332 THE DESCENT OF MAN. 



accounts through such contests for the mandibles of the 

 males being in certain species larger than those * of the 

 females. In some cases the males are far more numerous 

 than the females, either early in the season, or at all times 

 and places, or locally; whereas the females in other cases 

 are apparently in excess. In some species the more beauti- 

 ful males appear to have been selected by the females; and 

 in others the more beautiful females by the males. Conse- 

 quently in certain genera (Miiller, p. 42) the males of the 

 several species differ much in appearance, while the females 

 are almost indistinguishable; in other genera the reverse 

 occurs. H. Miiller believes (p. 82) that the colors gained 

 by one sex through sexual selection have often been trans- 

 ferred in a variable degree to the other sex, just as the 

 pollen-collecting apparatus of the female has often been 

 transferred to the male, to whom it is absolutely useless. * 



Mutilla Europma makes a stridulating noise; and accord- 

 ing to Groureau f both sexes have this power. He attributes 

 the sound to the friction of the third and preceding 

 abdominal segments, and I find that these surfaces are 

 marked with very fine concentric ridges; but so is the pro- 

 jecting thoracic collar into which the head articulates, and 

 this collar, when scratched with the point of a needle, 

 emits the proper sound. It is rather surprising that both 

 sexes should have the power of stridulating, as the male is 



*M. Perrier in his article " la Selection sexuelle d'apres Darwin" 

 ("Revue Scientifique," Feb., 1873, p. 868), without apparently having 

 reflected much on the subject, objects that as the males of social bees 

 are known to be produced from unfertilized ova, they could not trans- 

 mit new characters to their male offspring. This is an extraordinary 

 objection. A female bee fertilized by a male, which presented some 

 character facilitating the union of the sexes, or rendering him more 

 attractive to the female, would lay eggs which would produce only 

 females; but these young females would next year produce males ; 

 and will it be pretended that such males would not inherit the char- 

 acters of their male grandfathers? To take a case with ordinary ani- 

 mals as nearly parallel as possible; if a female of any white quad- 

 ruped or bird were crossed by a male of a black breed, and the male 

 and female offspring were paired together, will it be pretended that 

 the grandchildren would not inherit a tendency to blackness from 

 their male grandfather ? The acquirement of new characters by the 

 sterile worker-bees is a much more difficult case, but I have endeav- 

 ored to show in my " Origin of Species " how these sterile beings are 

 subjected to the power of natural selection. 



\ Quoted by Westwood, " Modern Class, of Insects," voL ii, p. 214 



