Animal Behaviour

I.—Impulse, Interest, and Emotion

Any discussion of animal behaviour must deal largely with what is termed the conative aspect of consciousness. “The states designated by such words as craving, longing, yearning, endeavour, effort, desire, wish, and will,” says Dr. Stout, in his admirable “Manual of Psychology,”[117] “have one characteristic in common. In all of these there is an inherent tendency to pass beyond themselves and become something different. This tendency is not only a fact, but an experience; and the peculiar mode of being conscious, which constitutes the experience, is called conation.” Closely associated with this conation is impulse, which Dr. Stout defines as “any conative tendency, so far as it operates by its own isolated intensity, apart from its relation to a general system of motives. Action on impulse is thus contrasted with action which results from reflection and deliberation.”[118] In the interpretation we have advocated, animals are essentially creatures of impulse, and not to any large extent, if at all, reflective agents. And their impulses may be associated either with their inherited and congenital behaviour, or with that which is due to acquired experience. In other words, their impulses may be divided broadly into two classes, the one instinctive, the other acquired.

Dr. Stout says that conation is not only a fact, but an experience. Now, first as to the fact. It seems to be the correlative in consciousness of the behaviour of the nervous system under stimulation. Let us take some simple case such as that, for example, of a hungry chick pecking at a grain of corn. This is explained from the physiological point of view by saying that internal and external stimulation—internal from the digestive organs and system in need of food, external through the eye—gives rise to a state of unstable equilibrium in the nerve-centres; and that, when the instability reaches a certain value, the nervous system discharges into the motor organs, the chick pecks, and stable equilibrium is restored. The tendency to discharge in some way under stimulation is an essential characteristic of a nervous system. It is one of the facts of physiological science. So, too, the conative tendency is one of the facts of psychological science; it is a change in the situation introduced by the effects of the physiological discharge.

Let us here parenthetically notice that the physiological tendency in the nervous system is an evolved complication and a specialized development of one of the fundamental properties of protoplasm—that which is often spoken of as irritability. One of the characteristics of all living matter is its “explosive” instability. So that at the very threshold of organic behaviour we have the analogue of that which, in its developed form, becomes the tendency of the nervous system to discharge as the result of stimulation. The conative tendency of the psychologist, therefore, has its roots deep down in the elemental germs of all organic life.

And this conative tendency is, says Dr. Stout, not only a fact but an experience. Let us return to our hungry chick that pecks at a grain of corn. And let us grant that as the result of stimulation there arise states of consciousness which we describe as a feeling of hunger and the sight of the grain of corn. The nervous system now discharges; and there are introduced into the situation a further group of data, the motor consciousness of the actual behaviour, sensory data from the results of the act, the seizing of the grain and so forth. The situation has unquestionably changed. But is there any specific consciousness of the conative tendency as such? Is there any “peculiar mode of being conscious which constitutes the experience which is called conation”? It is difficult to say. Hence we find differences of opinion among psychologists as to what, from the psychological point of view, the impulse actually is. Is it simply the conscious situation prior to the response? Is it a feeling of the change from the initial to the succeeding phase? Or are new data introduced apart from those afforded by stimulation on the one hand and response on the other? We will not attempt to decide. Without determining its exact nature we may rest content with the very general statement that impulse is a concomitant of a change in the conscious situation.

There is, however, a use of the term concerning which it seems necessarily to enter a word of protest. Impulse is by some regarded as the underlying cause of the conative tendency. Now science, as such, has nothing whatever to do with underlying causes. If, as a matter of observation and inference, we have reason to believe that there is such a tendency, science simply accepts the fact, and endeavours to formulate the conditions under which it arises, and to trace its observed or inferred antecedents. No doubt many of us find it difficult or impossible to rest content with the strictly scientific position, that of unquestioning acceptance of the facts of nature as we find them given in experience. We say: Here is an observed tendency the conditions and antecedents of which are described by science. But what causes the tendency; what is the impelling force? Now to such questions science can give no answer. Science deals with phenomena, and tries to tell us all about their conditions and their antecedents. But whenever Science is asked: “What is the underlying cause of the phenomena,—that which calls them into being?” Science should always give one answer and one only: “Frankly, I do not know; that lies outside my province; ask my sister Metaphysics.” Science ought to have nothing whatever to do with force as the underlying cause of anything in this universe of phenomena. And impulse, as the impelling force which calls a conative tendency into being, is a metaphysical, not a scientific conception.

We need not further discuss the psychological nature of impulse. Indeed, the little that has been said would not have been necessary to our inquiry were it not that we frequently have occasion to speak of animals as “creatures of impulse,” and to refer to their behaviour as due to impulse. What do we mean by such expressions? If we regard conative tendency as a fact (whatever may be said for or against its being also a specific experience), and if this fact is the tendency of the conscious situation to develope in certain definite ways, then we may define impulse with sufficient clearness by saying, with Dr. Stout, that it is characterized by being unreflective. Conative tendency thus comprises two categories—impulse and volition; the one unreflective, the other involving deliberation.

Before passing on to consider how impulse is partly determined by the feeling-tone and the emotional attributes of the conscious situation, we may first draw attention to the important way in which the results of conative tendency afford the data through which consciousness attains its unity in the midst of diversity of experience.

