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. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. CCELENTERATES 197 tion from the cnidoblast. The '' explosion " of the cell results in the ejection of the dart and injection of the poisonous acid into the victim. The animal hit by a number of these darts is usually so paralyzed that further resistance is impossible. Food Taking. — The tentacles then reach out like arms, grasp the food, and bend over with it toward the mouth. Digestion takes place by means of a fluid given out from some of the cells near the mouth. After the food has

. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. CCELENTERATES 197 tion from the cnidoblast. The '' explosion " of the cell results in the ejection of the dart and injection of the poisonous acid into the victim. The animal hit by a number of these darts is usually so paralyzed that further resistance is impossible. Food Taking. — The tentacles then reach out like arms, grasp the food, and bend over with it toward the mouth. Digestion takes place by means of a fluid given out from some of the cells near the mouth. After the food has  Stock Photo
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Paul Fearn / Alamy Stock Photo

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RCREB1

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7.2 MB (200.6 KB Compressed download)

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1391 x 1797 px | 23.6 x 30.4 cm | 9.3 x 12 inches | 150dpi

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. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. CCELENTERATES 197 tion from the cnidoblast. The '' explosion " of the cell results in the ejection of the dart and injection of the poisonous acid into the victim. The animal hit by a number of these darts is usually so paralyzed that further resistance is impossible. Food Taking. — The tentacles then reach out like arms, grasp the food, and bend over with it toward the mouth. Digestion takes place by means of a fluid given out from some of the cells near the mouth. After the food has been partially digested, many of the cells lining the cavity put out pseudopodia, which grasp and ingest the food particles. The tentacles are hollow, and the body cavity extends into them. From this cavit}^ food may be taken up by cells in all parts of the body near where it is to be used. The outer layer of this little animal does not digest the food, but receives some of it already digested from the inner t -^ ^- i .• r u ^ ^ u ^ i. ** u ^ ^ Longitudinal section of a hydra; b, bud; 6a, attached layer. This food passes ^^d; m, mouth; ov, ovary; sp, spermary holding r „ . 1, • 1 , sperm cells. irom cell to cell, as m plants, by osmosis. The oxygen necessary to oxidize the food is passed through the body wall, seemingly at any point, for there are no organs for respiration (breathing). Division of Labor. — We have here then a step toward a more complex animal, for certain parts of the body here have certain work to perform. The outside for sensation, offense and defense, and for movement and coordination of parts, and the layer form- ing the interior of the bag for taking in food, digesting it, and distributing it to other parts of the body. Reproduction. — The hydra reproduces itself either by budding. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illus

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