just as the superior officer has to bring into due relation the evolutions which are carried out under the control of his subordinates, so does consciousness correlate the data received through many groups of different nerves and co-ordinate a number of varied activities into a more or less definite course of behavior. It is true that the analogy here again, to some extent, fails us, since the drill-sergeant and his superior officer are separate individuals, while consciousness is continuous and is drill-sergeant and superior officer rolled into one. But, though this continuity of consciousness remains unbroken, we have abundant evidence, in the course of our own experience, of the fact that, during the gradual establishment of the supreme conscious control of the bodily activities, the regulation of details of active response is, step by step, relegated to subconscious guidance, which, though constantly in touch with, requires but little attention from, the supreme centres of voluntary control. The horseman, the cyclist, the pianist, knows well that, when once skill has been attained, such further guidance as is required under the special conditions of any particular performance of the act of skill may be safely left to subconsciousness, scarcely troubling the attention at all. Habit has, in large degree, rendered these actions part of the acquired automatism. But consciousness, like a wise superior officer, still keeps vigilant watch. So long as the performance is satisfactory and accurate the superior officer sees as if he saw not; but when anything goes wrong, consciousness, as superior officer, steps in more or less smartly and decisively.

Few are likely to question the importance in animal life of the acquisition of habits, including, as we must, under this term, nearly all the varied forms of animal skill. For even when the skill is founded upon a congenital and instinctive basis, it is (except, perhaps, in some instinctive activities of insects and other invertebrates) improved and guided to finer and more delicate issues in the course of individual experience. So that we may regard the function of consciousness as twofold; first, it is concerned in the establishment of habits; and, secondly, it is concerned in the utilisation of all the active powers, including the habits so established, in meeting the varied requirements of daily life.

How, then, we may proceed to ask, is the guidance of consciousness effected? Upon what principles are the acquisition of skill and the utilisation of skill to be explained?

There can be no question that, from the psychological point of view, the association of impressions and ideas is of fundamental importance. Whatever may be the position assigned to so-called "association by contiguity" in human psychology, there can be no question as to its essential importance in the more primitive psychology of such animals as young birds and young mammals. When chicks learn rapidly to distinguish between the caterpillars of the cinnabar moth and those of the cabbage moth, so that they gobble up the one without hesitation and avoid the other without fail, they give us the plainest intimation which can be conveyed by objective signs that an association has been formed in either case between appearance and taste. Professor Preyer notes that his chicks rapidly learnt to associate the sound of tapping with the presence of food. I have elsewhere described how one of my chicks which had but recently learnt to drink standing in its tin, subsequently stopped as it ran through the water in such a way as to lead one to infer that the wet feet had become associated with the satisfaction of thirst. Young pheasants seemed to associate water with the sight of a toothpick on which I gave them drops. Ducklings so thoroughly associated water with the sight of their tin that they tried to drink from it and wash in it, though it was empty, nor did they desist for some minutes. A young moor-hen, for whose benefit we had dug up worms with a spade, and which, standing by, jumped on the justturned sod and seized every wriggling speck which caught his keen eye, would soon run from some distance to me so soon as I took hold of the spade. There is no need to multiply instances of this kind. The study of these young birds is an impressive lesson in association psychology, and one daily grows more convinced of the importance of association in the acquisition of experience of this homely elementary but essentially practical kind.

But it may be said that though association is unquestionably important, yet its efficiency in the guidance of action depends upon something deeper still. Granted that, in a chick which has

first seen and then tasted a nasty morsal, an association is formed between sight and taste, so that on a subsequent occasion its peculiar appearance suggests its peculiar nastiness. What is the connexion between the nastiness of a cinnabar caterpillar and the checking of the tendency to eat it, or between the niceness of a cabbage moth caterpillar and the added energy with which it is seized? Why do taste-stimuli of one kind have the one effect and taste-stimuli of a different kind have just the opposite effect? What are the physiological concomitants of the augmentation of response in the one case and of the inhibition of response in the other case? I conceive that there is but one honest answer to these questions. We do not know. This and much beside must be left for the physiology of the future to explain. This much may be said: Certain stimuli call forth cortical disturbances, the result of which is the inhibition of activities leading to the repetition of these stimuli; certain others call forth cortical disturbances the result of which is the augmentation of the activities which lead to their repetition. The accompaniments in consciousness of the latter we call pleasurable; the accompaniments in consciousness of the former we call unpleasant, distasteful, or painful. That appears to be a plain statement of the facts as we at present understand them.

Now there can be no question as to the strongly-marked hereditary element in such augmentation of response when the cortical disturbances have pleasurable concomitants and the inhibition of response when the cortical disturbances have unpleasant concomitants. This is, in fact, grounded on the innate powers or faculties which the organism derives from its parents or more distant ancestors. But if the cortical augmentation and inhibition form the basis upon which all acquisition and all control are based, what becomes of the distinction between instinctive and acquired activities? What of that between automatic and controlled behavior? Do we not come back, after all, to the universal automatism advocated by Professor Huxley?

Let us look again at the facts. A chick sees for the first time in its life a cinnabar caterpillar, instinctively pecks at it under the influence of the visual stimulus; seizes it, and instinctively shrinks

under the influence of the taste stimulus. So far we have instinct and automatism. Presently we throw to it another similar caterpillar. Instinct and automatism alone would lead to a repetition of the ⚫ previous series of events-seeing, seizing, tasting, shrinking. The oftener the experiment was performed the more smoothly would the organic mechanism work, the more definitely would the same sequence be repeated-seeing, seizing, tasting, shrinking. Is this what we actually observe? Not at all. On the second occasion the chick acts differently as the result of the previous experience. Though he sees, he does not seize, but shrinks without seizing. We believe that there is a revival in memory of the nasty taste. And in this we seem justified, since we may observe that sometimes the chick, on such occasions, wipes its bill on the ground as he does when he experiences an unpleasant taste, though he has not touched the larva. The chick, then, does not continue to act merely from instinct and like an automaton. His behavior is modified in the light of previous experience. What, then, has taken place in and through which this modification, born of experience, is introduced? In answering this question we seem to put our finger upon that in virtue of which the distinction now regarded as of so much biological significance that between congenital and acquired activities— has a valid existence. The answer may be given in two words— Association and the Suggestion that arises therefrom. The chick's first experience of the cinnabar caterpillar leads to an association between the appearance of the larva and its taste; or, from the physiological point of view, a direct connexion between the several cortical disturbances. On the second occasion the taste is suggested by the sight of the cinnabar larva; or, physiologically, the disturbance associated with taste is directly called forth by the disturbance associated with sight. It is through association and suggestion that an organism is able to profit by experience and that its behavior ceases to be merely instinctive and automatic. And such association would seem to be a purely individual matter-founded, no doubt, on an innate basis, linking activities of the congenital type, but none the less wholly dependent upon the immediate touch of individual experience.

In watching, then, the behavior of young birds or other animals, we observe a development which we interpret as the result of conscious choice and selection. For the chick, to which a handful of mixed caterpillars is thrown, chooses out the nice ones and leaves the nasty ones untouched. The selection is dependent upon an innate power of association which needs the quickening touch of individual experience to give it activity and definition, without which it lies dormant as a mere potentiality. On this conscious selection and choice depends throughout its entire range this development of those habits which are acquired as opposed to those which are congenital; and on it depends the whole of mental as contrasted with merely biological evolution. On it, too, depends the distinction between animal automatism, in the restricted sense here advocated, and those higher powers which, though founded thereon, constitute a new field of evolutionary progress.

C. LLOYD MORGAN.