DECOMPOSITION OF THE BILIARY CONSTITUENTS. 217 



corresponding fatty acids, but the process extends further and as a 

 result a gradual reduction of the higher acids to the lowest forms 

 takes place. To a certain extent these are then absorbed and 

 further decomposed in the body, but a not inconsiderable portion is 

 directly eliminated in the feces, and we accordingly find here repre- 

 sentatives of the group, from palmitic, stearic, and oleic acids down 

 to butyric acid and acetic acid. The glycerin is absorbed, and is to 

 a certain extent no doubt utilized in the synthesis of fats. 



The lecithins are decomposed in the same manner as under the 

 influence of steapsin, with the formation of glycerin-phosphoric acid, 

 fatty acids, and cholin. Whether or not the latter may then be 

 transformed into neurin is not known, but under normal condi- 

 tions this probably does not occur. The glycerin-phosphoric acid 

 is subsequently no doubt absorbed together with some of the fatty 

 acids, and appears in the urine as such. The cholin, on the other 

 hand, is further decomposed, with the formation of ammonia, carbon 

 dioxide, and methane. 



BACTERIAL DECOMPOSITION OF THE BILIARY CON- 

 STITUENTS. 



In former years it was supposed that the biliary acids after their 

 elimination into the intestinal canal were there largely absorbed 

 and returned to the liver, while a smaller portion was decomposed 

 and eliminated in the feces. 



Within more recent years there has been a tendency among 

 physiologists to deny the existence of a circulation of the bile acids, 

 on the basis principally that bile acids could normally not be 

 demonstrated in the blood or in the urine. Croftan, however, has 

 shown that after all such a circulation may exist, for he succeeded 

 in demonstrating the presence of biliary acids in the leucocytes. 

 Occurring in this form, however, it suggests itself that they may 

 play the role of foreign matter and do not enter into account 

 physiologically. 



That portion of the bile acids which is not resorbed is decomposed 

 in the intestinal canal, and in the human being dyslysius only are 

 encountered in the feces while the amino-radicles have apparently 

 been further broken down. In other animals glycocholic acid has 

 been found, but taurocholic acid apparently always succumbs to the 

 action of the bacteria. Of the fate of the amino-radicles w r e know 

 little, but it is possible that both are in part further decomposed and 

 in part absorbed. Taurin may then appear in the urine either as 

 such or as tauro-carbaminic acid ; but it may, on the other hand, again 

 combine with cholalic acid and reappear in the bile. The glycocoll 

 similarly may in part be transformed into urea ; or it may combine 

 with the non-hydroxylated aromatic acids which are also formed 

 during the process of intestinal putrefaction, and appear in the 



