. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. 3S4 CU^DTOPODA. co-exist in the same segment with segmental organs [Lumhricidui). 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 9 th and 10th segments two pairs
. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. 3S4 CU^DTOPODA. co-exist in the same segment with segmental organs [Lumhricidui). 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 9 th and 10th segments two pairs of receptacula seminis, which open at the junction of the 9th and 10th and 10th and 11th 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 11th segments, and two vasa defe- rentia, each of which opens inter- nally by two fvin- 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 flows out from the openings of the sperm duct and passes backwards in a longitudinal groove to the clitelJus, and thence into the receptaculum seminis of the other worm. In Tuhifex 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 ^on the above-mentioned * The head (prsestomium and buccal region) being reckoned as the first Fig. 310.—Generative organs of Lumbriom in segments VIII. to XV. (after E. Hei-ing). T, Testes ; St, the two funnels of the vas deferens on either side ; Yd, vas deferens; Or, ovary ; Od, oviduct; Be, rec
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanimals, bookyear1892
