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, but510 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 two511 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:—
CEREBRAL REFLEXES.
 
While Theory separated the actions of the cord from those of the brain on the ground of their being at times unconscious and involuntary, Observation disclosed that this distinction could not be maintained.
This step was taken by Dr. Laycock in 1840. In a striking paper247 read by him at the British Association in 1844, he brought together the evidence on which his view was founded. The idea has been adopted and illustrated in the writings of Dr. Carpenter, who now calls the action “unconscious cerebration.”
512 “I was led to this opinion,” Dr. Laycock says in announcing his view, “by the general principle that the ganglia within the cranium, being a continuation of the spinal cord, must necessarily be regulated as to their reaction on external agencies by laws identical with those governing the spinal ganglia and their analogues in the lower animals. If, therefore, the spinal cord is a centre of reflexion, the brain must also be one.” It is a matter of regret that Dr. Laycock did not extend this principle, and declare that whatever was true of the properties of the cranial centres must also be true of the spinal centres; if the brain have Sensibility, the spinal cord must also have it.
Dr. Laycock refers to the curious phenomena of Hydrophobia in proof that reflex actions may be excited by the optic nerves, or by a mere idea of water. When a mirror was presented to a patient, the reflexion of the light acting on his retina, in the manner of a reflexion from the surface of water, produced a convulsive sobbing, as in the attempt to swallow water, and the patient turned aside his head with expressions of terror. Money was given him to induce him to look a second time, but before he had looked a minute the same effect was produced.
The idea of water excited similar convulsions. No sooner was it suggested that the patient should swallow a little water than he seemed frightened, and began to cry out. By kindly encouragements he was brought to express his willingness to drink, but the sound of the water, as it was poured out again, brought on convulsions. In another case, “on our proposing to him to drink, he started up, and recovered his breath by a deep convulsive inspiration. On being urged to try, he took a cup of water in one hand and a spoon in the other. With as expression of terror, yet with great resolution, he filled the spoon and proceeded to carry it to his lips; but before513 it reached his mouth his courage forsook him, and he was forced to desist. He repeatedly renewed the attempt, but with no more success. His arm became rigid and immovable whenever he tried to raise it to his mouth, and he struggled in vain against this spasmodic resistance.”
In 1843 Griesinger—who appears to have known nothing of Dr. Laycock’s paper—published his remarkably suggestive memoir on Psychical Reflexes,248 in which he extends the principle of Reflexion to all the cerebro-spinal centres. The whole course of subsequent research has confirmed this view; so that we may say with Landry, “L’existence du pouvoir réflexe dans l’encéphale ou dans quelques unes de ses parties établit une nouvelle analogie entre le centre nerveux cranien et la moelle épinière.”249 Indeed we have only to consider the Laughter which follows a ludicrous idea, or the Terror which follows a suggestion of danger,—the varying and involuntary expression of Emotion,—and the curious phenomena of Imitation and Contagion,—to see how large a place cerebral reflexion occupies.
46. The existence of cerebral reflexion having been thus made manifest, Dr. Carpenter classed all reflex actions under three heads: 1°, the excito-motor, determined by the spinal cord; 2°, the sensori-motor, determined by the ganglia at the base of the brain; 3°, ideo-motor, determined by the brain. From all these Consciousness is absent. From the first, he supposes Sensation to be absent. As an artifice, such a classification may have its value, but it is physiologically and514 psychologically misleading. It sustains the hypothesis of an imaginary excito-motor mechanism. It restricts Sensibility to one of its many modes. It fails altogether to connect Sensation with Thought, the Logic of Feeling with the Logic of Signs.
47. The view of Sensibility as common to the whole cerebro-spinal axis is by no means new. Robert Whytt maintained it. Prochaska held that the spinal cord formed the greater part of the sensorium commune; and he adduced, in proof, the familiar facts of sensibility manifested by headless animals. The next writer whom I can discover to have held this opinion is J. J. Sue,—the father of the celebrated French romance-writer,—who, in 1803, conceived that his experiments proved the spinal cord to be capable of replacing, to a certain extent, the functions of the brain.250 Next came Legallois,251 who undertook to show, by a series of experiments, that the principle of sensation and movement, in the trunk and extremities, has its seat in the spinal cord. The mere division of the cord, he said, produces “the astonishing result of an animal, in which the head and the body enjoy separate vitality, the head living as if the body did not exist, and the body living as if the head did not exist. Guinea-pigs, after decapitation, seem very sensitive to the pain caused by the wound in the neck; they alternately carry first one hind-leg and then the other, to the spot, as if to scratch it. Kittens also do the same.”
