UC-NRLF 
 
LIBRARY 
 
 University of Californi 
 
 Class 
 
 S ' lXH. 
 ;3RARY 
 
PHILOSOPHY 
 
 INSTINCT AND EEASON. 
 
ruiNTED BY NEILL AND CO., OLD FISHMARKKT. 
 EDINBURGIf. 
 
THE 
 
 PHILOSOPHY 
 
 OP 
 
 INSTINCT AND REASON, 
 
 J. STEVENSON BUSHNAN, 
 
 M. D., F.L.S. 
 AUTBOH OF THE INTRODUCTION TO THE STUD.Y OF NATITHE, 
 
 EDINBURGH: 
 ADAM AND CHARLES BLACK, 
 
 BOOKSELLERS TO HIS MAJESTY FOR SCOTLAND. 
 MDCCCXXXVII. 
 
GENEDAL 
 
 
DEDICATION. 
 
 TO HENRY LORD BROUGHAM, F.R.S., 
 
 AND MEMBER OF THE INSTITtJTE OF FRANCE. 
 
 My Lorb^ 
 
 I GLADLY avail myself of the permission 
 your politeness has afforded me, to add to the fol- 
 lowing pages the lustre of a name associated with 
 almost emry department of literature and science. 
 In such a dedication^ I am fully aware the ad- 
 loa/ntage is altogether upon my side ; nothing that 
 Ihaioe written, or may write, can add to the 
 fame of your Lordship'^s labours, while your 
 name may seme as a passport to mine where their 
 own unassisted powers could not gain them ac- 
 cess. 
 
 But it giioes me, my Lord, peculia/r pleaswe to 
 take this opportunity of telling the world of my 
 
 SG1596 
 
VI DEDICATION. 
 
 readers^ — small as that world may be, — that al- 
 tkouphdifferiuff with your Lordship on many high- 
 ly important points, what is the high sense I enter- 
 tain of your genius — enlightening every subject 
 on which it glances ; adorning every pursuit to 
 tchich it applies its powers; and giving energy and 
 direction to every measure which it influences. 
 
 In the folloicing Treatise I differ from your 
 Lordship in many opinions which you support in 
 your late work on Natural Theology ; but I am 
 too well acquainted with your Lordship'^s charac- 
 ter not to feel assured, that the expression of a 
 conscientious conviction, however much opposed to 
 your own, will always be received by you with 
 candour and indulgence. 
 
 I have the honour to be. 
 
 Your Lordship'' s most obedient 
 
 And very humble Servant, 
 
 J. STEVENSON BUSH NAN. 
 
 Ansford House, 
 
 Castle Cary, Somersetshire. 
 
 June 1837. 
 
Vll 
 
 CONTENTS. 
 
 CHAP. I Introductiok, . . . Page 1 
 
 II. — The Functions of Organized Bodies, 12 
 
 III. — Nervous System in Vertebrate Animals, 20 
 
 Section I — In Man, ... 23 
 
 II — In Animals below Man, . 57 
 
 IV — Nervous System in Avertebrate 
 
 Animals, .... 67 
 
 V. — Of Irritability in Plants and Animals, 78 
 VI. — Seat of Irritability, ... 92 
 
 VII. — Of Sensation as a cause of Motion in 
 
 Animals, ..... 99 
 y/ VIII. — The Nature of Instinct, . . . 137 
 
 IX. — The Nature of Thought, . . 186 
 
 X. — Opinions or Metaphysicians as to the 
 
 Nature of Thought, . . 231 
 
 XI. — Of Reason in Animals, . . . 266 
 
 "^ XII Seat of Thought 304 
 
PREFACE. 
 
 In presenting the following work to the public, 
 I can claim no greater naerit than that of applying 
 certain received principles of physiology to the sub- 
 jects of which it treats ; by which, as I cannot but 
 feel convinced, they are disentangled from many of 
 the grave objections applicable to the common 
 views taken of them, and thereby rendered more 
 worthy of a place in a rational philosophy. 
 
 The general reader, I am well aware, fears to 
 encounter a treatise on Instinct and Reason, per- 
 suaded, as he is, of the little profit to be reaped 
 from the established modes of discussing such sub- 
 jects, and altogether unprepared to admit that they 
 can be made obedient to any intelligible law or 
 condition. This persuasion, however, on his part, 
 has arisen entirely from those great principles of 
 action having hitherto been treated of more in a 
 
X PREFACE. 
 
 metaphysical tlian in a physiological point of view. 
 And, indeed, to the abstruse and entangled style 
 of metaphysical speculations, there is perhaps a 
 stronger bias, at least in the majority of those who 
 turn naturally to such inquiries, than to the plain 
 and simple spirit in which physiological deductions 
 must be conducted ; so that I fear not a few may 
 refuse to listen to the attempt I have made, in the 
 following pages, to distinguish Instinct from Rea- 
 son, rather by some essential differences in the con- 
 dition of each, than by differences — often acciden- 
 tal — in their phenomena. 
 
 The physiological principles on which the views 
 taken in this Treatise are founded — although it can- 
 not be affirmed that they are all received, without 
 exception, by the physiological world — are support- 
 ed by the highest authority ; and most of them are 
 familiar to those who are acquainted with the writ- 
 ings of physiologists in the past, as well as the pre- 
 sent age. But my chief obligations for the gene- 
 ral tenor of the treatise are due to the instructions 
 of my much lamented friend and preceptor, the late 
 Dr Fletcher. 
 
 In Dr Fletcher, Edinburgh lost an ornament, 
 brilliant even among the many shining lights that 
 
PREFACE. XI 
 
 have adorned her academic walks ; her Schools of 
 Medicine, a teacher whose erudition and acumen had 
 begun to infuse new vigour into their constitutions ; 
 science, a labourer who gave rich promises of add- 
 ing to her stores ; and the favoured few who were 
 bound to him by the ties of intimacy, a friend, who 
 walked, almost alone, in the affectionhe excited. 
 
 J. S. B. 
 
 Ansford House, 
 
 Castle Gary, Somersetshiri;, 
 
 June 1837. 
 
UNIVERSITY 
 
 OF 
 
 PHILOSOPHY 
 
 INSTINCT AND REASON. 
 
 CHAPTER I. 
 
 INTRODUCTION. 
 
 The actions of the inferior animals, in as far as 
 they conduce to some particular end, and appear, 
 therefore, to imply motive and foresight, are in ge- 
 neral referred to Instinct ; while all those of man 
 of a similar character are in turn traced to Reason, 
 There is commonly displayed the utmost unwilling- 
 ness to allow any glimmerings of Eeaso?i to brutes, 
 since such an admission seems to exalt them be- 
 yond their proper sphere, by conceding to them a 
 portion of what we have been accustomed to con- 
 sider the chief attribute of man ; and an equfJ repug- 
 nance to acknowledge that any of the actions of man 
 are Instifictive, since he appears to be humbled by 
 being represented as ever actuated by any princi- 
 ple in common with brutes. The epithet of Ra- 
 tional Being is very generally appropriated to man, 
 
2 INTRODUCTION. 
 
 as the direct antithesis to that of Brute, which is 
 apphed to all other animals ; and prejudiced peo- 
 ple are always disposed to make this assumed line 
 of demarcation as distinct and as wide as possible. 
 Nor is this prejudice confined to the vulgar — nay, 
 it is, in all probability, from philosophers that they 
 have originally imbibed this, as well as most other 
 fallacies. It has been from the earliest ages as- 
 sumed in most schools of philosophy, that the lower 
 animals are guided by definite instincts to the full 
 attainment of all their wants, and all the ends for 
 which Providence has designed them — that they 
 do not require reason, and therefore do not possess 
 it ; w hereas that man, being destitute of any such 
 definite instincts to guide him, and requiring a full 
 share of reason, at once to direct him to the ac- 
 complishment of his wishes, and to minister to the 
 other and more important ends for which he w^as 
 created, has been, on these accounts, endowed with 
 this faculty. But this does not appear to be a le- 
 gitimate way of disposing of the question. We 
 should not begin by assuming that brutes are ac- 
 tuated by instinct alone, and man by reason ; and 
 then endeavour to reconcile all the actions of the 
 former to the one, and all those of the latter to the 
 other: but we should commence by expressly stat- 
 ing what are the conditions of an instinctive, and 
 what those of a reasonable action, as discovered by 
 a patient scrutiny of all the actions belonging to 
 the relative functions of the animal kingdom, all of 
 which, as we shall presently see, must belong to 
 
INTRODUCTION. 3 
 
 one head or to the other; and afterwards rigorously 
 refer to either head any action, whether of brutes 
 or of man, which corresponds to the established de- 
 finition of each. 
 
 As it appears to us, then, an instinctive action is 
 one which, however directly it may minister to 
 some important end, is performed without any con- 
 sciousness, on the part of the agent, of that end ; 
 which is effected as perfectly the first time it is at- 
 tempted as at any subsequent period, and which is 
 quite unsusceptible of any adaptation to particular 
 emergencies: while a reasonable action, on the con- 
 trary, is one which always imphes a consciousness, 
 on the part of the agent, of the end in view ; which 
 becomes only progressively perfect, and which is 
 capable of being variously modified according to 
 existing circumstances. 
 
 Now, can it be reasonably doubted, but that many 
 of the actions, both of the lower tribes of animals 
 and of man, are referable respectively to both these 
 heads ; or affirmed, that there exists any primary and 
 essential distinction, on the one hand, between the 
 principle which directs the young chick to pick up 
 grain the instant it is hatched, and that which 
 prompts the new-born infant to draw milk from the 
 nipple of the mother the first time it is applied to 
 it ; or, on the other, betw een the principle which ac- 
 tuates an old bird in its manifest stratagems, either 
 in the pursuit of advantage, or the shunning of dan- 
 ger, and that which guides an experienced man, in 
 his various measures towards either the attainment 
 
4 INTRODUCTION. 
 
 of good or tlie avoidance of evil? Tn the two former 
 cases, there is no consciousness on the part of the 
 animal, that the aliment taken is to repair the waste 
 of the body; the action of taking it is performed as 
 perfectly the first time it is attempted, as it could 
 have been after a long course of experience and 
 instruction ; and it is invariably the same. In the 
 two latter, on the contrary, the animal has a distinct 
 consciousness of the object in view ; he becomes, 
 by experience, better and better acquainted with 
 the most effectual means of attaining this object ; 
 and he can change or modify his measures, in pro- 
 portion as such a change or modification seems re- 
 quisite. We conclude, therefore, that, while some 
 of the actions of the inferior tribes of animals are 
 instinctive, others spring from reason ; and again, 
 that, while some of the actions of man are the re- 
 sult of reason, others spring from instinct, — the 
 only difference appearing to consist in this, that, in 
 brutes, the great majority of the actions are instinc- 
 tive, while, in man, the great majority of the ac- 
 tions are rational ; and that, in him, the faculty of 
 reason very far surpasses, not in kind, but in de- 
 gree, the same faculty in brutes. 
 
 Accordingly, while there is no tribe of man so 
 savage as not to have acquired, by experience, some 
 rude notion of tilling the ground, and learned at 
 once the uses of fire and the means of kindhng it, 
 and of applying it to their necessities, there is no 
 description of brutes so far advanced as, however 
 necessary to their existence roots, fi'uits and grain 
 
INTRODUCTION. 5 
 
 may be, or whatever comforts they may have de- 
 rived from heat, ever to have attained to the means 
 of artificially rearing the one, or producing, or even 
 keeping alive, the other ; and while, even in the 
 wildest and most imcultivated tribes of the human 
 race, some traces of a barbarous religion are con- 
 stantly to be met with, no rudiment of such a sen- 
 timent has ever betrayed itself in the most highly 
 gifted of the brute creation. 
 
 Still, these are differences in degree only, and 
 not in kind ; and the faculties and sentiments with 
 which many brutes are endowed, appear to be quite 
 competent, were they enlarged and expanded in a 
 high degree, to lead, without any alteration in kind, 
 to all the results which, as displayed by man alone, 
 we commonly attribute to a distinct source; and 
 those who adopt the opposite opinion, seem to dif- 
 fer from us only in as far as they fix their standard 
 of reason somewhat higher than we do. They 
 admit that most of the inferior animals learn many 
 things by experience and education ; but affirm that 
 they are guided, in these cases, by memory alone, 
 without observing that memory can only recall past 
 events, and must be quite inadequate, without rea- 
 son, to prompt an animal, either to repeat an ac- 
 tion from which it has previously derived advan- 
 tage, or to refrain from one from which it has al- 
 ready suffered injury. Again, there are few of the 
 lower animals which do not manifest, besides hope 
 and fear, — which must have actuated them in the 
 instances already adduced, — gratitude to those who 
 
INTRODUCTION. 
 
 have been kind to them, and dislike to those by 
 whom they have been ill used, as well as frequently 
 a decided love of justice, and a hatred of oppression 
 in general. Such impulses as these meet the de- 
 finition which wc are disposed to adopt of reason, 
 without any addition of those strictly intellectual 
 or highly moral qualities, M'hich, by some persons, 
 are made essential to this principle. In these, 
 brutes are unquestionably deficient : they want the 
 more exalted degree, as well as the more continued 
 exercise, of the faculty of reason, which distin- 
 guishes man, in his most abject state, from the 
 higher tribes of other creatures, and which, as it 
 renders him alone a responsible agent, opens upon 
 him alone the prospect of eternal retribution, as his 
 actions shall have been conformable, or otherwise, 
 to those precepts of religion and morality, which he 
 alone is capable of understanding. 
 
 And this analogy between the lower tribes of ani- 
 mals and man, in as far as regards the admission, in 
 both, of a double principle of action, will be still more 
 obvious, if we contemplate lor a moment the pheno- 
 mena of Idiotism, — a state which, when extreme, 
 reduces proud imperial man to the level of the low- 
 est brute ; and it has accordingly been said by Dr» 
 Paris, upon the common presumption that brutes 
 are guided by instinct alone, that an idiot " cannot 
 reason at all, — he acts from animal appetency, and 
 has no will." But we must remember, that the 
 difference between the veriest idiot and a man, not 
 only of sound mind, but of the most exalted under- 
 
INTRODUCTION. 7 
 
 Standing, is in degree only, and not in kind ; and, 
 assuming, for an instant, that the only incentive 
 to action in the brute is instinct, and in the sane 
 man reason, at what point of his degeneracy shall 
 we say that an idiot ceases altogether to be ac- 
 tuated by the latter, and begins to be actuated by 
 the former alone? There is certainly no such 
 point. The instinctive operations of an idiot are 
 not more numerous than those of other men, but 
 his rational operations, in proportion to the degree 
 of his infirmity, are fewer and less dignified, and 
 in so far he approximates to the lower animals. 
 His principles of action are still two ; but the no- 
 bler falls into obscurity, while the baser remains 
 unchanged. " Do we wish,'* says Virey, " the di- 
 recting and preserving power" — that is, instinct — 
 " to become apparent ? Weaken the understand- 
 ing, which restrains or opposes it, and it will im- 
 mediately revive to take the reins of the organic 
 machine, and thus prevent it from destroying it- 
 self." 
 
 It belongs to the introductory part of this work to 
 remark, that some care and attention are occasion- 
 ally requisite, if we would avoid confounding purely 
 instinctive acts with acts of reason, notwithstand- 
 ing the apparent distinctness and easy applicabi- 
 lity of the two definitions which we have laid down. 
 The acts of instinct, which are apt to put on the 
 disguise of reason, are principally those developed 
 in extraordinary circumstances, so that it seems as 
 if the animal accommodated itself, by a process of 
 
INTRODUCTION. 
 
 reasoning, to a new state of tilings. But instincts 
 are not innate, any more than ideas. Every in- 
 stinct is called forth by impressions made on sen- 
 sation, as will hereafter appear more clearly; so 
 that, in the same species, or even in the same in- 
 dividual, it often happens that, owing to the non- 
 application of certain impressions in the earlier part 
 of its existence, certain corresponding acts appear 
 only in the course of life, or not till the impressions 
 which were destined to excite them come to take 
 effect. This is particularly the case with many 
 habits acquired by animals, when transported by 
 man to new climates. 
 
 We have hitherto presumed that instinct and 
 reason are essentially different in their nature, and 
 made it a question only, whether one were proper 
 to brutes, and the other to man ; or whether each 
 were common, under certain conditions, to both. 
 But it would be improper to leave this part of our 
 subject without remarking, that, by some philoso- 
 phers, it has been believed that there is no real 
 distinction between them, — that instinct is but an 
 inferior degree of reason, or — what amounts to the 
 same thing — reason but a superior degree of in- 
 stinct. Thus, by Darwin, all the reputedly instinc- 
 tive actions are regarded as really intellectual ope- 
 rations, lower or higher, according to the less or 
 more elevated rank of the animal ; while, by Hume, 
 all the actions commonly called rational, are looked 
 upon as in fact, a train of instinctive movements, 
 the number of which is, in every animal, greater or 
 
INTRODUCTION. 9 
 
 less, in proportion to its place in the scale of crea- 
 tion. We have above stated, a« one characteris- 
 tic of an instinctive action, that it is from the first 
 perfect, and does not, like a rational action, become 
 only progressively so in proportion to experience ; 
 but Dr Darwin is of opinion that no action is at 
 first perfect ; — that the young chick, for example, 
 has undergone a kind of apprenticeship to the busi- 
 ness of picking up grain, — which it does perfectly 
 as soon as it emerges from the shell, — by having 
 been accustomed, during the whole period of incu- 
 bation, to swallow a portion of the egg for food ; 
 and he thinks it " not unreasonable to conclude, that 
 some of the actions, both of large animals and of 
 insects, may have been acquired in a state preced- 
 ing the present one, and have been derived from 
 the parents to their offspring, by imitation, or other 
 kinds of tradition." Again, we have above repre- 
 sented a consciousness on the part of the agent, 
 of the end in view, as one distinguishing mark of a 
 rational action, as opposed to an instinctive one ; 
 but by Mr Hume it is asserted, " that the experi- 
 mental reasoning itself, on which the whole con- 
 duct of life depends, is nothing but a species of in- 
 stinct, or mechanical power, that acts in us un- 
 known to ourselves, and, in its chief operations, is 
 not directed by any such relations or comparisons 
 of ideas as are the proper objects of our intellec- 
 tual faculties." By Darwin, every tiling is thus 
 referred to reason ; by Hume, every thing to in- 
 stinct; and in either case, of course, the old esta- 
 
10 INTRODUCTION. 
 
 blislicd distinction between brutes and man, with 
 respect to tlieir supposed different principles of ac- 
 tion, must be nugatory. This we have no liesita- 
 tion in beheving to be the case; not, however, be- 
 cause there is but one principle of action, which, 
 of course, must be common to both, but because 
 both afford evidences of two principles of action, 
 which — as we hope to make it appear in the se- 
 quel — are fundamentally distinct from each other. 
 
 As we have remarked in our preface, we appre- 
 hend that a great deal of the difficulty and obscu- 
 rity which hang over the subjects of instinct and 
 reason would have been obviated, had the investi- 
 gation been taken up rather in a physiological, than 
 in a metaphysical spirit ; and had the attempt been 
 made to distinguish the one from the other, ra- 
 ther by some essential differences in the conditions 
 of each, than by any differences — often, perhaps, 
 accidental — in their phenomena. In this view of 
 the matter, instinct and reason, as the actions of 
 living beings, should be regarded only as functions, 
 as much as sight or hearing are functions ; and as 
 every function requires two conditions, namely, a 
 faculty, on the part of the body, of being acted 
 upon, and some power to call this faculty into ac- 
 tion, so this must be the case with instinct and 
 reason. But if the conditions in both cases were 
 the same, the functions could not be, as we have 
 above assumed they are, essentially different ; we 
 must be prepared to prove, therefore, or at least to 
 
INTRODUCTION. 11 
 
 render it probable, that the conditions of instinct 
 and reason are primarily and fundamentally dif- 
 ferent. 
 
 Before, however, entering on the proper subject 
 of our treatise, it seems necessary to lay before the 
 unprofessional reader a short explanation of the 
 nature of the functions of organized bodies ; and 
 then to pass on to the anatomy of the nervous sys- 
 tem throughout the several orders of animals. The 
 latter, which, however, we shall render as brief as 
 possible, must necessarily be somewhat tedious ; 
 yet, as the after part of the treatise is altogether 
 founded upon the functions of that system, as it is 
 more and more developed, as we ascend from the 
 lowest link of the chain of organized beings, through 
 tlie avevtebrate animals — the zoophytes, worms, and 
 insects — to the vertebral — the fishes, reptiles, birds, 
 and mammals — till we arrive at immortal Man, the 
 most exalted example of animated nature, and whose 
 superiority appears, in a great measure, to depend 
 on the more perfect organization of this system, it 
 seems impossible to treat the subject in any other 
 way. without departing from the first rule of phy- 
 siological investigation. To render, however, the 
 descriptions more intelligible to the non-medical 
 reader, we shall refer to a few lithographic plates, 
 which we have introduced for this purpose. 
 
12 ; 
 
 CHAPTER II. 
 
 THE FUNCTIONS OF ORGANIZED BODIES. 
 
 As there is no kind of action, in the economy of 
 organized bodies, which has not been referred, by 
 one philosopher or another, to instinct, it will be 
 useful, before proceeding further in this inquiry, to 
 pass these several kinds of action under review, and 
 to attempt to arrange them under appropriate or- 
 ders. Matter is divided into two great classes, term- 
 ed generally the Inorganic and Organic; the former 
 includes all mineral substances, the latter all vege- 
 tables and animals. Both are formed probably by 
 the combination of more or fewer of the same pri- 
 mary or elementary principles ; but the characters 
 of the resulting compounds, and the properties 
 which they display, are essentially different. 
 
 Of the differences between these two great king- 
 doms of nature, it is not necessary here to treat ; 
 suffice it to say, that a distinguishing mark of an 
 organic substance, in as far as its structure is con- 
 cerned, is, as the name implies, the possession of 
 certain organs, each of which is more or less essen- 
 tial to the welfare of the whole ; and an equally dis- 
 tinguishing mark of the same substance, as far as 
 
FUNCTIONS OF ORGANIZED BODIES. 13 
 
 regards its motions, is the performance by these 
 organs, each of its own proper functio?i, in the sum 
 of which the Hfe of the being appears to consist. 
 A function therefore maybe defined to be the pro- 
 per action of a Hving organ, or set of living organs, 
 conducive to some definite end in the animal eco- 
 nomy. It is therefore quite distinct from a pro- 
 pert?/, such as that of excitability, or a poiver, such 
 as that which calls excitability into action, since it 
 signifies such properties and powers in mutual co- 
 operation. Every action of every individual organ 
 of the animal body is its function, and the due per- 
 formance of this is the only end of its existence ; 
 but the functions, collectively considered, are com- 
 monly classified according to the particular end to 
 which more or fewer of these actions are subser- 
 vient, since they would otherwise be altogether 
 innumerable, and the consideration of them would 
 involve a series of useless repetitions, and present 
 an inextricable chaos without beginning or end. 
 In this view, therefore, we include, under the head 
 of the function of Digestion, all the actions of the 
 several parts of the intestinal canal and its appen- 
 dages, which are instrumental to the assimilation of 
 the food; under that of the function of Circulation, 
 all the actions of the heart, bloodvessels, and other 
 parts, which are subservient to the propulsion of the 
 blood ; and under that of the function of Respiration, 
 all the actions of the chest and its contents, which 
 minister to the conversion of the venous into arte- 
 rial blood and many other important ends. It is 
 
14 FUNCTIONS OF ORGANIZED BODIES. 
 
 obvious, therefore, that the number of functions ad- 
 mitted into any treatise on pliysiology, is almost 
 entirely arbitrary, — each of those just mentioned, 
 includin<j^ perhaps twenty distinct functions of twenty 
 different parts ; any one of which might have been 
 selected, if we so pleased, and treated of as a se- 
 parate function. But if the enumeration of the se- 
 veral functions be so indefinite, their arrangement 
 is hardly less so ; and accordingly, not only very 
 different heads of functions, but very different ar- 
 rangements of these heads, are to be met with in 
 different authors. By the Father of Medicine, the 
 sum of the functions of the living body was aptly 
 compared to a circle, in describing which we may 
 begin at any point, and set off in any direction we 
 choose ; and there is certainly no point at which we 
 can begin, but it requires a great deal of previous 
 knowledge to render it at all intelligible, and none 
 which can be in any degree exhausted, without in- 
 volving, more or less, the consideration of every other 
 function of the body. One leading ground of dis- 
 tinction, however, between the functions is, that 
 while some of them require only excitability, or ir- 
 ritability in general, more properly speaking, to be 
 called into action, and are carried on without the con- 
 sciousness of the individual, and not only indepen- 
 dently of the will, but even against the will, others 
 require some new properties superadded to general 
 excitability, such as sensibility and susceptibility of 
 thought, and are not only attended with conscious- 
 ness, but subject, in a great measure, to the controul 
 
FUNCTIONS OF ORGANIZED BODIES. 15 
 
 of the will. The former of these have been called 
 collectively the organic functions, since they are 
 common, under some modification or other, to all 
 forms of organized beings, vegetable as well as ani- 
 mal, and include all those to which we have already 
 alluded ; the latter have been called animal func- 
 tions, since they have been presumed to be charac- 
 teristic of animals, and include sensation, thought, 
 and voluntary motion. 
 
 Plants and animals possess, in common, the nutri- 
 tive and reproductive functions, and these two orders 
 taken together, constitute the functions of organic 
 life, including all those concerned in the develop- 
 ment, repair, and maintenance of the individual, 
 and the continuance of the species. These actions 
 vary almost without limit in the wide range of the 
 two organized kingdoms of nature, yet continue to 
 possess throughout certain distinctive features. The 
 end of all the actions of this great order, is directly 
 or indirectly subservient to the conversion into their 
 substance, or the assimilation, as it is technically 
 called, of certain substances ; in j^lants, principally 
 of water and carbonic acid ; and in animals, of sac- 
 charine, oily, and albuminous matters, the products 
 of vegetable or of animal life ; or, finally, of form- 
 ing certain productions or secretions essential to the 
 renewal of the species. The circulation of a nu- 
 tritive fluid, the successive additions to this fluid 
 by nutritive absorbing vessels, the purification of 
 this fluid by exposure to the atmospheric air, the 
 elimination of superfluous or noxious particles from 
 
If) FUNCTIONS OF ORGANIZED BODIES. 
 
 it, and finally, the consolidation of its constituent 
 parts into solids, or their conversion into lubricatin*^ 
 or otherwise useful Inmiours, constitute the leading 
 acts of organic life throughout both organized king- 
 doms of nature. 
 
 To ascribe such acts as these to instinct, appears 
 at lirst sight little short of the height of extrava- 
 gance in speculation ; yet we shall find hereafter, 
 that they have been referred to such a principle, 
 and that by philosophers who are reputed sound 
 thinkers on most occasions ; nor, indeed, is it so 
 easy as one might naturally suppose, to draw the 
 nice line of distinction between the principle on 
 which they depend, and that which is properly re- 
 garded as instinct. 
 
 All the other acts of organized bodies belong to 
 the functions by which relations become established 
 betueen the individual and the world without, and 
 these, therefore, are termed the Functions of Rela- 
 tion, or the relative functions ; and because they 
 hardly exist, or do not at all exist, in plants, while 
 they constitute a prominent feature ui the animal 
 kingdom, they are also called the Animal Functions, 
 or the functions of animal life. 
 
 The relations which can become established be- 
 tween an animal and the external world, are two- 
 fold — relations of knowledge and relations of power. 
 Relations of knowledge are the result of sensibility 
 and the internal acts connected with it, as, in the 
 higher animals, of the five external senses on the 
 operation of the intellect and of the moral feelings : 
 
FUNCTIONS OF ORGANIZED BODIES, 1? 
 
 relations of power, founded on the muscular frame, 
 are the faculty of locomotion, the exertion of strength, 
 the production of the voice, &c. and, under this order, 
 all the acts usually referred to instinct and reason 
 are principally placed. It is often made a question, 
 whether plants do not possess some rudiments of 
 functions of this kind, and whether there are not 
 some animals altogether destitute of them. It will 
 appear hereafter, that some of the phenomena of 
 plants, in the existing state of our knowledge, so 
 closely agree with the condition of this order of 
 functions, and with that of instinct in animals, that 
 no satisfactory circumstance of difference can be 
 pointed out between them. And as to the second 
 question, it may be remarked, that although the 
 evidence of the existence of this order of functions 
 in the very lowest animals be obscure, yet both 
 analogy and all the recent additions to our know- 
 ledge as respects both the habits and structure of 
 such animals, are very favourable to the belief of 
 this order of functions, however limited in degree, 
 being co-existent with the animal kingdom. 
 
 Such, then, is the ordinary general arrangement 
 of the functions of animals, founded on presumed 
 differences in their essential conditions ; the formei 
 class requiring for their display only a general pro- 
 perty common to all living matter, the latter some 
 specific properties in addition ; but there is another, 
 and perhaps a better foundation for such an arrange- 
 ment, in certain general ends, to which more or 
 fewer of the several functions — independently of 
 
18 FUNCTIONS OF ORGANIZED BODIES. 
 
 the individual end to which eacli is subservient — 
 conjointly coiuiuce. These general ends are three ; 
 the ultimate object of every function being either 
 to preserve the individual in a state of life and 
 health, to perpetuate its species, or to maintain its 
 relation with the external world ; and in this view 
 of the matter, the functions have been arranged 
 into the nutritive, the reproductive, and the relative. 
 Of these, the first head includes digestion, circula- 
 tion, secretion, absor})tion, and respiration, all of 
 which extend no farther than the individual, and 
 have no ulterior end ; the second includes genera- 
 tion alone, and is exercised for the sake, not of the 
 individual, but of the race ; and the third includes 
 sensation, thought, and voluntary motion, and fur- 
 nishes us with the only means which we have ol 
 maintaining an intercourse with each other, with 
 nature, and with nature's God. It is sensation 
 and thought which constitute the proper subjects 
 of this work. It will be observed that this arrange- 
 ment does not differ very materially from the pre- 
 ceding ; in fact, it leads to the same order of succes- 
 sion in classifying the functions, but, as founded on 
 less questionable principles, and leading to a more 
 precise nomenclature, it appears to be infinitely 
 preferable to it. Further, it is the best adapted 
 continually to inculcate upon the mind the main 
 purposes of our existence as living and rational 
 creatures ; and to lead us to observe, while investi- 
 gating the phenomena of each function, the admi- 
 
FUNCTIONS OF ORGANIZED BODIES. 19 
 
 rable adaptation of the means to the object, not only 
 individual, but general, for which this function was 
 appointed, and to which, in common with others, it 
 conduces, as subservient, directly or indirectly, to 
 the great end of our being.* 
 
 * See our '•' Introduction to the Study of Nature." Lon- 
 don : 1834. 
 
( 20 ) 
 
 CHAPTER III. 
 
 SKETCH OF THE NERVOUS SYSTEM IN MAN AND 
 THE VERTEBRATE ORDERS OF ANIMALS. 
 
 If the exercise of function in living creatures, 
 imply the operation of a certain power or property 
 on an organ or instrument, the step which should 
 follow such a careftil observation of the phenomena 
 as the case will permit, is an examination of the 
 organ itself under every possible bearing. Through- 
 out every department of physiology, the phenomena 
 fall under notice before any knowledge is obtained 
 concerning the organ itself, or of its connection with 
 the power which calls it into activity. Men ob- 
 served that the use of food renewed their exhaust- 
 ed strength and stimulated them to fresh exer- 
 tions, long before they were enabled to inform them- 
 selves what share in this eflPect was to be assigned 
 to the stomach, what to the liver, what to the bowels, 
 what to the lacteal tubes, what to the heart and 
 bloodvessels, what to the lungs. Nor should the 
 case be very different as respects the operations of 
 instinct and reason, the phenomena of which are 
 
NERVOUS SYSTEM IN MAN. 21 
 
 known but to a limited extent. It is proper, then, 
 to attempt to add to our imperfect knowledge of 
 these subjects by the investigation of the organs on 
 which their operation cannot but be acknowledged 
 to depend ; and it were superfluous to prove that 
 the nervous system must be the organ through 
 which all such acts as rank under these two heads 
 are produced. This system, for example, in man, 
 is not so much one organ as a collection of several 
 organs, each distinguished by special endowments 
 or properties, severally subservient to different 
 functions, or at least to different parts of one or two 
 great functions; while in other animals of the higher 
 orders, its parts vary in number and development 
 nearly in accordance with the degree in which each 
 approaches to man in character ; and further, the 
 lowest tribes, which shew little of the powers cha- 
 racteristic of man and the higher orders, are desti- 
 tute of many parts of the same system. Here, 
 then, is offered a basis for a physiological inquiry 
 into the distinction between the two great princi- 
 ples of action, the consideration of which forms the 
 subject of our work ; and the following brief out- 
 line, which in this place is all that can be offered, 
 will at least indicate the high situation which the 
 comparative anatomy of the nervous system must 
 hold in such an investigation. In it are comprised, 
 first, a short account of the nervous system in man, 
 and the variations from it presented in other mam- 
 mals, as well as in birds, reptiles, and fishes ; and, 
 secondly, a succinct statement of the progress of 
 
22 NERVOUS SYSTEM IN MAN 
 
 its development throughout the avertebrate orders 
 of animals, from the infusoria up to the highest o 
 the mollusca. 
 
 It would be premature to hazard a definition of 
 a nervous system, while the extent of its properties 
 and influence in the animal economy is undeter- 
 mined ; certain descriptive characters, however, 
 belong to it, by which it is usually possible to as- 
 certain its presence, even in animals of the lowest 
 rank in the scale. These are drawn from its ana- 
 tomical structure and disposition, its chemical qua- 
 lities, and partly even from its properties as dis- 
 played in the acts or habits of an animal. 
 
 The elements of a nervous system are, in every 
 known instance, a nervous centre and nerves. A 
 nervous centt-e consists of certain soft, pulpy, inelas- 
 tic parts placed internally in the body of an animal, 
 varying extremely in development, as from a few 
 minute rounded knots connected by similar fila- 
 mentous lines, up to the elaborate complexness of 
 the human encephalon and spinal chord. The 
 nerves are threads composed of the same, or a simi- 
 lar kind of matter, which spread from the centre to 
 the periphery of the body, throughout its extent, 
 connecting all, or nearly all, its parts with the ner- 
 vous centre. 
 
AND VERTEBRATE ANIMALS. 23 
 
 SECTION I. 
 
 THE NERVOUS SYSTEM IN MAN. 
 
 In the vertebrata of Cuvier's system — which we 
 here follow without any material modification — 
 comprising the four great orders of mammals, birds, 
 reptiles, and fishes, the nervous system is made up 
 of an encephalon and spinal chord, together with 
 the ganglionic and other nerves. The encephalon 
 comprises all the nervous parts lodged within the 
 skull, as the brain, the cerebellum, the optic tuber- 
 cles, the peduncles of the brain, the peduncles of 
 the cerebellum, the annular protuberance, and the 
 medulla oblongata. The word brain, then, it is to 
 be remembered, in strict anatomical language, such 
 as ought to be employed even in a popular scientific 
 treatise, excludes several parts contained within the 
 head, and corresponds merely to the word cerebrum, 
 or brain proper. The necessity of the closest at- 
 tention to precision in language must have struck 
 everyone conversant with works of anatomy ; where, 
 notwithstanding the apparent facility of avoiding 
 the use of contradictory terms, owing to the descrip- 
 tive character of the science, opposite views of the 
 acceptation of a word too often create an inextri-, 
 cable confusion. Thus in the arrangement of the 
 parts of the nervous system in vertebrate animals, 
 the subject under consideration, the student dis- 
 
24 NERVOUS SYSTEM IN MAN 
 
 covers a variety of significations among our most ap- 
 proved authors, attached to the term cerebro-spinal 
 axis. Thus the nervous system is often said, and 
 very properly, to be composed o£ the cerebro-spinal 
 system, together with the great sympathetic and 
 other nerves. Here the cerebro-spinal system 
 refers to the whole encephalon or parts within the 
 skull along with the sj)inal chord ; or the cerebro- 
 spinal system is properly made to include the whole 
 nervous centre of such animals. All this is very 
 plain and obvious, but how is the student perplexed 
 when, on opening another work perhaps of equal 
 authority, he sees that the term Axis is substituted 
 for System, while m others the nervous system in 
 the same animals is made to consist of a cerebro- 
 spinal axis, the cerebrum, the cerebellum, the sym- 
 pathetic, and other nerves. 
 
 The term cerebro-spinal axis, is then sometimes 
 employed synonymously with cerebro-spinal system; 
 sometimes to signify the spinal chord, the medulla 
 oblongata, the annular protuberance, and the optic 
 tubercles, or the whole of the nervous centre in 
 vertebrated animals, with the exception of the brain 
 itself and the cerebellum. In this signification it 
 is not less expressive than convenient, and it is 
 therefore made use of in the present sketch ; the 
 few remarks above offered, sufficing to avert any 
 ambiguity. 
 
 In man, then, and in the other vertebrate ani- 
 mals, the nervous system is composed of a cerebro- 
 spinal axis, extending upwards from the lower part 
 
AND VERTEBRATE ANIMALS. 25 
 
 of the vertebral column into the skull, to terminate 
 with the optic tubercles, its highest point ; of the 
 brain and cerebellum superimposed on this vertical 
 column or axis ; together with the great sympathe- 
 tic or ganglionic nerve ; and the other nerves dis- 
 persed over the body. Of each of these parts a brief 
 account must be given. 
 
 Our first lithographic plate, after Paxton, and 
 Fig. 1 represents one side of the brain and spinal 
 chord, shewn by making a section of the cranium 
 and spinal column. In it, a refers to the cere- 
 brum; 6, the cerebellum; c, the medulla oblongata; 
 and c?, the spinal chord, extending from the first 
 cervical vertebra, and terminating at e in the 
 Cauda equina. 
 
 The canal in which the spinal chord, or inferior 
 part of the cerebro-spinal axis, is lodged, is formed 
 behind the vertebral bones by an osseous arch at- 
 tached to each, and extended more or less oblique- 
 ly backwards, constituting the prominences so 
 easily discovered with the finger along the middle 
 of the back. The chord itself is nearly cylindri- 
 cal, being, however, somewhat less in diameter 
 from before backwards than from side to side ; it 
 does not any where much exceed half an inch across. 
 It occupies the two upper thirds of the vertebral 
 column, its lowest point being at the upper part of 
 the loins, where the pia mater, or the membranous co- 
 vering of the chord, together with the origins of the 
 lumbar and sacral nerves, descend into the lower 
 part of the canal, under the name of cauda equina. 
 
26 NERVOUS SYSTEM IN MAN 
 
 from its filamentous appearance, resembling a horse's 
 tail. The chord itself, which does not even nearly 
 fill the canal, ascends to jiass into the skull by the 
 great occipital hole, where it assumes the name of 
 medulla oblongata. It is not of uniform thickness 
 throughout, being considerably enlarged just above 
 its inferior extremity, and again in the neck and 
 upper part of the back or dorsal region : to these 
 enlargements much importance has been attached 
 by physiologists, as will appear in the sequel. The 
 chord is divided into two similar halves, on each side 
 of the middle or mesial plane by two lines, one run- 
 ning along the anterior, the other along the posterior 
 surface ; these are entirely superficial, at least after 
 the full development of the organ ; there are also 
 two collateral grooves on each side, from which the 
 roots of the spinal nerves arise in pairs, thirty on 
 each side, passing out to their destinations from be- 
 tween the long arches of which the canal is formed. 
 Fig. 2, in our first plate, gives a very good poste- 
 rior view of the nervous centre, wath the origin of 
 the spinal nerves. When the chord is traced from 
 the spinal canal into the skull, it is found to re- 
 tain nearly the same form for about an inch, and 
 to proceed nearly in the same vertical direction*, 
 being, however, considerably enlarged towards its 
 upper part, it presents here the appearance of a 
 flattened cone truncated beneath. This is the me- 
 dulla oblongata of anatomists ; and on its surface 
 a further deviation from the cylindrical form is 
 produced by the existence of six eminences : — 
 
AND VERTEBRATE ANIMALS. 27 
 
 two on the anterior aspect looking to the basilar 
 process of the occipital bone, which is above and 
 before the large foramen at the base of the skull, 
 by which the chord enters, are termed the pyramidal 
 bodies, one being on each side of the mesial or mid- 
 dle line ; they are marked in Plate 2, Fig. 1, by the 
 letters z, i ; two placed further back are the olivary 
 bodies, marked h in the same figure ; and other two, 
 which look backwards, are known by the name of the 
 restiform bodies ; these are at the upper and back part 
 of the medulla oblongata, and contribute to the for- 
 mation of the cerebellum. Between these restiform 
 bodies, the posterior line of the spinal chord expands 
 into a triangular depression, called the calamus scrip- 
 torius, so named by Vesalius, who conceived it to 
 have a resemblance to a uTiting pen ; it is the ter- 
 mination of what is called the fourth ventricle of 
 the brain, and is seen in Plate 3, Fig. 1, marked 
 7w. The anterior collateral line of the spinal chord 
 ascends, in like manner, on either side, between the 
 pyramidal and olivary bodies; and the posterior col- 
 lateral line between the olivary and restiform bodies 
 of the side to which it belongs. The medulla ob- 
 longata is regarded as composed of six chords cor- 
 responding to these six eminences, and designated 
 by the same names ; and the spinal chord itself is 
 conceived to be made up of six chords in the same 
 manner, although the evidence, as respects it, is by 
 no means so satisfactory. 
 
 The medulla oblongata passes above into the an- 
 nular protuberance or pons Varolii, well seen in 
 
28 NERVOUS SYSTEM IN MAN 
 
 Plate 2, Fig. 1 , d. Tliis is a considerable eminence 
 on the anterior inferior aspect of the cerebro-spinal 
 axis, convex from side to side, and connected lateral- 
 ly with two large chords, the crura or middle pedun- 
 cles, which pass into the substance of the cerebel- 
 lum. From the anterior part of this eminence two 
 chords also emerge, which expand one into the sub- 
 stance of each hemisphere or superior portions of 
 the brain itself; these last are the crura or pedun- 
 cles of the brain. Immediately above the pons Va- 
 rolii, and continuous with its substance, except in 
 the middle line, where there is a small canal, are the 
 optic tubercles, or tubercula quadrigemina. These 
 four tubercles, seen in Plate 3, Fig. 1, supporting 
 the pineal gland g, are of considerable size, the two 
 anterior being the larger ; their convexity is di- 
 rected upwards, and they constitute the highest part 
 of the cerebro-spinal axis. 
 
 The cerebro-spinal axis, then, as we may now 
 see, is composed of the spinal chords the medulla 
 oblongata, the annular protuberance, and the tu- 
 bercula quadrigemina ; while it is connected with 
 the brain by its peduncles, and with the cerebellum 
 principally by the crura cerebelii or middle pedun- 
 cles, but also by two other pairs of chords called the 
 restiform chords or inferior peduncles, and by the 
 processus ad testes or superior peduncles ; the first 
 are prolongations of the posterior chords of the me- 
 dulla oblongata into the substance of the cerebel- 
 lum, and the other proceed from the two posterior 
 optic tubercles to the cerebellum, supporting be- 
 
AND VERTEBRATE ANIMALS. 29 
 
 tween them a thin medullary lamina termed the 
 valve of Vieussens. 
 
 The cerebellum, which altogether does not much 
 exceed the bulk of an ordinary fist, is placed pos- 
 terior to the medulla oblongata, occupying the in- 
 ferior part of the cavity of the skull behind the great 
 occipital hole. Its inferior, lateral, and posterior 
 surfaces are in contact with the concavity of the 
 occipital bone ; and, although somewhat sulcated, 
 are smooth and nearly convex : its upper surface, 
 which is of a similar character, though more flatten- 
 ed, is covered with a strong and dense membrane, 
 derived from the dura mater-^a membrane of the 
 brain — ^which, being projected forwards nearly in a 
 horizontal direction from a ridge on the inner sur- 
 face of the occipital bone, supports the posterior 
 lobes of the brain, while it covers the whole cere- 
 bellum and separates it from them. This horizon- 
 tal membrane is termed the tentorium ; and, from 
 its inferior surface in the middle line, a process de- 
 scends attached posteriorly and inferiorly to a ver- 
 tical ridge of the occipital bone as far as the great 
 foramen ; this is, from its resemblance to the cut- 
 ting part of a scythe, termed the falx of the cere- 
 bellum ; it is received into a fissure of that organ 
 corresponding to its depth and extent, "and thus 
 divides it, on this aspect, into two lateral hemi- 
 spheres. 
 
 The anterior surface of the cerebellum is deeply 
 notched, corresponding to the medulla oblongata, 
 and constituting with it principally the fourth ven- 
 
 1 
 
'AO NERVOUS SYSTEM IN MAN 
 
 tricle, wliicli in Plate 3, Fig. 1, has, by an oblique 
 section, been laid open, and marked /. The central 
 portion of the org^n is narrow, and rises superiorly 
 into a small conical elongation, the superior vermi- 
 form ])rocess, Plate 2, Fig. 1, e; while between the 
 medulla oblongata and the anterior great notch, the 
 inferior vermiform process is seen at g. Along the 
 circumference of each hemisphere a fissure extends 
 transversely, to the bottom of which we trace the 
 crura or middle peduncles derived from the annu- 
 lar protuberance. The fourth ventricle, or ventricle 
 of the cerebellum, Plate 3, Fig. 1, /, is placed, as 
 above noticed, between the anterior surface of the 
 cerebellum and the posterior surface of the medulla 
 oblongata ; while the roof or upper part is formed by 
 the valve of Vieussens, h, extending from the ver- 
 miform process to the posterior part of the corpora 
 quadrigemina or optic tubercles. This ventricle 
 communicates with the third ventricle of the brain 
 by what is called the aqueduct of Sylvius, already 
 referred to as existing between the annular protube- 
 rance and the optic tubercles. And here it is con- 
 venient to allude to the parts depicted in Plate 2, 
 Fig. 1, which, after Paxton, displays the base of the 
 brain, deprived, however, of the commencements 
 of the encephalic nerves, which are distinctly seen 
 in Plate 4, Fig. 1 : — a, the anterior lobes ; b, the 
 middle lobes ; c, the corpora albican tia ; c?, the pons 
 Varolii ; e, the superior vermiform process ; f, the 
 cerebellum; g, the inferior vermiform process; 
 A, the medulla oblongata — the letter being placed 
 

 AND VERTEBRATE ANIMALS. 31 
 
 on the corpora olivaria ; 2, the corpora pyramidalia ; 
 k, the posterior lobes ; n, the pituitary stem. 
 
 The inferior surface of the brain is divided on 
 each side into three lobes ; the two posterior of 
 these he over the cerebellum, being supported by 
 the tentorium, already described ; the middle and 
 anterior lobes rest on the bones which enter into 
 the formation of the base of the skull. In the space 
 between the lobes, the crura cerebri, already no- 
 ticed as proceeding from the fore part of the annu- 
 lar protuberance, deserve our first attention. They 
 are two rather thick white chords, which diverge 
 from their origin to lose themselves quickly in the 
 brain. In the substance which connects these 
 crura in the first part of their course, is a triangu- 
 lar depression closed by a thin plate, which forms 
 part of the floor of an internal cavity termed the 
 third ventricle of the brain ; but, before tracing the 
 connections of this cavity with the adjacent parts, 
 one or two names belonging to the base of the 
 brain should be explained. The part between the 
 crura, just mentioned, is called the middle perforated 
 plate ; before this are two rounded pea-like bodies, 
 the corpora albican tia, Plate 2, Fig. 1, c, attached to 
 each other and to the commissure of the optic nerve 
 by a soft grey substance called the tuber cinereum, 
 from the centre of which a thin conical tube, of a 
 reddish colour, descends — the infundibulum ; this 
 communicates above m ith the third ventricle, and 
 terminates in the pituitary gland. The commissure 
 
32 NERVOUS SYSTEM IN MAN 
 
 or junction of the two optic nerves is placed just 
 before the parts last described. 
 
 It is not difficult to trace from the third ventri- 
 cle the principal internal parts of the brain. This 
 is situated, as we have said, between the peduncles 
 as they spread out into the substance of the organ ; 
 and as these more immediately form the optic tha- 
 lami, Plate 2, Fig. 2, e, and Plate 3, Fig. 1, c, and 
 the corpora striata, Plate 2, Fig. 2, c, and Plate 3, 
 Fig. 1, 6, so these are adjacent to the third ven- 
 tricle ; its sides, indeed, if we dissect the brain from 
 above downwards, instead of following it, as we are 
 now doing, from below upwards, seem to be formed 
 by the optic thalami. These bodies are firm, white 
 externally, grey within ; their free surface, which is 
 smooth, is in the lateral ventricle, and forms its poste- 
 rior cornu, Plate 2, Fig. 2, b, of which we shall pre- 
 sently speak; their internal surfaces are joined above 
 tlie ventricle, in what is called the soft commissure. 
 The third ventricle, lying under the corpus callosum, 
 Plate 3, Fig. 2, c, communicates with the fourth by 
 the aqueduct of Sylvius, which runs beneath the 
 tubercula quadrigemina, seen supporting the pineal 
 gland in Plate 3, Fig. 1, ^, and with the infundibuium 
 by a canal termed the iter ad infundibuium. It was 
 here that Des Cartes placed the seat of the soul. 
 When the roof of the third ventricle is destroyed 
 by removing the fornix and separating the soft com- 
 missure, it is thrown into one cavity with the lateral 
 ventricles ; and if these ventricles are supposed to 
 
AND VERTEBRATE ANIMALS. 33 
 
 hsive been laid open from above by the removal of 
 the thick substance of the upper part of the hemi- 
 spheres, while the corpus callosum (Plate 3, Fig. 2, c) 
 and septum lucidum (Plate 2, Fig. 2,fyxJ) are taken 
 away, a distinct view of all the more remarkable parts 
 is obtained. 
 
 Our second figure in Plate 2, after Paxton, re- 
 presents a horizontal section of the cerebrum belov/ 
 the inferior surface of the corpus callosum ; a a, the 
 anterior cornua of the lateral ventricles ; b b, the 
 posterior cornua ; c c, the corpora striata ; e e, the 
 optic thalami'; fd, the septum lucidum, extending 
 between the two letters ; ff ff, a. tissue of blood-ves- 
 sels called the choroid plexus. 
 
 In this figure we see anteriorly the two corpora 
 striata c c presenting half their pear-shaped bodies 
 smooth and free, their great ends directed forward, 
 while their small extremities diverge from each 
 other as they proceed backwards, so as to receive 
 between them the optic thalami ; between which, 
 however, and the corpora striata is a narrow ribbon 
 termed taenia semicircularis (Plate 3, Fig. 1 , d). 
 
 Our first figure in Plate 3, also after Paxton, ex- 
 hibits many interesting parts of the brain, which, 
 to describe further in this place, is unnecessary. It 
 shews a horizontal section of the cerebrum, and an 
 oblique division of the cerebellum ; a is the ante- 
 rior part of the corpus callosum; b, the corpus stria- 
 tum ; €, the optic thalamus ; d, the taenia semicir- 
 cularis ; e, the anterior pillars of the fornix cut off 
 at their base ; f, the commissure of the optic tha- 
 c 
 
34 NERVOUS SYSTEM IN MAN 
 
 lami; g, the pineal gland, situated on four eminences 
 termed the corjx)ra quadrigemina ; A, the valve of 
 Vieussens ; k, the arbor vitae, shewn by an oblique 
 section of ;/, the cerebellum ; /, the fourth ventri- 
 cle, terminating in m, the calamus scriptorius ; 
 rt, the cerebellum. 
 
 In the lateral ventricle, and in contact with the 
 optic thalami, on each side, when the fornix is not 
 destroyed, is seen the pes hippocampi or cornu am- 
 monis, being the termination of a line called the 
 taenia hippocampi or corpora fimbriata, being the 
 plaiting of the margin of the processes of the for- 
 nix ; further back is the pineal gland, and next 
 in order are the optic tubercles, to the posterior of 
 which the processus ad testes are seen advancing 
 from the cerebellum. To conceive the state of 
 these parts in their entire condition, we must sup* 
 pose the optic thalami united in the mesial line, or 
 the soft commissure restored ; the corpus fimbria^ 
 tum on each side extended to meet its fellow in the 
 mesial plane, by which junction the fornix, which 
 forms the roof of the third ventricle, is produced, 
 while the septum lucidum, a thin lamina placed ver- 
 tically over the fornix, is viewed as dividing the one 
 lateral ventricle from the other. We must also 
 suppose that no damage has been done to the corpus 
 callosum (Plate 3, Fig. 2, c), under which this septum 
 immediately Ues ; and further, that the thick supe- 
 rior mass of cerebral substance which crowns the 
 hemispheres is produced anew. We shall thus have 
 the appearance presented which the encephalon 
 
AND VERTEBRATE ANIMALS. 35 
 
 exhibits when the calvarium or upper half of the 
 skull has been removed from it, — namely, a grey, 
 convoluted, convex surface, divided by a very deep 
 sulcus, extending from before backwards, into two 
 lateral portions or hemispheres ; into this sulcus or 
 fissure the great falciform process of the dura mater, 
 formed like the falx of the cerebellum, is introduced; 
 and at the bottom is seen the white substance of 
 the corpus callosum, just spoken of. 
 
 When the dissection and demonstration of the 
 brain is commenced from above and continued 
 downwards, the first step is to slice off portions of 
 the hemispheres on a level with the bottom of their 
 division by the falciform process, and Plate 3, Fig. 2, 
 represents the appearances then presented; aaa^ the 
 cortical part of the convolutions, with the fissures 
 between them ; h 6, the medullary part forming the 
 centrum ovale ; c, the corpus callosum. 
 
 A deeper section of the cerebrum exhibits the 
 appearances presented in Plate 2, Fig. 2 ; and a still 
 deeper section is displayed in Plate 3, Fig. 1. 
 
 Such, then, is a rude outline of the parts which 
 compose the nervous centre in man. To those who 
 have not opportunities of seeing a dissection of the 
 brain, some assistance will be afforded towards a 
 more perfect conception of the several parts, by the 
 consideration of the successive steps of their de- 
 velopment in the earliest period of life ; for the very 
 instructive knowledge of which, anatomists are in- 
 '^lebted to the researches of the celebrated Tiede- 
 
.'^ NERVOUS SYSTEM IN MAN 
 
 niann, a professor at Hiedelbcrp:,and a short accounf 
 of which we sliall proceed to lay before the reader. 
 
 Tlie spinal chord is first formed, and the progresjv 
 of its devclo^iment is the more readily discovered, 
 as the posterior part of the long canal in which it 
 is lodged, is, for some time, deficient ; the chord 
 ascends into the skull after a time, and the rudi- 
 ments of the several parts of the encephalon are in 
 succession derived from it. 
 
 At the end of the first month of fetal life, nothing 
 but a limpid fluid is seen in the situation which the 
 nervous centre is afterwards to occupy. About the 
 fifth or sixth week a membranous canal, containing 
 a whitish and almost transparent fluid, extends along 
 the posterior part of the spinal column, expanding 
 in the head into a pouch, composed, to all appear- 
 ance, of several vesicles. Soon after this period 
 the spinal portion extends through the whole length 
 of the vertebral column, composed, at first, of two 
 lateral ribbons of uniform dimensions throughout ; 
 these soon unite at their anterior margin, and some 
 enlargement appears next the skull, into which the 
 chord is soon found to extend. From the lowest 
 part of the chord, within the skull, two thin narrow 
 plates afterwards arise, one on each side, so as to 
 rest upon each other and form an arch over the 
 chord, but without, at this time, becoming united. 
 These two plates are the rudiments of the cerebel- 
 lum ; and the arch beneath represents the fourth 
 ventricle. At the same time, two other plates, im- 
 mediately anterior to these, arise from the chord in 
 
AND VERTEBRATE ANIMALS. 37 
 
 a similar direction, rest on each other, and form an- 
 other arch — the rudiments of the optic tubercles, or 
 tubercula quadrigemina ; the arch beneath is the 
 ventricle which in some animals exists throughout 
 life, but which in man and other mammals becomes 
 reduced to a narrow canal — the aqueduct of Syl- 
 vius. The anterior part of the chord now exhibits 
 the rudiments of the peduncles of the brain ; and 
 from these, which must be regarded as the anterior 
 prolongation of the chord, two rounded bodies, one 
 on each side, afterwards arise, in a manner similar 
 to the origin of the two first pairs of plates, the in- 
 terval between which corresponds to the third ven- 
 tricle of the fully developed brain. Finally, two 
 other eminences, still further forward, appear on a 
 similar plan — the corpora striata, the interval be- 
 tween which, though open for a great part of fetal 
 life, becomes closed before birth. 
 
 Such is the state of the encephalon towards the 
 beginning of the third month of fetal life ; or the 
 parts, the rudiments of which are already formed, 
 are those which constitute the prominent points in 
 the adult, after the upper substance of the hemi- 
 spheres has been removed, the lateral ventricles 
 laid open, and thrown into one cavity with the third 
 ventricle. There is at this time no corpus callosum 
 or other commissure, no fornix, no appearance of 
 the expansion of the chord called the annular pro- 
 tuberance, and no nerve is discoverable. There is 
 no appearance of hemispheres ; although, from the 
 rudiments of the corpora striata, the most anterior 
 
38 NERVOUS SYSTEM IN MAN 
 
 processes of the chord, two productions arise curved 
 from before backwards, whicli are the rudiments of 
 these bodies, after a time to extend backwards, so as 
 to cover the parts already formed in the reversed or- 
 der of that in which they were respectively produced; 
 or, in other words, they are prolonged gradually 
 into a cap or canopy, by which the lateral ventri- 
 cles are completed ; the germ of the corpus cal- 
 losum, by which the two hemispheres, before sepa- 
 rated, are connected, being discovered in the course 
 of the third month. In the same month the ante- 
 rior pillars of the fornix appear ; and, at a later pe- 
 riod, the opposite pillars become joined to consti- 
 tute the fornix itself, by which the third ventricle 
 is separated from the lateral. In the same month 
 the bodies which represent the optic thalami appear 
 to be prolonged downwards to constitute the inftin- 
 dibulum ; the pituitary gland, which is hollow, and 
 comm\micates by the infundibulum with the third 
 ventricle, is also discoverable ; and the rudiments 
 of the corpora albicantia are seen within the pe- 
 duncles of the cerebrum. Before the end of the 
 third month the olfactory nerves, the accessory of 
 Wilhs, and some others, have appeared ; the first 
 are hollow, and their cavity communicates with the 
 third ventricle through the interval then existing 
 between the corpora striata. 
 
