UNSEGMENTED WORMS 205 



Some suggestion of their importance to man and the higher 

 animals may be gathered by reference to the following table 

 (p. 206). 



238. Supplementary Studies for the Library. 



1. In what different ways are the forms included in this 

 chapter classified in the various textbooks to which you have 

 access ? 



2. Consider the economic importance of the parasites in- 

 cluded in this chapter. 



3. Make a further study of the life histories of selected repre- 

 sentatives of these parasites. 



4. Illustrate by means of the unsegmented worms the de- 

 generation and simplification which attends parasitism. 



5. In what various ways do the intestinal parasites in the 

 group adhere to the walls of the digestive tract of the host ? 



6. Do you think the domestic animals are more or less likely 

 to be attacked and suffer from these internal parasites than the 

 wild ? What evidences would you offer for your view ? 



7. Prepare for the class a diagram of the reproductive organs 

 in the Tape-worm, indicating the function of each of the por- 

 tions. 



8. What is meant by the ' ' dermo-muscular " sac in worms? 

 Its functions ? 



9. Report on the importance of the Brachiopods in early 

 geological time, with the main structural features of the class. 



