SEXUAL SELECTION 421 



she has simply retained to a large extent her primordial 

 colors. 



Finally, as we have seen, various considerations lead to 

 the conclusion that with the greater number of brilliantly 

 colored Lepidoptera it is the male which has been chiefly 

 modified through sexual selection; the amount of difference 

 between the sexes mostly depending on the form of inheri- 

 tance which has prevailed. Inheritance is governed by so 

 many unknown laws or conditions that it seems to us to act 

 in a capricious manner;" and we can thus, to a certain 

 extent, understand how it is that with closely allied species 

 the sexes either differ to an astonishing degree, or are iden- 

 tical in color. As all the successive steps in the process of 

 yariation are necessarily transmitted through the female, 

 a greater or less number of such steps might readily become 

 developed in her; and thus we can understand the frequent 

 gradations from an extreme difference to none at all between 

 the sexes of allied species. These cases of gradation, it 

 may be added, are much too common to favor the sup- 

 position that we here see females actually undergoing the 

 process of transition and losing their brightness for the sake 

 of protection; for we have every reason to conclude that 

 at any one time the greater number of species are in a 

 fixed condition. 



Mimicry. — This principle was first made clear in an 

 admirable paper by Mr. Bates," who thus threw a flood of 

 light on many obscure problems. It had previously been 

 observed that certain butterflies in South America, belong- 

 ing to quite distinct families, resembled the Heliconidae so 

 closely in every stripe and shade of color that they could 

 not be distinguished save by an experienced entomologist. 

 As the Heliconidae are colored in their usual manner, while 

 the others depart from the usual coloring of the groups to 

 which they belong, it is clear that the latter are the imi- 



>» "The Variation of Animals and Plants under Domestication," vol. a. 

 ebap. xii. p. 17. 



«» "Transact. Linn. Sec," vol. xiiii., 1862, p. 496. 