A few years afterwards, 1817, Dr. Wilson Philip concluded that “the spinal marrow possesses sensorial power, as appears from very simple experiments”; but he held515 the brain to be the chief source of sensorial power.252 The following year, Lallemand supported this opinion by the very curious phenomena exhibited by infants born without brains: these infants breathed, swallowed, sucked, squalled, and gave very unequivocal signs of sensibility. The value of such observations consists in disproving the objection frequently urged against the evidence of decapitated animals, namely, that in these animals the spinal cord preserves the remains of a sensibility endowed by the brain.
Longet here places an observation recorded by Beyer. A new-born infant, whose brain, during the birth, had been completely extirpated (to save the mother’s life), was wrapped in a towel, and placed in the corner of the room, as a lifeless mass. While the surgeon was giving all his care to the mother, he heard with horror a kind of murmur proceeding from the spot where the body had been placed. In three minutes a distinct cry was heard. The towel was removed, and, to the surprise of all, this brainless infant was seen struggling with rapid movement of its arms and legs. It cried, and gave other signs of sensibility for several minutes.253
In 1828 Calmeil arrived at the same conclusion as that reached by Legallois, Wilson Philip, and Lallemand. Indeed when, in 1833, the Reflex Theory appeared, this opinion was so firmly rooted, that we find Mr. Grainger combating it as the established error of the day. He takes as much pains to show that physiologists are wrong in attributing sensation to the spinal cord, as I am here taking to show that they were right.254 “It is, indeed,516 apparent,” he says, “that the whole question concerning the truth or falsehood of the theory which attributes the reflex power to the spinal cord hinges upon the correctness or incorrectness of the received doctrines respecting the seat of sensation and volition; so that until those doctrines are proved to be false, it is impossible to establish the hypothesis of Dr. Hall.”255
The reader is requested to take note of this, because when we come to the evidence which proves the spinal cord to be a centre of sensation, we shall find that the only ground for rejecting that evidence is the assumed truth of the Reflex Theory, coupled with the assumption of the brain being the exclusive seat of sensation. Whereas if the evidence proves that the spinal cord is a sensational centre, then the Reflex Theory is destroyed, and cannot be urged against such evidence.
48. Thus many of the facts which prove the sensational function of the spinal cord were known, and even a vague conception of their real significance was general, until the Reflex Theory came to explain all such facts as the results of mechanical adjustment, and of a new nervous principle called “Reflexion.” For many years this theory has reigned, and met with but little opposition. Yet the true doctrine has not wanted defenders in Germany. Nasse256 denied that decapitated animals showed no spontaneity; he asserted that they exhibited clear signs of mental activity. Carus sarcastically pointed out that the word “reflex” was replacing “irritability,” as a key to unlock all puzzles; and he took up a position which is very similar to the one occupied in these pages, namely, that the spinal cord being formed of gray matter as well as of fibres, it must have sensibility and power of reacting on nervous stimulus, no less than conductibility;517 that, in fact, it is a centre, and must act like all other nerve-centres.257 J. W. Arnold opposed the Reflex Theory in a very remarkable little work, in which he vindicates the claim of the spinal cord as a sensory and motor centre, although denying to its actions any volitional character.258 This was in 1844. Eleven years elapsed without any further opposition, when Edward Pflüger, in 1853, published his work on the Sensorial Functions of the spinal cord.259 In this work he recurred to the old views of Prochaska and Legallois; but although he attacked Marshall Hall with merciless severity, he did not point out the fundamental error of the Reflex Theory, which theory he seems to accept. Nor did he give his views that philosophical and anatomical basis which could alone render his interpretations acceptable. Added to this, the tone of asperity in which his work was written, created some prejudice against him; and thus, while many admitted his facts, they rejected his conclusions.260
In 1858 Professor Owen read a paper of mine at the Leeds meeting of the British Association, on “The spinal cord as a centre of Sensation and Volition,” in which a rapid indication of my point of view, and an account of some experiments to illustrate it, were given—not, I believe, conclusive to any of the audience. Indeed, the subject was too vast to be discussed in such a paper; and my object was rather to excite new inquiry, than to make converts to a view which could only be embraced after a thorough reinvestigation of the dominant theories.
