Page:Proceedings of the Royal Society of London Vol 1.djvu/283

Rh fourth stomach. The glands, from which this ﬂuid is secreted, are very distinctly seen in the upper portion of the stomach of the deer; and in the lower portion are other glands, which secrete a ﬂuid, to complete the process of digestion by forming chyle.

In the porpoise and whale tribe the two processes of solution and chyliﬁcation are completely separate, as there can be no doubt of the food being dissolved before it arrives at the third stomach; since the opening leading into that cavity is too small to admit anything but ﬂuids to pass, and the analogy between the second and third cavities of the whale, with the two portions of the fourth of ruminants, is very great.

In the cod there are only two cavities, one for solution, with a structure that bears a strong resemblance to that of the second cavity of the porpoise, and having oriﬁces similar to those in the plicated portion of the stomach of the deer. Beyond this ﬁrst cavity in the cod, the food cannot pass till it is broken down; so that the analogy between the ﬁsh and the porpoise is very strong: in both one and the other, solution is a step previous to the formation of chyle, which is performed by secretions from glands of a different structure, and applied to the food in a different cavity. And in this, the bird, the ﬁsh, and the whale tribe, all agree. ,

The animals most nearly allied to the ruminants in their mode of digestion are those which occasionally ruminate, as the hate and the rabbit; and in these also that part of the stomach nearest to the (esophagus is never emptied, as happens in perfect ruminants.

The next variety in the process of digestion is that of the beaver and dormouse, in both' of which there is a glandular structure, peculiar in quantity, which seems to correspond with the solvent glands of other animals, and renders it probable that an increased secretion of solvent liquor renders rumination unnecessary.

Next to these follow animals with a cuticular reservoir, in which the food macerates before it is submitted to the process of digestion, as in the water rat, the common rat, and the mouse. In the ﬁrst there is a permanent division, but in the two last it is only muscular.

The stomachs of the horse and ass are also very nearly allied to these in their structure, and must be considered of the same kind.

That of the kanguroois peculiar, having pouches at its cardiac extremity lined with a glandular membrane. This stomach is, from its unusual length, more capable of subdivision into a number of cavities by muscular contraction; and Mr. Home thinks this form likely to facilitate regurgitation for the purpose of ruminating, which this animal has been seen to perform.

The other stomachs that are observed to have pouches at their cardiac extremity are those of the hog, pecari, hippopotamus, and elephant. That of the hog, excepting for a single pouch at its cardiac extremity, would very much resemble those of the horse or rat.

The stomachs that come next under consideration are those adapted to digest animal food. In these there is little difference observable in the cardiac portion (because animal substances are easily dissolved);