HEMORRHAGIC ENTERITIS 
15 
him, Schutz, Bouley, Cornevin and others alluded to it, but it 
remained for Bollinger, in 1870, to describe a typical case. 
Etiology and Anatomy .—The causes are many and varied. 
I shall concern myself with but one at present, and that, in 
my estimation, is a very fruitful one. I refer to parasitic 
aneurism of the anterior mesenteric artery, which occurs in 
seventy-five per cent, of all horses, and, in many sections, 
more than that. Roll and Bollinger gave ninety to ninety- 
four per cent, while Ellenberger, in eighty-five post mortems, 
found eighty-four horses with aneurisms. Now, as you all 
will remember, the anterior mesenteric is given off from the 
aorta at nearly a right angle, two and one half inches poster¬ 
ior to the cceliac axis, and supplies the larger part of the 
intestinal mass with blood; it is divided into three fasciculi 
(left, right and anterior); the left fasciculus has about twenty 
branches, the first few of which go to the duodenum and 
anastomose with the duodenal artery, a branch of the cceliac 
axis. The more posterior branches are longer, and anasto¬ 
mose with the ilio-coecal, a branch from the right fasciculus. 
The right fasciculus furnishes the ilio-ccecal, two ccecal and 
the right colic. The ilio-coecal, I have already stated, anasto¬ 
moses with branches from the left fasciculus. The ccecal 
arteries anastomose with each other. The right colic runs 
from the origin of the colon to its pelvic flexure, there inos¬ 
culating with the left colic. The anterior fasciculus has only 
two arteries of importance, left colic and the first, or small, 
artery of the floating colon. The left colic runs along the 
colon from its termination to the pelvic flexure in an inverse 
direction to the passage of the food, and there inosculates 
with the right colic. These arteries send loops or transverse 
branches to each other along their whole course. The first 
artery of the floating colon anastomoses with a branch of the 
posterior mesenteric. The profusion of anastomoses of these 
arteries, you see, provides for compression or even obstruc¬ 
tion, if not too sudden in occurrence, or too great in extent, 
as the blood can readily pass from the coeliac axis via the 
duodenal branch into the left fasciculus, thence to the ilio-coe¬ 
cal, thence to the left colic, thence to the right colic, and to 
