TAPEWORMS 



493 



infectecC 

 Small f'eh^ 



segments 

 iJreaJt off 

 appear- m 

 feces 



tape*£n*m, 

 in the*, 

 intestine 



^egm-ants 

 liberate 

 mariv- egg's 



g^- ; - ^ « at (Xclops" 



Cestodes or tapeworms. These parasites infest man and many 

 other vertebrate animals. One tapeworm (Taenia solium) passes 

 through two stages in its life history, the first within a pig, the 

 second within the intestine of man. The developing eggs are 

 passed off with wastes from 

 the intestine of man. The 

 pig, an animal with dirty 

 habits, may take in the 

 tapeworm embryos with its 

 food. These develop within 

 the intestine of the pig, but 

 scon make their way into 

 the muscles or other tissues, 

 where they are known as 

 bladder worms. If man 

 eats undercooked pork con- 

 taining them, he is likely to 

 become a second host for 

 tapeworms. 



Another common tape- 

 worm ( Taenia saginata) 

 parasitic on man lives part 

 of its life as an embryo 

 within the muscles of cattle. 

 The adult tapeworm con- 

 sists of a round headlike 

 part provided with hooks, 

 by means of which it fastens itself to the wall of the intestine. 

 This head now buds off a series of segment-like structures, which 

 are practically bags full of sperms and eggs. These structures, 

 called proglottids, break off from time to time, thus allowing the 

 developing eggs to escape. The proglottids have no separate 

 digestive systems, but the whole body surface, bathed In digested 

 food, absorbs it and thus they are enabled to grow rapidly. 



Roundv/orms. Still other wormlike creatures called round- 

 worms are of importance to man. Some, as the vinegar eel found 

 in vinegar, or the pinworms parasitic in the lower intestine, partic- 





Cyclops <lcct «gg> 



George W. Hunter III 



The bass tapeworms infest the small-mouthed black 

 bass. The mature posterior segments of the worm, 

 filled with eggs, break off and pass from the host. 

 The eggs are liberated and settle to the bottom of 

 the stream, where they are eaten by small crustaceans, 

 called cyclops, which in turn are eaten by small fish 

 which form the food of the bass. 



