LIMITS OF NATURAL SELECTION. U 



progressively adapt themselves to changes in the 

 environment, that therefore environment must, in 

 some way, be the cause of their variation, and must 

 determine what that variation shall be.i Even could 

 the theory of the mixture of germ-plasms be shown to 

 be the only means of causing variations, we would 

 find that we had made but a single step in advance, 

 and were again confronted by the same problem as 

 to why variations occur along certain lines tending 

 toward the better adaptation of the species. 



There is another point of view, however, from 

 which this whole subject may be regarded. In a 

 mechanical theory of evolution, natural selection 

 cannot be regarded as a cause of evolution. It is 



1 " It is plain that the useful additions which have constituted 

 certain genera, families, orders, etc., what they are, must have been 

 produced as a consequence of the existence of a need for them; or, 

 on the other hand, being created first, they must have sought for use 

 and found it. But what are the relative chances of truth for these 

 two propositions? In the second case, admitting evolution as proved, 

 we perceive that an almost infinite chance exists against any usual 

 amount of variation as observed, producing a structure which shall 

 be fit to survive, in consequence of its superior adaptation to external 

 circumstances. It would be incredible that a blind or undirected 

 variation should not fail, in a vast majority of instances, to produce a 

 single case of the beautiful adaptation to means and ends which we 

 see so abundantly around us. The amount of attempt, failure, and 

 consequent destruction would be preposterously large, and in nowise 

 consistent with the facts of teleology as we behold them." — Proeessok 

 E. D. Cope, Origin of the Fittest. 



