FUNCTIONS OF THE STOMACH. 
387 
The rumen is the largest of all the stomachs. It is situated 
on the left side of the cavity of the abdomen—extending from 
the diaphragm to the pelvis; its inferior surface resting on the 
floor of the abdomen, and its superior one being in contact with 
the left flank. It is divided by a large scissure or muscular 
band into two distinct sacs; and these are again subdivided, 
thus forming four compartments. These separations are for the 
purpose of retarding the food in its passage through the rumen, 
so that the process of maceration may be more eflectually 
carried on. 
The rumen is composed of four coats—an external peritoneal, 
a muscular, a glandular, and an internal dermoid or cuticular. 
The internal coat is studded with numerous papillae, which are 
most developed at the centre of each compartment. They are 
erectile, and are for the purpose of protecting the follicular glands 
beneath them from being injured by the food as it passes over 
them. They also assist in retarding the food and in mixing it 
with the mucus or alkaline fluid, which is secreted by these 
glands. 
There are two openings into the rumen, one through the two 
pillars communicating with the oesophagus, and the other (which 
is guarded by a valvular fold of the rumen, running obliquely 
across it) leading to the second stomach or the reticulum. This 
stomach is situated anteriorly and rather to the right side of 
the upper or left sac of the rumen, and between it and the dia¬ 
phragm. It is, I believe, considered to be the smallest of the 
four stomachs, and is composed of the same number of coats as 
the rumen, differing from it only in that its internal coat con¬ 
sists of numerous wide and shallow cells, which present a beau¬ 
tiful net-work appearance. On their sides and in their centres 
are developed innumerable papillae, which have undoubtedly a 
secerning function. It has two openings into it, one which I 
have already mentioned from the rumen, and the other through 
the posterior part of the two pillars communicating with the 
oesophagus. 
The third stomach, or maniplus, is situated posteriorly to the 
reticulum, between the liver and the right sac of the rumen. It 
is of a most j)eculiar but beautiful structure, consisting of a series 
of folds or plaits, whicli are arranged in a perfect and exact 
order. Thus, a long fold hangs down from the roof of the 
stomach, floating freely within it, and reaching down to its 
floor : on each side of this is another lesser one, and beyond that 
another, until the last one is very small. Then commences 
another group similarly arranged : this is followed by a third, 
and so on, until the viscus becomes filled, or, as it were, made 
