MANIFESTED IN THE ANIMAL KINGDOM 89 



in a very short space of time, but their energy is not 

 enduring. They will usually outrun a herbivore in a 

 short burst of speed, but they cannot stand the distance. 

 When at liberty they expend their energy in seeking and 

 stalking their prey, and they often experience long fasts 

 between meals. In captivity they have little opportunity 

 or necessity for exercise, and they are well and regularly 

 fed. Their meals are of meat, which is one of the richest 

 in proteids of all foods. The herbivorous animals will 

 be little better fed in captivity than in a wild state, and 

 the difference will lie chiefly in the amount of the exercise. 



" The most notorious case of an animal not breeding 

 in captivity is that of the elephant. Elephants are kept 

 in large numbers in their native Indian home, live to 

 old age, and are vigorous enough for the severest labour, 

 yet, with few exceptions, they have never been known 

 even to couple, though both males and females have their 

 proper periodical seasons." l In this case failure to 

 breed seems to be mainly due to failure to couple, rather 

 than to actual sterility. With such unwieldy animals 

 coupling is a serious business, not to be lightly undertaken, 

 a fact of which the animals themselves are probably not 

 unconscious. Therefore it is probable that the failure 

 to couple is mainly due to lack of opportunity under 

 favourable conditions. It may, of course, be due to some 

 failure of the sexual instinct. 



Elephants in India are usually fed partly on a corn 

 diet, and between a wild elephant and one in captivity 

 there is a difference very similar to that between a grass- 

 fed and a corn-fed horse. And when the elephant is 

 treated in the same manner as a grass-fed horse, it also 

 becomes more fertile. Proceeding " a little eastward 

 to Ava, we hear from Mr. Crawfurd that their ' breeding 



1 Variation of Animals and Plants under Domestication, ehap. xviii. 



