70 A GUIDE FOR THE STUDY OF ANIMALS 



Review and Library Work on Worms 



1. What are the distinguishing characteristics of 

 worms ? 



2. Give the classes of worms, and the authority for this 

 classification. 



3. What kind of soil do earthworms seem to prefer ? 

 Why should they ? How do they form their burrows ? 

 What are the castings around the mouth of a burrow? 

 How are they placed there ? 



4. In what ways do earthworms benefit the soil ? How 

 great is their effect estimated to be ? 



5. Give a brief sketch of the life of Charles Darwin, 

 noting especially the work he did with earthworms. 



Why is Darwin's work on earthworms noteworthy : because it is 

 such a large proportion of the work he did, or because it is so much of 

 the work which has been done on earthworms ? 



6. How are earthworms protected against the cold of 

 our winters .'' What limits the northern range of earth- 

 worms .'' 



7. Where are earthworms found geographically .' Why 

 are they so widely distributed .'' By what means are they 

 extended from one locality to another ? 



8. How do earthworms reproduce .? What care do 

 they take of their young ? 



9. What tissues or organs of earthworms correspond in 

 function with the ectoderm of hydra; with the endo- 

 derm ? Why does an earthworm need a system of blood 

 circulation more than a hydra does .■' 



10. Contrast the number of openings in an earthworm's 

 alimentary canal with the number in a hydra's diges- 

 tive cavity. Which plan seems a better one .■' In what 

 respects ? 



