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 instance, in his very interesting work, "The Naturalist in La Plata," after bringing forward a number of cases of curious dance-movements (or of song), performed by birds, and which are, in his opinion, not to be explained on the theory of sexual selection, says, in regard to other cases brought forward by Darwin in support of that theory:

"How unfair the argument is, based on these carefully selected cases gathered from all regions of the globe, and often not properly reported, is seen when we turn from the book to nature, and closely consider the habits and actions of all the species inhabiting any one district!"

Now, had Darwin been of opinion that antics performed by a bird which could not, or could not easily, be explained by his theory, were fatal to it in other cases—if he had thought that the one was inconsistent with the other—then, no doubt, it would have been unfair on his part to have marshalled the affirmative evidence without concerning himself with the negative. But why should he have held that view, or on what good grounds can such a view be maintained? As well might it be argued—so it appears to me—that woollen or other goods could only have been produced through the action of the loom, or some such special machinery. But let the wool be there, and it can be worked up in various ways. Mr Hudson would account for all such displays or exhibitions by "a universal joyous instinct" present throughout nature, but to which birds are more subject than mammals. I do not dispute the instinct—or rather, perhaps, the emotion—or that some of