138 A NEW THEORY OF EVOLUTION. 



trees where they are to be found. But the 

 exceptions to this correlation are numerous 

 enough to show that correlation is not due 

 to environment. 



The blackcock differs much in colour from 

 his grey mate ; the mountain-hare, bluish 

 grey in summer, becomes white in winter, 

 but the fox, living on the same mountain, 

 retains his colour unchanged. Grouse and 

 ptarmigan live in almost the same localities, 

 and in summer are similar in colour ; but as 

 winter approaches the grouse becomes a 

 darker brown, the ptarmigan white, and the 

 change begins long before the advent of snow. 



Some butterflies are attractively and bril- 

 liantly coloured, whilst others in the same 

 locality can hardly be distinguished from the 

 leaves and twigs on which they rest. 



Most animals in the arctic regions are 

 white, but the sable and the musk-sheep 

 are conspicuously brown, and other animals 

 are of different hues. 



Mr Alexander Wallace, in explanation of 

 these inconsistencies, says : " Whenever we 

 find arctic animals which, from whatever 

 cause, do not require protection by their 

 white colour, then neither the snow nor the 

 glare have any effect upon their colouration/' 



But this explanation seems really an argu- 



