IS THE THEORY OF SELECTION SUFFICIENT? 157 



Standpoint of Physiology and the Theory of Descent." 

 (Das Unbewusste vom Standpunkt der Physiologie and 

 Descendenztheorie),*" has again recently observed that 

 the truth of the doctrine of Descent is independent of the 

 bearings and adequacy of the Darwinian theory. 



" This circumstance,'' he says, " is misunderstood by 

 the majority of Darwin's opponents; when they adduce 

 arguments for the inadequacy of natural selection in the 

 struggle for life, they usually fancy they have adduced 

 just as many arguments against the reliability of the 

 theory of Descent. But the two have no direct connec- 

 tion with one another; for it might be possible that Dar- 

 win's theory of natural, selection was absolutely false and 

 unserviceable, and the doctrine of derivation true not- 

 withstanding; that only the causal medium of the der- 

 ivation of one species from another was different from 

 that stated by Darwin. Similarly, it might be possible 

 that, although the immediate causes of transition discov- 

 ered by Darwin were partially effective, — on the other 

 hand, transitional phenomena existed which could not as 

 yet be explained by this hypothesis; that this therefore 

 required either an auxiliary hypothesis supplementing 

 that of Darwin, or even a co-ordinating principle of ex- 

 planation, as little discovered naw as was the Darwinian 

 theory twenty years ago. Such imperfect knowledge of 

 the causes operating in the transition of one form into 

 the other, can prejudice the general truth of the doctrine 

 of Descent as little as the absence of intermediate forms, 

 or the uncertainty, still existing in many cases, of the 

 derivation of any given form. If even fn former times, 

 when all knowledge of the causes by which tfansition 

 is effected was still wanting, the doctrine of Derivation 



