24 2 THEORIES OF MIMICRY 



superficial and deep-seated, and the only common bond 

 which can be established between the various elements 

 which make up the common effect is that they all co- 

 operate in producing superficial resemblance to some 

 other species. 



It is here shown that the changes wrought in a single 

 species are far from uniform. It will be shown later on 

 (see Sections 1 1 and 12, pages 250 and 261) that there is 

 frequently no uniformity in the methods made use of by 

 mimic and model, nor any uniformity between the various 

 mimics of the same model, nor between the different 

 members of a synaposematic group. These, too, often 

 have only one thing in common, and that inexplicable 

 except on a theory of Selection, viz. the subordination of 

 all these divergent methods to a single end the attain- 

 ment of a superficial resemblance. 



The arguments in this and the preceding Section are 

 equally powerful in support of the interpretation of 

 Protective Resemblances as due to Natural Selection. 



Again, Mimetic Resemblances are comparatively rarely 

 seen in more than one stage of insect life, and are, in the 

 great majority of cases, restricted to the final stage. In 

 all such species the total appearance presented by the 

 final stage, including mimetic resemblance, is prepared 

 for in the earlier stages, especially the larval. Not only 

 are the changes in question confined, as has been already 

 pointed out in this Section, to the parts, tissues, and 

 organs which influence the superficial appearance, but 

 they are also generally confined to the final stage of 

 insect life. During larval life the foods peculiar to the 

 locality are devoured and the material for the mimetic 

 stage is stored up. The larval and pupal stages are 

 together, in the great majority of cases, far longer than 

 the imaginal stage, and are no less, and, as regards food, 

 far more, subject to the direct action of the forces peculiar 

 to the locality. On what theory except Natural Selection 

 is it possible to explain the rigid limitation of these changes, 

 in so large a proportion of cases, to the final stage, and 

 their entire exclusion from the stages during which they 

 are, in the history of the individual, predetermined ? 