 The spinal chord, which, by the junction of the 
 posterior margins of the ribbons of which it was 
 originally composed, has become a tube, begins to 
 shew indications of the two expansions which cor- 
 
AND VERTEBRATE ANIMALS. 39 
 
 respond to the origin of the nerves for the pectoral 
 and pelvic extremities ; the rudiments of the spinal 
 nerves are also discovered. The connection be- 
 tween the cerebellum and optic tubercles, to become 
 the roof of the fourth ventricle, has also appeared. 
 In the fourth month, the eminences on the sur- 
 face of the medulla oblongata are first seen — the 
 pyramidal being discovered before the olivary and 
 restiform. The chord beyond the pyramidal emi- 
 nences swells into the annular protuberance, and 
 the pineal gland appears. At this period, then, the 
 nervous centre has assumed a character very simi- 
 lar to that which it is to exhibit throughout life. 
 
 The nervous centre is composed of two kinds of 
 matter, — the grey or cineritious, and the white or 
 medullary. The grey, in the encephalon, is chiefly 
 placed on the external surface, while the white con- 
 stitutes the substance of the internal parts ; the 
 grey matter, however, alternates with the white in 
 some of the internal parts, as in the thalami and 
 the corpora striata ; and in the spinal chord it is 
 placed exclusively within the tube, which at an 
 early period extended through it. Grey matter is 
 also found in the interior of the parts prolonged 
 upwards from the spinal chord, as in the annular 
 protuberance and crura cerebri. 
 
 The general structure of the nervous matter is 
 fibrous, that is, composed of globules placed in 
 linear rows. This is more particularly acknow- 
 ledged of the white matter, and may be seen in the 
 
40 NERVOUS SYSTEM IN MAN 
 
 spinal cliord as early as the fourth month of fetaJ 
 life. The recent researches of Kaspail and Ehren- 
 berg, support the existence of two distinct kinds of 
 fibres in the white matter, namely, fibres studded 
 with minute knots or globules, and fibres of larger 
 <ize, distinctly tubular, and contained within a gra- 
 nular matter. The first kind are formed in most 
 parts of the brain and cerebellum, as also in the 
 nerves of the special senses, in the sympathetic nerve, 
 and ganglia j those of the latter belong to the base 
 of the brain, to the crura cerebri, the motor nerves 
 of the skull, and to the spinal nerves, particularly 
 to such as are destined to motion. 
 
 The general fibrous nature of the medullary 
 matter, is made obvious by the assistance of such 
 agents as coagulate the albumen which it contains, 
 such as alcohol, dilute nitric acid, a solution of cor- 
 rosive sublimate, or of alum, and by the action of 
 hot oil of turpentine. 
 
 The fibres assume two principal directions, — 
 vertical and horizontal. Vertical fibres are seen 
 in the spinal chord, and they appear to ascend 
 through the medulla oblongata, annular protube- 
 rance, and crura cerebri, into the substance of the 
 brain. From the crura they ascend on the outer 
 side of the optic thalami, and thence diverge in all 
 directions to reach the convolutions of the surface. 
 The thalami and coi^pora striata, are appendages 
 of this vertical set of fibres. The horizontal fibres 
 are formed only in the encephalon ; they belong to 
 the corpus callosum and the other commissures, in 
 
AND VERTEBRATE ANIMALS. 41 
 
 •which they run transversely, and to the fornix and 
 its crura, in which they run antero-posteriorly. 
 The fibrous nature of the cortical or grey matter, 
 is not so distinctly made out. Reil considered it 
 as fibrous, and Raspail and Ehrenberg regard it as 
 differing from the white matter in being more vas- 
 cular, in the fibres being less regularly arranged 
 and interspersed with a granular matter not dis- 
 posed in fibres. The view perhaps which Grant 
 takes of it is not far from correct ; namely, that it 
 consists of a vascular plexus, in the meshes of which 
 is an irregular granular pulp, assuming more of a 
 regular fibrous arrangement as it approaches its 
 junction with the medullary substance. 
 
 The mode in which the convolutions of the sur- 
 face are produced, is most easily understood from 
 the description given of them by Gall and Spurz- 
 lieim, who assume that the vertical fibres of the 
 medullary matter which reach the surface of the 
 hemispheres, are of unequal lengths, some stopping 
 short, others proceeding farther, so that the medul- 
 lary surface, that is, the surface which would be 
 presented, were the external'cortical matter with its 
 membrane simply removed, is indented or compos- 
 ed of numerous points and depressions. Again, 
 they say that this membrane — the pia mater — 
 which is much larger than simply to contain the 
 brain, is covered to one uniform depth with grey 
 matter on its internal surface. This large mem- 
 brane then, they continue, with its lining layer of 
 grey matter, is thrown into plaits or folds which 
 
42 NERVOUS SYSTEM IN MAN 
 
 fill up the depressions of tlie medullary surface, as 
 it spreads over the hemispheres. Little objection 
 can be taken to this description, except that it is 
 not distinctly proved that the prominent medullary 
 points which are introduced between the layers of 
 the grey matter in the convolutions, are prolonga- 
 tions of the vertical fibres of the substance of the 
 organ. 
 
 In the cerebellum, are horizontal fibres, particu- 
 larly in its nucleus ; but the greater part of these 
 connect themselves with the cerebro-spinal axis by 
 three columns on each side already referred to, — 
 the superior, middle, and inferior peduncles. From 
 the nucleus also, fibres spread into the laminae of 
 the surface, where the medullary plates are enclosed 
 between thin layers of grey matter. This disposi- 
 tion of the two kinds of matter which is brought 
 into view by a vertical section of the cerebellum 
 on each side, is seen in Plate 3, Fig. 1 . 
 
 Albumen appears to be the principal chemical 
 constituent of the nervous substance; it affords, be- 
 sides, various fatty matters and cholesterine ; it also 
 contains sulphur ; and, according to Couerbe, phos- 
 phorus, on the amount of which, however, accord- 
 ing to the same authority, its fitness for the main- 
 tenance of its peculiar functions depends. 
 
 We come now to the nerves of the human body. 
 These are arranged into the two great divisions of 
 Cerebro-spinal and Ganglionic. The first of these 
 
AND VERTEBRATE ANIMALS. 43 
 
 are again divided into cranial or encephalic, and spi- 
 nal. With regard to the number of the former 
 there is some ambiguity, but it is sufficient for our 
 purpose to describe nine encephalic pairs, and thirty 
 spinal pairs. 
 
 Nerves are white, and for the most part cylin- 
 drical chords, formed of a more or less considerable 
 number of interlaced filaments connected by cellular 
 tissue. As they recede from their origin, they are 
 divided and subdivided, almost without limit, into 
 more and more minute filaments, until they termi- 
 nate in different ways, either losing themselves in 
 the tissue of organs, or continued by anastomosis 
 into other nervous filaments ; of the latter termina- 
 tion, four varieties have been pointed out : 1 . two 
 branches which belong to the cerebro- spinal system 
 unite ; 2. branches or filaments derived from the 
 cerebro-spinal system unite with others belonging 
 to the ganglionic system ; 3. two branches of the 
 same nerve unite ; 4. branches of a nerve of one 
 side unite in the mesial region with branches of the 
 corresponding nerve of the opposite side. As the 
 nerves recede from the nervous centre, the sum of 
 the united diameters of the several branches, great- 
 ly exceeds the diameter of the trunk from which 
 they are derived ; so that every nerve represents a 
 cone, the apex of which is in the nervous centre, 
 and the base in the organs or parts to which it is 
 distributed. Every nerve is composed of a great 
 number of chords, which again are made up of an 
 indeterminate number of filaments : while both so 
 
44 NERVOUS SYSTEM IN MAN 
 
 frequently anastomose with each otlier, as to form 
 a complete net-work or plexus ; and hence, from 
 this constant interlacing, it follows that, in the pro- 
 gress of a nerve, its chords and filaments are no 
 longer distinct as they were at its origin. The size 
 of the component chords of a nerve is by no means 
 uniform, nor does their number bear any fixed pro- 
 portion to the volume of the nerve itself. A large 
 nerve may consist of many small chords, while a 
 much smaller is made up of a few large chords ; or, 
 as the pneumo-gastric, it may be composed of only 
 one grooved chord. The proper sheath or mem- 
 brane of the nerves is called their neurilema ; the 
 olfactory nerve, however, has none, and it is only 
 found round the optic nerve after its commissure. 
 
 The encephalic or cranial nerves were formerly, 
 with less propriety, called cerebral ; for they are 
 not strictly cerebral, inasnmch as all of them have 
 their origin in the cerebro-spinal axis, or in that 
 part within the skull on which the cerebrum and 
 cerebellum are superimposed. This is seen in our 
 Plate 4, Fig. 1, after Milne-Edwards, which, though 
 somewhat fanciful and incorrect, represents, suffi- 
 ciently well for our purpose, a vertical section of the 
 brain and cerebellum, with the medulla oblongata, 
 and encephalic nerves. It is needless to add, that 
 A is the anterior, B the middle, and C the posterior 
 lobe of the brain ; D the cerebellum, and E the 
 spinal chord ; / is the divided corpus callosum, 
 which, as we already know, is situated at the bot- 
 tom of the sulcus, separating the two hemispheres, 
 
AND VERTEBRATE ANIMALS. 45 
 
 and beneath which the lateral ventricles are'placed ; g 
 represents the optic lobes. In the following brief de- 
 scription of the nerves, we shall refer to this figure. 
 
 The first pair (1) is olfactory passing through 
 a perforated plate in the fore-part of the base of 
 the skull, to supply the organ of smell. 
 
 The second pair (2), traced from the optic lobes 
 (^), or highest part of the cerebro- spinal axis, and 
 connected with the optic thalami, unite in the base 
 of the skull to form the optic commissure, from 
 which two nerves again proceed, one into each or- 
 bit, to spread into the retina, or proper seat of vi- 
 sion in the eye. The two first pairs, then, are 
 nerves of special sensibility. 
 
 The nerves of the third part arise near the inner 
 edge of the peduncles of the cerebrum, close to 
 their origin from the annular protuberance ; their 
 filaments are distributed to the muscles moving the 
 eye-ball, and a small portion is traced to the eye- 
 ball itself, which probably reaches the iris, the 
 moveable curtain of which the pupil is the centre. 
 In the plate, the third pair is seen arising before 
 the optic nerve, and distributed as above. 
 
 The nerves of the fourth pair (4) arise close to 
 the posterior optic tubercles, at the outer margin 
 of the valve of Vieussens ; and its origin is seen in 
 the plate immediately below that of the last men- 
 tioned nerve. It is the smallest of the encephalic 
 nerves, and distributed to a single muscle of the 
 eye-ball. This nerve has long been supposed to 
 be concerned in movements of the eye expressive 
 
46 NERVOUS SYSTEM IN MAN 
 
 of mental emotion, and lience it has been termed 
 the pathetic and amatory nerve ; more recently Sir 
 Charles Bell has named it the respiratory of the eye. 
 This name refers to the same property, as it is a 
 part of his theory, that all the nerves of expression 
 take their origin from what he terms the respira- 
 tory tract of the nervous centre. Under this view, 
 then, the third pair are nerves of general motion, 
 while the fourth pair are nerves of special motion. 
 The fifth pair (5) is the largest and most re- 
 markable of the encephalic nerves. It is a symme- 
 trical nerve, belonging to the same order as the 
 spinal ; that is, it has two roots, or rather fasciculi 
 of roots, one appropriated to sense, the other to 
 motion. The first set arise from the angle between 
 the annular protuberance and the crura of the ce- 
 rebellum ; the second from the pyramidal chords in 
 the substance of the same protuberance. The first 
 forms a ganglion, called the Gasserian, with which 
 the other has no direct connection. From this 
 ganglion three nerves arise, the highest, or ophthal- 
 mic (5 a), passes into the orbit to supply the eye- 
 ball, the membrane of the nose, and the forehead ; 
 the portion of this nerve designed for the eye-ball 
 forms a minute ganglion, termed the lenticular, with 
 which a branch of the third pair is connected be- 
 fore it is distributed to the eye, where it appears to 
 be spent principally on the iris. The second por- 
 tion of the fifth pair, the superior maxillary (5), is 
 transmitted to the face, through a hole immediately 
 below the eye ; it is in this nerve that tic doloureux 
 
AND VERTEBRATE ANIMALS. 47 
 
 has its most frequent seat. These first two portions 
 of the fifth pair being derived exclusively from the 
 posterior set of roots, are nerves of sense only ; for 
 when they are divided in living animals, no loss of 
 motion, but only loss of sensation follows. The 
 third nerve, derived from the ganglion of the fifth 
 pair, unites with the anterior fasciculus of roots which 
 has not entered the ganglion, to constitute the in- 
 ferior maxillary nerve (5 b), which sends branches 
 to the muscles moving the jaw, forms the gustatory 
 or nerve of taste in the tongue, and the dental 
 nerves of the teeth in the lower jaw. When this 
 nerve is divided, the power of moving the jaw on 
 the side on which it has been cut is lost. 
 
 To shew the double origin and distribution of 
 this remarkable nerve, we refer to Plate 4, Fig. 2, 
 for which we are indebted to our friend Dr Handy- 
 side, a well-known and eminent teacher of anatomy 
 in the Edinburgh school. The drawing is highly 
 illustrative; and the reader will find it fully describ- 
 ed in the references to our plates at the beginning 
 of the volume. 
 
 The sixth pair (6) are motor nerves, arising along 
 the sides of the pyramidal eminences of the medulla 
 oblongata, and becoming free at the groove between 
 it and the annular protuberance. They supply that 
 muscle of the eye-ball which draws the organ out- 
 wards. 
 
 The seventh pair (7) is more complex ; it con- 
 sists of two portions, the first a nerve of special sense, 
 the auditory or portio mollis of old authors going to 
 
48 NERVOU3 SYSTEM IN MAN 
 
 to the labyrinth of the car; the other the portio dura> 
 a respiratory nerve, in Bell's system, and certainly 
 a motor nerve, for the face ; the first portion arises 
 over the restiform body, in what is called the floor 
 of the fourth ventricle, so it must be regarded as 
 coming from the posterior columns of the cerebro- 
 spinal axis; while the second portion, the true facial, 
 becomes free just behind the posterior edge of the 
 annular protuberance a little to the outside of the 
 origin of the sixth pair, and somewhat anterior to 
 the origin of the auditory. It is, however, still 
 uncertain whether it should be ascribed to the an- 
 terior or middle columns of the axis, the latter of 
 Mhich Bell considers as in the respiratory tract. 
 
 The eighth pair is very complicated ; it consists, 
 according to the most usual arrangement, of three 
 parts ; one which comes upwards from the side of 
 the cervical portion of the spinal chord into the 
 skull, to accompany the other two portions which 
 are altogether encephalic outwards, to be distributed 
 on two muscles concerned in the elevation of the 
 ribs in the act of inspiration ; this is the accessory 
 nerve of Willis, termed by Bell the respiratory of 
 the neck; 12 in our plate gives some idea of it. 
 The least important of the encephalic portions, 
 named glosso-pharyngeal (9), destined as its name 
 indicates for the tongue and adjacent parts, arises 
 from the groove between the restiform and olivary 
 eminences immediately above the origin of the pneu- 
 mo-gastric or par vagum (10), the most import- 
 ant portion of the eighth pair, supplying the 
 
AND VERTEBRATE ANIMALS. 49 
 
 pharynx, larynx, windpipe, gullet, lungs, and sto- 
 mach, and communicating with the nerves of the 
 heart and those of the digestive organs in general. 
 Much difficulty still attends the determination of the 
 true theory of this nerve : Bell ranks it among the 
 respiratory. 
 
 The ninth pair (11) is plainly a motor nerve, 
 and its origin corresponds with this circumstance, 
 being derived from the groove between the olivary 
 and pyramidal bodies. It supplies the tongue, in 
 which it is the nerve of motion, and also some of 
 the muscles concerned in deglutition. 
 
 Although in the above sketch we have made but 
 nine pairs of encephalic nerves, many anatomists 
 have made more ; some dividing our seventh pair 
 into two distinct pairs, and others our eighth pair 
 into three pairs. 
 
 The spinal nerves, as already noticed, amount to 
 thirty pairs ; they arise, as is seen in Plate 1 . Fig. 
 2, from the sides of the spinal chord by two roots, 
 the anterior being smaller than the posterior. Each 
 root is formed by a number of filaments, distinct at 
 their commencement ; they traverse a space of the 
 spinal chord, before they issue, by the intervertebral 
 holes in which they unite, and before which union 
 the posterior root has formed a minute hard enlarge- 
 ment or ganglion of a grey colour and oval form. 
 From these nerves are formed those which supply 
 the diaphragm or midriff, an organ essential to the 
 function of respiration, the upper extremities, the 
 muscles of the back and abdomen, and the lower 
 
50 NERVOUS SYSTEM IN MAN 
 
 extremities ; besides which, they communicate with 
 the ganghonic nerves wliich descend on the fore 
 part of either side of the spinal column. 
 
 The ganglionic system next arrests our atten- 
 tion. Ganglia are minute nervous centres from 
 which filaments proceed to anastomose with neigh- 
 bouring nerves, or to become lost in the sub- 
 stance of adjacent organs. They are met with in 
 the trunk, back, and head only, the extremities ex- 
 hibiting no traces of them. They communicate 
 with each other throughout, and all present the 
 same definite character. Their general appearance 
 is as delineated in Plate 5, Fig. 1 ; although they vary 
 considerably in form and magnitude, they always 
 appear as reddish or greyish bodies deeply situated 
 in the cellular tissue, and possessed of no particular 
 envelope ; they are highly vascular, and believed to 
 be composedof a multitude of minute filaments; they 
 are hardened by moderate boiling. The nervous 
 filaments which proceed from the ganglia commu- 
 nicate with the cerebro-spinal system of nerves very 
 Ireely, connect the ganglia with each other, and fol- 
 low the arterial system throughout all its ramifica- 
 tions. 
 
 The largest and most remarkable ganglion is the 
 semilunar, situated on the fore part of the aorta or 
 great arterial trunk, in the region of the stomach. 
 It is rather, however, a collection of ganglia, than 
 a single ganglion, the number of its parts being va- 
 riable. There are always two principal portions, a 
 
AND VERTEBRATE ANIMALS. 51 
 
 right and a left, and these two are always much 
 larger than the others, which are less uniformly 
 present. These several portions are united by a 
 great number of nervous filaments, and the same 
 filaments in their passage anastomose with each 
 other. This collection of ganglia and filaments are 
 properly called the solar plexus ; from it a plexus of 
 nerves is transmitted to the liver, another to the 
 spleen and pancreas, and a third, joining some 
 branches of the pneumo-gastric nerve, to the sto- 
 mach. From the lower part of the solar plexus fila- 
 ments proceed, which, joining other filaments de- 
 rived from the hepatic and splenic plexuses, descend 
 to constitute the superior and inferior mesenteric 
 plexus, the renal plexus, and the hypogastric plexus, 
 from which the bowels, kidneys, and organs of the 
 pelvis are supplied. Plate 5, Fig. 2, exhibits, after 
 Paxton, some of the principal nervous ganglia and 
 plexuses of the thorax and abdomen on the left side, 
 and the pneumo-gastric nerve on the same side ; 
 a «, being thoracic ganglia ; b, the pneumo-gastric 
 nerve ; c, a branch of the former, called the inferior 
 laryngeal or recurrent, curving round the arch of 
 the aorta ; c?, the oesophageal plexus ; e, the pericar- 
 dium ; / the lungs ; g, the diaphragm ; h, the 
 spleen ; e, the stomach — the two last named or- 
 gans being turned to the opposite side to shew 
 the distribution of the nerves ; k is the kidney ; 
 /, the abdominal aorta ; m, the semilunar gan- 
 glion and solar plexus, the latter radiating to all 
 the divisions of the aorta ; n, is the splenic plex- 
 
52 NERVOUS SYSTEM IN MAN 
 
 US ; o, the pancreas ; p, j), p, the lum])ar ganglia ; 
 7, the obturator nerve ; and r, the pulmonary plexus. 
 Another division of tlie ganglionic system, is the 
 great sympathetic nerve. The chain of ganglia 
 which, with their connecting filaments, constitute 
 this nerve, extends from the base of the skull, on 
 each side, along the fore and lateral parts of the 
 vertebral column, to the extremity of the sacral 
 bone. In the neck there are three ganglia ; in the 
 back twelve ; in the loins five, and lower down four 
 or five called sacral ganglia ; finally, on the upper 
 part of the coccygeal bone, or the lowest of the 
 spine, the filaments, from each side, unite in a small 
 ganglion called the ganglion impar. The filaments 
 from the cervical ganglia communicate with the 
 spinal nerves of the neck, and, moreover, constitute 
 the cardiac nerves, which unite to form a ganglion 
 and plexus near the root of the aorta, from which 
 the nerves proceed along with the coronary or pro- 
 per nourishing arteries of the heart to be distributed 
 in the substance of the organ. From five or six of 
 the inferior dorsal ganglia, a nerve on each side arises 
 to descend with the aorta into the abdomen, and 
 to communicate M'ith the great semilunar ganglion 
 already described. From the lumbar and sacral 
 ganglia, branches proceed to connect themselves 
 with the several abdominal and pelvic plexuses de- 
 rived from the great solar plexus. From the supe- 
 rior cervical ganglion two rather large, soft, reddish 
 filaments ascend into the canal of the internal ca- 
 rotid artery, around which they form a plexus send-- 
 
AND VERTEBRATE ANIMALS. 53 
 
 ing filaments to several parts ; one of these unites 
 with the vidian nerve derived from the second por- 
 tion of the fifth encephalic pair ; several unite with 
 the sixth encephalic pair ; and another goes to join 
 the ophthalmic portion of the fifth and its nasal 
 branch ; by means of this filament a communication 
 is established between the first cervical ganglion 
 and the lenticular ganglion of the orbit. 
 
 Such is a slight outline of this important ramifi- 
 cation of the nervous system. 
 
 It is not compatible with the design of this trea- 
 tise to enter into a detailed account of all that is 
 plausible, probable, or ascertained with respect to 
 the function of the system, a sketch of which has 
 now been exhibited ; yet it will not be out of place, 
 with a view to the immediate object before us in 
 this chapter, namely, the bearing of the anatomy of 
 the nervous system on the difference between in- 
 stinct and reason in animals, to notice a few of the 
 more remarkable facts in evidence of the special 
 endowments of particular parts of the nervous sys- 
 tem, or of the connections which have been estab- 
 lished by observation and experiment between the 
 existence of certain forms of development and the 
 exercise of corresponding acts or offices in the ani- 
 mal economy. It is true that all or nearly all of 
 these facts have not been ascertained by direct ex • 
 periments upon the human body, but they are just- 
 ly inferred to be true of it, because true of animals 
 of a similar character. There is no just ground for 
 
r>4 NERVOUS SYSTEM IN MAN 
 
 objecting to connect these with the nervous sys- 
 tem of man ; nor is any thing sought in the present 
 case in placing them here rather than elsewhere, 
 but the simple convenience of arrangement. 
 
 Although many metaphysicians have delighted to 
 inculcate that the nervous system should be regard- 
 ed as one organ, spreading indeed over the body, 
 yet simultaneously affecting in all its parts ^^ hen any 
 function is exercised ; yet the very opposite cha- 
 racters of the two acts in which the nerves are least 
 equivocally concerned, namely, sensation and mo- 
 tion, had led others at an early period to conjecture 
 that the nerves of sensation must be different in 
 substance from those of motion, although, as they 
 imagined, both might be bound up in the same 
 sheath. The truth of this conjecture has been 
 verified in our own day principally by the researches 
 of Sir Charles Bell ; and without entering upon the 
 intricacies of the subject, or touching on certain 
 points still under controversy, let it suffice to say, 
 that two distinct sets of nerves have been establish- 
 ed as concerned respectively in motion and in sen- 
 sation. Here, then, we have the first step in as- 
 signing different functions to different portions of 
 the nervous system ; and in respect to which it 
 should be noticed, that the irritation of certain parts 
 of the nervous centre in the living body is uniform- 
 ly followed by muscular contractions, while no such 
 effects attend the irritation of certain other parts. 
 Thus the irritation of the cerebro-spinal axis pro- 
 
A-ND VERTEBRATE ANIMALS. 55 
 
 duces such contractions, while that of the brain 
 proper and the cerebellum does not give rise to 
 any such effect, unless in so far as irritation of the 
 axis may accompany it. Again, it is established 
 by numerous experiments that no part of the ner- 
 vous centre, higher than the optic tubercles, is 
 essentially concerned in sensation, that is, that nei- 
 ther the brain proper n(M- the cerebellum is essen- 
 tial to that act. It is proved also, that, at least in 
 many animals, the optic tubercles are the only parts 
 of the encephalon essential to the sensations con- 
 cerned in vision. It appears also, that, while sen- 
 sation belongs to the cerebro-spinal axis, or rather 
 to certain parts of it, the recollection of sensations, 
 the association of them, and other intellectual acts 
 are essentially dependent on the brain, all trace of 
 such operations being lost when the cerebral lobes 
 are removed, although the evidence of the continu- 
 ance of sensation be still perfect. The destruction 
 of the cerebellum does not interfere with the power 
 of sensation or with intellectual acts in general, but 
 is followed by the loss of the power of regulating 
 the motions of the limbs in particular ; or the cere- 
 bellum appears to be the organ through which an 
 animal recollects muscular sensations, as the cere- 
 brum is subservient to the recollection of other 
 sensations and mental acts in general. 
 
 But it is time to close this brief illustration of 
 the separate endowments of different parts of the 
 nervous system, and the subject may be properly 
 broken off with a reference to the singular anoma- 
 
56 NERVOUS SYSTEM IN MAN 
 
 lies of volition jiroduced by the section of certain 
 parts of the encephalon. Thus, when the bands of 
 medullary matter, passing from the peduncles of 
 the brain through the corpora striata to tlie hemi- 
 spheres, are divided in the living body, the ani- 
 mal acquires an irresistible tendency to move 
 forwards. Again, when the cerebellum is cut 
 through, the tendency is to motion backwards ; 
 and when the middle j^eduncle of the cerebellum 
 is cut on one side, the animal rolls over to the same 
 side. These and many other analogous effects 
 inust depend on the usual influence of the cere- 
 brum or cerebellum, originating in recollected sen- 
 sations or other mental operations, such as produces 
 muscular motions through the medium of the cere- 
 bro-spinal axis, being interrupted and disturbed by 
 the lesion which has taken place. 
 
AND VERTEBRATE ANIMALS. 57 
 
 SECTION II. 
 
 THE NERVOUS SYSTEM IN VERTEBRATE ANIMALS BELOW 
 MAN. 
 
 What Aristotle believed to be the principal dif- 
 ference that distinguishes the nervous system of 
 man from that of the other vertebrate animals, the 
 greater proportionate size of the brain compared 
 with the bulk of the body, is found, although gene- 
 rally correct, to be liable to some exceptions. Thus 
 among mammals, some of the quadrumana, parti- 
 cularly a few of the sapajous or American apes, 
 have, in the adult state, a cerebrum as great in 
 comparison to the bulk of their bodies, as the brain 
 of the human infant to its body, which is consider- 
 ably beyond the proportion in adults. Again, the 
 brain of one species of dolphin among the cetacea, 
 compared with its body, exceeds the proportions of 
 the human brain. Exceptions still more remark- 
 able, are found among birds, principally, if not ex- 
 clusively, among the smaller species. Thus in the 
 house-sparrow, the proportionate size of the brain 
 equals its proportion in the infant state of man ; 
 while in the canary bird it considerably exceeds it. 
 It does not appear that any exceptions of this kind 
 occur among reptiles and tishes. Notwithstanding 
 these exceptions, which are nearly confined to small 
 animals, — in which, as a rule, the brain is propor- 
 tionally more developed than in large, — the gene- 
 rally greater comparative size of the human brain 
 
58 NERVOUS SYSTEM IN MAN 
 
 must be regarded as an important circumstance of 
 difference in our reasonings witli respect to the 
 nervous system. A distinction, to which no excep- 
 tion has yet been stated, was pointed out by Soem- 
 mering, namely, that the brain of man bears a 
 greater proportion to the bulk of his nerves than 
 the brain of all other animals to the bulk of theirs. 
 This fact at once marks out the superior develop- 
 ment of the brain as the characteristic of man, since 
 the relation of the several parts of the same system 
 affords a far more just standard of measurement 
 than the size of the body — the aggregate of many 
 systems, the development of each of which, in dif- 
 ferent animals, is influenced by many circumstances 
 of an accidental nature. 
 
 The cerebrum of man is estimated at ^^th, <j jth, 
 ^Qth, in the progress of life from birth, and finally, 
 in the adult at 5^5 th of the weight of his body ; 
 and the cerebellum is said to equal ^th of the mass 
 of the cerebrum, while, with two singular excep- 
 tions, the cerebrum is much more developed, com- 
 pared to the cerebellum, than in other animals. 
 Thus in the dog the cerebellum is ^th of the bulk 
 of the cerebrum ; in the cat ^th ; in the sheep 
 ith ; in the beaver id ; and in the mouse ^th. The 
 ox, on the contrary, has a cerebellum bearing the 
 same relation to its cerebrum as the two organs 
 bear to each other in man ; and there is further a 
 very extraordinary and inexplicable anomaly in the 
 saimiri, an American sapajou, in which the brain is 
 to the cerebellum as 14 to 1, or the cerebellum is 
 
AND VERTEBRATE ANIMALS. 59 
 
 but J:jth of the bulk of the cerebrum. In the rest 
 of the quadrumana, the cerebellum is more deve- 
 loped in comparison of the cerebrum, as respects 
 man, just as it is in other tribes of animals. 
 
 The cerebro-spinal axis, taken as a whole, is 
 much more developed proportionally in other ani- 
 mals than in man. Thus the spinal chord is uni- 
 formly of greater size compared to the cerebrum, 
 and the medulla oblongata is also more developed 
 in general ; an exception, however, has been pointed 
 out in this respect in the dolphin. The annular 
 protuberance is, however, more developed in man, 
 or it is developed in the same ratio as the cere- 
 brum, while on the contrary the optic tubercles 
 are least developed in man of all the vertebrata. 
 In all mammals these are four in number, the two 
 anterior being of greater size in herbivorous tribes, 
 the two posterior in the carnivorous ; and in man 
 the anterior but slightly surpass the posterior in 
 magnitude. In the human fetus, and in the fetus of 
 mammals in general, there are but two optic tuber- 
 cles, from the absence of the transverse groove. 
 At this period they are ventricular, owing, as we 
 have remarked, to the great size of the opening 
 which is to become the aqueduct of Sylvius. In 
 birds, reptiles, and fishes they remain throughout 
 life in this state, being only two in number and 
 ventricular. In fishes they constitute almost the 
 whole encephalon, and were till lately mistaken 
 for the optic thalami. In reptiles their proportional 
 development is somewhat less than in fishes ; 
 
f)0 NERVOUS SYSTEM IN MAN 
 
 while it is greater in birds. In birds it is greater 
 than in mammals ; while among the latter it is least 
 in man. They are developed then in the inverse 
 ratio of the cerebrum ; but in the direct ratio of the 
 x>ptic nerves. 
 
 Before leaving the cerebro-spinal axis, certain 
 j)eculiarities of form, connected with the existence 
 or absence of extremities and of a tail, must be no- 
 ticed, as illustrative, in a remarkable manner, of the 
 extension of development in the nervous system, 
 with extension of function and vice versa. It has 
 been already observed, that the spinal chord exhi- 
 bits two enlargements, one near its termination, cor- 
 responding to the origin of the nerves of the pel- 
 vic extremities ; the other, at the lower part of the 
 neck and upper part of the dorsal region, corres- 
 ponding to the origin of the nerves of the pectoral 
 extremities. 
 
 It has been observed that human monsters, born 
 without legs or arms, do not exhibit these enlarge- 
 ments. In those mammals which have no pelvic 
 extremities, as the cetacea, there is no posterior 
 enlargement on the spinal chord. In those birds 
 which live on the earth, as our domestic fowls, those 
 which climb trees, and more particularly in the os- 
 trich, the posterior enlargement much exceeds the 
 anterior in magnitude ; while, on the contrary, in 
 birds which are much on the wing, the anterior en- 
 largement is of surprising size. In the ophidean 
 reptiles, or those destitute of extremities, the spinal 
 jchord does not swell at all in this manner. In the 
 
AND VERTEFRATE ANIMALS. 61 
 
 krvaof the frog, — the tadpole, — the spinal chord is 
 of uniform thickness, until the metamorphosis into 
 the perfect state commences, and limbs begin to 
 sprout out, when these enlargements arise. In fishes 
 the enlargement in this part of the nervous cen- 
 tre is less conspicuous, but corresponds to the place 
 of the fins. In those which have no ventral fins 
 or the apodes of naturalists, there is no enlarge- 
 ment ; in the jugular fishes, or those which have 
 the ventral fins placed before the thoracic, the en- 
 largement is in the cervical portion of the spinal 
 chord ; in the pectoral fishes, in which the ventral 
 fins are directly under the thoracic, the enlargement 
 is in the dorsal or middle region of the chord ; and 
 in the abdominal fishes, in which the ventral fins 
 are behind the thoracic, the enlargement is in the 
 abdominal region of the chord. In the flying-fish, 
 in which the pectoral fins are greatly developed, 
 there are enlargements of the spinal chord corres- 
 ponding in magnitude and number to the detached 
 rays of the fins ; while in the electric fishes there is 
 a considerable enlargement, corresponding to the 
 nerve which supplies the electrical apparatus. 
 
 •Again, in the human fetus, before the third 
 month, the spinal chord is extended to the extre- 
 mity of the coccygeal bone, and at that time this 
 bone is prolonged into a true tail ; after this period 
 the chord becomes suddenly shortened, so as to ter- 
 minate in the upper part of the lumbar region ; and 
 when this change takes place, the coccyx become> 
 reduced in dimension by absorption, and the can- 
 
62 NERVOUS SYSTEM IN MAN 
 
 dal prolongation disappears ; if, liowever, from any 
 accidental cause, interiering with the energy of de- 
 velopment at this period, the shortening of the 
 spinal chord should be arrested, then the infant is 
 born with a tail, as has been observed in many in- 
 stances. 
 
 In bats the same thing occurs ; they have at first 
 a tail, which disappears as the spinal chord rises in 
 the canal. Further, a similar law is observed as 
 regards animals with long tails as compared with 
 those that have short tails ; the more the spinal 
 chord rises in the canal, the shorter the tail, — re- 
 maining prolonged in such as have long tails through- 
 out life. Sometimes the frog retains the tail which 
 characterises it in the larva state ; and, when this 
 is the case, it is found that the spinal marrow has 
 failed to ascend in the canal, in accordance with the 
 ordinary law which regulates the transition to the 
 perfect condition. 
 
 There is thus, then, in these respects, the most 
 obvious connection between the particular develop- 
 ment and the particular action which belongs to the 
 animal ; nor is it to be doubted but that an analo- 
 gous correspondence exists between the develop- 
 ment of the brain and cerebellum, and the functions 
 to which they are subservient, although this part of 
 the subject we are by no means able to pursue in a 
 manner so satisfactory. No sufficiently just standard 
 of comparison, either as respects the degree of in- 
 telligence and instinct possessed by different ani- 
 
AND VERTEBRATE ANIMALS. 63 
 
 mals, or as respects the relative development of cer- 
 tain parts of their nervous system has yet been esta- 
 blished. The actual size of the parts composing 
 the brain and cerebellum, or their size as compared 
 to the bulk of the body, is evidently a very rude 
 kind of measurement ; and a perfect knowledge of 
 the relative size of all the parts in every animal is 
 still far from being attained, although the value of 
 what has been already ascertained gives promise of 
 the greatest success by this species of investiga- 
 tion. 
 
 While the size of the cerebrum, as compared to 
 the bulk of the body, varies very much in mammals 
 and birds, without any distinct reference to the de- 
 gree of intelligence in the animal, still the connec- 
 tion between its development, even as estimated by 
 this imperfect standard, is supported by some facts 
 remarked of these two orders, and much more uni- 
 formly by what is observed of the two other orders 
 of the vertebrata, in which the small development 
 of the cerebrum is not more remarkable than their 
 obvious inferiority in intelligence. Thus, to take 
 a few examples illustrative of both positions here 
 referred to : — the brain of the quadrumana varies 
 in different species from g^th to y^jth of the bulk 
 of the body ; in the bat it is g^^jth ; in the mole g^^th ; 
 in the bear i^^th ; in the dog from Jyth to j^jth, 
 in different varieties ; in the fox jj^jth ; in the wolf 
 g^oth ; in the beaver jg^th ; in the rat y^^th ; in 
 the mouse ^g^d; in the elephant j^o^h ; in the 
 wild boar ^^^th ; in the ox a^o^h ; in the sheep 
 
64 NERVOUS SYSTEM IN MAN 
 
 ^}ySt to T^ijth ; in the horse Too^h ; in tlie ass 
 j^^th ; in the dolphins ^V^h, ^^^th, ^'^th, jiirth, in 
 different species ; in the sparrow ^^^^th ; in the ca- 
 nary bird y'yth ; in the eagle Tj^n^h ; in the goose 
 j^jjth. But among reptiles mark the prodigious 
 change ; in the turtle jjyVs^h ; in the tortoise 
 jj^^th ; though in the frog as high as yt^^^^ 5 ^^^<^ 
 in the shark ^^^jyth ; in the pike y^oj 5 ^^ the 
 tunny y^^joth- 
 
 According to Serres, the degree in which the 
 crura cerebri diverge anteriorly to the annular pro- 
 tuberance, together with the size of the third ven- 
 tricle and the development of the optic thalami, 
 are the best criteria of the amount of intelligence 
 possessed by an animal. If this rule prove to be 
 correct, it will most probably be found to resolve 
 itself into some other less obscure character. 
 
 The particular parts, then, of the brain which ap- 
 peal* to be most developed in man are the convolu- 
 tions of the hemispheres, the corpus callosum, the 
 corpora striata, and the optic thalami. The fornix 
 and pes hippocampi attain their highest develop- 
 ment in some of the mammals, but not in man. 
 The convolutions exist only in some of the highest 
 orders of the vertebrata ; the corpus callosum is pe- 
 culiar to mammals ; the lateral ventricles do not 
 exist except in the same order of animals, and no 
 animal except man and the dolphin {Delphinm 
 Delphis\ is known to have three horns, as they are 
 barbarously termed, in these cavities. The corpora 
 striata are developed in the direct ratio of the cere- 
 
AND VERTEBRATE ANIMALS. 65 
 
 brum itself, or are greater in man and the higher ani- 
 mals ; and there are none in birds, reptiles, and fishes. 
 The optic thalami are developed in the direct ratio 
 of the brain in mammals, birds, and reptiles ; in 
 fishes they do not exist. The fornix is not found 
 in reptiles and fishes ; it is deficient also in most 
 birds ; while in some, as in the parrots and eagles, a 
 rudiment of it is discovered. In mammals, on the 
 contrary, it is constant, and most developed in the 
 Rodentia, as in the rabbit, squirrel, and beaver ; it 
 is less developed in the Ruminantia, still less in the 
 Carnivora, Quadrumana, and Man. The cornu 
 ammonis does not exist in birds, reptiles, or fishes ; 
 and among mammals its development obeys the 
 same law as the fornix. The pineal gland is found 
 in all the vertebrate animals, — mammals, birds, 
 reptiles, and fishes. 
 
 The cerebellum consists in fishes of two distinct 
 portions, — a middle lobe, connected with the optic 
 tubercles, and lateral layers, proceeding from, or 
 continuous with, the restiform bodies. These two 
 portions are insulated and disjointed throughout the 
 whole order of fishes. The same are the elements 
 of the cerebellum in the higher orders of animals"; 
 the superior vermiform process, connected in all 
 with the optic lobes, represents the first, while the 
 hemispheres continuous with the restiform bodies 
 represent the others. These two portions of the 
 cerebellum should be regarded as distinct, even 
 when continuous the one with the other, as in the 
 
 WNlVERSiTY 
 
i)C) NERVOUS SYSTEM IN MAN. 
 
 liigliLT orders ; they are developed uniformly in the 
 inverse ratio of each other. 
 
 It would he tedious to enter on the variations of 
 the nerves in the different orders of vertebrate ani- 
 mals; the general plan on which they are distributed, 
 both as respects the cerebro-spinal and ganglionic 
 systems, is the same, the varieties ])eing dependent 
 on the variations in the existence and the develop- 
 ment of organs subservient to the habits of the seve- 
 ral orders of animals. 
 
( 67 ) 
 
 CHAPTER IV. 
 
 THE NERVOUS SYSTEM IN THE AVERTEBRATED 
 ORDERS OF ANIMALS. 
 
 It has been a favourite doctrine with many phy- 
 siologists, that irrif abihty, in its Hmited signification, 
 or as denoting the susceptibiUty of movement or 
 contraction on the appUcation of a stimuhis, is in- 
 dependent of the nervous power. This property 
 they conceive to be inherent in particular tissues, as 
 in the muscular fibre of animals and certain fibres 
 of plants ; and they have been accustomed to sup- 
 port this doctrine more especially by a reference 
 to the supposed absence of nervous matter in the 
 lowest orders of animals. The actions of these, they 
 contend, result altogether from irritability ; that is, 
 the movements of their organs are determined by 
 the direct application of stimuli from without. 
 Thus in such animals inhabiting the water, sub- 
 stances, it is conceived, are brought into contact 
 with their prehensile organs, and stimulating them 
 to contract, are detained and brought within the 
 reach of the assimilating powers of the animal ; and 
 so they reason of the other actions belonging to such 
 animals. This doctrine, however, appears to main- 
 tain itself rather from the difficulty of refuting it 
 than from any considerable weight of positive evi- 
 dence in its favour. While, however, there are 
 
6s NERVOUS SYSTEM IN THE 
 
 some animals so passive in tlicir habits that such an 
 irritability might be deemed adequate to explain all 
 their phenomena, it has been found that even in 
 many of these a nervous system exists, while in 
 many others equally low in the scale of life, in which 
 as yet no indications of a nervous system have been 
 detected, the actions are so lively, as plainly to im- 
 ply sensibility, and, in consequence, the existence of 
 a nervous system. As the irritability of a part, in 
 its limited signification, denotes a susceptibility in 
 that part of movement on the application of a sti- 
 mulus, so sensibility in a part denotes a property in 
 that part of transmitting impressions made on it so 
 as to affect a more or less distant internal organ ; 
 which organ in turn may become a centre of excite- 
 ment through other nerves to the moving organs of 
 the body in general. An animal, then, which is go- 
 verned exclusively by irritability, must be purely 
 passive in its nature, since no act can occur in any 
 of its parts or organs, except when an external sti- 
 mulant has come into direct contact with some one 
 of them ; while on the contrary, in an animal pos- 
 sessed of sensibility, an external stimulus can give 
 rise to a long series of acts in organs or parts dis- 
 ant from that to which it was applied. Thus by an 
 external agent, one external part receives an impres- 
 sion ; this impression is followed by an affection of 
 the nervous centre ; this again is succeeded by the 
 muscular contraction of some other part or organ 
 supplied with nerves from the centre ; but this con- 
 traction is itself a new source of impression to the 
 
AVERTEBRATED ORDERS OF ANIMALS. 69 
 
 sensibility of that part, which, as in the case of the 
 first external agent, becomes the cause of a new 
 affection of the nervous centre, from which a new 
 series of the same changes may proceed to an in- 
 definite extent. 
 
 It is but a few years since a nervous system was 
 denied to the whole order of Zoophyta ; more mi- 
 nute anatomical investigation, however, has demon- 
 strated how erroneous was this inference ; and now 
 its presence is acknowledged in most of the sections 
 of that order, and ithas more recently been discovered 
 by Ehrenberg even in the Infusoria. It is found in 
 the actinia or sea-anemone, in the medusa or sea- 
 blubber, and is very distinct in the star-fish and echi- 
 nus or sea-urchin. If, then, it exists demonstratively 
 in animals so sluggish as these, is it possible to deny 
 it to others full of life and activity, such as the cer- 
 cariae, which are distinctly sensitive to light, possess 
 an acute sense of taste, distinguish, pursue, and 
 seize their prey, while they avoid impinging upon 
 €ach other, as they swim in myriads in a drop of 
 water ? From such evidence, then, the fair conclu- 
 sion seems to be, that a nervous system exists 
 throughout the animal kingdom ; though it may be, 
 that, besides its transparency in most such animals, 
 the additional obstacle to its discovery exists that 
 it is diffused and mixed up in one homogeneous 
 mass with the general tissue of the body. 
 
 The simplest form of the nervous system in the 
 lower animals of the avertebrate division, is a series 
 
70 NERVOUS SYSTEM IN THE 
 
 of minute nervous knots or ganglia, connected by 
 nervous filaments or commissures ; while the proper 
 nerves that proceed to the periphery of the body, 
 arise, not from the commissures and ganglia indif- 
 ferently, but from the ganglia only, as seen in 
 Plate 6. Fig. 1. representing the nervous system in 
 the Beroe pileus ; in which it is disposed around the 
 month, at the lower extremity of the body in form of 
 a double filament with eight small ganglia. In the 
 well-known echinodermatous animal the star-fish, a 
 series of ganglia are placed around the central 
 mouth, one opposite to each ray ; these are connected 
 by a nervous chord into a complete circle, and from 
 each ganglion a nerve is transmitted to the opposite 
 ray, while two other nerves pass inwards from each 
 to be distributed about the gullet within the disk 
 of the animal. {Plate 6, Fig. 2.) On a very simi- 
 lar plan the nervous system is developed in the sea- 
 urchin, in the medusa or sea -blubber, and in the ac- 
 tinia or sea-anemone. 
 
 In the entozoa or intestinal worms which belong 
 to the Zoophyta of Cuvier, the nervous system 
 should perhaps be considered as less developed. 
 In the ascaris, for example, (Plate 6, Fig. 3.) it is 
 a simple chord, hardly exhibiting, in its course, any 
 thing entitled to the name of ganglia ; this chord, 
 however, separates into two columns above to em- 
 brace the gullet, and lower in the body to encircle 
 the female organ of generation. In the animals of 
 this order, which adhere to the external surface of 
 others, the system is more developed, forming two 
 chords, one on each side of the mesial plane. 
 
AVERTEBRATED ORDERS OF ANIMALS. 7 1 
 
 As we ascend from the zoophyta, in Cuvier's ar- 
 rangement, the Insecta stand next ; yet it is more 
 convenient to consider before these the annehdaor 
 red-blooded worms ; which present as great a va- 
 riety in the development of their nervous system 
 as in that of their bodily frame. In the planariae, 
 and in the simplest of the avquatic worms, traces of 
 a nervous longitudinal chord are perceived with 
 difficulty ; and even in the naiads and some of the 
 nereids, the central chord is as simple as in the 
 ascaris and other intestinal worms. Ganglionic 
 enlargements are hardly discovered even in the more 
 developed air-breathing earth-worm, along the mid- 
 dle chord, though numerous lateral nerves extend 
 to their highly moveable segments and very sensi- 
 tive skin, and two encephalic ganglia embrace the 
 gullet at their anterior extremity, {Plate 6, Fig 4). 
 When the body of the annelida acquires a greater 
 lateral development, as in the leech or the sea- 
 mouse, the nervous columns and ganglia become 
 more conspicuous. The ganglia in the leech are 
 about twenty-five in number ; and are placed closer 
 to each other in the anterior part of the nervous 
 column than in the posterior ; or there is here an 
 indication of that nervous concenti'ation, which cha- 
 racterizes the higher orders of the articulata. 
 Throughout this order, then, there is a remarkable 
 illustration of the uniform connection between the 
 development and the action of parts, and the com- 
 plexity of the nervous system. 
 
72 NERVOUS SYSTEM IN THE 
 
 In Insects, the general character of the nervous 
 system is still the same, but more developed ; while 
 its successive changes may be traced from the lar- 
 va state through the pupa to its perfect maturity in 
 the imago or complete insect. In the larva state, 
 the nervous column shews a development very simi- 
 lar to that in the annelida, or it is often a nearly 
 simple cylinder, without any conspicuous enlarge- 
 ment. Some insects, as the myriapods, preserve 
 this helminthoid form of the nervous system in the 
 mature state, and the simplicity of their outward 
 form, and the imperfection of their internal organs, 
 are in accordance with this inferior development of 
 their nervous system. 
 
 The distinct distribution of certain nerves, deri- 
 ved from the nervous centre even in the lowest 
 tribes, as in the star-fish, to the organs of locomo- 
 tion, and of others to the organs of sensation and 
 various internal parts, seemed to point out, from the 
 first, the same division into motor and sensific por- 
 tions in the avertebrate as in the vertebrate tribes. 
 In insects, however, this distinction becomes alto- 
 gether unequivocal, as might be expected in ani- 
 mals in which the motor power acquires so extend- 
 ed a development. The abdominal nervous columns 
 of insects, w^re long since correctly regarded as 
 corresponding to the cerebro-spinal system of the 
 vertebrata ; or their nervous system corresponds at 
 once to the ganglionic nerves and nervous centre 
 of the same animals. There are generally at first 
 thirteen pairs of approximated ganglia correspond- 
 
AVERTEBRATED ORDERS OF ANIMALS. 73 
 
 ing with the original segments along the middle of 
 the ventral surface, and the gullet penetrates the 
 nervous columns between the first and second pairs 
 of ganglia, or the first pair only are supra-oesopha- 
 geal, or cephalic. The ganglia at first are nearly 
 at equal distances and of equal sizes, as in the worms ; 
 but as the animal advances, the ganglia and columns 
 of opposite sides approximate, and become concen- 
 trated in a longitudinal direction, so as to become 
 accumulated towards the place where, in the adult 
 state, nervous power is more required. The change 
 in the development of the nervous system in the pro • 
 gress of an insect, is proportioned to the degree of 
 alteration produced on it, as its metamorphosis pro- 
 ceeds and is completed. In the larva state, the 
 cesophageal ring is broader, corresponding to the 
 extreme voracity of the animal in that state, — a ca- 
 terpillar being computed to devour and digest three 
 times its own weight of aliment in twenty-four 
 hours. In Plate 6 is exhibited the respective con- 
 ditions of the nervous system, as described and fi- 
 gured by Herold, in the Papilio BrassiccB, or com- 
 mon cabbage butterfly, in the states of larva, Fig. 
 5 ; pupa. Fig. 6 ; and imago. Fig. 7. 
 
 It was in the arachnida, for example in the scor- 
 pion, that a continuous motor tract along the sur- 
 face of the nervous column was first pointed out by 
 Treviranus and MuUer ; it is seen in their figure 
 (Plate 7, Fig. 1.), running by the side of the ganglia. 
 As it lies over the sensific, it does not correspond in 
 place to the motor tract of the cerebro-spinal axis 
 
74 NERVOUS SYSTEM IN THE 
 
 of the vertebrata, in which it is formed by tlie an- 
 terior or inferior cohnnns. TJiis, liowever, is but a 
 part of a general law of inversion as to the position 
 of the nervous system in the articulata. 
 
 The development of the nervous system in the 
 whole tribe of araclmida, well accords with the ac- 
 tivity of their habits, and the energy of their func • 
 tions in general. 
 
 In the Crustacea, the nervous system exhibits a 
 variety of character, not less remarkable than an- 
 swering to the diversity of form and function ob- 
 served in the order ; in some it hardly exceeds its 
 condition in the lowest worms, while in others it 
 approaches to the development which belongs to 
 the molluscous animals. The same tendency to 
 concentration of the nervous system, as it becomes 
 more develo}:>ed, is observed here as in the insecta. 
 Plate 7, Figures 2, 3, 4, and 5, grouped from Au- 
 douin, Edwards, Succow, and Grant, exhibit the 
 nervous system in the Talitrus locusta, the cyrao- 
 thea, the lobster, and the maia. 
 
 In the molluscous animals of all the avertebrata, 
 the nervous system attains the greatest develop- 
 ment ; yet a difficulty immediately strikes us here, 
 for many of the molluscous tribes appear among 
 the most sluggish of the whole chain of animals ; 
 and it seems difficult to admit any accordance be- 
 tween function and development, when we find the 
 nervous system of an oyster, mussel, whelk, or lim- 
 pet, placed above that of the industrious bee, and 
 the provident ant. The mollusca, however, do not 
 
AVERTEBRATED ORDERS OF ANIMALS. 75 
 
 SO much form a group in which throughout, the ner- 
 vous system is more highly displayed than in the 
 zoophyta and articulata, as a group in which that 
 system assumes a new type ; which, in the least 
 evolved state, should not be considered as more 
 perfect than that of the articulata, though, in the 
 progress of development, as the animals grow in 
 structure and function, it undoubtedly stands supe- 
 rior to that of the other avertebrated orders, and 
 makes a close approach to the" state in which the 
 same system is found in the vertebrated classes* 
 Plate 8, Fig. 1, exhibits the nervous system in the 
 common mussel. We see two large v/hite ganglia 
 placed on the lateral parts of the mouth (a, h), 
 and sending numerous branches to the lips ; two of 
 which often form a distinct supra-oesophageal or en- 
 cephalic ganglion, after encompassing the gullet ; 
 and two others form a double ganglion just below 
 the first pair. From the same ganglia nervous co- 
 lumns proceed backward along the inferior surface 
 of the abdominal cavity, to the base of the muscu- 
 lar foot, where the middle pair of ganglia (c, d) are 
 placed. These latter vary much in size, according 
 to the magnitude of the foot which they supply. 
 The columns being continued backwards, form on 
 the inferior surface of the great abductor muscle of 
 the valves, a third pair of ganglia at e, varying in 
 size with the muscle, and sending nerves to the 
 posterior part of the trunk and the adjacent organs. 
 From the large nerves (/) branches are traced to 
 the gills. 
 
76 NERVOUS SYSTEM IN THE 
 
 It would be tedious to trace the successive stej^s 
 by wliich this system is unfolded through the seve- 
 ral orders of" this great class, from the acephala, to 
 which the mussel belongs, through the cirrhopo- 
 da, brachiopoda, gasteropoda, and pteropoda, up 
 to tlie cephalopoda, in which the development of 
 the nervous system comes nearest to that of the 
 vertebrata ; since the only conclusion to be drawn 
 from these anatomical descriptions, namely, that 
 «very advance in function is accompanied with a 
 corresponding advance in development, has already 
 been sufficiently illustrated. A slight reference to 
 the state of this system in the highest of the mol- 
 lusca and of the avertebrate tribes, will form a pro- 
 per termination to this sketch of the nervous sys- 
 tem. In these the gullet still perforates the brain, 
 as in all the inferior classes, but the greatest part 
 of that organ, and of the symmetrical columns pro- 
 -duced from it, are, in them, situated above the ali- 
 mentary canal. The brain is enclosed in a distinct 
 cranium; many symmetrical ganglia are formed 
 both before and behind that organ ; and sympathe- 
 tic ganglia appear in the abdominal cavity. Plate 8, 
 Fig. 2, after Chiaje, of the skull of the argonauta, 
 laid open from behind, will give some idea of its 
 development. The brain {a) is of a roundish form, 
 and descends to encircle the gullet (?) ; it gives off 
 the large optic nerves {g) which perforate the skull 
 to reach the pedunculated eyes. From the brain 
 uilso are derived the separate great symmetrical co- 
 
AVERTEBRATED ORDERS OF ANIMALS. 77 
 
 lumns (b, b), which are directed backwards to the 
 parallel ganglia {c,c). When the supra-cesopha- 
 geal ganglion and the oesophagus are removed, the 
 great lateral sub- oesophageal pedal ganglia (/) are 
 found to send nerves {d, d, d, e, e), along with the 
 bloodvessels, to ramify on the canal of the arms. 
 
( 78 ) 
 
 CHAPTER V. 
 
 OF IRRITABILITY IN PLANTS AND ANIMALS. 
 
 The simplest faculty possessed by organized 
 beings, plants as well as animals, is Irritability, 
 or, in its largest sense, that susceptibility of being 
 acted upon, otherwise than merely chemically or 
 merely mechanically, by various agents, such as 
 heat, light, air, aliment, and the like, so as to 
 evince various phenomena, which, for the sake of 
 distinction, may be called vital : it is by the posses- 
 sion of this faculty or susceptibility that such beings 
 are distinguished from inorganic, or mineral sub- 
 stances in general ; and it is by the display of these 
 phenomena that Life, in its simplest state, exists. 
 Life, then, and irritation, or irritability in action, 
 are synonymous terms ; it implies certain motions 
 characteristic of organized beings in general, but 
 not such as are either instinctive or rational, al- 
 though, in their character and results, they are 
 often equally, if not more wonderful than either. 
 It is proper to be aware, however, as we have be- 
 fore hinted, that, by some physiologists, — for ex- 
 ample, by Dr Good and others, who believe in the 
 existence of a Living Principle, as a distinct enti- 
 
IRRITABILITY IN PLANTS AND ANIMALS. 79 
 
 ty, — these vital motions are regarded as instinctive. 
 " The law of instinct," says Dr Good, " is the law 
 of the vital principle; instinctive actions are the 
 actions of the living principle." By M. Virey also, 
 these organic motions are regarded merely as a 
 species of instinct ; under which general term he 
 includes, as well the mechanism of organization, as 
 " those spontaneous outward impulses which, like 
 the former, manifest themselves without the inter- 
 vention of intelligence." We hope to make it ap- 
 pear, however, that the two are, in the main, as 
 distinct from each other in their nature and condi- 
 tions, as either of them is from reason. 
 
