valentin^ have shown that the tactile power of the skin is not proportionate to its sensibility. The mammae, for example, are easily tickled, and susceptible of great pain when irritated; yet they are moderately endowed with the sense of touch. The difterent parts of the skin, too, vary in their tactile power. The left hand, in most persons, is more sensible to temperature than the right, probably owing to the epidermis being thinner from less use. Weber made various experiments for the purpose of determining the relative sensibility of difterent portions of the skin, by touching the surface with the legs of a pair of compasses, the points of which were inserted into pieces of cork. The person's eyes being closed at the time, the legs were brought together so as to be separated by difterent distances. The following are some of the results of his ex- periments. Point of middle finger Point of tongue . Palmar surface of third finger . 1 Red surface of lips . . 2 Palmar surface of middle finger . 2 Dorsal surface of third finger • 3 Tip of the nose ... 3 Dorsum and edge of tongue . 4 Part of lips covered by skin . 4 Palm of hand ... 5 Skin of cheek ... 5 Extremity of great toe . . 5 Hard palate ... 6 Dorsal surface of fore finger . 7 Dorsum of hand . Weber found, that the seemed to be greater, alt Lines. Mucous membrane of gums 9 Lower part of forehead . 10 Lower part of occiput . 12 Back of hand 14 Neck, under lower jaw . 15 Vertex . 15 Skin over patella 16 Skin over sacrum 18 18 18 acromion . Dorsum of foot Skin over sternum 20 Skin beneath occiput . 24 Skin over sjiine, in back 30 Middle of the arm 30 thigh 303 listance between the legs of the compasses hough it was really less, when they were placed upon more sensitive parts. It has been supposed, that some of the recorded instances of great resistance to heat have been caused by unusual thiclvness, and com- pactness of cuticle, together with a certain degree of insensibility of the skin. The latter may be an important element in the explanation; but some of the feats, executed by persons of the character alluded to, could hardly have been influenced by the former, as the resistance seemed almost equally great in the delicately organized mucous mem- branes. A Madame Girandelli, — who was exhibited in Great Britain many years ago, — was in the habit of drawing a box with a dozen ' Art. Tastsinn und das Gemeingefiihl, in Wagner's HandwiJrterbuch der Physi- ologie, 22ste Lieferung, S. 539. Braunschweig, 1849. His earlier experiments are detailed and confirmed by Dr. Allen Thomson, in Edinb. Med. and Surg. Journal, for July, 1833. ^ Lehrbuch der Physiologic des Menschen, ii. 565. Braunschweig, 1844 ; and Grundriss der Physiologie, S. 331. Braunschweig, 1846. ' A full table of the results of the observations of Professors "Weber and Valentin is given by Dr. Carpenter, in Art. Touch, Cyclop, of Anat. and Physiol., iv. 1169, Lon- don, 1852. TOUCH — APPRECIATION OF TEMPERATURE. 689 lighted candles along her arm, putting her naked foot upon melted lead, and of dropping melted sealing-wax upon her tongue, and im- pressing it with a seal, without appearing to experience uneasiness; and several years ago (1832), a man of the name of Chabert excited in this country the surprise which followed his exhibitions in London a year or two previously, and gave him the appellation of the " Fire King," In addition to the experiments performed by Madame Giran- delli, Chabert swallowed forty grains of phosphorus; washed his fin- gers in melted lead; and drank boiling Florence oil with perfect im- punity. For the phosphorus he professed to take an antidote, and doubtless did so. It is probable, also, that agents were used by him to deaden the painful impressions ordinarily produced by hot bodies applied to the surface. A solution of borax or alum spread upon the skin is said to exert a powerful effect of the kind; but, in addition to the use of such agents, there must be a degree of insensibility of the corpus papillare; otherwise it is difficult to understand why those hot substances did not painfully inflame the surface. We see, daily, striking differences in individuals in the degree of sensibility of the mucous membrane of the mouth and gullet, and are frequently sur- prised at the facility with which certain persons swallow fluids of a temperature that would excite the most painful sensations in others. In this, habit has unquestionably much to do. The surprising feats of dipping the hand into melted lead, laying hold of a red-hot iron, &c., were explained by M. Boutigny at the meeting of the British Association at Ipswich in 1851 as follows. In all such cases, a thin film of aqueous fluid in the spherical state inter- venes between the skin and the heated surflice; and a hand, which is naturally damp, or which has been slightly moistened, may, it is affirmed, be safely passed into the stream of melted iron as it flows from the surface, as was shown by M. Boutigny at the meeting.' In the mucous membranes, tact is effected in the same way as in the skin. The layers, of which it is constituted, participate in like man- ner; but the sense is more exercised at the extremities of the mem- brane than internally. The food, received into the mouth, is felt there ; but after it has passed into the gullet it excites hardly any tac- tile impression; and it is not until it has reached the lower part of the membrane, in the shape of excrement, that its presence is again indi- cated by this sense. Pathologically, we have some striking instances of this difference in different parts of the mucous membrane. If an irritation exists within the intestinal canal, the only indication we may have of it is itching of the nose, or at one extremity of the membrane. In like maimer, a calculus in the bladder is indicated by itching of the glans penis ; and a similar exemplification is offered during the passage of a gall-stone through the ductus communis choledochus. On its first entrance, the pain experienced is of the most violent character; this, after a time subsides, — as soon, indeed, as the calculus has got fairly into the canal, ' Eeport on the 21st Meeting of the British Association for tlie Advancement of Science, Lend,, 1852; and Carpenter, rrincijiles of Human Physiology, Amor, edit., p. 411 (note), Philad., 1855. VOL, I. — 4-1: 690 SENSIBILITY. One of tlie great purposes of the seuse of tact is to enable us to judge of the temperature of bodies. This office it executes alone. No other sense participates in it. It requires no previous exercise; is felt equally by the infant and the adult, and requires only the proper de- velopment of its organs. The relative temperature of bodies is accu- rately designated by the instrument called the therrriometer ; but very inaccurately by our own sensations; and the reason of this inaccuracy is sufficiently intelligible. In both cases, the effect is produced by the disengagement of a subtile fluid, called caloric or the matter of heat, which pervades all bodies, and is contained in them to a greater or less extent. This caloric is constantly passing and repassing between bodies, either by radiation or by conduction, until there is an equili- brium of caloric and all have the same temperature as indicated by the thermometer. Hence, objects in the same apartment will exhibit, cceteris jjarihus, a like temperature by this test. From this law, how- ever, the animal body must be excepted. The power which it pos- sesses of generating its own heat, and of counteracting the external influences of temperature, preserves it constantly at the same point. Although, however, all objects may exhibit the same temperature, in the same apartment, when the thermometer is applied to them; the sensations communicated by them may be very different. Hence the difficulty, which the uninstructed have in believing, that they are actually of identical temperature; — that a hearth-stone, for instance, is of the same degree of heat as the carpet in the same chamber. The cause of the different sensations experienced in the two cases is, that the hearthstone is a much better conductor of the matter of heat than the carpet. The consequence is, that caloric is more rapidly ab- stracted by it from the part of the body which comes in contact with it, and the stone appears to be the colder of the two. For the same reason, when these two substances are raised in temperature above that of the human body, the hearth-stone will appear the hotter of the two; because, it conducts caloric and communicates it more rapidly to the body than the carpet. When the temperature of the surrounding air is higher than 98°, we receive caloric from the atmosphere, and experience the sensation of heat. The human body is capable of being penetrated by the caloric of substances exterior to it, precisely like those substances themselves; but, within certain limits, it possesses the faculty of consuming the heat, and retaining the same temperature. When the temperature of the atmosphere is only as high as our own — an elevation which it not unfrequently attains in many parts of the United States — we still ex- perience the sensation of unusual warmth ; yet no caloric is commu- nicated to us. The cause of this feeling is, that we are accustomed to live in a medium of a less elevated temperature, and consequently to give off' caloric habitually to the atmosphere. Lastly, in an atmosphere of a temperature much lower than that of the body, heat is incessantly abstracted from us; and, if rapidly, we have the sensation of cold. From registers, kept by the illustrious founder of the University of Virginia, Mr. Jefterson, at his residence at Monticello,^ lat. 87° bS\ long. 7b° 40', it appears that the mean ' Virginia Literary Museum, p. 36, Charlottesville, 1830. TOUCH — APPRECIATION OF TEMPERATURE. 691 temperature of that part of Virginia, is about 55i° or 56° ; and that the thermometer varies from 5J° in the coldest month, to 94° in the warmest. Now, the temperature of the human body being 98°, it follows, that heat must be incessantly parting from us, and that we ought, therefore, to experience constantly a sensation of cold ; and this we should unquestionably do, were we not protected by clothing, and aided by artificial temperature during the colder seasons. Yet, accustomed as the body is to give oft' caloric, there is a temperature, in which, clothed as we are, we do not feel cold, although we may be disengaging heat to some extent. This temperature ma}^ perhaps be fixed somewhere between 70° and 80° in the climate of the middle portions of the United States. So much, however, are our sensations in this respect dependent upon the temperature which has previouslv existed, that the comfortable point varies at dift'erent seasons. If the thermometer, for instance, has ranged as high as 98°, and has main- tained this elevation for a few days, a depression of 15° or 20° will be accompanied by feelings of discomfort;, whilst a sudden elevation from 30° to 75° may occasion an oppressive feeling of heat. In northern Siberia, M, von Wrangel' found, that only a few degrees of frost was currently denominated " warm weather;" and that after having been accustomed to the winter temperature of that climate, it seemed to him, that 10° of cold, 22° below the freezing point of Fahrenheit, was a mild temperature. During the voyages made by Captain Parry and others to discover a northwest passage, it was found, that after having lived for some days in a temperature of 15° or 20° below 0, it felt comfortable when the thermometer rose to zero. These are the great sources of the deceptive nature of our sensations as to warmth and cold which enable us to judge merely of the com- parative conditions of the present and the past; and hence it is, that a deep cellar appears warm in winter and cold in summer. At a certain distance below the surface, the temperature of the earth indicates the medium heat of the climate; 3'et, although this may be stationary, our sensations on descending to it in winter and summer would be by no means the same. If two men were to meet on the middle of the South American Andes, — the one having descended, and the other ascended, — their sensations would be very different. The one, who had descended, coming from a colder to a warmer atmos})here, would experience warmth; whilst the other, who had ascended, would feel correspondently cool. An experiment, often performed in the chemi- cal lecture-room, exhibits the same physiological fact. If, after having held one hand in iced, and the other in warm water, we plunge both into water of a medium heat, it will seem warm to the one hand, and cold to the other. But our sensations are not guided solely by bodies surrounding us. They are often greatly dependent, especially in disease, on the state of the animal economy itself. If the power, which the system possesses, of forming heat, be morbidly depressed, — or if, in consequence of old age, or of previous sickness, calorification does not go on regularlv ' Reise des kaiserlicli Russischen Flotten Lieutenants F. v. Wrangel Kings derNord- kiiste vou Siberien, u. s. w., Berlin, Ib^D, translated in Harper's Family Library. 