Lastly, the general opinion is that the secretion intermits, and, like the gastric, and pancreatic juices, bile is only formed during digestion. Were it so, however, where would be the necessity for a gall-bladder? Is it not to store up the secretion formed in the intervals of digestion, and to retain it until it is required? No doubt there are several animals, such as the horse, and the deer, that possess no gall-bladders; but there is undoubtedly in them some special arrangement of the digestive apparatus, rendering the presence of a gall-bladder unnecessary. In fact, it is easily shown that the biliary secretion in ordinary cases is continuous; for if in an animal possessing a gall-bladder a biliary fistula be established, and the secretion of bile carefully watched, it will be found that at no period of the day does it entirely intermit, although it is more active at one time than at another, the minimum of its activity being during sleep--the maximum during active digestion. The absolute quantity of bile secreted in the twenty-four hours is tolerably uniform, although the daily amount is slightly influenced by the kind of food.[3]
[Footnote 3: Arnold found that dogs secreted more bile on a bread, than on an animal diet. "Zur Physiologie der Galle," Mannheim, 1854.]
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.