MENTAL LIFE OF MONKEYS AND APES 101 



the box, looking after it and then pulling it out and looking 

 into the box. Having done this he again came to my end of 

 the cage, and from there returned to tr}^ once more with the 

 pole which he had first used. He pushed this pole all the way 

 through, then walked to the other end of the box, looked in 

 and reaching in, obtained the banana which had been pushed 

 far enough along to be within his grasp. Figures 29, 30 and 31 

 of plate V show stages of this process. 



Julius had worked twenty-four minutes with relatively little 

 lost time before succeeding. He had shown almost from the 

 start the idea of using the pole as an instrument, and his sole 

 difficulty was in making the pole serve the desired purpose. 



The experiment was rendered still more crucial on May 5 

 by the placing of the two poles upright in opposite corners of 

 the large cage. For a few minutes after he entered the cage, 

 Julius did not see them, and his time was spent pulling and 

 gnawing at the box. Then he discovered one of the poles, 

 seized it, and pushed it into the box. He tried four times, then 

 went and got the other pole and pushed it into the opposite 

 end of the box. Twice he did this, then he returned to the 

 original pole, bringing the second one with him. He pushed 

 it in beside the first, and as it happened, shoved the banana out 

 of the opposite end of the box. But he did not see this, and 

 only after several seconds when he happened to walk to that 

 end of the box did he discover the banana. The total time 

 until success was fifteen minutes. 



Subsequently the ape became very expert in using the pole 

 to obtain the banana, and often only a minute or two sufficed 

 for success. It was not possible for him to direct the stick 

 very accurately, for when he was in such a position that he 

 could look through the box, he could not work the stick itself. 

 It was, therefore, always a matter of chance whether he obtained 

 the banana immediately or only after a number of trials. 



Although it is possible that the use of the poles in this experi- 

 ment was due to observation of human activities, it seems prob- 

 able in the light of what we know of the natural behavior of the 

 anthropoid apes that Julius would have solved this problem 

 independently of human influence. It was the expectation of 

 the experimenter that the pole would be used to push the banana 

 through the box, but as a matter of fact the ape used it, first 