 It is then to simple irritation that we ascribe the' 
 chief kinds of vital action, whether obvious to the 
 senses or inferred, in which the functions common- 
 ly called organic, such as the digestion of the aliment, 
 the circulation of the fluids, secretion and absorp- 
 tion, consist, — functions carried on not only without 
 the will, but without the consciousness of the being 
 in which they are taking place. 
 
 Organic life is exemplified in its simplest form by 
 plants, since, in them, the indications of any super- 
 added functions, dependent on the possession of 
 certain other faculties besides irritability, which 
 most animals display, are in general somewhat am- 
 biguous. Nor is it merely in the motions conti- 
 nually going on within themselves, by virtue of 
 certain common stimuli, to which they are con- 
 stantly exposed, that the irritability of plants consists, 
 since many of them display very remarkable move- 
 
80 IRRITABILITY IN PLANTS AND ANIMALS. 
 
 merits when certain parts of their surface are ex- 
 posed to the touch or to other median ical agents. 
 It is famiharly known to every body, that if the 
 finger be apphed, however sHghtly, to the leaves of 
 the humble plant (Mimosa pudica), they imme- 
 diately acknowledge the impression and subside ; 
 and if a Hy or other small insect alight on the leaf 
 of the ^'enus fly trap (Dioncea muscipula)^ it is 
 often suddenly imprisoned, by the closing of the 
 leaf over it in the manner of a cup. In like man- 
 ner, the stamens of the common barbery (Berheris 
 vulgaris), of the prickly pear (Cactus opuntia), a 
 kind of nettle (Urtica pilulifera), and of several 
 other plants, are immediately stimulated to very 
 remarkable motions by the application to them of 
 various agents. These motions are the result of 
 mere irritation, and similar to those which may be 
 excited in the muscles of an apoplectic man — in 
 whom the organic functions alone continue to be 
 performed — by similar means. But by far the 
 most wonderful examples of the irritation of plants, 
 are the processes continually going on within them- 
 selves, from which result the assimilation of their 
 aliment, the motion of their sap, and in particular, 
 tlie periodical formation of their several parts, such 
 as the leaves and flowers, the exquisite delicacy 
 and beauty of the structure of which, and the direct 
 subserviency of each part to the usefulness of the 
 whole, infinitely surpass those of any production of 
 either instinct or reason that ever existed ; nay, 
 some of the motions of plants bear the closest affi- 
 
IRRITABILITY IN PLANTS AND ANIMALS. 81 
 
 nity to the actual instincts of animals. But as it 
 does not yet appear how far these are produced by 
 any apparatus of sensation, such as exists in ani- 
 mals, it seems proper to take notice of them here 
 under the head of irritability, rather than to place 
 them under the same head with animal instinct. 
 It is well known to every body, that if a plant be 
 kept in a room which is lighted only by one small 
 hole, it will always shoot towards that aperture, and 
 having passed through it, Avill afterwards vegetate 
 in its natural direction ; and it is equally so that 
 many plants, the hop-plant (Humulus Lupulusjy for 
 example, revolving round a pole, and the gorgeous 
 sun-flower (Heliotropiimi annuum), rotating onjts 
 stem, follow the course of the sun. The experi- 
 ment of Dr Percival also, in proof of the tendency 
 of plants to move in search of pure air, has often 
 been appealed to. " Several years ago," says he, 
 " while engaged in a course of experiments to as- 
 certain the influence of fixed air on vegetation, the 
 following fact repeatedly occurred to me. A sprig 
 of mint suspended by the root, with the head down- 
 wards, in the middle glass -vessel of Dr Nooth's 
 machine, continued to thrive vigorously, without 
 any other pabulum than what was supplied by tlie 
 stream of mephitic gas to which it was exposed. 
 In twenty- four hours the stem formed into a curve, 
 the head became erect and gradually ascended to- 
 wards the mouth of the vessel, thus producing, by 
 successive efforts, a new and unusual configuration 
 of its parts. Such exertions in the sprig of mint to 
 
 F 
 
82 IRRITABILITY IN PLANTS AND ANIMALS. 
 
 rectify its inverted position, and to remove from a 
 foreign to its natural element, seems to evince vo- 
 lition to avoid what is evil, and to recover what had 
 been experienced to be good." The same tendency 
 also is constantly evinced by the plumiila of the 
 seeds of plants, which, in whatever direction the 
 seed be sown, always rises into the air, while the 
 radicle with equal constancy sinks deeper and 
 deeper into the soil. In this case, while the for- 
 mer ascends in search of air, the latter descends in 
 search of moisture ; and the power which all roots 
 display of altering their course whenever they ap- 
 proach a substance which would afford them insuf- 
 ficient nourishment, and of shooting towards any 
 thing which promises them abundance of this, has 
 been very frequently remarked. Lord Karnes re- 
 lates an instance in which a fine compost for flowers 
 was left for two or three years at the foot of an elm, 
 and, in this period, the greater part of the root of 
 the tree had shot into it ; and it has been proved 
 by repeated experiments, that if a wet sponge be 
 placed near a root, exposed to the air, the fibres of 
 the root will extend towards it, and change their 
 course as often as the situation of the sponge is 
 changed. Now these motions of plants, unlike 
 those of certain parts of the humble plant, the 
 Venus' fly-trap, the prickly pear, and others to 
 which we have already alluded, are not the result 
 of any direct stimulus applied to them, but take 
 place rather from the defect of such stimulus. The 
 pliant in comparative darkness moves in search of 
 
raRITABILITY IN PLANTS AND AT^IMALS. 83 
 
 light, the hop and the sun-flower, which the sun is 
 deserting, move in search of heat, the sprig of mint 
 in carbonic acid, and the plumula of seeds in earth, 
 move in search of air, while the radicle of seeds 
 and the roots of plants in general, in comparatively 
 arid situations, move in search of moisture; and all 
 these, light, heat, air, and moisture, are the ordi- 
 nary and essential stimuli of plants, but they cannot 
 act where they are not. These motions of plants, 
 therefore, cannot arise from any direct irritation, 
 but must proceed from something analogous to the 
 sensation of a want, originating in an indirect irri- 
 tation excited by the absence of their accustomed 
 stimuli, and prompting them to the proper means 
 of relieving it by motions quite analogous to those 
 wTiich in animals are called instinctive. They do 
 not imply thought any more than the satisfying of 
 hunger, by taking food implies thought ; but do 
 they not imply sensation in that modification of it 
 which is called touch ? 
 
 Nor is it only in pursuit of good, but also in 
 warding off evil, that many plants appear to display 
 a form of instinct. This is the case with the Con- 
 volvulus arvensis, the Anagallis arvensis, or poor 
 man's weather-glass, and many others, which con- 
 stantly fold up their petals in cold cloudy weather, 
 or at the approach of rain, and do not again unfold 
 them till cheered by the returning sun. These 
 instances, however, are less conclusive in favour of 
 the doctrine which ascribes instinct to plants, than 
 those previously adduced ; since it may be made a 
 
M IRRITABILITY IN PLANTS AND ANIMALS. 
 
 (juestion, wliethcr the motions, in these cases, do 
 jiot arise — hke the reputed sleep of plants — rather 
 from the intermission of ordinary actions, than from 
 the supervention of new ones. Perhaps it is the 
 expansion of the petals, when acted on by the 
 stimulus of light and heat during fair weather, 
 which should be considered as their active state, 
 while the closure of them, when these are with- 
 drawn, should be regarded as their repose ; but in 
 the instances previously adduced, there can be no 
 ambiguity, and as motions similar to them, when 
 displayed by animals, are without hesitation admit- 
 ted as evidences of their instinct, they must be 
 taken as proof of an analogous function in plants. 
 luid appear to be explicable in the manner above 
 proposed. 
 
 What has been said of the irritation of plants may 
 he applied equally to that of animals. It is upon 
 this that depends the action, more or less constant, 
 of the stomach and intestines, of the heart, and of 
 all the other viscera which minister directly or in- 
 directly to the several organic functions, as well as 
 that — infinitely more wonderful — of the extremities 
 of the bloodvessels, from which results as well the 
 .primary formation as the continued subsequent main- 
 tenance in a state of integrity of all the organs of 
 the body. And what result of either Instinct or 
 Rational actions, — what snail's shell, what spider's 
 web, what bee's comb, what bird's nest, what 
 beaver's hut on the one hand, or, on the other, what 
 piece of workmanship that ever issued from the 
 
IRRITABILITY IN PLANTS AND ANIMALS. 85 
 
 hand of man, gifted with the highest degree of in- 
 telligence, profound in every department of science, 
 and skilful in every branch of art, can for a moment 
 compete, in delicacy and beauty of structure, or in 
 subserviency of means to the end in view, with the 
 eye or ear of the humblest reptile that crawls ? 
 How admirably, likewise, is each organ of every 
 animal adapted, not only to the function in gene- 
 ral, to which it ministers, but to the particular mo- 
 dification of that very function, as connected with the 
 habits of the individual ; or rather, assuming what 
 appears to be really the case, that the habits of ani- 
 mals are dependent on their organization, how per- 
 fect is the harmony of structure between all the or- 
 gans of every animal, as conducing equally to cer- 
 tain habits ! Where do we find the rigid spine, 
 the hinge-like wi*ist, and the few and hoof-clad 
 toes, which characterise a vegetable feeder, asso- 
 ciated with the broad jaw-bone, with its hinge-like 
 joint and powerful elevating muscles, and the sharp- 
 pointed teeth, or with the simple and short stomach 
 and intestines which distinguish a carnivorous qua- 
 druped ; or where, on the other hand, the flexible 
 spine, the rotating wrist, and the numerous well- 
 armed toes, adapted for seizing and retaining living 
 prey, associated with the long and narrow jaw-bone, 
 with its revolving joint and strong lateral muscles, 
 and the broad flat teieth, calculated for grinding 
 grass, or with the numerous stomachs and long and 
 complicated intestinal canal, appropriated to its di- 
 gestion ? " The reason," says Kant, " of the ex- 
 
f^fi IRRITABILITY IN PLANTS AND ANIMALS. 
 
 isteycc," and he might liave added of the character, 
 " of cacl) })art of an organized being resides in the 
 whole ;" and liow admirably is the correspondence, 
 in this respect, of all the parts of every tribe of ani- 
 mals, can be only conceived even by one who has 
 within his grasp, as it were, the whole of animated 
 nature, and is master in detail, of the anatomy and 
 physiology of every individual which it embraces. 
 Where shall we look, among the results of either 
 Reason or Instinct, for productions at once so ex- 
 quisite, considered individually, and so harmonious, 
 when contemplated as parts of a stupendous whole, 
 as these results of simple irritation ? 
 
 It has been presumed by some authors, who seem, 
 like Good and Virey, to have confounded the ac- 
 tions just described with those properly called in- 
 stinctive, that the latter are merely the operations 
 of a kind of machinery obeying certain fixed laws, 
 like those of attraction and repulsion, of w hich each 
 of the inferior animals, presuming that they are ac- 
 tuated by instinct alone, is an example ; and, con- 
 sequently, that the various structures, such as the 
 shell of the snail, the web of the spider, and so 
 forth, which result from such operations, are only 
 one remove, with respect to their manner of forma- 
 tion, from the arrangement of matter constituting 
 the hoar-frost which forms on the window in a win- 
 ter night, or a salt which crystallizes from its solu- 
 tion. This doctrine appears to have originated 
 with Pereira in 1 554, and was subsequently adopt- 
 ed by Descartes, Buffon, and many others. In all 
 
IRRITABILITY IN PLANTS AND ANIMALS. 87 
 
 probability, however, it is not so much to really in- 
 stinctive actions as to those which we have just de- 
 scribed as proceeding from irritation that it is ap- 
 plicable. And, indeed, in as far as the internal ad- 
 ministration of their bodies is concerned, not only 
 the lower tribes of animals, but man also, seems to 
 be little better than a machine, acting in blind obe- 
 dience to laws, vital indeed, and so far superior to 
 those which regulate the condensation of a vapour, 
 or the crystallization of a salt, but still entirely in- 
 dependent, as respects the major part of them, as 
 well of the consciousness, as of the volition of the 
 individual in which they manifest themselves. The 
 actions, then, resulting from these laws may be re- 
 garded perhaps as something intermediate, as it 
 were, between those which take place in the mine- 
 ral kingdom and those properly called instinctive. 
 
 Before proceeding further, however, the view 
 just alluded to, which confounds organic acts with 
 true instinctive acts, merits a brief consideration. 
 This view, perhaps, dates from the vegetative soul 
 of Plato, and runs more or less throughout many 
 systems both ancient and modern, — the construct- 
 ing soul of Aristotle, the impetum faciens of Hip- 
 pocrates, the archaeus of Paracelsus and Van Hel- 
 mont, and the formative appetency and propensity 
 of more recent ones, — for there is this common to 
 all these varied views and expressions, that some- 
 thing like intelligence or consciousness of design is 
 implied as existing in the principle made to direct 
 and preside over organic acts. And the prevalence 
 
88 IRRITABILITY IN PLANTS AND ANIMALS. 
 
 (if this mode of" ex})laining sucli acts through so 
 many ages may be ascribed to that early propen- 
 sity among men to satisfy their passion for giving 
 causes to events and the hke, to call in the agency 
 of animate beings in the shape of a goddess, nymph, 
 or genius loci, as often as they fail to hit upon a more 
 intelligible cause. But let us consider how far there 
 are any points of resemblance between organic and 
 instinctive acts, in order to draw the proper line of 
 distinction between them. Organic acts are not all 
 of the same kind ; one description is analogous in 
 effect to the operations of chemistry, while another 
 bears an analogy to mechanical results. Thus, the 
 conversion of aliment into chyme in the stomach, 
 the separation by the lacteal tubes of the chyle 
 from the mixture of chyme, bile, and pancreatic 
 juice contained in the intestinal canal ; the conver- 
 sion of the chyle into the blood ; the purification 
 of the blood in the lungs under the influence of the 
 atmospheric air ; the formation of the several con- 
 stituents of the secretions ; the deposition of new 
 matter for the growth and repair of the solids ; and, 
 finally, the removal of decayed or exhausted tissues, 
 are so many operations strictly analogous to the or- 
 dinary effects of chemistry, though not produced in 
 accordance with the known laws which regulate the 
 chemistry of inert bodies. These processes, indeed, 
 constitute organic chemistry, and the bodies con- 
 cerned are, as in every other kind of chemistry, 
 minute particles acting on each other at insensible 
 distances, by attraction and repulsion, the particles 
 
IRRITABILITY IN PLANTS AND ANIMALS. 89 
 
 here being not mere atoms, but organic particles or 
 molecules. These organic molecules, by the at- 
 tractions and repulsions, and the capabilities of 
 change under the variation of conditions and cir- 
 cumstances to which they are subjected, are instru- 
 mental in the growth and development, the repair 
 and maintenance, and, finally, in the decay and 
 death, of animal bodies. Here, then, are thousands 
 and tens of thousands of organic molecules unceas- 
 ingly ranging themselves each in its appropriate 
 place, changing that place to assume a new situa- 
 tion, and altering their very nature to fit themselves 
 for new circumstances ; so that the collective effect 
 of the acts and changes of each is the production 
 and support of a machine unequalled in the intri- 
 cacy of its parts, unparalleled in the complexity of 
 its movements. What may be called a poetical 
 solution of these phenomena is, to conceive each of 
 these numerous particles endowed with intelligence 
 and consciousness, and capacity of action sufficient 
 to enable it to perform its particular task, so that 
 the united operation of the whole multitude may 
 give effect to the production and maintenance of 
 an animal body. This, however, becomes a highly 
 rational view w hen changed to this form : it has 
 pleased the Almighty Author of Nature to impress, 
 or to cause to be im.pressed, on such molecules cer- 
 tain capacities of action to be called forth various- 
 ly under different circumstances of position, im- 
 parted and withdrawn under definite conditions, so 
 that their blind and unconscious action on each 
 
00 IRRITABILITY IN PLANT? AND ANIMALS. 
 
 otlicr has for its result the animal frame, a work of 
 the most perfect design, — the chief wonder of crea- 
 tion. 
 
 The analogy between the operation of such mole- 
 cules and what are generally known as the opera- 
 tions of instinct, cannot but be discovered on the 
 most superficial glance. Nor would it be illogical, 
 however little it may be expedient, to term the at- 
 tractions of such molecules instinctive affinities. 
 
 While, then, there is an undeniable analogy be- 
 tween the acts commonly regarded as instinctive, 
 and those processes of the living machine, there is 
 also a broad line of distinction, the former being 
 exclusively acts of relation or animal acts, and, at 
 the same time, of a mechanical nature, or analogous 
 to mechanical movement, while the latter are assimi- 
 lative actions, and analogous to chemical operations. 
 
 The acts, however, of a mechanical kind belong- 
 ing to the functions of assimilation make a nearer 
 approach to ordinary instinctive acts, and are, in- 
 deed, often ranked under instinct ; for example, 
 the contraction of the heart in the circulation of the 
 blood, the enlargement of the chest in respiration, 
 the evacuation of the stomach in vomiting, and the 
 expulsion of the contents of the bladder and rec- 
 tum. These acts, in as far as they are independent 
 of the will, are termed automatic ; and, while most 
 of them become so far subject to the will, they are 
 all at birth involuntary, the influence of the will 
 over them being altogether acquired. With the 
 exception of the heart's contraction, concerning the 
 
IRRITABILITY IN PLANTS AND ANIMALS. 91 
 
 exact nature of which physiologists are not yet 
 agreed, all the above acts are dependent upon sen- 
 sation ; from which it will afterwards appear that 
 all ordinary instinctive operations result. And it 
 will perhaps facilitate the exposition of the connec- 
 tion between sensation and instinct, to consider 
 such acts along with instinctive acts, as less equivo- 
 cally under the influence of that principle. 
 
( 1^:^ ) 
 
 CHAPTER VI. 
 
 SEAT OF IRRITABILITY. 
 
 With respect to the immediate seat of irritabi- 
 lity, which we have just treated of as an attribute 
 of organized beings, there is reason to believe that, 
 like all analogous faculties, it is situated, in animals, 
 in some part of the nervous system; and as w^e 
 know that the faculties and powers imparted re- 
 spectively by the spinal chord and brain, situated- 
 within the vertebral canal and skull of such animals 
 as are furnished with a skeleton, are quite distinct 
 from irritability, and that this faculty continues un- 
 impaired when the influence of both these portions 
 of the nervous system is suspended, we should be 
 disposed, a priori, to refer irritability to the gan- 
 glionic, as the only remaining portion of the system 
 in question. This system, as has already been shewn, 
 consists essentially of two sets of knots of nervous 
 matter, situated one on each side of the body, on a 
 line principally with the spine, — in animals furnish- 
 ed with one, — but before it, and connected toge- 
 ther by slender chords and net-works, which fur- 
 ther extend from them in all directions. In animals 
 without skeletons, it is, of course, amalgamated, as 
 
SEAT OF IRRITABILITY. 93 
 
 it were, with the spinal and cerebral systems. Now, 
 according to Sir Charles Bell, " we know only what 
 the sympathetic nerve" — the main branch of the 
 ganglionic system — " is not; and by that means are 
 left to conjecture what are its functions." But be- 
 sides this negative evidence in favour of the theory 
 that it is the immediate seat of irritabihty, some 
 positive facts may be adduced in its support. And 
 in the first place, it may be alleged that as the dis- 
 play of sensibility and of thought by every tribe of 
 animals as we rise in the scale of creation, is seve- 
 rally coeval with the appearance of a spinal chord 
 and a brain — the acknowledged seat of these fa- 
 culties — so the first indication of irritability is co- 
 eval, in general, with that of a ganglionic system of 
 nerves, which, of course, therefore, is the first met 
 with in the ascending scale of animals. The gan- 
 glionic system of nerves, moreover, as ministering 
 apparently to an essential condition of any degree 
 of development, is rarely or never found wanting, 
 however monstrous the infant may be ; whereas 
 sensibility and the faculty of thinking being, as it 
 were, adventitious properties, the spinal chord has 
 not unfrequently, and the brain very often, been 
 found defective. Further, this system of nerves is, 
 in general, relatively larger in children and females, 
 than in adults and males, and it is commonly very 
 small in old persons ; and it is well known how 
 much the irritability of old persons commonly falls 
 short of that of middle-aged persons and males, and 
 the irritability of these again, that of children and 
 
94 SEAT OF IRRITABILITY. 
 
 females. Finally, the internal structure of the gan- 
 glions, and of the nerves connected with them, is very 
 similar to that of the sensific system in general ; 
 and as we know that the former do not impart sen- 
 sibility, it is only fair to believe that they impart an 
 analogous faculty ; and what is so analogous as ir- 
 ritability ? It is remarkable also, that, wherever the 
 irritability of two or more organs of the body seems 
 to be of a different character, a corresponding dif- 
 ference has been observed in the particular struc- 
 ture of the ganglionic nerves which supply them. It 
 may be objected to this doctrine respecting the im- 
 mediate seat of irritability, first, that plants, although 
 they possess irritability, have no nerves whatever ; 
 secondly, that the ganglia which send nerves to 
 any particular organ, may be removed without de • 
 priving this organ of its irritability ; and, thirdly, 
 that the distribution of this sy&tem of nerves is too 
 circumscribed, to allow of our attributing to it a 
 faculty possessed by every part of the body. 
 
 To the first objection, however, it may be replied, 
 that supposed traces of a nervous system have been 
 detected in plants, and, what is remarkable, chiefly 
 in those which afford the most striking instances of 
 irritability ; and even though no such traces had 
 been found, it would be as unreasonable to deny 
 that the ganglionic system of nerves is the imme- 
 diate seat of irritability in animals, because plants 
 have no such system, as it would be to deny that 
 the stomach and heart are, in most animals, the 
 chief agents in effecting digestion and the motions 
 
SEAT OF IRRITABILITY. 95 
 
 of the fluids, because plants perform these functions 
 without their aid. To the second objection it may 
 be answered, that, when we remove a ganghon, we 
 do not immediately impede the functions of the 
 nerves connected with it, each point of such nerves 
 — which, in this respect, are unlike the spinal 
 nerves — being a source of nervous energy to itself, 
 and quite independent, for a time, on any common 
 centre. Lastly, against the third objection it may 
 be said, that such is the communication between 
 the spinal and ganglionic nerves in numerous parts 
 of the body, that we seem to be justified in believ- 
 ing that whithersoever a nerve from the former 
 system proceeds, thither a filament from the latter 
 accompanies it, and, consequently, that the distri- 
 bution of the ganglionic nerves, however apparent- 
 ly circumscribed, is in fact universal. Upon the 
 whole, we are disposed to think favourably of the 
 theory in question ; and we have dwelt upon it, 
 perhaps, at somewhat greater length than the sub- 
 ject may seem to have demanded, from our desire 
 to assign "a local habitation" to the faculty of irrita- 
 bility, as well as to those of which we are presently 
 to speak, and thus to establish, not only the differ- 
 ences in the condition of functions which we have 
 presumed to be different, but also, as far as possi- 
 ble, the source of these differences, as connected 
 with the organization of the body. 
 
 We shall conclude these arguments by briefly 
 drawing upon the lucid account of the history of 
 
96 SEAT OF IRRITABILITY. 
 
 the ganglionic nerves, as given by our lamented 
 triend Dr Fletcher.* 
 
 Before the time of Galen, the ganglionic system 
 of nerves was entirely unknown, and although by 
 him and his followers, the Arabians, the existence 
 of this system, as well as its supposed origin, was 
 pointed out, it was not till the time of Willis that 
 the ganglionic nerves were generally considered as 
 a part of the nervous system at all. Willis, how- 
 ever, still looked upon them as merely an append- 
 age to the cerebro-spinal system, and represented 
 them, both in his verbal description of them, and 
 in his curious diagrams of their distribution, as 
 growing upon the latter " ut frutex super alio fru- 
 tice ;" and this notion having been adopted by nu- 
 merous other writers, both before and since the 
 time that their independence was insisted on by 
 W^inslow, it has become a prevalent custom to regard 
 these nerves as of very secondary importance, and 
 the names imposed upon the system in general, as 
 well as the uses assigned to it, have generally cor- 
 responded with this idea. But it were needless, in 
 this place, to follow our author through all the un- 
 tenable opinions that have been entertained con- 
 cerning these nerves. Even in the present day, 
 the functions of this system is matter of dispute ; 
 Mr Mayo follows Dr Bostock and others in saying 
 " it is unknown" {Outlines of Physiology^ 1833); 
 and Dr Henry, in his report to the British Asso- 
 ciation of the same year, observes, that it "is mat- 
 * Rudiments of Physiology, part ii. «, p. 64, note a. 
 
OF 
 SEAT OF IRRITABILITY. 97 
 
 ter, at present, of conjecture." This, however, we 
 hope we have persuaded the reader, is far from 
 being the case; and it is probable, from the circum- 
 stance of the gangUonic system of nerves not hav - 
 ing been generally introduced to the notice of phy- 
 siologists, till their minds were fully made up re- 
 specting the cerebro-spinal system as the only pri- 
 mary source of nervous energy, as it is called, that 
 the real independence of the former has been over- 
 looked, and facts warped in support of prejudice 
 and habit. Perhaps Winslow was the first to de- 
 scribe the ganglions of the sympathetic system as a 
 kind of nuclei, or little.brains, generating a peculiar 
 property or power of their own, — a description 
 which was adopted by Le Cat ; but it is from the 
 celebrated Essay of Johnstone ( O71 the Use of the 
 Ganglions^ 1771), that the origin of the opinion 
 that they are the primary source of irritability may 
 be dated. The notion of the independence of the 
 ganglionic system was espoused by Cuvier, and 
 particularly insisted on, with his accustomed elo- 
 quence, by Bichat, who represented all the gan- 
 glions of this system as " des centres particuliers de 
 la vie organique, analogues au grand et unique cen- 
 tre de la vie animale, qui est le cerveau ;" and who 
 further demonstrated, not only that all these gan- 
 glions were collectively independent of the cerebro- 
 spinal system, but that each ganglion was indepen- 
 dent of every other — nay, that each nerve proceed- 
 ing from such a ganglion was in a great measure 
 independent of that ganglion, and that even each 
 
iiH SEAT OF IRUITABILITV. 
 
 point ol" such a nerve was independent of all the 
 rest, and constituted alone a distinct focus of ner- 
 vous influence. The doctrine which ascribes irri- 
 tability to the ganglionic system was, however, still 
 more explicitly promulgated by Peffinger, ReiU 
 Richerand, Gall, Wutzer, and Broussais ; the last 
 in particular describing the ganglionic system of 
 nerves as possessing a peculiar kind of sensibility, 
 (i. e. irritability) with which it immediately endows 
 all the organs destined for deposition, absorption, and 
 the other organic functions, and, by means of its 
 repeated connexions with the cerebro-spinal system, 
 all the organs of the body. Views, such we would in- 
 culcate as to the seat of irritability are certainly in- 
 creasing in popularity ; and the reader who wishes 
 to pursue the subject further, will find it forcibly ad- 
 vocated in the works of Dr Copland, Mr Parker, Dr 
 Lovell, Phillips, and especially of Dr Fletcher. 
 
( 99 ) 
 
 CHAPTER VII. 
 
 OF SENSATION AS A CAUSE OF MOTION IN ANIMALS. 
 
 Myriads of animals exist in all parts of creation ; 
 but especially in water, enjoying a brief, but, we 
 cannot doubt, a pleasurable life. Many of these are 
 so minute that it is scarcely possible to conceive, 
 even from their effects, the nature or the range of 
 the powers which they exercise ; and simply con- 
 structed as these creatures are, they nevertheless 
 display a sensibility of astonishing acuteness ; — the 
 faintest impression, which in the more highly en- 
 dowed animals passes unfelt or unheeded, such as a 
 beam of light or the agitation of the air or water, 
 exciting in them motions shewing that they are con- 
 scious of and stimulated by these external agents. 
 Some polypi appear to derive gratification from the 
 influence of light, seek its presence and are ob- 
 served to move towards it, while others display as 
 decided an aversion to it, retreating before the 
 slightest glimpse. Sensibility, or the susceptibility 
 of sensation, then is co-existent or nearly co-exist- 
 ent with the animal kingdom ; in the lower range 
 of which, however, it must be but the rudiment of 
 what it is in the higher. The term implies the 
 
100 OF SENSATION AS A CAUSE OF 
 
 power of transmitting the effect of a stimulus ap- 
 j)lied at one part to a more or less distant part or 
 organ ; and while certain preliminary physical 
 changes must be presumed to occur in the nervous 
 substance, a consciousness of a new impression is 
 the final conclusion of a sensation. It has been long 
 observed, that certain sensations are so invariably 
 followed by certain muscular acts, that they are pro- 
 perly regarded in physiology as the direct conse- 
 quences or effects of them. These are best known 
 in the organic acts before referred to as being ana- 
 logous in their effects to mechanical operations — 
 most of these were originally involuntary, but have 
 become, at least in man, subject to the will. They 
 have a very close resemblance to instinctive acts, 
 and indeed are often said to be so ; although in as 
 far as they take place without the control of the 
 will, they are better termed automatic acts depend- 
 ent on sensation. The difference, however, be- 
 tween them and instinctive acts is somewhat ar- 
 bitrary, being nothing more than that they are sub- 
 servient to organic life, or the assimilative functions ; 
 while true instinctive acts almost exclusively be- 
 long, as has been before remarked, to the functions 
 of animal life, or those of relation. If it appear, 
 then, that many complex muscular acts are the di- 
 rect effects of sensation, there will be less dif- 
 ficulty in the admission of the conclusion at which 
 we shall hereafter arrive, that instinctive acts in ge- 
 neral are the result of definite sensations. Thus 
 inspiration depends on the sensation which arises 
 
MOTION IN ANIMALS. 101 
 
 when the venous blood in the capillaries of the lungs 
 aifects the sentient extremities of the pneumo-gastric 
 nerve. The stimulus is propagated upwards to the 
 encephalon ; and, as it is to be presumed, a physi- 
 cal change in some part of that organ is the conse- 
 quence, which, in certain states at least of the ani- 
 mal, is acccompanied by a perception of uneasiness, 
 referred to the chest, and more or less distinct, ac- 
 cording, to the degree in which the original cause, 
 namely the presence of venous blood in the vascu- 
 lar tissue of the lungs, is applied. This sensation, 
 then, as often as it takes place, according to an 
 original law of the animal economy, at least in cer- 
 tain orders of animals, is succeeded by a transmis- 
 sion of nervous power originating in the nervous 
 centre, — but by what means we know not, — along 
 the nerves of the diaphragm and intercostal muscles, 
 which under this stimulus contract and enlarge the 
 chest for the admission of air. It has been deter- 
 mined that the only part of the encephalon essen- 
 tial to this sensation is the medulla oblongata ; and 
 accordingly anencephalous monsters or those born 
 without brains, live and breathe for a short time 
 after birth, if the spinal chord rises within the skull, 
 without which portion of the encephalon they pe- 
 rish instantly, because when it is wanting the lungs 
 do not act. Death by "pithing" gives an additional 
 illustration of the same thing, for death in that case 
 is produced by the destruction of that part of the 
 nervous system on which the sensation essential to 
 respiration is dependent 
 
102 OF SENSATION AS A CAUSE OF 
 
 It can no longer be reasonably doubted, but that 
 what is here stated, namely, that respiration is di- 
 rectly the consequence of the occurrence of such a 
 sensation, is an observed fact ; but it may be asked, 
 does this fact afford any explanation of the nature 
 of tlie connection between the two acts ? It does 
 not further than to this extent, that, in the animal 
 economy, before the influence of the will is estab- 
 lished, and after that, as often as the will is sus- 
 pended, as in sleep, these two acts stand to each 
 other in the relation of cause and effect — that is, of 
 invariable antecedent and consequent ; or, that the 
 explanation is as perfect in kind as the nature of 
 human knowledge admits of. And supposing it 
 were a settled point, that no intervening link in the 
 chain of causes could possibly be attained by the 
 human mind, it might then be safely pronounced as 
 full an explanation as the effect of impulse in gene- 
 rating motion, — since no other reason can be ulti- 
 mately assigned for the latter than for the former, 
 but that such is the will of the Almighty, — that be- 
 ing the final link in every argument upon causation 
 in general. Although, then, it is possible that some 
 intervening event may hereafter be discovered be- 
 tween the occurrence of sensation and such auto- 
 matic acts as we have described, it must, in the 
 mean time, be regarded, in this as well as in all simi- 
 lar instances, as a logical and sufficient cause. 
 
 Not merely, how^ever, does the simple act of re- 
 spiration admit of explanation on this principle, but 
 all, or nearly all, the varieties and modifications of 
 
MOTION IN ANIMALS. 103 
 
 which its apparatus is susceptible, may in hke man- 
 ner be referred to particular forms of sensation. 
 Thus, the first respiration after birth is not correctly 
 ascribed to a sensation originating in the capillary 
 vessels of the lungs, because, till the air of the at- 
 mosphere has entered these organs, the kind and 
 quantity of blood contained in them must be nearly 
 the same as it was just before birth, so that no cause 
 of a new sensation is derived from this source by 
 the mere circumstance of birth. But in this case 
 there is another and a very important source of sen- 
 sation in the contact of the very vascular surface of 
 the infant's body with the external atmosphere ; 
 that is, the contact of a membrane in the highest 
 degree provided with nerves and bloodvessels, and 
 which has up to that period been accustomed to no 
 greater stimulus than that of a bland fluid, uniform 
 in its composition, uniform in its temperature, and 
 uniform in the mode of its application, with a pe- 
 netrating aeriform fluid abounding in oxygen, the 
 most powerful agent, perhaps, which acts upon the 
 blood, and of a considerably lower temperature than 
 that to which the infant's feelings have hitherto been 
 habituated. The joint stimulus, then, of the cold 
 and of the oxygen of the atmosphere cannot but be 
 productive of a vivid sensation, and this sensation 
 is admitted generally by physiologists to be the im- 
 mediate cause of the first inspiration : that is, the 
 sensation is by an original law of the animal con- 
 stitution followed by a transmission of motor power 
 to the muscles by which the capacity of the thorax 
 
104 OF SENSATION AS A CAUSE OF 
 
 is augmented. Of the very numerous attempts to 
 expound the cause of the first inspiration after birth, 
 such is that which is least open to objection, and 
 which has accordingly obtained the sanction of the 
 most eminent physiologists of our times. The fact 
 before referred to, that infants born altogether with- 
 out an encephalon cannot breathe, while those which 
 have no more than the medulla oblongata within 
 the skull do so for a short time, is in perfect accord- 
 ance with this view, and in a great degree confirma- 
 tory of its truth. 
 
 Nor is this by any means the only instance in 
 which the application of stimuli to the surface of 
 the body is attended with an effort of respiration. 
 The effect of going into the cold-bath when we are 
 unaccustomed to it, or when the water is unusually 
 cold, is familiar to every one. There is in this case 
 a succession of almost convulsive inspirations, which 
 admit of no explanation so simple, as that they are 
 dependent on the sensation which originates in the 
 cold applied to the surface. This, in short, is very 
 much the same as what happens to the infant at 
 birth ; for having been accustomed, during all the 
 j)revious part of its existence, to a temperature equal 
 to that of the internal parts of the mother's body, 
 it is suddenly plunged into a new medium of a more 
 stimulating kind, and at the same time lower in 
 temperature. 
 
 Again, it is observed, that respiration goes on 
 with much greater energy in cold air than in warm, 
 a familiiir example of which is the facility with which 
 
MOTION IN ANIMALS. 10.') 
 
 persons in health keep up the natural temperature, 
 or even overheat themselves by moderate muscular 
 exertion in frosty weather. Now, altliough this 
 effect is attributable to the joint operations of se- 
 veral causes, yet one of these the least equivocally 
 called into operation, is the sensation which follows 
 the application of cold air to the surface. 
 
 The effect of sprinkling cold water on the face, or 
 on other sensible parts of the surface of the body, in 
 promoting the recovery from a fainting fit, is a fact 
 with which every tyro is acquainted. This effect 
 is, however, the result of the same principle, namely, 
 of the increased activity of the muscles of inspira- 
 tion, consequent on a sensation of cold derived from 
 the surface. It might be allowable to avail our- 
 selves of this, as a fact bearing on the view which 
 ascribes motion to sensation, after a simple refer- 
 ence to the circumstance familiar to every one ac- 
 customed to see persons affected with fainting, of 
 the return of animation being accompanied by a 
 full inspiration ; but at the risk of being somewhat 
 tedious, it may be proper to exhibit to the non-me- 
 dical reader, how well the whole theory of the re- 
 covery from this state accords with the doctrine 
 which we would advocate. Fainting consists in a 
 cessation or very great diminution of the action of 
 the heart. Consciousness ceases, for it is observed 
 that the functions of the brain are performed per- 
 fectly only when the blood moves through the ce- 
 rebral vessels with a certain degree of momentum; 
 yet It ciov. »>ot follow that the sensibility of all the 
 
lOfJ OF SENSATION AS A CAUSE OF 
 
 parts of the nervous centre is altogether suspended. 
 Thus in many instiinces, where consciousness is 
 lost, together with all exercise of the external senses, 
 and of the power of volition over the muscles of 
 vohmtary motion, so that the sufferer helplessly falls 
 to the ground, enough of sensibility remains to 
 carry on the function of respiration, dependent 
 though it be on sensation ; that is, at least, on the 
 physical steps preliminary to a perfect sensation. 
 Such is the case in the comatose state which fol- 
 lows severe injuries of the brain, which attends 
 apoplexy, and the epileptic paroxysm, and the un- 
 conscious condition which often precedes death ; in 
 all which instances the medulla oblongata retains 
 its property of being so affected by the venous 
 blood acting on the extremities of the nerve of the 
 lungs, as to generate the motor power necessary 
 for the muscular act of inspiration, after the other 
 parts of the encephalon exhibit no visible signs of 
 being susceptible of the ordinary effects of their 
 proper stimuli. In fainting, however, this part of 
 the nervous centre has its sensibility very much im- 
 paired, though not altogether destroyed; while part- 
 ly from this cause, partly from the languid and in- 
 terrupted motion of the venous blood from the 
 right side of the heart towards the lungs, the respi- 
 ration, if not wholly suspended, becomes impercep- 
 tible. The person is placed in the horizontal position 
 by which the resistance to the return of the venous 
 blood from the extremities to the right side of ^he 
 heart is diminished, so that, detern-* ckI by the 
 
MOTION IN ANIMALS. 107 
 
 slight movements of the heart still subsisting, or 
 perhaps only by the contraction of the arteries, it 
 gradually accumulates in the chambers of the or- 
 gan on the right side, in sufficient quantity to sti- 
 mulate them to contract and transmit it to the 
 lungs. One step, then, towards recovery has 
 now been made, in the application of the proper 
 stimulus on which inspiration depends, to the ex- 
 tremities of the pulmonic nerve ; and even if the 
 sensibility of the medulla oblongata and other sen- 
 tient parts at the base of the brain had been wholly 
 lost at first, as the horizontal posture of the body 
 assists the motion of the blood in the veins of the 
 lower extremities and abdomen towards the right 
 side of the heart, so must it promote the languid 
 motion of the blood in the arteries, whether kept 
 up by a slight action of the organ, or only by the 
 slow contraction of the arteries towards the base of 
 the encephalon, by which its sensibility must be in 
 part restored. If, then, an inspiration is determin- 
 ed by these causes, the venous blood both flows 
 more freely towards the chest, and therefore to- 
 wards the right side of the heart by the action of the 
 thorax during that act, and the blood flows with 
 greater facility through the lungs towards the cham- 
 bers of the left heart by which its action is increased 
 or restored. If, in the mean time, cold be applied 
 to the face, which is copiously supplied with nerves 
 of sensation derived from the base of the encepha- 
 'm, the inspirations become more energetic, and 
 thus the entire recovery of the person is accelerated. 
 
108 OF SENSATION AS A CAUSE OF 
 
 It would be tedious to multiply instances of the 
 influence of the sensation resulting from the appli- 
 cation of cold to the surface, upon the mechanical act 
 of inspiration ; with one or two other instances, then, 
 we will content ourselves. AVhen the concentrat- 
 ed hydrocyanic or prussic acid is administered to an 
 animal, all signs of life almost immediately cease — 
 yet this is not death ; for the animal may be often 
 recovered by the artificial inflation of the lungs. 
 The state produced by this agent seems to be a 
 suspension of the function of the nervous system ; 
 the immediate consequence of which is an inter- 
 ruption of respiration, inasmuch as it is a function 
 dependent on sensation. If, then, respiration be 
 kept up artificially for some time, the effects of the 
 poison on the nervous system by degrees decline, 
 natural respiration is restored, and the animal, which 
 would otherwise have perished, is revived. It has 
 been observed, however, that dashing cold water 
 on the surface proves, in such a case, a substitute 
 for artificial respiration, so as to furnish another 
 evidence of the influence of the sensation of cold 
 upon respiratory movements. It is stated in the 
 earlier reports of the effects produced on dogs in 
 the Grotto del Cane near Naples, that they were 
 immediately recovered by being plunged into cold 
 water. The effect produced by the carbonic acid 
 of the cavern is much the same as that of the hydro- 
 cyanic acid ; and it is by no means improbable that 
 this old practice, which is now neglected, would save 
 the dogs much of the suffering which they are de- 
 
MOTION IN ANIMALS. 109 
 
 scribed as undergoing in recovery, by those who 
 have more recently visited this famous place. 
 
 In illustration of the power of definite sensa- 
 tions in modifying the action of the muscular appa- 
 ratus of respiration, expectoration and sneezing 
 afford an instructive evidence. The design ^of 
 both acts is to expel noxious matters which may 
 have gained access to the windpipe or nostrils. 
 When any unusual irritation aflPects the nerves of 
 the membrane lining the air-passages, cough with 
 expectoration is produced. Thus in deglutition, if 
 any particle of food enters the larynx, it is instant- 
 ly expelled by a violent effort of the respiratory 
 organs ; and when the secretion of the membrane 
 itself becomes either over abundant or acrimoni- 
 ous, or morbid matter is determined fi'om diseased 
 parts of the lungs, or even from the adjacent or- 
 gans, expulsion in the same manner occurs. We 
 have here, then, an unusual stimulus applied to the 
 extremities of the nerves in this membrane, which 
 becomes the source of a sensation destined to be 
 followed by the transmission of motor power to a 
 certain combination, and that a complex combina- 
 tion of many muscles. Cough and expectoration 
 take place in the following manner. A full inspi- 
 ration is produced by the rapid action of the mus- 
 cles, by which, in ordinary circumstances, the chest 
 is enlarged. This of itself implies the operation of 
 the motor power in an unusual manner through 
 several distinct nerves ; then the aperture of the 
 larynx is firmly closed by the action of appropriate 
 
110 OF SENSATION AS A CAUSE OF 
 
 muscles; next the muscles of expiration come into 
 rapid, even convulsive, or at least unusual action, 
 while the air, much condensed, is retained by the 
 closure of the larynx till that organ relaxes, when 
 rushing forth with great impetus, it sweeps along 
 tlie substance giving rise to irritation, and which is 
 said to be expectorated or spit up. The effort is 
 repeated to an extent proportionate to the quantity 
 of the irritating matter, and the difficulty of its re- 
 moval. Cough takes place under too great a va- 
 riety of circumstances of a morbid kind to be fully 
 explained in a treatise of this kind, which seeks an 
 illustration only from the general principle of the 
 act, without pretending to enter into any of the 
 pathological details connected with it. It may, 
 however, be satisfactory to the uninitiated reader, 
 briefly to give a reason why cough sometimes arises, 
 when there is nothing to be expectorated. In 
 pleurisy an example of this kind is usually met with. 
 There, on account of inflammation affecting a neigh- 
 bouring membrane, the pleura, by means of what 
 is called in technical language a derivation, the or- 
 dinary secretion with which the membrane of the 
 air passages is bedewed and defended from slight 
 irritations becomes deficient, and the atmospheric 
 air itself, the continual entrance of which is a ne- 
 cessary condition of the function of respiration, 
 now^ constitutes a source of irritation : or cough is 
 excited, not by the presence of any uncommon ir- 
 ritation, but by the unusual susceptibility of the 
 
MOTION IN ANIMALS. Ill 
 
 nerves'to be affected, when deprived of an ordinary 
 means of protection. 
 
 Sneezing even more signally illustrates the doc- 
 trine which it is the object of all these details to 
 support. An irritation affects the membranes of 
 the nostrils, and is succeeded by an act of inspiration 
 and another of expiration, in which the expulsion 
 of the air takes place through the nostrils, can-ying 
 with it all the irritating substance ; and both these 
 acts are altogether peculiar in their character, being 
 very different from the same acts under any other 
 circumstances. Nor can this pecuUarity and dif- 
 ference depend on any other cause, than the pecu- 
 liarity in the modes in which, and the combination 
 of the muscles to which, the motor power is con- 
 veyed. And this peculiarity in turn admits of no 
 other explanation than that of an established con- 
 nection between the sensations originating in irri- 
 tation applied to the nostril and the generation of 
 such a motor power. The chief pecuHarity in the 
 action of the respiratory apparatus in sneezing, con- 
 sists in both inspiration and expiration taking place 
 while the mouth is closed, and also the passage be- 
 tween it and the nostrils ; and further, the inspira- 
 tion being a slow convulsive movement, while the 
 expiration is as much distinguished for its force and 
 rapidity. It may be worth while to mention, that 
 sneezing is prevented even after the preliminary 
 steps have commenced, by any thing which engages 
 the attention ; thus we often may prevent a person 
 who is made to sneeze easily by snuff doing so, by 
 
112 OF SENSATION AS A CAUSE OF 
 
 telling him that it will not cause him to sneeze. The 
 very wish to sneeze, or the doubt raised in his mind 
 by the conhdencc of the assertion, prevents the sen- 
 sation being followed by its effects. Sighing and 
 yawning are two other forms of respiration, the 
 peculiarities of which must be ascribed to a modi- 
 fication of the ordinary cause of respiration, namely, 
 the stimulus of venous blood in the capillaries of 
 the lungs. Both these acts arise, when the circu- 
 lation through the lungs is in a languid state, and 
 both consist of an inspiration and expiration, each 
 of a specific kind ; and though the word sigh, in all 
 languages, appears to point to the expiration, while 
 the word yawn points to the inspiration, yet they 
 are so closely allied, that when the approach of 
 either is foreseen, it may usually, by an effort of 
 volition, be exchanged for the other. Depressing 
 affections of the mind, want of sleep or of mental 
 occupation, and hunger, are the ordinary conditions 
 on which both occur. It is not so easy to point 
 out the particular circumstances which determine 
 sometimes the one and sometimes the other, to 
 occur under what appears to be nearly the same 
 state of the system ; nor is it necessary for our pre- 
 sent purpose to enter into any scrutiny of such a 
 nicety ; let it suffice to refer to what every one must 
 be aware of, that the sigh more particularly attends 
 depressing affections, while the yawn is chiefly the 
 result of fatigue, idleness, listlessness, and hunger. 
 It may readily be proved, then, that under these 
 circumstances, both the circulation in the lungs and 
 
MOTION IN ANIMALS. 113 
 
 the State of the encephalon, have deviated from a 
 perfect state of integrity or health. A languid state 
 of the former and an impaired sensibility of the 
 latter, must mutually act and react upon each other, 
 until a new state of relation between the one as an 
 excitant and the other as a recipient of stimulus, 
 is established. Whatever retards the motion of 
 the blood through the lungs, by impairing the ac- 
 tivity of the heart's action, on a principle before 
 referred to, diminishes the sensibility of the ence- 
 phalon ; and whatever has this effect in turn in- 
 terferes with the due energy of respiration. It 
 must be supposed, then, that as both the effects go 
 on accumulating under the circumstances supposed 
 now to exist, the venous blood collects in the capil- 
 laries of the lungs, owing to the defect of the mere 
 mechanical act of the enlargement of the chest, in 
 a greater ratio than that in which the sensibility of 
 the medulla oblongata is repaired, so that the con- 
 dition on which sighing and yawning arise, may be 
 regarded as an unusual amount of the ordinary 
 stimulus, viz. venous blood acting through the pul- 
 monic nerves on a diminished sensibility of the 
 part of the nervous centre on which respiration 
 depends ; and this variation in the relative states of 
 the agent and the subject, is attended with a cor- 
 responding variation and effect ; that is, a sigh or a 
 yawn, as compared ^dth an ordinary respiration. 
 
 In a sigh, however, hardly any muscles but those 
 concerned in an ordinary full respiration are con- 
 cerned ; its peculiarity consists in a certain time 
 
 H 
 
I 14 or SENSATION AS A CAUSE OF 
 
 or rythm of action, a slow and measured expansion 
 of the chest, and a corresponding compression of it. 
 In a yawn, on the contrary, many muscles not 
 employed in ordinary respiration are brought into 
 play, more particularly when the cause being 
 greater than usual, it is attended with a stretching 
 of the arms and legs or pandiculation ; which, though 
 it may be controlled by the will, is by no means a 
 voluntary act. It must be regarded, then, as essen- 
 tially determined by the same sensation as the 
 simple sigh, stronger only in degree. We see, then, 
 how many muscles this modification of the ordinary 
 sensation on which respiration depends, brings into 
 activity besides those concerned in the simple act ; 
 namely, the muscles which, by drawing down the 
 jaw, open the mouth wide, the muscles which ex- 
 tend the several joints of the upper extremities, 
 those which extend and straighten the trunk, and, 
 finally, the numerous muscles which extend the 
 joints of the inferior extremities. 
 
 The complex act of deglutition affords an illus- 
 tration of the same kind of movement as the states 
 of respiration just detailed. It may be conveniently 
 divided into three stages. In the first, the mass 
 collected on the tongue, after mastication and mix- 
 ture with the saliva, is transmitted to the base of 
 that organ ; in the second, it is precipitated into 
 the pharynx ; and, in the third, it is transmitted 
 through the gullet into the stomach. The first 
 stage is very much under the control of the will 
 
MOTION IN ANIMALS. 115 
 
 in adults, though doubtless originally automatic and 
 determined by the sensation resulting from the 
 mere presence of the mass in the mouth ; of this 
 stage no more need be said, than that the mass is 
 pressed backwards by the motion of the tongue, 
 while the muscles of the palate prevent it from be- 
 ing thrown upw^ards, and the mouth is contracted 
 by the action of the muscles of the cheeks. No 
 sooner, however, has the mass reached the base of 
 the tongue, than a complex series of acts commences 
 altogether beyond the control of the will, and de- 
 termined by no other cause than the sensation 
 which arises from the effect of a foreign body 
 in that part of the throat. The hyoid bone is 
 drawn forcibly upwards, and along with it the 
 larynx is raised (as may be felt by putting the finger 
 on the pomumAdami), while the epiglottis is forced 
 down to close the aperture of the windpipe ; the 
 pharynx is also drawn upwards and forwards to- 
 wards the base of the tongue. No sooner have the 
 parts of the throat come into this state, than a 
 sudden revulsion is occasioned by the action of 
 antagonising muscles, during which the mass of 
 food is precipitated into the oesophagus or gullet, 
 and the parts restored to their former condition. 
 While, then, we regard the stimulus of the foreign 
 matter on the nerves at the upper part of the throat 
 as the source of sensation, which brings into action 
 the first series of muscles — not a. few in number ; 
 the sensation which results from their contractioii 
 must be considered as the immediate cause of the 
 
11') OF SENSATION AS A CAUSE OF 
 
 contraction of the antagonising muscles, by which 
 the sudden revulsion is produced. The last part 
 of the act of deglutition, or the transmission of the 
 bolus through the gullet into the stomach, is the 
 most simple of all, and takes place, perhaps, with.out 
 any sensation, merely by the stimulus of the mass 
 on the irritability of the muscular fibres, which enter 
 into the structure of the tube. 
 
 \^omiting is another act dependent upon sensa- 
 tion, the origin of which is not so simple as in the 
 former cases, since it takes place under a variety 
 of circumstances, such as the introduction of cer- 
 tain substances into the stomach, tickling the throat 
 with a feather, injecting an emetic solution into a 
 vein, and many others ; still it will not take place 
 under the operation of any such cause, if the ence- 
 phalon be in a state of lesion or of deep stupor, and 
 accordingly Magendie found that vomiting is im- 
 mediately put a stop to by compressing the me- 
 dulla oblongata. ^Vhether, then, it be the medulla 
 oblongata alone, or whatever other part of the ner- 
 vous centre may be the immediate seat of the phy- 
 sical part of this sensation, it is allowed in physiology 
 that such is the cause of vomiting. But vomiting 
 consists not of a mere contraction of the stomach, 
 nay, in perfect vomiting the stomach itself is pas- 
 sive, while a multitude of muscular organs are called 
 into activity ; and how should these be brought 
 into motion? No other answer can be given but. 
 one similar to that offered in the former case, 
 
MOTION IN ANIMALS. 117 
 
 namely, that it is an established law in the economy 
 of animals, that as often as a certain sensation ori- 
 ginating in a peculiar stimulus arises, it is succeeded 
 by the transmission of a nervous power through 
 motor nerves to a definite number of muscular 
 organs, which are in consequence called into action, 
 and produce the evacuation of the stomach. This 
 automatic act deserves particular attention, as illus- 
 trative of proper instinctive operations, on o.ccount 
 of the number of separate muscles called into 
 action ; its complexity is so great, that it does not, 
 like many others, bend to the will even in man. 
 Perfect vomiting is produced in the following 
 manner : — The diaphragm, or midriff, which is in 
 contact with the upper surface of the stomach, by 
 the powerful contraction of its muscular fibres under 
 the influence of the phrenic nerve, descends and 
 remains for a moment fixed in this position, while 
 the muscles which shut the aperture of the wind- 
 pipe and those of the abdomen, act with a simul- 
 taneous and convulsive effort ; so that the air being 
 retained in the lungs, the ordinary effect of the 
 action of the abdominal muscles, namely, the ex- 
 pulsion of the air from the lungs by the diminution 
 of the chest, is prevented, and the whole force of 
 these powerful instruments is made to bear on the 
 stomach, still pressed on from above by the dia- 
 phragm, and thus that organ is evacuated instead 
 of the lungs. Hence the motor influence trans- 
 mitted from the nervous centre, as a consequence 
 of the previous sensation, is not confined to the 
 
118 OF SENSATION AS A CAUSE OF 
 
 plnonic nenT, but equally affects the nerves of the 
 laryngeal muscles, of those of the abdominal mus- 
 cles, and those which act simultaneously with the 
 litter. 
 
 The evacuation of the bowels and bladder takes 
 j;lace in infants and undomesticated animals on a 
 plan altogether similar. A local irritation affects 
 the sentient extremities of their nerves ; a sensation 
 follows, which is succeeded by a transmission of 
 motor power to the diaphragm and abdominal mus- 
 cles, which contracting expel the contents of the 
 organs. In infants the former operation is effected 
 altogether independently of volition, though not 
 without consciousness, which must exist both from 
 the irritation produced on the nerves of the bowel 
 by the distension of its cavity, and also from the 
 contraction of the several muscles, as those of the 
 abdomen and diaphragm, by which the organ is com- 
 pressed, and the resistance of its sphincter overcome. 
 But no one will deny but that if any unusual impe- 
 diment occur to the evacuation of the rectum, the 
 infant will suffer pain and become acutely sensible 
 of the presence of an irritation, in the degree in 
 which its intensity increases ; or, which is the same 
 thing, in proportion to the vividness of the sensa- 
 tion. What room, then, is left for denying that this 
 act is dependent upon a sensation ? Yet in it we 
 discover the simultaneous action of many muscles, 
 not only of the diaphragm and of the ordinary mus- 
 cles of expiration, as those of the abdomen and 
 
MOTION IN ANIMALS. 119 
 
 loins, but also of the pelvic muscles, and more par- 
 ticularly of one of them, the levator ani. The pro- 
 gress of this operation as the child increases in age, 
 from a pure antomatic to a voluntary act, gives an 
 additional illustration of the dependence of such 
 muscular combinations upon sensation. The nurse 
 soon discovers when this act is about to take place ; 
 and by what signs? surely by no other than such 
 as indicate that her charge is conscious of the first 
 approaches of sensation, which, as it grows in inten- 
 sity, will quickly enforce tlie action over which it 
 presides. To trace the steps by which it becomes 
 a voluntary act does not belong to our present pur- 
 pose ; but it can easily be conceived that, within 
 certain limits, an act which is accomplished from 
 the first by muscles destined to be under the con- 
 trol of the will, may be suspended for a time by an- 
 tagonising m.uscles, equally under the dominion of 
 the same power. 
 
 What has been said of the evacuation of the rec- 
 tum applies very closely to that of the bladder. 
 There is a similar irritation of the nerves of the 
 organ, and the action of as many muscles conse- 
 quent upon the sensation thence originating, and 
 the same progress from a mere autom.atic act to a 
 voluntary effort, and that progress accomplished by 
 means wholly similar. It is well known that boys, 
 long after the time when the evacuation of the 
 bladder has become a voluntary effort, are sometimes 
 subject to an involuntary discharge of its contents. 
 This state hardly amounts to disease, but depends 
 
120 OF SENSATION AS A CAUSE OF 
 
 upon an unusual and temporary susceptibility of the 
 nerves of the organ to the stimulus of distension ; 
 so that, when this has once reached a certain pitch, 
 the action of the antagonising muscles is of no avail, 
 and the law established between the sensation re- 
 sulting from that distension and the generation of 
 motor power enforces instant obedience. It is com- 
 monly thought that these circumstances are to be 
 overcome by punishment ; yet unless the principle 
 upon which punishment operates be strictly kept in 
 view, the unfortunate boy may often, as indeed he 
 often is, be subjected to unavailing cruelty. Pun- 
 ishment can only operate by awakening attention 
 to the first approaches of the sensation ; so that the 
 child may anticipate, by an act of will, that degree 
 of distension which enforces the sequence, and 
 which, w^hen it has arisen, no effort of the will, even 
 under the dread of punishment, is adequate to re- 
 sist. 
 
