254 INTESTINAL DIGESTION. 



the fat taken with the food passes through the intestine and is found in the 

 faeces. 



The action of the bile in exciting muscular contraction, particularly in the 

 non-striated muscular fibres, is well established. It has been shown by Schiff 

 that this fluid acts upon the muscular fibres situated in the substance of the 

 intestinal villi, causing them to contract, and according to his view, assisting 

 in the absorption of chyle by emptying the lacteals of the villi. The ques- 

 tion, however, of the absorption of fats is difficult of investigation. Not- 

 withstanding the obscurity in which this subject is involved, it is certain that 

 the progressive emaciation, loss of strength, and final death of animals de- 

 prived of the action of the bile in the intestine, are due to defective digestion 

 and assimilation. Notwithstanding 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 necessary 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 process and are absorbed in a modi- 

 fied form with the food. 



The observations of Bidder and Schmidt show that the characteristic con- 

 stituents of the bile are absorbed in their passage down the alimentary canaL 

 Having arrived at an 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 possibil- 

 ity 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 sulphur contained in the faeces and found that the entire 

 quantity was hardly one-eighth of that which was discharged into the intes- 

 tine 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 sodium taurocholate had 

 been taken up again by the blood. These observations show that the greater 

 part of the bile, with the biliary salts, is absorbed by the intestinal mucous 

 membrane. Dal ton attempted to follow the constituents of the bile into the 

 blood of the portal system, but was unable to detect the biliary salts. Like 

 the peculiar constituents of other secretions which are reabsorbed in the ali- 

 mentary canal, these substances become changed and are not to be recognized 

 by the ordinary tests, after they are taken into the blood. 



While 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 show great disturbance in 

 the digestion and absorption of other constituents 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. 



Although it has been demonstrated that the presence of the bile in the 