In 1859 appeared Schiff’s work;261 and here we find a518 large space allotted to the discussion of Pflüger’s doctrine. Schiff, whose immense experience as an experimentalist, and whose acuteness and caution every one will highly estimate, frankly pronounces in favor of the sensational character of spinal actions; but he denies that they are volitional, and objects strongly to the introduction of any such idea as that of “psychical activity.” He thinks it utterly untenable to suppose that impressions have reactions in the brain which they have not in the spinal cord:—if one has sensibility, the other must have it; and he thinks that, so far from the actions of the cord being distinguishable from those of the brain by the character of “reflexion,” and depending on a mechanical arrangement—all actions, cerebral or spinal, are reflex; all depend on a mechanical arrangement.262
Since that time there has been the remarkable work of Goltz, so often cited in these pages,263 and his subsequent experiments on dogs, which (although he does not decisively adopt the views of Pflüger) furnish ample evidence that sensation and volition cannot be exclusively localised in the brain.
49. Heubel’s interesting experiments264 show that a frog may be thrown into a state of profound sleep by the withdrawal of all external stimulation, and in this state will remain lying on its back for hours. Now this position is one so very uncomfortable that, when awake, the frog will not retain it a moment, if free to turn round; and519 when asleep, a prick on the toe, a sudden noise, or a beam of light will awaken it, causing it to turn. That is to say, the withdrawal of the normal stimuli so lowers the sensibility of the frog’s nerve-centres, that he does not feel the effects of the unusual position, but feels them directly the centres are stimulated into activity. All this is intelligible enough on the supposition of the state of sleep being dependent on a lowering of the cerebral activity. But what shall we say on learning that precisely the same phenomena are manifested by a brainless frog? Every one knows that the brainless frog is intolerant of lying on its back, and immediately turns round, if placed on it. Yet the brainless frog may be thrown into deep sleep by the same exclusion of external stimuli; from which he also will be awakened by a prick, a noise, or a beam of light; and no sooner is he awakened than he at once turns round. Were the brainless frog incapable of sensation, a prick on his toe would cause a simple reflex withdrawal of the leg; but this is not the effect; on the contrary, the stimulus excites the whole spinal cord, and whatever sensation of discomfort may be caused by the abnormal position of the limbs in an uninjured awakened frog, is excited in the brainless frog.
50. I need not swell this chapter with examples of Sensibility in animals deprived of the brain; many have already been given, and any text-book of Physiology will supply more. No one disputes the observations, only the inference that these manifestations were sentient: they are said to have been merely mechanical reflexes. If, however, we can detect in them some evidence of what all recognize as peculiarly characteristic of Mind, the mechanical interpretation will be less plausible.
At the outset the reader must be warned against exaggerating and distorting the bearing of my remarks, and must not suppose that I disregard the vast differences520 between the Logic of Signs which belongs to Thought, and the Logic of Feeling which belongs to Sensation, nor suppose that I look upon the spinal cord as a mental organ having the same functions as the brain. All that I wish to establish is the common character of spinal and cerebral processes, modified as each is by the character of the actions initiated by the process.
51. This premised, let us begin with the evidence of
DISCRIMINATION.
