EARTHWORM. 



LUMBRICUS TERRESTRIS. 



A. OBSEEVATIONS ON THE LIVING WORM. 



I. Put a living worm upon a sheet of paper on the 

 laboratory table and observe its shape and 

 its movements. (Be careful not to let the worm 

 become dry.) 



1. Note tlie changes of form of the anterior and 



posterior parts of the body as the worm 

 moves over the paper. In what way is 

 this change of shape brought about? 



2. With a blunt instrument touch one end and 



then the other end of the worm. Which 

 end is more sensitive ? 



3. Note the pulsations in the dorsal blood- 



vessel (visible through the skin along the 

 median dorsal line). What is the direc- 

 tion of the wave of contraction ? 



B. EXTERNAL CHARACTERS OF THE PRESERVED SPECI- 



MEN.* 



I. With the worm extended in a dissecting -pan and 



covered with water or with iveak alcohol, observe : 



1. The division of the body by constrictions 



into a number of segments or somites (me- 



* For method of preservation, etc., see ' ' General Biology," Sedg- 

 wick and Wilson, second edition, 1895, pp. 210-213. 



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