The Principles of Psychology, Vols. 1-2

But is the consciousness which accompanies the activity of the cortex the only consciousness that man has ? or are his lower centres conscious as well ? This, is a difficult question to decide, how difficult one only learns when one discovers that the cortex-conscious ness itself of certain objects can be seemingly annihilated in any good hypnotic subject by a bare wave of his operacommon to talk of an ' ideational centre ' as of something distinct from the aggregate of other centres. Fortunately this custom is already on the wane.

* Rech. Exp. sur le Fonctionnement des Centres Psycho-moteurs (Brus sels, 1885). \ I ought to add, however, that Fra^ois-Franck (Fonctious Motrices, p. 370) got, in two dogs and a cat, a different result from this sort of ' cir fjumvallation."' tor's hand, and yet be proved by circumstantial evidence to exist all the while in a split-off condition, quite as ' ejective ' * to the rest of the subject's mind as that mind is to the mind of the bystanders, f The lower centres themselves may conceivably all the while have a split-off consciousness of their own, similarly ejective to the cortex-consciousness; but whether they have it or not can never be known from merely introspective evidence. Meanwhile the fact that occipital destruction in man may cause a blindness which is apparently absolute (no feeling remaining either of light or dark over one half of the field of view), would lead us to suppose that if our lower optical centres, the corpora quadrigemina, and thalami, do have any consciousness, it is at all events a consciousness which does not mix with that which accompanies the cortical activities, and which has nothing to do with our personal Self. In lower animals this may not be so much the case. The traces of sight found (supra, p. 46) in dogs and monkeys whose occip ital lobes were entirely destroyed, may possibly have been due to the fact that the lower centres of these animals saw, and that what they saw was not ejective but objective to the remaining cortex, i.e. it formed part of one and the same inner world with the things which that cortex per ceived. It may be, however, that the phenomena were due to the fact that in these animals the cortical ' centres ' for vision reach outside of the occipital zone, and that destruc tion of the latter fails to remove them as completely as in man. This, as we know, is the opinion of the experiment ers themselves.

For practical purposes, nevertheless, and limiting the meaning of the word consciousness to the per sonal self of the individual, we can pretty confidently answer the question prefixed to this paragraph by saying that the cortex is the sole organ of consciousness in man.$ If there be any consciousness pertaining to the lower centres, it is a consciousness of which the self knows nothing. Another problem, not so metaphysical, remains. The most general and striking fact connected with cortical in jury is that of the restoration of function. Functions lost at first are after a few days or weeks restored. How are ive to understand this restitution ?

1) Restitution is due to the vicarious action either of the rest of the cortex or of centres lower down, acquiring func tions which until then they had not performed ; 2) It is due to the remaining centres (whether cortical or 'lower') resuming functions which they had always had, but of which the wound had temporarily inhibited the exercise. This is the view of which Goltz and Brown- Sequard are the most distinguished defenders. Inhibition is a vera causa, of that there can be no doubt. The pneumogastric nerve inhibits the heart, the splanch nic inhibits the intestinal movements, and the superior laryngeal those of inspiration. The nerve-irritations which may inhibit the contraction of arterioles are innumerable, and reflex actions are often repressed by the simultaneous excitement of other sensory nerves. For all such facts the reader must consult the treatises on physiology. "What concerns us here is the inhibition exerted by different parts of ^ne nerve-centres, when irritated, on the activity of dis tant parts. The naccidity of a frog from ' shock,' for a, minute or so after his medulla oblongata is cut, is an in hibition from the seat of injury which quickly passes away.

What is known as ' surgical shock ' (unconsciousness, pallor, dilatation of splanchnic blood-vessels, and general syncope and collapse) in the human subject is an inhibition which lasts a longer time. Goltz, Freusberg, and others, cutting the spinal cord in dogs, proved that there were functions inhibited still longer by the wound, but which re established themselves ultimately if the animal was kept alive. The lumbar region of the cord was thus found to contain independent vase-motor centres, centres for erec-

