372 THE DESCENT OF MAN. 



have varied in a slightly different manner, and that the 

 variations have been transmitted by each sex to the same, 

 without any benefit or evil thus accruing. When the 

 male is brilliantly colored and differs conspicuously from 

 the female, as with some dragon-flies and many butterflies, 

 it is probable that he owes his colors to sexual selection, 

 while the female has retained a primordial or very ancient 

 type of coloring, slightly modified by the agencies before 

 explained. But in some cases the female has apparently 

 been made obscure by variations transmitted to her alone, 

 as a means of direct protection; and it is almost certain 

 that she has sometimes been made brilliant, so as to imitate 

 other protected species inhabiting the same district. When 

 the sexes resemble each other and both are obscurely colored 

 there is no doubt that they have been in a multitude of 

 cases so colored for the sake of protection. So it is in some 

 instances when both are brightly colored, for they thus imi- 

 tate protected species, or resemble surrounding objects such 

 as flowers; or they give notice to their enemies that they 

 are unpalatable. In other cases in which the sexes resem- 

 ble each other and are both brilliant, especially when the 

 colors are arranged for display, we may conclude that they 

 have been gained by the male sex as an attraction, and have 

 been transferred to the female. We are more especially led 

 to this conclusion whenever the same type of coloration pre- 

 vails throughout a whole group, and we find that the males 

 of some species differ widely in color from the females, 

 while others differ slightly or not at all with intermediate 

 gradations connecting these extreme states. 



In the same manner as bright colors have often been par- 

 tially transferred from the males to the females, so it has 

 been with the extraordinary horns of many Lamellicorn 

 and some other beetles. So, again, the sound-producing 

 organs proper to the males of the Homoptera and Orthop- 

 tera have generally been transferred in a rudimentary, or 

 even in a nearly perfect condition, to the females ; yet not 

 sufficiently perfect to be of any use. It is also an interest- 

 ing fact, as bearing on sexual selection, that the stridu- 

 lating organs of certain male Orthoptera are not fully 

 developed until the last moult; and that the colors of cer- 

 tain male dragon-flies are not fully developed until some 

 little time after their emergence from the pupal state, and 

 when they are ready to breed. 



