COSMIC PHILOSOPHY 



ences of environment, when aided by natural 

 selection, has brought about a differentiation 

 of the higher mammals analogous to that which 

 had formerly taken place among the marsupi- 

 als. That six or seven orders of monodelphi- 

 ans should vary in the same direction with six 

 or seven orders of didelphians is no more sur- 

 prising than that twenty-nine kinds of Amer- 

 ican trees should all differ in the same direction 

 from their European congeners. It is certainly 

 far less surprising than would be the simultane- 

 ous loss of a pouch and acquirement of a pla- 

 centa by a host of marsupial genera scattered 

 all over the earth. 



Pursuing the argument a step farther, we may 

 begin to understand, in a general way, even the 

 similarity of the eye of a cuttle-fish to the eye 

 of a vertebrate. Utterly unlike a vertebrate in 

 general structure, — and so remotely akin that 

 for all practical purposes of argument the kin- 

 ship is of no account, — if a cuttle-fish could be 

 shown to possess numerous points of special re- 

 semblance to a vertebrate, the fact would be an 

 obstacle to any theory of the origin of organic 

 forms. But the only special resemblances which 

 are found to exist are those between the eyes 

 and the ears. Now these are organs in which 

 such variations as occur must be in a preeminent 

 degree directly adaptive. The eye, for example, 

 contains an optical apparatus of which the func- 

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