3hap. X. Hymenoptera. 293 



such contests for the mandibles of the males being in certain 

 Bpecies larger than those of the females. In some cases the 

 males are far more numerous than the females, either early 

 m 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- beautiful males appear to have been selected by the 

 females ; and in others the more beautiful females by the males. 

 Consequently in certain genera (MUller, p. 42), the males of the 

 .several species differ much in appearance, whilst the females are 

 almost indistinguishable ; in other genera the reverse occurs. 

 H. Muller believes (p. 82) that the colours gained by one sex 

 through sexual selection have often been transferred 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 Europsea makes a stridulating noise ; and according to 

 Goureau "^ 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 con- 

 centric ridges ; but so is the projecting thoracic collar, into wljich 

 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 winged and the female wingless. It is notorious that 

 Bees express certain emotions, as of anger, by the tone of their 

 humming; and according to H. Mtiller (p. 80), the males of 

 some species make a peculiar singing noise whilst pursuing the 

 females. 



" M. Pernor in his article ' la Se- male grandfathers? To take a case 



lection sexuelled'aprSs Darwin '('Re- with ordinary animals as nearly 



vue Soientifique,' Feb. 1873, p. 868), parallel as possible: if a female of 



without apparently having reflected any white quadruped or bird were 



much on the subject, objects that as crossed by a male of a black breed, 



the males of social bees are known and the male and female offspring 



to be produced from unfertilised were paired together, will it be 



ova, they could not transmit new pretended that the grandchildren 



characters to their male offspring, would not inherit a tendency to 



This is an extraordinary objection, blackness A'om their male grand- 



A female bee fertilised by a male, father? The acquirement of new 



which presented some character fa- characters by the sterile worker-bees 



cilitating the union of the sexes, or is a much more dilEcult case, but I 



rendering hiro more attractive to have endeavoured to show in my 



the female, would lay eggs which 'Origin of Species,' liow these sterile 



ironld produce only females ; but beings are subjected to the power o' 



these young females would next natural selection. 



year produce males; and will it be '^ Quoted by Westwood, 'Modern 



pretended that such miiles would Class, of Insects,' vol, . p, 214, 

 Bot inherit the ch,ii'actoi-.s of Iheir 



