RELATIONSHIP BETWEEN SPLEEN AND PANCREAS. 375 



outset hardly any active pepsin., but a zymogen accumulating 

 in its glands in the intervals of digestion, so the pancreas does 

 not at once elaborate active trypsin, but a substance destined 

 to become trypsin under certain conditions and in a certain 

 phase of the digestive act, this substance being, of course, the 

 pancreatic zymogen trypsinogen, or protrypsin. The researches 

 of Heidenhain are well known, and it suffices to recall here 

 only one or more essential points: Thus from them we know 

 that the pancreas of a fasting dog contains little or no trypsin, 

 but merely trypsinogen; consequently its glycerin infusion 

 possesses little or no digestive power; the infusion, however, 

 of a dog in full digestion digests rapidly and copiously, because 

 it contains trypsin. If the pancreas of a fasting dog be divided 

 into two equal portions, one of which is infused at once and 

 the other only after an exposure of 24 hours to the air, the 

 first is found to be inactive, while the other is immediately and 

 energetically active, from which it is clear that the inert tryp- 

 sinogen which it contains becomes spontaneously transformed 

 into active trypsin; indeed, it suffices to pass a current of 

 oxygen through a pancreatic infusion, rich in trypsinogen and 

 poor in trypsin (an active infusion), to transform it into an 

 infusion possessing a digestive power. This transformation, 

 then, is an oxidation, trypsin being oxidized trypsinogen. 



"The fact observed by Heidenhain of the continuous for- 

 mation and storing up of trypsinogen in the pancreas and its 

 subsequent transformation into trypsin during the culmen of 

 gastric digestion proved that the former substance at any rate 

 enjoyed an origin quite independent of all influence outside 

 the pancreas itself, and the hypothesis of Schiff as to the inter- 

 vention of the spleen seemed, in consequence, to be at fault. 

 But it was only the theory of Schiff which suffered by these 

 new revelations; as far as the experimental results of the two 

 observers were concerned, physiologists were face to face with 

 two series of apparently contradictory facts apparently be- 

 cause facts properly observed can never stand in contradiction 

 with one another, and when they appear to do so it is merely 

 because the interpretation of them is either false or incom- 

 plete. It fell to the lot of M. Herzen to unravel the tangled 

 hypotheses. It appeared to him that, by modifying the hy- 