692 SENSIBILITY. and energetically, a temperature of the air, wliicli to the vigorous is agreeable, may produce an unpleasant impression of cold. Under opposite circumstances, a feeling of heat exists. In regard to the mode in which the temperature of bodies is appre- ciated, there are peculiarities, which would favour the idea of the sense of heat being distinct from that of tact or touch. Professor Weber, for example, found that the left hand is more sensitive than the right, although the sense of touch is more acute in the latter; and that if the two hands, at the time of like temperature, be plunged into separate basins of water, the one in which the left hand is, will appear to be the warmer, even although its temperature may be somewhat lower than that of the other. It would seem, too, from Weber's experiments, that in regard to sensations of heat and cold, a weaker impression made upon a large surface appears more powerful than a stronger made upon a small surface; and, accordingly, to judge of nice shades of difference in the temperature of a fluid, the whole hand will enable a variation to be detected, that would be inappreciable to the finger. A dilference of one-third of a degree, it is affirmed, may be easily de- tected, when the same hand is placed successively in two vessels of water, or any other fluid.^ These and other phenomena of an analogous kind have led to the suggestion, thift every nerve of sensation is composed of several nerves, each of which may have its special function ; and that the nerves of touch comprise some which appreciate temperature; others, which per- ceive the resistance of bodies, and others which effect touch properly so called. In pi'oof of this a recent writer urges that either of these faculties may be lost, without the other being so. Thus, when the arm has been '"asleep," and sensibility is returning to it, the hand first per- ceives temperature, then the resistance of bodies, and it is not until some time afterwards that the faculty of touch, properly so called, is exercised. In the lower extremities the contrary takes place; the sense of touch first returns; then a sensation of pricking is experienced, fol- lowed by the perception of temperature, and the power of appreciating resistance returns last. It may be added, that many cases are recorded, in which the sense of temperature has been lost, whilst the ordinary sense of tact remained; and, as remarked by Dr. Carpenter,'^ it is an additional evidence in favour of the distinctness of nervous fibres to convey the impressions of temperature, that these are frequently affected, — a person being sensible of heat or of chilliness in some part of the body, — without any real alteration of its temperature, whilst there is no corresponding affection of the tactile sensations. By tact we are lilvcwise capable of forming a judgment of many of the qualities of bodies,— such as their size, consistence, weight, distance, and motion. This faculty, however, is not possessed exclusively by the sense in question. We can judge of the size of bodies by the sight; of distance, to a certain extent, by the ear, &c. To appreciate these characters, it is necessary, that the sense should be used actively ; that we should call into exercise the admirable instrument with which ' E. H. Weber, art. Tastsinn und das Cremeiii,G;efuhl, in Wagner's Handworterbucli der Physiologie, 22te Lieferung, S. 549, Braunschweig, 1849. ^ Princix'les of Physiology, 2d Amer. edit., j). 229, Philad., 1845. TOUCH — THE HAND THE GREAT ORGAN". 69S we are provided for that purpose; and in many of them we are greatly instructed by the muscular sense. In treating of the external senses generally, it was remarked, that we are capable of judging, by their aid, of impressions made on us by portions of our own body. By the sense of touch we can derive infor- mation regarding its temperature, shape, consistence, &c. An opinion has, indeed, been advanced, that this sense is best adapted for proving our own existence, as every time that two portions of the body come in contact, two impressions are conveyed to the brain, whilst if we touch an extraneous body, there is but one. The tact of mucous membranes is extremely delicate. The great sensibility of the lips, tongue, tunica conjunctiva, Schneiderian mem- brane, lining membrane of the trachea and urethra, is familiar to all. Excessive pain is produced in them by the contact of extraneous bodies; yet, in many cases, they signally exemplify the effect of habit in blunt- ing sensation. The first introduction of a bougie into the urethra generally produces intense irritation ; but after a few repetitions the sensation may become scarcely disagreeable. To appreciate accurately the shape and size of objects, it is neces- sary, that they should be embraced by a part Fig- 234. of the body, which can examine their surfaces, and be applied to them in every direction. In man, the organ well fitted for this purpose is the hand. This is situate at the free extremity of a long and flexible member, which admits of its being moved in every direction, and renders it not only well adapt- ed for the organ of touch, but for that of prehension. Man alone possesses a true hand; for although other animals have organs of pre- hension very similar to his, they are much less complete. Aristotle and Galen termed it the iyistruvynt of instrumeiits^ and its construction was considered worthy of forming the subject of one of the ^'■Bridge- water Treatises''' "On the Power, Wisdom, and Goodness of God, as manifested in the Creation," — a task assigned to Sir Charles Bell. The chief superiority of the hand consists in the size and strength of the thumb, which stands out from the fingers, and can be brought in opposition to them, so as to enable us to grasp bodies, and to execute various mechanical processes under the guidance of the intellect. So important was the thumb esteemed by Albiuus,^ that he called it a lesser hand to assist the larger — " manus parva majori adjutrixr Hand of Man, compared with anterior extremity of Oranj ' De Sceleto, p. 465. 694 SENSIBILITY. In addition to the advantages referred to, the hand is furnished with a highly sensible integument. The pa- Fis. 235. pillae are largely developed, especially at the extremities of the fingers, where they are ranged in concentric circles, and rest upon a spongy tissue, by many considered to be erectile, and serving as a cushion, and are well supplied with capillary vessels. (See Figs. 217, and 235.) At the posterior ex- tremity of the fingers, are the nails, which support the pulps of the fingers behind; and Capillary Neiw,,rk at margin Tender the coutact with external bodies of lips. more immediate. This happy organization of the soft parts of the hand alone concerns the sense of touch directly. The other advantages, which it possesses, relate to the power of applying it under the guidance of volition. Of the mode in which touch is effected it is not necessary to treat. Being nothing more than tact, exerted by an appropriate instrument, the physiology of the two must be identical. Metaphysicians have differed widely regarding the services thatought to be attributed to the touch. Some have greatly exaggerated them, considering it the sense par excellence^ the first of the senses. It is an ancient notion to ascribe the superiority of man over animals and his pre-eminence in the universe — his intelligence, in short — to the hand. Anaxagoras asserted, and Ilelvetius' revived the idea, "that man is the wisest of animals because he possesses hands." The notion has been embraced and expanded by Condillac,^ Buffon,^ and many modern phy- siologists and metaphysicians. Biiffon assigned so much importance to the touch, that he believed the cause why one person has more intel- lect than another is his having made a more prompt and repeated use of his hands from early infancy. Hence, he recommended, that infants should use them freely from the moment of birth. Other metaphysi- cians have considered the hand the source of mechanical capabilities ; but the same answer applies to all these views. It can only be re- garded as an instrument by which information of particular kinds is conveyed to the brain ; and by which other functions are executed, under the direction of the will. The idiot often has the sense more delicate than the man of genius or than the best mechanician, whilst the most ingenious artists have by no means the most delicate touch. We have, indeed, some striking cases to show, that the hand is not en- titled to this extravagant commendation. Not many years ago, a Miss Biffin was exhibited in London, who was totally devoid of upper and lower extremities; yet she was unusually intelligent and ingenious. It was surprising to observe the facility with which she hem-stitched; turning the needle with the greatest rapidity in her mouth, and insert- ing it by means of the teeth. She painted miniatures faithfulh^, and beautifully;— holding the pencil between her head and neck. All her ' De I'Homme, &c., torn. i. ^ Traite des Sensations, P. i. * Histoire Naturelle, torn. vi. TOUCH — THE GEOMETRICAL SENSE. 695 motions were, in fact, confined to tlie tongue and lips, and to the muscles of the neclv. M. Magendie^ alludes to a similar case. lie says, that there was, in Paris, at the time he wrote, a young artist, who had no signs of arm, forearm, or hand, and whose feet had one toe less than usual — the second ; yet his intelligence was in no respect inferior to that of boys of his age; and he even gave indications of distinguished ability. He sketched and painted with his feet. Not many years ago, a Miss Honeywell, born without arms, travelled about this country. She had acquired so much dexterity in the use of the scissors, as to be able, by holding them in her mouth, to cut likenesses, watch-papers, flowers, &c. She also wrote, drew, and executed all kinds of needle- work with the utmost ease and despatch. How fatal are such authentic examples to the views of Helvetius and others! But, it has been said, that touch is the least subject to error of all the senses : it is the regulating — the geometrical sense. In part only is this accurate. It certainly possesses the advantage of allowing the organ of sense to be brought into immediate contact with the body that excites the impression; whilst, in the case of olfaction, the organ receives the impression of an emanation from the body ; and, in vision and audition, only the vibration of an intervening medium. Yet some of the errors into which touch falls are as grievous as those that happen to the other senses. How inaccurate is its appreciation of the temperature of bodies ! We have attempted to show, that it affords merely relative knowledge, — the same substance appearing hot or cold to us, according to the temperature of the substance previously touched. Nay, infallibility so little exists, that we have the same sen- sation communicated by a body that rapidly abstracts caloric from us, as by one that rapidly supplies it. By touching frozen mercury, which requires a temperature of — 40° of Fahrenheit to be congealed, we experience the sensation of a burn. Again, if we cross the fingers and touch a rounded body — a marble, for instance — with two of the pulps at the same time: instead of experiencing the sensation of one body, we feel as if there were two, — an illusion produced by the lateral portions of fingers being brought in apposition, which are naturally in a different situation, and at a distance from each other; and, as these two parts habitually receive distinct impressions when separated, they continue to do so when applied to opposite sides of the rounded body. It has been asserted, that the touch is the great corrector of the errors into which the other senses fall. But let us inquire, whether, in this respect, it possesses any decided superiority over them. For this purpose, the distinction of the sensory functions into immediate and mediate has been adopted. Each sense has its immediate func- tion, which it possesses exclusively ; and for which no other can be substituted. The touch instructs us regarding resistance; the taste appreciates savours; the smell, odours; audition, sound; and vision, colours. These are the immediate functions of the senses, each of which can be accomplished by its own organs, but by no other. As concerns the immediate functions of the senses, therefore, the touch ' Precis Elementaire, 2de edit., i. 154, Paris, 1825. 