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376 TROPICAL NATUREtion, and what may be termed male selection, will tend togive them the advantage in the struggle for existence, andthus the fullest plumage and the finest colours will be transmitted,and tend to advance in each succeeding generation.The fullTheory of Display of Ornaments by Malesand interesting account given by Mr. Darwin ofthe colours and habits of male and female birds (Descent ofMan, chaps, xiii. and xiv.), proves that in most, if not inall cases, the male birds fully display their ornamental plumagebefore the females or in rivalry with each other ;but onthe essential point of whether the female's choice is determinedby minute differences in these ornaments or in theircolours, there appears to be an entire absence of evidence.In the section on " Preference for particular Males by theFemales," the facts quoted show indifference to colour, exceptthat some colour similar to their own seems to be preferred.But in the case of the hen canary who chose a greenfinch inpreference to either chaffinch or goldfinch, gay colours hadevidently no preponderating attraction. There is some evidenceadduced that female birds may, and probably do,choose their mates, but none whatever that the choice isdetermined by difference of colour and no less than three;eminent breeders informed Mr. Darwin that they " did notbelieve that the females prefer certain males on account ofthe beauty of their plumage." Again, Mr. Darwin himselfsays " As a : general rule colour appears to have little influenceon the pairing of pigeons." The oft-quoted case of SirR. Heron's pea-hens, which preferred an '"old pied cock" tothose normally coloured, is a very unfortunate one, becausepied birds are just those that are not favoured in a state ofnature, or the breeds of wild animals would become as variedand mottled as our domestic varieties. If such irregularfancies were not rare exceptions, the production of definitecolours and patterns by the choice of the female birds, or inany other way, would be impossible.There remains, however, to be accounted for, the remarkablefact of the display by the male of each species of itspeculiar beauties of plumage and colour a display which Mr.