284 



DIGESTION. 



tine, are due to defective digestion and assimilation. In spite of the great quantities of food 

 taken by these animals, the phenomena which precede the fatal result are simply those 

 of starvation. It may be that the biliary salts are absorbed by the blood and are neces- 

 sary to proper assimilation ; but there is no experimental basis for this supposition, and 

 it is impossible to discover these salts in the blood of the portal system by the ordinary 

 tests. It is more probable that the biliary salts influence in some way the digestive pro- 

 cess and are modified and absorbed with the food. 



The observations of Bidder and Schmidt show conclusively that the characteristic 

 constituents of the bile are absorbed in their passage down the alimentary canal. Hav- 

 ing arrived at a pretty close estimate of the quantity of bile daily produced in dogs, they 

 collected and analyzed all the faecal matter passed by a dog in five days. Of the dry 

 residue of the faeces, the proportion which could by any possibility represent the biliary 

 matters did not amount to one-fourth of the dry residue of the bile which must have been 

 secreted during that time. They also estimated the total quantity of sulphur contained 

 in the faeces and found that the entire quantity was hardly one-eighth of that which 

 was discharged into the intestine in the bile ; and, inasmuch as nearly one-half of that 

 found in the faeces came from hairs which had been swallowed by the animal, the experi- 

 ment showed that nearly all the sulphur contained in the non-crystallizable element of 

 the bile (the taurocholate of soda) had been taken up again by the blood. These obser- 

 vations show conclusively that the greater part of the bile, with the biliary salts, is ab- 

 sorbed by the intestinal mucous membrane. Prof. Dalton has attempted to follow these 

 principles into the blood of the portal system, but has never been able to detect the bili- 

 ary salts, by the most careful analysis. Like the peculiar principles of other secretions 

 which are reabsorbed in the alimentary canal, these substances become changed and are 

 not to be recognized by the ordinary tests, after they are taken into the blood. 



Although it is the digestion and absorption of fatty substances which seem to be 

 most seriously interfered with in cases of biliary fistula in the inferior animals, the rapid 

 loss of weight and strength indicates great disturbance in the digestion and absorp- 

 tion of other articles of food. A fact which indicates a connection between the bile and 

 the process of digestion is that the flow of this secretion, although constant, is greatly 

 increased when food passes into the intestinal canal. This has been noted by all who 

 have experimented on the subject. The following observations on the dog, showing the 

 variations in the flow of bile from the fistula, were made twelve days after the fistula had 

 been established, when the weight of the animal had been reduced from twelve to ten 

 pounds. 



Table of Variations in the Flow of Bile with Digestion. 



(At each observation, the bile was drawn for precisely thirty minutes.) 



