28 



ECONOMIC ZOOLOGY 



muscles. If, now, this muscular tissue be eaten, imperfectly cooked, 

 by man, the cysticerci, when the meat is digested complete their 

 development into the adult T. saginata in the intestine of the new 

 victim. 



Taenia is most common in women especially between 20 to 40 

 years, and a worm may live for years, if not expelled by proper 

 treatment. Of course, if no raw or very rare beef be eaten it is im- 

 possible to be infected; probably most infections come from pri- 

 vately killed cattle, as the larger slaughter houses keep the beef in cold 



FIG. 20. Human tapeworm, Tcenia solium. A, the entire animal. X /4- 

 B, the head or scolex, sc, enlarged; n, neck region; p, segment or proglottid; s, suckers; 

 sc, scolex; gp, genital pore; h, hooks. 



storage for three weeks, which is thought to destroy the cysticerci 

 that may be present. Thorough salting will also kill the cysticerci. 



The life-history of T. solium, which most books describe as the 

 "common" tapeworm, is essentially the same as that of T. saginata 

 except that the hog is the second host. The head here is very tiny, 

 not so large as the head of a pin, and is armed with hooks, hence the 

 name "armed" tape worm. The cysticercus of T. solium is not so 

 easily killed by cold storage as that of T. saginata, so that there is 

 always danger from eating raw pork, though the greatest danger is 

 from another worm, to be described later. 