696 SENSIBILITY. can afford no correction. Its predominance, as regards the mediate functions of the senses, is likewise exaggerated. The mediate functions are those that furnish impressions to the mind; and by aid of which it acquires its notions of bodies. The essential difference between these two sets of functions is, that the mediate can be effected by several senses at once, and may be regarded as belonging to the cere- brum. Vision, olfaction, and audition participate with touch in enabling us to judge of distances; the sight instructs us regarding shape, &c. It has been affirmed by metaphysicians, that touch is necessary to several of the senses to give them their full power, and that we could form no notion of the size, shape, and distance of bodies, unless instructed by this sense. The remarks already made have proved the inaccuracy of this opinion. The farther examination of it will be resumed under Vision. The senses are, in truth, of mutual assistance. If the touch falls into error, as in the case of inaccurate appreciation of temperature, the sight, aided by appropriate instru- ments, dispels it. If the crossed fingers convey to the brain the sen- sation of two rounded bodies, when one only exists, the sight apprises us of the error ; and if the sight and touch united impress us with a belief in the identity of two liquids, the smell or the taste will often detect the erroneous inference. But, it has been said by some, touch is the only sense that gives us any notion of thf existence of bodies. M. Destutt-Tracy' has satis- factorily opposed this, by showing that such notion is a work of the mind, in acquiring which the touch does not assist more immediately than any other sense. "The tactile sensations," he observes, "have not of themselves an}'- prerogative essential to their nature, which dis- tinguishes them from others. If a body affects the nerves beneath the skin of my hand, or if it produces certain vibrations in those distri- buted on the membranes of my palate, nose, eye, or ear, it is a pure impression which I receive; a simple affection which I experience; and there seems to be no reason for believing that one is more in- stinctive than another ; that one is more adapted than another for enabling me to judge that it proceeds from a body exterior to me. Why should the simple sensation of a puncture, burn, titillation, or jjressure, give me more knowledge of the cause, than that of a colour, sound, or internal pain? There is no reason for believing it." There are, indeed, numerous classes of bodies, regarding whose existence the touch affords us no information, but which are detected by the other senses. On the whole, then, we must conclude, that the senses mutually aid each other in the execution of certain of their functions ; that each has its province, which cannot be invaded by others ; and that too much preponderance has been ascribed to the touch by metaphysicians and physiologists. Ministering, however, as it does, so largely to the mind, it has been properly ranked with vision and audition as an in- tellectual sense.^ By education, the sense of touch is capable of acquiring extraordi- ' l-ltniens d'lrltologie, lere Partie, p. 114, 2de edit. Paris, 1S04. ^ Gall, Sur les Foiic-tious du Cerveau, i. 99, I'arid, 1S25. TOUCH IMPROVED BY EDUCATION". 697 narj acuteness. To this circumstance must be ascribed the surprising feats we occasionally meet with in the blind. For all their reading and writing they are, indeed, indebted to this sense, and modelling in clay, wax, &c., and sculpture, carving in wood, and even engraving have been accomplished by them.' Dr. Saunderson — who lost his eyesight in the second year of his life, and was Professor of Mathematics at Cambridge, England — could discern false from genuine medals; and had a most extensive acquaint- ance with numismatics.^ As an instance of the correct notions, which may be conveyed to the mind of the forms and surfaces of a great variety of objects, and of the sufficiency of these notions for accurate comparison. Dr. Carpenter' mentions the case of a blind friend, who has acquired a very complete knowledge of conchology, both recent and fossil; and who is not only able to recognize every one of the numerous specimens in his own cabinet, but to mention the nearest alliances of a shell previously unknown to him, when he has tho- roughly examined it by the touch. Baczko, referred to by Eudolphi,"* who describes his own case, could discriminate between samples of woollen cloth of equal quality but of different colours. The black appeared to him among the roughest and hardest: to this succeeded dark blue and dark brown, which he could not, however, distinguish from each other. I'he colours of cotton and silk stuffs he was unable to discriminate; and he properly enough doubts the case of a Count Lynar, blind, who, it was said, was capable of judging of the colour of a horse by the feel. The only means the blind can possess of discri- minating colours must be through the physical differences of surface, which render it capable of reflecting one ray or combination of rays, whilst it absorbs the rest; and if these differences were insufficient to enable Baczko to detect the differences between cotton and silk fabrics, it is not probable, that the sleek surface of the horse would admit of such discrimination.* Education or sustained and discriminating!: attention gives the same facility in the appreciation of temperature. It is affirmed, that Dr. Saunderson, when some of his pupils were en- gaged in taking the altitude of the sun, could tell by the slight modi- fication in the temperature of the air, Avhen very light clouds were passing over the sun's disk. The deaf have no perce|ition of the vibrations of sonorous bodies ; yet by the sense of touch they can judge of tangible percussions from bodies that are thrown into powerful vibration ; and Dr. Kitto'' — him- self deaf — has given a vivid representation of the impression made upon him by different forms of percussive vibrations. ' Rev. Wm. Taylor, F. R. S., in Notices of tlie Meetings of the Roval Institution, 1853. * Abercrombie's Inquiries concerning the Intellectual Powers ; Anier. edit., p. 55, New York, 1832. ^ Principles of Human Physiology, American edit., p. 657, Philad., 1854; and art. Touch, Cyclop, of Anat. and Physiol., iv. 1180, Lond., 1852. ■• Gtrundriss der Physiologie, 2er Band, S. 85, Berlin, 1823. 5 For an interesting account of the blind and deaf James Mitchell, Laura Bridgman, and others, referred to hareafter — and of blind travellers, blind i)0(:'ts, blind musicians, blind divines and blind philosophers, see The Lost Senses, by John Kitto, D. D., F. S. A., Series II., Blindness, Lond., 1845. ^ Op. cit., Series I., Deafness, Lond., 1853. 698 SEXSIBILITY. lu animals the organ of touch varies. The monkey's resembles that of man. In other quadrupeds, it is seated in the lips, snout, or proboscis. In molluscous animals, the tentacula; and in insects, the antenna or feelers, are organs of touch, possessing, in some, very great sensibility. Bats appear to have this to an unusual degree. Spallan- zani observed them, even after their eyes had been destroyed and the ears and nostrils closed, flying through intricate passages, without striking the walls, and dexterously avoiding cords and lines placed in the way. The membrane of the wings is, in the opinion of Cuvier and many others,^ the organ that receives an impression produced by a change in the resistance of the air, M, Jurine concludes, that nei- ther hearing nor smell is the channel through which they obtain per- ception of the presence and situation of surrounding bodies. He ascribes this extraordinary faculty to the great sensibility of the skin of the upper jaw, mouth, and external ear, which are furnished with large nerves; whilst Sir Anthony Carlisle attributes it to the extreme delicacy of hearing possessed by the animal f a view which is con- firmed by experiments instituted by the author's friend. Professor J. K. Mitchell. Certain experiments by Mr. Broughton' sanction the idea that this may be, in part, dependent upon their whiskers. These, which are found on the upper lip of feline and other animals, are plen- tifully supplied with nerves, which seem to proceed from the second branch of the fifth pair, and are lost in the substance of the hairs. In an experiment, made by Mr. Broughton on a kitten, he found that whilst the whiskers were entire, it was capable of threading its way, blindfold, from a labyrinth in which it was designedly placed; but it was totally unable to do so when the whiskers were cut off. It struck its head repeatedly against the sides; ran against all the corners; and tumbled over steps placed in the way, instead of avoiding them, as it did prior to the removal of the whiskers. From facts like these Mr. Broughton drew the conclusion, that cer- tain animals are supplied with whiskers for the purpose of enabling them to steer clear of opposing bodies in the dark. B. SENSE OF TASTE OR GUSTATIOX. The sense of taste teaches us the quality of bodies called sapidity. It is more nearly allied to touch in its mechanism than any other of the senses, as it requires the immediate contact of the body with the organ, and the organ is, at the same time, capable of receiving tactile impressions distinct from those of taste. Of this we have a striking example, if we touch various portions of the tongue with the point of a needle. "We find two distinct perceptions occasioned. In some parts the sensation of a pointed body without savour; and in others, a metallic taste is experienced. Pathological cases, too, exhibit, that the sense of taste may be lost, whilst general sensibility remains, — and conversely. The organ of gustation is not, therefore, restricted to that sense, but participates in touch. Yet so distinct are those functions, that touch can, in no wise, supply the place of its fellow ' Carpenter, Human Physiology, p. 253, Lond., 1842. ^ See Roget's Animal and Vegetable Physiology, ii. 399, Amer. edit., Pliilad., 1836. ' Loudon Medical and Physical Journal, for 1823. ORGANS OF TASTE. 699 sense, in detecting the sapidity of bodies, instruction afforded by gustation. This last is the immediate 1. ANATOMY OF THE ORGANS OF TASTE. The chief organ of taste is membrane covering the upper The lips, inner surface of the cheeks, palate, and fauces, par- ticipate in the function, espe- cially when particular savours are concerned. M. Magendie^ includes the oesophagus and stomach; but we know not on what grounds : his subsequent remarks, indeed, controvert the idea. The lingual branch of the fifth pair is, according to him, incontestably the nerve of taste; and, as this nerve is dis- tributed to the mouth, we can understand, why gustation should be effected there; but not how it can be accomplished in the oesophagus and stomach. The tongue consists almost en- tirely of muscles, which give it great mobility, and enable it to fulfil the various functions as- signed to it ; for it is not only an organ of taste, but of masti- cation, deglutition, and articu- lation. The muscles being un- der the influence of volition, enable the sense to be executed passively or actively. As regards gustation, the mu- cous membrane is the portion immediately concerned. This is formed, like the mucous mem- branes in general, of the differ- ent layers already described. The corpus papillare requires farther notice. If the surflxce of the tongue be examined, it will be found to consist of my- riads of fine papillae or villi, that give the organ a velvety appearance. These papillas are, doubtless, like those of the skin, the tongue, or rather the mucous surface, and sides of that organ. Fig. 236. Front View of the Upper Surface of the Tongue, as well as of the Palatine Arch. 1, 1. Posterior lateral half arches, with the palato- pharyngei muscles, and tonsils. 2. Epiglottic cartilage, seen from hefore. 3, 3. Ligament and mucous mem- brane, extending from the root of the tongue to the base of the epiglottic cartilage. 4. One of the pouchp.s on the .side of the posterior frjenum, in which food sometimes lodges. 5. Foramen cjecum. 6. Papillje capitata; seu maxima;. 7. The white point at the end of the line, and all like it, are the papilla fungiformes. 8. Side of the tongue, and rugre transversa; of Albinus. 9. Papillse filiformes. 10. Point of the tongue. Fig. 237. View of a Papilla of the smallest class, magnified 25 diameters. The loops o blood-vessels are hero shown, each, loop containing usually only one vessel. Precis de Physiol., i. 139. 700 SENSIBILITY. Fig. 23S. formed of the final ra- mifications of nerves, and of the radicles of exhalant and absorbent vessels, united by means of a spongy erectile tis- sue. Great confusion exists among anato- mists in their descri])- tions of the papillse of the tongue. Those cer- Vertical Section of one of the (iustatory Papilla; of the Inrgest tainly Concerned in the fY^' showing its corneal form, its sides, and the fissure ggj^gg ^f ^^g^^ ^iOW- between the different Papillae. , . , ■; , The length of soTie of the divided blood-vessels, a transverse CVCr, section of others, and the vessels which rise up from the surface t\VO like loops or meshes, are also shown. Fig. 239. msssmM be included in divisions: — 1st, the conical ov pyramid- al, — the finest sort by some called filifonn; and 2dly, lh.Q fvjvj if arm. The former are broader at the base than at the top; and are seen over the Avhole surface of the tongue, from the ti]) to the root. The latter, which are larger at the top than the base, and resemble the mushroom, — whence their name, — are spread about, here and there, on the surface of the orgjin. These must be distin- guished from a third set, the painllcB capHaloR or circumvallatce, which are situate near the base of the ton one in The Hypoglo.=sal ; Lingual branch of fifth pair; fJlosso-Pha- rvntceal and deep-seated Nerve.* of the Neck. 1. The hypoglossal nerve. 2. Branches communicating with the lingual branch. 3. A branch to the origin of the hyoid muscles. 4. The desceudens noni nerve, o. The loop formed with the branch from the cervical nerves. 6. Muscular branches to the depressor tWO V shapcd llllCS at muscles of the larynx. 7. A lilament from the second cervical j.i v, ^1 nerve, and 8. a filament from the third cervical, uniting to form the tllC OaSC OI tllC Orgail. communicating branch with the loop from the descendens noni. fpi-io-,,- o ro <-> i vi^i n 1 o r .lo 9. The auricular nerve. 10. The inferior dental nerve. 11. Its -*- ^^J "■'^^ CirCUidT Cie- mylo-hyoidean branch. 12. The lingual branch. 1.3. The chorda- tympani passing to the lingual branch. 14. The chorda-tympani learing the lingual branch to join the sub-maxillary ganglion. 1.5. The sub-raaxillary ganglion. 16. Filaments of communication with the lingual nerve. 17. The glosso-pharyngeal nerve. 18. The pneumogastric or par vagum nerve. 19. The three upper cer- vical nerves. 20. The four inferior cervical nerves. 21. The first dorsal nerve. 