Vines . — The Proteases of Plants. 31 1 
25 cc. of the NaCl extract were put into each of 2 bottles with the addition of some 
toluol and 0-2 grm. fibrin, the fibrin having been previously boiled in one case : 25 cc. 
of the watery extract were put, with toluol and unboiled fibrin, into each of 2 bottles, 
and to one of them 1 grm. NaCl was added. 
After 19 hours in the incubator, the unboiled fibrin in the bottle containing 
NaCl extract had disappeared ; the fibrin had not disappeared in any of the other 
three. 
This experiment demonstrates not only the superior activity of the 
NaCl extract, but also the solvent action of the NaCl (compare Yeast, 
P . 306). 
The next experiment relates to the action of acid and alkali upon 
a rapidly prepared NaCl extract. 
Experiment 10. 100 grms. fresh mushroom-pulp were extracted with 300 cc. 
of 2 % NaCl solution containing toluol, and filtered, the whole process of preparation 
occupying about an hour. 40 cc. of the extract were put into each of 5 bottles, with 
0-2 grm. of fibrin, treated thus — to No. 1, nothing further added; to No. 2, Na 2 C 0 3 
to 1 % ; to No. 3, Na 2 C 0 3 to 2 % ; to No. 4, HC1 to o-i % ; to No. 5, HC 1 to 0-2 %. 
After 24 hours in the incubator, the fibrin had disappeared in No. 1, was 
unaltered in Nos. 2 and 3, and seemed to be attacked in Nos. 4 and 5 : 24 hours 
later the fibrin had not disappeared in any one of these four bottles. 
These results, as also those of Expts. 6 and 8, show that the pepto- 
nizing activity of a mushroom-extract, of the strengths employed, is 
destroyed by the addition to the naturally acid liquid of o-i °/ o HC1, or 
of 0.5-1 % Na 2 CO s . 
So far it has been assumed that the disappearance of the fibrin in the 
experiments implied peptonization. In order that there might be certainty 
on this point, the following experiment was made : — 
Experiment 11. 60 cc. of NaCl extract (toluol 1 %) were put to digest 2 grms. 
of fibrin: in 20 hours the fibrin had disappeared, and the liquid, after boiling and 
filtering, gave a well-marked biuret-reaction. At the commencement of the experi- 
ment, a sample of the extract gave no biuret-reaction. 
The results of these experiments on fibrin are such as to lead inevitably 
tothe conclusion that the mushroom contains a peptonizing enzyme capable 
of digesting fibrin : it is therefore remarkable that Delezenne and Mouton 
(see p. 309) should have expressed the contrary opinion. The reason 
for this contradiction is that these observers used boiled fibrin in their 
experiments. This precaution, it is true, obviates a possible source of error 
by eliminating any self-digestion of the fibrin : but it is doubtful if this 
advantage compensates for the disadvantage involved, the disadvantage 
of missing altogether the presence of the peptonizing enzyme. Proteids 
coagulated by heat offer, as is well known, considerable resistance to 
the digestive action even of animal proteases ; so that it is not surprising 
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