tion, for control of the sphincters, etc., which could be excited to activity by tactile stimuli and as readily reinhibited by others simultaneously applied.* "We may therefore plausibly suppose that the rapid reappearance of motility, vision, etc., after their first disappearance in consequence of a cortical mutilation, is due to the passing off of inhibitions exerted by the irritated surface of the wound. The only question is whether all restorations of function must be explained in this one simple way, or whether some part of them may not be owing to the formation of entirely uew paths in the remaining centres, by which they become ' educated ' to duties which they did not originally possess. In favor of an indefinite extension of the inhibition theory facts may be cited such as the following : In dogs whose dis turbances due to cortical lesion have disappeared, they may in consequence of some inner or outer accident reappear in all their intensity for 24 hours or so and then disappear again, f In a dog made half blind by an operation, and then shut up in the dark, vision comes back just as quickly as in other similar dogs whose sight is exercised systematically every day4 A dog which has learned to beg before the operation recommences this practice quite spontaneously a week after a double-sided ablation of the motor zone.§ Occasionally, in a pigeon (or even, it is said, in a dog) we see the disturbances less marked immediately after the operation than they are half an hour later. | This would be impossible were they due to the subtraction of the organs which normally carried them on. Moreover the entire drift of recent physiological and pathological specu lation is towards enthroning inhibition as an ever-present and indispensable condition of orderly activity. We shall see how great is its importance, in the chapter on the "Will. Mr.

Charles Mercier considers that no muscular contraction, once begun, would ever stop without it, short of exhaustion of the system ; * and Brown-Sequard has for years been accumulating examples to show how far its influence ex tends, f Under these circumstances it seems as if error might more probably lie in curtailing its sphere too much than in stretching it too far as an explanation of the phenomena following cortical lesion. J On the other hand, if we admit no re-education of cen tres, we not only fly in the face of an a priori probability, but we find ourselves compelled by facts to suppose an almost incredible number of functions natively lodged in the centres below the thalami or even in those below the corpora quadrigemina. I will consider the a priori objection after first taking a look at the facts which I have in mind. They confront us the moment we ask ourselves just which are the parts ivhich perform the functions abolished by an operation after sufficient time has elapsed for restoration to occur ?

The first observers thought that they must be the cor responding parts of the opposite or intact hemisphere. But as long ago as 1875 Carville and Duret tested this by cutting out the fore-leg-centre on one side, in a dog, and then, after waiting till restitution had occurred, cutting it out on the opposite side as well. Goltz and others have done the same thing. § If the opposite side were really the seat of the restored function, the original palsy should have appeared again and been permanent. But it did not appear at all ; there appeared only a palsy of the hitherto unaffected side. The next supposition is that the parts surrounding the cut-out region learn vicariously to perform its duties. But here, again, experiment seems to upset the hypothesis, so far as the motor zone goes at least ; for we may wait till motility has returned in the affected limb, and then both irritate the

f Brown-Sequard has given a resume of his opinions in the Archives de Physiologic for Oct. 1889, 5rne. Serie, vol. I. p 751. \ Goltz first applied the inhibition theory to the brain in his ' Verrichtungen des Grosshirns,' p. 39 ff. On the general philosophy of Inhibition the reader may consult Brunton's ' Pharmakology and Therapeutics,1 p. 154 ff., and also ' Nature/ vol. 27, p. 419 ff. § E.g. Herzen, Herman u. Schwalbe's Jahres-bericht for 1886, PhysioL AJbth. p. 38. (Experiments on new-born puppies.?

cortex surrounding the wound without exciting the limb to movement, and ablate it, without bringing back the vanished palsy.* It would accordingly seem that the cere bral centres below the cortex must be the seat of the regained activities. But Goltz destroyed a dog's entire left hemi sphere, together with the corpus striatum and the thalamus on that side, and kept him alive until a surprisingly small amount of motor and tactile disturbance remained.t These centres cannot here have accounted for the restitution. He has even, as it would appear, J ablated both the hemispheres of a dog, and kept him alive 51 days, able to walk and stand. The corpora striata and thalami in this dog were also prac tically gone. In view of such results we seem driven, with M. Francois-Franck,§ to fall back on the ganglia lower still, or even on the spinal cord as the ' vicarious ' organ of which we are in quest. If the abeyance of function between the operation and the restoration was due exclusively to inhibi tion, then we must suppose these lowest centres to be in reality extremely accomplished organs. They must always have done what we now find them doing after function is restored, even when the hemispheres were intact. Of course this is conceivably the case ; yet it does not seem very plausible. And the a priori considerations which a moment since I said I should urge, make it less plausible still.

For, in the first place, the brain is essentially a place of currents, which run in organized paths. Loss of function can only mean one of two things, either that a current can no longer run in, or that if it runs in, it can no longer run out, by its old path. Either of these inabilities may come from a local ablation; and ' restitution ' can then only mean that, in spite of a temporary block, an inrunning current has at last become enabled to flow out by its old path again — e.g., the sound of ' give your paw ' discharges after some

* Fran9ois-Franck : op. cit. p. 382. Results are somewhat contradictory. weeks into the same canine muscles into which it used to discharge before the operation. As far as the cortex itself goes, since one of the purposes for which it actually exists is the production of new paths/ the only question before us is : Is the formation of these particular ' vicarious ' paths too much to expect of its plastic powers ? It would cer tainly be too much to expect that a hemisphere should receive currents from optic fibres whose arriving -place with in it is destroyed, or that it should discharge into fibres of the pyramidal strand if their place of exit is broken down. Such lesions as these must be irreparable ivithin that hemisphere. Yet even then, through the other hemisphere, the corpus callosum, and the bilateral connections in the spinal cord, one can imagine some road by which the old muscles might eventually be innervated by the same in coming currents which innervated them before the block. And for all minor interruptions, not involving the arrivingplace of the 'cortico-petal' or the place of exit of the 'corticofugal ' fibres, roundabout paths of some sort through the affected hemisphere itself must exist, for every point of it is, remotely at least, in potential communication with every other point. The normal paths are only paths of least resistance. If they get blocked or cut, paths formerly more resistant become the least resistant paths under the changed conditions. It must never be forgotten that a current that runs in has got to run out somewhere ; and if it only once succeeds by accident in striking into its old place of exit again, the thrill of satisfaction which the consciousness connected with the whole residual brain then receives wil] reinforce and fix the paths of that moment and make them more likely to be struck into again.

The resultant feeling that the old habitual act is at last successfully back again, becomes itself a new stimulus which stamps all the exist ing currents in. It is matter of experience that such feel ings of successful achievement do tend to fix in our memory whatever processes have led to them ; and we shall have * The Chapters on Habit, Association, Memory, and Perception will change our present preliminary conjecture that that is one of its essential uses, into an unshakable conviction.

a good deal more to say upon the subject when we come to the Chapter on the Will. My conclusion then is this : that some of the restitution of function (especially where the cortical lesion is not too great) is probably due to genuinely vicarious function on the p'irt of the centres that remain ; whilst some of it is due to the passing off of inhibitions. In other words, both the vicarious theory and the inhibition theory are true in their measure. But as for determining that measure, or saying which centres are vicarious, and to what extent they can learn new tricks, that is impossible at present.

And now, after learning all these facts, what are we to think of the child and the candle-flame, and of that scheme which provisionally imposed itself on our acceptance after surveying the actions of the frog ? (Cf. pp. 25-6, supra.) It will be remembered that we then considered the lower cen tres en masse as machines for responding to present senseimpressions exclusively, and the hemispheres as equally exclusive organs oi action from inward considerations or ideas ; and that, following Meynert, we supposed the hemi spheres to have no native tendencies to determinate activity, but to be merely superadded organs for breaking up the various reflexes performed by the lower centres, and com bining their motor and sensory elements in novel ways. It will also be remembered that I prophesied that we should be obliged to soften down the sharpness of this distinction after we had completed our survey of the farther facts. The time has now come for that correction to be made.

Wider and completer observations show us both that the lower centres are more spontaneous, and that the hemi spheres are more automatic, than the Meynert scheme allows. Schrader's observations in Goltz's Laboratory on hemisphereless frogs* and pigeons f give an idea quite different from the picture of these creatures which is classically current. Steiner's J observations on frogs already went a good way in the same direction, showing, for example, that locomotion is a well-developed function of the medulla oblongata. But Schrader, by great care in the operation, and by keeping the frogs a long time alive, found that at least in some of them the spinal cord would produce movements of locomotion when the frog was smartly roused by a poke, and that swimming and croaking could sometimes be performed when nothing above the medulla oblongata remained.* Schrader's hemisphereless frogs moved spontaneously, ate flies, buried themselves in the ground, and in short did many things which before his observations were supposed to be impossible unless the hemispheres remained. Steinerf and Yulpian have re marked an even greater vivacity in fishes deprived of their hemispheres. Vulpian says of his brainless carps:): that three days after the operation one of them darted at food and at a knot tied on the end of a string, holding the latter so tight between his jaws that his head was drawn out of water. Later, "they see morsels of white of egg; the moment these sink through the water in front of them, they follow and seize them, sometimes after they are on the bottom, sometimes before they have reached it. In captur ing and swallowing this food they execute just the same movements as the intact carps which are in the same aqua rium. The only difference is that they seem to see them at less distance, seek them with less impetuosity and less per severance in all the points of the bottom of the aquarium, but they struggle (so to speak) sometimes with the sound carps to grasp the morsels. It is certain that they do not confound these bits of white of egg with other white bodies, small pebbles for example, which are at the bottom of the water.

