Natural Selection and Adaptation 275 



older naturalists who thought and spoke with Burchell of "the intention 

 of Nature " and the adaptation of beings " to each other, and to the 

 situations in which they are found," could have conceived the 

 possibility of evolution, they must have been led, as Darwin was, by 

 the same considerations to Natural Selection. This was impossible 

 for them, because the philosophy which they followed contemplated 

 the phenomena of adaptation as part of a static immutable system. 

 Darwin, convinced that the system is dynamic and mutable, was 

 prevented by these very phenomena from accepting anything short of 

 the crowning interpretation offered by Natural Selection l . And the 

 birth of Darwin's unalterable conviction that adaptation is of 

 dominant importance in the organic world, — a conviction confirmed 

 and ever again confirmed by his experience as a naturalist — may 

 probably be traced to the influence of the great theologian. Thus 

 Darwin, speaking of his Undergraduate days, tells us in his Auto- 

 biography that the logic of Paley's Evidences of Christianity and 

 Moral Philosophy gave him as much delight as did Euclid. 



"The careful study of these works, without attempting to learn 

 any part by rote, was the only part of the academical course which, 

 as I then felt and as I still believe, was of the least use to me in the 

 education of my mind. I did not at that time trouble myself about 

 Paley's premises ; and taking these on trust, I was charmed and 

 convinced by the long line of argumentation 2 ." 



When Darwin came to write the Origin he quoted in relation to 

 Natural Selection one of Paley's conclusions. "No organ will be 

 formed, as Paley has remarked, for the purpose of causing pain or for 

 doing an injury to its possessor 3 ." 



The study of adaptation always had for Darwin, as it has for 

 many, a peculiar charm. His words, written Nov. 28, 1880, to 

 Sir W. Thiselton-Dyer, are by no means inapplicable to-day : " Many 

 of the Germans are very contemptuous about making out use of 

 organs ; but they may sneer the souls out of their bodies, and I for 

 one shall think it the most interesting part of natural history 4 .' 



Protective and Aggressive Resemblance: Procryptic and 

 Anticryptic colouring. 



Colouring for the purpose of concealment is sometimes included 

 under the head Mimicry, a classification adopted by H. W. Bates in 



1 "I had always been much struck by such adaptations [e.g. woodpecker and tree-frog 

 for climbing, seeds for dispersal], and until these could be explained it seemed to me 

 almost useless to endeavour to prove by indirect evidence that species have been modified." 

 Autobiography in Life and Letters of Charles Darwin, Vol. i. p. 82. The same thought is 

 repeated again and again in Darwin's letters to his friends. It is forcibly urged in the 

 Introduction to the Origin (1859), p. 3. 



2 Life and Letters, i. p. 47. 3 Origin of Species (1st edit.) 1859, p. 201. 

 4 More Letters, n. p. 428. 



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