 
Although this process is usually regarded as purely psychological, it must obviously have its physiological side; we find it in Sensation as in Ideation, and may expect to find it in unconscious as in conscious processes—in a word, in all sensorial processes whatever. Place a bit of marble on your tongue, and it will be touched, but not tasted: the sensations of contact and temperature will excite reflexes, but little or no reflexes from parotid and salivary glands. A difference in sensation has a corresponding difference in reflex action; which may be made evident by removing the tasteless marble, and replacing it by a pinch of carbonate of lime, i. e. the marble in another state reduced to a powder: this will excite a sensation of taste, and a secretion from the glands. In both cases your sentient organism was affected, but it reacted differently because the difference of the stimulation was discriminated: consciously or unconsciously, you felt differently. Again: touch the back of your mouth with your finger, or a feather, and a convulsive contraction of the gullet responds, followed by vomiting, if the excitation be renewed. Yet these same nerves and muscles respond by the totally opposite action of swallowing, if instead of the stimulation coming from your finger, it come from the pressure of food or drink.
521 Analogous experiments on animals without their brains yield similar results.265 The salivary secretion and the ordinary reactions of Taste are provoked by sapid substances. Still more conclusive are the observations made on a dog whose spinal cord has been divided, and who therefore according to the reigning ideas is incapable of feeling any impression made on parts below the section. A pencil inserted in the rectum causes a reaction of the muscles energetically resisting the entrance of this foreign body; yet this rectum so sensitive in its reaction on the stimulus of the pencil, responds by the totally different reaction—the relaxation of the muscles—on the stimulus of f?cal matters.
52. “This is all mechanical,” you say? Mechanical, no doubt, as all actions are; but the question here is whether among the conditions of the mechanical action Sensibility has a place? The answer can only be grounded on induction. The actions of the dog are analogous to the actions which you know were sentient in yourself. There was in both a discrimination, in both a corresponding reaction. I admit that what is here called “discrimination” is the application of a logical term to a mechanical process; I admit that if the spinal mechanism is insentient, the fact of discrimination may still be manifested; but I conceive that the many and coercive grounds for admitting that the mechanism is sentient gain further support in the evidence of discrimination. Every particular sensation has its corresponding reaction; and although this has been acquired during ancestral or individual experiences, so that in the majority of cases there is no consciousness accompanying the operation, this, as we have seen, is not a valid argument against the existence of a sensorial process. We have only to lower the Sensibility of the cord by an?sthetics, or to preoccupy522 its energies by some other excitation, and the reaction fails.
MEMORY.
 
53. “But discrimination, if not a purely physical process, implies Memory?” No doubt. And what is Memory—on its physiological side—but an organized tendency to react on lines previously traversed? As Griesinger truly says: “There is Memory in all the functions of the central organs, including the spinal cord. There is one for reflex actions, no less than for sense-images, words, and ideas.” Gratiolet makes a similar assertion.266 Indeed if, as we have seen, reflex actions are partly connate, and partly acquired, it is obvious that the second class must involve that very reproduction of experiences, which in the sphere of Intellect is called Memory.
There is assuredly something paradoxical at first in this application of the terms of the Logic of Signs, yet the psychologist will find it of great service. But if the terms discrimination and memory be objected to, they may be replaced by some such phrase as the “adaptation of the mechanism to varying impulses.” On its objective side, Discrimination is Neural Grouping; on its subjective side, it is Association of experiences.
INSTINCT.
 
54. If we can detect evidences of Volition and Instinct in the absence of the brain, our thesis may be considered less questionable. And such evidence there is. Goltz decapitated a male frog (in the pairing season), and observed that it not only sought, grasped, and energetically523 embraced a female, but could always discriminate a female from a male. Thus when a male frog closely resembling a female in size and shape was presented to this decapitated animal, he clasped it, but rapidly let it go again, whereas even the dead body of a female was held as in a vice. Goltz tried to delude this brainless animal in various ways, always in vain. Only a female would be held in his embrace. Goltz then presented a female in a reversed position, so that the head was grasped by the male. Now here, had there been simply a reflex machine, incapable of sentient discrimination, the clutched female would have been held in this position, just like any other object which excited the reflex; there would have been no “sense of incongruity,” such as Goltz noticed in his frog, who at once began a series of movements by which he was enabled, without letting the female escape, to bring her into the proper position. To render this observation still more significant, I may add that Goltz did not find all male frogs act thus—many relinquished the female thus improperly presented to them. Such phenomena observed in frogs possessing brains, would be accepted as evidence of sexual instinct and volition.
