. A manual of zoology. Zoology. ek Fig. 172. Fig. 172.—Hydra viridi.\* testes above; ovarian enlargement below. Fig. 173.—Body layers of Hudra, (After Schulze, from Hatschek.) c, cuticula; en, nettle cells; eh^ ectoderm; c?i, entoderm; .s, supporting layer. tions appear on the column, enlarge, form tentacles, and at last a mouth, after which they may separate from the parent. In the sea are numerous hydroid joolyjis which, while agreeing in the main with Hydra, are distinguished from it in two important respects: (1) they do not directly produce sexual organs; (3) they rei^roduce asexually, an
. A manual of zoology. Zoology. ek Fig. 172. Fig. 172.—Hydra viridi.\* testes above; ovarian enlargement below. Fig. 173.—Body layers of Hudra, (After Schulze, from Hatschek.) c, cuticula; en, nettle cells; eh^ ectoderm; c?i, entoderm; .s, supporting layer. tions appear on the column, enlarge, form tentacles, and at last a mouth, after which they may separate from the parent. In the sea are numerous hydroid joolyjis which, while agreeing in the main with Hydra, are distinguished from it in two important respects: (1) they do not directly produce sexual organs; (3) they rei^roduce asexually, and by incomplete budding form jiersLstent colonies. In this formation of colonies a series of parts have arisen which require special designations (fig. 174). The sejiarate animals are the liijdranths, and are connected together by a system of tubes, the cmnosarc, which, like the hydranths, consist of ecto- derm, entoderm, and mesogloea, and since the gastrovascular space continues in them, these effect a distribution of food throughout the colony. The crenosarcal tubes may creep over some support (stone, alga, snail-shell, etc.) and form a network, the hydrorhna, or it may stand erect and tree-like, forming a Inidrocaulns. Usually both hydrorhiza and hydrocaulus occur in the same 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929. New York, H. Holt and Company
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