UNIVERSITY OF CALIFORNIA MEDICAL CENTER LIBRARY SAN FRANCISCO Ex Libris C. K. OGDEN HABIT AND INSTINCT. HABIT AND INSTINCT BY C. LLOYD ^MORGAN, F.G.S., AUTHOR OF " ANIMAL LIFE AND INTELLIGENCE," » PSYCHOLOGY FOB TEACHEES/' ETC. EDWARD ARNOLD, to t&e IFnDta CMce. LONDON: NEW YORK: 37, BEDFORD STREET. 70, FIFTH AVENUE. 1896. PREFACE. I WISH that dedications were still in vogue, so that these pages could be inscribed to all those many friends whose unfailing kindness and courtesy made my visit to the United States so pleasant, when the substance of this volume was delivered as a Lowell Course at Boston, and as lectures in New York, Chicago, and other university centres, during the early part of this year. The reader will doubtless be glad to learn that further observations — and they are much needed — on habit and instinct will probably form part of Prof. Whitman's work at an experimental station in connection with the Bio- logical Department of Chicago University. Similar observations might also be prosecuted with advantage in some of our own zoological gardens, as was the earnest wish of George Eomanes, to whose influence and encourage- ment I am, like many others, so deeply indebted. A few passages from the Fortnightly Review, Nature, Natural Science, the Monist, and the Humanitarian, may perhaps be recognized. Much of the chapter on Modifica- tion has appeared by request in Science. My best thanks are due to Mr. F. Howard Collins for many valuable suggestions. C. LL. M. BRISTOL, October, 1896. 148487 CONTENTS. I. PRELIMINARY DEFINITIONS AND ILLUSTRATIONS ... ... 1 II. SOME HABITS AND INSTINCTS OF YOUNG BIRDS 29 III. LOCOMOTION IN YOUNG BIRDS ... ... ... ... 59 IV. FURTHER OBSERVATIONS ON YOUNG BIRDS ... ... 80 V. OBSERVATIONS ON YOUNG MAMMALS ... ... ... 101 VI. THE RELATION OF CONSCIOUSNESS TO INSTINCTIVE BEHAVIOUR 126 VII. INTELLIGENCE AND THE ACQUISITION OF HABITS ... ... 144 VIII. IMITATION ... 166 IX. THE EMOTIONS IN THEIR RELATION TO INSTINCT ... ... 186 X. SOME HABITS AND INSTINCTS OF THE PAIRING SEASON ... 210 XI. NEST-BUILDING, INCUBATION, AND MIGRATION ... ... 232 XII. THE RELATION OF ORGANIC TO MENTAL EVOLUTION ... 262 XIII. ARE ACQUIRED HABITS INHERITED? ... ... ... 280 XIV. MODIFICATION AND VARIATION ... ... ... 307 XV. HEREDITY IN MAN , 323 FRONTISPIECE : GROUP OF YOUNG BIRDS, FROM A DRAWING BY G. E. LODGE. HABIT AND INSTINCT. CHAPTEK I. PRELIMINARY DEFINITIONS AND ILLUSTRATIONS. THE naturalist commonly uses the word " habits " in describing the activities and behaviour of animals, each after his kind. Having given some account, for example, of the external form and internal structure of beast or bird or insect, he proceeds to deal with its habits, its general mode of life — how it seeks its food, how it rears or makes provision for its young, and so forth. The habits of animals thus constitute a wide and interesting field for observation and study. The word is, however, often used in a more restricted sense. In speaking of human beings, we generally use the word " habit " to describe some action or mode of behaviour which results from repetition in the course of individual experience. We should not speak of an act that is only occasionally performed under special circumstances as a habit. In employing the word " habit " as a technical term for purposes of scientific description, it is expedient to adopt this restriction. In this sense a habit is a more or less definite mode of procedure or kind of behaviour which has been acquired by the individual, and has become, so to speak, stereotyped through repetition. There can be little objection, however, to the concurrent use of the word in its broader and more general acceptation ; B Habit and Instinct. and when it is so employed in this work, the context will, it is hoped, serve to make the meaning clear and to prevent misapprehension. Still, wherever it is so used there will be implied, at least, some element of that individual acquisition and repetition which gives to habit, in the narrower and more restricted sense, its salient characteristic. The word " instinct," too, is used in daily conversation and in popular speech with a signification somewhat wider and less restricted than that which attaches to it as a technical term. In the first place, it is commonly employed to distinguish broadly the doings of animals from the ways of man. The former are said to be due t< instinct, while the latter are described as rational. But not all the ways, not even all the thoughts, of man are rational. And thus, in the second place, the word "instinct" is used in describing that part of humai character and conduct which is not the outcome of consciously rational process. The man who acts without deliberation is said to do so instinctively ; the girl whc shrinks, she knows not why, from the companionship oi some of her schoolfellows, is guided, it is said, by hei natural instincts. These two uses are closely connect There is in both a common antithesis to rational ; in botl a reference to something deeply ingrained in the nature And each is serviceable, seldom giving rise to mis- apprehension, since the meaning is sufficiently defined the context. But for use as a technical term, we need further precision. The difference between a word as employed for the daily purposes of familiar conversation or in genen literature, and the same word in its usage as a technical term, is this : that in the former case it is in itself freer and more mobile, being, in its usage, moulded to definiteness by the context of the passage in which it occurs ; while Preliminary Definitions and Illustrations. 3 the latter case, as a technical term, it has to a large extent lost its freedom and mobility, being bound in the chains of a more or less precise, but at the same time more or less arbitrary, definition. For the purposes of exact science such bondage is necessary ; and there are many words, such as "force," "energy," "impression," " sensation," which we continually use in daily conversation or in general literature with a freedom which would be inadmissible in technical descriptions. Such a word is " instinct." But it unfortunately happens that, whereas physicists are generally agreed among themselves as to the exact meaning which the words " force " and " energy " shall carry as technical terms, naturalists and psychologists are by no means fully agreed * as to the precise sense in which the term " instinct " shall be used. There is, moreover, in the case of "instinct," a source of difficulty which is absent in that of the technical terms which are employed in the science of physics. Let us suppose that we are watching a silkworm spinning its cocoon. A set of activities, for the carrying out of which the structure of the caterpillar is admirably adapted, are performed before our eyes, and may be watched in all their stages ; such activities, if they fulfil certain conditions, we term instinctive. But if