THE PHYLUM PLATYHELMINTHES 219 



7. Where does the life cycle of a tapeworm differ markedly from that of a digenetic 

 trematode? 



8. Define sporocyst, oncosphere and redia. 



Supplementary Reading 



The phylum is thoroughly described and discussed in The Invertebrates, volume II, 

 by L. Hyman. Problems of regeneration and polarity in many organisms are discussed in 

 Analysis of Development by Willier, Weiss and Hamburger. Many life cycles of the 

 parasitic forms can be found in parasitology texts, including Chandler, Introduction to 

 Parasitology. 



