318 Darwin, and after Darwin. 



duced differs in different animals; but it is needless 

 for our purposes to go into this part of the subject. 

 Again, there are yet other cases where protective 

 colouring which is admirably suited to conceal an 

 animal through one part of the year, would become 

 highly conspicuous during another part of it namely, 

 when the ground is covered with snow. Accordingly, 

 in these cases the animals change their colour in the 

 winter months to a snowy white : witness stoats, 

 mountain hares, ptarmigan, &c. (Fig. 108.) 



Now, it is sufficiently obvious that in all these 

 classes of cases the concealment from enemies .or 

 prey which is thus secured is of advantage to the 

 animals concerned ; and, therefore, that in the theory 

 of natural selection we have a satisfactory theory 

 whereby to explain it. And this cannot be said of 

 any other theory of adaptive mechanisms in nature 

 that has ever been propounded. The so-called La- 

 marckian theory, for instance, cannot be brought to 

 bear upon the facts at all ; and on the theory of 

 special creation it is unintelligible why the phenomena 

 of protective colouring should be of such general 

 occurrence. For, in as far as protective colouring 

 is of advantage to the species which present it, it is 

 of corresponding disadvantage to those other species 

 against the predatory nature of which it acts as a 

 defence. And, of course, the same applies to yet 

 other species, if they serve as prey. Moreover, the 

 more minutely this subject is investigated in all its 

 details, the more exactly is it found to harmonise 

 with the naturalistic interpretation 1 . 



1 Were it not that some of Darwin's critics have overlooked the very 

 point wherein the great value of protective . colouring as evidence of 



