UNIVERSITY OF CALIFORNIA AT LOS ANGELES GIFT OF CAPT. AND MRS. PAUL MCBRIDE PERIGORD 6 r > ', i UNIVERSITY of CALIFOBMA AT LOS ANGELES LIBRARY THE PHYSIOLOGY OF MIND. THE PHYSIOLOGY OF MIND. BEING THE FIRST PART OF A THIRD EDITION', REVISED, ENLARGED, AND IN GREAT PART REWRITTEN^ OF " THE PHYSIOLOGY AND PATHOLOGY OF MIND." BY HENRY MAUDSLEY, M.D. NEW YORK: D. APPLETON AND COMPANY, 1, 8. AND 6 BOND STREET. 1887. 1381(5;) UV*nrY -3F /&,< m4 mi PREFACE. THE first edition of my work on the Physiology and PatJiology of Mind was published in the year 1867. A second edition appeared in the following year, which was in due time exhausted, and the book has been out of print for some years. The T3 delay in the publication of a third edition has been owing mainly to the occupations of active profes- sional life, which have hindered the bestowal of the systematic work of revision and enlargement made necessary by the progress of physiological and psychological knowledge ; but partly also to a lack of enthusiasm in the labour, arising from a conviction that what was of value in the book had r-\ either been said already, or would anyhow very soon be said, by some one else. The current of psychological thought having set so strongly in physiological channels, it is pretty certain that the reflections which one person has had, however original they may seem to him, some other person has had, has now, or will very soon have. One is happily, too, more critical, as well as less enthusiastic vi PltEFACE. and confident, at forty than at thirty years of age ; and a result of the more sober mood is that what seemed very important, and much needing to be said, at the earlier date, does not seem of so much consequence, or anywise to press for delivery, at the later date. There was another inhibitory reflection, occa- sioned by a contemplation of the revolution in psychological method, which has been going on for some time now, and of the entirely different aspects which many psychological questions have assumed in consequence. The changes that have taken place have been so great and so rapid that a book written ten years ago must necessarily, unless re -written, be much out of date now. In the preface to the first edition, the aim of the work was declared to be twofold : " first, to treat of mental phenomena from a physiological rather than from a metaphysical point of view ; and, secondly, to bring the manifold instructive in- stances presented by the unsound mind to bear upon the interpretation of the obscure problems of mental science to do what I could to put a happy end to the 'inauspicious divorce' between the Physiology and Pathology of Mind!" The way in which the fulfilment of the first part of this twofold aim was prosecuted did not fail to provoke much criticism, of the direct and indirect sort, from those who assumed that it was a reck- PREFACE. vfi less attempt to discard entirely the psychological method of inquiry into mental phenomena, and to employ the physiological method exclusively. No doubt the energetic exposition of the shortcomings of the psychological method and the earnest ad- vocacy of the physiological method lent some countenance to that supposition, but it was none the less directly contrary to the distinct enunciation of that which was advocated in the first chapter as the proper method of the study of mind, and with the method actually pursued in the execution of the work throughout. It was not possible to set forth adequately the fruitfulness and the rich promise of the physiological method, and to elevate it to its rightful position, without exposing the shortcomings of the psychological method, and degrading it to a lower rank than that which it had usurped. The physiological method has made such great way that it stands not now in need either of de- fence or advocacy ; and the result cannot fail to be, as regards this book, that the exposition of its merits, made with all the vehemence of youthful enthusiasm, must look like a superfluous assertion of claims which are not seriously contested, while the record of acquisitions which have become part of the general body of thought certainly requires not the aggressive prominence which it had. To adapt this edition in some measure to these fiii PREFACE. new conditions, I have, while incorporating the entire substance of previous editions, omitted or modified various expressions and passages which seemed objectionable as they stood, and have sought to maintain the level of a more sober style ; and, in order to bring it even with the present state of knowledge, the original matter has been carefully revised and largely added to. The con- sequence has been that what was the First Part of former editions, treating of the Physiology of Mind, and had been written in the first instance in order to lay a foundation for the Second Part, which dealt with the Pathology of Mind, has grown so much, and attained by its growth such an independent character, as to render it advisable to make it a separate volume. This volume is, then, presented as a treatise on the physiology of mind, and may stand on its own account as such, quite apart from the second volume which, following in due season, will be occupied entirely with the pathology of mind, and with the accomplishment of the second part of the twofold aim. Or, if it be thought too ambitious a thing to call it a treatise, let it be looked upon as a disquisition, by the light of existing knowledge, concerning the nervous structures and functions which are the probable physical foundations, or the objective aspects, of those natural phenomena which appear in consciousness as feelings and IREFACE. ix thoughts, and are known only in that way that is to say, subjectively. Should any one choose to declare that the book is neither Physiology nor Psychology, but an ill-conceived medley, and be offended at what is offered to him, I am not careful to answer in that matter ; I am more wishful, in my unwisdom, that it should be in conformity with nature than with the divisions of sciences which he and those who think with him labour to impose upon nature by way of amend- ment upon its continuity and unity. It may not be amiss perhaps to caution the reader that he allow not the book to obtain by implication, either from physiology or from psychology, more authority than it is fairly entitled to ; I desire only that it may stand on its own bottom as an exposition of the aspects, be they right or wrong, in which the author's study and reflection have led him to view the matters which are discussed in its pages. CONTENTS. CHAPTER I. ON THE METHOD OF THE STUDY OF MIND. Aspects of nature terrible to man in the infancy of thought ; whence superstitious feelings and fancies regarding nature. As these disappear metaphysical entities are assigned as natural causes, and man deems himself the " measure of the universe." Finally, the interrogation and interpretation of nature, after the inductive method, begin ; fruitful results of this method. Its adoption was the extension to the intellect of the law of internal adaptation to external relations. Any proposition concerning the uncon- ditioned or absolute is nonsense. Is the inductive method, objectively applied, available for the study of Mind ? Difficulties in the way of such application. Development of biography, and absence of any progress in metaphysics, are evidences of its value. Discussion of the claim of Psychology to be inductive. Its method of interrogating self-consciousness palpably inade- quate ; contradictory results of its use, and impossibility of applying it inductively. Observation of animals, of children, of the lower races of men, and of insane persons has been entirely neglected. Self-consciousness unreliable in the information which it does give, and incompetent to give any account of a large part of mental activity : gives no account of the mental phenomena of the infant, of the uncultivated adult, and of the insane ; no account of the bodily conditions which underlie every mental manifestation ; no account of the large field of unconscious mental action exhibited, not only in the unconscious assimilation xii CONTENTS. of impressions, but in the registration of ideas and their associa- tions, in their latent existence and influence when not active, and in their recall into activity ; and no account of the influence organically exerted upon the brain by other organs of the body. Mind a consensus of affective, intellectual, and active functions, and the basis of the affective functions is in the organic life : mind a direct function of brain, but every organic function represented in the brain. Defects of psychological nomenclature. Incom- petency of self-consciousness further displayed by examination of its real nature ; its method to be dethroned, not discarded. Physiology cannot any longer be ignored ; henceforth necessary to associate the Physiological with the Psychological method ; the former being really the more important and fruitful method. The study of the plan of development of Mind, the study of it forms of degeneration in the insane and in criminals, the study of its progress and regress, as exhibited in history, and the study of biography, should not be neglected. The union of empirical and rational faculties, really advocated by Bacon as his method, is strictly applicable to the investigation of mental as of other natural phenomena. Development of mind in nature a process of organic evolution : unity and continuity in nature. The question of relative value of inductive or deductive reasoning often a question of the capacity of him who uses it ; difference between genius and mediocrity. Conclusion Notes. Page 176 CHAPTER II. MIND AND THE NERVOUS SYSTEM. The term " Mind " used in different senses : in its scientific sense, as a natural force ; and in its popular sense, as an abstraction made into a metaphysical entity. The brain certainly the organ of the M ind ? and the nervous cells the immediate agents of mental function. A correlative change in nerve element accompanies each mental state ; chemical composition of nerve element being extremely complex and unstable. Mental power an organized result in the proper centres a mental organization. No nerve in lowest animal forms ; perception of stimulus being the direct physical effect in a homogeneous substance. The differentiation CONTENTS. xiii of tissues in higher animals demands special means of intercom- munication : the nervous system, at first very simple, subserving this function. With increasing complexity of organization, a corresponding complexity of the nervous system. Organs of special senses appear, in very rudimentary form at first, by differ- entiation of the general sense of touch ; corresponding central nervous ganglia constitute entire brain in Invertebrata. Sensori- motor function. Discriminations of organic susceptibility or sensibility. Relation of consciousness to sensibility. Rudiments of cerebral hemispheres and rudimentary ideation and emotion in fishes. Convolution of the grey matter of the hemispheres in the higher mammals, and corresponding increase of intelligence in them. Differences in the sjze of the brain, and in the complexity of its convolutions, in different races of men, and in different in- dividuals of the same race ; corresponding differences in intel- lectual development. Human embryonic development conforms with general plan of development of Vertebrata. Discrimina- tion of nervous centres : (a) primary, or Ideational ; (b) secondary, or Sensorial ; (c ) tertiary, or Reflex ; (d) quaternary, or Organic. The evidence of the different functions of these centres is ana- tomical, physiological, experimental, and pathological. Lock- hart Clarke on the structure of the convolutions in man. Discriminating observation of mental phenomena necessary, and metaphysical conception of Mind no longer tenable. Definitions of mind. Mind never met with apart from brain. Differences of matter in dignity and corresponding modes of force. Mind the most dependent of all the natural forces ; relations of mental force in nature. Concluding remarks. Notes. Page 77 135 CHAPTER III. THE SPINAL CORD AND REFLEX ACTION. Spinal cord not a conducting organ only, but contains nervous centres of reflex or automatic movements. Earliest movements of infant are reflex. Illustrations of reflex movements in the decapitated frog. Pfliiger's experiments on the frog, and dis- cussion of the theory that the spinal cord has sensorial functions. So-called design of an act not necessarily evidence of will or CONTENTS. consciousness. Examples of inhibitory function. The nature of the idea of design. Spinal cord is educated, and becomes the centre of many acquired or secondary automatic movements ; illustrations. The motor faculties mostly acquired in man by education and exercise, but innate in many animals. Hearing of instances of acquired adaptation of means to end on the doctrine of final causes. Motor faculties are exhausted by exercise, and require periodical rest for restoration of power by nutrition. Quantitative and qualitative relation of reaction to the impression. Innate potentiality of nerve-element, and ac- quired potentiality. Hereditary transmission of acquired faculties implants the germ of innate endowment. Continuous function of spinal cord : it acts (a) on muscles ; (b) on vessels : (f) on elements of a tissue ; (d) on other nerve-centres. Pfluger's laws of reflex movements. Causes of disorder of function of spinal cord : (a) original differences of constitution ; (t>) excessive action ; (c) quantity and quality of the blood ; (d) eccentric irritation ; () on the sensory ganglia, physiologically, CONTENTS. as a regular part of mental function ; pathologically, in the pro- duction of hallucinations ; (c) on the functions of nutrition and secretion : illustrations ; (it) on other ideas : reflection or delibera- tion. Relation of consciousness to Ideational activity. Com- parison of ideas with movements in regard to their association, their relation to consciousness, the time required for their per- formance, and the limited power which the mind* has over them. The nature and influence of attention : voluntary and involuntary attention. Motor innervation an essential factor in attention. The physical conditions of an act of attention. Localization of consciousness in the brain. The character of the particular association of Ideas determined by (a) the individual nature, (b) special life-experience. General laws of association of ideas. Fundamental or innate ideas. The uniformity of nature. Acquisition of ideas through the accumulated experiences of the race and of the individual. The individual's particular associa- tion of ideas need of an individual psychology. Concluding remarks on the illustration of the law of progress from the general to the special in development, afforded by the develop- ment of ideas. Notes. Fa$e 259347 CHAPTER VI. ON EMOTIONS OR AFFECTIONS OF MIXD. Relation of emotion to idea. Emotions are based in the organic life. Influence of state of nerve-element upon emotion. Idea favourable to self-expansion is agreeable ; an idea opposed to self-expansion is disagreeable or painful. Appetite or desire for agreeable stimulus, and repulsion to or avoidance of painful stimulus, as nwtives of action. Desire is self-conscious appetite. The operation of the sexual appetite. Equilibrium between individual and his surroundings not accompanied with desire. Desires furnish the impulses to action ; the function of the intel- lect is regulative. Character of the emotion determined by the nature of external stimulus, and by the condition of the nerve- element, original and acquired. Original nature as determined by (a) the race ; (6) the culture of the epoch ; (c) ancestral qualities ; (if) bodily temperament. The coencesthesis. The mental or psychical tone. The complex nature of emotional CONTENTS. xvii aptitudes, and their resolution or retrograde metamorphosis. Effects of organic viscera upon the emotions ; such effects are complex and non-intermittent, and cannot be s'udied by the subjective method. Influence of condition of blood upon the emotional tone. The expressions of the emotions : (a) in muscular movements ; (6) in changes of nutrition and secretion ; (c) in ideational activity. Action of disordered emotion. Emotions and passions. The evolution in the mental life of the fundamental instincts of self-preservation and propagation. The moral feeling its origin and development. The moral law and the law of natural selection. The progress from the general and simple to the special and complex, in the evolution of the emotions. Notes Page $$ 408 CHAPTER VIL ON VOLITION. Will, like every other natural force, has a cause. Free-will or necessity : discussion of question. The reason and utility of the doctrine of free-will. The will not a single, undecomposable faculty of uniform power, but varies as its cause varies : differs in quantity and quality, according to the preceding reflection. According to the common view of it, an abstraction is made into a metaphysical entity. The design in the particular volition is a result of a gradually effected mental organization : a physical necessity, not transcending or anticipating, but conforming with, experience. Erroneous notions as to the autocratic power of will. Its actual power considered (i) over movements, and (2) over the mental operations. I. Over movements : (a) no power over the involuntary movements essential to life ; (b) no power to effect voluntary movements until they have been acquired by praciice ; (c) cannot control the means, can only will the event. 2. Over mental operations : (a) the formation of ideas and of their associations independent of it ; (b) its impotency in the early stages of mental development in the young child and in the savage ; (c) cannot call up a particular train of thought, or dismiss a train of thought, except through associations of ideas which are beyond its control, and sometimes not at all. As many centres of volitional reaction in the brain as there are centres of CONTENTS. ideas. Volition built up from residua of previous volitijns of a like kind. Volitional control is an instance of inhibitory function in the highest nerve-centres. To the freest action ot the will there are necessary an unimpeded association of ideas and a strong personality. Character not determined by the will, but determining it in the particular act. Relation of emotion to volition. Character determines belief as well as conduct. Modi- fication of character. The history of a man declares his character. Differences in the quality and energy of the will. The character of the reformer, and the conditions of a successful reform. Ex- tensive and intensive reformers. Will the highest force in nature ; its highest function creative initiating a new development of nature. Notes. I age 409 462 CHAPTER VIII. ON ACTUATION. Movement follows sensation. Movements leave behind them residua in the motor centres, whence a repository of latent or abstract movements. Motorium commune. Motor residua or intuitions intervene between motive and act, and are related to conception on the reactive side as sensation is on the receptive side. Actua- tion proposed for the psychological designation of this depart- ment. Motor intuitions mostly innate in animals, acquired in man. Illustrations from vision, speech, the phenomena of hypno- tism, paralysis, insanity, &c. The effects of bodily attitudes upon mental states. The acquisition of speech. Aphasia : the pathological conditions of its phenomena, and their signification in relation to motor intuitions. Condilion of intelligence in aphasia. Thought possible without verbal language. Motor hallucinations. Co-ordinate convulsions. The muscular sense : its relation to the motor intuitions, and the essential part which it plays in mental function. Morbid disorder of the muscular sense. The will acts upon muscles indirectly through the motor nervous centres. Orderly subordination of nervous centres in the expression of the will in act on. Natural differences between different persons in the power of expression by speech or other- wise. The origin, nature, and development of language. Notes. Past 463 511 CONTENTS. CHAPTER IX. ON MEMORY AND IMAGINATION. Definition and organic condition of memory. Memory exists in every organic element of the body an organic registration of im- pressions. Conception of a mental organization necessary to an understanding of its phenomena. Relation of consciousness to memory. No memory of that which we have not had experi- ence of, and no experience ever entirely forgotten. Physiological ideas of assimilation and differentiation necessary to the interpre- tation of its formation. Memory and recollection. Conscious- ness of the possession of what we do not actually remember. Imagination : its nature and function. The conditions of its highest development. Relation of memory to imagination. Fancy. Power of imagination built up by the assimilation not only of the like in ideas, but also of the relations of ideas. The one-making faculty. Its productive or creative power is, in its highest display, involuntary and unconscious : it is the supreme manifestation of organic evolution. Differences in the character of memory in different persons. Manifold dis- orders to which memory is liable. The memory of early youth and of old age. No exact memory of pain : why? Notes Page 512 540 THE PHYSIOLOGY OF MIND CHAPTER I. ON THE METHOD OF THE STUDY OF MIND. '* Ich sag? es dir : em Kerl der speculirt, 1st wie ein Thier, auf diirrer Heide Von einem bosen Geist im Kreis herum gefiihrt, Und rings umher licgt schoue griine Weide." Faust. THE right estimate of his relations to external nature har ever been to man a matter of difficulty and uncertainty In the savage state of his infancy he feels himself sc little in the presence of nature's vastness, so helpless in conflict with its resistless forces, so overawed by the spec- tacle of its serenely inexorable course, that he falls down in abject prostration before its various powers The earth of a sudden heaves beneath his trembling feet and his shattered dwellings bury him in their ruins ; the swelling waters overpass their accustomed boundaries and indifferently sweep away his property or his life ; the furious hurricane ruthlessly destroys the labours of years; and famine or pestilence, regardless of his streaming eyes and piteous prayers, stalks in desolating march through a panic-stricken people. In the deep conscious- ness of his individual powerlessness he falls down in an 2 THE PHYSIOLOGY OF MIND. [CHAP. agony of terror and worships the causes of his sufferings : he deifies the powers of nature, builds altars to propitiate the angry Neptune, and, by offering sacrifices of that which is most dear to him, even his own flesh and blood, hopes to mitigate the fury of Phoebus Apollo and to stay the dreadful clang of his silver bow. When the army of the King of Assyria, coming np against Jerusalem to de- stroy it, is devastated by pestilence, it is the angel of the Lord which goes out in the night and smites in the camp of the Assyrians an hundred fourscore and five thousand, so that they are all dead corpses in the morning. In like manner, when any case of sudden death occurs now among the Bongos of Central Africa; it is some old woman- who has allied herself with the witches to do evil, for it is deemed certain that a strong man would not die unless he were bewitched.* Everything appears supernatural when man knows nothing of the natural; palsied with fear, he cannot observe and investigate; himself he feels to be insignificant and helpless, while to nature he looks up with awe-struck apprehension as mys- terious and almighty. Reflect on the fearful feelings which any apparent exception to the regular course of nature the appearance of a comet, the occurrence of an earthquake or of an eclipse even now produces in many uncultivated minds, on the superstitious dread which follows such unfamiliar event, and it will not be difficult to realize the extreme mental prostration of primitive mankind. Through familiarity, however, consternation after a while subsides, and the spirit of inquiry follows upon that of reverence; the prostrate being rises from his * Schweinfurth's Heart of Africa, vol. i. p. 310. When the North American chief Picheto was one night much alarmed by the violence of the storm, lie got up and offered some tobacco to the thunder, entreating it to stop. TANNKK, Narrative of a Captivity am nig the North American Indians, p. 136. L] THE METHOD OF THE STUDY OF .MIND. 3 knees to examine into the causes of events. Experience, sooner or later, reveals the uniformity with which they come to pass ; he discovers more or less of the laws of their occurrence, and perceives that he can by applying his knowledge avoid much of the damage which he has hitherto suffered that he can, by attending to theit laws, even turn to his profit those once dreaded physical forces. Now it is that man begins to feel that he has a much higher position in nature than in his infancy he had imagined ; for a time he looks upon himself as be- longing to the same order as the things around him ; and he emancipates himself in great part from the dominion of the priests in whom he had hitherto believed as the sacred propitiators of the gods whom his fears had fashioned. When his creeds are seen to spring from an imperfection of intellect, the prayers founded on them are abandoned as marking an imperfection of will. Thales of Miletus re said to have been the first who, in this advance amongst the Greeks, laid aside the priestly character and stood forth as a pure philosopher ; and those who immediately followed him, and consti- tuted the Ionian school of philosophy, having an instinc- tive feeling of the unity between man and nature, did seek objectively for a first principle of things the ap\rj common to him and the rest of nature. This slow and tedious method was soon, however, abandoned for the easier and quicker method of deduction from conscious- ness : abstractions were made from the concrete by the active mind ; and the abstractions being then projected out of the mind into objective realities, were looked upon and applied as actual entities in nature. Anaxi- inander, diving into his own mind and finding something inconceivable there, gave to it the name of the Infinite, and, transferring it outwards, was thenceforth content to pronounce it to be the true origin of all things ; whilst Pythagoras, going perhaps still further into the unmeaning, 4 THE PHYSIOLOGY OF MIND. [CHAP. proclaimed numbers, which are mere arbitrary symbols, to be actual existences and the essences of things. Thus it was that man, forgetful of his early humility, rose by degrees to the creation of a god after his own image, and to the construction of the laws of an external world after the pattern of his own thoughts : he wor- shipped a god who was of like passions with himself, sus- picious, jealous, revengeful, kindled to anger by neglect, appeased by praise and sacrifice, while such motives as he felt to influence his own actions were held also to be the principles governing the relations of external objects; natural phenomena being explained by sympathies, loves, discords, hates. As the child attributes life to the dead objects around it, speaking to them and thinking to re- ceive answers from them, so mankind, in the childhood of thought, assigned its subjective feelings to objective nature, entirely subordinating the physical to the meta- physical : it was but another form of that anthropo- morphism by which the Dryad was placed in the tree, the Naiad in the fountain, Atropos with her scissors near the running life-thread, and a Sun-god enthroned in the place of a law of gravitation. As was natural, man, who thus imposed his laws upon nature, soon lost all his former humility, and from one erroneous extreme passed to the opposite : as once he fell abjectly down in an agony of fear, so now he rose proudly up in an ecstasy of conceit. The assertion that man is the measure of the universe was the definite expression of this metaphysical stage of human development. But it was a state that must plainly be fruitless of real knowledge ; there could be no general agreement among men when each one looked into his own mind, and, arbitrarily framing the principles of external nature out of what he thought he found there, evolved the laws of the world out of the depths of his own consciousness. Disputes must continually arise about words when words have not definite meanings j I.] 777;? METHOD OF THE STUDY OF MIND. 5 and the unavoidable issue must be Sophistry and Pyr- rhonism. This has been so ; the history of the human mind shows that systems of scepticism have alternated regularly with systems of philosophy. Fruitful of empty ideas and wild fancies, philosophy has not been unlike those barren women who would fain have the rumbling of wind to be the motion of offspring. Convinced of the vanity of its ambitious attempts, Socrates endeavoured to bring philosophy down from the clouds, introduced it into the cities, and applied it to the conduct of human life ; while Plato and Aristotle, opposite as were their professed methods, were both alive to the vagueness of the common dis- putations, and both laboured hard to fix definitely the meanings of words. But words cannot attain to de- finiteness save as living outgrowths of realities, as the exact expressions of the phenomena of life in the in- creasing speciality of human adaptation to external nature. As it is with life objectively, and as it is with cognition or subjective life, so is it with the organic growth of the language in which the phenomena are embodied : there is a progress from the simple to the complex. When the words of the Aryan languages are carefully analysed into their last radical elements, those prehistoric or primor- dial elements which resist further analysis, we trace a gradual progress from simple to mixed modes of thought, and from concrete to abstract conceptions; there is a continuous differentiation, first of nouns into substan- tives and adjectives, then of the latter into adjectives proper and nouns abstract ; synonymes again disappear, each getting its special appropriation, for the more ancient a language the richer it is in synonymes, and superfluous words arc taken up by new developments and combina- l : ons of thought.* How, then, was it possible that a * " There are dialects spoken at the present day which have no abstract nouns, and the more we go back in the history of languages, 2 6 THE PHYSIOLOGY OF MIND. [CHAP. one-sided method, which entirely ignored the examina- tion of nature, should do more than repeat the same things over and over again in words which, though they might be different, were yet not less indefinite? The results have answered to the absurdity of the method ; for, after being in fashion for more than two thousand years, nothing has been established by it ; " not only what was asserted once is asserted still, but what was a question once is a question still, and instead of being resolved by discussion is only fixed and fed. " (') * Perhaps if men had always lived in the sunny climes of the south, where the luxuriance of nature allowed of human indolence and internal contemplation, they might have continued vainly to speculate ; but when they were brought face to face with nature in the rugged north, and were driven to force by persevering labour the means of subsistence from a sterile soil, then there arose the necessity to observe her processes and investigate hei secret ways. It has been remarked that the religions ol the world have originated in subtropical climates where nature does not necessitate a continued and intense application to labour : Zoroaster, Moses, Buddha, Christ, Mahomet, having all belonged to subtropical zones. In cold and temperate climes, where man must observe and work, rather than meditate and pray, in order to live, there was an unavoidable intending of the mind to the realities of nature ; and this practice, which the exigen- cies of living first enforced, became, in the fulness of time, with those who had leisure and opportunity, the disposition consciously to interrogate and interpret the smaller we find the number of these useful expressions. As far as language is concerned, an abstract word is nothing but an adjective raised into a substantive." Auxiliary verbs have the same position among verbs as abstract nouns among substantives ; they are of late origin, and had originally a more material and expressive character. MAX MULLER, Chips from a German Workshop, vol. ii. p. 54. * See Notes at the end of the Chapters. I.] THE METHOD OF THE STUDY OF MIND. 7 nature. In Roger Bacon, we see the human mind striving unconsciously, as it were, after the true method of development ; while in Francis Bacon, who systema- tized the principles and laid down the rules of the in- ductive philosophy, we observe it doing with design and method that which it had hitherto been blindly aiming at. But as it is with the infant, so was it with humanity ; action preceded consciousness, and Bacon himself was the efflux of a spirit which prevailed and not the creator of it ; he was the conscious exponent of an unconscious impulse at work. By thus humbling himself to obey, man has conquered nature ; and those plenteous " fruits and invented works" which Bacon confidently antici- pated as " sponsors and sureties " for the truth of his method have been reaped in the richest abundance. It seems strange enough now to us that men should not have sooner hit upon the excellent and profitable method of induction. How came it to pass that when they surveyed organic nature, as Aristotle notably did, they failed to perceive the progress in development from the general and simple to the special and complex, which is evident throughout it, and which in modern times has been formularized by Von Baer as the law of progress in organic development ? Had they but formularized this law of increasing speciality and complexity in organic adaptation to external nature, then they had scarcely failed to apply it to conscious human development ; and that would have been to establish deductively the neces- sity of the inductive method.* Unfortunately, Aristotle stood alone ; and it remains his particular merit to have * " Every one of our beliefs, as Kant saw very clearly, is at the same time subjective and objective ; involving both an active and a passive condition of the mind. The real bearing of this great logical conception is an extension to the intellectual operations of the fundamental principle of biology, the correspondence of organism and environment common to every vital phenomenon. " COMTt's Positive Polity, vol. i. p. 575. (English Translation.) 8 THE PHYSIOLOGY OF MIX D. [CHAP. foreseen in some sort the value of the inductive method. Had he also consistently followed it in practice, which he did not, there was an impassable hindrance to its general adoption, in the moral errors engendered by the metaphysical or subjective method, of which Plato was so powerful a representative and so eloquent an exponent. Man, as the measure of the universe, esteemed himself far too highly to descend to be the servant and interpreter of nature; and this erroneous conceit not only affected his conception of his relation to the rest of nature, but permeated his social nature, arid vitiated his whole habit of thought. The supersti- tious reverence of the Greek, who would put to death a victorious general because he had left his dead unburied on the field of battle, must, we cannot doubt, have pre- vented Aristotle from anatomical examination of the structure of the human body. The same errors are con- tinually reappearing in human history under new forms : what happened in the Middle Ages may illustrate for us the habit of Greek thought ; for at that time mistaken religious prejudice allied itself most closely with the metaphysical method which exalted man so much over the rest of nature, opposing most virulently the birth of positive science, which seemed to threaten to degrade him; and for a time it was doubtful which would win. Can we wonder that the erroneous method was triumphant in Greece in the fourth century before Christ, when it is only recently in England, in the nine- teenth century after Christ, that the barbarian's reverence for a dead body has permitted anatomical dissection, and when the finger-bone of a saint, or a rag of his clothing, is still treasured up in some parts of the civilized world as a precious and sacred relic indued with miraculous virtues ! The evil of the metaphysical method was not intellectual deficiency only, but a corresponding baneful moral error. i.] THE METHOD OF THE STUDY OF MIND. 9 The adoption of the inductive method, which makis man the servant and interpreter of Nature, is in reality the systematic pursuance of the law of progress in organic development ; it is the conscious intending of the mind to external realities, the submitting of the understanding to things in other words, the increasing speciality of internal adjustment to external impressions; and the result is a victory by obedience, an individual increase through adaptation to outward relations, in accordance with the so-called principle of natural selec- tion. For in mental development, as in organic develop- ment, that variation will survive which is best fitted to survive. The mental capacity of one who is deprived of any one of his senses, which are the inlets to im- pressions from without, or the gateways of knowledge, is less than that of one who is in the full possession of all his senses; and the great advances in science have uniformly corresponded with the invention of some instrument by which the power of the senses has been increased, or their range of action extended. Astronomy is that which the eye has been enabled to discover by the aid of the telescope ; the revelations of new and marvellous worlds of nature have been due to the increased power of vision which the microscope has conferred ; the extremely delicate balance has supplied to science a numerical exactness ; the spectrum has furnished a means of analysing the constitution of the heavenly bodies ; and the galvanometer has given hopeful presages of important discoveries in nervous function. By the invention of these powerful aids to the senses, we have succeeded in penetrating into regions of nature which in times past were utterly unknown and undreamt of; but the deeper our inquiries have gone, the more clear has it been made that the phenomena with which the senses, whether aided or unaided, bring io THE PHYSIOLOGY OF MIND. [CHAP. us into relation, are but an inconsiderable fraction, on the one hand, of the infinite magnitude of the universe, and, on the other hand, of the infinitely minute and complex molecular activities of nature, which are equally inaccessible to our present powers of perception as in conceivable to us as colour to the blind, or as music to the deaf. Art has attained to the skill to measure the one-millionth of an inch, to detect a rise in temperature of 8,8ooth of a degree centigrade, to reveal by the spec- troscope the 1 80,000, oooth part of a grain of soda; but these are probably only coarse measurements when com- pared with the delicacy of the sense of smell, or at any rate with the infinite minuteness of the molecular activities of matter. There is endless room for further development of the senses. Through them has know- ledge entered; and the intellect has in turn devised means for extending their action and increasing their discriminating exactness : there have been action and reaction and progressive specialization and complication thereof. The two aspects of this relation we designate, in their highest manifestations, as cognition and action, or science and art. That which lies outside the relations of the subject, with which man cannot come into any sort of relation by his senses or otherwise, which lies therefore altogether beyond consciousness, has been called the Real, the Unconditioned, the Absolute, the Unknowable; and it would not be difficult to invent another meaningless term, beginning with a capital letter, in order to name the unnameable. Such existence has no more relation to us as conscious beings than the moral feelings of man- kind have to the sensibility of an oyster or of an infusory animalcule ; it could be known only by a consciousness which had the power of transcending consciousness ; and to affirm anything of it, either positive or negative, is simply nonsense. Metaphysicians have, it is true, some- I.] THE METHOD OF THE STUDY OF MIND. \\ times converted this impotence into a superconscious faculty of mind to which they have given a big name, such as Intuition of the Absolute or the like ; but although we may think it probable, or feel certain, that there is existence beyond human consciousness, which is no more knowable by us than are moral relations by the oyster or the infusory animalcule, we are not entitled to make a positive cognitive faculty out of what is a negation. Whence do we derive the assurance we have of existence transcending human consciousness, if all we know, feel, and believe are states of consciousness ? I cannot but look upon it as the utterance or blind pro- phecy of an instinct which will have conscious develop- ment hereafter; in other words, as the prompting of that impulse of evolution working in us which has been from the beginning, and still is, and through which it may well come to pass, ages hence, that much or something of what now lies beyond the range of human consciousness will come within the consciousness of new or more highly developed faculties of superior beings ; nature thus going on in her evident progress to attain to more complete self-consciousness. Products of the mighty past, we forefeel dimly, as it were, the mighty future, of humanity. Thus much concerning the historical evolution of the inductive method. But now comes the important ques- tion whether it is available for the study of the whole of nature. Can we apply the true inductive and objec- tive method to the investigation of psychical as well as of physical nature? In the latter case it has long re- ceived universal sanction ; but in the study of a man's mind it is still a question what method should rightly be employed. Plainly, it is not possible by simple ob- servation of others to form true inductions concerning their mental phenomena ; the defects of an observation which reaches only to the visible results of invisible 12 THE PHYSIOLOGY OF MIND. [CHAP. operations expose us without protection to the hypo- crisy, conscious or unconscious, of the individual ; and the positive tendency, which no one can avoid, to interpret the action of another mind according to the measure of his own, to see not what is in the object but what is in the subject, frequently vitiates an assumed penetration into motives. If we call to our aid the principles of the received system of psychology, matters are not mended ; for its ill-defined terms and vague traditions, injuriously affecting our perceptions and overruling the understanding, do not fail to confuse and falsify inferences. It must unfortunately be added that, in the present state of physiological science, it is quite impossible to ascertain, by observation and experiment, the nature of those organic processes which are the bodily conditions of mental phenomena. There would appear, then, to be no help for it but to have entire recourse to the psychological method that method of interrogating self-consciousness which has found so much favour at all times. Before making any such admission, let this reflection be weighed : that the instinctive nisus of mankind com- monly precedes the recognition of systematic method ; that men, without knowing why, do follow a course for which very good reasons exist. Nay, more : the practical instincts of mankind often work beneficially in actual contradiction to their professed doctrines. When in the Middle Ages faith was put in the philosophy of the schools, the interrogation of nature by experiment was going on in many places ; and the superstitious people that believe in the direct interference of spirits or oi gods, still adopt such means of self-protection as a simple experience of nature teaches. Man does not consciously determine his method and then enter upon it; he enters blindly upon it and at a certain stage awakes to consciousness. The process of reasoning L] THE METHOD OF THE STUDY OF M1XD. 13 itself adds nothing to knowledge ; it only displays what was there before, brings to conscious possession what before was unconscious, makes explicit what was implicit in practical instinct. In the onward flowing stream of nature's organic evolution, life first becomes self-con- scious in man : in the slumbering mental development of mankind, it is the genius who at due time awakens to active consciousness the sleeping century. It would indeed go hard with mankind if they must act wittingly before they acted at all. Two facts come out very distinctly from a candid observation of the state of thought at the present day. One of these is the little favour in which metaphysics is held and the very general conviction that there is no profit in it : the consequence of which firmly fixed belief is, that it is cultivated as a science only by those whose particular business it is to do so, who are engaged not in action, wherein the true balance of life is main- tained, but in speculating in professorial chairs, or in other positions where there are little occasion for hard obser- vation and much leisure for introspective contemplation ; or if by any others, by the ambitious youth who goes through an attack of metaphysics as a child goes through an attack of measles, getting haply an immunity from a similar affection for the rest of his life ; or, lastly, by the active and ingenious intellects of those metaphysical philosophers who, never having been trained in the methods and work of a scientific study of nature, have not submitted their understandings to facts, but live in a more or less ideal world of thought A second fact, which has scarcely been sufficiently weighed, is the extreme favour in which biography is held at the pre- sent time and the large development which it is re- ceiving. Let us look first at the import of biography. As the business of a man in the world is action of some kind, 14 THE niYSIOLOGY OF MIND. [CHAP. and as his actions undoubtedly result from the relations between him and his surroundings, it is plain that bio- graphy, which estimates both the individual and his circumstances and displays their inter-workings, can alone give an adequate account of the man. What was the mortal's force of character, what was the force of circumstances, how he struggled with them, and how he was affected by them, what was the life-product under the particular conditions of its evolution ; these are the questions which a good biography aspires to answer. It regards men as concrete beings, takes note, if it does its work properly, of their ancestral antecedents, acknowledges the differences between them in characters and capabilities, recognises the helpful or baneful influence of surroundings, and patiently unfolds the texture of life as the inevitable result of the ele- ments out of which, and the conditions under which, it has been worked. It is, in fact, the application of positive science to human life and the necessary con- sequence of the progress of the inductive philosophy. No marvel, then, that biography forms so large a part of the literature of the day, and that novels, its more or less faithful mirrors, are in so great request. The practical instincts of mankind are here, as heretofore, in advance of systematic knowledge or method. On the other hand, the metaphysician has dealt with man as an abstract or ideal being, having taken no account of concrete men, has postulated him as a certain constant quantity, and thereupon confidently enunciated empty propositions. The consequence is that meta- physics has never made any advance, but has only appeared in new garb; nor can it in truth advance unless some great addition is made to the inborn power of the human mind. It surely argues no little conceit in any one to believe that what Plato and Descartes i.] THE METHOD OF THE STUDY OF MIND. 15 have not clone, he, following the same method, will do.* Plato interrogated his own mind, and set forth its answers with a clearness, subtilty, and elegance of style that is unsurpassed and unsurpassable; until then the probably yet far distant event of a better mind than his making its appearance, his system may well remain as the adequate representation of what the metaphysical method can accomplish. Superseded by a more fruitful method, it is practically obsolete ; and its rare advocate, when such a one is found, may be said, like the Aturian parrot of which Humboldt tells, to speak in the lan- guage of an extinct tribe to a people which understand him not.t But the method of interrogating self-consciousness may be employed, and is largely employed, without carrying it to a metaphysical extreme. Empirical psy- chology, founded on direct consciousness as distin- guished from the transcendental consciousness, whatever that may be, on which metaphysics is based, claims to give a faithful record of our different states of mind and of their mutual relations, and has been extravagantly lauded by the Scotch school as an inductive science. It is argued, and with great cogency, that such states as * " It would be an unsound fancy and self-contradictory, to expect that tilings which have never yet been done can be done, except by means which have never yet been tried. " Nov. Org. Aphorism vi. Forasmuch, however, as we have good grounds for believing that there is an accumulation of the inherited results of mental acqui- sitions through the ages, whereby an inborn addition is made to the power of the individual mind, we must admit the possibility that those who can detect the forms and laws of thought by introspec- tion may, after all, be able to do more than has been dene in times past. t ' ' There still lives, and it is a singular fact, an old parrot in Maypures which cannot be understood, because, as the natives assert, it speaks the language of the Atures an extinct tribe of Indians, whose last refuge was the rocks of the foaming cataract of the Orinoco." HUMDOLDT, Views of Nature, vol. i. p. 172. 16 THE PHYSIOLOGY OF MIND. [CHAP. thoughts, feelings, memories, volitions, are subjective, known only to the individual's consciousness, the words denoting them having acquired their meaning from introspection ; that they admit of classification, which obviously can only be done by introspection ; and that there may therefore be a science of mind, a psychology, which may stand on its own basis and be studied in- dependently of all other sciences. The question then is concerning the nature of the basis. Its value as an inde- pendent science must plainly rest upon the trustworthi- ness and the sufficiency or competence of consciousness as a witness of that which takes place in the mind. Is the foundation sufficiently secure? It may well be doubted ; and for the following reasons : (a.) The first, which is of no great weight, seeing that a similar objection might be made to observa- tion in any other science, is, that there are but few individuals who are capable of attending to the succession of phenomena in their own minds ; such in- trospection demanding a particular cultivation, and being practised with any degree of, or pretence to, success by those only who have learned the terms, and been imbued with the theories, of the system of psychology supposed to be thereby established. And with what success ? (.) There is no agreement between those who have acquired the power of introspection ; and men of ap- parently equal cultivation and capacity will, with the utmost sincerity and confidence, lay down inconsistent or directly contradictory propositions. It is not possible to convince either opponent of error, as it might be in a matter of objective science, because he appeals to a witness whose evidence can be taken by no one but himself, and whose veracity, therefore, cannot be tested. He brings forward the factitious deliverances of his indi- vidual consciousness, but no fact which is capable of I.] THE METHOD OF 7 HE STUDY OF MIND. 17 being demonstrated to another mind. Now there is no witness who is so easily suborned to give false evidence, and whose testimony at all times requires such stringent cross-examination, as self-consciousness. For when it is at work, the observed and the observer are one, and the observer is not likely in such case to be unbiased by the feelings of the observed and to conform rigidly to the rules of exact observation. In external observation we find it necessary to lay down strict rules in order to avoid fallacies ; it is certainly not less necessary to do so in observation from within. (c.) To direct consciousness inwardly to the observa- tion of a particular state of mind is to isolate that activity for the time, to cut it off from its relations, and, therefore, to render it unnatural. In order to observe its own action, it is necessary that the mind pause from activity ; and yet it is the train of activity that is to be observed. So long as you cannot effect the pause necessary for self-contemplation, there cannot be a sufficient observation of the current of activity : if the pause is effected, then there can be nothing to observe ; there would be no consciousness, for consciousness is awakened by the transition from one physical or mental state to another.* This cannot be accounted a vain and theoretical objection, for the results of introspection too surely confirm its validity : what was a question once is * To persist in one mode or state of consciousness would be really to be unconscious ; wherefore when our attention is given intensely to some observation or reflection, so that we are absorbed in it, we hardly seem to be conscious ; in fact, consciousness is aroused when the attention wanders. We do not perceive one con- tinuous and unvarying action upon the senses, e.g. the movement of the earth, the pressure of the atmosphere upon the surface of our bodies, &c. For the same reason probably we do not hear the music of the spheres ; a sound of unvarying tone and continu- ance falling on the ears from the first moment of life. And yet it is possible the noise may be stupendous. i8 THE PHYSIOLOGY OF MIND. [CHAP. a question still, and instead of being resolved by intro- spective analysis is only " fixed and fed."( 2 ) (d.) The madman's delusion, which is only an extreme instance of error growing out of causes that are con- stantly at work to pervert an individual's feeling and to vitiate his reasoning, is of itself sufficient to excite profound distrust, not only in the objective truth, but in the subjective worth, of the testimony of an individual's self-consciousness. Descartes laid down the test of a true belief to be that which the mind could clearly and distinctly conceive : if there is one thing more clearly and distinctly conceived than another, it is commonly the madman's delusion. No marvel, then, that psycho- logists, since the time of Descartes, have held that the veracity of consciousness is to be relied upon only under certain rules, from the violation of which, Sir W. Hamilton believed, the contradictions of philosophy had arisen. On what evidence, then, do the rules rest ? Either on the evidence of consciousness, whence it comes to pass that each philosopher and each lunatic has his own rules, and no advance is made ; or upon the observation and judgment of mankind, to confess which is very much like throwing self-consciousness overboard not otherwise than as was advantageously done by positive science when the exact figures on the ther- mometer, and not the subjective and deceptive feelings of heat or cold, were recognised to be the true test of the individual's temperature. The charge against self-consciousness is not merely that it cannot always be relied upon in that of which it does give information, but that it does not give any account of a large and important part of our mental activity : its light reaches only to states of conscious- ness, not to states of mind. Its evidence, then, is not only untrustworthy save under conditions which it no- wise helps us to fix, but it is of little value, because it I.] THE METHOD OF THE STUDY OF MIND. 19 has reference only to a small part of that for which its testimony is invoked. May we not then justly say that self-consciousness is utterly incompetent to supply the facts which shall lay the foundations of a truly inductive psychology ? Let the following reasons further warrant the assertion : i. It is the fundamental maxim of inductive philoso- phy that observation should begin with simple instances, ascent being made from them step by step through appropriate generalizations, and that no particulars should be neglected. How does the interrogation of self-consciousness fulfil this just demand? It is a method which is applicable only to mind at a high degree of development, so that it perforce begins with those most complex instances which give the le*ast certain information ; while it passes completely by mind in its lower stages of development, ignoring those simpler instances which give the best or securest infor- mation. In this it resembles the philosopher who, while he gazed upon the stars, fell into the water ; " for if," as Bacon says, " he had looked down, he might have seen the stars in the water, but, looking aloft, he could not see the water in the stars."( 3 ) Where has the animal any place in the accepted system of psychology ? or the child, the direction of whose early mental development is commonly decisive of its future destiny? To speak of induction, where so many important instances are neglected and others are selected according to caprice or the ease of convenience, is to rob the word of all definite meaning and mischievously to misuse it. Psychology has neglected not only all animals except man, as it was bound by its method to do, but all the lower races of men : instead of being a science of mental phenomena as these are presented in nature, it represents the deliverances of the complex self-consciousness of an educated white man who has been specially trained ao THE PHYSIOLOGY OF MIND. [CHAP. in its method. Hence have arisen the hot disputes between the empiricists who looked on one side of the shield and the idealists who looked on the other side of it between those who hold that all knowledge is derived from experience, and those who uphold the existence of forms of thought in the mind anterior to experience. Study the development of mind from its beginning in animals through its manifold gradations up to its highest reach in man, and it is made probable that the so-called forms of thought represent the innate mental capacities which are the result of evolution which the civilized man has, and which the animal or the lowest savage has not. A psychology which is truly inductive must follow the order of nature, and begin where mind begins in the animal and infant, rising thence gradually to those higher and more complex mental phenomena which the introspective philosopher discerns or thinks he discerns. Certainly it may be said, and it has been said, that inferences as to the mental phenomena of the child can be correctly formed from the phenomena of the adult mind. But it is exactly because erroneous inferences have been made in that way, that the mental phenomena of the child have been misunderstood and misinterpreted, and that psychology has not received the benefit of the correction which a faithful observation of them would have furnished. It was the physiologist who by a care- ful observation of the lower animals, " having entered firmly on the true road, and submitting his understanding to things," arrived at generalizations which were found to explain many of the mental phenomena of the child, and which have furthermore thrown much light upon the mental life of the adult. The careful study of the genesis of mind is as necessary to a thorough knowledge of mental phenomena as the study of its plan of de- velopment confessedly is to an adequate conception of the bodily organization and its functions. I.] THE METHOD OF THE STUDY OF MIND. 21 Again, it rriight be thought a monstrous mistake of nature to have brought forth so many idiots and lunatics, seeing that the introspective psychologists, though mak- ing a profession of induction with their lips, have taken no notice whatever of the large collection of instances afforded by such unwelcome anomalies. Certainly it may be said, and no doubt it has been said, that the mental phenomena of the idiot and lunatic are morbid, and do not, therefore, concern psychology. It is true that they do not concern a psychology which violently separates itself from nature. But it is exactly because psychology has thus unwarrantably severed itself from nature of which the so-called morbid phenomena are no less natural a part than are the phenomena" of health that it has no sure foundations ; that it is not induc- tive ; that it has not received the benefit of the corrective instances which a faithful observation of the unsound mind would have afforded. In reality the phenomena of insanity, presenting a variation of conditions which cannot be produced artificially the instantia contra- dictoria furnish what iu such matter ought to have been seized with the utmost eagerness ; namely, actual experiments well suited to correct false generalization and to establish the principles of a truly inductive science. The laws of mental action are not miraculously changed nor reversed in madness, though the conditions of their operation are different; and nature does not recognise the artificial and ill-starred divisions which men, for the sake of convenience, and not unfrequently in the interests of ignorance, make. 2. Consciousness, which does not even tell us that we have a brain, is certainly incompetent to give any ac- count of the essential material conditions which underlie every mental manifestation and determine the character of it. Let the function of an individual's optic ganglia be abolished by disease or otherwise, and he would not 22 THE FH\SIOLOGY OF MIND. [CHAP. be conscious that he was blind until experience had con- vinced him of it. Let him have a sensation of light or of sound, or any other seemingly most simple sensation, he would not learn through consciousness how complex it really is, nor even whether it proceeded from within or from without whether it was entirely subjective or whether it had an objective cause; that he could only learn by subsequent discovery. The most simple phenomenon which consciousness makes known to us is really very complex ; a feeling which is elementary to it may be far from elementary ; and we cannot, by its means, go deeper into the discovery of the simpler constituent elements. Clearly then the science which does enable us to go deeper in the analysis of the really complex state which the most simple delivery of consciousness is, must lie at the foundation of a true psychology. On grounds which will not easily be shaken it is now indeed admitted, that with every display of mental activity there is a cor- relative change or waste of nervous element ; and on the condition of the material substratum must depend the degree and character of the manifested energy or the mental phenomenon. Now the received system of psy- chology gives no attention to these manifold variations of feeling in the same individual which are due to tem- porary modifications of the bodily state, and by which the ideas of the relations of objects to self and to one another are so greatly affected. The quality of the ideas which arise in the mind under certain circum- stances, the whole character indeed of our insight at the time, is notably determined in great part by the feeling which may then have sway ; and that feeling is not always objectively caused, but may be entirely due to a par- ticular bodily condition, as the daily experience of every one may convince him, and as the early phenomena of insanity often illustrate in a striking manner. The most ingenious introspectionist could never discover from the I.] THE METHOD OF THE STUDY OF MIND. 23 revelations of self-consciousness that the cause of a par- ticular mood of mind lay in the liver, or in the heart, or in some other organ of the body ; nor could he gain from them the least inkling how essentially the opera- tions of these organs affect the characters of the in- dividual, the actual constitution of his ego. Every sensation, again, is located by consciousness peripherally; it tells us plainly that touch is in the finger, sound in the ear, sight in the eye, smell in the nostrils ; whereas physiological observation proves to us conclusively that this information is incorrect, and that each sensation has its immediate seat centrally in the brain. Again, Bacon long ago set down individual psychology as wanting ; and insisted on a scientific and accurate dissection of minds and characters, and the secret dispositions of particular men, so " that from the knowledge thereof better rules may be framed for the treatment of the mind."(*) So far as the present psy- chology is concerned, the individual might have no existence in nature ; he is an inconvenience to a system which, in neglecting the individual character or tem- perament, ignores another large collection of valuable instances. -So far as truth is concerned, however, the individual is of some moment, seeing that he often posi- tively contradicts the principles arbitrarily laid down by a theoretical system. He who would realize how vague, uncertain, speculative, how far from the position of a true science, psychology is, should endeavour to grasp some one of its so-called principles, and to apply it deductively in order to predicate something of the char- acter of a particular person ; let him do that, and he can- not fail to perceive how much he has been mocked with the semblance of knowledge, and must needs agree with Bacon as to the necessity of a " scientific and accurate dissection of minds and characters and the secret dis- positions of particular men." That, moreover, is a study 24 THE PHYSIOLOGY OF MIND. [CHAP. which will be prosecuted successfully not by looking within but by looking without himself. When the theologist, who occupies himself with the supersensuous, has said all that he has to say from his point of view; when the jurist, who represents those principles which the wisdom of society has established, has in turn exhaustively argued from his point of view, then the ultimate appeal in a concrete case must be to him, be he physiologist or physician, who deals with the bodily organization; through his ground only can the theologist and jurist pass to their departments, and they must accept their knowledge of it from him : on the foundation of facts which the faithful investigation of the bodily nature lays, must rest, if they are to rest safely, their systems. Certainly it is not probable that this most desirable and inevitable result will come to pass in this day or generation; for it is not unknown how far distant yet is the day of full and exact physiological knowledge, nor how slowly, when it approaches, we may expect the light to penetrate the thick fogs of ignorance, and to dissipate the irritated prejudices which ever op- pose the gentle advent of new truth. Happily, it is certain that in the mortality of man lies the salvation of truth. 3. There is an appropriation of external impressions by the mind or brain, which regularly takes place without any, or only with a very obscure, affection of conscious- ness. As the various organs of the body obtain from the blood the material suitable to their nourishment and assimilate it, so the organ of the mind unconsciously appropriates, through the inlets of the senses, the influ- ences of its surroundings. The impressions which it thus receives and retains do not produce definite ideas and feelings, but they nevertheless permanently affect the mind's nature ; so that as an individual consciously provides his food, and then leaves the due assimilation i.] THE METHOD OF THE STUDY OF MIND. 25 of it to the unconscious action of the organism, in like manner may he consciously arrange the circumstances in which he will live, but cannot then prevent the uncon- scious assimilation of their influence and the correspond ing modification of his character. Not only slight habits of movement are thus acquired, but habits of thought and feeling are imperceptibly organized ; so that an acquired nature may ultimately govern one who is not at all conscious that he has changed. Let any one take careful note of his dreams, he will find that many of the seemingly unfamiliar things with which his mind is then occupied, and which appear to be new and strange pro- ductions, are traceable to the unconscious appropriations of the day. There are other stories on record like that well-known one which Coleridge quotes of the servant- girl who, in the ravings of fever, repeated long passages in the Hebrew language, which she did not understand, and could not repeat when well, but which, when living with a clergyman, she had heard him read aloud. The remarkable memories of certain idiots, who, much defi- cient in or nearly destitute of intelligence, will repeat the longest stories with the greatest accuracy, testify also to this unconscious cerebral action ; and the way in which the excitement of a great sorrow, or some other cause, such as the last flicker of departing life, will sometimes call forth in idiots manifestations of mind of which they always seemed incapable, renders it certain that much is unconsciously taken up by them which cannot be uttered, but which leaves its relics in the mind. It is a truth which cannot be too distinctly borne in mind, that consciousness is not co-extensive with mind, that it is not mind but an incidental accompaniment of mind. It may seem, perhaps it is, an extravagant thing to say, but to me it seems conceivable that a man might be as good a reasoning machine without as he is with consciousness, if we assumed his nervous system to be *6 THE PHYSIOLOGY OF MIND. [CHAP. equally susceptible to the influences which now affect him consciously, and if we had the means, by microscope or galvanoscope or some other more delicate instrument hereafter to be invented, of reading off the results of his cerebral operations from without : we should be dis- pensing only with the sense by which the operations are observed within, not with the power by which they are done with the witness not with the agent of them. From the first moment of its independent existence the brain begins to assimilate impressions from without, and to react thereto in corresponding organic adaptations; this it does at first without con- sciousness, and this it continues to do unconsciously more or less throughout life. Thus it is that mental power is being organized before the supervention of con- sciousness, and that the mind is subsequently regularly modified as a natural process without the intervention of consciousness. The preconscious action of mind, as certain metaphysical psychologists in Germany have called it, and the unconscious action of mind, which may perhaps be now deemed to be established, are assuredly facts of which the most ardent introspective psychologist must admit that self-consciousness can give us no ac- count. I do not overlook the fact that some writers hold these supposed unconscious states not to be, as they appear, entirely unconscious, believing that it is because slight attention only is given to them that they pass away immediately and are forgotten. But if this be granted, it does not really alter matters much ; for it would only prove that the brain or mind may do its work with a consciousness so slight as to be almost nil. A con- sciousness which has sunk to such a degree of subcon- sciousness as to be practically unconsciousness, cannot be of much moment in the operations : when so much is dispensed with, it is hardly worth while to contend for the importance of the little that is left. I.] THE METHOD OF THE STUDY 01< MIND. 27 4. That which has existed with any completeness in consciousness leaves behind it, after its disappearance therefrom, in the mind or brain, a functional disposition to its reproduction or reappearance in consciousness at some future time.( 5 ) Of no mental act can we say that it is "writ in water;" something remains from it whereby its recurrence is facilitated. Every impression of sense upon the brain, every current of molecular activity from one to another part of the brain, every cerebral reaction which passes into muscular movement, leaves behind it some modification of the nerve elements concerned in its func- tion some after-effect or, so to speak, memory of itself in them which renders its reproduction an easier matter, the more easy the more often it has been repeated, and makes it impossible to say that, however trivial, it shall not under some circumstances recur. Let the excita- tion take place in one of two nerve-cells lying side by side, and between which there was not any origina* specific difference, there will be ever afterwards a differ- ence between them. This physiological process, what- ever be its nature, is the physical basis of memory, and it is the foundation of the development of all our mental functions. That modification which persists or is retained in structure after function, has been differently described as a residuum, or relic, or trace, or disposition, or vestige, or again as potential, latent, or dormant idea. Not only definite ideas, but all affections of the nervous system, feelings of pleasure and pain, desires, and even its out- ward reactions, thus leave behind them their structural effects, and lay the foundations of modes of thought, feeling, and action. Particular talents are sometimes formed quite, or almost quite, involuntarily ; and com- plex actions, which were first consciously performed by dint of great application, become automatic by repeti- tion ; ideas, which were at first consciously associated, 23 THE PHYSIOLOGY OF MIND. [CHAP. ultimately coalesce and call one another up without any consciousness, as we see in the quick perception or intuition of the man of large worldly experience ; and feelings, once active, leave behind them their uncon- scious residua, thus affecting the general tone of the character, so that, apart from the original or inborn nature of the individual, contentment, melancholy, cowardice, braver)-, and even moral feeling are generated as the results of particular life-experiences. Conscious- ness is not able to give any account of the manner in which these various residua are perpetuated, and how they exist latent in the mental organization ; but a fever, a poison in the blood, or a dream, may at any moment recall ideas, feelings, and activities which seemed to have gone for ever. The lunatic sometimes reverts, in his ravings, to scenes and events of which, when in his sound senses, he has no memory ; the fever-stricken patient may pour out passages in a language which he understands not, but which he has accidentally heard ; a dream of being at school again brings back with painful vividness the school feelings ; and before him who is drowning every event of his life seems to flash in one moment of strange and vivid consciousness. ( 6 ) Some persons who suffer from recurrent insanity remember only in their lucid intervals the facts of former lucid intervals, and in their paroxysms of derangement the ideas, feelings, and events of former paroxysms. Dreams not remembered in the waking state may yet affect future dreams, appearing in them as vague and confused recollections. * " A Lutheran clergyman of Philadelphia informed Dr. Rush that Germans and Swedes, of whom he had a considerable number in his congregation, when near death, always prayed in their native language, though some of them, he was confident, had not spoken these languages for fifty or sixty years." ABERCROMEIE, On tJu Intellectual Povtert, p. 142, 8th ed. 1838. I.J THE METHOD OF THE STUDY OF MIND. 29 It has been before said that mind and consciousness are not synonymous; it may now be added, that the existence of mind does not necessarily involve its con- stant activity. Descartes maintained that the mind is a spiritual activity which always thinks; and others, resting on that assumption, have held that we must always dream in sleep, because the mind, being spiritual, cannot cease to act; for non-activity would be non- existence. Such opinions illustrate how completely metaphysical conceptions may overrule the best under- standing : non-activity of function is certainly non-exist- ence of function, but it is not mental annihilation ; so far from the mind being always active, it is the fact that at each moment the greater part of the mental organi- zation is not only unconscious, but inactive. Mental power exists in statical equilibrium as well as in mani- fested energy; and the utmost tension of a particular mental activity may not avail to call forth from their secret repository the dormant energies of latent faculty, even when its function is most urgently needed : no man can call to mind at any moment the thousandth part of his knowledge. How utterly helpless is con- sciousness to give any account of the statical condition of mind ! But as statical mind is in reality the statical condition of the nervous substrata which minister to its manifestations, it is plain that, if we ever are to know anything of mental organization, it is to the progress of physiology that we must look for information. 5. Consciousness reveals nothing of the actual process by which one idea calls another into activity, and has no control whatever over the manner of the repro- duction ; it is only when the idea is made active by virtue of some association, when the effect solicits or extorts attention, that we are conscious of it; and there is no power in the mind to call up ideas indifferently. If we would recollect something which at the moment 3 30 THE PHYSIOLOGY OF MIND. [CHAP. escapes us, confessedly the best way of succeeding is to permit the brain to work unconsciously ; and while the consciousness is otherwise occupied, the forgotten name or circumstance will oftentimes flash into the memory. A glass of wine or some other stimulant shall sometimes do more to arouse ideas by its physical or chemical action upon the nerve-element than the strongest efforts of attention will do. In composition the writer's consciousness is engaged chiefly with his pen and with the sentences which he is forming, while the results of the brain's unconscious working, matured by an insensible gestation, emerge from unknown depths into consciousness, and are by its help embodied in appropriate words. As there are undulations of ether which are too rapid, and others which are too slow, to produce the sensation of light when they strike upon the eye, so it is easy to conceive that there may be molecular vibrations in the nerve- element which are either too rapid or too slow to generate consciousness, but which, never- theless, suffice to effect these latent associations. Not only is the actual process of the association of our ideas independent of consciousness, but that assimi- lation or blending of similar ideas, or of the like in different ideas, by which general ideas are formed, is in no way under the control or cognizance of conscious- ness. When the like in two perceptions is appropriated, while that in which they differ is neglected, it would seem to be by an assimilative action of the nerve-cells or circuits of the brain which, particularly modified by the first impression, have an attraction or affinity for a like subsequent impression : the nerve-element so modified and so ministering takes to itself that which is suitable and which it can assimilate, or make of the same kind with itself, while it rejects, for appropriation by other nerve-circuits, that which is unlike and which will not blend. Or that which takes place may perhaps 7.] THE METHOD OF THE STUDY OF MIND. 31 be represented more correctly in this way : when two objects resemble one another, having common qualities of which we can form a general idea, that which is like in them will necessarily* excite in the same nerve-tract of the brain exactly the same number and kind of molecular vibrations; the second perception will be a reproduction of the first, in so far as it is a perception of the qualities which the second object has in common with the first. Now this reproduction of the same vibra- tions, which is the perception of the like in two ideas, will take place the more readily because of the functional disposition to the reproduction of them which the first perception has left behind it ; wherefore, as all experi- ence shows, there is a tendency of mind to perceive resemblances. That in which the second perception differs from the first will also excite its appropriate vibra- tions, but if they do not blend into unity with any previously experienced ones, they are not readily appre- hended, and may be overlooked entirely by conscious- ness ; they are so feeble or pass away so rapidly perhaps that the state of consciousness appropriate to them is not produced. It is the aim, therefore, of a good training in observation and reasoning to compel attention to differ- ences in order that they may make a fit impression and be registered, and thus to prevent too hasty generalization. Whatever the organic process in the brain, it takes place, like the organic action of other elements of the body, quite out of the reach of consciousness. We are not aware how our general and abstract ideas are formed ; the due material is consciously supplied, and there is an unconscious elaboration of the result Mental development thus represents a sort of nutrition and organization ; or, as Milton aptly says of the opinions of good men that they are truth in the making, so we may truly say of the formation of our general and complex ideas that it is mind in the making. When 3* THE PHYSIOLOGY OF MIND. [CHAP. the individual brain is a well-constituted one, and has been duly cultivated, the results of its latent activity, rising into consciousness suddenly, sometimes seem like intuitions ; they are strange and startling, as the products of a dream ofttimes are, to the person who has actually produced them. Hence it was no extravagant fancy in Plato to look upon them as reminiscences of a previous higher existence. His brain was a brain of the highest order, and the results of its unconscious activity, as they flashed into consciousness, would show like revelations, and might well seem intuitions of a higher life quite beyond the reach of present will. But the process of unconscious mental elaboration is sufficiently illustrated in daily experience. The in- stantaneous judgments of the distance, the position, the size, the figure of objects, which accompany our visual sensations, are not consciously made, nor are they put in logical form ; in fact, all the labours of philosophers hitherto have not been sufficient to discover and ex- plain the processes by which we acquire them to set forth explicitly the premisses, the reasoning, and the con- clusions which are implicit in them. In dreams a person may compose vigorously and fluently, or speak eloquently, who can do nothing of the sort when awake; in the first stages of acute mania there is sometimes exhibited a wit, a liveliness of imagination, a fluency of speech, of which the person is utterly incapable when he is in sound health ; schoolboys know how much a night's rest improves their knowledge of a lesson which they have been learning before going to bed; great writers or great artists, as is well known, have been truly astonished at their own creations, when they have calmly examined them after the enthusiasm of invention was past, and have been unable to conceive how they contrived to produce them ; and to the unconscious action of the brain is owing, most probably, that occasional sudden I.] THE METHOD OF THE STUDY OF MIND. 33 consciousness, which almost every one at some time or other has had, of having been before in exactly the same circumstances as those which are then present, or having said or done exactly the same thing, though such a previous exact experience was impossible ; but the action of the brain in the assimilation of events here mo- mentarily anticipates consciousness, which, when aroused, finds a familiarity in them. The same conviction is sometimes felt in dreams. The impression is momentary, vanishing in the instant of feeling it, and cannot be recalled by any voluntary effort, nor can it be adequately described in words. Inventions seem sometimes, even to the discoverers, to be matters of accident and good fortune, who, however, have not failed to deserve the accident of good fortune by long labour and training in inquiry ; the most voracious plagiarist is commonly the most unconscious ; the best thoughts of an author are always the unwilled thoughts which surprise himself; and the poet under the inspiration of creative activity is, so far as consciousness is concerned, being dictated to. If we reflect, we shall see that it must be so ; the products of creative activity, in so far as they transcend the hitherto experienced, are unknown to the creator himself before they come forth, and cannot therefore be the result of a definite act of his will ; for to an act of will a conception of the result is necessary. " The character," says Jean Paul, speaking of the poet's work, "must appear living before you, and you must hear it, not merely see it; it must, as takes place in dreams, dictate to you, not you to it ; and so much so that in the quiet hour before you might perhaps be able to foretell the what but not the hk which shall be opened at the day of judgment is the everlast- ing roll of remembrance. "The minutest incidents of my childhood, or forgotten scenes of later years, were often revived. I could not be said to recollect them ; for, if I had been told of them when wakjng, I should not have been able to acknowledge them as parts of my past experience. But placed as they were before me in dreams like intuitions, and clothed in all the evanescent circumstances and accompanying feelings, I recognized them instantly. .... Of this, at least, I feel assured, that there is no such thing as ultimate for- getting ; traces once impressed upon the memory are indestructible : a thousand accidents may and will interpose a veil between our pre- sent consciousness and the secret inscriptions of the mind. Accidents of the same sort will also rend away this veil. But alike, whether veiled or unveiled, the inscription remains for ever ; just as the stars seem to withdraw before the common light of day, whereas, in fact, we all know that it is the light which is drawn over them as a veil ; and they are waiting to be revealed, whenever the obscuring daylight itself shall have withdrawn." One is tempted to add the question from Blanco White's Sonnet: "If Light may thus deceive, wherefore not Life?" * (/. 41). "It is to be regretted that he (Dugald Stewart) had not studied (he even treats it as inconceivable) the Leibnitzian doctrine of what has not been well denominated obscure perceptions or ideas that is, acts and affections of mind, which, manifesting their existence in their effects, are themselves out of consciousness or apperception. The fact of such latent mental modifications is now established beyond all rational doubt ; and on the supposition of J4 THE PHYSIOLOGY OF MIND. [CHAP. their reality, we are able to solve various psychological phenomena otherwise inexplicable. Among these are many of those attributed to habit" (Sir W. Hamilton, in his edition of Reid, p. 551.) " Daraus, dass die Seele des Gedankens sich nicht bewusst sei, folge noch gar nicht, dass sie zu denken aufhore." (Xcue l-'ersuche lib. J. menschlich. Ver stand. B. ii. " Ich sehe nicht," says Leibnitz, again, "dass die CartesSaner jtmals beweisen haben oder beweisen konnen, dass jede Vorstellung von Bewusstsein begleitet ist" And again : " Darin namlich haben die Cartesianer sehr gcfehlt, dass sie die Vorstellungen, deren man sich nicht bewusst 1st, fiir nichts rechneten. Das war auch der Grand, warum sie glaublen, dass nur die Geiste onaden waren, und dass es keine Seelen der Thiere oder andere Entelechien gebe." Leibnitz als Denker. Ausu>ahl seiner kleincrn Aufsatze. By G. Schelling. Pp. 108 and 115. He was the first to assert the existence of "unconscious per- ceptions or ideas," and he assigned them a high importance. The phrase may seem paradoxical, but the contradiction is perhaps only apparent For if we only know what we are conscious of, and know nothing of which we are not conscious, what right have we to declare of the existence which we know by or in consciousness, that it can have no existence out of consciousness ? "Vorstellungen zu haben, und sich ihrer doch nicht bewusst zu sein, darin scheint ein Widerspruch zu liegen. Allein wir konnen uns doch mittelbar bewusst sein, eine Vorstellung zu haben, ob wir gleich unmittelbar uns ihrer nicht bewusst sein." KANT, Anihropologie. Quoted by Hartmann : Philos*phic des Unbewussten. VoL i. p. 13. Fichte, in his Btstimmung dts Afenscken " In jedem Momente ihrer Dauer ist die Natur ein zusumrnenhangendes Ganze ; in jedem Momente muss jeder einzelne Theil derselbe so sein wie er ist, weil alle iibrigen sind wie sie sind ; und du konntest kein Sandkornchen von seiner Stelle verriicken, ohne dadurch vielleicht alle Theile des unermesslichen Ganzen hindurch etwas zu verandern. Al>er jeder Moment dieser Dauer ist bestimmt durch alle abgelaufenen Momente, und wird bestimmen alle kiinftigen Momente, und du kannst in dem gegenwartigen keines Sandkorne Lage andcrs denken als sie ist, ohne dass du genothigt wiirdest die ganze Vergangenheit ins Un- bestimmte hinauf, und die ganze Zukunft ins Unbestimmte herabdir anders zu denken." Sammtliche Werke, ii. 178. It is only right to add, that the fullest exposition of unconscious menial action is to be found in Beneke's works. A summary of his views is contained in his Lchrbutk der Psychologic als Natur- wissenschafl. I.] THE METHOD OF THE STUDY OF MIND. 75 * (/ 69)- I leave this note as it stood in the first edition (1867). Then the criticism was thought by some to be hardly just ; indeed, it has not escaped censure. There are few persons, I suspect, who would not endorse it now in its application to Mill. Since this chapter was written, and, indeed, separately published, Mr. J. S. Mill has made a powerful defence of the so-called Psycho- logical Method. In his criticism of Comte in the Westminster A'at'fU 1 for April 1865, and in his " Examination of Sir W. Hamil- ton's Philosophy," he has said all that can be said in favour of the Psychological Method, and has done what could be done to dis- parage the Physiological Method. This he had already done many years ago in the second volume of his "System of Logic," and he is now only consistent in returning to the charge. Nevertheless, the admirers of Mr. Mill may well experience regret to see him serving with so much zeal on what is a so desperately forlorn hope. Physiology seems never to have been a favourite study with Mr. Mill in none of his writings does he exhibit any indications of being really acquainted with it ; for it is hardly possible to conceive that any one having a knowledge of the present state of this science, would disparage it as he has done, and exalt so highly the psycholo- gical method of investigating mental phenomena. The wonder is, however, that he who has done so much to expound the system of Comte, and to strengthen and complete it, should on this question take leave of it entirely, and follow and laud a method of research which is so directly opposed to the method of positive science. Of course, I speak now strictly of the method, not of Comte's applica- tion of it in his unfounded phrenological speculations, which are scarcely less wild and absurd than his religious delirium appears to be. [Not really so wild as I rashly imagined that comes of giving an opinion of an author without having read him properly.] However, though one may suspect Mr. Mill to be unfortunate in his ignorance, or entirely mistaken in his estimate, of the physiological method, one cannot fail to profit by the study of his arguments on behalf of the psychological method, and by his exposition of its merits. By parading the whole force of the reasons in favour of it, he has exhibited, not so much its strength as its wenkncss, and has undesignedly given important assistance to the physiological method. For the reasons why he has not been convincing, and why this chapter has been left unmodified, I may refer to the arguments set forth in a review of his "Examination of Sir W. Hamilton's Philosophy" in the Journal of Mental Science for January 1866. "Mr. Mill," it is there said, "has a high opinion of the psycho- logical method of inquiry into mental phenomena, and thinks Comte 76 THE PHYSIOLOGY OF MIND. [CHAP. L to have committed a great error in discarding it. Whether that be true or not is not the question now ; we may admit it to be true, and still ask whether it is a sufficient reason for ignoring those important results of the physiological method of research which bear vitally on psychology ; whether, in fact, because a certain method has some worth, it can therefore afford to dispense entirely with the aid furnished by other methods." And again : " The present complaint against Mr. Mill is that he takes no notice of the effects of recent scientific conceptions on the questions referred to philosophy ; that he goes on exactly as he might have gone on if he had lived in the days of Aristotle ; that at a time when a new method, highly fertile in fact and of more fruitful promise, was available, he persists in trying to do, by the old method, what Plato, Descartes, Locke, Berkeley, and a host of others have not done. Now, we have not the slightest faith that ten thousand Mills will, following the same method, do what these great men have not done; but there can be no question that, had Mr. Mill chosen to avail himself of the new material and the new method, which his great predecessors had not in their day, he would have done what no other living man could have done." CHAPTER II. THE MIND AND THE NERVOUS SYSTEM. '* That -which fere fives is a part of nature as truly as the objects of perception which act on it, and, as a part of nature, is itself an object of investigation purely physical. It is known to us only in the successive changes which constitute the variety of our feelings : but the regular sequence of these changes admits of being traced, like the regularity which we are capable of discovering in the suc- cessive organic changes of our bodily frame. There is a Physiology of the Mind, then, as there is a Physiology of the Body a science which examines the phenomena of our spiritual part simply as phe- nomena, and from the order of their succession, or other circum- stances of analogy, arranges them in classes under certain general names ; as, in the physiology of our corporeal part, we consider the phenomena of a different kind which the body exhibits, and reduce all the diversities of these under the names of a few general Func- tions." Sketch of a System of Philosophy of the Human Mind, by T. Brown, M.D. THE crude proposition that the brain secretes thought as the liver secretes bile has been the subject of much ridicule to those who have not received it with out- cries of disapprobation and disgust.* Assuredly it is not an exact expression of the facts ; one may rightly admit the brain to be the principal organ of mind without ac- cepting the fallacious comparison of mental function * "Nous concluons avec la mcme certitude que le cerveau dige're en quelque sort les impressions ; qu'il fait organ ; quement la secre- tion de la pensee." Rapport du Physique et du Moral de F Ilomme, par P. J. G. Cabanis. 5 78 THE PHYSIOLOGY OF MIND. [CHAP. with biliary secretion. Here as elsewhere, confusion is bred by the common use of the word " secretion " to ex- press, not only the functional process but the secreted product, both the insensible vital changes and the tangible results of them. Let us begin with the endeavour to fix, with as much precision as possible, what we mean by mind. In the first place, mind, viewed in its scientific sense as a natural force, cannot be observed and handled and dealt with as a palpable object ; like electricity, or gravity, or any other .of the natural forces, it is appreci- able only in the changes of matter which are the con- ditions of its manifestation. Few, if any, will now be found to deny that with each display of mental power there are correlative changes in the material substratum ; that every phenomenon of mind is the result, as manifest energy, of some change, molecular, chemical, or vital, in the nervous elements of the brain. But we have to deal here with matter the chemical nature of which is extremely complex and obscure; for notwithstanding the labour which has been given to the chemical analysis of the brain and nervous system, and, notwithstanding that we are sure of its chemical elements, very little is yet known exactly of the actual composition of nerve element. This much, however, is certain : that its constituents are of a very complex character, easily undergo decomposition, and, being compounded largely of carbon and hydrogen, have a high oxidation value. It is probable that a chemical synthesis is effected in the substance of nerve, through which the nutrient material brought by the blood is finally converted into highly complex and unstable albuminoid compounds ; these representing a great value of potential energy, which becomes actual through their decomposition during function. The compounds named Cerebrin, Cerebrinic acid, Lecithin, and the various fats containing phosphorus, which have been discovered in ii. 1 THE MIND AND THE NERVOUS SYSTEM. 