Evolutionism and Darwinism. 71 



Darwinian hypothesis must be provisional so long 

 as one link in the chain of evidence is wanting ; 

 and so long as all the animals and plants certainly 

 produced by selective breeding from a common 

 stock are fertile, and their progeny are fertile with 

 one another, that link will be wanting. For so 

 long selective breeding will not be proved to be 

 competent to do all that is required of it to pro 

 duce natural species.&quot; So that &quot;it yet remains 

 to be seen,&quot; as lie tersely puts it, in a later work, 

 &quot; how far natural selection suffices for the produc 

 tion of species.&quot; 



According to most eminent authorities, then, 

 the case stands thus : Biology has demonstrated, 

 as matter of historic fact, that life first appeared 

 on our globe in plant-form, that it next emerged 

 in the lower animals, and thence passing by in 

 numerable gradations through beings of increasing 

 complexity of organ and function it culminated 

 in man. There is, therefore, evolution in the 

 organic world, as science has already traced it in 

 the inorganic. But the cause of this evolutionary 

 movement in the history of organisms has not as 

 yet been established ; though it is probable Dar 

 win s natural selection is a part of the cause. In 

 other words, we know that there has been evolu 

 tion, but we are not yet certain how it has been 



