The Physical Basis of Mind / Being the Second Series of Problems of Life and Mind.

by George Henry Lewes

THE REFLEX THEORY.

CHAPTER I.
THE PROBLEM STATED.

1. The peculiarity of the Reflex Theory is its exclusion of Sensibility from the actions classed as reflex; in consequence of which, the actions are considered to be “purely mechanical.”

No one denies that most of the reflex actions often have conscious sensations preceding and accompanying them, but these are said not to be essential to the performance of the actions, because they may be absent and the actions still take place. It is notorious that we breathe, wink, swallow, etc., whether we are conscious of these actions or not. Our conclusion therefore is that these peculiar states of Consciousness are accessory, not essential to the performance of these actions. The fact is patent, the conclusion irresistible. But now consider the equivoque: because an action takes place without our being conscious of it, the action is said to have had no sensation determining it. This, which is a truism when we limit Consciousness to one of the special modes Of Sensibility, or limit sensation to this limited Consciousness, is a falsism when we accept Consciousness as the total of all combined sensibilities, or Sensation as the reaction of the sensory mechanism. That a reflex action is determined by the sensory mechanism, no one disputes; whether the reaction of a sensory mechanism shall be called a sensation or not, is a question of terms. I have shown why it must be so called if anything like coherence is to be preserved in physiological investigations; and I have more than once suggested that the fact of intellectual processes taking place at times with no more consciousness than reflex actions, is itself sufficient to show that a process does not lapse from the mental to the mechanical sphere simply by passing unconsciously.

Inasmuch as an organism is a complex of organs, its total function must be a complex of particular functions, each of which may analytically be treated apart. Vitality is the total of all its physiological functions, and Consciousness the total of all its psychological functions. But inasmuch as it is only in its relation to the whole that each part has functional significance, and cannot therefore be isolated in reality, as it is in theory—cannot live by itself, act by itself, independently of the organism of which it is an organ, there is strict accuracy in saying that no particular sensation can exist without involving Consciousness; for this is only saying that no sensory organ can react without at the same time involving a reaction of the general sensorium. But since this general sensorium is simultaneously affected by various excitations each of which is a force, every sensation, perception, emotion, or volition is a resultant of the composition of these forces; and as there can be only one resultant at a time, to be replaced by another in swift succession, this one represents the state of Consciousness, and this state may or may not be felt under the peculiar mode named “Consciousness,” in its special meaning. In other words, the reaction of a sensory organ is always sentient, but not always consentient.

2. Let us illustrate this by the sensation of musical tone. When we hear a tone we are affected not only by the fundamental tone, representing the vibrations of the sounding body as a whole, but also by the harmonics or overtones, representing the vibrations of the several parts of that whole. It is these latter vibrations which give the tone its timbre, or peculiar quality; and as the harmonics are variable with the variable structure of the vibrating parts, two bodies which have the same fundamental tone may have markedly different qualities. There are some tones which are almost entirely free from harmonics; that is to say, their harmonics are too faint for our ear to appreciate them, though we know that the vibrations must be present. Apply this to the excitations of the sensorium. Each excitation will have its fundamental feeling, and more or less accompanying thrills of other feelings: it is these thrills which are the harmonics, giving to each excitation its specific quality; but they may be so faint that no specific quality is discriminated. A fly settles on your hand while you are writing, the faint thrill which accompanies this excitation of your sensory nerve gives the specific sensation of tickling, and this causes you to move your hand with a jerk. If your attention is preoccupied, you are said to be unconscious of the sensation, and the jerk of your hand is called a reflex action; but if your attention is not preoccupied, or if the thrill is vivid, you are said to be conscious of the sensation, and the action is no longer reflex, but volitional. Obviously here the difference depends not on the sentient excitation by an impression on the nerve, but on the state of the general sensorium and its consequent reaction. Had not the impression been carried to the sensorium, no movement would have followed the fly’s alighting on your hand, because no sensation (sensory reaction) would have been excited; the hypothesis of a purely mechanical reflex is quite inadmissible.

3. Or take another case. It sometimes happens that we fall asleep while some one is reading to us aloud. The sounds of the reader’s voice at first awaken the familiar thrills which give the tones their quality, and the words their significance; but gradually as sleep steals over us, the organism ceases to react thus; the words lose more and more of their significance, the tones lose more and more of their harmonics; at last we pass into the state of unconsciousness—we cease to hear what is read. But do we cease to feel? We have not heard, but we have been affected by the sounds. Not by distinguishable sensations; nevertheless a state of the general Sensibility has been induced. To prove that we have been affected is easy. Let the reader suddenly cease, and if our sleep be not too profound, we at once awake. Now, unless the sound of his voice had affected us, it is clear that the cessation of that could not have affected us. Or let us suppose our sleep to be unbroken by the cessation of the sound; even this will not prove that we have been unaffected by the sounds, it will merely prove that those sounds, or their cessation, did not excite a conscious state. For let the reader, in no louder tone, ask, “Are you asleep?” and we start up, with round eyes, declaring, “Not at all.” Nay, should even this question fail to awaken us, the speaker need only utter some phrase likely to excite a thrill—such as, “There’s the postman!” or, “I smell fire!” and we start up.

I remember once trying the experiment on a wearied waiter, who had fallen asleep in one of the unoccupied boxes of a tavern. His arm rested on the table, and his head rested on his arm: he snored the snore of the weary, in spite of the noisy laughter and talk of the guests. I called out “Johnson,” in a loud tone. It never moved him. I then called “Wilson,” but he snored on. No sooner did I call “waiter,” than he raised his head with a sleepy “yessir.” Now, to suppose, in this case, that he had no sensation when the words “Johnson” and “Wilson” reached his ears, but had a sensation when the word “waiter” reached his ears, is to suppose that two similar causes will not produce a similar effect. The dissyllable “Johnson” would excite as potent a reaction of his sensory organ as the dissyllable “waiter”; but the thrills—the reflex feelings—were different, because the word “Johnson” was not associated in his mind with any definite actions, whereas the word “waiter” was so associated as to become an automatic impulse.[231]

4. Two sisters are asleep in the same bed, and a child cries in the next room. The sounds of these cries will give a similar stimulus to the auditory nerve of each sister, and excite a similar sensory reaction in each. Nevertheless, the one sister sleeps on undisturbed, and is said not to hear the cry. The other springs out of bed, and attends to the child, because she being accustomed to attend on the child and soothe it when crying, the primary sensation has excited secondary sensations, thrills which lead to accustomed actions. Could we look into the mind of the sleeping sister, we should doubtless find that the sensation excited by the child’s cry had merged itself in the general stream, and perhaps modified her dreams. Let her become a mother, or take on the tender duties of a mother, and her vigilance will equal that of her sister; because the cry will then excite a definite reflex feeling, and a definite course of action. But this very sister, who is so sensitive to the cry of a child, will be undisturbed by a much louder noise; a dog may bark, or a heavy wagon thunder along the street, without causing her to turn in bed.[232]

Although during sleep the nervous centres have by no means their full activity, they are always capable of responding to a stimulus, and sensation will always be produced. When the servant taps at your bedroom door in the morning, you are said not to hear the tap, if asleep; you do not perceive it; but the sound reaches and rouses you nevertheless, since when the second tap comes, although no louder, you distinctly recognize it. In etherized patients, sensation is constantly observed returning before any consciousness of what is going on returns. “I was called,” says Mr. Potter, “to give chloroform to a lady for the extraction of ten teeth. The first five were extracted without the slightest movement, but as the operation proceeded, sensation returned, and I was obliged to use considerable force to keep her in the chair during the extraction of the last tooth. She came to herself very shortly after, and was delighted to find she had got over all her troubles without having felt it the least in the world.”[233]

5. We do not see the stars at noonday, yet they shine. We do not see the sunbeams playing among the leaves on a cloudy day, yet it is by these beams that the leaves and all other objects are visible. There is a general illumination from the sun and stars, but of this we are seldom aware, because our attention falls upon the illumined objects, brighter or darker than this general tone. There is a sort of analogy to this in the general Consciousness, which is composed of the sum of sensations excited by the incessant simultaneous action of internal and external stimuli. This forms, as it were, the daylight of our existence. We do not habitually attend to it, because attention falls on those particular sensations of pleasure or of pain, of greater or of less intensity, which usurp a prominence among the objects of the sensitive panorama. But just as we need the daylight to see the brilliant and the sombre forms of things, we need this living Consciousness to feel the pleasures and the pains of life. It is therefore as erroneous to imagine that we have no other sensations than those which we distinctly recognize—as to imagine that we see no other light than what is reflected from the shops and equipages, the colors and splendors which arrest the eye.