79 the brain, have been supposed, indeed, to be derived from the disintegration of a more complex substance named Protagon, having a chemical composition re- presented by the formula C 232 H 240 N 4 PO 44 .* Whether that be so or not must be decided by future research ; meanwhile, we are content to believe that without oxida- tion we can no more have thought from brain than we can have flame from fuel. The so-called extractives of nerve further testify to change or retrograde metamorphosis through functional activity ; for there are found lactic acid, kreatin, uric acid, probably also hypoxanthin, and, representing the fatty acids, formic and acetic acids. These products are like those which are found in muscle after its functional activity : in the performance of an idea, as in the perform- ance of a movement, there is a retrograde metamorphosis of organic element ; the display of energy is at the cost of highly organized matter, which undergoes degeneration or passes from a higher to a lower grade of being ; and the final retrograde products are, so far as is at present known, somewhat similar in muscle and nerve. While the con- tents of nerves, again, are neutral during rest in the living state, they become acid after death and after great ac- tivity during life : the same is the case also with regard to muscle.t Furthermore, after prolonged mental exercise, the products of the disintegration of nerve element, into the composition of which phosphorus enters largely, are recognised in an increase of phosphates in the urine ; while it is only by supposing an idea to be accompanied by a correlative change in the nerve-cells that we can * The constitution of Lecithin has been represented by the formula C M H 90 Nl'O 9 ; that of Cerebrin by the formula C 37 II 33 NO,. t During putrefaction the brain furnishes acid products, among which are recognised oleic, margaric, phosphoglyceric and phos- phoric acids. 8o THE PHYSIOLOGY OF MIND. [CHAP. explain the exhaustion following excessive mental work and the breaking down of the brain in extreme esses. These things being so, what is it which in a physio- logical sense we designate mind ? Not the material pro- ducts of cerebral activity which pass as excretions into the blood, but the marvellous energy which cannot be grasped and handled. The energy which is mind may more properly be compared with the energy which is muscular function. Here, then, is manifest a fallacy of the statement that the brain secretes thought as the liver secretes bile. It is plain that the tangible results of the brain's activity, the waste matters which pass into the blood for assimilation by tissues of a lower kind and for ultimate excretion from the body, might not less rightly be called the secretion of the brain, and be com- pared to the bile, than the intangible energy displayed in the mental phenomena. That there is a consumption of matter during function, not otherwise than as there is a consumption of fuel in the steam-engine, and that the energy in both cases is produced thereby, is beyond doubt ; but whether the sub- stance of the nerve-cell itself suffers any waste is not so certain. It has been supposed that it is the material supplied by the blood which is chiefly consumed during function, not the substance of nerve-cell, in like manner as it is the fuel, not the steam-engine, which supplies the necessary force. But if this were so, why should the nerve-cell be so soon exhausted by work, and require re- pose in order to recruit if we may not say, repair itself? And why does function once exercised leave behind it a disposition to future function, unless there be some molecular disintegration of nerve which is made whole by nutrition ? It is found by experiment that if the vagus nerve of an animal be stimulated, so as to make the heart beat slowly, it will continue to beat for a long time ; but if galvanism be applied in such a way as to II.] THE MIND AND THE NERVOUS SYSTEM. 81 quicken the heart's pulsations, it quickly becomes ex- hausted and stops ; owing, it would seem, to exhaustion of its motor nerve-centres, which stimulation of the vagus prevented by diminishing somehow the changes in them. Then again, the appearance of Lecithin and of the other similar complex compounds in such quantities as are met with in the brain would indicate that there is something more going on than a mere deposit of material from the blood and a consumption thereof would point, in fact, to some disintegration of the nerve substance itself; so that it is certainly a legitimate sup- position that they may be supplied to the brain ready made for consumption. However, similar compounds have been obtained from the blood, lymph, yolk of egg, and the spermatic fluid. By the old writers it was said that the "vital spirits" were secreted from the blood in the brain and were diminished or exhausted by frequent or prolonged use. With the necessary change of terms, that is probably very much what happens. The elements of nerve substance are secreted from the blood in the nerve-cells, and, undergoing decomposition during function, are diminished or exhausted by frequent or pro- longed use. It may be that there is something in the nerve-cell which is fixed and forms a sort of permanent framework, and that a part is unstable and transitory, being perpetually decompounded during function and recompounded during rest The fact is, that we cannot sever a nerve-cell from its medium ; tha' which it takes into itself from the blood is an essential part of its nature and function without it, it could not be a living nerve-cell ; and it is to make an absolute division which exists not in nature when we affirm that the material consumed in function belongs either exclusively to the blood or to the nerve-cell. Secondly, it is needful, in order to avoid confusion, to apprehend the exact signification of what is understood by 8a THE PHYSIOLOGY OF MIND. [CHAP. the common and vague use of the word mind. It is really a general term acquired by observation of and abstraction from the manifold variety of mental pheno- mena : by such observation of the particular phenomena and appropriate abstraction from them we get, as an ultimate generalization, the general conception or the, so to speak, essential idea of mind. An illustration will help to exhibit what I mean. The steam-engine is a complicated mechanism, of the construction and mode of action of which many people know very little, but it has a very definite function of which those who know nothing of its construction can still form a sufficiently distinct conception ; the co-ordinate integral action of the steam-engine, as we conceive it, is different from the nicely-adjusted mechanism, or from the action of any part of it. But the function of the engine is dependent on the mechanism and on the co ordinate action of its parts, as well as on the supply of suitable fuel, cannot be dissociated from these, and has no real existence apart from them, though it may exist separately as a conception in our minds. By observation of the mechanism and appropriate abstraction we get the essential idea of the steam-engine, a fundamental idea of it, which, as our ultimate generalization, expresses its very nature as such, containing, as Coleridge would have said, "the inmost principles of its possibility as a steam-engine." So likewise with regard to the manifold phenomena of mind : by observation of them and abstraction from the particular we get the general conception or the essential idea of mind, an idea which has no more existence out of the mind than any other abstract idea or general term. Because we can form the general conception of mind, it does not follow that mind can exist apart from the complex organization of the brain and its suitable blood-supply ; we have no warrant in science or in logic for such an inference. In virtue, however, of that powerful tendency II.] THE MIND AND THE NERVOUS SYSTEM. 83 in the human mind to make the reality conformable to the idea, a tendency which has been at the bottom of so much confusion in philosophy, this general conception has been converted into an objective entity and allowed to tyrannize over the understanding. A metaphysical abstraction has been made into a spiritual entity, and a complete barrier thereby interposed in the way of posi- tive investigation. Whatever be the real nature of mind and concerning that it is as vain to speculate as concerning the real nature of gravitation, electricity, or chemical affinity it is most certainly dependent for its every manifestation on the brain and nervous system ; and now that scientific research is daily disclosing more clearly the relations between it and its organ, it is plainly most desirable to guard against the common metaphy- sical conception of mind, by recognizing the true subjec- tive character of the conception and the mode of its origin and growth. A third important consideration is that mental power is truly an organized result, not, strictly speaking, built up, but matured by insensible degrees in the course of life. The brain is not, like the liver, the heart and other internal organs, capable, from the moment of birth, of all the functions which it ever discharges j for while, in com- mon with them, it has a certain organic function to which it is born equal, its high special character in man as the organ of conscious life, the supreme instrument of his relations with the rest of nature, is developed only by a long and patient education. Its functions are developed by education in the individual as they have been de- veloped in the race by the gradual results of education through the ages. If we are inclined to feel surprise that so great a result should be accomplished in the in- dividual in so short a time, we shall do well to reflect upon first, the rich inheritance of other men's labour, ' the capitalized experiences,' which he has in the constitution 84 THE PHYSIOLOGY OF MIND. [CHAP. of his brain ; and, secondly, the vast amount of human labour and experience which is concentrated in what we call education that is, in the means and appliances brought to bear even on the humblest child ; for these means and appliances represent the accumulated acquisi- tion of ages of human struggle. The very language which it is taught embodies the gains of countless ages of progressive adjustment of the human organism to its environment. Though the brain, then, is formed during embryonic life, its highest development only takes place after birth; and, as will hereafter appear, the same gradual progress from the general to the special which is ex- hibited in the development of the organ is witnessed in the development of our intelligence. How inexact and misleading in this regard, therefore, is any comparison between it and the liver ! Nevertheless, it must be distinctly laid down that mental action is as surely dependent on the nervous structure and its due supply of suitable blood as the function of the liver confessedly is on the hepatic struc- ture and its blood-supply : that is the fundamental prin- ciple upon which the fabric of a mental science must rest.* The countless thousands of nerve-cells which form so great a part of the -delicate structure of the brain are undoubtedly the centres of its functional activity : we know right well from experiment that the ganglionic nerve-cells scattered through the tissues of organs, as for example through the walls of the intestines and the * Strangely enough, some philosophers in Germany now maintain that the proposition "that all conscious mental activity can only take place as a function of the brain " is unassailable, but that it is not true of unconscious mental activity and of the impulses and in- tuitions which it produces. " Uber die unbewusste Geistesthatigkeit dagegen sagt er gar nichts aus, sie bleibt also, da alle Erscheioungen ihre Unabhangigkeit von den IIirnfunction.cn beweisen, als etwas Selbststiindiges bestehen, und nur die Form des Bewusstsein erscheint durch die Materie bedlngt" HARTMANN, p. 388, 3rd ed. ii.] THE MIND AND THE NERVOUS SYSTEM. 85 structure of the heart, are centres of nerve force minis- tering to their organic action ; and we may confidently infer that the ganglionic cells of the brain, which are not similarly amenable to observation and experiment, have a like function. Certainly they are not inexhaustible centres of self-generating force ; they give out no more than what they have in one way or another taken in ; they receive material from the blood, which they assimi- late, or make of the same kind with themselves ; a correlative metamorphosis of energy necessarily accom- panying this upward transformation of matter, and the nerve-cell thus becoming, so long as its unstable equili- brium is preserved, a centre of statical power of the highest vital quality. The maintenance of the equili- brium of nerve element is the condition of latent thought it is mind statical; the manifestation of thought in- volves the change or destruction of nerve element. The nerve-cell of the brain, it might in fact be said, repre- sents statical thought, while thought represents dy- namical nerve-cell, or, more properly, the energy of nerve-celL I do not go then farther than fncts warrant when I de- clare the following propositions to be established in mental science : (a.) When a thought occurs in the mind there necessarily occurs a correlative change in the grey matter of the brain ; without it the thought could not arise, and with it cannot fail to arise, (b.) This change consists in a movement of some kind, which, in our present defect of knowledge, everyone may conceive of as he pleases. The nearest analogy is probably to be found in the com- pounds, and compounds of compounds, of vibrations in music ; at any rate this analogy will help us, coarse and defective as it may be, to frame some kind of intuition of what takes place. Unzer called these movements material ideas, and divided them into object-presentative and repre- sentative according as they were excited from without 80 THE PHYSIOLOGY OF MIND. [CHAT. and from within. They are determined in direction by the established nerve-paths the fibres and the connections of cells, (c.) The movement takes time ; the time occupied is sometimes longer, sometimes shorter, but is always an appreciable period, as will be pointed out later on. (//.) It requires a regular supply of properly constituted blood. (e.) It is arrested or prevented by an interruption of the continuity of nerve, or by slight modifications of its struc- ture, as by section of or pressure on a nerve, or by com- pression of the brain. (/.) The movements are impeded and finally prevented by the exhaustion produced by frequent or prolonged exercise without due intervals of rest. So far from discussing whether mind is a function of brain, the business which science now has immediately before it is the mofe special investigation of the condi- tions of activity of the ganglionic nerve-cells or groups of nerve-cells and of the fibres which unite them into mul- titudinous plexuses. If we look to those humbler animals in which nervous tissue makes its first appearance, it is plain that the simple mode of its existence in them allows of no other manner of proceeding ; if we trace upwards the gradual increasing complication of the nervous system through the animal kingdom, i.t is evident that such manner of proceeding is the only one to furnish the materials of a comprehensive and sound induction ; and if we duly weigh the results of physiological experiment and pathological research, it is no less certain that we must discard scientific investigation altogether in cerebral physiology, if we reject the ganglionic nerve-cells of the brain as centres of mental force. In the lowest forms of animal life nerve does not exist: the Protozoa and many of the Zoophytes are, so far as can be ascertained, destitute of any trace of nervous system. The most simple beings consist of an apparently uniform, homogeneous substance, by means of which all ii.] THE MIND AND THE NERVOUS SYSTEM. 87 their functions are executed.* They are nourished without digestive organs ; breathe without respiratory organs ; feel and move without organs of sense, without muscles, without nervous system. The stimulus which the little creature receives from without produces some change in the molecular relations of its almost homo- geneous substance, and these insensible movements would seera to amount collectively to the sensible move- ment which it makes. The perception of the stimulus by the creature is the molecular change which ensues, the imperceptible motion passing, by reason of the homogeneity of its substance, with the greatest ease from element to element of the same kind, as it were by an infection, or as happens in the sensitive plant; and the sum of the insensible molecular motions, as neces- sarily determined in direction by the form of the animal, or by some not yet recognised cause, results in the visible movement. The important researches of Graham into the colloidal condition of matter have proved the neces- sity of considerable modification in the common concep- tion of solid matter : instead of the notion of impenetra- ble, inert matter, we must substitute the idea of matter which, in its colloidal state, is penetrable, exhibits energy, and is widely susceptible to external agents, " its existence being a continued metastasis." f This sort of energy is not a result of chemical action, for colloids are * One must guard against the assumption that any kind of living protoplasm is really homogeneous. Hyaline it may be, but we know not how complex its structure may be. It is possible that sometimes tracks in the apparently homogeneous substance may be so far differentiated as to be adapted to convey impressions, and thus to serve the primitive function of nerve, although we cannot observe the least difference in structure. As nerve is formed by differentiation from apparently homogeneous substance, there must be a period when we cannot say with certainty whether what we see is nerve or is not. t Philosophical Transactions ,1862. 88 THE PHYSIOLOGY OF MIND. [CHAP. singularly inert in all ordinary chemical relations, but a result of its unknown intimate molecular constitution ; and the undoubted existence of colloidal energy in organic substances which are usually considered inert and called dead, may well warrant the belief of its larger and more essential operation in organic matter in the state of instability of composition in which it is when under the condition of life. Such energy would then suffice to account for the simple uniform movements of the homo- geneous substance of which the lowest animal consists ; and the absence of any differentiation of structure is a sufficient reason of the absence of any localization of function, and of the general uniform reaction to different impressions. But it will be observed that even the movements of these simplest creatures, in which there is not the least indication of the elements of a nervous system, are not entirely vague, confused, and indefinite ; they present certain indications of adaptation to func- tional ends ; they are definite in relation to their medium. They evince, in fact, the fundamental property of living matter, which is manifest even in a mere speck of living protoplasm namely, adaptive motion in response to im- pressions, co-ordination of variety to unity of action, a principle of individuation. With differentiation of tissue and increasing complexity of organization, which are met with as we ascend in the animal kingdom, the nervous tissue appears, but at first under a very simple form.(') Wherever differentiated parts of an organism are combined for a common end, the co- operation is effected by a nervous system. Its simplest type or unit may be represented as two fibres that are connected by a nerve-cell or a ganglionic group of nerve- cells ; the fibres are apparently simple conductors, and might be roughly compared to the conducting wires of a telegraph, while the cell, being the centre in which nerve force is generated, may be compared to the telegraphic II.] THE AtlND AND THE NERVOUS SYSTEM. 89 apparatus ; the effect which the stimulus of the afferent or centripetal nerve excites in it is transmitted along the efferent or centrifugal nerve, and therein is displayed the simplest form of that reflex action which plays so large a part in animal life.* This type of structure is repeated throughout the complex nervous system of all the higher animals : the fibres with their junction-cells form units from the multiplication and complex arrangement of which the various and most complicated nervous structures are built up. Cut across the afferent nerve or otherwise in- terrupt its continuity, the impression made upon its terminal fibres cannot reach the centre ; cut across the efferent nerve, the central excitation is powerless to in- fluence the muscles or parts to which it is distributed. Not all the passion and eloquence of a Demosthenes * The fibres act as conductors, and have like physiological properties. Fhilippeau and Vulpian (Comptcs Rendus, vL) and Roscnthal (Cent- ralblatt, No. 29, 1864) have succeeded in uniting the central end of the cut lingual nerve, the sensory nerve of the tongue, with the peri- pheral end of the cut hypoglossal, the motor nerve of the tongue. The natural course of a stimulus is upwards in the lingual, down- wards in the hypoglossal. But after the union has taken place, stimulation of the central part of the lingual produced contractions of the tongue, such as normally follow stimulation of the hypoglossal. Thus it is proved that the end of a sensory nerve may be united with the end of a motor nerve, and when the union is complete, excitation of the sensory may be transmitted to the motor fibres. Inversely, stimulation of the peripheral end of the hypoglossal produced evidence of pain. If the end of a rat's tail be grafted into the skin of its back, and when the graft is completed, if the tail be cut through at its base, the animal will, at the end of some months, feel a pinch of the grafted tail and turn round to bite (Bert). The irritation of the nerve which, before the operation, travelled from the end to the base of the tail, i.e. centripetally, now travels in the opposite direc- tion, still centripetally. It would seem that, as Mr. Lewes has in- sisted, the neurility is the same in all nerves ; the difference of function being due, not to difference of physiological properties, but to differences of connections of the fibres. See also Lemons sur la Physiologic Generate et Compared du Syslcme Nerveux, par A. Vulpian. 1866. 90 THE PHYSIOLOGY OF MIND. [CHAP. could force its way outwards into words, if the motor nerves of the tongue were cut across ; he would grimace vainly, like a speechless idiot, if a slight molecular change in their structure sufficient to bar conduction were pro- duced. Owing to the differences of kinds of tissue and to the specialization of organs in the more complex animal, there cannot plainly be that intimate molecular sympathy between all parts which there is in the homogeneous sub- stance of the simplest monad ; the easy motion, as by an infection, from particle to particle, where the substance is of the same kind, cannot take place in the heteroge- neous body, where the elements are of a different kind : accordingly special provision is required for insuring com- munication between different parts, and for co-ordinating and harmonizing the activity of different organs. The animal must be rendered capable of associating a number of distinct actions for definite ends. This function, necessitated by the physiological division of labour, the nervous system subserves ; and we might compare it to that which the gifted generalizer fulfils in human development : he grasps the results of the various special investigations which a necessary division of labour enforces, brings them together, and elaborates a result in which the different lines of thought are co-ordinated, and a unity of action is marked out for future progress. The nervous system effects the synthesis which the specializa- tion of organic instruments in the analysis of nature renders necessary ; it represents the integration of relations, and of relations of relations, of things in a gradually ascend- ing scale ; it is the highest expression of that principle of individuation which is the characteristic feature of life in all its forms, but most manifest in its highest forms. To this function it is well adapted, first, by the extent of its distribution, and, secondly, by its exceeding sensibility, whereby an impression made at one part is soon felt at a distance from the place where it is made. if.] THE MIND AND THE NERVOUS SYSTEM. 91 With the increasing complexity of organization which marks the increasing speciality of organic adaptation to external nature, or, in other words, which marks an ascent in the scale of animal life, there is a progressive compli- cation of the nervous system : special developments ministering to special purposes take place. The fibres appear to preserve their characters as simple conduc- tors, while a development of special structures at their peripheral and of special ganglionic cells, or of special connections of cells, at their central endings reveals the increasing speciality and complexity of function. Upon the special terminal structures, which are, as it were the instruments of analysis, depends the kind of the impres- sion made; they are adapted to the special nature of the external impressions which they take up, while the kind of impression that is perceived and the character of the reaction thereto are determined by the nature of the nerve-cells with which the central end of the nerve is connected. Accordingly, we find that with the appear- ances of the organs of the special senses, as we mount in the scale of animal life, there is a corresponding increase in the ganglionic centres, which, being clustered together, form the primitive rudiments of a brain, and represent, in the main, those sensory ganglia which in man lie at the base of the brain between the decussation of the pyramids and the floors of the lateral ventricles. It is not known with certainty when the different organs of the special senses severally make their first appearance ; they are at first very rudimentary, and are clearly special- ized evolutions from the most general sense, that of touch. The skin is an organ of sense which extends over the outside of the body, and perceives by actual contact with the objects that affect it ; the other senses are probably nothing else than differentiated involutions of it, complex cuticular structures, which are placed more or less within the body, and they perceive without actual r)2 THE PHYSIOLOGY OF MIND. [CHAP. contact ; touch then may be justly held to be the primi- tive, the fundamental sense, that which is the mother tongue of knowledge. In the highest animals the terminal fibres of the nerves of the special senses enter cells which have the character of epithelial cells, and the forms of which are modified according to the nature of the external impressions which they are fitted to receive. This epithelial character of the terminal cells is best seen in the organs of smell and taste, but it is manifest also in the organ of sight ; for the so-called staffs and cones of the retina, which are alone sensitive to light, the nerve-cells themselves of the retina and the optic fibres being not, are regarded as metamorphosed epithelial cells.* In some of the lower creatures the organs of hearing, smell, and taste are manifestly special modifications of certain portions of the covering of the body, and the organ of sight itself, when it appears in its earliest and simplest form, is nothing more than the terminal ending of a nerve, surrounded by a few pig- ment granules, in the epithelial cells of a fold or recess of the skin. Even in the Amphioxus, which is a vertebrate animal, the eyes are two small pigment spots, the organ of smell is a cup-shaped depression at the fore end of the body, and no organ of hearing is discoverable. As we ascend in the scale, structures adapted to the reception of particular impressions, as of light, of sound, of touch, become more special, and render the higher animal capable of more numerous, special, and complex rela- tions with external nature. There is a diffusion through the entire substance of the simplest creatures of physio- logical properties which are specialized and localized ill the higher animals.f * Wundt, Grundzuge der physiologischen Psychologie, p. 318. + The Hydra exhibits a sensitiveness to light, although it has no special sense of sight ; it shuns the dark and chooses the light side of the vessel in which it is placed. Some again of the zoophytei II.] THE MIND AND THE NERVOUS SYSTEM. 93 Not till we arrive as high as the fishes do we discover anything more in the brain than sensory ganglia con- nected with the origins of nerves ; below them there is no trace of cerebral hemispheres or brain proper. It is plain, then, that the cerebral hemispheres are not essential to sensation or the motor reaction to sensa- tion ; for they are altogether wanting where both these functions are displayed in a lively and vigorous way. To the simpler relation between the individual organism and external nature which is denoted by reflex or excito-nwtor that have no definite organs of hearing contract themselves when vibrations of sound are propagated through the medium in which they are. They feel the vibrations, though the feeling is no doubt different in quality from that which a well-developed organ of hearing would impart. " Polypes, zoophytes, and other infusory animalcules that have neither brain nor nerves, feel and move without a nervous system, because the Author of Nature appears to have endowed the pulp of which their bodies are composed with the faculty of sen- sation and motion, just as the medullary pulp of the nervous system alone, of all the organs of our body, is endowed with that faculty." PROCHASKA, On the Nervous System, p. 387. Syd. Soc. Transl. When a special sense fails in man, the general sensibility may partially replace it. " I have known several instances, " says Abercrombie, " of persons affected with that extreme degree of deaf- ness which occurs in the deaf and dumb, who had a peculiar suscepti- bility to particular kinds of sounds, depending, apparently, on an impression communicated to their organs of touch or simple sensation. They could tell, for instance, the approach of a carriage in the street without seeing it, before it was taken notice of by persons who had the use of all their senses." On the Intellectual Powers. Kruse, who was completely deaf, nevertheless had a bodily feeling of music ; and different instruments affected him differently. Musical tones seemed to his perception to have much analogy with colours. The sound of a trumpet was yellow to him ; that of a drum, red ; that of the organ, green, &c. Early History of Mankind, by J. B. Tylor. In his Reminiscentes of the Opera, Mr. Lumley tells of a friend who used to compare the voices of the different celebrated singers to different colours, distinguishing them so. It is an old saying of a blind man, that he thought scarlet was like the sound of a trumpet. No doubt colours have different psychical effects, red having an exciting and blue a calminc; effect. 94 THE PHYSIOLOGY OF MIND. [CHAP. action, there now succeeds the more complex relation of sensory stimulus and sensori-motor reactions in place of general reaction to stimulus, discriminations of impres- sions and corresponding special reactions by virtue of specially adapted structures are witnessed. This condition or stage of the development of the nervous system, which is natural and permanent in so many of the lower ani- mals, corresponds to that artificial state of things which may be produced experimentally in a higher animal by depriving it of its cerebral hemispheres. The kind of function manifest is strictly comparable to that of the infant's mental life in the early brief stage before the cerebral hemispheres have come into action, or to those phenomena of mental life sometimes displayed by the adult, as for example by the somnambulists, when the influence of the cerebral hemispheres is nearly sus- pended. Here is suggested a reflection : how important it is clearly to distinguish in thought and to denote by language special features, which, being included under, or described by, a general term, are so commonly con- founded. What different perceptions or reactions, for example, are confounded by the loose way of using the word sensibility ! The infusory animalcule, which has no nervous tissue, is said to be sensible of a stimulus ; the higher animal, with its special senses, to be sensible of light, or of sound, as the case may be, and, if made to suffer, to be sensible of pain ; while it is common enough to speak of man being sensible of pleasure, horror, or disgust, according to the nature of the active ideas. Using the generic term sensibility to express the fundamental reaction, as we may perhaps properly do, it is highly important that we go on further to distinguish by appropriate terms the special differences ; the sensi- bility of pain is not the sensibility of sense, nor is the sensibility of the infusory animalcule equivalent to ii.] THE MIND AND THE NERVOUS SYSTEM. 95 either of these. So far we have taken pains to distinguish that form of sensibility and reaction proper to the lowest animals, which might be called irritability ; that form of reaction, or rcfttx action, which is the lowest expres- sion of nervous function ; and that form of reaction to which the sensory ganglia minister, which is rightly called sensorial. It is found to be no easy matter to form a distinct conception of the relations of consciousness to these dif- ferent forms of sensibility. In order to do so, we must at the outset abandon the notion of consciousness as something of constant quality, which either is or is not, and must realise the truth that it may exist in different degrees, ranging from the highest display of self-conscious- ness through grades of sub-consciousness down to uncon- sciousness. In the ordinary vague use of the word consciousness, what is implied, though not explicitly asserted, is the reflex consciousness which is properly self-consciousness. There is certainly a vast difference between this highest development of consciousness and that kind which accompanies the sensation of one ol the special senses ; much more between it and the con- sciousness, if there be any, which accompanies the sensibility of the infusory animalcule. The latter they place on too high a level who rank it with self-con- sciousness, as they practically do when they vaguely apply the same word to both : deriving their notion of consciousness from experience of self-consciousness, they apply it to the sensibility of the lowest creatures. It would be hardly less absurd to attribute to them the possession of the complex nervous system which is essential to the manifestation of self consciousness. We might say, it is true, that as there are in the tissues of the lowest animals the elements of a nervous system which is in process of time differentiated from them, so in the sensibility which they display there are 96 THE PHYSIOLOGY OF MIND. [CHAP. the elements of those special sensations and of that self- consciousness which appear as their respective organs are individualized in the highest animal ; but because we can, by a survey of the course of evolution through the ages, thus foresee in the germ potentially the full fruit, we are not therefore qualified to find the properties of the fruit in the germ : we do wrong to discover in the functions of the lowest organisms the far more specialized functions of the highest organisms, and to translate those into terms of these. Generation is a function which is as widely extended as sensibility through the animal king- dom, but no one dreams of discovering the phenomena which are part of the function of generation in man in the phenomena of generation which the polype displays. The question is whether we ought to attribute con- sciousness at all to the sensibility or susceptibility of creatures which have no nervous system. The adapted impression certainly produces a definite effect which issues in a definite movement, either to avoid it, if in- jurious, or to embrace it, if profitable ; but what pretence is there to affirm that consciousness has any part in these events ? The phenomena of our own organic life, which are of a much higher order, point the other way ; we are not conscious of having a liver, which neverthe- less produces marked effects upon our mental moods; we are not conscious of the very powerful influence which it is certain that our sexual organs exert upon our ideas and feelings ; we are not conscious of a thousand movements which we make daily, and which nevertheless relieve some uneasy, or occasion some easy, feeling. I know it may be said that we are conscious of these things but do not attend to them ; to which I am tempted to reply that it is the attention which is the conscious- ness, and that a consciousness which is not conscious because it does not attend is not properly called con- sciousness. I know no reason why those who attribute H.] THE MIND AND THE NERVOUS SYSTEM. 97 consciousness to the sensibility of the lowest nerveless creatures should deny it to sulphuric acid when, by virtue of its superior affinity for barium, it goes definitely to work to displace nitric acid from its combination with that base. It is in fishes that the rudiments of cerebral hemi- spheres first appear. In them they are represented by a thin layer or projection of nervous matter in front of the optic lobes, covering the corpora striata and the optic thalami ; in the Amphibia they have already increased somewhat in size;* in Birds the optic lobes are pushed out to some extent by their further increase; in the Mammalia they begin to cover the optic lobes, and, as we ascend in the scale of life, gradually increase back- wards until, in some of the higher monkeys and in man, they entirely cover the cerebellum. In this ascent through the series of vertebrate animals, it is found that the relations of the sensory ganglia remain alike throughout, the chief differences being differences in the relative size of them. Their functions as primary constituents of the brain may then fairly be reckoned the same in all the vertebrata, and indeed in all the animals in which they exist. As the hemispheres appear as secondary constituents secondary, be it noted, in the order of development, but primary in dignity we may rightly conclude their function to be secondary in the order of development to that which the primary con- stituents or sensory ganglia fulfil. The impressions received by the sensory centres when these do not react directly outwards, as they may do where hemispheres exist and as they must do where hemispheres do not exist, are in fact passed onwards in the brain to the cells which are spread over the hemispheres, and are there * The Perenni-branchiate reptiles retain the fish character of brain all their lives ; the Batrachians have it only during their tadpole state. 98 THE PHYSIOLOGY OF MIND. [CHAP. further fashioned into what are called ideas or concep- tions. If the excitation is conveyed to .the sensory centre, passes thence to a connected motor centre, and is finally discharged along the motor nerve in motion if, that is, it passes along what may be called the seasonal arc the function is sensation and sensori-motor action : if, however, the impression is conveyed to the higher ideational centres in the hemisphere, passes thence to motor centres, and is finally discharged along a motor nerve in action if, that is, it passes along the ideational arc it is perception and volition. Here then we come to another kind of sensibility with its appropriate reaction, to which special nervous centres minister; and it is known as perception, or, more strictly, ideational percep- tion. As the hemispheres have this function and are not necessary to sensation, it is quite in accordance with what might be predicted, that, as experiments prove, they are insensible to pain, and do not give rise to any display of that kind of feeling when they are injured.* They have, agreeably to their special nature, a sensibility of their own to the ideas that are fashioned in them ; so that these may be pleasurable or painful or have other particular emotional qualities. Emotion is strictly, per- haps, the sensibility of the supreme centres to ideas. Observation of the mental phenomena of those ani- mals in which cerebral hemispheres exist confirms fully the foregoing view of their function and import In Fishes there is the first distinct appearance of simple ideas and of the lowest rudiments of emotion ; carp will collect to be fed at the sound of a bell, thus giving evidence of the association of two simple ideas ; and a shark, suspicious of mischief, will avoid the baited * Those who have made the painful experiment tell us that an animal which makes violent movements while the skin is being cut and the roof of its skull removed, remains quite quiet while its hemispheres are being sliced away bit by bit. II.] THE MIND AND THE NERVOUS SYSTEM. 99 hook. In Birds, conformably to the increased develop- ment of the hemispheres, the manifestations of intelli- gence are much greater ; the tricks which some of them may be taught are truly marvellous, and those who teach them know well how much different birds differ in intelli- gence and temper. We look on such performances as marvellous, because of our ingrained disposition to think surprising all manifestations of intelligence in animals below us in the scale of life ; but if we bear in mind the fundamental plastic property of nerve element by which it receives impressions and grows to its modes of exercise, we may abate somewhat our surprise, and see reason to think that animals might be made capable of much higher displays of intelligence if only we took pains to educate them through a few generations. Nor are simple emotional exhibitions wanting amongst birds; very evident at times is the feeling of rivalry or jealousy in canaries, and there are undoubted instances on record in which an orphan bird has owed its life to the kindly care of birds of a different species.* In Mammalia a gradual advance in intelligence may be traced from very humble manifestations up to those highest forms of brute reason which assuredly differ only in degree from the lowest forms of human intelligence.! Consider how deeply meditative the elephant sometimes shows itself ; how apt in cunning schemes the monkey is ; how plainly in the dog an inhibitory conception often intervenes between the sensation and the usual respondent move- ment, so that the animal refrains from doing what it has a strong impulse to do, the impression having been passed on to the hemispheres and their controlling action brought into play. It is needless to speak of the various * Anatomie Comparte Ju Systeme Nerveux, par Leu ret et Gratiolet t For examples of remarkable displays of intelligence in different animals, I may refer to a paper by me on the "Genesis of Mind" in the Journal of Mental Science, iS62. loo THE PHYSIOLOGY OF MIND. [CHAP. emotions, nay, the veritable moral feeling, displayed by the dog and other domesticated animals. A single reflection will show, what anatomy might lead us to pre- dicate, how limited must be the range of animal intelli- gence now that its development is checked by the dominating ascendency of man ; for how can animal in- telligence grow through the ages in face of a superior hostile intelligence which has taken possession of the earth, and is fast subduing all things therein to its uses ? If the fox, cunning as it is, had but the sense to learn to climb a tree, like the cat, or always to run to earth, like a rabbit, men would soon give up hunting it. But the fox, like so many men, cannot get out of the accustomed groove of automatic thought, cannot originate anything ; and, like not a few intriguing plotters, it wastes a great deal of low cunning in efforts which a little larger view of things would render quite unnecessary.* * If the fox did hit upon a discovery of the kind, it would soon be exterminated as vermin and would frustrate the design or final cause of its present existence, which presumably is to serve by its sufferings for human amusement. Some persons have thought that man was the only animal which found pleasure in inflicting torture on other animals merely for amusement, but it would seem that his next-of- kin, the monkey, takes delight in doing so when it gets the chance that it will catch a crow or pigeon and pluck its feathers off and otherwise torture it, highly gratified with its victim's struggles the while. The cat's play with the mouse might be thought perhaps not to be an original invention, but an accomplishment first taught by man, and now inherited as an instinct, which is still, however, educated in the kitten both by man and by its mother. It may be said truly that man is the only animal which, having imagination enough to realize that its victim suffers, yet delights in inflicting suffering for his sport. Therefore we cannot properly describe fox-hunting as brutal cruelty, or as barbarous cruelty, neither brutes nor barbarians having the imagination to realize the sufferings which they inflict, as civilized persons of this age presumably have ; one must call it civilized cruelty, meaning thereby the most sinful cruelty, because a sin against knowledge and right feeling. Thus much from a moral point of view. From a philosophical point of view the ILJ THE MIND AND THE NERVOUS SYSTEM. 101 As we ascend through the Mammalian series, we find that not only do the hemispheres increase in size by gradually extending backwards, but that the grey surface of them is further increased by being thrown into folds or convolutions. While the lower Mammals are entirely destitute of such convolutions, these are present, as a rule, in simple forms in the Ruminantia and the higher Carni- vora ; they are more fully developed in the marine Mam- malia, and most fully developed in the apes and in man. It is true that we cannot at present unfold an exact re- lation between the development of the convolutions and the degree of intelligence in different animals ; for the brains of the ass, the sheep, and the ox, which do not evince much intelligence, are more convoluted than those of the beaver, the cat, and the dog, which certainly evince more intelligence. But the relative size of the animals must be taken into account in such comparison. The volume of a body such as the brain which increases in size increases in greater proportion than the superficies, and the latter again in greater proportion than the diameter. Now in each natural group or order of Mammalia, the head, but especially the capacity of the skull, bears a certain proportion to the body, a proportion which re- mains pretty constant in different species ; the head of the tiger or of the lion, for example, has about the same proportion to the body as that of the cat's head to its body, although the sizes of the animals are so different. It follows then that, as the volume of the brain of the tiger in relation to the size of the body is the same as in the cat, and as the larger the brain the smaller the relative amusement is interesting ; for it is a striking instance of the survival in man of a primitive savage instinct, testifying to an animal kinship which he has not yet outgrown. Thus animal nature is avenged in some sort for the oppression which it suffers from human nature ; since it declares through man in his pride of place, in accents which cannot be mistaken, that after all he is one with his animal kind. 6 103 THE PHYSIOLOGY OF MIND. [CHAP. superficies, the superficies of the brain is proportionately greater in the cat ; and that, consequently, in order to get a proportionate extent of grey surface in the tiger, this must be convoluted in it, when it may remain nearly smooth in the smaller animal. If in two animals of equal size, and of like form of structure, the convolutions are differently fashioned, then it may be said truly that one will be more intelligent than the other in proportion as its convolutions are more numerous and complicated and the sulci deeper. Comparing the brains of different species of dogs or of anthropoid apes, it is certain, too, that the more intelligent animals have larger and more convoluted hemispheres. That proposition is true of man. The intellectual differences which exist between the Bosjesman, or the Negro, and the European are attended with differences in the extent and complication of the nervous substance of the brain. Gratiolet has carefully figured and de- scribed the brain of the Hottentot Venus, who was no idiot ; and what is at once striking in the figure is the simplicity and regular arrangement of the convolutions of the frontal lobe; they present an almost perfect symmetry in the two hemispheres, " such as is never exhibited in the normal brains of the Caucasian race," and which involuntarily recalls the regularity and sym- metry of the cerebral convolutions in the lower animals. The brain of this Bosjes woman was, in truth, inferior to that of a white woman at the normal stage of develop- ment : " it could be compared only with the brain of a white who is idiotic from arrest of cerebral development." Moreover, the differences between it and the brain of the white are unquestionably of the same kind as, though less in degree than, those which exist between the ape's brain and that of man, as Professor Huxley has pointed out.* Mr. Marshall has carefully examined a Bushwoman's * Men's Place in Nature. II.] THE MIND AND THE NERVOUS SYSTEM. 103 brain, and has found like evidence of structural inferi- ority ; the primary convolutions, though all present, were smaller than in the European, and much less compli- cated ; the external connecting convolutions were still more remarkably defective ; the secondary sulci and convolutions were everywhere decidedly less developed ; there was a deficiency of the system of transverse com- missural fibres ; and in size, and in every one of the signs of comparative inferiority, " it leaned, as it were, to the higher quadrumanous forms."* The brain of the Negro is superior to that of the Bushman, but still it does not reach the level of the white man's brain \ the weight of the male Negro's brain is less than that of the average European female ; and the greater symmetry of its convolutions, and the narrowness of the hemispheres in front, are points in which it resembles the brain of the orang-outang, as even Tiedemann, the Negro's advo- cate, has admitted. Among Europeans it is found that, other circumstances being alike, the size of the brain bears a general relation to the mental power of the individual, although apparent exceptions to the rule sometimes occur. The average weight of the brain in the educated class is certainly greater than in the uneducated ; and some carefully-com- piled tables in a valuable paper by Dr. Thurnam prove that, while the average brain weight of ordinary Europeans is 49 oz., in distinguished men it is 54*6 oz.t On the other hand, the brain is oftentimes very small in idiots ; the parts being not only smaller, but less complex, and the convolutions in particular being simpler and less * Philosophical Transactions, 1865. t On the Weight of the Human litain, by John Thurnam, M.D. ; yournal of Mental Science, April 1866. Professor Wagner has care- fully figured and described the brains of five very distinguished men. The extremely complex arrangement of the convolutions was most remarkable. The Convolutions of the Human Cerebrum, by W. Turner, M.B. 1866. 104 THE PHYSIOLOGY OF MIND. [CIIAP. developed. Mr. Marshall found the convolutions of the cerebra of the two idiots which he examined to be fewer in number than in the apes, the brains being in this respect more simple than the brain of the gibbon, and approaching that of the baboon. In fact, there are micro- cephalic idiots which present a complete series of stages in a gradual descent from man to the apes. As a general proposition, it is certainly true that we find the evidence of a correspondence between the development of the cerebral hemispheres and of the intelligence, when we examine the different races or kinds of men, as we do when we survey the scale of animal life. But in making comparisons between the brains of men in the same state of civilization we must not lose sight of the fact that quality has to be taken into account as well as quantity. An increase in the rapidity of undulations of vibrating ether makes that light which before was darkness; and it is conceivable that, in like manner, an increase in the number of vibrations in the nerve-tracts of the brain might convert stupidity into genius. A de- mented patient, whose mind seemed nearly extinguished, has in some instances recovered temporary intelligence in a marvellous manner during the excitement of a fever ; and persons who have not been remarkable for mental display will sometimes exhibit surprising intellectual sparks at the commencement of an attack of acute mania. It stands to reason that the susceptibilities of nerve element to molecular vibrations should be de- termined by that intimate condition of its nature which the word quality denotes, and should be affected after- wards by slight physical modifications of its condition. As in the series of the manifold productions of her creative art Nature has made no violent leap, but has passed by gentle gradations from one species of animal to another, and from the highest animal to the lowest man, it is not surprising that the embryonic development 1L] THE MIND AND THE NERVOUS SYSTEM. 105 of man should present indications of the general plan.* It admits of no question that man does, in the course of his development, pass through stages closely resembling those through which other vertebrate animals pass, and that these transitory conditions in him are not unlike the forms that are permanent in the lower animals; he presents us in the microcosm with an abstract of the evolution which has gone on through countless ages in the macrocosm. There is a very close morphological resemblance between the human ovum and the lowest animals with which we are acquainted, the microscopic Gregarinida ;t in both, an outer membrane contains a soft semi-fluid substance, at one end of which is a deli- cate vesicle having in it a solid particle or spot. At the earliest stages of its development no human power can distinguish the human ovum from that of a quadruped ; scrutinize it as carefully as you will with the highest * " That there should be more species of intelligent beings above us," says Locke, " than there are of visible or material below us, is probable to me from hence, that in all the corporeal world we see no chasms or gaps." But how can it be safe to apply to the unseen a generalization from the seen ? Between the corporeal and spiritual world there is, at any rate, a vast chasm or gap. t "The Gregarinida," says Huxley, "are all microscopic, and any one of them, leaving minor modifications aside, may be said to consist of a sac, composed of a more or less structureless, not very well denned membrane, containing a soft semi-fluid substance, in the midst, or at one end, of which lies a delicate vesicle ; in the centre of the latter is a more solid particle. No doubt many persons will be struck with the close resemblance of the structure of this body to that which is possessed by an ovum. You might take the more solid particle to be the representative of the germinal spot, and the vesicle to be that of the germinal vesicle ; while the semi-fluid sar- codic contents might be regarded as the yelk, and the outer mem- brane as the vitelline membrane. I do not wish to strain the analogy too far, but it is at any rate interesting to observe this close mor- phological resemblance between one of the lowest of animals and that form in which all the higher animals commence their existence." Lect. on Coinp. Anal. 1864. io6 THE PHYSIOLOGY OF MIND. [CHAT-. microscopical powers, you shall not be able to say whether it contains the potentialities of a Socrates or of a he-goat ; and, as it proceeds to its destined end, it passes through similar stages to those through which other vertebrate embryos pass. That which is true of the whole body is true also of the development of the brain. The brain of the human foetus at the sixth week may be described in general terms as consisting of a series of vesicles, the foremost of which, a double one, representing the cerebrum, is the smallest, and the hindmost, represent- ing the cerebellum, the largest. In front of the latter is the vesicle of the corpora quadrigemina j and in front again of this, the vesicle of the third ventricle, which contains also the thalami optici, and which, as development proceeds, becomes covered, as do the corpora quadrigemina, by the backward growth of the hemispheres in front of it. At this stage the human brain resembles the fully-formed brain of the fish, more closely the brain of the fcetal fish, in the small proportion which the cerebral hemispheres bear to the other parts, in the absence of convolutions, in the deficiency of com- missures, and in the general simplicity of structure. Later, about the twelfth week of embryonic life, there is a great resemblance to the brain of the bird : the cerebral hemispheres are much increased in size, and arch back towards the thalami optici and the corpora quadrigemina, though there are still no convolutions and the commis- sures are very deficient. Up to this time the cerebral hemispheres represent no more than the rudiments of the anterior lobes ; they do not yet completely cover the thalami optici, nor indeed pa? s the grade of develop- ment which is permanent in the Marsupial Mammalia. During the fourth and early part of the fifth months, the middle lobes develop backwards and cover the corpora quadrigemina; and, subsequently, the posterior lobes II.] THE MIND AND THE NERVOUS SYSTEM. 107 sprout out, so to speak, and gradually extend backwards so as to cover and overlap the cerebellum. It was upon the erroneous assumption that the posterior lobes were peculiar to man, that Professor Owen grounded his divi- sion of the Archencephala ; but it has now been proved beyond doubt that the posterior lobes exist in the apes, and that in some apes they extend as far back as they do in man. It is easy to perceive, then, that an arrest of development of the human brain at one stage or another of its formation may leave it very much in the condition of an animal brain ; and it is found in some cases, as a matter of fact, that congenital idiots have brains very like those of the monkeys. As man is thus a sort of compendium of animal nature, paralleling nature, as Sir Thomas Browne has it, in the cosmography of himself, we find exhibited in the workings of his organism all the different modes or kinds of nervous function which are met with in the animal kingdom. The so-called irritability of tissue, whereby it reacts to a stimulus without the help of nerve, may be of the same kind as that molecular energy of matter manifest in the movements of the humblest animal : whether the nerve ends outside the sarcolemma of muscle, or within it, there can be no doubt that it is not distributed to every particle of the sarcous element ; and, at any rate, when all nervous influence is withdrawn, an energy still exists sufficient to produce rigor mortis of the muscle.* * It has furthermore been maintained by Bilharz and Kiihne that the nerves pass by continuity into the muscular substance, as in the electric organs of the fishes they pass continuously into the proto- plasm of the electric plates. The controversy respecting the manner in which nerves end in muscles seems, then, likely to terminate in the conclusion that they do not end at all, but pass by continuity of substance into the sarcous elements. The observations of Kiihne and Rouget prove that the nerve fibre, reduced to its axis cylinder, penetrates the sarcolemma, and is lost The nervous filaments of insects cannot sometimes be distinguished from the other elements loS THE PHYSIOLOGY OF MIND. [CHAP. The simplest mode of nervous action in man, compar- able to that of the lowest animals that possess nerve, is exhibited by the scattered ganglionic cells belonging to the sympathetic system which are concerned in certain organic processes. The heart's action, for example, is due to the ganglionic cells dispersed through its sub- stance ; Meissner has shown that nerve-cells disseminated through the tissues of the intestines govern their motions ; and Lister thinks it probable that cells scattered in the tissues preside over the contractions of the arteries, and over the remarkable diffusion of the pigment granules which takes place in the stellate cells of the frog's skin. The separate elements of the tissue are co-ordinated by the ganglionic nerve-cells of the sympathetic system ; and these co-ordinating centres, again, are found to be under the control of the cerebro-spinal centres. In the spinal cord the ganglionic nerve cells are collected together, and so united that groups of them and con- nected groups of them become independent centres of combined movements, simultaneous and successive, in answer to stimuli ; this arrangement representing the entire nervous system of those animals in which no organs of special sense have yet appeared. The stimulus conveyed by the afferent nerve does not go directly across the cord and produce the first movement at hand, but excites the energies of a plexus of interconnected cells, which energies are expressed ultimately in the efferent or motor effect ; not otherwise than, as we shall see hereafter, a stimulus to the brain excites energies in the plexuses of its convolutions which appear in con- sciousness as reflection and issue finally in voluntary movement . ^ Still higher in the scale of the nervous system, the sen- by means of the m'croscope. Pfliiger has discovered that the nerves to the glands penetrate the walls of the cells, and, as he believes, end in the nuclei. ii.] THE MIND AND THE NERVOUS SYSTEM. 109 sory ganglia, consisting of multitudes of cells differentiated by their special connections, are clustered together, forming a very important part of the brain of man, while in many animals, as already seen, they constitute the whole of the brain. In the cerebral hemispheres there is still greater specialization and complication Of structure with corre- sponding exaltation of function; and, conformably to its highest degree in man, there are in him the highest and the most complex manifestations of mental function. In the human organism, then, is summed up the animal kingdom, which actually presents us with a sort of ana- lysis of it ; for in the functions of man we observe, as in a microcosm, an integration and harmonious co-ordina- tion of different vital actions which are separately displayed by subordinate members of the animal kingdom. In dealing with the function of the nervous system in man, it is, then, most necessary to distinguish different nervous centres : 1. The primary centres, or ideational centres, consti- tuted by the grey matter of the convolutions of the hemispheres. They are superordinate to 2. The secondary nervous centres, or sensory centres, constituted by the collections of grey matter that lie between the decussation of the pyramids and the floors of the lateral ventricles. These are subordinate to the primary and superordinate to 3. The tertiary nervous centres, or centres of reflex action, constituted mainly by the grey matter of the spinal cord ; which again are superordinate to 4. The organic nervous centres, as we might call them, belonging to the sympathetic system. They con- sist of a set of ganglionic bodies distributed mainly over the viscera, and connected with one another and with the spinal centres by internuntiant cords. Each distinct centre is subordinated to the centre no THE PHYSIOLOGY OF MIND. [CHAP. immediately above it, but is at the same time capable of determining and maintaining certain movements of its own without the intervention of its supreme centre. For example, the rhythmical contractions of the heart are kept up by the ganglia distributed through its sub- stance, and accordingly continue for a time after the removal of the organ from the body. But these local powers are not left uncontrolled : terminal branches of the vagus nerve, or rather branches of a motor nerve called the spinal accessory, which go with the vagus to the heart, are connected in some way with the ganglia ; and when the vagus is irritated the ganglia are controlled and cease to act upon the heart, which comes to a stand- still in a relaxed condition. The organization of the entire nervous system is such that a due independent local action is compatible with the proper control of a superior central authority. The ganglionic cells of the sympathetic co-ordinate the energy of the separate ele- ments of the tissue in which they are placed, and thus represent the simplest form of a principle of individua- tion;* through the cells of the spinal centre the func- tions of the different organic centres are so co-ordinated as to have their subordinate but essential place in the movements of animal life and herein is witnessed a further and higher individuation ; the spinal centres are similarly controlled by the sensory centres ; and these, in their turn, are subordinate to the controlling action of the cerebral hemispheres, and especially to the action which, revealing itself in consciousness as will, represents the most complete co-ordination of the functions of the hemispheres, and "is the highest display of the principle of individuation. The more unlike the parts in any animal and the more complex their subordination, the * Coleridge, in his Hints towards the Formation of a Comprehen- sive Theory of Life" takes from Schclling the definition "Life is the principle of Individuation." li.] THE MIND A.\D THE NERVOUS SYSTEM. Ill higher and the more perfect it is.* Were it not well if man in his social life could contrive to imitate this excel- lent organization? Most important and varied functions having been ascribed to nerve-cells, it may be asked : on what evi- dence do the statements rest? On the evidence of anatomical investigation, experiments upon animals, and physiological and pathological researches. (a) Anatomical Evidence. It is cenainly not possible to trace every nerve fibre to its connection with a cell, and until lately no such connection had been distinctly seen ; but it has now been observed in many instances, and most investigators believe that neither in the brain nor in the spinal cord does there exist an isolated apolar nerve cell ; such, if supposed to be seen, being in reality one which has had its processes torn away, or a young one that has not yet formed its connections, or not being a nerve-cell at all, but a connective tissue corpuscle. This is an inference which has scarcely less certainty than an observed fact ; as Goethe has said, it is not neces- sary to travel round the world in order to feel sure that the heaven above is everywhere blue.t Granting the constant connection of the fibre with the cell, are the ganglionic cells so numerous and so arranged as to render it conceivable that they can minister ade- quately to the manifold and complex manifestations of our mental life ? Most certainly they are : Dr. Lockhart * After speaking of an organism as a collection of individual elements, Goethe goes on to say: "Je unvolkommener das Geschopf ist desto mehr sind diese Theile einander gleich oder ahnlich, und desto mehr gleichen sie dem Ganzen. Je volkommeuer das Geschopf wird, desto unahnlicher werden die Theile einander. Je ahnlicher die Theile einander sind, desto weniger sind sie einander subordinirt. Die Subordination der Theile deutet auf ein volkom- meneres Geschopf." \ Um zu begreifen das dcr Himniel iibcrall blau ist, braucht man nicht um die Welt zu reisen. 112 THE PHYSIOLOGY OF MIND. [CHAP. Clarke's careful and valuable researches into the struc- ture of the cortical layers of the hemispheres reveal a variety, delicacy, and complexity of constitution such as answer to the varied and complex manifestations of mind. The following concise summary of those import- ant researches, for which I am indebted to Dr. Lockhart Clarke's kindness, will indicate exactly how the com- plexity of physical structure agrees with the complexity of mental function : " In the human brain most of the convolutions, when properly examined, may be seen to consist of at least seven distinct and concentric layers of nervous substance, which are alternately paler and darker from the circum- ference to the centre. The laminated structure is most strongly marked at the extremity of the posterior lobe. In this situation all the nerve-cells are small, but differ considerably in shape, and are much more abundant in some layers than in others. In the superficial layer, which is pale, they are round, oval, fusiform, and angular, but not numerous. The second and darker layer is densely crowded with cells of a similar kind, in company with others that are fyriform and pyramidal, and lie with their tapering ends either toward the surface or parallel with it, in connection with fibres which run in corresponding directions. The broader ends of the pyra- midal cells give off two, three, four, or more processes, which run partly towards the central white axis of the convolution and in part horizontally along the plane of the layer, to be continuous, like those at the opposite ends of the cells, with nerve fibres running in different directions. " The third layer is of a much paler colour. It is crossed, however, at right angles by narrow and elon- gated groups of small cells and nuclei of the same general appearance as those of the preceding layer. These groups are separated from each other by bundles of II.] THE MIND AND THE NERVOUS SYSTEM. 113 fibres radiating towards the surface from the central white axis of the convolution, and together with them form a beautiful fan-like structure. "The fourth layer also contains elongated groups of small cells and nuclei, radiating at right angles to its plane ; but the groups are broader, more regular, and, together with the bundles of fibres between them, pre- sent a more distinctly fan-like arrangement. " The fifth layer is again paler and somewhat white. It contains, however, cells and nuclei which have a general resemblance to those of the preceding layers, but they exhibit only a faintly radiating arrangement. " The sixth and most internal layer is reddish-grey. It not only abounds with cells like those already de- scribed, but contains others that are rather larger. It is only here and there that the cells are collected into elongated groups which give the appearance of radia- tions. On its under side it gradually blends with the central white axis of the convolution, into which its cells are scattered for some distance. " The seventh layer is this central white stem or axis of the convolution. On every side it gives off bundles of fibres, which diverge in all directions, and in a fan- like manner, towards the surface through the several grey layers. As they pass between the elongated and radiating groups of cells in the inner grey layers, some of them become continuous with the processes of the cells in the same section or plane, but others bend round and run hori- zontally, both in a transverse and longitudinal direction (in reference to the course of the entire convolution), and with various degrees of obliquity. While the bundles themselves are by this means reduced in size, their component fibres become finer in proportion as they traverse the layers towards the surface, in conse- quence, apparently, of branches which they give off to be connected with cells in their course. Those which 114 THE PHYSIOLOGY OF MIND. [CHAP. reach the outer grey layer are reduced to the finest dimensions, and form a close network with which the nuclei and cells are in connection. " Besides these fibres, which diverge from the central white axis of the convolution, another set, springing from the same source, converge, or rather curve inwards from opposite sides, to form arches along some of the grey layers. These arciform fibres run in differen planes transversely, obliquely, and longitudinally and appear to be partly continuous with those of the diver- gent set which bend round, as already stated, to follow a similar course. All these fibres establish an infinite number of communications in every direction between dif- ferent parts of each convolution, between different convo- lutions, and between these and the central white substance. " The other convolutions of the cerebral hemispheres differ from those at the extremities of the posterior lobes, not only by the comparative faintness of their several layers, but also by the appearance of some of their cells. We have already seen that, at the extremity of the posterior lobe, the cells of ALL the layers are small and of nearly uniform size, the inner layer only containing some that are a little larger. But, on proceeding forward from this point, the convolutions are found to contain a number of cells of a much larger kind. A section, for instance, taken from a convolution at the vertex, contains a number of large, triangular, oval, and pyramidal cells, scattered at various intervals through the two inner bands of arciform fibres and the grey layer between them, in company with a multitude of smaller cells which differ but little from those at the extremity of the posterior lobe. The pyramidal cells are very peculiar. Their bases are quadrangular, directed towards the cen- tral white substance, and each gives off four or more processes which run partly towards the centre to be continuous with fibres radiating from the central white II.] THE MfND AND THE NERVOUS SYS7*EM. 115 axis, and partly parallel with the surface of the convolution to be continuous with arciform fibres. The processes fre- quently subdivide into minute branches, which form part of the network between them. The opposite end of the cell tapers gradually into a straight process, which runs directly towards the surface of the convolution, and may be traced to a surprising distance, giving off minute branches in its course, and becoming lost, like the others, in the surrounding network. Many of these cells, as wells as others of a triangular, oval, and pyriform shape, are as large as those in the anterior grey substance of the spinal cord. " In other convolutions the vesicular structure is again somewhat modified Thus, in the surface convolution of the great longitudinal fissure, on a level with the anterior extremity of the corpus callosum, and therefore corres- ponding to what is called the superior frontal convolu- tion, all the three inner layers of grey substance are thronged with pyramidal, triangular, and oval cells of considerable size and in much greater number than in the situation last mentioned. Between these, as usual, is a multitude of nuclei and smaller cells. The inner orbital convolution, situated on the outer side of the olfactory bulb, contains a vast multitude of pyriform, pyramidal, and triangular cells, arranged in very regular order, but none that are so large as many of those found in the convolutions at the vertex. Again, in the insula, or island of Reil, which overlies the extra- ventricular portion of the corpus striatum, a great number of the cells are somewhat larger, and the general aspect of the tissue is rather different A further variety is presented by the temporo-sphenoidal lobe, which covers the insula and is continuous with it ; for while in the superficial and deep layers the cells are rather small, the middle layer is crowded with pyramidal and oval cells of considerable and rather uniform size. But not only in u6 THE PHYSIOLOGY OF MIND. [CHAP. different convolutions does the structure assume, to a greater or less extent, a variety of modifications, but even different parts of the same convolution may vary with regard either to the arrangement or the relative size of their cells. " Between the cells of the convolutions in man and those of the ape tribe I could not perceive any difference whatever ; but they certainly differ in some respects from those of the larger Mammalia from those, for instance, of the ox, sheep, or cat."* Dr. Herbert Major has recently made a careful ex- amination of the minute structure of the convolutions of the brain of the Chacma Baboon, and he finds that the general characters thereof agree with those that are met with in the human brain that the forms and relations of the cells show no variation. There was only one doubt- ful exception to this general rule, and that was the second layer of the frontal and parietal convolutions, the large cells of which are more rare in the baboon than in man. Whether such predominance of large cells in man is * In the first edition of this work an error occurred in the brief abstract made of Dr. Clarke's investigations, as they appeared in the Proceedings oftJu Royal Society, vol. xii. 1863. I regret the mistake the less, as it has been the occasion of my receiving, from Dr. Clarke's own pen, the above clear and concise description of his latest researches. Schroeder van der Kolk found a different structure of the grey substance of the convolutions in the anterior and posterior lobes of the dog and the rabbit : in the anterior lobes of the rabbit there are bundles of fibres, with cells, mostly tripolar, between them ; in the posterior lobes there is a regular series of pedunculated cells, which are placed close to one another, like organ pipes ; there are also single larger cells. As the result of his investigations, continued through an industrious lifetime, he states positively that, wherever there are differences of function, there differences of structure and composition and connexion do exist; "microscopical investigation has established this in the completest manner." Die Pathologie und T/ifrafie der Geisteskrankheiten auf Anatomisch-Physiologisclur GrtinJ/ae. Von J. L. C. Schroeder van der Kolk. 1863. ii.] THE MIND AND THE NERVOUS SYSTEM. 117 connected with superior function in him, must of course be entirely conjectural. Dr. Major was, however, led by a close comparison of numerous sections of brain to the distinct conclusion that in man the number of the cell processes, and, as a consequence, the extent of their connections, are greater than in the baboon ; and he be- lieves that the more numerous and complex anastomoses have relation to the superior functional activity in man.* Assuredly we are lost in the vastly intricate and complicated mechanism of cerebral cells and fibres when we attempt to trace the way in which function goes on, but we may perhaps realise how sufficient or more than sufficient for all the variety of our mental processes is the multitude of cells and extremely delicate fibres which constitute the convolutions. It is certain that in one cubic inch of convolution there would be found, if they could be counted, several hundred thousand nerve-cells and fibres, and in all the convolutions cells more in number than the stars of heaven ; and when we" compare these numbers with the number of words made use of by the most fertile writers, we shall perhaps be tempted to think that only a small portion of our intellectual instruments are actually utilized.f Out of a possible number of English words amounting to ninety or a hundred thousand, Shakespeare uses about fifteen thousand, Milton about eight thousand, and an agricultural labourer about three hundred. Complex, however, as is the structure of the convolu- tions, we find the same type as in the spinal cord namely, the nerve-cell forming the junction of fibres * " Observations on the Brain of the Chacma Baboon. " Journ.tl of Menial Science, January, 1876. \ " A portion of grey matter upon the surface of a convolution, not larger than the head of a very small pin, will contain portions of many thousands of nerve-fibres, the distal ramifications of which may be in very distant and different parts of the body." Bioplasm, p. 321. Dr. Beale, 2nd Ed. li8 THE PHYSIOLOGY OF MIND. [CHAP. and of other cells; this structure being multiplied in the brain in innumerable plexuses. Moreover, we find suitable anatomical provision for uniting in common function different parts of the same convolution, dif- ferent convolutions of the same hemisphere, and corre- sponding convolutions of the two hemispheres. Besides the fibres which are a continuation of the central white axis, and which conduct to and from the grey matter, there are the commissural fibres connecting cor- responding parts of the two hemispheres and effecting simultaneous or successive function of these parts ; and there are also the arciform fibres passing between different parts of the same hemisphere and combining in function both adjacent and more distant convolutions. Anatomy clearly reveals a structure destined to subserve varied and intimate intercommunion of function. And we may conceive, as we survey these manifold uniting fibres and the innumerable multitude of junction-making cells, how it happens that the functions of the cortical layers are soon restored after a partial destruction thereof; in the grey matter of these layers, as in the grey matter of the spinal cord, it is probable that equivalent parts connected in the most intimate and complex way may take the place of each other functionally. We may conceive, also, how it is that with two distinct hemispheres we have not a divided but a single consciousness ; one hemisphere is so intimately united by commissural fibres with the other that they are bound together in function and their con- sciousness is made one ; were the cortical centres of the brains of two men as closely united by commissural fibres as are the two hemispheres of one brain, they perhaps would not have a double but a single conscious- ness. The phenomena of hemiplegia prove that when two corresponding motor centres, which have to do with opposite parts of the body, lie near together and are closely united anatomically, and have been accustomed II.] THE MIND AND THE NERVOUS SYSTEM. 119 to act together functionally, their functions are coinci- dent, and one will do the work of the other when the latter is damaged. Although there are observable differences in the size and configuration of the cells of the cortical layers, as of the cells of other centres, yet it is clear that we cannot at present penetrate those intimate special differences in constitution or composition, or trace those special con- nections, which the variety of their functions implies. These essential differences of constitution are not such, indeed, as the microscope is ever likely to reveal ; for they probably depend on the intimate chemical composi- tion, and are not likely, even if we could isolate cells as required, to be disclosed until chemistry has arrived at microscopical application, or until some means has been discovered of penetrating the molecular constitution of nerve element. Those who may be disposed to think it impossible that such important constitutional differ- ences should exist in so small a compass, might reflect with advantage on the various undetectable conditions which may confessedly exist in the minutest organic matter ; as, for example, in the delicate microscopic sper- matozoon, or in the intangible virus of a fever. And yet it is from the conjunction of a minute spermatozoon with a minute germinal vesicle that are produced the muscles, vessels, nerves, and brain the intellectual organs of a Socrates or a Caesar. The single sperm-cell, integrating the qualities of generations of male and female ancestors, unites with the germ-cell, integrating in like manner the qualities of generations of male and female ancestors, and gives birth to a new organic product which, minute as it is, contains in latent form all the potentialities, and displays actually in evolution many of the qualities, of ancestors on both sides, and furthermore evinces new qualities as a result of the organic combination ; not otherwise than as a chemical 120 THE PHYSIOLOGY OF MIND. [CHAP. compound evinces properties that are unlike those of its constituents. There is nothing extravagant in the supposition that a single nerve-cell may contain like potentiahies.* Consider, again, the infinite littleness of the odorous particles that affect the smell, and, more wonderful still, the marvellous discriminating suscep- tibility of sense to these undetected agents. The ex- quisite minuteness and consummate delicacy of the operations going on in the most intimate recesses of nature are even more striking and wonderful than the vastness and grandeur with which the astronomer is concerned. " What the immensity is to the astronomer or geologist," says Sir H. Holland, "such are these infinitely small dimensions of matter in space to the physiologist." Of what may happen in a world into which human senses have not yet found means of en- tering we are no better entitled to speak than the blind man is to talk of the appearance of objects. In such matter it would be more wise to adopt Ter- tullian's maxim, " Credo quia impossible est," than that which is so much favoured by the conceit of human ignorance that a thing is impossible because it ap- pears to be inconceivable.t (b) Experiments on Animals have distinctly proved * It is worth remark that similar complex chemical compounds have been found in nerve-substance and in the semen and the ovum, calling to mind the statement of Alcmxon, an ancient writer on medical subjects, that a drop of semen is a drop of brain. t The latest speculations concerning the actual constitution of atoms render it probable that even chemical atoms are really very complicated structures, and that in them there are complex intestine motions of which we have not the least conception. "An atom ol pure iron is probably a vastly more complicated system than that of the planets and their satellites." JEVONS, Principles of Science. The smallest particle of solid matter will consist of a number of such systems united in regular order, the problem of their forces and motions being beyond the reach of our mathematical powers, even were the systems accessible to observation. II.] THE MIND AND THE NERVOUS SYSTEM. 121 the differences between the functions of the ganglionic cells that constitute the principal different nervous centres ; but such results will more properly find their place afterwards. Let it suffice here to say that the sight of an animal may be destroyed by injury to its corpora quadrigemina as surely as by burning out its eyes. By the experiments of Fritsch and Hitzig, which have been repeated and extended by Dr. Ferrier, some- thing has lately been done towards distinguishing the functions of different convolutions. (c) Physiological Evidence. The study of the plan of development of the nervous system through the animal kingdom, with the corresponding progress in complexity of function, undoubtedly furnishes the best testimony in favour of differences in the constitution and function of the nerve centres. That evidence has already been suffi- ciently set forth. The hopeless vanity of all discussions concerning infinite or absolute truth might well have been made manifest by this physiological reflection : that our pei- ception of external nature is the effect which the object produces, through an adapted medium, in certain of om central nerve-cells, an effect on which we can exercise no influence ; it is, as Hobbes puts it, " but an apparition unto us of the motion, agitation, or alteration, which the object worketh in the brain, or spirits, or some internal substance of the head." Excite that condition of the central cell otherwise than by the stimulus from without, the perception does not fail to ensue : a blow on the eye produces flashes of light ; on closing the eyes after looking at the sun a spectrum of it remains, which, as it slowly fades away, may be brightened and darkened alternately for a time by pressing the eye and removing the pressure ; luminous spectra are sometimes seen after complete destruction of the retina ; a disturbance of the circulation in the auditory ganglia gives rise to noises in 122 THE PHYSIOLOGY OF MIND. [CHAP. the ears ; an insane person who is quite deaf will some- times hear what he believes to be the voices of persons ad- dressing him, and will dispute with them; in fact, all the senses may be excited subjectively. The reason is evi- dent : because the perception depends upon the nature of the special centres and the mechanism by which the stimulus is conveyed to them. The idea in the mind is the result of an action excited in the nerve centres ; the external impression not being conveyed to them, but exciting the physiological property of the nerve, which thereupon gives rise in them to the special effect. Accordingly, the effect of any stimulus capable of affecting one of the special senses is, as Muller pointed out, of the same kind as that produced by the proper stimulus of the particular sense : thus the effect of the electric stimulus on the optic ganglia is to cause a sensation of light ; on the olfactory nerves, some kind of smell ; on the gusta- tory nerves, some kind of taste. In like manner, whether irritation of a nerve shall produce a muscular move- ment, a secretion, or a sensation, depends not upon the constitution of the nerve, nor upon the means of irritation, but upon its connections whether it is con- nected with a muscle, gland, or sensory centre. It is clear then that the qualities of our sensations do not represent corresponding qualities in objects that our senses do not give us anything like an exact impression of the outer world. Whether the rays of the sun appear to us as colour or heat depends not upon any properties of colour or heat in them, but simply upon the fact whether they stimulate the fibres of the optic nerve or those of the skin ; and of what colour rays of light shall appear to us will depend entirely upon the length of the undulations, those of red being the longest, those of violet the shortest If the nerve fibres which answer to the undulations of what appears in us as red were wanting in our eyes, we should not have the least IL] THE MIND AND THE NERVOUS SYSTEM. 123 conception of red.* That man is by nature thus limited to the reception of certain special impressions through a few avenues, proves how limited must be his knowledge at the best : it may well be, of a truth is, that there are many things in nature of which he has not, and cannot have, the least apprehension ; and that a new sense con- ferred upon him might alter the whole aspect of the universe and transform entirely the character of that which he calls knowledge. What is true of the sensory ganglia is probably no less true of the higher centres of intelligence. There is reason to assume differences, not merely between gan- glionic centres in one lobe of the brain and in another, but also between centres in the same lobe and even in the same convolution. The law of progress from the general to the special in organic development does not, it may be presumed, stay its action suddenly at the cere- bral hemispheres. The philosopher is not, it is true, in * Suppose that men and all animals that have similar organs of sight were swept off from the face of the earth : there would be no light, for light is something relative to the eye ; without which it could have no existence as such. And if the earth were inhabited by beings so differently constituted as to have entirely different kinds of senses from what we have, it is impossible to conceive what the world would be to them. We find ourselves in a, position in which we are acted upon and react, and, being conscious of this action and re- action, we get the notions of object and subject ; we are constrained to believe in an external something, not ourselves, which is beneath the phenomena of which we are conscious, and which includes us in its operations, and we may represent it as we will as nature, or a universally immanent spirit, or as personal God, or personal devil. But we never can know more of this external something which is not ourselves than in its relation to ourselves can never by any possi- bility know what it is in itself. Men should amuse themselves by trying to develop a new sense in some individual or in his progeny by selective breeding, as the bees, having lost their queen, take in hand a common young one, ard feed and foster it into a queen bee. lie might amply repay their pains by teaching them how little they really knew of the external something which is not themselves. 124 THE PHYSIOLOGY OF MIND. [CHAP. possession of more senses than the savage ; but he un- questionably has more numerous and complex convolu- tions, and, therefore, many more differentiated centres in the primary centres of intelligence. The differences be- tween persons notably become greater as civilization in- creases; and outer differences assuredly mean differences in the innermost. It is a common remark that all savages are much alike, and it is certain that uneducated labourers are more like one another than educated persons are. By intending his mind to the realities of external nature the scientific inquirer acquires information through the senses, but his intelligence reacts advantageously upon the senses ; he constructs instruments which extend their power of observation, thus acquires, as it were, new artificial senses; so that hitherto obscure relations of external nature are disclosed to him, and he attains to more special and complex relations therewith. If in the nervous centres cortical cells of a higher quality and of more complicated connections than the savage has, do not answer to this increased speciality and complexity of external relations, it is contrary to all the analogy of organic development. (d) Pathological Evidence. This will be brought for- ward in detail at a later period. Let it suffice here to say, that Schroeder van der Kolk could venture to assert that he never failed to discover morbid changes of struc- ture in insanity, and that, when intellectual disorder espe- cially had existed, he had found the cortical layers under the frontal bones to be darker coloured, more firmly con- nected with the pia mater, or softened ; in melancholia, on the other hand, where the feelings mainly were excited or depressed, the pathological changes were found prin- cipally in the convolutions of the upper and hind lobes. In old age when the memory fails, he found the cells of the cortical layers visibly atrophied. The very many and various disorders to which the memory is liable, failures ii. J. THE MIND AND THE NERVOUS SYSTEM. 135 of such variety, degree and character as can only be described by being given in detail, surely indicate in no uncertain way the different functions of different centres in the cortical layers of the hemispheres. Thus much, then, by way of setting forth facts which will not easily be discredited. What is the unavoidable conclusion ? That no true scientific result can possibly proceed from a vague and general descriptive employment, without further discrimination, of mental action to embrace phenomena of such manifestly different nature. If the psychologists had duly minded the old but wholesome maxim, that whosoever distinguishes well teaches well, they might have found in the revelations of self-con- sciousness, when interpreted without bias, those dis- tinctions which an investigation of the physiology of the nervous system in man and animals establishes beyond question. But the metaphysical conception of mind, the abstraction made into an entity, has overridden all dis- cerning observation, and, confounding well-marked dif- ferences in a vague obscurity, has constructed a loose system of undefined words in place of an exact and posi- tive science of facts. Instead of mind being, as assumed, a wondrous spiritual entity, the independent source of power and self-sufficient cause of causes, an honest obser- vation proves incontestably that it is the most depend- ent of all the natural forces. It is the highest develop- ment of force, and to its existence all the lower natural forces are indispensably prerequisite. It is most needful, if we would avoid confusion and error, once for all to form a just and definite conception of what we intend to mean by mental force, and of its position in nature. The various definitions of mind which philosophers have tendered do not help us far on our way. It is the substantia cogi'tans, says Descartes; " that which thinks, reasons, wills," says Reid ; " the subject of the various internal phenomena of which we 7 126 THE PHYSIOLOGY OF MIND. [CHAP. are conscious, or the subject of which consciousness is the general phenomenon that which perceives, thinks, feels, wills, desires," says Sir W. Hamilton ; " the sum total of subject experiences, that which has not extension," according to Mr. Bain. But what is the thinking substance : that which thinks, reasons, wills ; that of which conscious- ness is the phenomenon ; that which is the subject of ex- periences ; when we resolutely pierce the vague abstrac- tion and get as near as we can to the concrete fact ? The physiologist answers that it is the brain, not any supposi- titious metaphysical entity of the existence of which he has no evidence whatever, and of the need of which as a hypothesis he is not conscious. To him the hypothesis is as superfluous in thought as it is unfounded in obser- vation. By observation of mental phenomena wherever displayed and of whatever sort, by experiment, by rea- soning by all the means of knowing which serve him in other scientific inquiries, he has come to the assured conviction that mind does not exist in nature apart from brain : all his experience of it is in connection with brain just as all his experience of gravitation is in connection with matter : he has never met with gravitation without a heavy body, chemical force without chemical sub- stances, life without organic matter, thought without nervous tissue. Mind he holds to be nothing more than a general term denoting the sense of those functions of brain which are accompanied by consciousness, and which are commonly described as thought, feeling, and will (3) To deal with mind as a force in nature apart from the consideration of the matter through the changes of which it is manifested, is truly no less vain and absurd than it would confessedly be to attempt to handle electricity and gravitation as forces apart from the changes in matter by which alone we know them. No man in his senses would attempt to develop a child's mind without paying any regard to its bodily nutrition. Many persons, however, n.] THE MIND AND THE NERVOUS SYSTEM. 