. A manual of zoology. Zoology. 302 CCELHELMINTIIES. and now is common in Germany lis* half to three quarters of an inch in length, the male and female always in pairs, cause the disease l<nown as 'gapes'in fowl. Avkylo- stomum (Dochmius) dtiodenale (tig. 266}, about two fifths of an inchiii length, lives in the small intestine of man, causing s(;vere loss of blood and the disease known as Egyptian chlorosis. The eggs develop in mud and moist earth, and hence people who drink muddy water (Fellahin of Egyptj or work much with clay (potters and brick-makers) are especially subject to infectio
. A manual of zoology. Zoology. 302 CCELHELMINTIIES. and now is common in Germany lis* half to three quarters of an inch in length, the male and female always in pairs, cause the disease l<nown as 'gapes'in fowl. Avkylo- stomum (Dochmius) dtiodenale (tig. 266}, about two fifths of an inchiii length, lives in the small intestine of man, causing s(;vere loss of blood and the disease known as Egyptian chlorosis. The eggs develop in mud and moist earth, and hence people who drink muddy water (Fellahin of Egyptj or work much with clay (potters and brick-makers) are especially subject to infection. It was first known in Egypt, caused considerable trouble during the building of the St. Gotthard tunnel in Switzerland, Recently it has been thought that the Ankjjlostoma larvse obtain entrance to man through the skin, as in bathing, etc. Family 4. These owe their common name of ' bair necks ' to the fact that the part of the body wliich contains the pharynx is hair-like and elongate, uhile the pharynx itself traverses a peculiar cord of cells. Long- est known of the family is Trichocephalus dispar*- of man (fig. 267), about an inch or an inch and a half in length, which lives with its neck burrowed like a cork- screw in the wall of the intestine near the csecnm. Since it does not move, it causes little injury. Its presence can be recog- nized l)y the oval brown double-shelled eggs (fig. 246, d) in the fteces. A second .species. Trichina spiralis * (figs. 268, 269), is much smaller, but much more dangerous. Two stages are to be distinguished, the encysted muscle Tri- china and the sexually mature intestinal Tricliina. The first was discovered in a human body in 1835; the latter was not known until much later, its history being worked out by Leuckart, Virchow, and Zenker. In the encysted stage it occurs in the muscles of pigs, rats, mice, man, rabl)its, guinea pigs, dogs, etc. (never in birds), enclosed in an oval capsule about to mm. long and hence
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