Several physiologists have given it as their opinion that bile is not essential to life, for animals have lived for many months after the artificial establishment of a biliary fistula, through which the bile was allowed to flow away, and be lost to the animal. Now, although this is perfectly true, yet it is at the same time evident that the uses of the bile cannot altogether be dispensed with, for all the animals with a biliary fistula lose flesh, become emaciated, and weak; the hair has a tendency to fall off, the bowels to become irregular; and a great and an almost constant discharge of foul-smelling gases takes place from the intestinal canal. At length, after a shorter or longer period, the animal sinks, and dies. The fatal termination can, however, be retarded by allowing him an additional quantity of nourishing food, for death from want of bile, as is too often seen in the human subject, is nothing else than death from slow starvation. The fact just related regarding the beneficial effects of an additional quantity of food in prolonging life, should never be lost sight of in the treatment of cases of obstruction of the gall-ducts, for, by attending to this circumstance, it is often in the power of the medical man to keep his patient alive for a considerable length of time. {14} It may perhaps not be out of place if I here briefly enumerate the chief uses of bile in the animal economy. In order to live, not only must the individual particles of our frames die, but they must be continually replaced by new materials of a similar kind; and for the accomplishment of this important end, nature has endowed animals with a digestive apparatus in which their food undergoes the various physical, and chemical changes necessary to its absorption, and assimilation. In the animal laboratory or digestive apparatus there are five important agents constantly at work--saliva, gastric juice, bile, pancreatic fluid, and intestinal secretion, and each of these agents has a special and definite office to perform in the elaboration of the food.[4] At present, however, I must limit myself entirely to the consideration of bile. [Footnote 4: For an explanation of these offices, see the author's article on "The Chemistry of Digestion," in the "British and Foreign Quarterly Review," January, 1860.]