236 Animal Intelligence 



caused the smoker to blow in his face. He was often given 

 a lighted cigar or cigarette to test him for imitation. He 

 formed the habit of rubbing it on his back. After doing so 

 he would scratch himself with great vigor and zest. He 

 came to do this always when the proper object was given 

 him. I have recounted all this to show that the monkey 

 enjoyed scratching himself. Yet he apparently never 

 scratched himself except in response to some sensory stimulus. 

 He was apparently incapable of thinking ' scratch ' and so 

 doing. Yet the act was quite capable of association with 

 circumstances with which as a matter of hereditary organi- 

 zation it had no connection. For by taking a certain well- 

 defined position in front of his cage and feeding him when- 

 ever he did scratch himself I got him to always scratch 

 within a few seconds after I took that position. 



GENERAL MENTAL DEVELOPMENT OF THE 



MONKEYS 



It is to be hoped that the growing recognition of the worth 

 of comparative and genetic studies will lead to investiga- 

 tions of the mental make-up of other species of monkeys, and 

 to the careful overhauling of the work done so far, including 

 these rather fragmentary studies of mine. Work with three 

 monkeys of one species, especially when no general body of 

 phenomena, such as one has at hand in the case of domestic 

 animals, can be used as a means of comparison, must neces- 

 sarily be of limited application in all its details and of inse- 

 cure application even in its general features. What I shall 

 say concerning the advance in the mental development 

 of the monkeys over that of other mammals may then be 

 in strictness true of only my three subjects, and it may be 

 left to the judgment of individuals to extend my conclusions 



