SECRETION OF BILE.
The secretion of bile is but a small part of the function of the liver, and that is by no means a purely eliminating process. Man secretes in twenty-four hours about 10 parts per 1,000 of body weight, the dog 14 to 15, the cat 15 to 20, the sheep 25, the rabbit 130, the Guinea-pig 170, the goose 12 (Cadeac), the horse 12 (Colin). But the amount varies largely; Scott found that a dog yielded 21, and Kölliker that another yielded 36 per 1,000 of the body weight.
Only about one-fourth of the biliary acids (Bischoff, Voigt), and one-eighth of the sulphur (Bidder and Schmidt) of the bile can be found in the fæces. Most of the bile is re-absorbed from the intestine and secreted anew, so that, in the course of twenty-four hours, the material secreted serves the same purpose again and again. During this repetition of secretion and absorption, it becomes little by little metamorphosed into other products, which are eliminated by the lungs and kidneys (Parkes, Murchison).
The functions of the bile so far as known are:
a. The solution of alimentary matters, and especially of fat, in the intestine, and the hastening of endosmosis, of fats and peptones;
b. The stimulation of peristalsis in the bowel;
c. Antisepsis and deodorization of the contents of the bowels;
d. The determination of the formation of glycogen;
e. The excretion of bile coloring matter, bile acids and cholesterine.
In regard to the glycogenic action it may be said that in cats, the bile ducts of which have been tied, no glycogen was formed, even when the diabetic puncture of the brain was made (Legg). Clinical observation seems to throw some doubt on the formation of bile coloring matter apart from the liver. In diseased liver with suspended secretion of bile (waxy and fatty degeneration, cancer, cirrhosis) the bile pigment was found in neither blood nor urine (Frerichs, Murchison, Haspell, Budd). Even after extirpation of the liver in frogs, neither biliary acid nor pigment could be found in the blood (Müller, Lehmann, Moleschott). These results must, however, be qualified by the observations of Hammersten who found bilirubin as a normal constituent of blood serum in the horse, and by Virchow’s discovery that hæmatoidin (now held to be identical with bilirubin) is constantly found in old blood extravasations into the tissues.