Page:The Zoologist, 4th series, vol 3 (1899).djvu/576

546 immediately from the egg like Partridges, &c, and are withdrawn to some flinty field by the dam, where they skulk among the stones, which are their best security, for their feathers are so exactly of the colour of our grey-spotted flints, that the most exact observer, unless he catches the eye of the young bird, may be eluded." The same observer records an illustration of active mimicry in a Willow-Wren:—"This bird a friend and myself had observed as she sat in her nest, but were particularly careful not to disturb her, though we saw she eyed us with some degree of jealousy. Some days after, as we passed that way, we were desirous of remarking how this brood went on; but no nest could be found, till I happened to take up a large bundle of long green moss, as it were carelessly thrown over the nest, in order to dodge the eye of any impertinent intruder."

Active mimicry, rather than natural selection per se, appears very largely to account for the assimilative colouration of birds' eggs to their nests or environment. Without recapitulating all the evidence which can be readily obtained from so many sources—either by observation, or reference to much illustrated literature—we may safely conclude, with Mr. Wallace, that on the whole, "while white eggs are conspicuous, and therefore especially liable to attack by egg-eating animals, they are concealed from observation in many and various ways." This is a very important consideration before we proceed farther. We find a great number of white or prominent eggs, apparently unaffected by "natural selection," but preserved by intelligent concealment, which is only a form or phase of what we have noted before, and to what will be referred to again on this very matter of birds' eggs, as active mimicry. If the process of natural selection was to be applied, according to a very frequent method, as universal, then birds arising from these white and prominent eggs would seem in course of time to be doomed to destruction. But we find nothing of the kind. Natural selection is here replaced by the evolution of intelligence or active mimicry. True, it may be