s given as a reward. After the first trial in this series, in which
Julius repeatedly entered the first box at the left, that is box 7,
there was but slight tendency to reenter the first box at the left of
the group. Instead, Julius developed the method of moving box by box
toward the right end of the group. The choices were made promptly, and
their systematic character enabled the animal to obtain his reward
fairly quickly, in spite of the large number of mistakes.

In the second series, the orang utan developed the interesting trick of
quickly dodging out of the wrong box before the experimenter could lower
the door behind him. This he did only after having been punished for
many wrong choices to the point of discouragement. The trick was easily
broken up by the sudden lowering of the entrance door as soon as he had
passed under it.

There appeared on May 21 an unfavorable physical condition which
manifested itself, first of all through the eyes which appeared dull and
bloodshot. On the following day they were inflamed and the lids nearly
closed. Julius refused to eat, and experimentation was impossible. Until
June 2 careful treatment and regulation of diet was necessary. He passed
through what at the time seemed a rather startling condition, but
rapidly regained his usual good health, and on June 3, although somewhat
weak and listless, he again worked fairly steadily.

Since it was now possible to lock the doors and confine the animal for
any desired period, on June 5 the interval of punishment was made sixty
seconds, and a liberal quantity of banana, beet, or carrot was offered
as reward. No increase in the number of successful choices appeared, and
Julius showed discouragement. Sawdust had been strewn on the floor, and
in the intervals between trials as well as during confinement in wrong
boxes, he took to playing with the sawdust. He would take it up in one
hand and pour it from hand to hand until all had slipped through his
fingers, then he would scrape together another handful and go through
the same process. Often he became so intent on this form of amusement
that even when the exit door was raised, he would not immediately go to
get the food.

The reactive tendencies which appeared in the work on problem 2 will now
be presented in order, since I shall have to refer to them repeatedly,
and the list will be more useful to the reader at this point than at the
conclusion of the presentation of daily results. Th