326 CAUSES OF ALBINISM. 



survival in the battle of life than their white-robed 

 companions the latter would therefore in the end 

 assert their superior fitness, and would thus survive, 

 whilst the former perished of this there can be little 

 doubt ; but that does not explain to us by what process 

 Nature proceeds to whiten the fur and feathers of her 

 proteges. The question therefore which we propose to 

 ask ourselves is How do they come to turn white ? Are 

 we to regard this as merely an effect of exposure to 

 great cold? And if so, does it ever whiten the coats 

 of birds and animals exposed to exceptional cold, 

 which are always (except on those rare occasions) 

 otherwise coloured? We can have no doubt but 

 that these questions must be answered in the affirm- 

 ative. 



We humbly venture to believe, and say, that in 

 our opinion the white colours of the creatures inhabiting 

 the polar regions are simply due to the permanence 

 and intensity of the cold. This however is a highly 

 technical question, and we feel that we are here treading 

 upon somewhat delicate ground, concerning which 

 conflicting opinions may be held, and that it is sometimes 

 said that in the case of birds, these changes of colour 

 are due to a regular moult, and not to any change 

 of colour in the feathers themselves ; we are inclined how- 

 ever to regard this view as an error. * Alteration in the 

 colour of the hair, in the case of the human subject 

 for instance (where the matter has been made the subject 

 of extensive research) is now known to proceed from 

 " the arrest of pigmentation, which gives rise to 



* See for instance observations on this subject in A Spring and 

 Summer in Lapland, by Horace W. Wheelwright (Naturalist), 1871, 

 PP- 3I43I7- 