127 seem to labour under the impression that they have the right to demand from the physiologist who deals with mental functions that he shall tell them more about the real nature of mind than they know of the real nature of any other natural force, and to exult over him when he fails to do so. Not content with his efforts to trace uniformities of sequence, they insist that he shall explain how or why a certain mental sequence is the result of certain antecedent cerebral states. Were they to con- sider fairly how much they know and do not know concerning other natural forces, they would perceive that it is a preposterous demand to make in respect of mind. I know not why they should suppose it impossible that a Creator whom they believe to be omnipotent can have endowed matter in its most complex development with feeling and thought, nor why they should be hor- rified at the suggestion that he has done so. They strangely overlook the fact that the brain is not a dead instrument, but a living organ, with functions of a higher kind than those of any other bodily organ, insomuch as its structure far surpasses in organic dignity that of any other organ. What, then, are these functions if they are not mental ? It were wise to ponder well the remark- able operations of which matter is capable, and to reflect upon the wonderful works which it is continually doing before our eyes. Consider the seed dropped into the ground : in due season it springs up as a tender shoot, which grows into a plant that puts forth first its leaves and then its blossoms, making use in the process of a more subtile chemistry than man can yet compre- hend or attain unto, until finally it is clothed in such a floral beauty that "Solomon in all his glory was not arrayed like one of these." It is not a spiritual plant which does these things through the agency of matter ; they are operations of matter, and wonderful enough, 128 THE PHYSIOLOGY OF MIND. [CHAP. rightly considered, to satisfy any one of the properties that are inherent in it. We cannot choose but believe that the highest and most complex development of organic structure is capable of even more remarkable operations. In truth, when we trace the development of the nervous system step by step through the animal series, from its first germ to its most complex evolu- tion, we shall find it a hard matter to declare at what point it suddenly loses all its inherent properties as living structure, and becomes the passive instrument of an immaterial entity. Those who repudiate such mate- rialism may comfort themselves by conceiving a fine matter of extreme subtility and tenuity, a sort of im- material matter : whether they spiritualise matter in this way, or materialise mind, is a question of words, not of facts. The truth is that it has been the custom to dispute violently and vaguely about matter and motion, and about the impossibility of matter affecting an immaterial mind, without being at the pains to reflect carefully upon the different kinds of matter and the corresponding differences of kind in its motions. All sorts of matter, diverse as they are, were vaguely matter no discrimina- tion was made ; and all the manifold and special proper- ties of matter were comprised under the general term motion. This was not, nor could it lead to, good. As there are different kinds of matter, so there are dif- ferent modes of force, in the universe ; and as we rise from physical matter in which physical properties exist and laws hold sway up to chemical matter and chemical forces, and from chemical matter again up to living matter and its modes of force, so do we rise in the scale of life from the lowest kind of living matter, with its corresponding force or energy, through different kinds of organic elements, with their corresponding energies or properties, up to the highest kind of living matter and II.] THE MIND AND THE NERVOUS SYSTEM. 129 corresponding mode of force with which we are ac- quainted, viz. nerve element and nerve force. But, when we have arrived at nerve element and nerve force, it behoves us not to rest content with the general idea, but to bestow pains on the patient and careful discrimination of the different kinds of nerve-centres in the nervous system, and to study their different manifestations of energy. So shall we ascend to the most exalted agents of mental function, and so only shall we obtain the ground-work of a true conception of the relations of mind and the nervous system. In like manner as men have disputed vaguely con- cerning matter, without reaching an adequate conception of that most complex combination of elements and ener- gies, physical and chemical, in a small space, which exists in the smallest atom of nerve element, so has much barren discussion been owing to the undiscriminating inclusion of all kinds of mental manifestations under the vague and general term mind. These are important differences in the nature and dignity of so-called mental phenomena, when they are carefully observed and analyzed. By rightly submitting the understanding to facts, it is made evident that, on die one hand, matter rises in dignity and function until its acknowledged energies merge insensibly into functions which are assumed to be purely mental, and, on the other hand, that there are gradations of the so called purely mental functions, the lowest of which confessedly do not transcend the functions of matter. The burden of proving that the Deus ex machina of an immaterial agent intervenes somewhere, and where it intervenes, lies therefore upon those who make the asser- tion or need the hypothesis. They are not justified in arbitrarily fabricating an hypothesis entirely inconsistent with what we know of the orderly development of nature, and which postulates a domain of nature that human sense cannot take cognizance of, and in then calling 130 THE PHYSIOLOGY OF MIND. [CHAP. upon those who reject their assumption to disprove it. These have done enough when they have shown that there are no grounds for nor need of the hypothesis. The chief feature to be noted in this upward trans- formation of matter and correlative metamorphosis of force is, that the exaltation or transpeciation on each occasion represents an increased speciality of elements, and a greater complexity of combinations, in a smaller space : all exaltation of matter and force is, as it were, a concentration thereof. As one equivalent of chemical force corresponds to several equivalents of inferior force, and one equivalent of vital force to several equivalents of chemical force ; so in the scale of tissues the higher kind represents a more complex elementary constitution, and a greater number of simultaneously acting forces, than the kind of tissue below it in dignity. If we suppose a higher tissue to undergo decomposition, or retrograde metamorphosis of its matter, with which must necessarily coincide a resolution of its energy into lower modes, then we might say that a single monad of the higher tissue, or one equivalent of its force, would equal in value several monads of the lower kind of tissue, or several equivalents of its force. The characteristic of living matter is the complexity of combinations and the variety of elements in so small a compass that we cannot yet trace them ; and in nerve structure this complication and concentra- tion is carried to its highest pitch. We may suspect, but we cannot conceive, the complexity of systems and of motions of molecules which exist in the smallest atom of nerve element. Nervous tissue with its energy is, there- fore, dependent for its existence on all the lower kinds of tissue that have preceded it in the order of development : all the force of nature could not develop a nerve-cell directly out of inorganic matter. The highest energy in nature is really the most dependent ; in the fact that it is so dependent, that it implicitly contains the essence or M.J THE MIND AND THE NERVOUS SYSTEM. 131 abstraction of all the lower kinds of energy, lies the reason of the powerful influence which it is able to ex- ercise over all the lower forces that are subservient to its evolution. As the man of genius implicitly contains humanity, so nerve element implicitly contains nature.* What is the progress or nisus that is manifest on sur- veying nature as a whole ? Is it not the struggle to arrive at consciousness, to attain to self communion ? In the series of her manifold productions man was, so to speak, says Goethe, the first dialogue that Nature held with God. Every poet, then, who is sensitive to a hitherto unrevealed subtlety of human feeling, every philosopher who apprehends and reveals a hitherto unobserved rela- tion in nature, opens the door to new discoveries, and is, each in his place, aiding the onward progress ; in his art nature is undergoing evolution ; in him the world is more or less regenerate, " To whom the winged Merarch replied : O Adam, one Almighty is, from whom All things proceed, and up to Him return, If not depraved from good, created all Such to perfection, one first matter all, Indued with various forms, various degrees Of substance, and in things that live, of life ; But more refined, more spirituous, and pure, As nearer to Him placed, or nearer tending, Each in their several active spheres assigned, Till body up to spirit work, in bounds Proportioned to each kind. So from the root Springs lighter the green stalk, from thence the leaves More aery, last the bright consummate flower Spirits odorous breathes ; flowers and their fruit, Man's nourishment, by gradual scale sublimed, To vital spirits aspire, to animal, * For the further development of this view of life, I may refer to n article on the "Theory of Vitality," in the British and Foreign A/a/.-Cfiir. Review, October 1863, which is rcpublished in the second edition of Body and Mind, 1873. 132 THE PHYSIOLOGY OF MIND. [cHAr. To intellectual ; give both life and sense, Fancy and understanding ; whence the soul Reason receives, and reason is her being, Discursive, or intuitive ; discourse Is oftest yours, the latter most is ours, Differing but in degree, of kind the same." (*) Paradise Z^sf, B. V. NOTES. 1 (p. 88). In the first chapter I attributed to Von Baer the formu- larization of the law of progress from the general to the special in-or- ganic evolution ; and it is true that he traced it admirably through the differentiations of the fundamental tissues of the embryo. But it would appear that Von Baer never claimed the law as his discovery, for he says of it " This law of development has indeed never been overlooked." Mr. Lewes (Life and Works of Goethe, 1 8$5) claims it for Goethe. "The law," he says, "announced by Goethe, and I believe distinct 1 y announced by him for the first time, is now to be met with in every philosophic work on zoology. One form of it is known in England as Von Baer's law ; viz., That development pro- ceeds from the Like to the Unlike, from the General to the Particular, from the Homogeneous to the Heterogeneous." However, Wolff, in his Theoria Gcncralionis, anticipated Goethe. a (p. 91). The doctrine of the relation of the organism to its en- vironment, so far as it belongs to anyone in particular, ought perhaps to be credited to Comte, who, at any rate, recognised its important bearing and laid very great stress upon it when treating of Biology. Lamarck had not, however, failed to perceive and appreciate the powerful action of external circumstances upon the organism, while Blainville, in his 'Court de Physiohgie gtnfrale et comfaree, clearly points out the modifying effects which are thus produced. .The fol- lowing extracts will suffice to exhibit Comte's conception of the doctrine : " All biological conceptions must of necessity depend upon two kinds of adjustment ; that of the Organism to its Environ- ment, and that of Organs to Functions, or rather of Agents to Acts. . . . No conception in systematic biology can be considered as thoroughly complete until it exhibits these two elementary relations :oherently combined." (Positive Polity, vol. i. p. 517, Eng. Trans.) ..." Their study " (that of the special relations of functions to organs) " will be begun and carried on with a distinctly systematic purpose ; that of forming a clearer conception of the general rela- tion between the Organism and its Environment ; for this, and thii II.] THE MIND AND THE NERVOUS SYSTEM. 133 only, is the ultimate goal at which the science of Life aims " (p. 519). . . . "In this more systematic conception of Biology, Function will be regarded as the special result of a determinate relation between Knvh umiu'iit and Organism " (p. 520). He speaks of the general theory of organic environments as "an entirely new branch of biology, of which Lamarck must be considered as the true founder, although with him it was too much mixed up with unfounded hypo- theses as to the indefinite variability of species" (p. 537). Mr. Herbert Spencer has given the most complete and elaborate de- velopment to the doctrine in his Principles of Biology ; but as Mr. Spencer does not on any occasion give references to or make quota- tions from authors who have preceded him, but works up their re- sults systematically into his lucid exposition, those who gain all their knowledge of philosophy from the most recent and popular exposi- tions of it, and ascribe to their authors all they find there, are prone to think original that which is often a legacy from the past. This practice of ignoring authorities, though it no doubt has its conveni- ences, bears hardly and disagreeably sometimes on those who may have occasion to write upon the same subjects, inasmuch as they are liable to be charged by ignorant persons with borrowing from an eminent contemporary what the contemporary has really derived from the same well-known source, and would not claim as his own. This is trying : the most serenely pankleptic appropriator of the fruits of past thought will become recalcitrant when he is charged with specific appropriation of material, not from the real proprietor of the property, who may perhaps not be known by name, but from one who, indebted for it to the same sources in the stores of the past as himself, does not make specific acknowledgments. 3 (p. 126). The definition of Descartes makes the function the sub- stance. Instead of mind being the thinking substance, the substantia cogitans, it is the thinking which is mind the function of the sub- stance ; the substance being the brain. Hamilton's definition is de- fective on its own ground. By defining mind to be the subject of the various internal phenomena of which we are conscious, he leaves all the mental phenomena of which we are not conscious, and the existence of which he admitted, without any subject ; he does not deal with that substratum of mentality which is beneath mentation or con- scious mental function, and which is in the cerebral organization. Cerebral mental function may be conscious or unconscious, active, subactive, or in abeyance ; and it is only when the intimate organs of thoughts, desires, &c., reach a certain height of energy that their functions become conscious that they, in fact, function as con- sciousness. Mr. Bain's definition seems still more open to animad- 134 THE PHYSIOLOGY OF MIND. [CHAP. version, as will appear if we alter the wording of it, when it will run thus mind is the sum total of the experiences of that which has not extension, that which has not extension being a subject! What, we may ask, is this subject which has not extension ? Surely it stands in need of some definition. Psychologically speaking, moreover, we cannot properly say that a sensation has or lias not extension ; consciousness does not tell us ; the word extension has no meaning when applied to its revelations ; the meaning of the word is entirely objective. And if we come to objective experience, we cannot conceive something which has not extension ; it is a con- tradiction, not something but nothing. We never meet with mind except in connection with matter with a subject that has extension, and cannot, it seems to me, think of it otherwise. By a process of abstraction, it is true, we may separate mind from matter, as we separate weight from a heavy body, but it is a mere abstraction which corresponds to nothing in nature. * (p. 132). That Milton intended this passage to be sound philo- sophy is shown by what he says in his Treatise on Christian Doctrine. After declaring the inconceivability of God having created the world out of nothing, arguing that it was framed out of pre-existent matter, which proceeded from God, and is incapable of annihilation, he goes on to propound the doctrine that there is no ground for the supposed distinction between body and soul. Matter being "an efflux of the Deity" is plainly capable of intellectual functions. " That man is a living being, intrinsically and properly one and individual, not compound or separable, not, according to the common opinion, made up and framed of two distinct and different natures, as of soul and body, but the whole man is soul, and the soul, man ; that is to say, a body or substance, individual, animated, sensitive, and rational . . . Hence the word used in Genesis to signify soul is interpreted by the apostle, I Cor. xv. 45, ' animal.' Again, all the attributes of the body are assigned in common to the soul ; the touch, Lev. v. 2 ' if a soul touch any unclean thing* ; the act of eating, vii. 8 'the soul that eatelh of it shall bear its iniquity,' and in other places ; hunger Prov. xiiL 25, xxvii. 7 ; thirst, xxv. 25, ' as cold waters to a thirsty soul,' Isaiah xxix. S; capture I Sam. xxiv. II, 'thou huntest my soul to take it.' . . . . But that the spirit of man should be separate from the body, so as to have a perfect and intelligent existence inde- pendently of it, is nowhere said in Scripture, and the doctrine is evidently at variance both with nature and reason, as will be shown more fully hereafter. For the word soul is also applied to every kind of living being ; Gen. L 30, ' to every beast of the earth, &c., n.] THE MIND AND THE NERVOUS SYSTEM. 135 wherein there is life ' ; vii. 22, ' all in whose nostrils was the breath of life, of all that was in the land, died' ; yet it is never inferred from these expressions that the soul exists separate from the body in any of the brute creation. .... It would seem, therefore, that the human soul is not created daily by the immediate act of God, but propagated from father to son in a natural order. .... There seems, therefore, no reason why the soul of man should be made an ex- ception to the general law of creation. For, as has been shown before, God breathed the breath of life into other living beings, and blended it so intimately with matter, that the propagation and production of the human fonn were analogous to those of other forms, and were the proper effect of that power which had been communicated to matter by the Deity For the original matter of which we speak is not to be looked on as an evil or a trivial thing, but as intrinsically good, and the chief productive stock of every subsequent good." Vol. i. p. 1 88. Robert Hall, the great Baptist preacher, at one peiiod of his life, held a similar opinion. "I am," he says, "and have been for a long time, a materialist My opinion upon this head is that the nature of man is simple and uniform ; that the thinking powers and faculties are the result of a certain organization of matter ; and that after death he ceases to be conscious until the resurrection." However, "attentive to the voice of heavenly admonition," his biographer tells us, he afterwards abandoned these dangerous specula- tions, and "buried materialism in his father's grave," Memoir of Robert Uall, p. 32. CHAPTER III. THE SPINAL CORD, OR TERTIARY NERVOUS CENTRES; OR NERVOUS CENTRES OF REFLEX ACTION. OMITTING for the present any mention of the lowest nervous centres of the body first, because they minister chiefly to the organic life, and little is definitely known about them ; and secondly, because something will be said of them incidentally when treating of the Passions I go on to show forth the functions of the spinal cord. It is not a conducting organ between the outer world and the brain only, but contains many independent nerve centres. A large part of human activity notably takes place without any voluntary control, or even without any consciousness, on the part of the individual ; and of these unconscious or involuntary actions a great part is as plainly due to the independent power of reaction which the ganglionic cells of the spinal cord have. If it be cut across at a spot below where the respiratory nerves are given off, all sensation and voluntary motor power are lost in the parts of the body below the section ; but if the sole of the foot be then tickled with a feather, the leg is drawn up, though the man is unaware of it unless he sees or is told by others what happens. John Hunter mentions the case of a patient suffering from paraplegia, that is, paralysis of the lower half of the body, in whose legs violent movements which he did not CHAP, in.] THE SPINAL CORD. 137 feel were produced when the soles of the feet were irri- tated. When asked whether he felt the irritation which excited the movements, he replied, " No, sir ; but you see my legs do." Such automatic action of the spinal cord, manifest enough in the actions of man, but still more so in those of the lower animals, may be illustrated both from the animal kingdom and from the phenomena of human life. When the earliest actions of the new-born infant are observed, it is plain that, like the movements of the foetus within the mother's womb, or the movements of many of the lower animals, they are simply reflex to im- pressions, and take place without will, or even without consciousness. The anencephalic infant, in which ab- sence of brain involves an absence of consciousness, not only exhibits movements of its limbs, but is capable also of the associated reflex acts of sucking and crying. An infant does not require to be taught to cough ; it can expel irritating matter from the bronchial tubes by simple reflex action ; but it cannot spit until it has learnt the art. Hence, when it coughs up a quantity of mucus it is al- most choked by it, or, another reflex act coming into play, swallows it. The same thing happens in the apoplectic and the dying person when the original reflex functions sur- vive the decay of the acquired automatic functions. But it is from experiments on animals that we have gained our clearest ideas of reflex action. When the head of a male frog which is clinging to the female at the season of sexual congress is cut off, the body main- tains its hold, and even when a foot is cut off, clings to her with the stump ; if the posterior half of the body be cut away, the anterior half still holds on ; but if that part of the cord from which the nerves to the anterior limbs go is destroyed, the hold is loosened at once, just as the grasp of a vice is loosened when a backward turn is given to the tightening screw. A similar relaxation is produced in 138 THE PHYSIOLOGY OF MIND. [CHAP. higher animals by discharge of the energy of the nerve- centres concerned : compare the spasmodic grasp of eager love with the relaxed hold of sated lust A decapi- tated frog will draw up its leg with mechanical regularity whenever its foot is pinched or acetic acid is applied to it, the time which elapses between the application of the irri- tant and the withdrawal of the foot varying according to the strength of the irritant, and hardly varying more than a second at each application if the strength of the irritant is the same. But there is a well-known experiment which yields even more striking results. Pfliiger touched with acetic acid the thigh of a decapitated frog over its internal condyle ; it wiped it off with the dorsal surface of the foot of the same side : he thereupon cut off the foot, and applied the acid to the same spot ; the animal attempted to wipe it off again with the foot of that side, but, having lost its foot, of course could not. After some fruitless efforts, therefore, it ceased to try in that way, seemed unquiet, " as though it were searching for some new means," and at last it made use of the foot of the other leg, and succeeded in wiping off the acid. When it has done that, the animal will remain at rest for hours, until some new stimulus is applied ; it makes no spon- taneous movements. Notably we have in this striking experiment not merely contractions of muscles, but com- bined movements in due sequence for a special purpose ; we have actions that have all the appearance of being instigated by will and guided by intelligence in an animal the recognized organ of whose intelligence and will has been removed. So much, was Pfliiger impressed by this wonderful adaptation of means to an end in a headless animal, that he actually inferred that the spinal cord, like the brain, was possessed of sensorial functions. We have clearly, however, no knowledge that the frog feels the irritation ; all we know certainly is that this has induced in.] THE SPINAL CORD. 139 certain definite movements. Others, who would scarce admit Pfliiger's supposition to be true of man, have thought that it might be so of some of the lower ani- mals. Instead of grounding their judgment of the com- plex phenomena in man on their experience of the simpler instances exhibited by the lower animals, they have applied to the lower animals what I believe to be their subjective misinterpretation of the complex pheno- mena in man.C) It is obviously quite possible to draw another inference from Pfliiger's experiment : that the so-called design of an act does not necessarily witness to the co-existence of will, forethought, or consciousness ; that actions " having the semblance of pre-designing consciousness " may, nevertheless, be unattended with consciousness.* No doubt there is a definite purpose in the movements which the maimed frog makes, as there is definite purpose in the movements of the anencephalic infant's lips, in the respiratory movements of man or animal, or in such movements as are necessary for coughing, sneezing, and swallowing ; but in all these instances the co-ordinate activity is the result of an innate nervous constitution, an original endowment of the nervous centres. In the* * Very interesting, in relation to this matter, are Prochaska's ob- servations, published in 1784 : " Cum itaque precipua functiosen- sorii communis consistat in reflexione impressionum sensoriarum in motorias, notandum est quod ista reflexio vel animd inscid vcl vera animd conscid fiat" He gives numerous examples, often given since by other authors, and adds : " Omnes istae actiones ex organismo et physicis legibus sensorio communi propriis fluunt, suntque propterea spontaneae et automatic*." Commentatio de Functionibiis Systematic Nervosi, p. 88. 1784. It must be rememSered that Prochaska in- cluded the spinal cord under the semorium commune. To the same effect are Unzer's remarks : " What in them appears to be voli- tional, only appears so, because we draw conclusions as to other animals from the nature and working of our own minds. What ap- pears to be designed arises from the preordination of nature." Unser and rrochaska on the Nervous System. Syd. Soc. TransL, p. 323. 140 THE PHYSIOLOGY OF AlIND. [CIJAP. physiological mechanism of the frog's spinal cord are the faculties of the movements which it makes for self-pre- servation ; it has inherited them as a part of its nature, and without them could hardly live a day. Accordingly we see that the frog acts necessarily and blindly ; though it has lost its foot, acts as if the foot were still there, which, were there intelligent consciousness, it plainly should not; and only employs other means when the irritating action of the stimulus continues unaffected by its fruitless movements. As the movement which takes place in a sensitive plant the Mimosa pudica for in- stance when it is irritated, is not limited to the spot where the irritation acts, but extends, if this be sufficiently intense, to the whole plant ; or as when an insect settles on a leaf of the Dioncea muscipula, it is held first by the bending round of the hairs, and afterwards the whole leaf gradually rolls itself round it ; or as in certain mor- bid states of the human organism the continuance of an irritation, which at first only causes slight reflex action, may produce a more general involuntary reaction, or convulsions; so in the frog, the enduring stimulus, which has not been affected by the customary reflex movement, now gives rise to those further reflex movements which are the physiological sequences of the former, and would have been made use of had the creature still possessed its brain. In the constitution of the spinal cord are implanted the capabilities of such co-ordinate energies ; and the continuance of the irritation determines the ex- tension of the activity. There takes place an irradiation of the stimulus. But this happens unquestionably with- out the frog's consciousness, whether or not it happens without a consciousness on the part of its spinal cord; all the design which there is in the movement is of the same kind as the design which there is in the formation of a crystal, or in the plan of growth of a tree. A crystal cannot overstep the laws of its in.] THE SPINAL CORD. 141 form, nor can a tree grow up into heaven ; the particles of the crystal aggregate after a certain definite plan, and thus strictly manifest design. Are we then to assume that, because of the design, there is consciousness in the forming crystal or the growing tree ? Assuredly not ; and yet it is to such extreme conclusion that the argu- ments of those who look upon the so-called design of an act as testifying to consciousness logically lead. The design of an act is nothing else but the correlate in the mind of the observer of the law of the matter in nature ; and each observer will see in any event exactly that amount of design which he brings with him the faculty of seeing. Although we have good grounds for affirming that the movements of the frog which has been deprived of its hemispheres may be explained satisfactorily without the assumption that its spinal cord possesses feeling and will, there are persons of eminence who hold positively that the experiments prove the diffusion of these functions through the nerve-centres of the lower animals. In sup- port of this opinion, they instance further the fact that when an insect is cut in two the forepart of the body may continue to eat, while the hind part continues the act of sexual congress, as proof that the will to eat and the feeling of appetite lie in the former, the will to sexual congress and the feeling thereof in the latter. It some- times happens, again, when an earwig is cut in two, that the divided parts of the body turn on each other, and fight with fury and passion until death or exhaustion ends the fray ; an event which could not be, they say, unless there were consciousness and will in each part. They believe, therefore, that consciousness and will may undergo as many divisions as there are separate nerve-centres in the body. Some go yet farther, and refuse to limit will to the nervous system, holding that they observe clear evi- dence of its action where there is no trace of either 142 THE PHYSIOLOGY OF MIND. [CHAP. muscular or nervous fibres. If a polype be placed in a glass of water, and if a living infusory animalcule be put in the water, and brought near to the polype, the latter perceives it somehow, and thereupon raises a whirlpool with its tentacles in order to bring it within their grasp and drag it into its stomach : an instance, it is said, of feeling and will in a creature which has neither muscle nor nerve. Assuredly they are logical in this extension of their theory ; but when they have endowed the polype with these conscious functions, they will do well to take heed that they are not suffering themselves to be beguiled by words, and to reflect whether there lurks not some obscurity and confusion in the use which they make of the words consciousness and will ; whether, in fact, they mean anything like the same things when they speak of the consciousness and the will of a polype, and when they speak of human consciousness and will. The dispute with their opponents must be vague and endless unless they agree upon some more precise definition of terms in accordance with the undoubted diversities of the facts. It will not advance knowledge to identify phenomena of a different kind by giving them the same name ; on the contrary, the progress of know- ledge lies in following the specializations of develop- ment, and in defining differences by a precise use of terms. The matter may be put briefly thus : does feel- ing imply that which a person means when he says / feel, / am conscious ? If it does, one cannot believe that the polype or the spinal cord has feeling ; if it does not, then some other term than feeling should be used to denote organic susceptibilities, or that so-called feel- ing which the individual has not as an ego, but which the least particle of his living protoplasm is assumed to have. In trying to determine whether the spinal cord is endowed with feeling and will, we shall do well to con- in.] THE SPINAL CORD. 143 sider how very small a part of a conscious and voluntary movement we are really conscious of. We know the end or aim of the movement, and we know that we give the order to accomplish it ; but the actual execution of it is left to the organized mechanism, innate or acquired, of the motor centres and their connections. The main part of a voluntary act is truly the automatic action of the spinal cord ; and the will is absolutely dependent upon the automatic mechanism for the accomplishment of its acts, while this may operate by itself independently of the will. It is clear, then, that the conscious has essential need of the automatic, while the latter has no need of it. Consciousness is a superfluity so far as the execution of the act is concerned, being, when it occurs, merely a co- effect Instead of attributing consciousness to the func- tion of the spinal cord, the lesson of nature teaches us rather to proceed in the opposite direction, and to take out of a voluntary act the large part which is strictly auto- matic, and which, the impulse once given, would be done as well without as with consciousness. It is well known that the impulse to an act which was first voluntary may, after the act has become habitual, be a stimulus from with- out; for movements that were at first executed consciously oftentimes become unconscious, and are done in answer to external stimuli. We remove an irritation which is acting upon some part of the body, as for instance a fly on the forehead, without being conscious of what we have done, unless we reflect afterwards. We have certainly no clear conception of the place of the irritation, or of the character and measure of the muscular exertion which we make, and we can hardly suppose that a dim conscious- ness or obscure conception would suffice to make so nice and exact an adaptation as takes place : a suppo- sition which would nevertheless have to be made if the adaptation were dependent on consciousness. Are we then to entertairi seriously the more improbable assumption 144 THE PHYSIOLOGY OF MIND. [CHAP. that the spinal cord has such an exact consciousness ? And yet this is an assumption which those must make who believe that the spinal cord feels impressions and responds to its feelings by exact purposive movements. The organized mechanism is the real automatic agency, and we shall see hereafter that the exact faculty of ac- complishing the act has been organized in it, built into its nature, so to speak, by previous training and experience. What we have to realize is that the afferent nerve is adapted to receive a certain impression and to convey it to the nervous centre, and that, the impression made, it does so receive and convey it whether we are conscious of it or not ; that when the impression reaches the centre, it stimulates the energy which is latent in it, whether we are conscious of it or not; and that this energy then acts upon the Afferent or motor nerve, and accomplishes the movement through the agency of the proper muscles, which we could not even select con- sciously if we would. It is entirely a physical pro- cess, which is nowise prevented from taking place because it is not accompanied by consciousness. Our own experience, rightly interpreted, is adverse, then, to the opinion that the movements of the decapitated frog evince that its spinal cord is endowed with consciousness. It is hardly conceivable, if it were so endowed, that the creature should never make a single spontaneous move- ment; that it should remain perfectly quiet until a new stimulus is applied ; that its activity should be pro- portionate to the stimulus ; and that it should not profit by its experience of previous excitations, notwithstand- ing that it is supposed to have so nice a consciousness of the place of the irritation and of the exact movements proper to relieve its sufferings. The way in which such movements as the mutilated frog makes may be prevented, furnishes further evidence of their mechanical nature. In the experiment in which in.] THE SPINAL CORD. 145 its leg is regularly drawn up on irritating its foot, it has been found by Nothnagel that no effect is produced if the sciatic nerve of the other leg is irritated by a faradic current This is an instance of what is called inhibition : some change is produced in the motor centres of the cord, which operates to inhibit or prevent the movement. Does not this experiment strengthen our conception of the entirely physical nature of the movements ? Take another example of reflex action similarly prevented. After division of the spinal cord in dogs, Goltz discovered that by touching the anus with a wet sponge, or tickling it, and by touching or pressing the foreskin, the sphincter of the bladder was relaxed, and a stream of urine ex- pelled, at first in a steady stream, and afterwards in jets, from the action of the bulbo-cavernous muscles. The con- traction of these muscles was at once arrested by press- ing on the foot of the animal. It may, of course, be said that these facts really furnish evidence that the spinal cord feels, and that the proper interpretation of them is in this wise : feeling the stimulus to the foreskin it responds by relaxation of the sphincter and contraction of the bulbo-cavernous muscles, but when a new impres- sion from the foot reaches it, its attention is distracted thereby, and it no longer feels the first impression. Let who will choose this conception : to me it appears to be the imagination of the phenomena of an unconscious consciousness, and an unwarranted application of ideas derived from experience of the highest nerve-centres to the interpretation of the phenomena of much lower centres. It is because of the adaptation to a purpose which these movements effected by the spinal cord show, because of the design manifest in them, that so many people find it hard to believe them to be purely reflex and unconscious ; they seem to have an insuperable difficulty in realising that adaptive reaction is a radical property of living organic matter, and that conscious 146 THE PHYSIOLOGY OF MIND. [CHAP. design is itself but a manifestation of this property in the highest nerve-centres. Much fruitless theory would have been avoided if the real nature of design had been kept distinctly in mind. The notion that the soul works unconsciously in the build- ing up of the organism, which has at different times been so much in vogue, rests entirely upon the assumption that an intelligent principle or agent must be immanent in organic matter which is going through certain definite changes. But if in the development of an animal, why not in the growth of a tree, which fulfils an equally definite plan, adapting itself wisely to its surroundings ? If in the formation of an organ, why not also in the formation of a chemical compound with its characteristic properties ? The function is the necessary result of a certain definite organic structure under certain conditions, and in that sense must needs minister to the furtherance of its well- being.* But an organic action, with never so beautifully manifest a design, may, under changed conditions, be- come as disastrous as it is usually beneficial ; the peri- staltic movements of the intestines, which serve so essential a purpose in the economy, may, and actually do, in the case of some obstruction, become the cause of intolerable suffering and a painful death. Where, then, * The proper course would be to reverse the method of our in- quiries and conclusions, and, instead of discovering the operations of soul in the processes of organic growth and development, to discover the properties of matter that are evinced by organic growth and de- velopment to operate in the construction of soul to place our feet firmly upo.i the lower steps before we attempt to go up higher. That appropriation of matter of force and concentration thereof in its sub- stance which organic element accomplished when it was first formed out of inorganic matter, and accomplishes constantly now when it in- creases and multiplies in plants and animals at the cost of inorganic matter, is what a higher tissue, like nervous tissue, does, with increas- ing complexity, when it is developed out of a lower tissue, and what is displayed, in a still higher degree of complexity, in the development of the mental structure and functions of the supreme cerebral centres. Hi.] THE SPINAL CORD. 147 is the design of their disastrous continuance ? The pro- cess of repair in a ruptured urethra will, instead of restoring the integrity of the canal and then coming to a stop, go on, with a final purpose singularly and obstinately mischievous, to produce an obliteration of the canal, unless human art come to the rescue. M. Bert has made many extremely interesting experiments on grafting parts cut from the body of one animal on to that of another. For example, he cut off the paw of a young rat, and grafted it in the flunk of another rat ; it took root there, and went through its normal growth, be- ginning to dwindle after a time. Where was the design of its going through its regular development there ? Or what, in the temporary adoption and nutrition of this useless member, was the final purpose of the so-called intelligent vital principle of the rat on which the graft was made ? The idea of design is really a conception which we form from repeated experiences of the law of the matter a law fulfilling itself in the effect necessarily, fatally, blindly and to which we transfer our experience of an event or end willed by us, and accomplished, not directly, but indirectly through intermediate steps or means. We are not in the habit of speaking of an im- mediate effect as the aim or design of the cause of the evolution of heat, for example, as the design of combus- tion, or of the properties of a chemical compound as the design of its combining elements ; but when a cause works effects, which in turn become causes of further effects and so accomplish finally a certain definite result, or when a concurrence of circumstances has led to an event, we recognize in the series of operations or the con- on rence of conditions a suitability or so-called adaptation of causes and conditions to the final effect; thereupon we pronounce this to be the aim or design of them, because if we consciously willed the effect, and brought it about 148 THE PHYSIOLOGY OF MIND. [CHAP. through such a chain of means, we should say rightly that we had designed it The more complex the process, so long as we perceive that it works out a definite result, the more we are struck with admiration of the design. Hence it is that organic nature is the fruitful field of final causes. But it is certain that when men have thus transferred to nature the experience of their imperfect working through means to an end, and have concluded the existence in it of a mind like their own, they have made a conception of God after their own image, which, as Spinoza remarked, divests him of his perfection. " For if God acts for an " end or purpose, he necessarily desires something which "he is without."* It will not be amiss to take note here of the very different way in which we are in the habit of regarding dead matter and living matter. In dead matter the form is looked upon as the attribute of the matter; whereas, on the other hand, in living bodies the matter is treated as the attribute of the form : in inorganic nature the matter is the essential thing, in organic nature the form is all in all. We cannot get rid of the notion of some mysterious potency in organic form which controls the action and determines the disposition of matter, be- cause we cannot get rid of the notion of matter as inert or dead. But matter is not inert ; not the smallest par- ticle of it which is not a complex system of atoms in most active and complicated movements ; and to neglect the exact consideration of the conditions and combinations of matter, as determining organic form, is not less mis- chievous than it is to concentrate all attention upon matter in inorganic nature. What are inseparably joined together in nature let us not vainly attempt to put asun- der. Mindful of this maxim we shall not be so much tempted to fall back upon that vague and shifting * Spinoza. Ethics: Parti., Appendix. Translated by R. Willis, M.D. p. 448. in.] THE SPINAL CORD. 149 doctrine of final causes which has done so great harm in science, or, as Bacon has it, has strangely defiled philo- sophy, and which, though often rejected absolutely, and now banished from the more advanced sciences, still works injuriously in biology, where so much is yet recondite and obscure. (') The human understanding can indeed best impose its own rules on nature in that province where the truth is most inaccessible and least known. Not only does it in biology look for a final cause answer- ing to its own measure, but, having found this, or created it, proceeds straightway to superadd its own attribute of consciousness, so that wherever evidence of design is met with, be it only in the function of the spinal cord of a decapitated frog, there consciousness is assumed. Is it not a marvel that no teleologist has yet been found to maintain that the final cause of the moon is to act as a " tug" to the vessels on our tidal rivers; or that the final cause of the redness of human blood is to facilitate the detection of the murderers who shed blood ? There can be no difficulty in admitting that the spinal cord is an independent centre of so called aim-working acts that are not attended with consciousness. It is the centre, however, not only of co-ordinate action the capa- bility of which has been implanted in its original consti- tution, but also of co-ordinate action the power of which has been gradually acquired and matured through indi- vidual experience. Like the brain, the spinal-cord has, so to speak, its memory, and must be educated ; the reaction which it displays, in consequence of a particular impression conveyed to it from without, does not vanish issueless, leaving the track unmodified after the function has been discharged. With the display of energy there is a coin- cident change or waste of nerve element ; and, although a subsequent regeneration or restoration of the statical equilibrium takes place by the quiet process of nutrition, yet the nutritive repair, following the track of the energy ISO THE PHYSIOLOGY OF MIND. [CHAP. and coincident material change, registers the experience. It is not an integration only which is accomplished, but a redintegration ; the substance is made whole after a par- ticular exercise of function after in pattern as well as time. Thereby the definite activity is to some extent real- ized or embodied in the structure of the spinal cord, exist- ing there for the future as a motor residuum, or as, so to speak, a potential or abstract movement ; accordingly there is thenceforth a tendency to the recurrence of the particular activity a tendency which becomes stronger with each repetition of it Every impression which is made leaves behind it, therefore, its trace or residuum, which is again quickened into activity on the occasion of an appropriate stimulus ; the faculties of the spinal cord are thus gradually formed and matured. We may easily note in the acquirement of a complex purposive movement the difficulty which there is at first in defining the path of the stimulus and directing it exactly to the proper muscles in limiting the excitation ; and we shall not fail to note hereafter that this is done, not by willing to put these muscles in action, but by clumsily imitating the move- ment until we attain to an exact imitation, or by making many trials of movements until we find out the most suitable one, and so get an unconscious mastery of the proper muscles. The path must be made, and the more often it is trodden the more distinct will it be : awk- wardly through trials and blunders we fall into the adjustment which we aftenvards perfect by experience. When a series or group of movements is, after many voluntary efforts, associated, they notably become more and more easy, and less and less separable, with every repetition, until at last they are firmly fixed in the consti- tution of the cord, become a part of the faculty of it, and may be accomplished without effort or even without con- sciousness : they are the secondary or acquired automatic acts, as described by Hartley. ( 3 ) Once the track has Hi.] THE SPINAL CORD. 151 been laid down it is easier for the stimulus to follow it than to leave it, just as it is easier for a train to run on the rails than to run off them, or for water to run in its channel than to run out of it In this way walk- ing becomes so far a reflex or automatic act that a man in a profound abstraction may continue to walk without being conscious where he is going, and find himself, when he is aroused from his reverie, in a different place from that which he intended to visit. In that form of epilepsy known as the petit mat an individual sometimes continues automatically, whilst consciousness is in abeyance, the act which he was engaged in when the attack seized him : a shoemaker used frequently to wound his fingers with the awl as he went on with his work, and on one occasion walked into a pond of water during the suspension of consciousness ; and a woman whom Schroeder van der Kolk knew used to continue eating or drinking, or the occupation she was about, being quite unconscious on recovery of what had happened. Trousseau mentions a young amateur musician subject to epileptic vertigo, who sometimes had a fit lasting for ten or fifteen seconds whilst playing the violin. Though he was perfectly unconscious of every- thing around him, and neither heard nor saw those whom he was accompanying, he still went on playing in time during the attack. The same author also mentions an architect who had long been subject to epilepsy, and did not fear to go up the highest scaffoldings, though perfectly aware that he had often had fits while walking across narrow planks at a considerable height He had never met with an accident, although, when in a fit, he ran rapidly over scaffoldings, shrieking out his own name in a loud and abrupt voice. A quarter of a minute afterwards he resumed his occupation and gave his orders to the workmen ; but unless he was told of it afterwards, he had no idea of his strange behaviour 152 THE PHYSIOLOGY OF MIND. [CHAP. during the fit.* In fact, if any one attends to his ordi- nary actions during the day, it will be surprising how small a proportion of them are consciously willed, how large a proportion of them are the results of the acquired automatic action of the organism. It is sufficiently evi- dent that the faculties of the spinal cord are, for the most part, not inborn in man, but gradually built up by virtue of experience and education ; in their formation they illustrate the progress of human adaptation to ex- ternal nature. Certainly the capability of associated voluntary move- ments, or the germ of such capability, does appear to exist as an innate endowment of the spinal cord even in man ; ready to come into action at the proper epoch of that development which goes on in him after birth, under the influence of suitable external conditions, until he reaches maturity. As the young animal, directly it is born, can sometimes use its limbs with complete effect, or as the infant, previous to any experience, is capable of that association or catenation of movements necessary to crying, breathing, or coughing, so soon as it meets with suitable external conditions ; so likewise does there appear to be, as Mr. Bain argues, t the germ of a loco- * " Their condition may be compared to somnambulism, or better still to what happens in the case of certain individuals who answer questions during sleep, but do not recollect anything when they wake up." TROUSSEAU, Clinical Lectures, vol. L, p. 60. t The Senses and the Intellect, 2nd ed. It has long been dis- tinctly recognized as a general law that when a moderate stimulus excites several motor nerves, these are physiologically connected : first, inasmuch as all the fibres going to a particular muscle are simultaneously excited, so that partial movement of the muscle does not take place ; secondly, as the regular reflex activity implicates such muscles as are functionally co-ordinated, the associated action of which produces certain physiological effects e.g., coughing, sneezing, swallowing. In the electric fish, the malapterus, the nerve going to the electric apparatus is at first a single fibre which divides and subdivides in its couise, until it furnishes as many branches as ill.] THE SPINAL CORD. 153 motive harmony in the original conformation of the nervous centres of man which develops rapidly at the proper epoch. Not only does the analogy of the lower animals favour the belief in the original existence of such an associating link, but the tendency to an alternate action of the lower limbs, and of the two sides of the body, observably precedes any acquisition of experience. Before a child can walk it will make alternate move- ments of its legs when it is held with its feet touching the ground. There is, furthermore, a proneness to the in- voluntary association of the motions of corresponding parts of the two sides of the body ; and, as Miiller has observed, the less perfect the action of the nervous system in man, or the less developed volition is, the more general are the associate movements. It would be a fruitless task, however, to attempt to fix the value of this pre-established arrangement in man, where it is obviously at best rather a potentiality than an actuality ; for all practical purposes, we must view the faculties of there are electric plates ; so that the creature cannot isolate a part of the apparatus, but must put all the plates into action together. As Sir C. Bell has remarked, "a child smiles before anything incon- gruous can_enter the mind, before even pleasure can be supposed a condition of the mind. Indeed, the smile on the infant's face is first perceived in sleep." Its forefathers have smiled, and it is the heir of their acquisitions. Contortions of its face from pain or uneasiness are witnessed long before smiles ( The Hand ; its Mechanism and Vital Endowments). The locomotive harmony is the result of the connections of certain cells and groups of cells in the nerve-centres. " Si I'homme, le lapin, le moineau, le pigeon, ne marchent pas des leur naissance, c'est uniquement a cause du developpement incom- plet des divers organes, et surtout, sans doute, des centres nerveux. Si 1'enfant naissait en prcsentant un degre de developpement egal a celui qu'offre le cochon d'Inde, il marcherait desle premier jour." VULPIAN (op. cit.), p. 529. What happens in the infant's nerve- centres when it does learn to walk, we know not : it may be that an actual growth of nerve-cells and of their connections takes place in the course of such education ; or it may be that pre-existent cells and connections are gradually differentiated in function. 154 THE PHYSIOLOGY OF MIND. [CHAP. his spinal cord as acquired by education. The child certainly has the capability of learning to walk, but the actual process of learning involves the expenditure of much time and energy, and represents a progressing development of the spinal cord : it is the faculty thereof in the making. Of course it is not to be supposed that the spinal centres of themselves suffice ordinarily for all the complicated movements of walking, although they may do so: all that is claimed is, that they are the automatic centres of certain associate movements which have been acquired, and which constitute a large part of our daily action.* This power of co-ordinate action, which the spinal centres acquire by assimilation of the influence of the individual's surroundings and respondent reaction thereto, is plainly a most useful, as it is a most necessary, provi- sion of nature. For if an act became no easier after being done several times, if the careful direction of conscious- ness were necessary to its accomplishment on each occa- sion, it is evident that the whole activity of a lifetime might be confined to one or two deeds that no progress could take place in development. A man might be oc- cupied all day in dressing and undressing himself; the attitude of his body would absorb all his attention and energy ; the washing of his hands or the fastening of a * Schroeder van der Kolk, after saying that the production of harmonized movement is due to the ultimate connection of certain groups of ganglionic cells in the spinal cord, goes on to say "It has always been incomprehensible to me, how any one could ever have referred it (co-ordination) to the cerebellum. If the cause of the co-ordination lay in the cerebellum, no harmonixed reflex move- ments could take place in a decapitated frog." On the Minute Structure of Spittal Cord ami Medulla Oblongata, p. 72. The sup- position that the cerebellum is the sole centre of co-ordination of movements is now, in fact, abandoned as untenable. There never was any real scientific evidence to support it, while there was positive evidence against it (See Vcrsuch einer physiologischen Pathologie 4tr A'erven, von. G. Valentin, 1864, vol. ii., p. 68.) Hi.] THE SPINAL CORD. 155 button would be as difficult to him on each occasion as to the child on its first trial ; and he would furthermore be completely exhausted by his exertions. Think of the pains necessary to teach a child to stand, of the many efforts which it must make, and of the ease with which it at last stands, unconscious even of an effort For while secondary automatic acts are accomplished with com- paratively little weariness in this regard approaching the organic movements, or the original reflex movements the conscious efforts of the will soon produce exhaustion. A spinal cord without that power of retention which in the higher centres we call memory would simply be an idiotic spinal cord incapable of culture a degenerate nervous centre in which the organization of special faculties could not take place. It is impossible for an individual to realise how much he owes to its automatic agency until disease has impaired its functions : and it is the lesson of a good education so consciously to exercise it in reference to its surroundings that it shall act auto- matically, in accordance with the relations of the indi- vidual in his particular walk of life. The phenomena of secondary automatic action are well fitted to exhibit the mode of origin and the nature of what we call design. It is here seen to be an acquisition that is gradually organized in respondence to particular experience and education ; representing as it does, the acquired nature of the nervous structure, its manifesta- tion is the simple result of the constitution of the mate- rial substratum, just as the properties of any chemical element are the unavoidable result of its nature. To say that means are adapted to the production of an end in the phenomena of life, is but another way of saying that what we please to call life exists ; for if means or causes were not adapted to the end or effect, there could plainly be no end ; and if we perceive, or choose to assume, a certain result to be the end of certain means, then we 156 THE PHYSIOLOGY OF MIND. [CHAP. are but saying that, according to our experience, certain combinations of matter have certain definite properties. The vulgar doctrine of final causes contravenes nature entirely, assuming as effect that which is truly cause, and as cause that which is truly effect In the building up of the secondary automatic faculties of the spinal centres, .ve are able to trace through the course of its formation in individual life that design which we meet with fully formed in the innate faculties of so many animals ; but which even in that case has been, as we shall hereafter see, gradually organized through generations. If it be said that the gradual building up by education of this embodied design into the constitution of the nervous centres is itself evidence of design, then we can only answer that such proposition is merely a statement in other words of the fact that things are as they are, and add the expression of a conviction that science cannot enter into the councils of creation. Certainly nothing is gained by taking refuge in that ' asylum of ignorance the Will of God.' The growth of a cancer until it kills the body, or of a vice until it ruins the mind, is neither more nor less evidence of design. Should these considerations not be satisfactory to the teleologists, it will be sufficient to recall to them the already quoted remark of Spinoza, and to congratulate them on their power of diving into "the mysteries of things, as if they were God's spies." Were it not well, however, that they should condescend to humble things, and unfold to us, for example, the final cause of the rudimentary mammary gland and nipple in the male animal ? * * A task which, after all, is perhaps not inconceivably difficult For example : we know that the male integrates the qualities of its male and female ancestors, having them potential or actual, and transmits them to its progeny : may we not conceive, then, that the rudimentary gland in it is a necessary condition of such complete inheritance and transmission, integrating the mammary characters ; and that, if the male were wiUiout it, it would be impossible for the in.] THE SPIXAL CORD 157 f As the faculties of the spinal cord are built up by organization, so must they be kept up by due nutrition. If not so preserved in vigour, if exhausted by excesses of any kind, the ill effects are manifest in degenerate action ; there is, so to speak, a decomposition of its composite motor functions ; instead of definite co-ordinate action ministering to the well-being of the individual, irregular spasmodic or convulsive movements ensue, which, though inevitable consequences of the degenerate condition of the nerve centres, serve no good end, but have strangely forgotten their beneficial design.* Sir James Paget has made the probable suggestion that the rhythmical organic movements, such as those of the heart, of respiration, of the cilia, are due to a rhythmical nutrition ; that is, " a method of nutrition in which the acting parts are, at certain periods, raised, with time-regulated progress, to a state of instability of composition, from which they then decline, and in their decline discharge nerve-force." f It may be easily conceived, therefore, why they are never tired when acting naturally ; between each succeeding act of function a nutritive repair takes place, and the time of each occurrence of the movement represents the time-rate influences of its female ancestors to take effect in the mammary de- velopment and function of its female progeny, as we have good reason to believe they do ? But, it may be said, if this argument is valid, it would involve this necessity : that the male shall have every organ which the female has, and the female every organ which the male has. Well, so they have ; or, at any rate, they have organs that are the homologues of one another. At one period of development we cannot distinguish the male from the female ; the subsequent differ- ences being produced by the female stopping short on, and diverging a little from, the track of development on which the male goes forwards. * They have, no doubt, their design quite as much as the healthy movements, in so far as they accomplish what they cannot he'p doing, their destiny in other words, fulfil the law which necessitates them. t CroontJH Lecture before the Royal Society, 1857. 158 THE PHYSIOLOGY OF MIND. [CKAP. of nutrition. When the heart is made to beat slowly by stimulation of the vagus nerve it will continue to beat for a long time, but when its pulsations are quickened by irritation of the sympathetic nerve, it soon becomes exhausted and stops, owing no doubt to exhaustion of its motor centres in consequence of nutrition being unable to keep pace with the quickened action. But the spinal centres are equally dependent on nutrition for the main- tenance of the functions which they discharge in the animal life ; the structural or chemical change produced by the ordinary activity of the day must be repaired during a period of cessation of action. This restoration we believe to take place during sleep ; and there is some reason to believe that the periodical action of the spinal centres is, like rhythmical organic movement, dependent upon, or closely related to, the time-rate of nutrition. The unconscious quiet manner in which the automatic function of the spinal centres is performed, though in one way or another the work is continuous during waking, might seem at first sight to render no cessation of action necessary ; but a little reflection shows that, here as else- where, the expenditure of force must be balanced by a corresponding supply ; there must be alternation of acti- vity and repose. If no rest be allowed, the exhaustion is evinced, first, in an inability to accomplish successfully the most delicate or complex associated movements in a loss, that is, of design ; then in trembling incapacity, which, if the degeneration increases, may pass on to actual spasmodic movements and finally to paralysis. Therein we have sure evidence that the constitution ot the nerve element has suffered from the drain of energy. A reflection which occurs, in considering the nervous mechanism by which the action and reaction between the individual and nature take place, is as to the dispro- portionate exhibition of force by the organism to the force of the simple impression which may happen to be in.] THE SPINAL CORD. 159 made upon it. How, with due regard to the principle of the conservation of force, do we account for this seeming generation of energy? In the first place, the central nerve cell is not a simple impassive body, which merely reflects or passes onwards a received current of activity, without affecting it or being affected by it : on the con- trary, it is the complexly constituted, supremely endowed centre in which force is released or evolved on the occa- sion of a suitable stimulus ; and that which is perceived, as it were, in the spinal cord is not the actual impression made upon the afferent nerve, but it is the effect pro- duced in the particular central nerve cell or cells. It is not hard to conceive how this force or energy is evolved, or, as it were, let loose in the cell. By the dis- turbance of the statical equilibrium of an intensely vital structure ; by a change of the material into lower kinds, or a degeneration of it, and a correlative resolution of its force into lower modes and larger volumetrical display. There is not any actual generation of energy ; there is a transformation of the high quality of latent or potential energy which the nervous monad implies into actual energy of a lower quality and larger display. The little change or motion which the impression makes at the extremity of the afferent nerve is propagated along the nerve and produces a much greater change or motion in the unstable nerve element of the central cell; an ex- plosion of molecular energy, so to speak, is occasioned, which thereupon is propagated in different directions to other cells, where it is similarly multiplied ; the final re- sult being the release of sufficient energy to accomplish the act. If, as has been calculated, the consumption of half a pound of carbon would produce an amount of heat which, if expressed in its equivalent of mechanical force, would be enough to raise a man of average weight to the highest summit of the Himalayas, it is clear that the oxi- dation of the complex carbon compounds of the nerve i6o THE PHYSIOLOGY OF MIND. [CHAP. element is sufficient to account for the nerve force which is liberated in its function. Consider what has been pre- viously said as to the nature of nerve element and its posi- tion in the universe, it will then be sufficiently evident what manner of process it is that takes place. Slowly and, as it were, laboriously, by a steady appropriation and ascent 1 through many gradations of vitality, does organic element .. arrive at the complex and supreme nature of nerve structure ; quickly and easily does nerve element give back force and matter to nature, in the rapid resolution which the accomplishment of its function implies. ( 4 ) Thus much concerning the inherent force of the spinal cord as a nervous centre. In the second place, bear in mind the nature of its acquired faculties, and the great expenditure of power made upon its education. In the registration of impressions made upon it, in the assimi- lation of their residua, there is slowly embodied a quantity of energy as an organic addition of power ; force is being stored up in the gradual organisation of its faculties. The exhaustion which we feel from our efforts to acquire any particular skill of movements, as in learning to dance, the labour given to the frequent voluntary repetition of the stimulus and adapted reaction thereto, until by prac- tice the definite relation has been established, and the desired skill acquired ; these testify to the expenditure of so much force which has been laid up as potential in the constitution of the ganglionic cells of the cord, rendering possible for the future the easy performance of a group of associated movements in answer to a moderate and, as might often seem, disproportionate stimulus from without Like the brain, the spinal cord lays up good store of power in its memory. Man's life truly represents a progressive development of the nervous system ; none the less so because it takes place out of the womb instead of in it The regular transmutation of motions which are at first voluntary into secondary automatic motions, as ill.] THE SPINAL COKD. 161 Hartley called them, is due to a gradually effected organisation in the proper centres ; and we may rest assured of this, that co-ordinate activity always testifies to stored-up power, either innate or acquired.* The way in which an acquired faculty of the parent animal is sometimes distinctly transmitted to the progeny as a heritage, instinct, or innate endowment, furnishes a striking confirmation of the foregoing observations. Power which has been laboriously acquired and stored up as statical in one generation, manifestly in such case becomes the inborn faculty of the next ; and the develop- ment takes place in accordance with that law of increas- ing speciality and complexity of adaptation to external nature which is traceable through the animal kingdom ; or, in other words, that law of progress from the general to the special in development which the appearance of nerve force amongst natural forces and the com- plexity of the nervous system of man both illustrate. As the vital force gathers up into itself inferior forces, and might be justly said to be a development of them, or as in the appearance of nerve force simpler and more general forces are gathered up and con- centrated in a more special and complex mode of energy ; so, again, a further specialisation takes place in the development of the nervous system, whether watched through generations or through individual life. Not by limiting our observation to the life of the indi- vidual, who is but a link in the chain of organic beings * The description of the spinal functions as reflex is not entirely free from objection, because the term is apt to convey the idea that the centripetal current of the afferent nerve is simply reflected on to the efferent nerve and becomes the centrifugal current ; whereas, as has been pointed out, the affair in the spinal centres is much more complex than that. We mean by reflex action function which is performed by the nervous centres, so far as we can judge, without will or consciousness mechanically ; not by virtue of any mysterious mental agency, but by virlue of the properties of the nerve structure. 1 62 THE PHYSIOLOGY OF MIND. [CHAP. connecting the past with the future, shall we come at the full truth ; the present individual is the inevitable conse- quence of his antecedents in the past, and through the examination of these alone do we arrive at the adequate explanation of him. It would be the function of an exhaustive psychology, having found any faculty to be innate, not to rest content there, but to follow steadily backwards the line of causation, and thus to display, if possible, its manner of origin. This is the more neces- sary with the lower animals, where so much is innate. Thus much concerning the general functions of the spinal cord as an aggregation of independent nerve centres, so far as they bear directly upon psychology. It must not be supposed that I have given an exhaustive de- scription of its functions in the animal economy. I have spoken of its intermittent activity, but it must be remem- bered that it is also in a state of continuous activity ; the permanent contraction of the sphincter being due ap- parently to a continuous influence exerted upon the motor nerves by its ganglionic centres. In like manner, all muscles that have antagonists, as, for example, the flexors and extensors of the arm, are kept in a certain degree of counter-activity, maintain a certain tonicity, as is immediately evident when their antagonists are para- lyzed ; this tonicity disappearing at once when the part of the spinal cord from which the motor nerves proceed is destroyed. It appears also to be of a reflex character, as it disappears when the excito-motor or sensory nerves of a part in a state of tonicity are cut But we may go even farther, and discover the functions of the spinal cord at work in the intimate processes of organic activity. Take one example of this far-reaching action. Certain blood- vessels are kept in a state of moderate contraction by the influence of vaso-motor nerves proceeding from ganglia lying close to the vessels, which ganglia are connected by nerves with the spinal cord. When these nerves are ui.] THE SPINAL CORD. 163 irritated the action of the ganglia is inhibited ; they cease to stimulate the walls of the vessels, which thereupon dilate and are filled with blood, so that the organ in which they are distributed becomes swollen and turgid. After the irritation of the nerves has ceased, the ganglia regain their power and cause the vessels to contract, so that the organ becomes flaccid. It appears, then, that a stimulus to the nerve centres of the spinal cord has several out- going channels of activity : it may act on the muscles, voluntary or involuntary, of the body, producing visible movements; or it may act upon the vessels, enlarging or diminishing their calibre, and so modifying the nutri- tion and function of the parts supplied by them ; or it may, as other experiments have shown, act directly upon the elements of a tissue, and so affect directly nutrition and secretion ; or it may pass to other nerve centres, and so occasion a variety of indirect effects. How manifold, far- reaching, and important these indirect effects may be, the experiments before-mentioned on the frog and the dog will help us to realise. When we find movements that are going on to be suddenly arrested by a new stimulus to the spinal cord, and consider what a complicated mechanism it is, and how many stimuli it receives, we may imagine vaguely what a variety of intricate and complicated functions, though we wot not of them, it is continually discharging every moment of our lives. It is not within the scope of this work to describe those special functions of the spinal cord which belong more properly to a treatise on physiology ; I am mainly con- cerned with those more general reflex functions which play so large a part in human activity, and which have, therefore, an essential place in psychology. An accurate knowledge of them affords the only solid basis from which to prosecute inquiry into the functions of the higher cerebral centres. We have seen that the spinal cord pos- sesses that power of retention which in the higher centres 164 THE PHYSIOLOGY OF MIND. [CHAP. we designate memory ; that by virtue of this power an act done for the second time contains something from the first act, and is done easier on that account ; that the faculty is strengthened by exercise, as memory is, until it becomes completely automatic ; and that an association or catenation of movements may be organised in the nerve centres, whereby movements that have taken place together several times may finally be so firmly bound together that there may be the greatest difficulty, or it may be actually impossible, to separate them, just, in fact, as ideas may be associated in the supreme cerebral centres. A spinal cord will do the acts, simple or complex, which it has inherited from ancestors or acquired by education the faculties to do, but if required to do new and strange acts, to associate in action muscles which have not acted together before, it will manifest an utter stupidity and impotence. It is an organised mechanism for the accom- plishment of the former ; it must be gradually organised as a mechanism in order to accomplish the latter. It may not be amiss to add that the reflex functions of the spinal cord were distinctly recognised by the physio- logist long before the anatomist was in a condition to give the physical explanation. It is only recently that the nerve fibres which pass to or from the spinal cord have been proved to be connected with the unipolar, bipolar, and multipolar cells of its grey substance ; and this so plainly as to justify the belief that an isolated apolar nervous cell does not exist in the spinal cord or brain. For the conveyance of an impression to the grey centres, and for the passage of the reacting force out- wards, there is thus revealed a definite physical path, along which the current of molecular activity travels. From the cells with which nerves are connected, again, other processes go to join neighbouring cells, and thus, forming a connecting path between them, enable them to act together : hundreds of ganglionic cells -xre yoked together in.] THE SPINAL CORD. 165 by such anastomoses, and, functionally co-ordinated there- by, represent the centres of innervation of corresponding systems of motor nerves. By similar anastomoses the gang lionic cells of different nervous centres are connected, and in this way a means is afforded for the communication of the activity of one centre to another; A consideration of the nervous system of the Annelida will assist in the con- ception of the physiological nature of the spinal cord. In those humble creatures the central nervous system con- sists of a ganglionic apparatus, each separate ganglion of which is united to that which precedes it, and to that which follows it, by longer or shorter nervous connexions.* Now the spinal cord of the Vertebrata may be considered as an analogous ganglionic apparatus, the connecting cords of which are not seen by reason of the coalescence of the ganglia. From a physiological point of view, there- fore, the grey substance may be considered as formed ot distinct segments, each segment consisting of a group or association of cells, and having connected with it the roots of two anterior motor and two posterior sensory nerves. Many, therefore, are the channels by which the activity excited in the nerve-cell by the stimulus of the efferent nerve may be discharged : it may be at once reflected on an efferent nerve, and through it discharge one or other of the functions which we have previously described ; or it may pass to other interconnected cells, and, acting thus upon a system of nerves, produce associ- ated movements, either such as proceed from the cord * Or take the bee as an illustration. If its head be suddenly cut off, and honey applied to its proboscis, sucking movements are made, showing that the co-ordinating centres for these movements are in the head segment. The body, when separated from the head, makes movements as if for collecting pollen, and if it be placed upon its back, it gets on to its feet again ; the centres for these movements being in the thoracic segment. If the abdomen be cut off, it is found that the centre for stinging movements is in this segment. Rcifhert and Du Bats' Archsv* H. I. 47, 1875. 166 THE PHYSIOLOGY OF MIND. [CUAP. nearly on the same level as the afferent nerve enters, or from a different level ; or, lastly, it may pass upwards, and excite the higher functionally co-ordinated centres. To Pfliiger belongs the merit of having first attempted to systematise the laws of the reflex movements. They are : i. The law of 'simultaneous conduction for one-sided reflex movements. When a reflex movement takes place on one side of the body only, in answer to a stimulus, it is always on that side of the body on which the irritation of the afferent nerve operates ; the reason being pro- bably that the motor nerves proceed from ganglionic cells which are in direct connection with the stimulated afferent nerves. 2. The law of symmetry of reflex action. When a stimulus has produced reflex movements on one side, and its continuance or its further extension in the spinal cord produces movements of the opposite side, then the corresponding muscles only of this side are affected. This is owing, no doubt, to the commissural system, which connects together the corresponding gang- lionic cells of the two halves of the cord. 3. The un- equally intense reflex action of the two sides in the event of both being affected. When the reflex action is stronger on one side than upon the other, the stronger movements take place upon the side of the irritation. 4. The law of irradiation of reflex action, by which an extension of reflex action takes place from the nerves in which it first appears to neighbouring ones, owing to the communications between the different systems or groups of ganglionic cells. When the excitation of an afferent cerebral nerve is transferred to motor nerves, it is observed that the roots of both sorts of nerves are placed nearly upon the same level in the central organ, or that the motor nerve lies a little behind or below, never in front of or above, the afferent nerve. If the reflex action spreads further, the way of irradiation is downwards to the medulla oblongata ; stimulation of the in.] THE SPINAL CORD. 167 optic nerve, for instance, produces contraction of the iris. In the spinal cord the primarily affected motor nerve lies nearly on the level of the stimulated sensory nerve. But if the reflex action spreads, then it passes upwards towards the medulla. When the irritation has arrived at the medulla, then it may pass downwards again. 5. The reflex action produced by the irritation of a sensory nerve can only appear in three places, whether one-sided or occurring on both sides of the body, (a) It appears in the motor nerves which lie nearly on the same level with the excited sensory nerve. (p) If reflex action implicates the motor nerves on a different level, these motor nerves are constantly such as spring from the medulla oblongata : tetanus and hysteri- cal convulsions in consequence of local irritations fur- nish examples, (c) The reflex action affects the muscles of the body generally ; the principal focus of irradiation thereof being the medulla oblongata. I go on next to indicate briefly the causes which affect the functional activity of the spinal cord ; the interest of the study lying in the fact that similar causes affect the functions of the higher nerve centres, and are the morbid conditions of the various phenomena of mental dis- orders : i. As an original fact, the ganglionic cells may have a greater or less stability of composition. It sometimes happens that a child is born with so great an instability of nerve element, that the most violent convulsions ensue on the occasion of very slight irritation. Or the evil may be less serious, and the individual may be equal to the ordinary emergencies of a quiet, favourably spent life ; but there is an absence of that reserve power necessary to meet the extraordinary emergencies and unusual strain of adverse events. When, therefore, an unaccustomed stress is laid upon the feeble nerve ele- ment, it is unequal to the demand made upon it, and 168 THE PHYSIOLOGY OF MIND. [CHAP. breaks down into a rapid degeneration. This innate feebleness is evinced by an excessive irritability ; it is truly an irritable weakness ; and its most common cause is an unfortunate inheritance, the curse of a bad descent. Any sort of disease of the nervous system in the parents seems to predispose more or less to this ill condition of the child ; the acquired deterioration of the parent be- coming the inborn organic feebleness of the offspring. The degeneration of nerve element in the ganglionic cells reveals itself in a disturbance of the co-ordinate or aim working activity which, as we have already seen, marks the highest development of its function. Convul- sions are the sure signs of a weakness or lowered ' vitality of nerve element, a defect which, though we cannot yet ascertain its exact nature, certainly implies an unstable equilibrium of its organic constitution. Each central nerve-cell exists in close relations, physical and physiological, with other nerve-cells ; when, regardless of these relations, it reacts directly outwards on its own account, it is very much like an individual in a social system who, by reason of madness, or of a criminal dis- position, rejects the restraint of social relations and breaks out in mischievous anti-social activity. Not only may an excess of irritability be a defect in the nature of the ganglionic cell, but this may be defec- tive also by reason of a great insensibility of nature and a want of power of assimilation. In congenital idiots the central cells of the cord do plainly sometimes partake of the degeneracy of the brain, and are idiotic also ; they are incapable of receiving impressions with any vividness, and of retaining the traces or residua of such as they do receive incapable of education. Spasms of the limbs, sometimes limited to the toe, to one arm or leg, at other times more general contractions of a foot, or of the knees to such degree as to. make the heels touch the buttocks ; more frequent still, paralytic in ] THE SPINAL CORD. 169 conditions of varying degree and extent, and atrophied limbs, now and then indulging in convulsive movement all these morbid states are met with in idiots, and, though in part attributable to the brain, are certainly in part due to degeneration of a spinal cord utterly obli- vious of its design or final purpose in the universe. In some cases where the morbid degeneration is not so extreme, it is not impossible to teach such combinations of movements as are necessary for the common work of life. It may be observed incidentally that the ease and rapidity with which those idiots who have by persever- ance been taught difficult feats of action perform them, and the machine-like exactness of their movements, dis- play well the important functions of the spinal cord as an independent nerve centre ; for they display its functions in a case in which the influence of the cerebral hemi- spheres is sometimes almost excluded. 2. The functional action of the spinal ganglionic cells may suffer from the too powerful or prolonged action of an external stimulus, or from an activity continued with- out due interval of rest The molecular degeneration or waste, which is the condition of functional activity, must be repaired by rest and nutrition^ the nerve-cell is no inexhaustible fountain of force, but must take in from one quarter what it gives out in another ; and if due time be not allowed and proper material be not supplied for the development of its highly vital structure by assi- milation of matter of a lower quality, it is certain that, notwithstanding the best innate constitution, deterioration must ensue as surely as a fuelless fire must go out. In that degeneration of the spinal cord which sometimes occurs in consequence of sexual vice or excess, one of the first symptoms is a loss of co-ordinating power over the motions of the legs a loss, in other words, of that which is the last organized faculty of the spinal centres. The starlings of the limbs and the partial contractions of i?o THE PHYSIOLOGY OF MIND. [CHAP. Certain muscles which may follow do not evince in- creased power, as some have heedlessly fancied, but are the indications of lowered vitality ; they are the inco- herent manifestations of a degenerate instability of nerve element. When such a morbid condition of things is brought about, there is necessarily a failure in the power of the ganglionic cells to receive and assimilate impres- sions : hence it is that in general paralytics, in whom the memory of each independent nervous centre is decayed, there is not only an inability to accomplish successfully the actions to which they have been accustomed as, for example, an inability of a musician, whom from his con- versation one would deem quite capable of his work, to perform on his accustomed instrument ; but there is also the impossibility of teaching them new combinations of movements. In other sorts of lunatics this is often possible : though mentally much degenerate, and actually lost for ever to the world, they may by persevering train- ing be made useful in certain simple relations to which they grow and react as automatic machines, their own cerebral hemispheres not interfering ; the general para- lytics, in whom the disease has advanced so far as to affect the spinal cord, cannot thus be utilized. 3. The supply of blood and the condition of it are manifestly of the greatest consequence to the welfare of the spinal cells. The grey matter of the cord is very richly supplied with capillaries, to the end that there may be a quick renewal of blood ministering to the active interchange that goes on between the ganglionic cell and the nutrient fluid ; the enormous consumption of force in nervous function demanding such an abundance of supply. What Mr. Bain describes as the spontaneous energy of nerve centres, and lays so much stress on as the foundation of volition, is probably the result of the state of the blood in them either of its compostion or of its distribution. We know at any rate that the IU.J THE SPINAL CORD. 171 movements of inspiration are provoked by an excess of carbonic acid in the blood circulating through the medulla oblongata and the spinal cord. How many modifications of nutrition, of secretion, and of the distribution of blood in the different organs, of which we can give no account, may be due to the character or the distribution of the blood circulating in the spinal cord ! When the supply of blood is suddenly cut off, as in the well-known experiments of Stannius, Brown-Sequard, and Schiff, the nervous activity is presently paralysed, and rigor mortis of the muscles ensues. When the supply of blood is soon restored to a part in which rigor mortis has taken place, as in Brown-Se'quard's experiment of injecting warm blood into the stiffened arm of an executed criminal, the muscles presently regain their contracti- lity, and the nerves their irritability. As a complete cutting-off of the blood is paralysis of nerve element, so a deficiency of blood, or of material in it fitted for the nutrition of nerve, is to the extent of its existence a cause of degeneration or instability of nerve element. Such deterioration is exhibited by cachectic and anaemic persons in a great irritability, and in a disposition to spasms or convulsions an acquired condition not unlike that which is sometimes inherited. The state of the blood may be vitiated by reason of the presence of some foreign matter which, whether bred in it or introduced from without, acts injuriously or as a direct poison on the individual nerve-cells. Strychnia notably so affects them that, on the occasion of the slightest stimulus, they react in convulsive activity ; while the curare poison, on the other hand, produces a sort of stupor or coma, and paralyses all activity. Curiously enough the methyl derivatives of strychnia, the iodide of methyl-strychnium and the sulphate of methyl-strychnium, according to the observations of Drs. Frazer and Crum Brown, produce exactly the same symptoms as the 172 TILE PHYSIOLOGY OF MIND. [CHAP. curare ; showing that a slight difference in the chemical composition of a substance may occasion a great differ- ence in its physiological effects. Moreover, if a suffi- ciently large quantity of strychnia be introduced under the skin of a frog, the effects may closely resemble those produced by the curare; death taking place without any, or with only very feeble, convulsions. Opium, which usually produces coma in man, produces convulsions in frogs, and sometimes in children. We might, were it needful, accept these different effects of poisons, which are alike positively injurious to the integrity "of nerve element, as evidence that convulsions do not mean strength : they are not the result of an increase in the proper vital activity of parts ; on the contrary, they evince degenerate function and are the forerunners of paralysis. The various vegetable poisons indicate also, by their different effects upon the same and upon different struc- tures, the fine differences of composition in the gang- lionic centres of the central nervous system ; in this way they throw some light as chemical reagents upon the nature of physiological functions, and they are the most sensitive reagents in this regard which we yet possess. There is reason to believe that the presence of too much blood in the spinal cord may be as baneful as an insufficient supply. All the symptoms of disorder of nerve element which accompany anaemia may certainly be produced also by congestion or congestive hyperaemia ; the proper nutritive interchanges, the supply of suitable nutrient products and the removal of effete products, being as much impeded or checked by stagnation as by deficient supply of blood. The blood-vessels are fur- nished with vaso-motor nerves which regulate their calibre and therefore the amount of the supply of blood, and these nerves are more or less plainly under the control of spinal centres. It is obvious that an undue contraction in.] THE SPINAL CORD. 173 or dilatation of the vessels may affect temporarily the function, or permanently the nutrition, of the nerve centres, and so occasion morbid phenomena. 4. The existence of a persistent cause of eccentric irritation, whether the result of injury or disease in some part of the body, may give rise to a morbid state of the spinal nerve-cells by a so-called sympathetic or reflex action. This may be considered a pathological appli- cation of physiological function which is in constant operation. Volkmann has observed movements to be produced in the limbs of a decapitated frog by stimula- tion of the intestinal canal ; the results being much more evident if the animal has previously been poisoned with strychnia. In a well-known experiment by Goltz a sharp tapping upon the abdomen of a frog produces a sudden arrest of the heart's action; and it has been recently shown by Tarchanoff that when a loop of the intestine with its corresponding piece of mesentery is pulled out of the abdomen of a frog, and exposed to the air for a few hours until if becomes inflamed, the slightest touch of the inflamed loop will suffice to produce a stoppage of the heart's action within from a few seconds to half a minute.