The Wallace-Darwin Correspondence 



the two radically distinct kinds of *^ sexual selection." 

 Perhaps ^^ conscious " would be a better word, to which I 

 think you will not object, and I will alter it when I re- 

 publish. I lay no stress on the word ** voluntary.'' 



Sound- and scent-producing organs in males are surely 

 due to '^natural'' or ^^ automatic " as opposed to ** con- 

 scious " selection. If there were gradations in the sounds 

 produced, from mere noises, up to elaborate music — the 

 case would be analogous to that of '^ colours '' and '' orna- 

 ment." Being, however, comparatively simple. Natural 

 Selection, owing to their use as a guide, seems sufficient. 

 The louder sound, heard at a greater distance, would 

 attract or be heard by more females, or it may attract 

 other males and lead to combats for the females, but this 

 would not imply choice in the sense of rejecting a male 

 whose stridulation was a trifle less loud than another's, 

 which is the essence of the theory as applied by you to 

 colour and ornament. But greater general vigour would 

 almost certainly lead to greater volume or persistence of 

 sound, and so the same view will apply to both cases on 

 my theory. 



Thanks for the references you give me. My ignorance of 

 German prevents me supporting my views by the mass of 

 observations continually being made abroad, so I can only 

 advance my own ideas for what they are worth. 



I like Dorking much, but can find no house to suit me, 

 so fear I shall have to move again. 



With best wishes, believe me yours very faithfully, 



Alfred B. Wallacb. 



Dowriy Bechenhanty Kent. September 5, [1877]. 



My dear Wallace, — "Conscious" seems to me much 

 better than *' voluntary." Conscious action, I presume, 

 comes into play when two males fight for a female; but I 



301 



