WILD ANIMALS IN CAPTIVITY 
wear down, and unless they were reproduced and con- 
tinually growing the animals would die from starvation. 
It is not my intention to enter into the anatomical 
details of the very remarkable conditions and various forms 
of teeth structure found in the animal world, but simply 
to state facts, taking for example the teeth of the beaver. 
This rodent s food consists of the bark of trees and other 
vegetable substances, it will, however, sometimes gnaw 
bones and horns. If by accident or otherwise one of the 
four incisor teeth should be broken, the tooth on the 
opposite jaw would continue to grow, and having nothing 
to oppose its growth would become so elongated as to 
cause the animal much difficulty in obtaining food ; in fact, 
many rodents have been found dead from this cause. I 
have from time to time been compelled, in order to save 
the lives of the animals, to capture some of the beavers in 
the Gardens and cut off the elongated incisor teeth. 
It happens unfortunately that, in order to prevent 
animals of this class gnawing their way out of their 
enclosures and making their escape, I am obliged to 
employ iron, and they in attempting to bite and gnaw 
this metal break their teeth, consequently in course of 
time the opposing teeth become too long to be useful, and 
therefore it is found necessary to cut them shorter to 
make them even, so as to be used as before. This opera- 
tion is by no means an easy one. In the first place, to 
hold an animal of this strength and form is a very difficult 
matter. I have found it necessary to confine the animal 
in a strong net, two ]3ersons being required to hold it in 
order to prevent it struggling. When this preliminary 
business is arranged, the operation is gone through. The 
enamel of the front of the incisor teeth is so excessively 
hard that it requires a very sharp three-cornered steel file 
to make any impression. As soon, however, as the enamel 
106 
