PLA TYHELMINTHES 



213 



irritation in the intestine and in secreting substances which 

 prove poisonous, especially to the nervous system, is more 

 serious. They may be avoided by care taken in regard to 



Fig. 132. — Diagrams of bladder-worms. — From Thomson. 



I. The ordinary Cysticercus type, with one head (-//.). 

 II. The Ccenurus type, with many heads. 

 III. The Echinococcus type, with many heads, and with 

 brood capsules (B.C.) producing many heads. 



food, and are treated with vermifuges, such as extract of 

 male fern, and purgatives. The cysticercus stage is beyond 

 the reach of medical remedies, but may sometimes be 

 treated surgically. 