* The stimulus is carried to the medulla oblon- gata, there reflected upon the vagus nerve, and operates through it upon the ganglia of the heart ; for the effect does not take place if conduction be arrested by section of the vagus or by poisoning with curare. The convulsions which sometimes take place during teething in children, owing to the presence of worms in the intestines, are familiar examples of sympathetic or reflex effect upon a susceptible growing nervous system. It is necessary to distinguish two kinds of effects of this reflex action or, perhaps, different degrees of the same kind of effect namely, a reflex functional modification and a reflex nu- tritive modification. * Archiv de Physiologic, 1875, P- 48- 9 174 THE PHYSIOLOGY OF MIND. [CHAP. The irritation of a decayed tooth may, as is well known, give rise to a contraction of the muscles of one side of the neck, or to a violent facial neuralgia, or to blindness or deafness, all which presently disappear upon the re- moval of the cause of the mischief. A functional derange- ment only has existed so far. But the irritation of a bad tooth produces a greater and more lasting effect, when, as does now and then happen, an abscess in the glands of the neck takes place in consequence of it, and remains an incurable fistula until the removal of the scarce sus- pected cause. The nutritive derangement has been caused and kept up by the reflex irritation. It must cer- tainly be allowed that the functional disorder, when it alone seems to exist, does testify to some kind of change in the molecular relations of the ganglionic cells ; but as the abnormal modification vanishes the moment the real cause of mischief, the bad tooth, is gone, it is scarcely possible to view the disturbed function as evidence of any serious chemical or organic derangement in the nerve-cells. With the continuance of the cause of irritation, the func- tional disorder undoubtedly may, and is liable to, pass into disorder of nutrition. The relations of these differ- ent degrees or kinds of derangement to the morbid cause are such that we might not unfairly represent the sole existing functional derangement as due to a modification of the polar molecules of the nerve element, while the abnormal nutrition may be supposed to mark an actual chemical change in its constitution. Again, as the spinal centres minister both to our animal life and to our organic life, they necessarily have, in the former case, a periodical function ; in the latter case, a continuous function. When, therefore, a morbid condition of the ganglionic cells subserving animal life exists, the functional derangement will probably be not continuous but intermittent. Intermittence of symptoms is indeed a common, almost a constant, feature of nervous disease, HI.] THE SPINAL CORD. 175 and I know not why we should be surprised thereat, if we reflect that alternation of rest and activity is the law of the nervous functions of animal life. Thus, in epilepsy, it appears as if the reacting centres must be gradually charged until they reach a certain tension or instability, when the statical equilibrium is destroyed, and they dis- charge themselves violently. Something of the same kind takes place in the poisonous action of strychnia : a dog so poisoned will fall down in convulsions, but, according to Schroeder van der Kolk, they cease after a time, and the animal seems to be perfectly well ; even for so long as an hour it may be touched or stroked without harm ; after which the susceptibility again becomes so great that by simply blowing upon the skin convulsions are repro- duced. The molecular explosions in the intimate elements of nerve tissue produce molecular exhaustion ; and when the energy of the parts is restored by respite and repair, the morbid instability is restored, so long at any rate as the morbid conditions remain. If the dog can be kept alive until the strychnia is eliminated by the secretion, then the restoration of energy will be the gradual restor- ation of a stable equilibrium of molecules; the convulsions will become less and less violent and finally cease ; and the animal will recover. When, on the other hand, the function of the spinal centres ministering to the organic life is deranged, the morbid effect will most likely be continuous. The experiments of Lister, showing that the movements of the granules in the pigment cells of the frog's skin are under the control of the spinal system, and the investigations of Bernard and others, agree to prove that the cerebro-spinal axis may not only control the contractions of the small arteries, but that it directly in- fluences the organic elements engaged in nutrition and secretion. The moment food is introduced into the mouth there is a flow of saliva and of gastric juice. 1 76 THE PHYSIOLOGY OF MIND. [CHAP. Numerous examples have been of old quoted of distant modifications of nutrition in consequence of some irrita- tion of a centripetal nerve : a large secretion of extremely acid gastric juice has been cured by the extirpation of painful piles ; ptyalism is produced sometimes, as lachry- mation frequently is, by neuralgia of the fifth nerve; irritation of the uterus, or of the skin of the breasts, or of the mucous membrane of the vagina, has been known to give rise to the secretion of milk ; and menstruation may follow irritation of the ovaries, or the application of warm poultices to the breasts. We witness phenomena due to this reflex nutritive action again in the sympathy which one eye so often exhibits with disease of the other ; in the congestion of the eye or the actual amaurosis which sometimes accompanies severe neuralgia; in the para- plegia due to displacement or disease of the uterus ; and in many other instances too numerous to be mentioned. Pfliiger quotes from Dieffenbach a striking case, which admirably illustrates the effects of an eccentric irritation upon the spinal cord. A young girl fell upon a wine-glass, and cut one hand with a piece of the broken glass ; for years afterwards she suffered from violent neuralgic pains and emaciation, with contraction and complete useless- ness of the hand; she was afflicted also with severe attacks of epilepsy. On cutting through the cicatrix of the old wound, a minute splinter of glass, which had wounded the nerve, was detected ; the nerve was also thickened and hardened. After removal of the glass, the neuralgia and epilepsy disappeared, and the girl recovered the entire use of her hand. These instances of morbid reflex function prove how complete is the unity of the bodily life, and how important and far-reaching may be, through the agency of the unifying nervous system, the effects of disorder of what seems a trivial part. In truth, we can call nothing trivial in the marvellous consensus of energies which a living organism is ; and a prudent man ill.] TIfE SPIRAL CORD. 177 will deem it a sacred duty to keep holy, i.e. healthy, the temple of his body.* 5. lastly, the severance of the connection between the brain and the ganglionic cells of the spinal cord seems in some degree to affect their function. When a nerve is cut across in the living body, the peripheral end soon undergoes fatty degeneration, while the central end re- mains unchanged after years; and this degeneration is not owing solely to the inactivity of the nerve, for it still takes place when the nerve is regularly stimulated, and takes place much less quickly in frogs and cold-blooded animals, in which nutrition is sluggish, than in warm- blooded animals, in which it is active. It is perhaps a fair conclusion that the nerve fibres have their nutrition subjected in some measure to the nerve centres; that these play in relation to them the part of nutritive centres. After apoplexy in or about the corpus stria- turn, Turck professes to have found granular cells in the course of the fibres as they pass downwards, so that such cells were met with in the spinal cord on the opposite side to the seat of disease. It is known, too, that the removal of the brain in the lower animals increases the ease with which reflex movements take place ; and there are many cases on record in which the reflex action has been increased in man when disease or injury has interrupted the continuity of the spinal centres with the brain. May we not, then, conclude from such facts that a positive nutritive influence is exercised by the brain upon the ganglionic cells of the cord and upon the nerve fibres which proceed from the cerebro-spinal axis, as well * It is known that a small cause of irritation may cause tetanus. Dr. Taylor {Medical Jurisprudence) mentions a fatal case of tetanus, which was at first thought to be idiopathic, but which was found to have been really caused by a small splinter of wood that had pene- trated the thumb. And Dr. G. Johnson has recorded a case of tetanus which was cured by the removal of a small piece of the fibre of cloth from the scar of an old wound. 178 THE PHYSIOLOGY OF MIND. [CHAP. as by the spinal centres on the nerve fibres which proceed directly from them and upon the subordinate ganglia? In fact r may we not justly conclude that this influence, which was expressed by old writers as the secretion of the vital spirits by the brain, is exerted by every nerve centre on the centre which is subordinate to it,* and on the nerves which proceed from it; and that the inhibitory action which a higher nerve centre is observed to have upon the function of a lower centre may be really an instance of its exercise ? The inference would be agreeable to what we know of the direct functional action of the brain upon that of the cord ; the reflex acts in health being for the most part notably subordinate to the control of the will As a guiding influence passes from above downwards when the cerebro-spinal system is ministering to the functions of animal life, so it is not improbable that the brain, in the accomplishment of its function as an organ of organic life, exerts some power which is favourable to the nutri- tion of the parts which lie below it, and which are the instruments through which it acts. This influence being withdrawn, an exaggeration of the excitability of the cord occurs, such as a wound causing tetanus may produce, or such as was produced by Brown-Sequard in guinea-pigs, when, having injured their spinal cord two or three weeks before, he was able to excite epileptiform convulsions at will by pinching the skin over a certain area of the face. It is true that some have thought to explain in another way the increase in the reflex movements which follows the severance of connection between the brain and cord ; * "As the brain secretes the vital sphits, and as in animals endowed with brain it is requisite that the nerves be supplied with these, as the medium for the transmission of impressions, the brain must be considered as being necessary, at least, to the continued pro- duction of nerve-actions ; unless the animal be so constituted that the vital spirits are secreted in the medulla of the nerves, or in theU ganglia, as in a vertebrate animals." UNZKR (op. fit.), p. 225 lit.] THE SPINAL CORD. 179 they have attributed it to the augmented energy of the spinal centres, and to the concentration of the stimulus, now that a path for the dispersion of its force is cut off. Such theory is hardly innocent of the vulgar error of regarding as increased energy that which is truly a diminution or deterioration of the higher vital energy of the part The co-ordinate reflex acts which take place in answer to the natural tactile impressions are not made more energetic or effective by cutting off the influence of the brain ; only the irregular reflex move- ments that follow chemical, electrical, or strong me- chanical stimuli are increased. One most important function of the brain is to exert an inhibitory power over the nerve centres that lie below it, just as man exercises a beneficial control over his fellow animals of a lower order of dignity ; and the increased irregular activity of the lower centres that have escaped from control betokens degeneration : it is like the turbulent, aimless action of a democracy without a head. Such, then, are the disturbing causes which may affect the activity of the spinal cord, both as a conducting path and as an independent centre of the generation of nerve- force. When we reflect upon the great proportion of the daily actions of life that are effected by its unconscious agency, we cannot fail to perceive how important is the due preservation of its integrity. No culture of the mind, however careful, no effort of the will, however strong, will avail to prevent irregular and convulsive action when a certain, degree of instability of nerve ele- ment has, from one cause or another, been produced in the spinal cells. It would be as absurd to preach control to the spasms of chorea, or restraint to the convulsions of epilepsy, as to preach moderation to the east wind, or gentleness to the hurricane. That which in such case has its foundation in a definite physical cause must have its cure in the production of a definite physical change. l8o THE PHYSIOLOGY OF MIND. [CHAP. So certain and intimate is the sympathy between the individual nerve-cells in that well-organized common- wealth which the nervous system represents, that a local disturbance is soon felt more or less distinctly throughout the whole state. When any sericus degeneration of the ganglionic cells of the cord exists, there is not only an indisposition or inability to carry out as subordinate agents the commands which come from above ; but there is a complaint sent upwards a moan of discontent or pain reaches the supreme authority. That is the meaning of the feelings of weariness, heaviness, achings of the limbs, and utter lassitude which accompany disorder of the spinal centres ; and the convulsive spasms and the local contractions or paralysis of muscles are the first signs of a coming rebellion. If the warnings do not receive timely heed, a riot may easily become a rebellion ; for when organic processes, which normally go on without consciousness, force themselves into consciousness, it is the certain mark of a vital degeneration. If the appeal is made in vain, then further degeneration ensues. Not only is there irregular revolutionary action of a subordi- nate, but there is pro tanto a weakening of the supreme authority ; it is less able to control what is more difficult of control. When due subordination of parts exists, and the individual cell conforms to the laws of the system, then the authority of the head is strengthened. A foolish despot, forgetting in the pride of his power that the strength and worth of a government flow from and rest upon the well-being of the governed, may fancy that he can safely disregard the cry of the suffering and the oppressed ; but when he closes his ears to complaints, he closes his eyes to consequences, and finally wakes up to find his power slipped from him, and himself entered upon the way of destruction. So is it with the nervous system : the cells are the individuals, and, as in the state, so here, there are individuals of higher dignity and in.] THE SPINAL CORD. 181 of lower dignity ; but the well-being and power of the higher individuals are entirely dependent upon the well- being and contentment of the humbler workers in the spinal cord, which do so great a part of the daily work of life. The form of government is that of a constitutional monarchy, in which every interest is duly represented through adequate channels, and in which, consequently, there is a proper subordination as well as co-ordination of parts. I have lingered thus long upon the spinal cord, because most of what has been said concerning its functions may, with the necessary change of terms, be applied to the higher nervous centres. A distinct conception of the nature and mode of development of the functions of the spinal centres is the best, is indeed the only adequate, preparation for an entrance upon the study of cerebral function ; it is an indispensable prerequisite to the right understanding of the higher displays of nervous function, and alone fixes the sure basis whereon to build a true mental science.* In this way we apply the laws gene- ralised from the more simple cases to disentangle the phenomena of the more complex cases. Any system not * In the Archiv. fiir Physiolog. Heilkunde, 1843, there is an ex- cellent paper by Prof.Griesinger, " Ueber psychische Reflexactionen. mit einem Blick auf das Wesen der psychischen Krankheiten ;"and another in the same Journal for 1854, "Neue Beitrage zur Physio- logic und Pathologic des Gehirns." In the Journal of Mental Science (January 1876) is an histori- cal and critical paper by Dr. Laycock, entitled " Reflex, Auto- matic, and Unconscious Cerebration," in which he gives a full and detailed account of the first promulgation by himself, in this country, of the doctrine of the reflex action of the brain, and of its subsequent development. It appears from this paper that he first broached the doctrine in 1840, in his "Treatise on the Nervous Diseases of Women," although he did not fully expound it until he read a paper "On the Reflex Function of the Brain" before the British Medical Association in 1844. The paper was afterwards published in the British and Foreign Medical Reviau, January 1845. 182 THE PHYSIOLOGY OF MIND. [CHAP. so founded follows not the order of development in nature, and must be unstable and insecure : Nature herself protests against it with energetic eloquence when she makes, as she unquestionably sometimes does, morbid action of the cells of the cerebral hemispheres vicarious of the morbid action of the spinal cells. NOTES. * (p. 139). Pfliiger compares the movements of a decapitated animal with those of a sleeping man, deeming the movements in both to be conscious. He tickled the right nostril of a sleeping boy, and the lad rubbed it with his right hand : when Pfliiger tickled the left nostril the lad rubbed it with his left hand. If he held the sleeper's right hand without waking him, and tickled his right nostril, the boy first made attempts with his right hand to rub it, but when this did not succeed, and the irritation continued, he then made use of the left hand. " Crickets allure to sexual congress after decapitation by the vibration of their wings ; and Redi, Bibiena, and others, have ob- served that butterflies, after having copulated but once in their lives, repeat the function repeatedly when decapitated, and the females, after sexual congress, deposit their eggs as carefully as if excited thereto by their instinct." UNZER. On the New System, Syd. Soc. Trans, p. 287. Thus the fluttering of the wings of the female butter- fly excites the sexual organs of the male, but only when the route has been laid down by an accomplished sexual act ; for no such effect is produced unless sexual congress has taken place at least once before decapitation. On the first occasion a sensory stimulus must co-operate with the purely reflex stimulus ; the latter suffices after- wards. The following quotation is from Spinoza, as translated by M. Saisset : " Personne, en effet, n'a determine encore ce dont le corps est capable ; en d'autres termes, personne n'a encore appris de 1' experience ce que le corps peut faire et ce qu'il ne peut pas faire, par les seules lois de la nature corporelle et sans recevoir de Tame aucune determination." "This is not astonishing," he adds, "as no one has sufficiently studied the functions of the body," and in- stances the marvellous acts of animals and somnambulists " toutes choses qui montrent assez que le corps humain, par les seules lois de la nature, est capable d'une foule d'operations qui sont pour 1'ame in.] THE SPINAL CORD. 183 jointe a cc corps un objet d'&onncment. .... J'ajoute eufiu que le mccanisme clu corps humaiu est fait avcc un art qui surpassc in- imiiiiont 1'industrie humaine." The associating link of many move* ments as, for example, of those of the heart, of the eye, of breath- ing plainly exists in the conformation of the nervous centres ; the wisdom or design is exhibited in the primary arrangement, whereby the reactions of the organism necessarily following do, as a rule, minister to the furtherance of its well-being. ' (p. 149). "And therefore it was a good answer," said Bacon, ' ' that was made by one, who, when, they showed him, hanging in a temple, a picture of those who had paid their vows as having escaped shipwreck, and would have him say whether he did not now acknow- ledge the power of the gods, 'Ay,' asks he again, 'but where are they painted that were drowned after their vows ? ' " Speaking of final causes, upon which the human understanding falls back, he says that they " have clearly relation to the nature of man rather than to the nature of the universe ; and from this source have strangely denied philosophy." Nov. Org. Aphorism xlvi. To the same effect Spinoza wrote : " But we are not to overlook the fact, that they who advocate this doctrine, and who have desired to find scope for the display of their ingenuity in assigning causes, have had recourse to a new style of argument to help them in their conclusions, namely, by reduction not to the impossible or absurd, but to ignorance or the unknown ; a procedure which shows very plainly that there was no other course open to them. If, for instance, a stone or tile fell from a house-top on the head of any one and killed him, they demonstrated in their way that the stone or tile fell to the end that the man might be killed. For if not to this end, and the special will of God, how should so many concurring circum- stances (and very many circumstances do often concur in such a case) have led to the event ? You will reply, perhaps, that the event happened because of the rough wind, the loose tile, and the presence of the man on the spot. But they will then urge : wherefore blew the wind so rudely? Why wa the man at the particular instant on the very spot on which the tile must fall ? If you answer, that the wind blew because of the neighbouring tempest, whose approach was indicated by the heaving of the sea on the pre- ceding day, though the weather was then fine, and because the man had been invited, and was on his way to the house of a friend, they will still go on to ask for in such a case there is no end of asking why the tempest arose at a distance on the day before, and why the man was invited at that particular time, the cause of a new cause inquired for in endless sequence, until shelter is sought in what in 184 THE PHYSIOLOGY OF MIND. [CHAP. such a case is called the Will of God, the asylum of ignorance. So also when they regard the structure of the human body they are amazed ; and because they are ignorant of the cause of so much art, they conclude that it has been contrived and put together by no mechanical, but by some divine or supernatural art, in such wise that each part in serving its own purpose is not injurious to another. And thus it comes that he who inquires into the true causes of miracles and prodigies, and who admires the harmony of natural things as a person of knowledge and understanding, and not as a simpleton, is everywhere proclaimed an infidel and impious per- son, and is so regarded by those whom the vulgar bow before as the interpreters of nature and the Divine decrees. For these men know that with ignorance removed wonder ceases, and the only means they have of enforcing their dicta and preserving their authority comes to an end." 3 (P- 1 5)- "After the actions which are most perfectly voluntary have been rendered so by one set of associations, they may, by another, be made to depend upon the most diminutive sensations, ideas, and motions, such as the mind scarce regards, or is conscious of ; and which, therefore, it can scarce recollect the moment after the action is over. Hence it follows that association not only con- verts automatic actions into voluntary, but voluntary ones into automatic. For these actions, of which the mind is scarce con- scious, and which follow mechanically, as it were, some precedent diminutive sensation, idea, or motion, and without any effort of the mind, are rather to be ascribed to the body than the mind, i.e. are to be referred to the head of automatic motions. I shall call them automatic motions of the secondary kind, to distinguish them both from those which are originally automatic, and from the voluntary ones ; and shall now give a few instances of this double transmuta- tion of motions, viz. of automatic into voluntary, and of voluntary into automatic." He instances the manner in which children learn, and especially the way we learn to speak, to play on the harpsi- chord, &c. " The doctrine cf vibrations explains all the original automatic motions ; that of association the voluntary and secondarily automatic ones." HARTLEY'S Theory of the Hitman Mind, edited by Priestley, pp. 31, 37. 1795. Unzer clearly recognised the nature of the acquired automatic acts : " And, on the contrary, we seek at first to avoid many pains and other unpleasant external sensations by voluntary movements, which afterwards become purely automatic, as, for example, shout- ing, writhing and retracting when in pain ; the quickened walk and the drawing up the legs to the body in severe cold ; the contraction HI.] THE SPINAL CORD. 185 of the eyelids in a strong light, and a thousand other movements, the objects of instincts, formerly volitional, but become mechanical from frequent repetition. Neither can we infer that the sentient actions of an instinct, which in us or in another animal are volitional movements, must have been such formerly, or will be for the future, or are such in any other creature." Op. cit., p. 152. * (/. 160). " Impressionum sensoriarum in motorias reflexio, quos in sensorio communi fit, non peragitur juxta solas leges physicas, ubi angulus reflexionis zcqualis est angulo incidentiae, et ubi, quanta fit actio, tanta etiam sequitur reactio ; sed leges peculiarea, a naturd in pulpam medullarem sensorii quasi scriptas, sequitur ista reflex io quas ex solis effect ilms tantum noscere, neutiquam vero assequi nostro ingenio valemus. Generalis tamen lex, qua commune sen- sorium imprcssiones sensorias in motorias rcllectit, est nostri con- servatio : ita ut imprcssiones externas corpore nostro noscituras scquantur certse impressiones motoriae, motus productune eo colli- niantes, ut monumentum a corpore nostro arceatur, amoveaturque ; et vice versa impressiones externas seu sensorias, nobis profuturas, sequantur impressiones internse seu motorioe, motus productune eo tendentes, ut gratus ille status ultra conservetur." PROCHASKA, op. cit. p. 88. Unzer had upheld the same doctrine, describing the effects re- spectively as connatural and contranatural (naturlich und wider- naturlich), according as they are in accordance with the well-being of the organism or not. CHAPTER IV. SECONDARY NERVOUS CENTRES, OR SENSORY GANGLIA ; SENSOR WM COMMUNE. THE diffefent collections of grey matter in the medulla oblongata, and at the base of the brain, consist chiefly of the nervous centres of the senses with corresponding centres of motor reaction. They are really continuations of the grey substance of the spinal cord, from which they are differentiated by more specialised functions. Con- tinuing the grey substance as high as the floor of the lateral ventricles, they include the optic thalami, the corpora striata, the corpora quadrigemina, and the different sensory centres that are placed in the medulla oblongata, the tuber annulare, and the cerebral pedun- cles. The olfactory bulbs, which lie at the base of the anterior cerebral lobes, must also be included in the sensorium commune. Any one of the senses may be destroyed by injury to its sensory ganglion as surely as by actual destruction of its organ; blindness is pro- duced by injury to the corpora quadrigemina, smell is abolished by destruction of the olfactory bulbs. These ganglionic centres are thus intermediate between the hemispherical ganglia above and the spinal centres below ; to those they are subordinate, to these they are superordinate. In many of the lower animals, as already pointed out, the brain consists of nothing more than the sensory ganglia, with centres of motor reaction ; there are no superimposed cerebral ganglia. CHAP, iv.] SECONDARY NERVOUS CENTRES. 187 It is not the place here to enter into a discussion of the different opinions which have been entertained con- cerning the exact centres of the different senses ; much of what is said on these difficult questions being still conjec- tural. It has for some time been supposed that the seat of common sensation is in the thalami optici, because it is in these bodies that the posterior or sensory columns of the spinal cord seem to terminate ; and that the cor- pora striata, to which the anterior or motor columns of the cord pass, are the corresponding motor centres. Vulpian, however, has brought forward strong arguments in favour of assigning the seat of common sensation to the tuber annulare. After the removal of the corpora striata, the tubercula quadrigemina, and the cerebellum the tuber annulare and the medulla oblongata being the only parts of the encephalon left he found that dogs and rabbits evinced, by violent agitation and decided cries of suffering, the pain felt when severely pinched or otherwise irritated. Moreover, injuries of the thalami optici, pathological or experimental, do not weaken sensibility, but do often produce motor paralysis. He concludes that we are yet in entire ignorance of the special functions both of the thalami optici and the cor- pora striata. Notwithstanding this opinion, those who have examined the arguments on this subject will pro- bably conclude that Vulpian's theory concerning the tuber annulare has blinded him to the import of the evidence in favour of the thalami optici and the corpora striata as sensory and motor centres respectively. It may well be that they are not the entire centres, and that there are other centres of sensibility and motion in the tuber annulare and cerebral peduncles ; but that they do minister to those functions it is hardly possible to doubt. Luys looks upon the thalami optici as a kind of sen- sorium commune in which all sensations meet. But it is not by any means certain that all the sensory nerves go 188 THE PHYSIOLOGY OF MIND. [CHAP. to them, some of these nerves apparently going directly to the cortex of the hemispheres, while it is tolerably certain that some motor nerves are connected with them. Wundt makes the conjecture that they are centres of reflex functions in which the impressions of touch are received and transformed into corresponding movements. That destruction of them is not followed by loss of sensibility of the skin may be owing to the fact that some sensory fibres ascend beneath them directly to the hemi- spheres. He looks upon the chief portion of the cor- pora striata as a motor centre through which the impulses of the will coming downwards from the cerebral hemi- spheres act upon the motor nerves ; the remaining small portion at their base being a centre in which the central olfactory fibres and certain motor fibres terminate.* Meanwhile all that concerns us here, in dealing with the cerebral functions from a psychological point of view, is to have some general term to embrace and designate all the centres of sensation ; and for this purpose I shall employ the term scnsorium commune, using it as a generic term to denote the common centres of sensation, and not, as Vulpian and some others have misused it, as a special term to designate the centres of common sen- sation. In a similar psychological sense I shall subse- quently use the terms motorium commune and intellcctorium commune. The ganglionic centres of the sensorium commune are formed of numerous nerve-cells, which, like those of the spinal cord, are in connection with afferent and efferent nerves ; the afferent nerves in this case coming mostly from the organs of the special senses. The im- pressions which the afferent nerves bring are, therefore, special in kind, as also are the grey nuclei to which they are brought ; a progressive differentiation of structure and function is manifest ; and we might describe the sen- * Grundzuge der Physiologischtn Psychotogit, p. 198. IV.] SECONDARY NERVOUS CENTRES. 189 sorium commune, physiologically, as a spinal cord, the afferent nerves of which are the nerves of the special senses, or rather of the various kinds of sensibility. For although we usually distinguish only between the special senses and general sensibility, yet there are really diffe- rent kinds of the latter, each perhaps having its special nucleus : the tactile sense, the sense of temperature, the muscular sense, differ not in degree only, but in kind. An exact knowledge of the anatomical relations of the different grey nuclei is still wanting, notwithstanding the patient investigations of many inquirers. All that we are certain of is, that the fibres of the nerves are connected with the cells, as may be most easily seen in the case of the auditory nerve and ganglion ; that mani- fold connections exist between different nuclei ; and that fibres may sometimes be traced from the nucleus of a sensory nerve to a motor nerve upon which it is known to exert a reflex action. The trigeminus, or fifth nerve, for example, passes from above downwards through the medulla, and in its downward course forms reflex con- nections with all the motor nerves of the medulla as it reaches the level of their nuclei ; in this way the facial, the glossopharyngeal, the vagus, the spinal accessory, and the hypoglossal nerves receive communications from it. The ganglionic cells of different nuclei also differ in form and size ; and Schroeder van der Kolk held that, as a general rule, at every spot where fibres are given off for the performance of any special function, there fresh groups of ganglionic cells giving origin to them appear. We justly conclude, then, that, as we should d priori expect, special ganglionic centres minister to special functions ; that the central cells are, as it were, the work- shops in which, on the occasion of a suitable stimulus, the peculiar current necessary for the performance of the specific action is excited. A message is sent up to them by the appointed channels, and they reply by sending igo THE PHYSIOLOGY OF MIND. [CHAP. through the regular motor channels the particular ener- gies which it is their function to supply. Charged with their proper force during the assimilating process of nutrition, it exists in them in a potential or latent form ; and the condition of unstable vital equilibrium is upset, the force being then discharged, as the Leyden jar is, when a certain stimulus meets with a sufficient tension. The natural course of a stimulus, all the force of which is not reflected upon an efferent nerve in the spinal centres, is upwards to the sensorium commune, where it becomes the occasion of a new order of phenomena ; the law of extension of reflex action excited by a spinal nerve observably being, as Pfliiger has shown, from below upwards to the medulla. Having arrived at the gan- glionic cells of the sensorium commune, the stimulus may be at once reflected through the motor nuclei on a motor nerve, for which there is provision in a direct physical path, and involuntary movements may thus take place in answer to a sensation, just as involuntary movements take place from the spinal centres without any sensation. The gan- glionic cells of the sensory centres are unquestionably centres of independent reaction, and, in association with their proper motor nuclei, give rise to a class of reflex movements of their own. When a man lies with the lower half of his body paralysed in consequence of injury or disease of his spinal cord, the tickling of the soles of his feet will sometimes produce reflex movements of which he is unconscious. When a man lies with no paralysis of his limbs, but with a perfectly sound spinal cord, the sudden application of a hot iron to his foot or leg will give rise to a movement quite as involuntary as that which takes place in the paralysed limb, but, in this case, in answer to a painful sensation ; the reaction takes place in the sensory ganglia, is accompanied by feeling, and the movement is sensori-motor. Had the hot iron been applied to the paralysed limbs, no move- IV.] SECONDARY NERVOUS CENTRES. 191 ment would have followed, because the path of the stimulus was cut off as completely as the current of the electric stimulus is interrupted when the telegraphic wires are cut across. Experiments on animals have yielded the most striking instances of complex acts, simultaneous and sequent, in answer to sensory stimuli. Take away that part of the brain of an animal which lies above the sensory ganglia, namely, the cerebral hemispheres, and it is still capable of a variety of sensori-motor movements, though it does not display the least evidence of intelligence, emotion, or will Flourens, whose experiments have been repeated by Longet, Schiff, and others, removed the cerebral hemispheres of a pigeon, and observed the results. It ceased at once to evince intelligence and power of spon- taneous action, and remained in a state of torpor, as if it were asleep. But if thrown into the air, it would fly ; if laid on its back, it struggled on to its legs ; the pupil of the eye contracted to light, and if the light was very bright, the eyelids were closed. It dressed its feathers when they were ruffled, and sometimes followed with a movement of its head the movement of a candle before its eyes; and, when a pistol was fired off, it opened its eyes, stretched its neck, raised its head, and then fell back into its former torpid attitude until another stimulus was applied. To each sensory stimulus it answered by making the proper movement in a mechani- cal way : the impressions of sense reached and affected the sensory centres, which in turn instigated the proper reflex or automatic acts. There was neither intellectual perception nor volitional action ; and it would have died of hunger with a plateful of food before it, though it would swallow food when this was pushed far enough into its mouth to come within the range of the reflex movements of deglutition. The animal was brought to the level of the invertebrata, which have no higher nerve 192 THE PHYSIOLOGY OF MIND. [CHAP. centres than sensory ganglia, no centres of intelligence and will, and which execute all their varied and active movements, seeking what is good for them, avoiding what is hurtful to them, and providing for the propagation of their kind, through sensory and associated motor nuclei. Similar experiments have been made on other animals with similar results. Vulpian made a complete transverse section of the nerve centres of the rat immediately above the medulla oblongata, and then pinched its foot severely : it uttered a short, sharp cry of pain which presumably was reflex or sensori-motor, just like the cry which an anencephalic infant may make. He then destroyed the medulla oblongata, and again pinched the foot : there were reflex movements, but there was no cry. In another experiment he removed the cerebral hemispheres, the corpora striata, and the optic thalami of a rat, when it remained perfectly quiet; but immediately a sound of spitting was made in imitation of that which a cat makes sometimes, it made a bound away, and repeated the jump each time that the noise was made.* The rat, by reason probably of having been hunted through many generations, is very fearful, scampering away on hearing the least unusual sound ; and, though its cerebral hemi- spheres were removed, it still responded to the sensory stimulus to the auditory ganglion by the proper automatic movements. Longet having removed the cerebral hemi- spheres of young cats and dogs, introduced into their mouths a concentrated bitter decoction; he observed that they performed active movements of mastication, and made grimaces with their lips as if they sought to get rid of a disagreeable taste ; they made, in fact, the same movements as he observed were made by an uninjured animal of the same kind when it was made to swallow a similar bitter decoction. * VULPIAN, 0/nV., p. 5^8. iv.] SECONDARY NERVOUS CENTRES. 193 Many more experiments of a like kind might be adduced, but it will suffice to mention the recent experiments of Goltz upon frogs. When a frog, the cerebral hemispheres of which have been removed, is placed on the palm of the hand held horizontally, it remains there crouched quietly ; if the hand be now gently turned, it will move first one paw and then the other, so as gradually to get upon the upper border of the hand as this rises, and to prevent itself from falling ; and if the turning be slowly continued, it finally gets carefully on to the back of the hand, when this is upper- most, and there sits quietly until the hand is gently turned backwards again, when it goes through the reverse operations. To the sensory stimuli from the muscular sense it responds by the adapted automatic movements, as exactly as if it still possessed its nerve centres of intelligence and will. In fact, the same agency is put in motion by the sensory stimulus to accomplish the proper movements as would have been made use of had the stimulus come from the will of the animal ; and while the sensory stimulus can excite the movements without the will, it would be quite impossible for the will to accomplish them without the automatic agency of the lower nerve centres. Another interesting experiment is the croaking ex- periment (Quakversuch). If the frog which has been deprived of its cerebral hemispheres be gently stroked between the shoulders or along the flanks, it will croak once at each stroke with machine-like regularity; dif- fering in this respect from an unmutilated frog, which either will not croak at all, or will croak several times, its cerebral hemispheres enabling it either to control or to strengthen the reflex act. But even frogs which do not croak so long as they possess their cerebral hemi- spheres will croak readily and regularly when these have been removed. However, none of them so mutilated will 194 THE PHYSIOLOGY OF MIND. [CHAP. croak their gratification in this way if the stimulus be painful instead of pleasant. If touched or stroked with a sharp instrument, or if electrical or chemical irritation be applied to the skin of the back, they execute defen- sive movements and may make a cry of pain, but will not make the croak of contentment The movements in answer to impressions on the senses are, like the simplest reflex movements, primary and secondary automatic. Examples of primary automatic movements are to be found in the contraction of the pupils and the involuntary closure of the eyelids when a strong light falls upon the eye ; in the distortion of the face in consequence of a sour taste ; in the quick with- drawal of the hand when it is touched by something hot ; in the cry which excessive pain calls forth ; in the motions of sucking which take place when the nipple is put between the infant's lips; in coughing and sneezing; and in yawning on seeing some one else yawn. Illus- trations of acquired or secondary movements of this class are seen in the adaptation of the walk to the music of a military band ; in the maintenance of the balance and attitude of the body, through combined impressions on sight and touch, during walking, running, leaping, dancing; in the articulation of words on seeing their appropriate signs, or hearing their sounds ; in playing from notes on a musical instrument when the mind is occupied ; and in many other of the common actions of life of which we are not conscious at the time, but of the necessity of which, were there no power of performing them automatically, we should soon become actively conscious * ('). We little * Mr, James Mill clearly recognised this class of movements, as Hartley had done before him. " Innumerable facts are capable of being adduced to prove that sensation is a cause of muscular action," p. 258. After instancing, as examples, sneezing, coughing, the con- traction of the pupils, and the movements of the eyelids, he says : " We seem authorised, therefore, by the fullest evidence, to assume iv.] SECONDARY NERVOUS CENTRES. 195 think, indeed, how much we owe to the acquired auto- matic functions of the nerve centres of the different senses. In the expression of thought by speech, it is not certain whether the idea acts directly upon the motor ganglia ; it may be that it acts first upon the auditory that sensation is the mental cause, whatever the physical links, of a great proportion of the muscular contractions of our frame ; and that among those so produced are found some of the most con- stant, the most remarkable, and the most important of that great class of corporeal phenomena." Analysis of the Human Mind, p. 265. Their nature was also distinctly pointed out by Unzer, who cited instances, e.g., many movements made during sleep, especially by somnambulists, "But f^f principal pcint is, that on this depends the secret of the instincts in those animals which probably do not feel the sensational stimuli of the instincts." Unzer's work was pub- lished in 1771. Op. cit. t p. 242. Hartley's Observations on Man were published in 1 749 ; and they are certainly surprising when we consider how little was known at that time of the anatomy and physiology of the nervous system. He supposed that when external objects affected the sensory nerves, they excited vibrations in the small particles of the medullary sub- stance, which were propagated to the brain ; " as soon as the vibrations enter the brain, they begin to be propagated freely every way over the medullary substance." .... "The subtle motions excited in the sensory nerves and medullary substance of the brain during sensation, and intelligence, must, of whatever kind they be, pass into the motory nerves, and when they are arrived there, it is probable that they cause the contraction of the muscles. " .''.' . . "The same motion that occasions sensation and intel- lectual perception passes through the seats of these into the motory nerves, in order to excite there the automatic and volun- tary motions." As examples of this reflex action he instances sneezing, swallowing, coughing, hiccoughing, vomiting, and ex- pelling the excretions, and "general convulsions from acidities, and other irritations in the bowels." He even extends this doctrine of reflex action to the secretory and excretory vessels of the glands, which " must be constantly agitated with a like motion from the same causes, performing their ordinary secretions and excretions thereby." Here then we have as clear an anticipation as could be desired of the doctrine of reflex action, and of its application to all nerve-centres. 196 THE PHYSIOLOGY OF MIND. [CHAP. ganglia and so excites the sensation of the sound of the proper word, or what would be the sensation were we actively conscious of it, and that this thereupon acts upon the motor ganglia and gives rise to the appropriate reflex movements of speech. It may be observed in regard to the automatic acts that, when completely organised, they are more perfectly performed the less we are conscious of them, that is, the more entirely reflex they are ; wherefore it is that somnambulists are able to walk and run safely where they would not dare to walk or run if they were wide awake. The instinctive actions of animals fall under the cate- gory of consensual acts : without the intervention of any conception, the sensation at once excites the ap- propriate movement, and the animal is almost or quite as skilful on its first trial as it is after a life experi- ence. It is true that the instinctive life is extremely limited in man, but sensori-motor action plays a large part in such manifestations of it as are witnessed ; in the taking of food the movements of mastication and deglutition, like the earlier ones of sucking, are in answer to sensational stimuli, as also are some of the co-ordinated movements necessary to the gratification of the sexual instinct. The adjustment of the human eye to distances, which takes place with such marvellous quickness and accuracy, is effected, according to the best authorities, by a change in the convexity of the lens and perhaps of the cornea, and by an alteration in the direction of the axes of the eyes. It is not a voluntary, not even a conscious act, but a consensual act in respondence to a visual sensation, and it is well suited to convey a notion of what an in- stinctive act in an animal is. It is plain enough that the intuitions of the distance and form of objects, which are acquired by man, are innate in many of the lower animals. The young swallow can apparently seize its small prey with as exact a skill on IV.] SECONDARY NERVOUS CENTRES. 197 the first occasion as the old one can after a life-experience ; and there is a certain Indian fish which brings down the insects on which it feeds by shooting a drop of water at them from its snout as they move above the surface of the water, and which is said seldom to miss its aim. When we consider that the refraction of the rays of light on entering the water will cause the insect to appear at a different spot in the air from that at which it really is, and that the difference between the real and apparent position will vary according as the rays of light enter the water more or less obliquely, we shall wonder the more at the remarkable intuition displayed. There can be no doubt, however, that the act is entirely automatic ; innate func- tions of the kind are limitations which compel and con- fine the animal to fixed routes of machine-like action ; and the absence of such limitation in man's original nature marks his higher freedom. Still it is interesting to observe how much even he is indebted to original endowment in this very matter of estimating distance. For what is the immediate cause that determines the muscular adjustment of the eye to distance ? The act is consensual, or, using the vaguer term, instinctive, in re- spondence to a visual sensation or picture an act of which there is no direct consciousness, and over which the will has no direct control Though the process is confused and uncertain at first, unlike in that regard the process in the lower animals, yet it is not long before the proper muscular adaptations are acquired and definite motor intuitions organised. Plainly, then, very much is due to the pre-arranged constitution of the nervous cen- tres even in man. We are under no little difficulty when we try to realise how far consciousness accompanies many so-called sen- sations and their respondent movements ; the question being whether consciousness is an essential element in the action, not of a sensation because the word implies 10 198 THE PHYSIOLOGY OF MIND. [CHAP. consciousness, but of a sensational stimulus upon the sensory ganglion, the passage of the resulting molecular motion to the associated motor nucleus, and its ultimate issue in the proper movement. But that, it may be objected, is nothing else than a question whether con- sciousness is a necessary part of sensation ; a question which can hardly be seriously asked. Not quite so, as will be evident if we do not suffer ourselves to be satis- fied with a somewhat vague term, but resolve to appre- hend the facts as distinctly as possible. When an impression on sense has affected the sensory ganglion, the resulting disturbance may be discharged in two ways : it may either travel upwards to the cerebral centres, where it is perceived, and is without doubt then a conscious state ; or it may pass along the sensori-motor arc into some movement, when it is not so certain that it is a conscious process. Certain it is that our natural bias is to attribute too much or too distinct consciousness to a sensori-motor act, because we are apt to deduce from our experience of self-consciousness. In our mental func- tions the action of the cerebral centres and of the sensory centres are so intimately intermingled that we are unable to separate them by self-conscious analysis, and so run the unavoidable risk of assigning to the latter, when they act independently, qualities which may be derived from the former. Could we get inside the nervous system of the insect which has no cerebral hemispheres, or of an infant as soon as it is born, before its cerebral hemi- spheres begin their functions, and observe directly what part, if any, consciousness plays in sensori-motor action, it would be a vast help in our analysis. Inasmuch as we cannot obtain that insight, the right method is, first, to observe carefully the simplest instances, making no further inferences than they warrant, before we go on to study the more complex phenomena of intermixed sensation and perception in man; and, secondly, to iv.] SECONDARY NERVOUS CENTRES. 199 make use of those in the interpretation of these, rather than to apply these to the interpretation of those.* Bearing in mind that the sensory ganglia are a continu- ation of the grey tract of the spinal cord, differentiated by their connections with the nerves of the special senses, I would call to mind what was said in the foregoing chapter concerning the supposed consciousness of the spinal cord. The conclusion reached was that it was capable of responding automatically to stimuli by co-or- dinate or adaptive movements, without possessing con- sciousness in any definite sense of the word. We may fairly suppose it possible then that the sensory ganglia, with their higher functional endowments, are capable of more complex automatic acts in answer to their special stimuli without the intervention of consciousness ; the more so as there is no line of demarcation between sen- sori-motor and reflex acts. Let us take a simple instance the contraction of the pupils to light : certain undula- tions strike upon the retina, are transmitted to the optic ganglia, reflected thence upon a motor nucleus, and the circular muscular fibres of the iris presently contract, whether we wish it or not, whether we know it or not ; if the light be brighter, contraction of the eyelids follows. We are not in truth conscious of the contraction of the pupils unless we watch it in a glass. The efferent part of the process is clearly unconscious, whatever be thought of the afferent part. But are we conscious of the * In adopting this canon one is liable to be met with the reproach from the metaphysician, that it is a setting to work to deduce the greater from the less and to subordinate the higher to the lower. But it is an empty reproach : we believe the greater to include the less, the higher to rest on the lower, and think that a knowledge of the less will help to a knowledge of the greater, of the lower to a knowledge of the higher, without supposing that the greater or higher does not contain something which will not be so explained. To apply this something to the less or lower is, we say, an entirely false method. JOG THE PHYSIOLOGY OF MIND. [CHAP. sensational stimulus in this instance ; in other words, have we a conscious sensation of light ? I think not, unless the sensation becomes perception, in which case it has passed beyond the sphere of sensory function to the higher sphere of the cerebral centres. The pupils of a person in apo- plexy who is unconscious of sight or sound will contract, just as those of the pigeon deprived of its hemispheres will, when a strong light is thrown upon them. The pure sensation is not strictly a conscious state ; we may rightly speak of an organic sentience and an ensuing movement that are not conscious. This is a conclusion which may certainly be disputed, and the more easily because of the want of anything like a precise definition of consciousness. It may be said that the before mentioned experiments on the frog show plainly that it feels, that is, consciously feels, the stimulus; for it utters the cry of pain when it is scratched, the croak of gratification when it is stroked gently. How should the frog respond to the gratification or the pain unless it felt it? But we go beyond the facts when we assume that it does respond to the gratifi- cation or the pain ; what we know is, that it responds to the stimulus, of which consciousness may be an incidental coeffect and by no means an essential accompaniment ; that the croak and the cry are made in answer to their respective stimuli. The surprise would be if they were not, the constitution of the frog being what it is, so long as the properties of its tissues are maintained by the due circulation of blood in them. Let us take the other ex- periment in which the frog cleverly balances itself on the hand, as this is slowly turned, so as to prevent itself from falling off Here it makes a series of complex move- ments in answer to a succession of stimuli from its mus- cular sense that are occasioned by its changing relations to the hand as this is turned. Is it conscious of these stimuli ? If we refer to our own experience of similar iv.J SECONDARY NERVOUS CENTRES. 201 stimuli operating in the maintenance of the attitude of the body and in the various adapted movements which we make for the accomplishment of special acts, it would appear that we are not conscious of them, so far as we know, and that those who affirm that we are so do really assume a consciousness which is not conscious. They, in fact, beg the entire question by the tacit assumption that we could not perform the adapted movements unless we were, without knowing it, conscious of the sensory stimuli of the muscular sense. So much concerning that which we learn from observation of simple instances. Let us now go on to consider a more complex instance. It is well known that the fly-catcher will, immediately it is out of the egg, catch an insect with its beak. In like manner a chicken, very soon after its escape from the egg, pecks at a grain and takes good aim ; that is to say, in answer to a visual sensation it adapts a set of move- ments with the most exact appreciation of the proper muscles to be put in action and of the degree of contrac- tion required in each muscle with the nicest accuracy of judgment to the accomplishment of a difficult feat. The lives of most chickens would be far too short to enable them to learn this skilful art, were they under the neces- sity of learning it Mr. Spalding has made some experi- ments on chickens which prove that they do not need to be taught As soon as they emerged from the egg he put hoods over their heads so that they could not see, and kept them in this state of darkness for two or three days until they could run about ; when he uncovered their eyes they appeared stunned or dazed for a minute or so, owing no doubt to the diffused molecular action through their nervous centres produced by the sudden impression of the undulations of light ; but immediately upon their recover)- from this state, when the molecular action was limited to the proper tracks, they followed 202 THE PHYSIOLOGY OF MIND. [CHAP. the movements of insects and pecked at them with precise aim. In like manner, they made their way straight towards a box in which a hen with chicks was shut up, when they heard her chuck, struggling through grass and over rough ground, though hardly able to stand steadily on their legs. Even chickens that were still hooded tried in this way to get to the hen when they heard her chuck. He observed also that a young turkey only ten days old, which had never seen a hawk, was so frightened by the note of a hawk which was concealed in a cupboard, that it fled away from the cupboard in the greatest terror. It will hardly be affirmed in these instances of so-called instinct that there is a distinct consciousness of the nature of the stimulus and of the ensuing actions ; the simple sensory impression in one case, of sight, in the other case, of sound is the spring which puts in motion auto- matically the proper muscles.* This it does by a physical necessity, not by the will, nor perhaps with the conscious- ness, of the chicken. In like manner, when ducklings are hatched by a hen, they make their way into water as soon as they see it ; the impression on the sense of sight determines their action, notwithstanding the consternation of the hen, and notwithstanding that they cannot have fore-knowledge of the qualities of water or prevision of what will happen to them when they get into it; and when they get into the water, the impression which it makes upon their bodies sets going the proper movements of swimming, just as happens when the frog * The metaphysical psychologists, who make most of conscious- ness, do not seemingly attribute consciousness to instinct in man. Most strange, from their point of view : but so it is ! " Man is indeed furnished with instincts, so far as he needs them, to impel and direct his movements, before his intellect is developed, or with respect to objects of which the intellect take no cognizance. Instinct is a blind, unconscious force ; it is not knowledge." The Human Intellect. By Noah Porter, D.D., LL.D., p. 176. v.] SECONDARY NERVOUS CENTRES. 203 that has been deprived of its hemispheres is put into water. On the other hand, chickens that have been hatched by a duck are not moved by her example to follow her into the water : she cannot educate them in the way she would have them go. It would be strange if ducklings and chickens did not thus act, in relation to water, in conformity with their nature ; their differences of constitution representing, in the one case, a mechanism which has been organised through past ages in that special adaptation to water which enables them to swim in it ; and, in the other case, a mechanism which has not been organised in relation to it at all. Could we penetrate the intimate construction, and disclose the secret springs of action, of the organic mechanism, we should without doubt perceive the result to be as clearly physical as are the successive motions of the piston and wheels of a steam-engine when the valve is opened which lets in the steam to act upon the piston. That the duckling swims and the chicken drowns in water is no more surprising than that wood floats and iron sinks in water. If we clearly realize this conception of an organic machine which has, through past ages of function, been now definitely organised to respond by physical necessity in special ways to special sensory stimuli, it will appear that consciousness, whether it exists or not, is not required for its operations is, if it occurs, an incident rather than of the essence of the function. Having once got this conception fixed in the mind, we shall be the better fitted to estimate the phe- nomena of sensori-motor or instinctive action, without bias from our self-conscious experience. It is easier to believe that the chicken is unconscious of the auto- matic movements which it makes when it pecks at the grain, than to admit that it is unconscious of the sen- sory stimulus when it sees the grain. But why should we endow the special susceptibility or reaction of the 204 THE PHYSIOLOGY OF MIND. sensory ganglion to the external stimulus with a quality of consciousness which it is not thought necessary to attribute to the special susceptibility or reaction which the associated motor nucleus shows to the stimulus from the sensory ganglion ? Here, in fact, we are involved in the confusion which comes of the want of an exact agree- ment as to what is meant by consciousness ; we suffer from the want of an exact definition in which men agree. When pressed hard by their opponents, those who uphold a diffusion of consciousness throughout the nervous sys- tem will say that although the chicken may not be con- scious of grain or of insect, yet it is impossible to believe that its sensory ganglion is not conscious of the stimulus which the grain or insect is to it But what is the mean- ing of this consciousness which is not the consciousness of the individual, but which is, nevertheless, attributed to the separate organs or parts of the body? Is it consciousness at all? Let the metaphysical psycholo- gists answer to that question, who define consciousness as the knowledge which the mind of the individual has of its own acts and states. It is surely the fact that / am conscious only as an individual, as an ego, by the power which I have of introspective observation of my- self : I cannot know anything subjectively of an alleged consciousness of separate organs or parts of my body which is not part of my consciousness as an ego, and assuredly I cannot know it objectively; it is therefore an assumption, which may be true or not, but for which we have no warrant, to ascribe consciousness to them. If it be said that although / am not conscious of a sen- sational stimulus my sensory ganglion is, and that its simple consciousness does, unconsciously to me, affect the com- plex consciousness which I, as an ego, have, its special waves being merged and lost in the more complex waves of general consciousness, I cannot deny the possible iv.] SECONDARY NERVOUS CENTRES. 205 influence ; but at the same time cannot but think that to call it consciousness is to take a license of assumption which is unwarrantable, and to render discussion futile ; it is to introduce a consciousness which defies subjective analysis and objective inquiry, and to rob the word of a definite meaning. Moreover, as I have already pointed out, it is an unnecessary assumption, once we have realised the purely automatic nature of the complex sensori-motor acts which excite our wonder. However, if it be still insisted that the sensory ganglion is always conscious, even when the indi- vidual to whom it belongs is not, it will be necessary to ascribe the quality, as some logically do, to the spinal cord also, and, in those creatures which, like the hydra, have no nervous system, to the sensitive ele- ments of their substance ; and I know not how, having got so far, we can forbear ascribing consciousness to the structure of the sensitive plant, to chemical elements which display affinities for one another, and to the aspir- ing ascent of water in a capillary tube. It will only be going back on the road to the old philosophy which found the explanation of natural phenomena in sympathies and antipathies, in loves and in hates. If anyone chooses to affirm that the sun, by an act of will attracts the earth and keeps it in its orbit, in spite of the voluntary resist- ance which the earth, anxious to get away into space, opposes to the compulsion, I cannot argue with him ; he silences me effectually, though he does not convince me. Certainly it behoves those who discover the diffused ele- ments of a rudimentary consciousness in the movements of the sensitive plant and of the hydra, if not in the affinities of chemical elements, which becomes more specialised as we ascend to more highly vital structures, to take scrupulous heed to discriminate plainly between these low modes of consciousness, the existence of which they infer objectively, and that consciousness which alone 206 THE PHYSIOLOGY OF MIND. [CHAP. we know directly ; and to refrain from tacitly investing the former with all the qualities of the latter. It must be borne in mind that the foregoing remarks have had reference to the primordial sensation of the chicken, while it was yet pure sensation, unmixed with perception. But in an animal with cerebral hemispheres this period of pure sensation must be brief and transitory. The moment the chicken has made the proper movements and picked up the grain, it has enlarged its experience of sensory stimuli by the coalescence with them of those which it has received from the muscular sense during the movements ; and it is in the association of these ex- periences of the muscular sense with the visual sensation of the grain, that the perception of the latter as an external object begins to dawn. These associated sensations, retinal and muscular, when they have been agglutinated, constitute the perception. The nearest thing in human experience with which we can compare the pure sensation, free from admixture of perception, is probably the so-called organic sense through which the brain is affected by the special stimuli of the several internal organs. Each organ is in intimate re- lation with the brain through internuncial nerve fibres, having, so to speak, a special correspondence with it ; and we have good reason to believe that each exerts its constant and specific influence upon it, and, through it, upon the constitution and function of mind. This intimate and essential sympathy is exhibited and observed most plainly in the great mental revolution which is produced by the development of the functions of the reproductive organs at puberty. Coming into action abruptly at a certain period of life, they display their specific effects in a decided and somewhat abrupt manner ; the effects being necessarily less evident with the specific sympathies of other organs which come into functional action directly after birth. iv.] SECONDARY NERVOUS CENTRES. 207 Now these organic stimuli, which affect us so essen- tially though we are not conscious of their operations, may provoke answering movements. I am not now referring to the contraction and dilatations of blood- vessels and the consequent disturbances of nutrition and secretion which they may undoubtedly occasion in other parts of the body, but to the movements of animal life. Flourens observed birds which had been deprived of their hemispheres to stand on one leg, and, after a time, owing probably to the sensory stimulus of fatigue, change to the other leg ; shake their heads, and put them under the wings for sleep ; ruffle their feathers, and sometimes plume them with their beaks. Neither intelligence nor will could have any part in the movements ; they were sensori-motor, and some of them probably in answer to stimuli arising within the body. Similar movements to relieve fatigue or an uneasy position take place in ourselves when we are asleep, or when our attention is so deeply absorbed in thought that we have not the least consciousness of them. Let any one who is accustomed to write while standing at a desk request some person to mark and record the various movements of his body which he makes while his atten- tion is so intently engaged in thought and composition that he is unconscious of what else he is doing, and he will be surprised how many he has really made. In animals the actions respondent to the organic stimuli constitute a great part of their daily activity ; and in man, when the influence of the highest nervous centres is weakened by disease, or when an organic stimulus has an abnormal energy, as happens sometimes in insanity, we may see the instinct for food or the sexual instinct mani- fested in a perverted and shameless manner. So far there is truth in a remark made by Jacobi, that the actions of the insane have an instinct-like character, as their physiognomies assume an animal-like look. In a zo8 THE PHYSIOLOGY OF MIND. [CHAP. complete description of sensori-motor function it will be necessary to take account of the organic stimuli from within the body as causes of various purposive move- ments. The difficulty which one has in bringing forward ex- amples of sensori-motor action in man springs from the impossibility, in many instances, of eliminating the action of the cerebral hemispheres. As soon as a reflex sensori- motor act is performed it awakens an echo or repeating movement of itself in the convolutions. In some instances, however, the function of the hemispheres is suspended. The somnambulist, who walks in dangerous places and goes through a series of performances when asleep, clearly receives information from some of his senses, by which he guides his movements. In those cases of epilepsy, quoted in the last chapter to illustrate reflex action, in which the person, during the transient unconscious- ness, goes on with the work which he was engaged upon when the fit seized him, and when he comes to himself is unaware of what has happened, it is evident that the acts are respondent to sensory stimuli. When a person is put under the influence of chloroform in order to have a surgical operation performed painlessly, it occasionally happens, if he is not completely narcotized, that as soon as the operation is begun he shrieks violently and strug- gles with all his might, displaying all the ordinary indica- tions of suffering so plainly that a bystander is convinced he is in great agony ; and yet when his consciousness is restored after the operation he is surprised when he is told that it has been done, declares positively that he felt no pain, and is unaware of his shrieks and struggles.* * Chloroform narcotizes the brain from above downwards first, thought being affected, then sensation, and lastly the purely reflex acts. In these cases, it may be supposed that the cerebral hemi- spheres are narcotized, but that the sensory ganglia are not fully under the influence of the chloroform. Dr. Lauder Brunton has iv.] SECONDARY NERVOUS CENTRES. 209 Two explanations offer themselves : either he really felt the pain at the time, as he seemed to do, and when he came to himself had clean forgotten it ; or the phenomena were entirely sensori-motor, the cries and struggles being as purely automatic as the cry and struggle which the frog deprived of its cerebral hemispheres makes when the skin of its back is sharply scratched. Schroeder van der Kolk mentions a case of a lady who had her breast ampu- tated while she was under the influence of chloroform, and who, though she felt no pain, was perfectly con- scious on awakening of having heard herself shriek. If she remembered the shriek, why should she not have remembered the pain had she really felt it 1 The same observer has also noticed violent shrieking in apoplexy, where there was not the least trace of consciousness manifested. Children learn to speak by reason of an in- voluntary impulse which they notably evince to reproduce a sound that is heard; and any one who has walked through a parrot-house, and heard the discordant screams which make the place hideous, must surely have some- times felt an involuntary inclination to shriek also. The clenching of the teeth and hands during severe pain is probably a sensori-motor action, like the shrieking which is another motor expression of it, both acts unquestion- ably relieving it in some measure ; indeed, were the spas- modic clenching to become a general convulsion, the pain would probably be no longer felt One might per- haps inhibit the pain of acute neuralgia by producing violent convulsions, and in like manner inhibit convul- sions by producing an agonizing neuralgia. ingeniously surmised that sudden deaths under chloroform, during surgical operations, are not always to be ascribed to an overdose of the chloroform, but to the shock of the operation, which shock pro- duced the fatal effect simply because the chloroform had not been given freely enough to narcotize the basal ganglia as well as the hemispheres of the brain. Biit. A fed. Journal, Dec. 4th, 1875. 210 THE PHYSIOLOGY OF MIND. [CHAP. The instinctive acts of animals, however, as I have already pointed out, furnish the most striking instances of sensori-motor action. Instinctive acts differ from reflex acts, such as the decapitated frog performs, in being more complicated ; they are equally automatic, but in them a combination and succession of movements take place in answer to a combination and succession of impressions. When we observe the wonderful operations which insects perform, it is hard to conceive that they are little more than automata, acting with almost mechanical constancy in answer to the stimuli which they are adapted to receive; but in reflecting upon their operations, it is incumbent upon us to take heed that we do not rashly measure the nature and range of their senses by the nature and range of our own. As Mr. Wallace has remarked,* their sight may far exceed ours both in delicacy and range, and may possibly give them knowledge of the intimate constitu- tion of bodies analogous to that which we obtain by the spectroscope. Insects certainly appreciate sounds of ex- treme delicacy. Besides the minute organs plentifully supplied with nerves which are presumed to be the organs of hearing, the orthoptera (such as grasshoppers, &c.) have what are supposed to be ears on their forelegs. In flies the third joint of the antennae contains thousands of nerve fibres which end in small open cells ; these have been supposed to be organs of smell ; or, it may be, although it is not so probable, that they are organs of some sense which man has not, and receive impressions * "That their visual organs do possess some powers which ours do not, is indicated by the extraordinary crystalline rods radiating from the optic ganglion to the facets of the compound eye, which rods vary in form and thickness in different parts of their length, and possess distinctive characters in each group of insects. This complex apparatus, so different from anything in the eyes of verte- brates, may subserve some function quite inconceivable by us, as well as that which we know as vision." On Natural Selection. A. R. Wallace, p. 202. IV.] SECONDARY NERVOUS CENTRES. 211 of which he has not the least perception. Certain it is that insects have an acuteness of sense by virtue of which they are in intimate relations with surroundings which we cannot perceive ; wherefore the automatic movements that are organically linked on to the im- pressions they receive appear to us marvellous and in- explicable. Not long since, a correspondent of a public journal related the following facts in a letter to it : He raised a female tiger-moth some years ago from the caterpillar state, and put it in a gauze-cage in a smok- ing-room opening into a town garden ; in less than two hours five male tiger-moths flew to the cage, although no flutter of wings or other sound was audible. He had sat in the same room with the window open and a light burning hundreds of nights without ever seeing a tiger-moth. It may fairly be presumed that the female moth made some peculiar noise inaudible to human ears, or emitted some emanation, imperceptible to human smell, by which the male moths were attracted. Were we to measure the delicacy of the dog's sense of smell by our own, we should gaze in wonder on what would seem the mysterious instinct by which it pursues its patient and sinuous course through field after field until it drives the hare from its hidden seat ; or were we to allow the vultures no keener sight or smell than we possess, it would be impossible to understand how it is that, when not a creature of the kind was previously visible in the heavens, they should be instantly gathered together from the remotest quarters of the horizon to the spot where the carcase is. It is well known with what speed and certainty the carrier pigeon finds its way to its far distant home ; and there are many stories telling how a cat or a dog which has been removed to a strange place far away from its home, under circumstances which reni dered it impossible that the animal could have made 212 THE PHYSIOLOGY OF MIND. [CHAP. observations by sight to guide it in returning, will never- theless find its way back. If one might venture a con- jectural explanation of so obscure a matter, it would be that it is guided back by a train of smells which it re- members as they are re-excited, just as a man who was finding his way home would be guided by remembering objects which he had seen. As we know that these animals have the same number and the same kind of senses which we have, we must suppose a much more acute susceptibility in one or more of their senses ; but even then we cannot easily conceive how they should act at so great a distance. It helps not to assume a co- operation of reason, for the reason of the greatest philo- sopher would not prevent him from losing his way hope- lessly under like circumstances.* There can be no doubt that human senses, especially those of touch and smell, are capable of a much more acute development than that which they commonly re- ceive. The loss of one sense is notably followed by an increase in the functions of those which remain, in conse- quence of the greater attention given to them. There is good evidence that blind persons may learn to distinguish colours by the touch. Dr. Abercrombie mentions two instances of blind men who were much esteemed as * " But let us suppose a nation of men, blind from their infancy, among whom a stranger arrives, the only man who can see in all the country ; let us suppose this stranger travelling with some of the natives, and that one while be foretells to them that in case they walk straight forward, in half an hour they shall meet men or cattle, or come to a house ; that, if they turn to the right and proceed, they shall in a few minutes be in danger of falling down a precipice ; that, shaping their course to the left, they will in such a time arrive at a river, a wood, or a mountain. What think you ? Must they not be infinitely surprised that one who had never been in this country before should know it so much better than themselves ? And would not those predictions seem to them as unaccountable and incredible as prophecy to a minute philosopher ?" Divine Visual Language: a Dialogue. l$ishop Berkeley. iv.] SECONDARY NERVOUS CENTRES. 213 judges of horses : one of them declared a horse to be blind though several persons had failed to observe the fact by recognising a peculiar and unusual caution in its manner of putting down its feet ; the other pronounced a horse to be blind of one eye, by feeling the blind eye to be colder than the other. He had known, too, several instances of persons aflfected with that extreme degree of deafness which occurs in the deaf and dumb, who had a peculiar susceptibility to particular kinds of sounds, de- pending apparently upon an impression communicated to their sense of touch. They could tell, for instance, the approach of a carriage in the street without seeing it, before it was taken notice of by persons who had the use of all their senses. They were, in fact, in the posi- tion of those lowly organised beings which have no special organs of hearing or of sight, but which are clearly in some degree sensible of vibrations of sound and undulations of light. ( 2 ) All the senses have proceeded by evolution from the simple and primordial sense of touch ; and when the higher senses fail, this sense is capable of re- suming to some extent, even in the highest animals, its primordial and general functions. Mr. Levy de- clares that whether in a house or in the open air, whether walking or standing still, he can, although quite blind, tell whether he is opposite an object, and can per- ceive whether it is tall or short, slender or bulky ; he can also detect whether it be a solitary object or a continuous fence, and whether it be a close fence or consist of open rails. Currents of air have nothing to do with this power ; nor has the sense of hearing. It seems to him that he perceives objects through the skin of his face, which he has ascertained by experiments to be the only part of his body possessing this power. Stopping his ears does not interfere with it, but covering his face with a thick veil destroys it altogether; and it is not diminished by 214 THE PHYSIOLOGY OF MIND. [CHAP. ordinary darkness, but it is by a fog.* This peculiar sus- ceptibility would appear to be a modification of tactile sensation, existing only in that part of the skin which is habitually exposed, and specially educated in conse- quence ; and it is of great interest, as marking an inter- mediate condition of development between touch and sight through which animals have probably passed, in the course of evolution, before the latter sense was distinctly differentiated and specialised. It helps us to conceive how, before a special organ of vision was formed, a portion of the covering of the body in the lowest organ- isms may have been differentiated so as to receive im- pressions which were neither impressions of touch, nor of sight exactly, but intermediate -between the two transi- tion stages in the development of touch into sight Bats at the present day display a susceptibility of the same kind ; for they will fly about a room without striking against the objects in it after their eyes have been put out.t The sense of smell may also be cultivated to a perfec- tion of which we little think until we set ourselves to observe or collect instances and to reflect upon the matter. Digby tells of a man who, like the negroes, could distinguish the approach of an enemy by the smell, and his wife from other women by the same sense. A certain religious person possessed almost divination in this respect, for he was said to be able to recognise persons by their different odours, and even to distinguish * Mr. Levy expresses his conviction that none of the five senses have anything to do with the existence of this power, which he con- siders to be an unrecognised sense, and calls by the name of " Facial Perception." Blindness and the Blind, by W. Hanks Levy. t The use of the same words to describe the qualities of the sensations of different senses points to this fundamental analogy f.f., softness of touch and softness of colour, a harsh sound and harsh colouring, a sweet taste and a sweet sound, &c. iv.l SECONDARY NERVOUS CENTRES. 215 chaste from unchaste women in the same way.* Haller remarks that negroes in the Antilles can distinguish by scent the footsteps of a negro from those of a French- man ; t and Humboldt affirms that the Peruvian Indians in the darkest night can not merely perceive by their sense of smell the approach of a stranger, but can say whether he is Indian, European, or Negro. % Dugald Stewart relates that James Mitchell, who was deaf, dumb, and blind, could tell by his sense of smell whether a stranger was present in the room or not, and indicate in what part of the room he might happen to be; it is probable that any dog would easily do the same thing. Idiots sometimes display a remarkable susceptibility of smell, accepting or rejecting, like animals, particular articles of food after sniffing them, or manifesting their lik.ing or dislike for particular persons after applying the same test. These instances prove that we might obtain a much more intimate knowledge than we do of the pro- perties of many natural objects by our senses of smell, taste, and touch, were we to cultivate them systemati- cally, and did we not depend so much as we habitually do upon the sense of sight ; and they serve well to indi- cate not only how much the senses of animals may sur- pass ours in range and delicacy, but how probable it is that many of their complex instinctive acts which strike us with wonder have their springs in sensational stimuli by which we are not affected. Could we unravel the intricacies of their sensori-motor functions, there can be little doubt that we should discover the explanation of their most complex instincts. Unfortunately the neces- sary data are wanting. * Traill Philosophique et Phyiiologique dc F Ilcrcditi NaturcUe. Par le Dr. Prosper Lucas, vol. i., p. 162. t White, On the Gradation of A/an, p. 148. * Humboldt's Cosmos. A case of the kind is related in Body and Mind, 2nd ed., p. 51. 2i6 THE PHYSIOLOGY OF MIND. [CHAP. I go on now to consider briefly the origin of instincts, moved thereto more particularly by an expectation of the light which the study of their mode of origin will throw upon the education of the nervous system of man. In the first place, there can be no dispute that instincts pass by hereditary transmission : the ant inherits the instincts of the ant, the bee those of the bee, the beaver those of the beaver, as distinctly as each inherits the anatomical and physiological characters of its progenitors. Indeed the fixedness of instincts is so great, and their transmis- sion so certain, that, as Mr. Darwin has pointed out, they persist long after the conditions of life to which they were adapted have been changed. Among other instances, he mentions that young pigs sometimes squat when fright- ened, and in this way try to conceal themselves even in an open and bare place ; that young turkeys, when the mother gives the danger cry, run away and try to hide themselves, like young partridges or pheasants, in order that their mother may take flight, of which she has lost the power ; that the dog, however well and regularly fed, often buries, like the fox, superfluous food, and turns round and round on a carpet before lying down, as if to trample down grass to form a bed ; and that lambs and kids discover the traces of their former alpine habits by the way in which they crowd and frisk on the smallest hillocks.* From these examples we learn first, that the tend- ency of instincts to pass by hereditary transmission is so strong that traces of them may be found centuries after a change in the external conditions to which they were adapted, and when they have long ceased to be of the least service to the animal; and, secondly, that the continued action, through generations, of changed ex- ternal conditions, such as domestication implies, does modify the organism of the animal, causing a decay of * On the Origin rfSfuus by means of Natural Selection. - iv.] SECONDARY NERVOUS CENTRES. 217 the old instincts which are not in use, and the develop- ment of new instincts suited to the changed conditions. The original instinct of the dog was to howl like a wolf; its acquired instinct, which it has possessed so long that it has become natural, is to bark. We are brought face to face then with two laws : the law of heredity, and the law of variation ; and it is in the operation of these two laws that we discover the mode of origin of new instincts and the probable mode of origin of all instincts from the beginning. Adopting the Darwinian law of evolution, we assume instincts to have been formed, as species have been formed, by the accumulation of slight differences which have been inherited. Unknown causes acting upon the brain have produced what have been called spontaneous variations of simpler instinctive actions ;* if these vari- ations were adapted to the external conditions, and gave the animal an advantage in the struggle for existence, they would survive by natural selection and be trans- mitted by heredity ; and thus in the course of time they would be fixed in its nature. The occurrence of a variation, the perpetuation of an advantageous variation by natural selection, and its hereditary trans- mission have been the main factors in the develop- ment of the greater number of the more complex * But why should they be called spontaneous, seeing that the term is so apt to occasion misunderstanding ? They are surely the effects of antecedent causes, though we know not what these causes may be. They may be conceived to arise in two ways : either by a variation in the external conditions provoking an organic adapta- tion ; or by a new impulse being generated from the combination of the organic antecedents, in like manner as a chemical compound displays properties that are not those of its constituents. It would be strange if while the simplest chemical combination develops entirely new properties, the infinitely more complex organic com- bination of two beings each of which again is a complex result of organic combinations did not develop new impulses or properties in the product. i8 THE PHYSIOLOGY OF MIND. [CHAP. instincts. If it be asked whence came the simpler instincts which have been assumed as a basis for the development of the more complex, we must seek for the basis of them in the complex reflex actions from which, as already pointed out, they have proceeded by successive complications in accordance with the same laws of natural selection and hereditary transmission of variations ; from the more complex reflex actions we may descend in like manner to the more simple, and from these to more simple still, until at last we reach the primordial reaction of the apparently homogeneous sub- stance of the lowest forms of animal life. So we trace a gradual progression from the most simple and general reaction, through successive complications of reflex action, to those most special and complex sensori-motor actions which are called instinctive. Another way though it is at bottom not another, but the same way in which we observe instincts to be formed in the higher animals is by the transformation of intel- lectual into instinctive acts. It is certain that intelligent actions which were acquired by experience or education in the first instance have, after being performed during many generations, been converted into instincts and inherited. G. Leroy made the observation long ago that in districts where war is made against foxes the young ones, before they have had any experience, display more caution and cunning than old foxes in districts where they are not persecuted ; and he accounted for the fact by attributing language to animals. While admitting that old foxes may use means to instruct their young, we may agree with F. Cuvier, who suggested the more probable explan- ation that the greater natural cunning displayed was owing, not to education, but to the hereditary transmission of acquired instincts. Birds in desert islands evince no fear of man when they first make acquaintance with him, but after they have had experience of the wanton iv.] SECONDARY NERVOUS CENTRES. 219 destruction which he works among them, the sight of his near presence instantly excites an instinct to escape. It may be taken for granted that birds in inhabited countries would show no more fear of him than they do of sheep, were it not for the embodied memories which they have of the enemy which he is to them ; Darwin has remarked that large birds are much more shy than small ones, because they have been more persecuted by man ; and I may add that among small birds robins approach him more boldly than others because it has long been incul- cated on children as almost a sin to kill a robin. Many other facts of the same kind might be quoted, some of which were carefully observed and recorded half a century ago by Knight He made trial with some pointer pups, having taken great care that when they were first taken into the field they received no instruction from the old dogs. The very first day one of the pups stood trembling with excitement, its eyes fixed, and all its muscles strained, pointing at the partridges, as its ances- tors had been taught to do. A young polecat terrier was thrown into a state of great excitement the first time he ever saw a polecat, while a spaniel remained calm and indifferent. The taming by man of the animals which are now domesticated without doubt cost him great pains originally ; and had there been no tendency to the fixation of acquired modifications by hereditary trans- mission, had the primitive instincts continued to display themselves with their original force in each succeeding generation, he would never have succeeded in domesti eating them.* " Will the unicorn be willing to serve thee, * The following quotation shows what a clear conception Cabanis had fonned of the modification of an organism by its environment, and of the fixation of the new organic habits or dispositions by hereditary transmission through successive generations: " Dea im- pressions particulieres, mais constantes et toujours les memes, sont done capable de modifier les dispositions organiques et de rendre leur modifications fixes dans les races. . . . Et si les causes deter- 220 THE PHYSIOLOGY OF MIND. [CHAP. or abide by thy crib ? Canst them bind the unicorn with his band in the furrow ? or will he harrow the furrows after thee ? " * These instances of instincts that have been acquired by the transformation of intellectual acts illustrate really the operation of the same laws which are manifested in the acquisition of complex instincts by the so-called spontaneous variation of simple instincts ; the only differ- ence being that the variation is produced, not by an unknown cause, but by human agency, and that its sur- vival is brought about, not by natural, but by human selection. They may be regarded in the light of experi- ments which test and support the theory of the natural origin of instincts. We observe in our own experience that intellectual acts, when frequently repeated, are done easily by habit, and finally become automatic ; habit may indeed be regarded in such case as instinct in the making. What we have to realize is that the nervous system of man and animal is moulded structurally according to the modes of its functional exercise, and that if these be defi- nite in character and frequently repeated, it becomes in time an automatic machine which performs its habitual functions with mechanical certainty on occasions of the suitable stimuli. The formation of a certain con- clusion in logic by an intelligent mind, when the minantes de 1'habitude premiere ne discontinuent pas d'agir pendant la duree de plusieurs generations successives, il se forme une nouvelle nature acquise, laquelle ne peut, a son tour, etre changee, qu'autant que ces memes causes cessent d'agir pendant longtemps, et surtout que des causes differentes viennent d'imprimer a I'economie animale une autre suite de determinations." Rapports du Physique tt du Moral de CHomme, J. G. Cabanis. " Qu'est-ce que nos principes naturels, sinon nos principes ac- coutumes?" says Pascal. "La coutume est une seconde nature qui detniit la premiere. Pourquoi la coutume n'est-elle pas naturelle ? J'ai bien peur que cette nature ne soit elle-meme qu'une premiere coutume, comme la coutume est une seconde nature." * Job xxxix. 9, 10. IV.] SECONDARY NERVOUS CENTRES. 