86 CONTROLLED NATURAL SELECTION 



should be associated with great secondary 

 sexual difference, and vice versa. 



In some animals, an excess of males is pro- 

 duced by special methods, e.g. ants and bees. 

 It appears not so much to ensure the fertili- 

 sation of all females, as to render the chance 

 of their destruction small. It is noteworthy 

 that polygamy is usually associated with great 

 secondary sexual differences ; these latter, ac- 

 cording to the theory, give rise to great 

 destruction of males, hence the association, 

 as in the peacock. In predatory animals, 

 polygamy is very rare ; as are also great 

 secondary sexual differences. 



If, as some maintain, the purpose of eye-spots in insects 

 is to entice enemies to strike them, rather than more 

 vulnerable parts : may not the eye-spots on the peacock's 

 (Pavo Cristatus) tail be to entice an enemy away from the 

 female, to draw its attack? 



When considering the parental colouring 

 of birds, it will be noted that confinement of 

 conspicuous colouring to the male is asso- 

 ciated with open-nesting habits. It is possible 

 that, among birds, conspicuous colouring con- 

 fined to the male arose in this way (Wallace), 

 and that afterwards it has become greatly 

 evoluted by Natural Selection working with 

 pairs. There is some evidence that open- 



