388 THE DESCENT OF MAN. 



To return to our more immediate subject. The case 

 stands thus; female fishes, as far as I can learn, never will- 

 ingly spawn except in the presence of the males; and the 

 males never fertilize the ova except in the presence of the 

 females. The males fight for the possession of the females. 

 In many species the males while young resemble the females 

 in color; but when adult become much more brilliant, and 

 retain their colors throughout life. In other species the 

 males become brighter than the females and otherwise more 

 highly ornamented, only during the season of love. The 

 males sedulously court the females, and in one case, as we 

 have seen, take pains in displaying their beauty before 

 them. Can it be believed that they would thus act to no 

 purpose during their courtship? And this would be the case 

 unless the females exert some choice and select those males 

 which please or excite them most. If the female exerts 

 such choice, all the above facts on the ornamentation of 

 the males become at once intelligible by the aid of sexual 

 selection. 



We have next to inquire whether this view of the bright 

 colors of certain male fishes having been acquired through 

 sexual selection can, through the law of the equal trans- 

 mission of characters to both sexes, be extended to those 

 groups in which the males and females are brilliant in the 

 same, or nearly the same, degree and manner. In such a 

 genus as Labrus, which includes some of the most splendid 

 fislies in the world for instance, the Peacock Labrus {L. 

 pavo), described,* with pardonable exaggeration, as formed 

 of polished scales of gold, incrusting lapis-lazuli, rubies, 

 sapphires, emeralds and amethysts we may, with much 

 probability, accept this belief, for we have seen tliat the 

 sexes in at least one species of the genus differ greatly in 

 color. Witii some fishes, as with many of the lowest ani- 

 mals, splendid colors may be the direct result of the nature 

 of their tissues and of the surrounding conditions, without 

 the aid of selection of any kind. The gold-fish ( Cyprinus 

 auratus), judging from the analogy of the golden variety 

 of the common carp, is perhaps a case in point, as it may 

 owe its splendid colors to a single abrupt variation, due to 

 the conditions to which this fish has been subjected under 



* Bory de Saint Vincent, in 

 1826, p. 151. 



