100 CONTROLLED NATURAL SELECTION 



protection ; the absence of scent in many 

 hen birds which nest on the ground, in- 

 dicates that scent plays a greater part in 

 Nature than our feeble sense organ would 

 lead us to imagine. 



The pleasant perfume which some male 

 insects have, may be to draw an enemy's 

 attention to them, during copulation, rather 

 than to the female. In offensively scented 

 insects, the sexes are usually similar, and 

 the character is probably of a warning 

 nature. 



This concludes the majority of the char- 

 acters of conspicuousness which distinguish 

 parents from young, male from female : in 

 the one case, young as protected at the ex- 

 pense of parents ; in the other, females at 

 the expense of males. The following table 

 indicates how precisely similar are the 

 methods used ; examples are given from 

 among birds : 



