Phrenology takes a run in order to get beyond the standpoint of the spectral soul, but it ends by peopling the whole skull with spectres. It falls back to the naïf standpoint, which will not be content without putting a machinist to sit in the ingenious machine of our body to guide the whole, a virtuoso to play the instrument. A man who has marvelled all his life at a steam-engine and never understood it, might perhaps think also that there must be in the cylinder again a little steam-engine, which produces the to-and-fro action of the piston. Was it, however, worth while to deal at such length with wholly unscientific phrenology to gain nothing but a new example of the long-known "irresistible tendency to personification," which has created this flock of active intellectual faculties? Though it may be that some representatives of Materialism have come nearer this view than they should have done, it has, nevertheless, had but little influence on the development of modern nerve-physiology. Well, but the great reason why there has hitherto been no progress in our explanations of the relation of the brain to the psychical functions seems to us to lie simply in the same ground which doomed phrenology to failure-in the personification of abstract ideas instead of the simple apprehension of the actual, so far as it is possible. What is the way that leads us to the brain? The nerves. In them we have before us a part of that complicated mass as it were unfolded before us. We can experiment on the nerves, since we have before us what is assuredly a single thing. In them we find conduction, electric currents, effects on the contraction of the muscles, on the secretion of the glands; we find reactions on the central organs. We find the peculiar phenomenon of reflex movements, which have already with a very promising tendency towards better things been repeatedly regarded as the primary element of all psychical activity.25 How 25 Comp. Piderit, Gehirn u. Geist; Entwurf einer physiol. Psychologie, 1863. Here, of course, the idea of a resolution of mental activity into re seriously personification stands in the way, or rather how hardly from habitual conceptions emerges the true idea, viz., to derive the personal from the impersonal, is shown in a most notable example by the history of Pflüger's experiments on the psychical importance of the spinal centres. Pflüger showed with great ingenuity and experimental skill that decapitated frogs and other creatures, even amputated tails of lizards, for a considerable time make movements to which we cannot refuse the character of adaptation. The most interesting case is this:-A frog, decapitated, is smeared on the back with acid; it wipes the drop away with the most convenient foot. Now this thigh is cut off; it tries with the stump, and as several efforts are unsuccessful, it at last takes the opposite foot, and completes the movement with this. This was no mere reflex action;-the frog seems to consider. It forms the conclusion that it can no longer attain its object with the one foot, and so it makes the attempt with the other. It seems demonstrated: there are spinal souls, actually tail-souls. Only a soul can think! Whether it is a materialistic soul, too-that is not the matter in dispute; but the entire frog is represented in its spinal marrow. There it thinks and decides after the manner of frogs. A scientific opponent now takes an unhappy frog, beheads it, and boils it slowly. To make the experiment quite perfect, it is proper that a frog which still enjoys its head should be boiled with it, and that another decapitated specimen should be placed alongside the pot for exact comparison. Now the result is that the beheaded frog quietly lets itself be cooked without struggling against its fate like its more perfect companion in misfortune. Conclusion: There are no spinal souls; for 66 psychology,' shows at S. 328 f. quite clearly the complete analogy between the "compound brain-reflexes" and the spinal reflexes. Comp., too, Horwicz, Psychol. Analysen, 1872, flex activity is still combined with if there were, it would have noticed the danger from the rising heat, and must have thought of flight.26 Both conclusions are equally forcible. Pflüger's experiment, however, is more valuable, more fundamental. Let us drop personification; let us cease to seek everywhere in the parts of the frog thinking, feeling, acting frogs, and try instead to explain the phenomenon out of simpler phenomena, i.e., from reflex movements, not from the whole, the unexplained soul. Then we shall easily discover, too, that in these already so complicated sequences of sensation and movement there is afforded the beginning of an explanation of the most complicated psychological activities. This would be a path to follow up. And what is there to prevent it? Lack of invention or ingenuity for the most difficult experiments? Assuredly not. It is the lack of perception that the explanation of psychical life requires us to carry it back to individual processes which form a necessary part of the activity, but which are utterly and entirely distinct from the mode of action of a complete organism. But the reflex movement happens unconsciously; and therefore the most composite activity of this kind cannot explain consciousness! Another objection of the crudest prejudice. Moleschott, as a proof that the consciousness is only in the brain, alleges the well-known observation of Jobert de Lamballes, according to which a girl injured at the top of the spine remained conscious for half an hour, although the whole body, with the exception of the head, was completely paralysed. "Thus the whole spine may become inactive without the consciousness being affected." Good! But when it is concluded from this case that decapitated crea 26 Comp. Pflüger, Die sensorischen Jahrb. ii. (1860). For a detailed Functionen des Rückenmarks der account, especially of the latter expeWirbelthiere, Berl. 1853; and, on riment, see Wundt, Vorles. über d. the counter-experiment, Goltz, Die Menschen-u.