110 DARWINISM STATED BT DARWIN HIMSELF. 



places in the polity of nature, and so be enabled to in- 

 crease in numbers. 



The advantage of diversification of struct- 

 ure in the inhabitants of the same region is, 

 in fact, the same as that of the physiological division of 

 labor in the organs pf the same individual body — a sub- 

 ject so well elucidated by Milne-Edwards. No physiolo- 

 gist doubts that a stomach adapted to digest vegetable 

 matter alone, or flesh alone, draws most nutriment from 

 these substances. So in the general economy of any land, 

 the more widely and perfectly the animals and plants are 

 diversified for different habits of life, so will a greater 

 number of individuals be capable of there supporting 

 themselves. A set of animals, with their organization 

 but little diversified, could hardly compete with a set more 

 perfectly diversified in structure. It may be doubted, 

 for instance, whether the Australian marsupials, which 

 are divided into groups differing but little from each 

 other, and feebly representing, as Mr. Waterhouse and 

 others have remarked, our carnivorous, ruminant, and 

 rodent mammals, could successfully compete with these 

 well-developed orders. In the Australian mammals, we 

 see the process of diversification in an early and incom- 

 plete stage of development. 



EVOLUTION OF THE HUMAN EYE. 



Origin of To suppose that the eye with all its inim- 



Species, itable contrivances for adjusting the focus 

 ^^°^ ' ■ to different distances, for admitting different 

 amounts of light, and for the correction of spherical and 

 chromatic aberration, could have been formed by natural 

 selection, seems, I freely confess, absurd in the highest 



