WORMS 

 THE EARTHWORM 



Lumbriciis sp. 



General Suggestions. — The earthworms burrow in the 

 ground to considerable depth, swallowing the earth re- 

 moved from the burrow. The digesitve juices dissolve out 

 the organic substance from the soil swallowed, and these 

 are absorbed. At night they leave their burrows and crawl 

 about. In the daytime, when at rest, they lie in their bur- 

 rows with the head at the surface of the burrow. In 

 winter they go deep down into the earth below the freezing 

 point. Fresh specimens may be kept all winter by providing 

 them with earth and a convenient place in which to burrow. 

 Specimens carefully prepared by running them up from 

 fifty per cent, to ninety-five per cent, alcohol should be kept 

 on hand for study of internal anatomy. 



External Morphology. — (i) Examine a live worm. 

 What is its general shape? Are both ends alike? Which 

 is the head end? Are the two ends alike in shape? How 

 do they differ? Has the worm the same diameter through- 

 out its length? Are both dorsal and ventral sides alike 

 in shape? 



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