22, 23. The brachial plexus. 24, 2.5. The phrenic nerve. 26. The carotid artery. 27. The internal jugular vein. , . - ,, i ■ , at the outside oi which, again, is a slightly elevated ring, the central elevation and the ring being formed of close set simple papillse. The epithelium of the tongue is of the tesselated variety, like that of the epidermis. Over the fungiform pajDilte, it forms a thinner layer than elsewhere; so that vations from g'^th to ^'.,th of an inch wide, each with a central de- pression, and surround- ed by a circular fissure, TASTE — SAVOURS. 701 they stand out more prominently tlian the rest. That which covers the conical papillae, according to Messrs. Todd and Bowman,^ has a singular arrangement; being extremely dense and thick, and project- ing from their sides and tops in the form of long, stiff", hair-like pro- cesses ; many of which bear a strong resemblance in structure to hairs ; and some actually contain hair tubes. All the nerves that pass to the parts whose office it is to appreciate savours, must be considered to belong to the gustatory apparatus. These are the inferior maxillary ; several branches of the superior ; filaments from the spheno-palatine and naso-palatine ganglions; the lingual branch of the fifth pair, commonly called the gustatory nerve ; the whole of the ninth pair or hypoglossal ; and the glosso-pharyngeal. To which of these must be assigned the function of gustation, we shall inquire presently. Like tlie skia and mucous membranes in general, that of the tongue and mouth contains, in its substance, numerous mucous follicles, which secrete a fluid that lubricates the organ, and keeps it in a condition adapted for the accomplishment of its functions. The fluids, exhaled from the mucous membrane of the mouth, and the secretion of the different salivary glands, likewise aid in gustation; but they are more concerned in mastication and insalivation, and will require notice under another head.^ 2. SAVOURS. Before proceeding to explain the physiology of gustation, it may be necessary to inquire briefly into the nature of bodies as connected with their sapidity ; or, in other words, into savours, which are the cause of sapidity. The ancients were of opinion, that the cause of sapidity is a peculiar principle, which, according to its combination with the constituents of bodies, gives rise to various savours. This notion has been long aban- doned; and chiefly, because we observe no general or common charac- ters amongst sapid bodies, which ought to be were they pervaded by the same principle ; and because bodies may be deprived of their sapidity by subjecting them to appropriate processes. Many of our culinary processes have been instituted for this purpose : the infusion of tea is indebted for all its attractions to the power we possess of separating, by boiling water, the savoury from the insipid portions of the plant. A sapid principle must, therefore, be esteemed an integrant molecule of a body ; not the same in all cases, but as heterogeneous in its nature as the impressions made upon the organ of taste. When the notion was once entertained, that a sapid principle is an integrant molecule, sapidity was attempted to be explained by its shape. It was said, for instance, that if the savour be sweet, the mole- cule must be round; if sharp, angular; and so forth. Sugar was said to possess a spherical, — acids, a pointed, or angular molecule. We ' The Physiological Anat. and Physiology of Man, i. 439, Lond., 1848, or Amer. edit., p. 382. See, also, H. Hyde Salter, art. Tongue in Cycloj). of Anat. and Physiol., iv. 1120, Lond., 1852. ^ For an elaborate account of the Anatomy of the Organ of Gestation, see H. Hyde Salter, op. cit. 702 SENSIBILITY. know, however, that substances which resemble each other in the primitive shape of their crj^stal, impress the organ of taste differently; and that solution, which must destroy most — if not all — the influence from shape, induces no change in the savour. Others have referred sapidity to a kind of chemical action between the molecules, and the nervous fluid. This view has been suggested by the fact, that, as a general rule, sapid, like chemical bodies, act only when in a state of solution; that the same savours usually belong to bodies possessed of similar chemical properties, as is exemplified by the sulphates and nitrates; and that, in the action of acids on the tongue and mouth, we witness a state of whiteness and constriction, indicative of a first degree of combination. All these circumstances, however, admit of another explanation. There are unquestionably many substances, which do combine chemically, — not with a nervous fluid, of whose existence we know nothing, — but with the mucus of the mouth ; and the sapidity resulting from such combination is appre- ciated by the nerves of taste ; but there are many bodies, which are eminently sapid, and yet attbrd us instances of very feeble powers of chemical combination ; nay, in numerous cases, we have not the least evidence that such powers exist. Vegetable infusions or solutions are strong 6^xamples of the kind, — of which syrup maj^ be taken as the most familiar. The effect of solution is easily intelligible ; the par- ticles of the sapid body are in this way separated, and come succes- sively into contact with the gustatory organ ; but there is some reason to believe, that solution is not always requisite to give sapidity. Metals have generally a peculiar taste, which has been denominated metallic; and this, even if the surface be carefull}^ rubbed, so as to free it from oxide, which is more or less soluble. Birds, too, whose organs of taste are as dry as the corn they select from a mass of equally arid sub- stances, are probably able to appreciate savours. The taste produced b}^ touching the wires of a galvanic pile with the tongue has been offered as another instance of sapidity exhibited by dry bodies. This is, more probably, the eftect of chemical action on the fluids covering the mucous membrane of the tongue, which always follows such contact. Such chemical change must, however, be confined to these fluids; and, when once produced, the nerve of taste is impressed by the savour developed in the same manner as it is in cases of morbid alterations of the secretion of the mucous membrane. In both cases, a body possessing considerable and peculiar sapidity may fail to impress the nerves altogether, or may do so inaccurately. The notion of any chemical combination with the nervous fluid must of course be dis- carded, as there is not the slightest evidence in favour of the hypo- thesis; yet the epithet cAem/ca? was once applied to this sense on the strength of it; in opposition to the senses of touch, vision, and audition, which were called mechanical^ and supposed to be produced by vibra- tions of the nerves of those senses. The savours, met with in the three kingdoms of nature, are innu- merable. Each body has its own, by which it is distinguished : few instances occur in which any two can be said to be identical. This is the great source of difficulty, when we attempt to throw them into classes, as has been done by physiologists. Of these classifications, TASTE — CLASSIFICATION OF SAVOURS. 703 the one by Linnaeus' is best known: it will elucidate the unsatisfactory character of the whole. He divides sapid bodies into sicca^ aquosa, viscosa^ salsa, acida, styptica, dulcia, pinguia, amara, acria, and nanseosa. He gives also examples of mixed savours, acido-acria, acido-amara, amaro-acria, amnro-acerba, amaro- dulcia, duhi-st>/2)tica, didci-acida, dulci- ac7-ia, and acri-viscida ; and remarks, that the majority are antitheses to each other, two and two, — as dulcia and acria ; pinguia and styftica ; viscosa and salsa; and aquosa and sicca. Boerhaave^ again divides them into primary and compound; the former including the so^ir, siveet, hitter, saline, acrid, alkaline, vinous, sjjirituovs, aromatic, and acerb; — the latter resulting from the union of certain primary savours. There is no accordance amongst physiologists as to those that should be esteemed primary, and those secondary and compound; although the division appears to be admissible. The acerb, for example — which is considered primary by Boerhaave — is by others, with more propriety, classed among secondary or compound, and believed to consist of a combination of the acrid and acid. We understand, however, sufficiently well the character of the acid, acrid, bitter, acerb, sweet, &c. ; but when, in common language, we have to depict other savours, we are frequently compelled to take some well-known substance as a standard of comparison. According to M. Adelon,^ the only distinction we can make amono-st them is, — into the agreeable and disagreeable. Yet of the unsatisfactory nature of this classification he himself adduces numerous proofs. It can only, of course, be applicable to one animal species, often even to an individual only ; and often again only to such individual when in a given condition. Some animals feed upon substances, that are not only disagreeable but noxious to others. The most poisonous plants have an insect which devours them greedily and with impunity : the southern planter is well aware, that this is the case with his tobacco, unless the operation of worming be performed in due season. The old adage, that " one man's meat is another man's poison" is metaphori- cally accurate. Each individual has, by organization or association, dislikes to particular articles of food, or shades of difference in his appreciation of tastes, which may be esteemed peculiar ; and, in cer- 'tain cases, these peculiarities are signal and surprising. Of the strange differences, in this respect, that occur in the same individual under different circumstances, we have a forcible instance iu the pregnant female, who often ardently desires substances, that were previously perhaps repugnant to her, or, at all events, not relished. The sense, too, in certain diseases — especially of a sexual character, or such as are connected with the state of the sexual functions — becomes strangely depraved, so that substances, which can in no way be ranked as eatables, are greedily sought after. A young lady was under the care of the author, whose honne bouche was slate pencils. In other cases, we find chalk, brickdust, ashes, dirt, &c., preferred. Habit, too, has considerable etl'ect in our decisions regarding the agreeable. The Roman liquamen or garum, the most celebrated sauce of antiquity, was prepared from half putrid intestines of fiah ; and one of the varieties ' Amoenit. Academ., ii. 335. ^ Prnelect. Academ., torn. iv. ^ riiysiologie de rHomuie, aeconde edit., i. 301, Paris, Ib'l'd. 704: SENSIBILITY. of the Ort05 'Eo.'piov, laserpitivm, is supposed to have been assafcjotida.' Even at this day, certain orientals are fond of the flavour of this nau- seous substance. Putrid meat is the delioht of some nations; and a rotten egg, especially if accompanied with the chick, is esteemed by the Siamese. In civilized countries, we find game, in a putrescent state, eaten as a luxury : this, to those unaccustomed to it, requires a true education. The same may be said of the pickled olive, and of several cheeses — -froma Todd and Bowman, The Physiological Anatomy and Physiology of Man, p. 442, London, 1845. ^ Traite de Physiologic, ii. 297, Paris, 1850. \ IMMEDIATE FUNCTION OF TASTE. 709 oblongata, and separating tlieir roots from those of the pneumogastric, contractions always ensued in the stylo-pharyngeus muscle. From all the facts adduced by recent observers, Mr. Paget' thinks it probable, — ■ First. That the glosso-pharyngeal is chiefly the nerve of taste, and, in a less degree, a nerve of common sensation ; and Secondly. That, according to tlie experiments of MM. Mliller and Ilein, it is the motor nerve of the stylo-pharyngeus, and probably also of the palato-glossus. Lastly, M, de Blainville supposes, that the sense of taste is, perhaps, neither sufficiently special nor sufficiently limited in extent to have a separate nervous system ; and therefore that all the afferent nerves of the tongue are equally inservient to the sense, as the different nerves of the skin, which proceed from numerous pairs, are equally inservient to touch or tact.^ Such is the existing state of uncertainty regarding this interesting point of physiology ; the view of Panizza appears, however, to the author, to be most in accordance with analogy ; and in all respects most worthy of adoption. From the experiments and observations of Bellingeri, Montault, Diday, C. Bernard, and Verga,^ it would appear, that the filaments of the chorda tympani, which are united and confounded with those of the lingual branch of the fifth pair, are in an inexplicable manner con- nected with gustation. When the facial nerve has been paralyzed, or divided above tlie origin of the tympanic branch, the sense of taste has been impaired. The functions of the chorda tympani are by no means determined ; — some esteeming it as a sensory, others as a motor nerve; whilst others, again, believe it to possess both sensory and motor properties. The immediate function of taste, as has been remarked, is to give the sensation of savours. This function, like touch, is instinctive ; requires no education; cannot be supplied by any of the other senses, and is accomplished as soon as the tongue has acquired the necessary degree of development. To this it may be replied, that the very young infant is not readily affected by savours. In all cases, however, certain sapid bodies excite their usual impression ; and, in the course of a few months, when the organ becomes developed, the sense acquires a high, and often inconvenient, degree of acuteness. The mediate or auxiliary offices of gustation are few, and limited in extent. It does not afford much instruction to the mind. The chemist and mineralogist occasionally gain information through it; but it is never considered to merit the rank of an intellectual sense: on the con- trary, it is classed with olfaction as a corporeal sense. To appreciate a savour accurately, the sapid substance must remain for a time in the mouth ; when rapidly swallowed, the impression is feeble, and almost null. Of this fact we take advantage when com- pelled to swallow nauseous substances ; whilst we retain a savoury arti- cle long in the mouth, in order that we may extract its sweets. IIow different, too, is the consent of the auxiliary organs under these two ' Brit, and For. Mefl. Rev., April, 1845, p. fiSO. 2 Adelou, op. cit., i. 309. ^ Cited hy M. Longet, op. cit.,p. 305, Paris, 1850. 