The amount of light received from the stars may be small, but it is present. The greater glory of the sunlight may render this starlight inappreciable, but it does not render it inoperative. In like manner the amount of sensation received from some of the centres may be inappreciable in the presence of more massive influences from other centres; but though inappreciable it cannot be inoperative—it must form an integer in the sum.

6. The reader’s daily experience will assure him that over and above all the particular sensations capable of being separately recognized, there is a general stream of Sensation which constitutes his feeling of existence—the Consciousness of himself as a sensitive being. The ebullient energy which one day exalts life, and the mournful depression which the next day renders life a burden almost intolerable, are feelings not referable to any of the particular sensations, but arise from the massive yet obscure sensibilities of the viscera, which form so important a part of the general stream of Sensation. Some of these may emerge into distinct recognition. We may feel the heart beat, the intestines move, the glands secrete; anything unusual in their action will force itself on our attention.

“What we have been long used to,” says Whytt, “we become scarcely sensible of; while things which are new, though much more trifling, and of weaker impression, affect us remarkably. Thus he who is wont to spend his time in the country is surprisingly affected, upon first coming into a populous city, with the noise and bustle which prevail there: of this, however, he becomes daily less sensible, till at length he regards it no more than they who have been used to it all their lifetime. The same seems to be the case also with what passes within our bodies. Few persons in health feel the beating of their heart, though it strikes against their ribs with considerable force every second; whereas the motion of a fly upon one’s face or hands occasions a very sensible and uneasy titillation. The pulsation of the great aorta itself is wholly unobserved by us; yet the unusual beating of a small artery in any of the fingers becomes very remarkable.”

7. A large amount of sensation is derived from the muscular sense, yet we are not aware of the nice adjustments of the muscles, regulated by this sensibility, when we sit or walk. No sooner are we placed in an exceptional position, as in walking on a narrow ledge, than we become distinctly aware of the effort required to preserve equilibrium. It is not the novelty of the position which has increased our sensibility; that has only caused us to attend to our sensations. In like manner, the various streams of sensation which make up our general sense of existence, separately escape notice until one of them becomes obstructed, or increases in impetuosity. When we are seated at a window, and look out at the trees and sky, we are so occupied with the aspects and the voices of external Nature, that no attention whatever is given to the fact of our own existence; yet all this while there has been a massive and diffusive feeling arising from the organic processes; and of this we become distinctly aware if we close our eyes, shut off all sounds, and abstract the sensations of touch and temperature—it is then perceived as a vast and powerful stream of sensation, belonging to none of the special Senses, but to the System as a whole. It is on this general stream that depend those well-known but indescribable states named “feeling well” and “feeling ill”—the bien être and malaise of every day. Of two men looking from the same window, on the same landscape, one will be moved to unutterable sadness, yearning for the peace of death; the other will feel his soul suffused with serenity and content: the one has a gloomy background, into which the sensations excited by the landscape are merged; the other has a happy background, on which the sensations play like ripples on a sunny lake. The tone of each man’s feeling is determined by the state of his general consciousness. Except in matters of pure demonstration, we are all determined towards certain conclusions as much by this general consciousness as by logic. Our philosophy, when not borrowed, is little more than the expression of our personality.

8. Having thus explained the relation of particular sensations to the general state of Consciousness considered as the function of the whole organism, we may henceforward speak of particular sentient states, as we speak of particular organs and functions, all the while presupposing that the organs and functions necessarily involve the organism, since apart from the organism they have no such significance. The reaction of a sensory organ is therefore always a sentient phenomenon. Apart from the living organism there can be no such vital reaction, but only a physical reaction. It is commonly supposed that sensation is simply the molecular excitation of the cerebrum; yet no one will maintain that if the cerebrum of a corpse be excited, by a galvanic current sent through the optic nerve, for instance, this excitation will be a sensation. Whence we may conclude that it is not the physical reaction or stimulus which constitutes sensation, but the physiological reaction of the living organism.

9. Now this is the point which the advocates of the Reflex Theory, implicitly or explicitly, always deny. Let us trace the origin of the fallacy, if possible. When we remove the eye from a recently killed animal, and let a beam of light fall on it, the pupil contracts. This is a purely mechanical action; no one would suggest that a sensation determined it. When we remove the leg, and irritate its nerve, the leg is jerked out. This is also a purely mechanical action. When we remove the brain from an animal, and pinch its toes, the leg is withdrawn or the pincers are pushed aside. Is this equally a purely mechanical action? And if not, why not?

The Reflex Theory would have us believe that all three cases were mechanical, at least in so far as they were all destitute of sentient co-operation, the ground for this conclusion being the hypothesis that the brain is the exclusive seat of sensation. The Reflex Theory further concludes that since these, and analogous actions, are performed when the brain is removed, they, being thus independent of sentience, may be performed when the brain is present without any co-operation of sentience. The grounds for this conclusion being the facts that in the normal state of the organism there are many actions of which we are sometimes conscious, and at other times unconscious; and some actions—such as the dilatation and contraction of the pupil—of which we are never conscious. This observation of parts detached from the organism seems confirmed by observation of actions passing in our own organisms, both converging to the conclusion that the actions in question are purely mechanical, involving no sentience whatever. We are taught, therefore, that there is besides the sentient mechanism, to which all conscious actions are referred, a reflex mechanism, to which all unconscious actions are referred. The cerebro-spinal axis, acting as a whole, constitutes the first; the spinal axis, acting without the co-operation of the cerebrum, constitutes the second.

