Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 OLKHH' 383 hypodermis there is present in the ditelrus a deeper glandular layer (Saulenschicht Clap.), which consists of finely granular cells embedded in a framework of pigment ed and vascular connective tissue and situated between the hypodermis and the external muscular layer. There are but few set;v present, and they are never disposed on special parapodia, but always in simple pits in the integument, by the cells of which they are secreted. There are small secondary bristles w
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 OLKHH' 383 hypodermis there is present in the ditelrus a deeper glandular layer (Saulenschicht Clap.), which consists of finely granular cells embedded in a framework of pigment ed and vascular connective tissue and situated between the hypodermis and the external muscular layer. There are but few set;v present, and they are never disposed on special parapodia, but always in simple pits in the integument, by the cells of which they are secreted. There are small secondary bristles which serve as a reserve. The blood is usually red, as in the Hirudinea. The alimentary canal is often divided into several regions, the relations of which are most complicated in the Lumbricidoe. In Lumbricus, the buccal cavity leads into a muscular pharynx, which is probably used for sucking. This is followed by a long oesophagus extending to the 13th segment, and furnished with a thick layer of glandular cells and several glandular dilated ap- pendages (calcareous sacs). The oeso- phagus is succeeded by a crop, a muscular gizzard, and finally by the intestine itself, the dorsal wall of which is pushed inwards so as to form a longi- tudinal fold, the typhlosole (comparable to a spiral valve). In the Limicolw the alimentary canal is simpler by the absence of a muscular stomach; a pharynx and oesophagus are, however, always present. Reproduction.—The Oliyochwta are hermaphrodite; they lay their eggs either singly or united in greater num- ber in a capsule; and they develop without a metamorphosis. The testes and ovaries are paired and placed in definite segments, usually near the an- terior end of the body; they dehisce their products into the body cavity. The generative ducts possess funnel-shaped openings into the body cavity through which the generative products pass, and may FIG. 309.—Lniiilji-iciix rnlrllti* (after G. Eisen). </, The whole worm; Cl, Clitellus. I,
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