The final stage is the digestion by the pancreatic juice. After the food has been exposed for some time to the gastric juice, it is allowed to escape a little at a time from the stomach, and continues its way along the alimentary tube. Before it has gone many inches it comes to the openings of two ducts, those of the liver and the pancreas, and immediately the acid stimulates them, and the glands pour out their secretion. That of the liver is largely excretion or refuse from the blood without direct action on the food, but it enables the pancreatic juice to do its work by making the food again alkaline, and stimulates the muscular coats of the intestine to force its contents along. That of the pancreas is the most important digestive fluid in the body, containing many ferments; it acts alike on proteids, carbohydrates, and fats—in fact, digests everything—so that the rest of the long tube is freed from any more laborious duty than absorbing them as they pass. NOTE.—The digestive ferments are now prepared for examination by chopping up the gland and placing it in glycerine; this extracts the ferment and preserves it from the action of bacteria. The first experiments on digestion, however, constitute one of the romances of physiology. A Canadian named St. Martin got into trouble with Red Indians whilst in the United States, America, and was shot through the body. The surgeon who attended him was unable to make the wound close, and when it healed there remained an opening in the man’s body communicating directly with his stomach. The surgeon, Beaumont, saw possibilities in this, and, obtaining gastric juice from his patient, made those classical experiments which entitled him to a place among the fathers of physiology. Americans do well to be proud of Beaumont, for it cost him many sacrifices, and his patience and courage are above praise. Not only was he devoid of all but the crudest appliances out in the backwoods, but his subject proved intractable and mercenary. No sooner did he discover his value than he crossed the border, and refused to return except upon exorbitant payment. Even after this had been arranged, he repeated the performance whenever he thought fresh extortion possible. In spite of these difficulties, the investigations proved wonderfully accurate and complete. IV. Of the absorption of the materials thus prepared it is not necessary to say much in a work of this compass, but the absorption of oxygen is too important to be passed over.