We said that the impulses might be divided broadly into two classes—the one instinctive, the other acquired. Now, from the point of view suggested by a study of behaviour, if not also, as I am disposed to think, from the more general standpoint of a genetic study of mental development, it is convenient to start with the instinctive act and the conscious situation it implies. We have here a piece of experience which, if we may so phrase it, hangs together; in which experience of things in the environment is included in the same elemental synthesis with that of bodily acts in organic relation to these things. It is closely linked, on the one hand, with a foregoing act of attention, itself of the instinctive type; closely linked, on the other hand, with the results of behaviour through which the environing things call forth a new conscious situation and evoke a further response. Thus not only does the experience of an instinctive act hang together, but a series of such acts do so likewise. And coalescent association not only links and groups the elements within the situation called forth by the single act, but comprises also the elements of the developing situation afforded by the whole series. We see this in the young chick, where, as the result of experience, attention is emphasized where the material is palatable, and lapses where it is nauseous—such nauseous substances being soon ignored. Furthermore many environing things appeal in different ways to the same limited number of sense organs, while the same motor organs respond in different ways in successive modes of instinctive behaviour. The same brain forms the physical basis of varied situations overlapping in many ways, and receives afferent messages from the same body. Hence, in its organic unity it affords the conditions for an underlying stratum of mental unity, amid all the diversities of experience; while the multiplicity of messages on the one hand from external things, and on the other hand from internal happenings, lays the foundations of a differentiation between the external world and the self—a differentiation long to remain implicit, and only to be rendered explicit on a far higher level of mental development. For at this early stage, and perhaps throughout animal life, “there is no single continuous self contrasted with a single continuous world. Self, as a whole, uniting present, past, and future phases, and the world as a single coherent system of things and processes, are ideal constructions, built up gradually in the course of human development. The ideal construction of self and the world is comparatively rudimentary in the lower races of mankind, and it never can be complete. On the purely perceptual plane [with which we are now dealing] it has not even begun.”[119] But though the ideal constructions of self and the world have not, as Dr. Stout says, at this stage, even begun, yet, as the same author observes,[120] “animals distinguish in the environment, and treat as a separate thing, whatever portion of matter appeals to their peculiar instincts, and affords occasion for their characteristic modes of activity.” And this differentiation of specially interesting things from each other, and from their relatively uninteresting surroundings, must be accompanied by some differentiation of these things from themselves as affected by them and reacting to them. So that here, as we have seen to be the case in other matters, what is commonly called the perceptual life of animals affords the rough-hewn materials from which ideal constructions may be elaborated by rational beings.

We cannot here attempt to do more than barely indicate the manner in which the perceptual process in animals may acquire unity and diversity—unity through the functioning of the same brain and body, diversity from the different modes of functioning and the differential effects of diverse modes of stimulation. The interesting point for us in our special inquiry is that it is through behaviour that all this is brought about.

As we interpret the facts, the restless activity of the young is primarily a biological fact, and is to be dealt with as an organic problem—a complication of the fundamental irritability of protoplasm. But it is also an essential condition to the acquisition of conscious experience; and the more there is of it in varied modes the wider is the range of the data afforded to consciousness. Congenital behaviour is thus the goal of organic heredity, and the starting-point of conscious accommodation and adjustment; it is the biological end of variation, and affords the means to intelligent modification.

So much for some of the results of conative tendency. Not only does it secure adaptation or adjustment to the environment, but it affords the conditions of mental development by which further accommodation is rendered possible. But, in addition to the attainment of biological ends, in addition to the furtherance of survival in the struggle for existence, mental development has another aspect. All sensory data, whether from the special senses, from the motor processes concerned in responsive behaviour, or from other sources, may, and perhaps always do, carry with them some amount of what is termed feeling-tone, giving rise to a net result in consciousness which we call pleasure or the reverse. Pleasure or satisfaction—however we name that which, though vague and indeterminate in outline, is a very real attribute of the conscious situation—affords its sanction to certain modes of conation, and may thus be regarded as the psychological end of their continuance or their repetition. It is partly, no doubt, a direct adjunct of sight, hearing, taste, and so forth, and of smooth and easy movements of the body and limbs; but it is partly due to a great body of stimulation coming from many parts of the organic system. The blood-vessels are dilated or contracted, the heart’s action increased or diminished; respiration is deepened or the reverse, and its rhythm may be altered; glands are thrown into a state of activity; the tone of the muscles is affected, and there may be either incipient contraction or relaxation. These are primarily organic effects; but they influence the conscious situation, and are themselves suffused with feeling-tone. For, from all the parts so affected, messages are carried in to the brain, and such afferent messages afford data to consciousness. It may be that the experience of the conative tendency, for which Dr. Stout and others claim a distinctive place in consciousness, is largely due to afferent messages from the motor organs incipiently innervated in preparation for the behaviour which follows. In any case these probably form very important elements in the conscious situation antecedent to the actual response. In what we may term motor attention—the state well exemplified by a cat in the strained pause which precedes the spring on to the prey, or in ourselves when we poise before a dive or hold the billiard cue in preparation for a delicate stroke—this incipient innervation, felt through afferent messages from the parts thus braced for action, enters with much distinctness into the conscious situation. In sensory attention, on the other hand, reflex acts have actually taken place, having for their end and purpose the focussing of the sense organs on the object which stimulates them, so that in this way further and more effective stimulation may be received. But, as the sense organ is steadily held to the focus, and made effectually to cover the stimulating thing, the motor apparatus concerned is kept on the strain, and is all the while contributing data to the conscious situation.

In primary genesis attention, both motor and sensory, is unquestionably organic and reflex in its nature. It is a product, and an invaluable product, of biological evolution. Without this as a basis, the higher forms of attention under conscious guidance would be impossible. For all these higher forms are modifications and complications of what is given in organic heritage. Here, as elsewhere throughout the whole range of behaviour, consciousness only guides to finer issues what is presented to it in rough outline, or in isolated fragments, as the outcome of biological evolution. But the organic responses afford the data which consciousness uses that it may mould and fashion the behaviour so as to reach higher and more complex modes of adjustment.

Lest a familiar form of words should give rise to misapprehension, it may here be stated that, when we say that consciousness moulds and fashions behaviour, we do not intend to imply that consciousness is an underlying cause. We are not using the term consciousness in a metaphysical sense. We mean that consciousness is the expression of certain conditions under which behaviour is guided. Instead of saying, therefore, that consciousness utilizes certain sensory data, it would be more correct to say that it is the sum-total of these data which are the psychical expression of certain brain conditions under which behaviour, as a matter of fact, takes a given set or direction. We use the word consciousness, then, not in its metaphysical sense of an underlying cause or force, but in its scientific sense, as the concomitant of certain antecedent conditions. Our common modes of speech lend themselves with misleading facility to metaphysical assumptions, all the more insidious since they are not consciously acknowledged as such. And not only what we comprise under the broader group-name “consciousness,” but what we include under narrower group-names, such as “impulse,” “volition,” “instinct,” “intelligence,” “reason,” and the like, often do duty as underlying causes of the phenomena, which, from the scientific point of view, they do no more than name.

We often say, for example, that interest guides behaviour in this direction or in that. But such interest must not be regarded as an impelling force; it is an attribute of the conscious situation, more or less suffused with feeling-tone. It is not easy to define; but it seems to take on its distinctive character when re-presentative elements contribute what Dr. Stout[121] terms “meaning” to the conscious situation. The meaning in the early stages of mental development is, however, merely perceptual, and not that which comes much later—that which is implied in the phrase “rational significance.” In the chick which has tasted a cinnabar caterpillar the situation evoked by the sight of this larva has meaning in virtue of the actual experience. But, in this case, the meaning is not conducive to continued interest, since it checks, rather than stimulates, behaviour. At first, indeed, there may be the repellent interest of aversion. But this passes by, and the larvæ are soon ignored. Small worms also acquire meaning, and here the interest is attractive, and is stimulated afresh each time the meaning is reinforced by repetition of the act of seizing and swallowing.

