Volume 2

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.

    27/558 (page 9)
    It is not enough that the nutritive juices are assimilated; another chemical process is still required to perfect their animalization, and to retain them in their proper chemical condition for the purposes of the system. This third object is accomplished by the function of Respiration. Fourthly, several chemical products which are wanted in different parts of the economy are required to be formed by a peculiar set of organs, of which the intimate structure eludes observation; although we may perceive that in many instances, among the higher orders of beings, a special appa- ratus of tubes, sometimes spread over the surface of a mem- brane, at other times collected into distinct masses, is pro- vided for that purpose. These specific organs are termed glands; and the office performed by them, as well as by the simpler forms of structure above mentioned, is termed Secretion. Fifthly, similar processes of secretion are also employed to carry off from the blood such animal products as may have been formed or introduced into it, and may possess or have acquired noxious properties. The elimination of these materials, which is the office of the excretories, constitutes the function of Excretion. Sixthly, changes may take place in various parts of the body, both solid and fluid, rendering them unfit to remain in their present situation ; and measures are taken for the removal of these useless or noxious materials, by trans- ferring them to the general mass of circulating blood, so as either to be again usefully employed, or altogether dis- carded by excretion from the system. This object is accomplished by a peculiar set of vessels; and the function they perform is termed Absorption. Lastly, the conversion of the fluid nutriment into the solids of the body, and its immediate application to the purposes of the development of the organs, of their preser-