The same carp which, three days after operation, seized the knot on a piece of string, no longer snaps at it now, but if one brings it near her, she draws away from it by swimming backwards before it comes into contact with * LOG. cit. pp. 80, 82-3. Schrader also found a biting-rettex developed when the medulla oblongata is cut through just behind the cerebellum, f Berlin Akad. Sitzungsberichte for 1886. j Comptes Rendus, vol. 102, p. 90. her mouth."* Already on pp. 9-10, as the reader may re* member, we instanced those adaptations of conduct to ne^ conditions, on the part of the frog's spinal cord and thalami, which led Pfliiger and Lewes on the one hand and Goltz on the other to locate in these organs an intelligence akin to that of which the hemispheres are the seat.

When it comes to birds deprived of their hemispheres, the evidence that some of their acts have conscious purpose behind them is quite as persuasive. In pigeons Schrader found that the state of somnolence lasted only three or four days, after which time the birds began indefatigably to walk about the room. They climbed out of boxes in which they were put, jumped over or flew up upon obstacles, and their sight was so perfect that neither in walking nor flying did they ever strike any object in the room. They had also definite ends or purposes, flying straight for more convenient perching places when made uncomfortable by movements imparted to those on which they stood ; and of several possible perches they always chose the most con venient. "If we give the dove the choice of a horizontal bar (Recti) or an equally distant table to fly to, she always gives decided preference to the table. Indeed she chooses the table even if it is several meters farther off than the bar or the chair." Placed on the back of a chair, she flies first to the seat and then to the floor, and in general " will for sake a high position, although it give her sufficiently firm support, and in order to reach the ground will make use of the environing objects as intermediate goals of flight, show ing a perfectly correct judgment of their distance. Although able to fly directly to the ground, she prefers to make the journey in successive stages. . . . Once on the ground, she hardly ever rises spontaneously into the air." f

Young rabbits deprived of their hemispheres will stand, run, start at noises, avoid obstacles in their path, and give responsive cries of suffering when hurt. Eats will do the same, and throw themselves moreover into an attitude of defence. Dogs never survive such an operation if per formed at once. But Goltz's latest dog, mentioned on p. 70, which is said to have been kept alive for fifty-one days after both hemispheres had been removed by a series of ablations and the corpora striata and thalami had softened away, shows how much the mid-brain centres and the cord can do even in the canine species. Taken together, the number of reactions shown to exist in the lower centres by these observations make out a pretty good case for the Meynert scheme, as applied to these lower animals. That scheme demands hemispheres which shall be mere supple ments or organs of repetition, and in the light of these observations they obviously are so to a great extent. But the Meynert scheme also demands that the reactions of the lower centres shall all be native, and we are not absolutely sure that some of those which we have been considering may not have been acquired after the injury ; and it further more demands that they should be machine-like, whereas the expression of some of them makes us doubt whether they may not be guided by an intelligence of low degree.

Even in the lower animals, then, there is reason to soften down that opposition between the hemispheres and the lower centres which the scheme demands. The hemi spheres may, it is true, only supplement the lower centres, but the latter resemble the former in nature and have some small amount at least of ' spontaneity ' and choice. But when we come to monkeys and man the scheme well-nigh breaks down altogether; for we find that the hemispheres do not simply repeat voluntarily actions which the lower centres perform as machines. There are many functions which the lower centres cannot by themselves perform at all. When the motor cortex is injured in a man or a monkey genuine paralysis ensues, which in man is incurable, and almost or quite equally so in the ape. Dr. Seguin knew a man with hemi-blindness, from cortical injury, which had persisted unaltered for twenty-three years. 'Traumatic inhibition' cannot possibly account for this. The blindness must have been an ' Ausfallserscheinung,' due to the loss of vision's essential organ. It would seem, then, that in these higher creatures the lower centres must be less adequate than they are farther down in the zoological scale ; and that even for certain elementary

