THE TRIUMPH OF THE MAMMALS 99 



of her blood." The kangaroo mother has not got 

 these blood-vessels. She cannot nourish the body of 

 her young with her blood. She goes a step beyond 

 the Platypus, it is true. She hatches the eggs inside 

 her own body; but when they are hatched — when all 

 the nourishment in the Qgg has been used up — she 

 can do no more in her womb. The very tiny and 

 imperfect young are born. Naturally, they would die 

 if left to themselves. She takes them in her mouth, 

 puts them in her pouch, and there they hang on to 

 her breasts (which are low down) until they are fully 

 formed. 



Here is the next stage in the formation of a 

 mammal; and we are much obliged to Australia 

 for preserving these ancient curiosities for us. The 

 higher mammals are so much more perfect in their 

 arrangement for the birth of the young that these 

 primitive mammals would not be able to stand compe- 

 tition with them. The waters of Australia kept them 

 away. For science the Platypus and the kangaroo 

 are extremely interesting; and there is a third type 

 which is in some respects between the two. We do 

 not say that they are the ancestors of the mammals, 

 but they are precious remnants of the great family of 

 early mammals of the Age of Reptiles, and they beau- 

 tifully illustrate the evolution of the mammal body. 



During the Age of Reptiles, as we saw, their higher 

 organization was of no service, and they lived an 

 obscure, hunted life and made little progress. Then 



