. A manual of zoology. 142 MANUAL OF ZOOLOGY kind of animal—a second or intermediate host — in order that the embryo may be enabled to enter the next phase of its life-history. In the case of some tape-worms, this second or intermediate host is, like the first or permanent host, a vertebrate animal: in the case of others it is some inver-. Fig. 77.—Development of Tape-worm. A. hexacanth embryo; B, Proscolex of Ta-aia saginata; C-E, stages in the formation of the scolex of the same; C, the invagination before the hooks and suckers have become developed; D, after th^, appearance of the hooks and
. A manual of zoology. 142 MANUAL OF ZOOLOGY kind of animal—a second or intermediate host — in order that the embryo may be enabled to enter the next phase of its life-history. In the case of some tape-worms, this second or intermediate host is, like the first or permanent host, a vertebrate animal: in the case of others it is some inver-. Fig. 77.—Development of Tape-worm. A. hexacanth embryo; B, Proscolex of Ta-aia saginata; C-E, stages in the formation of the scolex of the same; C, the invagination before the hooks and suckers have become developed; D, after th^, appearance of the hooks and stickers; E, partly evaginated; F, fully evaginated scolex of T. solium with caudal vesicle; G, scolex of T. serrata with the remains of the vesicie; H, young tape-worm of T. serrata. (After Leuckart.) tebrate animal such as an earth-worm, a centipede, or an insect. This transference of the hexacanth embryo to the second host is a passive migration, not an active one, as in. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Parker, T. Jeffery (Thomas Jeffery), 1850-1897; Haswell, William A. (William Aitcheson), 1854-1925. New York, The Macmillan Company; London, Macmillan & Co. ,Ltd.
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