THE DEVELOPMENT OF A YOUNG MONKEY 139 



Fewer data are at hand with respect to the method by which 

 the more complicated reactions were acquired, and indeed so 

 little is known with certainty of the conditions of discrimina- 

 tion and learning in the adult that a discussion of the questions 

 involved here does not seem advisable. There is, however, no 

 evidence to show that the infant monkey ever gained a new 

 activity by imitation. Walking, climbing, leaping, eating, and 

 even the different vocal sounds appeared as instinctive acts 

 which were merely perfected by practice. Dolly's movements 

 sometimes served to draw the baby's attention to some object, 

 but his own reactions to it never seemed to imitate hers. At 

 times also, his responses appeared to be determined by those 

 of the adults, as when Dolly's threatening attitude after some 

 acts of the observer induced fright in him although he had not 

 shown fear at the act itself. His response in such cases was, 

 however, quite different from that of the adult and in no sense 

 imitative. 



In conclusion we may say that this paper is primarily a record 

 of the facts of behavior observed in the development of the 

 young monkey. So little is known with certainty of. the more 

 complex activities of the adults that any explanation of the 

 actions of the infant monkey in terms of adult behavior is 

 extremely difficult. In view of this fact it has seemed best to 

 make little attempt to interpret the data at hand until the 

 psychology of the adults is more thoroughly understood. 



We wish to express our indebtedness to Mr. Donald Mackenzie, 

 to whose patience in the face of the most unfavorable conditions 

 the excellence of the included photographs is due. 



