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63

Birds, Chap. 13

was greatly disappointed by finding that at its appearance, for the ocelli appeared seemed flat or even concave. Mr. Gould, however, soon made the case clear to me for he had seen and made a sketch drawing of a male in full display. At such times the long secondary feather in both wings are then vertically erected & expanded; and these together with the enormously elongated tail-feathers form make a grand semicircular upright fan. Now as soon as the wing feathers are held upright, and the light shines on them from above, the full effect of shading comes out; each ocellus at once becoming and resembling the ornament called a ball and socket. These feathers have been shown to several artists, who

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have all expressed the highest admiration at their perfect shading. It may well be asked, how it can it be conceived that such chaste & artistically shaded ornaments could have been formed by means of sexual selection? But it will be convenient to defer giving an answer to this question, until we treat of the principle of gradation, when we shall see that an answer is at once suggested by the comparison of the several feathers of the wings.) of the

The short primary or first wing-feathers, which in most gallinaceous birds are uniformly coloured, are in the Argus-pheasant all not less wonderful objects than the secondary feathers. They are of a

[Descent 2: 91-2: "But when I looked at the specimen in the British Museum, which is mounted with the wings expanded and trailing downwards, I was greatly disappointed, for the ocelli appeared flat or even concave. Mr. Gould, however, soon made the case clear to me, for he had made a drawing of a male whilst he was displaying himself. At such times the long secondary feathers in both wings are vertically erected and expanded; and these, together with the enormously elongated tail-feathers, make a grand semicircular upright fan. Now as soon as the wing-feathers are held in this position, and the light shines on them from above, the full effect of the shading comes out, and each ocellus at once resembles the ornament called a ball and socket. These feathers have been shewn to several artists, and all have expressed their admiration at the perfect shading.
It may well be asked, could such artistically-shaded ornaments have been formed by means of sexual selection? But it will be convenient to defer giving an answer to this question until we treat in the next chapter of the principle of gradation.
The primary wing-feathers, which in most gallinaceous birds are uniformly coloured, are in the Argus pheasant not less wonderful objects than the secondary wing-feathers. They are of a soft brown tint with numerous dark spots, each of which consists of two or three black dots with a surrounding dark zone."]