710 SEXSIRILITY. circumstances! Whilst a luscious body augments tlie secretion of the salivary glands, or causes the " mouth to water,'' as it has been called — projecting the' saliva, at times, to a distance of some feet from the mouth, and disposing every part to approach or mingle with it — a nauseous substance produces constriction of every secretory organ ; an elYect which extends even to the stomach itself, so that it often rejects the offending article, as soon as it reaches the cavity. We can thus understand how, ccettris jMribus, an article, that is pleasing to the palate, may be more digestible than one that excites disgust; and con- versely. Of the " consent of parts," exerted between the stomach and the organ of taste, we have a familiar illustration in the fact, — that whatever may be the gout, with which we conmience a meal on a favourite article of diet, we find that the relish is blunted as the stomach becomes filled; and hence the Komans were in the habit of leaving the table once or twice during a meal, and, after having unloaded the organ, of returning again to the charge — ^^vornwit ut edant, edunt ut vomantP If we place a sapid substance in the mouth, and then close the nos- trils, the taste is diminished, — a fact, which has given rise to the gene- rally prevalent and correct opinion, that an intimate relation exists between the smell and taste. They are, however, distinct. Most sapid substances have an odour or "flavour," which is not appreciated when we prevent the air from passing through the nasal fossae. This renders the impression on the gustatory nerves still less marked, but it exists. Gustation is likewise diminished by the new sensation produced in the nostrils by their closure; so that the same amount of attention is not directed to the sense of taste. A curious case of deprivation and modification of the senses of taste and smell has been related by Mr. Justice,^ of Philadelphia. It shows the intimate relation between them. Nine months previously, a person of his acquaintance was thrown from his carriage; and in the fall, his head came first in contact with the ground, and concussion of the brain was produced. The injury appeared to have been received behind, but above the ear. He was laid in bed in a state of total insensibility, and thus remained for nearly a month, about which time he revived, and, to his surprise, found that he had entirely lost both the sense of taste and the sense of smell. In this situation he remained at the time when Mr. Justice detailed the particulars of the case. It was equally indif- ferent to him what he took as food so far as regarded taste, — Cayenne pepper or sawdust as he expressed it being alike tasteless; — but as a compensation for this privation, he had a constant sensation of a most delightful character, which he could only compare to that of the most delicious cordial flowing through his mouth. This continues night and day, and is especially perceptible when the lips are apart, and he in- hales the air through his mouth ; — the only intermission to this plea- surable sensation being whilst he is taking his food. Yet although closely related the senses of taste and smell are dis- tinct. A case has been related by Dr. J. C. Hutchinson^ in which the olfactory nerve appeared to be entirely paral3'zed, whilst the branches ' Proceedings of the American Philosopliical Society, vi. 52, Oct. 6, 1854. ^ American Journal of the Medical Sciences, Jan., 1852. ACUTENESS OF TASTE. 711 of tlie fifth pair retained their integrity. Smell was lost; yet a pun- gent sensation was excited by irritating vapours, and when snuft' was taken sneezing was induced. The sense of taste, however, did not seem to be modified ; inasmuch as substances, which were possessed of neither smell nor pungency could be readily distinguished from each other, even when their tastes were not very different. Among animals we see great diversities in this sense. Whilst none possess the refined taste of man, there are many, which are capable, by taste or smell, of knowing plants that are nutritive from those that are noxious to them; and it is unusual for us to find that an animal has died from eating such as are unquestionably poisonous to it. Yet, as we have remarked, a substance, that is noxious to one, may be eaten with impunity by another; and, if we select animals, and place them in a field containing plants, all of which are ranked as poisons, and are poisonous to a majority of them, we find that not only has a selection been made by each animal of that which is innocuous to it, but that the substance has furnished nourishment to it, whilst it might have proved fatal to others. All this must be dependent upon peculiar, and inappreciable organization. The sense of taste is more under the influence of volition than any other. It is provided with a muscular apparatus, by which it can be closed or opened at pleasure; and, in addition, ordinarily requires the assistance of the upper extremity to convey the sapid substance to the mouth. The sense can, therefore, be exercised either |x/s5iY-eZ?/ or actively ; and, by cultivation, it is capable of being largely developed. The spirit taster to extensive commercial establishments exhibits the truth of this in a striking manner. In his vocation, he has not only to taste numerous samples, but to appreciate the age, strength, flavour, and other qualities of each ; and the practised individual is rarely wrong in his discrimination. With almost all, if not all, these "tasters," the custom is to take a small quantity of the liquor into the mouth ; throw it rajiidly around that cavity, and eject it. A portion, in this way, comes in contact with every part of the membrane ; and of course im- presses the glosso-pharyngeal as well as the lingual and other ramifica- tions of the fifth pair. The gourmet of the French — somewhat more elevated in the scale than our ordinary epicure — prides himself upon his discrimination of the nicest shades of difference and excellence in the materials set be- fore him. Many gourmtts profess to be able to pronounce, by sipping a few drops of wine, the country whence it comes, and its age ; and, according to Stelluti, can tell, by the taste, whether birds put upon the table are domesticated or wild, — male or female.^ Dr. Kitchener' asserts, that many epicures are cajiable of saying in what precise reach, or stretch of the Thames the salmon on the table has been caught; and Sir Astley Cooper was in the habit of relating the remarkable case of a professional friend, who could discriminate by the taste the beef fur- nished by a particular London butcher.^ This acuteness of sense is ' American Quarterly Review, ii. 427. 2 Cook's Oracle, 3d edit., p. 22f), Lond., 1821. ^ Life of Sir Astley Cooper, Bart., by Brausby Blake Cooper, Esq., F. R. S., ii. 137, Lond., 1843. 712 SENSIBILITY. by no nrcans desirable. Doomed to meet, in his progress tlirongli life, with such a preponderance of what demands obtuseness rather than acuteness of feeling, the epicure must be liable to continual annoyances and discomforts, which the less favoured can never expe- rience. In disease, gustation often becomes greatly depraved; and the various morbid tastes have been accounted for by depraved secretions in the mouth, acting as foreign sapid substances on the papillas. Cer- tain tastes, however, cannot be explained in this way, and must be regarded as nervous phenomena — subjective sensations. If the epithe- lium be covered with a fur, taste may be lost or impaired, and be instantaneously restored as soon as the coating is removed. M. Ma- gendie observed, that dogs, after the injection of milk into their veins, liclvcd their lips, and gave other evidences of tasting. When Dr. E. Hale, in an experiment referred to in another part of this work, in- jected castor oil into one of his veins, he distinctly tasted the oil a short time afterwards. Messrs. Todd and Bowman' suggest that such phenomena, if uniformly present, might be occasioned by the transu- dation of the fluid from the vessels to the nerves of the papillaa ; and this may be the true explanation, although it is not so easy to see that such transudation could readily occur in the case of castor oil. C. SENSE OF SMELL OR OLFACTION. The object of this sense is to appreciate the odorous properties of bodies. It differs from the last in the circumstance that the body does not come into immediate contact. It is only necessary that an odorous emanation from it shall impinge upon the organ of sense. Still, it does not essentially vary in its physiology from the sense of taste. 1. ANATOMY OF THE ORGAN OF SMELL. The organ of smell is a mucous membrane, which lines the nasal cavities, and is called Schneiderian or 'pituitary. It resembles that which covers the organ of taste, except that the nervous papilhe are more delicate, to correspond with the greater tenuity of the body that has to make the impression. The membrane lines the whole of the bony cavities called nasal fossce^ which are constantly open anteriorly and posteriorly, to permit the air that traverses them to proceed to the lungs. The anterior aperture is covered by a kind of pent-house or capital, for the purpose of collecting the odorous particles. This capital is called the nose. The essential part of the organ is the pitui- tary or olfactory membrane, — the other parts being superadded to perfect the sense. The bony portions of the nose are separated from each other by the vomer. This bony septum is prolonged, by means of cartilage, to the anterior extremity of the nose, so that the nasal fossae are divided into like parts, which have no communication with each other, but open together, posteriorly, into the top of the pharynx. Within each of the nares are two convoluted or turbinated hones — generally called ossa spongiosa sen turhinata; and, by the French, cornets. These are situate ' Tlie Physiological Anatomy and Physiology of Man, p. 448, Loud., 1845. ORGAN OF SMELL. 713 Fig. 240. one above tlie other ; the superior formed of a plate of the ethmoid bone — the inferior a distinct bone. They divide the general cavit}^ of each nostril into three passages or meatus. The inferior meatus is broad and long ; the least oblique, and least tortuous; the middle is narrow, al- most as long, but more extensive from above to below ; and the su2:je- rior is much shorter, more oblique, and still narrower. The narrowness of these passages in the living sub- ject is so great, that the slightest tumefaction of the membrane renders the passage of air through the fossae extremely difficult. This is the cause of the difficulty of breathing through the nose, that attends " a cold in the head." Into the two upper passages, cavities in certain bones open, which considerably enlarge the extent of the foss[B. These are called sinuses ; and are the maxillary, ixdat'me^ fron- tal^ sphenoidal, ethmoidal, — the last being sometimes termed etlimoidal cells. All the cavities are lined by the delicate pituitary membrane, or by a prolongation of it. In the nasal fossEe it augments the thickness of the turbinated bones. It resembles the mucous membranes in general in its composition ; and adheres firmly to the bones and cartilages, which it covers. Its aspect is vel- vety," owing to a multitude of minute papilUe; and it receives a great number of vessels and nerves. The sinuses are lined by a prolonga- tion apparently of the same membrane, diflering, however, in some respects from the other. The whole of the membrane is the seat of the secretion of nasal mucus, which, doubtless, performs a part in olfaction as important as the secretion from the mucous membrane of the mouth does in gustation. The same nerve is not distributed over the whole of this membrane. In some parts, the olfactory, ethmoidal, or first pair can be traced; in others, we see only filaments of the fifth pair. The first of these have not always been regarded as the nerves of smell. Anciently, they were presumed to be canals for the passage of pituita or phlegm, which was supposed to be secreted by the brain. At the present day, anato- mists are doubtful only as regards their origin ; some .deriving them from the anterior lobes of the brain; others from the corpora striata, which have, in consequence, been called thalami nervorum ethmo'ida- lium ; and others, again, with Willis and GalV and with probability, ' Eeclierches sur le Systeme Nervimx en general et sur celui du Cerveau eu parti- culier, par F. J. Gall et G. tspurzUeiui, Taris, 1809. Vertical Section of the Middle Part hf the Nasal Fossa?, giving a Posterior View of the Arrangement of the Ethmoidal Cells, &c. 1. Anterior fossa of the cranium. 