588 SEXUAL SELECTION. [Part II 



been rendered brighter by degrees, and will have been 

 transmitted to both sexes or to one sex, according to 

 which law of inheritance prevailed. The process of sexual 

 selection will have been much facilitated, if the conclu- 

 sions arrived at from various kinds of evidence in the sup- 

 plement to the ninth chapter can be trusted ; namely, that 

 the males of many Xiepidoptera, at least in the imago 

 state, greatly exceed in number the females. 



Some facts, however, are opposed to the belief that 

 female butterflies prefer the more beautiful males ; thus, 

 as I have been assured by several observers, fresh females 

 may frequently be seen paired with battered, faded, or 

 clingy males ; but this is a circumstance which could hard- 

 ly fail often to follow from the males emerging from their 

 cocoons earlier than the females. With moths of the 

 family of the Bombycidse, the sexes pair immediately after 

 assuming the imago state ; for they cannot feed, owing to 

 the rudimentary condition of their mouths. The females, 

 as several entomologists have remarked to me, lie in an 

 almost torpid state, and appear not to evince the least 

 choice in regard to their partners. This is the case with 

 the common silk-moth {J3. mori), as I have been told by 

 some Continental and English breeders. Dr. Wallace, 

 who has had such immense experience in breeding J3om- 

 byx cynthia, is convinced that the females evince no choice 

 or preference. He has kept above 300 of these moths liv- 

 ing together, and has often found the_most vigorous fe- 

 males mated with stunted males. The reverse apparently 

 seldom occurs ; for, as he believes, the more vigorous 

 males pass over the weakly females, being attracted by 

 those endowed with most vitality. Although we have 

 been indirectly induced to believe that the females of 

 many species prefer the more beautiful males, I have no 

 reason to suspect, e ; .ther with moths or butterflies, that 

 the males are attracted by the beauty of the females. If 



