THE SEXES AND SEXUAL SELECTION. II 



due to natural selection, which has eliminated those which 

 persisted to the death in being gay. He points out that 

 conspicuousness during incubation would be dangerous and 

 fatal ; the more conspicuous have, he thinks, been picked off 

 their nests by hawks, foxes, and the like, and hence only the 

 sober-coloured females now remain. Darwin starts from 

 inconspicuous forms, and derives gorgeous males by sexual 

 selection ; Wallace starts from conspicuous forms, and derives 

 the sober females by natural selection ; the former trusts to the 

 preservation of beauty, the latter to its extinction. In 1773, 

 the Hon. Daines Barrington, a naturalist still remembered as 

 the correspondent of Gilbert White, suggested that singing- 

 birds were small, and hen-birds mute for safety's sake. This 

 suggestion Wallace has repeated and elaborated in reference 

 especially to birds and insects. The female butterfly, exposed 

 to danger during egg-laying, is frequently dull and inconspicuous 

 compared with her mate. The original brightness has been 

 forfeited by the sex as a ransom for life. Female birds in open 

 nests are similarly, in many cases, coloured like their sur- 

 roundings ; while in those of birds where the nests are domed 

 or covered, the plumage is gay in both sexes. At the same 

 time, Wallace allows original importance to sexual selection on 

 both sides in evolving bright colours and the like. We need 

 not repeat Darwin's reply to Wallace's objections, as the reader 

 will at once recognise considerable force in each position."^ 



(b) Brooks has called attention to the sexual differences in 

 lizards, where the females do not incubate ; or in fishes, where 

 the females are even less exposed to danger than the males ; 

 or in domesticated birds, where, though all danger is removed, 

 the males are still the more conspicuous and diversified sex. 



* Since the above was written, Mr Wallace's book on "Darwinism" has 

 been published, in which the author proceeds yet further in his destructive 

 criticism of Darwin's sexual selection. The phenomena of male ornament 

 are discussed, and summed up as being " due to the general laws of growth 

 and development," and such that it is "unnecessary to call to our aid so hypo- 

 thetical a cause as the cumulative action of female preference." Or again, 

 " if ornament is the natural product and direct outcome of superabundant 

 health and vigour, then no other mode of selection is needed to account 

 for the presence of such ornament." These conclusions are not only 

 important in relation to Darwin's theory, but obviously open up the pos- 

 sibility of interpreting not only these as the "natural product and direct 

 outcome of constitutional conditions " (j-<?(?chap. xxi.) but many other features 

 also. This consideration, however, is fraught with serious consequences to 

 Mr Wallace's main thesis. 



