ATRUDO. 195 
the crop the blood is slowly passed into the stomach and 
digested as required. 
The student will have noticed already in cutting open 
the leech (by a dorsal incision) that the interior is very 
different from that of Avenicola. There is no spacious 
coelomic cavity; the organs have to be picked 
out and the skin peeled off. This is due to 
the fact that the ccelom is filled up almost entirely by 
Colom 
Fig. 123. MAGNIFIED VIEW OF Two CONSECUTIVE SEGMENTS 
OF THE LEECH (10th and 11th). (Ad nat.) 
Nerve Cord in 
Ventral Sinus. 
Penis pulled in 
from exterior. 
Vas 
Deferens. 
connective tissue, the only parts of this cavity which are left 
being (1) a median dorsal sinus or space, (2) a median 
ventral sinus surrounding the nerve-cord, and (3) a few 
small spaces lying immediately over the testes. 
The blood-vascular system is complex and the blood- 
vessels have definite walls. There are two 
main J/ateral vessels which give off num- 
erous smaller branches. These communicate with a 
Blood-Vascular. 
