DIGESTION

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DIGESTION is that process in the animal hotly, by which the aliments are dissolved, and the nutritive parts are separated from those which cannot afford nourishment to the body. The organs effecting this process are divided into the digestive organs, properly so called, and the auxiliary organs. The former are composed of the divisions of the intestinal canal, which includes the stomach, the great and small intestines, &c. To the latter belong the liver, the pancreas and the spleen. The first process of digestion is the solution of the aliments. When the aliments, after being properly prepared, and mixed with saliva by masticntion, have reached the stomach, they are intimately united with a liquid substance called the gastric juice, by the motion of the stomach. By this motion, the aliments are mechanically separated into their smallest parts, penetrated by the gastric juice, and transformed into a uniform pulpy or fluid mass. At the same time, a solution of the aliments into their simple elements, and a mixture of them so as to form other products, takes place, effected partly by the peculiar power of the stomach and the liquid generated in it, partly by the warmth of this organ. This pulpy mass, called chyme (q. v.), proceeds from the stomach, through the pylo rus, into the part of the intestinal canal called the large intestines (q. v.), where it is mixed with the pancreatic juict< and tb# bile. (See Bile, and Pancreas.) Both these liquids operate most powerfully on the chyme, yet in very different ways. The mild juice of the pancreas attracts the milklike liquid of the chyme, and forms with it the chyle,which is absorbed by the capillary vessels called lacteals. On the other hand, the bitter matter called bile, formed by the liver from the blood, attracts the coarser parts, which are not fitted to be absorbed into the fine animal organization, and excites the intestinal canal to the motion which carries it off. (For further information on the subject of digestion, particularly of diseased digestion, see the article Dyspepsia.) Digestion, with chemists and apothecaries ; the maceration of any substance which is to be softened or dissolved, commonly pulverized, in a solvent liquid. It is enclosed in a tight vessel, and exposed to a gentle heat for a longer or shorter time. By this process essences, elixirs and tinctures are made.