194 Animal Intelligence 
mediately applied his teeth, though he had before always 
pulled it out with his hand. So again with a plug. It may 
be that there is a special inborn tendency to bite at objects 
pulled unsuccessfully. If not, the act would seem to show 
the presence of the idea ‘get thing out’ or ‘thing come out’ 
and associated with it the impulse to use the teeth. We 
shall see later, however, that in certain other circumstances 
where we should expect ideas to be present and result in 
acts they do not. 
The fact is that those features in the behavior of the 
monkeys in forming associations between the sight of a box 
and the act needed to open it which remind us of learning 
by ideas may also be possibly explained by general activity 
and curiosity, the free use of the hand, and superior quick- 
ness in forming associations of the animal sort. We must 
have recourse to more crucial tests or at least seek evidence 
from a number of different kinds of mental performances. 
The first of these will naturally be their behavior toward 
these same mechanisms after a long time-interval. 
THE PERMANENCE OF ASSOCIATIONS IN THE CASE 
OF MECHANISMS 
My records are too few and in all but one case after too 
short an interval to be decisive on the point of abrupt 
transition from failure to success such as would characterize 
an animal in whose mind arose the idea of a certain part of 
the mechanism as the thing to be attacked or of a certain 
movement as the fit one. The animals are all under ob- 
servation in the Columbia Laboratory, however, and I 
trust that later satisfactory tests may be made. No. 2 
was not included in the tests because he was either unwell 
or had become very shy of the boxes, entering them even 