We have seen that it is through behaviour that things become differentiated from their surroundings, and acquire relative independence in experience. It is through behaviour that what we have termed conscious situations develop. The thing is the centre or nucleus of a developing situation—that which starts the behaviour, and towards which the behaviour is directed; or, since the behaviour may be that of avoidance or escape, we should, perhaps, rather say, it is that to which the behaviour has reference. Now, if interest is the feeling-tone attaching to the whole attentive situation, and if the nucleus of the situation is the thing, it naturally follows that the thing becomes the centre of interest. The mouse is a centre of absorbing interest to the cat, her eggs to the mother-bird, his mate to the sparrow in the spring. Companions are centres of abiding interest to social animals, because they are also the centres of social behaviour and the conscious situations arising thereout; because they evoke in special ways the attentive situation.

The differentiated thing being thus a centre of interest, a relatively fixed nucleus in a changing conscious situation, the development of which is due to behaviour, there can be no question that, among social animals, the companion becomes a peculiar and specialized centre. Around him develops a particular type of behaviour. Towards him the reactions are of a quite distinctive kind. Mother and offspring, mate and mate, are reciprocal centres of interest. To the offspring the parent is a common centre of interest. As they grow up together, what is of interest to one is likewise of interest at the same time to others. Imitation begets similarity of conscious situations. In many ways such community of interest is fostered; and through this community of interest the conscious situations acquire their distinctively social character. Not only is the companion, as the nucleus of a situation, a thing which reacts in altogether special ways, so that it becomes differentiated from other things as something the meaning of which, and the interest in which, are sui generis and unique in type; but it enters into other situations in ways that are also peculiar and characteristic. A worm is thrown to a couple of chicks, and is to each a centre of interest—the nucleus of a situation involving appropriate modes of behaviour. But into this situation there enters for each of them, in a quite peculiar and distinctive way, the action and behaviour of the other chick. The situation is complicated by the introduction of a second centre of interest, and the behaviour has reference to both centres. Instead of quietly and leisurely dealing with the worm in accordance with its special meaning, as it does when there is no rival in the field, the chick darts at it, and bolts with it in accordance with the special meaning which its neighbour’s presence, under such circumstances, has acquired. And this different behaviour carries with it a felt difference in the conscious situation—the interest of which is centred in the companion. Or take the case of a herd of cattle, which attacks a common enemy. The enemy is the primary nucleus of the situation, but it is profoundly modified by the presence of companions by which the behaviour of attack is determined. The situation is social, and not merely individual, and a social interest suffuses it, and gives it a distinctive character.

In this social interest probably arise the germs—but only the germs—of the sense of personality. Some, indeed, go so far as to urge that we learn to know ourselves only through knowing others. The genetic order, so far as there is an order, is, they say, not first the ego and then the alter, but first the mother and companions and then through them the self. Or, to put this point of view in a less questionable form, it is only through the reaction of one on the other that the two are differentiated. Be this as it may, it is only through the action of environment on the organism, and the reaction of the organism on the environment in behaviour, that experience becomes polarized into subject and object. Let it be clearly understood that for the animal, in all probability, subject and object are not clearly distinguished, and set over against each other in the antithesis of thought. Only late in mental development are the self and the world distinguished in subtle analysis as different aspects of the common experience in which both have their inseparable being. Animals, and perhaps the majority of mankind, never trouble themselves about object and subject as clearly realized products of conception and reflective thought. For these concepts are exceedingly subtle. And here, too, the external aspect of experience has the precedence, so far as there is precedence. A healthy lad from the moment he gets up in the morning till the moment he goes to bed, lives chiefly in the objective aspect of experience, an aspect which is in us chiefly associated with the products in consciousness of the leading senses of sight and hearing. But the subjective aspect creeps in when he is hurt, when he is hungry, when he is fatigued. He does not argue about the matter, or formulate it in definite terms. He just dimly feels that the interest has somehow shifted. Still more dimly does the animal feel that, apart from external interests which prompt nine-tenths of its behaviour, chiefly through the senses of sight, hearing, and smell, there are also matters in which the interest has somehow shifted to his own body. For the germ of self is essentially an embodied self. And perhaps the emotions, which ring through the system for some time after the external cause has been removed, serve in some degree to aid in this dimly felt shifting of interest.

Whatever may be the exact psychological nature of the emotions—and there has been much discussion of the question—it may be regarded as certain that they introduce into the conscious situation elements which contribute not a little to the energy of behaviour. They are important conditions to vigorous and sustained conation. And so closely interwoven are these elements with the whole situation in its impulsive aspect, that their disentanglement, in psychological analysis, is a matter of extreme difficulty. I have elsewhere[122] devoted some space to the consideration of the matter. I there follow Professor William James in regarding organic effects, other than motor sensations, as specially characteristic of the emotions in their primary genesis. The cold sweat, the dry mouth, the catch of the breath, the grip of the heart, the abdominal sinking, the blood-tingle or blood-stagnation—these and their like, in varied modes and degrees, characterize the emotions of fear, dread, anger, and so forth, when they rise to any pitch of intensity, and contribute largely to their sharpness and piquancy. These organic effects may be regarded as part of the private and individual business of the body; but in experience they closely coalesce with the motor effects through which the animal has to deal in practical behaviour with that which evokes the emotion.

On this view these organic states which contribute characteristic elements in the emotional consciousness are due to afferent data from the vascular system and visceral organs, just as motor consciousness is due to afferent data from the parts concerned in overt behaviour. But, associated with emotional states, there are also certain motor reactions, which we speak of as their “expression”—so carefully discussed and elucidated by Darwin,—and these unquestionably contribute data to consciousness which coalesce with those afforded by the visceral and vascular elements. The whole is commonly suffused with feeling-tone, and the object which excites the emotion is a centre of pleasurable or painful interest. Representative elements, as experience develops, crowd into the conscious situation and render it more complex. And in addition to all this, there is, apart from the motor expression, the strenuous behaviour of flight or attack, or other mode of vigorous procedure which we commonly speak of as the outcome of the emotional state. The conscious situation, in the case of an enraged or scared animal actually behaving as such, is thus exceedingly complex. And it should be understood that in urging the importance of vascular and visceral elements, this complexity is nowise denied. What is suggested is that these elements are essential, and that they serve to characterize the distinctively emotional factor in the situation, that in any case they heighten the conative tendency.

