PARENTAL COLOUR 93 



young animal, or an adult, are of two kinds 

 (1) structures, or parts of structures, which 

 their ancestors possessed, and which have 

 been retained because they are useful ; (2) 

 added structures, which their distant ancestors 

 never possessed, to fit some new environment ; 

 these may be added at any stage of develop- 

 ment from the egg to the complete adult. 

 Therefore the hereditary explanation of the 

 difference of colour between young and adult 

 is not sufficient. That this is so is also proved 

 by the whole of experimental embryology, and 

 also by the fact that examples can be found 

 of young animals not presenting protective 

 colouring, and almost certainly not having the 

 colour of their ancestors. One must conclude, 

 therefore, that young animals are as a rule 

 protectively coloured, and adults often con- 

 spicuously coloured, for a purpose. 



An examination of the species which present 

 protectively coloured young and conspicuously 

 coloured adults, reveals the fact that in the 

 vast majority of cases young and parents are 

 associated together during a portion of their 

 lives ; and further, that it is whilst thus 

 associated that the difference is most marked 

 e.g. parents are most brilliant during the 

 breeding season. Examples of conspicuously 



