CHAP. X.] SEXUAL SELECTION. 315 



of the body and in certain hues is first required, and then perhaps, in 

 the case of birds, the female might choose the successive improvements 

 as they occurred ; though unless other variations were altogether pre 

 vented, it seems just as likely that they would mar the effect the law 

 of development of colour was tending to produce.&quot; 



&quot; The other objection is, that there are signs of such a tendency, 

 which, taken in connection with the cases of caterpillars, of shells, and 

 other very low organisms, may cover the whole ground in the case of 

 insects, and render sexual selection of colour as unnecessary as it is 

 unsupported by direct evidence. In many islands of the Malay Archi 

 pelago, species of widely different genera of butterflies differ, in precisely 

 the same way [the italics are ours] as to colour or form, from allied 

 species in other islands. The same thing occurs to a less degree in 

 other parts of the world. Here we have indications of some local 

 modifying influence which is certainly not sexual selection. So, the 

 production in the males only of certain butterflies of a peculiar neura- 

 tion of the wings, of differently formed legs, and especially of groups 

 of peculiarly formed scales only to be detected by microscopical exami 

 nation, indicate the existence of some laws of development capable of 

 differentiating the sexes other than sexual selection.&quot; 



But it is not only insects, but also birds, which present 

 similar parallel variations connected with locality, and cer 

 tainly not due to sexual selection. The element of caprice, 

 which Mr. Wallace urges as an objection, is admitted by Mr. 

 Darwin himself, for he speaks of sexual selection as depend 

 ing &quot; on an element eminently liable to change namely, the 

 taste or admiration of the female &quot; (vol. ii. p. 192). 



Mr. Wallace himself accounts for the brilliant colours of 

 caterpillars and many birds in another way. The His hypo- 

 caterpillars which are distasteful must have gained, colour, 

 if &quot; some outward sign indicated to their would-be destroyer 

 that its prey was a disgusting morsel.&quot; As to birds, he 

 believes that brilliance of plumage is developed where not 

 hurtful, and that the generally more sober plumage of the 

 hens has been produced by natural selection killing off the 

 more brilliant ones exposed during incubation to trying 

 conditions. 



Now as Mr. Wallace disposes of Mr. Darwin s views by 

 his objections, so Mr. Darwin s remarks tend to refute 

 Mr. Wallace s positions, and the result seems to point to 



