PLATYHELMINTHES 



joints. It develops from the egg in the digestive canal 

 of the pig, burrows into the muscular tissue of the 

 animal, and there becomes encased. Pork containing 



these cysts is called 

 "measly pork." If 

 the pork be eaten 

 by man, in an un- 

 cooked condition, 

 this case is dis- 

 solved by the gas- 

 tric juice, and the 

 embryo thus re- 

 leased attaches it- 

 self to the intes- 



FIG. 37. Tapeworm (Ttettia soliunt) : a, bead; b, c, d, 

 segments of the body. 



FIG. 38. Planarian 

 Worm. 



tine by its " head," and develops into the tapeworm by 

 budding off the reproductive segments, or proglottides. 

 As these become ripe and filled with fertilized eggs, 

 they are detached, and pass off with the excrement. 



The disease called " rot," in sheep, is produced by the 

 fluke (Distoma), which grows in the bile ducts of the 

 sheep. 



The flat worms are the most widely distributed of all 

 animals above the Protozoa. They are found on land, 

 at various depths in bodies of fresh water, and in the 

 sea. They also occur as parasites in animals in almost 

 every class of the Metazoa. 



