CLASSIFICATION 



133 



times in man. The latter two species produce numerous heads in 

 the bladder-worm stage. Since only one of these can be regarded 

 as continuing the individuality of the bladder-worm, the others 



2. 



Daughter cyst. 

 Brood capsule. 



Fig. 96. — Diagrams of bladder-worms. 



I. The ordinary Cysticercus type, with one head; 2. The Coenurus type, with many heads; 3. The 

 Echinococcus type, with secondary cysts or brood capsuJes producing many heads. Hooks and 

 suckers are not shown in 2 and 3. 



must be looked upon as buds from it, so that there is here a 

 metagenesis. The bladder produced by T. echinococcus is known as 

 a ' hydatid cyst ' ; it is very large, containing sometimes as much 

 as a gallon of fluid, and its wall buds off secondary cysts into the 

 cavity. 



