(TT) 
decided results; it even happened sometimes that no reinforcing 
action could be detected. 
The same result was obtained, when instead of a trypsin sol. in 
Nas CO; 0.3 %, a glycerine-extract of pancreas was employed; 
sometimes an evident action, at other times none at all. Sometimes 
even it would seem as if boiled intestinal juice, in which any ferment 
should have been annihilated, operated actively, whereas the unboiled 
juice was inactive. Looking at these contradictory results, it appeared 
possible that they might be explained on the hypothesis that trypsin 
was liberated from a combination (zymogen) in which it is present 
in the pancreatic juice. | 
A communication recently made at Turin at the physiological Con- 
gress, by one of PAwLow’s collaborators, Dr. WALTHER ') lends support 
to this supposition. 
In opposition to PAwLow’s opinion, this investigator considers 
that the action of enterokinase is due to a transformation of 
zymogen, which has no influence on white of egg, into the active 
trypsin. In his dissertation, written in 1899 in the laboratory of 
Petersburgh, SCHEPOWALNIKOW °) appears to be of the same opinion. 
In this way it can be explained that there were trypsin-prepara- 
tions, which were not, and others which were rendered active by 
intestinal juice. It, however, remained to be proved that the first 
preparations still contained a considerable quantity of zymogen and 
the others none at all. 
It was therefore thought desirable to make experiments with a 
zymogen, free from trypsin. To this end a pig’s pancreas was taken, as 
soon as possible after the animal had been killed (one or two hours), 
eut into small pieces and subjected to pressure. The thick juice 
obtained in this way, did not show the least action on coagulated 
white of egg. When however intestinal juice (which in itself is 
equally unable to digest white of egg) was added to it, the coagu- 
lated white of egg rapidly disappeared. | 
Evidently therefore the intestinal juice had liberated trypsin from 
its zymogen. 
The following table gives the details of one experiment, selected 
from many others which all gave the same result. It also shows 
that the intestinal juice is rendered inactive by boiling. 
1) Wantier, Archives Italiennes de Biologie, 1901, 
*) We have been enabled to read this dissertation which is written in Russian 
through the kindly aid of Dr, SanryKow, assistant in pathological anatomy in Groningen, 
