PHYSIOLOGY OF THE LIVER AND SPLEEN. 809 



tion playing an important role in the absorption of fats, and pos- 

 sibly in other ways. Bile is a continuous secretion, but in animals 

 possessing a gall-bladder its ejection into the duodenum is inter- 

 mittent. Bile is easily obtained from living animals by establish- 

 ing a fistula of the bile-duct or of the gall-bladder, or by the use 

 of the "duodenal tube," a small stomach-tube which when swal- 

 lowed works itself through the pylorus and gives a means for 

 aspirating the contents of the duodenum. From observations 

 made upon human beings in whom most of the bile was drained 

 to the exterior through a biliary fistula it has usually been assumed 

 that whatever part the bile takes normally in digestion and 

 absorption, its passage into the intestine is not absolutely neces- 

 sary to the nutrition of the body. This usual belief has been 

 denied, so far at least as the dog is concerned. Whipple and 

 Hooper* state that when the bile is wholly excluded from the 

 intestinal tract the animal shows intestinal disorders and dies 

 within a month. The quantity of bile secreted during the day 

 has been estimated for human beings of average weight (43 to 73 

 kgms.) as varying between 500 and 800 c.c. This estimate is based 

 upon observations on cases of biliary fistula.! Chemical analyses 

 of the bile show that, in addition to the water and salts, it contains 

 bile pigments, bile acids, cholesterin, lecithin, neutral fats and soaps, 

 sometimes a trace of urea, and a mucilaginous nucleo-albumin for- 

 merly designated improperly as mucin. The last-mentioned sub- 

 stance is not formed in the liver cells, but is added to the bile by the 

 mucous membrane of the bile-ducts and gall-bladder. The quantity 

 of these substances present in the bile varies in different animals 

 and under different conditions. As an illustration of their relative 

 importance in human bile and of the limits of variation, the two 

 following analyses by Hammarsten J may be quoted : 



I. II. 



Solids 2.520 2.840 



Water 97.480 97.160 



Mucin and pigment 0.529 0.9r0 



Bile salts 0.931 0.814 



Taurocholate 0.3034 0.053 



Glycocholate 0.6276 0.761 



Fatty acids from soap 0.1230 0.024 



Cholesterin 0.0630 0.096 



Fa?**^^" } 0.0220 0.1286 



Soluble salts 0.8070 0.8051 



Insoluble salts 0.0250 0.0411 



The color of bile varies in different animals according to the pre- 



* Hooper and Whipple, "American Journal of Physiology," 40, 332, 1916 

 t Copeman and Winston, "Journal of Physiology," 10, 213, 1889; Robson,. 



"Proceedings of the Royal Society," London, 47, 499, 1890; Pfaff and Balch, 



"Journal of Experimental Medicine," 2, 49, 1897. 



J Reported in "Centralblatt f. Physiologie," 1894, No. 8. For other 

 ; consult Rosenbloom, "Journal of Biological Chemistry," 14, 241, 1913. 



