134 THE VALUE OP COLOUR 



cases, been rendered brilliant so as to mimic some other 

 species, and thus escape danger. But can you account for 

 the males not having been rendered equally brilliant and 

 equally protected? Although it may be most for the 

 welfare of the species that the female should be protected, 

 yet it would be some advantage, certainly no disadvantage, 

 for the unfortunate male to enjoy an equal immunity from 

 danger. For my part, I should say that the female alone 

 had happened to vary in the right manner, and that the 

 beneficial variations had been transmitted to the same sex 

 alone. Believing in this, I can see no improbability (but 

 from analogy of domestic animals a strong probability) that 

 variations leading to beauty must often have occurred in the 

 males alone, and been transmitted to that sex alone. Thus I 

 should account in many cases for the greater beauty of the male 

 over the female, without the need of the protective principle.' ' 



The consideration of the facts of Mimicry thus led 

 Darwin to the conclusion that the female happens 

 to vary in the right manner more commonly than 

 the male, while the secondary sexual characters of 

 males supported the conviction ' that from some 

 unknown cause such characters [viz. new charac- 

 ters arising in one sex and transmitted to it alone] 

 apparently appear oftener in the male than in the 

 female \'^ 



Comparing these conflicting arguments, we are 



' More Letters, ii. 73, 74. On the same subject — ' the gay- 

 coloured females of Pieris ' {Pen-hyhris (Mylothris) pyrrha of Brazil), 

 Darwin wrote to Wallace, May 5, 1868, as follows: '1 believe 

 I quite follow you in believing that the colours are wholly due 

 to mimicry ; and I further believe that the male is not brilliant 

 from not having received through inheritance colour from the 

 female, and from not himself having varied ; in short, that he has 

 not been influenced by selection.' It should be noted that the 

 male of this species does exhibit a mimetic pattern on the under 

 surface. — More Letters, ii. 78. 



^ Letter from Darwin to Wallace, May 5, 1867, More Letters, 

 ii. 61. 



