* TAPE WORMS. 



201 



solved off in the alimentary canal of the animal ingesting it, and the 

 onchosphere bores its way through the gut to later become encysted in 

 various tissues. In some tape-worms a ciliated embryo is liberated 

 from the egg shell and swims about actively to enter some fish or other 

 animal. When the 6-hooked embryo reaches its proper tissue, the 

 hooklets are discarded and a scolex similar to the parent one is devel- 



to. 



C. 



FIG. 62. Tape worms. A. i, 2 and 3, Scolex, proglottides and ovum of Taenia 

 solium; B. 4, 5, 6 and 7, Scolex, proglottides and ovum of Dibothriocephalus 

 latus; C, 8, 9 and 10, Scolex, proglottides and ovum of Taeenia saginata. 



oped. At this time we have a bladderlike structure with the scolex 

 inverted in it. This little cyst with its scolex when ingested by another 

 animal is digested, and the scolex establishing itself in the intestine, 

 develops a series of segments. The ciliated embryo of the D. latus 

 does not form a cyst, but instead a worm-like creature similar to the 

 adult. This is termed a Plerocercoid. Small laminated calcareous 

 corpuscles are characteristic of cestode tissue. 

 14 



