156 The Study of Animal Life part n 



be actions in the formation of which intelligence has had a 

 considerable share. 



Now all these activities of an entire organism may be 

 studied from four points of view : — 



(1) Of natural history, or general description, such as 



occurs here and there throughout this work : 



(2) Of physiology, or the analysis of the muscular, 



nervous, and other mechanisms involved ; as 

 treated generally in the last chapter : 



(3) Of psychology, or the investigation into the states 



of consciousness and mental processes concerned ; 

 as sketched in the last chapter : 



(4) Of aetiology, or study of the factors in their origin 



and development. 



We shall first define more carefully than we have yet 

 done what we shall speak of as instinct, then give a few 

 examples, and finally discuss the aetiology of it. 



2. The Careful Usage of the term Instinct. — We have 

 enumerated all the possible varieties of action, and the pos- 

 sible states of consciousness with which they may be asso- 

 ciated have been described in the last chapter. If we retain 

 the use of the term instinct we must explain to what order 

 of activity we shall apply it. In our use of the term we 

 shall not strive after any great precision ; for, as already 

 noted, the difficulty of precision seems to us to be at present 

 insurmountable. In a general way we shall call any action 

 which does not require for its execution any immediate 

 exertion of perceptual inference an instinctive action. Thus 

 a burned child dreads the fire ; such dread and its conse- 

 quent avoidance of fires may, with propriety, be termed 

 instinctive. After the first burn the avoidance will, for a 

 short time, be the result of perceptual inference ; but in 

 perhaps a few days only the avoidance becomes " instinct- 

 ive" ; or it might be called " habitual," as hinted previously. 

 It is, of course, to be understood that an " instinctive " 

 action is not necessarily the result of this " lapsed intelli- 

 gence," as it has been called.' Thus, when a worm 

 wriggles away from a fire it probably has not at any time 

 reasoned out to itself the advantages of such procedure, 



