240 



INTESTINAL PARASITES. 



FIG. 88. 



has taken place. Boiling of suspected meat will destroy the 



infection. Some cases of infection 

 by the smaller tapeworm, or Tsenia 

 nana, have been reported. This is 

 the dog tapeworm, and its length is 

 about J inch. 



These worms have a life-cycle in 

 different animals. The T. saginata 

 in cattle, the T. solium in hogs, the 

 bothriocephalus in fish, and the T. 

 nana in dogs. When swallowed by 

 these animals the ova reach the 

 stomach, where the shells are dis- 

 solved and the larvae freed. These 

 emigrate to different parts of the 

 body muscles, liver, brain, etc. 

 where they become encysted, and 

 are then called Cysticerci. These 

 cysticerci, macroscopically, can be 

 seen as small grayish-white, hard 

 cysts. Meat infected with them is 

 called "measly." When incom- 

 pletely cooked and swallowed by 

 man, this sort of meat constitutes 

 the chief source of infection. The 



FIG. 89. 



Bothriocephalus latus. Bothriocephalus latus : Head. 



protecting envelope of the cysticercus is dissolved in the 



