CONSCIOUS PROTECTIVE RESEMBLANCE. 539 



For instance, in those wonderful cases which are found so frequently 

 among insects, the habits of each species are so intimately correlated 

 with its abnormal structure and colouring, 4 that it is unreasonable to 

 believe that these characters have been developed independently by 

 different factors ; the latter by natural selection, and the former by the 

 " evolution of active mimicry," whatever that may mean. These 

 special structures cannot be accounted for by " active mimicry," neither 

 can they be explained by any general theory of internal or external 

 causes, for, as the late Mr. Romanes has well remarked, "Were it not 

 that some of Darwin's critics have overlooked the very point wherein 

 the great value of protective colouring as evidence of natural selection 

 consists, it would be needless to observe that it does so in the minute- 

 ness of the protective resemblance which in so many cases is presented. 

 Of course, where the resemblance is only very general, the phenomena 

 might be ascribed to mere coincidence, of which the instincts of the 

 animal have taken advantage. But in the measure that the resem- 

 blance becomes minutely detailed, the supposition of mere coincidence 

 is excluded, and the agency of some specially adaptive cause de- 

 monstrated " ('Darwin and after Darwin,' p. 318, notei. 



Thus a strong objection may be lodged against the whole suggestion 

 of active mimicry, as opposed to that of natural selection, in that 

 the former suggestion is essentially incomplete and cannot explain all 

 the facts of the case. Let us take the instance of the leaf-butterflies 

 of the genus Kallima, of which Mr. Distant says: "The partiality of 

 this insect for settling on dry and withered leaves appears a true 

 instance of active mimicry " (/. c, 1899, p. 531). 6 Upon the theory of 

 natural selection (granted the undisputed facts of variation and the 

 struggle for existence), it is easy to understand that any marked varia- 

 tions in the direction of leaf-like shapes or markings, which would 

 afford better concealment, would tend to be preserved and further 

 augmented, both by heredity and by the increased keenness of enemies, 

 until the present admirable resemblance had been arrived at. " But, 

 as Mr. Badenoch has well enquired, ' Of what avail would be the dis- 

 guise were the insect prone to settle upon a flower, or green leaf, or 

 other inappropriate surface ? ' " \l, c). Quite true ; and the fact that 

 the insect is not so inclined is readily explainable by the Darwinian 

 theory ; for it is clear that a much greater proportion of those 

 individuals which were prone to render themselves conspicuous by 

 settling on inappropriate surfaces would be picked off by their enemies 

 than of those which selected suitable resting places ; and thus, by a 

 gradual process of elimination, the progeny of those individuals, which 

 possessed a well-defined instinct to settle upon withered leaves, &c, 



