. Zoology for high schools and colleges. Zoology. 210 ZOOLOGY. etc., as well as oyer the ground, by minvite, short, curved setse or bristles, which are deeply inserted in the muscular walls of the body, and arranged in four rows along each side of the body. The alimentary canal is straight, the stomach has three 2:)airs of ^mall lateral blind sacs (coeca), and the intestine, which is externally tubular, contains a thick inter- nal sac-like fold called a typMosole. The segmental organs are highly convoluted tubes, a pair to each segment of the body, except a few near the head, and opening inter
. Zoology for high schools and colleges. Zoology. 210 ZOOLOGY. etc., as well as oyer the ground, by minvite, short, curved setse or bristles, which are deeply inserted in the muscular walls of the body, and arranged in four rows along each side of the body. The alimentary canal is straight, the stomach has three 2:)airs of ^mall lateral blind sacs (coeca), and the intestine, which is externally tubular, contains a thick inter- nal sac-like fold called a typMosole. The segmental organs are highly convoluted tubes, a pair to each segment of the body, except a few near the head, and opening internally with ciliated funnels and externally in minute pores situated along th'e under side of the body. The earth-worm is monoecious (hermaphroditic). The oviducts open in the fourteenth segment, and the seminal ducts {vasa deferentia) in the fifteenth. Between the ninth and tenth, and the tenth and eleventh segments are the four openings of the seminal receptacles {receptacula seminis). Pairing is reciprocal (see Fig. 145), each worm fertilizing the eggs of the other; they pair in June and July in the night-time. The eggs of the European Lumhricus rubellus Grube are laid in dung, a single egg in a capsule; L. ar/ricola lays numerous egg-cap- sules, each containing sometimes as many as fifty eggs, though only three or four live to de- velop. The development of the earth-worm is like that of the leech, the germ passing through a . morula (blastula), gas- Kg. 145 .-Earth-worms pamng. After Curtis. ^ i , a, embryo (blastula) soon alter segmentation of trula and neuruia stagO, the yolk ; 6, embryo further advanced; 0, mouth; ,, i n j_ i <;, embryo still older; *, primitive streak; d, tilC WOrm, When hatch- neurulaio, its mouth-After Kowalevsky. ^^^^ resembling the pa- rent, except that the body is shorter and with a much less number of segments. "While the earth-worms are in the main beneficial, from their habit of boring in the soil of gai'dens and ploughed. Please note tha
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectzoology
