MECHANISM OF BILE SECRETION. 
By D. Noel Paton. 
Contents. — Mode of Formation of Bile Constituents, p. 559 — "Water, p. 559 — 
Inorganic Salts, p. 560— Nucleo-Proteid, p. 561 — Bile Acids, p. 562— Bile Pig- 
ments, p. 563 — Cliolesterin, p. 564 — Lecithin, etc., p. 564— Influence of various 
Factors on the Secretion of Bile, p. 564 — Flow of Blood, p. 565 — Food, p. 565 
— Pressure of other Organs, p. 567 — Nerves, p. 567 — Chemical Substances, p. 
567 — General Conclusions, p. 569. 
Ix considering the mechanism of bile secretion, it must be remembered 
that the formation of bile is only one of many functions performed by 
the liver. 
Placed as it is upon the course of the portal vein, the great channel 
of absorption of material from the alimentary canal, the liver regulates 
the supply of carbohydrates to the body by storing the surplus sugar 
absorbed in the form of glycogen. It also gets rid of any excess of 
nitrogen absorbed, by converting it into the innocuous and easily 
eliminated urea. In addition to performing these functions, the liver 
acts as one of the great storehouses of iron in the body, and in many 
animals it is also a situation in which surplus fats are accumulated. 
When these numerous functions are considered, the small amount of 
bile formed per diem by so large an organ is the less surprising. In man 
about 800 or 900 grms. of bile, with about 14 or 15 grms. of solids, are 
daily secreted from the liver, an organ which weighs about 1600 grms. 
In studying how bile is formed in the liver, it is necessary to 
remember that, besides the great mass of liver cells, there are in- 
numerable bile passages lined by a living epithelium. In most animals 
a saccular diverticulum, the gall bladder, is developed upon these 
passages. In this and in the passages the surplus bile accumulates. 
How far the liver cells, and how far the cells lining the ducts, act in 
producing the various constituents of bile, must be subsequently con- 
sidered. 
The bile is a fluid containing many different sul (stances in solution 
(see article, " Chemistry of Bile " ), and an invest igatii in of the mechanism 
of bile secretion necessitates a consideration of the mode of production 
of each of these. 
Mode of Formation of Bile Constituents. 
Water. — The water of the bile is in part secreted from the walls 
of the bile passages, for it has been found that when the cystic duct 
is occluded, and the fundus of the gall bladder opened, a small amount 