combinations of movement and impression the co-operation of the hemispheres is necessary from the start. Even in birds and dogs the power of eating properly is lost when the frontal lobes are cut off.* The plain truth is that neither in man nor beast are the hemispheres the virgin organs which our scheme called them. So far from being unorganized at birth, they must have native tendencies to reaction of a determinate sort.f These are the tendencies which we know as emotions and instincts, and which we must study with some detail in later chapters of this book. Both instincts and emotions are reac tions upon special sorts of objects of perception; they de pend on the hemispheres ; and they are in the first instance reflex, that is, they take place the first time the exciting ob ject is met, are accompanied by no forethought or delibera tion, and are irresistible. But they are modifiable to a certain extent by experience, and on later occasions of meeting the exciting object, the instincts especially have less of the blind impulsive character which they had at first. All this will be explained at some length in Chapter XXIV. Meanwhile we can say that the multiplicity of emo tional and instinctive reactions in man, together with his extensive associative power, permit of extensive recouplings of the original sensory and motor partners. The conse quences of one instinctive reaction often prove to be the inciters of an opposite reaction, and being suggested on later occasions by the original object, may then suppress the first reaction altogether, just as in the case of the child and the flame. For this education the hemispheres do not need

* Goltz: Ptiflger's Archiv, vol. 42, p. 447 ; Schrader: ibid. vol. 44, p. 219 ff . It is possible that this symptom may be an effect of traumatic inhibition, however. f A few years ago one of the strongest arguments for the theory that the hemispheres are purely supernumerary was Soltmann's often-quoted observation that in new-born puppies the motor zone of the cortex is not excitable by electricity and only becomes so in the course of a fortnight, presumably after the experiences of the lower centres have educated it to motor duties. Paneth's later observations, however, seem to show that Soltmann may have been misled through overnarcotizing his victims (Pfltiger's Archiv, vol. 37, p. 202). In the Neurologisches Centralblatt for 1889, p. 513, Bechterew returns to the subject on Soltmann's side with out, however, noticing Paneth's work.

to be tabulae rasce at first, as the Meynert scheme would have them ; and so far from their being educated by the lower centres exclusively, they educate themselves.* We have already noticed the absence of reactions from fear and hunger in the ordinary brainless frog. Schrader gives a striking account of the instinctless condition of his brainless pigeons, active as they were in the way of loco motion and voice. " The hemisphereless animal moves in a world of bodies which . . . are all of equal, value for him. . . . He is, to use Goltz's apt expression, impersonal . . . Every object is for him only a space-occupying mass, he turns out of his path for an ordinary pigeon no otherwise than for a stone. He may try to climb over both. All authors agree that they never found any difference, whether it was an in animate body, a cat, a dog, or a bird of prey which came in their pigeon's way. The creature knows neither friends nor enemies, in the thickest company it lives like a hermit. The languishing cooing of the male awakens no more im pression than the rattling of the peas, or the call-whistle which in the days before the injury used to make the birds hasten to be fed. Quite as little as the earlier observers have I seen hemisphereless she-birds answer the courting of the male. A hemisphereless male will coo all day long and show distinct signs of sexual excitement, but his activ ity is without any object, it is entirely indifferent to him whether the she-bird be there or not. If one is placed near him, he leaves her unnoticed. ... As the male pays no at tention to the female, so she pays none to her young. The brood may follow the mother ceaselessly calling for food, but they might as well ask it from a stone. . . . The hemi-

* Milnsterberg (Die Willenshaudlung, 1888, p. 134) challenges Meynert's scheme in toto, saying that whilst we have in our personal experience plenty of examples of acts which were at first voluntary becoming second arily automatic and reflex, we have no conscious record of a single origi nally reflex act growing voluntary. — As far as conscious record is concerned, we could not possibly have it even if the Meynert scheme were wholly true, for the education of the hemispheres which that schesra postulates must in the nature of things antedate recollection. Bit it s^oa to me that Munsterberg's rejection of the scheme may pcsaibl/ be correct as regards reflexes from the lower centres. Everywhere in this department 0* P«v chogenesis we are made to feel how ignorant wt, really an,.

Bphereless pigeon is in the highest degree tame, and fears man as little as cat or bird of prey." * Putting together now all the facts and reflections which we have been through, it seems to me that we can no longer hold strictly to the Meynert scheme. If anywhere, it will apply to the lowest animals ; but in them especially the lower centres seem to have a degree of spontaneity and choice. On the whole, I think that we are driven to sub stitute for it some such general conception as the following, which allows for zoological differences as we know them, and is vague and elastic enough to receive any number of future discoveries of detail.

