Julius the key. He immediately
laid it on the floor opposite him and began biting the box, rolling it
around, and occasionally biting also at the lock and pulling at it.
During these activities he had pulled the box toward his cage. Now he
suddenly looked up to the position where the banana had been suspended
in the box experiment. Evidently the box had suggested to him the
banana. For thirty minutes he struggled with the box almost
continuously, chewing persistently at the hinges, the hasp, or the lock.
Then he took the key in his teeth and tried to push it into one of the
hinges, then into the crack beneath the lid of the box.

Subsequently I allowed him to see me use the key repeatedly, and as a
result, he came to use it himself now and then on the edge of the box,
but he never succeeded in placing it in the lock, and the outcome of the
experiment was total failure on the part of the animal to unfasten the
lock of his own initiative or to learn to use the key by watching me do
so. I did not make any special attempt to teach him to use the key, but
merely gave him opportunity to imitate, and it is by no means impossible
that he would have succeeded had the key been larger and had the
situation required less accurately coordinated movements. However, it is
fair to say that the evidence of the idea of using the key in the lock
was unconvincing. My assistant's observation was, perhaps, misleading in
so far as it suggested that idea. It may and probably was purely by
accident that the animal used the splinter on the padlock.

2. Skirrl, _Pithecus irus_

_Box Stacking Experiment_

The monkey Skirrl was tested by means of the box stacking experiment
much as Julius had been. On August 23, with a carrot suspended six feet
from the floor of the large cage and three boxes in distant corners, the
animal was admitted and his behavior noted.

The boxes, which were made of light, thin material, ranged in size from
one six inches in its several dimensions to one twenty inches long,
thirteen inches wide, and eleven inches deep. Only by using at least two
of these boxes was it possible for the animal to reach the carrot.

Immediately on admission to the cage, Skirrl began to gnaw at the boxes,
trying with all his might to tear them to pieces. After some thirty
minutes of such effort, interrupted by wanderings about the cage and
attempts to get at the other monkeys, he suddenly went to the largest
box of all, set it up on en