2, CONTROLLED NATURAL SELECTION 



On the other hand, the soma carrying the 

 male germ cells, the male, discharges its 

 germ cells before fertilisation, and therefore 

 is at no time bisexual, as the female can be. 

 For another reason, males are less valuable 

 than females because the male can fer- 

 tilise a number of females ; therefore fewer 

 males than females are required by a species. 

 Further, as the sexes at birth commonly are 

 approximately equal, and the environment 

 of a species is always limited, and a species 

 is best off when it fills its environment with 

 individuals capable of the greatest fer- 

 tility ... it follows that males, when in 

 excess of females, or when equalling them 

 in number, or perhaps even when somewhat 

 less numerous, must be less valuable than 

 females. Besides a difference in the value 

 of individuals according to sex, there is a 

 difference according to age. 



A very old and sterile, or relatively sterile, 

 individual is not only valueless but harmful 

 to the species, in that it fills a place that a 

 fertile individual should occupy. Young are 

 more valuable than old, because they have 

 a longer life for reproduction before them. 



There are other factors which give in- 

 dividuals of a species differences in value, 



