Digestion begins at the mouth. Food is masticated by the movement of the lower jaw, broken into small pieces, moistened by the saliva, and starchy substances are converted into sugar. No change takes place during the rapid transit through the æsophagus. In the stomach the proteids are acted upon by the gastric juice and converted into peptones. Fats remain unchanged, and sugars are not acted upon. While these changes are proceeding, the thick grayish liquid, or chyme, formed by the imperfectly dissolved food, is from time to time ejected through the pylorus, accompanied even by large morsels of solid less digested matter. This may occur within a few minutes of food having been token, but the larger escape from the stomach probably does not begin till from one to two and lasts from four to five hours after the meal, becoming more rapid towards the end, such pieces as most resist the gastric juice being the last to leave the stomach. Substances can be absorbed from the cavity of the stomach into the circulation. The presumption is, that the diffusible sugars and peptones pass by osmosis direct into the capillaries, and so into the gastric veins. In the small intestines the semi-digested food, or chyme, as it passes the biliary orifice causes a gush of bile, and at the same time the pancreatic juice which flows freely into the intestine at the taking of the meal, is secreted again with renewed vigor, when the gastric digestion is completed. The conversion of starch into sugar, which may have languished in the stomach, is resumed with great activity by the pancreatic juice. The pancreatic juice emulsifies fats, and also splits them into their respective fatty acids and glycerine, and the bile is able to a certain extent to saponify the free fatty acids. It also appears that the slight emulsifying power of the bile is much increased by the presence of soap; and as a matter of fact, the bile and pancreatic juice do largely emulsify the contents of the small intestines, so that the grayish turbid chyme is changed into a creamy-looking fluid, which has been called chyle. These products as they are formed pass into the lacteals or the portal blood-vessels. Through the large intestine pass off indigestible or undigested constituents of the meal, and the gases generated. Absorption takes place from the stomach, and occurs along the course of the small and large intestines, especially of water. The largest and most important part of the digested material passes away from the canal during the transit of food along the small intestines, partly into the lacteals, partly into the portal vein.