series of periodically recurring movements, which lasts until it is interrupted by a new volitional impulse. Without this arrangement all our ordinary actions, as walking, reading, playing, speaking, &c., would absorb an amount of the volitional impulses of the brain which must very soon result in fatigue. It, however, proves also the independence of the lower nerve-centres, and most decidedly refutes the above assumption of a direct anastomosis of the nerves. It may also now be comprehensible how it comes to pass that so many actions and occupations, whose slightest details must be attended to in their conscious acquisition, later on, with prolonged practice and habit, are performed quite unconsciously, as knitting, playing on the piano, reading, writing, &c. All the work, then, which during acquisition was done by the brain, has been handed over to subordinate nerve-centres; for these can call into play an habitual combination of certain activities just as efficiently as the brain in thinking or in learning by heart. That, however, then the activities become for the most part unconscious to the brain, gives them in respect to the brain a certain resemblance to instinctive actions, whilst indeed, in respect to the nerve-centre which presides over the activity, practice and custom is the precise opposite of instinct.

That all the phenomena hitherto considered have essentially the same underlying principle, it is not very difficult to see. We started with the reflectorial movements produced by irritation of peripheral parts of the body, and found a purpose most decidedly expressed therein, both in the result of the whole movement and in the simultaneous and successive combinations of the most different muscles; nay, in part, most decidedly expressed even in an alternating play of the antagonists. We then passed on to the reflex movements produced by means of sense-perceptions, and found here the same fact, only often with a dash of higher intelligence, in that the higher central points of the spinal cord came more into play.

Lastly, we noticed that reflex actions, in which the exciting stimulus is an innervating current from the brain to the other central organs concerned, are produced by the conscious will, and did not remark here any quantitative increase of effects as compared with the reflex movements produced through sense-perceptions; naturally enough, for the intelligence revealed in reflection depends far more on the stage of development of the reflecting central organ than on the nature of the stimulus.

That, in fact, the brain also can become a central organ of reflex actions, we cannot doubt from the analogy of its structure with the other centres. In reflex actions of the ganglionic system and in individuals deprived of brains, perception by the brain is excluded; but this may very well accompany the reflex actions of the spinal cord in the case of sound organisms. In this case, however, only the stimulation, but not the will to move, is felt in the brain; but the latter must manifestly also have place if the brain itself is to be a central organ of reflection. Such cases are, however, already familiar to us; e.g., the catching at a falling glass or the parrying of a previously seen blow may have these characteristics. Accordingly we shall not be able to avoid regarding them as reflex actions, if only the link between perception of the action and the will to execute it lies outside the cerebral consciousness, which receives additional confirmation from the fact that conscious reflection would manifestly come too late. To the same category belongs a part of the not quite unconscious prelection and preluding, or the rapid answers to sudden questions, or the sudden taking off the hat at the unexpected greeting of an unknown person. Cerebral reflection frequently surpasses the reflection of the spinal cord, and prevents its occurrence; e.g., a decapitated frog scratches the nipped place on the skin, a living one hops away. Here is seen the direct transition from cerebral reflection to conscious psychical activity, between which no line can be drawn. There follows from this the unity of

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the principle underlying all these phenomena. There are, therefore, only two logical ways of looking at these things either the mind is everywhere only the last result of material processes, both in the brain and in the rest of the nervous life (then, however, purpose would also have to be everywhere denied when not posited by conscious nervous activity), or the soul is everywhere the principle lying at the basis of material nervous processes, causing and regulating them, and consciousness is only a phenomenal form of the same, brought about by means of these processes. We shall see in the sequel which of these two assumptions better suits the facts.

