578 PROF. E. B. POUIiTOTf : ]S^A.TTJRAL SELECTIOJf 



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 

 11 and 12, pages 585 to 602) 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 synapopematic 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 attainment of 

 a superficial resemblance. 



The arguments in this and the preceding Section are equally 

 powerful in support of the interpretation of protective resem- 

 blances 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 appearances presented by the final stnge, includ- 

 ing mimetic resemblance?, are prepared for in the earlier stages, 

 and especially the larval. Not only are the changes in question 

 confined, as has been pointed out in the earlier parts of this 

 Section, to the parts, tissues, and organs which affect the super- 

 ficial 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 or 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 in 

 which they are, in the history of the individual, predetermined ? 



(8) Conditions of a Species in any Locality are chiejly 

 determined hy its Habits and Life-history. 



In the last Section it was shown that there is no uniformity 

 in the effects produced in any locality. In this Section it will be 

 made clear that there is no uniformity in the forces which, by 



