THE TAPEWORM 103 



produces proglottids so tliat a new adult is formed. Draw the bladder- 

 worm (3-5 X projected size). 



Exercise 5. — Typical Life-cycles. 



(g) Tapeworms, therefore, have two hosts. In the following cases 

 of known life-cycles, which would be the primary and which the 

 secondary host: man — pig; mouse — cat; housefly — hen; fish — bird; 

 louse — dog; man — fish? Consider where and how the three stages 

 above studied would occur in each case. Tabulate your conclusions. 