221 premises are clearly apprehended, is as much an auto- matic necessity, or, if you will, an instinct, as the act of swimming by a duck when it is thrown into water. What is physical necessity, regarded objectively, is, as VVundt has remarked, logical necessity, regarded sub- jectively. Not to anticipate what will come afterwards, I for- bear to proceed farther with this matter now. Enough has been done by the foregoing short exposition of the nature and of the mode of formation of instincts to pre- pare the way for what I have to say touching those actions in man which may be described as acquired sensori-motor acts. To understand their nature, it is necessary to pass for a short time beyond the region of pure sensation into the higher region of perception, and to consider what relation the latter bears to the former. Sensation expresses merely the state of simple feeling without reference to an external cause ; it is wholly within, entirely subjective : perception includes not only the internal feeling, but the reference of it to an external cause ; it embraces the without as well as the within, is the synthesis of subject and object ; wherefore every distinct perception implies actually a judgment. In order to acquire a perception, it would seem that two senses at least must co-operate ; and in order to acquire the completest perception possible of an object, there must be a co-operation of all the senses which it is cap- able of affecting. Men are often one-sided or defective in judgment because they do not bring themselves into intimate relations with all the aspects of an object or event : they cannot understand it thoroughly unless they so stand under it that they perceive all its bearings. Let us take the simplest perception conceivable : that of something external to us, something which is not our- selves. The muscular feelings co-operate with the sense of touch to give us this information. The order of events 11 222 THE PHYSIOLOGY OF MIND. [CHAP. is presumably in this wise : the object excites the sensa- tion, which is at first entirely subjective ; the immediate outcome of the sensation is a simple movement, which thereupon brings into action the muscular sense, exciting certain muscular feelings; the effect of the muscular feelings is to produce further movements of the limb, whereby, pressing against the object or moving over its surface, or otherwise acting upon it, its position in rela- tion to the limb is changed ; the consequences of which are further modifications of the original sensation of touch in correspondence with further modifications of muscular feeling. In the association, fusion, agglutination, consilience, or synthesis, call it what we will, of these different impressions of the tactile and the muscular senses arises perception, which is necessarily at first of a very vague and obscure character. However, we have now got our perception, such as it is, of an ex- ternal object, which on any future occasion of touch is represented mentally in relation to these other simul- taneously or successively experienced sensations.* We * Our perceptions of space depend upon experience ; our visual sensations are not images, but signs, the meaning of which we have to learn by expeiience. This we do by comparing them with the result of our movements, with the changes which we make in the outer world. The infant as it learns to grasp, to turn its eyes and Lands to an object, to turn it over and over, so as to see it in all posi- tions, learns to recognise the different views of it in connection with the movements. Thus a conception of the object is obtained, and we are ever afterwards able to imagine what appearance it would present if looked at from some other point of view, and what move- ments we should have to make in order to put it in that point of view. "I have often," says Helmholtz, "noticed a striking in- stance of what I have been saying in looking at stereoscopic pictures. If, for example, we look at elaborate outlines of complicated crystalline forms, it is often at first difficult to see what they mean. \Vhen this is the case, I look out two points in the diagram which correspond, and make them overlap by a voluntary movement of the eyes. But as long as I have not made out what kind of form the TI.] SECONDARY NERVOUS CENTRES. 223 perceive then the importance for the perfection of perception, in other words, for the acquisition of know- ledge, of the capacity of a variety of movements of the organ. The more movements it is capable of and the more numerous the sensory nerves with which it is furnished, the more frequent are the occasions of sensations. We want to get every sensation which we can of it, by bringing the organ into every possible rela- tion with it, in order to perfect our perception. So much truth then was there in the saying of the old Greek philosopher that man is the wisest of animals by reason of his having hands ; the hands being capable of so great a variety of movements and being furnished with a highly developed tactile apparatus. In like manner, it might be said that the elephant is the most intelligent of quadrupeds by reason of its having a trunk ; for the trunk is an organ which has an extreme delicacy of touch, and a great and varied range of action. We infer then that the distinction between object and subject is not given in our earliest sensations. The sen- sation felt is all that the infant is at first conscious of; it tastes before it perceives a cause of taste ; there is no distinction of subject and object, of the ego and the non- drawings are intended to represent, I find that my eyes begin to diverge again, and the two points no longer coincide. Then I try to follow the different lines of the figure, and suddenly I see what the form represented is. From that moment my two eyes pass over the outlines of the apparently solid body with the utmost ease, and without ever separating. As soon as we have gained a correct notion of the shape of an object, we have the rule for the movements of the eyes which are necessary for seeing it. In carrying out these movements, and thus receiving the visual impressions we expect, we retranslate the notion we have formed into reality, and by finding this retranslation agrees with the original, we become convinced of the accuracy of our conception." Pop. Scunt. Led. p. 304. We may note by the way that the process is fundamentally the same as that by which we form and test our generalizations in observation and reasoning. 224 THE PHYSIOLOGY OF MIND. [CHAP. ego. It is an organic part of nature and is not conscious of being a self. But it makes movements which meet with resistance, and it is out of this feeling of resistance that the idea of an object grows ; when it has been ex- perienced a sufficient number of times, the spontaneous inference of an external world is organized in the mind. The notion is really an induction spontaneously made from experience, at so early a period of life that no one can have the least memory of the moment or of the manner of it. But the correlate of the idea of an external world is the idea of a self to which it is external. This idea grows out of the internal impressions and the feelings of pleasure and pain accompanying them : the muscular feelings, the sensa- tions of hunger and weariness, the double sensation which we experience on touching a part of our own bodies these contribute gradually to the definite individualiza- tion of the ego in relation to the non-ego. It is a long time before a child attains to a definite conscious idea of its ego and speaks of itself in the first person, although, like the animal, it manifests from the earliest period a, so to speak, instinctive feeling of self. Here, as elsewhere, obscure instinct precedes definite knowledge. The lower we descend in the animal scale the less distinct becomes the consciousness of a distinction between the self and the not self, until, as we have every reason to believe, it ceases to exist. No one supposes a tree to possess it ; and even those who think that the infusory animalcule has the simple primordial consciousness of sensation, will hardly go so far as to invest it with the higher con- sciousness of perception. In considering the mode of origin of the ideas of subject and object in the human mind, it is import- ant to remember, what some persons seem to forget, that we have an individual body to begin with; that there is a physiological union or consensus of organs before consciousness appears on the scene, the organism IV.] SECONDARY NERVOUS CENTRES. 225 being a whole in which there is not a part but acts upon the whole, as the whole again reacts upon and through every part ; that this union or commonwealth of organs, bound together by an intimate sympathy, is re- presented unconsciously in the brain as the central organ ; and that when it is awakened into consciousness by ex- ternal impressions, it becomes naturally the idea of self. The ego is the unity of the organism declaring itself in consciousness. When I touch a certain part of my body, I am conscious of a sensation of touching and of a sensation of being touched, both sensations in my self : the organism is the self, and consciousness only makes it known. Is it any wonder then that the idea of self should dawn as soon as conscious function begins, and grow into definiteness with its development. We should be ill furnished for life if we were entirely dependent upon our tactile and muscular feelings, pri- mordial and paramount as they are. In sight, hearing, smell, and taste we possess other important inlets of knowledge. When we perceive an object, such as an orange, we associate together all the sensations which it can produce in us its colour, taste, smell, figure, and consistence ; this combination of sensations constituting the object as perceived by us. Whether the object has an actual existence distinct from the sensation or per- ception of it, as most persons think, and, if so, how far it corresponds to the perception ; or whether, as Berkeley stoutly maintained, " all those bodies which compose the mighty frame of the world have not any subsistence without a mind" in which they are perceived ; I shall not pretend to discuss. Suffice it for present purposes that all the knowledge of them we have is through the effects which they produce upon our senses in fact, in percep- tion. The more carefully we have looked at the object, touched it, experimented on it by the different senses, in order to get the greatest number of possible sensations 226 THE PHYSIOLOGY OF MIND. [CHAP. which it is capable of exciting, and so to fulfil the condi- tions of sound induction, the more complete is the per- ception of it when present to sense, that is, when the proper nerve-currents are excited by its presence, and the more complete the idea or concept of it when it is absent from sense, but present to memory, that is, when the proper nerve-currents are excited by an in- ternal cause. A person born blind would know an orange by taste, or smell, or touch, but his perception would of course want the sensation of those qualities which sight alone imparts ; and if he were to acquire sud- denly the power of seeing, it is certain he would not at first recognise the orange by that sense alone ; before he could do so, it would be necessary for him to associate the new visual sensation with the experience of the other senses, especially of tactile and muscular sensation. This has been proved experimentally in several cases in which persons born blind have gained sight by means of a surgical operation on the eyes. In like manner, the perception of one who was born without smell or without taste would lack the information which the sensations of these senses respectively furnish; and if the absent sense were suddenly acquired, he would not recognise the object by it, until he had brought the new sensation into associa- tion with the previous experiences of his other senses : it would then take its place in the organized group or cluster of sensations which constitute the object. Cul- tivation of a sense whereby its susceptibility to impres- sions is sharpened, or the use of instruments which are adapted to increase its delicacy and range, will similarly add to the perception, when the information gained is brought into relation with the former sensations of which it is composed. But not otherwise. Were any one who had never seen a telescope or a microscope asked to look for the first time through a telescope at the moon, or through a microscope at a flea, he iv.] SECONDARY NERVOUS CENTRES. 227 would not in the least recognise the object he was looking at. The agglutination, blending, or organized grouping of separate sensations which constitutes the perception of an object, and which is fundamentally an induction or judgment, takes place, we believe, in the cortical centres ; these being the higher nerve-centres in which the sensa- tions of the lower sensory ganglia are co-ordinated into the idea of the object. This is what we mean when we speak of the process as a mental synthesis.* We now go * An acquired perception is truly an induction. The mind infers from the perceptive signs of one sense that there are properties of objects existing which, if trial were made, the other senses would discover. The difference between this induction and that which we call generalization is not in the process, but in the materials. The infant is engaged in making such inductions from the moment its mind dawns at first, on a very few objects, which constantly recur, its universe being very limited, and its whole soul being absorbed in them ; it constantly repeats the sensation and responsive move- ment, being gratified with trial and success, so that the perception is fashioned and fixed ; it does not reflect upon the means by which it arrives at the result, but makes its inductions, like the clodhopper, unconsciously. The perceptions which we thus derive from our senses cannot be analyzed and expressed in logical conclusions ; but they involve the same kind of mental process as the conclusions of logic. "There appears to me to be in reality only a superficial difference between the ' conclusions ' of logicians, and those inductive conclusions of which we recognise the result in the conception we gain of the outer world through our sensations. The difference chiefly depends upon the former conclusions being capable of expression in words, while the latter are not ; because, instead of words, they only deal with sensations and the memory of sensations. Indeed, it is just the impossibility of describing sensations, whether actual or remembered, in words, which makes it so difficult to discuss this department of psychology at all." HELMHOLTZ, Pop. Sec. Left. p. 308. " If I know that a particular way of looking, for which I have learnt how to employ exactly the right kind of innervation, is necessary in order to bring into direct vision a point two feet off and so many feet to the right, this also is a universal proposition which applies to every 32S THE PHYSIOLOGY OF MIND. [CHAP. on to remark that when we have once acquired in this way the definite perception of an object, it may on all future occasions be aroused by any one of the separate sensations of which it is constituted ; either the sight of an orange alone, or the touch of it alone, or the smell of it alone, or the taste of it alone, will excite the idea of the orange, the other possible sensations being, as it were, understood. We know right well that these other sensations will be forthcoming if we case in which I have fixed a given point at that distance before " (P- 31). " The sensations of our nerves of sense are mere symbols indicat- ing certain external objects, arfd it is usually only after considerable practice that we acquire the power of drawing correct conclusions from our sensations respecting the corresponding objects. Now it is a universal law of the perceptions obtained through the senses, that we pay only so much attention to the sensations actually ex- perienced as is sufficient for us to recognise external objects. In this respect we are one-sided and inconsiderate partisans of practical utility ; far more so indeed than we suspect. All sensations which have no direct reference to external objects we are accustomed, as a matter of course, entirely to ignore, and we do not become aware of them till we make a scientific investigation of the action of the senses." HELMHOLTZ. After pointing out the most striking analogy between names and objects, the connection of which must demonstrably be learnt, and sensations and the objects which produce them, Helmholtz says : " The elementary signs of language are only twenty-six letters, and yet what wonderfully varied meanings can we express and communi- cate by their combination ! Consider, in comparision with this, the enormous number of elementary signs with which the machinery of sight is provided. We may take the number of fibres in the optic nerves as 250,0001 Each of these is capable of innumerable different degrees of sensation of one, two, or three primary colours. It follows that it is possible to construct an immeasurably greater number of combinations here than with the few letters which build up our words. Nor must we forget the extremely rapid changes of which the images of sight are capable. No wonder, then, if our senses speak to us in language which can express far more delicate distinctions and richer varieties than can be conveyed by words (P- 3'4-) iv.] SECONDARY NERVOUS CENTRES. 229 make the experiment, but it is as unnecessary to do so on each occasion as it is to spell each letter in a word when we have once learnt to read with ease. The nerve-current of one sense is sufficient for our purpose. Just as we pay away a cheque and other per- sons take it as payment, because we know that it repre- sents its value in cash which will be forthcoming when it is presented, so we use the sensation as a sign of former perception, without testing its value by exciting the associated sensations. It is not only, however, in observation and thinking that we thus employ it as a sign. We employ it in the same way in acting, which is the outward issue or completion of observation and thinking : we observe in order to act, and judgment is the internal representation of the outward act in relation with the perception that which would, if outwardly ex- pressed, be the act. For this reason I have traced the relations of sensation and perception in this chapter; I could not else have placed our acquired sensorimotor acts in their true light. Little observation is needed to show that the greatest part of the habitual acts which we perform daily are strictly automatic, and that the stimuli which excite them are sensational. Let it be noted, moreover, that these sensations act in their capacity of representative signs : assuredly we do not perceive all the qualities of the objects in reference to which we act ; but one sensation, most commonly that of sight, serving as a sign of former perceptions, is sufficient to excite the appropriate move- ments. Here, indeed, we have the exact analogy of an instinctive act in an animal, the only difference being that in man has been acquired by education what in it has been inherited. When any one moves about in a house or room with the arrangements in which he is quite familiar, he is scarcely more conscious of the objects around him and of the greater part of his 230 THE PHYSIOLOGY OF MIND. [CHAP. movements than he is of his movements of breathing or of his particular steps in walking ; notwithstanding which, he does not run against the chairs nor stumble against the stairs, but fairly adapts his movements to the position and forms of the objects. But if some new piece of fur- niture be put in a part of the room where there was nothing before, or if some old piece of furniture have its figure changed, if an additional leaf, for instance, be placed in the table the chances are that he does stumble against it for a while, until, by familiarity or habit, the new sensation has taken its proper place in the organic groupings of former sensations and been associated with corresponding movements. The sensory stimuli of the objects to which we are thoroughly accustomed affect us unconsciously, or nearly so ; we see them, so to speak, without perceiv- ing them, if we are used to them, when we are in such a state of abstraction that we should not see them at all, and we should not be affected by the stimuli of them, if we were not used to them. Perhaps the most striking illustration of automatic action is furnished by the monotonous processes of dressing and undressing which we have the trouble to go through every morning and night of our lives. One operation follows another in mechanical sequence, while consciousness is absorbed in some train of thought, and it is only when something has occurred to interrupt the habitual sequence of acts, or when our attention has been aroused in some other way, that we become conscious in what an automatic fashion we are proceeding. The successive sensations do duty for perceptions, and arouse the movements which are or- ganically linked to them. So customary is it to wind up one's watch after taking it out of the waistcoat pocket on going to bed, that it must have happened to many persons to have on some occasions wound up their watch without intending it, indeed quite unconsciously, when changing iv.] SECONDARY NERVOUS CENTRES. 231 their waistcoats in order to dress for dinner ; and I have known a person to go so far as to put on his nightshirt instead of a clean shirt under the same circumstances. Again, it has sometimes happened that, when the mind has been deeply interested in a train of thought, a person has walked from one place to another through streets busy with the turmoil of traffic and the coming and going of men, and yet been unable, on reflecting afterwards, to say positively along which of two streets he came, though he has undoubtedly had what may be called sensory perception of the persons and objects which he has avoided in his walk. Many other instances of a like nature might be easily adduced, but I shall content myself with calling atten- tion to the firm association which is established by education between particular sounds, or particular visual sensations, and the adapted complex movements for the articulation of the appropriate words. Children plainly exhibit a tendency to imitate a particular sound, when there is certainly not yet any idea of what the sound means; and, as every one knows, it is easy enough to read aloud without paying the least atten- tion to the meaning of what is read, the consciousness being otherwise engaged. Dr. Radcliffe relates how he once knew a bright little English girl, about five and a half years of age, who could speak English, French, and German with equal readiness. If spoken to in English, she invariably answered in English ; if in French, she always answered in French ; and if in German, always in German. When addressed in one language, and urged to reply in one of the other languages which she under- stood, she could not do so, and if pressed beyond a certain point burst into tears : a good and obedient child, she could not be coaxed, bribed, or urged to reply in a different language from that in which she was addressed. Dr. Radcliffe's attention was called to the 232 THE PHYSIOLOGY OF MIND. [CHAP. fact by the governess, an intelligent person, who could not account for what appeared so singular an act of disobedience. The child died when she was about eleven years old from some affection of the brain, which was supposed to have been brought on by over-educa- tion.* There was no doubt that the child connected definite ideas with the words used in the questions put and the replies made ; but the fact that it could not put the same ideas into another language than that in which it was addressed, showed the dominion exercised by the sound over the articulating movements the mechanical connection established between them. Three special sounds were adapted to excite one idea, which was capable of expression in three special movements of speech, having in fact its three special tracks through the brain ; but the special sound in each case, acting in its character of sign or excito-motor stimulus of the idea, compelled the movement to which it had been organi- cally linked by education.! It is hardly necessary to point out that language, difficult as it is of acquisition, ultimately gets all the unconscious facility of a reflex act ; experience proving too well that many waste floods of vain words are poured forth without fatigue by some who, like officious Peter proposing to build three tabernacles, know not what they say. Assuredly consciousness is not an essential accompaniment of speech, which may be conscious, sub-conscious, or entirely unconscious. It is of the utmost importance to true conceptions of mental function that the full meaning and real bearing * Man Trans-Corporeal. Contemporary Revifiv, December 1874. t Narcisse Palletier, a Frenchman, who had lived so long among savages as to have forgotten his own language, soon recovered it, and forgot his savage language, when he was rescued. The old sounds, when once remembered, soon excited the old movements to which they were linked ; no doubt, if he had fallen again among savages, he would soon have recovered their language when he heard the sounds of their words. iv.] SECONDARY NERVOUS CENTRES. 233 of the foregoing facts should be distinctly realized. When the sensation excites an acquired sensori-motor act, we must suppose that it does so by virtue of the acquired nature of itself and of its sensory nerve-centre ; that, in fact, it is by virtue of this acquired nature that an object, which has been known by perception, is capable of acting merely as the sensory excito-motor stimulus of adapted movements. For we can hardly suppose in such case that the molecular current excited by the stimulus ascends from the sensory ganglion to the higher cerebral centres, and descends from them to act upon the motor ganglia, or that, having so ascended, it re-acts upon the sensory ganglion and then passes to the connected motor ganglia. One of these events, no doubt, is what happens when there is a distinct perception of the object, but it is a superfluous and improbable journey to make when the object is not really perceived, and when one quality of it, signifying, if we choose to attend or to per- ceive it, all its other qualities, excites a sensation which acts in its artiBcial character of a sign of the perception by virtue, that is, of the acquired nature of its nerve- centre. Moreover, notwithstanding the intimate struc- tural and functional relations between sensory and cere- bral centres, the supposition of an ascent of motion to the latter is opposed to what we have learnt concerning the instinctive acts of animals, and concerning the sensori-motor acts of animals which have been deprived of their hemispheres. These last experiments, if they have been rightly interpreted, seem indeed to be decisive against the argument of an ascent. It is necessary to be constantly on our guard to pre- vent physiological conceptions of mental phenomena from being overruled or vitiated by psychological terms. Sensation is not, as the psychological use of the word might seem to imply, a certain inborn faculty of constant quantity, but a general term embracing a multitude of Z34 THE PHYSIOLOGY OF MIND. [CHAP. particular phenomena that exhibit every degree of varia- tion both in quantity and quality. Simple as a sensation appears, it is in reality infinitely compound, being formed by a fusion of elements. A simple tone is one which is caused by a combination of simple wave-forms ; a ray of light is notably a very complex affair; and even our perception of colour is an induction. It has been supposed that all our sensations of colour are com- pounded of three elementary modes of sensation red, green, and violet ; Helmholtz adopting Young's hypo- thesis, that there are three classes of optic-fibres distri- buted pretty equally over the surface of the retina, which answer to the undulations of these colours, in other words, which minister to these three modes of sensation. The purest coloured light of the spectrum excites more than one class of fibres, so that our common sensations of colour are never pure elementary feelings ; the red rays, though they affect most powerfully the fibres sensitive to red, affecting in a less degree the other two classes of fibres. If these are incapacitated by allowing the eye to rest for a time on the comple- mentary colour and so exhausting them, and if the eye be then turned to the required colour, a much purer colour is obtained. Whether there are really three sets of fibres, or whether the three colours are produced by different excitations of the same fibres, matters not ; they are still complex. It has been discovered that ordinary sounds consist in like manner of complex aggregates of undulations of different pitches. We perceive, then, that sensations which seem elementary to consciousness are actually compound, and learn furthermore that no amount of skill in subjective analysis could ever have given us the least conception of their complex nature. If a sensation which seems to be elementary is thus complex, how much more complex must be the acquired sensation which is gradually matured in the proper IV.] SECONDARY NERVOUS CENTRES. 235 nervous centres from the residua or traces which previous sensations of a like kind have left behind them ; the sensation of a cultivated sense thus summing up, as it were, a thousand experiences, as one word often sums up the accumulated acquisitions of generations of men. Education can assuredly improve every sense we have in a remarkable manner. An experiment by Volkmann has shown that when the finger or any limited portion of skin on one side of the body is frequently experimented upon with the compasses, in order to test the degree of sensibility, its tactile sensibility is thereby increased above the level of that of the adjacent parts; and what is more remarkable is, that the sensibility of the symmetri- cal portion of skin on the opposite side of the body will be found to have been also rendered more acute. In- stances of improved sensibility of smell, taste, and hear- ing are too familiar to need mention. A patient and thorough study of the phenomena of vision is no doubt best suited to show how composite a product a mature sensation really is, for it will show that in the education of sight there is a gradual transformation of elementary sensations into what finally stand for simple intuitions of the mind : the cultivated visual sensation of an object really being a complex sensori-motor process which represents an implicit judgment of its distance, magnitude, and direction. The experience of those who, having been born blind, have afterwards gained sight, proves that an object seen for the first time seems actually to touch the globe of the eye, and is not recognised, if it be even distinguished as an object ; not the least information is given concerning its form, size, and situation ; the information which cultivated sight gives has been added unto it by education, and is a pro- duct of its acquired nature. As Berkeley aptly says, vision is a language speaking to the eye, which we are not conscious of having learned, because we have been 36 THE PHYSIOLOGY OF MIND. [CHAP. learning it ever since we were born, whenever our eyes are open in the light (3). The fact is, that we do not see, hear, or othenvise feel by sense the object itself, and have no guarantee that what we feel has any resemblance to the object ; what we feel is the effect that is produced in the nerve centre by the external stimulus, an effect which must needs contain the complex results of the experience embodied in the acquired or differentiated nature of the nerve-circuit ; and if the sensori-motor current were ex- cited in exactly the same way by an internal cause, no external object being present, we should have exactly the same feeling of it, just as dreamers and madmen have. Innate in the constitution of the different ganglionic centres is a specific power of reaction to certain im- pressions made upon organs that are specially adapted to receive them ; but as the waste following activity is restored by nutrition, and a structural modification is thus embodied in the constitution of the nervous centre, becoming more complete and definite with each succeed- ing impression, it comes to pass that an acquired nature is gradually grafted on the original nature of the nerve- centres, and that the sensation gains infinitely in com- plexity. The idea to be formed and fixed in the mind from a consideration of the phenomena of the development of sensation, and necessary to their proper interpretation, as indeed to the interpretation of every manifestation of life, is the idea of organization. The mind is not like a sheet of white paper which receives just what is written upon it, nor like a mirror which simply reflects more or less faithfully every object, but by it is connoted a plastic power ministering to a complex process of organization, in which what is suitable to development is assimilated, what is unsuitable is rejected. By the appropriation of the like in impressions made upon the senses we acquire iv.] SECONDARY NERVOUS CENTRES. 237 a sensation, of which we might speak, as we do when speaking of idea, as general or abstract ; there is a sort of organic classification ; and there exists henceforth, latent or potential, in the sensor)' centres, something that may be called a faculty, which on the occasion of the appro- priate impression renders the sensation clear and definite in other words, gives the interpretation. It is exactly like what happens in the spinal centres, and exactly like what happens, as we shall hereafter see, in the supreme cerebral centres. Coincident with the assimilation of the like in impressions, there is necesssarily a rejection of the unlike, which, being then appropriated by other nerve tracts, becomes the foundation, or lays the basis, of the faculty of another sensation, just as nutrient mate- rial which is not taken up by one kind of tissue element is assimilated by another kind. In the education of the senses, then, there takes place a differentiation of cells in other words, a discernment, as well as an improvement of the faculty of each kind of sensation by the blending of similar residua. There is an analysis separating the unlike, a synthesis blending the like ; and by the two pro- cesses of assimilation and discrimination our sensations are gradually formed and developed. The process illus- trates the increasing speciality of individual adaptation to external nature ; and the length of childhood in man is in relation to the formation of his complex sensations. Thus much concerning sensation and sensori-motor action. It is a hard matter for those who take the psy- chological view of mind to realize the firm organic con- nection that is established between the sensory stimulus and its proper movements the feeling and the act whereby these finally become as automatic as the motions of a clock's hands. When they observe an end to be accomplished they fail not to fly incontinently to the notion of design. The act, with whatsoever design it dis- plays, is the necessary result of a certain constitution, 238 THE PHYSIOLOGY OF MIND. [CHAP. innate or acquired, of the nervous centres, and is not dependent either upon volition or consciousness. Whe- ther consciousness exists or not as an accompaniment, is another question ; automatism does not necessarily exclude consciousness; and it is certainly conceivable that some animals are conscious automata, and that, though acting with mechanical necessity, they feel pleasure or suffer pain in doing what they do. Those persons go far beyond this supposition, however, who assume that the nervous centres of man or animal, when performing automatically a series of co-ordinate move- ments, possess a notion of the end which they effect, or display any degree of intelligence and volition. They probably possess no more of such notion than the ele- ments of a chemical compound have of the end which they accomplish when they combine, or than the wind has when it bloweth where it listeth ; * and accordingly they do not fail sometimes, under conditions of disease, to make terrible mistakes, and to cause much suffering to and perhaps miserably to kill the individual by con- tinuing violently reflex actions the cessation of which was necessary to the preservation of life. Even so philo- sophical a writer as Mu'ller inferred that the sensory centres were endowed with some degree of voluntary power, because of the remarkable actions to which they minister ; thus introducing into his observation, and applying to his interpretation, of the functions of the secondary nervous centres conceptions derived from his * " Whoever will examine the language of mankind, may find that we apply expressions to bodies which belong properly to our own manner of proceeding ; and, how well soever we know the contrary, speak of them as voluntary agents, exercising powers of their own ; thus it is said that the wind bloweth where it listeth, and we say of water that it will not mingle with oil, that it will force its way, &c, : terms expressive of a choice, compliance, and resolu- tion similar to those exercised by man." TUCKER'S Light of Nature, voL ii. p. 545. IV.] SECONDARY NERVOUS CENTRES. 239 knowledge of the functions of the higher or primary centres. This was surely to reverse the natural order of inquiry, and to apply the complex and obscure to the interpretation of the simple, instead of ascending by in- ductive steps to use the simple in order to disentangle the complex. The before-mentioned experiments upon the frog's spinal cord prove that movements seemingly purposive may be purely automatic : why then introduce a new agency, derived from experience of the highest cerebral centres, in order to account for sensori-motor functions which, though more complex than, are of the same character as, those of the spinal cord ? The answer which I conceive it probable may be made is this because the sensory centres are intermediate in structural position and physiological dignity between the spinal and the supreme cerebral centres, and may be expected, while exhibiting reflex functions like those of the spinal cord, to exhibit also the rudiments of func- tions which attain their special development in the cerebral convolutions. They are more special and com- plex in structure than the spinal centres, receiving and co-ordinating a greater variety of impressions, and it may be argued that they possess not only some degree of consciousness but the germs of intelligence and volition. At any rate, if it be not so in man, there is evidence that it may be so in some of the lower animals. It would appear that the ant and the bee, which have no higher nervous centres than sensory ganglia, and in which the functions of these centres reach a remarkable perfec- tion, are not simply organised machines that operate with unvarying regularity and are destitute of any power of shaping their acts to new experiences ; on the con- trary, observation shows that these creatures do some- times discover in their actions indications of a sensibility to strange experiences and of corresponding adaptations of movements. Take Huber's account of the humble- 40 THE PHYSIOLOGY OF MIND. [CHAP. bees which he put under a bell-glass along with a comb which was of such a shape as not to be capable of stand- ing steadily. Two or three of the bees got upon the comb, and, stretching themselves over its edge with their heads downwards, fixed their fore-feet on the table, so as to make themselves props and to prevent the comb from falling. When they were tired, others took their places, and the series of reliefs went on for nearly three days, until the bees had prepared sufficient wax to build pillars of support. Moreover, when the first pillars were dis- placed, they had recourse to the same operations in order to rebuild them. We could scarcely have a more striking instance of an apparent adaptation of means to an end according to varying circumstances. And I know not how those who would attribute such appropriate action to instinct can distinguish it from understanding, even if it be assumed that similar experiences must at some time have occurred to the race of bees. After all, it is only a manifestation of a power of adapting acts to circum- stances by which we must suppose, and Mr. Darwin has shown it to be probable, that bees have gradually ac- quired their wonderful instincts, and which at bottom is a property of nervous tissue, if not of organic substance.* The power is evidently of a rudimentary kind in bees, and must remain so in creatures that have not the higher nerve centres in which sensations are combined into ideas, perceptions of the relations of things thus ac- quired, and acts purposely shaped in consequence to * Mr. Wallace has broached and upheld the opinion that bees and ants do not act without instruction and blindly. He thinks that birds build their nests, as men build their houses, from obser- vation, memory, and imitation, using the material which each kind can most readily obtain, and building in situations most congenial s habits. Indeed, he asserts that " the peculiar notes of birds are acquired by imitation, as surely as a child learns English or French, not by instinct, but by hearing the language spoken by its parents." iv.] SECONDARY NERVOUS CENTRES, 241 accomplish ends whether the circumstances are changed or not But because bees have possessed, and still pos- sess, this rudimentary understanding, which differs in simplicity rather than in kind from human understand- ing, it does not follow that the sensory ganglia of man are endowed with similar rudimentary functions. On the contrary, it might be argued that as higher nervous centres are differentiated in the course of evolution, functions are localised in them which were more gene- rally diffused in the lower animals, not otherwise than as the fore limbs in man, which in the ape and some other animals serve both for grasping and walking, are special- ised in structure and function as prehensile organs. In the absence then of positive evidence of intelligence and voluntary power in the sensory ganglia of man, it is a scarcely warrantable assumption to endow them even with the rudiments of these functions.* But it is impossible to feel an equal assurance when the question is made one not of the existence of intel- ligence and will, but of the existence of consciousness in the sensory centres. Three considerations occur to the mind in reference to this question. The first is, that in the higher animals properties are localised in particular organs which in lower animals are diffused throughout the organism ; and while this may be used as an argument in favour of the supposition that conscious- ness is entirely limited to the cerebral hemispheres in man, it certainly does not exclude the possibility of its existence in the sensory centres. For it may well be * Unless, as I have already pointed out, we take all heart of meaning out of the word volition, by calling the adaptive power of organic element by the name. After referring to Spallanzani's observations on polypes, Prochaska says " From these and other facts it is manifest that these infusory animalcules feel, and have volition, and possess the character of the true animal ; consequently, they are endowed with a sentient and volitional principle, howevei destitute they may be of a nervous system." 242 THE PHYSIOLOGY OF MIND. [CHAP. that organs which are only a little lower in dignity than the supreme cerebral centres, which are essential to the development of their function, and which are in such intimate functional relation with them throughout life that a functional separation appears to be pure abstrac- tion, do possess that property which is most highly, but not exclusively, developed in the higher centres. Secondly, it admits of no doubt that consciousness is not a constant quantity, but that there are gradations of consciousness from its most vivid manifestations through stages of lessening subconsciousness down to actual un- consciousness. It may well be then that the sensory centres possess it in a less degree than the centres above them. The plain proof that they do possess it, some might argue, is that we feel pain when we are hurt ; and that the pain is felt in a sensory centre is further proved by experiments on animals which cry out when they are hurt, after their cerebral hemispheres have been re- moved. The argument, however, is by no means con- clusive. In the first place, we have no proof that the animals feel the pain ; all we know is that they cry out as if they felt it; and if we may trust our inferences from other experiments on animals and from observations of men under chloroform and in comatose states, we must admit that the cry may be purely a reflex act. In the second place, it is doubtful whether we ever are conscious of a sensation without perceiving, whether in fact we can have consciousness of a pure sensation: when we say we feel it, we feel it in a particular part of the body; and what is that but to perform internally a sensori-motor act and to recognise more or less clearly its where, in other words, to perceive it according to forms of space ? We infer the existence of simple sensations out of which ideas are formed by a mental synthesis, but it is a ques- tion whether a consciousness of them does not imply that our higher cerebral centres have come into play iv.] SECONDARY NERVOUS CENTRES. 243 and that we are exercising perception. To adopt the metaphysical theory which has been broached by some psychologists, that the organism in its relation to per- ception belongs neither to the ego nor to the non-ego, but occupies an intermediate position between them, is to dupe ourselves with vain words, which do not carry us a step farther towards an understanding of the facts ; whether we accept it or not, the problem remains just what it was. The third consideration is, that although the cere- bral centres, as representing the highest and most com- plex co-ordination of functions, are undoubtedly the seat of clear consciousness, of the individual's conscious- ness as an (go, the sensory centres may still be conscious after a fashion of their own, and may send their un- perceived contributions to make up the sum of that general consciousness which is the consciousness of the (go. This theory of an unconscious consciousness 1 have already discussed, and I need say no more about it now. The conclusion of the whole matter is, that while many plausible arguments may be brought forward on the one side and on the other, we have not the data to warrant us in deciding positively whether conscious- ness, or, if any, what sort of consciousness, is a property of the sensory ganglia, and that the question must for the present remain open. One reflection we may profitably educe from the dis- cussion, before passing from the subject namely, how artificial and unwarranted is the absolute division which is made between the conscious and the unconscious, between psychology and physiology. Notwithstanding that nature everywhere reveals the law of continuity, and notwithstanding that the progress of knowledge has been a history of the breaking down of arbitrary divisions in knowledge where none existed in nature, we still go on to make nature conform to our divisions, and as soon as 244 THE PHYSIOLOGY OF MIND. [CHAP. we are driven from one artificial barrier flee for refuge to another and insist on holding that at any cost All creation's endless changes proclaim the continuity and the becoming of things : man proclaims the divisions of science and the immutability of knowledge. How much idle discussion would have been saved in times past, and would be prevented in times to come, had the true lesson been taken to heart ! When it was found out that the earth was not fixed and immovable, men opposed the new doctrine as if all their faith and hope depended upon their holding fast to the old and false doctrine which they had so long cherished; when the geologists announced that the surface of the earth had been undergoing continuous changes through the ages, the mountains having been built up and the valleys scooped out by natural agencies, and the sea having become dry land and the dry land sea, the new doctrine was opposed with might and main ; and now that in this day and gene- ration it has been all but proved that the species of living things are not immutable creations, but have been formed by the gradual operation of natural causes through successions of ages, there is the same angry opposition made to the new doctrine, and the same passionate cling- ing to the old doctrine of fixedness is displayed. When a new and great truth is discovered, men too often act as if the earth were giving way beneath their trembling feet and heaven vanishing from their longing gaze, when it is merely the fabric of their ideas which is giving way, and when they ought to set earnestly to work to re- construct it. Has not the time come when we may justly ask ourselves whether there really is so great a gulf fixed as it has been the fashion to assume between brain and mind ? It may be worth while at any rate to adopt by way of experiment the theory that consciousness, though the usual, is not the indispensable accompaniment iv.] SECONDARY NERVOUS CENTRES. 245 of mental function a constant concomitant, if you will, but not an essential factor and that all the operations which are considered mental and to belong to psychology may be performed as pure functions of the nervous system, without consciousness giving evi- dence of them or having any part in them ; and then to observe how far the theory will throw light upon the phenomena of the menial life. Reasoning would go on as before in that case, only there would be no inner sense of it, What appears to the outer senses as physical law appears to the inner sense of consciousness as logical necessity ; they are two aspects of the same fact ; were consciousness suspended or abolished, the fact and the function would remain though the logical cogni- tion was lost ; the physiological mechanism would per- form its work whether its process and results appealed to the inner sense of consciousness or not, just as it would do whether it was watched or not by the outer senses of another person. To ascribe to consciousness an active part as cause in the cognition of a logical necessity is therefore no less absurd than it would be to ascribe to the outer senses of a scientific observer an active part in the causation of the physical law which they are making known to him. Whatever else may be thought, it can hardly be doubted that too much has been made of con- sciousness in times past, and that instead of mental phe- nomena revolving round it as the sun of the system, it is rather a sort of satellite of mind the indicator which makes known what is being done, not the agent in doing it. Let us suppose that one half of the brain may suffice to do all our mental work, as there is some reason to believe it may, and let us make the purely hypothetical supposition that the other half serves, by reason of its intimate communion and sympathy with it, to make us conscious of what is going on in the working half; 12 246 THE PHYSIOLOGY OF MIND. [CHAP. it is not difficult to conceive that something might occur to interrupt close intercommunion between the two halves, in which case it is plain that mental func- tions would go on without consciousness. That the division of the brain into two halves is the physiologi- cal condition of self-consciousness may be an unten- able hypothesis, but there is nothing unwarrantable in the assumption that there is a certain unknown action of the brain which is the condition of consciousness, and that this action may be suspended without entailing an entire or perhaps even a partial suspension of those cerebral functions which, when conscious, are called mental. However, let the truth concerning the cerebral hemispheres be what it may, it hardly admits of question that sensations and their respondent movements, which are accompanied by consciousness when first experienced, are gradually organised in the proper nerve-centres, thus become automatic, and then take place as effectually without consciousness as with it. The reaction of the motor ganglia that are in con- nection with sensory centres, whether designed or undesigned, co-ordinate or irregular, may be excited not only by impressions conveyed to them by the afferent nerves of the senses, and by the so-called organic stimuli, but also by a stimulus descending from the cerebral hemispheres. That cerebral activity which coming from above appears in consciousness as an idea or an impulse of the will, acts upon the secondary motor centres, and calls forth those movements which are commonly reflex to impressions from without. In such case it is tolerably certain that the idea or volitional impulse does not act directly on the motor nerve-fibres, but that it acts either upon the sensory nuclei and through them upon the connected motor nuclei, or, as is more probable, directly upon the ganglionic cells of the motor nuclei, in which the potentiality of the movement exists latent, iv.] SECONDARY NERVOUS CENTRES. 247 statical, or, as it were, abstract ; the stimulus from above disturbing the organic equilibrium, and releasing or setting free the movement together with whatsoever of design there is in it ; the same operations are performed, and through the same instrumentality, as when the im- pression conveyed by the afferent nerve from without excites the movement Thus the will is entirely de- pendent for its outward realisation in action upon that mechanism of automatic function which is gradually organised in the subordinate centres ; it cannot, as we shall hereafter see, at once instigate successfully a new movement, nor can it execute any movement without a guiding sensation of some kind : the cultivation of the senses, and the special adaptations of their motor re- actions which are gradually organised, are necessary antecedents, essential prerequisites, to the due formation and operation of will. The sensorium commune repre- sents, in fact, various independent nervous centres, and never does act merely as a conductor transmitting un- modified the stimulus, whether this ascend from without or descend from the cerebral hemispheres. Bear this clearly in mind, and the memory of it will help to get rid of some difficulties, when we come to deal with the will It is not needful to say anything here of the seeming disproportion between the amount of energy expended in the answering movement, and the moderate stimulus to the sensory ganglia by which the movement is excited ; inasmuch as what was said in this regard of the spinal centres is strictly applicable to the secondary nervous centres. A special inquiry would only serve here, as elsewhere, to set forth needless evidence in support of the principle of the conservation of force. And now let me briefly indicate the general causes of disorder of the functions of the sensory ganglia : they are in the main such as have been already pointed out to be causes of disturbance of the functions of the spinal cord : 248 THE PHYSIOLOGY OF MIND. [CHAP. i. As a natural fact, there may be an innate vice, feebleness, or instability of composition of the ganglionic cells. Such fault of nature is commonly owing to the existence of some nervous disease in the hereditary ante- cedents ; but it may of course be due to any other of the many recondite causes of degeneration of nerve element. Hallucinations of vision are by no means infrequent amongst some children at an early age, especially among such as suffer from chorea. And in those rare cases in which insanity occurs in children soon after they are born, it is chiefly exhibited in violent and irregular sen- sori-motor movements ; herein resembling essentially the insanity that sometimes ensues in animals. The un- natural laughter, the shrieking, the biting, and the tearing of the insane infant assuredly testify to a degenerate state of the motor and sensory cells in the sensorium commune : one might even venture to say that there was a true sensorial madness. It is most interesting to add that the disorder may alternate with, or be replaced by, general convulsions, the madness ceasing when the convulsions supervene ; in such case a transference of the disturb- ance from one system of nervous centres to another takes place. Again, there may be every degree of deficient sensi- bility down to actual insensibility of the ganglionic cells of the sensory ganglia. It is obvious that people differ naturally in the acuteness of their senses : there are un- dulations of light to which one person's retina is not sensitive, which nevertheless produce the sensation of light in another person; and there are vibrations of sound audible to one person which, either by reason of being too rapid or too slow, are inaudible to another. Moreover, singular idiosyncrasies in regard to the sus- ceptibility of a particular sense are displayed in some in- stances, one person being overpowered by the scent of a rose, another fainting away if a cat be concealed in the IV.] SECONDARY NERVOUS CENTRES. 249 room, and a third almost falling into convulsions if a piece of silk be sharply brushed with the finger. In idiots the senses commonly partake of the general stupidity, although a remarkably acute smell is now and then exhibited. The hearing is frequently defective; smell is often imperfect, the olfactory bulbs being insuffi- ciently developed ; taste absent or extremely vitiated, so that they will eat unconcerned the filthiest or the most pungent matters ; and the sensibility of the skin is some- times extensively absent, or it is generally dull, so that they suffer very little pain from injuries. The idiots of the lowest class have usually no other affection but that of hunger, which they exhibit by unrest, grunting, or the like ; but even some of these miserable creatures have at times attacks of fury, without evident reason, in which they scratch, strike and bite, as the insane infant does. Dulness of sensibility, when not nearly reaching the stage of idiotic degeneration, is of course unfavourable to intellectual acquisition ; but, on the other hand, a very acute and delicate sensibility is attended with evils and dangers of its own. In the former case, although there is a hindrance to assimilation, yet that which is appro- priated is commonly retained with great persistence ; in the latter case, there is certainly quick reaction, but no lasting appropriation, and, if the sensibility is intensified beyond a certain point, there may even be a lapse into that degenerate state in which, not the special sensation, but pain is felt, and irregular and convulsive reaction takes place. When the sensory centre is acutely affected, perception is incomplete or absent, just as when there is strong emotion there is little knowledge. To know an object there must be little feeling; the organic sensations, which are all feeling, yield no knowledge. It is of no small importance that these natural differences in the constitution of the ganglionic cells should be plainly recognised, for they unquestionably are at the root of 250 THE PHYSIOLOGY OF MIND. [CIIAP. certain differences in individual character and intellect. The direction of a man's pursuits in life may be deter- mined by the capacity of a particular sense, which naturally selects the class of impressions agreeable to it; and so determines the corresponding reactions, that is, the general course of the life-work. 2. An excessive use of the senses, without due inter- vals of rest, produces exhaustion, and, if continued, actual degeneration of them ; here, as elsewhere, the force ex- pended must be restored if the energy of the matter is to be maintained. A too powerful impression made upon any sense may also diminish, or actually destroy, its power of reaction ; immediate paralysis of sight, of hearing, or of smell has followed a sudden and powerful impression upon the particular sense ; and if the paralysis is not complete, the sensibility of the sense for weaker im- pressions may still be lowered for some time. After looking at a green colour for a while the sensibility of the retina to green rays is exhausted, so that when the eye is afterwards directed to white light the part of the retina susceptible to the green elements of white light is unaffected, and a sensation of the complementary colour, purple, is produced. Moreover, the sensation itself may persist for a while after the cause of it has disappeared, as when an image of the sun remains after we have ceased to look at it, or the roar of the cannon abides in the ears after the firing has ceased. The molecular vibrations excited in the nerve-centres continue for a few moments, and subside gradually. Such persistence of action in the ganglionic centre will serve to convey a notion of the con- dition of things which exists when a hallucination has been produced by internal causes. One of the best illustrations of the persistence of a sensation is afforded by the well-known experiment of rotating a circular disc with alternate black and white sectors. Above a certain rate of rotation there are no longer separate impressions iv.] SECONDARY NERVOUS CENTRES. 251 of black and white, but a continuous impression of grey is produced. The impression made upon the retina by a white sector continues during the short interval occupied by the passage of the black sector over the same point ; the result being the same as if the quantity of light from the white sectors were distributed uniformly over the whole surface of the disk. In this way the maximum duration of an impression has been measured. 3. The state of the blood has a most direct effect upon the functions of the sensory ganglia. Too much blood, as is well known, gives rise to subjective sensa- tions, such as flashes of light before the eyes and roaring ,-in the ears ; but it is not so generally known that when the abnormal action reaches a certain intensity, move- ments responsive to, or sympathetic with, the hallucina- tions may take place. N evertheless, they may : as the sensory ganglia have an independent action in health, so also may they act independently in disease ; and as in health there is co-ordinate or designed sensori-motor action, so in disease there may be convulsive sensori- motor action evincing more or less co-ordination or design. Of violent, but more or less co-ordinate, action we have, I think, an example in the raving and danger- ous fury which often follows a succession of severe epileptic fits, and which I take leave to describe as in the main a semorial insanity. The patient's senses are possessed with hallucinations, his ganglionic central cells being in a state of what may be called convulsive action ; before the eyes are blood-red flames of fire, amidst which whosoever happens to present himself appears as a devil, or otherwise horribly transformed ; the ears are filled with a terrible roaring noise, or resound with a voice imperatively commanding him to save himself; the smell is perhaps one of sulphurous stifling ; and the desperate and violent actions are the convulsive reactions to such fearful hallucinations. The individual in such state is a 252 THE PHYSIOLOGY OF MIND. [CHAP. sensori-motor machine set in destructive motion, and he perpetrates the extremes! violence or the most desperate murder without consciousness at the time, and without memory of it afterwards. A deficiency of healthy blood is a cause of disorder of the sensory centres. A great loss of blood powerfully affects the senses ; the anosmia of chlorotic and hysterical women is the probable cause of the many anomalous sensations and motor disturbances which disappear as the condition of the blood improves ; and a manifest poverty of blood often accompanies the chorea of chil- dren with its hallucinations. A perverted condition of the blood, whether from something bred in the body or introduced from without, is known to be a powerful cause of sensor}* disorder. Evidence of such injurious influence we have in the hallucinations which sometimes follow for a time certain acute diseases, as well as in the delirium which occurs in the course of them ; in the effects which alcohol pro- duces upon the senses ; in the actions of poisons, such as belladonna and aconite, which markedly affect the senses ; and especially in the operation of haschisch, a poison which appears to concentrate its action upon the sensorium commune. In hydrophobia the presence of a virus in the blood notably gives rise to most violent nervous disturbance ; the sight or sound of a fluid, a movement in the room, or a current of air, being suffi- cient to excite terrible convulsions. 4. An irritation operating by reflex action is un- doubtedly the occasional cause of sensorial disturbance. Pressure upon or wound of a sensitive nerve has some- times produced extensive paralysis of sensibility ; a bad tooth may notably give rise to amaurosis ; vertigo, hal- lucinations, and illusions are now and then plainly the result of an irritation proceeding from a centripetal nerve, not perhaps felt in any other way than as it is iv.] SECONDARY NERVOUS CENTRES. 253 testified by effects which disappear with the removal of the irritation. An interesting example of severe dis- turbance of the nervous centres from a slight eccentric irritation is related by Dr. Brown-Sequard, to whom it was communicated by Mr. C. De Morgan. A lad, aged fourteen, as he was getting up in the morning, was heard by his father to be making a great noise in his bedroom. On the latter rushing into the room, he found his son in his shirt, violently agitated, talking incoherently, and breaking to pieces the furniture. His father caught hold of him and put him back into bed, where at once the boy became composed, but did not seem at all conscious of what he had done. On getting out of bed he had felt something odd, he said, but he was quite well. A surgeon who was sent for found him reading quietly, with clean tongue and cheerful countenance, and wishful to get up. He had never had epilepsy, but had enjoyed good health hitherto. He was told to get up ; but on putting his feet on the floor and standing up his coun- tenance instantly changed, the jaw became violently convulsed, and he was about to rush forward, when he was seized and pushed back on to the bed. At once he became calm again, said he had felt odd, but was sur- prised when asked what was the matter with him. He had been fishing on the previous day, and, having got his line entangled, had waded into the river to disengage it, but was not aware that he had hurt his feet in any way, that he had even scratched them. " But on hold- ing up the right great toe with my finger and thumb, to examine the sole of the foot, the leg was drawn up, and the muscles of the jaw were suddenly convulsed, and on letting go the toe these effects instantly ceased." There was no redness, no swelling, but on the bulb of the toe a small elevation, as if a bit of gravel, less than the head of a pin, had been pressed beneath the cuticle. On compressing this against the nail cautiously, a slight 254 THE PHYSIOLOGY OF MIND, [CHAP. convulsion ensued ; there was no pricking when pressed, but he said something made him fed very odd. The slightly raised part was clipped away ; no gravel was found, but the strange sensation was gone, and never returned.* The general bodily feeling which results from the sum of the different organic processes is not attended with any definite consciousness or perception of the causes that give rise to it ; the organic stimuli are, in fact, organically felt, but do not in the natural state of health excite, as a stimulus to one of the special senses does, a particular state of consciousness ; and when the organic stimuli do force themselves into consciousness, as hap- pens in disease, then it is in pain that their action is felt. In respect of our organic feeling we are, in reality, on a level with those humble animals that have a general sen- sibility without any organs for special discrimination and comparison ; and if this were the only feeling which an individual had, he would probably not know that he was an ego. Having no idea of the particular cause of any modification in this general feeling, we are plainly most favourably placed for the generation of illusions with regard to the cause. Consequently it is not sur- prising to find that the insane frequently have extravagant * Lectures on the Physiology and Pathology of the Central A'ervotu System, by Dr. Brown-Sequard, 1860. A case singularly and sus- piciously like the one above related is quoted by Burrows (Com- mentaries on Insanity, p. 215) from Ilufcland. A boy between thirteen and fourteen years of age suddenly began to talk in a very wild and incoherent way, and at length became ungovernable. This state was assuaged by soporifics. But the paroxysm was observed to recur whenever he was placed on his feet. On examination, a reddish spot was noticed on one foot, which, when pressed, always occasioned a fresh paroxysm. Upon an incision being made, a rcinute piece of glass was discovered and extracted. During the operation the patient was furious, but every symptom of violence vanished when the offending cause was removed. iv.] SECONDARY NERVOUS CENTRES. 255 hallucinations and illusions respecting the cause of an abnormal sensation which is actually clue to a morbid state of some integral organ ; they think to interpret it as its unusual character seems to demand, and conform- ably with their experience of the definite perceptions of the special senses; accordingly they attribute the anomalous feeling to frogs, serpents, or other such crea tures that have got into their insides. 5. Whether any beneficial influence is exerted upon the nutrition of the nervous centres of the sensorium commune by ihc centres that lie above it, must remain uncertain, though it is probable enough. No trustworthy conclusions c?.a be drawn from experiments in which the cerebral hemispheres have been removed, for the mis- chief done is far too great to warrant any inference. It is certain that an area of morbid activity in the cerebral hemispheres may act injuriously upon the sensory centres and give rise to secondary derangement of their func- tions; but the result is then perhaps due to reflex or sympathetic action, the morbid centre acting as a morbid centre of irritation in another internal organ notably does. In concluding this account of the sensory nervous centres, I have only to add that a review of their relations and functions does certainly establish a close analogy with the relations and functions of the spinal centres. In both cases there are nervous centres which have the power of independent reaction, though they are usually subordinated to the control of higher centres ; in both cases the faculties are for the most part organised gradu- ally in relation to outward circumstances through the plastic power of the nervous centres ; and in both cases the independent power of action of the centres may, by reason of disease, be exhibited in explosive demonstra- tion. The paroxysm of hallucination which affects the cells of the sensorium commune excites, a corresponding convulsive energy of the motor centres, and drives the 256 THE PHYSIOLOGY OF MIND. [CHAP. furious epileptic to desperate violence, is as little within his control as is the convulsion of his limbs that is owing to disease of the spinal cord. NOTES. 1 (p. 194). It ought not to be forgotten that Dr. Darwin distin- guished voluntary from sensori-motor movements. " Many common actions of life are produced in a similar manner (i.e., by sensation). II a fly settles on my forehead, whilst I am intent on my present occu- pation, I dislodge it with my finger without exciting my attention or breaking the train of my ideas." Zoonomia, vol. i. p. 40. " Other muscular motions, that are frequently connected with our sensations, as those of the sphincter of the bladder and anus, and the musculi erectores penis, were originally excited into motion by irritation, for young children make water, and have other evacuations, without attention to these circumstances ' et primis etiam ab incunabulis tenduntur scepius puerorum penes, amore nondum expergefacto. So the nipples of young women are liable to become turgid by irri- tation, long before they are in a situation to be excited by the pleasure of giving milk to the lips of the child." Ibid. p. 38. "There is a criterion by which we may distinguish our voluntary acts or thoughts from those that are excited by our sensations. The former are always employed about the means to acquire pleasurable objects, or to avoid painful ones ; while the latter are employed about the possession of those that are already in our power." And he goes on to say that the ideas and actions of brutes, like those of children are almost perpetually produced by their present pleasure or their present pains ; they seldom busy themselves about the means of pro- curing future bliss or avoiding future misery. Ibfd., vol. i. p. 184. One of the best examples of acquired sensori-motor action is furnished by the story of the old soldier who was carrying home his Sunday dinner, when some one behind him called out suddenly in a tone of command, "Attention." Instantly he dropped his dinner and stood in the attitude of attention. Dr. Jackson tells another equally illustrative story : he was riding on an omnibus one day when, after the vehicle had stopped, one of the horses turned stupid and would not start again, notwithstanding all that the driver could do. The conductor thereupon opened the door of the omnibus and shut it with a bang, when the animal started at once. a (p. 2IJ). In the Forty-third Report of Ihe Massachusetts Asylum for the Blind, Dr. Howe relates the following instances of IV.] SECONDARY NERVOUS CENTRES. 257 the greater keenness to which the remaining ?ense* may be brought when one sense U absent : "Julia Brace, a deaf and blind mute, a pupil of the American Asylum, had a fine physical organization and highly nervous temperament. In her blindness and stillness her main occupation was the exercise of her remaining senses of smell, touch, and taste, so that through them she might get knowledge of all that was going on around her. Smell, however, seems to be the sense on which she most relies. She smells at everything which she can bring within range of the sense ; and she has come to perceive odours utterly insensible to other persons. When she meets a person whom she has met before she instantly recognizes him by the smell of his hand, or of his glove. If it be a stranger she smells his hand, and the impres- sion is so strong that she can recognize him long after by smelling his hand, or even his glove, if just taken off. She knows all her acquaintances by the smell of their hands. Surprising things are told of the nicety of her sense. She was employed in sorting the clothes of the pupils, after they came out of wash, and could distinguish those of each friend. If half a dozen strangers should throw, each one his glove into a hat, and they were shaken up, Julia will take one glove, smell it, then smell the hand of each person, and unerr- ingly assign each glove to its owner. It is even said that if, among the visitors, there is a brother and sister, Julia can pick out their gloves by a certain similarity of smell, but cannot distinguish the one from the other." Does not this case furnish a strong argument in support of the conjecture that a dog removed to a distant place finds its way home by following backwards a train of smells which it has experienced ? He gives another instance illustrating the remarkable acu'eness of the sense of hearing in a blind boy : "Many years ago, an ingenious locksmith applied to me for the Moan ' of a blind boy, as he said, who had quick ears and a silent mouth. On giving satisfactory answers, he got his 'loan.' He wanted a boy to help him to open a new and complicated lock to a safe. An inventor had exhibited a locked safe and the key, saying that there was money within, which should be given to whoever could open the lock without deranging it. The peculiarity of the lock was that it had ten bolts which could not be seen from the outside. These ten bolts seemed, from all that could be ascertained, exactly alike ; but, in reality, one ( f them was an inch longer than the others, so that when all were thrown forward, that one alone reached the projecting part of the safe, and held the door closed. The key, when inserted, would lift any of the ten bolts ; but, in 258 THE PHYSIOLOGY OF MIND. [CHAP. iv. order to open the safe, it must be applied to the long bolt, and to that only, and that one must be lifted and turned back, in order to open the lock. But, if any other of the ten were lifted and turned lack, ever so liitle, it deranged the combination, and the lock could only be opened by a peculiar instrument. The object, then, was to ascertain which of the ten was thrown forward, without turning back any other one. "The mechanic lifted each bolt carefully with the key, and let it fall, but without trying to throw it back ; and be then tried to ascertain if in falling it made any peculiar noise ; for he inferred that, as the only one which held the door was an inch longer than the others, it must fall with a slightly greater force. But the difference was too slight for his ear. He took the blind lad, and asked him to listen carefully to the sound which each bolt made as he lifted it and let it fall After listening to each one intently, the lad said the sixth one struck a little the loudest The mechanic lifted and let fall each one carefully several times, and each time the boy insisted that the sixth bolt sounded the loudest. Upon this, the mechanic lifted and turned back the sixth, and the lock was opened without the combination being deranged." 3 (p. 236). " ALCIPHRON :-^-If vision be only a language speak- ing to the eyes, it may be asked, when did men learn this language ? To acquire the knowledge of so many signs as go to the making up a language, is a work of some difficulty. But will any man say he hath spent time, or been at pains, to learn this language of vision ? "EUPHRANOR : No wonder we cannot assign a time beyond our remotest memory. If we have been all practising this language, ever since our first entrance into the world : if the author of nature constantly speaks to the eyes of all mankind, even in their earliest infancy, whenever their eyes are open in the light, whether alone or in company : it doth not seem to me at all strange that men shonld not be aware they had ever learned a language, begun so early, and practised so constantly, as this of vision. And if we also consider that it is the same throughout the whole world, and, not like other languages, differing in different places, it will not seem unaccount- able that men should mistake the connexion between the proper objects of sight and the things signified by them to be founded in necessary relation, or likeness, or that they should even take them for the same things. Hence it seems easy to conceive, why men who do not think should confound in this language of vision the signs with the things signified, otherwise than they are wont to do in the various particular languages formed by the several nations of men." BISHOP BERKELEY'S Minute Philosopher, vol. i. p. 231. Ed, 1732. CHAPTER V. HEMISPHERICAL GANGLIA; CORTICAL CELLS OP THE CEREBRAL HEMISPHERES; IDEATIONAL NERVOUS CENTRES;* PRIMARY OR SUPREME NERVOUS CENTRES; INTELLECTORIUM COM- MUNE. BY the study of physiology it has been placed beyond doubt that the nerve-cells which exist in countless numbers about 600 millions in number, according to Meynert's calculations in the grey matter spread over the surface of the hemispheres are the nervous centres of ideas. The cerebral hemispheres represent, in reality, two large ganglia that lie above the sensory and motor centres, and are connected with them by a multitude of nerve-fibres, de- scribed by Reil as the fibres of the internal sense ; they are superadded in man and the higher animals for the further fashioning of sensory impressions into ideas or conceptions. This important step in the evolution of the human mind consists in an abstraction of the essential irom the particular and its re-embodiment in idea ; it is in fact an idealisation of the sensory impressions, and may be * " We have not a name for that complex notion which embraces ns one whole all the different phenomena to which the term Idea relates. As we say Sensation, we might say also Ideation ; it would be a very useful word ; and there is no objection to it, except the pedantic habit of decrying a new term." JAMES MILL, Analysis of the Human Mind, p. 42. 260 THE PHYSIOLOGY OF MIND. [CHAP. regarded as an epigenetic development of nature : what the true artist does in his art nature does continually in the development of the human mind. Looking not at the individual man and his work as the end, but looking at him as a small and subordinate part of the vast and har- monious whole, as a means to a far-off end, it is suffi- ciently evident that the history of mankind is the history of the latest and highest organic development ; that in the evolution of the human mind nature is undergoing its consummate development through man. And the law manifest in this highest display of organic development is still that law of progressive specialisation and in- creasing complexity which has been traceable through the long chain of organic beings. So exquisitely deli- cate, however, are the organic processes of mental de- velopment which take place in the nerve-centres of the cortical layers, that they are certainly, so far as our pre- sent means of investigation reach, quite impenetrable to the senses ; the mysteries of their secret operations can- not be unravelled ; they are like nebulae which no tele- scope can yet resolve. Nor will it be thought reasonable to ask such knowledge, when we reflect that we have not yet the means of knowing the properties and structure of the molecule of any liquid or solid what are its internal motions and what are the parts and shape of it; and that it would require a microscope capable of magnifying from 12,000 to 16,000 times to show the molecular structure of water.* The cerebral hemispheres are not alone the nerve cen- tres of ideas, but they are also the centres of emotion and volition. In animals that are deprived of their hemi- spheres, all trace of spontaneity or will disappears from their movements ; this effect being, as might be expected, * According to Sir W. Thomson's calculations, the distance between two molecules of water is such that there are between five hundred millions and five thousand millions of them in an inch. v.] HEMISPHERICAL GANGLIA. 261 much more evident in experiments on the higher than on the lower Vertebrata. In Fishes, as for example in the carp, scarcely any difference is observed in its swimming after its hemispheres have been removed ; but if its move- ments be watched more carefully, and compared with those of a carp which has not been mutilated, a certain change will be recognised. According to Vulpian, it moves forward in a straight line, never turning to one side or the other except when it meets with an obstacle, and not stopping until it is completely fatigued ; it seems impelled to move by some necessity, a necessity occa- sioned probably by the stimulus of the water on its body. The more marked effects produced in the higher Verte- brata by the removal of the hemispheres have already been described. It has long been surmised that different convolutions of the brain discharge different functions in the mental life, and the phrenologists, by inferring organ from func- tion, went so far as to precisely map out the cerebral surface into definite regions and to assign its particular mental faculty to each region. The localisation which they made has not been borne out by anatomical re- search, nor do the faculties which they assume receive adequate support from psychological analysis. That the high, broad, and prominent forehead marked intellectual power, was a belief which the ancient Greeks entertained, and which has long been popularly held ; and the notion that lowness and narrowness of the forehead indicate intellectual inferiority is in harmony with the observa- tions that in the negro, and more markedly in the Bosjes- man, the anterior part of the hemispheres is narrower than in Europeans, and that the narrowing of the frontal lobes to a point is one character by which the brain of the monkey differs from that of man. It has been con- jectured also that the upper part of the brain and the posterior lobes have more to do with feeling than with the 262 777.fi: PHYSIOLOGY OF MIND, [CHAP. understanding; Huschke found them to have a propor- tionately greater development in women than in men ; and Schroeder van der Kolk's pathological researches afforded him what he considered convincing proofs that the anterior lobes of the brain were the seat of the higher intellectual faculties, and that the upper and posterior lobes ministered rather to the emotional life. Comte elaborated a phrenological scheme which was a modification of that put forth by Gall, holding confidently that from the study of cerebral functions it was possible to determine the number of cerebral organs and their rela- tive position. But the details of his scheme will hardly strengthen the authority of his method. Regarding the brain as forming an anatomical connection between the two external mechanisms of sensory and of motor nerves, as it manifestly does, he surmised that the arrangement of the two parts of the central apparatus would be ad- justed to these two extreme terms in the system, and was led to place the intellectual organs in front, as being more connected with the various mechanisms of sensa- tions. The rest of the brain was appropriated by him to affective functions, which were placed backwards because of their connection with the principal mechanisms of motion ; the centres of intellectual operations, which do not of themselves lead to motion, being more remote from its mechanism. The cerebral functions were sup- posed to be higher in quality and inferior in force as we proceed from behind forwards ; and in conformity with this view the anterior part of the affective region was appropriated to the social or altruistic feelings, which were thus in proximity to the intellectual organs, the hinder part being reserved for the less noble personal or egoistic propensities. In consequence of pathological observations it was insisted by Dr. Todd, contrary to general opinion at that time, that the seat of the convulsive phenomena of V.] HEMISPHERICAL GANGLIA. 263 epilepsy was in the cerebral lobes, but this theory found no favour, because of the general belief that the grey matter was insensible to stimulation and had nothing to do with movements. Nevertheless the observations of Dr. Wilks led him subsequently to a decided conviction of the correctness of Dr. Todd's opinion; he had no hesitation in saying that for one case of disease in the pons varolii with epilepsy, fifty cases might be found in which the morbid changes were on the surface of the brain ; and he could not see any grounds for the theory that the seat of epilepsy was in the pons or in the central ganglia of the brain. He felt sure that the/o/ts rf origo malt was in the cortical layers of the brain, and that improved methods of examination would disclose morbid changes there in cases of long-standing epilepsy.* Before this, Broca had propounded a theory that the seat of articulate language was in the posterior part of the third convolution of the left side of the brain, founding it upon certain patholo- gical observations in which loss of speech was accom- panied by destruction thereof; and the theory, though it seemed startling and improbable to many persons, had received competent support. Dr. Hughlings Jackson next made a conjectural step farther in our knowledge of epilepsy ; noticing that the convulsive phenomena often commenced in certain muscles, different in different cases, and then spread to the whole body, he inferred that the commencement of the morbid irritation which led to the epileptic discharge was in the special convolu- tions presiding over the group of muscles first affected, and that it afterwards spread to the other convolutions. He ventured even in some instances^o fix upon the special convolution which was presumably at fault Such, until quite recently, was all that was known or conjectured concerning the functions of the different * " Observations on the Pathology of Diseases of the Nervous System." Guy's Hospital Reports. 264 THE PHYSIOLOGY OF MIND. [CHAP. cerebral convolutions. There was great difficulty in the way of acquiring more exact knowledge by means of physiological experiments on animals and pathological observations of man, the difficulty being much increased by the fact that the hemispheres have a compensating action ; for it has been observed that a pigeon which has had one hemisphere or considerable portions of both hemispheres removed does not, after a few days or weeks, present any notable differences from an unin- jured bird. In man, too, not only may there be consid- erable destruction of a portion of one hemisphere by disease without any disturbance of intelligence, the dis- turbance, if any, being more often motor than mental, but there may be a total destruction of one hemisphere without any appreciable impairment of mental function. The probable explanation of these facts is that different parts of the cortical area replace one another in function in a singularly complete manner, so that a disturbance of function produced at first by sudden injury or disease gradually disappears more or less completely. This vicarious action will appear the less surprising when we call to mind the infinite multitude of nerve-cells that exist in the grey matter of the hemispheres, the great majority of which are probably never used in our ordi- nary mental functions. In fact, just as one spermatozoon suffices for impregnation, while thousands are produced only to go to waste, so it may be that a comparatively small number of the multitude of nerve-cells which are secreted in the brain are engaged in mental function, while thousands come and go without being called upon to perform any ^function under ordinary circumstances. A profuse and reckless waste of life is in the regular course of nature's operations. Recent physiological experiments on animals have at length thrown some light upon the functions of the cerebral convolutions. Instead of being insensible to all kinds of v.J HEMISPHERICAL GANGLIA. 265 stimuli as was so long supposed, Fritsch and Hitzig dis- covered that the application of a weak galvanic stimulus to the cortical layer excited movements ; they observed furthermore that these movements were of a definite co- ordinate character, and might be uniformly excited by stimulating particular convolutions. Not all the con- volutions thus reacted, for stimulation of some was fol- lowed by no external phenomena whatever ; but in those which did react to the stimulus the results were so defi- nite and uniform that they might be predicted. Similar ex- periments have been made in this country by Dr. Ferrier, who made use of the more intense Faradic current of an induction coil ; the results of which were to confirm and extend the observations of Fritsch and Hitzig.* It has been objected to these experiments that the electric currents are conducted from the surface of the brain to the motor centres in the ganglia beneath, and that the results do not therefore prove that there are motor centres in the cortical layers. An obvious answer to this objection was that motor phenomena are not pro- duced by stimulation of all the convolutions, not even by stimulation of some which lie in much closer relation to the corpora striata than those which do respond to the stimulus, and that the stimulation of closely adja- cent regions is followed by uniform results of a very different character. Moreover, it has been shown by Nothnagel and others that the removal of the centres, the stimulation of which produces certain co-ordinate movements, is followed by * A complete account of these experiments is given in Untersuch- ungen iiber das Gehirn, von Dr. E. Hitzig, Berlin, 1874. But the first paper on the subject appeared in Uu Bois Reymond's Archiv, Heft 3 : 1870. Dr. Hitzig severely criticises Dr. Ferrier, and roundly charges him with "adorning his work, without acknowledgment, with dis- coveries which belong not to him, but to us." Dr. Terrier's experi- ments are recorded in the West Riding Asylum Rtports, voL viii. P. 52, 1873. 266 THE PHYSIOLOGY OF MIND. [CHAP. paralysis of these movements. If the cortical area form- ing the presumed centre be not entirely removed, but only separated carefully from the parts beneath, so as to form a flap, and if the stimulus be applied when the flap is in position no motor result follows, showing that there is no conduction ; if the flap be turned back, and the fibres beneath be stimulated, the definite move- ment follows. Dr. Burdon Sanderson had observed that after complete removal of the supposed cortical centres of a group of movements these might still be excited by stimulation of the white fibres beneath, by which the removed centres had been connected with the corpora striata ; and quite recently he has succeeded in some instances, by fixing the points in the corpus striatum corresponding to the supposed cortical motor centres and applying the stimulus to them, in exciting the same definite movements as are produced by stimulation of the cortical areas. These experiments are quite in accordance with the opinion that the actual co-ordination of movements is effected in the motor ganglia, and with the observed phenomena of sensori-motor action, but they are also consistent with the theory that there are in the cor- tical layers higher centres which are differentiated by their special connections with the co-ordinating centres below and minister to voluntary movements which sup- ply us with the mental presentations, so to speak, of the movements. No doubt were our senses acute enough, and our instruments delicate enough, to limit the appli- cation of a stimulus to the special centre of co-ordination in the subordinate motor ganglia in all cases, we might always produce exactly the same definite movements as we do when we apply the stimulus to the higher cortical centres, but as things are, we certainly should not fail, in most instances, to excite a great many more centres in the motor ganglion if we were to make the attempt. v.] HEMISPHERICAL GANGLIA. 267 The conclusion then which we are warranted in drawing from the experiments is that there are in the cortical layers of the hemispheres motor areas which are differentiated by having their definite connections with the different co-ordinating centres in the subordinate motor ganglia. The question is, what is the actual function of these cerebral motor areas ? Fritsch and Hitzig reject the idea of an actual paralysis being produced by the extir- pation of one of the centres; believing the apparent paralytic phenomena to be due to a disturbance or destruction of the muscular feelings of the special movements. They fairly claim to have shown experi- mentally that those parts of the cerebral cortex, of which stimulation produces movements, and which act therefore as motor centres, are the seat of muscular feeling, of the conception of the measure and kind of the muscular innervation, or, in other words, of the so-called muscular intuitions. The sensory .and motor ganglia notably suffice to perform all forms of move- ment in a purely reflex manner after the removal of the hemispheres ; when the hemispheres are present, how- ever, the impressions of such reflex acts are carried cen- tripetally to the cortical centres, where they are, as it were, echoed or repeated, and the feeling of their inner- vation takes place, and so it comes to pass that the motor intuitions are formed which afterwards take their part in the conscious movements of the will. This con- clusion from experiment harmonizes well with what I have always maintained that psychological analysis teaches us concerning the nature of the motor intuitions and the essential part which they play in our mental life.* * In the first edition of this book, there was a chapter on "mo'or intuitions " which attracted no attention ; the argument of which was that while the immediate agents of definite movements were the motor ganglia, these, when active, had definite functional relations with the superordinate cerebral centres, in consequence of which they produced the motor intuitions in the latter. 263 THE PHYSIOLOGY OF MIND. [CHAP. The convolutions which respond to stimulation by giving rise to movements are in the anterior portion of the brain ; no motor effect is produced by stimulation of the convolutions of the posterior lobes. It has been sur- mised that the posterior convolutions are the seat of sensorial perceptions, for while the motor tract of the cerebral peduncles terminates principally in the cortex of its frontal part, some of the nerves of sense have been traced to the posterior convolutions, while others are presumed to end there. Moreover, a resemblance in some respects has been observed between the structure of some of these convolutions and that which is met with principally in parts that minister to sensation, to wit, the retina, the olfactory lobes, the nucleus of the fifth nerve, and the gelatinous substance of the posterior cornu of the spinal cord. Lastly, the results of experiments on animals, so far as they are definite and can be relied upon, are in favour of this supposition.