THE EARTHWORM AND HIS WORK. 149 
where they may remain for several weeks. Then put 
them in a one per cent. solution of chromic acid for five 
or six days. Remove 
them from this solu- 
tion, wash them thor- 
oughly in water and 
place them in a dish 
with turpentine, al- 
lowing them to re- 
main there for a few 
days longer. They 
may then be dried, Fic. 120. — An Earthworm. 
when they are ready 
for use. The worms should be spread out in flat- 
bottomed dishes during the processes of tanning. 
With specimens thus prepared or simply hardened in 
alcohol, the class should write the answers to the fol- 
lowing questions: 
Do the worms all have the same number of seg- 
ments ? 
Do you find several rings together which seem to be 
enlarged? This is the cltellum or reproductive girdle. 
How many segments from the clitellum to the head 
end? 
Is the body of the angleworm smooth? Does it 
appear more rough when the finger is moved in any 
special direction? The roughness is caused by bristles 
or set@. Do they all point in the same direction ? 
How many rows of sete along the body? How 
many setz on a single segment? 
Does the worm have an internal skeleton? Does a 
thin cuticle separate easily from the body of a worm 
which has been soaking in water for a time ? 
Can you make out the shape of the segment in front 
of the mouth ? 
Summary of Drawings. (2) The whole worm, nat- 
ural size. 
(6) The segments near the head x 6. 
