234 ANIMALS UNDERGROUND 



amusement. Another primitive instinct may also have 

 contributed to develop the burrowing habit, namely, 

 that of burying food. Dogs will scratch rudimentary 

 burrows to do this, and there is no doubt that the rats, 

 hamsters, field- voles, and other rodents felt the burrow- 

 ing impulse in this connection. Some tame rats kept in 

 a cage where they could not burrow were recently seen 

 to cover their food up with small pebbles, which they 

 fetched from the floor ; but had it been possible to 

 make a hole and so secrete it, they would no doubt 

 have done so. 





