348 EVOLUTION, OLD AND NEW. 



arise " * the variations themselves arising, as we have 

 just seen, from variation. 



Nothing, then, can be clearer from these passages 

 than that natural selection is not a cause of modifica- 

 tion ; while, on the other hand, nothing can be clearer, 

 from a large number of such passages, as, for instance, 

 " natural selection may be effective in giving and keeping 

 colour,"! than that natural selection is an efficient 

 cause ; and in spite of its being expressly declared to 

 be only a "means" of modification, it will be accepted 

 as cause by the great majority of readers. 



Mr. Darwin explains this apparent inconsistency 

 thus: He maintains that though the advantageous 

 modification itself is fortuitous, or without known cause 

 or principle underlying it, yet its becoming the pre- 

 dominant form of the species in which it appears is 

 due to the fact that those animals which have been 

 advantageously modified commonly survive in times 

 of difficulty, while the unmodified individuals perish : 

 offspring therefore is more frequently left by the 

 favourably modified animal, and thus little by little 

 the whole species will come to inherit the modification. 

 Hence the survival of the fittest becomes a means of 

 modification, though it is no cause of variation. 



It will appear more clearly later on how much this 

 amounts to. I will for the present content myself with 

 the following quotation from the late Mr. Gr. H. Lewes 

 in reference to it. Mr. Lewes writes : 



" Mr. Darwin seems to imply that the external con- 

 ditions which cause a variation are to be distinguished 



* ' Origin of Species,' p. 98. t Ibid. p. 66. 