All the centres, in all animals, whilst they are in one aspect mechanisms, probably are, or at least once were, organs of consciousness in another, although the conscious ness is doubtless much more developed in the hemispheres than it is anywhere else. The consciousness must every where prefer some of the sensations which it gets to others ; and if it can remember these in their absence, however dimly, they must be its ends of desire. If, moreover, it can identify in memory any motor discharges which may have led to such ends, and associate the latter with them, then these motor discharges themselves may in turn become desired as means. This is the development of will ; and its realization must of course be proportional to the possible complication of the consciousness. Even the spinal cord may possibly have some little power of will in this sense, and of effort towards modified behavior in consequence of new experiences of sensibility, f

f Naturally, as Schiff long ago pointed out (Lehrb. d. Muskel-u. Ner« venphysiologie, 1859, p. 213 ff.),the 'Riickenmarksseele,' if it now exist, can have no higher sense-consciousness, for its incoming currents are solely from the skin. But it may, in its dim way, both feel, prefer, and desire. See, for the view favorable to the text: G. H. Lewes, The Physiol ogy of Common Life (1860), chap. ix. Goltz (Nervencentren des Frosches 1869, pp. 102-130) thinks that the frog's cord has no adaptative power. This may be the case in such experiments as his, because the beheaded frog'a

All nervous centres have then in the first instance one essential function, that of 'intelligent' action. They feel, prefer one thing to another, and have 'ends.' Like all other organs, however, they evolve from ancestor to descend ant, and their evolution takes two directions, the lower centres passing downwards into more unhesitating autom atism, and the higher ones upwards into larger intellectu ality.* Thus it may happen that those functions which can safely grow uniform and fatal become least accompanied by mind, and that their organ, the spinal cord, becomes a more and more soulless machine; whilst on the contrary those functions which it benefits the animal to have adapted to delicate environing variations pass more and more to the hemispheres, whose anatomical structure and attendant consciousness grow more and more elaborate as zoological evolution proceeds. In this way it might come about that in man and the monkeys the basal ganglia should do fewer things by themselves than they can do in dogs, fewer in dogs than in rabbits, fewer in rabbits than in hawks, f fewer in hawks than in pigeons, fewer in pigeons than in frogs, fewer in frogs than in fishes, and that the hemispheres should correspondingly do more. This passage of functions for ward to the ever-enlarging hemispheres would be itself one of the evolutive changes, to be explained like the develop ment of the hemispheres themselves, either by fortunate variation or by inherited effects of use. The reflexes, on this view, upon which the education of our human hemi spheres depends, would not be due to the basal ganglia

short span of life does not give it time to learn the new tricks asked for. But Rosenthal (Biologisches Centralblatt, vol. iv. p. 247) and Mendelssohn (Berlin Akad. Sitzuugsberichte, 1885, p. 107) in their investigations on the simple reflexes of the frog's cord, show that there is some adaptation to new conditions, inasmuch as when usual paths of conduction are interrupted by a cut, new paths are taken. According to Rosenthal, these grow more pervious (i.e. require a smaller stimulus) in proportion as they are more often traversed.

* Whether this evolution takes place through the inheritance of habits acquired, or through the preservation of lucky variations, is an alternative which we need not discuss here. We shall consider it in the last chapter in the book. For our present purpose the modus operandi of the evolution makes no difference, provided it be admitted to occur. alone. They would be tendencies in the hemispheres them* selves, modifiable by education, unlike the reflexes of the medulla oblongata, pons, optic lobes and spinal cord. Such cerebral reflexes, if they exist, form a basis quite as good as that which the Meynert scheme offers, for the acquisition of memories and associations which may later result in all sorts of ' changes of partners ' in the psychic world. The diagram of the baby and the candle (see page 25) can be re-edited, if need be, as an entirely cortical transaction. The original tendency to touch will be a cortical instinct ; the burn will leave an image in another part of the cortex, which, being recalled by association, will inhibit the touch ing tendency the next time the candle is perceived, and excite the tendency to withdraw — so that the retinal picture will, upon that next time, be coupled with the original motor partner of the pain. We thus get whatever psycho logical truth the Meynert scheme possesses without en tangling ourselves on a dubious anatomy and physiology.