consequently we find with such food the most difficult digestion. In ruminants the canal is over twenty times the length of the body; and the stomach is divided into four chambers, to delay the food and complete the mechanical process. The first two, however, are more properly expansions of the gullet. The first chamber, called the paunch or rumen, stores and moistens the half-chewed food. This division in the camel has a portion lined with cells for storing water. The second chamber, known as the reticulum, or honey-comb stomach, receives this raw material, rolls and presses it into separate balls, which are sent up to the mouth for more perfect mastication. When this is complete, the now semi-fluid or pasty bolus, being unable to distend the aperture to the first and second chambers, flows into the third chamber. This has its lining greatly folded in order to detain coarse material, whence it is called manyplies or psalterium. The fourth chamber,
abomasum, is the stomach proper, as here alone is the food subjected to the gastric juice.
On account of defective mastication, the whales have at least three divisions of the stomach; many mammals have two divisions; and the toothless ant-eater has a gizzard.
Digestive Fluids.—After considerable investigation, the precise action of the several fluids which accomplish the chemical change of food is yet unknown. Indeed, their general function is still a matter in discussion. Naturally, then, our knowledge of the functions of the accessory digestive organs in the lower animals is limited. That digestion, however, in all animals is the result of chemical action under the influence of vital force seems assured.
Of the several fluids or chemical agents prepared within the laboratory of the digestive apparatus, the most important and indispensable
