384 KARM NARAYAN BAHL 
origin. Asa matter of fact the valves at the point of entrance 
of both the dorso-intestinals and the commissural vessels 
(dorso-tegumentaries) look like sphineter muscles when they 
are not in the protruding position and are flush with the wall 
of the dorsal vessel. It is not unlikely that the sphincter 
muscles seen in Moniligaster by Bourne are really the 
valves in the closed condition, which, like those of the dorsal 
vessel, have the form of circular ridges. In transverse sections 
of Pheretima they are seen as small club-shaped structures, 
attached to the inner wall of the commissural vessel just 
where the latter narrows to join the dorsal vessel, and having 
their broad ends projecting freely into the cavity of the dorsal 
vessel (fig. 9). Johnstone (8 and 9) describes a similar disposi- 
tion of valves in Lumbricus both in the dorso-intestinals 
and the commissurals, and I have verified it from my sections 
of Lumbricus. The disposition of valves and the course 
of blood-flow in these two vessels are therefore similar in both 
the worms (Lumbriecus and Pheretima) and probably 
in all earthworms. 
Another fact, which confirms my view with regard to the 
flow of blood into the dorsal vessel from the commissural 
(dorso-tegumentary) and not vice versa, is that in dissec- 
tions of the fresh worm when the flaps of body-wall are pinned 
down after a mid-dorsal incision, the commissural vessels are 
almost always torn off from the dorsal vessel near their point 
of entrance into the latter, and the blood oozes out not from 
the dorsal vessel or the portion of the commissural left attached 
to it, but always from the cut end of the commissural near 
the outer edge of the flaps. This shows that the direction of 
blood is towards the dorsal and not away from it. If the flow 
of blood were from the dorsal to the commissurals, we should 
see the dorsal emptying itself through the upper cut pieces 
of the commissurals, especially since the dorsal vessel keeps 
pulsating for some time after the worm is opened in the salt 
solution. As a matter of fact no blood oozes out of the dorsal, 
which remains full. 
Moreover, leaving aside the question of valves and the 