 The process of parturition affords another instance 
 of the dependence of muscular acts on definite sen- 
 sation ; but on this we shall not enlarge, and here 
 also we close our illustrations, observing that al- 
 though the acts which we have described, and many 
 analogous to them which we might have adduced, 
 agree with proper instinctive acts, in so far as they 
 depend upon sensation ; yet there remains a cir- 
 cumstance, which, for the sake of distinction, must 
 be made a ground of difference ; and that is, they 
 are concerned in the assimilative functions, — in 
 
MOTION IN ANIMALS. 121 
 
 functions which end in the body itself, while those 
 which are properly termed instinctive, as was be- 
 fore remarked, appertain to the functions of rela- 
 tion. 
 
 Such, then, is the general character of the ex- 
 planation of these actions of the living body, af- 
 forded by the doctrine that sympathies operate 
 through the nervous centre. That some objections 
 may be taken to this view is undeniable. These, 
 however, evidently result rather from our imperfect 
 knowledge of the nervous system, and of the actions 
 dependent on it, than from any thing wrong in the 
 principle itself on which the doctrine rests. To 
 say that time will make no change in the explana- 
 tion we have offered of the phenomena referred to, 
 is the same thing as to assert that no further pro- 
 gress will be made in the discovery of the laws 
 which regulate the operations of the nervous sys- 
 tem and other functions of the body. While, how- 
 ever, the subordinate details, and even the language 
 in which the theory is expressed, will undergo a 
 change corresponding to the course of improve- 
 ment in physiology, there is no ground for the 
 apprehension that the essential character of the 
 theory will be proved to be erroneous, or that 
 the inferences drawn from it by analogy, or other- 
 wise, will not continue applicable in effect, if not 
 in language, to other phenomena. It is very short 
 sighted policy in science, to refuse a theory merely 
 
122 or SENSATION AS A ( ALSE OT 
 
 because there may be reason to suspect that in 
 after times, from the advance of know ledge, it will 
 r.ot retain tlie same character. This is to put on 
 effectual sto}) to all improvement. Every theory 
 which reduces to one principle a number of seeming- 
 ly discordant and diversified phenomena — for such 
 a princii)le cannot be lost or overthrown, whatever 
 change may occur, — claims in science to be received 
 as a truth. It may require to be remodelled, it 
 may change its name, it may seem to be reversed, 
 yet it cannot be divested of its original character, 
 provided it once answered the description now re- 
 presented to belong to the doctrine in question. We 
 may rest assured, that the principle under considera- 
 tion will remain essentially unchanged, however 
 much altered and modified in language by future 
 improvements in the science ; and this principle, 
 in its most simplified condition, may be stated to 
 be, that an impression, made on the extremities of 
 certain nerves in the first link of a chain of causes, 
 generates, through the nervous centre, motion in 
 muscular organs ; and this doctrine, since it first 
 appeared in the works of physiologists, while it re- 
 mains unchanged in reality, has already undergone 
 several alterations in its details — an index to what 
 new forms it is still destined to assume. Some ves- 
 tiges of it occur in the works of Astruc, Van Swie- 
 ten, and Haller, but it assumes a more definite and 
 extended form in the writings of Whytt, the pre- 
 decessor of Cull en in the Chair of Medicine in the 
 University of Edinburgh. It may be worth while 
 
MOTION IN ANIMALS. 123 
 
 to give an example of his mode of applying it to 
 some of the actions of the body in contrast with 
 the views we would take, and those found in the 
 writings of its chief advocates in modern times, Ali- 
 son, Broussais, Georget, and Roux. The follow- 
 ing passage shews the reasoning of Whytt on the 
 application of the doctrine to the function of respi- 
 ration, from which it will at once appear how much 
 recent improvements in physiology have served not 
 to change the principle, but to simplify its applica- 
 tion : — " It may be asked how a stimulus or uneasy 
 sensation in the lungs, can affect the inspiratory 
 muscles with which they seem to have no imme- 
 diate connection ; I should answer, it were easy to 
 ascribe this effect to a sympathy between their 
 nerves ; a phrase, indeed, oftener used than well 
 understood ! but, as the pulmonic plexus has no 
 greater connection or communication with the phre 
 nic nerves and those which supply the intercostal 
 muscles, than with the nerves of the stomach, in- 
 testines, and other abdominal viscera, which are no 
 ways affected by the gentle stimulus of the blood, 
 as it passes through the pulmonary vessels ; I think 
 Me cannot fairly ascribe the motions of the respira- 
 tory muscles to any sympathy proceeding from a 
 connection or communication between their nerves 
 and those of the lungs. Further, as the nerves of 
 the inspiratory muscles and lungs most certainly do 
 not terminate precisely in the same part of the 
 brain, but probably in places somewhat distant from 
 each other, any sympathy that obtains between 
 
124 OF SENSATION AS A CAUSE OF 
 
 them as proceeding from one common origin, must 
 be owing to something equally present in these 
 several places, i. e. to the mind or sentient princi- 
 ple ; for, without supposing some percipient being 
 in the brain, how can an irritation of tlie extremi- 
 ties of the nerves taking their rise from one part of 
 that organ, occasion a more than ordinary deriva- 
 tion of spirits, into such nerves as have their origin 
 from a different part ? If external objects act on 
 the nerves only by putting a stop to the equable 
 progression of their fluids, or by exciting some vi- 
 bratory motions in them, how can any of these oc- 
 casion not only a more copious derivation of spirits 
 through the nerves thus affected, but also through 
 a great variety of other nerves with which they have 
 no connection, and whose rise is from a different 
 part of the brain ? The sympathy, therefore, or 
 consent observed between the nerves of various 
 parts of the body, is not to be explained mechani- 
 cally, but ought to be ascribed to the energy of that 
 sentient being which, in a peculiar manner, displays 
 its powers in the brain, and by means of the nerves, 
 moves, actuates, and enlivens the whole machine. 
 
 " But further, if the sympathy observable be- 
 tween different parts of the body be wholly owing 
 to the connection or communication of their nerves, 
 how comes the pupil to be contracted by the action 
 of light on the retina, when the nerves of the uvea 
 have not only no communication with the optic 
 nerve, but arise from a pretty distant part of the 
 brain ? or, if there w ere some general sympathy 
 
MOTION IN ANIMALS. 125 
 
 between the nerves, why should not the longitu- 
 dinal fibres of the uvea be contracted as well as the 
 orbicular ones, and the coarctation of the pupil pre- 
 vented ? If the alternate contractions of the inspi- 
 ratory muscles were owing merely to their receiv- 
 ing a few nervous twigs from the intercostals which 
 furnish the plexvis pulmonicus, why is not the heart 
 and alimentary canal equally affected with them by 
 a stimulus or uneasy sensation in the lungs ? Why 
 are not the intercostal muscles as much convulsed 
 in vomiting as the diaphragm and abdominal mus- 
 cles ? and why, upon an irritation of the membrane 
 of the nose and trachea, are not the abdominal mus- 
 cles contracted, till the inspiratory muscles begin to 
 be relaxed ? These questions will scarce be an- 
 swered satisfactorily, upon any scheme of sympathy 
 depending ivholly upon the communication or con- 
 nection of nerves ; but have no difficulty in them, if 
 the motions now mentioned be referred to the mind 
 or sentient principle. 
 
 " When, therefore, in consequence of a disagree- 
 able sensation in the lungs, arising from the difficult 
 passage of blood through their vessels soon after 
 expiration is finished, the inspiratory muscles are 
 contracted, we are not to ascribe this to any un- 
 known sympathy acting mechanically upon these 
 muscles or their nerves, but to the mind or senti- 
 ent principle, which, being affected by the uneasy 
 perception in the lungs, is thereby excited to in- 
 crease to action of the nervous influence upon the 
 abdominal muscles and diaphragm, by which the 
 
126 or SENSATION AS A CAUSE OF 
 
 cavity of the tliorax being enlarged, and the lungs 
 inflated with fresh air, the disagreeable sensation 
 in them is removed, and consequently the extra- 
 ordinary contraction of the inspiratory muscles 
 ceases ; hence, by the reaction of the elastic carti- 
 lages of the ribs, abdominal muscles, &c. the cavity 
 of the thorax is lessened, /. e., inspiration is natu- 
 rally followed by expiration ; which again must 
 soon be succeeded by a new inspiration, on account 
 of the particular sensation which begins to arise in 
 the lungs." — Essay on Vital and Involuntary Mo- 
 tions. Whytt's Works, 4to, p. 97. 
 
 We have here all that is essential in the princi- 
 ple of the explanation, while, in several respects, 
 the details are in fault. It is true that the blood 
 does not pass so freely through the lungs, when in 
 the state produced by expiration ; which fact gives 
 rise to the supposition of a compression of their 
 nerves being the source of their sensation. But 
 the improvements which the advance of chemical 
 science has made on our knowledge of the function 
 of respiration, more particularly as respects the 
 change of the blood from the venous to the arterial 
 state in these organs, aifords at once a more intel- 
 ligible source for the sensation, while it explains 
 at the same time the reason why the activity of 
 the respiratory apparatus keeps pace with every 
 increase in the heart's action. W^e are, moreover, 
 now able to point out the precise part of the ner- 
 vous centre, namely, the medulla oblongata, on 
 which this impression acts. And besides, it may 
 
MOTION IN ANIMALS. 127 
 
 be regarded as established, that the mental feeling 
 or consciousness of the impression is not essential 
 but contingent ; that is, it accompanies the physi- 
 cal change which we must believe to occur in the 
 medulla oblongata, when the animal is awake and 
 free from coma, but is dispensed with in the oppo- 
 site states. It is not easy to predict how many im- 
 provements on the doctrine as explained above, 
 equally important with those made on it since 
 Whytt's time, physiology may have yet in reserve ; 
 indeed, it is not improbable that it is on the eve of 
 a great and most important modification ; and it 
 may be observed, that the theory before us had 
 nearly reached its present state before the signal 
 discoveries of Sir Charles Bell of the different func- 
 tions of the different nerves, and the tracts of the ner- 
 vous centre from which they respectively originate. 
 The doctrine of a sensitive and motor tract and 
 corresponding nerves must be regarded as fully 
 established, and, in a great degree, reconcilable 
 with the theory under consideration. But, with 
 respect to the respiratory tract and the correspond- 
 ing nerves, great difficulties still exist ; and, for 
 this reason, we have not attempted to consider the 
 actions which we have been reviewing, in connec- 
 tion with that supposed distinct part of the nervous 
 system. If, however, the labours of anatomists and 
 physiologists shall distinctly establish the existence 
 of the respiratory tract, a great modification of this 
 theory will most probably be required — indeed a 
 total change of the language employed in express- 
 
128 OF SENSATION AS A CAUSE OF 
 
 ing it, still, as we cannot but persuade ourselves, 
 without any detriment to the great principle — 
 namely, that such acts as we have described, de- 
 pend upon impressions on the extremities of one 
 nerve or set of nerves, operating upon other nerves 
 througii the medium of the nervous centre, whe- 
 ther the intermediate step be found to consist in 
 sensation or in any other kind of process. And in 
 this we must differ in opinion with our much la- 
 mented friend and preceptor the late Dr Fletcher, 
 who, overlooking the identity of principle between 
 Whytt's doctrine and that which he himself incul- 
 cates, has failed to do full justice to its merits. 
 A brief outline of that view we will offer ; we have 
 not adopted it, partly because the conclusions as to 
 the respiratory nerves are yet very doubtful, and 
 partly because, even supposing those of sufficient 
 probability, it would be difficult to make them suf- 
 ficiently clear for their popular application to the 
 subject of instinct. But if these views are suffi- 
 ciently established, it is but a change of language 
 that is required to reconcile them with the theory 
 before inculcated, and its application to the whole 
 range of instinct. The view, then, which Dr Flet- 
 cher has adopted, is, that sympathies and instinc- 
 tive actions are dependent on the respiratory sys- 
 tem of nerves. Much difficulty occurs on the very 
 threshold of this doctrine, from the discordant opi- 
 nions of anatomists as to what are and v,hat are not 
 respiratory nerves, and the no less discordant views 
 of physiologists as to the acts in which they are 
 
MOTION IN ANIMALS. 129 
 
 concerned. If, however, the pneumo-gastric nerve 
 be assumed to be a respiratory nerve, we must ad- 
 mit that the ramifications of that system spread to 
 nearly every organ of the body; there being no 
 difficulty in the belief that that nerve, while it is 
 directly transmitted to the larynx and pharynx, 
 windpipe, gullet, lungs and stomach, is, by its com- 
 munications with the cardiac and splachnic ganglia^ 
 spread to the liver, spleen, bowels, kidneys, bladder, 
 and uterus ; and through the branches of the gan- 
 glionic system, with which it so fi-eely communicates, 
 over the muscular system of the extremities and other 
 merely muscular parts. It may be supposed, then, 
 that the apparatus of the functions above explained 
 on the views of Whytt, are supplied from this re- 
 spiratory nerve. The impressions, therefore, such 
 as that of the venous blood in the capillaries of 
 the lungs, the stimulus of cold on the surface, the 
 irritation of foreign substances in the air-passages or 
 nostrils, the presence of aliment in the fauces, the 
 impression of emetics on the stomach, the irritation 
 of feculent matter on the bowels, and of urine in 
 the bladder, are conveyed to the respiratory tract 
 of the nervous centre, and that an affection of it is 
 the immediate antecedent of the transmission of 
 motor power through proper nerves to the muscu- 
 lar organs concerned in the several acts with which 
 such irritations are connected. The following pas- 
 sage from Dr Fletcher will shew that such is the 
 view which he wishes to inculcate : '• Thus be- 
 tween the lungs and respiratory muscles, the sym • 
 I 
 
130 OF SENSATION AS A CAUSE OF 
 
 pathy seems to be maintained by the pneiimo-gas- 
 tric nerve, with which the former are furnished, 
 being associated, at its origin, with the roots of the 
 abdominal nerves, so that the primary irritation 
 calling for the expiratory process excites the abdo- 
 minal and lumbar muscles to action, more or less 
 violent in proportion to its intensity. And with 
 respect to the sympathy between the lungs and re- 
 spiratory muscles, the pneumo-gastric nerve is as- 
 sociated at its origin with the roots of the intercos- 
 tal and phrenic nerves, so that when the primary 
 irritation calling for the inspiratory process is mo- 
 derate, the intercostal muscles and diaphragm alone 
 are excited ; with those of the accessory and exter- 
 nal respiratory nerves, so that, when this primary 
 irritation is more severe, the muscles on the front of 
 the neck also, and sides of the chest, are called into 
 action ; and with those of the pathetic, facial, and 
 glosso-pharnygeal nerves, so that, on this primary 
 irritation becoming intense, many of the muscles 
 of the eyelids and eyebrows, nostrils, face, and 
 throat, are involved in the general perturbation. 
 The sympathy, again, which subsists between the 
 diaphragm and the muscles which depress the lower 
 jaw, seems to depend upon the associations, at their 
 origins, of the phrenic and facial nerves ; between 
 the stomach and diaphragm, of the pneumo-gastric 
 and phrenic, and between the nostrils, larynx, eye, 
 &c., and the abdominal muscles, respectively, of 
 the facial, pneumo-gastric, and pathetic, and the 
 abdominal nerves. Upon the same principle, the 
 
MOTION IN ANIMALS. 131 
 
 sympathy between almost every other organ of the 
 body and the heart, seems to be maintained by the 
 respiratory nerves which are supphed to these or- 
 gans, being associated at their origins with the 
 pneumo-gastric ; that between the nostrils and la- 
 crymal gland by a similar association of the facial 
 and pathetic ; that between the mouth and salivary 
 glands of the facial, glosso-pharyngeal, and pneumo- 
 gastric ; that between the fauces and stomach, of 
 the glosso-pharyngeal and pneumo-gastric; and 
 that between almost every other part of the body 
 and this latter organ, of numerous other respiratory 
 nerves and the pneumo-gastric. So, also, between 
 the rectum and urinary bladder, and the abdominal 
 muscles, the sympathy may be presumed to be 
 effected by the association, at their origins, of the 
 pneumo-gastric and abdominal nerves ; that between 
 the choroid coat and iris upon a similar association 
 of different parts of the pathetic nerve ; and that 
 between the ear and gums, of the different portions 
 of the facial. Lastly, the integuments of the arm- 
 pit, or sole of the foot, appear to extend a sympa- 
 thy to the expiratory muscles, and indeed to almost 
 all the muscles of the trunk and limbs, by the asso- 
 ciation of the pneumo-gastric — connected, as it 
 may be presumed everywhere to be, with the seve- 
 ral ganglionic nerves going to the surface of the 
 body — and the abdominal and numerous other 
 nerves of the same system. With respect, again, 
 to passion or instinct, the primary action constitu- 
 ting which is always in the brain, and immediately 
 
l'A'2 OF sp:\sation as a cause of 
 
 coniniunicated, we must suppose, to the respiratory 
 tract, we have only to find a nerve tending fron? 
 tliis part to the organ Mhich is to displny the se- 
 condary irritation, in order to explain its transla- 
 tion by this system of nerves; and that such a 
 nerve may be always, either directly or indirectly, 
 traced to every organ liable to be so acted on, may 
 be easily inferred from what has preceded." (Hu- 
 diments of Physiolor/y, hy Dr Fletcher, part ii. /3, 
 p. 40.) There is some ambiguity in the expression 
 '• associated at their roots," as it may be designed to 
 teach the ordinary opinion that sympathies depend 
 on the communications between nerves subsequent- 
 ly to their detachment from the nervous centre ; 
 but that this is not referred to, appears from the 
 following expression in speaking of respiration, — " In 
 these cases, the translation of the sympathy is from 
 the lungs, through the common centre of the respira- 
 tory system of nerves, to the muscles in question.'' 
 {Note, p. 40.) It seems obvious, then, that this 
 view — at least when it is remembered that con- 
 sciousness of the impression is not considered in 
 Whytt's system, as taught by Alison and other 
 physiologists of our time — is no more than a modi- 
 fication of the older theory, such as the discovery 
 of a new region of the nervous centre must de- 
 mand; for, to repeat what was said before, the 
 theory, as we would inculcate it, had reached a cer- 
 tain maturity before the doctrine of a respiratory 
 tract was taught, and all that appears essentially to 
 belong to it is, that impressions made on the ex- 
 
MOTION IN ANIMALS. 133 
 
 tremities of one nerve operate upon organs of mo- 
 tion through the nervous centre, and not through 
 mere inosculations of nervous branches between 
 the nervous centre and the parts concerned. And 
 this principle, as it was termed in the previous part 
 of this chapter, manifestly pervades and constitutes 
 the essence of both views. While, however, there 
 is this obvious identity of principle in both, it is not 
 therefore immaterial which is adopted. We are 
 bound to follow that which, in the existing state of 
 our knowledge, is attended with the smallest num- 
 ber of difficulties, while it explains the phenomena 
 in an equal degree ; and in these respects it does 
 appear to us, that the older view still maintains an 
 advantage. The variety of opinions, indeed, held 
 with respect to the powers of the respiratory nerves, 
 and the particular nerves which rank as belonging 
 to that system, as before noticed, renders it impos- 
 sible to make use of any function assigned to them 
 just now, as an illustration of any other set of ner- 
 vous actions ; which, it is to be remembered, is al - 
 together the purpose of the present chajTter. How 
 far this is the case, will appear from the following 
 short summary of the subject. The respiratory 
 nerves, in Dr Fletcher's table, are the pathetic, the 
 facial, the glossopharyngeal, the pneumogastric, the 
 accessory, the phrenic, and the external respi- 
 ratory. But the pathetic is still regarded as a sim- 
 ple motiferous nerve by Mayo, Earle, Arnold, and 
 Panizza, while, by Bellengeri and Walker, it is 
 iicmsidered at once a vehicle of sympathy and in - 
 
134 OF SENSATION AS A CAUSE OF 
 
 stinct. The glossopharyngeal is regarded by Earle 
 and Panizza as sensiferous, the latter representing 
 it as the nerve of taste ; by Mayo, as in some of its 
 filaments regular, in others sensiferous only; while 
 according to Bellingeri and Walker, it partakes of 
 the compound character of the facial. The sanu- 
 is supposed to be the case vv^itli the pneumogastric : 
 while it is by Mayo accounted a regular nerve ; and 
 by Rolando, Brachet, Earle, and Arnold it is re- 
 garded as simply sensiferous, inasmuch as it is sup- 
 posed to convey certain irritations from the viscera* 
 to the sensorium, so as to occasion the sensations 
 giving rise to the desire to breathe, to eat, and the 
 like. Such discordant views with respect to this^ 
 supposed system of nerves, renders it altogether 
 imwarrantable to found any conclusions by analogy 
 upon their mode of action. 
 
 But even suppoing an agreement to exist among 
 anatomists and physiologists as to what nerves be- 
 long to the respiratory tract, and what do not, ano- 
 ther important difficulty has to be solved in the in- 
 quiry what is their kind of action ; whether it be 
 all of one kind as the conveyance of impressions tor 
 the nervous centre fi'om distant parts or the trans- 
 mission of specific motor power ; or whether, com- 
 bining functions analogous to the functions of the 
 two other kinds of nerves jointly, they both con- 
 vey impressions to the nervous centre, differing 
 from those conveyed by the sensitive nerves, in 
 that they do not produce consciousness, while at the 
 same time they, or at least nerves belonging to the 
 
MOTION IN ANIMALS. 135 
 
 same system, transmit motor power to muscular 
 organs. If it be contended that their function is 
 that of specific motion, as exemplified in the pathe- 
 tic and facial, and on a superficial view, supported 
 by the resemblance of their structure to that of the 
 motor nerves, and by the analogous effect of gal- 
 vanism on them — then on what principle can they 
 be supposed to be concerned in sympathetic action? 
 for that can only take place through nerves capa- 
 ble of transmitting impressions from their extre- 
 mities either to their roots, or at least towards their 
 roots, as far as the supposed points of inosculation 
 with the nerves through which such impressions are 
 to be conveyed to the organs where the effect of the 
 sympathy is displayed. If, on the other hand, it 
 be contended that their power is in particular that 
 of transmitting impressions ; or, that their function 
 resembles that of the sensitive nerves, with this 
 difference, that no consciousness follows the physi- 
 cal change produced through them in the nervous 
 centre, and the most obvious part of the function 
 of the pneumogastric nerve might bear out this 
 view — what becomes of the whole beauty of the 
 supposed discovery, or what becomes of the system 
 of respiratory nerves deprived of its brightest orna- 
 ments ? — the pathetic or respiratory of the eye, and 
 the portio dura or lesser sympathetic, the respira- 
 tory of the face, not to speak of the phrenic or great 
 internal respiratory, the accessory or respiratory of 
 the neck, and the nerve of the great serratus or 
 respiratory of the trunk, all of which are undeni- 
 
136 MOTION IN ANIMALS, 
 
 ably nerves of mere motion ? But let us suppose 
 for a moment further, that this power of transmit- 
 ting impressions from their extremities to the ner- 
 vous centre, unaccompanied by any consciousness, 
 is the characteristic property of the respiratory 
 nerves, unaccompanied by consciousness, we repeat, 
 — for if consciousness attends this operation, what are 
 they but nerves of sensation ? — by what additional 
 apparatus is it that we are conscious of an uneasy 
 leeling in the chest, when the venous blood, the 
 proper stimulus, by hypothesis, of the extremities 
 of the pneumo-gastric, accumulates too largely ; of 
 another, when any thing irritates the membranes 
 of the air-tubes simultaneously with the production 
 of cough ; of another, when snuff irritates the mem- 
 brane of the nostril at the moment of sneezing ; of 
 nausea, or a peculiar sensation referred to the sto- 
 mach, which reaches its height at the instant of vo- 
 miting ; of an irritation in the rectum, and in the 
 bladder, growing in intensity up to that moment 
 when the force of the natural stimulus overpowers 
 the will, and commands the instant evacuation of 
 these cavities ? 
 
 It is time, however, without insisting more on 
 the comparative merits of these two views, to pro- 
 ceed to what is more immediately the object of the 
 treatise, namely, the subject of sensation as a course 
 of instinctive acts, and to which what we have al- 
 ready said forms an appropriate, though somewhat 
 lengthy, introduction. 
 
( 137 ) 
 
 CHAPTER VIII. 
 
 THE NATURE OF INSTINCT. 
 
 As, then, certain organic acts are the direct ef- 
 fect of sensation, so it will be found that instinctive 
 acts, pro perly so c all^dj ^^ ^>p tracprt to thf. sflmc 
 cause, and are, li ke them, dependen Lpi^her on ^^v^. 
 ternal or internal stimuli. It will be advisable to 
 point out, m this place, some of the sources of sen- 
 sations which become the cause of these phenome- 
 na,] the most perfect and least equivocal of which 
 are the special senses, — Sight, Hearing, Smell, Taste, 
 and above all. Touch. But besides these there are 
 sensations which acknowledge an internal cause, 
 such as those which accompany hunger, thirst, the 
 sexual propensity, a general feeling of a want, and 
 the like. To these are to be added sensations of 
 
 the impressions made on the sentient extremities 
 of nerves give origin to sensations of the most ob- 
 vious and simple kinds, the seat of which is un- 
 doubtedly in the cerebro-spinal axis — so many 
 objects of consciousness, as remembered emotions 
 and passions, the immechate seat of which, as will 
 
138 THE NATURE OK INSTINCT. 
 
 be seen hereafter, is most probably the brain itself, 
 are to be considered in like manner as the source 
 of sensation, an influence being transmitted, as in 
 the former case, through the nerves, so in the latter 
 from the cerebrum ; and in regard to some kinds 
 of such feelings from the cerebellum to the cerebro- 
 spinal axis, the exclusive seat of sensation. 
 
 Jnstinctive acts, then, in the animal kingdom, it 
 being understood those at present referred to are of 
 a relative kind, may perhaps be divided into those 
 which are momentary in dumtion and ihose. which 
 continue, or seem to continue, for an indefinite 
 pe riod wi thout an y very apparent re newal of their 
 cause. Those of the first description are very 
 closely allied to the automatic acts of which notice 
 has already been taken, and the theory of them is 
 comparatively easy; while those of the second de- 
 scription present a greater difficulty when we come 
 to seek a solution of their phenomena. 
 
 Let us begin, then, with some examples of those 
 of the first kind, so that we may lay some founda- 
 tion for the attempt to give a satisfactory explana • 
 tion of those of the second. 
 
 A remarkable instinctive act of the first kind 
 presents itself in the exercise of sight in man and 
 in other animals, the eyes of which are similarly 
 constructed, when the pupil accommodates itself, 
 by a change of diameter, to the greater or smaller 
 quantity of light which happens to be present at 
 any time. When the light is intense, or the bodies 
 presented to the eye highly illuminated, the pupil 
 
THE NATURE OF INSTINCT. 139 
 
 contracts in diameter, while, in the contrary cir- 
 cumstances, as in the ordinary darkness of night, it 
 expands much beyond its usual diameter in the day 
 time. It is found that this variation of diameter is 
 not dependent on any direct effect of light on the 
 iris itself, but that it results altogether from the kind 
 of impression made by it on the retina, or expansion 
 of the optic nerve, the ultimate seat of vision in the 
 eye. For, when the retina or optic nerve becomes 
 diseased and unfit to transmit the impression of 
 light to the nervous centre, the pupil remains di- 
 lated and immoveable, although its own structure 
 remains of the most healthy character. y^The con- 
 traction, then, of the pupil, proportionate to the 
 intensity of the light present, is an instinctive act 
 even in man, and takes place in the following man- 
 ner : — The impression made by the stimulus of 
 light on the retina, is transmitted according to the 
 ordinary law of sensation to the optic tubercles, 
 that part of the nervous centre on which the sen- 
 sations connected with vision depend, and a sensa- 
 tion takes place which is proportioned in intensity 
 to the intensity of the impression giving birth to 
 it, just as that is proportioned to the intensity of the 
 light transmitted through the eye to the retina. 
 But this sensation, more or less intense as it may 
 be, is succeeded, in obedience to the general law 
 of such sensations already explained, by a trans- 
 mission of motor power through the sixth pair of 
 nerves, a filament of which joins the ciliary nerves 
 in the lenticular ganglion, and these are traced to 
 
140 THE N ATI' HE OF INSTINCT. 
 
 the iri^ in the middle of wliich tlie pupil is, — and 
 by this motor power the circular or sphincter mus- 
 cular fibres of the curtain are made to contract, 
 and the pupil, consequently, to close its aperture to 
 an extent proportionate to the amount of motor 
 power transmitted, as that is to the original sensation. 
 A very remarkable action similar to this is seen in 
 the singular eye of the Surinam sprat, a reptile ca- 
 pable of adapting its eyes to reflect rays transmitted 
 either by air or water ; the refracting power re- 
 quired is different in tliese two cases, as any one 
 may satisfy himself by attempting to distinguish 
 minute objects placed in water, with his head like- 
 wise iiTimersed in this fluid. The reason that he 
 cannot do this is, because, though there is a suf- 
 ficient difference between the density of the hu- 
 mours of his eye and that of the air, to bring the 
 rays transmitted by the latter to a focus on the 
 retina, there is not a sufficient difference between 
 the density of these humours and that of water, to 
 do the same by rays transmitted by this fluid, so 
 that such rays are not brought to a focus sufficient- 
 ly soon. Hence divers, in some places, are in the 
 habit, when they descend into the water, of using 
 extremely convex glasses, in shape almost like the 
 lens of fishes, and turning their eyes by this means, 
 as it were, into those of an aquatic animal. But 
 how do reptiles manage this ? Not by using spec- 
 tacles, nor by increasing the density of their hu- 
 mours ; but by increasing the distance between the 
 cornea and retina- — which they effect by compress- 
 
THE NATURE OK INSTINCT. Ml 
 
 Ing the globe of the eye by proper muscles given 
 to them for that purpose — so that the rays which, 
 from the defective refracting powers of their humours, 
 would have otherwise formed a focus beyond the 
 retina, now form a focus ujmti it. When again in 
 the air they relax these muscles, and the retina 
 again approaching the cornea, still receives the 
 focus of the rays, which, as passing now through 
 air, are sufficiently refracted for the purpose. 
 
 Of the nature of instinct, or perhaps we should 
 rather say of the condition on which it takes place, 
 no better examples can be brought forward. Many 
 other instinctive motions belong to the exercise of 
 vision, more particularly the winking of the eye-lids 
 and the adjustment of the muscles, all of which may 
 be traced as consequences of definite sensations. / 
 
 With regard to Hearing ; the disposition to mus- 
 cular movements of the extremities, as of the hands 
 and feet, in unison with the time observed by mu- 
 sical instruments, should be regarded as of the 
 same description; it is seen in infants of a few months 
 old. Indeed from the earliest periods, the motions 
 of the hands as expressive of mental affections has 
 been a theme of admiration : " Caeterae partes," says 
 Quintilian, " loquentem adjuvant, hae (manus) 
 prope est ut dicam ipsae loquuntur."* 
 
 * " The whole art of the player consists in a delicate per- 
 ception of the effects of passion on the muscles of the eye, face, 
 larynx, trunks, and limbs, and in an accurate imitation of them, 
 by throwing into the same muscles the stimulus of volition, 
 while he at the same time counteracts, by similar means, the 
 expression of any emotion by which he may be actually excited." 
 —Fletcher. 
 
142 THE NATURE OF INSTINCT. 
 
 Ill quadrupeds, tlie inclination of the head and 
 ears in the direction from whicli sounds proceed, 
 are unquestionably instinctive and necessary in 
 many cases to their security. Hence a frequent 
 and rapid motion of the ears is, in all animals, with 
 justice regarded as indicative of a timid disposition. 
 An instinctive means of adapting the organ of hear- 
 ing to the medium in which sounds are conveyed, 
 analogous to the eye of the Surinam sprat, is met 
 with in the crocodile, ^^hich animal makes the first 
 approach to the well known appendage to the ear, 
 technically called the pinna ; being furnished with 
 a kind of external flap, with which it closes the 
 auditory apparatus. It is in this way probably that 
 the animal excludes too intense sounds when under 
 water ; but it appears that the greater number of 
 amphibious animals are capable of adapting their 
 auditory apparatus, at least partially, to the medium 
 in which they are, by putting all the parts upon 
 the stretch, by means of the proper muscles, when 
 in the air, so as to qualify them to receive slighter 
 impressions, and by throwing them all into a state 
 of relaxation when under water, so as to prevent 
 them from being stunned by more powerful ones. 
 
 The following passages from Why tt ( On Vital 
 and other hwoluntcvry Motions. Works — 4to. 
 p. 79.) afford some interesting speculations on the 
 effect of sensations on the muscular acts connected 
 with hearing. " As without the motions of the 
 pupil, the eye would have been ill contrived for 
 vision indifferent degrees of light and at different 
 
THE NATURE OF INSTINCT. 143 
 
 distances, so the ear would have been unfit for 
 hearing distinctly a diversity of sounds, were not 
 some of its parts capable of various degrees of ten- 
 sion. A musical chord of a determinate length 
 and tension, can only vibrate harmonically with one 
 particular sound ; if, therefore, there was no me- 
 chanism by means of which the membranes of the 
 tympanum and fenestra ovalis could be more or 
 less stretched or relaxed, they could only be har- 
 monically affected by one sound, which, therefore, 
 alone would be heard distinctly, and all others more 
 or less confusedly. To prevent this inconveniency, 
 the malleus is furnished with three muscles and the 
 stapes with one ; by the various contractions of the 
 former, the membrane of the tympanum, and by 
 means of the latter the membrane of the fenestra 
 ovalis, is rendered more or less tense, and so ac- 
 commodated to almost all possible sounds. 
 
 " It may well appear wonderful how the ear 
 should be so exactly adapted, by the various con- 
 tractions of these muscles, to such a vast variety of 
 sounds, but with what exquisite skill and amazing 
 wisdom is every thing in the animal frame adjust- 
 ed ! As the stimulus of light upon the retina and 
 the sensation of indistinctness in near objects excite 
 the mind to contract the pupil, so the less distinct 
 tremor of different sounds affecting the auditory 
 nerves is the cause of the subsequent contractions 
 of the muscles of the internal ear ; for no sooner 
 does the mind perceive the first indistinct noise of 
 any sound, but it instantly contracts some of the 
 
144 THE NATURE OF INSTINCT. 
 
 above muscles, so as most nicely to adapt to it the 
 membrane of the tympanum and fenestra ovalis ; 
 if the sound be acute, these membranes are just as 
 much stretched as is necessary for their vibrating 
 harmonically with it ; if it be flat, they are duly 
 relaxed ; and thus by a simple mechanism, the ear 
 is rendered sensible of the smallest variation of 
 sound or difference of notes in music. As infants 
 seem by habit to acquire a faculty, or at least a 
 greater dexterity, of adjusting their eyes by the 
 motions of the pupil and the crystalline humour to 
 the various distances of objects, so it is not impro- 
 bable that they may at first hear less distinctly, till 
 by degrees they come to acquire a power of readily 
 accommodating their ears more exactly to different 
 sounds. And is not the want of an ear (as it is 
 usually called) owing to a deficiency of this power ? 
 While that exquisite discernment of musical sounds 
 which many possess, shews that they can adjust 
 their ears to different notes with the greatest accu- 
 racy. 
 
 " That the motions of the muscles of the internal 
 ear proceed from the mechanical action of sound or 
 vibrating air on their fibres, the analogy of the 
 motions of the pupil would seem to contradict. 
 And if this were the case, why should not all the 
 muscles of the malleus be equally contracted by the 
 same sound ? And why should those which serve 
 to stretch the membrane of the drum be excited 
 into motion by acute sounds, while the muscle 
 which relaxes it is only brought into action by 
 
THE NATURE OF INSTINCT. 145 
 
 grave ones. As brute animals, upon the first per- 
 ception of any noise, turn their external ears to- 
 wards the place from whence it comes, so at the 
 same time they adapt their internal ear to it ; the 
 first of these motions cannot be denied to flow from 
 their sentient principle actuated by the sound, why, 
 then, should we doubt that the latter proceeds from 
 the same cause ? 
 
 " The motions of the muscles of the internal ear, 
 in consequence of various sounds, are not only un- 
 attended with any consciousness of volition, but are 
 altogether involuntary ; for we cannot move them 
 except when sound strikes the ear, nor hinder them 
 to act when it does." 
 
 But the great source of instinctive acts in the 
 lower animals, are the senses of Smell and Taste. 
 By these, particularly by the former, they are led 
 with unerring certainty to the selection of their 
 -food. Of herbs they reject such as are noxious, 
 while they select those which are salutary, with 
 a certainty which far exceeds the boasted know- 
 ledge of man : yet what is this but an original 
 connection between the muscular movement ne- 
 cessary for cropping the herbage and the sensa- 
 tions which the smell of it excites ? How wisely 
 adjusted to each other must be the two processes, 
 ^md how redolent of inferences of the goodness and 
 greatness of the Creator I but the animal kingdom 
 every where abounds with such, and innumerable 
 as they are, they are inadequate to impress us with 
 
14f) THE NATURE OP INSTINCT. 
 
 more than a fuint idea of the stupendous extent to 
 which these attributes are displayed. There is 
 scarcely a j)lant which is not refused by some while 
 it is eagerly sought after by others. The horse 
 rejects the common water-hemlock, on which the 
 goat luxuriates ; the cow refuses the long-leaved 
 water-hemlock, which the sheep is greedy for ; and 
 the goat will not touch the wolf's-bane, which the 
 horse enjoys. The Indian buceros devours with 
 avidity the nux vomica, so well known as poisonous 
 to dogs, rats, and most animals ; and the land-crab 
 feeds on the berries of the deadly manchineel tree. 
 The deer and the round-horned elk thrive on the 
 broad -leaved kalmia, which is poisonous to sheep, 
 horned cattle, horses, and man. From the flower 
 of the same plant, the bee draws honey, and man 
 finds death.* Parrots are poisoned by parsley, hogs 
 by pepper, and fowls, dogs, and foxes by sweet 
 almonds ; whereas fowls are uninjured by darnel, 
 and pheasants by stramonium, hogs thrive on hen- 
 bane., and storks, likr sheep and goats, on hemlock, 
 the last again are uninjured by tobacco. 
 
 Many sensations originating in the qualities of 
 the atmosphere at certain times, are the source of 
 instinctive actions, momentary as well as more con • 
 tinued. These are not less marked in animals, 
 than, from the same cause, are the effect of the 
 seasons upon vegetables. With the first appear- 
 ance of the renovating spring, the wood-lark renews 
 •its note, the thrush retunes his throat to melody, 
 * S:7tdllc,i. 3:Q. -Ilanvocky 24-. 
 
THE NATURE OF INSTINCT. 147 
 
 and the rook revisits its breeding-tree to make 
 choice of a nest for the approaching summer. 
 Flowers and trees acknowledge the glad influence 
 in their many tinted blossoms, their opening buds, 
 the bloom which is beauty, and the fruit-promising 
 blossom. The trouts, too, begin to rise in the 
 stream, and the water-fly skims along the surface 
 of the secluded pool, and, if the day be fine and 
 warm, the brimstone-winged butterfly issues from 
 the wood to enjoy the sunshine ; the ewe drops 
 her lamb ; the sparrow builds its nest ; and when 
 Hesperus glimmers o'er the southern hill, the bat 
 comes forth on restless wing to spend an hour in 
 dalliance with evening, till scared to its ivy bed bv 
 the darkening shades of night. As spring deepens 
 into summer, the air murmurs with exulting insects, 
 and bush and brake, " hymning their great God," 
 send forth their voice of melody. But as June 
 melts into July, the music of the groves makes a 
 pause, or is confined to the wren and a few tiny 
 companions. 
 
 Autumn, in like manner, exerts its peculiar and 
 proper influences, and among these none are more 
 remarkable than the instinctive acts evidenced in 
 the migrations of animals, — inducing them to under- 
 takings reason would not have dared to prompt, and 
 which volition vv?ould have been inadequate to ac- 
 complish ; few subjects are more interesting or 
 have called forth more notice ; to almost all they 
 are familiar, and the inspired seer found in them an 
 ilhistration suited to liis purpose : " The stork ip 
 
\A^ THE NATURE OF INSTINCT. 
 
 tlie heaven," says Jeremiah, " knoweth her appoint- 
 ed times ; and the tm-tle, and the crane, and the 
 swallow observe the time of their coming/' But 
 soon the cold night, and the shortening day, and 
 the declining sun, and the departure to warmer 
 climes of many a feathered visitant, and the fading 
 leaves tinting the woods with a varied livery, pro- 
 claim stern winter is at hand — that night of the 
 year when Nature sleeps and rests her from fatigue. 
 The sensations now imparted have called forth new 
 instincts in animals ; numerous tribes have provided 
 for themselves comfortable retreats, burrowing in 
 the earth, boring beneath the bark of trees or pene- 
 trating their natural hollows, lodging in crevices of 
 walls and rocks, or diving beneath the surface of 
 the water. Here some are preserved during this 
 period, either by feeding on the stores they have 
 collected during the bountiful weeks of harvest, or 
 by faUing into a deep sleep, during which they are 
 unassailed either by hunger or by cold. " Who 
 knoweth not in all these, that the hand of the Lord 
 hath ^vrought this" by the gift of an organization 
 enabling an animal to perceive the approaching, 
 changes of weather, which stimulate to acts depend- 
 ent on an established connection between the sen- 
 sations arising from the impressions made on their 
 delicate organs by variations in the humidity, dry- 
 ness, temperate, and electrical states of the atmo- 
 sphere, and the movements which they are observed 
 to perform. Animals are conscious long before 
 '"nan of the approaching storm, and prepare for its 
 
THE NATURE OF INSTINCT. 14fi 
 
 coming ; in the woodlands the birds hush their 
 song, in the meadows the flocks bleat in dismay, 
 and on the mountain side the lowing of the cattle 
 is wild and desolate ; but Dr Jenner, in his signs of 
 rain, giving as an excuse for not accepting the invi- 
 tation of a friend, well illustrates our position, and 
 spares us more remarks upon the subject : — 
 
 " The hollow winds begin to blow, 
 
 The clouds look black, the glass is low, 
 The soot falls down, the spaniels sleep, 
 And spiders from the cobwebs creep. 
 Last night the sun went pale to bed, 
 The moon in halos hid her head. 
 The boding shepherd heaves a sigh, 
 For see ! a rainbow spans the sky. 
 The walls are damp, the ditches smell ; 
 Closed is the pink-eyed pimpernel. 
 Hark! how the chairs and tables crack; 
 Old Betty's joints are on the rack. 
 Loud quack the ducks, the peacocks cry; 
 The distant hills are looking nigh. 
 How restless are the snorting swine ! — 
 The busy flies disturb the kine. 
 Low o'er the grass the swallow wings ; 
 The cricket, too, how loud it sings ! 
 Puss, on the hearth, with velvet paws, 
 Sits smoothing o'er her whisker'd jaws. 
 Through the clear stream the fishes rise, 
 And nimbly catch th' incautious flies; 
 The sheep were seen, at early light, 
 Ciopping the meads with eager bite. 
 Though June, the air is cold and chill; 
 The mellow blackbird's voice is still. 
 The glow-worms, numerous and bright, 
 illumed the dewy dell last night,; 
 
loO THE NATLHE OF INSTINCT. 
 
 At dusk the squalid toad was seen, 
 
 Hopping, crawling, o'er the green. 
 
 The frog has lost his yellow vest, 
 
 And in a dingy suit is dress'd. 
 
 The leech, disturbed, is newly risen 
 
 Quite to the summit of his prison. 
 
 The whirling wind:, the dust obeys, 
 
 And in the rapid eddy plays. 
 
 My dog, so altered in his taste, 
 
 Quits mutton-bones, on grass to feast; 
 
 And see yon rooks, how odd their flight 
 
 They imitate the gliding kite ; 
 
 Or seem precipitate to fall, 
 
 As if they felt the piercing ball. 
 
 'Twill surely rain." 
 
 All the acts we have just enumerated as occur- 
 ring in the animal kingdom, are in strict accord- 
 ance with impressions made on the nerves, and 
 founded neither on accident nor reflection. It is. 
 thus, as Shakespeare observes, — 
 
 " That when the dawn, in russet mantle clad. 
 Walks o'er the dew of yon high eastern hill, 
 
 « » « « » 
 
 The cock, that is the herald of the morn, 
 Doth with his lofty and shrill sounding throat 
 Awake '' 
 
 And it is from the same impression of light that the 
 greater part of the animal kingdom are stimulated 
 to activity with the approach of sunrise, while they 
 retire to repose as it sets ; and, as has particularly 
 been remarked of birds, if an eclipse occurs, they 
 still obey the impulse of sensation, retiring as dark- 
 ness comes on to return to their fluttering and chirp- 
 
THE NATURE OF INSTINCT. 151 
 
 ing as it subsides. Expecting the annular eclipse 
 on the 15th of May last year, we were wandering 
 in the ducal gardens at Mannheim on the Rhine. 
 In the full glare of sunshine that preceded the ap- 
 proaching phenomenon, the close thickets of the gar- 
 dens, overgrown with brush and underwood, were 
 redolent with songs poured from a thousand Httle 
 throats of the groves' sweetest choristers. But as 
 dimness threw her mantle on the earth, all was hush- 
 ed ; there was no sound save that of dreamy stillness 
 which the poet only hears, whispering to his soul 
 uneartlily words. For a few moments it continued, 
 feeding our hearts with fancies wild and strange. 
 But no sooner did dimness begin to deepen into 
 shade, and darkness, like that of evening, shed its 
 influence around, than the voice of the nightingale 
 burst upon our startled ear, " w^arbling his sweet 
 notes, as if he feared the night would be too short 
 to utter his love chant." 
 
 Hunger rouses the beast of prey to the chase, and 
 the sensation of thirst stimulates it to long journeys 
 in quest of water. It is an indefinite desire, and 
 independent of any deliberate object in resisting 
 danger, or procuring food, that excites the herbi- 
 vorous tribes to be gregarious, as it does the car- 
 nivorous, to avoid their fellows; and it is in the 
 same way, and not from the possession of definite 
 weapons, that the bull and ram are prompted to butt 
 with their horns, the horse to kick with its hoof, 
 tlye cat to seize and scratch with its claws, the dog 
 
152 THE NATURE OF INSTINCT. 
 
 to snap with its mouth, and the cock to strike with 
 its spurs. 
 
 The sensations dependent on the sexual secre- 
 tions are of vast importance in producing instinc- 
 tive acts, and from them result many of the pecu- 
 liarities observed in different species of the animal 
 kingdom. The degree of desire, indeed, which 
 prompts individuals in the defence of their young, ap- 
 pears to amount to enthusiasm. All enthusiastic acts- 
 it is well observed by Dr Pletcher, are instinctive, 
 and, therefore, in our own species, frequently such as 
 to surprise even the enthusiast himself, on again sub- 
 jecting himself to the sober dictates of reason and 
 volition. They arc like those of a person partially 
 imbecile or insane; and if a special providence some- 
 times seems to preside over the actions of an idiot 
 or a maniac, it is only because he is actuated un- 
 der circumstances of difficulty, by a power less fal- 
 lible both in its end, and the means employed to 
 attain that end, than reason and volition. It is 
 hence easy to understand how in the lower animals, 
 the blind impulse of instinct should often supersede 
 reason, and be competent to excite numerous 
 actions, corresponding to those which, in man, can 
 be excited only or chiefly by volition. Thus when 
 the latter would construct a fabric of any kind, he 
 proceeds upon a plan more or less deliberate, and 
 adopts means which are at first, in a greater or less 
 degree, inadequate to the end in view; and it is 
 only after efforts more or less frequently repeated, 
 . — and that not by himself alone, but by liis fellows 
 
THE NATURE OF INSTINCT- 153 
 
 for many succeeding ages, — that he attains any 
 thing Hke perfection in his manufacture. But the 
 snail in constructing its shell, the spider its web, or 
 the silk-worm its cocoon, the bee in building its 
 comb, the bird its nest, or the beaver its hut, with- 
 out any deliberation, adopts at once the most ef- 
 fectual means of attaining a certain end ; and the 
 resulting fabric is as perfect the first time it is at- 
 tempted, as it can ever by any possibility become. 
 These are the criteria of instinctive, as distinguished 
 from rational actions ; and the more nearly man, 
 in attaining perfection in his works, approaches to 
 these conditions, — in other words, the more he is 
 actuated in their production by instinct, — the great- 
 er is his genius ; the more by reason and volition, 
 the greater is his talent. And upon this principle 
 is explained why a man of genius is generally a 
 bad dissembler, and a man of talent a good one ; 
 in the former, the instinctive impulses preponde- 
 rating, in the latter the rational ; — no one can be a 
 hypocrite in whom the feelings preponderate over 
 the judgment. It is most erroneous to imagine that 
 we detract from the proper rank of the lower ani- 
 mals by representing them thus, with respect to 
 -many of their actions, as a kind of automaton ; 
 since we are, in fact, raising them to that of artists, 
 acting under an impulse which man conceives it 
 glorious to obey. It is this consciousness of a 
 power superior to any over which we have control, 
 which has led poets in all ages to invoke Apollo and 
 the Muses to inspire their verse, — in other words, to 
 
 or THE \ 
 
 UNIVERSITY I 
 
 Ca. . 
 
 OF y 
 
154 THE NATURE OF INSTINCT. 
 
 call upon passion or instinct to supersede reason ; and 
 tliat some sucli instinctive power at once absorbed 
 the mind, and actuated the mighty hand of a Mi- 
 chael Angelo and a liaphael, and excited, notonh' 
 the conceptions, but the merely physical movements, 
 destined to develop works on which ages were to 
 ponder with admiration and delight, is unquestion- 
 able. It is said of Paesiello, that, in his fits of 
 composition, he used to bury himself under the 
 bed-clothes, trying to banish from his memory all 
 the rules and precepts of his art, and giving vent 
 to his feelings in the exclamation, " Holy Mother, 
 grant me the grace to make me forget that I am a 
 musician." It is true that the instinct thus running 
 riot over the reason, is, in man, very liable to become 
 morbid, and even to terminate in confirmed idiot- 
 ism or insanity ; and numerous melancholy instan- 
 ces of partial or total imbecility or madness, as a 
 concomitant of the " fine phrensy" of poesy, might 
 be adduced from among the poets of every age : 
 
 " Great wits to madoess sure are near allied, 
 And thin partitions do their bounds divide." 
 
 It is this constant subserviency of many of the ac- 
 tions of a great genius, and of a fatuous or furious 
 person, to the same blind impulse, which produces 
 that close alliance of the sublime and the ridicu- 
 lous, the lofty and bombastic, — as well in works, as 
 in thoughts and words, — which has furnished in 
 every age, so fertile a theme of animadversion. Both 
 equally recede from the reasonable ; and the only 
 
THE NATURE OF INSTINCT. 155 
 
 xlifterence between them appears to consist in this, 
 that, while the former so far carries with it the 
 mind of the judge as to warp his judgment, by in- 
 spiring him with some degree of that enthusiasm in 
 which the conception originated, the latter fails in 
 this object, and, by leaving him in full possession of 
 his reason, stands exposed at once in all its native 
 deformity. An unhappy point in the most majestic 
 statue or picture, like an ill-timed word in the most 
 elevated sentence, frequently has the effect of sud- 
 denly aw^akening us from a day-dream of admira- 
 tion ;* and what we were perhaps about to pro- 
 nounce a model of the grand, becomes at once a 
 beacon of the ludicrous : the insignia of royalty dif- 
 fer only in the spirit in which we contemplate them 
 from the tinsel of punchinello. {Jt is a similar mor- 
 bid preponderance of instinct over reason which 
 leads man into every description of intemperance ; 
 although this results much more frequently from 
 the reason being too weak, as in the case of ordi- 
 nary debauchees, than from the instinct being too 
 strong, as in that of men of genius, who are un- 
 happily so often characterized by this infirmity ; as il- 
 
 * The spinous processes of the vertebrae of serpents are so 
 constructed, that the motions of their spinal column are not 
 only, or chiefly, lateral, but in a great measure upwards and 
 downwards also. Some painters and statuaries, however, ap- 
 pear to have overdone this matter, and to have represented flex- 
 ures in the bodies of serpents where no countenance can be 
 given to them by anatomy. There are limits, in this respect, 
 beyond which we cannot allow even the sublime hand of. th& 
 sculptor of the Laocoon to pass without reproach^. 
 
156 THE NATURE OP INSTINCT. 
 
 histrative of this, it is sufficient to mention Rochester, 
 Parnell, Otway, Sheffield, Savage, Churchill, Prior, 
 and Burns. Nevertheless, let those, as remarked 
 by Dr Currie in his life of the last, who are with- 
 out follies, cast the first stone at their infirmities, 
 and thank their God that they are not, like the poor 
 children of genius, frail in health, feeble in resolu- 
 tion, in small matters improvident, and unfortunate 
 in most things. 
 
 But, inquires Dr Fletcher, to whom we are in- 
 debted for the above illustrations, if instinct, thus 
 opposed to reason, sometimes betrays man into er- 
 rors, is reason, when opposed to instinct, quite ex- 
 empt from a similar imputation? Whence have 
 originated all the absurd attempts, made by repu- 
 ted philosophers, from the earliest periods, to coun- 
 teract the natural tendencies, as well of brutes as 
 of man, and to make them what nature never de- 
 signed that they should be ? What was it that has 
 led some of them to forbid us to sit near the fire 
 when we are t,old, lest peradventure we should dry 
 up our radical moisture ; or to court the refreshing 
 gales of heaven when we are in a fever, lest per- 
 chance we should interfere with the salutary fer- 
 mentation of our fluids ? What was it which has 
 prompted some to the idle attempt to make aqua- 
 tic animals terrestrial, and terrestrial aquatic ; to 
 render herbivorous creatures carnivorous, and car- 
 nivorous chewers of the cud ; or to turn quadru- 
 peds into bipeds, and bipeds into quadrupeds ? 
 Whence have arisen the injunctions, which we are 
 
THE NATURE OF INSTINCT. 157 
 
 condemned still sometimes to hear, not to eat when 
 we are hungry, nor to drink when we are thirsty, 
 and to feed exclusively on herbs and fruits, and 
 water from the spring,* or, at any rate, to be satis- 
 fied with the least possible quantity of the simplest 
 fare ? What formerly induced our boarding-school 
 mistresses to endeavour to improve the shape and 
 carriage of the poor things committed to their care, 
 by debarring them from all natural exercises ; and 
 what is now leading them, with almost equal absur- 
 dity, to attempt the same by all sorts of unnatural 
 gymnastics and calisthenics ? ,' There are few who 
 have not, at one time or other of their lives, tried 
 to supersede their instinctive and wholesome im- 
 pulses by some rational system of diet and regimen,/ 
 and there are few who have not found themselves the 
 worse for their pains ; and if man is more prone to de- 
 formity and disease than any other animal, he per- 
 haps owes a great part of the melancholy distinction 
 to so frequently allowing the artificial precepts of rea- 
 son to interfere with the natural dictates of instinct. 
 We may distort the propensities, as we may deform 
 the skull like the Charib, or the nose like the Afri- 
 can, or the foot like the Chinese ; but we cannot 
 improve them.f 
 
 * The principal patrons of this twaddle in modern timea to 
 
 say nothing of Pythagoras and the ancients — have been Gas- 
 sendi, Rousseau, Willis, Lamb, and Newton, the last of whom 
 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 ! 
 
 t Fletcher, Part ii. /3, pp. 19-20. 
 
158 THE NATURE OF INSTINCT. 
 
 But to return from tliis digressior|[, the sense of 
 an ungratitied want,; though less distinct in its cha- 
 racter than others we have mentioned, is not the 
 Jess the origin of many instinctive acts of whicli 
 we shall hereafter speak. 
 
 The sensations arising fi'om the consciousness of \ 
 the actions of the muscular frame become a new 
 source of activity; and it will be found to play an ,- 
 important part in the economy of instinctive acts. / 
 The pleasure which results from them, especially 
 in the young, appears to be one of the chief enjoy- 
 ments in the existence in animals. We see the 
 young steed bounding over field and meadow glory- 
 ing in the consciousness of his powers ; and the 
 delight which the lambs in spring display in the 
 exercise of their speed, is one of the most pleasing 
 contemplations in nature. It has drawn strains that 
 will never die from many a poetic mind. 
 
 / The last order of internal sensations on whicli in- 
 stimitive acts depend, are those of Emotion.., Of this 
 are all the forms of the expression of emotion or 
 passion in man and the higher animals, as seen in 
 the aspect of the countenance, and the attitudes of 
 the body. These, as connected with emotion or 
 passion, give one of the best illustrations of the 
 philosophy of all instinct ; for the muscles concern- 
 ed are all voluntary, yet here assume definite com- 
 binations of action wholly independent of the will ; 
 and in the human race, the acts of expression in 
 particular, are so numerous, that they must equal, 
 if they do not exceed, the various movements ne- 
 
THE NATURE OF INSTINCT. 159 
 
 cessary in other animals for the ends of their relative 
 existence. It is perhaps true, as Sir Charles Bell 
 remarks, that there is no expression in the face of 
 any animal lower in the scale than the quadruped ; 
 yet the same limitation is not to be extended to the 
 action of tlie eye, and the attitudes of the body, 
 which occur in correspondence with emotion in 
 birds and reptiles, as in mammals. The fire-like 
 flashing, the fascinating power of " the magic circle 
 of the eye," is no fable ; and as remarkable in some 
 reptiles as in man. The increased brilliancy in the 
 eye of the rattlesnake from desire, and in which 
 appears to consist its reputed fascinating power, is 
 well known, and seems to have suggested to Mil- 
 ton the idea of endowing the serpent in the Garden 
 of Eden with a similar property, — 
 
 '' its gentle, dumb expression turned at length 
 
 The eye of Eve :" 
 
 the erect bearing of the common cock after vic- 
 tory, and the perching aloft to crow over his van- 
 quished rival, and the dejected mien of the con- 
 quered ; the swagger of the turkey-cock, and the 
 amorous movements of the pigeon, are so many 
 muscular acts determined by sensations of emotion. 
 Again, the sudden inflation of the Diodons and Te- 
 tradons among fishes when irritated, so as to ren- 
 der all their spines erect ; and the violent instinc- 
 tive movements by v.hich many other species in- 
 flict, in the same mariner, severe wounds on their 
 aggressors ; and the pouching of the neck of the 
 cobra-da-capello, among reptiles, from agitation. 
 
