452 
The Progress of the 
[October, 
Selection would here aCt, as in birds, in perpetuating the 
strongest and most vigorous males, and, as these would 
usually be the most highly coloured of their race, the same 
results would be produced as regards the intensification and 
variation of colour in the one case as in the other.” 
But now comes the question, why, if the females are not 
attracted by the beauty of their mates, do the males make 
such a striking display of the brilliance of their plumage ? 
Of the faCt of such display there can be no doubt whatever. 
But the main point — the question whether the choice of the 
females is at all influenced by shades of colour or slight 
differences in design—is totally unproven. There is no 
evidence that the females admire, or even notice, the dis- 
play. “ The hen, the turkey, and the pea-fowl go on 
feeding while the male is displaying his finery.” The flut- 
terings and dancings, the erection of tails and crests, are 
probably a mere result of the exuberant energy with which 
the male at this season is overcharged. 
Mr. Wallace, however, founds his strongest argument on 
the interference and opposition of Natural and Sexual 
Selection. He says — “Natural Selection, or the survival 
of the fittest, aCts perpetually, and on an enormous scale. 
Taking the offspring of each pair of birds as on the average 
only six annually, one-third of these at most will be pre- 
served, whilst the two-thirds which are least fitted will die. 
At intervals of a few years, whenever unfavourable condi- 
tions occur, five-sixths, nine-tenths, or even a greater pro- 
portion of the whole yearly production, are weeded out, 
leaving only the most perfect and best adapted to survive. 
Now, unless these survivors are on the whole the most 
ornamental, this rigid Natural Selection must neutralise 
and destroy any influence that may be exerted by Female 
Selection. The utmost that can be claimed for the latter is 
that a small fraction of the least ornamented do not obtain 
mates, while a few of the most ornamented may leave more 
than the average number of offspring. Unless, therefore, 
there is the strictest correlation between ornament and 
general perfection, the more brightly coloured or ornamented 
varieties can obtain no permanent advantage ; and if there 
is (as I maintain) such a correlation, then the sexual selec- 
tion of colour or ornament, for which there is little or no 
evidence, becomes needless, because Natural Selection — 
which is an admitted vera causa — will itself produce all the 
results. In the case of butterflies the argument becomes 
even stronger, because the fertility is so much greater than 
in birds, and the weeding out of the unfit takes place, to a great 
