. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. Fig. 209. Intake mechanism of plants, a, young seedling, showing root hairs; b, part of a section through a young root, showing some of the superficial cells growing into root hairs. A thin layer of cytoplasm (dotted) lines the cell wall and encloses the cell sap. (After Brown.) Like plants, animals depend upon osmotic intake through thin cell membranes, cellular middlemen between indispensable food and the animal body, which cannot remain without harm on
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. Fig. 209. Intake mechanism of plants, a, young seedling, showing root hairs; b, part of a section through a young root, showing some of the superficial cells growing into root hairs. A thin layer of cytoplasm (dotted) lines the cell wall and encloses the cell sap. (After Brown.) Like plants, animals depend upon osmotic intake through thin cell membranes, cellular middlemen between indispensable food and the animal body, which cannot remain without harm on the outside of bodies of ad- venturous locomotor organisms. The intake cells of animals, as well as of plants, must be protected from mechanical injury and from drying up, while their possessors are seeking food. This explains the evolution in loco- motor animals of the digestive tube, an enclosed passage-way arranged for one-way traffic and paved with thin-walled absorbing cells that correspond to the osmotic root hairs of plants. In one sense the digestive tube is simply an infolding of the integument, making a protected subway where food admitted at the entrance is exposed to intake cells, which proceed to do their osmotic duty in security without drying up while being trans- ported to fresh fields of food supply. Thus, in a way, an animal may be regarded as a plant turned Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Walter, Herbert Eugene, b. 1867; Sayles, Leonard Perkins, 1902-. New York : Macmillan Co.
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Keywords: ., bookcentury1900, booksubjectanatomycomparative, booksubjectverte
