ON THE USE OF THE OMENTUM. 
609 
tine from its relative position in the abdomen ; very little friction, 
therefore, is likely to take place between the peritoneum of the 
colon and that of the parietes of the abdomen, and, conse¬ 
quently, an omentum is not required in that situation. 
In the ox, sheep, and other ruminating animals, however, the 
paunch is large, and rests upon the abdominal parietes to a great 
extent. In them, if the extensive plain surface of the stomachs 
had to move on the similarly plain surface on which they rest, 
there would of necessity, from the weight of the rumen, be a 
considerable degree of friction; but to prevent that, and to faci¬ 
litate the motion of the paunch, which is considerable, there is 
interposed between them an auxiliary substance—the omentum ; 
and this extends throughout the whole of that part of the abdomen 
where this pressure is most severe, and serves therefore to assist 
the movements of the parts on each other, with a facility which 
could not otherwise exist. The fat, too, which it contains, con¬ 
tributes much towards this effect; for being in a semifluid state, 
and in irregular masses, it more readily assists in the movements 
which are taking place by yielding to them, and is increased in 
quantity where it is most required for this purpose. The small 
quantity of fat which the omentum of the horse contains suffi¬ 
ciently shews that it is not a reservoir for this substance, as some 
have been led to imagine. 
In the dog, the hog, and many other animals, there are different 
conditions of the parts. In these animals the stomach is small 
when compared with the ruminants, and the intestines have not 
the marked difference in size which is so conspicuous in the 
horse; yet, in these animals, the omentum is large, and extends 
from the diaphragm back to the pelvis, interposed between the 
parietes of the abdomen and the intestines, containing a consi¬ 
derable quantity of detached portions of fat, but by no means 
the quantity found in oxen, and animals with a similar arrange¬ 
ment of organization. 
All these quadrupeds have a rapid peristaltic motion of the intes¬ 
tines ; and this rapid peristaltic motion being essential to the 
well-being of the animal, requires to have an omentum so formed 
and arranged as to facilitate their motion most readily ; and 
such we find to be the case. The omentum in these animals slides 
more freely between the intestines and the parietes of the abdo¬ 
men, or rather aids those parts to change their relative position 
more readily than in the other classes of animals to which I have 
alluded. 
From what I have stated, and from what is to be found upon a 
more extensive and general examination of the subject than I 
have thought myself warranted to make, I am led to conclude, 
