226 THE BILE. 



near its inner end, which might be left open or kept closed by shifting 

 the position of an inner tube fitting closely in the canula. Thus the bile 

 might be at will either discharged externally from the orifice of the 

 canula, or allowed to pass into the duodenum by its lateral opening. It 

 was found that, after being discharged externally for even two or three 

 hours previously to the examination, its rate of secretion was much less 

 than if it had been allowed to pass into the intestine. The results 

 obtained, in a dog weighing 12 kilogrammes, were as follows: 



CUBIC CENTIMETRES OF BILE OBTAINED IN TEN MINUTES AFTER HAVING BEEN, 

 FROM Two TO THREE HOURS, 



Evacuated externally. Discharged into the duodenum. 



2.2 6.0 



2.3 5.4 

 2.1 5.6 

 2.0 6.2 



1.8 6.5 



1.9 5.7 



Average . . 2.05 5.90 



Thus the quantity of bile secreted, when it has been allowed to follow 

 its natural course into the duodenum, is nearly three times as great as 

 when it has been evacuated through the external fistula. It does not 

 necessarily follow from this that it is again directly used for secretion 

 by the liver, since this process may be influenced by a variety of sec- 

 ondary conditions ; but it is difficult to avoid the conclusion that its 

 ingredients are absorbed from the intestinal cavity, and supply in some 

 way the materials for continued secretion. 



Before their reabsorption, however, the biliary salts undergo certain 

 alterations in the alimentary canal, so that when finally taken up by the 

 bloodvessels, they have already assumed a different form; otherwise 

 they could be detected in the blood of the portal vein. But such re- 

 searches have constantly led to a negative result. Our own experiments 

 on this point were performed on dogs, by examining the portal blood 

 obtained at different periods after feeding. The animals were killed by 

 section of the medulla oblongata, a ligature immediately placed on the 

 portal vein, while the circulation was still active, and the requisite 

 quantity of blood collected by opening the vein. The blood was some- 

 times immediately evaporated to dryness by the water-bath. Sometimes 

 it was coagulated by boiling in a porcelain capsule over a spirit lamp, 

 with water and an excess of sodium sulphate, and the filtered watery 

 solution afterward examined. But most frequently the blood, after 

 being collected from the vein, was coagulated by the gradual addition 

 of three times its volume of alcohol, stirring the mixture constantly, so 

 as to make the coagulation gradual and uniform. It was then filtered, 

 the moist mass remaining on the filter subjected to strong pressure in a 

 linen bag, by a porcelain press, and the fluid thus obtained added to that 

 previously filtered , The entire spirituous solution was then evaporated 



