CH. XLI. NATURAL SELECTION. 49 



derful harmony of nature which keeps every part, however 

 insignificant, exactly fitted to do its work in the one gre.Mt 

 scheme of creation. 



Difficulties in Natural History explained by 

 Natural Selection. And now, if we adopt Mr. Darwin's 

 explanation, you will see how St.-Hilaire and Cuvier could 

 both be right when the former said that all animals are formed 

 on one plan, and the latter, that each part of an animal is 

 exactly fitted to work harmoniously with the rest of its body. 

 For if animals have been gradually altered the one from the 

 other, it is natural they should all be made on one plan ; 

 as, for instance, if the ancestor of the bat, millions of years 

 ago, was also the ancestor of those animals out of which the 

 horse has come, then the bones of the bat's wing may well 

 be similar to those of the horse ; while, on the other hand, 

 if no variation can become fixed, and develop into import- 

 ant parts or organs unless it is useful, it is clear that all the 

 parts of an animal must have been gradually modified so as 

 to fit each other and to work in the best possible way for 

 its well-being. Again, it explains why the living animals in a 

 country should be of the same class as those found fossil in 

 the earth, though slightly different from them. For if in 

 Australia the ancestors were pouched animals, it must take 

 a very long time before their descendants could be anything 

 else, although they might begin to differ in many points of a 

 less fundamental nature. 



Lastly, it enables us to understand why we find the lower 

 forms of life in the oldest rocks, and why gradually, as 

 animals multiplied and the struggle for life became greater, 

 more and more complicated forms should arise, from the 

 improvement and inheritance of specially useful parts ; so 

 that the higher animals have a greater number of different 

 parts to perform different actions, just as a civilised country 