2. The same covered by the dura mater. 3. Dura mater turned up. i. Crista galli of the ethmoid bone. 5. Its cribriform phite. 6. Its nasal himella. 7. Middle spongy bones. 8. Ethmoidal cells. 9. Os planum. 10. Inferior spongy bones. 11. Vomer. 12. Superior maxillary bone. 13. Its union with the ethmoid. 14. Anterior parietes of the antrum Higbmoriauum, covered by its membrane. 15. Its fibrous layer. 16. Its mu- cous membrane. 17. Palatine process of the su- perior maxillary bone. 18. Roof of the mouth, covered by the mucou.s membrane. 19. Section of this membrane. A bristle in the orifice of the antrum Highmorianum. 714 SENSIBILITY. Fig, 241. Outer wall of the Nasal Fossa, with the Three Spongy Bones and Meatus : the Nerves lieing shown as thej' would appear through the membrane if it were transparent. a. Olfactory process. &. Olfactory bulb (represented rather too short) resting on the cribriform plate. Below is seen the plexiform arrangement of the olfactory filaments on the upper and middle spungy bones, c. Fifth nerve within the cranium with its Gasserian ganglion, d. Its superior maxillary divi- sion, sending branches to Meckel's ganglion, and through tliat to the three spongy bones, where they anastomose with the olfactory filaments, and with ^f, branches of the nasal division of the ophthalmic nerve, o. Posterior palatine tvrigs from Meckel's ganglion, .supplying the soft and hard palate, t. Orifice of the Eustachian tube on the side of the pharynx, behind the lower spongy bone. — Two-thirds dia- meter. referring them, like every other nerve of sense, to the medulla oblon- gata. M. Beclard affirms, that in a hydrocephalic patient, where a part of the brain had been destroyed Fig. 242. by disease, he actually saw this origin.^ The nerve proceeds di- rectly forwards until it reaches the upper surface of the cribriform plate of the ethmoid bone, where it divides into a number of filaments, JF^^^^^M^iiH^ ^''^^^^^ ^^^^^ V^^^ through the foramina in .A^P/ *^ ^^^^ the plate, and attain the nasal fossae; where they are dispersed on the upper and middle part of the Schneiderian membrane; but can- not be traced on the lower. Most anatomists are of opinion, that here they constitute, with vessels of ex- halation and absorption, the pa- pilke ; whilst others, as Scarpa, not havino" been able to trace them thither, have been of opinion, that the filaments interlace to constitute a kind of proper membrane. Our means of observation cannot be considered sufficient to enable us to Nerves of the Septum of the Nose. a. Olfactory bulb resting on the cribriform plate, below which its branches may be tracod on the septum, abou< half way down. Behind, the naso-palatine nerve from Meckel's ganglion is seen descending to the naso-palatine canal. In front, the nasal twig of the ophthalmic nerve de- scends towards the tip of the nose, dividing into two principal branches, p. Roof of the mouth, e. Orifice of the Eustachian tube. — One-half dia- meter. Adelon, Physiologie de rHomine, edit, cit,, i, 330. ORGAN OF SMELL. 715 decide tliis question positively. The nerve has not been traced on the OS spongiosum inferius; on the inner surface of the middle spongy bone, or in any of the sinuses. Fig. 243. A portion of the Pituitary Membrane of the Na?fil Septum, magnified 9 times, showing the jN'umher, Sizes, and Arrangement of the Mucous Crypts. A portion of the Pituitary Membrane with its Arteries and Veins injected.— Magnified ]5 diameters. The natural size of this piece is seen at the bot- tom of the cut. 1, 1, 1. Orifices of three mucous crypts sur- rounded by veins and arteries. Fig. 245. The olfactory filaments, according to Messrs. Todd and Bowman,^ form a considerable part of the entii'e thickness of the Schueiderian membrane, and differ widely from the ordinary encephalic nerves in struc- ture. They contain no ivhite substance of Schwann ; are not divisible into elementary fibrilloa ; are nucleated and finely granular in texture, and invest- ed with a sheath of homogeneous membrane ; and are regarded by those gentlemen as direct continuations of the vesicular matter of the olfactory bulb or ganglion; and they "venture to hint," that the amalgamation of the elements of the peripheral part of the nervous apparatus in the larger branches, and probably in the most remote distribution, as well as the nucleated character indicative of an essential continuity of tissue with the vesicular, matter of the lobe, are in accordance with the oneness of the sensation resulting from simulta- neous impressions on different parts of this organ of sense, and seem to show, that it would be most correct to spealc of the first pair of nerves as a portion of the nervous centre put forward beyond the cra- Olfactory Filaments of the Dog. b. In acetic acid. — Magnified a. In water. 2.50 diameters. ' Op. cit., ii. 5-11. 716 SENSIBILITY. nium, in order that it ma}'' there receive, as at first hand, the impres sions of which the mind is to become cognizant. Besides the first pair of nerves, the pituitary membrane receives several branches from the fifth encephalic pair; for example, the nasal twig of the ophthalmic branch of the fifth, and filaments from the frontal branch of the same ; from the spheno-palatine ganglion ; the palatine nerve ; the vidian nerve ; and from the anterior dental branch of the superior maxillary. One of these twigs enters the anterior naso-pala- tine canal ; and, in its course to the roof of the mouth, passes through a small ganglion, which has been described by M. H. Cloquet under the name naso-jjalatine, and which he conceives to be the organ of sym- pathy between the senses of smell and taste. The pituitary membrane is kept moist by nasal mucus, as well as by the exhalation that constantly takes place from it. It receives the superfluous tears by means of the ductus ad nasum, — a duct passing from the inner canthus of the e3'e, and opening into the nasal fossae below the lower spongy bone. The constant evaporation which must take place from the membrane, owing to the passage of the air during respiration, requires that the secretion should be continuous and copious, otherwise the membrane would become dry. The nasal fossee communicate externally by means of the nostrils, the shape, size, and direction of which vary, so as to give rise to the aquiline, Roman, inig, and other varieties of nose. At the extremity of the nostrils long hairs are situate — technically called vihrissce — whose function, it is conceived, may be to sift, as it were, the air passing through during respiration, and thus prevent extraneous bodies from entering the fossa3. The nostrils are also capable of being expanded or contracted by appropriate muscles. In this sense, there is a more clear separation between the physical and nervous part of the apparatus than in either of those alread}^ con- sidered ; — the nose proper forming the physical portion ; and the nerves of smell the organic or nervous. 2. ODOUES. The comprehension of the physiology of olfaction will not be complete ■without an inquiry into odours or those emanations from odorous bodies, that give them their character, and impress the organ of smell. It was long maintained, as in the case of savours, that odours are dependent upon a peculiar principle, which, according to its particular combination with the constituents of bodies, gives rise to various odours. To this principle the terms aroma and spiritus rector hsive been assigned; but the notion has been long abandoned, because no general or common characters are observable amongst odorous bodies, which should be expected were they indebted for their odour to the same principle. Walther, a German physiologist, expresses the opinion, that an odorous body is such by virtue of a vibratory motion, analogous to that made by a sonorous body. We have, however, the most satisfactory evidence, that there are special odours, as there are special savoury molecules. We can prevent an odorous body from impressing our olfactory nerves by covering it with a glass receiver. Odours can be separated By in- fusion and distillation. The fact, moreover, has been directly proved by ODOURS. 717 an experiment of M. Bertbollet. On nearly filling a tube with mercury, and placing a piece of camphor at the top of the tube, he found that, after a time, the mercury descended, the camphor had diminished in size, and the space above the metal was occupied by an odorous gas.* But what is the cause of the diseno;a2:ement of these odorous mole- cules? By most writers on this subject it has been considered to be owing to the solvent action of caloric on the odorous body. The opinion that all bodies are odorous is as old as Theophrastus; and it is one which it is difficult not to embrace, if we add — provided they are subjected to the appropriate agents for disengaging the odorous particles ; and the probability is, that the reason we esteem particular bodies inodor- ous is, that our olfactory nerves are not organized with sufficient deli- cacy to enable us to distinguish their odorous properties. Heat assists the escape of odorous particles from a variety of bodies ; and hence it has been maintained, that every body which is volatile must be odor- ous. M. Adelon^ asserts, that this is not the case; but it is difficult to accord with him. The fact of our not appreciating the odour is no proof of its non-existence. In truth, bodies that are inodorous to one animal or individual may not be so to another. In cases, too, in which smell is morbidly acute, a substance may appear overwhelmingly odor- ous, which may seem devoid of smell to a healthy individual. M. H. Cloquet^ refers to the case of a celebrated Parisian physician, who was subject to violent attacks of hemicrania or megrim, and who was dreadfully tormented, during one of the paroxysms, by the smell of copper, exhaled from a pin that had been dropped on the bed ! Caloric seems to be only one of the causes of the disengagement of odours. Some are retained by so feeble a degree of affinity, that they appear to be exhaled equally at all temperatures. Light influences their escape in particular cases; some plants giving off' their fragrance during the day ; others perfuming the air only at night. Dampness, in many instances, assists their escape, — hence the fragrance of a gar- den after a summer's shower ; and the smell afforded by all argillaceous substances when breathed upon, — a fact, the knowledge of which is of importance to the chemist. Lastly; — substances, that appear to us devoid of odour, may exhale a strong one, when rubbed together. All these circumstances tend greatly to prove, that every substance is possessed of odorous quali- ties, although we may not be aware of the precise mode for causing their emanation, or our olfactory nerves may not be sufficiently deli- cate to appreciate them. Ai'ouud odorous bodies, the molecules, as they escape, form an atmo- sphere, which, of course, will be denser, the nearer it is to the body. These particles are diffused around, — not, probably, in the same man- ner as light or sound, but as one fluid mixes with another; and, when the air is still, it is conceived, their strength will be inversely as the square of the distance from the substance that exhales them. There is a great difference, however, in odours as regards their diftusibility in ' Cloquet, Art. Odeurs, Diet, des Sciences Medicales, torn. xxxvii.,p. 89, Paris,1819. « Op cit., i. 322. 3 Ospliresiologie ou Traite des Odeurs, Paris, 1821. 713 SENSIBILITY. the atmosphere. Some extend to a great distance, whilst others are confined ^s'ithin a small compass. The odours of many flowers are so delicate as not to be appreciated, unless they are brought near the olfactory organs; whilst that of cinnamon is said to have been detect- ed at sea, at the distance of twenty-five miles from Ceylon. Lord Valentia^ affirms, that he himself distinctly smelt the aromatic gale at nine leagues' distance; — but Dr. Kuschenberger^ was not equally fortunate. The author was informed by Commodore Stewart, of the Navy, that he had discovered the spicy emanations when two hun- dred miles from Ceylon, and the terebinthinate odours of the pines of Virginia, when one hundred miles from the coast; and Dr. Wil- cocks, of Philadelphia, when at sea in 1844, and two hundred miles to the westward of the coast of Ireland, observed, as did- many others of the passengers, a smoky odour, which lasted for several days in suc- cession. On appealing to the captain for the cause of the phenomenon, he informed them that he had frequently remarked it before; and that it was owing to the long continuance of easterly winds, which carried the odour of burning peat from Ireland far out to sea.^ Facts of this kind are employed by the natural philosopher to exhibit the excessive divisibility of matter. Scales, in which a few grains of musk have been weighed, have retained the smell for twenty years afterwards, although they must have been constantly exhaling odorous molecules during the whole of this pericjd. Ilaller'* kept some pa})ers, for more than forty years, which had been perfumed by a single grain of amber; and, at the end of that time, they did not appear to have lost any of their odour. That distinguished physiologist and mathe- matician calculated, that every inch of their surface had been im- pregnated by osyro'sToiio^^'' ^^ ^ grain of amber, and yet they had scented for 14,600 days a stratum of air at least a foot in thici17, Luiul., 1^;;!