238 



INTESTINAL PARASITES. 



the link on a clean slide and examining with the | (16 in.m.) 

 objective. 



The Tsenia saginata (Fig. 84), or beef tapeworm, which is 

 the prevailing one in the United States, is distinguished prin- 

 cipally by its head, which is 2 m.m. long and nearly square 

 in shape. Its head is not provided with hooks. 



The scolex (head) of the Tsenia solium (Figs. 85 and 86), or 



FIG. 85. 



Head of Trcnia solium ; X 45. (Lcuckart.) 



pork tapeworm, is about the size of a common pin, and is sur- 

 rounded by a projecting rostellum which has on it a double 

 row of booklets. Both species of worm are provided with 



FIG. 86. 



Ova of Tsenia solium (Leuckart): a, With yolk ; b, without yolk, as in mature seg- 

 ment. The hard brown shell is indicated. 



sucking disks, or suckers, four in number, by which they 

 attach themselves to the intestines and through which they 

 nourish. The T. saginata is longer than the T. soliu-m, the 

 former measuring, when fully grown, 12-20 feet, the latter 

 612 feet in length. Larger and longer than either is the fish 

 tapeworm of Europe, the Bothriocephalus latus (Figs. 88 and 



