CHAP. X Instinct 159 



apparent similarity in the actions of individuals of the same 

 species must, to a certain extent, be due to incompleteness of 

 observation. 



It is after considering all these definitions that \it. have 

 come to the conclusion that it is convenient to describe all 

 those actions of animals which are not immediately ratio'nal 

 or intelligent as instincts. If we classify an instinct as 

 reflex in cases where the exact chain of internal events is 

 known and use the other qualifications already enumerated, 

 we reach a simplicity and precision of speech that is 

 convenient. 



At the same time all such criteria as adaptiveness and 

 similarity of performance in all the individuals of a species 

 can obviously be applied as they are discovered. 



The essential distinction, we believe, between non- 

 intelligent, that is, instinctive, and intelligent actions, is 

 that non-intelligent actions are performed in virtue of the 

 innate and co-ordinated mechanisms of the organism, 

 whereas for an intelligent action the organism has to do a 

 greater or less amount of the co-ordination for itself. 



3. Examples of Instinct, — If we classify all the actions 

 of animals according to the period of life at which they are 

 performed, we shall find that there are three distinct classes 

 of action which may with convenience be considered 

 separately. 



They are — 

 (i) Those which are performed at birth, or shortly 

 afterwards, as perfectly, or nearly so, as at any 

 future time ; 



(2) Those more varied actions which are characteristic 



of the mature life of any animal ; 



(3) Those which are associated with reproduction. 

 The first of these classes must evidently consist of very 



pure instincts, since the creature cannot be supposed to 

 reason before it has any store of experience. 



The second class is well typified by the marvellous 

 actions of insects, such as ants, bees, and wasps. These 

 ;«aybe instinctive, but it is very probable that many of 

 them are, at least, improved by intelligence. 



