The phenomena of rumination suppose a power of voluntary motion in the part. And indeed the influence of the will in the whole function is incontestable. It is not confined to any particular time, since the animal can delay it according to cir cumstances, when the paunch is quite full. It has been expressly stated of some men, who have had the power of ruminat ing, (instances of which are not very rare) that it was quite voluntary with them. Blumenbach knew two men, who rumi nated their vegetable food : both assured him that they had a real enjoyment in do ing this, which has also been observed of others ; and one of them had the power of doing it, or leaving it alone, according to circumstances.
The final purpose of rumination, as ap plicable to all the animals in which it takes place, and the chief utility of this wonderfully complicated function in the animal economy, are still completely un known. What has been already suggest ed on these points is completely unsatis factory. The old dream of Aristotle and Galen, that rumination supplies the place of incisor teeth, the materials of which are applied, in these animals, to the formation of horns, scarcely deserves mention. Perault and others supposed, that it contributed to the security of these animals, which generally eat much and are timid, by showing the necessity of their remaining long employed in chew ing in an open pasture. But the Indian buffalo ruminates, although it does not fly even from a lion, but rather attacks, and often vanquishes that animal : and the wild goat dwells in Alpine coun tries, which are inaccessible to beasts of prey.
The peculiar structure of the stomach in the camel and lama, which enables these animals to take at one time a suffi cient quantity of water to last them for two, three, or more days, and thereby renders them adapted to inhabit the dry and sandy deserts, which constitute their natural abode, is highly worthy of atten tion. The fluid which they drink is depo sited in numerous cells, formed in the substance of their first and second sto machs, by strong bands of muscular fi bres crossing each other at right angles. It should seem that the animal has the power of closing these cells by the con traction of those fibres which form the mouths of the cavities, or of expelling the contained fluid by putting the other portions of fibres in action.
This cellular structure is found in two parts of the first stomach ; and it occu pies the whole of the second. It was found in a dead camel, that these cavities would hold two gallons of fluid ; but they were probably more capacious during life, as the animal in question always drank six or seven gallons of water every other day, and took more in the interme diate time. Mr. Bruce states, in his travels,
that he procured four gallons from one which he slaughtered in Upper Egypt. " Shaw's Abridgment of Bruce's Travels." Ed. 3. p. 371.
As all the food which the animal takes passes into the first stomach, the water of the cells in that part becomes turbid ; but it remains perfectly pure in the se cond, where it resides in the greatest quantity ; which circumstance accounts for traveller being able to drink it on an emergency. The muscular bands, which form the groove described in the ac count of the ruminating stomach, are par ticularly strong ; and by drawing the third stomach to the cesophagus, convey the ruminated food through the second, without polluting the water in its cells. Hence the food that has been macerated in the paunch must be sent back to the mouth directly from that cavity, without passing into the second stomach, as it does in the cow. See " Observations on the camel's stomach respecting the water which it contains," &c. by E. Home, esq. Philos. Trans. 1806.
The structure of these parts in the lama, according to the account which Cuvier has given o them, from the examination of a fetus, does not seem to differ essentially from that of the camel.
There is a peculiar glandular body at the upper orifice of the beaver's stomach, about the size of a florin, full of cavities that secrete mucus. It re sembles, on the whole, the bulbus glan dulosus of birds, and assists in the digestion and animalization of the dry food which this curious animal takes, con sisting chiefly of the bark and chips of trees, &c.
According to Cuvier, there is a gland as large as the head of a man, situated be tween the coats of the stomach in the manati (trichechus manatus borealis). It is placed near the esophagus, and dis charges, on pressure, a fluid like that of the pancreas, by numerous small open ings.
Mr. Home is of opinion that the glandu lar structure exists in the stomach of the sea-otter near the pylorus. Philos. Trans. 1796. pl. 2. And Mr. Macartney has dis covered an arrangement of glandular bo dies in the dormouse, round the cesopha gus, just before its termination, similar in situation and appearance to the gastric glands of birds.
The stomach of the pangolin (manis pentadactyla) is almost as thick and mus cuter as that of the gallinaceous fowls, and contains, like that of granivorous birds, small stones and gravel, which are probably swallowed for the same purpose as in those birds.