now we are asked what prompts the silkworm at a certain stage of its existence to spin its cocoon, the reply is that this is due to " instinct." How far such a reply is justifiable we shall have to consider. But it is clear that, in the case of the activities themselves, we are dealing with matters of actual observation ; but if we say that the activities are due to instinct, we are dealing with something which cannot be directly observed, but which we infer to be present. And that which we thus * Cf. "Some Definitions of Instinct" in Natural Science for May, 1895, vol. vii. p. 321. Habit and Instinct. infer to be present is commonly ascribed to the sphere of mental phenomena, and regarded as a special mode of the workings of consciousness. If, then, we are putting the matter fairly and correctly ; if observation of the activities provides us with the facts from which to infer the existence of a special mode of the workings of con- sciousness, termed " instinct ; " it is clearly our duty, as scientific inquirers, to deal first with the observable facts, and then with the psychological inferences which may be drawn from them. Thus only can we hope to overcome the difficulties which arise from the circum- stance that the term "instinctive" is applied on the one hand to certain observable activities, and on the other hand to certain inferred mental faculties. Let us, then, proceed to consider some of the leading characteristics of instinctive activities as they present themselves to our observation and study in the animal world. In popular speech, as was noted at the outset, all the activities of animals are comprehensively instinc- tive. What we have to do, therefore, is to show in what respects the use of the word as a technical term has undergone limitation ; and to indicate the more restricted group of activities to which it is specifically applicable. In the first place, instinctive activities are severally common to, and similarly performed by, all the like members of the same more or less restricted group of animals. They are essentially lacking in individuality. The spinning of a cocoon by the silkworm, the migration of the swallow, the fieldfare, or the golden plover, the hibernation of the frog or the bear, the behaviour of an irritated bee, an irritated skunk, an irritated cuttle-fish, — these and a thousand other peculiar activities are charac- teristic of particular individuals, not in virtue of their individuality, but as representatives of their kind. I once Preliminary Definitions and Illustrations. 5 heard instinctive activities defined as those on which you could safely bet; but, if the element of chance is that which gives zest to the wager, one must add that such betting would be dull work. You might almost as well lay a wager that the sun will rise to-morrow morning, as bet, for example, that the larva of the great water-beetle (Hydropliilus piceus) will, as the period of pupation draws nigh when the insect is soon to pass into the chrysalis stage, leave the pool and bury itself in the damp earth, so constant, under the appropriate circumstances, is the performance of an instinctive activity. It need hardly be said that there is the closest possible connection between the structure and organization of any given animal and its instinctive activities. The spinnerets of the spider are associated with its web-making instinct ; the activities of flight are rendered possible by the possession of wings ; the burrowing habits of the mole are correlated with many peculiarities and adaptations of structure. The specific way in which any essential life- function — say, for example, that of respiration — is per- formed, and the activities which are rendered necessary for its performance, have been developed in direct associa- tion with the organic mechanism which is subservient to the process and the activities in question. In insects respiration is effected by means of a delicate system of ramifying tubes (the tracheal system) which open to the outer air by orifices or spiracles on either side both of the middle or thoracic and of the posterior or abdominal region. Of the two large aquatic beetles that are found in our English ponds, each must come from time to time to the surface to renew its supply of air ; * but the manner in which they take in and store the air is quite different. Dytiscus floats slowly to the surface with its hinder end * See Professor Miall's " Natural History of Aquatic Insects" (1895). Habit and Instinct. at a slightly higher level than its head, and this end breaks the surface film and rises into the air. The last pair of spiracles, or breathing orifices, near the hinder end of the body, are large and take in a direct supply, while air is also stored in the space between the wing- cases and the body, and is thus supplied to the smaller abdominal spiracles. In the great water-beetle, Hydro- philus, however, the front pair of abdominal spiracles are the largest, and the air is stored not only beneath the wing- cases, but along the hairy ventral surface of the beetle. "When the insect comes up to breathe, it is the head and not the hinder end that reaches the surface ; the feeler, or antenna, is specially modified so as to effect a communication between the whole storage area and the atmosphere ; and the air is taken in at the junction of head and thorax. Thus the activities which minister to the process of respiration are seen in each case to have a close dependence on the general structural organization of the insect. And throughout the whole animal kingdom we have abundant illustration, not only of the intimate connection between the structure of a given organ and its particular function, but also between such specific performance and the activities which lead up to it. In other words, not only does an organ respond functionally under the appropriate conditions, but the whole organism co-operates by carrying out a sometimes complicated set of activities subservient to what we see to be the end in view. This leads us on to consider the relation which an instinctive activity bears to what is termed a reflex action. If the foot of a sleeping child be lightly tickled, the foot and limb will be withdrawn from the source of irritation. This is a case of reflex action. The effects of the stimulus (tickling) are carried inwards by nerves to the spinal cord ; Preliminary Definitions and Illustrations. 