The secretion of the pancreas is a clear, colourless, alkaline liquid of syrupy consistence. The quantity of juice secreted is relatively small, but the organic substances which it contains are in a concentrated form. They constitute as much as 10 per cent. of the pancreatic juice. Proteins are present, if the juice be fresh. If it has stood for any length of time, they are found as peptones. The digestive ferments of pancreatic juice are the most powerful which are secreted into the alimentary canal. =Bile.=—In its most important functions the liver has no relation to digestion. It is a storehouse of absorbed food. This organ will therefore be treated in a separate chapter. The bile which the liver secretes into the alimentary canal has no chemical action on any of the constituents of food, with the exception of a feeble tendency to digest starch. Yet it is in some degree accessory to digestion. Poured into the second portion of the duodenum through an orifice common to the liver and the pancreas, it mingles with the semi-digested food, or “chyme,” which, about two hours after a meal, passes through the pyloric valve. Gastric digestion has converted the greater part of the proteid constituents of the food into peptones or intermediate stages. The proteoses or propeptones—a name is needed for the intermediate products of proteid digestion which does not commit us to any theory as to their chemical constitution—are quickly peptonized by the pancreatic juice. But portions of the proteins have escaped the action of gastric juice, or have at most been affected by its acid only; these are precipitated by the bile-salts on the mucous membrane of the small intestine, which is raised into projecting flanges for the purpose of delaying the passage of the chyme, in order that it may be thoroughly submitted to the digestive action of pancreatic juice. Bile-salts also favour the digestion of fat, and its passage through the intestinal wall. The action of bile-salts in spreading fats is well known to artists. Ox-gall is smeared upon glass when it is desired to apply oil-paints to its surface. When mixed with oil, it causes its emulsification, or breaking up into microscopic globules. In the absence of bile, but little fat passes into the lymph-vessels which convey digested food from the intestine to the thoracic duct, and so to the great veins of the neck. Its action is mechanical. It favours the digestion of fats by rendering them easily amenable to hydrolysis by pancreatic juice.