MESENTERIC TUMOUR TAKEN FROM A HORSE. 
23 
large as the tumour itself. Its coat was not very thick, the 
thinnest part of it being where it was attached to the colon. 
The coagulum had been a long time in forming, as indicated 
by its colour and also its consistence. About one third of its 
bulk was of a light-straw^ colour, quite firm, and irregularly 
stratified. The middle third w^as less firm, and dark in 
colour, the red cells of the blood not having left its other 
solid constituents. The remaining portion was partly in a 
fluid state, the blood not having altogether coagulated. 
On examining that part of the sac which was occupied by 
the partially fluid blood two openings w^ere found, one of 
which could be traced directly into a large mesenteric vein 
and the other into the colon, the latter being produced by 
the coats of the tumour and also that of the intestine, having 
been so much thinned by absorption that it gave way, thereby 
allowing the contents of the tumour to flow freely into the 
colon. 
With reference to the origin of this large formation, I am 
inclined to look upon it as commencing from a varicosity of 
one of the veins of the mesentery, a little before it joins the 
vena portm. In this dilated vein the blood became partially 
arrested in its course, and a coagulum was formed, w hich, by 
being continually bathed with blood, slow ly increased in size, 
and with it the sac, until it reached its present dimensions. 
The outer walls of this tumour must also have gradually 
increased in thickness, which I think may have been due to 
a slow deposition of lymph between it and its peritoneal 
covering. The tumour being developed between the two 
layers of peritoneum forming the mesentery, they would, of 
course, be separated from each other, and the enlargement 
thereby gradually drawm more to the intestines before alluded 
to. The close contact with the colon favoured the adhesion 
we have before described. 
The interior of the sac was evidently supplied with blood 
by the mesenteric vein, w^hich opened into it, and so long as 
its w’all remained entire no particular inconvenience w'as 
experienced by the animal, except, perhaps, from the pressure 
it imparted to other organs; but the sac having at last yielded 
to the pressure within (at that part which w'e before noticed), 
the fluid blood it contained, and also that which con¬ 
tinued to flow into it from the vein, found its way at once 
into the large intestine. The result is very easily imagined, 
and the symptoms described by Mr. Fletcher can as readily 
be accounted for. 
It is interesting to notice the difference in the results of 
an adhesion of an intestine to a tumour of this character as 
