56 THE LIVEK. [CH. xxxm. 



sheep's-wool fat. It does not give Salkowski's reaction with 

 chloroform and sulphuric acid just described. 



The Uses of Bile. One of the most remarkable facts con- 

 cerning the bile is its apparently small use in the digestion of 

 food. It is doubtless, to a large extent, excretory. Some state 

 that it has a slight action on fats and carbohydrates, but it 

 appears to be rather a coadjutor to the pancreatic juice (especially 

 in the digestion of fat) than to have any independent digestive 

 activity. In some animals it has a feeble diastatic power. 



Bile is said to be a natural antiseptic, lessening the putrefactive 

 processes in the intestine. This is also very doubtful. Though 

 the bile salts are weak antiseptics, the bile itself is readily 

 putrescible, and the power it has of diminishing putrescence in 

 the intestine is due chiefly to the fact that by increasing absorp- 

 tion it lessens the amount of putrescible matter in the bowel. 



When the bile meets the chyme the turbidity of the latter is 

 increased owing to the precipitation of unpeptonised proteid. 

 This is an action due to the bile salts, and it has been surmised 

 that this conversion of the chyme into a more viscid mass is to 

 hinder somewhat its progress through the intestines ; it clings to 

 the intestinal wall, thus allowing absorption to take place. 



Bile is alkaline ; it therefore assists the pancreatic j uice in 

 neutralising the acid mixture that leaves the stomach. 



Bile assists the absorption of fats, as we shall see in studying 

 that subject. It is also a solvent of fatty acids. 



We have seen that fistula bile is poor in solids as compared 

 with normal bile, and that this is explained on the supposition 

 that the normal bile circulation is not occurring the liver cannot 

 excrete what it does not receive back from the intestine. Schiff 

 was the first to show that if the bile is led back into the 

 duodenum, or even if the animal is fed on bile, the percentage 

 of solids in the bile excreted is at once raised. It is on these 

 experiments that the theory of a bile circulation is mainly founded. 

 The bile circulation relates, however, chiefly, if not entirely, to 

 the bile salts : they are found but sparingly in the fseces ; they 

 are only represented to a slight extent in the urine : hence it is 

 calculated that seven-eighths of them are re-absorbed from the 

 intestine. Small quantities of cholalic acid, taurine, and glycocine 

 are found in the fseces ; the greater part of these products of the 

 decomposition of the bile salts is taken by the portal vein to the 

 liver, where they are once more synthetised into the bile salts. 

 Some of the taurine is absorbed and excreted as tauro-carbamic 

 acid in the urine. Some of the absorbed glycocine may be 

 excreted as urea or uric acid. The cholesterin and mucus are found 