10. Before proceeding with our exposition of the theory it may be well to state two considerations which must be constantly in view. If it should appear that there is any reasonable evidence for refusing to limit Sensibility to the cerebrum—and this evidence I shall adduce—the Reflex Theory must obviously be remodelled. Nor is this all. We might see overwhelming evidence in favor of the hypothesis that the cerebrum is the exclusive seat of Sensibility, and still reject as a fallacy the conclusion that because certain actions can be performed in the absence of the cerebrum, therefore those actions in the normal organism are likewise performed without cerebral co-operation. I mean that it is a fallacy to conclude from the contractions of the pupil, and the jerking of the leg, when eye and leg are detached from the organism, that therefore when eye and leg form integral parts of the organism, such contractions and jerkings are mechanical reflexes without sentient conditions. And the fallacy is analogous to that which would conclude from the observations of a mechanical automaton, that similar appearances in a vital organism were equally automatic and mechanical. So long as both sets of phenomena are apprehended simply as they appear to the sense of sight, they may be indistinguishable; but no sooner do we apprehend them through other modes, and examine the modes of production of the phenomena, than we come upon cardinal differences. A limb detached from the organism is like a phrase detached from a sentence: it has lost its vital significance, its functional value, in losing its connection with the other parts. The whole sentence is necessary for the slightest meaning of its constituent words, and each word is a language-element only when ideally or verbally connected with the other words required to form a sentence; without subject, predicate, and copula, no sentence can be formed. So the organic connexus of parts with a living whole is necessary for the simplest function of each organ; and a limb, or any other part, is a physiological element only when (ideally or really) an integral of a vital whole. The organism may be truncated by the removal of certain parts, as the sentence may be abbreviated by the removal of certain phrases; but so long as subject, predicate, and copula remain, there is a meaning in the sentence; and so long as the organic connexus needful for vitality remains, there will be vital function. The eye detached from the organism is no longer a part of the living whole, it no longer lives, its phenomena cease to be vital, its movements cease to have sentient conditions. The movements of the pupil may seem to be the same as those of the living eye; but when we come to examine their modes of production, we learn that they are not the same. The stimulus of light falling on the eye in the two cases necessarily has a different effect, because the effect is the result of the co-operating causes, and the co-operation in the one case is that of a lifeless organ, in the other that of a living organism. So long as the eye forms an integral part of the organism, every stimulus acting on the eye necessarily acts on the organism, and every reaction of the organ is necessarily conditioned by the state of the organism. Further, every stimulation of a sensory nerve necessarily affects the general sensorium, since the whole nervous system is structurally continuous and functionally co-operant. (See Prob. II. § [16].) Therefore, the stimulation of the eye, although too faint to be discriminated as a conscious sensation, must enter as a sentient tremor into the general stream of Sentience; and although we have no test delicate enough to reveal this operation, we know the obverse operation of conscious sensation on the movements of the pupil—in surprise, for example, the pupil is dilated.

11. There are still stronger reasons for asserting that the spinal reflexes are necessarily conditioned by the general state of the sensorium, so that in the normal organism we cannot legitimately exclude them from Sentience; and the Reflex Theory is therefore unphysiological, even on the hypothesis that the cerebrum is the exclusive seat of Sensibility. This hypothesis, however, seems to me untenable; and all the observed facts which it is invented to explain admit of a far more consistent explanation. It is irrational to suppose that a limb, detached from the body, felt the stimulus which caused its muscles to contract. The limb is not a living organism, having a sentient mechanism in its nervous mechanism. Not less irrational is it to suppose that when the limb forms an integral part of a living organism, with a sentient mechanism of nerves and nerve-centres, this organism does not react on the stimulus which excites the muscles of the limb to contract; nor, pursuing the same train of reasoning, is it irrational to suppose that when this living organism has been mutilated, and certain parts destroyed, which do not in their destruction prevent the connexus of the rest, but leave intact a sentient mechanism of nerves and nerve-centres, then also this truncated organism still reacts as a whole, still feels the stimulus which causes the muscles of the limb to contract. Hypothesis for hypothesis, we may at least say that the one is as reasonable as the other. And I shall be disappointed if, when the reader has gone through all the evidence hereafter to be adduced, he does not conclude that the hypothesis which assigns Sensibility to the nervous mechanism as a whole is not the more acceptable of the two.

12. Let us now pursue our exposition of the Reflex Theory. All that we have endeavoured to establish respecting the essential identity of the processes in conscious and unconscious states, and voluntary and involuntary actions,—an identity which does not exclude differences of degree corresponding with these different terms,—is ignored or denied in the Reflex Theory. Whereas I suppose all processes to be reflex processes, some of them having the voluntary, others the involuntary character, physiologists generally distinguish the involuntary as reflex, and invent for this class a special mechanism. According to Marshall Hall, who originated the modern form of this theory, actions are divisible into four distinct classes: the voluntary, dependent on the brain; the involuntary, dependent on the irritability of the muscular fibre; the respiratory, wherein “the motive influence passes in a direct line from one point of the nervous system to certain muscles”; and the reflex, dependent on the “true spinal system” of incident-excitor nerves, and of reflex-motor nerves. These last-named actions are produced when an impression on the sensitive surface is conveyed, by an excitor-nerve, to the spinal cord, and is there reflected back on the muscles by a corresponding motor-nerve. In this process no sensation whatever occurs. The action is purely reflex, purely excito-motor—like the action of an ordinary mechanism.[234]

Müller, who shares with Marshall Hall the glory of having established this classification, thinks that although the absence of sensation is a characteristic of the reflex actions, these actions may be, and are at times, accompanied by sensation. “The view I take of the matter is the following: Irritation of sensitive fibres of a spinal nerve excites primarily a centripetal action of the nervous principle conveying the impression to the spinal cord; if the centripetal action can then be continued to the sensorium commune, a true sensation is the result; if, on account of division of the cord, it cannot be communicated to the sensorium, it still exerts its whole influence upon the cord; in both cases a reflex motor action may be the result.”[235]

13. It is needless nowadays to point out that the existence of a distinct system of excito-motor nerves belongs to Imaginary Anatomy; but it is not needless to point out that the Imaginary Physiology founded on it still survives. The hypothetical process seems to me not less at variance with observation and induction, than the hypothetical structure invented for its basis. We have already seen that what Anatomy positively teaches is totally unlike the reflex mechanism popularly imagined. The sensory nerve is not seen to enter the spinal cord at one point, and pass over to a corresponding point of exit; it is seen to enter the gray substance, which is continuous throughout the spinal cord; it is there lost to view, its course being untraceable. Nor does the physiological process present the aspect demanded by the theory: it is not that of a direct and uniform reflexion, such as would result from an impression on one spot transmitted across the spinal cord to a corresponding motor-nerve. The impression is sometimes followed by one movement, sometimes by another very different movement, each determined by the state of neural tension in the whole central system.

Even the facts on which the Reflex Theory is based are differently interpreted by different physiologists. Van Deen, for instance, considers that Reflexion takes place without Volition, but not without Sensation; and Budge, that it takes place without perception (Vorstellung). And when it is remembered that most of the reflex actions will be accompanied by distinct consciousness whenever attention is directed to them, or the vividness of the stimulation is slightly increased, it becomes evident that the absence of Consciousness (discrimination) is not the differentia of Reflex action.

14. Nor can the absence of spontaneity be accepted as a differentia. All actions are excited by stimulation, internal or external. What are called the spontaneous actions are simply those which are prompted by internal, or by not recognizable stimuli; and could we see the process, we should see a neural change initiated by some stimulation, whether the change was conscious and volitional, or unconscious and automatic. The dog rising from sleep and restlessly moving about, is acting spontaneously, whether the stimulation which awakens him be a sensation of hunger, a sensation of sound, the sharp pain of a prick, or a dash of cold water. If he wags his tail at the sight of his master, or wags it when dreaming, the stimulation is said to be spontaneous; but if after his spinal cord has been divided the tail wags when his abdomen is tickled, the action is called reflex. In all three cases there has been a process of excitation and reflexion.

15. The advocates of the Reflex Theory insist that spontaneity is always absent in brainless animals; whence the conclusion that the brain is the exclusive organ of sensation. But the fact asserted is contradicted by the evidence. No experimenter can have failed to observe numberless examples of spontaneity in brainless animals. Many examples have already been incidentally noticed in previous pages. Let me add one more from my notes: I decapitated a toad and a triton, and divided the spinal cord of another triton and a frog. At first the movements of the decapitated animals were insignificant; but on the second day the headless toad was quite as lively as the frog; and the headless triton little less so than his companion with cord divided but brain intact. I have, at the time of writing this, a frog whose cord was divided some weeks ago. He remains almost motionless unless when touched; he is generally found in the same spot, and in the same attitude to-day as yesterday, unless touched, or unless the table be shaken. He occasionally moves one of the forelegs; occasionally one of the hind-legs; but without changing his position. If he were brainless, this quiescence would be cited in proof of the absence of spontaneity in the absence of the brain; but this conclusion would be fallacious, and is seen to be so in the spontaneous movements of his companion who has no brain.

