. Animal physiology. Physiology, Comparative; Physiology, Comparative. 24 STRUCTURE OF THE Fig. 1.—Hydra, or Fresh-water Polype. its arms in search of its food, which consists of minute aquatic worms and insects. These are securely laid hold of by one or more of the arms, and are drawn into the mouth, a, which leads to the stomach or general cavity of the body, in which they are digested, and from the walls of which the nutritious portions are absorbed. A kind of circulation, or flow of nutritious fluid through channels, appears to take place even in this simple animal, for the conveya
. Animal physiology. Physiology, Comparative; Physiology, Comparative. 24 STRUCTURE OF THE Fig. 1.—Hydra, or Fresh-water Polype. its arms in search of its food, which consists of minute aquatic worms and insects. These are securely laid hold of by one or more of the arms, and are drawn into the mouth, a, which leads to the stomach or general cavity of the body, in which they are digested, and from the walls of which the nutritious portions are absorbed. A kind of circulation, or flow of nutritious fluid through channels, appears to take place even in this simple animal, for the conveyance of nourishment to the arms. The portions of the food which are not capable of being digested, are cast out through the mouth; but in the higher po- lypes, as in all the more com- plex animals, a second aperture is provided for this purpose. — Now, that the lining mem- brane of the stomach is nothing else than an inward prolon- gation of that which covers its surface, is evident from a very curious experiment which has been many times performed upon this little animal, with the same result. It may actually be turned inside-out, as we should turn a glove or a stocking; so that the lining of the stomach shall become the external cover- ing, and the external membrane the lining of the stomach ; and yet the functions of the animal seem to go on as if they had not been in the least disturbed. 15. All the chief functions which have been described as taking place in plants, are performed by animals also, besides those which are peculiar to the latter. Thus, the nutriment which has been absorbed in the state which maybe called the raw mate- rial, has to be converted into a substance fit for the nourishment of the tissues, and capable of being appropriated by them; this process, resembling the " elaboration of the sap" in plants, is termed assimilation (or rendering-like). This assimilated fluid. Please note that these images are extracted from scanned page images that
Size: 1281px × 1950px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcarpenterwilliambenja, bookcentury1800, bookdecade1840
