8r2 THE CAUSES WHICH PEOPAGATE 



Generally speaking, sober browns, blacks (Plate IV., Fig. 12), 

 clilorophyle tints, and aerial purples are the pig-ments we notice 

 i>n protected sui-faces, and this is well exemplified in butterflies 

 mid moths. On the other hand, those more floi'id hues specially 

 designed to evoke the passions consist mainly in white and its 

 prismatic elements. These, which may be regarded as primitive 

 when compared with the more composite or protective colouring, 

 are not always strikingly present ; and we might surmise 

 tluit individuals possessing such beauty in the highest degree 

 require, on account of their apathy, this greater stimulus from 

 tlii^ solar beam to fulfil their drama in the economy of life, or 

 that they stand higher in the scale in respect to organisation. 

 The first hypothesis, I may remark, appears true, in regard to 

 the brighter-coloured Lepidoptera, as these seem certainly to want 

 auditory organs, or to have them less perfectly formed. W e 

 may also regard such primitive colour as in measure an index to 

 the ocular organs and nerves that receive its impression, for why, 

 abstractly, should one insect be excited by red, another by 

 blue, and a third by yellow, or white, unless predisposition for 

 such be present? Fritz Muller, indeed, assures us certain but- 

 terflies will only visit blossoms of a certain primitive tint; and if 

 this be correct, we should be inclined to consider it a manifesta- 

 tion of this capacity and preference for a ruling colour ray. 



Primitive and attractive colouring, then, in Lepidoptera is 

 present in a greater or less degree in the species and individuals 

 replacing the more composite grounds ; while, as regards differ- 

 entiation of the sexes, it characterises males in butterflies, though 

 not invariably, and in moths it is often most marked in the 

 female sex, an anomaly evidently resulting from a design to 

 render them visible at dusk in the majority of cases. In these 

 groups sometimes the wings are wholly different m the sexes, as 

 for instance, female white, male brown ; or female greenish, male 

 fnhous or yellow; or female yellow, male inclining to orange; 

 anil vice versa'. We will tabulate a few striking cases instancing 

 the genera or species where they occur. 



COMPLETE COLOUR DIFFERENTIATION. 



BiTTEKrLiES. Moths. 



. I Male, brown I -n • v, f Hypogynia. 



il*emalc. -white J " L opilosonia. 