16. With spontaneity is associated the idea of volition, and with volition choice. Now I admit that it is complicating the question to ask any one to conceive a headless animal choosing one action rather than another; but it is equally difficult to reconcile ourselves to the idea of “choice” in contemplating the actions of a mollusc. In what sense we can speak of the volition of a mollusc or an insect has already been considered (p. 408). When a man in a fit of coughing seizes a glass of water to allay the tickling in his throat, we have no hesitation in declaring this to be volitional—and the remedy to be chosen. But when a brainless animal adopts some unusual means, after the failure of the usual means, to allay an irritation, we still hesitate to call the action volitional. I see, however, no objection to calling it the adaptation of a sensitive mechanism which is markedly unlike any inorganic mechanism.

Place a child of two or three years old upon his back, and tickle his right cheek with a feather. He will probably move his head away. Continue tickling, and he will rub the spot with his right hand, never using the left hand for the right cheek, so long as the right hand is free; but if you hold his right hand, he will use the left. Does any one dispute the voluntary character of these actions?

Now compare the actions of the sleeping child under similar circumstances, and their sequence will be precisely similar. This contrast is the more illustrative, because physiologists generally assume that in sleep consciousness and volition are suspended. They say: “The brain sleeps, the spinal cord never; volition and sensation may be suspended, but not reflex action.” This proposition is extremely questionable; yet it is indispensable to the reflex theory; because unless sensation and volition are suspended during sleep, we must admit that they can act, without at the same time calling into activity that degree of sensibility which is supposed to constitute consciousness. The child moves in his sleep, defends himself in his sleep; but he is not “aware” of it.

“Children,” says Pflüger, “sleep more soundly than adults, and seem to be more sensitive in sleep. I tickled the right nostril of a three-year-old boy. He at once raised his right hand to push me away, and then rubbed the place. When I tickled the left nostril he raised the left hand. I then softly drew both arms down, and laid them close to the body, embedding the left arm in the clothes, and placing on it a pillow, by gentle pressure on which I could keep the arm down without awakening him. Having done this I tickled his left nostril. He at once began to move the imprisoned arm, but could not reach his face with it, because I held it firmly though gently down. He now drew his head aside, and I continued tickling, whereupon he raised the right hand, and with it rubbed the left nostril—an action he never performed when the left hand was free.”

17. This simple but ingenious experiment establishes one important point, namely, that the so-called reflex actions observed in sleep are determined by sensation and volition. The sleeping child behaves exactly as the waking child behaved; the only difference being in the energy and rapidity of the actions. If the waking child felt and willed, surely the sleeping child, when it performed precisely similar actions, cannot be said to have felt nothing, willed nothing? It is not at one moment a sentient organism, and at the next an insentient mechanism.

It is possible to meet this case by assuming that the child was nearly awake, and that a dim consciousness was aroused by the tickling, so that the cerebral activity was in fact awakened. But, plausible as this explanation may be (and I am the more ready to admit it because I believe the brain always co-operates when it is present), it altogether fails when we come to experiments on decapitated animals. If any one will institute a series of such experiments, taking care to compare the actions of the animal before and after decapitation, he will perceive that there is no more difference between them than between those of the sleeping and the waking child.

18. Even more striking is the following experiment, devised by Pflüger, which I have verified, and varied, many times: A frog is decapitated, or its brain is removed.[236] When it has recovered from the effect of the ether, and manifests lively sensibility, we place it on its back, and touch, with acetic acid, the skin of its thigh just above the condylus internus femoris. (Let the reader imagine his own shoulder burnt at the point where it can be reached with the thumb of the same arm, and he will realize the operation.) No sooner does the acid begin to burn than the frog stretches out the other leg, so that its body is somewhat drawn towards it. The leg that has been burnt is now bent, and the back of the foot is applied to the spot, rubbing the acid away—just as your thumb might rub your shoulder. This is very like the action of the tickled child, who always uses the right hand to rub the right cheek, unless it be held; but when the child’s right hand is prevented from rubbing, the left will be employed; and precisely this do we observe with the brainless frog: prevent it from using its right leg, and it will use its left!

This has been proved by decapitating another frog, and cutting off the foot of the leg which is to be irritated. No sooner is the acid applied, than the leg is bent as before, and the stump is moved to and fro, as if to rub away the acid. But the acid is not rubbed away, and the animal becomes restless, as if trying to hit upon some other plan for freeing himself of the irritation. And it is worthy of remark that he often hits upon plans very similar to those which an intelligent human being adopts under similar circumstances. Thus, the irritation continuing, he will sometimes cease the vain efforts with his stump, and stretching that leg straight out, bends the other leg over towards the irritated spot, and rubs the acid away. But, to show how far this action is from one of “mere mechanism,” how far it is from being a direct reflex of an impression on a group of muscles, the frog does not always hit even on this plan. Sometimes it bends its irritated leg more energetically, and likewise bends the body towards it, so as to permit the spot to be rubbed against the flank—just as the child, when both his hands are held, will bend his cheek towards his shoulder and rub it there.

19. It is difficult to resist such evidence as is here manifested. The brainless frog “chooses” a new plan when the old one fails, just as the waking child chooses. And an illustration of how sensations guide and determine movements, may be seen in another observation of the brainless frog, when, as often happens, it does not hit upon either of the plans just mentioned, but remains apparently restless and helpless; if under these circumstances we perform a part of the action for it, it will complete what we have begun: if we rub the irritated leg, at some distance from the spot where the acid is, with the foot of the other, the frog suddenly avails itself of this guiding sensation, and at once directs its foot to the irritated spot.

In these experiments on the triton and the frog, the evidence of sensation and volition is all the stronger, because the reactions produced by irritations are not uniform. If when a decapitated animal were stimulated it always reacted in precisely the same way, and never chose new means on the failure of the old, it would be conceivable to attribute the results to simple reflex action—i. e. the mechanical transference of an impulse along a prescribed path. It is possible so to conceive the breathing, or the swallowing mechanism: the impression may be directly reflected on certain groups of muscles. But I cannot conceive a machine suddenly striking out new methods, when the old methods fail. I cannot conceive a machine thrown into disorder when its accustomed actions fail, and in this disorder suddenly lighting upon an action likely to succeed, and continuing that; but I can conceive this to be done by an organism, for my own experience and observation of animals assures me that this is always the way new lines of action are adopted. And this which is observed of the unmutilated animal, I have just shown to be observed of the brainless animal; wherefore the conclusion is, that if ever the frog is sentient, if ever its actions are guided by sensation, they are so when its brain is removed.

20. Schröder van der Kolk thinks that Pflüger was deceived in attributing sensation and volition to the frog, because the reflex actions are, he says, so nicely adapted to their ends, that they are undistinguishable from voluntary actions. The mechanism is such that, by means of the communications established between various groups of cells, all these actions adapted to an end may be excited by every stimulus. But I deny the fact. I deny that all the actions are awakened by every stimulus. Only some few are awakened, and those are not always the same, nor do they follow the same order of succession. One decapitated frog does not behave exactly like another under similar circumstances; does not behave exactly like himself at different seasons; unlike a machine, he manifests spontaneity in his actions, and volition in the direction of his actions.

