Chap. VIII. SEXUAL SELECTION. 317 



selection in the manner hereafter to be described. The 

 same train of reasoning is applicable in the above, 

 as well as in the following case, if we assume that 

 females instead of males are produced in excess, for 

 such females from not uniting with males would be 

 superfluous and useless. So it would be with poly- 

 gamous species, if we assume the excess of females 

 to be inordinately great. 



An excess of either sex, we will again say of the 

 males, could, however, apparently be eliminated through 

 natural selection in another and indirect manner, namely 

 by an actual diminution of the males, without any in- 

 crease 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, inhabiting any locality, would produce 

 a rather smaller excess of superfluous males, but an 

 equal number of productive females. When the off- 

 spring 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 pro- 

 duced 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 afterwards. We see 

 this principle illustrated with plants; as those which 

 bear a vast number of seed produce small ones ; whilst 

 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 



' 3 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 seeds in the more productive 

 capsules. 



