THE COLORS OF ANIMALS AND PLANTS. 



537 



female may lead to more contrasted markings. 

 Mr. Darwin thinks that here the males have se- 

 lected the more beautiful females, although one 

 chief fact in support of his theory of voluntary 

 sexual selection is, that throughout the whole 

 animal kingdom the males are usually so ardent 

 that they will accept any female, while the fe- 

 males are coy, and choose the handsomest males, 

 whence it is believed the general brilliancy of 

 males as compared with females has arisen. ' 



Perhaps the most curious cases of sexual dif- 

 ference of color are those in which the female is 

 very much more gayly colored than the male. 

 This occurs most strikingly in some species of 

 Pieris in South America, and of Diadema in the 

 Malay islands, and in both cases the females re- 

 semble species of the uneatable Dauaidae and 

 Heliconidie, and thus gain a protection. In the 

 case of Pieris pyrrka, P. malenka, and P. lorena, 

 the males are plain white and black, while the 

 females are orange, yellow, and black, and so 

 bandad and spotted as exactly to resemble 

 species of Helieonida?. Mr. Darwin admits 

 that these females have acquired these colors 

 as a protection ; but as there is no apparent 

 cause for the strict limitation of the color to 

 the female, he believes that it has been kept 

 down in the male by its being unattractive to 

 her. This appears to me to be a supposition 

 opposed to the whole theory of sexual selection 

 itself. For this theory is, that minute variations 

 of color in the male are attractive to the female, 

 have always been selected, and that thus the brill- 

 iant male colors have been produced. But in 

 this case he thinks that the female butterfly had 

 a constant aversion to every trace of color, even 

 when we must suppose it was constantly recur- 

 ring during the successive variations which re- 

 sulted in such a marvelous change in herself. 

 But if we consider the fact that the females fre- 

 quent the forests where the Heliconidaj abound, 

 while the males fly much in the open, and assem- 

 ble in great numbers with other white and yellow 

 butterflies on the banks of rivers, may it not be 

 possible that the appearance of orange stripes or 

 patches would be as injurious to the male as it is 

 useful to the female, by making him a more easy 

 mark for insectivorous birds among his white 

 companions ? This seems a more probable sup- 

 position than the altogether hypothetical choice 

 of the female, sometimes exercised in favor of 

 and sometimes against every new variety of color 

 in her partner. 



The full and interesting account given by Mr. 

 Darwin of the colors and habits of male and fe- 



male birds (" Descent of Man," chapters xiii. and 

 xiv.) proves that in most, if not in all, cases the 

 male birds fully display their ornamental plumage 

 before the females, and in rivalry with each other ; 

 but on the essential point of whether the female's 

 choice is determined by minute differences in 

 these ornaments or in their colors, there appears 

 to be an entire absence of evidence. In the sec- 

 tion on " Preference for Particular Males by the 

 Females," the facts quoted show indifference to 

 color, except that some color similar to their own 

 seems to be preferred. But in the case of the 

 hen-canary, who chose a greenfinch in preference 

 to either chaffinch or goldfinch, gay colors had 

 evidently no preponderating attraction. There 

 is some evidence adduced that female birds may, 

 and probably do, choose their mates, but none 

 whatever that the choice is determined by differ- 

 ence of color; and no less than three eminent 

 breeders informed Mr. Darwin that they "did not 

 believe that the females prefer certain males on 

 account of the beauty of their plumage." Again, 

 Mr. Darwin himself says, "As a general rule, 

 color appears to have little influence on the pair- 

 ing of pigeons." The oft-quoted case of Sir R. 

 Heron's peahens which preferred an " old pied 

 cock " to those normally colored, is a very un- 

 fortunate one, because pied birds are just those 

 that are not favored in a state of nature, or the 

 breeds of wild birds would become as varied and 

 mottled as our domestic varieties. If such irreg- 

 ular fancies were not rare exceptions, the produc- 

 tion of definite colors and patterns by the choice 

 of the female birds, or in any other way, would 

 be impossible. 



We now come to such wonderful develop- 

 ments of plumage and color as are exhibited by 

 the peacock and the Argus-pheasant ; and I may 

 here mention that it was the case of the latter 

 bird, as fully discussed by Mr. Darwin, wdiich 

 first shook my belief in " sexual," or more prop- 

 erly " female," selection. The long series of 

 gradations, by which the beautifull y-shaded ocelli 

 on the secondary wing-feathers of this bird have 

 been produced, are clearly traced out, the result 

 being a set of markings so exquisitely shaded as 

 to represent " balls lying loose within sockets " 

 — purely artificial objects of which these birds 

 could have no possible knowledge. That this 

 result should have been attained through thou- 

 sands and tens of thousands of female birds all 

 preferring those males whose markings varied 

 slightly in this one direction, this uniformity of 

 choice continuing through thousands and tens of 

 thousands of generations, is to me absolutely in- 