Sufficient has now been said to indicate—but scarcely more than indicate—the importance of feeling-tone, interest, and emotion in determining the nature, character, and effective energy of the conscious situations which arise in the course of animal behaviour. They largely influence, and in part direct, the course of the conative tendency. But they also occur as its sequel. In animal, as in human life, the successful attainment of the end towards which conation sets is highly pleasurable. The equilibrium that is reached after instability, though it marks the close of present endeavour, leaves after-effects in consciousness in a sense of satisfaction which enters re-presentatively into later situations and helps to further more strenuous endeavour.

II.—Play

“There are two quite different popular ideas of play,” says Professor Groos, in his admirable work on “The Play of Animals.” “The first is that the animal (or man) begins to play when he feels particularly cheerful, healthy, and strong; the second that the play of young animals serves to fit them for the tasks of later life.” The former view, in which the latter may be included incidentally as a result, is closely associated with the names of Schiller,[123] who suggested it, and of Mr. Herbert Spencer,[124] who developed it. Mr. Wallaschek[125] expresses the conception briefly and clearly when he says, “It is the surplus vigour in more highly developed organisms, exceeding what is required for immediate needs, in which play of all kinds takes its rise, manifesting itself by way of imitation or repetition of all those efforts and exertions which are essential to the maintenance of life.” That surplus vigour is often a condition favouring the manifestation of play is probable enough, and seems to be supported by observation and experience; but that it is likewise a condition favouring the chase, combat, mating, and much of the serious business of animal life seems equally unquestionable. Success in all these matters is largely determined by overflowing energy. In play, however, this surplus vigour finds vent when there is no serious occasion for its exercise. But, as Professor Groos says,[126] “while simple overflow of energy explains quite well that the individual who finds himself in a condition of overflowing energy is ready to do something, it does not explain how it happens that all the individuals of a species manifest exactly the specific kind of play expression which prevails with their own species, but differs from every other.” And if to this it be replied, that the specific kind is determined by repetition or imitation of what we have called the serious business of animal life, Professor Groos’s rejoinder is,[127] that “the conception of imitation here set forth—namely, as the repetition of serious activities to which the individual has himself become accustomed—cannot be applied directly to the primary phenomena of play—that is, to its first elementary manifestations” prior to any experience of these serious activities. The repetition (with a difference!) is in such cases not the re-enactment of what has been previously performed in full earnest by the individual, but rather the reappearance in the young of ancestral modes of procedure—in other words, its specific character is such because it is a piece of instinctive behaviour or arises from instinctive proclivities. And this is the central point of the interpretation elaborated with great skill and candour by Professor Groos. Play is instinctive; and its biological value lies in the training it affords for the subsequent earnest of life.

Before leaving the surplus energy theory of play one more point made by Professor Groos may be mentioned. He contends that, though superabundant energy is a favouring condition of animal play (as it is, indeed, of all animal behaviour), still it is not a necessary condition. Animals often play when they are tired out. “Notice a kitten when a piece of paper blows past. Will not any observer confirm the statement that, just as an old cat must be tired to death or else already filled to satiety if it does not try to seize a mouse running near it, so will the kitten, too, spring after the moving object, even if it has been exercising for hours and its superfluous energies are entirely disposed of? Or observe the play of young dogs when two of them have raced about the garden until they are forced to stop from sheer fatigue, and they lie on the ground panting, with tongues hanging out. Now one of them gets up, glances at his companion, and the irresistible power of his innate longing for the fray seizes him again. He approaches the other, sniffs lazily about him, and, though he is evidently only half inclined to obey the powerful impulse, attempts to seize his leg. The one provoked yawns, and in a slow, tired kind of way puts himself on the defensive; but gradually instinct conquers fatigue on him too, and in a few minutes both are tearing madly about in furious rivalry until want of breath puts an end to the game. And so it goes on with endless repetition, until we get the impression that the dog waits only long enough to collect the needed strength, not till superfluous energy urges him to activity.”[128]

Coming now to Professor Groos’s interpretation of play, we find in it, perhaps for the first time in the literature of the subject, adequate stress laid on its biological value. “The play of young animals,” he says,[129] “has its origin in the fact that certain very important instincts appear at a time when the animal does not seriously need them.... Its utility consists in the practice and exercise it affords for some of the more important duties of life, inasmuch as selection [in the higher animals] tends to weaken the blind force of instinct, and aids more and more the development of independent intelligence as a substitute for it. At the moment when intelligence is sufficiently evolved to be more useful in the struggle for existence than the most perfect instinct, then will selection favour those individuals in whom the instincts in question appear earlier and in less elaborated forms—in forms that are merely for practice and exercise,—that is to say, it will favour those animals which play.... Animals cannot be said to play because they are young and frolicsome, but rather they have a period of youth in order to play; for only by so doing can they supplement the insufficient hereditary endowment with individual experience, in view of the coming tasks of life.”

Some stress is here laid on the fact that important instincts appear at a time when the animal does not seriously need them. It seems to imply the doctrine of what biologists term “acceleration”—which means the development of an organ or mode of behaviour at an earlier period in the descendants than that at which it appeared in the ancestors. Thus the adult fighting or hunting instinct of past generations appears in the young to-day as a fighting-play or a hunting-play. It is open to question, however, whether either the instinctive behaviour or the conscious situation in the one case and the other is so nearly identical that the playful fight or hunt can fairly be called the same instinctive procedure as the serious combat or chase. We may hold, with Professor Groos, that the one is an invaluable preparation for the other without identifying them as the same behaviour under different conditions. Indeed the conditions are so different that the identification seems strained. The question may be left open, however, without impairing the value of Professor Groos’s suggestion. And we may divide the preparatory behaviour in what is commonly called play under two heads: first, general preparation for varied modes of serious effort in after-life; and secondly, special preparation for particular forms of this after-effort. Under the first will fall what Professor Groos terms experimentation and movement play, including what Dr. Stout, who fully realizes its importance, calls “manipulation”;[130] under the second, such forms as hunting-play and fighting-play.