21. The reader will notice that my illustrations show these actions of the brainless animal to have the same external characters as those of the unmutilated animals. I am therefore not here concerned to prove the psychical nature of these actions, unless it be granted that the unmutilated animal has sensation and volition. This of course can only be inferred, not proved. But the inference must not be allowed in the one case and refused in the other. Young rabbits and puppies when taken from their mothers manifest discomfort by restless movement and whining. Do they feel the discomfort they thus express? If ever rabbits and puppies may be said to feel, we must answer, Yes. Well, if the brain be removed from rabbits and puppies, precisely similar phenomena are observed when these young animals are taken from their mothers. “I observed the motions, which seemed the result of discomfort, quickly cease when I warmed the young rabbit by breathing on it. After a while it was completely at rest, and seemed sunk in deep sleep; occasionally, however, it moved one of its legs without any external stimulus having been applied, and this not spasmodically, but in the manner of a sleeping animal.”[237] Is this cessation of the restlessness, when warmth is restored, not evidence of sensation? We see an infant restless, struggling, and squalling; and we believe that it is hungry, or that some other sensations agitate it; it is put to the breast, and its squalls subside; or a finger is placed in its mouth, and it sucks that, in a peaceful lull, for a few moments, to recommence squalling when the finger yields no satisfaction. If we accept these as signs of sensation, I do not see how we can deny such sensation to the brainless animal which will also cease to cry, and will suck the delusive finger.

22. One of the earliest advocates of the Reflex Theory sums up his observations in these words: “It is clear that brainless animals, although without sensation, because not endowed with mind, nevertheless, by means of external impressions which operate incessantly on them, perform all the acts and manifest all the activity of the sentient animal; everything that is effected sensationally and volitionally, they effect by means of the organic forces of the impressions.”[238] Call Sensibility one of the organic forces, if you please, but so long as the acts performed are not only the same as those of a sentient animal, but are performed by the same mechanism, they have every claim to the character of sensational acts which can be urged in the case of these animals when the brain is present. And the only reason on which this claim is disputed is the assumed loss of all sensation with the loss of the brain. Here, therefore, lies the central point to be determined.

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CHAPTER II.
DEDUCTIONS FROM GENERAL LAWS.

23. The evidence is of two kinds: deductions from the general laws of nervous action, and inductions from particular manifestations. The former furnish a presumption, the latter a proof.

The central process which initiates a reflex action may be excited by the external stimulation of a peripheral nerve, by the internal stimulation of a peripheral nerve, or by the irradiation from some other part of the central tissue. The last-named stimulations are the least intelligible, because they are so varied and complex, and so remote from observation; among them may be placed, 1°, the organized impulses of Instinct and Habit, with their fixed modes of manifestation; 2°, the organized impulses of Emotion, which are more variable in their manifestations, because more fluctuating in their conditions; 3°, the organized impulses of Intellect, the most variable of all. Whether we shrink on the contact of a cold substance or on hearing a sudden sound,—at the sight of a terrible object,—at the imaginary vision of the object,—or because we feign the terror which is thus expressed,—the reflex mechanism of shrinking is in each case the same, and the neural process discharged on the muscles is the same; but the state of Feeling which originated the change—or, in strictly physiological terms, the inciting neural process which preceded this reflex neural process—was in each case somewhat different, yet in each case was a mode of Sensibility.

24. The property of Sensibility belongs to the whole central tissue; and we have every reason to believe that unless it is excited no reflex takes place, whereas when it is exaggerated—as in epilepsy, or under strychnine—the reflex discharges are convulsive. When anæsthetics are given, consciousness first disappears, and then reflexion. When the sensorium is powerfully excited by other stimuli, the normal stimulus fails to excite either consciousness or reflexion. Hence our conclusion is that for consciousness, on the one hand, and normal reflexion, on the other, the proximate condition is a change in the sensorium; or—to phrase it more familiarly—Feeling is necessary for reflex action.

The difficulty in apprehending this lies in the ambiguity of the term Feeling. Many readers who would find no difficulty in admitting Sensibility as a necessary element in reflex action, will resist the idea of identifying Sensibility with Feeling. But this repugnance must be overcome if we are to understand the various modes of Sensibility which represent Feeling in animals, and its varieties in ourselves. We understand how the general Sensibility manifests itself in markedly different sensations—how that of the optic centre differs from that of the auditory centre, and both from a spinal centre. The tones of a violin are not the same as the tones of a violoncello, both differ from the tones of a key-bugle: yet they all come under the same general laws of tonality. So, as I often insist, the tissues in brain and cord being the same, their properties must be the same, their laws of excitation, irradiation, and combination the same, through all the varieties in their manifestations due to varieties of innervation. Hence it is that there are reflex cerebral processes no less than reflex spinal processes: the motor impulse from, the hemispheres on the corpora striata, or from posterior gray substance on anterior gray substance, is similar to that from the anterior gray substance on the motor nerves. The difference in reflexes arises from the terminal organs; as the difference in sensations arises from the surfaces stimulated. But not only are there reflex processes in the brain, of the same order as those in the cord, there are volitional processes in the cord of the same order as those in the brain. And in both the processes are sometimes conscious, sometimes unconscious. No evidence suggests that in the conscious action there is a sensorial process, and a purely physical process in the unconscious action—only a different relation of one sensorial process to others.

25. Let us contrast a cerebral and a spinal process, in respect to the three stages of stimulation, irradiation, and discharge. A luminous impression stimulates my retina, this excites my sensorium, in which second stage I am conscious of the luminous sensation; the final discharge is a perception, or a mental articulation of the name of the luminous object. But the irradiation may perhaps not have been such as to cause a conscious sensation, because the requisite neural elements were already grouped in some other way; in this case there is an unconscious discharge on some motor group, and instead of perceiving and naming the luminous object, I move my head, or my band, or my whole body, avoiding the object, or grasping at it. A third issue is possible: the irradiation, instead of exciting a definite perception, or a definite movement, may be merged in the stream of simultaneous excitations, and thus form the component of a group, and the discharge of this group will be a perception or a movement.

It is the same with a spinal process. An impression on the skin is irradiated in the cord, and the response is a movement, of which we are conscious, or unconscious. Here also a third issue is possible: the irradiation may be merged in a stream of simultaneous excitations, modifying them and modified by them, thus forming a component in some ulterior discharge.

26. The obstacle in the way of recognizing that cerebral processes and spinal processes are of the same order of sensorial phenomena, and have the same physiological significance when considered irrespective of the group of organs they call into activity, is similar to the obstacle which has prevented psychologists from recognizing the identity of the logical process in the combinations of Feeling and the combinations of Thought, i. e. the Logic of Feeling and the Logic of Signs. This obstacle is the fixing attention on the diversity of the effects when the same process operates with different elements. Because the spinal cord manifests the phenomena of sensation and volition, we are not to conclude that it also manifests ideation and imagination; any more than we are to conclude that a mollusc is capable of musical feelings because it is affected by sounds.

27. The careless confusion of general properties with special applications of those properties, and of functions with properties, has been a serious hindrance to the right understanding of Sensibility and its operations. Instead of recognizing that the nervous system has one general mode of reaction, which remains the same under every variety of combination with other systems, physiologists commonly lose sight of this general property, and fix on one mode of its manifestation as the sole characteristic of Sensibility. Sometimes the mode fixed on is Pain, at other times Attention. Thus, when an animal manifests no evidence of pain under stimulations which ordinarily excite severe pain, this is often interpreted as a proof that all sensation is absent; and if with this absence of pain there is—as there often is—clear evidence of the presence of some other mode of sensibility, the contradiction is evaded by the assumption that what here looks like evidence of sensation is merely mechanical reflexion. One would think that Physiology and Pathology had been silent on the facts of analgesia without anæsthesia, and of so much conscious sensation which is unaccompanied by pain.[239] Who does not know that a patient will lose one kind of sensibility while retaining others—cease to feel pain, yet feel temperature, or be insensible to touch, yet exquisitely alive to pain?[240] Inasmuch as Sensibility depends on the condition of the centres, an abnormal condition will obviously transform the reaction of the centres into one very unlike the normal reaction. For example, Antoine Cros had a patient who was quite unable to feel the sensation of cold on her left side—every cold object touching her skin on that side was felt as a very hot one; whereas a hot object produced “the sort of sensation which followed the application of an intermittent voltaic current.”[241] Thus also the experiments of Rose[242] and others have exhibited the effects of a dose of Santonine in causing all objects to be seen as yellow in one stage, and violet in another.

