lo THE INFANCY OF ANIMALS 



types. The fawn, the kid, the calf, the foal, the kitten, 

 the puppy, and the young kangaroo are all so many 

 witnesses of this fact. 



These most important differences are seldom realised. 

 Indeed we commonly ignore the early stages of develop- 

 ment in young mammals altogether, as is shown by the 

 fact that we have special names only for such species as 

 have a commercial value, or otherwise force themselves 

 on our attention. Not else are young mammals labelled, 

 so to speak, by special names, and this because they do 

 not manifest themselves till the period of infancy is past. 



The young, then, of the ungulates — that is to say of 

 the " hoofed " animals — deer, oxen, antelopes, sheep and 

 goats, swine, horses, rhinoceroses, camels, and so on, 

 and of the types wherewith we have contrasted them — 

 afford a striking illustration of the impossibility of drawing 

 a hard-and-fast line between pre- and post-natal charac- 

 ters. The eyes of the young rabbit do not open till some 

 days after birth, and similarly the appearance of its fur 

 is a post-natal event. The " leveret " remains within 

 the womb till both these events have been accomplished. 

 The young of the ungulates, similarly, are not born until 

 their development is, relatively, far advanced. In the 

 matter of length of leg indeed they lack little of their 

 final measure ; and they are no less advanced in other 

 ways. 



The reason for these exceptional features is not far to 

 seek. The ungulates are vegetarians, living for the most 

 part in herds, and hence, to obtain a sufficiency of food, 

 they can have no permanent abiding-place, no fixed 

 quarters. Further, they have become the prey of hosts 

 of carnivorous enemies, hosts which else had never 

 come into being. That is to say, the development of the 



