158 



ZOOLOGY. 



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suflBcient to kill the Cysticerci. Butchers especially suffer 

 from tape-worms, from their habit of eating bits of raw 

 meat, beef and veal harboring Cysticerci, which transform 

 into species of Tmnia nearly as injurious as TcBnia solium. 

 As a matter of course, in the use of drugs to expel a tape- 

 worm, they should be pushed so as to carry off the entire 

 animal, as new segments grow out from near the head as 

 rapidly as the proglottides are detached. 



The Cysticercus of another injurious tape-worm lives in 

 the muscles and internal organs of cattle. This is the Tcsnia 



mediocanellata of Kuchen- 

 meister, which is larger, 

 with a larger darker head, 

 larger suckers, and with- 

 out a rostrellum or hooks. 

 By far the most injurious 

 species is Tmnia echinococ- 

 cus Siebold (Fig. 108), 

 more frequently causing 

 death than any other en- 

 tozoon. In its adult or 

 strolila state this worm 

 only infests the dog and 

 wolf, but its larva, the 

 hydatid of physicians, fre- 

 quently occurs in the hu- 

 man body. It is very 

 small, seldom exceeding 

 six millimetres in length, 

 there being but four 

 segments, including the 

 head, which has a pointed 

 rostellum, with a double 

 crown of large-rooted 

 hooks ; there are four suckers present, and the last segment, 

 when sexually mature, is as long as the anterior ones taken 

 together. The hydatid (proscolex) forms large proliferous 

 vesicles, in which the scolices (Echinococcus heads) are de- 

 veloped by budding internally. About five thousand eggs 



Wg. 107.— Proglottis of T. solium, a, testis ; 

 6, sperm duct ; c, orifice of cirrus ; d, matrix 

 filled with eggs ; e, vagma ; /, sexual cloaca. — 

 After Beneden. 



