374 DIGESTION. 



ence in some way the digestive process and are modified and 

 absorbed with the food. 



The observations of Bidder and Schmidt show conclu- 

 sively 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 

 in that time. They also estimated the total quantity of sul- 

 phur contained in the faeces, and found that the entire quan- 

 tity 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 experiment 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. 1 These observations 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 biliary 

 salts, by the most careful analysis. 2 Like the peculiar prin- 

 ciples of other secretions which are reabsorbed in the aliment- 

 ary 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 sub- 

 stances which seem to be most seriously interfered with in 

 cases of biliary fistula in the inferior animals, the rapid loss 

 of weight and strength would indicate great disturbance in 



1 BIDDER UND SCHMIDT, Die Verdauungssafte, Leipzig, 1852, S. 217, 218. 



2 DALTON, Treatise on Human Physiology, Philadelphia, 1864, pp. 179 and 

 198. 



