212 INFLUENCE OP BILE AND BILE SALTS 



merely an illustration of the well-known fact that a weak 

 alkaline fluid is much more favorable for pancreatic proteolysis 

 than a neutral fluid. We are inclined to attribute such 

 retardation of proteolysis as bile induces when added to an 

 alkaline pancreatic fluid in great part to the reduction of alka- 

 linity liable to occur. We say liable because this will depend 

 primarily upon the relative proportion of acid and alkaline 

 salts in the bile. When the latter contains a relatively large 

 proportion of acid salts, as indicated by phenolphthalein, the 

 addition of large percentages of such a bile will rapidly diminish 

 the amount of sodium carbonate present, since the latter will 

 be more or less used up in transforming the acid compounds 

 into neutral ones. This is well illustrated in Experiment 20, 

 wherein actual examination showed that at the conclusion of 

 the digestion all the mixtures containing more than 15 per 

 cent of bile had lost entirely their alkaline reaction toward 

 litmus. In other words, the acid-reacting compounds con- 

 tained in 10 grams of this bile was sufficient to neutralize the 

 0.125 gram of sodium carbonate originally present in the 

 mixture. In harmony with this fact it is to be noted through- 

 out these latter experiments that retardation is most marked 

 in the presence of those biles which have been shown to have 

 as a rule the highest acidity, viz., pig's bile and human bile. 

 With dog's bile, on the other hand, in which acidity is usually 

 very slight, no retardation whatever was observed; all three 

 experiments gave evidence of some slight stimulation of pro- 

 teolysis. The occasional stimulation noticed with sheep's bile 

 and pig's bile we attribute in part to the lower acidity of the 

 samples used. Leaving these points out of consideration, 

 however, and turning our attention to the collected data, it 

 is plain that the addition of even 40 or 50 per cent of bile 

 to an alkaline pancreatic fluid does not greatly retard the 

 proteolytic action of the enzyme (see Experiments 19, 21, 

 and 24), certainly no more than would result from neutraliza- 

 tion of the alkalinity. By this we do not mean that the 

 specific bile salts are without influence on pancreatic proteoly- 

 sis, but merely that the changes in reaction resulting from 