28. If, then, certain alterations in the organic conditions are accompanied by a suppression or perversion of some modes of Sensibility, without suppressing the rest, it is but rational to suppose that profound disturbances of the organic mechanism, such as must result from the removal of the brain, will also suppress or pervert several modes of Sensibility, and yet leave intact those modes which belong to the intact parts of the mechanism. Assuming that the spinal centres with the organs they innervate are capable of reacting under certain modes of sensation, these will not necessarily be suppressed by removal of the brain—all that will thereby be suppressed is their co-operation with the brain. I know it will be said that precisely this co-operation is necessary for sensation; and that the spinal reactions are simple reflexions in which sensation has no part. This, however, is the position I hope to turn. Meanwhile my assumption is that sensation necessarily plays a part in the reflex actions of the organism, and when that organism is truncated, its actions are proportionately limited, its sensations less complex. The spinal cord, separated from encephalic connections, cannot react in the special forms of Sensation known as color, scent, taste, sound, etc., because it does not innervate the organs of these special senses, nor co-operate with their centres. But it can, and does, react in other modes: it innervates skin and muscles; and the sensibilities, thus excited, it can also combine and co-ordinate. It has its Memory, and its Logic, just as the brain has: both no longer than they are integral parts of an active living organism: neither when the organism is inactive or dead. We do not expect the retina to respond in sounds, nor the ear to respond in colors: we expect each organ to have its special mode of reaction. What is common to both is Sensibility. What is common to brain and cord is Sensibility—and the laws of Grouping. Instead of marvelling at the disappearance of so many modes of Sensibility when the brain is removed, our surprise should be to find so many evidences of Sensibility remaining after so profound a mutilation of the mechanism.

29. The current hypothesis, which assumes that the brain is the sole organ of the mind, the sole seat of sensation, is a remnant of the ancient hypothesis respecting the Soul and its seat; and on the whole I think the ancient hypothesis is the more rational of the two. If the Soul inhabits the organism, using it as an instrument, playing on its organs as a musician plays on his instrument, we are not called upon to explain the mode of operation of this mysterious agent; but if the Soul be the subjective side of the Life, the spiritual aspect of the material organism, then since it is a synthesis of all the organic forces, the consensus of all the sentient phenomena, no one part can usurp the prerogatives of all, but all are requisite for each. And this indeed is what few physiologists would nowadays dispute. In spite of their localizing sensation in the cerebral cells, they would not maintain that the cerebral cells, nor even the whole brain, could produce sensation—if detached from the organism; the cheek of the guillotined victim may have blushed when struck, but who believes that the brain felt the insult, or the blow? Obviously, therefore, when we read that thought is “a property of the gray substance of the brain, as gravitation is of matter,” or that the brain is the exclusive organ of Sensation, the writers cannot consistently carry out their hypothesis unless they silently reintroduce other organs as co-operating agents; for a neural process in the cerebrum is in itself no more a sensation than it is a muscular contraction, or a glandular secretion: the muscles must co-operate for the contraction, the gland for the secretion, the neural process being simply the exciting cause. In like manner the Sensorium is necessary for the sensation, the neural process—in cerebrum, or elsewhere—being simply the exciting cause.

30. And what is the Sensorium? A long chapter would be required to state the various opinions which have been held respecting its seat, although amid all the disputes as to the organ, there has been unanimity as to the function, which is that of converting stimulations into sensations. I cannot pause here to examine the contending arguments, but must content myself with expounding the opinion I hold, namely, that the Sensorium is the whole of the sensitive organism, and not any one isolated portion of it. When light falls on the optic organ, or air pulses on the auditory organ, the reaction of each organ determines the specific character of the sensation, but no such sensation is possible unless there be a reaction of the organism; and the nature of the product will of course vary with the varying factors which co-operate—a simple organism, a truncated organism, an exhausted or otherwise occupied organism, will react differently from a complex, a normal, or an unoccupied organism. Detach the optic organ with its centre from the rest of the organism, and no normal sensation of Sight will result from its stimulation; and in a lesser degree this is equally true of a stimulation of the optic organ when the sensorium is exhausted, or powerfully affected by other stimuli. Because of the great importance of the cerebrum, and its predominance in the nervous system, it has been supposed to constitute the whole of the sensorium, in spite of the evidence of varied Sensibility after the cerebrum has been removed. I do not wish to understate the cerebral importance (see p. 166), yet I must say that the modern phrase cerebration, when employed as more than a shorthand expression of the complex processes which a cerebral process initiates, and when taken as the objective equivalent of Consciousness or of Thought, seems to me not more justifiable than to speak of Combustion as the equivalent of Railway Transport. The railway wagons will not move unless the fuel which supplies the boiler be ignited; the organism will not think unless the cerebrum excites this peculiar mode of Sensibility by its action on the organs. It is the man, and not the brain, that thinks: it is the organism as a whole, and not one organ, that feels and acts.

31. Consciousness, or Sensation, is a complex product not to be recognized in any one of its factors. Cerebral processes and spinal processes are the elements we analytically separate, as muscular contractions are the elements of limb-movements. The synthetic unity of these elements is a reflex; this we analytically decompose into a sensation and a movement; and then we speak of sensation as the reaction of the sensory organ, the movement as the reaction of the muscular organ. By a similar procedure we separate the stimulation of a sensory nerve from the reaction of the sensory organ, and that from the reaction of the sensorium; and in this way we may come to regard Cerebration as Thought. But those who employ this artifice should remember that the organism is not an assemblage of organs, made up of parts put together like a machine. The organs are differentiations of the organism, each evolved from those which preceded it, all sharing in a common activity, all inter-dependent.

32. That co-operation of the Personality which is conspicuous in conscious actions is also inductively to be inferred in sub-conscious and unconscious actions. We know that a man reacts on an impression according to his physical and mental state at the moment—that through his individuality he feels differently, and thinks differently from other men, and from himself at other epochs, and in other states. Because he resembles other men in many and essential points we conclude that he will resemble them in all; but observation proves this conclusion to be precipitate. Other men see a blue color in the sky, or feel awe at sight of the setting sun; but he has perhaps not learned to discriminate this sensation, is not conscious of the blue; nor has he learned to feel awe at the setting sun. Why—having normally constructed eyes—does he not see the blue of the sky? For the same reason that a dog, or an infant, fails to see it. The color has no interest for him (and all cognition is primarily emotion), nor has this want of personal interest been rectified from an impersonal source: he has never been taught to distinguish the color of the sky; and his eye wanders over it with the indifferent gaze with which a savage would regard a Greek codex.

33. The point here insisted on, namely, that every reaction on an impression is indirectly the reaction of the whole organism, and that no organ detached from the organism has more significance than a word detached from a sentence, is of far-reaching importance, and peculiarly worthy of attention in considering the Reflex Theory, because almost all the evidence urged in support of that theory presupposes the legitimacy of concluding what takes place in the organism from what is observed in an organ detached from its normal connections. No experimental proof is necessary to show that many actions take place unconsciously; the fact is undisputed. But does unconsciously mean insentiently? It is certain that the unconscious actions take place in a sentient organism, and involve organic processes of the same order as the actions which are conscious. It is also certain that many sentient processes take place unconsciously. For thousands of years men used their eyes, and saw as their descendants see, yet were unconscious of the blue sky and green of the grass. Were their visual reactions not of the same order as our own? So far as the optic apparatus is concerned, there cannot be a doubt on the point; yet in them the sensorium having a somewhat different disposition—the neural elements being differently combined—their reactions correspondingly differed. They too had optical Sensibility, and visual sensations; but they did not feel precisely what we feel.

