SELECTION 171 



trated in Hydra and Tubularia, reminding us 

 of the struggle between sister queen- bees. 

 There is a kind of struggle among the hundreds 

 of spermatozoa in their race towards the ovum. 

 Allowing a margin for chance, the most 

 vigorous and sensitive spermatozoa will tend 

 to succeed and this will be for the advantage 

 of the species. We are quaintly reminded 

 of the race between drones to overtake the 

 queen-bee in her nuptial flight. There is also 

 sexual selection and germinal selection, which 

 may be conveniently considered in separate 

 sections. 



SEXUAL SELECTION. In extension of his 

 theory of natural selection Darwin proposed 

 a theory of sexual selection to account for the 

 frequent occurrence of markedly contrasted 

 secondary sex-characters, familiar in cases 

 like peacock and peahen, stag and hind. 

 There are two modes of this sexual selection: 

 the combats between rival males, and the 

 preferential mating where the female chooses 

 or seems to choose. 



The issue is clearer in the case of the combats 

 of males. For when the younger or weaker 

 candidates are killed, or expelled from the 

 herd, or left unmated, there seems little 

 reason to doubt the discriminateness of the 

 elimination. 



