96 CONTROLLED NATURAL SELECTION 



it is now only being introduced as a working 

 hypothesis. It will probably not explain all 

 cases of conspicuous colouring among parents, 

 for it has been shown that conspicuous colour- 

 ing may be used for other purposes. 



Attraction marks (see page 40, Chapter III) 

 may be especially mentioned, for although 

 they are conspicuous they are found in both 

 parents and young. The rule appears to be : 

 (1) vital parts that are conspicuously coloured 

 in parents are protectively coloured in young, 

 and (2) non-vital parts conspicuously coloured 

 in parents are similarly coloured in young. 



A few examples are necessary: (1) The 

 Goldfinch (Carduelis elegans) : yellow bar 

 across the wing, found in both parents and 

 young; other conspicuous colours on vital 

 parts of parents are not found in young, 

 which are protectively coloured ; (2) Wheat- 

 ear (Saxicola cenanthe) : white rump present 

 in both parents and young ; (3) Wood-pigeon 

 (Columba palumbus) : white patch on side of 

 neck in parent, and because on a vital part, 

 not present in young; (4) Mallard (Anasbascus): 

 speculum on wing found in young and old, in 

 all plumages. 



It appears, therefore, that some of the differ- 

 ences in colour between parents and young, 



