314 THE COLOURS OF ANIMALS 



CHAPTEK XVI 

 OTHEB THEORIES OF SEXUAL COLOUBING 



It now remains to consider the causes which Mr. 

 Wallace and other writers believe to have been efficient 

 in producing sexual colouring. 



A wide extension of the principle of Recognition Mark- 

 ings is believed largely to explain sexual colouring 



In the first place, this distinguished naturalist 

 very widely extends the principle of Eecognition Mark- 

 ings, and believes that one of the chief meanings of 

 sexual colouring is to enable * the sexes to recognise 

 their kind, and thus avoid the evils of infertile crosses.' 

 Thus he considers that ' among insects the principle 

 of distinctive colouration for recognition has probably 

 been at work in the production of the wonderful diver- 

 sity of colour and marking we find everywhere, more 

 especially among the butterflies and moths ; and here 

 its chief function may have been to secure the pairing 

 together of individuals of the same species.' 