7 there certain nervous centres are called into activity, as the result of which an orderly (co-ordinated) set of out- going nerve-currents are distributed to the muscles which are concerned in moving the leg. If a frog be killed by the rapid extirpation of the brain, and then its flank be sharply pinched, the hind leg of the same side will be raised, and the foot will scratch at the irritated spot. This again is a reflex action ; and the fact that the brain has been extirpated shows that spinal centres alone are sufficient for its due and accurate performance. Now, it is by no means easy, if indeed it be possible, to draw any sharp and decisive line of demarcation between instinctive activities and reflex acts. Instinct has been well described by Mr. Herbert Spencer as compound reflex action ; hence the distinction between them turns in large degree on their relative complexity. It would seem, therefore, that, whereas a reflex act — such, for example, as the winking of the eye when an object is seen to approach it rapidly — is a restricted and localized response, involving a particular organ or a definite group of muscles, and is initiated by a more or less specialized external stimulus ; an instinctive activity is a response of the organism as a whole, and involves the co-operation of several organs and many groups of muscles. Initiated by an external stimulus or group of stimuli, it is, at any rate in many cases, determined also in greater degree than reflex action by an internal factor which causes uneasiness or distress, more or less marked, if it do not find its normal instinctive satisfaction. Take, for example, the before- mentioned instinct of the great water-beetle to leave the pond and burrow in its bank when the time for pupation is at hand. There is something more here than a local response to an external stimulus ; something more, it would seem, than mere reflex action. There are activities 8 Habit and Instinct. affecting the whole behaviour of the organism, and there seem to be internal promptings of some kind due to organic conditions whose seat is within the body of the developing larva. Or take the migration of birds, their nest-building instincts, the activities involved in incubation and in the rearing of their young ; there is surely, it may be said, something in all this which may be distinguished, even if the line of demarcation be hard to draw, from reflex action. We cannot say more, however, than that the one is a more fully corporate act than the other. Eeflex action is involved in the carrying out of many instinctive activities. When the great water-beetle weaves with her spinnerets the delicate silken cocoon in which she deposits her eggs, there are reflex acts connected with the extrusion of the fluid which hardens to form the silk ; reflex acts accompany the moulding of the cocoon and its being supplied with air ; reflex acts are concerned in the laying of her eggs, " not at hazard, but in regular order, side by side ; " but during the hours of maternal labour there is an organization of all the activities into a definite line of behaviour, directed to what we see to be a final and adaptive end, and prompted, we feel sure, by some internal impulse ; and all this tends to raise series of activities, as a whole, above the level of mere reflex action. If we say that reflex acts are local responses due to specialized stimuli, while instinctive activities are matters of general behaviour, usually involving a larger measure of central (as opposed to merely local or ganglionic) co-ordination, and due to the more widely spread effects of stimuli in which both external and internal factors co-operate, we shall probably get as near as possible to the distinction of which we are in search. But it must be remembered that there are border- land cases in which the distinction can hardly be maintained. Eeverting now to the close connection we have seen to Preliminary Definitions and Illustrations. 9 exist between structure and habit, it must be noted that there are many instinctive activities that no examination of structure, with our present means and appliances, would enable us to foretell. In the tributaries of the Severn there is a spring migration of little eels, or elvers. Thou- sands may be seen swimming up stream, and even surmounting such obstacles as small waterfalls and mill- sluices by wriggling up the conferva-clad surface. But there is nothing in their structure to give a hint of this migratory instinct. If an ant-lion larva were given to a naturalist ignorant of its habits, he would no doubt be able to say that it led a predatory life. He would not infer from its structure that it made a conical pit in the sand to entrap unwary ants and other insects, and, as it lay almost concealed at the apex of the cone, scattered a shower of sand-grains, by which its victim was brought down into its very jaws. No examination of the structure of a limpet would enable us to foretell that it would wander in search of food within a radius of about a yard from its scar, performing its peregrination when the rocks were wetted by the tide, but returning home to its own particular scar on the rock ere the sun and air had baked and dried the surface, and ere the returning tide had deeply sub- merged its home.* Very many such cases might be given of activities to which the study of structure alone would afford no clue. The fact that the same organ often subserves more than one purpose may sometimes lead one astray in attempting to infer habit from structure. In Trinidad there occurs a climbing picarian bird, the red-tailed jacamar (Galbula ruficauda). It has a long, sharp, pointed bill, and no one from a study of its structure would be likely to foretell that it subsists on flies, which it catches * See Nature, vol. xxxi. p. 200; and vol. li. pp. 127 and 511. io Habit and Instinct. on the wing. And Mr. P. M. Chapman says * that these birds " are the most expert fly-catchers he has ever seen. Their watchfulness permits no insect to pass in safety. They maintain a constant look-out, turning the head quickly from side to side. The dart into the air is made with wonderful celerity. Sometimes it is straight up, again at various angles, and they go as far as thirty or thirty-five feet from their perch, to which they return after each sally." Fly-catchers, as a rule, have short bills and a broad gape. Why, then, is the long pointed bill preserved in these jacamars ? Mr. Chapman tells me that they scoop holes in the sand, in which they build their nest, and that they use their bills for this purpose. Hence, perhaps, the retention of the long pointed form. Be that as it may, no one would be likely to predict that the jacamar was one of the most expert of fly-catchers. The instinctive activities, which we have now seen to be something more than local responses to stimuli, and to involve the general behaviour of the animals which perform them ; and which, while they are correlated with organic structure, could not in many cases be inferred from the closest morphological or anatomical examination;— are characterized, as was said, by the fact that they are severally common to, and similarly performed by, all the like members of the same more or less restricted group of animals. Knowing the instinctive activities which are characteristic of the life-history of the great water-beetle or other organism, you may be sure that they are common to, and similarly performed by, all the like members of the species, the qualification like members being introduced to cover the divergencies of instinctive behaviour due to sex. It must not be supposed, however, that this constancy * " Chapman on the Birds of Trinidad," Bulletin Am. Mus. of Nat. Hist., vol. vi., 1894, p. G3. Preliminary Definitions and Illustrations. 