File:Animal and vegetable physiology, considered with reference to natural theology (1836) (14761599291).jpg

Identifier: animalvegetable01roge (find matches)
Title: Animal and vegetable physiology, considered with reference to natural theology
Year: 1836 (1830s)
Authors: Roget, Peter Mark, 1779-1869
Subjects: Biology Physiology Plant physiology Natural theology
Publisher: Philadelphia, Carey, Lea & Blanchard
Contributing Library: NCSU Libraries
Digitizing Sponsor: NCSU Libraries

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fila-ments of the feather have to encounter the resistance andimpulse of the air. It is here that strength is wanted, andit is here that strength has been bestowed. On examining the assemblage of these laminated filamentsstill more minutely, we find that they appear to adhere toone another. As we cannot perceive that they are unitedby any glutinous matter, it is evident that their connexionmust be effected by some mechanism invisible to the unas-sisted eye. By the aid of the microscope, the mystery isunravelled, and we discover the presence of a number ofminute fibrils, arranged along the margin of the laminas, andfitted to catch upon and clasp one another, whenever the la-minae are brought w^ithin a certain distance. The fibrils ofa feather from the wing of a goose are represented magnified FEATHERS OF BIRDS. 393 at a, a, b, b, Fig. 226, as they arise from the two sides ofthe edges of each lamina: they are exceedingly numerous,above a thousand being contained in the space of an inch;
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and they are of two kinds, each kind having a different formand curvature. Those marked a, a, which arise from theside next to the extremity of the feather are branched ortufted, and bend downwards, while those marked b, b, pro-ceeding from the other side of the lamina, or that nearestthe root of the feather, are shorter and firmer, and do notdivide into branches, but are hooked at the extremities, andIfire directed upwards. When the two laminae are broughtclose to one another, the long, curved fibrils of the one be-ing carried over the short and straight fibrils of the other,both sets becom.e entangled together; their crooked endsfastening into one another, just as the latch of a door fallsinto the cavity of the catch which is fixed in the door-postto receive it. The way in which this takes place will bereadily perceived by making a section of the vane of a fea-ther across the lam.ina^, and examining, with a good micro-scope, their cut edges, while they are gently separated fromone a

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