The Wallace-Darwin Correspondence 



11. But colour is more frequent in males, and varia- 

 tions always seem ready for purposes of sexual or other 

 selection. 



12. The fair inference seems to be that given in pro- 

 position 5 of the general argument, viz. that each species 

 and each sex can only be modified by selection just as far 

 as is absolutely necessary, not a step farther. A male, 

 being by structure and habits less exposed to danger and 

 less requiring protection than the female, cannot have 

 more protection given to it by Natural Selection, but a 

 female must have some extra protection to balance the 

 greater danger, and she rapidly acquires it in one way or 

 another. 



13. An objection derived from cases like male fish, 

 which seem to require protection, yet having brighter 

 colours, seems to me of no more weight than is that of 

 the existence of many white and unprotected species of 

 Lep talis to Bates's theory of mimicry, that only one or 

 two species of butterflies perfectly resemble leaves, or that 

 the instincts or habits or colours that seem essential to the 

 preservation of one animal are often totally absent in an 

 allied species. 



Down, Bromley, Kent. September 23, 1868. 



My dear Wallace, — I am very much obliged for all your 

 trouble in writing me your long letter, which I will keep 

 by me and ponder over. To answer it w^ould require at 

 least 200 folio pages! If you could see how often I have 

 rewritten some pages, you would know how anxious I am 

 to arrive as near as I can to the truth. We differ, I think, 

 chiefly from fixing our minds perhaps too closely on differ- 

 ent points, on which we agree : I lay great stress on what 

 I know takes place under domestication : I think we start 

 with different fundamental notions on inheritance. I find 

 p 225 



