138 



ANIMAL LIFE 



utilized. In general, those animals are highest in develop- 

 ment, with best means of holding their own in the struggle 



\V <^pr 

 FIG. 73. The altricial nestlings of the Canada jay (Perisweus canadensis). 



for life, that take best care of their young. The homes 

 of animals are elsewhere specially discussed (see Chapter 