Nothing is more characteristic of the young of intelligent animals than the variety and persistency of their behaviour, their sensitiveness to stimuli of many different kinds, their restlessness of swiftly changing attention and response, with occasional pauses of continued effort in some special direction. Constantly on the alert, they exhibit in all its shifting phases behaviour which we interpret as indicating curiosity, inquisitiveness, love of mischief, destructiveness, and so forth. The facts are so familiar to every observer of young animals that it is unnecessary to give any detailed illustration. Watch a kitten in this stage of its development and carefully note its behaviour during half an hour; the variety of effort, the rôles played by trial, failure, and success, the gain of skill and control over behaviour, will at once be evident. Or devote an equal space of time to observing young jays, magpies, or jackdaws. Every projecting piece of wire or bit of wood in their cage is pulled at this way and that way, from above, from below, from the side. Now one, then another, loose object is picked up and dropped, turned over, carried about, pulled at, hammered at, stuffed into this corner and into that, and experimented with in all possible ways. Then the wise bird goes to sleep, and wakes up again only to resume with new zest its persistent and varied efforts, by which it becomes acquainted with all the details of its environment. Watch young birds on the wing gaining their mastery of the air in flight, young seals tumbling in the water, young foals scampering and kicking up their heels in the meadows. A little observation, as occasion serves, a little attention to the progress towards an adequate experience of the meaning of things, towards more complete control, and increased nicety of behaviour, whether in reference to their surroundings, or in powers of finished locomotion, will serve to bring home what Professor Groos includes under experimentation and movement plays. He regards it all as play, since it seems to have no serious end, and is just a preparation for the sterner realities of adult life. And for human beings, whose work is so largely enforced, the freedom and evident joy of it all suggests the play which has acquired for us the meaning of relaxation from irksome effort, and glad abandonment to less constrained modes of behaviour. But in young animals such play is, after all, the serious business of their time of life. Its import for their future welfare can scarcely be overestimated.

And its import is in large degree psychological. If we watch a young puppy or kitten learning gradually to deal effectively with some difficulty in its extending environment, we see that it puts forth its efforts at first in a somewhat random and indefinite fashion. It is one of those animals in which intelligence has been evolved to supersede and become the more plastic substitute for instinct. The random and indefinite movements, are in detail reflex responses to stimuli. But whereas, in a piece of highly elaborated instinctive behaviour, such reflexes are grouped into a whole which is co-ordinated through inherited nervous mechanism; in the case of the acts of the puppy or kitten they have to be further co-ordinated, or more elaborately grouped, through experience. To act in one way some of the reflexes have to be checked as redundant and not to the point: to act in another way other reflexes have to be similarly checked; and in a third way, yet others. But in all three some of the reflexes are utilized to different ends. Many conscious situations contain common elements; and this tends to give unity to the developing experience. But they contain also elements and groupings which afford that diversity without which conscious behaviour could not be accommodated to them. So that we have here the conditions under which what is technically termed “the concomitant differentiation and integration of experience” can proceed.

And if we speak of the instinct of experimentation we must remember that what we are dealing with is rather an innate tendency or instinctive propensity than a definite and relatively clean-cut piece of instinctive behaviour. It comprises a great number of inherited reflex acts, and may perhaps be fairly called instinctive in detail. But experimentation must be regarded rather as the proximate end of a conative tendency, or group of conative tendencies, whose ultimate biological end is success in dealing with the environment in the sterner struggle for existence during adult life. The tendency is inherited, and therefore falls under the head of instinctive propensity. But “experimentation” is a group-term under which we comprise the general drift of varied modes of behaviour, founded indeed on a congenital basis, but receiving its stamp and character from what is acquired in the course of the experience it provides. It is essentially a process whereby the conscious situations acquire what Dr. Stout terms meaning; and is specially interesting as affording an example of the way in which intelligence moulds and refashions a number of disconnected reflex responses. And if, following Professor Groos, we call it play, it is a little difficult to see how it can be brought in line with his statement[131] that “the play of youth depends on the fact that certain instincts, especially useful in preserving the species, appear before the animal seriously needs them.” Does experimentation occur before it is needed in the economy of animal behaviour? And might we not with equal truth say that the play of youth depends on the fact that certain acquired habits, especially useful in preserving the species, are gained before the animal seriously needs them?

Passing now to those forms of play which afford more special preparation for particular forms of after-effort, under which fall such types as hunting-play and fighting-play, we may refer the reader to the copious examples so carefully collected by Professor Groos. The way in which a kitten pats a cork or a ball, making it roll and then pouncing upon it, is a characteristic example of animal play. Valuable as a preparation for dealing successfully with a mouse when occasion shall arise, this is a specialized form of experimentation; and it is more obviously in line with the hunting-behaviour of later life than is general experimentation with any particular modes of future behaviour. Still it is essentially experimentation, with the instinctive propensity setting in more definite channels. Its value lies in the acquisition of skill under circumstances easier than those presented in the serious chase. So, too, in the case of the playful tussles of puppies or in that of the kitten, which not only shows playful fight to its brothers and sisters, but also to its mother, who responds by holding down the struggling and scratching little creature. Unquestionably, there is an instinctive propensity; much of the detail, and some of the grouping, exhibit inherited reflexes due to special modes of stimulation. No doubt many of these responses occur in a similar but more emphatic way in a serious fight, and yet we may hesitate before committing ourselves to the theory of acceleration. It is at least equally probable that play as preparatory behaviour differs in biological detail (as it almost certainly does in emotional attributes) from the earnest of after-life, and that it was evolved directly as a preparation, as a means of experimentation through which certain essential modes of skill were acquired,—those animals in which the preparatory play propensity was not inherited in due force and requisite amount being worsted in the combats of later life, and eliminated in the struggle for existence. For, in the preparatory tussles and squabbles and playful fights of young animals, experience is gained without serious risk to life and limb.

The modifications of Professor Groos’s biological interpretation of play which we would suggest are so slight that we may be said to accept it almost unreservedly. The play of youth, we may urge, depends on instinctive propensities to experimentation in varied ways, some of more general and others of more special import; and the value of such experimentation lies in the fact that it is a means of acquiring, under circumstances more easy and less dangerous than those of sterner life, experience and skill for future use. In a word, play depends on instinctive propensities of value in education.

