138 ANIMAL LIFE 
utilized. In general, those animals are highest in develop- 
ment, with best means of holding their own in the struggle 
ile | 
! 
Sorter. sald 
Fie. 13,—The altricial nestlings of the Blue jay (Cyanocitia cristata). 
L 
for life, that take best care of their young. The homes 
of animals are elsewhere specially discussed (see Chapter 
