File:Key to North American birds. Containing a concise account of every species of living and fossil bird at present known from the continent north of the Mexican and United States boundary, inclusive of (14750917042).jpg

Identifier: keytonorthameric00coue (find matches)
Title: Key to North American birds. Containing a concise account of every species of living and fossil bird at present known from the continent north of the Mexican and United States boundary, inclusive of Greenland and lower California, with which are incorporated General ornithology: an outline of the structure and classification of birds; and Field ornithology, a manual of collecting, preparing, and preserving birds
Year: 1890 (1890s)
Authors: Coues, Elliott, 1842-1899
Subjects: Birds -- North America Birds -- Collection and preservation
Publisher: Boston, Estes and Lauriat
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: Biodiversity Heritage Library

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rooves.If, therefore, the hollow cone of gelatine, removed from its mould, were stretched from within;or if its thinnest parts became weak by drying ; it would tend to give way, along the inferiormedian line, opposite the rod-like cast of the dorsal median groove and between the ends of EXTERNAL PARTS OF BIRDS. — FEATHERS. 83 the casts of the lateral furrows, as well as between each of the minor grooves, and the hollowcone would expand into a flat feather-like structure with a median shaft, as a vane formedof barbs and barbules. In point of fact, in the development of a feather such a cast of thedermal papilla is formed, though not in gelatine, but in the homy epidermic layer developedupon the mould, and, as this is thrust outward, it opens out in the manner just described.After a certain period of growth the papilla of the feather ceases to be grooved, and a continu-ous homy cylinder is formed, which constitutes the quill. (Introd. Classif. Anim., p. 71.) ^14. ^^^ ^Ht-^ ^w^ 0080000
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Fig. 18. — Symmetrical Figrures from Forming Feathers; a, dove; 6, turkey. — In the summer of1869, whilst examining the feather capsule of a nestling dove, the microscopic slide was suddenly covered with amultitude of exquisite forms. . . . The next day my German farmer climbed to the doves nest and procured a fewmore pin-feathers. Some of these were cut into fine shreds, rubbed in a drop of water, and placed under themicroscope. In a short period the figures of yesterday were again before me. From the cut surfaces of theportions of the pin-feathers I had placed under the lens, granules appeared to stream forth like blood, coveringthe microscopic slide in countless numbers. Mingled with these were numerous larger cells of a globular or ovalform, having a transparent centre. These and the granules gave to the water a slightly glutinous consistency.As the fluids on the glass dried, lines at different angles shot across the slide, looking much as though anunseen camels hair pencil ha

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