spike. This figure does justice to the performance. At the moment the
picture was taken, Skirrl's attention had been attracted by a monkey in
an adjoining cage, and he had momentarily looked up from his task, the
while holding nail and hammer perfectly still.

This test was repeated on various days, and almost uniformly Skirrl
showed intense interest in hammer and nails and used them more or less
persistently in the manner described. Occasionally, apparently for the
sake of variety, he would put the blunt end of the nail on the board and
hammer on the point. Again, he would try persistently to drive the nail
into the cement floor, and once by accident, when hammer and nails were
left in his cage over night, he succeeded in making several holes in the
bottom of his sheet iron water pan. There was no doubting the keen
satisfaction which the animal took in this form of activity.

It is impossible to say that the behavior was not imitative of man, for
Skirrl, along with all of the other monkeys, had had abundant
opportunity to see carpenters working. But this much can be said against
the idea of imitation,--no one of the other animals, not excepting the
orang utan, showed any interest whatever in hammer and nails.
Occasionally they would be played with momentarily or pushed about, but
Sobke, Jimmie, Gertie, Julius, although given several opportunities to
exhibit any ability which they might have to drive nails, made not the
least attempt to do so. Evidently we must either conclude that Skirrl
had a peculiarly strong imitative tendency in this direction, or
instead, a pronounced disposition or instinct for the use of objects as
tools. It would seem fair to speak of it as an instinct for mechanical
activity.

Under this same heading may be described Skirrl's reactions to such
objects as a handsaw, a padlock, and a water faucet. The saw was given
to him in order to test his ability to use it in human fashion, for if
he could so expertly imitate the carpenter driving nails, it seems
likely that he might also imitate the use of the saw.

As a matter of fact, he showed no tendency to use the saw as we do.
Instead, he persistently played with it in various ways, at first using
it as a sort of plane to scrape with, later often rubbing the teeth over
a board so that they cut fairly well, but never as effectively as in the
hands of a man. After two or three days' practice with the saw, Skirrl
hit upon a method which is, as I und