Passing now to a brief consideration of the feelings and emotions which we may suppose to accompany play, we may place first those which characterize, from this point of view, general experimentation. We have here rapidly varying situations charged with conative impulse, the satisfaction of which must bring pleasure—the occasional thwarting of which is probably toned with the opposite—the latter serving, through contrast, to enhance the satisfaction of ultimate success. Both pleasure and its antithetical state of feeling are primarily matters of the conscious situation as a whole, and even in ourselves are difficult to distribute in analysis. But assuredly no small share of the total product must be assigned to the successful behaviour which consummates the conative tendency. Indeed, it is the thwarting of free action which is the source of much of the discomfort of the young. Unimpeded and vigorous behaviour also brings with it secondary effects in organic processes—fuller heart-beat, freer circulation, deeper respiration, better digestion, firmer muscular tone, and so forth—which have a marked effect on the conscious situation, and aid in producing that emotional tone which cannot, perhaps, be named in better terms than “good spirits” and the joy of existence, so forcibly suggested during the free play of youth. On the other hand, there is no more piteous sight than that afforded by the young animal, “cabined, cribbed, confined,” suffering from ennui and depression—all its organic processes sluggish and craving to be quickened into the natural vigour of life, not creeping slowly through the veins, but coursing at full flood.

In the psychological aspect of play Dr. Groos assigns perhaps the first place to pleasure in the possession of power, or, as Preyer phrases it, pleasure in being a cause. We must be careful, however, lest in using such expressions we seem to imply that animals—even quite young animals—are capable of entertaining ideas which belong to a much later stage of mental development. Speaking of “joy in ability or power,” Professor Groos says,[132] “This feeling is first a conscious presentation to ourselves of our personality as it is emphasized by play.... But it is more than this; it is also delight in the control we have over our bodies and over external objects. Experimentation in its simple as well as its more complicated forms is, apart from its effect on physical development, educative in that it helps in the formation of causal associations.... The young bear that plays in the water, the dog that tears a paper into scraps, the ape that delights in producing new and uncouth sounds, the sparrow that exercises its voice, the parrot that smashes his feeding trough—all experience the pleasure in energetic activity, which is, at the same time, joy in being able to accomplish something.” But those who agree with Dr. Stout, as I do without hesitation, in denying personality (save in a very embryonic condition) and the conception of causation to animals in the perceptual stage of mental evolution, though they may find in Dr. Groos’s contention a central core of truth, will be unable fully to accept his manner of presenting it. “Any single train of perceptual activity,”[133] says Dr. Stout, “has internal unity and continuity. But where conscious life is mainly perceptual, the several trains of activity are relatively isolated and disconnected with each other. They do not unite to form a continuous system, such as is implied in the conception of a person. We must deny personality to animals.” To this I would merely add that, even where perceptual continuity in animals reaches its maximum, it is not reflectively grasped as a whole, and the ideal construction of the personal ego is not conceived as antithetical to the impersonal world of objects. With what Dr. Stout says about causality I am in complete agreement. “We must notice,”[134] he urges, “the essential difference which separates the merely perceptual category from that of ideational and conceptual thought. The perceptual category is always purely and immediately practical in its operation. It is a constitutive form of thought only because it is a constitutive form of action. The question ‘Why?’ has no existence for the merely perceptual consciousness. It does not and cannot inquire how it is that a certain cause produces a certain effect. It does not and cannot endeavour to explain, to analyze conditions so as to present a cause as a reason. It does not compare different modes of procedure or different groups of circumstances, so as to contradistinguish the precise points in which they agree from those in which they disagree, and in this way to explain why a certain result should follow in one case and a different result in another case. Causality in this sense can only exist for the ideational consciousness, and the development of the ideational consciousness in this direction is a development of conceptual thinking—of generalization.”

Wherein, then, lies the central core of truth in Professor Groos’s contention? In the satisfaction that arises from the success of any conative activity. We see that the animal striving and doing falls within our conception of a cause, in the scientific sense of the word,—a relatively constant and continuous antecedent of diverse sequent effects. We infer that pleasure accompanies the satisfaction of the multifarious conative impulses. The pleasure is the animal’s; the conception of causality and of self as a continuous person, still the same amid diversity of conscious situations, is ours. If we bear this in mind there can be no objection to our attributing to animals joy in ability or power. It is the pleasure derived from that successful conation whereby animals fall into the category of causes within the scheme of our rational thought.

In fighting-play and hunting-play, too, there arise in more specific forms the pleasures of successful conation with the antithetical feelings accompanying thwarted conation. And these are distinguished from earnest, partly because the companion or the inanimate substitute for prey is the centre of a different situation from that afforded by an enemy or the natural object of the chase; partly by the absence of certain insistent emotional states which characterize earnest and the serious business of life. In fighting, this is anger. And we often see the tendency of this to arise in the midst of fighting-plays, and at once say that it becomes serious and passes into fighting in earnest. Indeed, some tinge of earnest, with its fuller emotional tone, forms part of the preparation for future life, and so far falls within the definition Professor Groos gives of play. From which we may see that play is not easily marked off from other forms of conation.

Brief reference to the element of “make-believe,” which Dr. Groos assigns to the higher forms of play, may be reserved for our fourth section; and some further discussion of its psychological aspect to the concluding chapter.

III.—Courtship

We have seen that Professor Groos regards play as the practice and preparation for the serious business of animal life. Founded on instinctive tendencies, it has its biological value in the acquisition of practical acquaintance with the environment, and of skill in dealing with it effectually. It is an education in behaviour of the utmost service in view of the struggle for existence. It is full of the pleasure derived from the satisfaction of innate impulse, the success of conative effort, and the diffused sense of well-being which accompanies a life of action, free and unrestrained. This freedom and gladness lead us to call it play; but we must not draw the inference that the playful animal knows that it is playing, or forms any conception of the antithesis between work and play, which is a product of late development.

In laying stress on the biological value of certain modes of behaviour which we thus call play, a value which lies in the practice and preparation they afford for life’s more earnest work, Professor Groos deserves our hearty thanks. Nor need our thanks be less hearty if we find that he has in some degree been anticipated by Darwin; for he has elaborated with systematic care what Darwin suggested incidentally. “Nothing is more common,” said Darwin,[135] “than for animals to take pleasure in practising whatever instinct they follow at other times for some real good. How often do we see birds which fly easily, gliding and sailing through the air, obviously for pleasure! The cat plays with the captured mouse, and the cormorant with the captured fish. The weaver bird, when confined in a cage, amuses itself by neatly weaving blades of grass between the wires of its cage. Birds which habitually fight during the breeding season are generally ready to fight at all times; and the males of the capercailzie sometimes hold their Balzen, or leks, at the usual place of assemblage during the autumn. Hence it is not at all surprising that male birds should continue singing for their own amusement after the season of courtship is over.”