*. ^ Pliysiology, ii. 5G1, cited by Dr. Carpenter, art. l^luel), in Cyclopredia of Anatomy and Physiology, pt. xxxvi. p. 703, Lend., June, lb4y^ VOL. I. — 10 722 SENSIBILITY. by savoury smells upon the appetite. It is not probable, that absorp- tion can occur to a sufficient extent to account for the apparent satiation. The fact can only be explained by the impression upon the nervous system, which influences the appetite materially, as we see in the effect of various mental emotions. The first impact of a nauseous odour, or even the view of a disgusting object, frequently converts the keenest appetite into loathing. Yet, anciently, it was believed, that life might be sustained for a time, by simply smelling nutritious substances. Democritus is said to have lived three days on the vapour of hot bread ; and Bacon refers to a man who supported an abstinence of .several days by inhaling the odour of a mixture of aromatic and alli- aceous herbs. Two hundred years ago these notions were entertained to a great extent ; and they suggested the viaticum for travellers pro- ceeding to the moon, according to the plan proposed by Dr. John Wil- kins. Bishop of Chester.^ " If we must needs feed upon something," he remarks, " why may not smells nourish us ? Plutarch and Pliny, and divers other ancients, tell us of a nation in India that lived only upon pleasing odours; and it is the common opinion of physicians that these do strangely both strengthen and repair the spirits." Fuller,^ a learned cotemporary of the bishop affords an amusing instance of liti- gation, originally given by Rabelais,^ — whom he does not cite, however, — arising from this supposed nourishing character of odours. A poor man being very hungry, stayed so long in a cook's shop who was dish- ing up the meat, that his stomach was satisfied with the smell thereof. The choleric cook demanded of him pay for his breakfast ; the poor man denied having had any ; and the controversy was referred to the decision of the next man that should pass by, who chanced to be the most notorious idiot in the whole city : he, on the relation of the mat- ter, determined that the poor man's money should be put betwixt two empty dishes, and that the cook should be recompensed with the jin- gling of the money, as the man had been satisfied by the smell of the cook's meat. It need scarcely be said, that if the vapour from alimentary sub- stances be capable, in an}' manner, of serving the purposes of nutrition, it can only be by passing into the blood-vessels of the lungs. 3. PHYSIOLOGY OF OLFACTION. In order that the sense of smell may be duly exercised, it is neces- sary that the emanation from an odorous body shall not only impinge upon the pituitary membrane, but that it shall do so with some degree of force. It must, in other words, be drawn in with the inspired air. Perrault^ and Lower^ found, that by making an opening into the tra- ' The Discovery of a New Woikl, or a Discourse tending to prove, that 'tis possible there may be another Habitable Workl in the Moon, with a Discourse concerning the possibility of a passage thither. Loud., 1G38. ^ Holy'State, London, 1()40. ' The Works of Francis Rabelais, ii. 115, Loud., 1849. In a note it is stated, "that Bocchoris, according to Plutarch, gave a similar juilgnient against the courtesan Tho- nis, who demanded in money the price of her favours from a young spark, who had enjoyed them in imagination only." ■* Ess. de Phys., iii. 2i). * Needham, de Format. Foetus, p. 165 ; and Haller, edit, cit., v. 173. PHYSIOLOGY OF OLFACTION. 723 chea of animals, and preventing the inspired air from passing tlirongli the nasal fossae, smell was not effected ; and that dogs, which were the subjects of the experiment, readily ate food they had previously refused. These experiments were repeated by Professor Chaussier, and with like results.' They explain why we use effort to draw in air loaded with an odour that is agreeable to us ; and, on the contrary, arrest the respiration, or make it pass entirely through the mouth when odours are disagreeable. Still they are occasionally so diffusible and expan- sible, that they reach, notwithstanding, the olfactory membrane ; and we are compelled to shut them off by calling in the aid of the upper extremity. The air being the ordinary medium for the conveyance of odorous molecules, we can understand why the organ of smell should form a part of the air passages. The use of the nose is to direct the air, charged with odours, towards the upper part of the nasal fossae. Its situation is well adapted for the reception of emanations from bodies beneath it, and its appropriate muscles allow the nostrils to be more or less expanded or contracted. These uses assigned to the nose are demonstrated by the fact, that they, whose noses are deformed — especially the flat-nosed — or whose nostrils are directed forwards, instead of downwards, have commonly the sense feebly developed. The loss of the nose, too, either by acci- dent or disease, has been found to destroy the sense completely ; and by no means the least advantage of the rhinoplastic operation is the enjoyment afforded by the improvement of this sense. M. Beclard affirms, that an artificial nose, formed of paper or other appropriate materials, is sufficient to restore it, so long as the substitute is attached.'^ It is proper to remark, however, that in a case which fell under the author's observation, although the nose had been lost by syphilis, the smell persisted ; and two cases of a similar kind occurred to M. P. H. Berard.' The mode in which olfaction is effected appears to be as follows : — The inspired air, loaded with odorous particles, traverses the nasal fossae ; and, in its passage, comes in contact with the pituitary mem- brane, through the medium of the nasal mucus. The use of this mucus seems to be, not only to keep the organ properly lubricated, but to arrest the particles as they pass, — not by any chemical attraction, but in a mechanical manner. The olfactory nerves being distributed on the membrane, receive the impression of the molecules, and, in this manner, sensation is accomplished. The use of the different spongy or turbinated bones would seem to be to enlarge the olfactory surface. According to some, however, they form channels to direct the air towards the openings of the sinuses. The sinuses, themselves, afford subjects for physiological discussion. By many they are considered to add to the extent of olfactory surfice : by others, to furnish the nasal mucus. No hesitation would be felt in pronouncing both the spongy bones and sinuses to be useful in olfaction, were it not that the olfactory nerves or first pair have not been traced on the pituitary membrane covering the middle and inferior spongy ' Adelon. op. cit., i. 335. ^ Magemlie, Precis El-'inentaire, 2(le I'dit., i. I'M), Paris, IS'Zf). 3 Art. Olfaction, Diet, de Medecine, 2dc edit., xxii. 9, Paris, 1840. 724 SENSIBILITY. bones, or on that lining the different sinuses ; — that the sinuses are wanting in the infant, which, notwithstanding, appreciates odours; — that they exist only in the mammalia ; — and that experiments would seem to show, that the up])er part of the olfactory organ is more par- ticularly destined for the function, and that the sinuses, which, as well as the membrane covering the middle and lower spongy bones, are supplied by filaments from the fifth pair of nerves, are not sensible to odours. Messrs. Todd and Bowman' — from the fact, that on the septum na- rium and turbinated bones bounding the direct passage from the nostrils to the throat, the lining membrane is rendered thick and spongy by the presence of ample and capacious submucous plexuses of both arteries and veins, of which the latter are by far the larger and more tortuous — surmise, and Dr. Carpenter^ thinks, with much probability, that the chief use of these may be to impart warmth to the air, before it enters the proper olfaetive portion of the cavity; as well as to afford a copious supply of moisture, which may be exhaled by the abundant glandulas seated in the membrane. ''The remarkable complexity of the lower turbinated bones in animals with active scent, without any ascertained distribution of the olfactory nerves upon them, has" — they remark — "given countenance to the supposition, that the fifth pair may possess some olfactory endowment, and seems not to have been explained by those who rejected that idea. If considered as accessory to the perfec- tion of the sense in the way above alluded to, this striking arrangement will be found consistent with the view, which thus limits the power of smell to the first pair of nerves." That the upper part of the nasal fossae is the great seat of smell is proved by the facts referred to regarding the uses of the nose. Dessault mentions the case of a young female, who had a fistula in the frontal sinuses, and who could not perceive an odorous substance, when pre- sented at the orifice of the fistula, because there was no communication with the proper poi'tion of the nasal foss«, although she was capable of breathing through the opening. M. Deschamps, the younger, relates the case of a man, who had a fistula of the frontal sinus, through which ether might be injected without its odour being appreciated, provided all communication had been previously cut off' between the sinus and the upper part of the nasal fossae; but if this precaution had not been taken, the sense was more vivid, when the odours passed through the fistulous opening, than when they reached the organ by the ordmary channel. Again; — AI. Richerand^ found that highly odoriferous injec- tions, thrown through a fistulous opening in the maxillary sinus or antrum of Highmore, produced no olfactory sensation whatever. All these facts would seem to lead to the belief, that the upper part of the nasal fossas, on which the first pair or olfactory nerves are dis- tributed, is the chief seat of olfaction, and that the inferior portions of these fosstB, as well as the different sinuses communicating with them, are not primarily concerned in the function; but, doubtless, offer se- condary advantages of no little importance. This conclusion would, ' Physiological Anatomy and Physiology of Man, ii. 3. 2 Art. Smell, Cyclop, of Anat. and Physiol., pt. xxxvi. p. 694, Lond., June, 1849. 2 Elemens de Physiologie. edit. 13eme par Berard, p. 202, Bruxelles, 1837. PHYSIOLOGY OF OLFACTION. 725 however, seem to admit, wliat is not by any means universally admitted, that the olfaetory is the sole or chief nerve of smell. Especially diffi- cult is it to embrace this view, and not to believe that the spongy bones and sinuses on which the fifth pair are distributed, are agents in per- fecting the sense, when we find them so largely developed in animals that possess unusual delicacy of smell, as the dog and elephant. It has already been remarked, that the ancients believed the olfactory nerves to be canals for conveying away the pituita or phlegm from the brain. Diemerbroeck, also, maintained this view,' At the early part of the last centur}^ however, the olfactory was supposed to be the proper nerve of smell, and the opinion prevailed, with few dissentient voices, until within the last few years. Inspection of the origin and distribution of the nerve seems to indicate it as admirably adapted for special sensibility connected with smell. It is largely developed in animals in proportion to their acuteness of the sense, and is distributed on the very part of the pituitary membrane to which it is necessary to direct air, loaded with odorous emanations, in order that they may be appreciated. M. Magendie^ has, however, endeavoured to show by experiment, that the sense of smell is in no wise, or little, dependent upon the olfactory nerve, but upon branches of the fifth pair. Prior to the institution of his experiments, he had observed with astonishment, that after he had j-emoved the cerebral hemispheres, with the olfactory nerves of animals, they still preserved this sense. He had noticed, too, that it continued in lunatics, who had fallen into a state of stupor, and in whom the substance of the brain appeared, on dissection, greatly disorganized. These facts induced him to expose the olfactory nerves on living ani- mals, and to experiment upon them; and he found, in the first place, that the nerves were insensible to puncture, pressure, and the contact of the most odorous substances. He afterwards satisfied himself, that after their division the pituitary membrane not only preserved its general sensibility, appreciated the contact of bodies, but also, strong- odours, those of ammonia, acetic acid, oil of lavender, Dippel's oil, &c. On the other hand, having divided the fifth pair of nerves within the cranium, and left the olfactory nerves entire, he remarked, that the pituitary membrane had lost its general sensibility; was no longer sen- sible to contact of any kind ; and had lost the power of appreciating odours. From these experiments, he considered himself justified in inferring, that the olfactory nerve does not preside over the general sensibility of the nose; that it has, at the most, a special sensibility as concerns odours; and that if the olfactory be the nerve of smell, it re- <|uires the influence of the fifth pair, in order that it may act. Lastly; lie asks, may not the general and special sensibility be comprised in the same nerve in the sense of smell, as they are in that of taste; — in the fifth pair? These experiments are interesting; but they by no means establish, that the fifth pair is the olfactory nerve. The numerous facts, already mentioned, attract us irresistibly to the first pair or olfacton/^ as they have been exclusively called. It has been already remarked, that the ' Anatome Corporis Humani, lib. iii. cap. 8, Ultraject., 1672. '^ Precis El.mentaire, 2i.le edit., i, 132. 