328 



NA TURE 



[February 3, 1898 



form of an uneasy tendency to be up and doing, perhaps due to 

 ill-defined nervous thrills from the organs of locomotion which 

 are in need of exercise. The sensory stimuli are presumably 

 afforded by the contact of the feet with the ground, or with the 

 water, and by the pressure of the air on the wing-surfaces. It 

 is a curious fact that, if young ducklings be placed on a cold 

 and slippery surface, such as that of a japanned tea-tray, they 

 execute rapid scrambling movements, suggestive of attempts to 

 swim, which I have never seen in chicks, pheasants, or other 

 land-birds. 



It will not be supposed that I claim for perfected locomotion, 

 so admirably exemplified in the graceful and powerful flight of 

 birds, an origin that is wholly instinctive and unmodified by the 

 teachings of experience. Here as elsewhere instinct seems to 

 form the ground-plan of activities which intelligence moulds to 

 finer and more delicate issues. This is the congenital basis on 

 which is built the perfected superstructure. And if our oppor- 

 tunities for observation, and our methods of analysis, were equal 

 to the task, we should be able to distinguish, in the develop- 

 ment of behaviour, the congenital outline from the shading and 

 detail which are gradually filled in by the pencil of experience. 



The difficulties which reiider this analysis at the best im- 

 perfect are, therefore, twofold. In the first place, intelligence 

 begins almost at once to exercise its modifying influence ; and 

 in the second place, many instinctive traits do not appear until 

 long after intelligence has begun its work. Much of the intel- 

 ligent detail of the living picture is filled in before the instinctive 

 outlines are complete. The term " deferred instincts " has been 

 applied to those congenital modes of procedure which are 

 relatively late in development. The chick does not begin to 

 scratch the ground, in the manner characteristic of rasorial 

 birds, till it is four or five days old ; nor does it perform the 

 operation of sand-washing till some days later ; the moorhen 

 does not begin to flick its tail till it is about four weeks old ; the 

 jay does not perform the complex evolutions of the bath till it 

 has left the nest and felt its legs, when the stimulus of water to 

 the feet, and then the breast, seems to start a train of acts 

 which, taken as a whole, are of a remarkably definite type. 

 The development of the reproductive organs brings with it, 

 apart from the act of pairing, a number of associated modes of 

 behaviour — nest-building, incubation, song, dance, display, and 

 strange aerial evolutions — which are presumably in large degree 

 instinctive, though of this we need more definite evidence. For 

 it is difficult to estimate with any approach to accuracy the 

 influence of imitation. There seems to be no reason for doubting 

 that, when an animal grows up in the society of its kind, it is 

 affected by what we may term the traditions of its species, and 

 falls into the ways of its fellows, its imitative tendency being 

 subtly influenced by their daily doings. The social animal 

 bears the impress of the conditions of its peculiar nurture. Its 

 behaviour is in some degree plastic, and imitation helps it to 

 conform to the social mould. 



The exact range and nature of the instinctive outline, inde- 

 pendently of those modifications of plan which are due to the 

 inherent plasticity of the organism, are, therefore, hard to 

 determine. And if, as we have good grounds for believing, the 

 growth of intelligent plasticity, in any given race, is associated 

 with a disintegration of the instinctive plan, congenital adapta- 

 tion being superseded by an accommodation of a more indi- 

 vidualistic type, to meet the needs of a more varied and com- 

 plex environment, the problems with which we have to deal 

 assume an intricacy which at present defies our most subtle 

 analysis. 



We must now turn to the consideration of the manner in 

 which individual accommodation through the exercise of intelli- 

 gence under the teachings of experience, is brought about. 

 And it will be well to pave the way by adducing certain facts 

 of observation. 



Although the pecking of a young chick under the joint in- 

 fluence of hunger and the sight of a small near object, would seem 

 to belong to the instinctive type, the selection of appropriate 

 food, apart from the natural guidance of the hen, seems to be 

 mainly determined by individual experience. There is no 

 evidence that the little bird comes into the world with anything 

 like hereditary knowledge of good and evil in things eatable. 

 Distasteful objects are seized with not less readiness than natural 

 food such as grain, seeds, and grubs. The conspicuous colours 

 of certain nasty caterpillars do not appeal to any inherited 

 power of immediate discrimination so as to save the bird from 

 bitter experience. They seem rather to serve the purpose of 



NO. 1475, VOL. 57] 



rendering future avoidance, in the light of this bitter experi- 

 ence, more ready, rapid, and certain. Bees and wasps are 

 seized with neither more nor less signs of fear than large flies or 

 palatable insects. Nor does there seem to be any evidence of 

 the hereditary recognition of natural enemies as objects of dread. 

