362 TIIJS DESCENT OF MAN. 



males; so that the part which the two sexes play is reversed, 

 as is their relative beauty. Throughout the animal king- 

 dom the males commonly take the more active share in 

 wooing, and their beauty seems to have been increased by 

 the females having accepted the more attractive individuals; 

 but with these butterflies the females take the more active 

 part in the final marriage ceremony, so that we may sup- 

 pose that they likewise do so in the wooing; and in this case 

 we can understand how it is that they have been rendered 

 the more beautiful. Mr. Meldola, from whom the fore- 

 going statements have been taken, says in conclusion: 

 ^' Though I am not convinced of the action of sexual selec- 

 tion in producing the colors of insects, it cannot be denied 

 that these facts are strikingly corroborative of Mr. Darwin's 

 views. * 



As sexual selection primarily depends on variability, a 

 few words must be added on this subject. In respect to 

 color there is no difficulty, for any number of highly variable 

 Lepidoptera could be named. One good instance will suffice. 

 Mr. Bates showed me a whole series of specimens of Papilio 

 sesostris and P. childrenm; in the latter the males varied 

 much in the extent of the beautifully enameled green patch 

 on the fore wings, and in the size of the white mark, and 

 of the splendid crimson stripe on the hind wings; so that 

 there was a ^reat contrast among the males between the 

 most and the least gaudy. The male of Papilio sesostris 

 is much less beautiful than of P. childrencB; and it like- 

 wise varies a little in the size of the green patch on the 

 fore wings, and in the occasional appearance of the small 

 crimson stripe on the hind wings, borrowed, as it would 

 seem, from its own female; for the females of this and of 

 many other species in the iEneas group possess this crimson 

 stripe. Hence between the brightest specimens of P. ses- 

 ostris and the dullest of P. childrenm there was but a small 

 interval; and it was evident that as far as mere variability 

 is concerned, there would be no difficulty in permanently 

 increasing the beauty of either species by means of selec- 

 tion. The variability is here almost confined to the male 



* "Nature," April 27, 1871, p. 508. Mr. Meldola quotes Donzel, 

 in "Soc. Ent. de France," 1837, p. 77, on the flight of butterflies 

 while pairing. See also Mr. G. Fraser, in " Nature," April 20, 1871, 

 p. 489, on the sexual differences of several British butterflies. 



