Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 384 CHJETOPODA. co-exist in the same segment with segmental organs (Lumhritido. ). In the earth-worm, whose generative organs were first accurately described by E. Hering, the female apparatus consists of two ovaries in the 13th segment,* and two oviducts, which begin with trumpet- shaped openings into the body cavity, contain several eggs in a dila- tation and open to the exterior on either side on the ventral surface of the 14th segment. There are in addition in the 9th and 10th segmen
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 384 CHJETOPODA. co-exist in the same segment with segmental organs (Lumhritido. ). In the earth-worm, whose generative organs were first accurately described by E. Hering, the female apparatus consists of two ovaries in the 13th segment,* and two oviducts, which begin with trumpet- shaped openings into the body cavity, contain several eggs in a dila- tation and open to the exterior on either side on the ventral surface of the 14th segment. There are in addition in the 9th and 10th segments two pairs of receptacula seminis, which open at the junction of the 9th and 10th and 10th and llth segment respectively. They are filled with sperm in copulation (fig. 310). The male genital organs consist of two pairs of testes in the 10th and llth segments, and two vasa defe- rentia, each of which opens inter- nally by two fun- nels and to the exterior in the 15th segment. Copulation takes place in June and July on the sur- face of the earth at night, The worms apply their ventral surfaces to one another and lie in opposite directions, in such a manner that the openings of the re- ceptacula seminis of one worm are opposite the clitellus of the other. During copulation sperm Hows out from the openings of the sperm duct and passes backwards in a longitudinal groove to the clitellus, and thence into the receptaculum seminis of the other worm. In Tubifex and Enchytwus the ovaries may break up into groups of ova which float free in the body cavity. Special albumen glands and also glands which secrete the substance of the shell of the cocoon are often present.' In the breeding season the above-mentioned * The head (pr;vstomium and buccal 'iniO 1 icing reckoned as the first segment. v FIG. 310.—Generative organs of Lumbricus in segments VIII. to XV. (after E. Hering). T, Testes ; St, the two funnels of the vas rteferens on either side ; Vd, vas deferens ; Or, ovary
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