Volume 1

Animal and vegetable physiology, considered with reference to natural theology / by Peter Mark Roget.

  • Roget, Peter Mark, 1779-1869.
Date:
1867
Catalogue details

Licence: Public Domain Mark

Credit: Animal and vegetable physiology, considered with reference to natural theology / by Peter Mark Roget. Source: Wellcome Collection.

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    ness,* and through which it cannot transude. Hence the whole mass of the fat, which is formed of an aggregation of these vesicles, has not the appearance of being fluid, but seems to be composed of small grains united by mem- branous investments into larger masses ; a structure pecu- liarly adapted to the purposes of a soft cushion, as it re- tains only a small share of elasticity ; and, while it at the same time possesses the absolute incompressibility of fluids, it admits readily, but only to a certain limited extent, of displacement by external pressure. These mechanical properties render it a peculiarly ser- viceable material for filling up the spaces left between adjacent organs, whose forms are not perfectly adapted to each other; and especially those whose functions require them to be in frequent or continual motion. This is exemplified more particularly in the heart and the great vessels connected with it; between which we accordingly t find a large quantity of fat interposed. Different parts of ; the alimentary tube are, in like manner, protected from : friction and from mechanical strains, which might have I occurred from mutual displacement, by cushions of fat, in- terposed between their folds, and which adapt themselves to their various changes of form and to their different movements. The ball of the eye obtains a similar protec- tion by resting on a mass of fat, which occupies the remain- ing space at the bottom of the orbit, and facilitates the quick and sudden movements required of that organ. The same design is apparent in the granules of fat which occur in the cavities of most of the joints, and wdiich being inter- Dosed between the terminal cartilages, limit their extent of contact, diminish their friction, and b}^ equalizing the pres- ;ures facilitate their relative motion. * Dr. Monro estimated their diameter at between the 800th and 00th of an inch. But their size varies in different animals.