90 CRITICISMS ON " THE ORIGIN OF SPECIES " ni 



assumes no special tendency of organisms to give 

 rise to useful varieties, and knows nothing of needs 

 of development, or necessity of perfection. What 

 he says is, in substance : All organisms vary. It 

 is in the highest degree improbable that any given 

 variety should have exactly the same relations to 

 surrounding conditions as the parent stock. In 

 that case it is either better fitted (when the varia- 

 tion may be called useful), or worse fitted, to cope 

 with them. If better, it will tend to supplant the 

 parent stock ; if worse, it will tend to be extin- 

 guished by the parent stock. 



If (as is hardly conceivable) the new variety is 

 so perfectly adapted to the conditions that no 

 improvement upon it is possible, it will persist, 

 because, though it does not cease to vary, the 

 varieties will be inferior to itself. 



If, as is more probable, the new variety is by no 

 means perfectly adapted to its conditions, but only 

 fairly well adapted to them, it will persist, so long 

 as none of the varieties which it throws off are 

 better adapted than itself. 



On the other hand, as soon as it varies in a 

 useful way, i.e. when the variation is such as to 

 adapt it more perfectly to its conditions, the fresh 

 variety will tend to supplant the former. 



So far from a gradual progress towards perfection 

 forming any necessary part of the Darwinian 

 creed, it appears to us that it is perfectly consistent 

 with indefinite persistence in one state, or with 



