21 



shown by Delezenne, as well as by Bayliss and myself, that normal 

 pancreatic juice as secreted contains no trypsin whatsoever. It has, 

 indeed, a feeble proteolytic ferment, which is powerless to digest 

 coagulated proteids or even solid gelatin and only slowly attacks un- 

 boiled fibrin or caseinogen. The proteolytic ferment of fresh pancreatic 

 juice is therefore no stronger than the ferments which can be extracted 

 from almost any tissue of the body. In the presence of succus entericus, 

 however, the pancreatic juice speedily develops a proteolytic power more 

 marked than that of any other proteolytic ferment we are acquainted 

 with. It dissolves proteids, whether or not coagulated, and rapidly 

 carries them through the stages of hydration to their end-products of 

 amino-acids, bases, and so on, effecting in this way a thorough destruc- 

 tion of the proteid molecule. Certain French observers, Delezenne, 

 Dastre, and others, have imagined that the interaction of enterokinase 

 and trypsinogen is of the same nature as the interaction between antibody 

 and complement, which is necessary for the destruction of red blood discs 

 by haemolytic sera. Experiments by Bayliss and myself have shown that 

 this view is untenable and have confirmed Pawlow's original statement 

 that the activating effect of succus entericus on pancreatic juice is due 

 to the presence of a body which acts like a ferment. Our results have 

 been fully confirmed more recently by Hekma in Holland and by Falloise 

 in Belgium. 



Enterokinase is active in such minute quantities that the presence 

 of the minutest trace of mucous membrane in a pancreatic juice will 

 suffice to activate the latter. It is important that the activation of 

 the proteolytic ferment should take place as speedily as possible after the 

 entry of pancreatic juice into the intestine, and there must therefore be 

 some means by which a flow of succus entericus containing enterokinase 

 is evoked in direct proportion to the amount of pancreatic juice entering 

 the intestine. That such a mechanism is present and is of a chemical 

 nature there can be little doubt, although some discrepancy still exists 

 between different observers as to the exact nature of the chemical 

 mechanism. We have commenced to study the subject, but our experi- 

 ments are not yet far enough advanced to enable us to decide between 

 the rival views. It is necessary to bear in mind that very considerable 

 differences may exist between the mechanism of secretion of succus 

 entericus in the upper and lower parts of the small intestine. It has 

 long been known that there is a gradual increase in the absorbing powers 

 of the intestine as we proceed from its upper to its lower end, and every 

 worker with intestinal fistula? has noticed an inverse ratio between the 

 secreting powers of the different parts of this tube, secretion being most 

 abundant in the duodenum and least abundant in the lower parts of the 

 ileum. It is possible, therefore, that the various mechanisms described by 

 different observers are really all involved, but that their importance varies 

 according to the part of the canal under investigation. Pawlow, as the 

 result of experiments carried out on dogs with intestinal fistulas, came 

 to the conclusion that two main factors were involved in the secretion of 



