FATE OF THE BILE IN THE INTESTINE. 367 



acids are not effective for carrying on gastric digestion; the peptone is precipitated 

 by them; neutralisation also causes a precipitate of pepsin and mucin. As 

 soon, however, as the walls of the stomach secrete new acid, the pepsin is redis- 

 solved. The bile which passes into the stomach deranges gastric digestion, by 

 shrivelling the proteids, which can only be peptonised when they are swollen up. 



182. Fate of the Bile in the Intestine. 



Some of the biliary constituents are completely evacuated with the 

 faeces, while others are reabsorbed by the intestinal walls. 



(1.) Mucin passes unchanged into the faeces. 



(2.) The bile pigments are reduced, and are partly excreted with the 

 faeces as hydroUliruUn ( 177, 3 g), and partly as the identical end-product 

 uroUlin by the urine. 



Hydrobilirubin is absent from Meconium, while bilirubin and biliverdin and 

 an unknown red oxidation product of it are present (Zweifel). Hence, no reduc- 

 tionbut rather oxidation processes occur in the foetal intestine (Hoppe-Seyler). 



(3.) Cholesterin is given off with the faeces. 



(4.) The bile salts are for the most part reabsorbed by the walls of 

 the jejunum and ileum, to be re-employed in the animal's economy. 

 Tappeiner found them in the chyle of the thoracic duct minute quan- 

 tities pass from the blood into the urine. Only a very small amount 

 of glycocholic acid appears unchanged in the faeces. The taurocholic 

 acid, as far as it is not absorbed, is easily decomposed in the intestine, 

 by the putrefactive processes, into cholalic acid and taurin ; the former 

 of these is found in the faeces, but the taurin at least seems not to be 

 constantly present. 



As putrefactive decomposition does not occur in the fo3tal intestine, unchanged 

 taurocholic acid is found in mecoiiium (Zweifel). The anhydride stage of cholalic 

 acid (the artificially prepared choloidinic acid ?), dyslysin, is an artificial product, 

 and does not occur in the fseces (Hoppe-Seyler). 



(5.) The faeces contain mere traces of Lecithin (Wegscheider, Bokay). 



The greatest part of the most important biliary constituents, the bile acids, 

 re-enter the blood, tind thus is explained why animals with a biliary fistula, 

 where all the bile is removed (without the animal being allowed to lick the bile), 

 rapidly lose weight. This depends partly upon the digestion of the fats being 

 interfered with, and also upon the direct loss of the bile salts. If such dogs are 

 to maintain their weight, they must eat twice as much food. In such cases, carbo- 

 hydrates most beneficially replace the fats. If the digestive apparatus is other- 

 wise intact, the animals, on account of their voracity, may even increase in weight, 

 but the flesh and not the fat is increased. 



The fact that bile is secreted during the foetal period, whilst none of 

 the other digestive fluids is, proves that it is an excretion. 



The cholalic acid which is reabsorbed by the intestinal walls passes into the 

 body, and seems ultimately to be burned to form C0 2 and H 2 0. The glycin (with 