The next point we have to investigate is the question, whether the phenomena we are considering may be looked upon as effects of a dead mechanism, or whether we are not compelled to conceive them as consequences of an intelligence immanent in the central organs, in which case the foregoing alternative may provisionally remain undiscussed. Let us first turn to physiology. The skin of a frog's thigh being pricked by a needle, we see both legs drawn up, provided the little piece of spinal cord from which issue the crural nerves remains intact. The prick of the needle manifestly affects only one primitive nerve-fibre, since within a circle of a certain size the position of the pricked place cannot be distinguished; the number of motor fibres put in action by the same is, however, enormously large, for it can embrace the whole body. The direct anastomosis of the sensory and motor nerves is hereby rendered improbable in the highest degree. It becomes, however, still more so by the circumstance that the same motor fibres react, when this or that place in the skin of the frog's thigh is pricked, when accordingly different sensory nerve-fibres convey the stimulus to the centre. Besides, microscopic investigations not only give no support to this supposition, but what is more, Kölliker has directly observed the emergence of motor fibres from globules of grey nerve-matter (central organ), and it is now generally supposed that the

central origin of all the nerve-fibres must be sought in the ganglion-cells, i.e., the peculiar spherical or radiated cells of the grey nerve-matter. The stimulus conducted. by the sensory fibres must accordingly, in any case, be first received by the central organ, and through this be conducted to the motor nerves; in no other way could any sensory fibre possibly be in a position to act upon. any motor fibre of the same centre (as is actually the case). But if all the stimuli are first received by the central organ, and are only propagated from this to the motor nerves, then the materialistic explanation of reflex actions by a peculiar mechanism of the channels of conduction becomes quite impossible; for no laws and contrivances can at all be imagined which should allow one and the same current to pass over now to near, now to remote parts, should cause the reactions to follow now in this, now in that order, nay, should even permit an alternating play of the antagonists to occur on a simple stimulus (as in the rubbing of the filliped part). The impossibility of a pre-established mechanism is, however, physiologically demonstrable in a much more striking way. If one divides the spinal cord throughout its whole length by a longitudinal section, the capacity for reflex movements is not affected; it is only limited to the half of the body irritated on each occasion. If, on the other hand, a connecting bridge be left between the two separated halves at any place whatsoever, or if, at some distance from each other, now the left and then the right half of the spinal cord be cut across, so that all the longitudinal fibres are severed, general reflex movements may be excited by stimulation of each main point. This is probably the clearest proof that the motor reaction is not a consequence of the predetermined paths of the conduction. of the stimulus, but that the current after destruction of the usual channels makes for itself new paths, in order to bring about the suitable reflex movements, provided only that the parts be not completely isolated. There must then be a principle superior to the material laws of con

duction of the nerve-currents, which brings about this change of circumstances, in virtue of which the courses of these currents are changed, and this principle can only be an immaterial one. This is also verified by the circumstance, that the union of reflex movements is for the most part capable of being dissolved by conscious volition. and exercise.

Forcible as are these anatomical-physiological reasons, they are still not the strongest of all. If the conformity to the end in view which appears in reflex actions were one externally predetermined, brought on the scene by a material mechanism, then the capability of accommodating movements to the nature of the circumstances, this inexhaustible wealth of combinations, each of which is suitable to its special case, would be plainly inexplicable. We should rather expect a constant recurrence of a few similar complex movements, whereas a single glance at the infinite number of combinations, as exemplified in the simple case of preserving one's balance, is sufficient to establish the conviction of an immanent fitness-an individual providence, as we have already come to know it when considering Instinct. We are absolutely obliged, then, so to represent to ourselves the event that the stimulus is perceived as idea, and through the idea of the danger or feeling of pain connected therewith the idea of relief through the corresponding counter-movement is produced, which now becomes the object of volition. That the nerve-centres of the spinal cord and ganglia possess the capacity of willing we have already settled; that the cases being strictly parallel, they must also possess sensibility is evident at once; but since no sensation can be imagined without a certain degree of consciousness, however small, they also possess a certain consciousness. The beginning and the end of the process, the perception of the stimulus and the will to move, are then the functions which we have no hesitation in ascribing to every nervous centre. The only question is, whether the link between them, the