 Pheasants and partridges showed no sign of alarm when my 

 dog quietly entered the room in which they were kept. When 

 allowed to come to closer quarters, they impudently pecked at 

 his claws. A two days chick tried to nestle down under him. 

 Other chicks took no notice of a cat, exhibiting a complete in- 

 difference which was not reciprocated. A moorhen several 

 weeks old would not suffer my fox-terrier to come near his own 

 breakfast of sopped biscuit, but drove him away with angry 

 pecks until the higher powers supervened. 



It is not, of course, to be inferred from these observations 

 that such an emotion as fear has no place in the hereditary 

 scheme, or that the associated acts of hiding, crouching, or 

 efforts to escape do not belong to the instinctive type. I have 

 seen little pheasants struck motionless, plovers crouch, and 

 moorhens scatter at the sound of a loud chord on the 

 violin, or of a shrill whistle. A white stoneware jug, placed ir> 

 their run, caused hours of uneasiness to a group of birds, includ- 

 ing several species. But there is no evidence that, in such cases, 

 anything like hereditary experience defines those objects which 

 shall excite the emotion. It is the unusual and unfamiliar ob- 

 ject, especially after some days of active life amid surroundings^ 

 to which they have grown accustomed ; it is the sudden sound, 

 such as a sneeze, or rapid movement, as when a ball of paper is 

 rolled towards them, that evokes the emotion. Hence, if the 

 parent birds are absent, the stealthy approach of a cat causes n» 

 terror in the breasts of inexperienced fledglings. But when 

 she leaps, and perhaps seizes one for her prey, the rest scatter in 

 alarm, and for them the sight of a cat has in the future a new 

 meaning. 



The elementary emotions of fear, anger, and so forth, stand 

 in a peculiar and special relationship to instinct. At first sight 

 they seem to take rank with the internal impulses which are the 

 part-determinants of instinctive behaviour. The crouching of a 

 frightened plover or landrail, the dive of a scared moorhen, 

 result partly from the external stimulus afforded by the terrifying 

 object, partly from the emotional state which that object calls 

 forth. But in their primary genesis I am disposed — here follow- 

 ing to some length the lead of Prof. Wm. James— to assign to 

 such emotioiis an origin similar to that of the consciousness 

 which follows on the execution of the instinctive act. As- 

 suming, as before, that consciousness owes its genesis to messages 

 which reach the sensorium through incoming nerve-channels, 

 the sensory stimuli, afforded, let us say, by the sight of a terrify- 

 ing object, do not seem, in the absence of inherited experience, 

 capable of supplying messages which in themselves are sufficient 

 to generate the emotion of fear. Now, the well-known ac- 

 companiments of such an emotional state are disturbances of the 

 heart-beat, the respiratory rhythm, the digestive processes, the 

 action of the glands, and the tone of the minute blood-vessels 

 throughout the body. And all these effects are unquestionably 

 produced by outgoing discharges from the central nervous 

 system. But they Axefelt as the result of incoming messages, 

 like vague and disquieting rumours, transmitted to the central 

 office from the fluttering heart, the irregular breathing, the sink- 

 ing stomach, and the disturbed circulation. Is it not therefore 

 reasonable to suppose that the emotion, in its primary genesis, 

 is due to the effect on the sensorium of these disquieting 

 messages ? If this be admitted as a working hypothesis— and it 

 cannot at present claim to be more than this — we reach, at any 

 rate, a consistent scheme. As primary messages to the central 

 office of consciousness we have, on the one hand, those due to 

 stimuli of the special senses, and, on the other hand, those re- 

 sulting from the conditions of the bodily organs, taking the form 

 of a felt craving for their appropriate exercise. These co- 

 operate to throw the brain into a state of unstable equilibrium 

 or neural strain, which is relieved by outgoing streams of 

 nervous energy. And these in turn fall into two groups ; first, 

 an orderly set of discharges to the voluntary muscles concerned 

 in behaviour, and secondly, a more diffuse group of discharges 

 to the heart, respiratory apparatus, digestive organs, glands, and 

 vascular network. In so far as these are outgoing discharges, 

 they do not directly affect consciousness. But there quickly re- 

 turns upon the sensorium an orderly group of incoming messages 

 from the motor apparatus concerned in instinctive behaviour, 

 and a more indefinite group from the heart and other visceral 



