and allowed to watch me place the boxes
in proper position. He then climbed up and obtained the desired food.
After the bait had been renewed and the boxes displaced, he immediately
tried to use the larger one, then he reached for the small one as though
to use both together. But the impulse died out and he turned again to
the larger box as usual, standing it on end, and persistently trying to
balance himself on it. Nothing else of special interest happened during
the interval of unaided effort.

Similarly, I placed the boxes for the ape on April 19, allowed him to
get the banana and then gave him opportunity to try for himself after
the boxes had been displaced. This time he immediately reached for the
smaller box and moved it about a little, thus indicating a new
association. He next turned to the larger box and worked with it
persistently. Later, he once more worked with the smaller box in an
unusual manner. He repeatedly stood on it, but made no attempt to lift
it or to place it on the larger box. Clearly the usually neglected
smaller box had become associated with the satisfaction of obtaining the
banana. The same method was carried out on April 20. As I placed the
boxes in position beneath the banana, Julius watched with unusual
intentness, and when it came his turn to try to obtain the food by the
use of the boxes, he began at once to work with the smaller box, but as
on April 19, he soon abandoned it and turned to the other. While I was
making note of this particular feature of his behavior, he suddenly
seized the smaller box by two corners with his hands and by one edge
with his teeth, and after a few attempts placed it on top of the larger
box, climbed up, and obtained the banana.

Because of bad weather on April 21, the next test was made on April 22,
with everything as usual. Unaided, the ape was given an opportunity to
obtain the coveted reward, while I stood ready to obtain records of his
behavior with my camera. He wasted no time, but piled the smaller box on
top of the larger one immediately, and obtained his reward. As soon as
opportunity was offered, he repeated the performance. The same thing
happened on April 23 and several succeeding dates.

Julius had got the idea, and the only further improvement possible was
in skill in manipulating the boxes.

One of the curious performances which appeared during the imitative
period is pictured in figure 26, plate V, where the ape is seen lifting
the small