OF WILD ANIMALS 81 



In the year 1915 Dr. Robert M. Yerkes, of Harvard Uni- 

 versity, conducted at Montecito, southern California, in a com- 

 fortable primate laboratory, six months of continuous and dili- 

 gent experiments on the behavior of orang-utans and monkeys. 

 His report, published under the title of "The Mental Life of 

 Monkeys and Apes: A Study of Ideational Behavior," is a 

 document of much interest and value. Dr. Yerkes' use of the 

 orang-utan as a subject was a decided step forward in the study 

 of "animal behavior" in America. 



