ADAPTATIONS 



339 



with almost all mammals the egg is very small and without 

 much food yolk. The egg begins its development within the 



FIG. 199. Kangaroo, Macropus rufus, with young in pouch. 



body. It is nourished by the blood of the mother, and after 

 birth the young is cherished by her, and fed by milk secreted 

 by specialized glands of the skin. All these features are 



