240 PHYLUM ANNELIDA. 
pockets point more or less backwards, it is evident that a 
leech to be emptied of the blood which it has sucked must 
be pressed from behind forwards. The pockets filled, the 
leech drops off its victim, 
seeks to retire into more 
private life, and digests 
at leisure. The digestion 
does not take place in the 
pockets, but in a small area 
just above the beginning 
of the terminal part or rec- 
tum. This rectum, running 
between the two last 
pockets, is separable from 
the true stomach just 
mentioned by a closing or 
sphincter muscle. It ends 
in a dorsal anus above the 
hind sucker. 
Vascular system.—Two 
main lateral vessels run 
longitudinally, one on each 
side of the body. They 
are connected with one 
another by looping vessels, 
give off numerous branches 
which riddle the spongy 
body, and have a definite 
muscular coat. On the 
dorsal surface and vent- 
rally around the nerve-cord 
are two lacunar spaces, 
which are really portions 
Fic. 124. —Dissection of leech. 
—After Bourne. 
c.g., Cerebral ganglia; 4., penis; s.v. 
is opposite the seminal vesicle; ov., 
ovary; uz., uterus; 7.d., vas de- 
ferens ; 2.4.v., lateral blood vessel ; 
T.4, fourth testis ; 2.v., nephridial 
vesicle: V.17, last nephridium ; 
G.19, nineteenth pair of ganglia; 
v.¢., nerve-cord. 
