FUNCTIONS OF BILE. 175 



guinea-pig) any fluid can be forced into the circulation from the 

 bile ducts. 



It is observable also in the stoppage of the bile ducts in the 

 human subject, when some at least of the bile constituents con- 

 tinue to be formed, and pass into the blood, where their presence 

 is demonstrated by the yellow color characteristic of jaundice. 

 The ready evacuation of the bile is then a matter of great import- 

 ance for health, the least check to its free exit causing the secre- 

 tion, or as it might be equally well called excretion, to be forced 

 into the cirulating blood instead of into the gall passages. Under 

 normal circumstances, the large receptacle of the gall-bladder 

 being always ready to receive the bile insures its easy exit from 

 the ducts, but the forces which cause its flow are extremely weak. 

 The smooth muscle in the walls of the duct seems rather for the 

 purpose of regulating than aiding the flow. 



When food from the stomach begins to flow into the duodenum, 

 the muscular coat of the gall-bladder contracts and sends a flow 

 of bile into the intestine, which action is doubtless brought about 

 by a reflex nerve impulse, for it is only when this part is stim- 

 ulated that the bile flows freely from the bladder, and the acid 

 gastric contents seem to be the most efficacious stimulus. 



In the human subject the quantity of bile secreted has been 

 found to be about 600 cc. (21 oz.) per diem in cases where there 

 were biliary fistulae. This would equal about 13 grms. per kilo 

 of the body-weight. 



In the guinea-pig and rabbit it has been estimated to be about 

 150 grms. per kilo body- weight. 



FUNCTIONS OF THE BILE. 



1. As Excrement. Although the great bulk of the bile is re- 

 absorbed from the intestinal tract into the blood, and again used 

 in the economy, some of its constituents pass off with the faeces, 

 and are no doubt simply excrementitious matters that must be got 

 rid of. Thus all the cholesterin, mucus, and coloring matter are 

 normally eliminated, and a considerable quantity of the bile acids 

 are split up, the cholic acid being found in the faeces. 



