PROTECTIVE COLOURING. 263 



sciously and without a plan. If we had not thoroughly 

 considered the interaction of Inheritance and Adaptation 

 under the influence of the struggle for life, we should not 

 at first be inclined to expect such results from this natural 

 process of selection as are, in fact, furnished by it. It may 

 therefore be appropriate here to mention a few especially 

 striking examples of the activity of natural selection. 



Let us first take Darwins hoonochromic selection of 

 animals, or the so-called " sympathetic selection of colours," 

 into consideration. Earlier naturalists have remarked that 

 numerous animals are of nearly the same colour as their 

 dwelling-place, or the surroundings in which they per- 

 manently live. Thus, for example, plant-lice and many 

 other insects living on leaves are of a green colour. The 

 inhabitants of the deserts, the jerboa, or leaping mice, foxes 

 of the desert, gazelles, lions, etc., are mostly of a yellow or 

 yellowish-brown colour, like the sand of the desert. The 

 polar animals, which live on the ice and snow, are white or 

 grey, like ice and snow. Many of these animals change their 

 colour in summer and winter. In summer, when the snow 

 partly vanishes, the fur of these polar creatures becomes 

 brownish-grey or blackish, like the naked earth, while in 

 winter it again becomes white. Butterflies and insects 

 which hover round the gay and bright flowers are like them 

 in colour. Now, Darwin explains this surprising circum- 

 stance quite simply by the fact that such colours as agree 

 with the colour of the habitation are of the greatest use to 

 the animals concerned. If these animals are animals of 

 prey, they will be able to approach the object of their 

 pursuit more safely and with less likelihood of observation, 

 and, in like manner, those animals which are pursued will 