-Thierseele, Leipz. 1863, Functionen der Nervencentren des ii. 427 ff. Comp. besides, Wundt, Frosches, in the Königsberg. Med. Physiol. Psych., 824-827. tures have no sensation and no consciousness, Moleschott overlooks that the head separated from the spine might show its consciousness in a way we can understand, but not the trunk. What sensation and what consciousness there may or may not be in the spinal centres when separated from the head, we cannot possibly know. This only we may certainly assume, that this consciousness can do nothing that is not based in the mechanical conditions of the centripetal and centrifugal nerve-conduction and the constitution of the centre. We may not therefore conclude, either, that the spinal centres feel, and therefore can do more than a mere mechanism. On the contrary, that the thing takes place quite mechanically is not only certain a priori, but, by way of supererogation, is established also by the counterexperiment of gradual heating. For the one class of stimuli there exists in the spine of the frog mechanism producing adapted reflex actions, but for the other class not. Whether in the latter case sensation too is wanting, or only the capacity to react upon the sensation by manifold movements, we do not know. It is, however, not improbable, although we have nothing here to support us but analogy, that everywhere where sensation arises there is also an apparatus to react upon the sensation; conversely we may assume that every reflex apparatus carries with it at least the possibility of a sensation, however weak, while it remains, of course, very doubtful whether, in a whole and sound creature, any part of this sensation of the subordinate centres comes clearly into consciousness.27 27 We are not, therefore, by any means inclined to regard the reflex act itself as that which objectively corresponds to the (subjective) sensation: this would rather be the opposition which the reflex act has to overcome in the central organ, so that sensation must be the less as sumed the more uninhibited is the reflex act. Where the reflex act is inhibited from a superior centre, we shall have to suppose that the place where the sensation arises is also transferred to the superior centre; and in the case of a full-grown animal with a developed brain, perhaps definite and distinct sensation occurs only in the brain, while the sensory phenomena of the subordinate centres only contribute to the tuning of the We see that we are here on the way to make Materialism for the first time consistent, and this, in fact, will be the common feeling. This involves the uncommonly difficult question of consciousness, for obviously we cannot indicate any definite degree of a physical condition of excitation in any part of the central organs which would in itself and necessarily be connected with consciousness. Rather the passing of a condition of excitation into consciousness seems always to depend on a relation between the strength of all simultaneously present excitations in the seats of sensation. Precisely the same physical phenomenon might therefore occur with equal reflexive effect, at one time consciously, at another unconsciously. This is to be borne in mind for the doctrine of 'latent' or 'unconscious' ideas, as to which so much uncertainty has prevailed down to quite recent times. Here we have to do, of course, not with an "unconscious consciousness," but quite simply with an unconscious play of the same mechanism, which in another state of the collective condition is connected with the subjective effect of a particular idea. That there are latent ideas in this sense is the A B C of every empirical psychology, and it cannot escape on a careful examination that not only purposeful but conscious actions, but also phenomena of association of the most various kind result from this play of the same mechanism, which in another collective condition of the brain is connected with ideation. Because of this unmistakable influence of the collective condition in the organically connected whole, we are also at one with Wundt that in the question of consciousness it is by no means indifferent whether a spinal centre is in connexion with the brain or is separated from it. (Comp. Physiol. Psychol., S. 714 f.) And we should be inclined also to VOL. III. argue that we must suppose a clearer consciousness in the spinal marrow of an animal which, in consequence of its organisation, possesses no cerebrum at all, than in the separated spine of an animal of higher organisation. Moreover, there is no doubt that the assumption of a consciousness in the separated centres of the second and third rank contributes nothing to the explanation of movements (Wundt, loc. cit. 829). On the other hand, we cannot agree with Wundt that the absence of any recollection and of anything resulting in spontaneous movement (S. 825 f.) in the decapitated frog is an argument against the real existence of consciousness. To all consciousness there appears, indeed, to belong, as Wundt too supposes, a synthesis; but this need not necessarily reach over a long period, and embrace different sensations in a unity. Even in the mere connexion of the newly arising state with the previous one, there lies a synthesis which makes consciousness logically intelligible. Sensation must refer to a change; that is sufficient. For the rest, let us repeat here that the question can never be to explain movements out of merely hypothetical partial consciousness, but the converse: from the peculiar combination of a more simple and intelligible mechanism with partial consciousness to explain how, in a much more complicated fashion, the whole can follow a strictly physiological mechanism and yet be at the same time the substratum of a manifold content of ideas. We must explain the engine out of its separate wheels, and attribute to the separate wheel, in addition to its other properties, a mysterious potency which belongs to it as part of the engine. I |