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 therefore, that such violent movements as are here imagined might have this effect, and thus, though excited originally by rage—or some high state of emotion—only, might be persisted in and increased through experience of their efficacy. But if this does ever happen, may we not have here the origin—or one of the origins—of those undoubted displays made by the male bird to the female, on which the theory of sexual selection is chiefly based? That the male birds should, in the beginning, have consciously displayed their plumage, in however slight a manner, to the females, with an idea of it striking them, seems improbable, and, even if we might assume the intelligence requisite for this, the theory of sexual selection supposes the beauty of the plumage to have been gained by the display of it, not that the display has been founded upon the beauty. Then what should first lead a bird of dull plumage consciously to display this plumage before the female? A mere habit of the male, increased and perfected by the selective agency of the female (as this is explained by Darwin), has hitherto—as far as I know—been considered a sufficient explanation of the origin and early stages of such displays as are now made by the great bustard, the various birds of paradise, or the argus pheasant. But if we can show a likelihood as to how this habit has arisen we are, at least, a step farther forward, even if a slight difficulty has not thereby been removed.

Now, with regard to these wheatears, it will, I think, be admitted that the little frenzies of the male birds—as I have described them—were of a very marked, and, indeed, extraordinary nature, and