. A manual of zoology. Zoology. '284 PLA THELMINTHES. the stomach the larvae with their six hooks bore through the intes- tinal wall and migrate, using the blood-vessels in their course, into the muscles, or more rarely other organs. Here they develop into bladder worms (cysticerci). In this they become oval and secrete a cyst to which, as a foreign body, the pig adds an envelope of connective tissue. The cysticercus blastema grows through. Fig. 247—Structure and development of the cysticercus (C. cellulossB of Tcenia soUrun). a,measly meat, natural size; below an escaped cysticercus: &, c
. A manual of zoology. Zoology. '284 PLA THELMINTHES. the stomach the larvae with their six hooks bore through the intes- tinal wall and migrate, using the blood-vessels in their course, into the muscles, or more rarely other organs. Here they develop into bladder worms (cysticerci). In this they become oval and secrete a cyst to which, as a foreign body, the pig adds an envelope of connective tissue. The cysticercus blastema grows through. Fig. 247—Structure and development of the cysticercus (C. cellulossB of Tcenia soUrun). a,measly meat, natural size; below an escaped cysticercus: &, cysticer- cus, with exserted scoiex, enlarged; c~e, development of the scolex, more en- larged ; c, young cysticercus with blastema of scolex (above) and water-vascular net; rf, e, different stages of scolex in receptaculum, the cysticercal wall mostly removed. increase of cells, but more by the infiltration of serous fluid, so that it becomes distended into a delicate translucent vesicle. So abundant can this be that in T. solium the microscoj^ically small embi^o can grow in three or four months to the size of a beau or j)oa; in other species as large as a hen's egg. By invagination the wall of the bladder produces the blastema of the scolex (fig. '2V!, c). This has at first a sac-like shape, but soon increases in length, its growth being confined by an envelope, tlie receptaculum (^d), so that it is bent. At the a])ex of this l^lind sac arises the characteristic armature of the scolex which makes it possil)le to say what tapeworm will come from the cysticercus. Thus in 'f. solium there are four suckers and a crown of hooks. These parts are at first inverted. 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929. New York, H. Holt and Compan
Size: 1323px × 1888px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
