llowing day I was equally unsuccessful in either driving or
tempting him with food into the apparatus. But on April 14 he was so
hungry that he was finally lured in by the use of food. He cautiously
approached the boxes and attempted to climb through on the sides instead
of walking on the floor. It was perfectly evident that he had an
instinctive or an acquired fear of the white surfaces. As the matter was
of prime importance for the success of my work, I inquired of Doctor
Hamilton, and of the men in charge of the cages, for any incident which
might account for this peculiar behavior, and I learned that some three
months earlier, while the animal cages were being whitewashed, Skirrl
had jumped at one of the laborers who was applying a brush to the
framework of one of the cages and had shaken some lime into his eyes. He
was greatly frightened and enraged. Evidently he experienced extreme
discomfort, if not acute pain, and there resulted an association with
whiteness which was quite sufficient to cause him to avoid the freshly
painted apparatus.

Having obtained an adequate explanation of this monkey's peculiar
behavior, I proceeded with my efforts to induce him to work smoothly and
rapidly, and on April 15, by covering the floor with sawdust, I so
diminished the influence of the whiteness as to render the preliminary
training fairly satisfactory. At the end of two more days everything was
going so well that it seemed desirable to begin the regular experiment.

On the morning of April 19, Skirrl was introduced to the apparatus and
given his first series of ten trials on problem 1. This problem demanded
the selection of the first door at the left in any group of open doors.
The procedure was as previously described in that the experimenter
raised the entrance doors of a certain group of boxes, admitted the
animal to the reaction-chamber, punished incorrect choices by confining
the animal for thirty seconds, and rewarded correct choices by raising
the exit door and thus permitting escape and the obtaining of food. The
trials were given in rapid succession, and the total time required for
this first series of ten trials was thirty-five minutes. Skirrl worked
faithfully throughout this interval and exhibited no marked
discouragement. When confined in a box he showed uneasiness and
dissatisfaction by moving about constantly, shaking the doors, and
trying to raise them in order to escape.

For the series of settings used in