200 



PARASITES OF THE DOMESTIC ANIMALS 



The entire length of the worm is 2-3 meters (6-9 feet), though it 

 may be longer. 



The eggs (Fig. 110) are oval and provided with a very deUcate shell. 

 The shell surrounding the onchosphere is globular and thick. 



This tapeworm is much more rare in the United States than is T. 

 saginata. In general, its distribution may be said to correspond with 

 that of the domestic pig, correlated with the custom of eating the fiesh 

 of this animal raw or imperfectly cooked. The cysticercus not only 

 infests the pig, but may find lodgment in man himself if the eggs from 

 an adult worm infesting his intestine find their way to his stomach. 



Fig. 110.— Egg of Tania 

 saginata, with outer shell and 

 filaments; embryo, with em- 

 bryonal shell, in center. Egg 

 of T. solium (above), show- 

 ing embryo with embryonal 

 shell. 



Fig. 111. — Mature segment of Taenia 

 saginata (left) and T. solium (right) , showing 

 laterally branched uterus. 



For this reason, with the added one that the 

 larvae may become established in the central 

 nervous system or eye, Tcenia solium consti- 

 tutes a much more serious infestation than 

 does T. saginata. 



A simple method for determining to which 

 of these two species the infecting tapeworm 

 belongs consists in clearing up a voided segment, pressing it between 

 two clean slides, and observing the form of the gravid uterus as the 

 specimen is held before a strong light. If the median trunt shows 

 numerous delicate lateral branches on each side (20-35) it indicates 

 that the infection is with Tcenia saginata. If these branches are less 

 numerous (7-12) and more robust, it may be concluded that the seg- 

 ment belongs to T. solium (Fig. 111). 



If treatment has resulted in the expulsion of the entire worm, an 

 exact differentiation can be made by examination of the head under low 

 power magnification. The pork tapeworm will show the cephalic arma- 

 ture which in the beef tapeworm is absent. 



Occurrence of Pork Measles. — While the larvae of the unarmed 

 tapeworm of man live only in cattle, those of the armed tapeworm may 



