388 
RUMINATION, AND THE 
up of them. These plaits or leaves consist of a folding or double 
reflection of the cuticular coat, with muscular fibres interposed : 
on their external surface are developed innumerable small pro¬ 
minences, which are of a very hard, firm texture, and become 
more so as they approach near to the edges, where they assume 
a hook-like shape. They are most numerous at the anterior part 
of the viscus, where they are most required, and least so at the 
posterior part which communicates with the abomasum. 
The abomasum is the true digestive stomach; for it is here 
that the food, which has been prepared by the other stomachs, 
becomes mixed with the gastric juice, and is formed into 
chyme. It is of a conical form, the base being anteriorly 
situated. It is placed posteriorly to the maniplus, and to the 
right of the right sac of the rumen. It is lined internally by a 
villous membrane, which is arranged in longitudinal folds. 
These are most developed at the anterior or wide part; and, 
generally, there is one more particularly so at the entrance into 
the maniplus, allowing the free passage of the food from it to 
the abomasum, but entirely preventing its return, and thus dis¬ 
charging the function of a valve. The abomasum communicates 
posteriorly by its pyloric extremity with the duodenum ; and here 
its muscular coat becomes thicker and stronger, and forms a kind 
of sphincter. It is more largely supplied with blood and with 
nervous energy than any of the other stomachs. 
The intestines of the ruminant are not so large as in the 
horse, but considerably longer. 
I will now, imperfectly I fear, but as well as I am able, en¬ 
deavour to explain the physiology of the structure I have been 
attempting to describe. 
The food having passed down the oesophagus, comes in contact 
with the two muscular pillars, which are immediately over the 
left sac of the rumen ; and, either by instinctive influence, or by 
mechanical force, the pellet being hard, and the muscles of the 
gullet strong, these pillars are forced open, and the food falls 
into the left sac of the rumen. 
The food is then, by the contraction of the muscular coat of 
the rumen, propelled through its different compartments, be- 
comino; mixed with the fluid which is there secreted, and also 
with that that has been swallowed and entered into the rumen. 
It is macerated and prepared for another process. The ox takes 
a deep inspiration. The diaphragm becomes tense, and presses 
upon the rumen and reticulum anteriorly. The abdominal mus¬ 
cles contract, and lend their aid posteriorly. The stomachs 
themselves also act powerfully, and contract upon their contents, 
and a portion of food (which had been jncviously forced out of 