* It would appear then that in the frontal part of the convolutions are con- tained the residua of the feelings of movements, from which we derive our. so-called motor intuitions, and that in the posterior part of the convolutions are contained the residua of the sensory perceptions, from which the sensory elements in ideas are obtained. Here then we have disclosed to us the path of a psy- chical reflex act The activity excited in the posterior convolutions passes to the anterior convolutions and there gets expression in the appropriate movement or speech. It is the simplest type of a mental process. We have reached in fact the higher ideo-motor or percepto- * The supposition has been recently strengthened by the results of numerous experiments which Dr. Ferrier has made upon the brains of monkeys. The briefest notices of these results have ap- peared in one or other of the medical journals, but I am not aware that any detailed description of the experiments has yet been published. -.] HEMISPHERICAL GANGLIA. 269 motor arc, which is spread above or overarches the sensori-motor arc ; perception answering to the afferent impression, and the efferent effect being the issue of the idea in movements. We may conceive the hemi- spheres to be formed of a multitude of such arcs which are interconnected in so many ways through junction- cells as to form a number of inconceivably intricate plexuses, such complication of structure producing cor- responding mental complexity ; wherefore it must almost always happen, after mind has been developed, that many associated sensory residua and many associated motor residua, joining forces with or antagonizing one another, are simultaneously or successively excited by a stimulus. Although movement may be looked upon as the outgoing energy of which sensation is the incoming supply, the expenditure of what has been gathered in, yet so many perceptions have been capitalized in the convolutions and may be drawn upon when a demand is made, that the outgoing current represents, not merely a reflected energy, but a motor effect which is charged with the gains of past experiences, that is to say, is enlightened by reason. It may be asked, what is the nature of the ideas that are formed in perception ? Are they impressions traced upon the brain, as Haller argued, or are they of the nature of minute vibrations or oscillations currents of molecular activity, along different nervous paths, as Bonnet ingeniously surmised? * It is easy to under- * " La faculte par laquelle les representations s'operent est ('imagination, mais les idees sont attaches aux mouvements des fibres sensibles. Pour qu'une idee se presente de nouveaux a Tame, il faut done que les fibres appropriees a cette idee soicnt mues de nouveau. La disposition du cerveau a repel er ces mouvements constitue done 1'imagination." BONNET, Essai de Psych. "Objections made to this opinion show how necessary to a know- ledge of psychology is a thorough knowledge of physics and physi- ology. It is said that the fibres are not capable of the tension and 13 270 THE PHYSIOLOGY OF MIND. [CHAP. stand that the occurrence of such vibrations along a nerve track on one occasion would render the delicately organized matter more apt to fall into similar vibrations on another occasion ; it has undergone a certain modi- fication in consequence of its excitation, and it will the more readily give back the same note, so to speak, or fall into the same rate of vibration, when it is again stimulated suitably, just as the stretched string of a piano, when several notes are sung in the room, will give back the note belonging to it. When we speak of a trace, vestige or residuum, all we mean to imply is that an effect is left behind in the organic element, a something retained by it, which disposes it to a similar functional act; a disposition has been acquired which differentiates it henceforth, although we have no reason to think that there was any original specific difference between one nerve-cell and another. When we are con- scious of this revival of the past, we say that we remem- ber it ; but when it takes place, as it does every minute of our lives, without consciousness, then we have no proper name for it. What are we to call this mental correlative of a nervous process which affects us not consciously? Those who would call it memory are charged with gross philosophical absurdity or with a relaxation which more rapid and forcible vibrations, or those which are slower and feebler, would require. As if the fibres were sup- posed to vibrate in their places like strings ! Then again, that they are not sufficiently numerous to answer to the myriads of millions of states of thought and feeling which are represented in memory and in the fancy. Again, it is objected, the theory, if complete and adequate in every other particular, would fail entirely to account for the creative energy of the imagination. Let it be granted that it did so fail, it might not be an entirely unprofitable failure, if it moved psychologists to reflect how little they account for by contentedly using the word imagination to do duty for actual knowledge, and helped them to realise what a quantity of ignorance they hide under its use." 7'he Human Intellect. Noah Porter, D.D. (p. 273.) T.] HEMISPHERICAL GANGLIA. 271 glaring contradiction of terms. Memory, it is said, im- plies consciousness, and the term ' unconscious memory ' is self-annihilating. So be it, if it is insisted that memory shall only be used in this restricted sense, only we must be careful not to let such use of the word blind us to the facts : we ought to take heed that we do not lose grasp of the important and incontestible fact that the physio- logical process of retention is something which lies beneath memory, which takes place unconsciously, and which is the physical basis of memory and of every other mental function. Believing then with Bonnet that ideas are insensible motions of nerve-molecules, of the nature of vibrations, or, as Hartley called them, vibriatuncles, we may grant that in Haller's description of them as impres- sions made upon the brain there was a just recognition of this important physiological process of retention. Ideas which arise from perception are naturally more vivid than when they are excited by internal causes ideas of presentation than ideas of representation because the motions are more easily and actively excited in the way they were first and are habitually excited, and because when excited by external causes, there is a vivid presen- tation of the sensory as well as of the motor element of the idea, which therefore occupies the attention more exclusively ; but if intense attention be given to them when internally aroused, they may be made more active, the sensory element being excited by reaction of energy upon its centre, and may sometimes become so vivid as to generate actual hallucinations. Just as the expression of an emotion by its suitable gesture will excite or in- crease the emotion, causing it to fill the field of con- scious vision, or, in other words, to engage the whole attention, so the internal repetition or actual utter- ance of the word which is the symbol of an idea re- acts upon the perceptive centre of it and makes more vivid, through this sensory representation, the concep- 272 THE PHYSIOLOGY OF MIND. [CHAP. tion of what it represents. We are only describing the same facts in different terms when we say that we are directing attention to it. In the foregoing chapter it was pointed out that a perception groups or organizes several sensations into one idea. Once the idea of the object has been thus acquired, any one of the different sensations of which it is constituted may suffice to arouse it ; it may be ap- prehended through sight, or touch, or perhaps taste or smell, not otherwise than as it may be apprehended through the written word after we have learnt to read : the sensation, like the word, is a symbol which serves to excite it. Our perceptions are really a language that we have been learning all our lives, and we no more per- ceive by a single sense the actual object, as we appre- hend it in idea, than we perceive the actual object in the artificial word or sign which has been used to de- note it Seeing alone, or smelling alone, for instance, would not impart any definite notion of the properties of an external object ; it could impart nothing more than its special sensation until a definite knowledge of the existence and nature of the object had been acquired by association of the sensation with the experiences of other senses, that is, by experience and observation. The impressions of its different qualities or properties received through the different senses are combined in the idea of it, and thenceforth we can think and reason about it abstractly through the idea when it is not pre- sent to any sense. This abstraction is made essentially easier by the fact that the object may be apprehended through different senses; not being inseparably linked to any one sensory impression, it is more easily thought about abstractly from all sensation. The idea in fact is organised as a separate mental existence in the cerebral convolutions, being for us, when so organised, to all in- tents and purposes the object, and may be aroused into V.] HEMISPHERICAL GANGLIA. 273 independent activity. Every idea is thus representative, the abstract of many sensations, comprising implicitly more than it displays explicitly ; in it the essential is embodied, the unessential suppressed or rejected ; it is not the idea of any particular object or event, but the idea of every object or event of a particular kind ; it is fundamentally a generalisation or induction. We may justly say, then, that the ideational nerve centres idealise or ideate our sensory perceptions; the process of idea- tion, like other processes of organic evolution, being one of progressive differentiation and integration, of discrimination of the unlike and assimilation of the like. As mental development proceeds we get not only more ideas, but ideas which are more and more abstract. From the idea of a concrete man we rise to the general idea of man, and from the general idea again we rise in ascending abstraction to the abstract idea or concept of benevolence, virtue, or other quality as belonging to man. As a percept is the abstract of sensations, so a concept is the abstract of percepts. It may be conjectured but it is a conjecture only that the superimposed layers of cells and fibres, of which the convolutions consist, answer to these increasing com- plexities of ascending abstraction; the lowest layer being concerned in concrete perception, the highest layer ministering to the most abstract thought. No animal, so far as we can judge, is capable of forming an abstract idea any more than a young child is, although there is good reason to think that the more intelligent animals are able to form a few general ideas ; a dog, for example, plainly having not only an idea of a particular man, such as its master, but a general idea of man apart from any particular man, and being pro- bably capable of conveying that idea to another dog. Savages occupy an intermediate position' between ani- mals and civilised men in this respect. The vocabulary 274 THE PHYSIOLOGY OF MIND. [CHAP. of many savages, which we may study profitably in order to ascertain what thoughts they have, is very limited, often containing only such phrases as are required to describe the most striking objects of nature, and those which enter into the daily life of the people. They have no abstract terms. In the North American languages a term suffi- ciently general to denote an oak-tree is exceptional j the Chocktaw language has names for the black oak, white oak, and red oak, but no generic name for an oak.* The Tasmanians, again, had no general term for a tree, though they had names for each particular kind of tree ; and no abstract words to express qualities, instead of hard, saying "stone-like," instead of round " moon-like," instead of high " with long legs."f The Bushmen, according to Lichenstein, could not count be- yond two, and many other savages cannot count beyond five. The language of the Friendly Islanders is said to contain no words expressive of the higher qualities of human nature, such as virtue, justice, humanity, or of their opposites, vice, injustice, cruelty; this is true also of the languages of the Native Australians and other savages. The Bongos of Central Africa have no words for the most common of our abstract ideas, such as spirit, hope, fear ; the words are absolutely wanting ; and experience shows that in this respect other negro tongues are not any better provided. % The Algonquin language, one of the richest in North America, contained no verb " to love," and when Elliot translated the Bible into Algonquin in 1661, he was obliged to coin a word to ex- press what was wanted. It is plain then from these examples that savages represent a much lower degree of mental development than civilised nations ; they are like children, who can- On the Origin of Civilisation. By Sir John I.ubbock. t Volkerkunde. Von Oscar Teschel, p. 116. J Schweinfurth's Heart of Afrifa, p. 311. v.] HEMISPHERICAL GANGLIA. 275 not understand abstractions, and must be instructed through sensible objects or pictures. The distance between animals and savages is undoubtedly far greater than that between savages and civilised people ; of the most intelligent animals only can we believe that they are capable of forming a few general ideas ; and we may venture to assume that no animal ever possesses an ab- stract idea. This destitution is closely connected with the absence of articulate language ; for as there are no actual objects, no external realities, corresponding to generaliza- tions, some sort of language is necessary, taking the form either of sound to the ear or of symbol to the eye, to fix the generalisations in order that they may be objects for future revival and use. Now it is plain that animals are without these necessary signs or symbols. Wanting verbal language, they want the signs by which to denote and express such ideas, but it would be an error to sup- pose that they are only destitute of abstract ideas because they have not language ; constituted as their brains are they would not have the capacity of abstract ideas, even if they had some capacity of language, because their brains have not the complication of nervous structure which is necessary to subserve such ideas ; and it is probable that, were they possessed of abstract ideas, these would not fail to enforce some means of expression, and that language would thus develop with the development of their minds. It is important to take notice of the nature of this process of mental development through ascending de- grees of abstraction, in order to estimate the true value or meaning of an abstraction. This must always be sought in the concrete, by resolving the higher abstrac- tions into lower abstractions, and these into the concrete. Had this searching method been pursued, instead of the opposite method of finding the meaning of the concrete in the abstract, many metaphysical entities would have died 276 THE PHYSIOLOGY OF MIND. [CHAP. at their birth, and much vain and empty metaphysical dis- cussion would have been spared to the world. It is instructive to take note how, when we consider the nature and origin of the language in which we express our intel- lectual processes and our feelings, we are perforce brought back to the senses and movements that is, to our means of actual contact with nature. " I see it," is commonly used to mean " I comprehend it," and in a similar sense we speak of the eyes of our understanding being opened. In like manner we grasp or apprehend an argument, fed a truth, have our feelings touched, disrelish or recoil from a proposal, are disgusted with a person's conduct. The French say Je gofite cela in an intellectual sense, and with \\\&iftj'entends cela means either "I hear that," or " I understand that." It is the same with other languages. The highest intellectual products betray their foundations in sense and movement by the terms which are used to denominate them. Those who are metaphysically-minded have done with idea as they have done with sensation ; they have con- verted a complex notion or general term, summing up a great number of varied phenomena, into an actual entity, and thenceforth allowed it to tyrannize over the thoughts. It is a great and mischievous error to suppose that an idea of the same object or event has always a uniform quan- titative and qualitative value ; and the way in which it is the custom to speak of certain abstract ideas, as if they were constant entities admitting of no variation, nor of the shadow of a change, is a remarkable example of that self-deception by which man fondly fools himself, "with many words making nothing understood." An idea may be definite, clear, and adequate, or it may be indefinite, obscure, and inadequate ; it by no means follows, therefore, that because the same name is given to an idea in two persons, it has the same value in each. The meaning which a child attaches to a particular word varies v.] I1EM1SPUERICAL GANGLIA. 377 according to its experience, being enlarged or reduced by new experiences, until it becomes precise and adequate.* Certain ideas will always have a different value in persons at a different stage of cultivation. When the well-mean- ing traveller or the ardent missionary thinks to find in the miserable savage the idea of a God, he should take heed that he is not erroneously interpreting the savage mind by the text of his ; and he might do well to be at the pains to define the idea which he supposes himself to have. The ideas of virtue and vice, for which the Australian savage confessedly has no words in his lan- guage, cannot be implanted or organised in his mind, until, by cultivation continued through generations, he has been humanised and civilised. (') Within historical and comparatively recent time such words as liberty, honour, right, and the like, have gradually undergone perceptible changes in meaning, and it is probable that they may continue to do so in the time to come ; for words, like creeds and laws, grow, change, decay, and die. Ancestral nervous substrata gradually become obsolete, as instincts in animals gradually become extinct, and new substrata are formed, as new instincts are de- veloped in animals, with changed conditions through ages. To acquire those so-called fundamental ideas, univer- sal intuitions, or categories of the understanding, of which some metaphysicians make so much, as constant elements, though they differ greatly in value in different people, there is no other need but, using Hobbes' words, " to be born a man, and live with the use of his five senses." ( 2 ) Because all men have a common nature, have the same number and kind of external senses, and because the nature by which all men are surrounded is * Beneke lays down the proposition " dass unter millionen Auftassungen desselben Gegenstandes auch nicht zwei cinander gleich sind." Pragmaththe Psychologic, p. 170. 278 THE PHYSIOLOGY OF MIND. [CHAP. the same, therefore are developed certain ideas which have a universal application, but they are nowise inde- pendent of experience ; on the contrary, the universality of their character is owing to the very fact that in every experience they are implicitly suggested or involved, so that they finally become fixed as endowments in the acquired nature or organisation of the nervous centres ; conscious acquisition becoming here, as elsewhere, un- conscious faculty, by virtue of an organic process. But their absolute truth, as expressions of certain fundamental relations between man and nature, is only guaranteed by the assumption of an unchanging persistence of these relations ; a new sense conferred upon him would en- tirely change the aspect of things, and render necessary a new order of fundamental ideas.( 3 ) As it is with the faculties of the spinal and the sensory centres, so it is with the faculties of the ideational centres : they are not innate, but are developed by education. The notion of innate idea, in the exact meaning of the word, as connatural, or contemporary with birth, is not less untenable and absurd than an innate pregnancy.(*) But if by innate is only meant that, by the necessity of his nature, an individual whose brain is well constituted will, when placed in certain circum- stances, acquire certain ideas, then all the phenomena of a man's life, bodily and mental, are just as innate or natural. A civilised person Certainly inherits, by virtue of being borrt of civilised parents in a civilised country, a predisposition to certain modes of conception and feeling, just as he inherits a predisposition to certain modes of perception or walking ; in other words, he inherits certain cerebral substrata which are ready to come into functional action on occasions of their suitable stimuli at the proper periods of life. He can no more help conceiving of his experiences in a certain way than he can help perceiving an object in a certain v.J HEMISPHERICAL GANGLIA. 279 way when he sees it, or than he can help feeling in a certain way when his reproductive organs come into functional action and arouse their cerebral representative substrata. It is necessary in fact to distinguish between what is predetermined by the nature of cerebral structure, as the so-called innate ideas are, and what is preformed, as they are not. The formation of an idea is an organic evolution in the appropriate nervous centres, which is gradually completed in consequence of successive ex- periences of a like kind. For our ideas of the size of objects, of their solidity, of their distance, and of their relations in space, we are dependent upon the move- ments of the eyes, and in so far as these movements presuppose an inborn mechanism by which they are performed, as they certainly do, we may properly say that the individual has an inborn aptitude or capacity to have such ideas. Man, whose cerebral convolutions are larger, more complex, and less symmetrical than those of the monkey, has in like manner an innate capacity of acquiring ideas which the monkey can never acquire, because he has the nervous substrata necessary to such functions. If he was made in the image of the ape, he is assuredly now born in the image of something higher than the ape. He is born with certain aptitudes which he has inherited in consequence of ancestral accumula- tions, is the heir of ages of acquisition, and so he learns to reason as he learns to see or to walk : when certain experiences are made through the effects of his social and physical surroundings, they result in certain developments, which could not be otherwise under the existing internal and external conditions. As the hu- man brain is constituted, it cannot, when certain facts are apprehended, help forming certain conclusions con- cerning them, the conclusion being as involuntary and irresistible as the instinct of an animal ; as Wundt has a8o THE PHYSIOLOGY OF MIND. [CHAP. remarked, the inner sense apprehends as a logical neces- sity what outer sense perceives as mechanical connec- tion, that which is given to us by psychological analysis as a logical conclusion being revealed to us by physio- logical analysis as physical effect. What is the mechanism of ideation, and what is the nature of the nervous action which is its physical basis, must for the present be entirely conjectural. It can hardly be doubted that there is a differentiation of parts in the grey matter of the convolutions, corresponding to differences of function, and that the cortical layers thus consist of a multitude of distinct mind-centres, so to speak, spread out in a sort of vault over the subordinate centres with which they are connected, directly or in- directly, by intercommunicating fibres, and spread out perhaps also over one another in superimposed layers. It is furthermore extremely probable that each sense has its special aggregate or grouping of cells in the convolu- tions, an area differentiated by its connections with the sensory ganglion beneath, which constitutes its perceptive centre, and has towards it, on the afferent side, the same relation which the motor areas in the anterior convolutions have towards the subordinate motor ganglia on the efferent side. Could we remove or extirpate exactly in any animal the perceptive centre of any one sense, we should eliminate from its perceptions of an object all those qualities thereof with which this sense was adapted to bring it into relation. But, as has been pointed out, a percept is a product of the combined action of more senses than one ; we must necessarily assume, therefore, the associated action of the perceptive centres of these other senses. Perhaps the most fit conception which we can form of the mechanism of the operation of ideation is that of a nervous circuit connecting a cell or a group of cells of each perceptive centre ; a current of molecular V.] HEMISPHERICAL GANGLIA. 181 action passing along this circuit would be the percept or idea of the object, and the current would naturally be excited at any point of the circuit to which the suitable stimulus could be applied. Obviously, however, the only points at which this could take place would be the cell-junctions, or the stations, so to speak, formed by the cell or group of cells of the respective perceptive centres included in the circuit Herein then lies the physical interpretation of the psychological fact that the idea of an object may be aroused by any one of the sen- sations of which it is formed. Furthermore, when an idea is thus aroused through one sense, the perceptions of the other associated senses being understood or not realised, we may conceive that there is only a subactive state of their cell-junctions, which may be supposed to act as continuations of the nervous circuit, rather than in the perceptive or receptive capacity in which they may act when aroused into more intense activity by a stronger stimulus : we may regard them in the light of stations on the track through which quick trains pass without stop- ping, but at which other trains stop to take in passengers, and at which any train may be stopped if necessary. The supposition is in entire accordance with what we know concerning the regular process of conversion of nervous actions which were at first conscious into actions that are purely automatic. When we rise from the percept to the concept, from the abstract of sensations to the abstract of perceptions, from representation to the representation of representa- tions, by combining into one general idea that which is common to several ideas and rejecting that which is different in them, it will be necessary to imagine more complex groupings of nerve circuits. We may imagine a higher and more complex circuit in which the nerve cir- cuits of the simple ideas now act as simple component units, taking the place in this circuit which the cell-June- 282 TflE PIiySlOLOGY OF MIND. [CHAP. tions of the perceptive centres have in the nerve circuit of the simple idea; the current of activity in the higher circuit will then be aroused by any one of these associated simple circuits, just as the current of activity in the simple circuit is aroused by any one of the associated perceptive cen- tres, and may become, like it, after several repetitions of function, automatic. In it the representatives are, so to speak, re-represented Multiplying these interconnected plexuses in accordance with the multiplication of our ideas, and associating them, as we must do, with corre- sponding motor plexuses in the anterior convolutions, we perceive the necessity of the infinitely complex me- chanism of cells and fibres which form the cortical layers of the hemispheres. They constitute such a complex structure as the complex mental functions must needs have ; for simple structures are capable only of simple functions. We may perceive also the reason of the necessity, if we would know the real value or mean- ing of the most abstract ideas, of seeking for it in the concrete; we must pass from the higher nerve-circuit to the lower nerve-circuits of which it is representa- tive, and from these again to the respective perceptive centres which they co-ordinate. If the abstract idea be not truly representative of the percept, and if the percept be not a just representation of the object, it is certain that we run great danger of losing ourselves in mazes of vague and erroneous reasoning. It is well known how difficult a business it is to observe an object or event accurately when we have a preconceived idea of it; the ideational current answers to, or, as it were, assimilates that which is like in the perception, and be- comes more active in consequence ; there is no reception or assimilation of that which is unlike in it, which is over- looked altogether, or at any rate not adequately registered; and the result is that the induction, which the perception really is, and the subsequent inductions of the higher v.] HEMISPHERICAL GANGLIA. 283 mental processes are unsound. Most part of a percep- tion is inference, for it is only when the mind actively co-operates after several experiences that it is adequate: and whether the inference be true or false will depend on the care which we have previously taken in observa- tion to build it up soundly, and on the care we now take, by proper attention to the object, to excite the right ideational current, if previous similar experience has fur- nished us with one; and if not, to appropriate a new nerve-circuit to the registration of that in the perception wherein it differs from former perceptions. The founda- tion of right reasoning is accurate perception.* How far men may go in vain reasonings about empty abstractions, when they abandon observation and divorce themselves from fact, refusing to bring their abstractions to the test of experiment, the records of mental philosophy yield abundant and instructive illustrations. The theory of mind as a spiritual entity, which, having an existence independent of the body, uses this as its instrument, owes its origin, as other metaphysical entities have owed their origin, to this tendency to convert abstractions into en- tities. Certainly, if I could perceive and measure the intimate and imperceptible currents of thought of another person's brain, as men may learn to do in time to come, they would be objective realities to me; but that is a * It may be remarked by the way that t\vo different classes of intellect are marked by the relative predominance of the assimilative or of the discriminative power : the superiority of one sort of in- tellect being shown by the way in which it discovers slight and deli- cate resemblances or analogies which are imperceptible to other minds, and in the variety and wealth of the language by which it expresses them ; the other sort of intellect being distinguished by its capacity of recognising and recording points of difference which other minds fail to observe. It is obvious that the just union of both these faculties is necessary to the best observation and reason- ing : they lie at the foundations of the method of agreement and the method of difference in formal reasoning. 284 THE PHYSIOLOGY OF MIND. [CHAP. very different thing from what metaphysicians have made of them ; and the only question for me would be whether they were as adequately representative immediately through presentation, or mediately through representa- tion of representations of the individual's surroundings as his brain-mechanism was capable of making them : the same question, in fact, as I should be required to con- sider if I were observing in a similar way the brain- currents of an ape or a frog, or if, being an accomplished musician, I were watching another person's musical per- formance in order to mark whether he brought out fully the capacities of the instrument on which he was playing. There is a question the answer to which one ought perhaps to endeavour to make more clear than it has been made thus far namely, Of what precise .part or pro- cess in a reflex cerebral function is idea the mental cor- relate ? There is the sensory impression ; there is the motor outcome ; and between them there is the cerebral track of the nervous current : of which stage then of the nervous process is the idea strictly the conscious corre- late ? The correct answer probably is that the entire process is necessary to the formation of the idea in the first instance, but that when its substrata have been de- finitely organised, a mental representation, faint or vivid, of either the first or the last stage, in connection with the cerebral intermediate process, may suffice; this mental representation consisting in an internal excitation of the proper perceptive or motor centre in the convolutions. A faint or nascent sensory perception may suffice in the one, it may be supposed, as a faint or nascent motor percept or intuition may in the other. And if we go on to reflect upon our ideas, we shall notice that with some the sensory element plainly predominates, so that we have the image vividly before our mental eye ; with others, the motor intuition is predominant, so that the word by which we denote the idea engages conscious- v.] HEMISPHERICAL GANGLIA. 285 ness ; while with other ideas of a more abstract character the intermediate cerebral factor is chiefly in operation, and little attention is paid to image or name. In the latter case we allow thought to call up thought without bringing it back to its sensory basis or to its motor ex- pression, although at the same time we feel it necessary to do both when we would positively satisfy ourselves that we have a clear, definite and genuine idea. It will be noticed also in this relation that we can intensify an idea either from the sensory or the motor pole of its cerebral process either by presentation and vivid repre- sentation of the object, or by such active intuition of the word denoting it as we get by repeating it to ourselves in- ternally in a sort of mental whisper or by uttering it aloud. In this way, .when our attention is prone to wander from a train of reflection, we hold it to its task by emphatic internal repetition of the words or the motor expressions of the ideas concerned, or by vivid sensory representa- tion of what we are thinking about. It would appear then that the idea is really the correlate of the entire excito-motor process in the convolutions, and that when either the sensory or motor element seems to be wanting, the reason is because it is understood ; being in such a state of faint or nascent excitation that it scarcely rises into consciousness. In using the physiological term 'excito-motor' to describe the process which takes place in the convolu- tions during ideation, and in referring it to the same category as the processes which take place in the lower nerve-centres, it behoves us to take heed that we do not overlook the complex nature of the nervous substrata which are subservient to it. Reflex function is merely a name, which neither conjures away difficulties magically nor furnishes an adequate explanation of them ; indeed, so far as it pretends to be an explanation, it is dis- tinctly an inadequate one, inasmuch as there is a great 86 THE PHYSIOLOGY OF MIND. [CHAP. deal more in mental reflection than a simple reflection of energy through the supreme centres from an afferent on to an efferent nerve. The central nervous substrata con- tain in their structure, first, a vast original capacity, and, secondly, a vast acquired capacity : they embody, as it were, a certain pre established harmony between their functions and the environment, which has been inherited, and a certain established harmony, which has been ac- quired by education and experience : they capitalise in a measure the acquisitions of the race, of ancestors, and of the individual. We cannot in the least com- prehend how it happens, but we cannot doubt, that the individual inherits in his cerebral "substrata not only parental but ancestral qualities of mind which are ready to come into function at different periods of life ; so that the qualities of one ancestor may discover themselves more evidently at one period, and those of another ancestor more evidently at another period, of his life. Reverting to the comparison which was previously made between the nerve- cell and the germ-cell, and taking it to be probable that the former, like the latter, contains in latent form the potential qualities of many ancestors, male and female, we may understand that it should, like it, when placed under suitable conditions, display them in its development. We may understand also how it is that one part of the convolutions can so easily take on the functions of another part, if we suppose, as we may reasonably do, that the nerve-cells, like the germ-cells, are endowed with very similar if not identical properties, and are therefore equivalent before they begin to function and to undergo that differentiation which, if not determined by original differences of properties, is involved in develop- ment under different conditions. It has been already shown that they exist in the convolutions in such count- less numbers that it is probable only a small proportion of them is ever utilised However that may be, it is V.] HEMISPHERICAL GANGLIA. 287 evident that when a stimulus excites the function of an ideational track for the first time, it does not merely excite a movement which passes along it without addition of energy, but awakens echoes that sound from we know not how far back in the past. Having said thus much concerning the nature of ideas and the manner in which they are acquired, I proceed next to indicate the different ways in which observation shows that the energy of an idea may be discharged : having considered its formation, it now remains to con- sider it in actual energy. (a) The reflex action or reaction of an ideational nerve- current is downwards upon the motor centres, and thus gives rise to what has been called ideomotor movement.*( 5 ) The energy may be exerted either upon the involuntary or upon the voluntary muscles ; in the latter case, taking * "To prove that Ideas, as well as Sensations, are the cause of muscular actions, it is necessary to make choice of cases in which the idea is in no danger of being confounded with that state of mind called the Will. And hardly any case will answer this condition, except ccme of those which are held to be involuntary, for the Idea itself never can be very clearly distinguished from the Will ." J. MILL, op. cit. p. 265. He instances yawning on seeing some one yawn, the infectious power of convulsions, laughter, sobbing, the swallowing of saliva, if assured that you cannot. "It seems, therefore, to be established by a simple induction, that muscular actions follow ideas, as invariable antecedent and consequent, in other words, as cause and effect ; that, whenever we have obtained a command over the ideas, we have also obtained a command over the motions ; and that we cannot perform associate contractions of several muscles, till we have established, by repetition, the ready association of the ideas." Ibid. p. 274. t "The idea of a particular motion," says Miiller, "determines a current of nervous action towards the necessary muscles, and gives rise to the motion independently of the will. " Again, of expectation, he says " It may be stated, as a general fact, that any state of the body which is conceived to be approaching, and which is expected with certain confidence and certainty of its occurrence, will be very prone to ensue as the mere result of that idea." iSS THE PHYSIOLOGY OF MIND. [CHAP. place either with consciousness or without consciousness. The idea that the bowels will act may notably sometimes so affect their involuntary peristaltic movements as to produce evacuation of them ; the idea that vomiting must take place, when a qualmish feeling exists, will certainly hasten vomiting ; and there is a very remarkable instance in the Philosophical Transactions of a man who could for a time stop the motions of his heart by composing him- self, and then either conceiving vividly or directly willing what was to happen.* ( 6 ) These are examples of the in- fluence of idea upon the involuntary muscles, and they accord with what has been previously said of the sub- ordination of the organic nerve-centres to the cerebro- spinal system. Some people even are able, through a vivid idea of shuddering, or of something creeping over their skin, to produce a cutis anserina or goose's skin : the immediate effect of the idea in this case, however, is probably to excite the appropriate sensation, which thereupon gives rise to the sequent phenomena. Examples of the action of idea upon our voluntary muscles are witnessed in every hour of our waking life. Very few, in fact, of the familiar acts of a day call the will into action : when not sensori-motor they are usually prompted by ideas. Most of the earlier actions of child- ren are prompted by ideas and feelings which, excited by suggestions from without, immediately pass into move- ments. In the adult, it sometimes happens that without any intervention of the will, or even in direct defiance cf the will, an idea discharges itself in movement or produces some other effect upon the body. The suddenly excited * "There is an instance told in the Philosophical Transactions of a man who could for a time stop the motions of his heart when he pleased ; and Mr. D. has often told me he could so far increase the peristaltic motion of his bowels by voluntary efforts as to produce an evacuation by a stool at anytime in half-an-hour." Zoonomia, vol. i. p. 39. v.] HEMISPHERICAL GANGLIA. 289 idea of the ludicrous, for example, causes involuntary laughter; the idea of an insult, a quick movement of retaliation; the idea of a beautiful woman, a glow of amatorial passion ; the idea of a great impending danger, or of a sudden terrible affliction, serious or even fatal disturbance of the organic life; the idea of an object, an actual hallucination sometimes. In the phenomena of electro-biology or hypnotism, the mind of the patient is possessed with the ideas which the operator suggests, so that his body becomes an automatic machine, set in motion by them. Every one's experience will recall to him occasions on which an idea excited in his mind could not be dismissed therefrom by the will, and perhaps would not let him rest until he had realised it in action, even though such realisation appeared to his judgment inadvisable. But the point on which I would lay stress here is, that such ideomotor movements may take place, not only without any intervention of the will, but also without consciousness; they are automatically accom- plished, like the actions of the sleep-walker, in obedience to an idea or a series of ideas of which there is no active consciousness. It may seem paradoxical to assert, not merely that ideas may exist in the mind without any conscious- ness of them which every one admits that in their dormant, latent, or statical condition they may but that an idea, or a train of associated ideas, may be quickened into action, and actuate movements, without itself being attended to. But those who reflect upon their actions will acknowledge that it is unquestionably so : a great part of the chain of our waking thoughts, and of the series of our daily actions, never is attended to ; at first consciously acquired, they have now become au- tomatic, the effect being that which first arouses con- sciousness, if it be aroused at all. Persons who have a habit of talking to themselves are generally unaware that 290 TUE PHYSIOLOGY OF MIND. [CHAP. they are talking, and yet they are performing both asso- ciated ideas and associated movements; and one who has a lively interest in some performance which he is watching intently, can hardly forbear making ludicrous movements of imitation. The phenomena of table-turn- ing, spirit-writing, divining with the magnetic rod, and the like, when they are not impostures, illustrate in like manner the unconscious action of idea upon movement, as do also the sudden cures of supposed paralysis which have sometimes been effected by an impressive command to rise and walk from one who claims a miraculous power of healing, or by the application of some instrument alleged and believed to have marvellous healing virtues. In such cases the idea of the movement, the belief that it will take place, is truly the movement in the inner- most ; it is the current of nervous action which, when transmitted along the proper nerves, will become the ex- ternal movement. And it is not without interest to note how in some of these instances the vivid idea of a move- ment may produce a more powerful effect than a deli- berate exertion of will could do ; for the idea represents undivided energy operating in a definite channel, no other ideas or feelings intervening to produce doubt or irresolu- tion, while there is not, from want of a proper training of mind, the power of effective co-ordination of its various energies into a complete and definite act of will. Indeed, the miraculous cures of paralysis which are from time to time recorded, take place commonly in hysterical persons whose malady is a paralysis of will rather than a paralysis of muscle. It is surprising how uncomfortable a person may be made by the obscure notion of something which he ought to have said or done on some occasion, but did not say or do, and which he cannot for the life of him remember. There is a dim feeling of some impulse unsatisfied, an effort, as it were, of the lost idea to get into conscious- v.] HEMISPHERICAL GANGLIA. 291 ness ; the activity thereof not being sufficient to excite distinct consciousness, but sufficient to react upon the unconscious mental life, and to produce a feeling of dis- comfort or vague unrest, which is relieved directly the idea bursts into consciousness. Certainly the tone of mind at different times is much affected by obscure sub- active ideational currents which do not reach the level of distinct consciousness, not otherwise than as there are un- dulations constantly striking upon the senses of sight and hearing which are too feeble to excite definite sensations of sight or sound. Then, again, when an active idea has once taken fast hold of consciousness, how hard a matter it is to dismiss it ! Some weak-minded persons cannot do so until they have expended its force in suit- able action : let a hysterical woman get a vivid idea of some action that she must do or cannot do, the idea be- comes a fate which she must sooner or later obey, not otherwise than as a person who is in a state of so-called mesmerism or hypnotism is dominated by the idea which the operator suggests. Let a quick-tempered man con- ceive a great insult suddenly done to him, in a moment, without any intervention of the will, the idea reacts upon the muscles of his body, and produces more or less general tension of them. Let a man engaged in a fight or a race get the idea that he will be beaten, his muscular energy is weakened, and he is already half vanquished : let another have the idea that he will win, his muscular energy and skill are augmented, and he is already half victor. () The ideational nerve-current may operate down- wards not only upon the motor nuclei, but also upon the sensory ganglia. As the idea is excited into activity by the impression on the senses, so it may in turn react back- wards upon the sensory centres, giving rise even undei certain circumstances to illusions and hallucinations. " I am confident," John Hunter said, " that I can fix my 29* THE PHYSIOLOGY OF MIND. [CHAP. attention to any part until I have a sensation in that part." The idea of a nauseous taste or of a putrid stench may excite the sensation to such a degree as to produce vomit- ing ; and the sight of a person about to run a sharp in- strument over glass will set the teeth on edge. The images of dreams, as Spinoza remarked, are sometimes actually visible for a short time after the eyes are open on awaking. " On awaking one morning out of a distress- ing dream, just as day was breaking, the images I had had present to me in my dream floated before my eyes as distinctly as if they had been actual objects. One form in particular, that of a leprous negro, whom I had never seen in my life, presented itself to me with singular dis- tinctness, but faded and in a great measure disappeared when, to turn my thoughts to something else, I fixed my eyes on a book ; as soon, however, as I allowed my eyes to wander from the page the vision of the blackamoor presented itself with the same vividness as before. By and bye it began to fade, and anon it disappeared en- tirely." * " The celebrated Baron von Swieten," says Dr. Darwin, who illustrates this kind of ideational action by many instances, "was present when the putrid carcase of a dead dog exploded with prodigious stench ; and, some years afterwards, accidentally riding along the same road, he was thrown into the same sickness and vomit- ing by the idea of the stench as he had before experi- enced from the perception of it." The action of idea upon sensory ganglia is a constant * Letter to P. Balling. See WILLIS'S Translation ofSpinoza ) p. 289. I have on several occasions experienced this persistence of dream- images on awaking in the night out of a dream, notably after tours in North Wales and Switzerland, in which I had made mountain ascents. Pursued in dreams by vivid images of mountain peaks and precipices, and steep and difficult paths, I could not, for a little while after awaking, realise that I was safe in bed, for I con- tinued to see the images of the dream, and was obliged to put my hands out and grasp each side of the bed to convince myself. v.J HEMISPHERICAL GANGLIA. 293 part of our mental life ; for the co-operation of sensory activity is, as I have already pointed out, necessary to the completeness of the idea to clear conception and repre- sentation. -In order to form a distinct and definite concep- tion of what is not present to sense, we are compelled to form some sort of image of it in the mind ; the sense of sight, which is anatomically in most extensive connection with the cerebral ganglia, affording us the greatest assistance in this regard. Men differ much in the power which they have of thus rendering an idea sensible. Goethe could call up the image of an object at will, and make it undergo various transformations before his eyes in accordance with the changes which he conceived in it ; and Shelley appears to have been, on one occasion at least, the victim of positive hallucinations generated by his ideas. But the most remarkable instance of a habit of seeing his own ideas as actual images was afforded by the engraver, William Blake " You have only to work up imagination to the state of vision, and the thing is done," was his own account of the genesis of his visions.* To render defi- * Dickens used to al'ege that he heard his characters actually speak to him. " Mes personnages imaginaires m'ecrit le plus exact et le plus lucide des romanciers modernes, m'affectent, me poursuivent, ou plutot c'est moi qui suis en eux. Quand j'ecrivais 1'empoisonne- ment d'Emma Bonary, j'avais si bien le gofit d'arsenic dans la boufhe, j'etais si bien empoisonne moi-meme, que je me suis donne deux indigestions coup sur coup, deux indigestions tres reelles, car j'ai vomi tout mon diner." TAINE, De f Intelligence, vol. i., p. 94. The more striking, as arsenic has a scarce appreciable taste. " Dr. Ferrier mentions of himself that, when at the age of fourteen, if he had been viewing any interesting object in the course of the day, as a romantic ruin, a fine seat, or a review of troops, as soon as evening come the whole scene was brought before him with a brilliancy equal to whit it possesses! in daylight, and remained visible for some minutes." ABERCKOMRIE, On the Intellectual Powers. Sir I. Newton could recall an ocular spectrum of the sun when he went into the dark and directed his mind intensely, "as when a man looks earnestly to see a thing which is difficult to be seen." From these 14 294 THE PHYSIOLOGY OF MIND. [CHAP. nite the creations of the imagination, and to give fit ex- pression to them, they must be accompanied by some sensorial representation. The great writers whose vivid descriptions of character, scenery, or events hold our attention and stir our feelings, have this power in high degree ; they create for themselves a world of sense by the influence of idea, and then strive to present vividly to us what they have thus represented to their own minds. Natural endowments being equal, those writers who have the greatest number of residua stored up in consequence of much and varied experience, are best qualified to call up vivid images, and best qualified to call up such as are truly representative of nature ; whilst those who are wanting in experience, or who have not sufficiently cul- recollected images of objects of sense, which the reason duly dis- tinguishes from the realities around, we meet with examples marking a gradual transition to those spectral images or illusions which can- not be distinguished from realities, which, in iact, compel belief, and excite emotions and actions in accordance with their character. Abercrombie mentions the case of a gentleman who was all his life affected by the appearance of spectral figures. Meeting a friend in the street, he could not satisfy himself sometimes whether he really saw the individual or a spectral figure, unless by touching the figure or listening to the sound of his footsteps. He had also the power of calling up spectral figures at will, by directing his attention steadily to the conceptions of his own mind, whether figures or scenes he had seen, or a composition of the imagination. " But though he has the power of producing the illusion, he has no power of banish- ing it ; and when he has called up any particular spectral figure or scene, he can never say how long it may continue to haunt him." An intense mental impression may produce such illusion involun- tarily. A step farther, and there is neither the power of calling up an illusion at will for it rises in spite of the will nor of distinguish- ing it from realities, nor of dismissing it at will. It is excited by some morbid cause, confounds itself with realities, compels belief, and dominates the conduct. This is the case with those insane persons who hear voices continually speaking to or of them, reply- ing to their unuttered thoughts, suggesting blasphemous or obscene ideas, and reviling or threatening them. v.] HEMISPHERICAL GANGLIA. 295 tivated observation, are sure to become visionary, vague, and unreal. Even in matters of scientific research, the scientific imagination by which hypotheses are succes- sively framed until a fit one is obtained, its verification completed, and a discovery thus made, is based upon a previous careful training of the senses in scientific obser- vation, and works by means of sensory representations. Natural endowments not being equal, however, we then perceive the wide difference which there is between one who has adequate ideation and one who has not The latter, in describing character, scenery, or events, will give a tedious picture characterised by minute industry and overwrought detail, in which there is no due subordina- tion of parts, no organic unity of idea in which truly soul is wanting and from which, therefore, no one can carry away a true idea of the whole : unpregnant of his subject, he has gone about to give a photographic copy or a minute delineation of what cannot be photographed ; he has laboured to realize the appearance until at last only something unreal remains.* The former, on the other hand, produces, by virtue of the plastic power of idea, a picture in which the unessential is suppressed, the essential extracted and moulded into an organic unity, in which due subordination and co-ordination of parts pre- vail, and from which, therefore, a true idea of the whole may be educed; truly comprehending or grasping his subject, he has in fact idealised the sensory perceptions, * " For facts," Lord Shaft esbury observes in his Characteristics, " unably related, though with the greatest sincerity and good faith, may prove the worst sort of deceit : and mere lies, judiciously com- posed, can teach us the truth of things beyond any manner. But to amuse ourselves with such authors as neither know how to lye, nor tell ttuth, discovers a taste which methinks no one should be apt to envy. The greatest critic says of the greatest of poets, when he extols him the highest, that above all others he understood how to lye: A5<5a(rxe 8f paAiara "O/iijpos KO! TOWS fiAAovs vofuSij Af)< 296 THE PHYSIOLOGY OF MIND. [CHAP. producing the illusion of a higher reality, and so displayed a real development of nature. This sort of difference between men is not less evi- dent in scientific working. One man records, with a praiseworthy but tedious industry, the unconnected im- pressions made upon his senses, and never gets further than that : fondly thinking that he sees with his eye, and not through it, he is very much like one who should, were he set to describe the sun for the first time, delineate with great care and exactness its ap- pearance to the eye, and rest content for the future with this sensory representation of it. The other and truer man of science succeeds in combining, by means of the organising power of idea, the scattered impres- sions made upon the senses, is able by comparison to complement or correct the impression made on a particu- lar sense, and to form to himself a true image of the sun, not as a mere disc of fire, but as an immense central body moving through space with its attendant planetary system. Only those who are destitute of idea would dream of rejecting entirely the aid of idea in scientific inquiries. These observations will not be a useless digression if they serve to teach how essential to the completeness of conception is the functional action of the sensory ganglia ; how much our intellectual development depends, not only upon the cultivation of careful habits of observation, but also upon the co-operation of the sensory centres in the subsequent intellectual action. The excitation and cultivation of the sensorial centres are necessary antece- dents, in the order of mental development, to the activity of the ideational centres ; and the ideational centre in turn performs its complete function in the formation of a distinct conception by reacting downwards upon the sen- sory centres. This secondary intervention of the sensory ganglia is not peculiar to man, being, perhaps, more evi- v.] HEMISPHERICAL GANGLIA. 397 dcntly displayed in some of the lower animals in which the ideas are so much fewer and so much Jess complex than in man. When the dog scents the rabbit, and begins to scratch furiously at the burrow, it is plain that the sense of smell has excited either directly the visual image of the rabbit, or rather, as the 'dreaming of the dog would seem to indicate, the idea of the rabbit, which idea there- upon calls up the appropriate visual image. It is worthy of remark in this relation, how singularly effective in man the sense of smell is in recalling vividly the ideas and images of forgotten scenes and places : there are certain smells which never fail to bring back to me instantly and vividly scenes of my boyhood, though I was not in the least thinking of them at the time. The reaction of ideas upon the senses is again very notable in dreams : for my part, when dreaming, I sometimes see pages of printed matter, which I read with a conscious effort and, as it were, a straining of the eyes, and understand; nay, more, I may awake, recognise it to be a dream, close my eyes, go in- stantly to sleep again, and resume the reading, continu- ing it by an effort, and conscious that the whole thing will vanish if my attention be withdrawn. At one time or another, most persons must have been awakened sud- denly by the distinctly heard voice of a dream-image. In insanity, when the nerve-centres are disordered and their relations disturbed, actual hallucinations of a sense, such as cannot be corrected by the evidence of unaffected senses, or by reflection, are sometimes due to the influence of morbid ideas. This disordered action is, after all, only an exaggeration of a process which is natural in our mental life. The idea cannot receive its stimulus directly from the external world, nor can it react directly upon the external world : both in its origin and in its expres- sion are the senses concerned. The idea of a sensation, which we have seen to be 298 THE PHYSIOLOGY OF MIND. [CHAP. sometimes so vivid as to become an actual hallucination, is no doubt an internal current or movement which is an imperfect reproduction of the movement caused by the external impression ; it will naturally therefore increase the susceptibility to such impression, forasmuch as the movement in the nervous centre occasioned thereby will be more easily and completely excited in conse- quence of being already in partial action; in other words, susceptibility will be increased by attention.* The madman who has the delusion that poison is secretly put into his food, or that persons in the streets say offensive things to him or of him, readily tastes the poison which is not there, or misinterprets innocent words to fit his thoughts ; the lover " sees Helen's beauty in a brow of Egypt;" and the poet finds his moods of feeling in the aspects of nature. The external im- pression easily produces the feeling which each is prepared to feel. For the same reason expectant idea is a potent cause of hallucination. The man who sees a ghost is he who expects to see one. In making his experiments on hypnotism, the phenomena of which are of the same nature as those of mesmerism, Braid found that if sus- ceptible persons believed that something was being done, although they did not see it, by which they were to be affected, they would become affected, while, on the con- trary, the most expert hypnotist might exert all his en- deavours in vain if the person did not expect it He relates the case of a lady who, when told to look intently at a horse-shoe magnet in a dark closet, saw nothing ; but when told to look again and she would see sparks of fire * This has been proved experimentally. Perception, like every other mental process, takes time. This time, which has been measured, and which may differ in different persons, or in the same person at different times, is less if the nature of the impression to be made is known beforehand, less still if the instant of its appear- ance be foreseen. v.] HEMISPHERICAL GANGLIA. 299 issuing from it, presently saw fire burst forth from it, which she continued to see when the magnet had been secretly removed. In like manner, at the so-called spiritual seances, the idea of an event being about to happen will produce in some persons a conviction that they actually see or feel it happen. A person of a certain sort of ner- vous temperament, sitting in the dark for some time in complete silence, having the feeling of some mysterious agency at work, and eagerly expectant, gets into such a state of mind that he is ready to perceive what he is confidently assured will occur, and perceives it accord- ingly, when what really occurred was perhaps something quite different. The rule of sound observation is that the mind should be free from a preconceived idea ; the rule of those who call spirits from the vasty deep is that the mind should be possessed by the preconceived idea. It has been the same with miracle-mongers in all ages. The man who sees a miracle, like him who sees a ghost, is the man who expects to see one ; wherefore the testi- mony as to miracles when religious emotional excitement prevails is of no value. As in a burning substance the heat given off by the portion that is combining with oxy- gen raises the adjacent part to a temperature at which it also will combine with oxygen and burn, so a high tem- perature of emotion in one person raises the temperature of emotion in his neighbour, and the epidemic of excite- ment and credulity spreads like wild-fire. It has always been the perverse custom of miracles to happen in the presence of those who were so full of faith that they did not require their occurrence in order to testify of them, and to fail to happen in the presence of those who were of so little faith as to doubt It is a disputed question whether the idea or emotion, when it acts upon the sensory centres so as to produce a hallucination, transmits the current of nervous action along the sensory nerves to the organs of sense. Miiller 300 THE PHYSIOLOGY OF MIND. [CHAP. believed that a current passed in this way from the centre to the periphery, just as happens when the ideational current affects nutrition or movement. Certainly it has been proved by the experiment of uniting the distal por- tion of a divided sensory nerve with the proximal portion of a divided motor nerve, that a current may traverse a sensory nerve in a dowmvard or efferent direction. On the other hand, it is certain that the hallucination would be generated if the sensory ganglia only were affected, and that the mind will always in such case refer the sensation to the peripheral end of the nerves. A person may have a visual hallucination when the retina and the optic nerve are so wasted as to be incapable of function, and an auditory hallucination when the auditory nerve is destroyed ; and one who has had his leg or arm ampu- tated feels sensations, as if he still possessed the lost limb, for some time after its removal. The transmission of the current to the periphery, whether it takes place or not, is clearly not essential. Some writers are in the habit of speaking of the sensation as not real but de- lusive, when it is of subjective origin. But the sensation is real, however it originate : the man who believes he sees a ghost has a real sensation of it, although he does not really see it, there being no object outside his eye to make that impression upon it which we mean by see- ing. Like the dagger which Macbeth saw, it is before his mind's eye, but not before his bodily eye. (c) A third important, though little recognised, way in which idea may operate, is upon the functions of nutri- tion and secretion. Whether the idea act, as is probable, directly upon the organic elements of the part through its nerves, or indirectly by an effect upon the vaso-motor system, or in both ways, it is certain that the energy of idea may increase or lessen a secretion, and may modify nutrition. The idea of food will cause a flow of saliva ; a sympathetic idea, a flow of tears ; the idea of suckling, v.] HEMISPHERICAL GANGLIA. 301 a secretion of milk ; the idea of itching in a particular spot will give rise to an itching there ; and the idea that a structural defect will certainly be removed by a particular manipulation does sometimes so affect the organic action of the part as to produce a cure. The most successful physician is ever one who inspires his patient with the greatest confidence in the virtue of his remedies ; and he is most likely to be attacked by epidemic diseases who most fears them. Bacon rightly, therefore, would have us inquire into the best means to " fortify and exalt the imagination." " And here," he says, " comes in crookedly and dangerously a palliation and defence of a great part of ceremonial magic. For it may be speciously pretended that ceremonies, characters, charms, gesticulations, amu- lets, and the like, do not derive their power from any tacit or sacramental contract with evil spirits, but serve only to strengthen and exalt the imagination of him who uses them." * It is well known that a bread pill will sometimes purge violently one who, believing that he has taken a strong purgative, confidently expects the purgative effect, and a perfectly innocent draught may produce sleep, when it is believed to contain a narcotic. On one occasion I was consulted about an old lady who for years had been in the habit of taking two purgative pills, two or three times a week or oftener, and a dose of chloral every night. Her husband, who thought that she must be doing injury to her health by this practice, substituted bread pills for those which she bought, and greatly lessened the dose of chloral, without saying anything to her ; the usual effect being produced in both cases. But it was always neces- sary that there should be a taste of chloral, however little the quantity of the drug, for the effect to be produced. The idea of a person that he will go to sleep, certainly pro- motes the occurrence of sleep ; the idea that he will not, * De Augmentis Scientiarum, B. iv. 302 THE PHYSIOLOGY OF MIND. [CHAP. -* on the other hand, as certainly tends to keep him awake ; and the idea that he must awake at a certain hour usually causes him to awake at that hour, or perhaps more often before it.* The so-called stigmata which the ecstatic mystics pro- fessed to show on their hands, feet, side, or forehead, in imitation of the sufferings which Christ underwent from the nails, spear and crown of thorns, were effects of the action of idea upon nutrition, if they were not fraudu- lently produced. But it is impossible for those who are not eager to seize opportunities of practising faith, to avoid the suspicion that they who thus professed to bear in their bodies the marks of the Lord Jesus bore ulcer- ations artificially produced, for the marks most often occurred in women of highly nervous temperament, whom experience proves to be not unapt to simulate strange bodily affections. It is to be regretted that the examination in such cases, when they occur now, is seldom made with such strictness as to exclude fraud : if the hands are the seat of bleeding, it is evidently not enough to put them in strong gloves and to take every precau- tion that these cannot be taken off, if they are penetrable by a needle. In a case of alleged spontaneous bleed- ing from a part of the surface of the body which occurred at one of the London Hospitals, the imposture was detected by placing secretly in the covering which was fastened over the bleeding surface a piece of tin- foil, which was found on examination afterwards to have many perforations by a pin or needle. It should be borne in mind, when attributing such events to * This is a curious fact, as it would appear to indicate that there is an appreciation of the lapse of time during sleep. We observe something of the same kind in the day, for a man who has not heard 7 clock strike, or looked at a watch, has a tolerably accurate notion what the hour is, especially if lie has been going on in his usual routine. V.] HEMISPHERICAL GANGLtA. 303 fraud, that it may not be deliberate deception in all cases. Deception is not a definite, constant mental state, which either is or is not, and which therefore when it is not, may be eliminated entirely from consideration. There are various degrees of deception ranging from the most wilful deception to the most innocent unconscious self-deception ; and assuredly the greatest impostor is he who imposes upon himself as well as upon others. We ought in this relation to take account of those peculiar states of abnormal consciousness which occur in dream- ing, hypnotism, epilepsy, catalepsy, even ecstacy, and the like morbid states, when it will appear not impossible that a person might, in a so-called ecstatic trance or vision, fabricate a stigma, and yet be unaware, when he returned to normal consciousness, of what he had done when he was, as it were, alienated from his proper self. For it is certain that those who fall into these anomalous states may, when they come to themselves, be quite ignorant of what they did while in the state of abnormal consciousness. I doubt not that some of those who suffered from what I take leave to call theolepsy were of this class. ( or excito-motor process in which a cerebral mechanism of extreme delicacy and intricate complexity of con- struction, embodying past experiences in its structure, intervenes between the ingoing stimulus and the out- going movement ; it is, if I may use such an ungainly compound term, a complex afferent-cerebro-efferent pro- cess. A volition or ideo-motor process which, though active in the brain, stops short of expression in actual movement, or in the inhibition of movement, is a belief: it is a certain internal experience which we feel and know can become a certain external experience, if H* THE PHYSIOLOGY OF MIND. [CHAP. necessary. " The will and the intelligence are one and the same thing," was the corollary of Spinoza from his close reasoning. Let us imagine the first appearing idea in the infant's mind to react outwards, and to leave, as it will do, its after-effect in the nervous centre : when the idea occurs again, there will be a tendency to a similar reaction. Suppose, however, that the action causes pain to the child, and that thereupon a second idea is formed in its mind, the energy of which is opposed to that of the first. When the first idea recurs, it will, instead of pass- ing outwards at once, excite into activity the second idea, which is inhibitory or preventive.* That is the simplest case of volition : the child has voluntarily re- frained from doing something, or has voluntarily done something else, having gained by its experience a belief that the act which it foregoes would be painful ; and the impulse that prompted the choice was not any abstract power, but sprang from that fundamental property of organic element by which what is agreeable is sought, what is painful is shunned. Bear in mind, when weigh- ing volition, that there is often more power demanded for preventing or inhibiting action than for producing it. As ideas multiply in the mind, and groups or series of ideas are associated, of course the process becomes more and more complicated ; the residua of volitions, like the residua of sensations or ideas, remain in the mind and render future volitions of a like kind more easy and more definite ; abstract or general volitions, as it were, are * This inhibition in the highest nerve-centres is just as mechanical as that which we have seen lo take place in the spinal cord, and does not betray any more mysterious agency in the one case than in the other. In the complex organised union of nerve-centres one has the power, when excited, either of discharging or of inhibiting the activity of another centre : it is a common physiological function of nerve-centres, and what we call volition is the subjective aspect of it as it takes place in the supreme cerebral centres. Vii.] VOLITION. 443 formed as the representatives of certain trains or groups of ideas, or as the expression of their due co-ordinate activity ; and by their persistence in the mind, when not in consciousness, and their interaction there, the charac- ter of our thought, feeling, and action is modified in a way which we cannot comprehend. Every one must have felt that an act which was at first disagreeable and demanded a painful effort of will may become, in fact invariably does become, after several repetitions, much less disagreeable or even an easy habit. Not only, how- ever, does that particular act lose its painful qualities, but all acts of a like kind or of the same genus are made easier ; and our manner of feeling with regard to them, and even our judgment concerning them, are greatly modified. Though we can give no explanation of the way in which we are aided by the traces of past volitions, it is plain enough that we are so aided ; conscious ac- quisition becomes unconscious power ; by an organic assimilation of some kind, even the will becomes auto- matic in certain relations. I suppose that if man could ever succeed in attaining to a perfect harmony with environing nature including in that word the nature of men and things around him so as to perceive and act in all relations with the unreflecting certainty and precision of instinct, he would have neither memory, nor reason, nor feeling, nor will, all which imply a persistence of the mental excitation in consciousness, but would act with the automatic regularity, precision and cer- tainty of a perfect machine. For what are these functions? Memory is the conscious recalling of former experiences for the purpose of comparison ; feeling the pleasing or painful character of experiences ; reason the deliberate weighing of them whence are deliberation and hesita- tion in consciousness ; and will the conscious impulse at the end of deliberation. Ideas are, on the efferent or motor side, nascent movements that is, intuitions 444 THE PHYSIOLOGY OF MIND. [CHAP. of such movements as have been performed ; on the afferent or sensory side, they are images of the sensory impressions which have been experienced, the revival of such sensory impressions on the occasion of a suitable external stimulus being perception. Plainly, then, none of these conscious functions neither memory, nor feeling, nor reason, nor will, would be necessary or be displayed if the complete harmony imagined were realised. These conclusions may then be distinctly formulated from the foregoing considerations : first, that wherever an afferent nerve passes to a cell or group of cells in the cortical layers of the hemispheres, and an efferent nerve issues from the cell or group of cells, there is the possi- ble or actual centre of a particular volition ; and, secondly, that volition or will, used in its general or abstract sense, does not denote any actual entity which existed anterior to experience, but simply expresses the due co-ordinate activity of the supreme centres of mental force, not otherwise than as the co-ordinate activity of the spinal cord or medulla oblongata might be said to represent its will the faculty in both cases being commonly an ac- quired one in man. Consequently there is no normal volitional power in the abstract; that is the normal power which each person develops for himself by in- telligent exercise ; and that will be the most perfect volition in any case which expresses the most perfect consensus of all the energies, mental and bodily, of a healthy organism. When an animal acts in answer to some stimulus with direct and definite purpose, or, as we are in the habit of saying, instinctively, it does so by virtue of an endowment of its nerve centres which is ori- ginal in it ; but in the formation of human volition we observe the power of intelligent action in gradual pro- cess of acquirement we witness an illustration of design in the making ; and if we only go far enough back through generations, the acquisition by the animals may sometimes vii.] VOLITION. 445 be traced. It would belie observation less to place an ideal entity behind the innate instinctive impulse of the animal than behind the gradually fashioned will of man. To the fullest action of will in an individual two con- ditions are obviously necessary ; first, an unimpeded association of ideas, whereby one conception may readily call up another, and complete deliberation ensue ; and, secondly, a strong personality or character to give the decision between conflicting ideas and desires. I shall say something of the second condition first. The strong or well- formed character which a well- fashioned will implies is the result of a good training applied to a well constituted original nature; and the character is not directly determined by the will, but in any particular act directly determines the will.* Character in truth settles not only what a person shall feel and do, but even what he shall think and believe, as it must needs do seeing that feeling and action lie deeper than thought and belief. Men are in some sort predestined by temperament to be spiritualists or materialists, orthodox * Common language, Tucker observes, implies two wil's or more, opposing, impeding, restraining, and mastering one another ; when an inordinate passion interferes with the prosecution of some design, we still regard it as a vo'untary result, because sensible of the in- stigation. " But if we listen to the common discourses of mankind, we shall find them speaking of several wills, several agents, in the same person, resisting, counteracting, overpowering, and controlling one another ; hence the so usual expressions of the spiritual and carnal wills, of the man and the beast, of self-will and reason, of denying our wills, subduing our passions, or being enslaved by them, of acting unwillingly or against the will, and the like. All which takes rise from a metonyme of the cause for the effect ; for our actions being constantly determined either by the decisions of our judgment, or solicitations of our desires, we mistake them for the will itself ; nor is it a little confirmation of the will being actuated by motives, to find them so intimately connected therewith, that a common eye cannot distinguish them apart." Light of Nature, i. 547. 146 THE PHYSIOLOGY OF ML\'D. [CHAP. or heretic, Evangelicals, Calvinists, Swedenborgians and the like. They are not moved by argument, discussion only feeding conviction ; wherefore it is that abstract questions, which are of no real moment, are contested with the greatest heat and acrimony, and with- out altering belief one jot A man cannot think truly, cannot realise in belief, that which his character cannot assimilate, any more than the string of a harp can respond to a note which is not its own, and is honestly astonished that others cannot be brought to see things as he sees them : his range of thought and belief is conditioned by his inherited ancestral and his acquired substrata. It is not argument addressed to the understanding, not the dry 'light of knowledge, which brings about reform in belief; when a changed feeling has been engendered through an unconscious modification of temperament, either in the individual or through generations, the reform takes place, as a crystal forms in a saturated solution ; the conclusions of reason are accepted when the premisses are already embodied in the character or temperament. The con- scious is but a superficial wave moving over the silent depths of the unconscious. The way in which the will operates upon the character, or affects the ego, is indirectly by determining the circum- stances which subsequently gradually modify it; we may place ourselves voluntarily in certain conditions of life or submit ourselves to certain influences, but all the energy of the strongest will cannot then prevent some degree of modification of character by them cannot prevent an equilibration taking place. In any future act of will the altered character, or acquired nature, is expressed ; and while we, perhaps, all unaware of any change, strenuously uphold our constancy, a looker-on clearly perceives the difference.* What we by a mental abstraction call the * The quantity of effect produced upon character in the interaction between the individual and the medium in which he lives will differ vn] VOLITION. 447 ego> is in reality a combination in which are contained the residua of all former feelings, thoughts and volitions, a combination which is continually changing and becoming more and more complex. That it differs at different times of life, and in consequence of different external relations, those who uphold most zealously its so-called identity do unconsciously admit when they acknowledge that, by religious influence or otherwise, any one may be made " quite another man/' may be "converted," or be " regenerate." The will of Saul of Tarsus was not the will of Paul the apostle to the Gentiles, The conversion may take place gradually in conse- quence of the steady operation of suitable outer influence, or it may sometimes take place suddenly after a great cere- bral shock, of epileptic OF other nature. Whosoever re- flects upon his past life must look back upon scenes and events in it which stand so far apart from his present much in different cases. The character exhibits a life of its own, tending to its own development independently of the medium, of such potency in some instances that it makes circumstances conform to it rather than conforms to them, but in other instances so feeble that it is lost in the medium. We may compare the effect to what happens in certain experiments on organic nutrition and absorption. Bone is known to be formed by the cells of the internal layer of the periosteum. M. Oilier proved by experiments the autonomy of these elements : he took a portion of the periosteum with its in- ternal layer of young cells and transplanted it to a part of the body where there was no boue into the neck or under the skin of the back. The piece developed there and produced a bony formation. The elements thus exhibited a life of their own independent of the medium in which they were born and in which they were placed. But the influence of the medium was shown in their ulterior lot, for M. Phillipeaux observed that the new bone disappeared after a time, being absorbed. The proper activity of the elements yielded to the influence of the medium. M. Ranvier removed a metatarsal bone of a very young animal and grafted it under the skin of the back. It grew at first, but after a time was absorbed. At the same time a new metatarsal bone was formed in place of the one which had oeen removed. W 8 THE PHYSIOLOGY OF MIND. [CHAP. personality that they seem almost as alien from him as il they had happened to some one else ; he may feel a diffi- culty in realising that his present ego was concerned in them. Memory brings them back, but with very much of the feeling of fading reality which attaches to dreams that are past, the ego of them being so different from the tgo of now. When the ego is transformed in correspondence with changed external circumstances, the changes are so gradual as to be imperceptible at the time ; but a rapid transformation of the ego may sometimes be effected by a great event, internal or external, as, for example, when, at the development of puberty, new ideas and im- pulses penetrate the old circle of thought, and become constituent parts of it, producing no little subjective dis- turbance until the assimilation is completed and an equilibrium established. When a great and sudden revolution in the ego is produced by an external cause, it is full of hazard to the mental stability of the indivi- dual, and very apt to become pathological : nothing is more perilous to the equilibrium of a character than for any one to be placed in entirely changed external cir- cumstances without his inner life having been gradually adapted thereto ; and madness, when its origin is fairly examined, always means discord between the individual and his circumstances.* * Dr. Channing, in a sermon On the Evil of Sin, speaking of the absurdity of the notion that in changing worlds there will be a change of character, says : " In the first place, it contradicts all our experi- ence of the nature and laws of the mind. There is nothing more striking in the mind than the connexion of its successive states. Our present knowledge, thoughts, feelings, characters, are the result of former impressions, passions, and pursuits. We are this moment what the past made us ; and to suppose that, at death, the influences of our whole past course are 1o cease on our minds, and that a character is to spring up altogether at war with what has preceded it, is to suppose the most important law or principle of the mind to be violated, is to destroy all analogy between the present and future, vii.] VOLITION. 449 The history of a man is plainly the truest revelation of his character ; for what he has done indicates what he has willed ; what he has willed marks what he has thought and felt, or the character of his deliberations and feelings ; what he has thought and felt has been the result of his nature then existing as the develop- mental product of a certain original construction and a definite life experience. Objectively considered, the identity of the ego is neither more nor less than the identity of the full-grown oak with the first slight shoot from the acorn : subjectively considered, the strong and sure conception which each one has of the ego is not surprising, inasmuch as it is the most frequently active idea, being concerned with more or less consciousness in every event of his life, being that to which every action has fundamental reference. The fashioning of the will is the fashioning of the character ; and this can only be done indirectly by fasohining the circumstances which determine the manner of its formation. But, however formed, it is the character which determines what the inclination shall prompt as most desirable, the judgment decide to be most eligible, and the will carry into effect If it were possible for any one to enter thoroughly into the inmost character of another person, and to become exactly acquainted with the moving springs of his con- duct in his particular relations of life, it would be possible not only to predict his line of action on every occasion, but even to work him, free will notwithstanding, like an automaton, by playing on his predominant passions, interests, or principles. Secondly, there is manifestly required for the free and to substitute for experience the wildest dreams of fancy. In truth, such a sudden revolution in the character, as is here supposed, seems to destroy a man's identity. The individual thus transformed can hardly seem to himself or to others the same being. It is equiva- lent to the creation of a new soul." o THE PHYSIOLOGY OF MIND. [CHAP. action of will an unimpeded association of ideas, so that the due materials for the formation of a sound judgment may be available. But the ease, completeness, and character of such association depend, as already shown, on the condition of the nervous element, very slight dis- orders of which accordingly quickly declare themselves in a deterioration of the will. The person who has long addicted himself to alcoholic excesses, or to the habitual use of opium, or to some other pernicious vices, initiates a degeneration in the intimate elements of nervous struc- ture, which, though we cannot yet detect its nature by microscopic observation, declares itself distinctly in a deterioration of moral sense and a pitiful enervation of will ; and if the degeneration increase, the further depra- vation of will is shown by the loss of co-ordination of mental functions. As the secondary automatic faculties of the spinal centres soon suffer from any disorder of nerve element, and reveal their suffering in the loss of co-ordinate power over the movements, so in the loss of co-ordinating power over the ideas and feelings, in their irregular and independent reactions, is revealed the deterioration of the will. And as, when the disorder of the spinal centres is still greater, all co-ordination is lost and convulsions ensue ; so in the supreme gangli- onic cells of the hemispheres, when the disturbance is great, there is no co-ordination of the thoughts and feelings, convulsive reactions of the cells take place, and the individual is a raving lunatic, or a dangerous one dominated by a few persistent morbid ideas. Volition is, as it were, resolved into the inferior constituents out of which it is in the due course of things compounded, as a ray of white light may be decomposed into several coloured rays; and in place of the definite, calm, co- ordinate activity of well-formed will, there is the aimless, irregular, explosive display of inferior activity. It is obvious, however, that even in the sound mind the vi L] VOLITION. 451 quantity and quality of the volition depend upon the fulness of the reflection, and that any hindrance to the due association of ideas will pro tanto affect the will : if the particular volition were to be resolved by a retro- grade metamorphosis into its component elements there would be an explication or unfolding of all the ideas and desires which had gone to form it ; and going still fur- ther back in the analysis, there would be a revelation even of those particular relations in life which have helped to determine the individual's definite organiza- tion of ideas, the character of his ego. It will be proper, before finishing with the considera- tion of the will, to say something more special con- cerning the relations of the emotions to it than I have done in pointing out that the dynamic impulse is derived from the affective life. If an active emotional idea reacts to its stimulus directly in outward action, as its tendency is, it so far weakens the will ; duly controlled and co- ordinated in reflection, as is the case after a right mental cultivation, it strengthens the will. Before many ideas have been acquired, and their multitudinous associations fixed, as in the young child ; or where the state of the development of the brain precludes intellectual develop- ment, as in the idiot and in the animal, the emotions excited immediately expend their energy in outward manifestation ; and when in the cultivated adult there exists, from some cause, an unstable condition of nerve element, or when the tension of the emotion or passion is exceedingly great, it will also react directly outwards in spite of the will : the law, admitting this, would count it therefore no great crime for a husband to kill a man whom he surprised in the act of adultery with his wife. But whosoever takes careful note of his own mental states may call to mind occasions on which a suddenly excited emotion prompted strongly a particular action, which he nevertheless withstood for an instant, 452 THE PHYSIOLOGY OF MIND. [ciur. and might, if necessary, have forborne altogether ; but perceiving, with quick intuition, that he might do well to manifest the emotion, he afterwards allowed the action to take place. The looker-on, perhaps, sees only an im- pulse and rashness ; and yet the rashness was in some sort deliberate an indiscretion which served the end when wiser plots might have failed. Emotion was the real motive force, but it was emotion acting under the direction of reason, and, therefore, in accordance with prudent insight into the external relations. The indi- vidual might have done the same action in obedience to a calm resolution of the will, and better so, perhaps, if he had been operating upon inanimate objects ; but in dealing with men it may sometimes be that a prudent exhibition of feeling much aids the success of the ends designed. Only let a man beware that, however he impose upon others, he deceive not himself by his pas- sion, by allowing it to obscure his reason and pervert his judgment : restrained within the supreme centres, it is apt to do that in all minds, and sure to do so in weak minds ; but, duly subordinated and co-ordinated in re- flection, it adds force to resolution. Restrained passion, acting under the calm control of reason, is verily a most potent force ; it gives a white heat, as it were, to the ex- pression of thought, an intensity to the will. An emotional person who is literally an explosive person certainly often produces great effects in the world, and especially such effects as are destructive of some existing system or belief; it is, indeed, commonly their great self-feeling that gives to the reformers their abandon- ment, energy, and consequent success. But an evil often outweighing these advantages is that there is no guarantee that they are right ; for, necessarily one-sided, they see but a part of a truth that part which affects their self- hood most keenly. The history of human labours and failures furnishes many examples which teach how a great vii.] VOLITION. 453 principle has suffered seriously from the hasty, violent, and ill-considered action of its sincere and earnest ad- vocates : adverse events or circumstances, which they in the torrent of their passion could not recognize, but which, as rational beings looking to the operation of causes, it behoved them to have recognized, have swept them away, and the truth which they upheld has been for a while the victim of their indiscretion. As in the mental phenomena of the individual the power of reflection is often best exhibited in the prevention of action prompted by feeling in an inhibitory function ; so amongst men in the social state the power of a good understanding is sometimes best shown by not pressing hotly forward an immature reform. But it is a very hard matter for a reformer who feels strongly to perceive that what is theoretically desirable and right may also practically be undesirable and wrong under existing social conditions ; he is apt to treat adverse circumstances as if they were accidents or anomalies in nature, having no right of existence, and thus more or less wilfully shuts his eyes to the force of events on which he proposes to operate, and which will, in any case, operate upon his principle. He hurls a favourite principle, which maybe a very just one, into the world not sufficiently prepared for it, not having reached the due level of its evolution, and which, there- fore, is necessarily hostile to it ; and if his truth is op- pressed and seemingly extinguished by the opposition which it meets with, then he is disheartened and com- plains, or is angry and rails. However, it is not nature which is wrong, if there be any wrong, but himself the reformer. The fact that he did not succeed proves that he did not deserve to succeed ; he has not rightly estimated the character and weighed the force of cir- cumstances which have been too strong for his truth, and by a simple law of nature have, for a time at least, quenched its light. 