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. Trichotrachelid.e. 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 

 0.4 to 0.6 mm. long and hence recogniz- 

 able by a practised observer Avith the 

 They are more easily seen 



Fig 369 



Fig. 2fi7. — Trichnrephnlus di^pny, malo 



witti anterior end imbedded in 



intestinal wait. (Friiin Leue]<- 



art.) 

 Fig. 2W. — Trtdiinn fijiirdU.'i, male. 



(From Hatschek). <(, cloaca; (, 



testes. 

 Fig. ;3f)*.t.—Tr/t7i/na in muscle. (From naked eye. 



Boas.) , * . , . ., 1 T 



when they arc partially calcified and 

 have a whitish color. Certainty in their recognilion demands a lowpower 

 of the microscope. In the capsule is coiled up the worm, about 1 mm. 

 long, which is not yet sexually mature, although furnished with the 



