448 THE DESCENT OF MAN 



can see that one sex will not be modified througb natural 

 eelection for the sake of protection more than the other, 

 supposing both to vary, unless one sex is exposed for a 

 longer period to danger^ or has less power of escaping from 

 such danger than the other; and it does not appear that 

 with fishes the sexes differ in these respects. As far as 

 there is any difference, the males, from being generally 

 smaller and from wandering more about, are exposed to 

 greater danger than the females; and yet, when the sexes 

 differ, the males are almost always the more conspicuously 

 colored. The ova are fertilized immediately after being 

 deposited ; and when this process lasts for several days, as 

 in the case of the salmon," the female, during the whole 

 time, is attended by the male. After the ova are fertilized 

 they are, in most cases, left unprotected by both parents, 

 BO that the males and females, as far as oviposition is con- 

 cerned, are equally exposed to danger, and both are equally 

 important for the production of fertile ova; consequently 

 the more or less brightly colored individuals of either sex 

 would be equally liable to be destroyed or preserved, and 

 both would have an equal influence on the colors of 

 their offspring. 



Certain fishes, belonging to several families, make nests, 

 and some of them take care of their young when hatched. 

 Both sexes of the bright-colored Grenilabrus massa and 

 melops work together in building their nests with sea-weed, 

 shells, etc." But the males of certain fishes do all the 

 work, and afterward take exclusive charge of the young. 

 This is the case with the dull-colored gobies," in which 

 the sexes are not known to differ in color, and likewise with 

 the sticklebacks (Grasterosteus), in which the males become 

 brilliantly colored during the spawning season. The male 

 of the smooth-tailed stickleback {G. leiurvs) performs the 



** Tarrell, "British Fishes," vol. ii. p. 11. 



*• According to the observatlona of M. Gerbe; see Gflnther's "Record of 

 Zoolog. Literature," 1865, p. 194. 



s« Cuvier, "B^gne Animal," vol. ii., 1829, p. 242. 



