358 KARM NARAYAN BAHL 
portion of the plexus in this region consisting of longitudinal 
capillaries lying parallel with one another along the intestine 
all round the circumference ; and the third region comprises 
the last twenty-three to twenty-eight segments of the animal, 
where the blood-plexus differs markedly from what we have 
in the first two regions. he difference in appearance of the 
blood-plexus in the three regions is illustrated in fig. 3, where 
at the pomt marked « there is a sudden change in the arrange: 
ment of capillaries from the second to the third region. While 
there is a regular, almost rectangular arrangement of the 
capillaries in the anterior two regions of the gut, the capillaries 
in the posterior region (last twenty-three to twenty-eight 
segments) branch off in a tree-like fashion from the dorso- 
intestinal vessels. That the three regions mentioned above are 
distinct from one another will be evident from the fact, ascer- 
tained by a study of sections passing through the three regions, 
that in the first region (fourteenth to twenty-sixth segment) 
the intestinal capillaries form only the internal plexus, the 
external plexus being absent, that in the second region 
(twenty-sixth segment onwards) there are both the internal 
and external plexuses well developed, while in the third region 
(last twenty-three to twenty-eight segments) we have no 
internal plexus at all, all the capillaries belonging to an external 
plexus. 
Besides the difference in the arrangement and position of 
capillaries in the three regions there is another feature which 
also distinguishes these three regions from one another, and 
that is the presence and absence of a typhlosole and the 
typhlosolar vessel. ‘aking the last region first, we have to 
note the entire absence of a typhlosole in this region. Bed- 
dard (8) describes the absence of typhlosole in the last few 
segments of Acanthodrilus, and ealls this last part of 
the gut without a typhlosole the ‘rectum’. Similarly, the 
typhlosole is absent in the gut in the last thirty-six segments 
of Lumbricus, and we can apply the term ‘rectum’ to 
these last thirty-six segments of Lumbricus and the last 
twenty-three to twenty-eight segments of Pheretima. 
