LABORATORY WORK: EARTHWORM. 



The student should be supplied with a live earthworm, and 

 also with a specimen killed by placing in a dish in which is a 

 bit of cloth dampened w-ith chloroform, the whole being covered 

 so as to prevent escape of the fumes. After death the worm 

 should be pinned out straight and hardened in plenty of 

 alcohol. 



Is the body cylindrical throughout? Is it bilaterally 

 symmetrical? Can you distinguish between dorsal and 

 ventral surfaces? Is the body apparently made up of 

 somites? Are they all essentially alike? Draw the worm 

 through the fingers; does it move with equal ease in both 

 directions? 



Examine the head end for the mouth; is it dorsal or 

 ventral in position? Is the ring (preoral lobe) in front of 

 the mouth complete? How is it attached to the next 

 ring? Examine the surface of the body with a lens for 

 bristles (chcetce or setce). Do you find them on each segment? 

 How are they arranged on the segment? What was the 

 cause of the difference in ease of motion through the 

 fingers? Would the chsetae be of value in the motions of 

 the worm through the soil? 



Where is the vent? About one fourth the length of 

 the body from the anterior end notice that certain rings 

 are enlarged and swollen, and that the lines between the 

 segments tend to be obliterated. This is the ditellum. 



How many segments are include, 1 in it? The clitellum 



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