ON PANCREATIC PROTEOLYSIS. 197 



however, are wholly wanting in the paper in question, hence 

 we are forced simply to take the results and guess at the actual 

 conditions under which they were obtained. Further, so-called 

 pure pancreatic juice, like the other digestive secretions, is 

 subject to constant modification by the character and extent of 

 the stimulation which calls it forth, while the character and 

 condition of the semi-digested food passing from the stomach 

 into the duodenum, together with the amount of free and 

 combined acid, must necessarily lead to variable conditions in 

 the duodenum. Add to this the well known variations in the 

 rate of flow and composition of the bile, and we may well ask 

 what are the conditions which normally prevail in the duode- 

 num ? Obviously, we cannot make a definite answer within 

 very close limits, for the conditions are bound to be more or 

 less variable. What we have to ascertain, therefore, is the 

 influence of bile and its constituents upon the proteolytic 

 action of the pancreatic juice or its specific enzyme under the 

 various conditions which are liable to exist in the upper part 

 of the small intestine. This, in our judgment, can be studied 

 to the best advantage by the use of artificial pancreatic juice, 

 or extracts of the active gland, where the quantity obtainable 

 will be sufficient to admit of comparative experiments under 

 definite conditions. Moreover, the artificial pancreatic juice will 

 not be widely different in the character of the proteid matter 

 present from the natural secretion employed by Rachford and 

 Southgate. Thus, these investigators state that from four to six 

 hours were required for about 1 c.c. of the pancreatic juice to 

 flow from the fistula. Plainly, during this interval the active 

 proteolytic enzyme present would transform the natural proteids 

 of the juice into peptone, amido-acids, etc., as completely as 

 the transformation would be accomplished in the extracts them- 

 selves. Hence, in this respect at least, both fluids must differ 

 from the natural secretion normally poured into the intestine. 



I. METHODS EMPLOYED. 



The pancreatic extracts employed in our experiments were 

 prepared from two kinds of glands and by two distinct 