454 THE PHYSIOLOGY OF MIND. [CHAP. A great advance can never be superimposed upon people miraculously; in order to be genuine and last- ing, it roust be a natural evolution from pre-existing events must grow out of them ; and that which most effectually demolishes an old error is not a passionate attack upon it by the intensely feeling reformer, but a new and better creation, which quietly undermines it and takes its place. It is one good function of the conservative instinct in human nature, by withstanding change, to prevent reform taking place until the new has absorbed that which is good in the old to constrain re- volution to be evolution. Creation is a far higher order of work than destruction ; it is the quiet, self-contained activity of definite productive aim in other words, of will in its highest development as opposed to the ex- plosive and dissipated display of an inferior and mostly destructive emotional force. But as the calm intellectual contemplation of events, viewing all the relations of them, is attended with no great spur to any particular activity, but marks an equilibration between the indi- vidual and his environment, it is easy to understand how excellent a thing to put the will in active motion, in a particular case, is a passionate feeling or desire of good to be attained or of ill to be shunned, in order to establish an equilibration. Then the will, enlightened by an adequate reflection upon all the co-operating con- ditions, is able to act with a calm, steady, intelligent and potent energy. However, as emotion is strongly infectious, running like an epidemic sometimes through multitudes of people, it is impossible to foresee with certainty what effect the emotional man may or may not produce ; he sometimes raises a storm of agitation which sweeps all before it, when reason looking calmly at the circum- stances would prognosticate a fruitless labour. The difference in quality and immediate energy be- tween the will which is urged by strong desire and the vii.] VOLITION. 455 will which proceeds from a calm and full reflection, is strikingly evident in the character of the work done by two kinds of reformers. Surveying the men who have exercised great effects on the progress of mankind in this capacity, they appear broadly divisible into two classes : the men of wide intellectual grasp, vast know- ledge, serene feeling, and calm energy, and the men of limited vision, intense feeling, and impetuous energy the extensive or many-sided, and the intensive or one- sided men. The fonner, taking a comprehensive survey of events, seeing in them the simple operations of na- tural law, recognizing the character and the import of existing relations, and the true value of the present question, which is often exaggerated by its immediate urgency, have their feelings subordinated to their reason, and do not abandon themselves to an unrestrained im- petuosity. They may do great work, but they do it, not like lightning, rapidly and tumultuously, but like light, slowly, quietly, and silently ; their work is con- structive, not destructive ; they are reformers of opinion rather than of practice; and the fertilizing influence of their thought is felt through many generations. The latter, on the other hand, are possessed with a conviction so tremulous with intense self-feeling that it seems the one important thing in the world, and they are more or less blind to everything else ; they put all their energy into explosive action, which, like lightning, is destructive; they are iconoclasts who beat down furiously the idols that are worshipped in order to set up others in their places ; they are reformers of practice rather than of thought ; and though they often effect a great imme- diate practical result, they have little or no fertilizing influence upon the intellectual development of the future. The earnest desire which inspires their energy springs from a basis of strong self-feeling. The most perfect display of will involves the full agree- 156 THE PHYSIOLOGY OF MIND. [CHAP. ment of all the powers and dispositions of the mind, and is the expression of their complete co-operation. If there be any want of harmony between them, any feeling or thought which does not work in entire consent with the rest, holding back like a stubborn horse in a team, or inclining to deviate from the track like a wilful one, the act of will loses so much vigour thereby ; it is no longer, as it were, the complete union of coloured rays into one ray of pure white light, but is partially broken up into dissentient forces. In postulating this complete har- mony of the mental functions, we necessarily postulate at the same time that complete harmony of the bodily functions which is perfect health ; so that the highest display of will is the expression of the most perfect health of mind and body. In order that the will on all occasions may reach, as near as possible, this height of excellence, it is obviously necessary that care should be taken to maintain the body in the best health, and so habitually to fashion the mental character in relation to the circumstances of life that it shall be itself a complete harmony ; that on no occasion shall passion incline where the judgment approves not, or conflicting passions distract the mind, or inclination prompt what conscience condemns; that always the whole energies of being shall consent in the will. Without doubt, will is the highest force which Nature has yet developed, the last consummate blossom of all her marvellous works. The natural product of desire illuminated by the highest and completcst reflection, it represents the exquisitely and subtly adapted reaction of man to the best insight into the relations in which he moves. Hence the vast power of the human will wit- nessed in the lives of those eminent men of practical genius who have exhibited its highest evolution. They were in harmony with the current of events among which they lived ; co ordinating in themselves the forces vii.] VOLITION. 457 that were at work around them, they accomplished what the world had at heart in that age. Thus the force which they displayed was a force not their own ; the power of the universe was behind them, and they became the organs of its manifestation. Beneath them were " the everlasting arms." If we reflect upon the way in which the social and intellectual forces of an age are thus co- ordinated in the work of genius, and again upon the manner in which the actions of the different nerve- centres of the body are subordinated and co-ordinated in the manifestation of will, how there are, as it were, in both cases, a gathering together and a concentration of different forces into one definite mode of action, a unifying of their energies, we may be able to form a conception, by help of what we can thus observe, of the mode of that exaltation or transpeciation of force and matter throughout, nature which we cannot follow through its inmost processes.* By the power of a well-fashioned will man reacts with intelligent success upon the external world, brings himself into a complete harmony with its surroundings, assimi- lates and incorporates nature, and thus carries forward its organic evolution : he realises practically that there are not two worlds, a world of physical nature and a world of human consciousness, standing over against one another, but that there is one world of nature whereof his con- scious life is an event The highest action of the will is therefore truly creative, for in it is initiated a new develop- ment of nature through man ; it adumbrates the possibili- ties of mankind, as a rudimentary organ in a lower species of animal foretells obscurely the higher species in which it will have full development. If we ask whence comes the impulse which displays itself in this upward nisus, we can only answer lamely that it comes from the same un- * Transpaiation is a word used by Sir Thomas Browne which might be found useful at the present day. 458 THE PHYSIOLOGY OF MIND. [CHAP. fathomable source as the impulse which inspires or moves organic evolution throughout nature. He who reflects upon himself and upon the universe is forced in the end to the recognition, in the workings of the world, of a power from which all life and energy proceed, which has been from the beginning, is now, and, so far as we can see, ever shall be, and which cannot be comprehended and controlled by human thought and will, but comprehends and controls human thought and will. We recognise an impulsion outside ourselves, working also in our wills, which is the moving energy of the evolution which went on through countless ages before man appeared upon earth, which is going on now in his progress, and which will doubtless go on through countless ages after he has ceased to replenish the earth and subdue it We come back indeed to something which, however we name it, or forbear to name it, is very like the theological Trinity God the Unrevealed and Unrevealable, God the Revealed, and God the Revealer. In human thought and will nature has arrived at self-consciousness, but the power which impels the highest evolution of life, as mani- fested in the highest reach of human thought and will, is fundamentally the same power as that which impels the evolution of the lowest forms of life. For man to seize upon this power as it works in him, to divorce it from the rest of nature, to look upon it as supernatural ly infused and designate it free-will, and thereupon to base claims for himself not only to a rank infinitely higher than, and to a destiny entirely different from, that of anything else in the universe, but to be the end and purpose of creation, may be set down as a proof that nature, having reached self-consciousness, is, like a youth at the corresponding stage of development, afflicted with an insufferable conceit vii.] VOLITION. 459 NOTES. 1 (/. 416). Jonathan Edwards asserts that there is no difficulty in showing, by attention to our own experience, not only that the will must be influenced in its choice by something that has a prepon- derating influence upon it, but also how it is so : " Thus, supposing I have a chess-board before me ; and because I am required by a superior, or desired by a friend, or to make some experiment concerning my own ability and liberty, or on some other consideration, I am determined to touch some one of the spots or squares on the board with my finger ; not being limited or directed in the first proposal, or my own first purpose, which is general, to any one in particular ; and there being nothing in the squares, in themselves considered, that recommends any one of all the sixty- four more than another ; in this case my mind determines to give itself up to what is vulgarly called accident,* by determining to touch that square which happens to be most in view, which my eye is especially upon at that moment, or which happens to be most in my mind, or which I shall be directed to by some other such like acci- dent. Here are several steps of the mind's proceeding (though all may be done as it were in a moment) : the fast step is its general determination that it will touch one of the squares. The tuxt step is another general determination to give itself up to accident, in some certain way ; as to touch that which shall be most in the eye or mind at that time, or to some other such like accident. The third and last step is a particular determination to touch a certain in- dividual spot, even that square which, by that sort of accident the mind has pitched upon, has actually offered itself beyond others. Now it is apparent, that in none of these several steps does the mind proceed in absolute indifference, but in each of them is influenced by a preponderating inducement. So it is in the first step ; the mind's general determination to touch one of the sixty-four spots : the mind is not absolutely indifferent whether it does so or no ; it is induced to do it, for the sake of making some experiment, or by * I have elsewhere observed what that is which is vulgarly called accident ; that it is nothing akin to the Arminian metaphysical notion of eontingence, something not connected with any thing fore- going ; but that it is something that comes to pass in the course of things, in seme affair that men are concerned in, unforeseen, and not owing to thtir design. 4&o THE PHYSIOLOGY OF MIND. [CHAP. the desire of a friend, or some other motive that prevails. So it is in the second step ; the mind's determining to give itself up to acci- dent, by touching that which shall be most in the eye, or the idea of which shall be most prevalent in the mind, &c. The mind is not absolutely indifferent whether it proceeds by this rule or no ; but chooses it because it appears at that time a convenient and requisite expedient in order to fulfil the general purpose aforesaid. And so it is in the third and last step ; it is determining to touch that individual spot which actually does prevail in the mind's view. The mind is not indifferent concerning this ; but is influenced by a prevailing in- ducement and reason ; which is, that this is a prosecution of the pre- ceding determination, which appeared requisite, and was fixed before in the second step " "As the acts of will, in each step of the fore-mentioned procedure, do not come to pass without a particular cause, every act is owing to a prevailing inducement : so the accident, as I have called it, or that which happens in the unsearchable course of things, to which the mind yields itself, and by which it is guided, is not anything which comes to pass without a cause ; and the mind, in being determined to be guided by it, is not determined by something that has no cause, any more than if it determined to be guided by a lot, or the casting of a die. For though the die's falling in such a manner be accidental to him that casts it, yet none will suppose that there is no cause why it falls as it does. The involuntary changes in the suc- cession of our ideas, though the cause may not be observed, have as much a cause as the changeable motions of the motes that float in the air, or the continual, infinitely various, successive changes of the unevenntss on the surface of the water." An Inquiry into the Modern preva ling notions of that Freedom of the Will which is sup- posed to be essential to Moral Agency, Virtue and Vice, Reward and Punishment, Praise and Blame, p. 67. 2 (/. 427). " Sixthly, the will appears to be nothing but a desire or aversion sufficiently strong to produce an action that is not auto- matic primarily or secondarily. At least it appears to me that the substitution of these words for the word will may be justified by the common use of language. The will is, therefore, that desire or aversion which is strongest for the present time. Since, therefore, all love and hatred, all desire and aversion, are factitious and gener- ated by association, i.e. mechanically, it follows that the will is mechanical also." HARTLEY'S 7'hcory of the Human Mind, p. 205. " Appetite, therefore, and aversion are simply so called as long as they follow not deliberation. But if deliberation have gone vii.] VOLITION. before, then the last act of it, if it be appeti'e, is called will ; il aversion, unwillingness. .... Neither is the freedom of willing or not willing greater in man than in other living creatures. For where there is appetite the entire cause of appetite hath preceded ; and, consequently, the act of appetite could not choose but follow ; that is, hath of necessity followed. And, therefore, such a liberty as i* free from necessity is not to be found either in the will of men or of beasts. But if by liberty we understand the faculty or power, not of willing, but of doing what they will, then certainly that liberty is to l>e allowed to both, and both may equally have it, whensoever it is to be bad." Hobbts, vol. i. p. 409. " The whole sum of desires, aversions, hopes, and fears, con- tinued till the thing be either done or thought impossible, is that we call Deliberation." Leviathan, vii. 8 (P- 436)' I extract the following remarks of Hume : 1. " But do we pretend to be acquainted with the nature of the human soul, and the nature of the idea, or the aptitude of one to produce the other? .... We only feel the event, namely, the existence of an idea, consequent to a command of the will. But the manner in which Ihis operation is performed, the power by which it is produced, is entirely beyond our comprehension." 2. " The command of the mind over itself is limited as well as its command over the body ; and these limits are not known by reason. .... Will any one pretend to assign the ultimate reason of these boundaries, or show why the power is deficient in one case, not in another ? " 3. " Self-command is very different at different times Can we give any reason for these variations, except experience? Is there not here, either in a spiritual or material substance, or both, some secret mechanism or structure of parts, upon which the effect depends, and which, being entirely unknown to us, renders the power or energy of the will equally unknown and incomprehen- sible?" 4. " The motion of our body follows upon the command of our will. Of this we are every moment conscious. But the means by which this is effected, the energy by which the will performs so ex- traordinary an operation ; of this we are so far from being imme- diately conscious, that it must for ever escape our most diligent inquiry." After explaining that volition does not act directly on a limb itself, but through certain muscles and nerves, through which the motion is successively propagated, he asks " Can there be a more certain proof that the power by which this whole operation is per- 21 462 THE PHYSIOLOGY OF MIND. [CHAP. vii. formed, so far from being directly and fully known by an inward sentiment or consciousness, is to the last degree mysterious and un- intelligible. Here the mind wills a certain event ; immediately another event unknown to ourselves, and totally different from the intended, is produced. This event produces another equally un- known ; till, at last, through a long succession, the desired event is produced." Inquiry contenting the Human Understanding. CHAPTER VIII. MOTOR NERVOUS CENTRES OR MOTORIUM COM- MUNE, AND ACTUATION OR EFFECT! ON. THUS far I have been engaged in considering the de- velopment of the mental organization, as it takes place in the production of simple or presentative ideas out of sensory impressions, with their associated motor reac- tions, that is, in apprehension ; in the production of representative ideas or conceptions by abstraction from the simple ideas, that is, in comprehension ; and in the production of volition as the result of the complex inter- working of desires and conceptions. But it is not man's function in life merely to think and feel ; his inner life he must express or utter in action of some kind. In all animals there is an instinct or impulse to perform move- ments, either spontaneously or in answer to conscious and unconscious stimuli; for bodily exercise is necessary to the procuring of food, to the preservation of health, and to defence against their enemies. When there is no exercise of the proper movements, sensations of discomfort and restlessness are produced which impel the animal to per- form movements in order to obtain relief from the discomfort which is felt, and to procure the agreeable sensations which will follow activity. After exertion there is an instinct for repose ; the energy stored up by nutrition in the nervous centres having been spent, and requiring renewal. The instincts to movements in 464 THE PHYSIOLOGY OF MIND. [CHAP. the different organs with which animals are thus furnished to fulfil the ends of their life produce the habits and actions of their so-called animal life, and the movements are really complex manifestations of sensori-motor action. Just as centripetal and centrifugal nerve fibres united by nerve cells and commissural fibres are the simple elements out of which the complicated structure of the nervous system is built up, so sensation and motion are the simple functional units from which the complex mental processes are evolved. The natural consequence of a sensation is a movement, which follows necessarily, unless it be inhi- bited, or unless it be transformed into an equivalent activity, as happens when its energy is expended in acting upon the blood-vessels and affects secretion and nutrition. It is evident then that there are other residua besides those which have already been specially dealt with, which enter as constituents into his mental life the residua, namely, that are left behind by movements or actions. The movements that are instigated or actuated by a particular nerve centre do, like the ideas, leave behind them their residua, which, after several repetitions, be- come so completely organized into the nature of the nerve centre that the movements may henceforth be automatic. There is then, intervening between the volitional impulse and the action, a department or re- pository of motor residua, in which exist the immediate agents of movements a region, psychologically speaking, of abstract, latent, or potential movements. If recourse be had to physiology, it is found that, conformably with what psychological analysis teaches, there are numerous special motor nervous centres, or nuclei of ganglionic cells, cerebral and spinal, from which motor nerves pro- ceed, and by the experimental irritation of which move- ments may be artificially excited. These motor centres have their special connections, by means of internunciant VIM.] MOTOR NERVOUS CENTRES. 465 fibres, with regions of the anterior convolutions of the brain, so that, as recent experiments have shown, the definite movements may be excited by stimulation of the cortical representatives. As the sovereign deals with his subjects through their representatives, so the will deals with movements through their representative centres in the convolutions. The term which I have taken leave to use for the purpose of designating, psychologically, the common centres of movement is the motoriutn commune. This region of motor residua, or, as I have ventured to call it, this motoriutn commune, is related to concep- tion on the reactive side of human life, as sensation is on the receptive side. As the. residua of sensorial acti- vity, as already seen, minister and are necessary to a definite representative conception, so the residua of motorial activity in their turn enter essentially into con- ception, and are indispensable to its realization in action. It may not be amiss, then, to take notice here, again, how the highest mental action comprehends or contains the whole bodily life. The sensory life enters essentially into conception ; the organic life, as previously set forth, participates in the emotional quality of it ; and the motorial activity of the body is essential to its exact definition and outward expression. How mischievously unjust, then, is the absolute barrier set up between mind and body ! How misleading the parcelling out of the mind into separate faculties that answer to nothing in nature ! What name may most properly be given to this neg- lected but important motorial region of our mental life ? The motor residua that mingle in our conceptions have been called, in Germany, motor intuitions or percepts (Bewegungs-anschauungen). This name is applicable only to those motor substrata that are concerned in voluntary movements those the functions of which 466 THE PHYSIOLOGY OF MIND. [CHAP. intervene between volitions and acts and which may be excited by stimulation of the cortical representative motor centres. But it must not be overlooked that the subordinate motor ganglia are the real motor centres, containing the organized faculties of the different move- ments, and that these may be excited to action by a sensational or reflex stimulus as well as by an impulse from the hemispheres. In this case it plainly would not be proper to speak of motor intuitions or percepts : it is only when the impression of the definite movement has been conveyed upwards to the frontal brain that the motor intuition is produced. The whole region of motor residua might be described generically as the department of actuation; a department containing the powers or faculties through which the nervous centres, when excited to activity, act upon the muscular system, and, by thus uttering or expressing their energies, restore the equili- brium between the individual and the environment. It contains the means by which will, idea, or sensation actuates definite movements, or prevents their occur rence. To give the name of locomotive faculty to this province of mind would land us in the inconsistency of denominating locomotive an agency which often acts to inhibit or prevent motion. However it be named, there can be no doubt that such a region of mental activity exists, and that in it are con- tained, fashioned and co-ordinated, the faculties of different groups and series of movements. It is easy to perceive why will can only determine the result when it dictates an act, and cannot determine the ac- tion of a particular muscle, or the combined actions of certain muscles which have not acted together before. All it does is to let loose, as it were, the proper agency in the motor centre; and this is done by willing the event, which it is enabled to do by means of the proper motor intuition. When I "will to utter a certain word, I vni.] MOTOR NERVOUS CENTRES. 467 will the event, the complex articulating movements being possible to me only through the medium of the proper motor intuition. The impulse plus the special motor intuition constitutes the particular volition. A voluntary movement is truly a reflex act in the cortical centres of Vie brain ; differing from the lower reflex movements in .hese circumstances first, that it does not immediately follow the stimulus, but is caused by the excitation of many associated sensory residua which have been laid up in consequence of former experiences ; and, secondly, that it contains or evinces a distinct adaptation to an end or purpose, by reason of the excitation of associated motor residua which have been organized effects of former adjustments. If the result wished is a new, unfamiliar one, no residua thereof from previous experiences exist- ing in the motor centres, then the will is unequal to the accomplishment of it ; there is not an exact and definite idea of the end to be effected, the necessary motor in- tuition being wanting. After repeated trials, the desired skill is firmly acquired, and the movement is thenceforth automatic, the motor intuition having been gradually organized in the proper nervous centres : the result stored up strictly corresponds with that which in other nervous centres we describe as abstract idea. It is pro- bable that the so-called motor centres in the cerebral convolutions are really the centres of these motor in- tuitions ; in other words, they are the centres in which the subordinate motor centres act upon consciousness, and they thus constitute the physiological agency of voluntary movements. In animals the motor intuitions, like their other facul- ties, are mostly innate. There are no distinct, clear conceptions accompanying their instinctive actions ; but obscure sensations and feelings excite the motor centres, which then determine the action of the proper muscles. In man, on the other hand, although the faculties of & THE PHYSIOLOGY OF MIND. [CHAP. certain co-ordinate movements do exist, preformed in the nervous centres, the motor faculties are mostly acquired ; in this regard corresponding with the formation of his other mental faculties. Our ideas of distance, size, and solidity furnish striking examples of the manner in which we are indebted to our motor intuitions, and of the dif- ference in respect of them between us and the animals. The young swallow's intuition of distance appears to be as perfect when it begins to fly as it is after a life-experi- ence ; but it is not so with the young child, which cannot for some time tell how distant or how near an object is. In the first instance, the child's body moves with the eyes, when these are fixed upon a light that is moved about before it After a few weeks the moving light is followed by a motion of the head only; next the eye-ball itself is turned also; and ultimately objects are followed with the eye without any motion of the head. As this is going on, a recognition of the position and distance of an object is acquired gradually, and the convergence of the axes of the eyes is seen to change regularly and quickly with the approach of the object to, or its removal from, the eyes. Now it is well known that the accommodation of the eyes to distance is effected, for near objects, by a con- vergence of their axes and an accommodation of their lenses, two actions which are from the first very firmly associated ; so much so that a congenital defect in the lens is now recognised to be the frequent cause of squinting in children. And it is quite possible, by expe- rimentally modifying, by the use of suitable glasses, the customary consentaneous convergence of the axes, to deceive perception and to cause it to be a false induction concerning the object It infers certain things from cer- tain movements, and when these are deranged it makes false inferences for a time. But these accommodating movements of the eye are not determined by any act of vtil.] MOTOR NERVOUS CENTRES. 469 will, nor are they within consciousness ; they are con- sensual movements in respondence to the visual sensa- tion, and strictly comparable with the instinctive move- ments of the animals. It is not the visual sensation directly which gives us the idea of intuition of distance, but the motor intuition of the accommodating movement in association with the visual impression, which, though uncertain and confused at first in man, soon gets precision and distinctness. And, after all, it gets this precision and distinctness in so short a time only because it inherits an anatomical mechanism which represents the accumulated experiences of countless ancestors : if the individual were obliged to acquire it himself from the foundations, all his life would not suffice for the work. In this example we have a type of that which happens, with greater or less rapidity, in the case of every movement in the body. The infant at first kicks out its leg whether from a so-called spontaneous outburst of energy, or by reason of some organic or of some external stimulus, matters not and bringing it in contact with some ex- ternal object, gets thereby a sensation, in respondence to which, as in the consensual accommodation of the eyes, adaptations of movements take place, and muscular intuitions are more or less quickly and completely organized.* There is a fusion of different local sensa- tions with different muscular feelings ; certain sensations and certain movements are thus associated, and the residua of the muscular movements, or the motor intui- tions, are henceforth essential constituents of our mental life, whether we are distinctly conscious of them or not. Consider, if further illustration be needed, the gradual * The innate mechanism soon comes into action, being in a state of waiting preparation, so to speak, to respond to the suitable stimulus. As Sir C. 15ell remarked, an infant evinces an apprehen- sion of falling while it is still in the nurse's arms. A young kitten will stretch its neck in search of the teat when it is only half born. 170 THE PHYSIOLOGY OF MIND. [CHAP. acquisition of the complex movements of speech, and the intimate connection which they have with the formation of our conceptions. We acquire articulate speech through imitation of the sounds of words ; the sensory residua of the sound of the word are associated by practice with definite muscular articulating move- ments ; the motor intuitions are thus organized in their proper centres ; and these motor intuitions may then be excited, and give expression to ideas, by stimuli pro- ceeding from the associated sensory residua of other senses than sound. Thus the sight, or touch, or taste of an object will excite the proper word without inter- vention of the auditory residua, when speech has been learned. A weak-minded person, or a person of low cultivation, often cannot content himself with the mental representation of a word, or clearly comprehend a ques- tion put to him, without bringing the actual movement to his assistance ; he must utter the word or repeat the question aloud, in order to get his conception distinctly. Education consists fundamentally in the association of certain definite sensory currents, excited by ex- ternal impressions, with certain definite motor currents, which are the adapted reactions of the individual to the impressions which affect him. No wonder then that we find so much automatic action when we look closely into the mental processes of men ; the whole aim of education on the part of one generation being to produce upon the next generation the same impres- sions which it has experienced, and to teach the same reactions which it has performed. It is most neces- sary, however, to guard against the strong disposition which there is to look upon certain movements, those of the eye and the tongue, as having a special connection with the mental life which other movements of the body have not ; they have a specially intimate connection, but not a special kind of connection. Unwarrantably sepa- viii.] MOTOR NERVOUS CENTRES. 471 rating by an absolute barrier the mind from the body, and then locating it in a particular corner of the latter, as is commonly done, we are prone to forget that in mental action the whole bodily life is comprehended that what is displayed outwardly exists in the innermost that every motor intuition has its essential place and influence in our mental life. It is not without instruction to note how very far the limit of possible utterance by speech is from being reached. Of the possible sounds which man is able to pronounce and distinguish a great variety is never made use of. " Each language or dialect of the world is found in practice to select a limited series of definite vowels and consonants, keeping with tolerable exactness to each, and choosing what may be called its phonetic alphabet." * In the different languages of the world there is an abundant variety of sounds, many of which are now used to express the same ideas, but which might, if need were, be used at some future time to express the new ideas and feelings which mankind will presumably acquire. Moreover, as Mr. Tylor has re- marked, there are many sounds capable of being used in articulate speech, such as varieties of chirping, blowing, hissing, whistling, &c., which no tribe is known to have brought into their alphabet. Meanwhile we are very far from having exhausted the resources of the English alphabet. It appears that if the combinations of the twenty-six letters of the English alphabet were free, " so that any letter could be indifferently sounded with any other, the number of words which could be formed with- out any repetition would be 2 26 i, or 67,108,863."! But as the formation of our vocal organs is such as to prevent us using the greater part of these conjunctions of letters, inasmuch as at least one vowel must be presenf * Tylor's Primitive Culture, vol. L p. 155. t Jevons's Principles of Science, vol. i. p. 197. 172 THE PHYSIOLOGY OF MIND. [CHAP. in each word and more than two consonants cannot usually be brought together, the actual number of avail- able words is 100,000; an ample store for the present, seeing that Shakespeare uses no more than 15,000, a person of ordinary cultivation between 3,000 and 4,000, and an agricultural labourer only about 300. In continuation of the foregoing exposition of the agency of motor residua in mental function, let me direct attention to their mental effects when they have been directly excited. In that condition which Mr. Braid called "hypnotism," it has been pointed out already that if the face or limbs of the patients are placed in an atti- tude which is the normal expression of a certain emotion, thereupon that emotion is actually excited; the motor intuition immediately awakening the appropriate con- ception. This is in accordance with what we frequently observe in watching the genesis of mind in young chil- dren, where it is plain that an attitude or gesture, uncon- sciously or involuntarily evoked, sometimes awakens iu the mind the correlative idea or emotion, and where, on the other hand, every thought is immediately translated into some movement.* It was taken notice of by Mr. Burke that when the body is disposed by any means whatsoever to such emo- tions as it would acquire by means of a certain passion, it will of itself excite something very like that passion in the mind. And he relates in confirmation a curious story told of the celebrated physiognomist Campanella : " This man, it seems, had not only made very accurate observations on human faces, but was very expert in mimicking such as were any way remarkable. When he had a mind to penetrate into the inclinations of those he * Vulpian (op. cil. p. 290) formularizes the general physiological law, that every excitation of a nerve, at any point in its length, is transmitted immediately and simultaneously both in a centripetal and centrifugal direction. vi I1.J MOTOR NERVOUS CENTRES, 473 had to deal with, he composed his face, his gesture, and his whole body, as nearly as he could, into the exact simili- tude of the person he intended to examine ; and then care- fully observed what turn of mind he seemed to acquire by this change. So that, says my author, he was able to enter into the dispositions and thoughts of people as effectually as if he had been changed into the very men."* Let any one make the experiment of fixing the coun- tenance in the expression of a certain passion, and, while retaining that expression, of trying to call up in the mind a quite different passion ; he will find it impossible to succeed until he alters the expression of his face. It may be remarked in this relation that these physiog- nomical expressions of the emotions are not really invented by the emotions which they express. The physiological mechanism which subserves them is innate in the indi- vidual, having been inherited by him as heir of the organized experiences of the race ; wherefore the mus- cular expression of a passion is uniform in different per- sons, and may be excited into action before the feeling of which it afterwards seems to become a necessary part. The smile on an infant's cheek, which in after years cor- responds with pleasurable emotions, is, as Sir C. Bell remarked, oftenest first seen when it is asleep, and is ascribed by the sage nurse to internal convulsions or irritation. Here the definite muscular action precedes the development of the mental state with which it is afterwards firmly associated. One observes the same thing sometimes on the face of a dying person, when the * Essay OH the Sublime and Beautiful, p. 261. "I have often observed," he says, "that on mimicking the looks and gestures of angry, or placid, or frightened, or daring men, I have involuntarily found my mind turned to that passion whose appearance I en- deavoured to imitate ; nay, I am convinced it b hard to avoid it, though one strove to separate the passion from its correspondent gtslures." 474 THE PHYSIOLOGY OF MIND. [CHA?. flitting smile, which might at the first glance seem to denote a happy thought, or the frown which would seem to mark a painful thought, is plainly the passing effect of some internal irritation. Here the special action of the features has survived the decay of the conscious state. I pointed out in a former chapter how essential a part the internal organs of the body play in the produc- tion of the passions, and how probable it is that the uniformity of passions among mankind is due to the uniform operation of these organs upon the brain ; it is now seen that the motor expressions of the passions may be produced by stimuli from the internal organs before the development, and after the extinction, of the con- scious mental states ; the question, then, may fairly be raised whether the development of the conscious mental state is not in great measure owing to this sensori- motor activity of the organic life. When, for instance, the infant, immediately after its birth, performs the movements of sucking as a purely reflex operation, it is presumed to have no more conscious feeling of the act than the anencephalic infant which does the same thing; but is it not probable that the operation awakens in its mind by degrees the appropriate conscious state, the current of sensori-motor activity exciting centripetally its representative current in the convolutions, and that it acquires by this means the knowledge and the feeling of pleasure which are afterwards associated with the con- scious gratification of the appetite for food ? At an early period, when the feeble muscles of the arms and legs can hardly make a few indefinite movements, the muscles of the face, Cabanis has remarked, already express, by dis- tinct movements, nearly all the series of general feelings peculiar to human nature, so that the attentive observer easily recognises in the picture the characteristic traits of the future man. It is, he says, not in external impressions that the causes of such complicated movements are to be via.] MOTOR NERVOUS CENTRES. 475 found, for, with the exception of touch, the senses hardly exist ; it is in internal impressions, in their simultaneous concurrence, in their sympathetic combinations, that we find the source of this language of the physiognomy. The condition of disease known as aphasia, which has been so much studied during the last few years, is espe- cially interesting in its bearing on the doctrine of motor intuitions. A person loses the power of expressing his thoughts by articulate language, understanding all the time perhaps what is said to him ; and although in the majority of cases in which this happens there is hemi- plegia of one side, generally of the right, there may be no paralysis at all. Moreover, in those cases in which there is hemiplegia, there is not any paralysis of the muscles of articulation ; the loss of speech is not due to any defect in the actual instruments of utterance ; nor is the loss of power of intelligent expression by speech owing in all cases, or entirely in any case, to the loss of intelligence, though it is certainly true that there is in many cases of hemiplegia some degree of mental failure some degree of enfeebled intelligence and of emotional excitability. Intelligence, however, often fails or is lost without loss of the power of speech; and we certainly meet with occasional instances of the latter defect with- out any appreciable loss of intelligence instances in which the patient is able to communicate his thoughts by gesture-language, or by writing. It is to be borne in mind, in regard to this question, that language consists essentially in the establishment of a definite relation between the idea and the sign by which it is outwardly manifested; that it may be verbal, vocal, graphic, or mimic ; and that the general faculty of language includes all these modes of expressing the thoughts. The per- sistence of one or more of these other modes of expres- sion, where the faculty of speech is lost, proves that, notwithstanding the intelligence is most probably weak- 476 THE PHYSIOLOGY OF MIND, [CHAP. ened in most cases of aphasia, it is certainly not then weakened to such an extent that the loss of speech can be due to the abolition of ideas. It may happen in some cases that the power of speech is not entirely lost, the person making use of wrong words, either conscious or unconscious that he is doing so ; in other cases, that he can make an apt emotional ejaculation under the influ- ence of excitement when he is quite unable to speak his thoughts. Where, then, does the immediate mischief in aphasia lie ? The first movements of speech which a child makes are made in imitation of the sounds which it hears ; they are of a reflex nature, and are executed by means of those parts of the pons and the medulla to which the auditory nerve goes the nuclei of the facial, the vagus, and the hypoglossal nerves, which are in anatomical con- nection with the nucleus of the auditory. They are a development, so to speak, of the inarticulate cry which the new-born infant makes; itself a muscular action which implies the combined action of the expiratory muscles and of the muscles which narrow the rima glottidis. When in due time the definite co-ordinate movement of a word has been executed as a reflex act of the auditory nerve and the proper associated motor nuclei, it is echoed, as it were, in the higher representa- tive centres in the convolutions, through the agency of the intercommunicating fibres which make the special connections between the lower and the higher centres the scnsorial and the ideational arcs. By repetition of this centripetal action the perceptive residua of the special sound are formed in the proper sensorial or afferent centre of the convolutions, and the associated motor residua of the special movements which effect its utterance are formed in the proper motor or efferent department of the convolutions ; so that when the word is afterwards uttered voluntarily the stimulated sensory VIIL] MOTOR NERVOUS CENTRES. 477 residua in the former excite the motor intuitions in the latter centres, which thereupon act centrifugally upon the motor nuclei. It is reflex action in higher centres along the ideational arc. This being the probable physiological mechanism of voluntary speech, we can easily perceive that disorder or loss of the function may be produced in more ways than one. If the continuity of a person's auditory nerve be interrupted, he will be deaf: deaf only, if residua of vocal sound have been stored up before he became deaf; deaf and dumb, if he was deaf before such residua had been acquired, that is, if he was born deaf. If the perceptive centres of the auditory nerve in the convolutions were clean cut out artificially, or entirely destroyed by disease or injury, all names would vanish from his memory ; he would not be able to understand or to repeat voluntarily a word spoken to him. It is conceivable, however, that he might even under these circumstances occasionally repeat a word as a reflex or sensori-motor act if the auditory nucleus and its motor connections were uninjured. Moreover, he would not be without ideas, forasmuch as having still the residua of the perceptive centres of the other senses of taste, touch, sight, his ideas might be excited through these, and might even be uttered in speech by means of their action upon the proper motor residua. Hearing is necessary to learn to speak, as men do learn speech, but once speech has been learned, it may be excited by the action of other sensory residua which have been asso- ciated with its motor residua. His mind would be an utter blank when the name of an object was spoken to him, but he might recognise the object and utter its name when it was shown to him, or might know it ihrough touch when it was put into his hands. If the connecting fibres between the auditory centres in the convolutions and the associated motor residua 178 THE PHYSIOLOGY OF MIND. [CHAP. in the frontal convolutions were destroyed, the person would understand everything said to him, and might certainly be able to speak freely, his motor residua being unimpaired, but he clearly could not make the connections between the sensory residua of sound and their proper motor residua. He could not select the right word through sound, although he might be per- fectly conscious of his mistake if he used a wrong one, and would certainly be able to stimulate the right motor residua through the perceptive centres of the other senses. If the motor residua of speech in the frontal convolutions were entirely destroyed, the person, while understanding what was said to him, would not be able to speak a single word voluntarily ; he could neither repeat voluntarily a word spoken to him, nor name an object placed before his eyes or made to affect any other sense, although it is possible that he might sometimes utter a word as a reflex sensori-motor act through the agency of the auditory nucleus and its motor connec- tions. It may be supposed that the result of destroying the nerves connecting the motor arrangements in the frontal convolutions with the subordinate motor ganglia would, so far as speech was concerned, be the same as that which would follow the destruction of the motor arrangements in the convolutions. Looking to these different ways in which injury to the anatomical substrata of speech may affect its function, and bearing in mind that the injury will seldom be of so defined a character as that which has been assumed for illustration in the supposed cases, we shall not be surprised to witness the varying phenomena which are actually met with in dif- ferent forms of aphasia. As will easily be understood, the difficulty is to observe accurately in a given case the exact nature and extent of the deficiencies which the person presents. I am inclined to think that the intelligence is often viii.] MOTOR NERVOUS CENTRES. 479 more deeply affected in aphasia than is supposed by on- lookers, and than the patient himself is apt to believe. Reflecting upon the important, indeed the essential, part which the motor intuitions play in the mental life, it is hard to conceive how the loss of them can take place without secondary injury to the ideational functions to the intelligence ; this may not be primarily affected by the disease, but it cannot fail to suffer secondarily. Is it possible to think definitely and consecutively without that power of internal representation which we have in the motor intuition, and which, in thinking, stands for the outward utterance ? * We may think, it is true, of con- crete perceptions, but can we pursue a train of abstract thought ? Even though the aphasic patient may not be himself aware of any mental failure, and may feel con- vinced that it is only the words to express his ideas that he lacks, yet it is not unlikely that his condition resembles somewhat that of a person in a dream, who fancies that he is thinking most logically, and discoursing most elo- quently, when his thoughts are confused and his words incoherent. The history of cases of aphasia proves that this is certainly so sometimes. It is easy to comprehend the disputes which arise among on-lookers who endea- vour to test the intelligence in these cases : when the regular channel by which intelligence expresses itself is closed, it must obviously be very difficult to appraise accurately the degree of intelligence. The simple ques- tions which are usually put, for this purpose, to aphasic patients certainly do not decide the question : a * " Herein lies the necessity of utterance, the representation of thought," says Heyse. "Thought is not even present to the thinker, till he has set it forth out of himself. Man, as an individual endowed with sense and mind, first attains to thought, and, at the same time, to comprehension of himself, by setting forth out of himself the con- tents of his mind ; and in this his free production, he comes to the knowledge of himself, his thinking 'L* He comes first to himself in uttering himself." 480 THE PHYSIOLOGY OF MIND. [CHAP. demented person, whose mental faculties were almost abolished, might answer sensibly when he was asked so commonplace a question as what he would do if the room were on fire ; and many patients in lunatic asy- lums whose intelligence is in a very shattered state are able to play cards and draughts skilfully. It is certainly quite possible for an aphasic patient to evince intelligent appreciation of simple questions and obvious suggestions when he has lost all power of sustained and definite thought. And, apart from all theoretical considerations, the evidence which exists at present is in favour of the opinion that the intelligence is often weakened in aphasia. There is one observation more to be made before pass- ing from this subject Some writers are in the habit of affirming that it is in names we think, and that they are the indispensable instruments of thought " I there- fore declare my conviction," says Max Miiller, " whether right or wrong, as explicitly as possible, that thought in one sense of the word, i.e., in reasoning, is impossible without language." Assuredly this sounds too absolute a statement Is not the deaf and dumb man a living refutation of the proposition that man cannot reason without speech ? The example of Laura Bridgman, who was deaf, dumb, and blind, as her case is admirably described by Dr. Howe, proves that a person may have human thought without being able to speak ; and the instances of aphasic patients who can express their ideas in writing point in the same direction. But neither these instances, nor the case of Laura Bridgman, can be used to prove that it is possible to think without any means of physical expression. On the contrary, the evidence is all the other way. The deaf and dumb man invents his own signs, which he draws from the nature of objects, seizing the most striking outline, or the principal move- ment of an action, and using them afterwards as tokens viii.J MOTOR NERVOUS CENTRES. 481 to represent the objects.* The deaf and dumb gesticulate also as they think, and Laura Bridgman's fingers worked, making the initial movements for letters of the finger- alphabet, not only during her waking thoughts, but in her dreams.f If we substitute for " names " " the motor intuitions," or take care to comprise in language all the modes of expressing thoughts, whether verbal, vocal writing, or gesture-language, then it is unquestionable that thought is impossible without language. In man the tongue has been almost exclusively appropriated for the expression of thought, but there is no absolute reason why his fingers, hands, and arms might not be used, like the antennce of ants, and the hands and fingers of the deaf mute, to express all the results of mental action. * " And whilst he silently elaborates the signs he has found for single objects, that is, whilst he describes these forms for himself in the air, or imitates them in thought with hands, fingers, and gestures, he develops for himself suitable signs to represent ideas, which serve him as a means of fixing ideas of different kinds in his mind, and recalling them to his memory. And thus he makes himself a language, the so-called gesture-language (Geberden-sprache) ; and with these few scanty and imperfect signs, a way for thought is already broken, and with his thought as it now opens out, the language cultivates and forms itself further and further." Many artificial signs are added by teachers to enrich the language. Krue, Uber Taubstummen, 1853. He was a learned deaf mute, who is quoted by Mr. Tyler in his Early History of Mankind, p. 20. f" Tyler's Early Ifistorv of Mankind, p. 70. And even to communicate such results by touch without the help of sight. In a Report of the Massachusetts Asylum for the Blind, Dr. Howe relates that a blind child, during the vacation, contracted St. Vitus's dance. When the school reassembled, another child soon manifested the disease, and soon afterwards a third. It was necessary to send these children home in order to prevent the whole school being infected through the imitative tendency. They soon recovered after separation. As the children were blind, it was not through sight that they were infected ; but a knowledge and imitation of the disordered movements were acquired by close con- tact of the children with one another at their school-desks, in their sports. &c. 482 THE PHYSIOLOGY 01-' MIND. [CHAP. The reasons why the tongue has been specially selected for this purpose are obvious : first, because of its con- nexion with the vocal organs, whereby its movements, in conjunction with those of the lips, modify in a great variety of ways the different sounds, and thus make audible language, which is plainly on the whole more useful to man than visible language, for it would be extremely inconvenient if one person could not com- municate with another without seeing or touching him ; secondly, because of the great variety, delicacy, and com- plexity of movements of which the numerous muscles of the tongue are capable in so small a space,whereby the most delicate shades of thought and feeling can be expressed ; and, thirdly, because the movements of the hands are required for other purposes, while it is difficult to per- ceive what other purpose the wonderful variety of the tongue's movements could have served, when it was not engaged in co-operating in the taking and mastication of food.* The influence of the motor department of mental action, the region of actuation, might receive further illustration from the phenomena of insanity and of certain convulsive diseases. It scarcely admits of question that some of the delusions of the insane have their origin in what may justly be called motor hallucinations ; a dis- order of the nervous centres of the motor intuitions gene- rates in consciousness a false conception or delusion as to the condition of the muscles, so that an individual lying in his bed believes himself to be flying through the air, or imagines his legs, arms, or head, to be separated from his body, just as he has hallucinations of sense when * It is a fact nowise surprising when we consider what they in- herit that deaf mutes, who have been bom so, do of their own accord, untaught, make vocal sounds more or less articulate, attach- ing a definite meaning to them, and using them afterwards in the same sense. In some these sounds are very clear and well defined. viii.] MOTOR NERVOUS CENTRES. 483 the sensorial centres are disordered. In dreams we may sometimes observe the same kind of thing, as when from hindered respiratory movements a person suddenly wakes up with the idea that he is falling over a precipice. Illusory movements, or illusory positions, are the charac- teristic traits of vertigo, which is the subjective aspect of the deranged motor factors ; other subjective sensations, such as noises in the ears, flashes before the eyes, and painful sensations in the head, accompanying them. In dreams, and in drunkenness also, there is no power of correcting these subjective motor experiences ; and the brain or mind, rendering them conscious, converts them into false conceptions of space.* Such motor illusions * " I had some years since," Dr. Whytt writes, "a patient affected with an erysipelas in his i'ace, who, when awake, was free from any confusion in his ideas ; but no sooner did he shut his eyes, although not asleep, than his imagination began to be greatly disturbed. He thought himself carried swiftly through the air to distant regions ; and sometimes imagined his head, arms, and legs to be separated from his body, and to fly off different ways." Obs. on Nature, Causes, and Cure of Nervous, Hypochondriacal, and Hysteric Disorders. 1765. A drunken man who may be fairly steady while his 'eyes are open, or while his motor centres are associated with sensory stimuli, gets subjective sensations of swimming in the head, sinking of his body, &c. , when his eyes are shut. The illusive effects which follow injuries of single muscles of the eye illustrate in a striking manner how the movements of the eye minister to our visual conceptions of space and of relations of position. If the external rectus of the eye is suddenly rendered powerless by an injury, the disposition to occasionally turn the eye outwards per- sists ; but it is, of course, without result. The eye may be turned in all other directions, and the position of objects in the field of vision is correctly perceived. So soon, however, as it is attempted to turn it outwards, an apparent movement of the objects occurs towards the same side to which the futile effort to move the eye is made. This is owing to the fact that the person believes the eye, which is motionless, to move ; the consciousness of the effort to move it is objectified, and produces the hallucination of an actual movement, and as the eye notwithstanding does not move, the objects appear to move. If the external rectus is only partially 484 THE PHYSIOLOGY OF MIND. [CHAP. or hallucinations can of course only ensue when the reaction of the disordered motor intuition is into con- sciousness ; if, as may happen, and commonly does happen, the reaction takes place outwards, there are irregular or convulsive movements, but no delusion is generated. In fact, when the motorium commune is dis- ordered, its morbid function may be displayed in irre- gular or convulsive muscular action, and, if the deterior- ation proceed far enough, in paralysis ; or it may react upon the mental life and give rise to disorder of intelli- gence. According as the disordered function acts in an upward or downward direction, centripetally or centri- fugally, that is, according as it invades the sphere of con- sciousness or passes into outward expression, it occasions mental disorder or convulsions. The phenomena of convulsions, properly examined, serve to illustrate the existence and to exhibit the inde- pendent action of the motor intuitions ; their discon- nected movements show plainly that there are special motor nerve-centres which may, when co-ordination is deranged, act independently. Be it noted that every kind of movement which may be normally excited by the will may occur as a convulsive act, when, of course, there is no question of the exercise of will, and when there is often an entire absence of conscious- paralyzed, the eye may be fixed upon an outward-lying object, but a stronger effort will be needed to do so. Accordingly the object will appear to be placed farther outwards than it actually is, and if the person makes a grasp at it, his hand will go beyond it. Thus the judgment of the position of an object in space is essentially de- termined by the feeling of effort which accompanies every im- pulse to movement. See WUNUT, Grundzitge der physiologischen Psychologie, p. 553, who has deeply discussed this subject ; also BAIN, The Stnsfs and the Intellect, where it is treated in thorough detail. It appears that Mr. Bain's theory and exposition of the nature of our perception of space agrees in essential points with that of Steinbuch. (Beitrag zur Fhysiohgie da- Sinne. Nurnberg, iSil.) vin.] MOTOR NERVOUS CENTRES. 485 ness. As the individual in sound health must give in- tense attention in order to isolate a certain muscular movement which usually takes place as a part of a com- plex series, and cannot always then succeed, it is nowise surprising that there should often be more or less co- ordination of movements in spasmodic or convulsive muscular action. Indeed, it would be surprising if there were not. In cases of cerebral hoemorrhage, it sometimes happens that the articulating movements of single sounds, or of a certain series of sounds, syllables, or words, are produced without any mental act or even against the will of the patient ; in like manner, other co-ordinate move- ments take place sometimes without the least trace of consciousness being evinced. We shall not be sur- prised at the occasional occurrence of speech movements and of other definite acts during complete unconscious- ness if we call to mind how poetry which has been thoroughly learned may be repeated mechanically, while the attention is engaged on something quite different ; the repetition, once started, being indeed most successful when done with least consciousness. As examples of general spasmodic action of the body, co-ordinated never- theless into a particular outcome, Romberg relates a remarkable case of what he calls rotatory spasm in a girl ten years of age, and another case of co-ordinated spasm in combination with chorea, which occurred in a boy aged six, who was occasionally attacked with an irresistible desire to climb in spite of every impediment; in the intervals he was affected with chorea. Conscious- ness is not always entirely abolished ; and in that case the patients are able to give an account of the impulse which instigates the movements, and which they are un- able to withstand successfully. It is a well known fact that the idea of convul- sions, whether excited by present perception or through memory, may express itself in convulsive movements 22 486 THE PIIYSIOLCGY OF MIND. [CHAP. movements which, nevertheless, often display a con- siderable amount of co-ordination. Everybody perceives how, in a healthy person, swallowing, coughing, and yawning are excited by the observation of these acts in another ; and as instances of similarly produced morbid actions, Romberg adduces those dancing epidemics of the Middle Ages, in which co-ordinate spasmodic move- ments were notoriously excited in delicate women, and continued by them with a violence and persistence which would soon have exhausted the strongest man who was in a normal mental state. Persons who are labouring under acute mania frequently keep up an unintermitting succession of purposeless, irregular, and mischievous or destructive acts, which nevertheless evince a considerable amount of co-ordination a complex co-ordination of acts, I mean, not of individual movements simply ; their actions, like their ideas, are delirious and incoherent. They are complex machines which, being out of order, go on in deranged action. Will represents the highest co-ordination of the ideas, feelings, and movements ; when disease has destroyed this highest acquisition of evolu- tion, we have, so to- speak, a resolution of will into the component factors, which now act on their own account automatically : the uncontrolled act of passion, or the convulsion of a limb, is a loss of power of will, because it is an independent act, no longer in due co-ordination with, or subordination to, other functions of the mental organization. It behoves us to keep well in mind, and to appreciate the full bearing and import of, the fact that as so many of our co-ordinate actions are done automa- tically in health, so there may be much co-ordinate automatic action in the convulsive phenomena of disease. There yet remain further important considerations. Let a man have the will to command a certain move- ment and a conception of the result desired, without viii.] MOTOR NERVOUS CENTRES. 487 any paralysis of motor power, he may still be impotent to perform the movement. And why ? Because there may be a paralysis of sensibility in the muscles of the part, by reason of which he has no means of knowing what is the condition of the instruments which he has to use cannot tell whether they are acting or not ; he lacks that information which the muscular sense should rightly yield him.(') In order that the will may actuate a movement, there are necessary, then, not only a concep- tion of the end desired and a motor intuition of the muscular movements subserving that end, but also a sense of the action of the muscles. Any psychological . arguments as to the value of this guiding muscular feel- ing are rendered needless by pathological experience, which plainly proves that, when the muscular sense is paralysed, the movements cannot be performed, except some other sense come to the rescue ; or, at any rate, that when all the other senses are seemingly perfect the movement cannot be performed, presumably because of the loss of the muscular sense. It is not to be looked upon as an actively conscious sense, like sight or touch, but rather as of the nature of organic sense, giving its in- formation and working its effects without definite con- sciousness. The sense of sight may take its place when it is lost : a woman whom Sir Charles Bell saw, who had lost the muscular sense in her arm, could nevertheless hold her child when she kept her eyes upon it ; but the moment she turned her eyes away she dropped the child. I have seen a similar instance of a woman, epileptic in consequence of syphilis, who had lost the muscular sense in her left arm, and who did not know, except she fixed her eyes upon the limb, whether she had got hold of anything with her hand or not ; if she grasped a jug, she could hold it quite well as long as she looked at it, but if she turned her eyes away she dropped it : she had no loss of tactile sensation. 4S8 THE PHYSIOLOGY OF MIND. [CHAP. In such morbid states the difference between tactile sen- sation and the muscular sense is well marked.* " Ollivier details a case in which the patient had lost the cutaneous sense of touch throughout the side in consequence of concussion ; at the same time he was able to form a correct estimate of the weight of bodies with his right hand. The physician observed by Marcet, who was affected with anaesthesia cutanea of the right side, was perfectly able to feel his patient's pulse with the fingers of the right hand and to determine its frequency and force, but in order to determine the temperature of the skin he was obliged to call in the aid of his left hand." Anaes- thesia of the muscle, without loss of tactile power, does, according to Romberg, invariably accompany the disease * Those who deny the existence of a special muscular sense hold that the information which we have of the position and movements of our limbs is furnished by the tactile sense, and by the sensory nerves distributed to the ligaments, the joints, &c. Certainly we are conscious of the position of a limb in passive movements, when, as it is moved for us, we appear to make no muscular exertion. But it is not then as passive as a dead man's limb. There is some muscular tension. Moreover it is true that, when there is cutaneous insensibility without loss of muscular feeling, the perception of our own movements is considerably disturbed. It would appear that the perception of the position of a limb is really a complex product produced by the fusion of manifold local sensations ot touch with our various muscular feelings, and that, once formed, it is excited by stimulation of any one of the simple sensations from the fusion of which it has proceeded by any one of its constituent sen- sations ; just, in fact, as a perception is excited by the stimulation ol any one of the special senses from the sensations of which it has been constituted e.g. the perception of an orange through touch, or smell, or taste, or sight. When we are lying in bed at perfect rest, with- out the least movement of a muscle being made, and without the least movement of anything that is in contact with the surface of a limb, we may be uncertain or unaware what its exact position is ; but the moment a slight muscular contraction is made, or the moment a sensation of touch is produced by the least movement of the limb, or by the slightest movement of the clothes covering it, we have an instant perception of its position. vin.] MOTOR NERVOUS CENTRES. 489 called tabes dorsalis."* The eyes of patients so affected are their regulators or feelers, and consequently their helplessness, when their eyes are shut, or they are in the dark, is extreme ; if told to shut their eyes while in the erect posture, they begin to oscillate until they fall down, unless supported. The skin remains sensitive except during the last stage of the disease. Romberg, Duchenne, and others have, moreover, described similar morbid conditions in aneemic and hysterical women, which can hardly be called paralysis, as they are manifest only in the night or when the eyes are shut : the patients can perform movements, but these do not answer accurately to the will ; they are deceived as to the amount of force necessary to be put forth, and some- times cannot undertake the movement of a limb without the help of sight. In these cases there is the desire to effect a certain action, there is the motor intuition of the movement necessary to the end desired, but the guiding sensation of the muscular sense is defective or wanting accordingly the action cannot be done unless the sense of sight takes upon it the function of the defective muscular sense. These and similar cases ot disease seem to me to throw some light upon the nature of that which we mean when we speak of directing the attention and exerting the will strongly. In order to direct the attention and exert the will sufficiently in these cases in which there is * It must be remembered that simple loss of muscular feeling is not tabes dorsalis. In tabes dorsalis, the characteristic phenomenon is a loss of the power of co-ordination of the muscles, and the morbid appearances are those of degeneration of the posterior columns of the spinal cord the motor repository or centres of co-ordination of the movements of the limbs. Hence the disease is now more properly called progressive locomotor ataxy. Loss of muscular feeling is a symptom that may occur in different diseases ; if another sense takes its place, movements are still effected ; so that the power of movement, the repository of motor residua, is not affected. 490 THE PHYSIOLOGY OF MIND. [CHAP. some temporary exhaustion or morbid enfeeblement of the motor faculties, and a powerful stimulus is necessary to do what a moderate stimulus will usually do, the sensory stimulus of the muscular sense must be strength- ened by the co-operation of the stimulus from the sense of sight, to which will be added the stimuli from the acting muscles of the eye. In this way the excito-motor process is aroused by a more active stimulus ; for the sum of the contributions of co-operating stimuli from different senses amounts to the same thing in this relation as the more powerful action of a single stimulus. The direction and the exertion of will are really a solicita- tion or excitation of greater excito-motor energy, and consequently of more active consciousness (i.e. attention) through the agency of co-operating sensory stimuli : the process is purely physiological. It is in the same way that the exhausted debauchee, who is impotent in response to the natural sensory stimuli, succeeds in arousing the excito-motor function of sexual gratification by bringing to bear upon each sense all the depraved stimuli to which it is sensible, thus accumulating a sufficient stimulus to produce the desired excitation. If he be a person of strong imagination he may perhaps succeed in producing the effect by a vivid mental representation, without actual presentation, of the impressions which are adapted to act as stimuli on the different senses. Thus it appears that, as was before set forth, what we call directing conscious- ness by a voluntary effort is really the excitation of con- sciousn ess in consequence of the greater activity of cere- bral processes which is produced through the co-opera- tion of as many stimuli, internal or external, as it is possible to bring into action. What relation has the muscular sense to the motor intuition ? It is not an easy question to answer either from a psychological or from a physiological basis, inasmuch as it is not easy to put asunder in thought viii.] MOTOR NERVOUS CENTRES. 491 what nature has joined together. The relation appears to be not unlike that which the sensation of a special sense has to the corresponding idea : as the sensation of the special sense is necessary to the formation of the idea, but, the idea once formed, not necessary to its existence or function, so the muscular feeling would seem to be an essential prerequisite to the for- mation of the motor intuition, but, this once formed, not necessary to its latent existence, or indeed to its active function, provided only another sense furnish the guiding information. Like other senses, the muscular sense is receptive ; it ministers to the building up of the funda- mental ideas of solidity, size, figure, and distance, through the impressions which it receives from without and conveys inwards, and the subsequent internal adapta- tions which take place ; and in the outward intelligent reaction of the individual upon external nature, by virtue of these ideas, it furnishes the guidirg feeling by which he is enabled to direct the aqtion and to regulate the amount of force applied in any given case. In point of fact, the consolidation of its different impressions with the adapted movements constitutes the percep- tion of the object constitutes what is, so far as we are concerned, the object : how then can we act practi- cally in relation to the perception, when the sensory contributions are taken out of it, and when it is no longer therefore to us the definite object, unless some other sense supplies what is wanting and so completes the perception in other words, reconstitutes the object for us ? How admirably graduated is the application of force by the skilful hand in delicate handicraft operations ! How clumsy and incapable is the beginner in such crafts until, by frequent practice, the requisite motor intuitions have been acquired 1 Consider how awkward any one is at so simple a matter as winding up a watch for the first time, and how quick, easy, and precise the operation 492 THE PHYSIOLOGY OF MIND. [CHAP. afterwards becomes. Observations made upon persons born blind prove that there is nothing essential to the highest intellectual processes which may not be acquired in the absence of sight, mainly through the muscular feeling in combination with touch. ( 2 ) Because the muscular feelings in combination with tactile and other sensations gradually build up the motor intuitions in accordance with the order, synchronous or successive, of our experience, it is not difficult to de- ceive them by a new experience modifying or reversing that order. They are inductions, and, like all in- ductions per enumerationem simplicem, they are liable to be upset by the instantia contradictoria. We have already shown how the eye may be deceived, and there is a familiar example of similarly produced illu- sion in the case of touch. It is well known that, if the middle finger be crossed over the fore-finger, and a pea or a like round body be put between them and the fingers rolled over it, while the eyes are turned away, there will be the sensations of two bodies ; the impression on that side of the fore-finger which is habi- tually associated in action with the thumb excites inde- pendently its residua, and the impression on that side of the middle finger which is accustomed to act with the third finger excites also its residua ; the consequence is a feeling of two bodies which it requires the evidence of another sense to correct. So closely and definitely are our different senses associated in their functions that they may, instead of aiding and correcting one another, as is their proper function, thus actually help to deceive one another when the order of their experiences is un- expectedly deranged. When the metal potassium was first shown to an eminent philosopher, he exclaimed, on taking it into his hand, " Bless me, how heavy it is ! " and yet potassium is so light as to float on water. The metallic appearance had suggested a certain resist- vin.] MOTOR NERVOVS CENTRES. 493 ance, or the putting forth of so much muscular energy as previous experience of substances having a similar look had proved necessary ; the consciousness of the effort made instigated the false judgment, the suggestion of the visual sense overswaying the actual experience of the muscular and tactile senses : the latter were deceived, as the man is who concludes that a certain co-existence or succession in nature must always exist because he has observed it in a great many instances ; or as, at the supposed disinterment of a body suspected to have been murdered, one of the spectators who fainted on account of the bad smell was deceived ; for, -when the coffin was opened, it was found to be empty. It is well-known that a person feels sensations in a limb, and is conscious of its different positions, as if it were present, for some time after it has been amputated. " Urging a patient who had lost his leg to move it," says Sir Charles Bell, " I have seen him catch at the limb to guard it, as if forgetting that it had been removed. Long after his loss he experi- enced a sensation not only as if the limb remained, but as if it were placed or hanging in a particular position or posture. I have asked a patient, ' Where do you feel your arm now ? ' and he has said, ' I feel it as if it lay across my breast,' or that it is ' lying by my side.' It seems also to change with the change of pos- ture of the body. These are additional proofs of a muscular sense ; that there is an internal sensibility cor- responding to the changing condition of the muscles; and that as the sensations of an organ of sense remain, after the destruction of the outward organ, so a decep- tious sensibility to the condition of the muscles, as well as to the condition of the skin, will be felt after the re- moval of a limb." * * The Hand, its Mechanism and Vital Endcnvment. Dr. Weir Mitchell has found that electrical stimulation of the nerves of a stump t94 THE PHYSIOLOGY OF MIND. [CHAP. The perfect functions of the motor residua are not only essential to the expression of our active life, but, like the functions of the special senses, they are essential constituent elements of our mental life. In the common form of the disease which is known as general paralysis ?f the insane there are two prominent characteristics : the first is the general paralysis, in greater or less degree, of the muscles of the body ; and the second is the extraor- dinary delusions of grandeur. It is a question well worth consideration, whether these characteristic symptoms do not stand in some degree of causal connection with one another. A tailor who is suffering from general paralysis will readily promise to make a magnificent coat or waist- coat, and, if the materials are supplied to him, will at once set to work. It is not improbable that, deceived by his quiet assurance, and knowing that to sew is his busi- ness, one may believe that he can make the garment But, in a little while, it will be found that his stitches are most unequal in size, and are placed in the most dis- orderly way ; and it is made clear that, whatever he himself may think, he certainly cannot sew properly. He has a sufficient desire to accomplish the result, an adequate general notion of the end desired, a full belief in his ability to effect it ; but he fails because his motor residua are disordered, and because he cannot regulate precisely the action of the necessary muscles. And because his disordered motor intuitions have invaded consciousness, he does not realise his failure, but is happy under the delusion that he has accomplished his work admirably. We must not overlook the effects upon con- sciousness as well as the effects upon movements : as the sleeper, whose external senses are so closed as to shut out the controlling influence of external objects, often does in his dreams the most wonderful things, and finds little will give rise to vivid feelings of different positions of the lost limb long after it has been removed. vn (.] MOTOR NERVOUS CENTRES. 495 or no hindrance to an almost miraculous activity, intel- lectual and bodily j so the general paralytic, whose dis- ordered motor residua cut him off from the due apprecia- tion of external relations, and suggest false intuitions of these relations, has the most extravagant notions as to his personal power and prowess engendered in his mind ; he dreams with his eyes open.* As we owe mainly to the muscular sense the development of our fundamental ideas of resistance, form, size, and space, it will easily be understood that, when this sense is deficient throughout the body, as in the general paralytic, there cannot be that intelligent accord between the inner life and the outward relations which, when in a perfect state, it main- tains. Here, again, we perceive how impossible it is to separate the mental from the bodily life; how plainly, when we scan the deeper relations of things in their genesis, there are displayed the closest connection and continuity of parts and functions. To the action of the will, as already pointed out, a conception of the result is essential, whether the voli- tional exertion be for the purpose of causing a movement, of preventing or checking a movement, or of dismissing a painful idea from the mind. When a sensation excites a co-ordinate movement in so-called sensori-motor action, we do not say there is a conception of the result, because of the absence of consciousness ; but at the same time we must admit that there is a definitely organized residuum in the proper motor nervous centre, which, as it were, * I once had under my care a general paralytic who was occa- sionally much excited, believing that he was fighting great battles, and winning great victories with his fists ; he believed, too, that he won immense sums of money as wagers on his prowess. The dis- order of his motorium commune entered into his thoughts and engendered corresponding delusions. He was confined to his bed or couch by reason of having lost one leg, or he would have been a violent and dangerous patient. VJ 6 THE PHYSIOLOGY OF MIND. [CHAP. implicitly contains the movement. Now it is important to bear in mind, when the movement is cerebro-motor, the will exciting that co-ordinate movement which a sen- sation alone may do, as not unfrequently happens, that it cannot operate directly on the motor nerves, but must necessarily operate through the medium of the same motor agency as that through which the sensation acts : in other words, the movement in both cases proceeds directly from the motor nervous centre in which the movement is latent. In both cases it is truly reflex, the stimulus in one case coming round by the convolutions, in the other case more directly across from the senses. If we could excite the motor centres artificially, not over- exciting and injuring them, as in our gross experiments we necessarily do, then we should not fail to set free the definite movements. Speaking psychologically, the con- ception of the result becomes in the execution of volun- tary movements the motor intuition, and the motor in- tuition excited into activity expresses itself in the designed movement through the agency of the subordinate motor centres. Thus, then, it appears that, as in the action of nature upon man, the stimulus which is not reflected in the spinal cord passes upwards and excites sensation, and the stimulus which is not reflected in sensori-motor action passes upwards and becomes idea, and the stimulus which is not reflected in simple ideomotor action passes from cell to cell in the hemispheres and excites complex ideation or reflection ; so in the reaction of man upon nature, the energy which we designate psychologically the will, passes downwards through the subordinate centres in an opposite direction : the will involves a conception of the result or a definite ideational action ; the conception of the result demands for its further transformation the appropriate motor intuition ; and the motor intuition gets its due expression in movement through the perfect viii.] MOTOR NERVOUS CENTRES. 497 function of the muscular feeling and the integrity of the motor nerves and the muscles. There is an orderly subordination of the different nervous centres ; a chain of means such as is revealed in every department of nature. Taking a survey of the different sciences, we perceive that chemistry is dependent on physics, while physics is independent of chemistry ; physiology is de- pendent on chemistry, while chemistry is independent of physiology ; sociology is dependent on physiology, while physiology is independent of sociology : and so the just analysis of our mental life proves that sensori-motor action is dependent on reflex action, while reflex action is independent of sensori-motor action; ideomotor ac- tion is dependent on sensori-motor action, while sensori- motor action is independent of ideomotor action ; the will is dependent on ideomotor action, while ideomotor action is independent of the will. These different epochs, as we might call them, in the order of develop- ment of the nervous system are represented by different classes of the lower animals : and it is interesting to note that, as in man there is a subordination of parts, and the will, as the highest energy, controls the inferior modes of nervous energy, so in the animal kingdom there is a subordination of minds, and the mind of man, as the highest development, controls and uses the inferior minds of many of the lower animals. There can be little doubt that his supremacy has checked the evolution of other animals which would probably have gone on had he not appeared on the earth. If execution has been in any wise answerable to con- ception, I have now said enough to prove the.importance of that region of mental activity in which dwell the motor residua, and which may properly be named the region of actuation. I have only to add that men differ much naturally as to the perfection of this as of other mental faculties. There are some who, with great intellectual 498 THE PHYSIOLOGY OF MIND. [CHAP. power, never can attain to the ability of successfully expressing themselves; there are others, on the other hand, who can pour forth endless talk with the most facile fluency. The art of expression in speech, or in writing, or even in eloquence of action, is one which, if there is not an innate faculty for it, can never be acquired in its highest perfection : unseen fetters hinder the full utterance, and lame execution falls far short of ambitious conception : with the distinct conception of what they would say, and the best will to say it, there is something wanting in the region of actuation, whereby they are prevented from doing justice to their thoughts, and are compelled, like Moses, to delegate that func- tion to others. " There is Aaron : he shall be thy speaker, and thou shall be to him instead of God." (Exodus iv. 1 6.) * It might be said perhaps that when a person is unable to express his thoughts clearly in suitable language it is that he has not the thoughts clearly conceived in his mind, that they are vague and only half formed, floating in an undefinable, hazy, or nebulous state. Without doubt, when a thought can be properly expressed it has acquired a precision and a definiteness of relation to other thoughts which it had not before it was embodied in language ; but it may be fairly doubted whether it is correct to describe as only half formed all those thoughts which cannot have full justice done to them in speech or in writing. There are few persons accustomed to think who have not experienced occasions when the mind has seemed to be illuminated by a vivid flash of intuition, or the emotions to have reached a strain of exaltation which transcended the capacities of expression in ade- quate words ; true or not, they have believed themselves * And a greater than Moses or Aaron was so gifted with the faculty of excellent expression, that it was said of Him that " Never man spake like this man." vtir.] MOTOR NERVOUS CENTRES. 499 to have had thoughts too deep for words and feelings that were unutterable. To me it seems that this occurs sometimes in coherent dreaming, and that one awakes with a feeling of despair at the inability to grasp de- finitely and to fix in words what has passed through the mind ; with a conviction, moreover, that what has been lost was not a mere illusion, but of genuine worth. How much, again, of the depth and subtilty of thought is sometimes lost in the feeble and inadequate expres- sion ! How great a part of the mental effect produced by the highest poetry or the best art is that which is not expressed, but suggested, and which cannot be ex- pressed, being unutterable ! It would not be prudent to predict what the course of human evolution will be through the ages to come, but, whatever it be, it can hardly fail to be accompanied by a more complex, special, and subtile development of the powers of expression. Certain it is that there has been a continuous develop- ment of language through the past ages of human life. Language was not a gift miraculously bestowed upon man, nor a conscious invention which was designedly improved by him, but it is essentially an organic growth which has proceeded from the instinctive or unconscious life, and has been brought to its present completeness by the accumulated contributions of successive generations of men. It would be obviously absurd to conclude con- cerning the beginnings of human language from the multitude of words possessed by any language of the earth at the present day. If the history of a language be traced back for a few hundred years, it will at once be seen how much it has changed in that time ; how many new words have been added to it ; and how much some old words have gradually changed their meanings, while others have fallen into disuse and become obsolete. Could we trace back language to its earliest beginnings, 5co THE PHYSIOLOGY OF MIND. [CHAP. and strip from it each fresh acquisition at the time and place where it was made, we should gradually lay bare- its early nakedness and poverty, discovering it to consist of a few primitive roots answering to the feeble intel- lectual shoots of the race. But we cannot go so far back. When we follow the course of development of the Indo-European languages backwards as far as we can, there is no certainty that the roots which we reach are original : on the contrary, it is almost certain that they are not ; that they are transformations ; that what we know to have been going steadily on in his- toric times has gone on in the pre-historic times of which we can only darkly guess. Language in all its forms consists of signs, and a sign is a particular movement which is in definite connec- tion with a certain sensation or thought ; sensory im- pressions or subjective states being reflected in objec- tive movements. The definite movement is accordingly, the sign of the internal state, and its relations are essen- tially social not individual. To the action of the envi- ronment upon the individual there is reaction by him in a modification of the environment he feels and under- stands what is in order to determine what is to be: were he a solitary being, he would require to make only those adapted movements that were necessary to self-preserva- tion, such movements being, as it were, a silent language addressed to, and understood of, nature ; but as he is not a solitary but a social being, as he must react upon human nature, he makes, in answer to social impressions, for the purpose of mutual communication, movements that are of social meaning, and these movements develop into the different forms of language. Language, there- fore, is truly a social growth, giving unity and cohesion to the social organism.* 1 here is every reason to suppose that the earliest form * Comte, System of Positive Polity, vol. il, Social Statics, via.] MOTOR NERVOUS CENTRES. 501 of language was the involuntary language of action and of cries, giving expression to feelings, and that the voluntary language of speech, giving expression to thoughts, was a later development. In the higher ani- mals definite acts are the constant signs of the feelings which actuate them ; they are the language of action, understood by all creatures similarly organized, and understood by man in virtue of the groundwork of or- ganization which he has in common with them. Gestures and cries are largely used in like manner by the lower races of mankind, among whom the social life is very imperfect, to communicate their feelings. The Bosjes- men are said to make so much more use of gestures than of speech that they are unintelligible to one another in the dark, and are compelled, when they want to con- verse at night, to assemble round their camp-fires. To this basis of emotional gesture-language must be traced the source or root of the voluntary language of speech which has reached so complex a development in man. For as social relations were multiplied and expanded, and became more special and complex, answering multiplications and complexities of movements were necessitated ; the interchange of feelings passed into an interchange of thoughts ; and the requisite means of in- tellectual expression were found in the numerous, com- plex and delicate movements of speech, the convenience of whicn has led to its almost exclusive adoption. Be- cause of this development of the complex voluntary language of speech in man, the involuntary basis of language is best studied in the lower animals, where it is presented in its simplest form ; for they, checked in evolution by the ascendency of man, have never passed from the language of feeling gestures and cries, to the language of thought speech. Cries and gestures are also the language of infants ; and under the influence of strong excitement the vocal organs of the adult act 5oa THE PHYSIOLOGY OF MIND, [CHAP. involuntarily, the cries of joy, horror, fear, amazement which give utterance to the internal feelings being in- telligible, without instruction, to all beings similarly organized. When feeling is expressed in speech, it is by modification of the vocal tone; and tone is original, in- voluntary, not acquired and designedly used. In mono- syllabic languages the same word has different meanings at the present day according to the tone in which it is uttered. Thus, in the child and in the least developed languages we find what may be justly considered as sur- vivals of an operation which has had large sway in the original formation of language. By whatever differences of tone of voice, or by what- ever differences of movements, an animal may express its different feelings, it is doubtful whether any animal has ever got so far as to appropriate a special call to a special person or object to name it ; unless it be in a few rare instances in which it has been taught to do so by man. Certain it is that if animals have such a power it is of the most rudimentary kind, and has not under- gone any development. So soon, however, as a child has consciously called its father or its mother, which it soon learns to do by using the special call for each, language in its true sense has commenced.* In the same way, no doubt, language began with the race of man : special names were given to special objects, and special words appropriated to express special feelings whereby mutual communication was accomplished. Wien, as we are informed, the Lord God, having formed out of the ground every beast of the field and every fowl of the air, brought them unto Adam to see what he would call * It appears that the earliest sounds made by the child Ma and Pa, are met with in all languages. They are natural sounds, the special meaning being given to each by the parents. For in some languages Pa is mother, and Ma father. Volkei'kunJe, von Oscar rescbcL viii.] MOTOR NERVOUS CENTRES. 