46* 726 SENSIBILITY. lifth is concerned in all the facial senses; that it convej's to them gene- ral sensibility or feeling; and that some of them are unquestionably supplied with nerves of special sensibility; — the eye with the optic; and the ear with the auditory; but that neither perhaps can fully exert its special functions, without the integrity of the fifth. The olfactory nerve is probably in this category, — is the nerve of special sensibility. It is true, that in the experiments of M. Magendie the animal appeared to be affected by odorous substances, after the division of the first pair ; but a source of fallacy existed here, in discriminating accurately between the general and special sensibility. Some of the substances employed were better adapted for eliciting the former than the latter; — ammonia and acetic acid, for example. In a case before referred to,^ whilst the olfactory nerve was paralyzed and smell proper was wholly lost, the person was able to appreciate the contact of pun- gent substances; and the application of snuff' to the Schneiderian mem- brane occasioned sneezing, because the ramifications of the nerve of the fifth pair or nerve of general sensibility were unaffected. The immediate function of the sense of smell is to appreciate odours. In this it cannot be supplied by any other sense. The function is in- stinctive; requires no education; and is exerted as soon as the parts have attained the necessary degree of developement. In many respects the sense is intimately connected with that of taste ; and the impres- sions made upon each are frequently confounded. In the nutritive function, the smell serves as a kind of advanced guard or sentinel to the taste ; and warns us of the disagreeable or agreeble nature of the aliment; but if a substance repugnant to the smell be agreeable to the taste, the smell soon loses its aversion, or at least becomes less disa- greeably impressed. The smell is not, however, in man so useful as a sentinel to the taste, as it is to animals: there are many bodies, — those containing prussic acid for example, — which are extremely pleasing by the odours they exhale, and yet are noxious to man. In the animal kingdom, this sense is greatly depended upon, and is rarely a fallacious H'uide. It enables animals to make the proper selection of the noxious from the innocent; — the alimentary from that which is devoid of nutri- ment; — the agreeable from the disagreeable ; and the power appears to be instinctive or dependent upon inappreciable varieties of structure in the organs concerned in olfaction. As an intellectual sense, smell is not entitled to a higher rank than taste. Its mediate functions are very limited. It enables the chemist, mineralogist, and perfumer, to discriminate bodies from each other. We can, likewise, by it form a slight — but only a slight — idea regard- ing the distance and direction of bodies, owing to the greater intensity of odours near an odorous body, than at a distance from it. Under ordinary circumstances, the information of this kind derived by olfac- tion is inconsiderable; but in the blind; and in the savage, who is accustomed to exercise all his external senses more than the civilized, its sphere of utility and accuracy is largely augmented. Of this we shall have to speak presently. We find it, too, surprisingly developed ' Page 710. IMMEDIATE FUNCTION" OF SMELL. 72i in certain animals; in wliicliit is considered, by the eloquent Buffon, as an eye that sees objects not only where they are, but where they have been, — as an organ of gustation, by which the animal tastes not only Avhat it can touch and seize, but even what is remote, and cannot be attained ; and he esteems it a universal organ of sensation, by which animals are most readily and most frequently impressed; by which they act and determine, and recognise whatever is in accordance with, or in opposition to, their nature. The hound amongst quadrupeds affords us a I'amiliar example of the extreme delicacy of this sense. For hours after the passage of game, it is capable of detecting its traces; and the l)loodhound can be trained to indicate the human footsteps with unerr- ing certainty. Until of late years, it was almost universally believed, that many of the birds of prey possess an astonishingly acute sense of smell. Plum- l)oldt^ relates, that in Peru, Quito, and in the province of Popayan, when they are desirous of taking the gigantic condor — Vultur grijj)hus of Linnaeus — they kill a cow, or horse, and in a short time, the odour of the dead animal attracts those birds in numbers, and in places where they were scarcely known to exist. It is asserted, that vultures went from Asia to the field of battle at Pharsalia, a distance of several liundred miles, attracted thither by the smell of the killed!^ Pliny ,-' liowever, exceeds almost all his contemporaries in his assertions on this matter. He affirms, that the vulture and the raven have the sense of smell so delicate, that they can foretell the death of a man three days beforehand, and in order not to lose their prey they arrive upon the spot the night before his dissolution! The turkey-buzzard of the United States is a bird of this class, and it is surprising to see how soon they collect from immense distances after an animal has died in the forests. The observations and experiments of the ornithologist Audubon'' would seem, however, to show that this, bird possesses the sense of smell in a less degree than the carnivorous quadruped. He stuffed the skin of a deer with hay, and after the whole had become ])erfectly dry and hard, placed it in an open field on its back, and in the attitude of a dead animal. In the course of a few minutes a vul- ture was observed flying towards it, which alighted near, and began to attack it ; tearing open the seams, and pulling out the hay ; but finding that it could obtain nothing congenial to its taste, it took flight. It was found, too, that when animals in an advanced state of putridity were lightly covered over so as to prevent vultures from seeing them, they remained undisturbed and undiscovered, although the birds re- ]ieatedly flew over them. In some other experiments it was found, that birds of prey were attracted by well-executed representations of dead animals painted on canvass and exposed in the fields, — and in ')thers, that young vultnres, enclosed in a cage, exhibited no tokens ol' their perceiving food, when it could not be seen by them, however near them it was brought. These results — which were obtained, also, by Dr. Bachman in the presence of a number of scientific gentlemen of ' Rec. de Zoolog. et d'Anat. Comp., 2de livr.,p. 73, Paris, 1807. ^ Haller, edit, cit., torn. v. lib. xiv. j). LOS. 3 Hist. Nat., lib. x. cap. «, p. 230, Lugd., 1587. ■• Oniitliological Biography, p. 33, Boston, 1835 ; Loudon's Mag. of Nat. Hist.,Yii. 1(J7. 728 SENSIBILITY. Charleston, South Carolina — are strange, inasmuch as the olfactory apparatus of the turkey-buzzard, when examined by the comparative anatomist, exhibits great developement, and admirable adaptation for acuteness of smell. They are confirmed, however, by more recent expe- riments on the condor by Mr. Charles Darwin,^ a distinguished natu- ralist. He tied several condors by ropes in a long row at the bottom of a wall ; and having folded up a piece of meat in white paper, he walked backwards and forwards carrying it in his hand at the distance of about three yards from them ; but no notice whatever was taken of it. He then threw it on the ground within one yard of an old male bird, which looked at it for a moment with attention, but regardecl it no more. With a stick he pushed it closer and closer, until at last the bird touched it with its beak; the paper was then instantly torn oft' with fury, and at the same moment every condor in the long row began struggling, and flapping its wings. "Under the same circumstances, it would have been quite impossible to have deceived a dog." As the organ of smell, in all animals that respire air, is situate at the entrance of the organs of respiration, it is probable that its seat, in insects, is in the mouth of the air tubes. This sense appears to guide them to the proper kinds of food, and to the execution of most of the few offices they perform during their transient existence. Occasionally, however, they are deceived by the resemblance between odours of substances very different in other qualities. Certain plants, for ex- ample, emit a cadaverous odour similar to putrid flesh, by which the flesh-fly is attracted, and led to deposit its ova in places that can furnish no food to its future progeny. As regards the extent of the organ of smell, man is undoubtedly worse situate than most animals ; and all things being, in other re- spects, equal, it may be fair to presume, that those, in which the olfac- tory membrane is- most extensive, possess the sense of smell most acutely. It is curious, however, that certain animals, which have the sense of smell in the highest degree, feed on the most fetid substances. The dog, for instance, riots in putridity ; and the birds of prey, to which reference has been made, but whose acuteness of smell, we have seen, has been contested, have similar enjoyment. The turkey-buzzard is so fetid and loathsome, that his captors are glad to loosen him from bondage ; and it is affirmed, that if his ordinary foetor be insufficient to produce his release, he affords an irresistible incentive, by ejecting the putrid contents of his stomach upon them P One inference may, perhaps, be drawn from this penchant of animals with exquisite olfactories for putrid substances; — that the taste of the epicure for game, kept until it has attained the requisite /wme^, is not so unnatural as might at first sight appear. Like the senses already described, that of smell is to a certain extent under the. influence of volition : — in other words, it can be exerted actively^ and passively. Its active exercise — as when we smell any substance to enjoy its sweets, or test its odorous qualities — generally ' Joiirnal of Researches into the Natural History and Geography of the countries visited during the voyage of H. M. S. Beagle rouiul the World, Aiuer. edit., New York, 1846. ^ Wilson's American Ornithology, by Geo. Ord, Philad., 1803-1814. SMELL IMrROVED BY EDUCATION. 729 requires prehension, the proper direction of the head towards the object, and more or less contraction of certain muscles of the alae nasi. Doubtless, here again, the papillas are capable of being erected under attention, as in the senses of taste and toach. On the other hand, we can throw obstacles in the way of the reception of disagreeable odours ; and, if necessary, prevent their ingress altogether, by compressing the nostrils with the upper extremity. Lastly : — like the other senses, smell is capable of great improvement by education. The perfumer arrives, by habit, at an accurate discri- mination of the nicest shades of odours; and the chemist and the apothecary employ it to aid them in distinguishing bodies from each other ; and in pointing out the changes that take place in them, under the influence of heat, light, moisture, &c. In this way, it becomes a useful chemical tost. The effect of education is likewise shown, by the difference between a dog kept regularly accustomed to the chase, and one that has not been trained. For the same reason, in man, the sense is more exquisite in the savage than in the civilized state. In the latter, he can have recourse to a variety of means for discriminating the properties of bodies ; and hence has less occasion for acuteness of smell than in the former ; whilst, again, in the latter state, numbers destroy the sense to procure pleasure. The use of snuff is one of the most common of these destructive influences. Of the acuteness of the sense of smell in the savage we have an example on the authority of Humboldt : he affirms, that the Peruvian Indian in the middle of the night can distinguish the different races by their smell, — whether they are European, American Indian, or negro. To the same cause must be ascribed the delicacy of olfaction generally observed in the blind. The boy Mitchell,^ who was born blind and deaf, and whose case will have to be referred to hereafter, was able to distinguish the entrance of a stranger into the roonj by smell alone. A gentleman, blind from birth, from some unaccountable impression of dread or antipathy, could never endure the presence of a cat in the apartment. One day, in company, he suddenly leaped up ; got upon an elevated seat ; and exclaimed, that a cat was in the room, begging them to remove it. It was in vain that the company, after careful inspection, assured him he was under an illusion. lie persisted in his assertion and state of agitation ; when, on opening the door of a small closet, it was found that a cat had been accidentally sliut up in it. ' Wanlrop's History of James Mitcliell, Loud., 1813 ; and Dugald Stewart's Elements of the Philosophy of the Human Mind, iii. 401, 3d edit., Lond., 1S08. END OF VOL. I. 78 6 UNIVERSITY OF CALIFORNIA LIBRARY Los Angeles This book is DUE on the last date stamped below. t"d£D5LI574 DEClSREC'D Form L9-40m-5,'67(H2161s8)4939