Chap. VIIL] SEXUAL SELECTION. 309 



selection in another and indirect manner, namely, by an 

 actual diminution of the males, without any increase of 

 the females, and consequently without any increase in the 

 productiveness of the species. From the variability of all 

 characters, we may feel assured that some pairs, inhabit- 

 ing any locality, would produce a rather smaller excess of 

 superfluous males, but an equal number of productive 

 females. When the offspring from the more and the less 

 male-productive parents were all mingled together, none 

 would have any direct advantage over the others ; but 

 those that produced few superfluous males would have 

 one great indirect advantage, namely, that their ova or 

 embryos would probably be larger and finer, or their 

 young better nurtured in the womb and afterward. We 

 see this principle illustrated with plants ; as those whicli 

 bear a vast number of seed produce small ones ; while 

 those which bear comparatively few seeds, often produce 

 large ones well-stocked with nutriment for the use of the 

 seedlings. 73 Hence the offspring of the parents which had 

 wasted least force in producing superfluous males would 

 be the most likely to survive, and would inherit the same 

 tendency not to produce superfluous males, while retain- 

 ing their full fortility in the production of females. So it 

 would be with the converse case of the female sex. Any 

 slight excess, however, of either sex could hardly be 

 checked in so indirect a manner. Nor indeed has a con- 

 siderable inequality between the sexes been always pre- 

 vented, as we have seen in some of the cases given in the 

 previous discussion. In these cases the unknown causes 

 which determine the sex of the .embryo, and which under 

 certain conditions lead to the production of one sex in 



73 I have often been struck with the fact that, in several species of 

 Primula, the seeds in the capsules which contained only a few were 

 very much larger than the numerous seeda in the more productive cap- 

 sules. 