1 1 of behaviour is absolute, and that the instinctive activities are quite invariable. Were this the case, there could be no organic progress so far as instincts are concerned. Evolu- tion would be no longer possible. The constancy is rather to be regarded as analogous to that which we find in those structural characters of animals which are termed specific or generic, as the case may be. When we say that struc- tural characters are constant, we no longer, since the revolution of thought caused by the publication of the " Origin of Species," mean that they are absolutely invari- able. We know, or have reason to believe, that these are often subject to variations, many, if not most, of which are slight and inconspicuous. In the same way, the per- formance of instinctive activities is probably subject to variations of a similar kind. This is, no doubt, difficult to establish on the basis of actual observation, since slight departures from the normal type of activity would be more liable to escape detection than departures from the normal type of structure. We must be guided by analogy, and this certainly does not warrant the assumption that con- stancy is to be interpreted in any absolute sense. The next point to notice with regard to the class of activities which we term instinctive is that they are per- formed under special circumstances, which are either of frequent occurrence, or are vitally essential to the welfare or continuance of the race. They are often of protective value, and very frequently correlated with structural characters which are likewise protective. Thus the hedge- hog, whose body is clad in a spiny skin, instinctively coils himself up when molested, and thus gives effect to his protective structure ; so, too, the tortoise instinctively withdraws his head and limbs under the carapace ; and the snail retreats within his shell. And in like manner the instincts of the hermit-crab lead him not only to withdraw 12 Habit and Instinct. into his borrowed shell, but to seek and insert himself into one suitable to his size; nay, farther, in the case of Pagurus, he may even affix to his shell a sea-anemone (Adamsia), the distastefulness of which to fishes will pre- vent his falling a prey to their voracity. In many familiar cases of mimicry, specific activities are correlated with mimetic structure and appearance. A not uncommon beetle (Clytus arietis), which is mimetic of the wasp, has a fussy manner, unlike the usually staid demeanour of beetles, which serves to make the mimicry more effectual. There occurs at the Cape of Good Hope a harmless, egg-eating snake (Dasypeltis scabra), which flattens its head, coils as if for a spring, hisses, and darts forward as though about to strike, in a way that closely resembles the characteristic mode of the berg-adder (Vipera, atropos), of which it is mimetic. It is really quite harm- less, subsisting on eggs, the shells of which are broken in the throat by the enamel-tipped processes of the verte- brae, which project into the gullet and form the so-called gular teeth ; but its resemblance both in form and be- haviour to a venomous snake presumably affords it pro- tection from enemies. Mimetic resemblance may also be of service in stealing upon prey. Thus hunting spiders, which resemble the flies on which they feed, rub their heads in very much the same way as do the flies them- selves. These mimetic activities, which are probably truly instinctive in their nature, must not be regarded as con- sciously imitative ; they are, rather, analogous to the mimetic appearance, and, like it, due to natural selection. A great number of other instinctive activities might be adduced in illustration of the fact that they are performed in subservience to the general welfare of the organism, and under circumstances which are of frequent recurrence in the life of the individual and of the species. Preliminary Definitions and Illustrations. 13 Many of these activities are so familiar to the obser- vant naturalist, constituting as they do the normal life- habits of the animals which exhibit them, that they are apt to suffer the common fate of the familiar, and receive less notice and less attention than the unusual and unfamiliar. That an insect should exhibit one set of activities as a larva or caterpillar, and a totally different set of activities as an imago or perfect insect, seems quite natural, and what we should expect. But the naturalist, who is some- thing more than a collector, sees in these activities problems not less difficult of solution than are the problems of structure with which they are associated. And, in any consideration of instinct, these familiar activities which are performed under the ordinary circumstances of normal life must not be allowed to fall into the background. They form the largest, if not the most conspicuous, group of instinctive activities. But there are other instinctive activities which are performed seldom or only once, and these are in all cases of vital importance to the continuance of the race. Of the many drones which follow the queen-bee in her nuptial flight, one only is successful in mating with her, and that but once in his life. And yet, were the sexual instinct of drones to lapse, even for a single year, the race would be decimated ; and were it to lapse altogether for but a few years, the race would become extinct. The instinct is essential to the preservation and continuance of the race. And many of these instinctive activities thus but seldom performed are adaptive with a nicety which is a continual source of our wonder and admiration. Of such exquisite adaptation we may take, for example, the instinctive activities * of the Yucca moth (Promiba yuccasella). * Described in Kernel's "Natural History of Plants," translated and edited by Prof. Oliver, vol. ii. p. 156. 