. Animal biology. Zoology; Biology. PARASITISM 173 In the uterus there develops in this egg a six-hooked embryo. As the proglottid becomes ripe and passes out of the body of the host with the feces, it carries with it thousands of embryos, still inclosed in the egg shells. 2. If this proglottid falls upon vegetation and is eaten by a cow, the eggs are freed from the proglottid in her intestine and the embryos Fig. 81.—Diagram showing the life history of Taenia saginata. A, the egg. X 550. B, egg containing six-hooked embryo. X 550. C, young eysticercus. X 30. D. cysticercus showing be
. Animal biology. Zoology; Biology. PARASITISM 173 In the uterus there develops in this egg a six-hooked embryo. As the proglottid becomes ripe and passes out of the body of the host with the feces, it carries with it thousands of embryos, still inclosed in the egg shells. 2. If this proglottid falls upon vegetation and is eaten by a cow, the eggs are freed from the proglottid in her intestine and the embryos Fig. 81.—Diagram showing the life history of Taenia saginata. A, the egg. X 550. B, egg containing six-hooked embryo. X 550. C, young eysticercus. X 30. D. cysticercus showing beginning of the papilla. X 30. E, the papilla showing an early stage in the dovelopment of the seolex. X 30. F, the papilla containing the scolex. with suckers and rostellum. The latter has rudimentary hooks, which later disappear as the rostelluni is retracted into the scolex. X 40. G, the scolex and neck everted but still attached to cyst. X 3. (All from Leuckart, " Parasiten des Menschen") They bore their way through the wall of the alimentary canal and, migrating through the tissues, reach the voluntary muscles, especially the muscles of mastication, where they become encysted. 3. The encysted larva in from three to six weeks develops a bladder- like sac filled with a clear watery fluid and so becomes a bladder worm, or eysticercus. One side of the wall of this sac gradually becomes thick- ened, is inverted, and forms a hollow papilla projecting into the 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 Wolcott, Robert Henry, 1868-1934. New York ; London : McGraw-Hill Book Company, Inc.
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