The Encyclopedia britannica; a dictionary of arts, sciences, and general literatureWith new maps, and original American articles by eminent writersWith American revisions and additions, bringing each volume up to date . ke place outside thebody of the host and at a lower temperature, the most favourablebe;rtg from 23° to 26° C, at which the process occupies two or threeweeks. The free embryo (fig. 2, A) is conical in shape, with a roundedapex, its average lengtli being 013 mm. At the broader anteriorend is a retractile liead-papilla, with tlie exception of which the body XXni. — 68 538 TREMATO
The Encyclopedia britannica; a dictionary of arts, sciences, and general literatureWith new maps, and original American articles by eminent writersWith American revisions and additions, bringing each volume up to date . ke place outside thebody of the host and at a lower temperature, the most favourablebe;rtg from 23° to 26° C, at which the process occupies two or threeweeks. The free embryo (fig. 2, A) is conical in shape, with a roundedapex, its average lengtli being 013 mm. At the broader anteriorend is a retractile liead-papilla, with tlie exception of which the body XXni. — 68 538 TREMATODA is ciliated all over. The interior of the body is composed of granularnucleated cells^ and it coTitains a double eye-spot, composed of twocrescentic masses of pigment. There are also two cHiated funnelsforming the rudiments of tlio excretory system and a granular massbehind the head-papilla, probably representing the digestive embryo swims actively about, but if it does not succeed in nieet-ingtl>£ appropriate host for its next stage of development {ZimssKStriincatuius, a small pond snail) its period of vitality seems to belimited to about eight-houis. If it should meet with one of these FlO. 3.—Five stages In the life-history of Faseioh hepatiea; all highly , The free-swimmine embryo. B, A sporocyst containing young redlED. C,A young rediu, tiio digestiTe tract shaded. D, An adnlt redia, containing adaughtcr-redia, two almost matuie ccicaria, and E. A free letters have the same significance throughout, e. neaily ripe cercaria?;ce, cystogenous cells; dr, daughter-jedla; dt, limbs of tha dlgcstivfe tract;/, head-paplUa; h, eye-spots; h, same degenerating ; *, germinal cell; /.cellsof Ihe anterior row ; 7n. embryo in optical section. gasUulaatagG ; n, pharynxof redIa; o, digestive sac; oe, cesophagus; p, lips of redia; ?, collar; r, processesserving as rudimentary feet; t, embryos;^, trabccuis crossing body-cavity ofredi
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Keywords: ., bookcentury1800, bookdecade1890, bookidencyclopedia, bookyear1892