14 Habit and Instinct. The silvery, straw-coloured insects emerge from their chrysalis-cases just when the large, yellowish-white, bell- shaped flowers of the yucca open, each for a single night. From the anthers of one of these flowers the female moth collects the golden pollen, and kneads the adhesive material into a little pellet, which she holds beneath her head by means of the greatly enlarged bristly palps. Thus laden, she flies off and seeks another flower. Having found one, she pierces with the sharp lancets of her ovipositor the tissue of the pistil, lays her eggs among the ovules, and then, darting to the top of the stigma, stuffs the fertilizing pollen-pellet into its funnel-shaped opening. Now, the visits of the moth are necessary to the plant. It has been experimentally proved that, in the absence of the insects, no pollen can get to the stigma to fertilize the ovules. And the fertilization of the ovules is necessary to the larvae, which in four or five days are hatched from the insect's eggs. It has been ascertained that they feed exclusively on the developing ovules, and in the absence of fertilization the ovules would not develop. Each grub consumes some twenty ovules, and there may be three or four such grubs. But the ovary contains some two hundred ovules. Of these, therefore, say, a hundred are sacrificed to the grubs of that moth, through whose instru- mentality alone the remaining hundred can be fertilized and come to maturity. These marvellously adaptive instinctive activities of the Yucca moth are performed but once in her life, and that without instruction, with no opportunities of learning by imitation, and, apparently, without prevision of what will be the outcome of her behaviour ; for she has no experience of the subsequent fate of the eggs she lays, and cannot be credited with any knowledge of the effect of the pollen upon the ovules. The activities also illustrate what Preliminary Definitions and Illustrations. 15 is by no means infrequent in the more complex instincts, namely, the serial nature of the adaptation. There is a sequence of activities, and the whole sequence is adaptive in its nature. A further example of the serial nature of instinct — of the way in which a number of activities are linked into one elaborately adaptive instinctive chain — may be cited.* A certain beetle of the genus Sitaris (one of the Meloidce, to which belongs the common oil-beetle) lays its eggs at the entrance of the subterranean galleries excavated by a kind of mason bee (Anthophora). From these eggs the larvae are hatched in autumn as active little insects very different from the ordinary type of beetle grub, having six legs each armed with a sharp curved hook. In the winter they become sluggish, but resume their activity in the spring. And when in April the drones of the bee emerge and pass out through the gallery, the Sitaris larvae fasten upon them. There they remain till the nuptial flight of the bees, when, as the insects mate, they pass from the drone to the female bee. Then again they wait their chance. The moment a bee lays an egg, the Sitaris larva springs upon it, and at length breaks its prolonged fast. " Even while the poor mother is carefully fastening up her cell, her mortal enemy is beginning to devour her offspring ; for the egg of the Anthophora serves not only as a raft, but as a repast. The honey, which is enough for either, would be too little for both ; and the Sitaris, therefore, at its first meal, relieves itself from its only rival. After eight days the egg is consumed, and on the empty shell the Sitaris undergoes its first transformation, and makes its appear- ance in a very different form. ... It changes to a white From M. Fabre, as given by Sir John Lubbock in his "Scientific Lectures," 2nd edit. p. 45 (1890). I utilized this example in much the same words in " Animal Life and Intelligence," p. 438. 1 6 Habit and Instinct. fleshy grub, so organized as to float on the surface of the honey, with the mouth beneath and the spiracles above the surface. ... In this state it remains until the honey is consumed," and, after some further metamorphoses, develops into a perfect beetle in August. Here, then, we have a curious and marvellously adaptive life-history, with specialized changes of form and structure, and with correlated modes of activity at each stage. How comes it to perform its varied activities, each step of which is so well adapted to the needs of the stage of life on which it is entering? Parental teaching is altogether excluded, for the parent never sees her offspring ; each individual is isolated from others of its kind, so that imitation is also excluded. The activities cannot be per- formed through intelligence in the common acceptation of the word, for intelligence involves the profiting by individual experience. The larva cannot fasten upon the drone as the result of any previous experience, since it has never done anything of the sort before ; nor can it pass to the female bee because experience has taught it that such a procedure brings with it satisfactory consequences. At no stage of the complex process can intelligence, based upon individual experience, be admitted as a factor. If there be experience, it must be the inherited experience of ancestors who have, each in turn, done much the same. Whether we are justified in speaking of inherited experience will be considered in due time. In any case, the procedure, which is typically instinctive in its nature, has its foun- dations in heredity. We here touch the very quick of the subject. As we shall use the term, the truly instinctive activity is characterized by a certain amount of definiteness which is hereditary, and which is not acquired in the course of individual experience. A habit, as such, is not, in the Preliminary Definitions and Illustrations. 17 restricted acceptation of the term we adopted at the outset, inherited. It is the result of individual acquisition, and is stereotyped by repetition in the course of the experience of the organism which exhibits the habit in question. Now, it is well known that there is a divergence of opinion among biologists as to the answer to be given to the question : Are acquired characters inherited ? For us this question takes the following form : Are acquired habits inherited in the form of congenital instincts? I shall not, at this stage of our inquiries, express any opinion in the matter. That must come after a careful consideration of the evidence. But it is clearly essential that we should so define the terms "habit" and " instinct," and the terms " congenital " and " acquired," as not in any way to forejudge the question ; nay, rather, in such a way as to facilitate a due grasping of the real nature of the question at issue. "Habit" has already been defined; it involves indi- vidual acquisition. An animal does not come into the world with any tendency to perform ready-made habits. The expression " ready-made habits " is indeed contradic- tory, for habits are reached by repetition in the course of experience. If they were ready-made, they would not be called habits ; if they were habits, they could not be ready- made. The definition of the term " instinct " is occupying our attention at present, and we have just said that what is instinctive is characterized by a certain amount of definiteness which is hereditary, and not acquired in the course of individual experience. Instinctive performances are ready-made activities, if the expression be permissible. In other words, they are congenital. Let us, then, use the terms " congenital " and " acquired " in such a way as to be so far as possible mutually exclusive. An activity that is congenital is one the definite performance of which is c 1 8 Habit and Instinct. antecedent to individual experience. Young moorhens, as soon as they are born and have recovered from the shock of birth, can swim with definite accuracy of leg-movements. Here the definiteness is not only congenital, but connate, if we use this latter term for a congenital activity which is definitely performed at or very shortly after birth. On the other hand, young swallows cannot fly at birth ; they are then too immature, and their wings are not yet sufficiently developed. But when they are some three weeks old, and the wings have attained functional size and value, little swallows will fly with considerable if not perfect skill and power. The definiteness is congenital, for it is not acquired by individual experience ; but it is not connate, since it is not exhibited at or shortly afte birth. The term deferred may be applied to such con- genital activities as are performed when the organism has undergone a certain amount of development after birth. The definiteness of the swimming instinct in the moorhen is congenital and connate ; the definiteness of the instinc- tive flight of the swallow is congenital, but deferred. Whether we apply the term " connate " or the term "deferred" to the instincts of fully developed insects— those in the imago stage — depends upon the view we take with regard to the new birth of the insect after its chrysalis sleep. Let us now turn to the activities the definiteness and the peculiar nature of which may be termed acquired in contradistinction to congenital. If we throw to young chicks several caterpillars, some nice, others nasty, the birds will, in the absence of previous experience, seize them without discrimination. But they will soon eat only the nice ones, and leave the others untouched. Two or three lessons of this kind will suffice. After that, if mixed cater- pillars be thrown to them, they will with definiteness and Preliminary Definitions and Illustrations. 19 precision select the nice and ignore the nasty. Experience has introduced a differentiation of response, and that of a perfectly definite nature, and it is to this differentiation, as the result of individual experience, that we may apply the term " acquired." In the animal kingdom there are a great number of skilled activities which are congenital in their definiteness —which have not to be learnt, but are performed with accuracy the first time circumstances and opportunity permit. But in any circus we may see examples of skilled activities which are not congenital, but have been taught to the animals ; and any one who has possessed a clever dog will have seen cases of skilled activities which the animal has learnt for himself through the exercise of his intelligence. It is to such activities as these, the performance of which is the result of individual experience, that the term " acquired " is properly applicable in the sense in which it is here defined. It must not be supposed, however, that what is acquired is always entirely new, if by this is meant something altogether disconnected from any instinctive basis. Quite the reverse. In the great majority of cases, what is ac- quired is a modification of that which is congenital. Of this, perhaps, there is no better example than that afforded by falconry. Here the congenital instincts of certain birds of prey, such as the peregrine falcon, are modified for the purposes of sport ; and the modification is always of the acquired type, since in all cases it is a wild bird — either a young one captured fully fledged, or a nestling (eyas) taken from the eyry — that the falconer takes in hand for special training. One cannot breed falcons for the chase. The training requires care, patience, and skill. The newly captured bird has first to be accustomed to man ; she is lightly hooded, and provided with bells, jesses, swivel, and 2O Habit and Instinct. leash. She is carried about continuously for several days, and late into the night, being constantly stroked with a bird's wing or feather, very lightly at first. Her early training is largely effected in the dark, and she is only unhooded in a dimly lighted room. She is led to associate certain sounds of lips or tongue with feeding ; and at a later stage, certain shouts and tones of voice with the appropriate response. She is trained to the lure — a dead pigeon, or an artificial lure made of leather and feathers or wings of birds and garnished with beefsteak — at first with the leash. Later a light string is attached to the leash, and the falcon is unhooded by an assistant, while " the falconer, standing at a distance of five to ten yards, calls her by shouting and casting out the lure. Gradually day after day the distance is increased, till the hawk will come thirty yards or so without hesitation ; then she may be trusted to fly to the lure at liberty, and by degrees from any distance, say a thousand yards. This accomplished, she should learn to stoop to the lure. Instead of allowing the hawk to seize upon it as she comes up, the falconer should snatch the lure away and let her pass by, and immediately put it out so that she may readily seize it when she turns round to look for it. This should be done at first only once, and then progressively, until she will stoop backwards and forwards at the lure as often as desired. Next she should be entered at her quarry. Should she be intended for rooks or herons, two or more of these birds should be procured. One should be given her from the hand ; then one should be released close to her, and a third at a considerable distance. If she take these keenly, she may be flown at a wild bird. Care must, however, be taken to let her have every possible advantage in her first flights — wind and weather, and the position of the quarry with regard to the surrounding country, must Preliminary Definitions and Illustrations. 21 be considered." With herons and rooks, the falcon is generally kept hooded till the quarry is in sight, when she is at once unhooded and slipped. With game birds the falcon is taught to " wait on " tiU the game is flushed. " A good game hawk in proper flying order goes up at once to a good pitch in the air — the higher she flies the better — and follows her master from field to field, always ready for a stoop when the quarry is sprung. Hawks that have been successfully broken and judiciously worked become wonderfully clever, and soon learn to regulate their flight by the movements of their master." These facts and extracts from Colonel Kadcliff's article on " Falconry " * will serve to show how the behaviour of a trained falcon is an adaptation and modification of the hawk's congenital instincts as a bird of prey. The finished performance is part instinct and part habit. The basis is instinctive and congenital ; the modification is a matter of acquired habit. In domesticated animals that are not only reared, but also bred, by man, there is opportunity for selective mating; and there is opened up the question whether the acquired modification of instinctive behaviour becomes congenital through heredity. Hence in the training of a retriever there may be hereditary effects which are absent in the case of the falcon. It may be objected, however, that the distinction be- tween " congenital " and " acquired " is one that cannot be sustained, since after all an organism can only acquire that for acquiring which it inherits a potentiality; and that we must in any case come back to heredity in the last resort. The Scandinavian jer falcons (F. gyrfalco), for example, will seldom "wait on "well; and merlins will not do it at all. They inherit no faculty for responding to training in this respect. Not only, therefore, is that which * " Encyclopaedia Britannica," 9th edit. vol. ix. 22 Habit and Instinct. is "congenital" dependent on heredity; that which may be acquired is also, at all events, limited by heredity. A somewhat similar objection may be urged on slightly different grounds. A great number of habitual activities and acquired modes of dealing with what is frequently presented in experience result from a gradual limitation of what was at first a varied and exuberant output of activity. 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 activities at first in a somewhat random and indefinite fashion. It tries to effect its object in a number of different ways, many of which are ridiculously inadequate and hopelessly unsuccessful. But gradually it finds that certain efforts are more satisfactory in their results than others ; these are repeated, and thus by successive limitations of the originally numerous and relatively in- definite trials the exuberant efforts are narrowed down to those which bring success ; these become habitual through repetition, a definite mode of procedure results, and we say that it has acquired a specific and well-adapted habit. Now, such acquisition may be regarded, by those who are sceptical as to the validity of any real distinction between what is congenital and what is acquired, as after all only the selection or rejection of these or those among many congenital activities. Suppose, to put the matter in a somewhat different and at the same time a concrete form, that a baby baboon exhibits a number of con- genital limb movements ; each in itself of a relatively definite kind, but without relation to, or co-ordination with, other movements ; and further suppose that, as the result of its individual experience, ten per cent, are selected and co-ordinated so as to form an acquired activity for the carrying out of some specific object, Preliminary Definitions and Illustrations. 23 while the ninety per cent, are, so far as this particular purpose is concerned, suppressed. The habit thus engen- dered arises out of the co-ordination of a small percentage of certain given congenital limb movements. But if the selected ten per cent., no less than the rejected ninety per cent., were originally congenital, and if this selected ten per cent, when duly co-ordinated are said to constitute an acquired habit, what becomes of the supposed radical distinction between " congenital " on the one hand, and " acquired " on the other ? The answer to this objection is, that what we have to fix our attention upon is, not the raw material, but what is manufactured out of it. The activity which results from the co-ordination of the selected ten per cent, of originally unrelated movements is, as such, a new product ; and this product is the result of acquisition, and is not, as a definite co-ordinated activity, congenital. Just as a sculptor carves a statue out of a block of marble, so does acquisition carve an activity out of a mass of given random movements. Or just as an architect builds a cathedral out of an indefinite mass of material by selecting, shaping, and bringing into relation the given parts, so does acquisition build an habitual response out of a given number of indefinite movements by selecting, modifying, and bringing them into relation. It is the definite, co-ordinated, responsive activity that is acquired. Now, there are certain activities which are congenitally definite, which are inherited ready-made, of which the co-ordination is practically perfect at birth. Instance the swimming of a young moorhen when first it enters the water, or the spinning of a cocoon by a silkworm without previous practice or experience. The definite- ness and co-ordination are here not of individual, but of ancestral origin. And there are other activities the definiteness and co-ordination of which are acquired 24 Habit and Instinct. through experience, and are thus not of ancestral, but of individual origin. The one group comprise congenital activities; the other group, acquired activities. And whether the definiteness individually acquired in one generation contributes to the definiteness of ancestral origin in succeeding generations, is the subject of discus- sion among biologists. It must not be supposed that the distinction between what is congenital and what is acquired — a distinction which we are endeavouring to draw with the utmost clear- ness— is invalidated by the fact that there are a great number of activities, such, for example, as the perfected flight of birds, which are of double origin, being in part congenital and in part acquired. Such cases do indeed show that imperfect instincts may be perfected by habit and individual acquisition of skill. But they render the more necessary a careful distinction between the factors which co-operate to produce the ultimate result. And only when the distinction is thus duly emphasized does the question, whether the acquired perfection of one generation tends to lessen the congenital imperfection in the next generation, stand out in its true significance. It is interest- ing here to compare the flight of birds with the flight of insects. In the latter class we find many cases in which the instinctive factor in flight is relatively much more highly developed towards congenital perfection than it is in the former class, at any rate so far as most birds are concerned. The question therefore arises, Is the greater relative perfection in the instinctive flight of some insects due to the inheritance of acquired skill on the part of their ancestors? Or is it due to the fact that there has beei among insects more elimination of those who failed ii congenital power of flight, and hence a survival througl natural selection of those in which the instinctive flight Preliminary Definitions and Illustrations. 