THE GRAY SQUIRREL 405 



The Reproductive System. The organs of reproduction in 

 the male consist of oval spermaries (Fig. 213, 48) and & penis 

 (Fig. 213, 54) ; in the female, of ovaries with their oviducts. 



Development. The squirrel is viviparous. The ovum pro- 

 duced in the ovary passes into the oviduct, where it becomes 

 fertilized, and in that portion of the oviduct called the uterus 

 it develops into the young squirrel. The young is born in a 

 condition resembling the adult, though the hair is not com- 

 letely formed and the eyes are closed. In the southern states 

 the first of two or three litters appears early in March, and 

 four young are usually produced at a birth. The nest is 

 usually in a hollow tree in the colder portions of its range, 

 and exposed on the branches in the warmer regions. The 

 female keeps the male away from the young during their 

 period of infancy, and feeds them on milk, which is secreted 

 by the mammary glands on her ventral surface. 



Relation to Environment. When the young have been 

 reared, the winter nest in a hollow tree is usually deserted 

 for a structure of leaves and twigs built high among the 

 branches of a tree. This outside nest is occupied (at least in 

 the colder regions) throughout the summer. 



The food of the squirrel in the spring consists largely of 

 buds, especially of the maple and elm. In the summer, fungi 

 and berries are added to the bill of fare, and in the fall nuts 

 form a large part of the diet. The gray squirrel has been 

 accused of varying its vegetable diet with such animal food 

 as the young and the eggs of song-birds, but it is probably 

 not as frequent an offender as the red squirrel, whose bad 

 habits in this respect are well known. The nuts of autumn 

 are gathered and stored in secret places beneath stumps and 

 in hollow trees, and many are separately buried in the ground. 

 Some observers are inclined to think that their sense of smell 

 guides them to the buried food, though it is doubtful if these 

 individual hoards are always located again. 



