Bile precipitates the proteins of the chyme, neutralizes the acidity of the gastric juice, dissolving the fatty acids, and activates the lipase or steapsin of the pancreatic juice and assists in the absorption of fats. When for any reason the discharge of bile is retarded and the organism attempts to eliminate it through the kidneys, the tissues become charged with its compounds and take on a yellowish coloration. _Pancreatic Juice._—The second action upon the food in the intestine is that of the bicarbonate of soda contained in the pancreatic and intestinal juices, which neutralizes its acidity; and pancreatic digestion can only take place in an alkaline medium. The pancreatic juice has the most comprehensive action of all of the digestive fluids; it contains a great variety of enzymes and acts upon all classes of nutrients. Its flow is intermittent, being induced by the action of the acids in the partially digested food from the stomach. The pancreatic secretion attains its maximum pressure about three hours after a meal, but this varies according to the character of the meal. The enzymes of the pancreatic fluid are _trypsin_, _amylopsin_, _lipase_ or _steapsin_, and _pancreatic rennin_. _Trypsin._—Pancreatic juice alone has but little influence on proteins, but when mixed with succus entericus its influence is great. Trypsin differs from pepsin by acting in an alkaline or neutral solution, and a free mineral acid, like hydrochloric, stops its operations; it acts much more powerfully and rapidly than pepsin. In conjunction with other enzymes it splits protein foods into simpler compounds, which may be regarded as the building stones of the original proteins. _Amylopsin._—The digestion of starch in the intestine is mainly effected by means of a diastatic ferment or enzyme in the pancreatic juice, called “amylopsin.” This enzyme has the power of hydrolyzing the starch mostly into maltose. _Steapsin or Lipase._—The pancreatic secretion acts vigorously on fats, not only splitting them into fatty acids and glycerin, but, in conjunction with the bile, also effects their emulsification. This latter result is doubtless aided by the soaps which form a union of the fatty acids and alkaline bases (mostly sodium) in the bile. The cleavage of the fats is due to the enzyme steapsin. The _succus entericus_ is the secretion of the glands of Lieberkühn. It contains quite a number of enzymes, including four which act on carbohydrates, namely, _amylase_, _maltose_, _lactase_, and _invertase_; the proteolytic enzyme is _erepsin_, which seems to supplement the action of trypsin. It has no action on native proteins except casein, but it breaks down proteoses and peptones into _amino-acids_.