54 CALIFORNIA ACADEMY OF SCIENCES. 



which might be adduced. Examples of insular species 

 are especially noteworthy in this regard. 



Mr. Romanes has considered these difficulties at some 

 length in a book which has but just appeared.* The 

 Duke of Argyll in advocating design in nature, made 

 use of the above objections to natural selection, and it 

 is to him that Mr. Romanes addresses his reply. It is 

 hardly necessary to say that the difficulties above stated 

 were not mentioned with a view to show the necessity 

 for design in nature, or some direct supervising power 

 to control the origination of variations, but merely to 

 call attention to the proposition that natural selection, 

 with the help of purely fortuitous variation, does not 

 seem sufficient to account for all structural and specific 

 details. Mr. Romanes, in his reply to the Duke of 

 Argyll, shows how careful it is necessary to be in any 

 particular instance in saying that a character is of no 

 use. Thus the eye must have been of use in its most 

 incipient stages as a black pigment spot whi'ch indicated 

 vaguely the presence of light to the nerves in its vicin- 

 ity. The wing in' its incipient stages must also have 

 been of use, as Mr. Romanes points out. Even if a 

 variation were of no use at first it might be indirectly 

 preserved by natural selection through correlation of 

 growth. " Mr. Darwin, who has paid more attention to 

 this matter than any other writer, has shown, in consid- 

 erable detail, that all the parts of any given organism are 

 so intimately bound together, or so mutually dependent 

 upon each other, that when one part is caused to change 

 by means of natural selection, some other parts are very 

 likely to undergo modification as a consequence." 



The theories which have been put forth to explain 

 variation are, for the most part, very incomplete. Darwin 



* Darwin and After Darwin. I The Darwinian Theory, pp. 350-373. 



