ANATOMY OF THE EARTHWORM. 107 
established between the three longitudinal trunks—between 
the great dorsal and the sub-intestinal by the deep commis- 
sural vessels, between the ventral and the dorsal and sub- 
intestinal by the internal superficial tegumentary plexus, and, 
again, between all three by the capillaries into which they 
break up at either extremity of the worm. 
There is, however, another distribution of the branches of 
the great trunks by which they become connected, and it is 
in the diaphragmatic muscles and the segment-organs. A 
branch is given off on either side in each segment from the 
sub-intestinal vessel near the anterior septum, from the 
ventral vessel near the posterior, and these on either side 
entering the diaphragmatic muscle are distributed to the 
segmental organs in the manner described in my last paper, 
forming small lacunze and networks most intricately and 
intimately ramified ; and thus we have in connection with 
each segment-organ a special afferent and efferent branch. 
The latero-dorsal vessels send ramifications through the 
diaphragmatic muscles with which they are closely con- 
nected, as also do the branches from the ventral vessel, which, 
though not so constant and regular in their disposition as the 
pair of vessels in each segment given off from the dorsal 
trunk, may nevertheless be conveniently spoken of as the 
latero-ventral branches. Neither the latero-dorsal nor the 
latero-ventral vessels send any branches whatever to the seg- 
mental organs, which are supplied solely by the special 
branches from the sub-intestinal and ventral vessels; these 
branches may therefore be called the afferent and efferent 
excretorial vessels. 
A modification of the visceral circulation takes place in 
the seven segments posterior to the seventh. It is in these 
segments that the organs of generation are situated, as also 
the three pairs of cesophageal glands, organs which are all 
most profusely supplied with the vascular fluid, and for the 
purpose of feeding which it would be supposed that the ar- 
rangements of an ordinary segment would be found inade- 
quate. Accordingly, parallel to the sub-intestinal vessel 
are found two others, one on either side, with which the 
enlarged, deep, commissural vessels, or hearts, communicate 
(fig. 2, p). Branches are given off from all three of 
these longitudinal vessels to the various organs; the central 
sub-intestinal vessel supplying, especially, the testes and 
ciliated inductors of the vasa deferentia, whilst the parallel 
additional vessels seem more closely connected with the 
cesophageal glands. 
We have, then, in the various segments of the worm’s 
