In ruminating animals, such as the sheep and ox, the stomach, as will be seen from the annexed figure, not only is large, to adapt it to the bulky nature of their food, but is complicated in its structure, to fit it for effecting the great changes which vegetable aliment requires to undergo before it can be converted into blood. It may indeed be said to consist of four distinct stomachs conjoined. In the first of these, AA, termed the _paunch_, the herbage is deposited when first swallowed after hasty and ineffectual mastication. It there undergoes a kind of maceration or steeping in a fluid provided for the purpose; after which it passes from the paunch into a smaller bag, called the _reticulum_, or bonnet, B, which, in some animals, such as the camel and dromedary, is designed exclusively as a reservoir for water, which being there stored up in large quantities, ready for use when wanted, fits them in a wonderful manner for travelling through the arid deserts where no water is to be obtained, and where, without some such provision, they would of course soon perish. So admirably is the reticulum adapted for this special purpose, that the water contained in it undergoes little or no change either in quality or quantity, although if it were collected in the ordinary digesting stomach, it would be entirely absorbed in the course of a few minutes. It is not even mixed with the food which is swallowed after it, as the animal has the power of directing solids at once into the other cavities. From the reticulum the alimentary mass is again returned to the mouth, there to be thoroughly masticated and mixed with the saliva; after which it descends a second time through the gullet: but instead of passing, as before, into the paunch, it enters the third bag, _omasum_, or many-plies, C, where it undergoes farther changes, and is then transmitted to the fourth portion D, adjoining the pylorus, and named _ab-omasum_, or red-bag. The last portion is exactly similar in structure and in function to the simple stomach of man and the other mammalia, and is in fact the true stomach, the other three being merely preparatory organs. The first part of the process, by which the food is taken hastily into the paunch and afterwards sent back to the mouth in detached portions for farther mastication, is called _rumination_ or _chewing the cud_, and those species which perform it are thence called _ruminating_ animals. Sheep and cows may be seen lying ruminating in pasture-fields after having cropped as much herbage as fills the paunch; and feeding is thus rendered to them a source of prolonged enjoyment.