THE STABILITY OF SPECIES 45 



the normal type, unless natural selection steps in to 

 their aid. 



Is comparative infertility the result of feebleness of 

 the sexual instinct ? If so, sexual selection must be 

 conducive to the stability of species. 



For if the rule be the greater the deviation of an 

 individual from the normal the less the development in 

 it of the sexual instinct and the less its fertility, it 

 follows that an abnormal organism is less likely to 

 find a mate than a normal individual is ; and if it do 

 succeed in forming a union, that union will probably 

 produce less than the average number of offspring. 



