Albinistic Variations 



example, the appearance of red hackles in the 

 cocks of black breeds of poultry. On the other 

 hand, some certainly are not reversions, such as 

 the appearance of a white ring in the neck of the 

 female of the Rouen duck, which should resemble 

 the Mallard as regards the plumage of the neck. 

 Again, the tendency of Buff Orpingtons to 

 assume white in the wings and tail must be 

 regarded as a variation which is not in the nature 

 of a reversion. In short, the efforts of all 

 breeders are largely directed to fighting against 

 the tendencies which animals display towards 

 variation in certain directions. 



This tendency to vary in the direction of 

 whiteness may account for many of the white 

 markings which occur in nature, as, for example, 

 the white tails of the Sea Eagle (Haliaetus 

 albicilla) the Nicobar Pigeon (Caloenas nico- 

 barica), and many hornbills. Provided that such 

 variations are not too great a handicap to their 

 possessors in the struggle for existence, natural 

 selection will allow them to persist. 



It was the belief of Linnaeus, based on experi- 

 ence, that every blue or red-coloured flower is 

 likely to produce a white variety, hence he held 

 that it is not safe to trust to colour for the identi- 

 fication of a botanical species. 



On the other hand, white flowers are not likely 

 to produce red varieties, and we believe we may 

 positively assert that they never produce a blue 

 E 65 



