Tlie Evidence from Sexual Characters. 211 



inexplicable if the dull colors of the females are due to 

 direct modification by natural selection. 



Again, we must recollect that among the lizards, where 

 the females do not incubate, the males are often much 

 more conspicuously colored than the females, and 

 the females of allied species are more alike than the 

 males. Here the dull colors of the females as compared 

 with those of the males cannot be accounted for by the 

 natural selection of those females which are least ex- 

 posed to danger during incubation. 



Among fishes the same rule is adhered to, and the 

 males are usually more conspicuous than the females, 

 and here the female is certainly no more exposed to dan- 

 ger than the male. *' As far as there is any difference, 

 the males, from being generally of smaller size, and from 

 wandering about more, are exposed to greater danger 

 than the females; and yet when the sexes differ, the 

 males are almost always the most 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, so 

 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; con- 

 sequently 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 or the race." (Darwin, Sex- 

 ual Selection, Vol. II, p. 19.) 



The male stickleback does all the work of building 

 the nest, and after the eggs are laid and fertilized he 

 drives the females away, and performs for a long time 



