100 ROBERT M. YERKES 



poles lay on opposite sides of the box and near the edges of the 

 cage. Doctor Hamilton and the writer were in the cage watch- 

 ing. Julius looked into the box through one end, and seeing 

 the banana, reached for it. He could not obtain it in this way, 

 so he began to bite at the box and to pull at it with all his strength. 

 During the fifteen minutes allowed him, he worked at the box 

 in a great variety of ways, fooling with the locks which had been 

 attached to the hasps as well as with the cross bars and con- 

 tinually reaching in at the one or the other end. He was some- 

 what distracted by the presence of the two observers and attended 

 rather unsatisfactorily to the task in hand. Not once did he 

 touch the poles, and it is doubtful whether he even noticed them. 

 He was not very hungry at this time, and after a few minutes 

 active work he virtually gave up trying to get the food. 



Two days later, on May 3, the box was once more placed in 

 position, this time with a half banana in the middle and a small 

 piece of banana near each open end. The two poles lay on the 

 floor of the cage, each several feet distant from the box. Julius 

 was eager for food. When released he went immediately to the 

 box, reached in and obtained a piece of banana from the end 

 nearer the laboratory. He then looked in and saw the piece 

 near the middle of the box. His next move was to pick up the 

 eight foot pole and push it into the box, but before pushing it 

 all the w^ay through, he stopped and began to pull at the box 

 in various ways. Shortly he returned to the pole and twice 

 thrust it in as far as he could reach. The first time, after thrust- 

 ing it all the way through, he pulled it out and examined the end 

 as though expecting the banana to come out with it. After a 

 third attempt he looked into the box, presumably seeing the 

 banana, then turned a backward somersault, came to the end 

 of the cage, and looked at me. Had it been at all possible, he 

 would have taken me by the hand and led me to the box as 

 a helper. After a few seconds, he returned to the pole, pried 

 the lid of the box with it, then gnawed at the pole. For about 

 five minutes he worked fairly rapidly and steadily, using the 

 poles, pulling, gnawing, and walking about. 



His next move was to go to the opposite end of the box, 

 look in, take the piece of banana which was near the opening, 

 then pick up the second pole, which had not previously been 

 noticed, and after a number of attempts, push it into and through 



