( cxvii ) 



they represent the highest achievement of natural selection in 

 the protective colours of insects. If these variable colours 

 represented the beginnings of ordinary fixed colour variations 

 the species would lose and not gain by the change. The essence 

 of the protective value is the power of being concealed in each of 

 several different environments, and hereditary transmission of 

 the results would only injure the individuals of the next 

 generation. The intricacy of the processes by which the 

 stimulus gives rise to each appropriate colour-effect is no 

 difficulty to the interpretation based on natural selection — 

 "an agency capable of dealing with complex physiological 

 relationships in precisely the same way that it deals with all 

 other kinds of variations." * 



The barren conception of " self-adaptation," — the hypothesis 

 that organisms possess a constitution which compels them to 

 react adaptively, breaks down when we find the adaptation is 

 only possible by means of a specialized and complex train of 

 physiological sequences. 



We must remember that the species we investigate are 

 " heirs of all the ages," thoroughly inured to experimental 

 research, past masters in the art of meeting by adaptive 

 response the infinite variety of stimulus provided by the 

 environment. If we remember this we shall always be on 

 our guard against a too hasty interpretation based on the 

 fundamental properties of protoplasm.! 



The hypothesis that organisms are so built that they must 

 produce useful variations, seems to be little more than the old 

 "internal developmental force," or "innate tendency towards 

 perfection," in a modern dress. Furthermore, a consideration of 

 the essential meaning of adaptation proves the futility of any 

 such attempt at explanation. The ultimate object of adapta- 

 tion is to obtain food, to escape enemies, or to subserve 

 reproduction. The most conspicuous adaptations manifested 

 by an individual are relative to the condition of the organic 

 environment with Avhich its contact is in many respects 



* Professor Meldola in " Nature," vol. xxxviii, 1888, p. 389. See also 

 Professor Meldola's Presidential Address in Proc. Ent. Soc. Lond., 1896, 

 pp. Ixx, Ixxi ; and the first scientific paper published by him, viz. Proc. 

 Zool. Soc. 1873, p. 153. 



t "Nature," vol. Ixxi, 1905, p. 244. 



