. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. 384 CILITOPODA. organs co-exist in the same segment with segmental organs (Lumlricidce). In the earth-worm, Avhose 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 se
. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. 384 CILITOPODA. organs co-exist in the same segment with segmental organs (Lumlricidce). In the earth-worm, Avhose 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 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 an other and lie. FIG. 310.—Generative organs of Lumbricus in segments VIII. to XV. (after B. Hering). T, Testes ; St, the two funnels of the vas rleferens on either side ; VcL, vas deferens; OP, ovary ; Od, oviduct; Re, receptacula seminis. 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 flows 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 Enchytrceus 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 (prfcstomium and buccal region) being reck
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