^'\ 



^ 



■'^t 



* 



I 



y- - 



ret>- 





betwi 



6(1 



liie i^y 



wei 



ntignous 



.■^n 



.--'';.) 





« 





I 



oii« 



dby 



ft 



1,r?i 



:^^ 



it - ' , 



Cii. XL.] 



JMIGEATIOX OF SPECIES. 



401 



some 



palatable food amongst the various herbs and trees of the 

 primeval wilderness, are unable to subsist on the olive, the 

 vine, the wheat, and a few trees and grasses favoured by 

 man. In addition, therefore, to his direct intervention, man, 

 in this case, operates indirectly to impede the dissemination 

 of plants, bj intercepting the migration of animals, many of 

 which would otherwise have been active in transporting seeds 

 from one province to another. 



We shall see in the sequel that species belonging to genera, 

 previously foreign to the province into which they are intro- 



make 



e 



genera and species which are indigenous, a fact which has a 



im 



^ ^ ^ — -J- 



It is unfavourable to the doctrine that new species have been 

 specially created in each station as best fitted of all possible 

 organisms to flourish there, while it agrees perfectly with the 

 view that new lands or stations are first colonised by such 

 plants and animals as can gain access to them without 

 violating the fixed and immutable laws whic! 

 diffusion of species. Once introduced, they 

 adapted by variation and selection to all the peculiar condi- 

 tions of the new region ; but they may still be less fitted for 



the 



maj 



and 



may 



barriers 



same 



in the battle of *life. 





VOL. II. 



D D 



