PDF - Wallace Online

374 TROPICAL NATUREwhite companions ? This seems a more probable suppositionthan the altogether hypotheticalchoice of the female, sometimesexercised in favour of and sometimes against every newvariety of colour in her partner.A strictly analogous case is that of the glow-worm, whoselight,as originally suggested by Mr. Belt, is admitted tobe a warning of its uneatability to insectivorous nocturnalanimals. The male, having wings, does not require thisprotection.In the tropics the number of nocturnal insectivorousbirds and bats is very much greater, hence wingedspecies possess the light, as they would otherwise be eaten bybe that themistake for more savoury insects; and itmayluminous Elateridse of the tropics really mimic the true fireflies(Lampyridse), which are uneatable. This is the moreprobable, as the Elateridae, in the great majority of species,have brown or protective colours, and are therefore certainlypalatable to insectivorous animals.Origin of the Ornamental Plumage of Male BirdsWe now come to such wonderful developments of plumageand colour as are exhibited by the peacock and theArgus-pheasant; and I may here mention that it was the caseof the latter bird, as fully discussed by Mr. Darwin, whichfirst shook my belief in " sexual," or more" "properly femaleselection. The long series of gradations by which the beautifullyshaded ocelli on the secondary wing-feathers of this birdhave been produced, are clearly traced out, the result being aset of markings so exquisitely shaded as to represent " balls"lying loose within sockets purely artificial objects of whichthese birds could have no possible experience. That thisresult should have been attained, through thousands and tensof thousands of female birds all preferring those males whosemarkings varied slightly in this one direction, this uniformityof choice continuing through thousands and tens of thousandsof generations, is to me absolutely incredible. And when,further, we remember that those which did not so vary'would also, according to all the evidence, find mates and leaveoffspring, the actual result seems quite impossible of attainmentby such means.