In the behaviour of courtship we have what is essentially part of the serious business of animal life. And in including it under the heading of “Love Plays,” Professor Groos may seem to be forgetful of his own definition of play. He is, however, too clear a thinker not to see, and too honest an exponent not to say, that much of the emotional behaviour commonly regarded as courtship falls outside his main thesis “in being, strictly speaking, not mere practice preparatory to the exercise of an instinct, but rather its actual working.”[136] But behaviour of a somewhat similar kind is seen in young animals before the time of mating has arrived, and is exemplified both in young and adults under circumstances different from those which distinguish what we may term the pairing situation. This, at any rate, may be regarded as a form of experimentation and practice in the arts of courtship. On different grounds does Professor Groos attempt to justify the inclusion of actual courtship under the head of play. For it may also, he thinks, even at the time of its serious exercise, be to some extent artful, involving “make believe,” and therefore playful in a somewhat different and more subtle sense; but a brief reference to “make believe” we may reserve for our next section.

There can be no question that special modes of behaviour often characterize the pairing situation, and that these not only exemplify an instinctive tendency, but from their constancy and relative definiteness constitute types of instinctive behaviour. They would form parts of any definition of a species founded not on structure but on behaviour. And if animals have feelings and emotions at all—if they are not Cartesian automata, which merely seem to be guided in their actions by consciousness—there can be but little question that the behaviour which characterizes the sexual situation is unusually charged with feeling-tone, and accompanied by all those adjuncts which distinguish an emotional state, broadly considered. This matter is of no little importance in our interpretation of the phenomena described as courtship. Do the accompanying feeling-tone and the state of emotional exaltation influence the behaviour, or would it run a similar course in the absence of any such accompaniments? If, as we can scarcely doubt, the consciousness attending the situation does profoundly influence the behaviour, the further question arises—Is this influence mainly the result of the presence and behaviour of an individual of the opposite sex? To this, again, we must answer that, so far as we can learn by observation, behaviour unquestionably is determined by such influence in the serious business of courtship. And then the further question arises—Is it a matter of indifference what the appearance and behaviour of the individual of the opposite sex may be? Are A., B., C., and the rest of the male alphabet, precisely alike in stimulating in a similar manner, and to a similar degree, the sexual impulse of the female? If we admit any differential influence, and if this influence takes effect in the sexual union to which courtship is preparatory, we so far admit the efficacy of that which Darwin termed sexual selection.

Let us, however, before proceeding with general considerations, present one or two examples of the facts which observation has furnished with regard to specialized modes of behaviour at the time of pairing. Speaking of American night-hawks, Audubon says, “Their manner of flying is a good deal modified at the love season. The male employs the most wonderful evolutions to give expression to his feelings, conducting them with the greatest rapidity and agility in sight of his chosen mate, or to put to rout a rival. He often rises to a height of a hundred metres and more, and his cries become louder and louder as he mounts; then he plunges downward with a slanting direction, with wings half open, and so rapidly that it seems inevitable that he should be dashed to pieces on the ground. But at the right moment, sometimes when only a few inches from it, he spreads his wings and tail, and, turning, soars upward once more.”[137] Mr. Strange, quoted by Darwin[138] says of the satin bower-bird, “at times the male will chase the female all over the aviary, then go to the bower, pick up a gay feather or a large leaf, utter a curious kind of note, set all his feathers erect, run round the bower and become so excited that his eyes appear ready to start from his head; he continues opening first one wing, and then the other, uttering a low, whistling note, and, like the domestic cock, seems to be picking up something from the ground, until at last the female goes quietly towards him.”

Darwin describes how, in the Argus pheasant,[139] “the immensely developed secondary wing-feathers are confined to the male, and each is ornamented with a row of from twenty to twenty-three ocelli, each above an inch in diameter. These beautiful ornaments are hidden until the male shows himself before the female. He then erects his tail, and expands his wing-feathers into a great, almost upright, circular fan or shield, which is carried in front of the body. The ocelli are so shaded that, as the Duke of Argyll remarks, they stand out like balls lying loosely within sockets. But when I looked at a specimen in the British Museum, which is mounted with the wings expanded and trailing downward, I was,” adds Darwin, “greatly disappointed, for the ocelli appeared flat or even concave. Mr. Gould, however, soon made the case clear to me, for he held the feathers erect, in the position in which they would naturally be displayed, and now, from the light shining on them from above, each ocellus at once resembled the ornament called a ball and socket.” The primary wing-feathers are scarcely, if at all, inferior in beauty to the secondaries, though the markings are quite different, the chief ornament being a space parallel to the dark-blue shaft, which in outline forms a perfect second feather lying within the true feather. “Now the secondary and primary wing-feathers are not at all displayed, and the ball and socket ornaments are not exhibited in full perfection, until the male assumes the attitude of courtship.”

It is unnecessary to describe the song of birds which is generally, but not always, at its best during the period of pairing. Bechstein, who kept birds during his whole life, and studied them with care, asserts that “the female canary always chooses the best singer, and that in a state of nature the female finch selects that male out of a hundred whose notes please her most.”[140]

Thus we are led back to sexual selection. If we are satisfied that the males of certain species do as a matter of fact behave in specific and distinguishable ways at the breeding season, and in presence of their would-be mates, the question is, What, if any, is the biological value of such behaviour? What has fostered and guided it in the course of its evolution? From the case of the Argus pheasant, which is only a sample of the large class of cases in which the male has special adornments, we see that the behaviour has often direct relation to the display of such plumage, or, in some apes, of coloured surfaces, so that behaviour and ornamentation must be taken together. The essence of Darwin’s contention is, that the adornments and behaviour give rise to a situation through which the female is stimulated or excited to accept the male; that the male in which they are best developed gives rise to the most effective situation, produces most excitement, and therefore has the best chance of acceptance, being “unconsciously preferred;”[141] and that he thus begets offspring which inherit his adornments and modes of behaviour, such inheritance being, however, confined to the males. Thus sexual selection takes effect through preferential mating, whereby certain hereditary traits are transmitted and become racial characteristics. And this is brought about through an appeal to consciousness, and seems to involve choice—generally that of the female.

