THE BILE. 227 



to dryness, the dry residue extracted with absolute alcohol, and the 

 alcoholic solution treated as usual to discover the presence of biliary 

 matters. In every instance, blood was taken at the same time from the 

 jugular vein, or the abdominal vena cava, and treated in the same way 

 for purposes of comparison. 



We have examined the blood, in this way, one, four, six, nine, eleven 

 and a half, twelve, and twenty hours after feeding. The result shows 

 that in the venous blood, both of the portal vein and of the general circu- 

 lation, there exists a substance soluble in water and in absolute alcohol, 

 and precipitable by ether from its alcoholic solution. This substance 

 is often considerably more abundant in the portal blood than in that 

 taken from the general venous system. It adheres closely to the sides 

 of the glass vessel after precipitation, so that it is always difficult, and 

 often impossible, to obtain enough of it, mixed with ether, for micro- 

 scopic examination. It dissolves, also, like the biliary substances, with 

 great readiness in water ; but in no instance have we ever been able 

 to obtain from it such a reaction with Pettenkofer's test, as would 

 indicate the presence of bile. This is not because the reaction is 

 masked by any other ingredient of the blood ; for if, at the same time, a 

 little bile be added to blood taken from the abdominal vena cava, in the 

 proportion of one drop of bile to seven or eight cubic centimetres of 

 blood, and the two specimens treated alike, the ether-precipitate may 

 be considerably more abundant in the case of the portal blood ; and yet 

 that from the blood of the vena cava, dissolved in water, will give Pet- 

 tenkofer's reaction for bile perfectly, while that of the portal blood will 

 give no such reaction. 



Notwithstanding the evidence, therefore, that the biliary matters are 

 absorbed by the portal blood, they cannot be recognized there by Pet- 

 tenkofer's test. They must accordingly have passed through such 

 changes, in the intestine, previously to their absorption, that they can 

 no longer give the ordinary reaction of the biliary salts. We cannot 

 say precisely what these changes are, but they are undoubtedly depen- 

 dent upon the action of the intestinal juices, and are therefore more rapid 

 while the process of digestion is going on. This is probably the ex- 

 planation of the fact that the bile, though a continuous secretion, is dis- 

 charged into the alimentary canal in greatest abundance immediately 

 after the ingestion of food ; since it is not so much needed to assist the 

 intestinal juices in the process of digestion, as to be itself acted on by 

 them and converted into other materials. 



The bile, accordingly, is a secretion which has not yet accomplished 

 its function when it is discharged from the liver and poured into the 

 intestine. While in the cavity of the alimentary canal, in contact with 

 its glandular surface, and mingled with the intestinal juices, its ingre- 

 dients lose their original character and pass into the form of new com- 

 binations. These substances again enter the circulation by absorption 

 from the intestinal cavity, and are carried away by the blood, to com- 

 plete their function in some other part of the body. 