160 THE NATURE OF INSTINCT. 
 
 are instances of tlie influence of passion on the 
 action of muscles generally voluntary. 
 
 The number of movements of this kind, how- 
 ever, in the inferior animals, falls very far short of 
 that whicli is observed in man. Thus in carni- 
 vorous animals, the expression most marked is 
 tliat of rage : — the glaring eye is fixed, the lips are 
 retracted, the canine teeth are exposed, and the 
 attitude of the body is such as collects the whole 
 energies of the muscular frame, and concentrates 
 them for attack. In graminivorous animals, as the 
 bull, the eye assumes a wild and fearful character, 
 the nostrils become dilated, the horns are directed 
 obliquely downwards, while the rest of the face, 
 especially the lips, remains calm and placid. In 
 the horse, the expression of the eye and nostril, 
 and the motions of the ears, mark the same state 
 of emotion. Rage and fear seem to be the chief 
 sources of expression and attitude in quadrupeds ; 
 but in man there is no emotion which is not attend- 
 ed by its corresponding indication on the muscles 
 of the face, so truly said to be the index of the 
 mind. In the expression of rage, the " human face 
 divine," combines, to a certain extent, the muscular 
 actions of both herbivorous and carnivorous ani- 
 mals ; the eye sparkles, the notrils are dilated, while 
 the canine teeth are in part exposed, to which is 
 added the knitting of the eyebrow, an act of which 
 other animals are incapable, and the cause of the 
 peculiarity of the expression of the emotions in the 
 human coimtenance. 
 
THE NATURE OF INSTINCT. l6l 
 
 In laughter, peculiar to man,* the outer-half of 
 the eyebrow is drawn down, the mouth is open, 
 the teeth appear, the angles of the mouth are drawn 
 backwards and upwards, the nostrils are dilated, 
 and the cheek raised. 
 
 In weeping the brow is drawn down, the cheek 
 raised, the nostril drawn up, and the mouth stretch- 
 ed laterally, the part of the eyelid next the nose is 
 elevated, while the corners of the mouth are de- 
 pressed.f 
 
 * Milton says that — 
 
 smiles tVoia reason flow, 
 
 To brutes denied. 
 
 The reverse, however, of the first part of the proposition holds 
 good ; the act is purely instinctive, and reason is not concern- 
 ed in its production. 
 
 t The only brutes said on good authority to weep from sor- 
 row, are some species of monkey, the seal, and the camel ; the 
 first species by Humboldt, the second by Steller, and the last 
 by Pallas ; the dog, however, should certainly be added to the 
 list. The alleged " big, round tears,'' of the deer, the hare, 
 and other animal? when hotly pursued, are in fact only seba- 
 ceous matter, which, under these circumstances, flows in profu- 
 sion from a collection of follicles in the hollow of the cheek ; 
 and the far-famed '' crocodile's tears," although bona fide tears, 
 do not flow from affliction. But if crying is not confined to 
 man, he is perhaps exclusively '• a laughing animal," as he has 
 been sometimes defined, no brute apparently being capable of 
 that sense of the ridiculous, arising from incongruous associa- 
 tions in which laughter orginates. The laughing of the hyaena, 
 it needs hardly be observed, furnishes no exception to the re- 
 mark. 
 
 And if man stands almost alone in his susceptibility of a flow 
 of tears from affliction, and of laughter from mirth, it is, per- 
 L 
 
162 THE NATURE OF INSTINCT. 
 
 In joy the eyebrow is raised moderately without 
 angularity, the forehead is smooth, the eyeball 
 lively and sparkling, the nostril slightly dilated, 
 and the lips smiling. In all the exhilarating emo- 
 tions, the eyebrow, the eyelids, the nostrils, and the 
 angles of the mouth are raised ; while in all depress- 
 ing passions the reverse is the case. In discontent 
 the brow is wrinkled, the nose peculiarly arched, 
 and the corners'of the mouth drawn down to a great 
 extent. But for descriptions of other kinds of ex- 
 pression, we must refer to the authors who have 
 written on the subject, particularly to Sir Charles 
 Bell's Anatomy of Expression, to whom we are in- 
 debted for much information on the subject.^ That 
 such combinations of muscular contraction are of 
 the same nature as instinctive acts cannot be rea- 
 sonably doubted ; they are independent of the will, 
 and although they do not display themselves in an 
 equally marked manner in every individual, yet the 
 muscles concerned, and the mode, if not the de- 
 gree, of their action, is one and the same in all 
 mankincj) It has been questioned, however, if these 
 are properly ranked with sensation ; and what can 
 be said on that point chiefly is, that this has been 
 a common plan of arrangement among physiolo- 
 gists, and even allowing it to be no more than a 
 convenient mode of classification, we shall not be 
 
 haps, not because there is no tendency in other mammals to the 
 same actions from the same primary stimuli, but because they 
 are in general incapable of the peculiar emotions in which these 
 primary stimuli consist — Fletcher, Part II. /3. 
 
THE NATURE OF INSTINCT. 163 
 
 precluded from insisting on the proposition that the 
 sources of instinctive acts are reduced to two4— cer- 
 tain states of sensation and certain forms of emo- 
 tion/ Nor should it be required of us to shew any 
 further connection between what is here assigned 
 as the cause and the effect in question. It is 
 enough if there be an uniform observation of a sen- 
 sation or emotion as the antecedent of every in- 
 stinctive act, to entitle the one or the other to the 
 name of cause. It is possible that some interme- 
 diate step between the two acts may hereafter be 
 discovered ; but in the mean time, as was before 
 observed, we must be content to view the connection 
 between them as simply established by the Almighty 
 wUl. 
 
 It would be improper to leave this part of our 
 subject, and proceed to the consideration of instinc- 
 tive acts of a more permanent kind, without allud- 
 ing, as illustrative of them, to the effects of emotion 
 on other parts of the body than the muscular. We 
 shall confine ourselves, however, and that briefly, 
 to the functions of secretion and absorption. 
 
 These are remarkably affected by emotion. In 
 intense grief and in fear, the secretions, at least 
 some of them, are altogether stopped ; the tears do 
 not flow, and the saliva is suppressed ; the ab- 
 sence of the latter, causing the cleaving of the 
 tongue to the roof of the mouth — the vox hceret 
 
 faucihus — the passio hysterica of poor Lear has 
 
 been turned to account in the detection of a thief 
 in an establishment of servants, by the dryness of 
 
H54 THE NATURE OF INSTINCT. 
 
 the rice \vhich lie, in common with the rest, had 
 been compelled to hold in liis moutli, while each was 
 taxed with the theft. From grief, in a few hours 
 the hair lias become perfectly blanched ; and the 
 same emotion in a canary-bird, from the loss of its 
 mate, has been known to cause a change in the co- 
 lour of its feathers. We have a case in our recol- 
 lection where, from intense and sudden grief in a 
 woman who was nursing, the milk entirely, and in 
 a very short time, left her breasts. From bad news 
 the breath will become instantly fetid; and not 
 only is the halitus from the lungs vitiated, but the 
 secretions also, which are at the same time increas- 
 ed in quantityc From bashfulness, the sebacious dis- 
 charge from the surface assumes so unpleasant an 
 odour, that the poor sufferer is often unjustly accused 
 of uncleanliness ; and all persons must be aware how 
 suddenly, from dismay, the whole body is bathed in 
 sweat. The phrase " green-eyed monster," is cor- 
 rectly applied ; jealousy, as Horace says, making 
 the liver swell with bile and causing jaundice. 
 By fear the alvine secretions are changed in quan- 
 tity, consistence, and odour, as every boy who has 
 been threatened with a caning, will well remember ; 
 and when cholera raged ^^mong us, this had no little 
 influence in the spreading and propagation of the 
 epidemic ; fear soon brought on a bowel complaint ; 
 a predisposition to the disease was thus establish- 
 ed, which soon followed to claim its unhappy victim. 
 In joy the tears often flow ; while, as we before 
 remarked, in intense grief they are suppressed, and 
 
THE NATURE OF INSTINCT. 165 
 
 when they do flow it is a proof of moderated sor- 
 row ; tears do not bring relief, as is commonly sup- 
 posed, but they indicate that it has been brought. 
 In hilarity and in despair fat is abundantly secreted ; 
 and hence " despair and grow fat " would be as 
 true a saying as " laugh and grow fat." Persons 
 left long to pine in condemned cells, without a sha- 
 dow of hope, become frequently, in spite of their 
 slender fare, remarkably stout. Absolute despair, 
 as Dr Fletcher justly remarks, is as incompatible 
 with solicitude, as total thoughtlessness ; and it is 
 solicitude which emaciates. Cassius was " lean," 
 because he was anxious to redress his country's 
 wrongs ; had he either been indirferent, or despair- 
 ed of redressing them, he would probably have been 
 as " fat and sleek-headed," as any of those whom 
 Caesar wished to have about him. 
 
 Nature has rendered the increase and vitiation 
 of certain excretions, under emotion, a means 
 of defence and security to many animals. The 
 cuttle-fish, among avertebrated animals, conceals 
 itself, when in danger, by colouring the water 
 black with the matter discharged from its ink- 
 bag. Among reptiles, the increase and vitiation 
 of the cutaneous exhalation of the alliaceous and 
 mephitic toad, when irritated; and the bath of 
 sweat which, under similar circumstances, enve- 
 lopes the salamander, and that to such an extent, 
 that it has been known, not indeed to extinguish, 
 but to escape from, a fire into which it was thrown, 
 ^re likewise instinctive acts, and the effects of 
 
106 THE NATURE OF INSTINCT. 
 
 emotion. The diodons and tetrodons, among fishes, 
 inflate themselves, under the same circumstances, 
 by the compound consequence of the effects of 
 emotion upon their muscles, to which we have allu- 
 ded, and the sudden secretion of air. The vulture 
 uses the contents of its stomach as a great means 
 of defence ; from fear, the odour of this becomes 
 highly vitiated, and when pursued, the bird voids 
 in the face of its pursuers a mass so intolerably 
 fetid, that they are compelled to desist from the 
 pursuit. The American skunk uses its intestinal 
 secretions in the same way. Many animals, again, 
 change colour from emotion, — analogous, perhaps, 
 to blushing in man ; of these we may mention, 
 among reptiles, the chameleon ; among fishes, the 
 perch and stickleback ; and among birds, the tur- 
 key-cock, as is seen in his wattles. 
 
 We might greatly add to this catalogue, but re- 
 frain from doing so ; simply observing, that all the 
 acts we have mentioned are of the same nature as 
 instinct, and to be referred to emotion. 
 
 The foregoing slight sketch of some of the 
 sources of those instinctive acts which are of a less 
 continued kind, is a step towards connecting those 
 of a more prolonged character with the same prin- 
 ciple. 
 
 » It was before remarked, that every muscular act 
 oVa relative kind is the source of a new sensation; 
 that is, an animal is conscious of the contraction of 
 the muscles concerned in such acts; and hence 
 a single muscular act originating in a sensation, 
 
THE NATURE OF INSTINCT. l67 
 
 as it gives rise to a new sensation, may become 
 the source of other muscular acts, which, being 
 in turn the source of sensations, produce in suc- 
 cession other acts, so that a continued and con- 
 nected train of instinctive acts may thus proceed 
 in a manner wholly analogous to that in which a 
 «ingle momentary act arises.* The limit to the con- 
 tinuance of such a train of 'acts, is the fatigue or 
 exhaustion, alike, perhaps, of the nervous power 
 and the muscular force ; which, being renewed and 
 refreshed by rest, the same stimulus, whatever it 
 may be, will be capable of setting again in motion 
 the former succession of acts, (f Again, the sensa- 
 tion accompanying an ungratified want, as it may 
 continue a long time, seems capable of giving rise 
 to prolonged acts,} just as momentary sensations 
 produce temporary acts. : Another source of conti- 
 nued action may be conceived, without any viola- 
 tion of the same principles, in the new impressions 
 made on the senses, as of sight or touch, by the 
 effects of the first acts on surrounding nature ; for 
 example, in constructing a nest, or a habitation of 
 any sort, the sight of the first steps in the work 
 may be regarded as so many sensations on which 
 the continuance of the necessary acts depends. The 
 application, then, of these propositions, seems to 
 bring continued acts of instinct under the same 
 general law as those above noticed ; while, at the 
 same time it must be admitted, that our assent to 
 the explanation in the case of these is less rea- 
 dily afforded. 
 
IG8 THE NATURE OF INSTINCT. 
 
 The most remarkable instances of continued acts 
 of an instinctive kind are found in the constructioi> 
 of habitations by the beaver, the nests of birds, the 
 comb of bees, the cocoons of silk-worms, and the 
 webs of spiders ; also in the migrations of birds, 
 land-crabs. Sec. These, however, we shall not en- 
 ter more fully upon, further than to remark, that 
 tlie first of these animals, which, in its native haunts, 
 seems to exhibit the most remarkable effects both 
 of reason and instinct, belongs to an order of mam- 
 mals by no means distinguished for the general 
 development of their brain, or of those parts in it 
 which are most perfect in man, the quadrumana, 
 and carnivora. Like the other rodentia, the beaver 
 is destitute of the convolutions on the surface of 
 the brain, so distinguishing a characteristic of man 
 and the higher animals. This might lead us to 
 the proposition that instinctive powers are more 
 produced when the organ on which reason depends 
 is less developed. 
 
 It may be added, as illustrative of the connexion 
 between instinct and certain definite sensations, 
 that the beaver, when removed from its native wilds, 
 becomes an extremely stupid animal. 
 
 In what has been called the accommodating 
 power of instinct, some evidence is obtained of the 
 necessity of definite sensation to call forth its phe- 
 nomena ; although, in some instances of this kind, 
 a degree of reason must be supposed to bring about 
 the change on the habits of the animal. Thus, in 
 Senegal, the rabbits, as Adanson relates, do not 
 
THE NATURE QF INSTINCT. l69 
 
 burrow, that is to say, that the sensation of cold» 
 which must be presumed to be the cause that de- 
 termines them to that act elsewhere, is not there 
 appHed. In the same country the ostrich sits upon 
 her eggs only by night, while at the Cape of Good 
 Hope she incubates both by night and day. This> 
 like every other bird, occasionally leaves her eggs; 
 and the sensation imparted from their coldness on 
 her return, must be the cause by which her sitting 
 is kept up. If, then, no such cooling takes place 
 during her absence by day in the warm climate of 
 Senegal as at the Cape, the condition on which her 
 assiduity depends does not take place. Many birds, 
 again, build their nests differently in different places, 
 — the difference being evidently connected with a 
 difference in the climate, and other circumstances 
 of the situation. Many of these differences may 
 be traced to differences in the sensations produced 
 by variety of climate and circumstances ; but some 
 of them must be referred to reason in the first in- 
 stance, — in the progeny, perhaps, to the transmis- 
 sion of acquired qualities. Thus it is said, that, in 
 countries infested with monkies, birds which in 
 other places build in bushes and clefts of trees, 
 suspend their nests on slender twigs, so as to avoid 
 the attacks of their predacious enemies. It does 
 not clearly appear how such changes in the habits 
 of these birds can be referred to instinct, — unless 
 we say that new sensations beget new instincts. 
 That such is the case is undeniable, yet, in the pre- 
 sent state of our knowledge, it is perhaps more ju- 
 
ltd THE NATURE OF INSTINCT. 
 
 dicioiis to refer such clianges to experience, thus 
 admitting a reasoning principle. But suppose it be 
 found that every new brood proceeds in the same 
 manner as the parent birds, without any apparent 
 source or time of instruction ; then we must refer 
 it to the transmission of quaUties acquired by the 
 parents to their offspring, — that is, what was ac- 
 quired by the parent birds at some previous time by 
 reason becomes transmittable to their progeny as an 
 instinct. It is certain that acquired quahties, how- 
 ever httle it may be the case among men, are trans- 
 ferred to the offspring among the inferior animals, 
 and that in no slight or unequivocal degree. Every 
 one has seen, or at least has heard of, the tailless 
 cats of the Isle of Man, and of the dock-tailed dogs 
 of the southern counties of England ; and it can- 
 not be doubted but that these two breeds arose 
 from the mere cutting off of the tails of certain pa- 
 rent cats and dogs, while the breed was confined 
 from admixture wnth those who enjoyed the full 
 plenitude of their caudal appendages. A cat of 
 this variety breeding with a common cat, produces 
 a litter of kittens with very short tails; and the 
 peculiarity will, by a repetition of the experiment, 
 soon disappear. That the peculiarity is originally 
 induced by the simple mutilation of the tails of the 
 parent animals, is proved by an experiment referred 
 to by Haller, in which a common cat, from which 
 the tail had been purposely removed, brought forth 
 a litter, some with tails and others without. A 
 fact is recorded in some books of natural history, 
 
THE NATURE OF INSTINCT. 171 
 
 which bears more closely on the present argument. 
 In some parts of America, it is the practice to hunt 
 herds of a species of deer with trained packs of 
 dogs ; the dogs are taught to attack the herd in 
 line, and by this method never fail to be success- 
 ful ; but if any of the dogs be led by excessive ar- 
 dour to break into the herd singly, they are sure 
 to be completely destroyed. This uniformly hap- 
 pens to untrained dogs, whatever be their strength 
 and courage. But the offspring of dogs which 
 have been fully trained to this kind of warfare, re- 
 quire no education, but at once fall into the only 
 kind of attack which can be attended not only with 
 success, but their own personal safety. 
 
 A more minute acquaintance with the animal 
 kingdom will doubtless enable us to point out many 
 sensations governing the instincts of animals, at 
 present unknown to us ; for every day's experience 
 adds something to our knowledge on this head, 
 even although the subject has seldom been investi- 
 gated on a proper plan. The migrations of birds, 
 in particular, offer a wide field for the illustration 
 of this subject, as connected with the changes of 
 temperature, and other qualities of the atmosphere, 
 the failure of food, and the like. One curious fact 
 which we may mention, as recorded some years ago, 
 offers a kind of key to such inquiries. In the neigh- 
 bourhood of the Carron iron-works, where the tem- 
 perature of the air, to a considerable extent around, 
 must be very much above that natural to the cli- 
 mate, swallows are said to remain the whole winter. 
 
172 THE NATURE OF INSTINCT. 
 
 Indeed tlie experiments of Mr Pearson, as detailed 
 by Bewick, puts tlie question beyond a doubt. Ha- 
 ving (obtained some swallows, he placed them sepa- 
 rately in cages in a warm room, feeding them with 
 nightingales' food, and guarding their feet from the 
 effects of damp and cold, by covering their perches 
 M^ith flannel. This precaution was adopted because, 
 in a former unsuccessful experiment, the birds' feet 
 had swollen and inflamed, as was supposed, from 
 this cause. " He had the pleasure to observe that 
 the birds throve extremely well ; they sung their 
 song throughout the winter, and soon after Christ- 
 mas began to moult, which they got through with- 
 out any difficulty, and lived three or four years, re- 
 gularly moulting every year at the usual time. On 
 the renewal of their feathers, it appeared that their 
 tails were forked exactly the same as in those birds 
 which return hither in the spring, and in every re- 
 spect their appearance was the same." The pro- 
 pensity to migration, then, does not arise in these 
 cases, because, so long as the birds are confined within 
 a certain boundary, the sensation arising from a de- 
 clining temperature does not affect them. And fur- 
 ther, it is probable that the same elevated tempera- 
 ture prc^vents, in their wild state, any deficiency of 
 their usual insect-food throughout the winter. 
 
 The instinctive actions of animals, then, it can 
 hardly be questioned by any who reflect upon the 
 subject, are referable to some uneasy sensations, in 
 like manner modifications of touch or tact, pro- 
 ceeding from certain irritations of particular organs. 
 
THE NATURE OF INSTINCT. 173 
 
 Thus, — to begin with some of those which the in- 
 ferior tribes of animals have in common with man, 
 — can it be doubted that the instinctive actions of 
 keeping themselves warm, and of taking food and 
 drink, spring from uneasy sensations, originating 
 in certain uTitations respectively of the skin and 
 the stomach, and prompting us to use the proper 
 means of removing them ? " The perception of 
 these irritations," it has been well remarked, " is 
 the monitor by which we are warned of the neces- 
 sity of effecting some change in the system ; and 
 it is a monitor, the voice of which it is not possible 
 either to disregard or misunderstand, since its im- 
 portunity iiicicases in proportion to the increased 
 demand for such a change, and its injunctions are 
 enforced by laws far less fallible than those of rea- 
 son." And if it be conceded that the instinctive 
 actions just mentioned originate, not in thought, 
 but in sensation, how can it be reasonably ques- 
 tioned that others, in every respect so nearly allied 
 to them, have likewise their source each in some 
 uneasy sensation, arising from a specific irritation, 
 and urging animals to adopt the only proper means 
 of getting rid of it, in the same way as coldness of 
 the surface prompts us to huddle the limbs toge- 
 ther, and to seek the other sources of heat, and 
 hunger and thirst to take food or drink, and to do 
 nothing else ? Instinct in general is, accordingly, 
 well described by Broussais as arising always from 
 " sensations which solicit a hving being to execute 
 involuntarily, and often unconsciously, certain acts 
 
174 THE NATURE OF INSTINCT. 
 
 necessary'for its welfare." Thus, not only the taking 
 of food wlien hungry, but the selection by every 
 kind of animal of its own proper aliment, the hoard- 
 ing up by some tribes of a store, in apparent anti- 
 cipation of a time of need, the depositing of their 
 eggs in appropriate places, the choosing by each of 
 its proper habitat, and the construction by many 
 of fit places of abode, all appear to indicate nothing 
 more than blind impulses arising from sensations, 
 themselves the result of specific irritations in cer- 
 tain parts of the body. The experiment of Galen 
 with the young kid, which selected milk, seen for 
 the first time, from numerous other kinds of ali- 
 ment placed before it, is well known ; and that in 
 all such cases, the selection is determined by an 
 uneasy sensation, which one particular aliment is 
 best calculated to remove, and which is different 
 in every animal, according to its particular organi- 
 zation, is as unquestionable as that, in certain states 
 of the human stomach, an appetite for acid, and in 
 others for alkaline substances, is experienced, with- 
 out, however, any thing like a reasonable convic- 
 tion of their efficacy. In like manner, the ant 
 hoards up its grain, and the bee its honey, not from 
 any reasonable persuasion that they shall in future 
 stand in need of such supplies, but because their 
 organization is such, that omitting to do so would 
 be felt by them as a natural appetite ungratified. 
 It is as actuated by the same impulse, that moths 
 and butterflies lay their eggs always in situations 
 where the young caterpillar, on being hatched, can 
 
THE NATURE OF INSTINCT. 175 
 
 at once procure substances adapted for its nourish- 
 ment. They think nothing of this ; but they lay 
 their eggs in such situations, because they are 
 prompted to do so by an uneasy sensation, excited 
 probably by certain odours, as dogs and other ani- 
 mals are stimulated to certain excretions under 
 similar circumstances. The instance, also, most 
 commonly brought forward of instinctive action, — 
 that of a young duckling, even though hatched and 
 reared by a hen, running into the water the first 
 time it comes near it, seems to be explicable on 
 precisely the same principle as the others.* It evi- 
 dently does so, as a means of obviating the uneasy 
 sensation arising from the want of gratification of 
 one of its natural appetites, which could not be in- 
 dulged while on dry land ; and it is from a similar 
 cause that every animal at once betakes itself to 
 that element, and that situation, to which its orga- 
 nization is adapted, and an exclusion from which is 
 — like confinement and restraint of every kind — 
 felt to be a positive evil. Thus the eagle inhabits 
 the rocks, the heron the shores, the partridge the 
 plains, and the ptarmigan the loftiest peak of the 
 mountains ; the snipe wades in the marshes, the 
 
 * " Take," says Galen, "three eggs, one of an eagle, an- 
 other of a goose, and a third of a viper, and place them favour- 
 ably for hatching. When the shells are broken, the eagle and 
 gosling will attempt to fly, while the young of the viper will 
 coil and twist along the ground. If the experiment be pro- 
 tracted to a later period, the eagle will soar to the highest re- 
 gions of the air, the goose will betake itself to the marshy pool, 
 and the viper will bury itself in the ground." 
 
17G THE NATDUE OF INSTINCT. 
 
 lark frequents the furrows, tlie woodpecker creeps 
 around the trees, and tlie slirill cry of the landrail 
 issues from among the long grass of the dank mea- 
 dows ; the martin, too, builds in our windows, and 
 the sparrow in our roofs, not because they have any 
 precise object in so doing, — however important 
 might be the object of the great Creator in dispo- 
 sing them to do so, — ^but because their organiza- 
 tion is such, that any other situation would be to 
 them " weary, stale, flat and unprofitable." Among 
 other instances of instinctive actions commonly 
 brought forward, are those from which result the 
 beautiful fabrics so frequently constructed by some 
 of the lower animals, and so admirably adapted each 
 to the end whicli it appears to have been intended 
 to serve. Of this nature are the shell of the snail, 
 the w eb of the spider, the cocoon of the silk-w^orm, 
 the comb of the bee, the nests of birds, the huts of 
 beavers, and innumerable others, which display at 
 once the most delicate mechanism, and apparently 
 the most admirable foresight. Concerning the fore- 
 sight, however, we Lave already said enough, in 
 speaking of the hoarding up of grain by the ant, 
 and of honey by the bee ; and concerning the me- 
 chanism, we shall find little grounds, on this score, 
 for attributing to the agent in question any thing 
 more than the blind impulse above alluded to, when 
 we remember that fabrics infinitely more subtle, 
 and furnishing infinitely better illustrations of the 
 adaptation of means to an end, are frequently the 
 
THE NATURE OF INSTINCT. 177 
 
 work of agents to which we concede neither thought 
 nor sensation, but only irritation.'* 
 
 * Among the most singular of these, is that faculty possessed 
 by animals by which not only the particles of each individual 
 tissue and organ of which their bodies are composed are con- 
 tinually undergoing a change, by the processes of absorption 
 and deposition, and the whole body in this manner kept, as it 
 were, in a state of freshness ; but whole tissues and organs^ 
 if accidentally removed, frequently entirely regenerated. This 
 occurrence, however, is much less frequent in man, and the 
 more perfect animals, than in the less advanced forms of or- 
 ganized beings. In plants the power of reproducing parts which 
 have been removed is almost unlimited, and in many of the 
 avertebrate animals it is very remarkable. Thus, the star-fish 
 (Asierias), the sea-anemone (^Actinia), and the cuttle (Sepia), 
 are capable of reproducing their rays and tentacula ;* and crabs, 
 lobsters, and cray-fish( Cancer), have the same power withrespect 
 to their claws ;t the snail (^Limax) can even reproduce its head 
 with all its natural appendages jlj: the earth-worm (Lumbricus 
 terrestris).) and the water-worm (i. variegatus), can regene- 
 rate either extremity of the body ; § and the fresh-water poly- 
 pus (^Hydra viridis), if cut into numerous pieces, is capable of 
 becoming, by the renewal in each piece of all deficient parts, 
 as many perfect animals. |j Nor is this faculty confined to the 
 avertebrate tribes, since many vertebrate animals also, and in 
 particular the reptiles, possess it to a very considerable degree, 
 numerous experiments having abundantly proved that the frog, 
 
 * A Trerabley, Memoires pour servir a I'histoire d'un genre de Polypes 
 d'eau douce. C. Bonnet, Considerations sur les Corps Organises, Reau- 
 jTiur, Memoires pour servir a I'histoire des Insects, &c. 
 
 t Reaumur sur les diverses reproductions qui se font dans les ecrevises, 
 les omards, &c. Mem. de I'Acad. Roy. des Sciences. 
 
 X Spallanzani, Precis d'un ouvrage sur les reproductions Animales. 
 Bonnet's Experiments in Spallanzani's Tracts, &c 
 
 § Reaumur. Bonnet. Spallanzani. J. G. Dalzell. Observations o* 
 the Planariae, &c. 
 
 H Trembley, ut supi-o. 
 
 M 
 
178 THE NATURE OF INSTINCT. 
 
 Instinctive actions, then, appear to be directly 
 connected with sensation, in tlie same way as cer- 
 tain organic actions are with irritability, and ra- 
 tional actions with thought. They seem to stand, 
 as it were, midway between the two latter, with one 
 or the other of which it is remarkable that they have 
 been almost constantly confounded. We have al- 
 ready had occasion to remark, that, by some philo- 
 sophers, all instinctive action has been attributed 
 to merely an exquisite kind of mechanism, such as 
 may perhaps be brought to explain the actions re- 
 sulting from mere irritation, but is quite inappli- 
 cable to such as are instinctive ; while, on the other 
 hand, they have been, by many others, referred not 
 only to thought, but to the most sublime degree of 
 
 the water newt,* and the lizard,t for example, are capable of 
 reproducing their eyes, lower jaw, tail, and extremities. In 
 the hot-blooded animals this faculty of reproduction is consider- 
 ably less striking, and the instances of renewal of removed or- 
 gans in birds and mammals are comparatively few and unimpor- 
 tant. Such, however, have occasionally occurred, and even in 
 man examples of the reproduction of whole organs are not want- 
 ing, as in the case of the nailst and other parts ;§ after the 
 removal of the cervix uteri also, a new os tincse, more or less 
 perfectly formed, is frequently met with, and the records of 
 surgery show that after the excision of a joint, a new joint, more 
 or less perfect, has been observed. 
 
 * Spallanzani's Experiments on the Tail of the Tadpole. Precis, &c. 
 Experiments on the reproduction of the extremities of the frog and toad, 
 in Troja de Ossium Regeneratione. 
 
 Bonnet and Blumenbach. Experiments on the eyes of lizards. Ru- 
 dolph! on the tail of the lizard, &c 
 
 \. i^ondon Med. and Phys. Journ. 181?. 
 
 § Edinb. Med. and Phys. Essays. 
 
THE NATURE OF INSTINCT. 179 
 
 intelligence of which we can form any conception. 
 I'Tnstinctive motions are prompted by a monitor, the 
 ^ voice of which is infallible, and they tend, with ab- 
 solute certainty, to the attainment of their object yj} 
 and it is on this account that they are not suscep- 
 tible of any ulterior improvement.* Hence has 
 arisen the notion that they spring from a kind of 
 inspiration — from the still small voice of the Al- 
 mighty, which at once excites and directs them ; 
 and hence, upon the presumption that instinct was 
 the impelling principle of brutes, and reason was of 
 man, and from a comparison of the deceitfulness of 
 the latter, with the total exemption from error of 
 the former, arose the maxim so common with many 
 writers, that Deus est anima brutorum. 
 
 " Animals in their generation," says Addison, 
 " are wiser than the sons of Men, but their wisdom 
 is confined to a few particulars, and lies in a very 
 narrow compass ;" and Cuvier has lately described 
 instinct as identical with innate ideas, which we 
 shall presently see have been identified with God 
 
 * We have sometimes heard it objected, that instinct cannot 
 be perfect and undeviating, because some insects are said to mis- 
 take certain stinking plants for putrescent substances, and depo- 
 sit their eggs upon them. But it is not less likely that insects, 
 prompted by instinct, should deposit their eggs in substances 
 susceptible of so rapid a decomposition as may afford a congenial 
 nidus to the young animal, than that they should do so on sub- 
 stances already undergoing such decomposition. Both the Phal- 
 lus and Agaricus, the plants alluded to, possess not only a putres- 
 cent odour, but are very rapidly reduced to that state. 
 
180 THE NATURE OF INSTINCT. 
 
 himself.* But, as the notion of animals being mere 
 machines, in as far as their instinctive operations 
 are concerned — however true it may be with re- 
 spect to such of their motions as depend on irrita- 
 tion — tends to degrade instinct below its proper 
 rank, so the presumption, that " 'tis the Divinity 
 which stirs within them," and directly actuates these 
 operations which are thus represented as springing, 
 not only from mind, but from the most sublime 
 mode of this faculty, tends equally to elevate it 
 above its proper place. The very fact of the in- 
 stinctive impulse being more unerring, and instinc- 
 tive operations more precise, and more exquisite in 
 their results than those of human reason, seems ini- 
 mical to the conclusion, that they are the effects of 
 the immediate influence of an intelligence superior 
 to this ; since, while they excel those of human 
 reason, they still fall short of those of mere irrita- 
 tion, as these again often do of those of mere che- 
 mical or mechanical attraction and repulsion. The 
 fact appears to be, that the greater number of the 
 movements of matter have in reality nothing to do 
 with mind as directly concerned in producing them. 
 " They are," as remarked by Sir Charles Bell, " the 
 mere consequences of events immediately anteced- 
 
 • The instinct of animals has been called by Sir Isaac New- 
 ton, " the wisdom and skill of a powerful ever-living Agent;" 
 by Addison, " an immediate impression from the First Mover ;" 
 by Hartley, " a kind of inspiration;" by Hancock, " the Di- 
 vine energy ;'' by Mason Good, " the Divinity that stirs with- 
 in them;" and by Kirby, " the interagent of the Deity." 
 
THE NATURE OF INSTINCT. 181 
 
 ing, and have not the least connection with a pre- 
 vious purpose or mental judgments in the beings or 
 things in which they are displayed." They appear 
 to be, indeed, as we have just implied, frequently 
 the more perfect the lower is the rank of the agent 
 whence they immediately spring, those resulting 
 from merely chemical and mechanical attraction 
 and repulsion being the most so, next those of irri- 
 tation, afterwards those from sensation, and, lastly, 
 those from thought ; and why any new Deus infa- 
 bula should be put in requisition to account for the 
 proper instinctive motions, when we require no 
 such agent in accounting for any of the rest, is al- 
 together inexplicable. Far be it from us to appear 
 to question for a moment that the Deity presides 
 over all the movements of all forms of matter, in- 
 animate and animate ; but he does so, not directly, 
 but through the medium of certain definite laws, 
 imposed by himself, and with the uniform opera- 
 tions of which we have no reason to believe he even 
 interferes. The motions which determine the for- 
 mation of a crystal, the development of a flower, 
 the construction of a cob-web, and the manufac- 
 ture of a watch, all equally proceed from the fiat of 
 the Almighty ; but his immediate instruments are 
 respectively the laws of attraction and repulsion, of 
 irritation, of sensation, and of thought ; and it is 
 with these laws alone that we have any thing to do 
 in philosophy.* 
 
 * That tte reader may not suppose principles such as these 
 to argue the inutility and the hopelessness of prayer, we shall 
 
182 THE NATURE OF INSTINCT. 
 
 As the primary seat of irritability seems to be, 
 at least in animals, the system of nerves called gan- 
 glions, so that of sensibility appears to be, not — 
 
 lay before him the opinions of Dr Chalmers, and of Mr Taylor, the 
 author of the Natural History of Enthusiasm, upon this most 
 important subject ; it has been admirably dis^cussed by the Reve- 
 rend Divine in his treatise on the Doctrine of a Special Provi- 
 dence and the Efficacy of Prayer (^Chalmers' Woiks, ii. 358); 
 and to this work we must refer the reader for detailed argu- 
 ments to shew that the answer to prayer may be effectively 
 given without any infringement on the known regularities of na- 
 ture. These regularities consist in the invariableness of certain 
 successions, each term of which is the consequent of the one 
 that went before it, and the antecedent of the one that cornea 
 after it. Grant that the contiguous links of any one chain, as far 
 upwards as we are able to trace them, follow each other in precise- 
 ly the same order, it should be recollected of the chief terres- 
 trial processes which are going on around us, that the chain does 
 not terminate at the point where our observation terminates — 
 that, somewhere along the ascent of our investigatioa, the me- 
 chanism ceases to be palpable, and begins to be obscure, till at 
 length it is shrouded, as if by an impenetrable veil, from our no- 
 tice altogether ; and that although we can trace the steps of a 
 casual progression a certain way back, it loses itselt at last among 
 the recondite places of the mechanism. Now, it signifies not to 
 the final result, whether the answer to prayer be given by a re- 
 sponsive touch from the finger of the Almighty at a higher or 
 lower place in the progression, as a change upon any of the 
 terms, wherever it may be situated, will have a controlling effi- 
 cacy on all the succeeding ones. Let the change, then, be ef- 
 fected far enough back, and there will be the alteration of a se- 
 quence no doubt, but without violence to any ascertained law — 
 because a sequence beyond the reach of all our philosophy. Prayer 
 may obtain its fulfilment without any visible reversal of the con- 
 stancies of nature — provided that its first effect is upon some la- 
 
THE NATURE OF INSTINCT. 183 
 
 as was formerly supposed to be the case — the brain, 
 but the posterior portion of the spinal chord. The 
 appearance of a spinal chord, as we rise in the scale 
 
 tent and interior spring of the mechanism, and not among its 
 palpable evolutions. Let but the touch of communication be- 
 tween the Deity and His works, when He goes forth to meet 
 the desire of any of his creatures, be behind or underneath that 
 surface which marks and measures off the farthest verge of man's 
 possible discovery, and then there may be many a special request 
 which receives as special an accomplishment, yet without dis- 
 turbance to those wonted successions which neither the eye of 
 man, nor his nicest instruments of observation, shall enable him 
 to ascertain. Such is the opinion of Dr Chalmers (p. 336) ; 
 Mr Taylor advances an hypothesis which has peculiar recom- 
 mendations. His conception is, that the history of nature and of 
 society is made up of innumerable progressions, in lines which per- 
 petually cross each other, and which, at their point of intersection, 
 receive a new direction, in virtue of the lateral impulse that has 
 come upon them. When an individual receives an answer to his 
 prayer, the interposition might be made, not in the line which he 
 himself is describing, but in one of those which are to meet him 
 in his path ; and at a point, therefore, where, even though the visi ■ 
 ble constancy of nature should have been violated, yet, as being at 
 the time beyond the sphere of his observation, is a violation not vi- 
 sible to him. The reader will observe the advantage this hypothesis 
 has over that of Dr Chalmers ; for, as he himself says, " in the 
 one the interposition, as being made at an anterior place in the 
 scale of causation, might require at times to be made, not in an- 
 swer to prayer, but in anticipation of it ; while in the other, the 
 interposition if made, at however little a way from the point of 
 junction, might be made both after prayer and beyond the direct 
 cognizance of the supplicant.'' 
 
 That God is the * ' hearer and the answerer of prayer," and 
 ♦' a very present help in the time of trouble,'' every Christian 
 snust feel to be true ; but how he is so, without any infringe 
 
184 THE NATIRE OF INSTINCT. 
 
 of animal creation, precedes that of a brain exactly 
 in the ratio that sensation precedes reason ; and, 
 in the human fetus and infant, the former is de- 
 veloped before the latter precisely in the same 
 ratio. 
 
 That the brain, moreover, is not the sensorium, 
 seems to be proved by the facts, that sensation is 
 impeded only when the base of the brain — the part 
 by which it immediately communicates with the 
 spinal chord — is injured ; that if only one side of 
 the brain have been injured, the impediment to sen- 
 sation is experienced only, or chiefly, on the oppo- 
 site side of the body, which can be attributed only 
 to the crossing of the fibres from right to left and 
 vice versa, found to take place about the summit of 
 the spinal chord ; from which, therefore, and not 
 from the brain, it may be inferred that all the sen- 
 sific nerves immediately arise ; that the impedi- 
 ment to sensation is, in these cases, often recover- 
 able, which it could not have been had the injury 
 of the brain operated otherwise than indirectly in 
 producing it; that sensation often survives, in the 
 
 ment on the visible sequences of nature, seems, perhaps, after 
 all, a mystery ; and it may be more philosophical at once to pro- 
 claim our ignorance — at once to confess with the Psalmist, that 
 such knowledge is too wonderful for us, too high to be attained 
 unto, than involve ourselves in speculations absolutely beyond 
 the reach of human faculties even in their highest and most 
 exalted states of development ; and only to be understood by 
 Hira who " measured the waters in the hollow of His hand, and 
 meted out heaven with the span, and comprehended the dust of 
 the earth in a measure, and weighed the mountains in scales^ 
 and the hills in a balance." 
 
THE NATCRE OF INSTINCT. 185 
 
 lower parts of the body, a total separation of the 
 brain, effected either experimentally or by disease, 
 or accident, from that part of the spinal chord which 
 sends nerves to these parts ; and, lastly, that, while 
 a lesion of the brain in general is totally unfelt, a 
 lesion of the posterior columns of the spinal chord, 
 or of the nerves connected with them, is attended 
 with the most agonizing pain. Further, it is suffi- 
 ciently well known that very many of the inferior 
 tribes of animals far excel man in the acuteness of 
 their sensations — as, among birds, the eagle, spar- 
 row-hawk, and kite in sight, the owl in hearing, 
 the vulture, raven, rook, and wood-cock in smell, 
 and others probably in some of the other senses — 
 which could not have happened had the brain, in 
 the relative size of which man so far surpasses all 
 other animals, been the sensorium, but which is 
 easily explained by the admission, that the imme- 
 diate seat of sensibility is the spinal chord, in the 
 relative size of which man falls so far short of brutes 
 in general. And do we not tacitly allow that such 
 is the case, by continually using the expression of 
 sensual as the direct antithesis to that of intellec- 
 tual ; since, if the immediate seat of intellect be, 
 as it is universally admitted, the brain, it is obvious 
 that some other seat must be assigned for a faculty 
 which is thus, by common consent, opposed to it ? 
 It is, then, to the posterior columns of the spinal 
 chord, and not as Monsieur Virey has done, to the 
 ganglionic system of nerves that we are disposed, 
 in animals, to refer these motions properly called 
 instinctive. 
 
( 186 ) 
 
 CHAPTER IX. 
 
 THE NATURE OF THOUGHT. 
 
 The third and last faculty possessed by animals, 
 although perhaps by still fencer than sensibility, is 
 the FACULTY OF THINKING ; and, as sensibility ap- 
 pears to be acted on only by irritation as its proper 
 stimulus, so this faculty seems to be acted on, in 
 the same capacity, only by sensation. Thought, 
 then, is not, any more than sensation or irritation, 
 any thing substantial ; it is not an entity, but a 
 mode of being, and consists in certain phenomena, 
 peculiar to the higher orders of living beings, and 
 necessarily resulting from one property of their 
 organization — the faculty of thinking — in action. 
 And this view of the matter we are particularly 
 anxious of inculcating, from the persuasion that it 
 is from the want of it that much of the difficulty 
 commonly supposed to attend the investigation of 
 tlie mental operations, has arisen. It is a prevail- 
 ing impression that these operations are always iso- 
 lated, and have no parallel in the animal economy ; 
 and the actions of the body and those of the mind 
 — the business of physics and that of metaphysics — 
 
THE NATURE OF THOUGHT. 187 
 
 have been generally regarded as directly contrasted 
 with each other. We know matter, it is commonly 
 urged, only by its properties, — extension, impene- 
 trability, and so forth ; and we know mind also only 
 by its properties, — attention, comparison, judgment, 
 and the like ; and where two sets of properties are 
 so decidedly dissimilar from each other, they must 
 indicate, it is argued, different entities. Thought, 
 then, in this view of the subject, may be attached 
 to matter, but cannot be a mode of being of mat- 
 ter; since matter, in no case, it is alleged, mani- 
 fests those indications, by which we recognise mind. 
 In no other case, certainly ; for in no other case is 
 the organization of matter such as to be suscepti- 
 ble of this mode of being. But are the indications 
 of mind, it may be asked, more distinct from those 
 of matter in general, than the indications of sensi- 
 bility — sight, hearing, smell, and so forth ; or even 
 than those of irritability — muscular contraction, se- 
 cretion, absorption, and other organic actions ? Cer- 
 tainly not ; so that, if a difference in properties ne- 
 cessarily evinces a difference in entities, we must 
 regard irritation and sensation, not as mere modes 
 of being of matter proceeding from certain facul- 
 ties or susceptibilities, the results of its peculiar 
 organization, but each as a distinct entity, attached 
 to matter in the same manner as th<^ght is pre- 
 sumed to be. They all consist in p^bptions of a 
 certain character, corresponding to the susceptibi- 
 lity of the organ acted on, and the power acting. 
 The muscular fibre must have perceived the sti- 
 
188 THE NATURE OF THOUGHT. 
 
 mulus, whatever it were, which called it into action, 
 or it would not have contracted ; and tlic sensorium 
 must have perceived the stimulus of the irritation 
 of the eye, or it would not have seen : the seat of 
 the faculty of thinking does nothing more tlian per- 
 ceive tlie stimulus of certain sensations, and thought 
 is the result, the consciousness of which, over- 
 whelming as it is, is only proportioned to the ex- 
 tent of its proper organ, — which is naturally iden- 
 tified, as it were, with the individuality of the 
 brain to which it belongs, — and the sublimity of 
 the function which it exercises. If, then, by the 
 word mind, we understand the faculty of thinking, 
 it is as decidedly an attribute of one part of the 
 corporeal system, as irritability and sensibility are 
 of the others. But no one has regarded irritability 
 as constituting a branch of study quite distinct from 
 the other properties of matter in general : it is true, 
 it is proper to organized or living matter ; but it is 
 as characteristic of this, as any chemical or mecha- 
 nical property of inorganic matter, — as combustibi- 
 lity of phosphorus, for example, or elasticity of 
 ivory. But irritability is certainly equally remote 
 from the other properties of matter in general, as 
 sensibility is from irritability, or the faculty of 
 thinking, again, is from sensibility. There is the 
 strictest analogy between them all ; and it is an 
 analogy which the physiologist should never lose 
 sight of, since it is only so far as this analogy is 
 admitted, that the operations of the mind become 
 a legitimate object of physiological investigation. 
 
THE NATURE OF THOUGHT. 189 
 
 Nor is this view of the matter in any degree ini- 
 mical, as is sometimes vaguely supposed, to the 
 purest and loftiest religion : on the contrary, it 
 seems to be the only view which is easily reconcil- 
 able with its dictates. The hackneyed arguments 
 against it, founded upon its supposed impiety and 
 immoral tendency, all seem to proceed upon the 
 erroneous assumption that the soul and the mind 
 are identical.* But who that has watched for five 
 
 * It is a very common impression — and one very far from 
 being confined to the uneducated — that not only is the supposed 
 principle of Thought and the real principle of Immortality iden- 
 tical with each other, but also the vital principle and the sensi- 
 tive principle ; and all four have had applied to them the same 
 name, as Soul, Spirit, &c. An attempt was indeed made at a 
 semi-distinction by Aristotle, who, while he confounded together 
 the Vital, Sensitive, and Immortal Principles, under the general 
 name of "^vpf^h or EvT-Xi;^stoc, still subdivided this into the 
 e^t^nxTi, or simply Vital, and the AttrdfrrtKh, or Sensitive and 
 Immortal, and at the same time admitted a distinct Rational 
 Principle under the name of N«vj or ^^hv ; and a similar dis- 
 tinction was affected by the Romans, who, while they called the 
 Vital and Sensitive Principles collectively Anima, distinguished 
 the Rational by the name of Animus or Mens. Thus Juvenal — 
 
 " Indulsit communis Conditor illis 
 Tantum Animas, nobis Animum quoque," &c. 
 
 Galen again tried an arrangement somewhat different, split- 
 ting the Vital nvsvju,a.ra into two classes, under the names 
 of proper Vital and Natural, while he packed on the contrary 
 the Sensitive and Rational together, under the nauie of 
 Animal. None of these proposed distinctions, however, were 
 «V3r steadily maintained ; and indeed it was impossible that they 
 should be so, thus discordant and irreconcilable as they were. 
 Dr Barclay indeed coolly argues that they were all unfounded ; 
 
190 THE NATURE OF THOUGHT. 
 
 minutes the actions of a dog — to descend no lower 
 in the scale of animals — can be so blind as to deny 
 that he possesses attention, comparison, judgment, 
 reason, liope, fear, love, animosity, — all the intel- 
 lectual faculties and passions, in short, in the dis- 
 play of which thought consists ; yet who will attri- 
 bute to a dog an immortal soul ? 
 
 And here we are unwillingly obliged to digress ; 
 for in denying to the lower animals the possession 
 
 and that the four substances in question, real and supposed, are 
 in fact all the same. The Immortal Principle he every where 
 identifies with the rational, as being responsible for the back- 
 slidings of the latter ; and the Rational again must be identical, 
 he infers, on the one hand with the Sensitive, and on the other 
 with the Vital, for " What," says he, " can it will or think with- 
 out feeling, and how can sensation iubslst without life ?" (On 
 Life and Organization, 1822, p. 495.) Upon such principles 
 a« these we might undertake to prove, on the one hand, that a 
 surety is identical with the man for whom he is bound, and, on 
 the other, that the second story of a tenement is identical with 
 the first, and the third with the second, because they cannot 
 respectively subsist independently of each other. Mr Abernethy 
 had some time before contended against confounding perception 
 and intelligence with mere vitality (Mr Hunter s Theory of 
 Life, 1814); and Dr Pritchard rationally concludes that at 
 least the Vital principle and the Sentient, Cogitative, and Im- 
 mortal principle — all which he unfortunately regards as one and 
 
 the same " supposing for a moment that both really exist, are 
 
 entirely distinct in their nature and attributes.'' (On the Vital 
 Principle, 1829). To a similar effect, says Dr Alison, " What- 
 ever notion we may entertain respecting the existence of a Vi. 
 tal principle, it has no connection with our notion respecting 
 the Existence of Mind,'' &c. (Outlines of Physiology, 183 1, 
 p. 3.) See Fletcher, part ii. and p. 32. 
 
THE NATURE OF THOUGHT. I9I 
 
 of a soul, we think it necessary to state, before pro- 
 ceeding with our argument, that there is one pas- 
 sage in Scripture, with which the view we have 
 taken may seem to be inconsistent. It is in Ro- 
 mans VIII. ] 9 — 23, and is as follows : — " For the 
 earnest expectation of the creature waiteth for the 
 manifestation of the sons of God. For the crea- 
 ture w^as made subject to vanity, not willingly, but 
 by reason of him who hath subjected the same in 
 hope, because the creature itself also shall be de- 
 livered from the bondage of corruption, into the 
 glorious liberty of the children of God. For we 
 know that the whole creation groaneth and tra- 
 vaileth in pain together until now ; and not only 
 they, but ourselves also, which have the first fruits of 
 the spirit, even we ourselves groan within our- 
 selves, waiting for the adoption, to wit, the redemp- 
 tion of our body." We need not inform the hiero- 
 logical reader that this passage has no parallel, nor 
 of the difficulties in which it is supposed to be in- 
 volved. At least three very distinct interpreta- 
 tions have been proposed, each claiming the sup- 
 port of distinguished names. By the " whole cre- 
 ation" some commentators understand all terres- 
 trial created existence, animate and inanimate, 
 making the words Trxa-n >j xT/e-<?, denote the whole 
 creatures of God, which, as they were cursed for 
 the sin of the first man, may, by a beautiful rheto- 
 rical image, be represented as groaning together 
 under that curse, and earnestly wishing to be de- 
 livered from it. But such images are not unusual 
 
192 THE NATIRE OF THOUGHT. : «♦ 
 
 in Scripture : thus the mountains and hills are said 
 to break forth into singing, the trees to rejoice, and 
 the fields to clap their hands : mere poetical images 
 to express a happy state attended with joy and ex- 
 ultation, and as such, in common use, among pro • 
 fane writers. Virgil, in the same strain, says, 
 
 " Ipsi laetitia voces ad sidera jactant 
 Intonsi montes ; ipsae jam carmina rupes, 
 Ipsa sonant arb\;-ta.'' 
 
 Other commentators following the analogy of the 
 n*^Dj limit it to the human race ; while a third 
 party make it synonymous with the new creation, 
 viz., real Christians and true believers. If either 
 of the last two views be correct — and it will be 
 allowed, at least, that a very high probability at- 
 taches to any opinion supported by such names as 
 Schleusner, Le Clare, and Koppe — then the passage 
 has no reference whatever to the lower animals. 
 But even if the first be adopted, if the expression 
 must be viewed as comprehending the brute crea- 
 tion, it does not, by any means, necessarily involve 
 their immortality. It might be viewed as intima- 
 ting that the lower animals are to participate in the 
 blessings of the Millennium. But this would not 
 imply that the present individuals are then to be 
 raised up, only that the individuals then existing 
 shall feel the influences of millennial peace. If we 
 were to say that the day is coming when the popu- 
 lation of America shall all enjoy their freedom, it 
 would not be understood as intimating that every 
 individual slave who now groans in bondage should 
 
THE NATURE OT THOUGHT. l^.*^ 
 
 •see that day, but only that all the slaves then in life 
 would be set at liberty. If a similar interpretation 
 be apphed to the passage before us, all difficulty will 
 vanish ; at any rate, the view which makes all cre- 
 ated beings to be waiting for the manifestation of the 
 sons of God, that is for immortality, seems to us 
 quite contradictory of Ecclesiastes iii. 21, which ex- 
 pressly tells us that the " spirit of the brute goeth 
 downwards,*' and is at an end ; while the immortal 
 soul of man " goeth upward" to the God who gave 
 it. The interpretation that makes man the " crea- 
 ture" of which St Paul speaks, seems, however, to 
 us the most correct ; and we most fully agree with 
 Dr Macknight in his view of the subject ; which, 
 to obviate any difficulty, we here present to our 
 readers. " In verse 21," says that learned and 
 reverend doctor, " where it is said, that the creature 
 itself will be liberated from the bondage of corrup- 
 tion, into the freedom of the glory of the children 
 of God, and the antithesis, verse 23, not only they 
 but ourselves also, shew that the apostle is speak- 
 ing, not of the brute and inanimate creation, but of 
 mankind, and of their earnest desire for immortality. 
 For these reasons, and especially because, Mark 
 xvi. 15, preach the Gospel, •Trxirvi « xt^s-;^, to every 
 creature, means to every human creature, I think, 
 •Tretayt vt y.TKri<;, in this versc, and vi KTio-ig, in the three 
 preceding verses, signify mankind in general, Jews 
 as well as Gentiles. In Col. i. 23. also, Trccc-r, -^ kti- 
 c-ig signifies evert/ hutnan creature." {Machnighfs 
 Translation.) 
 
 N 
 
\[)A IHE NATURE OF THOLLJHT. 
 
 But to I't'tuni to our argument that soul and iiiiiid 
 are not alter et idem ; let us adopt another, and per- 
 haps a more pertinent illustration, because it is fur- 
 nished by a certain psychological condition ofthehu- 
 man mind itself. We have hitherto contemplated and 
 treated the mind in its healthy, vigorous, and natural 
 state, let us turn for a moment to the phenomena 
 which attend its disease, decay, and, we speak advi- 
 sedly, its death. Physicians owe one-half of their dis- 
 coveries to a consideration of the functions of the dif- 
 ferent organs of the system, when deviating from the 
 standard of health, when interfered with or suspend- 
 ed ; and may not metaphysicians learn something, 
 nay much, from investigating the operations of mind 
 when they are disturbed by disease, whether that pro- 
 ceed from an abrogation of the laws by which they 
 are governed, or from structural changes affecting 
 the nervous system. It is surprising that this depart- 
 ment of philosophy cannot boast of a single student. 
 Let us then, as we have done in the case of the lower 
 animals, watch and examine the actions, and listen 
 to the words of a lunatic. We perceive in the for- 
 mer extravagance ; in the latter, inconsequence and 
 want of relation to the objects around, the mat- 
 ter under discussion, and even to the supposed state 
 of the speaker's mind ; and we know, from previous 
 experience, that neither of these features belonged 
 to the original and normal character of the indivi- 
 dual. But although the act of thinking and the act 
 of representing thought, or, it may happen, all the 
 intellectual acts, be here impaired, many of the emo- 
 
THE NATURE OF THOUGHT. 1^5 
 
 tive powers may remain in their primitive strength 
 and stability — provocation may excite anger, kind- 
 ness may eHcit affection, there may even remain 
 a strong devotional feeling ; the mind may be said 
 to be partially injured, and mutilated, or, if the 
 expression displease, to be capable of being affected 
 in certain modes only, or to resolve itself into cer- 
 tain states only. There are here obviously pre- 
 sented two facts, an original constitution of entire- 
 ness, and secondly, a new condition in which cer- 
 tain qualities of the former are altogther wanting, 
 and certain others, modified in consequence of these. 
 Moreover, these changes are not cognisable, or are 
 not recognised, by the mind in which they have 
 taken place. Consciousness fails to indicate either 
 that processes of thought are diflPerent, or that 
 the means by which these processes are carried on 
 are different from what they were at a particular 
 time, or during the whole period to which memory 
 extends ; and the individual lives on persuaded of 
 the uninterrupted continuousness of his ideas, and 
 of the identity of his powers. What becomes, it 
 may be questioned parenthetically, of the argument 
 that the mind is immaterial because it is unchange- 
 able ; that while the particles of the body are so 
 transitory as to lead to a renewal of the whole mass 
 in the lapse of a few years, the immaterial and im- 
 mutable mind remains the same, with the exception 
 of such alterations as culture may produce on it 
 to-day and for ever ? We shall not insist, because, 
 from the abundance of more conclusive reasons, 
 
UK) THE NATURE OE THOUGHT. 
 
 there is no necessity for insisting, on the fact that 
 this admission of alterations, being brought about 
 by education, settles the question, and shews that the 
 thinking principle docs undergo change, and that 
 of great magnitude. But here are alterations? 
 amounting to the obliteration of whole classes of 
 faculties ; here is that principle shorn of some, of 
 one-half or two-thirds, of itsmost glorious attributes, 
 and yet we are called upon to admit that it con- 
 tinues, while the worn out elements of the body 
 with which it is connected, are cast off and are re- 
 })laced, and, under all circumstances, invariably the 
 same in essence and in mode of action. It is un- 
 necessary to prosecute the inquiry ; and to revert 
 to the original investigation. We have depicted, 
 and the picture is faithfully drawn from life, a being 
 possessing a mutilated mind, but without any con- 
 sciousness of such mutilation. Now, it would be 
 well to know from those who contend for the iden- 
 tity of mind and soul, if it be the immortal soul that 
 is here injured ; if it be the spirit which has suf- 
 fered obscuration ; and if the individual be actually 
 the same individual, seeing that his soul has sus- 
 tained a complete transformation, and that he thinks 
 and feels without any, or with an imperfect recol- 
 lection of, or reference to, his original condition. 
 These are difficulties, we apprehend, which it will 
 require some ingenuity to move. But the illustra- 
 tion is not exhausted. If we contemplate the same 
 individual at a more advanced period of the disease, 
 when, in technical language, he has become fatuous, 
 
THE NATURE OF THOUGHT. 197 
 
 ^e discover not merely that solitary powers are 
 impaired, or that a portion of intellectual vigour is 
 abstracted, but that the whole mind is ruined and 
 annihilated : we find that all healthy volitions, and 
 all eccentricities, and extravagancies, alike have 
 disappeared ; that no manifestation of mind can be 
 elicited ; that even the senses are in a state of hebe- 
 tude ; that we are examining a living, breathing 
 automaton, without judgment, memory, emotion, 
 even without sensation. Now, here is a case, and 
 it occurs every day, where there exists no evidence 
 of the existence of a mental process, where indeed 
 there is demonstrable proof that all mental proces- 
 ses have ceased. And are we accordingly justified 
 in holding that it is the immortal soul which has been 
 extinguished ; that our spiritual nature has ceased 
 to exist, in consequence of some organic change in 
 the structure or functions of the body ? Those who 
 believe that mind and soul are synonymous, that 
 acts of judgment and states of feeling are really acts 
 and states of soul, must hold some such opinion. 
 It is true that this dark and dreadful conclusion may 
 be made to assume a less repulsive aspect ; but di- 
 vested of those qualifications which sophistry may 
 supply, it resolves itself into the plain statement that 
 mind and soul are one, and that mind may be in- 
 jured and destroyed. Surely it is more preferable 
 to conclude, that the display of mental acts de- 
 pends, at present, on certain conditions of organi- 
 zation, and that they may undergo changes, or sus- 
 pension^ while the soul is in no other degree affected 
 
If).^ THE NATURE OF THOUGHT. 
 
 l)y the circumstance than is matter when it loses its 
 rotundity, its angularity, its colour, or any other 
 secondary quality, or, to employ another comparison, 
 as it, itself, is in the child before the evolution of 
 these qualities ; and that it awaits, in its original 
 essence, the day-spring of anothcT state of existence 
 to resume these, or put forth other powers, under 
 such laws and conditions as may be appointed by 
 almighty wisdom and love. 
 
