42 NATURE STUDIES. 



produced Lave to " struggle for existence." Suppose 

 a number of white varieties produced in a cold, snowy 

 region, along with varieties of more conspicuous 

 colours. It is evident that, whilst the white varieties 

 would escape from their enemies,, the darker- coloured 

 individuals would succumb. Thus the white race 

 comes to the front, and holds its own, and its per- 

 petuation and increase becomes a matter of surety. 

 Summing tip the argument, we find that two factors 

 are at work in bringing about these wonderful colour 

 likenesses in the animal world. The one is variation, 

 producing the colour-varieties ; the other is the cir- 

 cumstances of life, which weed out the weak and give 

 the battle to the strong, which latter are those whose 

 colours best suit their surroundings. This is the 

 philosophy which natural history to-day lays down for 

 our acceptance. Nay, more, it is a philosophy which 

 explains far more important facts of life than mere 

 mimicry. It is " evolution and development " reduced 

 to their plainest and fundamental terms in a word, 

 Darwinism in a nutshell, as illustrated by the varia- 

 tion and change that all life knows, and by the 

 warring of that life bringing the best of its units to 

 the front of the battle. 



