THE EARTH-WORM. Ad 
and possibly between the tenth and eleventh seg- 
ments, These are the openings of the spermatheca. 
Other openings will be seen on the two last segments 
of the clitellum; these are the openings of the 
mucous glands. ‘The anus is at the posterior end of 
the body. With a magnifying glass, four double 
longitudinal rows of sete will be observed, two 
ventral and two lateral. 
3. Internal structure—Pin the anterior portion of the 
animal to the leaded cork, dorsal side upward. Make 
a small transverse cut with the scissors behind the 
clitellum ; then, steadying the lower blade of the 
scissors against the tip of the middle finger of the 
left hand, insert the point into the cut, and carry a 
longitudinal incision a little to the right of the 
middle, up to the anterior end. In order to avoid 
cutting the alimentary canal in this process, the point 
of the scissors must be inserted a very short distance 
for each cut ; and before making each cut the integu- 
ment of the worm should be lifted up by the inserted 
point of the scissors. 
4, Put the cork with the worm into a saucer, and cover 
with water. Place two or three pins in the cut 
integument on the right side of the worm. Then, 
using the dissecting microscope, pull back the integu- 
ment of the left side gently with the forceps, cutting 
with a sharp knife the transverse mesenteric septa 
which hold it, and pin it down. 
5. Notice the supra intestinal vessel of the pseud-heemal 
system, filled with a bright red fluid, lying on the 
intestine, and sending off two transverse vessels in 
each segment to join the sub-intestinal vessel lying 
below the intestine, and therefore hidden by it. In 