 There is still another aspect in which the subject 
 may be presented. It is afforded by certain consi- 
 derations springing out of the discussion as to the 
 emphatic " Ego," and seems to establish the distinc- 
 tion between mind and soul. The argument is 
 contained in the two states, what is thought and 
 what thinks. We judge, entering upon a chain of 
 reasoning in which a multitude of ideas and associa- 
 tions are presented, in which new arrangements of 
 thought are suggested, and so forth : now, how is it 
 known to the individual, thus judging, that it is by 
 him and in him that the process is carried on ? 
 Evidently by consciousness ; — then, that the pro- 
 cess is present to the mind, and that the mind knows 
 that it is present, is a proposition on which alt 
 men are agreed. But even from this proposition, 
 we must unavoidably infer, that the mind is some- 
 thing apart from its own acts ; that they may be 
 present to it or not, and yet it continues the same ; 
 that the mere states designated reflecting and feel- 
 ing, are states, or qualities of something, but that 
 they do not and cannot constitute that thing itself. 
 
THE NATURE OF THOUGHT. 199 
 
 If this be correct, it follows, that besides what is . 
 generally treated as mind, these states namely, there 
 is a more remote entity, with which these states 
 may, or may not, be associated. Further, if such 
 be the case, and the mind or soul preserve its iden- 
 tity, whether these states be present or not, the 
 phenomena of madness are to be explained on the 
 ground that certain of these states are not present, 
 or are present in an imperfect manner. 
 
 The existence of a soul, attached during life to 
 the body of responsible /men, and surviving to all 
 eternity, a divine gift to that creature alone, who, 
 from the paramount perfection of his faculties, or 
 as alone competent to recognise his almighty Crea- 
 tor, and to acknowledge the allegiance which he 
 owed to him — we are explicitly taught to believe ; 
 but it is a belief of faith rather than of demonstra- 
 tion, and to be determined not so much by its sus- 
 ceptibility of proof, as at once by its verisimilitude, 
 and by our confidence in the authority on which it 
 rests. Can any one contrast — as every one does 
 and must do — the chaotic condition of the moral 
 world in this state of our existence, with the harmo- 
 nized operations of the physical, and, knowing that 
 they are equally directed by the same Omnipotent 
 Hand, avoid believing that the Deity has set apart his 
 own time for rectifying this temporary derangement, 
 if, indeed, it may so be termed ; and when, in ad- 
 dition to this intuitive persuasion, universal in every 
 tribe of mankind, from the highest to the lowest, 
 
•200 THE NATDHE OF THOIGHT. 
 
 we have the assurances of Revelation to the same 
 effect, we have the less need to look to physical 
 j)hilosophy to corroborate it, or at least we should 
 allow no j)Ower to physical philosophy to shake our 
 conviction of its truth. The two subjects seem to 
 be totally unconnected. " I have no hope of a fu- 
 ture existence," says a late talented Professor of 
 Divinity in the University of Cambridge, " except 
 that which is grounded in the truth of Christianity." 
 We could never have inferred the existence of an 
 immortal soul in man from any phenomena of thought ; 
 and that the former is something essentially distinct 
 from the latter — which is nothing, at least nothing 
 substantial — is unquestionable. So far, then, we 
 know wliat the soul is not — what it is it will be time 
 enough to investigate when we can conceive the 
 nature, distinct from the properties, of the least of 
 the particles entering into the composition of one 
 of the filaments of the down upon a blade of grass ; 
 though should we succeed in comprehending this> 
 and much more than this, what right should we still 
 have to presume that nothing can exist which was 
 beyond the sphere of our comprehension ? We can- 
 not conceive, it is said, the nature of the soul, dis- 
 tinct from thought. God alone knows how little 
 tlie most profound of us, big with the conceit of 
 penetrating into the sublimest mysteries of his great- 
 est works, really and truly knows of the most fami- 
 liar features of the least of them ; and God, it is to 
 be hoped, will pardon, through the merits of our great 
 Mediator,, at once the rash flippancy with which the 
 
THE NATURE OF THOUGHT. 201 
 
 firmest and the best persuasions of natural religion, 
 and the most sacred doctrines of Revelation, have 
 been sometimes braved, because they were falsely 
 supposed to be incompatible with philosophy ; and 
 the bigoted blindness with which the most obvious 
 deductions of philosophy have been at other times 
 spurned, because they were falsely supposed to mi- 
 litate against natural religion and revelation. The 
 nature of the soul is probable such as man, in his 
 present state, has neither words to describe, nor 
 faculties to understand ; his efforts to do so, like 
 those of one born blind, to conceive and describe 
 the nature of light, are perhaps as irrational in their 
 object, as they have hitherto been unsuccessful in 
 their result ; and, for aught we know, a sixth sense, 
 in addition to those which he possesses for who 
 shall say that every possible mode of sense has 
 been in man exhausted ? — with all the new ideas 
 which would thus be excited, and all the new 
 symbols to which these ideas would give rise, may 
 be necessary before it can be comprehended and 
 expressed. We can infer only that the soul is not 
 any thing which we have in common with, not only 
 quadrupeds, but birds, reptiles, fishes, and even in- 
 sects — that it is not, therefore, merely the faculty 
 of thinking — and the withering and impious infer- 
 ence accordingly which has sometimes been drawn 
 by confounding the condition of man with that of 
 other animals, is totally unwarrantable. 
 
 We have insisted so much on the expediency of 
 viewing the operations of mind merely as the result 
 
202 THE NATURE OF THOUGHT. 
 
 of a material organ, for two reasons, one of which 
 was before hinted at, namely, because the assump- 
 tion, that the mental faculties are spiritual in their 
 nature, seems calculated to interfere with the pro- 
 gress of the true physiology of the nervous system ; 
 and secondly, because we think the cause which 
 that assumption is destined to serve, the cause of na- 
 tural religion, is materially injured by it. The im- 
 portance of right notions on such subjects to all, 
 and the particular importance to ourselves individu- 
 ally, that our sentiments on this point should not be 
 misapprehended and confounded with the opinions 
 of those who are the enemies of true religion, will 
 warrant a slight digression from what is strict phy- 
 siology at this place. 
 
 It is not because we join with those, who repro- 
 bate the reasoning from final causes altogether in 
 philosophy, that we object to the assumption of the 
 spiritual nature of mind ; but because, while we 
 contend, that this doctrine is, on all occasions, in 
 physiology, to be used with the utmost caution, it 
 seems to be particularly liable to lead into error and 
 retard the progress of knowledge, in regard to the 
 functions of the nervous system. In this depart- 
 ment of physiology we generally, but absurdly, set 
 out with ideas of spirit drawn from reflection on the 
 subjects of our own consciousness, that is, from the 
 consciousness of the only animal which possesses 
 it in the most extended range ; and with a determi- 
 nation to see nothing that shall interfere with our 
 preconceived notions of the adaptation of this spirit- 
 
THE NATURE OF THOUGHT. 203 
 
 ual nature to immortality, attempt to apply our prin- 
 ciples to the rest of the animal kingdom. Is it sur- 
 prising, then, that so little progress has been made 
 in the metaphysics, if we may so term it, of the 
 lower animals, when such a mode only of cultivating 
 it has been usually practised? This is indeed, as 
 Lord Brougham remarks in his Discourse on Na- 
 tural Theology, " The great abuse of the doctrines 
 of final causes ; and the more to be dreaded because 
 of the religious feelings which are apt to mix them- 
 selves with such speculations, and to consecrate 
 error." This is a limitation, we should observe, 
 made in an eloquent argument in favour of the use 
 of final causes in philosophy, from the general scope 
 of which we are very far from dissenting. The true 
 method, certainly, of cultivating the physiology of 
 the nervous system, is to examine its phenomena 
 where they are least numerous, and the organs con- 
 cerned least complex ; and thus to proceed onwards, 
 while the development of function is traced, as new 
 structure is again and again involved. We may 
 discover the source of most of the systems of instinct 
 in the opposite mode of investigating this subject, 
 that in which the properties ascertained as apper- 
 taining to man being received as the groundwork 
 on which was to be reared the whole system of 
 nervous function throughout the animal kingdom. 
 Cogito, ergo sum, said the Cartesian, (to which as 
 a mere part of human metaphysics, no objection 
 arises) ; but setting out to the investigation of the 
 animal nature, he came to the very absurd con- 
 
204 THE NATURE OF THOUGHT. 
 
 elusion, that all the inferior animals were meie auto- 
 mata, machines wound up to go througli a certain 
 amount of evolutions before their machinery ran 
 down, being altogether void of consciousness. Buf- 
 fon's inclination and aversion as the springs of ac- 
 tion in animals, are of the same character. The 
 same kind of investigation ledHelvetius and Darwin 
 to their theory of reasoning being the source of all 
 animal phenomena ; in which, as instinct plainly 
 excels reason in the perfection of its acts, they have 
 somewhat overstepped the model on which their hy- 
 pothesis is constructed. * And the same may be 
 said of many such speculations. 
 
 But, while this mode of considering mind is ob- 
 viously adverse to the progress of physiology, we 
 affirm that it is also injurious to the cause of natu- 
 ral religion, which it is intended to serve. Our 
 hopes of immortality, we remarked before, rest, in 
 our opinion, exclusively on Revelation. Perhaps a 
 probability of a future state of existence is afforded 
 by the light of nature ; but this simply illustrative 
 of the word of God, which must altogether form 
 the ground-work of our faith, as we have elsewhere 
 observed, and now hope to prove. As it appears 
 
 * Lord Brougham observes, at page 75 of his Discourse on 
 Natural Theology, " that the operations of pure instinct have 
 never been supposed by any one to result from reasoning." 
 Pythagoras and Plato, however, among the ancients ; and Hel- 
 vetius, Condillac, Smellie, Hill, Hume, and Darwin, among the 
 moderns, have, with various modifications, absolutely identified 
 instinct with reason. 
 
THE NATURE OF THOUGHT. 205 
 
 to US, no part of any probability of a future state 
 arises from the consideration of the actual nature 
 or properties of mind. It should be viewed as ex- 
 isting altogether on an independent footing ; and 
 the argument for it should run, not as a part of 
 physiology, but as a branch of natural theology 
 seeking light from it, as well as from every other 
 science. 
 
 Lord Brougham is the latest, as he is the most 
 distinguished writer, who has attempted to prove 
 an hereafter independently of Revelation. He has 
 devoted two most eloquent sections, and four very 
 erudite notes, of his Discourse upon Natural Theo- 
 logy, to this subject ; and as, when we reply to him, 
 we go at once to the " head and front of the of- 
 fending," we shall proceed to analyze, and, we hope, 
 confute, opinions which we feel to be founded in 
 error, and likely to lead, both on account of the 
 great beauty of the language in which they are 
 couched, and the high name and character of their 
 propagator, to very serious results. The portions 
 of the work to which we particularly allude are 
 sections iii. and v. 
 
 The first of these commences with a very sweep- 
 ing charge against Paley and other writers upon 
 natural theology, to the effect that, as they avoided 
 bringing proofs of design and a designer, from the 
 structure, habits, and operations of mind, they are 
 either to be accused of carelessness, or branded 
 with a tendency to materialism. " There cannot 
 be a doubt," says his Lordship, " that this extraor- 
 
20G THE NATURE OF THOUGHT. 
 
 dinary omission had its origin in the doubts which 
 men are prone to entertain of the mind's existence 
 independent of matter. The eminent persons above 
 named were not materialists, that is to say, if you 
 had asked tliom the question, they would have an- 
 swered in the negative ; nay, they would have gone 
 further, and asserted their belief in the separate 
 existence of the soul independent of body. But 
 they never felt this as strongly as they were per- 
 suaded of the natural world's existence. Their ha- 
 bits of thinking led them to consider matter as the 
 only certain existence — as that which composed 
 the universe — as alone forming the subject of our 
 contemplations — as furnishing the only materials 
 fdr our inquiries, whether respecting structure, or 
 habits and operations. They had no firm, definite, 
 abiding, precise idea of any other existence respect- 
 ing which they could reason and speculate. They 
 saw and they felt external objects ; they could ex- 
 amine the lenses of the eye, the valves of the veins 
 and arteries, the ligaments and the sockets of the 
 joints, the bones and the drum of the ear; but, though 
 they now and then made mention of the mind, and, 
 when forced to the point, would acknowledge proofs 
 of design in it, they never were fidly and intimate- 
 ly persuaded of its separate existence. They 
 thought of it and of matter very differently ; they 
 gave its structure, and its habits, and its operations 
 no place in their inquiries ; their contemplations 
 never rested upon it with any steadiness ; and, in- 
 deed, scarcely ever glanced upon it at all. That 
 
THE NATURE OF THOUGHT. 207 
 
 this is a very great omission, proceeding, if not 
 from mere carelessness, from a grievous fallacy, 
 there can be no doubt whatever." 
 
 As to carelessness being the cause of this omis- 
 sion, that is quite out of the question, and not for 
 a moment to be entertained ; and we are inclined 
 to think that circumstances widely different from 
 those hinted at, actuated Ray, Derham, and Paley, 
 when they avoided, in their several works, to treat 
 of the phenomena of mind as illustrative of design 
 and its consequences. It is probable that they 
 never were, as Lord Brougham insinuates, fully 
 persuaded of the existence of the human faculty of 
 thinking independent of matter, for it has no such 
 existence ; but the truth would seem to be, that, 
 seeing through a glass darkly, they were unwilling 
 to add to the dim obscure ; and that, in such a po- 
 sition, they acted judiciously in omitting the sub- 
 ject altogether, is quite evident when we study the 
 very unsatisfactory conclusion drawn even by one 
 possessed of the gigantic mental powers of Lord 
 Brougham. Nay, Paley himself has given as his 
 reason for omitting the subject the uncertainty of 
 the speculation. He says, " The existence and cha- 
 racter of the Deity is, on every view, the most in- 
 teresting of all human speculations. In none, how- 
 ever, is it more so than as it facilitates the belief of 
 the fundamental articles of Revelation. It is a step 
 to have it proved, that there must be something in 
 the world more than we can see. It is a farther 
 step to know that, among the invisible things of na- 
 
208 THE NATURE OF THOIGIIT. 
 
 ture, there must be an intelligent mind concerned 
 in its production, order, and support. These points 
 being assured to us by Natural Theology, we may 
 well leave to Revelation the disclosure of many par- 
 ticulars which our researches cannot reach, as re- 
 specting either the nature of this Being as the ori- 
 o-inal cause of all things, or his character and de- 
 signs as a moral governor ; and, not only so, but 
 the more full confirmation of other particulars, of 
 which, although they do not lie beyond our reason- 
 ings and our probabilities, tlie certainty is by no 
 means equal to the importance.** 
 
 Lord Brougham states, that "the evidence for the 
 existence of mind is to the full as complete as that 
 upon which we believe in the existence of matter. 
 Indeed it is more certain, and more irrefragable. 
 The consciousness of existence, the perpetual sense 
 that we are thinking, and that we are performing 
 the operation quite independently of all material 
 objects, proves to us the existence of a being diffe- 
 rent from our bodies with a degree of certainty 
 higher than any we can have for the existence of 
 those bodies themselves, or of any other part of the 
 material world." Of the operations of the mind we 
 do indeed possess the evidence of consciousness, 
 the highest evidence of which, as intelligent beings, 
 we are capable of attaining ; and, though that evi- 
 dence in itself is not, as is assumed in the above 
 passage, of higher authority than the evidence of 
 sense, it may be conceded to his Lordship, in the 
 mean time, that it is at least less liable to some 
 
THE NATURE OF THOUGHT. 2t^ 
 
 kinds of fallacy. Yet what does this admission avail 
 to his argument ? The evidence declares nothing, 
 but the certainty of the performance of this or that 
 mental operation at such or such a time ; it sug- 
 gests nothing as to the existence of the operating 
 agent separately from the body. It proves to us 
 beyond the possibility of doubt, that by turns we 
 remember, imagine, judge, fall under emotion or 
 passion ; or become actuated by desire; but no con- 
 comitant belief of the distinct nature of the being 
 that is so affected necessarily arises. It is true we 
 feel convinced that stocks and stones never become 
 affected in the same manner — but that is a judg- 
 ment formed upon our experience — upon the repeat- 
 ed proofs furnished by our senses that no such thing 
 ever occurs in regard to them. But, so far are we 
 from feehng any original internal conviction of the 
 distinction of the sentient, intelligent, or moral part 
 of our nature from the body itself, that we cannot 
 help assigning, by the very constitution of our na- 
 ture, a material local seat to our separate mental 
 and moral affections. The natural language of man 
 lays open to us his original impression, freed from 
 the fallacies in which they are apt to be involv- 
 ed by philosophical speculations. All languages 
 make the seat of the intellect the head, while they 
 place that of the affections in the heart or viscera. 
 In this there is sufficient proof that the conscious- 
 ness of mental operations is not attended with any 
 behef in the separate existence of an immaterial 
 agent concerned in the production of them. The 
 
210 THE NATURE OF THOUGHT. 
 
 distinction of our human nature into mind and body 
 is a generalization of philosophy — it is not, we re- 
 peat, an idea necessarily arising out of the mere 
 exercise of our mental faculties ; and, as a genera- 
 lization of philosophy, it must be tried by the ordi- 
 nary tests and ordeals to which such conclusions are 
 amenable. The idea of a separate mental agent stands 
 on a very different footing from our belief in the ex- 
 istence of an external world. It is the evidence of the 
 operation of the faculties called mental, not their 
 independent nature, which rests on the same irre- 
 fragable authority as our belief in an external world. 
 The operation of the senses by which we become 
 acquainted with all that is without us, is attended, 
 by the very constitution of our nature, with an ir- 
 resistible belief in the reality of what they repre- 
 sent to us, and in the outness or separate existence 
 of the objects from which the several impressions 
 conveyed by them emanate. Nor is there a grosser 
 error to be met with in all the vagaries of pseudo- 
 philosophy than that on which Pyrrhonism rests, 
 namely, the assumption that man has one set of fa- 
 culties for the ordinary pursuits of life, and another 
 for the cultivation of philosophy. Philosophy is es- 
 sentially human. The same faculties — the same 
 powers of reasoning — the same principles of belief 
 which govern the savage in his simple course of 
 life, and the civilized citizen in the acts of indus- 
 try, are those, and those alone, which the philoso- 
 pher must make use of in his science. For science 
 essentially is the search, not after the laws which 
 
THE NATURE OF THOUGHT. 211 
 
 may, by possibility, govern nature, but after the 
 laws according to which man, by the necessity of 
 his mental constitution, must see nature. To 
 doubt, then, the existence of an external world, is 
 just as great an error in philosophy as it would be 
 in the common transactions of life. But, to place 
 the evidence of consciousness on a much higher foot- 
 ing than the evidence of sense, as Lord Brougham 
 has done in the above passage, is planting the first 
 step to Pyrrhonism — but, in this instance, it may 
 be regarded as an inadvertent hyperbole of rheto- 
 ric rather than as a logical error. 
 
 But to leave this point alone, let us consider how 
 far the distinction of our human nature into body 
 and mind, as a generalization of philosophy, will 
 bear examination. The very attempt to find a 
 name for the intelligent and moral part of man, 
 shews how little he has been made capable of form- 
 ing ideas unconnected with matter. The names 
 which have been contrived to denote this supposed 
 separate part of man's nature, are drawn from at- 
 tenuated forms of matter : this the word taken from 
 the aig^o? of the Greeks, and the spiritus of the 
 Latins, plainly enough attest. We have here, then, 
 a sort of struggle against the original impressions of 
 our nature, in the very first steps of this generali- 
 zation. But suppose that, by contrasting the ope- 
 rations of thought, feeling, passion, with the phe- 
 nomena of bodies altogether inanimate, as the 
 components of the mineral kingdom, instead of 
 comparing them with the other acts performed by 
 
212 THE NATURE OF THOUGHT. 
 
 living bodies, as secretion, nutrition, absorption, 
 we have persuaded ourselves of the existence, in 
 connection with the luiman body, of a separate 
 immaterial agent by which all mental acts are per- 
 formed, and which we conceive to be capable of a 
 continued being after the body has returned to its 
 original terrestrial elements ; how does this belief 
 fare when we bethink ourselves of looking to the 
 condition of the other tribes of beings which parti- 
 cipate life like ourselves ? Philosophy strives in 
 vain to draw a line of demarcation between man 
 and other animals in this respect. In the lowest 
 animals which exhibit a consciousness of external 
 impressions, there is already found all that is essen- 
 tial to the idea of mind. Suppose this conscious- 
 ness to be but momentary, to awake to the passing 
 impression, and to be extinguished for ever as soon 
 as that impression has ceased, as is perhaps the case 
 in some of the zoophyta, still this is not merely the 
 rudiment, but the actual essence of a mental ope- 
 ration. The consciousness of the impression made 
 by light, or heat, or the presence of aliment in 
 contact with its tentacula in a polype, is as much a 
 mental operation as that thinking independently of 
 all material objects in man, which Lord Brougham 
 says proves " the existence of a being different from 
 our bodies, with a degree of certainty higher than 
 any we can have for the existence of those bodies, 
 or of any other part of the external world." 
 
 This gives but a poor confirmation of the con- 
 clusion somewhat too hastily drawn from the con- 
 
THE NATURE OF THOUGHT. 213 
 
 sideration of man's own little world of thought, to 
 the exclusion of the rest of the animal kingdom. 
 Had we discovered in the polype evidence of the 
 existence of a separate agent on which its con- 
 sciousness depends ; that is, of an agent different 
 from that organized frame by which the phenomena 
 of life are sustained (and organized it is, however 
 simply), then might we have justly inferred, that 
 a similar agent exists throughout the numerous 
 gradations of animal life up to man, in him to at- 
 tain a development infinitely surpassing its state in 
 any of the tribes below him. But, instead of be- 
 ing able to make such a discovery, our utmost ef- 
 forts enable us only to detect a system of material 
 parts more and more developed as we ascend in 
 the scale of animals, in a proportion corresponding 
 to the degree in which each animal becomes capa- 
 ble of higher mental operations. Yet, if we have 
 persuaded ourselves of the existence of such a think- 
 ing principle, separate from the body in man, why 
 do we not extend the conclusion to the rest of the 
 animal kingdom, or at least to all in which con- 
 sciousness is discoverable ? The functions of secre- 
 tion, absorption, nutrition, are in the higher animals 
 exactly of the same character as in man ; and from 
 these there is a gradation downwards, correspond- 
 ing to the decline in the general activity of living 
 action ; why, then, should we deny a correspond- 
 ing similarity of the thinking agent to these ani- 
 mals ? Why should not consciousness be uniform- 
 ly the property of the same spiritual principle ? 
 
214 THE NATURE OF THOUGHT. 
 
 Here, however, is the Gordian knot — this conclu- 
 sion is incompatible with all that we observe of man 
 — nith all that we observe of the tribes of animals 
 below him. It is a conclusion to which our reason 
 and our feelings are alike repugnant. And, while 
 such obstacles remain in the way of this conclusion, 
 it will be vain to seek an argument in favour of the 
 existence of mind separately from the body, from 
 any consideration of its mere sentient or thinking 
 properties. 
 
 The whole tenor of Lord Brougham's third section 
 is to prove, that the phenomena of mind are more de- 
 monstrative of design and a designer than the phe- 
 nomena of matter. But, wonderful and incompre- 
 hensible as attention, memory, and the like are, and 
 all-convincing as they must be of the existence of 
 a wise and a great God, the extent of whose attri- 
 butes we cannot conceive ; they are not more so than 
 any other function of the body, such as secretion and 
 absorption ; we understand both, simply by their 
 effects, and we see both invariably associated with 
 definite forms of matter ; but, with regard to the 
 final cause of the operation of either, that alone 
 rests with the will of God. Both are admirably 
 adapted to the wants and necessities of the animals 
 in which they are displayed, — both proclaim the 
 Almighty, but the one not less powerfully than the 
 other. 
 
 The fifth section of Lord Brougham's work is de- 
 voted to the moral or ethical branch of Natural 
 Theology ; and the psychological argument, or evi- 
 
THE NATURE OF THOUGHT. 215 
 
 dence of the Deity^s design drawn from the nature 
 of the mind, opens with the grave assertion, that 
 " the immateriality of the soul," — that is the 
 mind, for Lord Brougham uses the terms synony- 
 mously, " is the foundation of all doctrines relating 
 to its future state." Now, as it appears to us, the 
 soul is something, not material, indeed, but sub- 
 stantial, a divine boon to the highest alone of God's 
 creatures, and responsible for all the actions of the 
 mind, but as totally distinct from it as one thing 
 can be from another, or rather as something is from 
 nothing ; and we think it is much to be regretted 
 that this distinction, which embraces the only phi- 
 losophical view of the nature of mind, should ever 
 have been lost sight of. It is altogether from this 
 circumstance that many men have gained for them- 
 selves the title of philosophers, at the expense of 
 one which should have been far dearer to them. 
 We shall shortly reply to Lord Brougham's argu- 
 ments to prove the immateriality of mind ; but, in 
 the mean time, we cannot at all see how such a 
 faith is necessary to salvation, or how the light in 
 which we may happen to view an abstruse and me- 
 taphysical proposition, should in the least interfere 
 with our prospects of immortality. Lord Brougham's 
 arguments are quite inadequate to prove the imma- 
 teriality of mind, and besides, they go to prove 
 more than his Lordship contemplated, namely, that 
 the functions of every other organ in the body are 
 immaterial likewise. But the argument is alto- 
 gether useless, as the Christian believes that the 
 
'il6 THE NATURE OF THOUGHT. 
 
 whole body is destined for immortal liie ; — our 
 " mortal part shall put on immortality." The God 
 who at first formed man, as we see him in all his 
 majesty and intellectual splendour, from the dust 
 of the earth, and, after a brief career, redissolves 
 him into a few pristine elements, is able, in His 
 own time, to reconstruct his work. The " limo'^ 
 we know not, but the " wherefore " is in Scripture 
 revealed to us. 
 
 Lord Brougham proceeds to " the strongest of 
 all arguments, both for the separate existence of 
 mind and for its surviving the body ;" these, al- 
 though " drawn from the strictest induction of 
 facts," are futile in the extreme, and quite overstep 
 their march, in proving, according to the conclusions 
 dra\\ni from them by his Lordship, much more than 
 he could contemplate ; they prove too much. " The 
 body," says his Lordship, and so does the physiolo- 
 gist, " is constantly undergoing change in all its 
 parts. Probably no person at the age of twenty 
 has one single particle in any part of his body whicli 
 he had at ten ; and still less does any portion of 
 the body he was born with continue to exist in or 
 with him. All that he before had has now entered 
 into new combinations, forming part of other men, 
 or of animals, or of vegetable or mineral substances, 
 exactly as the body he now has will afterwards be 
 resolved into new combinations after his death. 
 Yet the mind continues one and the same, ' with- 
 out change or shadow of turning.' None of its 
 parts can be resolved ; for it is one and single, and 
 
CF 
 
 J 
 
 THE NATURE OF THOUGHT. 217 
 
 it remains unchanged by the changes of the body. 
 The argument would be quite as strong though the 
 change undergone by the body were admitted not 
 to be so complete, and though some small portion 
 of its harder parts were supposed to continue with 
 us through life." 
 
 " But observe," continues his Lordship, " how- 
 strong the inferences arising from these facts are, 
 both to prove that the existence of the mind is en- 
 tirely independent of the existence of the body, 
 and to shew the probability of its surviving I If 
 the mind continues the same while all or nearly all 
 the body is changed, it follows that the existence 
 of the mind depends not in the least degree upon 
 the existence of the body ; for it has already sur- 
 vived a total change of, or, in common use of the 
 words, an entire destruction of that body." 
 
 If such an argument could for a moment be held 
 good, every other function of the body, in the spi- 
 rit of Lord Brougham's deductions, — and we have 
 already shewn that there are many more functions 
 than that of thought, — must be conceived to be a 
 distinct, immaterial, and immortal entity. The or- 
 gan of mind undergoes a constant change, but its 
 function remains the same, therefore that function 
 is independent of the existence of the organ, and will 
 survive it to all eternity ; — so says Lord Brougham : 
 and, from a parity of reasoning, it must follow that 
 every other function, the nutritive, the reproductive, 
 and the relative, are in like manner independent of 
 their several organs, which they will survive to the 
 
218 THE NATURE OF THOUGHT. 
 
 end of time. What are the kind of existences re- 
 served for these entities in a future state of exist- 
 ence, Lord Brougham is profoundly silent; as silent 
 as he declares Revelation to be concerning the soul 
 under similar circumstances. The doctrine, how- 
 ever, as taught by Lord Brougham, is but a return 
 to the very ancient one, which assigns the peculiari- 
 ties of the actions of the different organs of the body 
 to their being the residence of several immaterial 
 agents. The Pastophori first alluded to these, as 
 genii, or demons, or decans of the air ; and their 
 pupils of Greece believed them to preside, under 
 the controul of a great master spirit, over the func- 
 tions of the several organs of the body. By Hip- 
 pocrates and Galen, these were termed Ayv«^s<5, 
 and were considered to reside one or more in each 
 organ, in subserviency to the grand Evo^/^m, or 
 nnZf*cc ; and to be the immediate cause of the pe- 
 culiar function which it performed. Thus, accord- 
 ing to Galen, the heart was the residence of three 
 
 ^vvctuiig, the ovvce^ig oixvriXXoi^iVY), 7ri^i<mXXoiu,svi^, and 
 
 <rv<mXXofiivn, or those by which it attracted the blood 
 from the lungs, retained it for an instant, and pro- 
 pelled it through the body. The same thing was 
 understood by Van Helmont under the name of 
 ArchcBii i?isiti, the number of which almost equal- 
 led the organs of the body, though all were held 
 in subordination by one sovereign Archaeus, cor- 
 responding to the 'Tviv^x, already mentioned, and 
 supposed to hold his court in the stomach. Har- 
 vey also admits in each organ a sensus propritts. 
 
THE NATURE OF THOUGHT. 219 
 
 Subject to the general anima by which the whole 
 body was actuated ; and Glisson speaks of each or- 
 gan as possessed of a " spiritus regens qui aliud in 
 jecora, aliud in liene, aliud in pancreati, aliud in 
 ventriculo et intestinis operatur."* The subject 
 of these imperia in imperio has been prosecuted in 
 more modern times by Borden and Bichat ; as in 
 the present day it evidently is by Lord Brougham ; 
 and we have ourselves applied the doctrine, with, of 
 course, some modifications, to the explanation of 
 the action of medicine in the removal of disease. 
 {Med. Quart. Rev. 1834.) Thus, then, modern 
 authors, as remarked by Dr Barclay, " instead of 
 advancing any thing new, as they probably sup- 
 posed, have only revived one of the most rude and 
 antiquated notions in all physiology." 
 
 This argument, then, is insufficient to prove the 
 immateriality of mind ; but, strange to say, it is 
 chiefly upon the same basis, and wholly independ- 
 ent of revelation, that an attempt is made to found 
 the doctrine of the immortality of the soul. Al- 
 luding to the constant change the body undergoes, 
 Lord Brougham says this fact proves the entire in- 
 dependence of the existence of mind of that of the 
 body ; and also " the immortality of the soul, as 
 
 * It was in ridicule of this that Dean Swift represents the 
 action of a smoke-jack as depending on a meat-roasting power, 
 and that of a fiddle on a time-playing power ; and, in the same 
 spirit, Moliere makes his candidate for a physician's diploma re- 
 ply to the question, Quapropter opium facit dormire ? Quia he- 
 bet vim dormitivam. 
 
220 THE NATURE OF THOUGHT. 
 
 rigorously as * if one were to rise from the dead.'" 
 As additional evidence, however, he brings forward 
 the attributes of God ; the fact that no tribe is so 
 dark and barbarous as to be without some kind of 
 worship, and some belief in a future state ; and, 
 lastly, the analogies presented by nature. We hope 
 we have already shewn the first argument to be 
 totally inadequate to bring us to the belief of the 
 immateriality of mind, much less to the immortali- 
 ty of the soul ; and we think we can shew that nei- 
 ther the attributes of God, the universality of the 
 belief, nor the analogies presented by nature, afford 
 any proof, however illustrative they may be, of the 
 doctrine of a future state. 
 
 By the attributes of God are generally under- 
 stood his eternity and immutability ; his omnipre- 
 sence, omniscience, omnipotence, and independ- 
 ence ; his benevolence ; his justice ; his truth and 
 his mercy. We cannot conceive how any of these 
 can be brought forward to prove an after life ; in- 
 deed LordBrougham himself only devotes a few hues 
 to the benevolence of God, and even that in con- 
 junction with the feelings and wishes of the human 
 mind. The attributes of God as merely displayed 
 in the creation, would never lead us to even the 
 hope of immortality; nay, he who penetrates deepest 
 into the secrets of nature, even armed with the im- 
 mensity of mental energies displayed by Lord 
 Brougham, bringing down knowledge from the 
 heavens, digging it from the depths of the earth, 
 and searching for it through the vastness of the 
 
THE NATURE OF THOUGHT. 221 
 
 ocean, extracting it from minerals and the wonders 
 of vegetables, and the birds, and the beasts, and 
 the meanest insects, will only multiply proofs that 
 " verily there is a God," who made and rules the 
 universe. The character he will obtain of God is 
 not that by which the Christian knows him ; he 
 will discover a fearful blight upon the face of na- 
 ture, and marks of imperfection and disorder will 
 every where perplex him ; in the intellectual world 
 he will see error and ignorance, fatuity and folly ; 
 and in the moral world passions, prejudices, selfish- 
 ness, wars, cruelties, and innumerable crimes ; in 
 external nature he will find the air, and the earth, 
 and the sea teeming with agents of apparent evil — 
 whirlwinds and tempests, mildew and drought, with 
 famine and pestilence in their train, carrying deso- 
 lation abroad, while decay and death fill the world 
 with mourning. And how will man himself be view- 
 ed ? While other animals are formed with admirable 
 skill to fulfil the end of their existence, and to be 
 happy up to the extent of their capabilities, he 
 would appear to form a melancholy exception to 
 this beneficial order of nature. Formed with feel- 
 ings susceptible of the most exquisite enjoyment, 
 yet doomed to a perpetual conflict of jarring emo- 
 tions and heart-rending cares, — endowed with fa- 
 culties capable of comprehending the most sublime 
 mysteries, yet grovelling in the dust and expend- 
 ing his powers on empty trifles, — glowing with hopes 
 and desires which look beyond the bounds of time 
 and grasp eternity, yet fixing his affections on this 
 
222 THE NATURE OF THOUGHT. 
 
 little spot of earth, contented with pleasures which 
 perish in the using ; and, after dragging out a few 
 miserable and inglorious years, sinking at last into 
 the silent tomb and mingling with the clods of the 
 valley, a wretched outcast of nature and a blot on 
 the face of creation. Revelation alone explains 
 the darkness of the mystery. Neither the attri- 
 butes nor the works of God are then sufficient upon 
 which to found our hopes of an immortal life ; on 
 the contrary, they rather lead us to the belief that 
 there is no hereafter ; inducing us to regard death 
 as the most benevolent act of the Creator, as re- 
 leasing us from scenes of so much misery and dis- 
 tress. 
 
 The fact that " there is no tribe so dark and 
 barbarous as to be without some kind of worship 
 and some belief in a future state," is still no proof 
 of its existence. It is not improbable, certainly not 
 impossible, that from the earliest age, even from the 
 fall of man, a tradition of this kind should have been 
 handed down through all people and through all na- 
 tions. It is quite clear that in the curse pronoun- 
 ced against Adam, temporal death as well as spiritual 
 or eternal death was threatened. That both Adam 
 and Eve understood the nature of the curse and the 
 remedy which it promised, is plain, for he named 
 his wife, after it had been pronounced. Eve or 
 Chavoh, "because she was the mother of all living;" 
 that is, as commentators observe, of all who should 
 live for ever, by means of " the seed of the woman ;" 
 and Eve, at the birth of Cain, says, " I have gotten 
 
THE NATURE OF THOUGHT. 223 
 
 a man, the Lord ;"* that is, the promised Lord, or 
 seed, who was to " bruise the serpents head." That 
 Adam and Eve became penitent and were accepted 
 we also know ; and as there can be no repentance 
 without hope of forgiveness, we would conclude 
 that they were aware what means they should adopt 
 to remove God's wrath. They could not expect it 
 in this world, where they were condemned to hard 
 and painful toil, and to a death, at the end of their 
 being, accompanied by horror and distress. They 
 trusted they would be rewarded for their penitence 
 after this life, and they cheered their immediate 
 descendants with the same hopes through their 
 toils and their difficulties. We can conceive no- 
 thing more probable than that the same comfort 
 should have been afforded by father to son from 
 that day even to the present ; and thus this, like 
 many other traditions, which, were we so disposed, 
 we might trace from a very early period, almost 
 becomes a universal creed. The fact, as it fair- 
 ly stands, is no proof of an immortality, and the 
 above explanation is offered as a mere suggestion. 
 The feeling may, however, be instinctive, and we 
 are far from denying "that a benevolent being 
 should have implanted this propensity without the 
 
 In our authorized version, this passage is translated, ** I 
 have gotten a m^n from the Lord." That this is agreeable to 
 the Hebrew idiom, is admitted by all commentators ; but we 
 are inclined to adopt the opinion of those who have rendered it 
 as given above ; that reading appearing the most natural inter- 
 pretation of the original words, xW^l^*! J^Ji^ ^^^ *n*^D- 
 
224 THE NATL RE OF THOUGHT. 
 
 intention of gratifying it." Still, however, proof is 
 absent. Lord Brougham here refers to Note VIII. 
 which describes the ancient doctrines of the im- 
 mortality of the soul ; to this, however, we shall not 
 refer, as the explanation we have offered above of 
 the possession of such a sentiment by savages, is 
 equally applicable to heathen philosophers. 
 
 Lord Brougham concludes his " proof" by a re- 
 ference to the analogies which nature presents ; 
 his Lordship says these are " feeble helps," and 
 even of a dangerous kind — because they are drawn 
 from material objects. They are so far feeble proofs, 
 as they are no proofs : they cannot, therefore, be 
 dangerous, even though " they all rest upon the 
 properties and the fortunes of corporeal existences" 
 — which, however, they do not. The resemblance, 
 for example, between the alternation of the seasons 
 and the progress and decay of human life, is too 
 obvious to have escaped the observation of any re- 
 flecting mind. Spring is the infancy and youth of 
 the year — summer its vigorous and sober manhood 
 — autumn its mellow age, when its fruits are reap- 
 ed and its labours are at a close. At last comes 
 winter — cold, desolate, and stark — an affecting type 
 of hoary age and of death : the leafy honours of the 
 woods have fallen — the flowers and grass which 
 adorned the fields have passed away — the music of 
 the grove has ceased ; — nature, clad in a ^^dnding- 
 sheet of snow, seems to indicate, that vegetation 
 has run its course and is annihilated. But, at the 
 voice of spring, nature revives ; — the sun, which, 
 
NATURE OF THOUGHT. 22.") 
 
 skirting the verge of the sky had become feeble 
 and cheerless, resumes its genial influences, and 
 takes a wider circuit in the heavens ; — young spring 
 walks forth again in beauty — gentle zephyrs fan 
 her bosom — ^flowers spring beneath her feet — and, 
 wherever she smiles, the woods and lawns burst 
 into life, and the voice of joy resounds. This is all 
 emblematic of the destiny of man, as he undergoes 
 the various vicissitudes of growth, maturity, decay, 
 and death ; — till, hearing the creative voice of a 
 new spring, he bursts his bonds and lives again. 
 But analogies of this kind are not so striking as 
 that of those insects which, after being apparently 
 dead and entombed, rise again, as it were, from the 
 grave, and, waving their painted wings, flutter from 
 flower to flower, and seem to live in a new world, 
 amidst a paradise of sweets. But the sober and 
 undeniable truth is, that the strongest of these ana- 
 logies are nothing more than illustrations, and can- 
 not be dignified by the name of solid arguments. 
 They could not be so even if the analogy were com- 
 plete ; but it fails in its most important point. Go 
 to the tomb of the caterpillar — it is empty. The 
 same body which reposed in seeming death, has 
 burst its shell, and has only assumed a new form. 
 Go to the human tomb — the remains of what was 
 once man are still there, mouldering into dust ! 
 But the reader will ask. Where, then, are the proofs 
 of the immortality of the soul ? Jliey are alone to 
 be found in the pages of revelation, before which 
 all human reason must infallibly boM^ ; and wo to 
 p 
 
22G NATURE OF THOUGHT. 
 
 him wlio would substitute the one tor the other. 
 Such a mode of argument cannot for a moment be 
 sustained ; it leads at once to imposition and im- 
 posture, to blind obedience, superstition, and an 
 abject deference to human authority. The dicta 
 of Scripture are at once conclusive ; or, as a wri- 
 ter has well observed, " the positive evidence of 
 Scripture holds the same rank in theology as expe- 
 rimental evidence does in reference to any hypo- 
 thesis in philosophy. As, in the latter case, there 
 is no disputing in favour of a system against facts, 
 phenomena, and experiments ; so, in the 'former 
 case, no reasoning can be valid in opposition to the 
 positive evidence or express discernible autho- 
 rity." And, not only is it untheological, but un- 
 physiological, being opposed to the opinion which 
 we have already inculcated, that human reason is 
 most fallible. In physics we may often infer with 
 certainty the cause from the effect ; but, in ethics 
 and religion, where the morality of an act or the truth 
 of an opinion is in debate, it is absurd to say that, 
 because a fallible creature acts or thinks in this or 
 that manner, he therefore ought to do so. 
 
 But in case our arguments should not satisfy the 
 reader of the insufficiency of external nature, to 
 prove more than the being of a God, and its utter in- 
 capability to meet or to overcome the problem of an 
 eternity ; let him consider the conclusions upon the 
 subject drawn by a justly celebrated divine, and 
 one of the Uving ornaments of the Protestant 
 Church. " We hold," says Dr Chalmers in his ob- 
 
NATURE OF THOUGHT. 227 
 
 servations on the defects and the uses of Natural 
 Theology ; " that the theology of nature sheds pow- 
 erful light on the being of a God ; and that, even 
 from its unaided demonstrations, we can reach a 
 considerable degree of probability, both for his mo- 
 ral and natural attributes. But when it undertakes 
 the question between God and man, this is what 
 it finds to be impracticable. It is here that the 
 main helplessness of nature lies. It is baffled in 
 all its attempts to decipher the state and the pros- 
 pects of man, viewed in the relation of an offending 
 subject to an offended sovereign. In a word, its 
 chief obscurity, and which it is wholly unable to dis- 
 perse, is that which rests on the hopes and the des- 
 tiny of our species. There is in it enough of ma- 
 nifestation to awaken the fears of guilt, but not 
 enough again to appease them. It emits, and au- 
 dibly emits, a note of terror) but in vain do we listen 
 for one authentic word of comfort from any of its 
 oracles. It is able to see the danger, but not the 
 deliverance. It can excite the forebodings of the 
 human spirit, but cannot quell them — know^Dg just 
 enough to stir the perplexity, but not enough to 
 set the perplexity at rest. It can state the diffi- 
 culty, but cannot unriddle the difficulty — having 
 just as much knowledge as to enunciate the pro- 
 blem, but not so much as might lead to the solution 
 of the problem. There must be a measure of light, 
 we do allow ; but, like the lurid gleam of a volcano, 
 it is not a light which guides, but which bewilders 
 and terrifies. It prompts the question, but cannot 
 
■J2S NATURE OF THOUGHT. 
 
 frame or furnisli the reply. Natural theology may 
 see as much as shall draw forth the anxious inter- 
 rogation, ' Wliat shall I do to be saved ?' The 
 answer to this comes from a higher theology." 
 
 So apposite to our purpose are the remarks of 
 Dr Chalmers, which follow the last quoted para- 
 graph, that we must conclude our argument with 
 them. " These," says he, " are the grounds on 
 which we would affirni the insufficiency of that aca- 
 demic theism, which is sometimes set forth in such 
 an aspect of completeness and certainty, as might 
 seem to leave a revelation or a gospel wholly un- 
 called for. Many there are who would gloss over 
 the difficulties of the question ; and who, in the 
 midst of all that undoubted outrage which has been 
 inflicted by sinful creatures on the truth, and the 
 holiness, and the justice of God, would, by merging 
 all the attributes of the Divinity into a placid and 
 undistinguishing tenderness, still keep their resolute 
 hold of heaven, as at least the splendid imagination 
 by which to irradiate the destinies of our species. 
 It is thus that an airy unsupported romance has been 
 held forth as the vehicle, on which to embark all 
 the hopes and the hazards of eternity. We would 
 not disguise the meagreness of such a system. We 
 would not deliver the lessons of natural theology, 
 without telling at the same time its limits. We 
 abjure the cruelty of that sentimentalism, which, to 
 liush the alarms of guilty men, would rob the Deity 
 of his perfections, and stamp a degi'ading mockery 
 upon his law. When expounding the arguments 
 
NATURE OF THOUGHT. 229 
 
 of natural theology, along with the doctrines which 
 it dimly shadows forth, we must speak of the diffi- 
 culties which itself suggests, but which it cannot 
 dispose of; we must make mention of the obscurities 
 into which it runs, but which it cannot dissipate — 
 of its unresolved doubts — of the mysteries through 
 which it vainly tries to grope its uncertain way — 
 of its weary and fruitless efforts — of its unutterable 
 longings. And should, on the one hand, the specu- 
 lations of human ingenuity, and, on the other, the 
 certainties of a well accredited revelation, come 
 forth to illuminate this scene of darkness — we must 
 not so idolize the light or the sufficiency of nature 
 as to turn from the firmament's meridian blaze, 
 that we might witness and admire the tiny lustre of 
 a glow-worm." 
 
 We have in the foregoing pages endeavoured to 
 shew that neither the phenomena of mind, nor the 
 attributes, nor the works of God, are sufficient to 
 prove the immateriality of the mind ; and still less 
 the immortality of the soul. Either for the mate- 
 riality or the immateriality of mind, there is no 
 Scripture authority ; and as for supposing that a 
 belief in its immateriality is necessary to salvation, 
 there seems not the slightest ground for doing so ; 
 with this view it is altogether unimportant to the 
 conclusion whether we believe that the whole ani- 
 mal kingdom is actuated in its operations by a spi- 
 ritual principle which perishes with the body in all 
 but man, or that material organs are alone concerned 
 in the production of the mental phenomena. Bu 
 
230 NATURE OF THOUGHT. 
 
 with regard to the immortahty of the s«ul the case 
 is very different. True, external nature affords no 
 j)roof for it ; but then the Christian founds his 
 faith upon Revelation, which distinctly tells him, 
 that the soul is immortal ; and explains the dark- 
 ness of the mystery with which he is surrounded. 
 It declares that the present world is not the ulti- 
 mate destiny of man — that he is here in a state of 
 preparation for immortality, and that, if he is not 
 wanting to himself, he will rise more vigorous and 
 lovely from his fall, assuming a new character, and 
 taking a higher station in the state of existence ; 
 it exhibits the Almighty to us in the character of 
 a father chastising his undutiful children for their 
 profit, bringing good out of apparent evil, employ- 
 ing sin and death as the handmaids of holiness and 
 immortality, making pain, disappointment, and grief, 
 the harbingers of eternal joy, and converting the 
 curse which blighted the earth into a blessing. 
 
 In comparing the phenomena of Mind as it ap- 
 pears in man and in other animals, we cannot but 
 be struck that the former is alone able to rise to the 
 contemplation of the great First Cause, and alone 
 possesses faculties to conceive a future state of ex- 
 istence ; and w^e cannot avoid feeling that it is our 
 exclusive privilege, endowed as we are by the free 
 gift of our Creator with an imperishable soul, to 
 look forward through the vistas of time to the en- 
 joyment of that life and immortality brought to 
 light through the Gospel. 
 
( 231 ) 
 
 CHAPTER X. 
 
 OPINIONS OF METAPHYSICIANS AS TO THE NATURE 
 OF THOUGHT. 
 
 We have above insisted on the necessity, on the 
 one hand, of a certain susceptibiUty, and, on the 
 other, of the stimulus of sensation, to the manifesta- 
 tion of thought ; but this necessity was not always 
 admitted. Before the time of Aristotle, thought 
 was commonly spoken of as a distinct attribute of 
 one particular part of the body, as life was of the 
 body in general, and presumed to be from the first 
 inherent in this part, and quite independent of any 
 impression from without; while after his time it 
 came to be more generally believed that thought is 
 merely a modification of these foreign impressions, 
 and that distinct from those it is nothing. Each 
 opinion has in modern times also had its advo- 
 cates, who imagine that in their tenets they are di- 
 rectly opposed to each other, as both are to the 
 supporters of the doctrine above adopted : we shall 
 perhaps find nevertheless, that, however they may 
 differ in words, they agree in fact, not only with 
 each other, but with those also who support the 
 view of the subject which we are desirous of in- 
 culcating. 
 
232 OPINIONS or metaphysicians as to 
 
 According to Plato, then, the commonly reputed 
 father of the " Innate Idea" School, there are in 
 the mind, from the beginning, certain immaterial 
 beings, abstract forms and essences, eternal designs 
 and models, types, architypes, and prototypes, of 
 which material beings are only, as it were, the co- 
 pies, and by which the mind ascertains the nature 
 of these beings, and not by the properties of the 
 beings themselves, which have in them nothing 
 fixed or permanent. These immaterial beings may, 
 in his opinion, remain latent till called forth by the 
 perception of something material; but, when so 
 called forth, it is only in the manner of a reminis- 
 cence, the senses being useful merely as joggers of 
 the memory, and not as sources of original infor- 
 mation. The same opinion is embraced by Des- 
 cartes, with this modification, that he regards the 
 immaterial beings, &c. of Plato, not as distinct 
 beings, but as a part of the mind itself, and he was 
 the first to apply to them the term ideas. , Accord- 
 ing to Malebranche, however, nobody can doubt 
 that ideas are really distinct beings, since they have, 
 he says, real properties ; and, with respect to their 
 being innate in the mind, he observes, " it is abso- 
 lutely necessary that God had from the first, before 
 material beings existed, ideas of all which he was 
 about to create, otherwise he could not have crea- 
 ted them, and it is equally certain that God is inti- 
 mately connected with the soul of man. Now, as 
 by means of the soul we can see God, who repre- 
 sents all created things, it follows that the soul has 
 
THE NATURE OF THOUGHT. 233 
 
 innate ideas of every thing which is in existence." 
 Similar notions are promulgated, with certain modi- 
 fications, by Bossuet, Fenelon, Leibnitz, and others. 
 It was the last-mentioned philosopher who added to 
 the celebrated axiom of Aristotle, of which we are 
 presently to speak, Nihil est in intellectu quod non 
 fuit prius in sensu, the words nisi ipse intellectus ; 
 which intellectus he believes to comprise some fun- 
 damental ideas, not all at once to be developed, but 
 only as occasion draws them forth. From the va- 
 garies of these, and other similar authors. Idealism, 
 in all its purity, took its rise. With them the senses 
 are of little use : they perceive material beings, not 
 such as they are in virtue, as well of their own na- 
 ture, as of the mind which takes cognizance of 
 them, but such as they are in virtue of the innate 
 notions of them in the mind alone ; and many of 
 them have accordingly considered every thing in 
 the material world as a mere illusion, like the day- 
 dream of a maniac, and have doubted of every thing 
 — even of their own existence. 
 
 A diametrically opposite doctrine to this origi- 
 nated, as we have just observed, with Aristotle, and 
 has been supported in modern times principally by 
 Bacon, Locked Condillac, and Buffon. With these 
 philosophers, it is a fundamental principle that the 
 mind is at birth a perfect carte -blanche, and that 
 it acquires all its ideas and principles by experience 
 alone, the senses being the only inlets to every spe- 
 cies of knowledge. Hence arose the axiom just al- 
 luded to — Nihil est in intellectu quod non fuit prius 
 
2:U Ol'lNIONS OF METAPHYSICIANS AS TO 
 
 in sensu ; and from their having thus, as it were, 
 identified intellect and sensation, it became incum- 
 bent on them to prove that man, as he surpasses all 
 other animals in the former, in the same degree 
 excels them likewise in the latter. But the only 
 sense in which man is decidedly superior to all 
 brutes, is that of touch ; and, as the chief organ of 
 this sense is the hand, it became established among 
 them, that all animals were intelligent in proportion 
 to the perfection of this organ ; the hawk and par- 
 rot, for example, among birds, and among quadru- 
 peds, those furnished with clavicles, owing their 
 superiority in this respect to the circumstance of 
 their using their hands as organs of prehension, 
 and that man owed all his perfection to the exqui- 
 site structure of his hand; — nay, Helvetius has 
 even gone so far as to say, that, had a horse pos- 
 sessed the hand of a man, he would have been 
 equally intelligent ! In this way the mutual agen- 
 cy of the percipient being and of the impression to 
 be perceived, has been neglected by both Idealists 
 and Realists ; and if the former made too little of 
 the senses, regarding them as nothing, or worse 
 than nothing, since they frequently only deceived 
 us, the latter, in an equal degree, made too little of 
 the mind, which they looked upon as a kind of soft 
 wax or clay, capable of receiving impressions con- 
 veyed to it by the senses, but incapable of adding 
 any thing to them in the way of either embellish- 
 ment or deterioration. 
 
