The Riverside Natural History, Vol. 4: Birds (Classic Reprint) - Softcover

John Sterling Kingsley

Softcover

ISBN 10: 1330487907 ISBN 13: 9781330487907

Publisher: Forgotten Books, 2020

Synopsis

Excerpt from The Riverside Natural History, Vol. 4: Birds

As remarked above, the feather is formed on a dermal papilla. At an early stage such papillae arise above the surface Of the skin, each of which Is grooved longitudi nally on one side This median groove sends Off laterally numerous smaller ones in an obliquely upward direction, gradually becoming shallow er. The secretion of the papilla moulds in these furrows, and, when pushed upward by new formations below, dries and splits into a feather, consisting of a scape and disconnected lateral barbs. These imperfect feathers are called plumules, and, taken collectively, constitute the down. While the papilla from which these plumules were formed sinks later on into a pit or follicle of the skin, another crop of more perfect feathers starts from papillae at the bottom of pits which are situated at the intersections of numerous ridges of the skin (the latter without sudoriferous glands and sebaceous follicles). These papillae are more deeply grooved, and have, moreover, very Often a corresponding but slighter furrow on the Opposite side, from which originates a usually small extra feather, known as the after-shaft (hyporachis), and attached to the under side of the main shaft. These stronger and more perfect feathers, which are called contour feathers, consist of a central stem and a lateral 'web' on each Side. The former is composed of two parts, a lower, cylindr,ical and hollow portion, the quill proper, enclosing the papilla, which shrivels when the feather ceases to grow it merges into the terminal part, the shaft, which Is four-sided and solid, and from which spring two lateral sets of barbs or radii these have on their margins secondary processes, barbules, which by means of small hooks or barbicels interlock with the neighboring barbs, thus uniting them into continuous and elastic webs,' termed the inner or outer web, according to the relative position to the median line of the body.

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Edition details

• Publisher: Forgotten Books
• Publication date: 2020
• ISBN 10: 1330487907
• ISBN 13: 9781330487907
• Binding: Paperback
• Language: English
• Number of pages: 623