Now, as I have elsewhere urged,[142] the hypothesis of sexual selection has often been placed in a false light by the introduction of the unnecessary supposition that the hen bird, for example, must possess a standard or ideal of æsthetic value, and that she selects that singer which comes nearest to her conception of what a songster should be. Darwin occasionally expressed himself unguardedly in the matter; he says, for example, that the female appreciates the display of the male, and places to her credit a taste for the beautiful.[143] But he also distinctly states that “it is not probable that she consciously deliberates; she is most excited or attracted by the most beautiful, or melodious, or gallant males.”[144] This is all that is really necessary for the theory of sexual selection. The hen accepts that mate which by his song or otherwise excites in sufficient degree the pairing impulse; if others fail to excite this impulse, they are not accepted. Even Mr. A. R. Wallace, who rejects the theory save in a very subordinate form, says[145] that “it may be admitted, as highly probable, that the female is pleased or excited by the display,” and speaks[146] of a possible choice of “the most vigorous, defiant, and mettlesome male,” giving, moreover,[147] several telling examples of preferential mating. Stripped of all its unnecessary æsthetic surplusage, at any rate so far as this implies an æsthetic ideal, or æsthetic motive, the hypothesis of sexual selection suggests that the accepted mate is the one which adequately evokes the pairing impulse.

Here Dr. Groos makes an interesting and important contribution to the subject. He lays stress on the coyness and reluctance of the female, and illustrates it by examples derived from observation. “Thus the female cuckoo answers the call of her mate with an alluring laugh that excites him to the utmost, but it is long before she gives herself up to him. A mad chase through tree-tops ensues, during which she constantly incites him with that mocking call, till the poor fellow is fairly driven crazy. The female kingfisher often torments her devoted lover for half a day, coming and calling him, and then taking to flight. But she never lets him out of her sight the while, looking back as she flies and measuring her speed, and wheeling back when he suddenly gives up the pursuit. The bower-bird leads her mate a chase up and down their skilfully built pleasure-house, and many other birds behave in a similar way. The male must exercise all his arts before her reluctance is overcome. She leads him on from limb to limb, from tree to tree, until it seems that the tantalizing change from allurement to resistance must include an element of mischievous playfulness.”[148]

Professor Groos regards the instinctive coyness of the female as the most efficient means of preventing the too early and too frequent yielding to sexual impulse.[149] He thinks it probable that “in order to preserve the species the discharge of the sexual function must be rendered difficult, since the impulse to it is so powerful that, without some such arrest, it might easily become prejudicial to that end. This same strength of impulse is,” he adds,[150] “itself necessary to the preservation of the species; but, on the other hand, dams must be opposed to the impetuous stream, lest the impulse expend itself before it is made effectual, or the mothers of the race be robbed of their strength, to the detriment of their offspring.” It has its origin in the general fact that, before any important motor discharge takes place, there is apt to be a preparatory and gradually increasing excitement. But this is specially emphasized in association with the sexual impulse. As Professor Zeigler wrote, in a private communication to Dr. Groos,[151] “Among all animals a highly excited condition of the nervous system is necessary for the act of pairing, and consequently we find an exciting playful prelude very generally indulged in.”

Courtship may thus be regarded from the physiological point of view as a means of producing the requisite amount of pairing-hunger; of stimulating the whole system and facilitating general and special vascular changes; of creating that state of profound and explosive instability which has for its psychological concomitant or antecedent an imperious and irresistible craving. This not only overcomes the coyness of the female, but generates and strengthens the ardour of the male—a point on which, perhaps, Professor Groos does not lay sufficient stress. For the process is reciprocal; and though the male leads in the ardour of courtship, yet this ardour constantly grows till at last it overcomes the barriers of reluctance. Courtship is thus the strong and steady bending of the bow that the arrow may find its mark in a biological end of the utmost importance in the survival of a healthy and vigorous race.

The coyness and reluctance of the female afford the conditions under which the bow is bent to the full. But they also afford the conditions of the apparent act of choice. This takes the place, on the perceptual plane of mental development, of that deliberation which precedes the higher act of choice on the ideational plane. For psychology, as well as for biology, then, Dr. Groos’s suggestion is a welcome and helpful one. Both upholders of sexual selection and critics of that hypothesis, have been apt to regard the choice of a mate in animals from too anthropomorphic a point of view—to look upon it as the outcome of rational deliberation, of weighing in the æsthetic balance the relative attractiveness of this suitor and of that, and of reaching a definite conclusion that the one is to be accepted because he behaves or is adorned in such and such a way, while the other is to be rejected because he falls below all reasonable standards of requirement. The choice exercised by the female, if so we term it, is far simpler and more naïve. Indeed, Professor Groos goes so far as to say that on his hypothesis the element of choice is altogether abolished. “It is the instinctive coyness of the female,” he says,[152] “that necessitates all the arts of courtship, and the probability is that seldom or never does the female exert any choice. She is not awarder of the prize, but rather a hunted creature. So, just as the beast of prey has special instincts for finding his prey, the ardent male must have special instincts for subduing female reluctance. According to this theory, there is choice only in the sense that the hare finally succumbs to the best hound, which is as much as to say that the phenomena of courtship are referred at once to natural selection.” He reaches this conclusion, however, by gradual stages. He first urges[153] that “it would be absurd to affirm that all bird songs originate in a conscious æsthetic and critical act of judgment on the part of the female. A conscious choice either of the most beautiful or the loudest singer is certainly not the rule, and probably never occurs at all. But,” he adds, “is it not still a choice, though unconscious, when the female turns to the singer whose voice, whether from strength or modulation, proves most attractive? Even if the song is primarily a means of recognition or an invitation from the male, still the psychological effect must be that the female follows the songster that excites her most, and so exerts a kind of unconscious selection.”

The phrase “unconscious choice” is, however, somewhat unsatisfactory, especially when we remember that it is used to indicate the result of a direct appeal to the conscious situation. If, however, we say that it is perceptual choice arising from impulse as distinguished from ideational choice due to motive and volition, we see that the distinction is in line with that which we have drawn again and again, and which Dr. Stout so well emphasizes in his “Manual of Psychology.” But we have also drawn the distinction between instinctive behaviour prior to individual experience, and intelligent behaviour the result of such experience. Under which of these classes does the behaviour of the female during courtship fall? Professor Groos, in the further development of his hypothesis, seems to place it in the instinctive category. “Instead of a conscious or unconscious choice, of which we know nothing certain,” he says,[154] “we have the need of overcoming instinctive coyness in the female, a fact familiar enough, but hitherto not sufficiently accounted for. Then the question no longer is, which among many males will be chosen by the female, but which one has the qualities that can overcome the reluctance of the female whom he woos. Sexual selection would then become a special case of natural selection.”