ON PANCREATIC PROTEOLYSIS. 



207 



be detected by litmus and lacmoid, but due mainly at least 

 to the presence of salts or compounds which are either acid 

 to phenolphthalein, or which exist side by side with such 

 compounds. Lastly, we would emphasize the fact already 

 brought out, that the so-called acidity of the bile, and likewise 

 the so-called alkalinity, have different values in different 

 species of animals, and may likewise vary in the same species 

 under different conditions of diet, etc. 



The bearing of these facts upon the problem before us is 

 sufficiently manifest. The addition of bile to a neutral pan- 

 creatic fluid (neutral to litmus) must plainly introduce a 

 change in the reaction, as measured by either litmus, lacmoid, 

 or phenolphthalein. Further, owing to the variations in the 

 acidity and alkalinity, already referred to, it is clear that differ- 

 ent samples of bile will produce different results, and when it 

 is remembered how sensitive the proteolytic enzyme trypsin 

 is toward changes of reaction, it is obvious that this feature 

 cannot be overlooked in considering the influence of bile upon 

 pancreatic proteolysis. 



Let us consider now the character of the bile used in some 

 of the preceding experiments on proteolysis. 



These data show us at once that in introducing say 10 per 

 cent of bile into the digestive mixtures, variations in reaction 

 must necessarily ensue. Contrast, for example, the bile used 



* Expressed in milligrams NaOH required to neutralize 1 gram bile, phe- 

 nolphthalein as indicator. 



t Expressed in milligrams HC1 required to neutralize 1 gram bile, lacmoid 

 as indicator. 



