STUDIES ON EARTHWORMS. Dit 
in somites x1f and xi11 communicate both with the dorsal and 
with the typhlosolar trunks on the one hand and with the 
ventral trunk on the other. Thus in the Anteclitelliani the 
hearts are anterior to, whilstin the other groups they are either 
posterior to the gizzard or in its neighbourhood. 
The subneural trunk is absent in Pleurocheta, Peri- 
cheta, and Pontodrilus [and in Microcheta]. 
The Course of the Blood.—The blood passes forwards 
along the dorsal (and typhlosolar) trunks and backwards 
along the ventral (and neural) trunks. The intestinal vessels 
rising from the dorsal trunk carry blood to the wall of the 
intestine, where there is a very close network of vessels, 
usually made up of longitudinal and circular branches; from 
this capillary network the blood is carried into the ventral 
trunk. From the ventral trunk a pair of vessels in each 
somite carries blood to the septa, nephridia, and body wall, 
where it is distributed in delicate loops and collected again by 
vessels which enter the dorsal trunk. This seems to be the 
course of the blood, as determined in Microcheta, where 
valves are placed in the dorsal trunk, at the exits and entrances 
of the vessels. 
Anteriorly the blood is distributed over the wall of the 
pharynx and collected from the network into the ventral 
trunk. In the lateral hearts the blood passes downwards from 
the dorsal to the ventral trunk. 
In the longitudinal lateral trunks the course of the blood 
seems to vary. In Lumbricus, it is evident that it passes 
forwards to be distributed over the pharynx, whence it is col- 
lected by the branches going to the ventral trunk. In Uro- 
cheta, Perrier considered this forward direction preferable ; 
while in Pontodrilus he thinks it probable that the blood 
has not the same direction as in the dorsal trunk. 
The Blood, by which I refer to the red liquid in the closed 
system of vessels, is a liquid, coloured red by hemoglobin, in 
which float oblong colourless corpuscles, as has been shown by 
Lankester in 1878 to be the case in Lumbricus (45), and 
by Bourne and Blomfield in 1881 for the Polycheta (46). 
