VASCULAR SYSTEM OF PHERETIMA 381 
question is, what is the course of blood in these two kinds of 
vessels? Does the blood come into the dorsal from both or 
from only one ? According to Bourne (1, p. 74) and Vejdovsky 
(11, p. 115), the blood flows from the intestinal capillaries into 
the dorsal vessel through the dorso-intestinals, and in this 
I agree with them. In recently-killed worms I have cut these 
dorso-intestinals to see from which of the cut ends the blood 
flows, and 1 have invariably found blood oozing out from the 
side of the intestinal capillaries. Moreover, the arrangement 
of valves which I refer to later confirms this view. With 
regard to the course of blood in the commissural vessel (* dorso- 
tegumentary ’ of Bourne in Moniligaster), I believe with 
Perrier (as quoted by Bourne in 1) and Benham (1, p. 255) 
that blood enters the dorsal vessel from these commissurals. 
Bourne (1, p. 75), however, believes that blood leaves the dorsal 
vessel by the dorso-tegumentaries. But later on in his paper on 
Moniligaster, after discussing the point in an elaborate 
manner (2, p. 335) and concluding that Benham’s view is 
incorrect and that blood flows outwards from the dorsal by 
the dorso-tegumentaries, he adds (2, p. 386), ‘ the peripheral 
capillaries in the region of the body behind the hearts are 
also supplied, to an extent which probably varies from time 
to time and is, | expect, never very great, from the dorsal 
vessel by means of the dorso-tegumentary vessels.’ Further 
on in the same paper (p. 850), while generalizing on the vascular 
system of earthworms, Bourne refers again to the course of 
blood in the dorso-tegumentaries (commissurals) and says, 
‘I have again and again returned to the course taken by the 
blood in these vessels (dorso-tegumentaries). I cannot help 
thinking that primitively they are efferent vessels, and that 
both they and the dorso-intestinal vessels 
bring blood to the dorsal vessel. In this case 
they can only have, in worms otherwise well provided with 
a venous system, the function suggested above for Monili- 
gaster grandis of regulating the pressure in the peripheral 
capillaries, and have practically no flow in them in one direc- 
tion or the other.’ Bourne here seems to give away his case 