34. I have chosen these somewhat remote illustrations for the sake of their psychological interest; but I might have confined myself to more familiar examples. Thus the contents of the consciousness of a man born blind cannot be the same as the contents of one who has had visual experiences, which will enter into the complex of every conscious state, because the visual organs will have affected his sensorium; nevertheless in the organism of the blind man there are conditions so similar to those of other men, and his experiences will have been so similar, that in spite of the modifications due to the absence of visual experiences, his consciousness will in the main resemble theirs. But now let us in imagination pursue this kind of modification, let us take away hearing, taste, and smell, and we shall have proportionately simplified the contents of consciousness—the reactions of the sensorium—in thus simplifying the organism. There still will remain Touch, Temperature, Pain, and the Systemic Sensations. There will still remain an organism to react on impressions. So long as there is a living organism, however truncated, there is a sentient mechanism. When the brain has been removed, the removal causes both a disturbance of function and a loss of function; the mechanism has been seriously interfered with; yet all those parts of the mechanism which still co-operate manifest their physiological aptitudes. The animal can live without its brain, ergo it can feel without its brain. Observation proves this, for it discovers the brainless animal manifesting various sensibilities, and combining various movements. The vision of the brainless animal is greatly impaired, but it nevertheless persists. The intelligence is greatly impaired, the spontaneity is reduced to a minimum; but still both intelligence and spontaneity are manifested.

35. The physiologist has only two conclusions open to him. Either he holds Sensation to be a property of nerve-tissue—and in that case he must assign it to the spinal cord as to the brain; or else he holds Sensation to be a function of an organ—and in that case, although analytically he may decompose the organism into separate organs, assigning special sensations to the reactions of each, he must still admit that in reality these organs only yield sensations as component parts of the organism. The notion of a separate organ, such as the brain, being the exclusive seat of sensation is thus seen to be untenable.

In popular phrase, “it is not the eye which sees, but the mind behind the eye.” It is not the stimulus which is the object felt—it is the change in consciousness—the reaction of the sensorium. No one would propound the absurdity that the retinal cells see, or the auditory cells hear (although by a conventional ellipsis these cells are said to be “percipient” of colors and sounds), yet many writers have no hesitation in asserting that the cerebral cells are the seats of these and all other sensations. In a hundred treatises may be read the most precise description of the transformation of molecular changes in the retinal cells into molecular changes in the cerebral cells, where, it is said, “we know that the stimulations become sensations.” Now who knows this? How can it be known? Nay, who, on reflection, fails to see that this cannot be so? If a sensation of sight were not much more than a molecular change in the cerebrum stimulated by a molecular change in the optic tract, three conclusions would follow, each of which is demonstrably erroneous:—

I. The cerebrum in a decapitated animal would respond by a sensation of sight to a retinal stimulation.

II. The animal deprived of its cerebrum could not respond by a sensation of sight to a retinal stimulation.

III. The same retinal stimulation would always produce the same cerebral process and the same sensation; whereas the sensation depends on the condition of the sensorium at the time.

36. The difference between the Reflex Theory and that here upheld is important in its general relations, and yet turns on a point which may easily appear insignificant. The Reflex Theory asserts that when a sensory nerve is stimulated, the excitation of the centre may either subdivide into two waves, one of which passes directly to the brain and there awakens sensation, the other passes over to the motor-roots and causes muscular contractions; or, instead of thus subdividing, the wave may pass at once to the motor-nerves, and then there is movement without sensation. This is obviously a restatement in anatomical terms of the observed fact that some reflexes take place consciously and some unconsciously. But what evidence is there for this anatomical statement? We have seen that there is none. According to all we actually know, and reasonably infer, the continuity of tissue and the irradiation of excitation are such that the stimulus wave must always affect the whole system, so that brain and cord being structurally united, their reactions must co-operate with varying energy dependent on their statical conditions at the time.[243]

37. The physiological fact that the irradiation is restricted to certain paths, and therefore only certain portions of the whole system are excited to discharge—the fact that stimulation takes effect along the lines of least resistance—is that which gives the Reflex Theory its plausible aspect. But this fact of restriction is not dependent on an anatomical disposition of structure, it is, as we have already seen (Problem II. § [166]), dependent on a fluctuating physiological disposition—a temporary statical condition of the centres. And it enables us to understand why the reflex action which is at one moment a distinctly conscious or even a volitional action, is at another sub-conscious or unconscious. When an object is placed in the hand of an infant the fingers close over it by a simple reflex. This having also been observed in the case of an infant born without a brain,[244] one might interpret it as normally taking place without brain co-operation, were there not good grounds for concluding that normally the brain must co-operate. Thus if the object be placed in the hand of a boy, or a man, the fingers will close, or not close—not according to an anatomical mechanism, but according to a physiological condition: if the attention preoccupy his sensorium elsewhere, his fingers will probably close, probably not; if his sensorium be directed towards the object, either by the urgency of the sensitive impression, or by some one’s pointing to the object, the fingers will close or not close, just as he chooses—perhaps the hand will be suddenly drawn away. The centre of innervation for the fingers is in the cord, and from this comes the final discharge of the sensitive stimulation; but the neural processes which preceded this discharge, and were consequent on the stimulation, were in each case somewhat different. In each case the impression on the skin was carried to the cord, and thence irradiated throughout the continuous neural axis, restricted to certain paths by the resistance it met with, but blending with waves of simultaneous excitations from other sources, the final discharge being the resultant of these component forces. We may suppose the brain to be the seat of consciousness, and yet not conclude that the brain was unaffected because the fingers closed unconsciously; any more than we conclude that the retina of the unoccupied eye is unaffected by light when with the other we are looking through a microscope, and only see objects with this eye—though directly we attend to the impressions on the other eye we see the objects which before were unseen. We know that the muscles of the back are all involved in walking, standing, etc., but we are seldom conscious of their co-operation till rheumatism or lumbago makes us painfully alive to it.

38. The two main positions of the Reflex Theory are, 1°, that reflex actions take place without brain co-operation,—as proved by observation of decapitated animals; 2°, that they take place without brain co-operation,—as proved by our being unconscious of them.

To these the answers are: 1°. The proof drawn from observation of decapitated animals is defective, because the conditions of the organism are then abnormal—there is a disturbance of the mechanism, and a loss of some of its components. The fact that a reflex occurs in the absence of the brain is no proof that reflexes when the brain is present occur without its participation. 2°. The absence of consciousness cannot be accepted as proof of the brain not being in action, because much brain-work is known to pass unconsciously, and there are cerebral reflexes which have the same characters as spinal reflexes.

39. A prick on the great toe traverses the whole length of the spinal axis with effects manifested in various organs—the muscles of the limb, the heart, the chest, the eyes, etc. The leg is withdrawn, the heart momently arrested, the eyes turned towards the source of irritation, the thoughts directed towards relief. These effects can be observed—there are others which lie beyond our observation, and can only be revealed by delicate experimental tests. But even the observable effects are very fluctuating, because they depend on fluctuating conditions. All we can say is, that so long as there is continuity of structure, there must be continuity of excitation; and the brain structurally connected with the centre of a sensory impression, must necessarily co-operate more or less in the reactions of that centre. In other words, the brain, although not the exclusive seat of sensation, plays a part in every particular sensation, so long as it forms a part of the stimulated organism.

