318 THE DESCENT OP MAN. 



than do the males. They thus show us approximately the pri- 

 mordial coloring of the parent-species of the group to which they 

 belong. They have, however, almost always been somewhat modi- 

 fied by the transfer to them of some of the successive variations, 

 through the accumulation of which the males were rendered beau- 

 tiful. But I do not wish to deny that the females alone of some 

 species may have been specially modified for protection. In most 

 cases the males and females of distinct species will have been 

 exposed during their prolonged larval state to different conditions, 

 and may have been thus affected; though with the males any 

 slight change of color thus caused will generally have been 

 masked by the brilliant tints gained through sexual selection. 

 When we treat of Birds, I shall have to discuss the whole question, 

 as to how far the differences in color between the sexes are due 

 to the males having been modified through sexual selection for 

 ornamental purposes, or to the females having been modified 

 through natural selection for the sake of protection, so that I will 

 here say but little on the subject. 



In all the cases in which the more common form of equal 

 inheritance by both sexes has prevailed, the selection of bright- 

 colored males would tend to make the females bright-colored; 

 and the selection of dull-colored females would tend to make 

 the males dull. If both processes were carried on simultaneously, 

 they would tend to .counteract each other; and the final result 

 would depend on whether a greater number of females from 

 being well protected by obscure colors, or a greater number of 

 males by being brightly-colored and thus finding partners, suc- 

 ceeded in leaving more numerous offspring. 



In order to account for the frequent transmission of characters 

 to one sex alone, Mr. Wallace expresses his belief that the more 

 common form of equal inheritance by both sexes can be changed 

 through natural selection into inheritance by one sex alone, but 

 In f3,vor of this view I can discover no evidence. We know from 

 what occurs under domestication that new characters often ap- 

 pear, which from the first are transmitted to one sex alone; and 

 by the selection of such variations there would not be the slight- 

 est diflBculty in giving bright colors to the males alone, and at 

 the same time or subsequently, dull colors to the females alone. 

 In this manner the females of some butterflies and moths have, it 

 is probable, been rendered inconspicuous for the sake of pro- 

 tection, and widely different from their males. 



I am, however, unwilling without distinct evidence to admit 

 that two complex processes of selection, each requiring the 

 transference of new characters to one sex alone, have been carried 

 on with a multitude of species, — that the males have been rendered 

 more brilliant by beating their rivals, and the females more dull- 

 colored by having escaped from their enemies. The male, for 



