220 INFLUENCE OF BILE AND BILE SALTS 



differences disappear. The bile salts still produce inhibition, 

 but the other two fractions no longer give rise to increased 

 proteolysis ; on the contrary, they tend to check the rate of 

 proteolysis. It is thus clearly evident that in bile there are 

 present various elements capable under different conditions of 

 producing divergent effects, in minor degree, upon pancreatic 

 proteolysis effects which may counterbalance each other to 

 some extent. 



V. INFLUENCE OP BILE AND BILE SALTS ON THE PRO- 

 TEOLYTIC ACTION OF THE PANCREATIC ENZYME IN 

 THE PRESENCE OF FREE AND COMBINED ACIDS. 



It has been generally accepted, on the basis of what has 

 seemed sufficient experimental evidence, that the proteolytic 

 enzyme of the pancreas is practically inactive in the presence 

 of free hydrochloric acid.* Even free organic acids inhibit 

 almost completely the action of the enzyme. Further, the 

 presence of combined acid, i. ., combined with proteid matter, 

 checks to a greater or less degree the activity of the digestive 

 fluid. Rachford and Southgate, however, state : " in our ex- 

 periment we have found that the proteolytic action of pan- 

 creatic juice on fibrin is quite as strong in a ^ per cent 

 hydrochloric-acid solution as it is in a neutral solution. If 

 there is any difference, in fact, it is in favor of the hydro- 

 chloric-acid solution." The statement is positive, but we can- 

 not find in their paper any conclusive evidence as to the actual 

 degree of acidity. Thus, to quote one of their experiments, 

 10 minims of pure pancreatic juice, 50 minims of water, and 

 30 minims of 0.1 per cent hydrochloric acid were mixed 

 together ; but how much of this acid was used in neutraliz- 

 ing the alkalinity of the pancreatic juice, and how much was 

 combined with the proteids of the secretion? Nowhere in 

 their paper can we find any evidence of discrimination between 

 free and combined acid, or any attempt to determine the actual 



* Chittenden and Cummins, Studies in Physiol. Chemistry. Yale Univer. 

 1885, vol. i, p. 135. This paper contains full references to other work in this 

 direction. 



