440 'Journal of Comparative Neurology and Psychology. 



not know, and hence lie cannot tell what causes his animals to act as 

 they do. This criticism does not hold against this investigation foi- 

 every animal was given abundant opportunity to manifest his 

 random activities and to exhibit his stock of tricks. That the situ- 

 ations were unfamiliar is evidenced by the animals' repeated failures 

 to learn. That this criticism is less important than it has been made 

 to seem is evidenced by two facts which come out in this study. First, 

 of the two animals which made the best records in the investigation, 

 No. 5 and No. 2, one had been in the garden several years, the 

 other had never been in the garden until June, 1908, when he was 

 shipped there from Cambridge. He had been bought from a dealer 

 and was presumably fresh from the forest. The other fact is that 

 not one of the Park monkeys learned to work the chute unaided, 

 whereas No. 2 did. 



The additional stimulus in the imitation tests was an animal 

 working at the mechanism and food coming from the mechanism. 

 The relative value of these two elements in the imitation-stimulus, 

 this investigation does not show. That in certain cases the presence 

 of the animal was necessary, there is sufficient evidence. The be- 

 havior of No. 6 in the Screen Experiment is a case in point. No. 

 had seen the screen lifted in the Paper Experiment. Immediately 

 thereafter, he had torn the paper and obtained food. He had done 

 this repeatedly and thus had learned that there was food behind 

 the screen. Yet throughout his entire preliminary trials he failed 

 to lift the screen. It was only after he had seen No. 4 get food by 

 liftinff the screen that he did the act himself. 



The case of No. 5 in the Button Experiment illustrates the same 

 thing. She had had a great deal of experience with the slide door. 

 Over and over she had served as the imitatee in the Plug Experi- 

 ment and had eaten more than a dozen bananas which she had 

 gotten after opening the door. Yet she was helpless to get the 

 food when the door was opened by the button. She learned to push 

 the button by watching No. 2 push it. 



On the other hand, there is evidence to show that in certain cases 

 the behavior of the animal unaccompanied by any profitable result 

 is not sufficient to produce imitation. In general, the monkeys did 



