Sketches from Nature. 3 1 1 



it would, a black speck on the otherwise white 

 surface, it would in a few years become extinct. 

 The ptarmigan, then, furnishes an example of the 

 assumption of three different states of plumage, 

 each assimilating to the physical conditions by 

 which it is surrounded. Of course the same rule 

 applies to the falcon, which is also white. 

 Precisely the same set of facts operate in the 

 case of the large snowy owl in the fir countries 

 which it inhabits. Here its food consists of 

 lemmings, Alpine hares, and birds, particularly 

 the willow-grouse and ptarmigan. The balance 

 of nature would be slightly against it, however, 

 in the capture of animals which have assumed 

 protective colouring, and hence we are told that 

 "it has been known to watch the grouse-shooters 

 a whole day for the purpose of sharing the spoil. 

 On such occasions it perches on a high tree, and 

 when a bird is shot skims down and carries it off 

 before the sportsman can get near it." Yet 

 again the same reasoning applies to the beautiful 

 silver fox, which structurally in nowise differs from 

 its red-furred cousin of more southern counties. 



Hares, according to the altitude of their range, 

 show almost every degree of variableness be- 

 tweeen red and white. Our common hare is 

 widely distributed, and to such an extent do 

 varietal forms differ that several distinct species 

 (so called) have been evolved out of one. 

 The extreme forms do seem widely separated, 



