This complicated stomach is not identical in all the Ruminantia. In the Camels and the Llamas it presents many points of difference from that of all the other members of the group, and in the Chevrotains it has slight peculiarities of its own.

This organ, as found in the Ox—and it is almost identically the same in the Giraffes, the Antelopes, the Sheep, and Deer—is seen to be divided into four well-defined compartments, as represented in the accompanying figures. These are known as—

  1. The Rumen, or Paunch (b).
  2. The Reticulum, or Honey-comb Bag (c).
  3. The Psalterium, or Manyplies (d).
  4. The Abomasum, or Reed (e).

The paunch (b) is a very capacious receptacle, shaped like a blunted cone bent partly upon itself. Into its broader base opens the œsophagus, or gullet (a), at a spot not far removed from its wide orifice of communication with the second stomach, or honey-comb bag (c). Its inner walls are nearly uniformly covered with a pale skin (known as mucous membrane), which is beset with innumerable close-set, short, and slender processes (known as villi), resembling very much the “pile” on velvet. It is this organ, together with its villi, which constitutes the well-known article of food termed “tripe.”

The honey-comb bag (c) is very much smaller than the paunch. It is nearly globose in shape, and receives its name on account of the peculiar arrangement of the ridges on the mucous membrane which lines it, these being distributed so as to form shallow hexagonal cells all over its inner surface, as seen in the figure on the previous page.

It is situated to the right of the paunch, with which, as well as with the manyplies (d), it communicates. Running along its upper wall there is a deep groove coursing from the first to the third stomach. This groove plays an important part in the mechanism of rumination; its nature must therefore be fully understood.

Its walls are muscular, like those of the viscus with which it is associated, which allows its calibre to be altered. Sometimes it completely closes round so as to become converted into a tube by the apposition of its edges. At others it forms an open canal.

The manyplies (d) is a very peculiar organ. It is globular, but most of its interior is filled up with folds, or laminæ, running between its orifices of communication with the second and fourth stomachs. These folds are arranged very much like the leaves of a book, and very close together. They are, however, not of equal depth, but form series of greater or less breadth. Their surfaces are roughened by the presence of small projections or papillæ.

The reed (e) is the stomach proper, corresponding with the same organ in man. Its shape is somewhat conical. The valve which partially obstructs its communication with the intestine is at the left of the foregoing figure. Its walls are formed of a smooth mucous membrane, which secretes gastric juice, and it is this stomach that, in the manufacture of cheese, is employed to curdle the milk.

Whilst grazing, the possessor of this complicated stomach fills its paunch with the imperfectly masticated food, and it is not until it commences to chew the cud that any of the other parts are brought into play.