25 was better developed? Or is it due to some other cause ? At present we will not attempt to answer such questions as these. We are concerned merely in drawing as clearly as possible a distinction which shall enable us to put the questions in a definite and intelligible form. It is a matter of no small importance accurately to focus the point of such questions. The distinction between that which is congenital and that which is acquired may be further illustrated from a structural point of view. There is an inherited organic mechanism through the possession of "which an animal is fitted to perform certain more or less definite and adaptive activities without learning, with little or no practice (though even in these cases practice helps to make perfect), through no teaching, by no imitation, and without any individual experience on which intelli- gent choice of the best mode of procedure could be based. This is due to what may be termed congenital automatism. On the other hand, there is an organic mechanism which is gradually developed during the individual lifetime, through the due co-ordination and persistent repetition of certain selected activities. These activities, by constant repetition, themselves become automatic as habits. We may term the working of this organic mechanism, which is thus developed during the course of individual life, acquired automatism. The bio- logical question is — Does the acquired automatism of one generation contribute, through inheritance, to the con- genital automatism of the next ? There is still, however, the difficulty suggested but not removed a few pages back, that after all an animal can only acquire that for acquiring which it inherits a potentiality; and that we must in any case, even when 26 Habit and Instinct. individual acquisition is under consideration, come back to heredity in the last resort. This is indubitably true; and it shows that the more or less definite congenital activities do not by any means exhaust the hereditary possibilities. All that an animal owes to heredity may, indeed, be classified under two heads. Under the first head will fall those relatively definite modes of activity which fit it to deal at once, on their first occurrence, with certain essential or frequently recurring conditions of the environment, and this forms the group here termed " congenital." Under the second head will fall the power of dealing with special circumstances as they arise, and this we may term innate capacity. The former may be likened to the inheritance of specific drafts for particular and relatively definite purposes in the conduct of life ; the latter may be likened to the inheritance of a legacy which may be drawn upon for any purpose as need arises. If the need become habitual, the animal may, so to speak, instruct his banker to set aside a specific sum to meet this need as often as it arises. But this arrangement is a purely individual matter, and no wise dictated by the terms of the bequest. In this classification instinctive activities, as we pro- pose to define them, fall under the first head. They display some share of that hereditary definiteness which is characteristic of what we have termed " congenital activi- ties." It must be remembered, however, that, as already mentioned, there is unfortunately no common and accepted agreement so to define the term " instinctive." Professor Wundt, indeed, divides instincts into two classes : (1) those which are congenital, and (2) those which are acquired. So that the distinction we are drawing will by no means be accepted by him and his followers. Where opposing views are in the field, it is necessary to carefully weigh the Preliminary Definitions and Illustrations. 27 advantages and disadvantages of each, and to adopt one or the other. I am quite convinced that, from the biological point of view, it is more satisfactory to restrict the term "instinctive" to those activities which are in greater or less degree congenitally definite, and it is in this sense that the phrase "instinctive activities" will be used in this work. No doubt there are in many cases difficulties, of interpretation ; but these must be met as they arise in the further prosecution of our studies. It may be convenient to indicate the nature of the suggested classification in tabular form : — INHEBITED. Congenitally definite activities, Innate capacity, involving (a) a under which those termed " in- power of association, and (6) stinctive " are comprised. hereditary susceptibilities to pleasure and pain. ACQUIRED. (a) Confirmation, or Particular application of innate (6) Modification, of congenitally capacity; definite or instinctive activi- (a) Occasional and under special ties so as to render them circumstances; habitual by repetition. (6) Frequently repeated, with the (c) Suppression of congenital ac- consequent formation of acquired tivities. habits. We may now sum up what has been advanced in the foregoing discussion, and say that from the biological point of view (and it is from this standpoint alone that they have been so far considered) instincts are congenital, adaptive, and co-ordinated activities of relative complexity, and involving the behaviour of the organism as a whole. They are not characteristic of individuals as such, but are similarly performed by all like members of the same more or less restricted group, under circumstances which are either of frequent recurrence or are vitally essential to the continuance of the race. While they are, broadly speaking, constant in character, they are subject to 28 Habit and Instinct. variation analogous to that found in organic structures. They are often periodic in development and serial in character. They are to be distinguished from habits which owe their definiteness to individual acquisition and the repetition of individual performance. CHAPTEE II. SOME HABITS AND INSTINCTS OF YOUNG BIBDS. MUCH stress has been laid, in the foregoing introductory chapter, on the distinction between the definiteness which is congenital and the definiteness which is in- dividually acquired. There would seem to be certain activities the definite performance of which is antecedent to individual experience, and these were termed in- stinctive. There are others which reach definiteness only through a process of learning, through the exercise of intelligence, or through imitation, their definite per- formance becoming more or less automatic and stereo- typed by individual repetition, and these were termed acquired. So far as our present inquiry is concerned, it is on the definiteness that we must fix our attention. And it is a matter for careful and unprejudiced observation to decide whether the definiteness of behaviour, under given circumstances, is congenital or acquired. This question of fact may, for the present, be kept quite dis- tinct from the question of origin. When some of the facts have been given, it will be time to inquire whether the congenital definiteness is due, on the one hand, to the natural selection of slight congenital variations, or, on the other hand, to the inheritance of the adaptive modifica- tions which result from individual acquisition. But the first thing is to collect facts observed with all possible accuracy. 3