503 them, " Adam gave names to all cattle, and to the fowl of the air, and to every beast of the field, and whatso- ever Adam called every living creature, that was the name thereof." The story indicates the mode of origin of language as a product of man's development ; and if Adam be interpreted to mean the successive generations of men that have in turn contributed to the formation of language, as scientific theologians or theological scientists interpret the formation of every living thing out of the ground to mean the process of evolution going on through successive ages, pious hearts need not be troubled, but may take courage and exult that each new scientific discovery is a new confirmation of faith, when Biblical history is interpreted in the largely liberal spirit of those who think " there be not impossibilities enough in religion for an active faith." It does not seem hard to conceive how, once the first step was reached, once the communication of a thought, feeling, or want was designedly made by one being, by means of a definite vocal expression, and was understood by another, the development of language gradually took place coincident with, or sequent to, the development of intelligence. But how was the first step made the first mutual understanding come to between the maker of the sound and the hearer of it ? We may conceive perhaps how this was if we call to mind what may be observed any day in the barn-yard when the cock, having dis- covered a grain, calls the hens by a special note, who understand and flock round him. It may be observed too that he will astutely pretend to have made a dis- covery, and will use a similar call, when he wishes to bring the hen to him in order to gratify his sexual want That the hen is sensible of the difference of call and apprehends guile is plain, for it often shows itself coy, making a timid approach as if suspecting mischief, and will not come close to him, but must be pursued. 504 THE PHYSIOLOGY OF MIND. [CHAP. Here, then, in the food-wants and the sexual wants we perceive how there must have arisen vocal communi- cation and understanding thereof among primeval human beings. In like manner, other feelings would have their expression which would be understood : an angry bite or blow or scratch could not fail to give meaning to, and to teach the meaning of, the accompanying tone or gesture. It is probable, as I have already explained, that the earliest vocal language consisted of these vocal expres- sions of wants and feelings, and that the naming of objects, or the development of language as an instru- ment of the intellect, was subsequent. How this naming of objects was done is a question the answer to which must be left to those who are learned in the knowledge of the origin and development of languages, when they have come to an agreement among themselves. To one who has no pretence to special knowledge of the subject it would seem that it was done then, in the main, as it is done now by children, by the imitation of the sounds by which attention was attracted to the object ; that the word was formed by imitation of the sound, and the connection of the idea with it made subse- quently, sensori-motor having preceded ideo-motor function. Thus for example, the child hears the dog bark, and thereupon imitates the sound, making a bow-wow ; the idea of a dog is expressed afterwards by making this sound. It is when a child is born deaf, and hears therefore no sounds to imitate, that it is dumb ; it is not dumb when it is born blind, though it is then deprived of the chief avenue of ideas, because it does hear sounds which it imitates. There is in man an innate aptitude to imitation, which may be regarded as an Expression of the reflex function of the nervous system ; it is very evident in children, and more so in the mimicry of his next-of-kin, the monkeys. It is obvious that this vni.] MOTOR NERVOUS CENTRES. 505 process of verbal naming by imitation could take place only in relation to sounds, and that the perceptions of the other senses must have been named in another way. Still, if a person had got so far as to name the perceptions of one sense, it would not be a great step forward to desig- nate the perceptions of the other senses by arbitrary signs ; for the deaf and dumb have invented their own signs, drawing them from the nature of the objects or from the outlines or principal movements of actions, and many of their signs are said to be the same as those used by the Indians from Hudson's Bay to the Mexican Gulf. Men all over the world do in fact hit upon the same gesture- language to express themselves, and we may justly con- clude that if they had not had speech they would still have acquired a means of communicating with one another by signs ; they could not well have helped it, so long as they were beings endowed with a capacity of re- acting to multitudinous impressions by answering varie- ties of movements. So much then concerning the origin and development of language ; it is the highest display of reflex function, and the most complex and special evolution of man's re- lations to his social environment. Using the words of Comte, we may say that "it is the expression of that essential unity which religion creates," being essentially relative to the social and not to the individual side of man, and presupposing the co-operation of men in associ- ation through successive generations. "The very sophism by which they [retrograde philosophers] blaspheme humanity itself could not be uttered at all, but for a system of expressions which are the work of long genera- tions of men."* These embody the slowly won experiences of past ages ; and in teaching them to those who will come after us and carry forward the torch when it falls * System of Positive Polity, vol. ii. Translated by Frederic Harrison. 506 THE PHYSIOLOGY OF MIND. [CHAP. from our failing grasp, we are exerting upon them through words all the influences which the objects in nature denoted by them have, during countless ages, exerted upon those who have gone before us ; for it is in lan- guage that the wisdom of past generations is enshrined, and through it that each succeeding generation inherits the accumulated knowledge of preceding generations. NOTES. 1 (p. 487). " When a blind man, or a man blindfolded, stands upright, neither leaning upon nor touching aught ; by what means does he maintain the erect position ? The symmetry of his body is not the cause. A statue of the finest proportion must be soldered to its pedestal, e'se the wind will cast it down. How is it, then, that a man sustains the perpendicular posture, or inclines in due degree towards the wind that blows upon him? It is obvious that he has a sense by which he knows the inclination of his body ; and that he has a ready aptitude to adjust the parts of it, so as to correct any deviation from the perpendicular. What sense is this? He touches nothing, and sees nothing; there is no organ of sense hitherto observed which can aid him. Is it not the sense which we have seen exhibited so early in the infant, in the fear of falling, and which caused its struggles while it yet lay in the nurse's arms ? It can only be by the adjustment of muscles that the limbs are stiffened, the body firmly balanced, and kept erect ; and there is no other source of knowledge but a sense of the degree of exertion in the muscular frame by which a man can become conscious of the position of the body and action of the limbs, while he has no point of vision, or the contact of any external body, to direct his efforts. In truth, we stand by so fine an exercise of this power, and the muscles, from habit, are directed with so much precision, and with an effort so slight, that we do not know how we stand. But if we attempt to walk on a narrow ledge, or rest in a situation where we are in danger of falling, or balance on one foot, we become sub- ject to apprehension : and the actions are then, as it were, magnified and demonstrative of the degree in which they are excited. Although we touch nothing, and see nothing, yet we are sensible of the posi- tion of our limbs ; that the arms hang by the side, or that they are raised and held out. And it must be by a property internal to the viu.] MOTOR NERVOUS CENTRES. 507 frame that we know this. At one time I entertained a doubt whether this knowledge proceeded from a sense of the condition of the muscles, or from a consciousness of the degree of effort which had been directed to them in volition . But I reasoned in this manner we awake with the knowledge of the position of our limbs ; this can- not be from recollection of the action which placed them where they are ; it must, therefore, be a consciousness of their present condition. When a person just after awaking moves his body, it is with a determined object ; and before he can desire a change or direct a movement, he must be conscious of a previous condition." Sir C. HELL, The Hand, Us Mechanism and Vital Endowments. The question is whether we do awake with the knowledge of the posi- tion of our limbs whether we are not without that knowledge until some movement, it may be ever so slight, is made. 2 (fl. 492). In the forty-third Annual Report of the Massa- chusetts Asylum for the Blind, Dr. Howe gives an interesting description of the method which he employed for the instruction of Laura Bridgman, who was totally blind and deaf, and who had only a very indistinct sense of smell. I quote Dr. Howe's descrip- tion entire : "I found in a little village in the mountains a pretty and lively girl, about six years old, who was totally blind and deaf, and who had only a very indistinct sense of smell ; so indistinct that, un- like other deaf-mutes, who are continually smelling at things, she did not smell even at her food. This sense afterwards developed itself a little, but was never much used or relied upon by her. She lost her senses by scarlet fever so early that she has no recollection of any exercise of them. Her father was a substantial farmer ; and his wife a very intelligent woman. My proposal to try to give regular instruction to the child seemed to be a very wild one. But the mother, a woman of considerable natural ability, animated by warm love for her daughter, eagerly assented to my proposal, and in a few days little Laura was brought to my house in Boston, and placed under regular instruction by lessons impro- vised for the occasion. " I shall not here anticipate what I intend to write about her, further than to say that I required her by signs, which she soon came to understand, to devote several hours a day to learning to use her hands, and to acquiring command of her muscles and limbs. But my principal aim and hope was to enable her to recognize the twenty-six signs which represent the letters of the alphabet. She submitted to the process patiently, though without understanding its purpose. 5o8 THE PHYSIOLOGY OF MIND. [CHAP. " I will here give a rough sketch of the means which I contrived for her mental development. I first selected short monosyllables, so that the sign which she was to learn might be as simple as pos- sible. I placed before her, on the table, a pen and a pin, and then, making her take notice of the fingers of one of my hands, I placed them in the three positions used as signs of the manual alphabet of deaf-mutes for the letters pen, and made her feel them, over and over again, many times, so that they might be associated together in her mind. I did the same with the pin, and repeated it scores of times. She at last perceived that the signs were complex, and that the middle sign of the one, that is the e, differed from the middle sign of the other, that is /. This was the first step gained. This process was repeated over and over, hundreds of times, until, finally, the association was established in her mind between the sign composed of three signs, and expressed by three positions ol my fingers, and the article itself, so that when I held up the pen to her she would herself make the complex sign ; and when I made the complex sign on my fingers she would triumphantly pick up the pen, and hold it up before me, as much as to say, ' This is what you want.' " Then the same process was gone over with the pin, until the association in her mind was intimate and complete between the two articles and the complex positions of the fingers. She had thus learned two arbitrary signs, or the names of the two different things. She seemed conscious of having understood and done what I wanted, for she smiled, while I exclaimed inwardly and trium- phantly, " ttpiiKa. ! t*pr)Kal" I now felt that the first step had been taken successfully, and that this was the only really difficult one, because by continuing the same process by which she had become enabled to distinguish two articles, by two arbitrary signs, she would go on and learn to express in signs two thousand, and, finally, the forty and odd thousand signs or words in the English language. " Having learned that the sign for these two articles, fin and f-en, was composed of three signs, she would perceive that in order to learn the names for other things she had got to learn other signs. I went on with monosyllables, as being the simplest, and she learned gradually one sign of a letter from another, until she knew all the arbitrary, tangible twenty-six letters of the alphabet, and how to arrange them to express various objects : knife, fork, spoon, thread, and the like. Afterwards she learned the names of the ten numerals or digits ; of the punctuation and exclamation and interrogation points, some forty-six in all. With these she could express the vni.] MOTOR NERVOUS CENTRES. 509 name of everything, of every thought, of every feeling, and all the numberless shades thereof. She had thus got the * open sesame' to the whole treasury of the English language. She seemed aware of the importance of the process ; and worked at it earnestly and inces- santly, taking up various articles, and inquiring by gestures and looks what signs upon her fingers were to be put together in order to express their names. At times she was too radiant with delight to be able'to conceal her emotions. " It sometimes occurred to me that she was like a person alone and helpless in a deep, dark, still pit, and that I was letting down a cord and dangling it about, in hopes she might .find it ; and that finally she would seize it by chance, and, clinging to it, be drawn up by it into the light of day, and into human society. And it did so happen : and thus she, instinctively and unconsciously, aided in her happy deliverance. After she had mastered the system of arbi- trary signs, made by the various positions of the fingers used by deaf- mutes, and called dactylology, the next process was to teach her to recognize the same signs in types, with the outlines of the letters embossed upon their ends. Thus with types, two embossed with p, two with , one with e, and another with *', she could, by setting them side by side in the quadrilateral holes in the blind man's slate, make the sign of pen or pin, as she wished ; and so with other signs. " The next process was to teach her that when a certain kind of paper was pressed firm'y upon the ends of these types, held close together, and side by side, there would be a tangible sign on the reverse of the paper, as pin or pen, according to the position of the three types ; that she could feel this paper, distinguish the letters, and so read ; and that these signs could be varied and multiplied, and put together in order, and so make a book. " Then she was provided with types having the outlines of the letters made with projecting pin-points, which, when pressed upon stiffened paper, pierced through, and left a dotted outline of each letter upon the reverse side. This she soon ascertained could serve for writing down whatever she desired, and be read by herself ; and also could be addressed to friends, and sent to them by mail. " She was also taught to write letters and words with a lead pencil, by the aid of the French writing-board, which is the most simple, most effective, and cheapest method ever yet invented. This apparatus is made out of a piece of stiff pasteboard of the size of a ccmmon sheet of letter-paper, and has grooved lines or channels, about the eighth of an inch deep, running, an inch apart, trans- 23 THE PHYSIOLOGY OF MIND. [CHAP. versely across the pasteboard plate. This pasteboard is inserted between the two pages of a common sheet of letter-paper, and the first leaf is pressed with the forefinger into the grooves. This leaves depressions or channels, the upper and lower edge of which can be felt by the pencil-point, and this, a little pressed, leaves it marked with an o, or an /, or a /. The sides of the grooves also give to the paper which is pressed between them rounded edges, so that the \ encil can slide upwards and downwards over and under' them, and also be guided from left to right. " It would occupy more space than can be spared here to explain how, after she had learned the names of substantive nouns, or names of things in the concrete, she came to understand words expressive of the various material or moral qualities thereof. The process was slow and difficult, but I was so aided by her native shrewdness and her love for learning new things that success followed. For instance, she knew that some girls and women of her acquaintance were very sweet and amiable in their tempers, because they treated her so kindly, and caressed her so constantly. She knew, also, that others were quite different in their deportment ; that they avoided or repelled her, and were abrupt in their motions and gestures while in contact with her ; and might be called, therefore, sour in their tempers. By a little skill she was made to associate in her mind the first person with a sweet apple, the other with a sour apple, and so there was a sign for a moral quality. This is a rough illustration ; but it is hard to explain the process by which any children come to understand the names of things in the abstract, or moral qualities. Success came of faith, and patience, and reliance upon her having the native desire and capacity for acquiring a complete arbitrary language, which desire had now become quickened to a passion for learning new signs. Moreover, I was greatly aided from the start by young lady teachers, who became in love with the work, and devoted themselves to it with saintly patience and perseverance. Then great assistance was given by the blind pupils, many of whom learned the manual alphabet and took every opportunity of using it and conversing with Laura. Thus early in the process the material and moral advantages of language began to show them- selves. Without it the girls could only manifest their interest in Laura, and their affection for her, as one does with a baby, by caresses, sugar-plums and other gifts, and by leading her up and down, and helping her in various ways. With it they began human intercourse through regular language. " And so she went on, diligently and happily, for a score or more of years, until at last she acquired a large vocabulary of words, and viii.] MOTOR NERVOUS CENTRES. 511 could converse readily and rapidly with all deaf-mutes, and all persons who could use these sigas. She could read printed books readily and easily, finding out for herself, for instance, any chapter and verse of Scripture. She could also read letters from her friends in pricked type, or by the Braille system of points. She could also write down her own thoughts and experiences in a diary ; and could keep up a correspondence with her family and friends by send- ing to them letters in pencil, and receiving their answers either in pricked letters, which she could read by the touch, or letters written with ink or pencil, which would be read to her by some confidential seeing person. "Thus was she happily brought at last into easy and free relations with her fellow creatures, and made one of the human family. " During many years Laura passed most of her time in exercises such as those above described, new ones being devised as she pro- ceeded. She spent as many hours daily in her studies and mental work as was consistent with her health ; but all the rest of the time was given to gymnastics, or learning to handle domestic implements, as the broom, the dish-cloth, and the needle ; to sew, to knit, to braid, to occupy herself in simple hcuse-work, sweeping floors, dusting furniture, making beds ; finally, to more difficult kinds of work, as crochet-work and the like. " In all these things she succeeded so well, that she is now capable of earning a livelihood as assistant to any kind and in- telligent housekeeper who would accommodate her work to Laura's ways. "The method of instruction was of course novel, and the pro- cess long and tedious, extending over several years, until she came to be able to read and understand books in raised letters ; to mark down variously shaped signs upon a grooved paper, and so write letters legible by the eye ; to attain a pretty wide command of the words of the English language, to spell them out rapidly and cor- rectly, and so express her thoughts in visible signs and in good English. To make all this fully understood by specimens of her style as she used the language of childhood, will require a good- sized volume ; and I confine myself now merely to saying that in the course of twenty years she was enabled to do it all. She has attained such facility for talking in the manual alphabet, that I regret that I did not try also to teach her to speak by the vocal organs, or regular speech. The few words which she has learned to pronounce audibly prove that she could have learned more." CHAPTER IX. MEMORY AND IMAGINATION. " You tell me it consists of images or pictures of things. Where is this extensive canvas hung up ? or where are the numerous re- ceptacles in which these are deposited ? or to what else in the animal system have they any similitude? That pleasing picture of objects represented in miniature on the retina of the eye seems to have given rise to this illusive oratory. It was forgot that this representation belongs rather to the laws of light than to those of life ; and may with equal elegance be seen in the camera obscun as in the eye ; and that the picture vanishes for ever when the object is withdrawn." DR. DARWIN, Zoonomia. HITHERTO nothing special has been said concerning memory, although its existence has been necessarily as- sumed, and its nature indicated, in the foregoing pages. No mental development would be possible without it, for if a man possessed it not he would be obliged to begin his conscious life afresh with each impression made upon him, and would be incapable of any education. We cannot perhaps better define memory than, following Locke, as the power which the mind has " to revive per- ceptions which it once had, with this additional perception annexed to them, that it has had them before ; " in other words, as the power or process by which that which has been once known is, when represented to the mind, known as a previous mental experience, that is, is re- cognised. When people speak of ideas being laid up in the memory, they of course speak metaphorically ; there CHAP, ix.] MEMORY AND IMAGINATION. 513 is no such repository in which ideas are stored up, ready to be brought out when required for use ; when an idea which we have once had is excited again, there is simply a reproduction of the same nervous current, with the conscious addition that it is a reproduction it is the same idea plus the consciousness that it is the same. The question then suggests itself, What is the physical condi- tion of this consciousness ? What is the modification of the anatomical substrata of fibres and cells, or of their physiological activity, which is the occasion of this plus element in the reproduced idea ? It may be supposed that the first activity did leave behind it, when it sub- sided, some after-effect, some modification of the nerve element, whereby the nerve circuit was disposed to fall again readily into the same action ; such disposition appearing in consciousness as recognition or memory. Memory is, in fact, the conscious phase of this physio- logical disposition when it becomes active or discharges its functions on the recurrence of the particular mental experience. To assist our conception of what may happen, let us suppose the individual nerve-elements to be endowed with their own consciousness, and let us assume them to be, as I have supposed, modified in a certain way by the first experience ; it is hard to conceive that when they fall into the same action on another occasion they should not recognise or remember it ; for the second action is a reproduction of the first, with the addition of what it contains from the after-effects of the first. As we have assumed the process to be conscious, this reproduction with its addition would be a memory or remembrance. Psychology affords us not the least help in this matter, for in describing memory as a faculty of the mind or the conservative faculty it does no more than present us with a name in place of an explanation. But we do get nearer realities when we go down to the organic aptitude which, Si4 THE PHYSIOLOGY OF MIND. [CHAP. in consequence of an action, there is to the recurrence of a similar action on another occasion. And physiology presents us with many illustrations of such organized aptitudes. Take, for example, the education of our movements : a designed movement is performed at first slowly and clumsily, and it is only by giving great pains to it and frequently repeating it that we acquire the skill to perform it easily and quickly; the aptitude thereto being at last so completely organized in the proper nervous centres that it may be performed without con- sciousness on our part, quite automatically. Thus it appears that memory in this case becomes less conscious as it becomes more complete, until, when it has reached its greatest perfection and is performed with the most facility, it is entirely unconscious. After which, if we are psychologists who are content to rest in words and forbear to pursue the facts which they denote, we must cease to speak of it as memory : it has become custom, or habit, or automatism. But if we go beneath words to the property of the motor nerve-centres whereby they react in a definite way to impressions made upon them, organically register their experience, and so acquire by education their special faculties, we perceive that we have not to do in the higher nerve-centres with funda- mentally different properties of nerve element, but with different functions which depend upon the same fun- damental property. Substitute the highest nerve-centres for the motor nerve-centres, and the complex idea for the complex movement, and what has been said of the latter is strictly true of the former; the idea, like the move- ment, is accompanied with less consciousness the more completely it is organized, and when it has been com- pletely organized it takes its part automatically in our mental operations, being performed, as a habitual move- ment is performed, automatically. ( z ) The physiological condition of memory is, then, the organic process by IX. ] MEMOR Y AND IMA GAVA T10X. 5 1 5 which nerve-experiences in the different centres are registered ; and to recollect is to revive these experi- ences in the highest centres, the functions of which are attended with consciousness to stimulate, by external or internal causes, their residua, aptitudes, dispositions, or whatever else we may choose to call them, into functional activity. Stimulated from without, they con- stitute recognition, that is, cognition with memory of former cognition; stimulated from within, they constitute recollection. It must be borne in mind, as Dr. Darwin remarked many years ago, that in dealing with memory we have to do not with laws of light, but with laws of life, and that the misleading notion of images or ideas of objects being stored up in the mind has been derived from our ex- perience of the action of light upon the retina. If we would understand the laws of organization in the highest nerve-centres, we shall certainly do well to study organic processes generally ; it would be not less absurd to at- tempt to understand the higher processes without giving attention to the lower, than it would be to attempt to build a house without taking pains to lay its foundations securely. It is a plain matter of observation that other organic elements besides nervous elements perpetuate impressions made upon them, which they may accord- ingly in a certain sense be said to remember ; the virus of small-pox, for example, makes an impression upon all the elements of the body, which they never lose, although it becomes fainter with the lapse of time ; in some un- known way it modifies their constitution so that ever afterwards their susceptibilities are changed. The scar which is left after the healing of a wound in a child's finger keeps the same relative proportion to the finger through life, growing as it grows ; for the elements of the new tissue not only renew themselves particle by particle, and thus perpetuate it, but they extend it in relation with 516 THE PHYSIOLOGY OF MIND. [CHAP. the growth of the surrounding parts. Perhaps the most remarkable example of the exceeding impressionability of organic element is afforded fey the minute germ-cell or sperm-cell, which carries in its constitution not only the particular dispositions of the several tissues of the parent, but even, as there is good reason to believe, the particular mood of mind which prevailed at the time of its secretion. We need not brave the fire of psycho- logical scorn by calling this retention of impressions memory, or care greatly what it is called, so long as due heed is given to the fact ; but we may be permitted to perceive in it the same physiological process which, in the cortical layers of the cerebral hemispheres, is the condition of memory, and of habit in thought. More- over, it may be fairly demanded of the psychologists that they be consistent, and that they no longer use the word memory to denote those mental processes which have been so completely organized that they take place without consciousness ; if it be wrong, as they profess, to assume or imply an unconscious memory, it must be still more wrong to assume or imply an unconscious consciousness, as they sometimes do. In any case, the foregoing considerations cannot fail to show how misleading it is to look upon per- ceptions as mere pictures of nature, and upon the mind as a vast canvas on which they are cunningly painted ; the real process is one of organization, and is rightly conceivable only by the aid of ideas derived from the observation of organic development namely, the fundamental ideas of Assimilation of the like and Differentiation of the unlike. Nowhere is it more necessary than in the study of memory to apprehend clearly that what we call mind is the function of a mental organization ; for thereby we get rid at once of many empty discussions which have been carried on without definite result ; as, for example, whether memory x. ] MEM OR Y AND IMA GIN A TION. 5 1 7 is a knowledge of the past, or a knowledge of the pre- sent with a belief of the past, and the like. Moreover, this conception of a mental organization is indispensable to the explanation of the manifold varieties of partial or general loss of memory which are produced by injury, disease, and decay of brain ; for memory is good or bad according to bodily states, is impaired in various ways by disease, decays with the decay of structure in old age, and is extinguished with the extinction of life in the brain. From of old two kinds of memory have been distin- guished, according as the object remembered occurs to the mind spontaneously, or is voluntarily sought for; the former being known as memory proper, the latter as recollection. It is certain that we do recognise this differ- ence, which common language attests, between that which is revived without any effort, and that which we endea- vour to recover by an effort ; and that men differ much, by virtue of natural capacities, both in memory and in power of recollection. No doubt much of the difference in both cases is due to the degree of attention which is given to the subject when it is first presented to the mind, but this will not account satisfactorily for all the difference which is observed ; some persons being able to repeat with great ease a row of figures, a number of dates, or several lines of poetry, after reading them over once, while others fail to do so with equal success after reading them over many times. Extraordinary instances have been recorded of this exactness of memory for de- tails reaching back to the earliest periods of life. I have seen an imbecile in the Earlswood Asylum for idiots who can repeat accurately a page or more of any book which he has read years before, even though it was a book which he did not understand in the least ; and I once saw an epileptic youth, morally imbecile, who would, shutting his eyes, repeat a leading article in a nswspaper S i8 THE PHYSIOLOGY OF MIND. [CHAP. word for word, after reading it once.* This kind of memory, in which the person seems to read a photographic copy of former impressions with his mind's eye, is not indeed commonly associated with great intellectual power; for what reason I know not, unless it be that the mind to which it belongs is prevented by the very excellence of its power of apprehending and recalling separate facts from rising to that discernment of their higher relations which is involved in reasoning and judgment, and so stays in a function which should be the foundation of its further development ; or that, being by some natural de- fect prevented from rising to the higher sphere of com- prehension of relations, it applies all its energies to the apprehension of details.f Certainly one runs some risk, by overloading the memory of a child with details, of arresting the development of the mental powers : stereo- typing details on the brain, we prevent that further de- velopment of it which consists in rising from concrete perception to conception of relations. However, it must be allowed that there have been a few remarkable in- stances of extraordinary men who have combined a wonderful memory for details with the possession of the highest intellectual powers.^ If we now proceed to examine closely the nature of recollection, it will be found that the difference between it and simple memory is not fundamentally so great as appears on the surface. When we voluntarily try hard * I have been informed of a similar case in which the person could repeat backwards what he had just read. f We know that the convolutions consist of several layers or strata, the higher of which may be presumed to have higher functions than the lower ; it is possible that in the defective brain of the idiot these higher strata of cells and fibres may be imperfectly developed or altogether wanting. i Macaulay may be cited as a remarkable instance ; for in him great intellectual powers were associated with an extraordinary memory for words, dates, facts, &c. tx.] MEMORY AND IMAGINATION. 519 to remember something which has been forgotten, and succeed in the end, the actual rsvivai is done uncon- sciously and, as it were, spontaneously ; for it is plain that if we were conscious of what we want we should not need to recollect it, inasmuch as it would already be in possession ; and it is furthermore plain that a defi- nite act of volition recalling it must imply a conscious- ness of it, inasmuch as it is impossible to will what we are not conscious of. Arbitrary recollection by an act of will is therefore nonsense. What we really do when we try to recollect is to apply attention to words or ideas which have, in our past experience, accidental or es- sential relations to, or associations with, the forgotten word or idea, voluntarily to keep these ideas active by making them consciousness, and to trust to their power of awakening into activity that which it is desired to recall ; indeed, it is notorious that the best way of succeeding is, having held the related ideas energeti- cally in attention for a time, to allow the thoughts to pass to other things, when the lost idea will, after a longer or shorter time sometimes indeed after days recur to the mind. The actual process of reproduction is therefore one of simple or spontaneous memory ; we prepare the way for it by stimulating into action the related ideas, but we positively interfere with its success if, by continuing to keep them in attention, we do not permit them to do their work spontaneously ; the reason of this being that we thereby, as set forth in a former chapter, hinder the propagation of their activity to other nerve- circuits. We shall understand this the better if we realize that consciousness is the result of a certain activity of idea, not driven to it but drawn by it, and get rid of the metaphysical notion that it is some mysterious power which we direct voluntarily to the idea in order to make it active. It will not be amiss, before passing from this subject, to 520 THE PHYSIOLOGY OF MIND. [CHAP. take note of and to ponder that certainty which, in try- ing to recollect something, we have of our possession of what we are thus striving to regain consciously, though we are not conscious what it is. We have the clearest conviction that, although we have forgotten it, we still have it and may recover it. How comes it to pass that we are so sure of the existence of that of which we are not conscious ? In the first place, it would appear to supply an argument in support of the theory that some- thing has been left behind in the nerve-circuit ministering to the forgotten idea, in other words, retained by it, which differentiates it from other nerve-circuits, disposes it to a repetition of its former activity, and produces the conviction of a latent possession, even when it is not active, or at any rate not active enough to awaken con- sciousness. In the second place, it must be remembered that the forgotten idea had associations with other ideas, which are really part of its meaning ; it may well be, there- fore, that when these are active and occupy the attention, while it remains inactive and below the horizon of con- sciousness, there is a tendency or sort of effort to reopen the former paths of association, in order to their com- pleteness to make the circuit, so to speak ; and that it is the consciousness of this tendency or effort which gives rise to the certainty which we have of something for- gotten. Certain it is, that when a stimulus excites one of two movements which have taken place together or in succession on former occasions, there is a tendency, when the stimulus is powerful or continued, to the re- production of the associated movement ; there is a diffu- sion of the stimulus along the accustomed path to the associated motor centres, and a synergy of movements is the result. A piece of poetry which has been thoroughly learnt may be repeated mechanically, as a tune may be whistled, when the proper verbal movements have been once started ; indeed, the repetition in such case is most ix.] MEMORY AND IMAGINATION. 521 successful when consciousness is not too much occupied with it ; for it frequently happens, if we think about the words which we are repeating, that we become uncertain and forget, and are obliged, in order to succeed, to begin again and to allow the succession of movements to go on automatically. We impede the operation of the spon- taneous memory, upon which we really depend, when, by maintaining the activity of a word in consciousness as attention, we hinder the propagation theieof to the asso- ciated nerve-circuits. When a person who is conscious of an idea is striving to revive a related idea which he has forgotten, he presents an example of memory in the making ; for he is striving to revive the yet incomplete organic union between them, which was the result of the original apprehension of their relations, and which, when complete, will cause the one idea to recall the other instantly and without the least effort, just as a single sensation of an object at once re- vives the cluster of sensations which are combined in the perception of it. The process of intellectual de- velopment consists in the mental organization of related ideas, as internal representatives of external relations in nature, and in making this organization so complete that a number of associated ideas shall act like a single idea, being combined into a complex product and recalled instantly and without conscious effort, just as a complex movement is. Then the memory is so complete that we must cease to call it memory, because it is unconscious. In fact, spontaneous recollection is at an end when in- voluntary memory begins, and involuntary memory merges gradually into a reproduction of former mental experiences which is as completely automatic as the habitual movements of our daily life. And well it may be ; for the same organic property of nerve element indeed, I might say, the same fundamental property of organization is at the bottom of both. 522 THE PHYSIOLOGY OF Ml M). [CHAP. Thus much concerning the nature and function of memory. Upon its basis rests the possibility of mental development, in which there are, as we have already seen, the organic registration of the simple ideas of the senses ; the assimilation of the like in ideas which takes place in the production or evolution of general ideas ; the assimi- lation of the properties common to two or more general ideas into an abstract idea ; the special organization, or differentiation, or discrimination, of unlike ideas; the organic combination of the ideas derived v from the differ- ent senses into one complex idea, with the further mani- fold combinations of complex ideas into what Hartley called duplex ideas. In fact, no limit is assignable to the complexity of combinations which may go to the formation of a compound idea. Take, for example, the idea of the universe. But how comes it to pass that a new imaginative creation of the mind, to which nothing in nature answers, is effected? By the same process fundamentally as that by which our general and abstract ideas are formed. For when we consider the matter, it appears that there are no actual outside existences an- swering to our most abstract ideas, which are, therefore, so far new creations of the mind ; in their formation \ there is a blending or coalescence of the like relations in two concrete ideas the development of a concept , ' there is, as it were, an extraction of the essential out of the particular, a sublimation of the concrete; and, by the creation of a new world in which these essential ideas supersede the concrete ideas, the power of the mind is most largely extended. Now, although there are no concrete objects in nature answering to these abstract ideas, yet these are none the less, when rightly formed, valid and real subjective existences expressing or signifying the essential relations of things, as the flower which crowns development expresses the essential nature of the plant. Thus it is that we rise from the ix.] MEMORY AND IMAGINATION. 523 idea of a particular man to the general idea of man, and from that to the abstract idea of virtue as a quality of man ; so that for the future we can make use of the abstract idea in all our reasoning, without being com- pelled to make continual reference to the concrete.* Herein, be it remembered again, we have a process cor- responding with that which ministers to the production of our motor intuitions ; the acquired faculty of certain co-ordinate movements by means of which complicated acts are automatically performed, and we are able to do, almost in the twinkling of an eye, what would cost hours of labour if we were compelled on each occasion to go deliberately through the process of special adaptation, is the equivalent, on the motor side, of the general idea by which so much time and labour are saved in reason- ing : in both cases there is an internal development in accordance with fundamental laws, and the organized result is, as every new phase of development is, a new creation. Creation is not by fits and starts, but it is continuous in nature. These considerations are of the utmost importance in respect of the nature of Imagination, which must ever be incomprehensible on the mischievous assumption of ideas being pictures or images of things painted on the mind by memory. Though imagination is certainly de- pendent on memory, there is unquestionably something more in imagination than memory only ; it is not repro- ductive only, as memory is or should be, but productive; it brings back the old, but with a new form that is, is * Not overlooking, as so many do, that the meaning of the general or abstract is to be sought in the concrete, not the interpre- tation of the concrete in the general or abstract. If we have any doubt about the meaning of an abstract idea, or doubt whether it has any meaning, we ought to trace it downwards to its root in per- ception, and discover its meaning there ; above all we ought not to convert it into an objective entity, and then to spin webs of argu- ment concerning it as the schoolmen did. 524 THE PHYSIOLOGY OF MI\'D. [CHAP. productive as to form, reproductive as to material. When any one affirms that he can imagine something as, for example, some animal of which he has not had experi- ence, what he does is to combine into one form certain selected characters of different animals of which he has had experience ; creating in this way, as nature is con- tinually doing, new forms out of old material. When the artist embodies in ideal form the result of his faithful observation, he has, by virtue of that mental process through which general ideas are formed, abstracted the essential from the concrete, and then by the shaping power of imagination given to it a new embodiment. In every great work of art, poem or painting, there is thus an involution of the universal in the concrete : it is pregnant in its meaning, yielding a wide range to the action of another's imagination when he contemplates it. If it is merely a copy or exact reproduction of nature, it is clever artifice rather than great art, and excites a feeling of gratified interest at the skill displayed rather than vague and elevating emotions of sympathy with a deep truth embodied in beautiful form. So it is that high art does not express anything essentially evanescent : it confers on the moment the steadfastness of eternity, representing the " shows of nature frozen into a motionless immor- tality." The man of science, who unlocks the secrets of Nature by means of observation, experiment, and re- flection, thus systematically training his mind in con- formity with Nature by exact interrogation and faithful interpretation of her works, foresees future combinations, and when he proceeds to react upon nature, is enabled, by means of a scientific imagination thus carefully culti- vated, to construct wonderful works of art that are truly an advance upon, or a development of, nature new creations ; forming combinations in harmony with these real and essential relations of things which he has by patient and sympathetic observation made a part of the ix.] MEMORY AND IMAGINATION. 525 furniture of his mind, he creates something which is a result of the nisus of evolution working in him, a pro- gress of nature through him, and which serves ever after- wards to inform, elevate, and better mankind. What else then, fundamentally, is the true imagination but the nisus of nature's organic development displaying itself in man's highest function ? It is the evolution of the mental organization. What is human art but nature developed through man ; nature as it has been moulded by the infused spirit the inspiration of man? In- formed of nature, in turn he informs nature. There is going on a recreation of nature by human means, but nature makes the means.* The productive or creative power of Imagination, which seems at first sight to be irreconcilable with knowledge gained entirely through experience, is then at bottom another, though the high- est, manifestation of that force which impels organic development throughout nature ; and the imagination of any one either creates truly, or brings forth abortions and monstrosities, according as the mind is well stored with sound knowledge and has true concepts, or as it is inadequately furnished with knowledge and has erroneous concepts according, in fact, as the individual is or is not in harmony with nature. In order to the full function of imagination, in order, that is, that it may combine into new form, according to higher laws, the ideas and feelings which have been fur- nished by the senses and the bodily organs it is plainly indispensable that the several pre-necessary mental opera- * " Yet nature is made better by no mean, But nature makes that mean ; so, over that art, Which, you say, adds to nature, is an art That nature makes This is an art Which does mend nature change, rather : but The art itself is nature." Winter's Tale. 526 THE PHYSIOLOGY OF MIND. [CHAP. tions should be performed correctly: it is essential, in fact, that there should be, in the first place, accurate perception that the mind or brain should respond truly and ade- quately to impressions ; secondly, that there should be accurate memory, the mind retaining or registering accu- rately what has been received ; thirdly, that there should be good recollection, the mind being able to reproduce and use with ease and completeness what it possesses ; and that, lastly, the mind or brain should be endowed with fttel productive power by which it is enabled to combine and create. Though a person may be capable of per- forming well the first three mental operations, if he have not also productive power, he is incapable of the highest imagination ; he lacks the highest function of mind. He may be able to gather material together, but he can- not truly combine it, according to mental laws, into a true creative product ; for production is not merely a binding together of material, but an organic combining and de- velopment of it As Wieland aptly remarked, the eyes of Juno, with the nose of Apollo, the brow of Minerva, and the smile of Venus, would form an absurdity, not a masterpiece of fancy ; it would be like a mixing together of several chemical elements that would not combine, not a combination of them into a new product having properties unlike those of its constituents. When we look back through the lower forms of mind we find that this productive or plastic power in- creases with the increase of mind. So far as we can judge, the imagination of animals is mainly, if not en- tirely, reproductive ; when they dream, as dogs evidently sometimes do, it is presumably memory rather than imagination which is at work. The imagination of savages is certainly much more limited to reproduction than that of highly civilized persons ; it is occupied with the ideas of perception, or with such incongruous and often gro- tesque mixing together of ideas as may serve for an ix.] MEMORY AND IMAGINATION. 527 explanation of natural phenomena that are not understood. The imagination of young children is very much like that of savages, and they are pleased and satisfied with the same kind of fabulous explanations of phenomena. In dreaming, the imagination commonly runs riot, wildly mixing together incongruous ideas into the most absurd forms, but still evincing its wonderful shaping power in the vivid dramas which it represents. In the man of genius, whose mind is in intimate sympathy with the laws of nature and strong with their strength, imagination shapes truly, for it is nature working in him ; it is the highest display of organic evolution, and, like nature, works unconsciously. ( a ) Although there is something more in imagination than perception and memory, which are its necessary founda- tions, it may be remarked that many times much of what we call memory is really imagination. When we think to recall the actual, the concrete, it is often the ideal, the general, that we reproduce ; and when we believe that we are remembering, we are often wwremembering, being swayed by the feelings of the moment which colour our remembrance, and unable to reproduce the feelings of the past under which we had the actual experience. How much of perception too is actually imagination ! The past perception unavoidably mingles in the present act, prevents us often from discriminating minute differences which exist, and thus causes us to perceive wrongly or observe incorrectly. What shall be admitted as a. fact in scientific observation depends entirely upon the ob- server's previous knowledge and training. So strong is the disposition to assimilate a previous observation with a past perception, to blend together the like in two ideas, that it is the easiest thing in the world to overlook those special differences which demand a discrimina- tion or organic differentiation ; there is, indeed, as great a danger of hasty generalization in perception as there is $28 THE PHYSIOLOGY OF MIND, [CHAP. in reasoning. That which in a present perception is the like of something in a former perception easily stimulates the same nervous current, which accordingly occupies attention, to the neglect or overlooking of that in which the perceptions are unlike ; whence it frequently happens that a misperception occurs, and that facts not the same are declared to be the same. It is always a pleasure when a new experience blends with an old one ; if a new observation will not easily assimilate with existing ideas, there is a feeling of dissatisfaction and of positive dis- comfort, and one is apt to pass the unwelcome fact by. But if a proper mental training prevents such neglect, the fact is deliberately appropriated or registered as a special fact, although small satisfaction is felt in the martyrdom of thus registering it, isolated as it appears ; after a while, however, other observations cluster about it, some blending with it, others connecting it with ideas to which it seemed entirely unrelated, until this pariah of the mind is found perhaps to bridge over a gap in knowledge, and organically to unite distant ideas. It may be supposed, indeed, that while this is going on its nervous- substratum is forming its organic connections in the plexuses of the convolutions. The habit of observing accurately, of carefully noting minute differences, and of scrupulously registering them so as to effect an exact internal corre- spondence with external specialities, is indispensable to the true cultivation of mind. When a past perception of a fact vitiates a present per- ception, it is hardly correct to ascribe the erroneous per- ception to imagination ; it is really a false perception arising from imperfect observation and hasty generaliza- tion j but when the fact that has been erroneously or im- perfectly observed is used in inference to warrant an anti- cipation or prediction, then certainly imagination is at work, and future observations are likely to be falsified by the erroneous anticipation or theory of what will be seen. U. j MEMOR Y AND IMA GIN A T10N. 529 That is what we mean to imply when we say of an un- trustworthy scientific observer that he resorts to his imagination for his facts ; his present observation is viti- ated by the perverting influence of an incorrect theory based upon imperfectly observed facts. Accurate per- ception and exact memory are the fundamental basis of sound reasoning and imagination. As we perceive more accurately, so shall we remember more correctly, judge more soundly, and imagine more truly. The habit of hasty and inexact observation, the unwarranted blending of residua that are not truly like, is necessarily the founda- tion of a habit of remembering wrongly ; and the habit of remembering wrongly is of necessity the cause of incor- rect judgment and of erroneous imagination : exact in- ternal correspondence and external relations being the basis of an imagination true to nature, in other words, of a true organic mental development. For these reasons, " the whole powers of the soul may," as Hartley observes, "be referred to the memory, when taken in a large sense. Hence, though some persons may have strong memories and weak .judgments, yet no man can have a strong judgment with a weak original power of retaining and remembering." If the imagination have not a sound basis in habits of accurate observation, it degenerates into fancy ; a term which, though originally it was considered to mean the same thing as imagination, is now used to denote a well- founded difference.* Fancy represents the productive or creative power of imagination working without that due restraint of law which is imposed upon its operation by habits of accurate observation, and without that proper and sufficient material of facrs which such obser- * Imago, image, imagination, were once synonymous with ^airrarr/^a, phantasm, fancy ; it is interesting to note how the latter have now received their special meanings, phantasm being an illusion or hallucination, and fancy a riotous imagination. 530 THE PHYSIOLOGY OF MIND. [CHAP. ration furnishes ; consequently it wildly or whimsically yokes together by means of accidental coincidences things that have no essential relations to one another. The productive power of imagination can create form, but cannot create the material with which it must work ; for that it must go to nature ; nor will it create true forms unless it be itself informed by nature. Yellow and blue mixed together produce green ; " but he who has never seen this colour," says Feuchtersleben, " can never create it in his fancy." Thus, in regard to the highest mental function as in regard to the lowest, we perceive that man is a complex medium, through which impressions are translated into action; he is a complex and intricate mechanism of so-called reflex function. As organic growth and development take place in obedience to the laws of nature, and yet constitute an advance upon them, so it is with the well-cultivated or truly developed imagination, which brings together images from different regions of nature, yokes them together by means of their occult but essential relations, and, thus making the whole one image, gives a unity to variety displays the one in the many: there is an obedient recognition of nature, and there is a develop- mental advance upon it This esemplastic faculty, as Coleridge, following Schelling, named it, has been fanci- fully supposed to be indicated by the German word for imagination, namely, Einbildung> or the one-making faculty* Its highest working in our great poets and philosophers really affords us an example of creation going steadily on as a natural process ; and creative or productive activity is assuredly the expression of the highest mental action : whosoever has such capacity has more or less genius ; whosoever has it not will do nothing original, though he work never so hard. What an amount * More correctly Ein for en (in), and Bildung (formation,) in- ternal image, i.e. imagination. ix.] MEMORY AND IMAGINATION. 531 has been unwisely Avritten by the sedulous followers of a so-called inductive philosophy in disparagement of imagi- nation and in favour of simple observation 1 " Men should consider," says Bacon, " the story of the woman in ALsop, who expected that with a double measure of barley her hen would lay two eggs a day ; whereas the hen grew fat and laid none." It were as wise in a man to load his stomach with food which it cannot digest, as to load his mind with facts which it cannot digest and assimilate. It is in the great capacity which it has of assimilating material from every quarter, and of develop- ing in proportion, that the superiority of genius consists ; and it is in the excellence of its creative imagination, whether poetic, artistic, philosophic, or scientific, that its superior energy is exhibited. Because the least things and the greatest in Nature are indissolubly bound together as equally essential parts of the mysterious but harmonious whole, therefore the intuition into one pure circle of her works by the high and subtile intellect of the genius contains implicitly much more than can be explicitly displayed in it ; and therefore it comes to pass at times that, in the investiga- tion of a new order of events by an intellect which is in genial sympathy with nature, the law of them explicitly declares itself as by a flash of intuition, after compara- tively few observations. The imagination successfully anticipates the slow results of patient and systematic research, flooding the darkness with the light of a true interpretation, and thus illuminating the obscure relations and intricate connections. Therein a well-endowed and well cultivated mind manifests its unconscious harmony with nature. The brightest flashes of genius come un- consciously and without effort : growth is not a voluntary act, although the gathering of food is. Certainly the intuition of truth can never be the rule amongst men, inasmuch as the genius capable of this 532 THE PHYSIOLOGY OF MIND. [CHAP. rapid and brilliant intuition, so far from being common, is a most rare exception amongst them. And the result, however brilliantly acquired, can never be safely accepted as lasting, until it has been further subjected to the tests of observation, experiment, and logical reasoning, until it has undergone verification. The man of genius who has revealed a great truth may perhaps, on some other occasion, promulgate an equally great error. Not, how- ever, is this likely to happen often : for a well-trained intellect is truly a most delicate, potent, and finished in- strument, which has been fashioned with great pains and skill, and which, when applied to the investigation of any department of nature, places its possessor at an enormous advantage over one who is not so gifted ; not otherwise than as one who uses a microscope or a telescope has vast advantages over him who uses his naked eye only. Happily his errors, if they are made, are indirectly most useful ; for the experiments and observations provoked and directed by them, and prosecuted for the purpose of displaying their instability, often lead to valuable dis- coveries. Mischief is undoubtedly wrought by the rash promulgation of ill-grounded theories on the part of those who have neither superior original capacity, nor a mind well stored with the results of observation, nor an imagination properly cultivated. It is the ignorant only, however, whom such persons deceive : those who possess an adequate knowledge of the subject can usually detect in the unwarranted theory the exact amount of know- ledge which its author has had, and the character of the defect in the reasoning by which it is supported. Those who take a philosophical view of things, and look upon the progress of human knowledge as a development which is going on continuously through the ages, will find it conformable to their experience of every other form of vital growth that there should be, coincidently with advance, a retrograde metamorphosis, degeneration, or ix.] MEMORY AND IMAGINATION. 533 corruption of that which is not fitted for assimilation, and which is ultimately rejected ; for as the body dies daily as the condition of its life, so false theories and corrupt doctrines are conditions of the progress of knowledge. In the growth and development of the body there is a correlative degeneration or retrograde metamorphosis of organic element going on a daily death in strict relation with the activity of life ; so likewise in the organic growth of thought through the ages, there is a corresponding decay or corruption of erroneous doctrines a death of the false in strict relation with the growth of the true ; thus healthy energy throws off effete matter, which, in the very act of undergoing decay, gives up force that is avail- able for the development of the higher doctrine which supersedes it. That men should evince a distrust of hasty generalization, and an unwillingness to accept new doctrines, is a healthy manifestation of the self-conserva- tive instinct of their nature ; for this aversion from new things prevents the human mind from being led astray by every vain and windy doctrine, opens the way for criticism and verification, and thus in the end promotes a sound development. Not in the individual, however, where so much active change takes place in so short a time, will the regular corruption and decay of false doctrines be clearly perceived, but in the historical development of the race, where the gradual evolution of mind may be observed and traced in its successive stages. Thus much concerning memory and imagination, the examination of which reveals, better perhaps than the analysis of any other of the so-called mental faculties, the complex organization which mind really is. It re- mains only to add, that the manifold disorders to which memory is liable illustrate in the most complete manner its organic nature. Its disorders are numberless in degree and variety ; for not only every degree of dulness, but every variety of partial loss, as of syllables in a 24 534 THE PHYSIOLOGY OF MIND. [CHAP. particular word, of certain words, places, names, is met with in particular cases. So various and numerous are its possible defects, that it has not yet been practicable to reduce them to any system, although it is probable that a careful classification of them would be a most useful contribution to the construction of a mental science. All that we can at present conclude from them is, first, that memory is an organized product ; and, secondly, that it is an organization extending widely through the cortical layers of the cerebral hemispheres. It is easy (o observe that differences exist in different persons in the character of the organic function which ministers to memory : one man, for example, has a good memory for particular facts, but is no way remarkable for reasoning power, or is even singularly deficient therein the regis- tration of the concrete impressions taking place with great ease and completeness, but the further digestion of the residua not being accomplished ; another, on the other hand, has no memory for particular isolated facts, they must have some relation to ideas already appro- priated, or must fall under some principle, if he is to recollect them ; in this case the digestion of residua is well effected, so that there exists a great power of gene- ralization. The latter is the memory of intellect; the former, as I have already pointed out, is not unfrequently the memory of idiots. It is well-known that memory is greatly affected by bodily states : it differs much at different times ; and in a state of complete bodily exhaustion from temporary causes it may sometimes become a com- plete blank for a time, being restored to its accus- tomed function with the restoration of bodily vigour. These occasional variations in its function are of no great moment ; they merely prove that memory, like any other bodily function, is well and easily, or ill and pain- fully, performed according to the state of the general ix. ] MEMOR Y AND IMA Gf.WA TION. 535 health. But it must also be borne in mind that some flaw in the memory, some breach in its exquisite organization, is one of the first indications of a disorder or degenera- tion of the nerve element of the cortical layers. Its slight, early affections are very apt to be overlooked, forasmuch as they do not reveal themselves in a con- scious inability to remember something, but i/i an un- conscious deterioration of the highest mental functions, and especially of the moral sense. The most delicately organized residua, representing the highest acquisitions of organic evolution, are here the first to attest by their sufferings any interference with the integrity of nerve- element, just as disorders of the most delicate and complex associated movements of the spinal cord are the first to declare the commencing degeneration of its centres. There is a decomposition or undoing of that which constitutes the latest and highest mental develop- ment an analysis of it, so to speak ; disease rudely unravelling that which has been intricately and delicately woven into a complex woof of associated nervous plexuses. Long before there is any palpable loss of memory in insanity, even before an individual is re- cognised to be becoming insane, there is a derangement of his highest reasoning and of his moral qualities ; his character is seen to be more or less altered, though what the exact change is cannot perhaps be described in words ; as it is said, " he is not himself." If the degene- ration of nerve element proceeds we witness successively every stage of declension in the disorder of the complex organization of the memory ; namely, manifest perversion of the higher social feelings, next greater or less destruc- tion of the organic connexions of ideas, whence follows incoherence of thought, and, finally, general forgetfulness, declining into complete abolition of memory. It is not difficult to understand how it is that the old man sometimes has a tenacious memory of the past, and 536 THE PHYSIOLOGY OF MIND. [CHAP. reasons tolerably correctly with regard to it, when he cannot duly appropriate and rightly estimate the present The brain, like every other organ of the body, suffers a diminution of power of activity with the advance of age ; it is less supple, its ideas, like the movements which it dictates, being performed slowly and stiffly ; it reacts to impressions with less and less vigour and vivacity, and there is less and less capacity to assimilate the influence of them, so that there ensue dulness of perception and an incorrect appreciation of events. Meanwhile, how- ever, the past is a possession which is incorporated in the organic nature of the brain, and may be sufficiently remembered, though perhaps with less vivacity than formerly, when the latest impressions have been ob- literated by " decay's effacing finger." It is easy, again, to perceive how it is that children, like animals, live almost entirely in the present ; they have no store of ideas organized in the mind which can be called into activity to influence the present idea, and they react directly to the impressions made upon them. The best possible evidence of the gradual process of mental or- ganization is indeed afforded by the mental phenomena of young children ; for, the residua of impressions not being completely organized, their memory is fallacious, and, a firm organic association between ideas not being established, their discourse is incoherent. The old man and the child both fail in judgment : the former, because he has forgotten more or less of the past, and has lost the standard by which to measure the present perception, or because he cannot perform accurately the present perception, and measures it entirely by the past ; the latter, because it has not yet any past. By the neces- sity of the case almost, an old man becomes conservative and the laudator temporis acti ; for the evolution of events goes on when his nature has ceased to assimilate and develop ; he has accordingly no sympathy with them, IX.] MEMOR Y AND IMA GIN A TION, 537 shrinks from contact with them, and querulously brands as revolutionary what is truly evolutionary. It were a grievous thing if old men did not die ; for in that sad case the world's movement onwards to where it is going would be very sluggish, if it were not actually arrested. How different with the youth ! The curtain of life rises, its illusions fascinate him, and he is en- chanted with all he sees ; his nature expands trustfully and joyfully, and though he may often mistake fleeting shows for lasting truths, and come to no little sorrow thereby, yet he assimilates, grows, and develops. Nature Jures him into young enthusiasm of faith and work, and by the time he finds her out in age dispenses with him. I^astly, it will not be amiss to bear in mind, in regard to the organic nature of memory, that we cannot well remember pain. It is certainly possible to remember that we have suffered a particular pain ; but vividly to recall the pain, as we can recall a definite idea, is not possible. And why ? Because the idea is an organized product which abides, while the disorganization or disturbance of nerve element which pain implies passes away with the restoration of the integrity of the nerve centre. To recall an idea is to reproduce the same nervous current which was experienced on the first occasion, to the recurrence of which there is an organic aptitude. To recall a pain as we actually felt it would be to reproduce the condi- tions of disorganization which accompanied it ; and that we cannot do by an effort of will. For the same reason, we cannot easily or adequately recall a very powerful emotion in which the idea or the form has been almost entirely lost in the commotion where, in fact, the storm among the intimate elements has been so great as to be destructive of form : Shakespeare's words, " formless ruin of oblivion," admirably expressing the state of things. When we do strive to bring to mind a particular 53 THE PHYSIOLOGY OF MIND. [CHAP. sensation or emotion, it is by vivid representation of its cause, and consequent secondary excitation of it : we remember the idea, and the idea thereupon generates the emotion or the sensation ; though seldom in so intense a degree as when this was actually experienced. But the sensation of pain is a different matter from the sensation of one of the senses ; it is the outcry of suffering nerve element, and cannot commonly be generated by an idea ; it is not the result of organization, but the token of disorganization. How, then, should it be accurately remembered ? NOTES. 1 (.A 5*4)' "The truth that memory comes into existence when the connections among psychical states cease to be perfectly auto- matic is in complete harmony with the obverse truth, illustrated in all our experience, that as fast as the connections of psychical states which we form in memory become, by constant repetition, automatic, they cease to be part of memory. We do not speak of ourselves as remembering those relations which become organically, or almost organically, registered ; we remember those relations only of which the registration is not yet absolute. No one remembers that the object at which he is looking has an opposite side ; or that a certain modification of the visual impression implies a certain distance ; or that the thing which he sees moving about is a living animal. It would be a misuse of language were we to ask another whether he remembers that the sun shines, that fire burns, that iron is hard, and that ice is cold. .... And similarly, though, when a child, the reader's knowledge of the meaning of successive words was at first a memory of the meanings he had heard given to them ; yet now their several meanings are present to him without any such mental process as that which we call remembrance." HERBERT SPENCER, Principles of Psychology, p. 551. 2 (/ S 2 7)- Jean Paul Richter, in one of his Letters, says : " The dream is an involuntary art of poetry : and it shows that the poet works more with the bodily brain than another man. How is it that no one has wondered that in the detached scenes of dreaming, he puts in the mouth of the actors the most appropriate language, the words most exactly characteristic of their nature : or rather that ix.] MEMORY AND IMAGINATION. 539 they prompt him, not he them ? The true poet even is in writing only the listener, not the language-teacher of his characters. .... Victor's observation that the opponent of his dreams often put before him more difficult objections than a real bodily one, may be made of the dramatist, who can in no manner be the spokesman of his company without a certain inspiration, though he is at the same time easily the writer of their parts. That dream-forms surprise us with answers with which we ourselves have inspired them is natural ; even when awake every idea springs forth suddenly like a spark of fire, though we attribute it to our attention ; but in dreams we lack the consciousness of attention, and we must thus ascribe the idea to the figure before us, to which also we ascribe the attention " Again: "Das Machtigste in Dichter, welches seinen Werken die gute und die bdse Scele einblaset, ist gerade das Unbewusste." Aesthtttk. Carlyle, whose writings exhibit in a marked degree the influence of Jean Paul and Goethe, says of Shakespeare: "Shakespeare is what I call an unconscious intellect ; there is more virtue in it than he is himself aware of. His dramas are products of Nature, deep as Nature herself. It is Nature's highest regard to a true, simple, great soul, that he gets thus to be a..patt of lurself. Such a man's works, whatever he with utmost conscious exertion and forethought shall accomplish, grow up withal wwconsciously from the unknown deep in him, as the oak-tree grows from the earth's bosom, as the mountains and waters shape themselves.'"' Dr. Brown (Philosophy of the Mind, p. 200), when enumerating what he calls the Secondary Laws of Suggestion, lays much stress on constitutional differences in individuals the differences of Genius, Temper, or Disposition. The tendencies in some minds are wholly to suggestions of proximity ; in other minds there is a powerful tendency to suggestions of analogy. It is in this latter tendency to the new and copious suggestions of analogy that the distinction of genius appears to consist ; a mind in which it exists is necessarily inventive ; " ior all to which we give the name of invention, having a relation to something old, but a relation to that which was never before suspected or practically applied, is the suggestion of analogy." There would be nothing new if objects were to suggest only, accord- ing to proximity, the very objects that had co-existed with them ; but there is a perpetual novelty of combination, when the images that arise after each other, by that shadowy species of resemblance which we are considering, are such as never existed before together or in immediate succession. Hence the rich figurative language of poetry the expressions of resemblances that have arisen silently 540 THE PHYSIOLOGY OF MIND. [CHAP. lx . and spontaneously in the mind ; hence the discoveries and inventions of science, &c. He goes on, too, to point out that this novelty of combination in imagination cannot depend upon the will. It is absurd, he says, to suppose that we can will directly any conception, since, if we know what we will, conception must be already a pait of consciousness. "Hence, in proportion as the memory is enriched and provided with materials, in the same proportion the rational mind, if backed by a happy genius, will be able skilfully, felicitously, and approxi- mately and agreeably to the truth, to distribute its analysis into series, to adjust and conclude them, of many analytic conclusions again to form new analyses, and in the end to evolve its ultimate analyses." SWEDENBORG'S Animal Kingdom, vol. ii. p. 348. In a note he adds "This is corroborated by the common opinion, that the knowledge and intelligence of an individual are in propor- tion to the furniture of his memory. But it does not follow from this, that a powerful memory is always accompanied with ability, or by an understanding of equal grasp. For the faculty of reducing the contents of memory to order is a fresh intellectual requisite. An edifice is not built simply by the accumulation of implements, bricks, tiles, and the materials. These and skill must be tasked to put all things together in their places." INDEX. ABRRCROMMK, Dr. ( 38, 93,312, 93. Absolute, the, TO. Abstraction, the moaning of, 275 ; made into entity, 83, 276, 283, 440, 436. Acid, cerebrinic, 78. Actuation, 463, 466. Affections of mind, 348. Alcmseon, 120. Amphibia, cerebral hemispheres of, 97 Amphioxus, the, 92. Analysis, introspective, 60, 61. Anaximander, 3. Anaesthesia, 316. Annelida, nervous system of, 165. Anthropomorphism, 4. Animals, limited ideas of, 273, 275 ; imagination of, 526. Antithesis, the principle of, 384. Ape, brain of, 103, 261 ; the attention of the, 311. Aphasia, 475 ; morbid conditions of, 477, 478 ; condition of intelligence in, 479. Appetites, 354. Apoplexy, 200, 209. Arc, the sensorial, 98 ; the ideational, 98. Archencephala, the, 107. Aristotle, 5, 7, 63. Assimilation, 237. Attention, effect of, upon sensibility, 398. 313 1 physical basis of, 308 ; nature of, 310 321, 490; voluntary and involuntary, 312; physical con- ditions of, 316. Ante mat ism, 238 : remarkable cane of, 342 ; and memory, 521. B. BABOON, brain of the Chacma, 116. Bacon, Francis, 6, 7, 15, 19, 23, 49, 50, 55. 57. 59. 61, 69, 70, 149, 183, 501, 35 6 . 3 8 3. 47, 433- Bacon, Roger, 7. Fun, Professor A., definition of mind, is6, 133 ; on the germ of locomotive harmony, 153; on spontaneous energy, 170. Beaufort, Sir F., on the feelings dur- ing drowning, 72. Bees, the nervous centres of, 165 : in- telligence of, 240 ; stupidity of, 328. Belief, the nature of, 413, 441 ; manner of reform of, 446. Bell, Sir Charles, on the infant's smile, 153, 473 ; on the infant's ap- prehension of falling. 469 ; on the muscular sense, 487, 493, 506. Beneke, on residua, 20 ; on uncon- scious mental function, 74 ; on con- ceptions, 277. Berkeley, Bishop, on visual language, 312, 23$, 258 ; on the non-existence of matter, 225. Bert.on grafting animal r tructur*s,i47. Bichat, on the seat of the passions, 37, 389. Biography, import of, 13; the study of. 52. Birds, cerebral hemispheres of, 07 : the intelligence of, 99 ; the emo tions of, 99. Blainville, on the effects of environ ment on the organism, 132. Blake, William, visions of, 293. Blindness, 313. Blushing. 317. Bone, transplantation of, 447. Bongos, the superstition of, a. Bonnet, on the nature of ideas, 269. Bosjesman, brain of, 102, 261 ; gesture- language of, 501. Braid, on hypnotism, 388, 479. Brain, organic sympathies of, 35 ; relations of, 40 ; waste and repair or, 40 ; education of, 83 ; development of, 102 ; weight of, 103 ; the quality of, 104 ; the foetal, 106 ; the structure of convolutions of, na 118; reflex function of, iSi. Bridgman, Laura, the case of, 480, 507 ; the account of method of in- struction of, 507511. 542 INDEX. Broca on the seat of articulate lan- guage, 263. Brown, Dr. T., on a physioloiry of mind, 77 ; on co-existence of con- scious states, 304 ; on imagination, 539- Browne, SirT., 107; on the music of the spheres, 408; iranspreciation, Brown-Se'quard, on the production of rigor mortis, 171 ; on the production of epilepsy, 178 ; on reflex delirium, 253. Drunton, Dr. Lauder, on chloroform narcosis, 208. Burke, on the mental effects of mimicking looks and gestures, 473. Burrows, Dr., a case of rtllex dtl.rium, *54- Burton, R. F., 339. CABAMS, on the secretion of thought, 77 ; on the transmission of organic habits, 219 ; on the expression of feelings, 474. Campanella, the physiognomist, 473. Causes, final, 146 149, 156, 183, 432. Cerebrin, 78. Charming, Rev. Dr., on change of character, 448. Character, 336 ; a change of, 362, 447 ; the constancy of, 370 ; transforma- tion, 372 ; its relation to will, 445. Chloroform, action of, 208. Christianity, the moral law of, 404. Clarke, Dr. Lockhart, on the struc- ture of the cerebral convolutions, xia; on the nature of volition, 427. Ccensesthesis, the, 359, 374. Coleridge, 25, 82, no, 530. Colloids, 87. Colour, perception of, 234. Commonwealth, the physiological, 37. Compensation, 400. Comte, Auguste, on the social unit, 53 ; on the received psychology, 70 ; on the relation of organism to en- vironment, 132 ; on the cerebral functions, 262 ; on heredity, 330; on the impulses of action, 358, 407 ; on continuous organic sympathy, 376 ; on egoism and altruism, 390 ; on family feeling, 399; on final causes, 432 ; on language, 505. Concept, the, 273, 522 ; its mechanism, 381. Confucius, 421. ^ Consciousness, interrogation of, x6 42 ; the necessary condition of, 17 ; nature and limits of, 45 ; grades of, 95, 242 ; relation to reflex acts, 138 146 ; relation to sensori-motor acts, 197205 ; relation to mental function, 245 ; states of abnormal, 303 ; co-existence of states of, 304 ; its relation to memory, 521. Convolutions, the cerebral, 101 ; the structure of, 112 118; differentia- tion of, 124 ; morbid changes in, 124 ; the functions of, 261 268. Convulsion, co-ordinated, 485. Corpora striata, functions of, 187. Criminals, the study of, 53. Curare, effects of, 171, Custom, effects of, 220,393. Curier, F. , on the hereditary trans- mission of acquired instincts, 218. D. DARWIN, Charles, on the persistence of instincts, 216; on attention, 311: on the acquirement of mental capa- city by gradation, 330 ; on the ex- pression of the emotions, 380, 383 ; on sexual selection, 404. Darwin, Dr. Erasmus, on sensori-motor actions, 256 ; on ideo-motor actions, 288, 292 ; on the performance of ideas, 307, 341 ; on epilepsy and somnambulism, 347 ; on memory, 512. Deliberation. 309, Delirium, reflex, 253, 254. De Quincey, on opium dreams, 73. Descartes, on the test of a true belief, 1 8 ; on the constant activity of mind, 29 ; his definition of mind, 38, 125 ; exaltation of consciousness, 47 ; automatic actions of animals, 48 ; on final causes, 432. Design, nature of, 146 148, 155, 430. Desire, 353, 357, 390, 434. Development, the law of organic, 7, 13 2 . '33. 33' 45- Dickens, Charles, 2 93- Dionaea muscipula, 140. Discernment, 237. Disease, emotional or affective features of, 375- Distance, intuition of, 201, 468. Doctrine, degeneration or corruption of false, 533. Dreaming, 319, 375, 498 ; imagination in, 527. Dreams, persistence of images of, 292, 297. Drowning, the feelings during, 72. EDUCATION, 84. Edwards, Jonathan, on the will, 422, 459 Effort, the consciousness of, 424. Ego, the conception of the, 224 : modi- fication of, 363, 372 ; the identity of the, 449. INDEX. 543 Emerson, Rnlph W., 553. Emotion, 348 408 ; relation to idea. 348, 361 ; influence of condition of nerve element upon, 358; evolution of, 366; resolution of. 367; basis of, in the organic life, 371, 373 : influ- ence of disease upon, 375 ; influence of stale of blood upon, 378 ; dis- charjfe of. 379 I expression of, 379 388 ; influence of bodily attitude , upon, 387 ; disorder of, 389 ; egoistic and altruistic, 390; the complexity f 39 1 relation of, to will, 451 Entity, conversion of abstraction into, 83. 276, 283, 426. Environment, organic adaptation to, 88, 131, 133. Epilepsy, the artificial production of, 178 ; insanity after, 251 ; the cerebral seat of, 263. Eunuchs, the mental character of, 373. Evolution, intellectu.il, 330 334. Expression, the art of, 498. r. FACULTY, imitative, i6t. Fame, the vanity of, 68. Fancy, the, 529. Faraday, on the formation of hypo- theses, 65. Feeling, social, 364,399 ; aesthetic, 365 ; philosophic, 365; muscular, 376; tribal, 399; egoistic and altruistic, 393 ; moral, 400 404. Ferrier, Dr. D., on stimulation of the cerebral convolutions, 265, 268. Keuchtersleben, on imagination, 530. Fishes, cerebral hemispheres of, 97 ; appearance of ideas in, 98. Flourens, on the removal of cerebral hemispheres. 191, 207. Foetus, the brain of, 106. Foster, John, on change of character, 362 ; on habit, 420. Foxes, acquired cunning of, 218. Foxhunting, barbarity of, 100, Fritsch, Dr., on stimulation of the cerebral convolutions, 265. Function, simplest reflex, 89, 161 ; sen- sori-motor, 94; cerebral reflex, 269, 384, 285. GANGLIA, sensory, 91, 109, 186 256; causes of disorder of, 248 256; in- nate defects of. 248 ; excessive func- tion, 250 ; the supply of blood to, 251; reflex irritation of, 252; trophic influence of cerebral hemispheres on, 355: ttie hemispherical, 159 339. General paralysis, the motor and men- tal phenomena .of, 494. Genius, assimilation by, 34 ; the . quality of, 64 ; the imagination of, 5*7- (nil !!, the, 119. Goethe, i, 59, Oi, 64,68, in, 131, 132, 293. Goliz, on inhibitory function, 145, 173; on the removal of cerebral hemi- spheres, 193. Graham, on colloidal matter, 87. Gratiolet, 99. Gray, ode on Eton College, 386. Gregarinida, the, 105. Griesinger, on psychical reflex action, 181. H. HABIT, 420. Hall, Robert, on materialism. 135. 1 1 a Her, on the sense of smell in negroes, tij. _ Hallucinations, 121, 236, 255, 291, 993, 297, 300. Hamilton, Sir W., the veracity of con- sciousness, 18 ; on latent modifica- tions of mind, 3% 73 ; the meaning of consciousness, 45 ; definition of mind, 126, 133 ; on co-existence of conscious states, 304. Hartley, on secondary automatic move- ments, 150, 184; on reflex cerebral function, 195 ; on the nature of ideas, 469 ; on complex and duplex ideas, 335 ; on different languages, 342 ; on the will, 427, 460 ; on memory, 529. Hartmann, K. von, on unconscious mind, 84. Haschisch, the effects of, 578. Heart, retardation of action of, 173 ; apparent cessation of action of, 341. Helmholtz, on the nature of perception, (23, 227 ; on perception of colour, 234. Hemiplegia, 118. Hemispheres, the cerebral, 93, 97, 259 ; insensibility of, 98 ; convolutions of, 101 ; the removal of, 191 194, 207, 261 ; compensatory action of, 264. Herbart, 352. Heredity, 217, 330, 369. History, the study of, 53. Hitzig, Dr. E., on stimulation of the cerebral convolutions, 265. Hobbes, 121, 277, 301, 309, 340, 341, 347. 352, 46. 427. 4- Howe, Dr. S. C, a case of acuteness of smell, 257 : on the case of Laura Bridgman, 480, 507 511. Huber. on the intelligence of bees, 240. Humboldt, 15, 64 ; on the sense of smell in Indians, 315. Hume, David, on association of ideas, 323 ; on innate idea, 340 ; on will, 461. Hunter, John, on paraplegia, 136; on the effects of attention, 291. 544 INDEX. Huxley, T. H., on differences between brains of ape and of man, 103 ; on the Gregarinida, 105. Hydra, the, 92. Hypnotism, 388, 472. Hypochondria, 377. Hypothesis, the use of, 65. I. IDEA, the essential, 82 ; the cerebral correlate of, 384 ; the action of, upon movement, 287 ; the action of, upon sensory centres, 291 ; the action of, upon nutrition and secretion, 300 ; the action of, upon other ideas, 303 ; different state of evolution of, 338. Ideas, unconscious, 70, 71, 73, 74, 305 ; material, 85 ; first appearance of, 98 ; the nature of, 269 ; general and abstract, 273, 522 ; fundamental or innate, ajj 286, 324334 : like movements, 306 ; association of, 321 ; complex, 335 ; hostility to new, 413 ; power of will over, 436. Ideation, 259, 272 ; mechanism of, 280. Idiosyncrasies, 248. Idiots, the brains of, 104; sense of smell of, 215 ; defective sensibility of, 249 ; remarkable memories of, 58. Imagination, 523 ; conditions of sound, 529 ; difference between fancy and, 529. Individuation, the principle of, 88, xio. Infants, reflex acts of, 137 ; anence- phalic, 137. Inhibition, 145, 163, 318, 442. lunervation, motor, 313 315; feeling of, 425. Insanity, the study of, 52; sensorial, 248, 251 ; moral, 367. _ Insects, the powers of vision of, 209. Instinctive actions, 196, aio. Instincts, 201, 202, 393 ; origin of, 216 221 ; evolution of, 394. Intellectorium commune, is8, 259. Intuition, xi, 59, 333; motor, 267, 463; imaginative, 531. JACKSON, Dr. Hnghlings, on epilepsy, 263. Jews, the national and moral feeling of, 401. K. KANT, on unconscious ideas, 74. Kuhne, on the endings of nerves, 107. Knight, on instincts in animals, 219, L. LAMARCK, on the relation of o'gnnism to environment, 132, 133. Language, analysis of, 5 : study of, 51 ; the seat of, 263 ; origin, nature, and development of, 499506. Lay cock, Dr., on reflex cerebral func- tion, 181. Lecithin, 78, 8r. Leibnitz, on consciousness of free will, 46, 429; on unconscious ideas, 74. Leroy, on the cunning of foxes, 218. Leuret, 09. Levy, W. H., on blindness, 214. Lewes, G. H., on neurility, 89 ; on the law of organic development, 132. Life, mind the highest development of, 43- 5- Lister, Joseph, on the contractions of wtfriss, 108 ; on the movements of pigment granules, 175. Locke, the psychological method of, 47; on spiritual beings, 105; on innate ideas, 440. Longet, on the removal of the cerebral hemispheres, 192. Love, the passion of, 377. Lucas, Dr. Prosper, 215. Luys, on the function of the thalami optici, 187. M. MACAULAY, remarkable memory of, 518. Major, Dr. Herbert, on thfc brain of the Chacma baboon, 116. Mammalia, cerebral hemispheres of, 97- Marshall, J., on the ape's brain, 103 ; on the brain of an idiot, 104. Materialism. 134, 135. Matter, colloidal, 87 ; powers of, 127 ; grades of, 130; the non-existence of, 223. Max Muller, on the analysis of lan- guage, 5 ; on the impossibility of thought without language, 480. Meissner, on scattered nerve-cells, 108. Memory, the basis of, 271 ; persis- tence of, 25 ; nature and function of, 512 523; unconscious, 514; dis- orders of, 534 ; of old age, 536. Mesmerism, 316. Mesnet, Dr. E., on a remarkable case of automatism, 342. Metaphysics, barrenness of, 13. Method, the metaphysical, 3, 4 ; the inductive, 9 H ; the psychological, xi, 60 ; the un on of subjective and objective, 63 ; discussion of, in study of mind, i 7 475 ; physiological mechanism of, 476- Spencer, Herbert, on ideas, 70 ; on organism and environment, 133 ; on memory, 538. Sperm-cell, the, 119. Spinal cord, education of. 160, 163 ; grey, substance of, 164 ; continuous activity of, 162 ; exhaustion and repair of, 157 ; inhibitory function of, 163 ; functions of, 137 182 ; in- stability of, 167 ; excessive stimula- tion of, 169 ; the supply of blood to, 170; reflex irritation of, 173. Spinoza, on final causes, 148, 156, 183 ; on automatic actions, 182 ; on dream- images, 292; his mathematical me- thod, 349 ; on pleasure and pain, 351; on desire, 353 ; on the passions, 394 406 ; on free-will, 409, 430 ; on final causes, 432 ; on will and intelligence. 443. Stewart, PugalJ, 215. Stigmata, 302. Strychnia, effects of, 171, 175 ; deriva- tives of, 171. Substantta cogitans, 125, 133. Sympathies, organic, 373. T. TABES DORSALIS, 489. Tarchanoff, on inhibiting the heart's action, 173. Tension, muscular, feeling of, 31*. Tertullian, 120. Tetanus, 177. Thalamus opticus, 187. Thales, 3. Theolepsy, 303. Thompson, Sir W., the molecular structure of water, 260. Thought, secretion of, 77. Thuraam, Dr. J., on the weight of the brain, 103. Tiger-moth, the, an. Todd, Dr., on the seat of epilepsy, 263. Tonicity, muscular, 162. Townshend, Colonel, remarkable case of, 34I-, . Transpeciation, 457. Trousseau, on epileptic vertigo, 151, 152- Truth, absolute, 121, 323. Tuber annulare, 187. Tucker, A., 238, 437, 445. Tyler, E. B., on analogy between colours and sounds, 93; on sounds not used in speech, 471 ; on gesture- language, 481. U. UKCOVDITIINKD, the, to. Unconsciousness, epileptic, 151, eo8, 347 Unknowable, the, 10. Unzer, on material ideas, 85 ; on reflex functions, 139, 183 ; on acquired automatic movements, 184 ; on sen- sory movements, 195 ; on pleasi.re and pain, 351 ; on the motor expres- sions of emotions, 379. V. VAN r>F.R KOI.K, SCHROBDBR, on the structure of cerebral convolutions, 1 16; on morbid changes in insanity. 124, 262 ; on epileptic unconscious- ness, 151 ; on the centre of muscu- lar co-ordination, 154 ; on ganglionic nuclei, 189; on unconscious shriek ing, 209. Variation, the law of, 217. Vertigo, epileptic, 151. INDEX. 547 Vision, complex nature of, 935. Vitality, the theory of, 131. Volkmann, on symmetrical increase of sensibility, 235 Volition, 309, 339, 409 461 ; self- determining, 412; abstract. 432, 442 ; neivou* centres of, 441, 444. Von Baer, on the law of development, 7,132. Vulpian, on properties of nerve-fibres, 80 ; on nerve-centres, 153 ; on the seat of common sensation, 187 ; on the removal of cerebral hemispheres, 192 ; on the law of transmission by nerves, 472. W. WALLACK, A. R., on vision in insects, 210 : imitation by bees, ants, and birds, 240. West, Gilbert, stanza of, 392. Whytt, Dr., on motor hallucinations. 483. Wieland, on imagination, 526. Wilks, L)n, ou the seat of epilepsy, 263. Will, the, 409462 ; free, 410422 ; its power over movements, 434 ; its power over ideas, 436 ; inhibitory function of, 442 ; relation of charac- ter to, 445 ; relation of emotions to, 451 ; represents the most complete consensus of energies, 456 ; is the highest force in nature, 456 ; and creative, 457 ; the resolution of, 486. Wolff, on the law of organic develop- ment, 132. Wollaston, Dr., letter to, 72. Wundt, on functional disposition, 72 ; on the functions of the thalami optici and corpora striata, 188 ; on motor innervation, 484. THE END. D. APPLE TON & CO. '8 PUBLICATIONS, DR. HENRY MAUDSLEY'S WORKS. BODY AND WILL: Being an Essay concerning Will in ita Metaphysical, Physiological, and Pathological Aspects. 12mo. Cloth, |2.50. 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The principal point In which Sir John's mode of experiment differs from those of Hubvr, Kon-L, McCook, and others, is that he has carefully watched and marked particular insects, and has bad their ncsta under observation for tang periods one of his ants' nests having been under constant Inspection ever since Is74. Ills observations are made principally upon ants, because they show more power and flexi- bility of mind; and tho value of 1m studies is thai they belong to the department of original research. 11 " We have no hesitation in saying that the author has presented us with the most valuable series of observations on a special subject that has ever been produced, charm- ingly written, full of logical deductions, and, when we consider his multitudinous en- ir-i^'fiiiriit.*. a remarkable illustration of economy of time. As a contribution to insect psychology, it will be long before this book tiuds a parallel." London Athenaeum. DISEASES OF MEMORY. 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