Further: Goltz removed the brain from a frog, which he then held under water, gently pressing the body so as to drive the air out of its lungs; the body being then heavier than the water sank to the bottom, where it remained motionless. He repeated this procedure with another frog, not brainless but blinded. This one sank also, but in a few minutes rose to the surface to breathe. This difference naturally suggests that the brainless frog was insensible of the condition which in the other caused a movement of relief. The one felt impending suffocation, the other felt nothing. Such was the interpretation of a German friend in whose presence I repeated the experiment.524 But I had been instructed by Goltz, and bade my friend wait awhile. He did so, and saw the brainless frog slowly rise to the surface and breathe there like his blinded companion. So that the only difference observable was in the lessened sensibility of the brainless frog.
55. But Goltz records a still more conclusive case. In a large vessel of water he inverted a glass jar also containing water, which could then only be retained in the jar by atmospheric pressure. Through the neck of this inverted jar he thrust a blinded frog, not having pressed the air out of its lungs. It rose at once in the jar, touching the inverted bottom with its nose, and when the necessity of fresh air was felt, the frog began restlessly feeling about the surface of its prison till an issue was found in the neck of the jar, through which it dashed into the vessel, and at once rose to the surface of the water to breathe. In this observation are plainly manifested the stimulation of uneasy sensation, the volition of seeking relief, and the discrimination of it when found. If this frog was a sentient mechanism, what shall we say to the fact that a brainless frog was observed to go through precisely the same series of actions? Goltz pertinently remarks: “So long as physiologists satisfied themselves that the brain was the sole organ of sensation, it was easy to declare all the actions of the brainless animal to be merely reflex. But now we must ask whether the greater part of these actions are not due to the power of adaptation in the central organs, and are therefore to be struck out of the class of simple reflexes? If I bind one leg of a brainless frog and observe that he not only sees an obstacle, but crawls aside from it, I must regard these movements as regulated by his central power of adaptation; but now suppose I unbind the leg and remove the obstacle, then if I prick the frog he hops forward. Must I now declare this hop to have been a525 simple reflex? Not at all. In both cases the physiological processes have been similar.”
* * * * *
56. There are no doubt readers who will dismiss all evidence drawn from experiments on frogs, as irrelevant to mammals and man. Let us therefore see how the evidence stands with respect to animals higher in the scale, endowed with less questionable mental faculties. In a former chapter (Problem II. § 29) we recorded the marked results of removing the cerebral hemispheres; and at the same time suggested that these by no means justified the conclusion usually drawn respecting the hemispheres as the exclusive seat of sensation. And this on two grounds: First, because the absence of some sensitive phenomena does not prevent the presence of others: the mutilated organism is still capable of manifesting Sensibility in those organs which remain intact. Secondly, because were the mutilation followed by total destruction of Sensibility, this would not prove Sensibility in the normal organism to have its seat in the part injured. If the removal of a pin will destroy the chronometric action of a watch, we do not thence infer that the chronometric action was the function of this pin. And this objection has the greater force when we remember that one hemisphere may be removed without the consequent loss of a single function, and both may be removed without the loss of several functions usually ascribed to cerebral influence.267
526 57. Consider the analogous effects of injuries to or removal of the Cerebellum, in causing disturbance of locomotion, whence the conclusion has been drawn that the Cerebellum is the exclusive organ of muscular co-ordination, in spite of the unquestionable evidence that very many muscular co-ordinations still persist after this organ is removed. What is the part played by the Cerebellum I do not pause here to examine.268 I only say that the movements of swimming, sucking, swallowing, breathing, crying, micturition, defecation, etc., are co-ordinated as well after removal of the Cerebellum as they were before, and that consequently their co-ordination has not its seat in the Cerebellum. The parallelism is obvious. Removal of the Cerebrum causes a disturbance in the combination of sensations, and the execution of certain sense-guided actions, but causes little appreciable disturbance in others. Removal of the Cerebellum causes a disturbance in the combination of certain muscular sensations, and the execution of certain co-ordinated actions, with little appreciable disturbance in others.
