ng box. As in the previous problem, he was aided after ten
successive wrong choices. As might have been anticipated, he
persistently entered the end boxes of the groups, and this in some
instances probably would have been kept up for many minutes had not the
experimenter lured him into the right box by slightly raising the exit
door. In the first series, he had to be aided in five of the ten trials.
The total time for the series was forty-five minutes, the total number
of choices, eighty-eight. In the second series, he was aided in four of
the trials. The total time required was seventy-two minutes, and the
total number of choices was seventy-six.

Throughout the first series, Sobke worked hard, but with evidently
increasing dissatisfaction. He clung persistently to his acquired
tendency to choose the end boxes, and after each trial he returned less
willingly to the starting point. Up to this time his attitude toward the
experimenter had been perfectly friendly, if not wholly trustful. But
when on July 21 he was brought into the apparatus for the second series,
he exhibited a wholly new form of behavior, for instead of attending
diligently to the open doors and devoting his energies to trying to find
the right box, he instead, after gazing at them for a few seconds,
turned toward the experimenter and jumped for him savagely, throwing
himself against the wire netting with great force. This was repeated a
number of times during the first two or three trials, and it occurred
less frequently later in the series. Since nothing unusual had happened
outside of the experiment room, the suggested explanation of this sudden
change in attitude and behavior is that the monkey resented and blamed
on the experimenter the difficulty which he was having in obtaining
food.

From this time on until the end of my work, Sobke was always savage and
both in and out of the apparatus he was constantly on the watch for an
opportunity to spring upon me. Previously, it had been possible for me
to coax him into the apparatus by offering him food and to return him to
his cage by walking after him. But on and after the twenty-first of
July, it was impossible for me to approach him without extreme risk of
being bitten.

Doctor Hamilton when told of this behavior, reported that several times
monkeys have shown resentment toward him when they were having trouble
in the experiment. I therefore feel fairly confident that I have not
misinterpreted Sobk