190 THE PLAY OF ANIMALS. 



could pronounce more than thirty words, making suit- 

 able answers to his master, and articulate clearly all the 

 letters of the alphabet except M, N, and H. 



The examples cited so far do not show us imitation 

 in its real meaning ; they are all the result of accidental 

 offshoots from this powerful instinct, for the actual 

 biological significance of imitative play is not expressed 

 in movements or sounds that are unconnected with the 

 struggle for life, but rather, to put it briefly, in playful 

 self-discipline of young animals in the life habits of 

 their kind. It is sometimes very difficult to place the 

 boundary between what is instinctive or hereditary and 

 what is acquired by imitation. Still, it can hardly be 

 questioned, after all that has been said, that imitative 

 plays are an important adjunct to heredity during the 

 youth of higher animals. The qualities of animals 

 brought up by foster parents furnish a strong experi- 

 mental proof of this. However the adopted animal may 

 be limited in his development by inherited instinct, 

 imitative impulse is still strong enough to bring about 

 some startling modifications. I have not been able to 

 collect many examples illustrative of this in mammals, 

 the class to which I have hitherto confined myself. 



Darwin tells us that "two species of wolves, which 

 had been reared by dogs, learned to bark, as does some- 

 times the jackal," * and it seems quite certain that dogs 

 brought up by cats learn many things from their fos- 

 ter parents. "From one account which I have read 

 there is reason to believe that puppies nursed by cats 

 sometimes learn to lick their feet, and thus to clean 

 their faces; it is at least certain, as I hear from 

 a perfectly trustworthy friend, that some dogs behave in 



* Descent of Man, p. 42. 



