NEMATODA 



221 



2. TRIOHINELLA Railliet (Trichina Owen). Minute worms, with the 

 forward portion not much slenderer than the hinder; male without spic- 

 ule but with 2 conical projections at hinder end; viviparous; anus 

 terminal: 1 species. 



T. spiralis* (Owen) (Fig. 353). Male 1.5 mm. long; female 3.5 mm. 

 long; young born alive: in the small intestine of man, the pig, rat, and 

 ether animals. The young worms, which are about .1 mm. long, are the 

 cause of trichinosis. They bore their way 

 through the intestinal wall of the host and 

 migrate in the blood and lymph to the muscles, 

 where they encyst themselves and frequently 

 so lame the muscles of the jaws, neck, and 

 thorax that their functioning is interfered with 

 and death may ensue. If meat containing the 

 cysts be eaten by another animal or a person 

 the worm is released and passing into the in- 

 testine quickly becomes mature. Man gets the 

 infection by eating insufficiently cooked pork 

 containing the cysts; the pig gets it by eating 

 offal or rats. The rat is supposed to be the 

 original host of the worm, 



3. TRICHOSOMA Rudolphi. Body hair-like, 

 the forward portion not much slenderer than 

 the hinder; usually a single spicule present: 

 in birds and mammals; numerous species. 



T. tenuissimum Diesing. Male 10 mm. 

 long; female 17 mm. long: in duodenum of 

 the pigeons. 



T. crassicaudum Bellingham. Female 17 mm. long; forward end 

 rounded and with small protuberances back as far as the vulva; male 

 2.5 mm. long, without spicule, and lies often in the female vulva: in the 

 liver and other organs of the rat. 



Fig. 353 TrichineUa spi- 

 ralis (from Ransom). A, 

 female ; B, male ; C, a piece 

 of pork containing cysts ; 

 D, an enlarged cyst. 1, fe- 

 male genital pore; 2, em- 

 bryos in the uterus; 3, 

 ovary ; 4, anus ; 5, testis. 



FAMILY 6. STBONGYLIDAE. 



Mouth surrounded by several papillae; no oesophageal bulb; hinder 

 end of male expanded to form a broad bursa (Fig. 355, B), also with 

 1 or 2 spicules: numerous genera and species which live in the intestine, 

 lungs and other organs of vertebrates, especially mammals. 



* See "Trichinosis in Germany," by C. W. Stiles, Bull. No. 30, Bureau of An. 

 Ind., TJ. S, Dept. of Ag., 1901, 



