THE BILE. 221 



regarded as representing approximately that of the biliary substances 

 proper, the result shows that the quantity of ether-precipitate is, both 

 positively and relatively, very much less in the large intestine than in 

 the small. Its proportion to the entire solid contents is only one-fifth 

 or one-sixth as great in the large intestine as it is in the small. But 

 even this inconsiderable quantity, found in the contents of the -large 

 intestine, does not consist of biliary matters ; for, the watery solutions 

 being treated with sugar and sulphuric acid, those from both the upper 

 and lower portions of the small intestine always give Pettenkofer's reac- 

 tion perfectly in less than a minute and a half; while in that from the 

 large intestine no red or purple color is usually produced, even at the 

 end of three hours. 



The small intestine consequently contains, at all times, substances 

 presenting the usual reactions of the biliary ingredients ; while in the 

 contents of the large intestine no such substances can be recognized by 

 Pettenkofer's test. 



It is not possible to say, however, what is the precise nature of the 

 changes undergone by the biliary salts in the intestinal canal. The sup- 

 posed decomposition of these salts by contact with the acid secretions 

 of the alimentary canal, and the separation of the glycine, taurine, and 

 cholic acid of their organic ingredients, with their subsequent transfor- 

 mations, are all more or less hypothetical, and without sufficient basis of 

 experimental evidence. The biliary matters in the intestine pass, by 

 decomposition or metamorphosis, into the condition of other unknown 

 substances which do not respond to Pettenkofer's test. 



Physiological Function and Destination of the Bile. The physio- 

 logical function of the bile is still very obscure. With regard to its 

 action in the digestive process, we may say that nothing whatever is yet 

 known which can account for' the constant presence of so important and 

 peculiar a secretion. By itself, in experiments on artificial digestion, it 

 does not exhibit any direct action upon either of the principal alimentary 

 substances, of such a definite character as those which belong to the gas- 

 tric, pancreatic, and intestinal juices ; its action being limited to simple 

 solution of a certain proportion of oily matter, and to a feeble and incon- 

 stant transforming power upon hydrated starch. Two other actions have 

 also been attributed to it, from certain properties which observation 

 shows it to possess ; namely, first, that of exciting the secretions and 

 peristaltic movement of the intestine and thus serving as a natural 

 cathartic, and secondly, that of facilitating the absorption of oily matters 

 by the intestinal mucous membrane. But although the bile is found, when 

 applied to the muscular coat of the intestine, to excite its contraction, 

 and similar effects are thought to have been seen even in the villi, yet 

 the alimentary canal is known to be naturally excited to action by the 

 ingestion of food, or its downward passage from other parts ; and there 

 is nothing to show that the intestine, below the orifice of the biliary 

 duct, should require any peculiar or exceptional stimulus for the excite- 

 ment of its normal actions. It is true, in the second place, that the bile 