 B\it to descend a little to particulars. With re- 
 
THE NATURE OF THOUGHT. 235 
 
 spect to the abstract forms and essences of mate- 
 rial beings, supposed by Plato and Descartes to be 
 inherent in the mind, either as distinct immaterial 
 beings, or as integrant parts of the said mind, it is 
 sufficient to say that the supposition is entirely gra- 
 tuitous and unnecessary, and, what is worse, en- 
 tirely unintelligible. It was well remarked by Dio- 
 genes, in conversation with the former on the sub- 
 ject, that, although he perceived the table and the 
 goblet which were before them, he had no abstract 
 notions of table-ity and goblet-ity, — ^he saw and 
 understood the things themselves, but he had no 
 conception of their types, architypes, and proto- 
 types. The alleged proof, adduced by Malebranche, 
 that ideas are not only innate, but substantial — 
 namely, their possessmg distinct properties — is quite 
 inadmissible. Ideas have no properties, — they are 
 nothing but a mode of existence of the thinking 
 organ, acted upon by its proper stimulus ; and are 
 no more entitled to be considered substantial, than 
 combustion or motion, which are, in like manner, 
 modes of existence of the thing burning and the 
 thing moving. The testimony also brought for- 
 ward by the same author, of the innateness of these 
 substantial ideas, founded on the intercourse of our 
 souls with God — whose mind necessarily from the 
 first embraced every thing — is that of a theologian, 
 not of a physiologist ; and presumes upon the no- 
 tion, which we have already endeavoured to shew 
 is false, that the mind and the soul are identical. 
 It might likewise be further objected to this al- 
 
230 OPINIONS OF METAPHYSICIANS AS TO 
 
 ieged evidence in favour of the innateness of our 
 ideas, that our notions are as often false as true, 
 unjust as just, whicli they could not have been, had 
 they come to us directly through the medium which 
 has been supposed ; and this objection is particu- 
 larly applicable to the ultra-Malebranchism of Fe- 
 nelon, who represents our innate ideas as not only 
 derived immediately from God, but identical with 
 God, — " elles sont," he says, " Dieu meme !" But 
 it is in vain to follow the vague flights of divines 
 on any subject of physiology : suffice it to say, that 
 the illusory world of the idealist has no existence, 
 and can have no existence, in nature. No func- 
 tion — and thought is a function — can exist w ithout 
 two conditions, a susceptibility of being acted on, 
 and a power acting : the idealist makes but one, — 
 not either of them individually, but both of them, 
 as it were, united into one, or rather a new entity 
 standing in the place of both, but not identical with 
 either. It is quite true that we can have no ideas 
 of external objects, considered per se, and that we 
 cannot know any thing of them otherwise than as 
 they affect our minds, — and therefore our notions 
 of them must be derived, as well from the quality 
 of our minds, as from the nature of the objects in 
 question. The properties of colour, for example, 
 of hardness, and so forth, have as close a reference 
 to the thing perceiving, as to the thing perceived, 
 what is one colour, or one degree of consistence, to 
 one animal, being not necessarily of the same to 
 others ; and there is no such thing as colour, no 
 
THE NATURE OF THOUGHT. 237 
 
 such thing as hardness at all, but where there is a 
 being conscious of these properties. But it is not 
 true that this being has, or can have, any idea of 
 colour or hardness, independently of such bodies as 
 are calculated to excite it, nor, consequently, that 
 the senses are otherwise than essential to our hav- 
 ing any ideas at all. The wildest maniac derived 
 all his ideas originally from his senses, — his hallu- 
 cinations arise from perturbed combinations of them. 
 But the senses are not, nevertheless — as supposed 
 by the Peripatetic School — all-in-all sufficient, the 
 mind being a yielding mass, capable of receiving 
 impressions from the senses, but not of contributing 
 any thing to them. If this were the case, whence 
 all the differences in the disposition, attainments, 
 and character of different individuals under precise- 
 ly similar circumstances ? It is well remarked by 
 Dr Barclay, that we may as well say that arts and 
 manufactures are derived from the doors and win- 
 dows of the work-shops by which the raw materials 
 enter, as that thought is derived from the senses 
 alone. There must be something within to act on 
 these raw materials, and to construct out of them 
 new fabrics, which are consequently the result of 
 the combined operation of the thing acting and 
 the thing acted on. Two conditions, we have re- 
 peatedly said, are essential to every function ; and 
 the Peripatetics, like the Academics, make but 
 one, — a different one, indeed, but still only one. 
 Our idea of colour or of hardness, results, not from 
 the object alone, any more than from the mind 
 
'238 Ol'lNIONS OF METAPHYSICIANS AS TO 
 
 alone, but iroiii the mutual agency of both ; and 
 any change in the constitution of either, effects a 
 corresponding change in the idea in question. 
 
 So far, then, as words go, both the Idealist and 
 Realist are equally mistaken ; but it is amusing to 
 observe that they are so in words alone, and that, 
 in fact, they not only are both of them correct, but 
 agree as well with each other, as with the advocates 
 of the doctrines which we have above adopted. For 
 what in reality are the abstract forms and essences 
 of the former, and the carte blanche of the latter, 
 but a susceptibility, resident from the beginning in 
 the body, of being affected in a certain way ; what 
 is the information represented by the one school 
 as merely revived, and by the other as originally 
 communicated by the senses, but the stimulus to 
 such an affection ; and what, lastly, is an individual 
 idea of either party but the result of the two mu- 
 tually acting on each other ? The chief difference 
 is, that the Idealists have exaggerated the influence 
 of the Percipient, the Realists, that of the thing 
 perceived. Thus, among the former, Descartes 
 distinctly defines an innate idea to be a Faculty 
 of engendering ideas — not an idea, in the common 
 and correct acceptation of the word ; and Fenelon 
 speaks of it as " une regie par laquelle on juge de 
 toute" — not a judgment, but a capacity for judging. 
 In like manner among the latter, Locke describes 
 his carte blanche as 2i Disposition — a faculty to re- 
 ceive impressions, and distinctly states that it is 
 from this capacity to receive these impressions, 
 
THE NATURE OF THOUGHT. 239 
 
 as well as from the impressions themselves, that an 
 idea arises. What is all this in the hands of either, 
 but the view all along taken above ? Both virtu- 
 ally admit the two conditions required, but each 
 formally admits only one ; both go hand in hand 
 with Truth without perceiving her. But it is to 
 Bonnet and Kant that we owe the fullest illustra- 
 tion of the real nature of thought. " Our brain," 
 observes Bonnet, " is organized with direct refer- 
 ence to the wonderful operations of our mind ; and 
 the organs of our senses are, in Hke manner, 
 adapted to the organization of our brain ; but 
 the latter are, in every thing, subservient to the 
 former. And so it is with all the lower animals. 
 The brain of man and the hand of man, the brain 
 of the horse and the hoof of the horse, have a di- 
 rect relation to each other ; but the horse would 
 be no more raised to the intellectual rank of a man 
 by giving him a hand, than a man sunk to the con- 
 dition of a horse by depriving him of it." The 
 Philosophy of Kant is, in like manner, the mean 
 of that of Plato and Aristotle, of Descartes and 
 Locke ; that is to say, he has the same general ideas 
 as they had — for we have just endeavoured to prove 
 that they do not essentially differ from each other 
 — but without falling into their exaggerations on 
 one side or the other. " The faculties of the 
 mind," says he, " are a priori, but it is external oc- 
 casions which determine their exercise : Thought 
 is the form of being derived fi'om both." It is true 
 the continuance of thought, when every avenue of 
 
240 OPINIONS AS TO THE 
 
 sensation is apparently closed, is, at first view, cer- 
 tainly against this doctrine. But the avenues of 
 sensation from the internal organs are never closed ; 
 and even though they were so, thought might con- 
 tinue for some time, without prejudice to the the- 
 ory in question. Neither imitation nor sensation 
 instantaneously ceases, on the abstraction of the 
 powers by wliich they are severally excited, and the 
 longer continuance of thought, once excited by the 
 sensations, implies a difference in degree only — 
 not in kind ; nor can we with greater reason deny 
 that thought was excited by sensations, because 
 these are now quiescent, than that the motion of a 
 tennis-ball was occasioned by the racket which 
 struck it, because that racket is now at rest. In 
 the most excursive reverie thought never wan- 
 ders into a field which has not been, at one time 
 or other, traversed by the senses ; we may think of 
 sirens, and mermaids, and golden mountains, which 
 we have never seen, but we have seen the elements 
 of them all, or we could never have fancied them. 
 
 A chapter devoted to the opinions of philosophers 
 as to the nature of thought, would be incomplete 
 without some notice of the modern doctrine of 
 Phrenology. And such a notice becomes the more 
 necessary, as that doctrine has this much in com- 
 mon with the view inculcated throughout this treat- 
 ise, namely, that the manifestations of mind in the 
 animal kingdom are proportioned to the develop- 
 ment of its physical organ. The leading principle 
 
NATURE OF THOUGHT PHRENOLOGY. 241 
 
 of phrenology, then, is common to it and to the 
 soundest modern physiology ; namely, that the brain 
 is the organ of the mind, or, more generally, that all 
 the phenomena in the animal kingdom that can be 
 termed mental, are manifested through the nervous 
 centre. On this point there is no room for contro- 
 versy, and those who have denied or disputed it, have 
 only shewn how ill prepared they are with the infor- 
 mation requisite for the proper investigation of the 
 functions of the mind. The second great principle 
 of phrenology, when expressed at least in the most 
 general terms, is also an acknowledged truth of 
 physiology, namely, that the nervous system, in the 
 performance of its functions, does not act as one 
 organ, but that separate parts of that system have 
 separate endowments of action, or that it is an ag- 
 gregate of organs, each possessed of a distinct func- 
 tion or functions. This, as we have seen above, is 
 one of the most important discoveries in modern 
 physiology ; and it cannot be denied that the phre- 
 nological anatomists have contributed, in no ordi- 
 nary degree, to the establishment and extension of 
 it as a law pervading the operations of the nervous 
 system. But it must be remarked that the part of this 
 principle, which specifically applies to phrenology, 
 is not included in, or deducible fi'om, the physiolo- 
 gical truth. Physiology has not yet pushed the di- 
 vision of the offices of the nervous organs into so 
 many compartments as the wants of phrenology re- 
 quire. Physiology teaches, not with dogmatic con- 
 fidence, but on rational grounds of belief, that the 
 Q 
 
'242 OPINIONS AS TO THE 
 
 anterior pillars of tlie cercbro-spinal axis are the 
 sole originators of motion, and the nerves derived 
 from them the only nerves by which the motive 
 power is transmitted to distant organs, — that the 
 posterior pillars of the same axis are the only seat 
 of sensation, and the nerves arising from them, or 
 perhaps ending in them, the only channels by which 
 impressions made on remote parts affect sensation, 
 — that the cerebellum is the organ of memory for 
 the muscular sensations connected with the exer- 
 cise of the voluntary motions of the body, and that 
 the brain itself is the sole seat of intellect, volition, 
 emotion, and passion. Physiology, then, does not 
 here countenance phrenology further than by ad- 
 mitting the truth of subdivision of function with 
 subdivision of parts ; while phrenology carries the 
 subdivision of function to an extreme degree with a 
 con-esponding assumption of the subdivision of the 
 encephalon into as many distinct parts or organs. 
 The difference in the modes of investigation pur- 
 sued respectively in these two branches of know- 
 ledge, and the distinction in the evidence on which 
 the conclusions in each rest, may be stated in a very 
 few words. The conclusions of physiology are 
 founded solely on the anatomical scrutiny of the 
 nervous organs, and on the results of experiments 
 made by cutting or removing certain parts in living 
 animals ; and no special function has been assigned 
 to a part unless it possesses distinct boundaries dis- 
 coverable by inspection, or rendered sensible by 
 anatomical manipulation. 
 
NATURE OF THOUGHT PHRENOLOGY. 243 
 
 The phrenologist looks to evidence of a very op- 
 posite kind ; he regards the surface of the brain in 
 contact with the skull as developed in the ratio in 
 which the aggregate of the organs conceived to 
 make up the encephalon is developed, and deter- 
 mines the place of each organ, when, on examining 
 the external surface of the head in the living body, 
 he discovers, or thinks he discovers, an unusual 
 extension of the skull peculiar to those individuals 
 who are observed to excel their fellow-men in the 
 exercise of some particular mental faculty. That 
 the external surface of the skull very exactly cor- 
 responds with the surface of the encephalon, must 
 be admitted by the candid anatomist ; the figure 
 of the skull is unquestionably determined by the 
 development of the contained parts, nor can the 
 slight deviations of the internal table from paral- 
 lelism with the external, or the frontal sinus be 
 any longer brought forward as objections of any 
 considerable weight against the mode of investiga- 
 tion pursued by phrenologists. Neither can any 
 logical objection be brought to bear against the 
 plan on which the phrenologist proceeds in deter- 
 mining the seat of the organ. If every individual, 
 who exhibits a peculiarity of mental operation, be 
 without exception possessed of a peculiarity in the 
 development of his skull, that is, if none but those 
 who shew the mental peculiarity are distinguished 
 by the physical development, the connexion be- 
 tween them as effect and cause is undeniable on 
 any principle of sound reasoning. The only point 
 
'24\ OPINIONS AS TO THE 
 
 tor inquiry here relates to the accuracy of the ob- 
 servation — of wliich we shall speak liereafter more 
 conveniently when some other preliminary points 
 have been adverted to. 
 
 Does physiology, then, afford any countenance 
 to the supposition that the nervous organs cor- 
 respond to such faculties as that which exa- 
 mines individual objects in detail, that which in- 
 vestigates forms, that which dwells upon colours, 
 that which estimates size, that which calculates 
 resistance, that which remembers localities, that 
 which reckons numbers, that which determines 
 to order, that which directs to the observation 
 of events or actions, that which affords a nice 
 perception of time, that which appreciates tune,, 
 that which gives d. facility of acquiring language, 
 that which compares the several conditions of ob- 
 jects, or that which impels to the penetration of 
 causes : or again, to such as that which begets be- 
 nevolence, or veneration, or firmness, or conscien- 
 tiousness, or hope, or wonder, or ideality, or wit, or 
 imitation, or self-esteem, or love of approbation, or 
 cautiousness : or finally, to such as that which draws 
 to amativeness, or the love of offspring, or creates 
 concentrativeness, or produces fiiendship, or leads 
 to brawling, or to murder, or to gluttony, or to the 
 love of life, or to preserve secresy, or originates 
 skill in mechanics ? In answer to this question, it 
 is in the first place to be remarked, that the con- 
 volutions of the brain which are in contact with 
 the internal surface of the skull, attain their great- 
 
NATURE OF THOUGHT PHRENOLOGY. 245 
 
 «st development in the higher animals, and that 
 they are more particularly perfect in man. Yet in 
 their very nature they seem to be but an appen- 
 dage to the essential or central part of the organ, 
 and are altogether deficient in some animals, as in 
 birds, which possess many faculties, as the above 
 list shews, in common with man himself. It 
 must be conceded, however, to the phrenologist, 
 that nothing in the range of physiological know- 
 ledge, proves that the supposed organs may not 
 extend from the surface of the encephalon to the 
 medulla oblongata, or at least to the upper ex- 
 tremity of the crura cerebri, — so as to constitute a 
 series of medullary cones having their bases on the 
 surface in correspondence with the portions of the 
 skull mapped out as the seats of the faculties. On 
 this supposition, the mass of each cone will be great 
 in proportion to the prominence and extent of its 
 base, as indicated by the portion of the skull de- 
 clared to correspond to it. Physiology, then, at 
 present, it must be confessed, leaves the whole of 
 the cerebrum to the phrenologist for the construc- 
 tion of such conical organs, since it appropriates to 
 that part of the encephalon no function but such as 
 the faculties enumerated by him affords a substi- 
 tute for, — or in the faculties above mentioned, in- 
 tellect, volition, emotion, and passion, are sufficient- 
 ly provided for. The case, however, is different as 
 respects the cerebellum. The place which the 
 phrenologist assigns to amativeness, evidently cor- 
 responds to the seat of that part of the encephalon. 
 
216 OPINIONS AS TO THE 
 
 uliilc tlic physiologist has appropriated it to the 
 memory of the muscular sensations by which volun- 
 tary motion is regulated, so that the phrenologist 
 must come prepared to dispute with him the pos- 
 session of this important point of attack. To enter 
 upon the discussion of such details as this would 
 lead to, forms no part of the plan of our present 
 general outline of the subject. 
 
 To proceed, then, with the further consideration 
 of the grounds of phrenology, we come next to in- 
 quire how far absolute volume can be regarded as^ 
 determining activity of function. As respects dif- 
 ferent individuals of the human race, physiology 
 does not afford the means of answering this ques- 
 tion. That science has hitherto confined itself 
 to comparing the development of the nervous sys- 
 tem and state of the functions in one species of 
 the animal kingdom, with its development and 
 the state of its functions in other species higher 
 or lower in the scale, so that it furnishes no cri- 
 terion by which to judge of the relative states of 
 development in different individuals of the same 
 species, according to the degree in which the fa- 
 culties belonging to that species are manifested^ 
 As the phrenologist then here far outruns the pre- 
 sent conclusions of physiology, as to the exact con- 
 nection of mere size of the organ with development 
 of its function in animals of the same species, no- 
 thing is left in our choice but to try his postulates 
 by general principles. His postulates on this head 
 are chiefly two, namely, that the mere bulk of an 
 
NATURE OF THOUGHT — PHRENOLOGY. 247 
 
 organ is not decisive of the activity of its func- 
 tion, without a comparison of the proportion which 
 it bears to the other organs in the head of the same 
 individual ; and again, that besides bulk and pro- 
 portion, something may be due to greater vital 
 energy in the part. It was observed above, in 
 speaking of the development of the nervous organs 
 in man, as compared with their development in in- 
 ferior animals, that the mere volume of the aggre- 
 gate of several organs may be dependent on a 
 variety of causes operating differently under slight 
 differences of circumstances ; but that proportionate 
 volume of parts must be regarded as an unfailing 
 evidence of their relative importance in the animal 
 economy. As this was said in speaking of the 
 comparison of parts in animals of different species, 
 it is not altogether an admission of the first of the 
 above postulates, yet it seems but fair to confess 
 that the phrenologist is entitled to seek our assent 
 on account of the strict analogy existing between 
 the two cases. There appears, then, to be no rea- 
 sonable ground for refusing to admit that the ag- 
 gregate of certain organs may be smaller in one 
 brain than in another, and yet that their functions 
 may be more active, because their development 
 bears a greater.Vatio to the entire mass, or, accord- 
 ing to the phrenological estimate, to the entire sur- 
 face of the skull. With respect to the second 
 postulate above stated, it is not to be denied but 
 that in different temperaments different degrees of 
 vital activity belong to the living solids ; nor can 
 
248 OPINIONS AS TO THE 
 
 the nervous substance be made an exception to 
 this general rule, so that the second postulate may 
 be also conceded to the phrenologists. But while 
 it is conceded, it does not clearly appear that they 
 can make any advantageous use of it in the explana- 
 tion of mental phenomena, at least when the pre- 
 ceding postulate is before acknowledged. For the 
 greater vital activity which difference of tempera- 
 ment bestows must be shared by the whole brain 
 indiscriminately, so were this common influence 
 withdrawn, the relative activity of all the organs 
 would continue the same as before. The phreno- 
 logist, besides, calls on us to concede that the habi- 
 tual exercise of a faculty increases its activity, and 
 is even followed by an augmentation of the organ. 
 Visible augmentation of the organ cannot be estab- 
 lished satisfactorily; but physiology admits that 
 organs so exercised in parents are prone to greater 
 physical development in the offspring, or at least 
 that such effects become manifest after two or three 
 generations. 
 
 Our next attention is called to a very important 
 principle which is assumed in phrenology — namely, 
 that differences in individual character are essen- 
 tially dependent on original differences of organic 
 structure, while doubtless some small influence is 
 conceded to the power of the circumstances under 
 which each individual has lived before his faculties 
 reach maturity. We have now to inquire, how far 
 physiology bears out phrenology in this assump- 
 tion. The opinion often inculcated by mere men 
 
NATURE OF THOUGHT PHRENOLOGY. 249 
 
 of letters, and sometimes by metaphysicians, that 
 all men are born with equal faculties and suscepti- 
 bilities, and that the differences actually observed 
 among individuals are due to the differences in 
 the circumstances to which each has been exposed, 
 not only receives no countenance from physiology, 
 but, on the sound principles of that science, must 
 be condemned as altogether untenable. The brain 
 is, in the strictest sense, the organ of the mind, 
 and there is no reason to doubt, what the best au- 
 thorities in physiology have commonly assumed, 
 that every individual's present condition as to his 
 sentient, intellectual, and moral nature, is what the 
 actual condition of the nervous organ makes him. 
 The evidence of this is, that it is the only suppo- 
 sition which agrees with the phenomena both of 
 health and disease. Further, it is usually assumed, 
 and on the justest grounds, that every mental ope- 
 ration must be attended with some physical change 
 in the nervous organ ; so that, while it is impos- 
 sible to doubt but that the after development of 
 the brain in the course of life is mainly determined 
 by its actual condition at the time of birth, there 
 is room for the supposition, that some considerable 
 influence is exerted upon that development by the 
 particular nature of the mental operations, to the 
 reaction of which it has been subjected by the train 
 of external circumstances distinguishing each indi- 
 vidual's early years. Physiology does not at pre- 
 sent enable us to estimate the exact extent to 
 which this influence of the mental operations reacts 
 
250 OPINIONS AS TO THE 
 
 upon the development ; but there is no ground for 
 believing that the change upon the original suscep- 
 tibilities is beyond a moderate alteration. Such an 
 alteration must doubtless be attended with a change 
 in the relative development of the nervous parts : 
 yet even the most finished education appears to be 
 incapable of making such a change on the internal 
 parts as can become conspicuous externally. The 
 children of peasants and labourers, though highly 
 educated, and transferred from their earliest years 
 to the society of the more intelligent orders, retain 
 throughout life the form of head belonging to their 
 original rank, while their offspring, in the course of 
 two or three generations, seem to acquire gradual- 
 ly that form of head which belongs to those orders 
 of society among whom the mental faculties are 
 exercised to a greater degree. In as far, then, as 
 the evidence of the change of form under the in- 
 fluence of external circumstances is an evidence of 
 the alteration of susceptibility of mental operations, 
 and it is sound physiological evidence, we must 
 conclude that it is very gradual and within very 
 narrow limits. The reader must see, I think, that 
 a distinction is made in the above observations be- 
 tween the effect of education as storing the mind 
 with knowledge, to use the popular language, and 
 its effect as augmenting the original susceptibilities 
 of the individual for mental operations. If the 
 brain be, as strictly as we have represented it, the 
 organ of mental function, it is impossible that its 
 susceptibility of mental operations can be improved 
 
NATURE OF THOUGHT PHRENOLOGY. 251 
 
 by any cause without a change in its physical de- 
 velopment; but there is no ground for believing that 
 the mere acquisition of knowledge is necessarily at- 
 tended with any such alteration of development. 
 
 It is often argued that no two individuals are 
 exposed to exactly the same external circumstances, 
 even though brought up together and treated as 
 carefully as possible on the same plan ; and there- 
 fore, that we are not at liberty to infer, that diffe- 
 rence of circumstances may not have given rise 
 to all the differences in mental and moral cha- 
 racter that may be observed to distinguish them. 
 The ready reply to this argument is, that there is 
 no evidence of the mental phenomena produced by 
 external causes reacting with such efficacy on the 
 organ as to account for the differences actually 
 observed. And if diversity of character, such as is 
 often observed in two individuals brought up as 
 much as possible alike, could be explained by such 
 slight variations in the circumstances as can possi- 
 bly arise in a case of this kind, how immense would 
 be the effect, in producing diversity of charac- 
 ter, of the remote extremes in the circumstances of 
 education and training, such as many individuals to 
 be met with in ordinary society have been subjected 
 to ? How many individuals do we see possessed of 
 much the same moral and mental dispositions, 
 though brought up under the most opposite disci- 
 pline ? The assumption, then, destroys itself, by 
 proving too much. 
 
 It may seem at first sight that the view taken 
 
2.V> 
 
 OPINIONS AS TO THE 
 
 above of the connexion between mental function 
 and physical development is, in effect, an admission 
 of the truth of phrenology. This, however, is far 
 from being the case. It is, however, an admission 
 towards the views of phrenology not made by many 
 of its opponents ; and yet we are mistaken if it be 
 made in any spirit of partiality in favour of its doc- 
 trines, or in any other spirit than that of sound 
 physiological truth. Throughout this treatise it 
 has been, inculcated that in the animal kingdom de- 
 velopment of mental phenomena goes on progres- 
 sively increasing with the expansion of the cerebral 
 organs, and when we arrive at man, and come to 
 compare the separate manifestations of the same 
 phenomena in different individuals, analogy forces 
 us to confess, in the absence of direct evidence, a 
 persuasion amounting almost to a conviction, that 
 the physical development of the brain must cor- 
 respond in each individual with the activity of the 
 mental phenomena. Phrenology can claim us as 
 converts or disciples on no other ground than that 
 many of its opponents deny what we admit, or 
 rather what we inculcate. But what we here 
 maintain is not phrenology, but physiology ; it rests 
 not on phrenological but on physiological observa- 
 tion. To this difference Hufeland referred when 
 he said, " organology is unquestionably true, but 
 organoscopy is doubtful." 
 
 Having pointed out, then, the very considerable 
 extent to which physiology supports phrenology, it is 
 time to direct the attention of our readers to thediffe- 
 
NATURE OF THOUGHT PHRENOLOGY. 253 
 
 rences which still exist between them. The grand 
 point of opposition between them is that to which the 
 quotation from Hufeland refers, namely, that physio- 
 logy has hitherto acknowledged no method of subdi- 
 viding the brain or the general seat of intellect, voh- 
 tion, emotion, and passion, into separate parts, or of 
 attaching a special function to any particular por- 
 tion of that organ. The division, then, of the en- 
 cephalon into thirty -five organs,* corresponding to 
 as many faculties or propensities, sentiments, know- 
 ing and reflective faculties, rests altogether on the 
 evidence peculiar to phrenolog^^, and derives no 
 immediate countenance from physiology. 
 
 In remarking, then, on the degree of credit to be 
 attached to the particular evidence on which phre- 
 nologists rest their doctrines, it will form no part of 
 our purpose to seek out the more vulnerable points 
 for attack, or, as has been too often practised by its 
 opponents, to seize on such parts of the doctrine as 
 may be made to appear in a ridiculous light to su- 
 perficial reasoners. A fair and candid view of the 
 subject is what we desire to present to our readers ; 
 a view at once guarded from the spirit of determined 
 hostility, and fi'om that of blind partizanship. No 
 subject in the whole range of human knowledge 
 more loudly calls for an impartial investigation ; 
 for if no branch of inquiry has been more misrepre- 
 sented, ridiculed, and calumniated by enemies, few 
 have suffered more injury from the weak homage 
 and adulation of partizans. By crowds of the lat- 
 • See Combe's <' System of Phrenology." Edin. 1836. 
 
254 OPINIONS A^; TO THE 
 
 terthe science lias been regarded as a sort of pleas- 
 ant legerdemain, a kind of intellectual palmistry 
 by which to practise on the credulity of their ac- 
 quaintance, while the fictions or exaggerations, 
 which they have employed to raise wonder, have 
 been received by the literary expounders of the 
 doctrine as facts, and gravely uttered to the world 
 as proofs of the truth of the doctrine. Others have 
 been permitted to bring forward, in recognised pub- 
 lications of the phrenological school, crude specula- 
 tions and reasonings, in behalf of the doctrine, such 
 as would hardly impose on an unbiassed school-boy. 
 If the established schools of philosophy still refuse 
 to recognise the claims of phrenology to the rank 
 of a science, they have at least this excuse, that if 
 its partizans are not the supporters of a pseudo- 
 science, they are very certainly chargeable with 
 much pseudo-reasoning. The abettors of phreno- 
 logy have undertaken to convince the world of a 
 most important fact ; a fact of the highest interest 
 to the happiness of mankind, namely, that the in- 
 tellectual and moral disposition of every individual 
 is discoverable by the inspection of his skull, and 
 the world is entitled to expect that those who take 
 on themselves the onus of proving a thing so new, 
 and so full of momentous consequences, will set 
 about the task with a gravity becoming the subject, 
 and keep their sober reasonings apart from the idle 
 frivolities of those who have no other object in view 
 than to consume a leisure hour. Whoever has 
 looked into the phrenological periodicals will be at 
 
NATURE OF THOUGHT PHRENOLOGY. 255 
 
 no loss to recognise the justice of this censure. As 
 a specimen of the looseness of reasoning permitted 
 in these acknowledged organs of the school, we will 
 refer to a series of papers in the Phrenological 
 Transactions, which are not the less mischievous in 
 their effects, because they are written with greater 
 ability than belongs to most of the productions to 
 which the above censure applies. One phrenolo- 
 gist chooses characters from Shakspeare, distin- 
 guished by some prominent moral disposition. He 
 frames a fictitious description of a cranial develop- 
 ment corresponding to the character as depicted by 
 the dramatist — this he delivers to another phreno- 
 logist, and calls on him to pronounce upon the dis- 
 positions of the person to whom this development 
 belongs, as if it were drawn from the head of an 
 acquaintance; the latter accordingly draws up a cha- 
 racter which does bear a certain resemblance to that 
 of lago, or whoever else was chosen from among the 
 dramatis personae of Shakspeare. The first phreno- 
 logist holds up his hands in wonder — a second 
 Daniel is come to judgment ! This is an experi- 
 mentum crucis in evidence of the truth of phreno- 
 logy ; and the public are straightway called in to 
 witness the same irrefragable demonstration of the 
 infallibility of the phrenological faith. The con- 
 clusion is worthy of a Professor of Palmistry. There 
 is no need to turn to the idola of Bacon, or yet to 
 the " Barbara celarenf,'' to detect the fallacy here ; 
 it stares us in the face. Where did the first phre- 
 
256 OPINIONS AS TO THE 
 
 nologist find tlie materials for the development of 
 lago's skull ? Nowhere surely but in the catalogue 
 of the organs ? Where did the second phrenologist 
 find the materials for lago's character — where but 
 in the same catalogue ? In this catalogue the facul- 
 ties are set down opposite to the organs. The 
 thing to be proved is the accuracy of the catalogue. 
 The first phrenologist picks out a few organs, and 
 hands the list of them to the second — he, wonder- 
 ful man that he is, is able to read off from the ca- 
 talogue the corresponding faculties — and this feat 
 is gravely put forward as establishing the con'ect- 
 ness of the catalogue. 
 
 To pass from such shallow sophistry, we have now 
 to consider what weight is due to the inductive evi- 
 dence in favour of phrenology, as laid down by its 
 more authoritative supporters. It was before no- 
 ticed that the first discovery of the organs and fa- 
 culties, and the alleged cumulative evidence in sup- 
 port of the discovery, are drawn fi-om the observa- 
 tion of an unusual extension of the dimensions of 
 the skull, at some definite spot, in those individuals 
 who are distinguished beyond their fellow-men for 
 some particular mental operation. We may add 
 to this, that some assistance in the original determi- 
 nation of the places of the organs, as well as in the 
 after confirmation of the decision, has been drawn 
 fi-om the supposed correspondence in development 
 between the skulls of certain inferior animals, and 
 those parts of the human skull, alleged to be the 
 
NATURE OF THOUGHT PHRENOLOGY. 257 
 
 seats of such faculties or powers as they possess in 
 common with men. 
 
 In reading the history of the first discovery of the 
 organs and faculties by Gall, a sober mind cannot 
 help being forcibly struck with the impression, that 
 here is a man of playful fancy indulging his peculiar 
 bent in the physiognomy of the head on grounds a 
 little more solid, indeed, than those on which men 
 are accustomed to build castles, towers, and cities 
 out of the clouds, or to see familiar scenes in a 
 cheerful fire ; but still that it is fancy with some- 
 thing more of a method in it. 
 
 Whatever may finally turn out to be the opinion 
 of philosophers on this point, it is not to be lost 
 sight of at present, either by phrenologists them- 
 selves, if they wish to take the most effectual steps 
 for the propagation of their tenets, or by their op- 
 ponents, if they are desirous of applying judiciously 
 to the same the tests of philosophic truth, that sys- 
 tems of opinions, as extensive as phrenology em- 
 braces, have been framed, believed, and propagated 
 with as much zeal and success; though in the end 
 it has been discovered that neither the original evi- 
 dence furnished by the inventor, nor the confirma- 
 tory parts, added by the devoted exertions of hun- 
 dreds of disciples, have had any other foundation 
 than the vivid workings of fancy on a small sprink- 
 ling of facts. The inventor of a system is not to 
 be trusted in the exposition of the facts of the case 
 without the most rigid surveillance ; still less is the 
 ardent partizan to be relied on, when he crowds his 
 
 R 
 
258 OPINIONS OF METAPHYSICIANS AS TO THE 
 
 pages with confirmatory evidence. If you refuse 
 botli, it may be asked, who then are we to believe ? 
 That question impHes tliat it is necessary that we 
 should decide, on the instant, whether phrenology 
 be true or unfounded. There is no such necessity 
 in the world of science ; a patience of ignorance 
 being one of the chief elements of the philosophic 
 character ; a determination to abide unweariedly 
 that fulness of time, when truth shall unfold itself. 
 Now, there cannot be conceived a subject in which 
 such patience is more requisite than phrenology. A 
 thousand probable sources of error beset it on every 
 side. It professes to solve a mystery, and offers at 
 once abundant food to our cause-seeking propen- 
 sity, — two properties which the history of mankind 
 teaches us to have belonged pre-eminently to almost 
 all the false views which have made the most rapid 
 progress, and obtained the greatest currency among 
 men. It is a subject of vast extent, too great to be 
 investigated within any moderate limits of time, in- 
 cluding, as it does, all that relates to the sentient, 
 the intellectual, and the moral nature of man, or 
 the entire sciences of metaphysics and morals. Nor 
 does it limit itself, like these sciences, to the mere 
 indication of the general laws under which intel- 
 lectual and moral phenomena take place in the 
 minds of all ; but professes to explain the origin of 
 individual differences of character, both intellectual 
 and moral ; or instead of being studied, like meta- 
 physics, by reflection on the subjects of our own 
 consciousness, it sends us abroad into the world to 
 
NATURE OF THOUGHT PHRENOLOGY. 259 
 
 scrutinize the dispositions of the individuals to be 
 met with in society ; to dive into their secret thoughts ; 
 to grope out the most concealed parts of their cha- 
 racters, and then to compare what we have learned 
 on these points with the contour and configuration 
 of their skulls. If it be easy to measure the di- 
 mensions of the skull, is there no difficulty, no 
 chance of error in estimating men's dispositions and 
 characters ? Or is it not true that there is no case 
 in which so many palpable errors are daily com- 
 mitted by men as in the estimate of the character 
 of their associates and contemporaries ? But if it 
 be difficult to estimate exactly the characters even 
 of those with whom we live in fi-equent intercourse ; 
 is it found more easy for a man to take an unbiassed 
 account of his own character ? Or is it not acknow- 
 ledged on every hand that there is nothing of which 
 men are so grossly ignorant as of the knowledge 
 of self; and yet a great part of the evidence in fa- 
 vour of phrenology, in those cases where the tests 
 are most accurately appHed, depends upon the re- 
 port given by the individual, whose head is subjected 
 to examination, as to his own powers, dispositions, 
 and sentiments. No one who reflects upon the diffi- 
 culty wdll seriously say that a man is a competent 
 witness of the degree in which he possesses those 
 faculties, or that his report can have that justness 
 and exactitude which are required in serious in- 
 quiries to shew, as an evidence of the truth of phre- 
 nology, their correspondence with the development 
 of his head. 
 
•2Gl) OPINIONS OF METAPHYSICIANS AS TO THE 
 
 When, then, we consider the numerous sources 
 of error which cannot but arise from those several 
 causes, we shall be inclined to pause before giving 
 our implicit assent to phrenology, or admitting that 
 its conclusions are the result of a rigid induction 
 from observed facts. These difficulties are inhe- 
 rent in the very nature of the subject, and altoge- 
 ther inseparable from the prosecution of it, so that 
 nothing but length of time can be expected to over- 
 come them. 
 
 But besides those sources of error, which spring 
 from the very nature of the inquiries in which phre- 
 nology embarks, there are others which flow at pre- 
 sent from the novelty of the subject, the hostility 
 which it has provoked, and the spirit of partizanship 
 which has been, in consequence, engendered in its 
 behalf. No system of philosophic opinions was 
 ever matured into truth under such a warfare of 
 attack and defence as phrenology has been hitherto 
 exposed to. The spirit of truth flies from violence^ 
 and is in vain courted to return till the acrimony 
 of abuse and mutual recrimination is laid aside, and 
 the contending parties are content to exchange their 
 tone of defiance for the calm and sober intercourse 
 of philosophic disputation. The debate between 
 the phrenologists and anti-phrenologists has hitherto 
 borne more the aspect of a political contest than 
 that of a rational inquiry into scientific truth. It 
 almost reminds us of the disputes between the Uni-^ 
 versalists and Realists, when kings and armies were 
 ranged on opposite sides of the question, and the 
 
NATURE OF THOUGHT PHRENOLOGY. 261 
 
 penalty of death was sometimes the lot of the van- 
 quished. We have not, indeed, seen bloodshed or 
 the actual warfare of brute force employed in this 
 contest ; but the means employed on either side 
 have been hardly better fitted to further the cause 
 of truth, than the event of a battle-field. Indiscri- 
 minate assemblages of people, and the rhetorical 
 and exaggerated statements which must be addressed 
 to them, or into which they will convert whatever 
 is addressed to them, are much more available for 
 gaining a political object by agitation, than for set- 
 tling the truth of numerous intricate questions de- 
 pending for their solution on a nice observation of 
 facts. When we consider the violence with which 
 phrenology was assailed on its first appearance, 
 we cannot, perhaps, justly blame its supporters for 
 forming themselves, for mutual support, into asso- 
 ciations and societies, and encouraging the public 
 to join them ; yet it surely will not be denied that 
 such societies, however well adapted to serve the 
 spirit of propagandism, must prove fertile nurseries 
 of error in all that concerns the investigation of 
 moral and metaphysical truth. The exaggeration 
 or the suppression of facts and errors of inference 
 to which the human mind, without any imputation 
 on its veracity, becomes so prone under the influ- 
 ence of preconceived opinion, run small risk of 
 being detected and exposed in an assembly composed 
 of men sworn to one faith, combined together for the 
 express purpose of spreading and defending that 
 faith, and taught to regard, not the discovery of 
 
2(i'2 OPINIONS OF METAPHYSICIANS AS TO THE 
 
 triitli, but a triumph over tlicir opponents as the 
 great object of their exertions. In such an assem- 
 bly, to doubt or to liesitate with respect to any one 
 article of that faith which the great apostles of the 
 doctrine inculcate, must be looked upon as a species 
 of infidehty to be shunned as a crime. We have 
 no hesitation, then, in setting down phrenological so- 
 cieties among the causes detrimental to the pro- 
 gress of phrenology, if it be in reality a well founded 
 doctrine. 
 
 We are compelled, then, to distrust the conclu- 
 sions of phrenology, not because there is any thing 
 in the principles on which it is founded at vari- 
 ance with the soundest physiology, or because the 
 mode of investigation, practised by its supporters, 
 is incapable of verification, but because, while the 
 facts on which it is alleged to rest are of a decep- 
 tive nature, and of very difficult determination mth- 
 out the nicest possible observation ; the subject up 
 to the present time has been prosecuted under cir- 
 cumstances extremely unfavourable to the establish-- 
 ment of any description of philosophic truth. 
 
 The questions connected with the function of 
 the brain bearing on this subject, which time alone 
 can decide, and it may be that but a few years will be 
 required for the purpose, may be stated M^ithin a 
 narrow compass. Physiology is most probably al- 
 ready on the point of determining whether one of 
 the leading principles of phrenology be well or ill 
 founded, that is, whether the brain, which it acknow- 
 ledges to be the general seat of intellect, volition. 
 
NATURE OF THOUGHT PHRENOLOGY. 263 
 
 desire, emotion, passion, act as one organ in these 
 several states, or be composed of a plurality of parts, 
 each endowed with a distinct mode of mental action, 
 such as shall exhaust these its more general attri- 
 butes. If we obtain this information from Physio- 
 logy, its effect may either be the confirmation of the 
 present system as founded by Gall in all its essen- 
 tial parts, or, what is by no means unlikely, it may 
 shew a necessity for an entire remodelling of that 
 system. 
 
 While, however, physiology may possess the 
 means of determining this great principle on grounds 
 peculiarly its own, it is by no means proper that 
 the cultivators of that science should refuse to in- 
 vestigate the same point by the kind of evidence 
 which phrenology employs. Men trained in the 
 severe pursuits of physiology are more competent 
 to the task of nice observation of this kind than 
 most of those who have hitherto engaged in it ; and 
 if they begin their observations with a total distrust 
 of all that has hitherto been done, admitting nothing 
 but upon repeated evidence, and guarding carefully 
 against the besetting sin of over-haste to rear a sys- 
 tem, while they keep themselves free from the tram- 
 mels of partizanship and the obligation of allegiance 
 to associations, and bring the fruit of their labours 
 before the established scientific bodies, composed of 
 men free to detect every unguarded assumption, 
 we shall not long remain in doubt whether phreno- 
 logy is to triumph or to be sent to repose with the 
 
2G4 OPINIONS OF METAPHYSICIANS AS TO THE 
 
 countless hypotheses which have, for a short season, 
 amused or perplexed the minds of men. 
 
 One important description of evidence for the 
 confirmation or refutation of the doctrines of phre- 
 nology of w hich its supporters profess to avail them- 
 selves, but of which they have hitherto made very 
 little use is, in particular, open to physiologists, 
 namely, the comparison of the cranial development 
 of the inferior animals with the state of their facul- 
 ties. The use phrenologists have hitherto made of 
 this kind of observation serves rather to make us 
 distrust their conclusions than to confess the accu- 
 racy of them. There is nothing to be found in 
 their writings like a connected series of observations 
 bearing upon the subject ; it would seem, indeed, as 
 if they never resorted to the lower tribes of animals, 
 but to bring some isolated case to back a weak 
 point in their system. Vimont, it is true, has pub- 
 lished a book on Human and Comparative Phre- 
 nology, but the importance of his observations is by 
 no means commensurate with the size and expense 
 of his work. 
 
 These remarks on the doctrines of phrenology 
 we must now bring to a close, as they have been 
 extended to as great a length as their incidental 
 connexion with the subject of this treatise can 
 claim. Nor, indeed, had our space permitted, 
 would it have been of much utility to extend our 
 attention to any detailed examination of the parti- 
 cular evidence on which the establishment of each 
 organ and corresponding faculty is believed to rest. 
 
NATURE OF THOUGHT PHRENOLOGY. 265 
 
 It is impossible to disprove alleged facts, however 
 little foundation they may actually possess. We 
 can but examine the testimony in their favour, and 
 pronounce on general grounds, as has been already 
 done in regard to the whole system collectively, 
 how far it seems entitled to credit. 
 
 Whatever is to be the fate of phrenology, we 
 cannot but anticipate that a new period in its his- 
 tory is about to open ; that is, that it will in future 
 be treated as a rational hypothesis, the grounds of 
 which deserve to be examined with a calm and de- 
 liberate attention. Without such a calm and de- 
 liberate attention, the difficulties which we have 
 shewn to beset the subject so thickly from its own 
 inherent nature, whether we look to the chance of 
 establishing it as a system of truth, or of refuting 
 it as a delusion, cannot possibly be overcome. But 
 many reasons concur to lead us to the belief, that 
 the tests of truth and of error will be applied to 
 this system, before much time elapses, with far 
 greater efficiency than in the past period of its ex- 
 istence. The extraneous sources of error and diffi- 
 culty must fast disappear. It has gone through the 
 fierce ordeal of animosity to which a new doctrine, 
 interfering largely with established opinions, is al- 
 ways subjected ; but this animosity cannot last for 
 ever, — it is already on the decline, and must soon 
 give way, on the part of the world of science, to a 
 desire to investigate dispassionately an hypothesis 
 which offers so large a field of interesting inquiry. 
 
( 266 ) 
 
 CHAPTER XI. 
 
 OF REASON IN ANIMALS. 
 
 Now, as it is to sensation, distinct from thought, 
 that we have ascribed all the motions of organized 
 beings, properly called instinctive, so it is to the 
 head of thought — the last and noblest function of 
 such beings — that we must refer all those distin- 
 guished by the name of rational. 
 
 Of such motions as these, in plants, we have no 
 unequivocal indications ; and it seems probable 
 that the highest source of motion in them is in- 
 stinct, the highest function sensation. 
 
 And, that the same is the case also with quite the 
 lowest tribes of animals, can hardly be doubted. 
 The corallines betray no evidences whatever of any 
 function approaching to thought, and its exercise 
 is very questionable in most other zoophytes. But 
 in insects in general, motions excited by this func- 
 tion are sufficiently obvious, and in some of them 
 exceedingly striking. Thus, though it is from in- 
 stinct probably that the ant hoards up grain, is it 
 not from reason that she bites off the germinating 
 part of it, if it have ever sprouted on her hands ? 
 
OF REASON IN ANIMALS. 267 
 
 and, though it is probably from instinct that the 
 spider constructs her web, is it not from reason 
 that she refrains from seizing a fly upon it, if she 
 observe at the same time an enemy to be dreaded. 
 The story also related by Darwin, and so frequent- 
 ly repeated since, seems to us quite conclusive in 
 favour of the reason of some insects. A wasp had 
 caught a fly, almost as big as herself, with which 
 she attempted in vain to rise in the air. Conclud- 
 ing that the weight of her prey was the impediment, 
 she alighted, and sawed oiF the head and tail, be- 
 fore she again took to flight. The weight was now 
 no obstacle to her progress, but she had not calcu- 
 lated upon the wind catching the wings of her vic- 
 tim, and thus retarding her ; which, however, she 
 no sooner observed to be the case, than she again 
 alighted, and, having deliberately removed first one 
 wing and then the other, carried it off triumphant- 
 ly to her nest ! 
 
 Many facts analogous to these are on record. 
 M. Cossigny saw, in the Isle of France, a sphege at- 
 tempt to drag a dead cockroach into its hole, which 
 was too big to enter it. After several ineffectual 
 attempts, the animal reduced the size of its prey by 
 biting off its elytra and legs, and then easily effect- 
 ed his purpose — {Reaum. vi. 283). That insects 
 gain knowledge from experience, is proved by Huber 
 {Linnean Transactions, vol. vi.), who states, that 
 he has seen large humble bees when unable, from 
 the size of their head and thorax, to reach the bot- 
 tom of the long tubes of the flowers of beans, go 
 
'2(j8 of reason in animals. 
 
 directly to the calyx, pierce it as well as the tube 
 with the exterior horny parts of their proboscis, and 
 then insert their proboscis itself into the orifice and 
 abstract the honey. Kirby and Spence noticed 
 holes at the base of the long nectaries of Aquilegia 
 vulgaris, and attributed them to the same agency ; 
 and, to use their words, " from these statements it 
 seems evident, that the larger bees did not pierce 
 tile bottoms of the flowers until they had ascertain- 
 ed by trial that they could not reach the nectar 
 from the top ; but that, having once ascertained by 
 experience that the flowers of beans are too strait 
 to admit them, they then, without further attempts 
 in the ordinary w^ay, pierced the bottoms of all the 
 flowers which they wished to rifle of their contents." 
 — {Entomology, ii. 522). Petit- Thouars observed 
 the same fact with regard to other flowers. — 
 {Nouveau Bulletin des Sciences, i. 45). 
 
 That insects communicate and receive informa- 
 tion, is fully proved by every historian of the ant 
 and the hive-bee. Kalm relates (Travels in North 
 America, i. 239), that the celebrated Dr Franklin 
 told him that, having placed a pot containing trea- 
 cle in a closet infested with ants, these insects 
 found their way into it, and were feasting very 
 heartily when he discovered them. He then 
 shook them out and suspended the pot by a string 
 from the ceiUng. By chance one ant remained, 
 which, after eating its fill, ^\^th some difficulty 
 found its way up the string, and thence, reaching 
 the ceiling, escaped by the wall to its nest. In 
 
OF REASON IN ANIMALS. 26!) 
 
 less than half an hour a great company of ants sal- 
 lied out of then- hole, climbed the ceiling, crept 
 along the string into the pot, and began to eat 
 again. This they continued until the treacle was 
 all consumed, one swarm running up the string 
 while another passed down. That one ant must 
 have communicated the situation of the pot to its 
 comrades, and guided them to it by the only road 
 by which it was accessible. 
 
 But it is principally in the several tribes of ver- 
 tebrate animals, that we observe all the same intel- 
 lectual faculties — differing only in degree — and all 
 the same propensities, which display themselves in 
 man. They learn by experience to procure the 
 aliment destined for their nourishment, to put in 
 practice the means proper for their own preserva- 
 tion and that of their young, to combine together, 
 not only habitually, but in cases of sudden emer- 
 gency, and to regulate their conduct in general 
 according to circumstances, and they may be arti- 
 ficially instructed in some things almost as readily 
 as a child. Thus, although in their selection, each 
 of its own peculiar kind of food, they are guided pro- 
 bably by instinct alone, it is not unfrequently rea- 
 son which directs them how to procure it. A crow, 
 for example, has been observed after having caught 
 a shell-fish, the covering of which she could not 
 break, to rise with it into the air, and, dropping it 
 from on high upon a stone, to make an easy prey 
 afterwards upon the meat which it contained ; and 
 we all know the story of the poet iEschyluSj whose 
 
270 OF REASON IN ANIMALS. 
 
 death is said to have been occasioned by an eagle 
 having in this manner dropped a tortoise on his 
 bald head, which slie had mistaken for a rock. Eh' 
 Fleming bears witness to this fact in the history of 
 birds, with some important additions. " Thus, for 
 example," he says, " we have seen the hooded-crow 
 in Zetland, when feeding on the testaceous mol- 
 lusca, able to break some of the tenderest kinds by 
 means of its bill aided in some cases by beating 
 them against a stone ; but as some of the larger 
 shells, such as the buckie and the whelk, c annot 
 be broken by such means, it employs another me- 
 thod, by which, in consequence of applying foreign 
 power, it accomplishes its object. Seizing the shell 
 with its claws it mounts up into the air, and then 
 loosing its hold, causes the shell to fall among stones 
 (in preference to the sand or the soil on the ground) 
 that it may be broken and give easier access to the 
 contained animals. Should the first attempt fail, a 
 second or third is tried, with this difference, that the 
 crow rises higher in the air in order to increase the 
 power of the fall, and more effectually remove the 
 barrier to the contained morsel. On such occasions 
 we have seen a stronger bird remain an apparently 
 inattentive spectator of the process of breaking the 
 shell, but coming to the spot with astonishing keen- 
 ness when the efforts of its neighbour had been 
 successful, in order to share in the spoil. (Philo- 
 sophy of Zoology^ i. 231.) 
 
 The common throstle (Turdus musicwi) adopts 
 the same method to break the shells of Turbo lit- 
 
OF REASON IN ANIMALS. 271 
 
 foreus and Trochus conuloides. These birds are 
 well known to feed on snails, fracturing their brit- 
 tle shells by taking them in their beaks and knock- 
 ing them against a stone. Periwinkles, however, 
 require considerable force to break their shells, and 
 the bird effects its purpose by letting them fall 
 from some height on the hard stones. This is only 
 one remove — and it is a remove perhaps rather in 
 favour of the birds — from the well known practice 
 of the monkey, which, when its teeth are inade- 
 quate to crack a nut, uses a stone for the purpose. 
 Although perhaps the following passage, which we 
 translate from the French as quoted by Dugald 
 Stewart from Bailly, the author of L'Histoire de 
 VAstrouomie^ gives it perhaps in favour of the 
 monkey. " One of my friends, a man of intelli- 
 gence and veracity, communicated to me two facts 
 witnessed by himself. He had a very sagacious 
 ape ; he amused himself with giving the animal 
 nuts, of which it was very fond, but as he threw 
 them down at some distance, the ape, confined by 
 his chain, could not reach them; after many efforts 
 ineffectual to any purpose but that of whetting his 
 invention, the ape seeing a servant pass with a nap- 
 kin under his arm, snatched the napkin and made 
 use of it to reach the nuts and bring them towards 
 him. To break the nuts required a new exertion 
 of ingenuity ; this he accomplished by placing 
 the nut on the ground and letting a stone or pebble 
 fall from a height sufficient to break it. You remark 
 that without the benefit of Galileo's knowledge of 
 the laws of falling bodies, the ape had observed the 
 
272 OF REASON IN ANIMALS. 
 
 force which such bodies acquire in their descent. 
 This plan, however, did not succeed on every occa- 
 sion. One day it had rained, the ground was soft, 
 the nut sunk into it so as to prevent the stone from 
 taking effect. Wliat contrivance does the ape fall 
 on ? He looked about for a tile, set the nut upon 
 it, and letting the stone fall he broke it without any 
 farther difficulty." {Discours et Memoires par 
 VAuteur de VHistoire de V Astronomie^^ Paris 1796, 
 tome ii. p. 126.) 
 
 Instinct, or the mere sensation of a want, could 
 never have suggested devices like these, implying, 
 as they do, at once attention to the effects of the 
 concussion of a brittle and an unyielding substance, 
 and the influence of height on gravitation in in- 
 creasing this concussion ; memory of such previous 
 experience ; comparison between substances of 
 different degrees of consistence and between dif- 
 ferent heights ; judgment in selecting a particular 
 substance and height best adapted for the purpose ; 
 and REASON in concluding that what had happened 
 before under certain conditions would happen again. 
 Further, although all animals are by instinct prompt- 
 ed to self-preservation, it is often reason which sug- 
 gests to them where danger is to be apprehended, 
 and how it is to be avoided. Thus it is well known 
 that a scarcely fledged bird allows itself without 
 any apprehension to be approached by boys, of 
 whom she is soon taught by experience to stand in 
 deadly fear; and it has been frequently noticed, 
 that all the brute inhabitants of a district, on its 
 first discovery by man, are generally perfectly fear- 
 
OF REASON IN ANIMALS. 273 
 
 less of him, and only come gradually to regard him 
 as an enemy. All the elements of thought are here 
 likewise obviously put into requisition. And in 
 avoiding apprehended dangers either to themselves 
 or offspring, what intelligence is frequently display- 
 ed by the inferior animals ! What teaches the 
 pigeon to remain on her perch when an eagle is at 
 hand, but a reasonable persuasion of security, 
 founded on the observation that it is only or chiefly 
 when on the wing that the members of her tribe 
 are clutched by the noble bird ; and what instructs 
 the hare to squat on the approach of the greyhound, 
 but a reasonable conviction, founded on experience, 
 that her safety depends rather on concealment than 
 on speed ? Why does she also abstain in general 
 from feeding near home, and, when the snow is on 
 the ground, refrain from stirring out as long as 
 possible, except from the apprehension that the de- 
 vastation which she might produce in the former 
 case, and her footsteps in the latter, would betray 
 her hiding-place ? An experienced deer, more- 
 over, knows how to elude the hunter by innumera- 
 ble feints ; and the tricks of an old fox, both in at- 
 taining his prey and avoiding the snares set for 
 him, are often so ingenious as to have rendered the 
 term emblematical of a cunning fellow. Again, it 
 is from instinct that birds build their nests, but it 
 is from reason that they make them inaccessible if 
 they have ever had their eggs stolen ; and accord- 
 ingly, certain tribes, which, under ordinary circum- 
 stances, construct their nests directly among the 
 
274 OF REASON IN ANIMALS. 
 
 branches of trees, in districts which are infested by 
 monkeys, make them to hang from these branches 
 in such a manner as to elude the grasp of the 
 spoiler. The devices also frequently resorted to by 
 the partridge and other birds, as well as those of cats 
 and many other quadrupeds, to divert the attention 
 of passengers from the situation of their nests and 
 lairs, by enticing them to attempt their own cap- 
 ture, and other means, are known to every school- 
 boy, and speak volumes in favour of the presump- 
 tion of their reasoning powers. But the occasional 
 co-operation of the lower tribes of animals, imply- 
 ing, as it does, previous consultation with respect 
 to the best means of attaining some particular ob- 
 ject — to say nothing of their habitual combinations 
 preparatory to migration and so forth, which are 
 probably instinctive alone — is still more remark- 
 able than any action prompted by their individual 
 intelligence. The following is related by Father 
 Bougeant : — " A sparrow finding a nest that a 
 martin had just built standing very conveniently 
 for him, possessed himself of it. The martin, see- 
 ing the usurper in her house, called for help to 
 expel him ; — a thousand martins came full speed 
 and attacked the sparrow, but the latter, being 
 covered on every side, and presenting only his large 
 beak at the entrance of the nest, was invulnerable, 
 and made the boldest of them who durst approach 
 him repent of his temerity. After a quarter of an 
 hour's combat, all the martins disappeared. The 
 sparrow thought he had got the better ; and the 
 
OF REASON IN ANIMALS. 275 
 
 spectators judged that the martins had abandoned 
 their undertaking. Not in the least. Immediately 
 they returned to the charge ; and each having pro- 
 cured a little of that tempered earth with which 
 they make their nest, they all at once fell upon the 
 sparrow and inclosed him in the nest to perish there, 
 though they could not drive him thence." 
 
 To these striking instances of the exercise of 
 reason in the lower animals it might seem unne- 
 cessary to add any others ; but as we are well 
 aware that there is a strong repugnance on the 
 part of many well informed and judicious people to 
 receive evidence of such a power in other crea- 
 tures than man ; and as some of the instances be- 
 fore stated may be perhaps by some persons re- 
 duced to the rank of instincts, we propose to lay a 
 few illustrative and well marked examples of rea- 
 son in animals before our readers. We shall be- 
 gin with mammals, and pass on to birds, fishes, 
 and reptiles. And first, of the dog, which might 
 afford to proud imperial man many lessons of con- 
 duct and morality which it were M'ell for him if he 
 would adopt ; and the " brute," often less brutal 
 than his savage master, has displayed actions which 
 might make his tyrant lord almost ashamed of his 
 humanity.* 
 
 * Our friend Dr Duncan of Ruth well has recorded, in hie 
 interesting " Philosophy of the Seasons," a conversation to 
 which, as a boy, he listened between the two poets Burns and 
 Blacklock. The subject was the fidelity of the dog. Burns 
 took up the question with all the ardour and kindly feeling witli 
 
27h OF REASON IN ANIMALS. 
 
 These actions are not instinctive but rational. 
 Witness tlie effects of his reasoning powers — his 
 thinking faculties — in lessening the dangers of the 
 winter storm, and mitigating the rigours of an un- 
 genial climate. We allude to the dogs of St Bernard ; 
 their history is well known, and surely it is not in- 
 stinct that sends them on their errands of huma- 
 nity ; it is not instinct that prompts them, when 
 the sky is dark and clouded, and the winds howl^ 
 and the snow swirls through the freezing air, to 
 leave their warm and cheering lair before the con- 
 vent fire to seek the hapless passengers exposed to 
 all the dangers of the mountain pass. It is not in- 
 stinct that teaches them, when they find an un- 
 happy wanderer sleeping beneath some thundering 
 avalanche, a sleep which promises to wake him in 
 
 which the conversation of that extraordinary man was so re- 
 markably embued. " Man," said he, " is the God of the dog 
 He knows no other; he can understand no other; — and see 
 how he worships him ! With what reverence he couches at 
 his feet ; with what love he fawns upon him ; with what de- 
 pendence he looks up to him ; and with what cheerful alacrity 
 he obeys him. His whole soul (? m'md^ is wrapped up in his 
 God ; all the powers and faculties of his nature are devoted to 
 his service ; and these powers and faculties are ennobled by the 
 intercourse. Divines tell us that it ought just to be so with 
 jhe Christian ; but the dog puts the Christian to shame." — 
 " The truth of these remarks," adds the Rev. Doctor, " which 
 forcibly struck me at the time, have since been verified by expe- 
 rience ; and often have events occurred which, while they re- 
 minded me that ' man is the God of the dog,' have forced from 
 me the humiliating confession, that < the dog puts the Chri»- 
 tiaii to shame.' " 
 
OF REASON IN ANIMALS. 277 
 
 eternity, to set up a continued hoarse and solemn 
 bark, and thus to bring the watchful monks to their 
 assistance. We grant it is instinct which enables 
 them to smell the perishing traveller ten and some- 
 times fifteen feet beneath the snow ; but we hold 
 it is reason that sends them on the search, and 
 makes them give notice to their pious masters of 
 the discovery they have made. It may be said 
 they are trained to this ; be it so : but an animal, 
 be it man or brute, is rational in proportion as he 
 is educatable. Captain Brown, in his anecdotes of 
 dogs, has detailed many of the shepherd's collie, 
 where wisdom little short of human has been dis- 
 played in the extrication of their masters from dan- 
 gers to which the inhabitants of mountainous dis- 
 tricts are peculiarly exposed. But we must refer 
 our reader to that gentleman's very entertaining 
 and instructive work. 
 
