126 WILD TRAITS IN TAME ANIMALS. 



vative principles of the donkey tribe, if such a 

 connection had left no traces in the instinctive 

 habits of the race. 



Perhaps it may be as well to remark that any 

 such fixed mental trait is not the result of accu- 

 mulated experience. It is developed by the 

 ordinary processes of evolution — that is to say, 

 through natural variation and the survival of the 

 fittest — just as is any peculiarity of the bodily 

 frame. In spite of many expressions of opinion 

 to the contrary which one still hears even among 

 well-informed people, there is at present no satis- 

 factory evidence that experience, or anything 

 else, gained during the life of an individual organ- 

 ism is naturally inherited by its progeny. To 

 take the case we are dealing with as an example 

 — the inbred dislike to entering the water which 

 characterises the ass tribe probably originated 

 somewhat in the following way. Among every 

 herd of wild asses there were always individuals 

 which were more timid in certain directions than 

 their fellows, just as in any assembly of human 

 beings — every individual of which differs some- 

 what from his companions both in features and 

 character — there will be some who are naturally 

 more easily alarmed than the rest. 



