374 TROPICAL NATURE 



white companions ? This seems a more probable supposition 

 than the altogether hypothetical choice of the female, some- 

 times exercised in favour of and sometimes against every new 

 variety of colour in her partner. 



A strictly analogous case is that of the glow-worm, whose 

 light, as originally suggested by Mr. Belt, is admitted to 

 be a warning of its uneatability to insectivorous nocturnal 

 animals. The male, having wings, does not require this 

 protection. In the tropics the number of nocturnal insect- 

 ivorous birds and bats is very much greater, hence winged 

 species possess the light, as they would otherwise be eaten by 

 mistake for more savoury insects; and it may be that the 

 luminous Elateridse of the tropics really mimic the true fire- 

 flies (Lampyridse), which are uneatable. This is the more 

 probable, as the Elateridae, in the great majority of species, 

 have brown or protective colours, and are therefore certainly 

 palatable to insectivorous animals. 



Origin of the Ornamental Plumage of Male Birds 



We now come to such wonderful developments of plum- 

 age and colour as are exhibited by the peacock and the 

 Argus-pheasant; and I may here mention that it was the case 

 of the latter bird, as fully discussed by Mr. Darwin, which 

 first shook my belief in " sexual," or more properly " female " 

 selection. The long series of gradations by which the beauti- 

 fully shaded ocelli on the secondary wing-feathers of this bird 

 have been produced, are clearly traced out, the result being a 

 set of markings so exquisitely shaded as to represent " balls 

 lying loose within sockets " purely artificial objects of which 

 these birds could have no possible experience. That this 

 result should have been attained, through thousands and tens 

 of thousands of female birds all preferring those males whose 

 markings varied slightly in this one direction, this uniformity 

 of choice continuing through thousands and tens of thousands 

 of 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 leave 

 offspring, the actual result seems quite impossible of attain- 

 ment by such means. 



