EAUTHWOEM 125 



d. The girdle, clitellum, or cingulxun. — Does it show 



equally well on all of several specimens % How 

 is it distinguished by shape, size, color, etc., from 

 the other regions ? Does it completely encircle 

 the body ? How many segments in it ? Is the 

 number constant % Counting from the anterior 

 end, with which segment does the girdle begin ? 

 With which does it end ? 



e. The cuticle. — Soak an alcoholic specimen in water 



for a few minutes, then with the point of a nee- 

 dle or with fine-pointed forceps strip some of the 

 cuticle off the body. What is its color ? Its text- 

 ure ? Is it easily torn % Is it flexible or rigid ? 

 Opaque or transparent ? Does it cover the en- 

 tire body ? Does it end at the mouth and anus ? 

 In its structure is the cuticle well-adapted to the 

 earthworm's mode of life ? Examine some from 

 the ventral surface in a drop of water and note 

 the cuticular sacs in which the setse are partly 

 embedded. How are these sacs arranged ? What 

 is their shape ? Examine the cuticle under a high 

 power and note the striae which mark its surface. 

 In which direction do they run ? To what is the 

 color of the cuticle as seen by the unaided eye 

 due? 

 Make a drawing of a portion of the cuticle as seen 

 under a high power. 



/. The bristles or setee. — Draw the worm backward 

 through the fingers and note the presence of the 

 rough points. Examine them with a hand-lens. 

 On what part of the body are they found ? How 

 are they arranged ? How many in each segment ? 