40. This view being so widely opposed to the views current in physiological schools, I was gratified to find Dr. Crichton Browne led by his researches to a conclusion not unlike it in essential features. In his essay on the Functions of the Optic Thalami[245] (well worthy of attention on other grounds) he says: “Allowing the spinal cord a power of independent action, it may still be that it generally acts reflexly through, or in association with, a superior centre. The sensorial ganglia can undoubtedly act alone in a reflex manner, but they almost invariably consult the cerebrum before dealing with the impressions which they receive; so it may be that the spinal cord, though capable of spontaneous reaction, may yet commonly refer to some higher seat of compound co-ordination before sending forth an answer to any message brought to it.” What is here stated as a possible and occasional process, I consider to be a necessary and universal process. Dr. Browne acutely remarks that if “what may be termed the encephalic loop were an integral part of every reflex act, then the influence of an intracranial lesion in checking reflex action would not be difficult to understand”—and we may add the notorious influence of the brain in arresting reflex actions, and modifying them by the will, which is only explicable on the supposition that the cerebral and spinal centres are functionally associated. Dr. Browne further remarks: “In experimenting upon myself I have sometimes thought that when the toe is pricked the sensation of pain actually precedes the movement of withdrawal; and in experimenting upon patients with sluggish nervous systems I have certainly noticed that after the pricking of the toe the little cry of pain has anticipated the muscular contractions of the leg. Now this cry of pain is a secondary reflex act through the sensorial centre; it is the result of a discharge from efferent nerves from the summit of what we have spoken of as the encephalic loop line; and we should certainly not expect that it would be developed earlier than the primary reflexion upon the motor apparatus, unless indeed what we have regarded as the primary reflexion really itself took place by way of the loop line.”

41. The difference between a voluntary and involuntary act is not, I conceive, that in the one case the brain co-operates and in the other is inactive, but that while in both the brain co-operates, the state of the sensorium known as mental prevision or ideal stimulation, is present in the one, and absent or less conspicuous in the other. So likewise the difference between a normal reflex action accompanied, and the same action unaccompanied by consciousness, is not that the brain co-operates in the one and is inactive in the other, but that the state of the sensorium is somewhat different in the two cases. Movements which originally were voluntary and difficult of execution—accompanied therefore by brain co-operation—become by frequent repetition automatic, easy of execution, and unconscious—they are then said to depend on the direct action of the established mechanism. Granted. But what are the components of this mechanism? Are they not just those centres and organs which at first effected the movements? In becoming easy and automatic, the movements do not change their mechanism—the moving organs and the motor conditions remain what they were; all that is changed is the degree of consciousness, i. e. the state of the sensorium which precedes and succeeds the movement. It is this which constitutes the difficulty of the question. Some readers may consider that all is conceded when unconsciousness is admitted. But this is not so. My present argument is the physiological one that the brain co-operates in reflex actions whenever the brain is structurally united with the reflex centres; the psychological question as to whether consciousness is also involved in this brain co-operation must be debated on other grounds; and we have already seen that consciousness operates in gradations of infinite delicacy.

Observe a man performing some automatic action, such as planing a deal board, or cutting out a pattern, which he has done so often that he is now able to do it “mechanically.” It is certain that his brain co-operates, and that he could not act thus with an injured brain; yet he is said to act unconsciously, his brain occupied elsewhere as he whistles, talks to bystanders, or thinks of his wife and children. Yet the brain is acting as an overseer of his work, attentive to every stroke of the plane, every snip of the scissors; and this becomes evident directly his attention is otherwise absorbed by an interesting question addressed to him, or an interesting object meeting his eye: then the work pauses, his hands are arrested, and the automatic action will only be resumed when his attention is released—when he has answered your question, or satisfied himself about the object.

42. This is a step towards understanding the co-operation of the brain even in those connate reflexes which were not originally voluntary acts, but were from the first organized tendencies, and are capable of being realized in the absence of the brain. I admit that it is difficult to find proof of brain co-operation here, though I think the anatomical and physiological evidence render it highly probable. But distinct proof to the contrary would not suffice for the Reflex Theory—would not prove that reflex actions were insentient—unless there had previously been proved that which seems to me contradicted by the clearest and most massive evidence, namely, that the brain is the sole seat of sentience. This contradictory evidence we will now furnish.

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CHAPTER III.
INDUCTIONS FROM PARTICULAR OBSERVATIONS.

43. In the last chapter we surveyed the deductive evidence, from which the conclusion was that Reflexion necessarily involves Sensibility, but not necessarily any one particular mode of Sensibility, such as Consciousness, Pain, Discomfort, Attention, or the reaction of any one of the special Senses. Although each or all of these modes may be involved in the sensorial process which determines a reflex act, each or all may be absent. Such is the fact of observation. This fact is interpreted on the hypothesis that Reflexion is the exclusive property of the spinal cord, as Sensation is of the brain. When we come to examine the evidence for this hypothesis, we find it to move in a circle: the brain is said to be the exclusive seat of sensation, because reflex actions can be effected after its removal; and reflex actions are said to be insentient because they take place in the absence of the brain.

A gentleman was one day stoutly asserting that there were no gold-fields except in Mexico and Peru. A nugget, dug up in California, was presented to him, as evidence against his positive assertion. He was not in the least disconcerted. “This metal, sir, is, I own, extremely like gold; and you tell me that it passes as such in the market, having been declared by the assayers to be undistinguishable from the precious metal. All this I will not dispute. Nevertheless, the metal is not gold, but auruminium; it cannot be gold, because gold comes only from Mexico and Peru.” In vain was he informed that the geological formation was similar in California and Peru, and the metals similar; he had fixed in his mind the conclusion that gold existed only in Mexico and Peru: this was a law of nature; he had no reasons to give why it should be so; but such had been the admitted fact for many years, and from it he would not swerve. He was not fond of new-fangled notions, which, after all, would only lead us back to the exploded errors of the past. To accept the statement that gold was to be found elsewhere than in Mexico and Peru, would be to return to the opinion of the ancients, who thought there was gold in the upper regions of Tartary!

Sensation is not tangible, assayable, like gold. We can understand, therefore, that the very men who would make merry with the auruminium, would accept easily such a phrase as “reflex action.” The decapitated animal defends itself against injury, gets out of the way of annoyances, cleans itself, performs many of its ordinary actions, but is said to do these things without that Sensibility which, if its head were on, would guide them. Even before the Reflex Theory was invented this line of argument was used. Gall, referring to the experiments of Sue, previously noticed, says that “Sue confounds the effects of Irritability with those of Sensibility.”[246] Not gold, dear sir, but auruminium!

44. On investigating the phenomena we soon come upon two classes which must cause hesitation. We find that the brain has its reflex processes, of the same order as those of the cord; we find that these processes may be conscious or unconscious, voluntary or involuntary; so that we can no longer separate brain from cord on the ground of Reflexion. In this respect, at least, the two are mechanisms with similar powers. Turning now to the other class of phenomena, we find that precisely as the brain is an organ of Reflexion, the cord is an organ of Sensation. All the evidence we can have, from which to infer the presence of sensation, is furnished by the sensorial processes in the cord. Remove the brain, and the animal still manifests Sensibility, and this in degrees of energy and complexity proportional to the mechanisms still intact: some of these manifestations have the character of volitional actions, some of automatic actions, some of Memory, Judgment, and selective Adaptation. These we observe not indeed with the energy and variety of such manifestations when the brain co-operates, since the disturbance of the organism which is the consequence of the brain’s removal—or the meagreness of the organism which is the correlative of the brain never having been developed—must of course involve a corresponding difference in the observed phenomena; but the point here brought forward is that phenomena of the same order are manifested by organisms with or without a brain.

45. Let us go seriatim through the evidence of these two classes:—