XX INTRODUCTION, 



plus energy stored up in the larval stage and differentiated in the 

 pupal stage. It appears to be abundantly clear that the energy stored 

 up by the female larva has more outlets, so to speak, than that of the 

 males, and the formation of the ovaries and ova &c., really a large 

 part of the female imago, must absorb a very large percentage of such 

 energy. In some species, already referred to under the head of 

 "apterous and semiapterous females," the demand is so great as to 

 absorb even that part which normally goes to form the wing mem- 

 branes, scales &c., but apart from these extreme cases, the reproduc- 

 tive system normally makes a large call to which there is nothing 

 corresponding in the male. The surplus energy in the male must 

 therefore be utilised in other directions, of which ornament, as ex- 

 hibited by colour etc., appears most certainly to be one, and it is 

 remarkable that in a very large percentage of cases, as in Lyccena 

 icdrus, corydon and bellargus only the most robust female specimens 

 are tinged or affected with the blue colouring which we have now 

 grown accustomed to look upon as particularly connected with the 

 male. The female helice var. of Colias edusa may be looked upon also 

 as a female form in which there is a minimum of surplus energy to 

 form pigment. I would also notice that the only male in which I 

 have observed a tendency to this colour was small and undersized 

 evidently a product of constitutional conditions. With regard to 

 colour as a secondary sexual character Geddes and Thomson write : 

 " That the male is usually brighter than the female is an acknow- 

 ledged fact." This certainly is so in lepidoptera. They then say : 

 " But pigments of many kinds are physiologically regarded as of the 

 nature of waste products." This also appears to be so in lepidoptera, 

 restricting the term " waste products " to that " surplus energy " 

 which is not utilised in the muscular and sensory structure of the 

 organism. " Abundance of such pigments, and richness of variety in 

 related series, point to pre-eminent activity of chemical processes in 

 the animals which possess them. Technically expressed, abundant 

 pigments are expressions of intense metabolism. But predominant 

 activity has been already seen to be characteristic of the male sex ; 

 these bright colours, then, are often natural to maleness. In a literal 

 sense animals put on beauty for ashes, and the males more so because 

 they are males, and not primarily for any other reason whatever." 

 These authors appear to me to have traced the actual facts through to 

 their last degree and then failed, and their last statement is altogether 

 un-understandable, and begs the whole question. The cause of 

 " secondary sexual characters " seems to be neglected for there must 

 be a reason underlying the whole which shall explain the origin of 

 these characters better than stating " that the males put on beauty 

 because they are males." Is their own suggestion, indeed, that the 

 cause of these characters is to be found in a physiological explanation 

 quite compatible with such a statement ? If the pigments are of the 

 nature of " waste products," is the reason not to be sought here ? I do 

 not doubt that the inherent tendency of these characters to develop 

 in the male is present, but the " surplus energy " or " waste products " 

 in the male organisation, compared with those in the female, seem to 

 me the primary cause and to point to the fact that the material utilised 

 for the development of ova &c., in the female, is modified in the male 



