File:Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget (1834) (14592598237).jpg

Identifier: animalandvegetab01roge (find matches)
Title: Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget ..
Year: 1834 (1830s)
Authors: Roget, Peter Mark, 1779-1869
Subjects: Biology Physiology Plant physiology Natural theology
Publisher: London : W. Pickering
Contributing Library: University of California Libraries
Digitizing Sponsor: MSN

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n which they donot bend that the filaments of the feather haveto encounter the resistance and impulse of theair. It is here that strength is wanted, and it ishere that strength has been bestowed. On examining the assemblage of these lami-nated filaments still more minutely, we find thatthey appear to adhere to one another. As wecannot perceive that they are united by anyglutinous matter, it is evident that their con-nexion must be effected by some mechanisminvisible to the unassisted eye. By the aid ofthe microscope the mystery is unravelled, andwe discover the presence of a number of minutefibrils, arranged along the margin of the laminae,and fitted to catch upon and clasp one another,whenever the laminae are brought within a cer-tain distance. The fibrils of a feather from thewing of a goose are represented magnified at 570 THE MECHANICAL FUNCTIONS, a, a, b, b, Fig. 226, as they arise from the twosides of the edges of each lamina: they areexceedingly numerous, above a thousand being
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contained in the space of an inch ; and they areof two kinds, each kind having a different formand curvature. Those marked a, a, which arisefrom the side next to the extremity of the featherare branched or tufted, and bend downwards,while those marked b, b, proceeding from theother side of the lamina, or that nearest the rootof the feather, are shorter and firmer, and do notdivide into branches, but are hooked at the ex-tremities, and are directed upwards. When thetwo laminae are brought close to one another,the long, curved fibrils of the one being carriedover the short and straight fibrils of the other,both sets become entangled together; theircrooked ends fastening into one another, just asthe latch of a door falls into the cavity of thecatch which is fixed in the door-post to receive FEATHERS OF BIRDS. 571 it. The way in which this takes place will bereadily perceived by making a section of thevane of a feather across the laminae, and exa-mining with a good microscope their cut ed

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