The bile contains two classes of constituents, one of which are true secretions, and destined to renter the system and perform certain functions. They contain, with other matters, some that are formed in the liver, and are no doubt elaborated from materials furnished by the blood. These are the salts included in the accompanying table under the names of taurocholate and glycocholate of soda. Biliverdin, the coloring matter of the bile, is probably a mixture of different coloring principles which undergo rapid change on ex posure to the air. It has some analogy to the coloring matter of the blood, and it is also, like the biliary salts, supposed to be formed in the liver. This coloring matter has intense power. and in eases of obstruction of the biliary passages will give the skin and conjunctiva' a decidedly yellow color. Like hemoglobin, it contains a portion of iron, hut the relative amount has never been ascertained. The other constituents of the bile are truly excretory, being composed of effete matter brought by the blood-vessels from the various parts of the system. In this class is cholesterin, which has long been known as a constituent of the bile, whose chemical and physical characteristics were well recognized, but whose physiological relations were not under stood. (See CHOLESTERIN.) In regard to the glycogenic function of the liver, it may be stated that nearly all physiologists admit that Bernard demonstrated it completely, al though for a long time many apparently well made experiments seemed to throw great doubt on the subject, some believing that the sugar found by Bernard was a product of post-mortem changes. 1 t is a fact that it is difficult to find
sugar in the liver which may not he said to be produced after death]; consequently, demonstra tive experiments are exceedingly difficult. Oa ex amining the blood which comes from the lungs in animals upon which vivisection has been per formed it is found to contain no sugar. Other experiments have left no doubt of the fact that, to serve some purpose in the animal economy, sugar is destroyed in its passage through the lungs, the most generally received view being that it is converted into lactic acid, which unites with the alkalies in the blood to form lactates, which again are converted into carbonates. It is thought that among the causes of the disease diabetes is an abnormal performance of the func-• tion of respiration (q.v.). The glycogenic mat ter of the liver, in composition, reactions, and particularly in its readiness to be transformed into sugar, has considerable resemblance to starch, and is called by some authors arnyloid matter. On account of its insolubility in water it may be extracted from the liver after all the sugar has been washed out. See LIVER, DISEASES OF THE.
Consult: Morris, human Anatomy (Phila delphia, 1902) ; Flint. The Physiology of Man (New York, 1875) ; and Flint. The Excretory Function of the Liver (Philadelphia, 1877).