376 INTERNAL SECRETIONS OF PANCREAS AND SPLEEN. 



pothesis of Schiff as to the manner in which the spleen acts as 

 a tryptogene, a fusion of the respective facts of Schiff and 

 Heidenhain could be brought about, and that, far from being 

 antagonistic, they could be shown to be reciprocally corrobora- 

 tive. He argued thus: since the zymogen, even in splenec- 

 tomized animals, is being continuously elaborated, and there- 

 fore independently of the spleen and its periodical congestion, 

 and that it accumulates in the gland-cells during fast, but that 

 it becomes rapidly and copiously transformed into trypsin only 

 in the presence of the spleen and in direct proportion to its 

 dilation, it would seem feasible that the spleen produces, by 

 'internal secretion' during its congestion, an unknown sub- 

 stance, which, carried away by the circulating blood, trans- 

 forms the inert zymogen already deposited in the pancreas into 

 active trypsin destined to pass into the secretion of the gland, 

 and that the influence exercised upon the zymogen by this 

 product of the spleen seemed to be a condition sine qua non 

 for the transformation of the former into trypsin, at least in 

 the living pancreas, since in the dead organ or its infusion it 

 is so transformed by direct oxidation. This hypothesis of 

 Herzen would seem to be further confirmed by the fact gleaned 

 from the researches of both Schiff and Heidenhain, to wit: 

 that the holding in zymogen of the pancreas at a given moment 

 either of fast or digestion is always in inverse ratio to its hold- 

 ing in trypsin, and vice versa, while the latter is always in 

 direct proportion to the spleen dilation. 



"So far so good. But Herzen reasoned further. If the 

 spleen really produces, during its congestion, a substance which 

 brings about the transformation of the pancreatic zymogen 

 into trypsin, it would then be possible to seize upon this sub- 

 stance in the spleen itself while in its turgescent condition 

 (from 6 to 7 hours after a meal), and by at once making an 

 infusion of it and mixing a certain quantity of this splenic 

 infusion with pancreatic infusion made from the pancreas of 

 a fasting animal (very rich in zymogen and very poor in trypsin, 

 and consequently nearly inactive) there could be obtained in 

 vitro a rapid and copious formation of trypsin easily recogniz- 

 able by the amount of proteid digested in a given time. The 

 control experiment would also be very simple, consisting merely 



