EAETHWOEM 137 



c. Circulation. — Lay a living specimen on a flat surface 

 and look for pulsations of the dorsal blood-vessel. 

 "Where do they begin? In which direction do 

 they proceed ? Do you find any portion of the 

 blood-vessel which is more contractile than the 

 other parts ? 



General Questions. — Does the earthworm have a skel- 

 eton? Did you discover any internal organs, as lungs, 

 for breathing ? In what way does the worm breathe ? 

 Note the resemblance in structure (serial lioniology) of 

 the segments of the body. Can you trace any struct- 

 ural resemblance whatever between the earthworm's 

 body and your own ? Do you know of any differences 

 between a caterpillar (" worm ") and an earthworm? Is 

 the former a worm ? "Why ? Of what use is the slimy 

 fluid which is excreted from the surface of the earth- 

 worm's body? If a worm's body be cut in two, does 

 each part become an individual animal? How do you 

 know? From your study of the earthworm, which of 

 the special senses would you credit it with having ? Of 

 what use, if any, are earthworms to man ? Of what to 

 plants ? What enemies do you Tcnow the earthworm to 

 have ? How does it protect itself from them ? Do you 

 know it to be the enemy of any other animal ? Do you 

 consider an earthworm to be a " higher " animal than a 

 starfish ? "Why ? In what ways may the worm be dis- 

 tributed geographically? 



Use the leech {Hirudd) and the sea-worm {Nereis) for 

 comparative study. 



