78 ANIMAL COLORATION. 



The musk-ox being a comparatively defenceless animal, it 

 is perhaps a little surprising to find that it does not assume 

 a white colour in the winter. But here union is strength ; 

 it is more important that a straggler should be able to regain 

 his companions, which would be difficult if they were less 

 conspicuous. One is inclined, however, to suggest in the case 

 of this animal that its scent may serve for recognition purposes 

 perhaps more efficiently than even its conspicuous appearance 

 against the white snow. It is difficult to decide offhand in 

 every case how far the white coloration is useful, whether 

 for protective or aggressive purposes. The polar bear, for 

 example, always quoted as an instance of an animal that has 

 reaped advantages from its protective coloration, according to 

 Nordenskiold, hunts rather by smell than sight ; its colora- 

 tion, therefore, can hardly be for aggressive purposes. It is 

 important to remember in this particular case that, although 

 the hairs are largely depigmented, they are not entirely so ; 

 at any rate the colour, except in very young bears, is of a 

 creamy tint rather than white. So pronounced is this some- 

 times that the Scotch whalers know the animal by the name 

 of " Brownie." * 



Even the Arctic fox does not always change colour in the 

 winter in its native country, any more than it does with us ;. 

 Mr. Brown states f that white and blue foxes are met with in 

 the winter, that the colour is not dependent on the season. Both 

 these facts look more like the direct effect of cold and dryness 

 than of natural selection. 



Professor Semper has pointed out another difficulty in the 

 way of accepting the theory that the change of coloration 

 in Arctic animals is due to natural selection. Even supposing 

 the usefulness of the change, which is not entirely obvious, 



* Proc. Zool. Soc., " Mammals of Greenland." 18G8. f Loc. cit. 