 There are few pictures more beautiful to the re- 
 flective mind than the care and intelligence with 
 which the dog will lead his blind master. Faber, 
 in his " Exposition des Animaux de la Nouvelle 
 Espagne^^ as quoted by Virey, has described at 
 great length the sagacity which the animal upon 
 these occasions exhibits ; and few who reside in 
 the great cities of Europe can have failed to ob- 
 serve it. The dog leads the beggar from his home 
 in the morning to the spot where he is to solicit cha- 
 rity, guiding him by the most direct route, and, 
 with the greatest anxiety, avoiding obstacles, such 
 as broken pavements and heaps of rubbish, over 
 which he might stumble ; in the evening, with the 
 
278 OF REASON IN ANIMALS. 
 
 same care, he is conducted to his homCy where the 
 faithful guide receives, as a recompense for his fi- 
 dehty, a few morsels of bread, frequently unwilling- 
 ly doled out, and too often embittered with blows 
 and imprecations. But what of this ? affection is 
 stronger than the recollection of injury ; he licks 
 the hand that has beaten him, — avenges himself by 
 new proofs of inviolable attachment, — and, with the 
 early morning, recommences his labour of love. 
 Dogs are known thus to guide their masters to 
 houses where they are accustomed to receive alms 
 on certain days, there to lie down at their feet to 
 rest, and not to move till some gratuity has been 
 bestowed. In Rome beggars are thus led to 
 churches in the suburbs, often miles from their re- 
 sidences, where they count their beads, utter a few 
 paternosters, and receive a small piece of money, 
 which is no sooner bestowed than up jumps the 
 dog and proceeds upon his pilgi'image. " I have 
 seen," says Faber, and the same may be often 
 seen, " not without pleasure and surprise, that 
 when a few small pieces of coin were thrown to a 
 blind singer in the street, his dog would pick them 
 all up and place them in the little cap or box held 
 in his master's hand ; if bread be thrown, he col- 
 lected it in the same way, and patiently waiting 
 until his due share was presented to him to satisfy 
 the cravings of hunger." Although it is far from 
 our intention to multiply examples of the reasoning 
 powers of animals, yet we shall detail a few that 
 bear illustratively upon our subject. A friend of 
 ours shooting upon the Everingham estate in York- 
 
OF REASON IN ANIMALS. 279 
 
 shire, lost a set of seals by the breaking of the chain 
 by which they were appended to his watch. He 
 recollected to have observed them on his person, 
 when in a large field of turnips, nearly a mile 
 from the spot where he then stood. He called 
 a very intelligent retriever that was with him ; 
 he shewed him the broken chain, and compared 
 it with the chain and seals of another gentle- 
 man present. Solway understood what had occur- 
 red ; hurrying off and retracing his steps, he found 
 the lost seals in the turni^D field, and brought them 
 to his master. The same gentleman, when he shot 
 a hare early in the day and was unwilling to carr)- 
 it, always left it in some secure nook, shewing it to 
 the dog, who, on returning in the evening, would, 
 when desired, go and bring it home. A volume of 
 well authenticated anecdotes of this kind might be 
 laid before the inquiring reader ; we shall detail 
 one more. Two gentlemen started early from In- 
 verleithen to fish ; they were accompanied by a 
 favourite retriever, and walked for some miles up 
 the Tweed before they began to cast their lines. 
 'Arrived at their ground, one of the party discover- 
 ■ed he had lost his flies ; he called his dog, shewed 
 him a similar book belonging to his companion, and 
 desired him to seek its fellow. Off went Can, and, 
 in less than half an hour, returned with the book. 
 
 If farther proof is wanted, it is related that at a 
 convent in France twenty paupers were served 
 with dinner at a certain hour every day. A dog 
 belonging to the establishment did not fail to be 
 
280 OF REASON IN ANIMALS. 
 
 present at this regale to receive the odds and ends 
 which were now and then tlirown down to him. 
 The guests, however, were poor and liungry, and 
 of course not very wasteful, so that their pensioner 
 did little more than scent the feast of which he 
 would fain have partaken. The portions were 
 served out by a person at the ringing of a bell, and 
 delivered out by means of what in religious houses 
 is called a tour, which is a machine like the section 
 of a cask, that, by turning roimd upon a pivot, ex- 
 hibits whatever is placed on the concave side, with- 
 out discovering the person who moves it. One 
 day this dog, who had only received a few scraps* 
 waited till the paupers had retired, took the rope 
 in his mouth, and rang the bell. His stratagem 
 succeeded. He repeated it the next day with the 
 same good fortune. At length the cook finding 
 that twenty-one portions were given out instead of 
 twenty, was determined to discover the trick, in 
 doing which he had no great difficulty ; for lying 
 perdu, and noticing the paupers as they came in 
 with great regularity for their different portions, 
 and seeing there was no intruder except the dog, 
 he began to suspect the real truth, which he was 
 confirmed in when he saw the dog wait with great 
 deliberation till the visitors were all gone and then 
 pull the bell. The matter was related to the com- 
 munity, and to reward him for his ingenuity, he 
 was permitted to ring the bell every day for his 
 dinner, when a mess of broken victuals was pur- 
 posely served out to him. (DihdirCs Observations 
 
OF REASON IN ANIMALS. 281 
 
 in a Tour through England.) We are acquainted 
 with an instance somewhat analogous to this : A 
 gentleman visiting a friend, always left his dog, a 
 fine Newfoundland, at the gate. The animal was 
 very anxious to follow his master but never allowed 
 to do so ; at length observing that on pulling the 
 bell the gate was invariably opened, he managed to 
 do so for himself, the domestic answered the sum- 
 mons, and in leapt the dog. 
 
 The attachment of the dog to his master is in- 
 violable, even in death ; to save him he will plunge 
 unhesitatingly into the angry flood, and mourning 
 his loss, he will die of sorrow and of hunger upon 
 his tomb. Virey mentions a dog who was seen by 
 thousands in Paris howling on a piece of ice upon 
 the Seine, from which his master had fallen and 
 sunk amid the waters. Nothing could win him 
 from his post of heroic fidelity and devotion ; there 
 he remained for three days and two nights when a 
 thaw commenced and he sunk near the spot where 
 the master he regretted with so much constancy 
 had been seen to disappear. There are many af- 
 fecting stories of a similar character. Daniel 
 {Field Sports, ii. 499) tells of a spaniel who, dur- 
 ing the last stage of consumption which carried his 
 master to the grave, unweariedly attended the foot 
 of his bed ; when he died the dog would not quit 
 the body, but lay upon the bed by its side. It was 
 with difficulty he was tempted to eat any food ; 
 and, although carried to the house of a friend, and 
 caressed with all the tenderness so fond an attach' 
 
282 OF REASON IN ANIMALS. 
 
 nient naturally excited, he took every opportunity 
 to steal back to the room where his master had ex- 
 pired and where he would remain for hours. From 
 thence, tor fourteen days, he constantly visited the 
 grave, at the end of which time he died — May we 
 not say of a broken heart ? 
 
 The story of Boswell is not imaginary, for many 
 instances might be adduced where criminals have 
 been discovered and brought to justice through the 
 agency of a dog. It cannot be to simple instinct 
 that these actions are to be referred ; on the con- 
 trary, the candid and unprejudiced reader must 
 allow that they are the result of very extended and 
 complex processes of reason — a reason differing 
 from that possessed by man not in kind but merely 
 in degree. 
 
 The manifestation of reason in dogs has been so 
 considerable, that some writers have been induced, 
 in the spirit of human pride and audacity, to ascribe 
 these actions, not to reason, but to a particular in- 
 terposition of Divine Providence. Of this nature 
 Mr Kirby, in his interesting but very unequal work, 
 the Bridgewater Treatise, on the history, habits, and 
 instincts of animals, conceives to be the account 
 given by Mr French (^Zool. Journ. i. 7.) of Sir H. 
 Lee's dog, which saved its master's life by taking 
 and maintaining its station, which it had never done 
 before, under his bed ; and also the instance related 
 by Beattie, which we repeat at length : — A gentle- 
 man named Irvine was crossing the Dee near Aber- 
 deen, then frozen over, the ice gave way about the 
 
OF REASON IN ANIMALS. 283 
 
 middle of the river and he sunk ; but having a gun in 
 his hand, he supported himself by placing it across the 
 opening in the ice through which he fell. His dog 
 used many fruitless efforts to save his master, and then 
 ran to a neighbouring village, where he saw a man, 
 and with most significant gestures pulled him by 
 the coat and prevailed upon him to follow him. 
 The man arrived at the spot in time to save the 
 gentleman's life. " These cases are remarkable," 
 says the reverend author, " but they do not appear 
 to belong to instinct, but rather to the doctrine of 
 a particular Vrovidence^ It is certainly not to 
 instinct that the above quoted rational actions can 
 be referred — ^which, however, we would observe, are 
 not more remarkable than many others which the 
 same animals are known to practise, for the acquire- 
 ment of an end totally unconnected either with the 
 prevention of a calamity or the production of a 
 benefit, and in which no particular providence could 
 for a moment be supposed to exert its influence. 
 Many we have alluded to bear upon this, as still 
 more so does the following, which Dr Hancock 
 quotes from Dr Abel's Lectures on Phrenology. 
 " The dog, a Newfoundland, was of a generous and 
 noble disposition, and when he left his master's 
 house was often assailed by a number of little noisy 
 dogs in the street. He usually passed them with 
 apparent unconcern, as if they were beneath his 
 notice ; but one little cur was particularly trouble- 
 some, and at length carried his petulance so far as 
 to bite the Newfoundland dog in the back of his 
 
*JK4 OF REASON IN ANIMALS. 
 
 tbot. This proved to be a step in wanton abuse 
 and insult beyond what was to be patiently endured, 
 and he instantly turned round, ran after the offender, 
 and seized him by the skin of liis back ; in this 
 way he carried him to the quay, and holding 
 him for some time over the water, at length dropped 
 him into it. He did not seem, however, to design 
 that the culprit should be punished capitally, and 
 he waited a little while till the poor animal, who 
 was unused to that element, was not only well 
 ducked but near sinking, when he plunged in and 
 brought him safe to land." 
 
 Is any " Divine interposition " to be supposed in 
 the following anecdote, which we give as we receiv- 
 ed it from our reverend friend Dr Duncan, one of 
 the parish ministers of Dumfries : — 
 
 One evening in spring, many years ago, the in- 
 mates of a farm-house near Gatehouse-of-Fleet 
 were alarmed by a loud screaming and knocking at 
 the kitchen door, accompanied by the flapping of 
 wings. On going to ascertain the cause, the ser- 
 vants discovered a gander in violent agitation, which 
 instantly setoff in the direction of the goose-house, 
 at the same time shewing by very significant ges- 
 tures that he wished to be followed. No sooner 
 had the place been entered than the cause of the 
 commotion became evident. A felon polecat rush- 
 ed out at the door, and on a nest within, covering 
 a brood of young goslings, sat the body of a slaugh- 
 tered goose. The affectionate mother had gene- 
 rously maintained her post at the expense of her 
 
OF REASON IN ANIMALS. 285 
 
 life, jather than abandon her little ones to her 
 ravenous assailant. 
 
 We have shortly alluded to this subject in our 
 eighth chapter ; and, at any rate, this is not the 
 place to discuss so unprofitable a doctrine as Mr 
 Kirby advocates. The Christian will readily ac- 
 knowledge, not only the omnipresence, but the om - 
 niscience of God, and confess that not a sparrow 
 falls without his knowledge and permission ; but 
 whether at times he does, as He did of old, before 
 the Christian dispensation, forsake the general laws 
 by which he rules and acts in order to adapt them 
 to particular circumstances, we do not believe, but 
 certainly we will not pretend to decide, contenting 
 ourselves with the humble confession, that " such 
 knowledge is too wonderful for us — it is high, we 
 cannot attain unto it." 
 
 We may perhaps be permitted shortly to remark, 
 that the supporters of the doctrine in question lay 
 great stress upon the fact, that a man has dreamed 
 he would die upon a certain day, and thus been 
 warned of his approaching fate ; that the day has 
 come, and the dream been realized. But is this a 
 particular providence of the Most High ? is it His 
 voice speaking amid the airy nothingness of a 
 dream ? or is it not rather the effects of an imagi- 
 nation unbridled by the restraints of reason — a par- 
 tial imbecility, the concomitant of the " fine 
 phrensy" of poesy ? Dark things may be done by 
 our own fantastic persuasions, and belief will en- 
 sure the miracles that it credits. The most potent 
 
286 OF REASON IN ANIMALS. 
 
 witcheries are less potent than fancy itself; and, as 
 we have somewhere seen remarked, Macbeth was 
 a murderer not because the witches predicted, but 
 because their prediction gave origin to the thought. 
 
 Among mammals, another very intelligent ani- 
 mal is the horse, of whom mt shall mention one 
 anecdote. 
 
 Some years ago, when deep-drinking was in 
 vogue, and landlords inhospitable who saw not their 
 guests under the table, a friend of ours possessed a 
 horse very difficult to mount, and, when mounted, 
 highly impatient and irritable. When this gentle- 
 man rode home at night from a convivial meeting, 
 his horse seemed conscious of the condition of his 
 master ; he permitted himself to be backed with 
 the greatest steadiness ; and, although at other 
 times he would evince his disapprobation of the 
 whip by violently kicking, rearing, and running 
 away, now^ neither whip nor spur would induce him 
 to depart from the walk, or otherwise to shew his 
 displeasure. On these occasions a person has come 
 behind him and applied the whip ; for a moment 
 his instinct would preponderate over his reason, 
 and a disposition to resent to injury manifest itself. 
 But it would be for a moment ; he scarcely lifted 
 his leg from the ground to inflict the blow when it 
 was quietly replaced, " willing to wound but yet 
 afraid to strike" lest his master should be injured 
 by his petulance.* 
 
 * He was the grandson of tbe Duke of Hamilton's celebrated 
 " Daintie Davie," and like his grandsire brought up by the 
 
OF REASON IN ANIMALS. 287 
 
 It is mentioned in the London Magazine of Na- 
 tural History (vol. iv. p. 499.)) that a young lamb 
 was observed to be entangled among some briars, 
 and it had seemingly struggled for liberty until it 
 was quite exhausted. Its mother was present, en- 
 deavouring with her head and feet to disentangle 
 it. After having attempted in vain for a long time 
 to effect this purpose, she left it, and ran away 
 baaing loudly and dolefully. Thus she proceeded 
 across three fields, until she came to a flock of 
 sheep ; among them she tarried for about five mi- 
 nutes, and left accompanied by a large ram that 
 had two powerful horns. They returned speedily 
 towards the poor lamb ; and, as soon as they reach- 
 ed it, the ram immediately set about liberating it, 
 which he did in a iew minutes, by dragging away 
 the briars with his horns. " Now it may be asked,** 
 continues the observer, " what analogy, even in the 
 
 hand, his mother dying three days after he was foaled. He 
 lived for the most part, while a coif, in the kitchen of Gribton 
 House, Dumfriesshire, a protege of the cook, sleeping in the 
 '* peat neuk '' at night, and gamboling among the dogs during 
 the day. These Le always accompanied to the chase, and, like 
 them, often made his way, rather an unwelcome guest, to dif- 
 ferent parts of the house. Till he was taken up for breaking, 
 he evinced the greatest docility, but, no sooner was a bit placed 
 in his mouth and he found himself restrained, than he rushed 
 at the breaker, and pursued him into the kitchen and through 
 other rooms, the man sought protection behind a door against 
 which the horse violently kicked. He was broken, however, 
 but became wild and vicious except on such occasions as we 
 have recorded. He afterwards went to Walcheren, where he 
 was celebrated for the attachment he shewed to his master. 
 
288 OP REASON IN ANIMALS. 
 
 remotest degree, had the actions mentioned in the 
 above anecdote to tlie ojierations of instinct ? Was 
 it an ' involuntary desire' that induced the sheep 
 to endeavour to Hberate her young one when she 
 observed it imprisoned amongst the briars ? Was 
 she urged by an ' involuntary desire,' or did she 
 act ' without motive or dehberation' when she ran 
 across three large fields, and surmounted four strong 
 thorn hedges in search of its relief, which, by these 
 means, she must have known, or at least hoped, 
 that she could obtain ? Did the ram act ' without 
 motive or deliberation' when he returned with her, 
 of course according to her request, and affected 
 what she desired ? Or is it not infinitely more pro- 
 bable, is it not, indeed, indisputable, that these and 
 a thousand actions of a similar nature, which are 
 daily observable in our domesticated animals are 
 ' perfectly free,' are the ' result of volition, are, in 
 short, neither more nor less than the operations of 
 reason ? 
 
 The following instances, as quoted by Hancock, 
 of the power of goats to accommodate their actions 
 to new circumstances, imply the exercise of the 
 reasoning faculty in no inconsiderable degree. 
 " Two goats grazing about the ramparts of Ply- 
 mouth citadel, got down upon a narrow ledge of 
 the rock, and one of them, advancing before the 
 other, came to an angle where it was enabled to 
 turn ; but, in its way back, met its companion, 
 which produced a most perplexing dilemma, as it 
 was impossible for them to get past each other. 
 
OF REASON IN ANIMALS. 289 
 
 Many persons saw them without being able to lend 
 any assistance. After a considerable time one of 
 the goats was observed to kneel down with great 
 caution, and crouch as close as it could lie ; which 
 was no sooner done than the other, with great dex- 
 terity, walked over him, and both returned the way 
 they came in perfect safety. And at Ardinglass, 
 near Glenarm in Ireland, two goats, moving to- 
 wards each other over a precipice a thousand feet 
 high, were seen to extricate themselves from dan- 
 ger by a similar expedient." 
 
 In Rees's Cyclopaedia the following singular anec- 
 dote of a cat is found : — " A lady had a tame bird 
 which she used to let out of its cage every day. 
 One morning, as it was picking up crumbs from 
 the carpet, her cat, who always before shewed 
 great kindness to the bird, seized it on a sudden, 
 and jumped with it in her mouth upon the table. 
 The lady, alarmed for the fate of her favourite, on 
 turning about, observed that a strange cat had just 
 come into the room. After turning it out, her 
 own cat came down from her place of safety, and 
 dropped the bird without inflicting the least in- 
 jury." On this case Hancock, who also quotes it, 
 remarks, " It seems very clear on considering this 
 act, that various circumstances must have influ- 
 enced this sagacious animal. She must have known 
 that the bird was in danger from the intruder, and 
 must have reflected on the best means of rescue ; 
 and we may take it for granted that instinct could 
 not, on the same principle, have prompted the one 
 
 T 
 
290 OF REASON IN ANIMALS. 
 
 cat to destroy ami the other cat to save at the same 
 moment of time. But the manner in which the 
 preservation was effected is instructive, and affords 
 a very striking example of reasoning in the brute^ 
 the more so as cats are not remarkable for sagacity." 
 (P. 84.) 
 
 With regard to birds : in Lord Bacon's writings 
 is to be found an instance of reasoning in a raven, 
 in the application of means to the fulfilment of a 
 desired end which would do no discredit to human 
 sagacity ; finding, during a severe drought, water 
 in the bottom of a tin which she could not reach, 
 she threw in stones till the water rose and she could 
 obtain it. This is so remarkable an exercise of 
 reason and display of knowledge acquired by ex- 
 perience, that but for the place where it is found, 
 one would readily infer that iEsop had invented it 
 as a useful lesson of wisdom to man, rather than 
 that a philosopher had actually observed it in a 
 raven. 
 
 The Encyclopaedia Britannica affords the follow- 
 ing fact as is alleged on unimpeachable authority : 
 " In the spring of 1791 a pair of crows made their 
 nest on a tree of which there were several jilanted 
 around the narrator's garden, and in his morning 
 walks he had often been amused by witnessing fe- 
 rocious combats between them and a cat. One 
 morning the battle raged more fiercely than usual, 
 till at last the cat gave way and took shelter under 
 a hedge, as if to wait a more favourable opportunity 
 of retreating to the house. The crows continued 
 
OF REASON IN ANIMALS. 291 
 
 for a short time to make a threatening noise, but 
 perceiving that on the ground they could do nothing 
 more than threaten, one of them hfted a stone from 
 the middle of the garden and perched with it on a 
 tree planted in the hedge, where she sat watching 
 the motions of the enemy of her young. As the cat 
 crept along under the hedge, the crow accompanied 
 her by flying from branch to branch and fi'om tree 
 to tree ; and when at last puss ventured to quit her 
 hiding-place, the crow leaving the trees and hover- 
 ing over her in the air, let the stone drop from on 
 high on her back. The writer remarks, that the 
 crow on this occasion reasoned is self-evident; 
 and it seems to be little less evident that the ideas 
 employed in her reasoning were enlarged beyond 
 those ideas she had received from her senses. By 
 her senses she may have perceived that the shell 
 of a fish is broken by a fall, but could her senses 
 inform her that a cat would be wounded or driven 
 off the field by the fall of a stone ? No ; from the 
 effect of the one fall preserved in her memory, she 
 must have inferred the other by her power of rea- 
 soning." 
 
 Mr White has recorded in Loudon's Magazine 
 (ix. 377), the following proof of reasoning in the 
 domestic cock. One of these birds, belonging to 
 his neighbour, from whose premises his own are 
 separated by a range of stables, &c., regularly pays 
 him a visit at the breakfast and dinner hours. He 
 keeps no poultry. The bird flies to the top of 
 the stables, and watches till the meal is ended. 
 
292 OF REASON IN ANIMALS. 
 
 when he descends into the yard to partake of the 
 crumbs, with which the children take great dehght 
 in feeding him. " Within the last few days," con- 
 tinues the observer, "his conduct appears to be 
 the result of forethought. On an ample meal 
 being placed before him, he has manifested great 
 anxiety for some of his fair companions to partake 
 of it with him ; this he has strongly shewn by tak- 
 ing up pieces in his mouth, calling with loud anxiety, 
 breaking the pieces into smaller portions and lay- 
 ing them down again ; then pacing to and fro as if 
 in expectation of the arrival of some of his com- 
 panions, renewing the dividing of the larger pieces 
 into smaller, and calling with increased anxiety. 
 On two occasions he has left his meal untouched, 
 so far as regards eating any portion of it himself, 
 returned to his own premises, and brought a hen 
 with him to share in his good fortune." 
 
 Of birds a thousand anecdotes might be related 
 to prove that all their actions cannot be referred 
 to simple instinct, and that many of them must, on 
 the contrary, be elevated into tlie higher depart- 
 ment of reason. The follov.ing is v.ell known in 
 Dumfriesshire, and bears so illustratively upon our 
 subject that we must introduce it to the notice of 
 our readers. In consequence of the unusually dry 
 spring of this year (1836), that pretty piece of 
 water upon the lawn before the mansion-house of 
 James Lennox, Esq. of Dalscaith, became very 
 shallow, and exposed the numerous roots of trees 
 thrown in to give shelter to the trout, and wliicii ut 
 
OF REASON IN ANIMALS. 293 
 
 Other times were hid below water. On one of 
 these, more elevated than the others, a pair of the 
 common wild duck{Anas boschas) constructed their 
 inartificial nest ; but scarcely had a few eggs been 
 deposited when the weather changed, down came 
 the rain, fresh flowed the springs, the neighbour- 
 ing burns poured the surcharged waters into the 
 lake, which soon began to rise to its accustomed 
 bed, threatening to touch the bottom of the nest, 
 to overwhelm the labours of its luckless owners, 
 and send their eggs adrift upon the swelling tide. 
 But the ducks were not idle in making preparations 
 against the coming peril. It was an unexpected 
 occurrence, for which mere instinct had no resource ; 
 reason, however, came to their assistance, and told 
 them plainly it was time " to put their house in 
 order." And so they did. No sooner did they 
 see the lake begin to swell, than one of them was 
 observed to bring rapid supplies of grass and straw 
 and moss, M-ith which the other built away below 
 the nest, gradually raising it upon a new founda- 
 tion till several inches of elevation were gained ; it 
 thus emerged from the flood, the waters became 
 stationary, and the birds quite safe in their domi- 
 cile. The fond mother now patiently brooded her 
 full time, and one duckling rewarded her maternal 
 care ; when, just as it had escaped from the shell, 
 another torrent of rain fell more suddenly and vio- 
 lently than the first, the waters rose higher and 
 higher, the nest and the remaining eggs were swept 
 into the abyss. In this emergency, the whole at- 
 
294 OF REASON IN ANIMALS. 
 
 tention of the parents was given to the Hving pro- 
 geny, which they safely conveyed to the shore, 
 where another nest was speedily constructed, and 
 their sagacity and solicitude finally crowned with 
 success. 
 
 M. Merveaux lately communicated to the French 
 Academy of Sciences a fact very analogous to the 
 preceding. A pair of nightingales had built in the 
 lower part of a hedge in his ga"den and had depc- 
 sited four eggs, when some water in the neighbour- 
 hood rose with much impetuosity and threatened to 
 reach the nest. M. Merveaux watched tiie birds 
 with some anxiety, and the d;iy when tlie water 
 neai'ly touched the nest, he perceived that only two 
 eggs remained in it. He thought the nest had been 
 abandoned; but looking at it soon after, he found an 
 egg had been removed, and he resolved to watch. 
 He did so ; and was much astonished to behold the 
 last egg disappear with the birds, who, flying cau- 
 tiously but rapidly, carried it to a new nest, at the 
 highest part of the hedge, in which he saw the 
 tour eggs safely deposited ; and where they were 
 afterwards hatched. He could not ascertain how 
 the eggs had been transported ; the fact, however, 
 is undeniable, and highly demonstrative of the rea- 
 soning power of the birds. 
 
 There is a South American bird, Psophia cre- 
 pitans^ which, acording to Sonnini {Npuv. Diet. 
 (tHist. Naturelle, 1. 190J, exhibits reasoning pow- 
 ers of a very high order ; so much so as to be in- 
 trusted with the care of young poultry and even of 
 
OF REASON IN ANIMALS. 295 
 
 flocks of sheep, which they conduct to and from 
 their pastures. These animals have a natural incli- 
 nation for the society of man, and seem to occupy 
 the same place among birds that the dog does 
 among mammals. When taken and fed in a house, 
 it becomes attached to the inmates, and knows, 
 like the dog, the voice of its master ; following him 
 when he goes out, leaving him with reluctance, and 
 appearing delighted to see him again. Sensible of 
 his caresses, he returns them with every mark of 
 affection and gratitude ; it seems even jealous of 
 his attentions, for it will peck at the legs of those 
 who come too near to him. It knows and acknow- 
 ledges also the friends of the family. It sometimes 
 takes a dislike to individuals, and whenever they 
 appear, attacks them, and endeavours to drive them 
 away. Its courage is equal to that of the dog, for 
 it will attack animals bigger and better armed than 
 itself. {Kirhy's Bridgeivater Treatise, ii. 455.J 
 
 Descending in the scale of creation from the 
 warm-blooded animals — the mammals and birds — 
 to those among the vertebrata, which circulate cold 
 blood — the reptiles and fishes — we pass from the 
 former, possessing a very great degree of intelligence, 
 to others where stupidity is highly developed. Had 
 animals been classified according to their intellec- 
 tual powers, and not as they are in relation to their 
 structure, fishes would have preceded reptiles, and 
 insects followed the birds. This, however, is not 
 the case ; reptiles are placed before fishes, and in- 
 sects fill a post very far down in the chain of exist- 
 
29(3 OF REASON IN ANIMALS. 
 
 ences. The bruin of reptiles is very small, and far 
 from fiUin^^ the cavity which contains it ; their in- 
 tellectual faculties are proportionate to it, scarcely 
 extending to the taming of a few species of serpent 
 and lizard, and that in a very slight degree. With 
 the reasoning powers of fishes we have not much 
 acquaintance ; indeed, as inhabitants of a medium 
 so widely different from that in which man lives 
 and moves and has his being, and in general ra- 
 pidly perishing when withdrawn from their native 
 element, they are much less frequently the objects 
 of our observation than those animals which, as 
 sharing with us the vital influence of the atmo- 
 sphere and inhabitants of the soil on which we our- 
 selves rest, we meet with at every turn, and with 
 the forms and habits of which we become almost 
 unconsciously more or less familiar. Fishes arc 
 rarely domesticated with us in our houses, we do 
 not meet with them in our walks, they are not pre- 
 sented to our eyes in menageries ; we see them for 
 the most part only in our markets, or on our tables, 
 and know them only or chiefly as administering to 
 our palates. If even we follow them to their na- 
 tive haunts, it is in the same spirit that we pursue 
 the fluttering bird with our gun, or the panting 
 hare with our hounds — in pursuit of a barbarous 
 sport, and with no other end in view than the gra- 
 tification of vanity in the contemplation of our dex- 
 terity in hooking and torturing them. But inde- 
 pendently of all this, the organization of the fish 
 would lead us to the belief that its intellectual pow- 
 
OF REASON IN ANIMALS. 297 
 
 ers were of a very low degree ; indeed, the greater 
 part of their nervous energy would seem to be ex- 
 pended in furtherance of their respiratory and other 
 sympathetic and instinctive actions ; of the latter 
 they furnish many and remarkable examples, some 
 of which we have mentioned elsewhere. Doubt- 
 less the fish is considerably more an instinctive than 
 a rational animal, the chief end of whose being 
 would seem to be the devouring of food — it lives to 
 eat, not eats to live. But nevertheless we cannot 
 deny to it some glimmerings of thought, slight in- 
 deed, but not less than its organization would have 
 led us to expect. As examples of these we would 
 take the stratagems which many species practise in 
 the acquisition of their prey — concealing themselves 
 for instance, in the sand or mud to wait for it. This 
 is the practice of the sturgeon, of the European 
 Silure, the largest probably of European river fishes, 
 of the bearded star-gazer, of the hideous European 
 angler or sea-devil, and of several others ; the mouths 
 of most of these are furnished with slender vermi- 
 form appendages called cirrhi, which are made use 
 of by the animal as baits ; these swimming in the 
 water while the rest of the hsh is immersed in the 
 soil, are mistaken for worms by less intelligent fry, 
 which thus, like many human fools, in their at- 
 tempts to prey upon others, become themselves the 
 victims. It is not easy to believe that the beaked 
 chaetodon or shooting fish did not serve a long appren- 
 ticeship to the task before it could acquire its prey in 
 the manner it does with so much certainty and pre- 
 
298 OF REASON IN ANIMALS. 
 
 cision. It frequents the shores and mouths of tro- 
 pical rivers, and when it sees a fly at a distance 
 ahghted on any of the plants in shallow water it ap- 
 proaches very slowly, and with the utmost caution, 
 coming as much as possible peq)endicularly under 
 the object. Then putting its body in an oblique 
 direction, with the mouth and eyes near the surface, 
 it remains for a moment immoveable. Having 
 fixed its eyes directly on the insect, it shoots at it 
 a drop of water from its tubular snout, but without 
 shewing its mouth above the surface from whence 
 only the drop is seen to rise. This is done with so 
 much dexterity, that though at the distance of four, 
 five, or six feet, it very seldom fails to bring the 
 fly into the water. M. Hommel, the governor of 
 the hospital at Batavia, convinced himself of the 
 truth of this statement by causing some of these 
 fish to be placed in a large tank of water. They 
 soon became reconciled to the confinement ; and 
 he had the pleasure of seeing them daily exercising 
 their skill by shooting at flies and other insects 
 which were placed at all distances within the sphere 
 of their vision. They seldom missed their mark. 
 {Phil. Trans, vol. 53. p. 89, and 56. 186.) 
 
 Besides this, fishes are in a slight degree educa- 
 table, and in proportion as they are so they must 
 be considered rational ; at the same time it is to be 
 confessed that the result evinces more a desire to 
 obtain food than any thing intellectual. The eels 
 of the orator Hortensius came at his call, entranced, 
 it has been said, like bipeds, with the music of his 
 
OF REASON IN ANIMALS. 299 
 
 troice ; gold fish are easily taught to take food from 
 the hand ; the carp will obey the ringing of a bell j 
 and, it is curious to witness the uproar that takes 
 place in the fish-pond at Logan, in Galloway, the 
 moment the fisherman makes his appearance with 
 his daily store of limpets and other food for his fin- 
 ny charge. The whole surface seems agitated by 
 some vast internal commotion, as hundreds of fishes 
 rush from all corners to one common point where 
 they know they will receive their accustomed food, 
 and where they greedily contend with each other 
 for the delicious mouthful. They are intimately 
 acquainted with the person of their keeper and will 
 feed from his hand, distinguishing him firom the 
 numerous visitors who frequent the spot. One old 
 cod, for the pond is a salt water one and connected 
 with the sea, allows the fisherman to stroke his head 
 and even to lift him from the water. Thus it is seen 
 that these animals have at any rate acquired a con- 
 sciousness of security which cannot be ascribed to 
 any modification of mere instinct, which rather 
 prompt them to shun the deceitful protection of 
 man, a? it doubtless did when they were first placed 
 in the pond. But they have acquired knowledge 
 from experience, and such is the result. 
 
 The manifestations of reason among insects are 
 very considerable ; we shall allude to a few of them. 
 A certain degree of heat is necessary for the deve- 
 lopment and rearing of the eggs, larvae and pupae of 
 the ant ; and any one who will watch these animals 
 on a fine sunshiny day must observe the great la- 
 
300 OF REASON IN ANIMALS. 
 
 hour they undergo in removing their charge to such 
 places in the nest where the temperature is affected 
 by the sun's rays. Reaumur tells us the ants fre- 
 quently saved themselves all this trouble, by esta- 
 blishing their colonies between the exterior wooden 
 shutters and panes of his glass hives, where their 
 progeny was at all times, and without the necessity 
 of changing their situation, in a constant, equable, 
 and sufficient temperature. {Reaum. v. 709-) 
 Bonnet observed the same fact, {CEtivres, ii. 416) ; 
 and during the last summer we discovered a nest 
 of ants in a hot bed in our garden, under a piece 
 of slate placed there to protect a cucumber from 
 the soil. This we frequently lifted ; and whether 
 the day was hot or cold, sunshiny or the contrary, 
 the eggs were always in the same place. When 
 disturbed the ants ran away with them, as in Bon- 
 net's example, but always replaced them. On con- 
 sidering the above, the reader must agree with 
 Kirby and Spence in their remarks on the observa- 
 tions of Reaumur and Bonnet, that it is impossible 
 to refer these facts to instinct, or to accoimt for 
 them without supposing some stray ant, that had 
 insinuated herself into their tropi(!al crevice, first 
 to have been struck with the thought of what a 
 prodigious saving of labour and anxiety would ac- 
 crue to her compatriots by establishing their society 
 here ; — that she had communicated her ideas to 
 them ; — and that they had resolved upon an emi- 
 gration to this new-discovered country, whose geni- 
 al clime presented advantages which no other situa- 
 
OF REASON IN ANIMALS. 301 
 
 tion could offer. Neither instinct, nor any conceiv- 
 able modification of instinct, could have taught the 
 ants to avail themselves of a good fortune, which, 
 but for the invention of glass hives, would never 
 have offered itself to a generation of these insects 
 since the creation ; for there is nothing analogous 
 in nature to the constant and equable warmth of 
 such a situation, the heat of any accidental mass of 
 fermenting materials coon ceasing, and no heat be- 
 ing given out from a society of bees when lodged in 
 a hollow tree, their natural residence. The con- 
 clusion, then, continue these writers, seems irresis- 
 tible, that reason must have been their guide. \En- 
 tomology^ ii. 519.) Haller gives many examples 
 of bees, having failed by one method in accomplish- 
 ing a purpose, adopting another, a great manifesta- 
 tion of reason. 
 
 Perhaps some apology is due to the reader for 
 troubling him with so many anecdotes, especially 
 since the possession of reason by animals is pretty 
 well established, and the object of this work more 
 to endeavour to shew the conditions on which they 
 become endowed with it ; at any rate, the reader 
 will allow that the cases we have quoted require no 
 further comment, proving as they do the possession 
 by the lower animals, not only of deliberate reason- 
 ing powers, enabling them at once to co-operate to- 
 gether in the same cause, and to change their mea- 
 sures according to circumstances, and Hope, Fear, 
 Affection, Dislike, and other similar emotions, but 
 also of a sense of justice, and a hatred of oppression, 
 
302 OF REASON IN ANIMALS. 
 
 which are justly considered among the higher sen-^ 
 timents, and which, together witli the passions and 
 intellectual iiiculties before alluded to, make up 
 the full compliment of thought. Who also will de- 
 ny to the jackdaw and ape a propensity to acquisi- 
 tion, to the pigeon and panther vanity, or to most 
 birds and quadrupeds a love of music ; and who can 
 consistently concede to them these modifications 
 of the faculty of thinking, and still deny that they 
 exercise the faculty of thought ? But it is, perhaps, 
 chiefly in their susceptibility of artificial education 
 that the inferior animals manifest this function ; and 
 who has not seen artificially educated horses, dogs, 
 lions, pigs, elephants, bears, monkeys, Canary birds, 
 even fleas ? Cormorants and pelicans have been 
 taught to exercise their skill in fishing for the bene- 
 fit of mankind ; and the Bengal sparrow to collect 
 trinkets and bring them to its master ; and there 
 are few who have not heard the voice of the bull- 
 finch, which has been taught to pipe to the chamber 
 organ ; the starling whistling very elaborate tunes ; 
 and, the speech of the parrot or magpie, which has 
 been trained to imitate the articulation of man. 
 Now, in as far as any animal is capable of profiting 
 by experience, whether spontaneously or for force 
 submitted to, in other words in as far as it is edu- 
 catable — if we may use the expression — it appears to 
 us that it is intellectual. Of all animals man is the 
 most improveable. He is not only individually the 
 most capable of advancing from what he can do, to 
 what he cannot, from what he does know to what 
 
OF REASON IN ANIMALS. 303 
 
 he does not ; but, having the means also of leaving 
 behind him records of his attainments, so that his 
 successors may begin where he leaves off, his race 
 is susceptible likewise of progressive civilization. 
 And it is chiefly, perhaps, in the last particular that 
 he rises so infinitely superior to the lower animals ; 
 which, being not only individually less improveable, 
 but totally incapable of leaving behind them any 
 such records, the attainments of each generation 
 necessarily die with it, and the race, therefore, re- 
 mains in statu quo. 
 
( 304 ) 
 
 CHAPTER XII. 
 
 THE SEAT OF THOUGHT. 
 
 The Faculty of Thinkingis pretty certainly seated 
 in the brain. " In order to have a just idea of 
 thought," says Cabanis, " it is proper to consider the 
 brain as an organ specifically adapted to produce 
 it, in the same way as the stomach and intestines 
 are adapted to produce digestion. The impressions 
 derived from the senses, upon arriving at the brain, 
 make it enter into action, precisely as the aliments 
 do with respect to the stomach, upon arriving at 
 that organ." It is this organ which thinks and wills, 
 and which is the seat also of the sentiments and the 
 affections ; the number and extent of the mental 
 operations bearing an exact relation, in all animals, 
 to the relative size and complexity of this brain, and 
 the general development of these in early life, their 
 stationary condition in middle age, and their pro- 
 gressive decay as old age advances — their energy 
 during health and their failure in disease — all cor- 
 responds with the state of the brain under these 
 several circumstances. Accordingly in the coral- 
 lines, which manifest no marks of thought, there is 
 no appearance whatever of a brain, and its existence 
 is somewhat problematical also in most molluscous 
 
THE SEAT OF THOUGHT. 305 
 
 and testaceous animals ; whereas in other molluscous 
 animals and in many insects, which frequently be- 
 tray very striking indications of this function, the 
 existence of what may be conceived to represent a 
 brain, is much less equivocal than in the other tribes 
 of avertebrate animals. How infinitely superior 
 are the habits of the ant, the spider, and the bee, 
 to those of the polype, the earthworm and the oys- 
 ter — yet they are not more so than the more volumi- 
 nous and complicated structure of the nervous sys- 
 tem of the former is calculated to explain ; and as 
 we rise higher in the scale of creation, it becomes 
 still more obvious how intimately an increasing 
 magnitude and multiplicity of this organ are con- 
 nected with more numerous and decided manifesta- 
 tions of mind. Thus it becomes, generally speak- 
 ing, larger and larger, and composed of more and 
 more parts as we rise progressively through fishes, 
 reptiles, birds, and the various tribes of mammals 
 up to man ; bearing an average proportion to the 
 spinal chord, in the first of about two to one, in the 
 second about two and a half, in the third about 
 three, in quadrupeds about four, and in man of not 
 less than about twenty-three ; and the degree of 
 intellectual superiority, in each case, to the one pre- 
 ceding may be said to correspond almost entirely 
 with this advancement in the size and structure of 
 the brain. The immediate dependence, indeed, of 
 intellect upon the brain has been pretty generally 
 admitted ever since the age of mythology, which 
 represented Minerva the godfV.rr. .f wUv jiii, as is- 
 
306 THE SEAT OF THOUGHT. 
 
 suing ready-armed from the head of Jupiter ; and 
 the same fact is continually inculcated by our fami- 
 liar expressions of long-headed, furnished with 
 plenty of brain and so forth, as applied to an intel- 
 ligent person, and thick-headed, addle-pated, num- 
 skull, &c., as applied to a fool. But with respect to 
 the immediate seat of the affections there has been 
 much less unanimity. By most of the ancient writ- 
 ers these were referred either to the viscera of the 
 chest or belly, or to the chest and belly themselves ; 
 and accordingly the words breast and heart are used 
 in almost every page of the oldest book in the 
 world, to signify the affections, and a similar mean- 
 ing is frequently attached to the Mords belly, bow- 
 els, liver, and reins or kidneys. Job talks of man's 
 belly preparing deceit, and, to describe his afflic- 
 tion, says, that his bowels boiled and rested not ; 
 Isaiah uses the phrase sounding of the bowels to 
 signify pity ; Jeremiah, to represent his suffering, 
 says that his liver is poured out ; and David fre- 
 quently speaks of his loins as synonymous with his 
 desires. In the earlier profane writers also, the 
 same impression is manifest in their continual use 
 of the words breast, heart, midriff, bowels, and so 
 forth, to signify the affections, and the term big-gutted 
 was not unfrequently applied by them to persons of 
 strong passions, as if there were a direct connection 
 between the strength of the passions and the size 
 of the viscera. By Hippocrates and Plato also, 
 while reason was placed in the brain, passion was 
 explicitly stated to reside in the heart and midriff; 
 
THE SEAT OF THOUGHT. 307 
 
 and Galen, while he also placed the animal spirits, 
 including reason, in the brain, referred the vital and 
 natural spirits, including, the one the irascible, and 
 the other the concupiscent passions, respectively to 
 the heart and the liver; and it is as influenced by 
 these old notions that we still so universally use 
 the words hearty, heartless, a stomach for any thing, 
 a yearning of the bowels, hot-livered, white-livered, 
 choleric, &c., as emblematic of the passions, and 
 that players constantly place their hands upon their 
 chest when they wish to indicate deep emotion. 
 Nor are these notions supported only by ancient 
 prejudices; not a few modern authors of repute, in- 
 cluding Borden, BufFon, Bichat, Cabanis, Reil, and 
 Broussais, having expressly adopted them. " The 
 passions,'' says Broussais, " are the triumph of the 
 viscera over intelligence." But, if the affections 
 and passions consist merely in perturbations to a 
 greater or less degree of the thoughts, it is obvious 
 that they can no more have a seat distinct from that 
 of thought, than a palpitation of the heart can have 
 a seat distinct from that of the healthy action of 
 that organ ; and they are, consequently, like the 
 intellect, energetic in all animals in proportion to the 
 size, not of the viscera of the chest and belly, but of 
 the brain. Thus it is only in the superior tribes of 
 animals — those in which the brain is well developed 
 — that we meet with evident indications of hope, 
 fear, love, hatred, courage, ambition, jealousy, joy, 
 and grief. " Passion,'"' says Bonnet, " has always 
 an object ; one does not desire what one does not 
 
308 THE SEAT OP THOUGHT. 
 
 know. Passion, then, has its beginning in volition : 
 it is Will applied strongly to its object.** It is the 
 brain, then, which is always affected the first, and 
 from which the manifestations of the passions ex- 
 tend by sympathy to the other viscera. If, on the 
 contrary, the passions had their primary seat in the 
 viscera of the chest and belly, they should be nu- 
 merous and violent — as was formerly, but very er- 
 roneously, supposed to be the case, — in proportion 
 to the magnitude and complexity of these viscera ; 
 but some of these, for example the liver, are rela- 
 tively the most voluminous in those animals which 
 betray few or no indications of passion. The herbi- 
 vorous animals also, among the higher orders, have 
 in general larger and more complicated viscera 
 than the carnivorous ; but has the peaceful cow, 
 with its four stomachs, long intestines, and volumi- 
 nous liver, more energetic passions than the savage 
 tiger, in which all these organs are comparatively 
 small and simple ? Among mankind also, those in- 
 dividuals who live, as it were, under the dominion 
 of the belly, have, in general, enormous viscera, but 
 they are comparatively destitute — not, indeed, of 
 appetites — but of affections and passions ; while, on 
 the other hand, those who exercise rather the func- 
 tions of the brain are commonly disting\iished by 
 the acuteness and intensity of their feelings, and 
 generally display, instead " of the fair round belly," 
 rather the appearance of the " lean and slippered 
 pantaloon.*' The viscera, then, of the chest and 
 belly, however rapidly and powerfully they may dis- 
 
THE SEAT OF THOUGHT. 309 
 
 play the effects of the affections and passions, can- 
 not be the immediate seat of them ; nor can such 
 emotions have any other seat than that of thought, 
 of which they are only a modification. But neither 
 reason nor passion is essential to hfe, — therefore 
 many of the lower animals have naturally no brain, 
 and it may be sometimes artificially abstracted from 
 animals, naturally possessed of it, without fatal ef- 
 fects. Thus we learn from the experiments of Redi 
 that the land -tortoise can live six months after ha- 
 ving been deprived of its brain ; and fi'om those of 
 Spallanzani, that the newt and frog can do almost 
 as well without a brain as with one. In the human 
 being also, as thought is the last function of the ner- 
 vous system which comes into exercise, so the brain 
 is the last part of this system which is perfected ; 
 and as thought is less requisite to the well-being of 
 the embryo and fetus than either irritation or sensa- 
 tion, so, while no mature fetus has ever been born 
 without a ganglionic system of nerves, and extreme- 
 ly few without a spinal chord, innumerable instances 
 are on record of such fetuses having been born 
 without a brain. It is the most sublime, but, at the 
 same time, the least essential part of the nervous 
 system ; and, like the third story of an edifice, while 
 it relies for support on the one immediately below 
 it, as this again relies upon the foundation of them 
 all, may itself be deficient, without prejudice to those 
 on which, when present, it is either directly or indi- 
 rectly dependent. 
 
310 THE SEAT OF THOUGHT. 
 
 In conclusion, we trust we may be allowed to ex- 
 press a hope, that we have rendered p obable the 
 positions with which we started, that the sources of 
 the organic, the instinctive, and the rational motions, 
 are all distinct from each other, an essential condi- 
 tion of the first being irritability, of the second sen- 
 sibihty, and of the third the faculty of thinking ; that 
 each of these faculties, as it is different in its nature, 
 so it has also a distinct seat from the rest; and that, 
 while to those animals which posse^-.s only a gangli- 
 onic system of nerves we allow only organic mo- 
 tions, and to those which display, besides this, a 
 spinal chord, only organic and instinctive motions, 
 we must concede to such as have at once a gangli- 
 onic system, a spinal chord and a brain, — which is 
 the case with by far the greater number of animals 
 — not only organic and instinctive motions, but ra- 
 tional motions also. Nor needs man to feel humi- 
 liated by an admission which still leaves all created 
 beings at so immeasurable a distance from him even 
 in this state of existence, if not in the kind, at least 
 in the degree, of their faculties ; and which further 
 reserves to him, by the especial favour of his Crea- 
 tor, a distinction infinitely more excellent in the 
 prospect of immortality. 
 
( 311 ) 
 
 ILLUSTRATIONS. 
 
 PLATE I. 
 
 Fig. 1. (Paxfon.) Left side of the brain and spinal chord, 
 shewn by making a section of the cranium and spinal 
 marrow. 
 
 a, The cerebrum ; 
 
 b, The cerebellum ; 
 
 c, The medulla oblongata; 
 
 d, The spinal chord, extending from the first cervical ver- 
 
 tebra, and terminating at 
 
 e, The cauda equina. 
 
 Fig. 2. Posterior view of the nervous centre, with the origin 
 of the spinal nerves. 
 
 PLATE II. 
 
 Fig. 1. (Paxton) Base of the brain, with medulla oblongata, 
 
 a, Anterior lobes ; 
 
 6, Middle lobes ; 
 
 c, Corpora albicantia; 
 
 d, Pons Varolii ; 
 
 e, Superior vermiform process ; 
 y, Cerebellum ; 
 
 ^, Inferior vermiform process; 
 * A, Medulla oblongata — the letter being placed on the cor- 
 pora pyramidalia; 
 t, Corpora olivaria; 
 A, Posterior lobes; 
 n, Pituitary stem. 
 
 « In the text this letter is inadvertently said to be placed on the cofo 
 pora olivaria. 
 
■ U'i ILLUSTRATIONS. 
 
 Fig. 2. (Paxton.) Horizontal section of the cerebrum. 
 n, a, Anterior cornua of the lateral ventricles ; 
 
 b, b. Posterior cornua ; 
 
 c, c. Corpora striata ; 
 
 f] (I, Septum lucidum, extending between the two letters ; 
 (/f y, Choroid plexus — a tissue of bloodvessels. 
 
 PLATE III. 
 
 Fig. 1. {Paxton.) Horizontal section of the cerebrum, with 
 oblique division of the cerebellum. 
 
 a, Anterior part of the corpus callosum ; 
 
 b, Corpus striatum ; 
 
 c, Optic thalamus; 
 
 d, Taenia semicircularis ; 
 
 e, Anterior pillars of fornix, cut off at their base ; 
 /, Commissure of the optic thalami ; 
 
 ff, Pineal gland, situated on four eminences termed the 
 
 corpora quadrigemina ; 
 h, Valve of Vieussens ; 
 
 A, Arbor vitae, shewn by an oblique section of 
 71, The cerebellum ; 
 /, Fourth ventricle, terminating in 
 m, The calamus scriptorius. 
 Fig. 2. (^PaxtonS) Transverse section of the brain, upon a 
 level with the corpus callosum. 
 a, u, a, Corticular part of the convolutions, with the fissures 
 
 between them ; 
 h, b, The medullary part, forming the centrum ovale ; 
 (T, The corpus callosum. 
 
 PLATE IV. 
 
 Fig. !• (^Milne- Edwards.^ Encephalic nerves. 
 
 A, Anterior lobe of the brain ; 
 
 B, Middle lobe ; 
 
 C, Posterior lobe ; 
 
 D, Cerebellum ; 
 
 £, Medulla oblongata ; 
 
ILLUSTRATIONS. 313 
 
 /, Divided corpus callosum ; 
 
 1, First pair, or olfactory nerves ; 
 
 2, Second or optic ; 
 
 3, Third, or motores oculorum ; 
 
 4, Fourth, or pathetic ; 
 
 5, Fifth, or trigeminus ; 6 a, ophthalmic branch ; 6, su- 
 
 perior maxillary branch ; 5 6, inferior maxillary 
 branch ; 
 
 6, Sixth pair ; 
 
 7, Seventh pair, divided into two portions, the auditory, 
 
 or portio mollis, and ^cmZ, or portio dura; 
 10, The par vagum, a portion of the eighth pair ; 
 12, The accessory nerve of Willis, a second portion of the 
 
 eighth pair ; 
 9, The glosso-pharyngeal, a third portion of the eighth 
 
 pair ; 
 11, Ninth pair, or lingual. 
 Fig. 2. (^HandysideJ) Distribution of the fifth pair of nerve* 
 on the left side. 
 
 A, Superior maxillary bone ; 
 
 B, Inferior maxillary bone ; 
 
 C, Nasal bone ; 
 
 D, Section of frontal bone ; 
 
 E, Portion of malar bone ; 
 
 F, Eyeball, with entrance into it of the optic nerve ; 
 
 G, Floor of the orbit ; 
 H, Tongue ; 
 
 I, I, Section of pons Varolii ; 
 K, L, Trunks of the fifth pair, as they pass from their origin 
 through the pons Varolii. K, small anterior or mo- 
 tive root ; L, large posterior, or sensitive root. 
 M, Gasserian ganglion, concealing from view the continu- 
 ation of K, as that root lies to the inner side of the 
 ganglion, on its way to I, I, I. 
 First, or ophthalmic division of the fifth pair. 
 X 
 
314 ILLUSTRATIONS. 
 
 1,1, Recurrent branches, passing between the layers of the 
 tentorium. 
 
 2, Lacrymal nerve ; 
 
 a, Its external branches, 
 
 b, Its internal branches. 
 
 3, Frontal nerve ; 
 
 c, Supra-trochlear nerve. 
 
 4, Nasal nerve ; 
 
 0, Large root of 
 
 r, Ophthalmic ganglion, connected with the sense 
 
 of sight by 
 y, Long and short ciliary nerves ; 
 s, Ethmoidal nerve ; 
 
 t, Its lateral nasal branch ; 
 V, Infra-trochlear nerve. 
 
 Second, or superior maxillary division. 
 1, 1, I, Orbital nerve ; 
 
 a, Subcutaneous malae ; 
 6, Temporal nerve. 
 
 2, Spheno.palatine nerves ; 
 
 c, Greater palatine, giving branches to the nostrils ; 
 
 d, Lesser palatine ;_ 
 
 2, Spheno-palatine ganglion, on the root of 2, and 
 connected by branches with the sense of smell. 
 
 3, Posterior dental (greater and lesser) ; 
 
 4, Anterior dental ; 
 o, Infra-orbital; 
 
 e, Inferior palpebral branches ; 
 /, Lateral nasal ; 
 
 g, Superior labial. 
 
 Third, or inferior maxillary division, 
 
 1,1,1, Lingual or gustatory nerve; 
 2, 2, Chorda tympani ; 
 
ILLUSTRATIONS. 315 
 
 3, Submaxillary nerve, on which is 
 * Submaxillary ganglion, with its branches to the sub- 
 maxillary gland connected with the sense of taste. 
 
 4, 4, Inferior dental nerve ; 
 
 5, 5, Mental nerve ; 
 
 16, Inferior labial branches. 
 
 6, 6, Deep temporal nerves (anterior and posterior) ; 
 
 7, Buccal nerve ; 
 
 8, Pterygoid nerves (external and internal) ; 
 
 9, Masseteric nerve ; 
 
 10, Superficial temporal (or auricularis anterior) ; 
 
 11, Mylo-hyoid and digastric branches ; 
 
 t Otic ganglion. Its situation on the inner side of the 
 sensitive root of I, I, I, is marked by a dotted line. 
 It is connected by its branches with the sense of 
 hearing. 
 
 PLATE V. 
 Fiti. 1. Ganglia. 
 
 Fig. 2. (Paxton.^ Some of the principal nervous ganglia and 
 plexuses of the thorax and abdomen, with the pneu- 
 mogastric nerve, 
 a, a, Thoracic ganglia ; 
 6, The pneumo-gastric nerve ; 
 
 c, A branch of the former, called the inferior laryngeal or 
 
 recurrent, curving round the arch of the aorta ; 
 
 d, iEsophageal plexus ; 
 ?, Pericardium ; 
 
 /, Lungs ; 
 
 r. Pulmonary plexus ; 
 
 g, Diaphragm ; 
 
 A, Spleen ; 
 
 /, Stomach ; 
 
 The two last named organs are turned ai^ide to 
 shew the distribution of the nerves. 
 k. Kidney ; 
 /. Abdominal aorta ; 
 
316 ILLUSTKATIONS. 
 
 m, Semilunar ganglion, and solar plexus, the latter radia- 
 ting to all the divisions of the aorta ; 
 n, Splenic plexus ; 
 0, Pancreas ; 
 P,p,p, Lumhnr ganglia ; 
 ry, Obturator nerve. 
 
 PLATE VI. 
 Fig. 1. (^Grant.^ Nervous system in the Beroe pileus. 
 
 ... 2 Star-fish. 
 
 ... 3. ... Ascaris, or intestinal 
 
 worm. 
 
 ... 4. ... Earth-worm. 
 
 ... b. {Herold.) larva of Cabbage Butterfly. 
 
 ... 6. ... pupa 
 
 ... 7. ... imago 
 
 PLATE VII. 
 Fig. 1. (^Treviranui and Muller.) Motor tract in Scorpion. 
 ... 2. (^Andojiin.) Nervous system in Sandhopper. 
 
 ... 3. (^Edwards.) Cyinothea. 
 
 ... 4. (^Succow.) Lobster. 
 
 ... 5. {^Grant.) Maia. 
 
 PLATE VIII. 
 Fig. \. (Grard.) Nervous system in common Mussel. 
 ... 2. {Chlaji.) Argonauta. 
 
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