58. So little have the facts been surveyed and estimated in their entirety that there is perhaps no subject on which physiologists are more agreed than on the function of the Cerebellum being that of co-ordination. Yet consider this decisive experiment. I etherized three healthy frogs, from one I removed the entire cranial centres; from another I removed only the cerebellum; and,527 leaving the third in possession of an intact encephalon, I made two sections of the posterior columns of the spinal cord. The two first hopped, swam, used their legs in defence, and exhibited a variety of muscular co-ordinations, although in both the supposed organ of co-ordination was absent. Whereas the third, which had this organ intact, and was capable of moving each limb separately, and each pair of limbs separately, was utterly incapable of moving all four simultaneously. Why was this? Obviously because in the first two frogs the motor mechanism remained intact, and only the cerebral and cerebellar influence was removed; in the third frog the sensory part of the motor mechanism had been divided, and no combination of the limbs was possible.
59. Physiological induction agrees with anatomical induction in assigning to the cerebrum and cerebellum the office of incitation and regulation rather than of innervation; for, as we have seen, no nerve issues directly from them (Problem II. § 7). Consequently the effects of injuries to these centres are losses of spontaneity and of complexity in the manifestations. Inasmuch as in the intact organism all sensory impressions are propagated throughout the nervous centres, the reactions of these highest centres will enter into the complex of every adjusted movement; so the abolition of these centres will be the dropping of a link in the chain, the abolition of a special element in the complex group. The organs which are still intact will react, each in its own way, on being stimulated; but the reaction will be without the modifying influence of the absent centres. For instance, the retinal stimulation from a luminous impression normally calls up a cluster of associated feelings derived originally from other senses, and a perception of the object is associated with emotions of desire, terror, etc., according to the past history of the organism, and its organized reactions,528 due to hereditary or acquired experiences. It is these which form the complex feeling discharged in the particular movement of prehension, or flight. Remove the brain, and there can be no longer this cluster of associated neural groups excited; there will be therefore no emotion, simply the visual sensation, and such a movement as is directly associated with it. The brainless dog moans when hurt, it does not bark at the cat which it nevertheless sees, and avoids as a mere obstacle in its path; the cat will cry, it will not mew. The present pain moves the vocal organs, but does not revive associated experiences. All those combinations by which a series of dependent actions result from a single stimulation are frustrated when the mechanism is disturbed, so that the mutilated animal can no longer recognize its prey or its enemy, to feed on the one and fly from the other; no longer builds its habitation, or rears its offspring. It can still live, feed, sleep, move, and defend itself against present discomfort; it cannot find its food, or protect itself against prospective discomfort. We must supply the place of its Intelligence. We must give it the food, and protect it from injuries.
There is therefore ample evidence to show that what is specially known as Intelligence is very imperfect after the cerebral influence has been abolished; but this does not prove the Cerebrum to be the exclusive seat of Intelligence, it only proves it to be an indispensable factor in a complex of factors. Still less does it prove the Cerebrum to be the exclusive seat of Sensation, Instinct, Volition; for these may be manifested after its removal, although of course even these will be impaired by the loss of one factor.
60. And here an objection must be anticipated. In spite of the familiar experience that one mode of Sensibility may be destroyed without involving the destruction529 of other modes, there is a general belief—derived from a mistaken conception of what is really represented by the unity of Consciousness—that Consciousness disappears altogether when it disappears at all; and hence, since Sensation is supposed to imply Consciousness, it also cannot be divisible, but must vanish altogether if it vanish at all. The first answer is that Sensation as an abstraction is neither divisible nor indivisible; but as a generalized expression of concrete sensorial processes it is reducible to these processes, and divisible as they are. No one doubts that we may lose a whole class of special sensations—sight, hearing, pain, temperature, etc.—yet retain all the others. No one doubts that we may lose a whole class of registered experiences—forget a language, or lose memory of places so familiar as the streets of the small town we inhabit, or of faces so familiar as those of friends and relatives, while the names of these streets and friends are still remembered when the sounds are heard. Yet sensation and intelligence are not wholly lost. The mind is still erect amid these ruins.269
61. This premised, let us consider the experimental evidence. Flourens declares that when he remov............