3 12 
Vines . — Proteases of Plants. 
that the protease of the mushroom should have failed to act upon them. 
This precaution is not, however, absolutely indispensable : for it is a simple 
matter to check possible self-digestion of the fibrin by control-experiments. 
Thus, in the foregoing Expt. 6, digestion of fibrin took place in Nos. i, 3, 
4, 5, 6, but not in No. 2 where the liquid (but not the fibrin) had been 
boiled : had the results given by Nos. 1, 3, 4, 5, 6 been due to self-digestion, 
then the probability is that the same result would have been given by 
No. 2, which was not the case. All the fibrin used in these experiments 
was prepared and preserved at one time and in the same manner : hence 
the fibrin may be regarded as a constant factor, all the variations being due 
to the mushroom-liquids, as affected by the various substances added 
to them. I may add that I have not succeeded in observing digestion 
of boiled fibrin, though strong mixtures and extracts were used, and the 
experiment was continued for a week. 
Peptolysis. 
There is already a certain amount of evidence that the mushroom 
contains an actively peptolytic enzyme, which is to be found in all the 
papers that I have previously cited (Nos. 11, 12, 13, 14). My main object 
in making further experiments has been not so much to establish this fact, 
as to determine the conditions that affect the activity of the protease and so 
to arrive at some conclusion as to its nature. I may say, however, that 
I have never failed to obtain from mushrooms, whether ripe or immature, 
and with great facility, a watery extract — in some cases a glycerine- 
extract — that readily peptolysed Witte-peptone, as indicated by the trypto- 
phane-reaction. It should be explained that, on account of the deep colour 
of the liquids, it was not possible to apply the tryptophane-reaction 
directly : the liquids had first to be boiled with animal charcoal and 
then filtered. 
The following experiment gives a general idea of the method employed 
and of the results obtained : — 
Experiment 1. 90 grms. of fresh mushroom-pulp were extracted for 18 hours 
with 200 cc. chloroform-water: on straining through muslin, a red, opalescent, 
acid liquid was obtained. 
40 cc. of the liquid were placed in each of 6 bottles, with 0-5 grm. Witte-peptone 
and a little toluol, the bottles being then treated as follows: added to 1, nothing 
further; to 2, 1 grm. chalk to neutralize any free acid ; to 3, Na 2 C 0 3 to 1*25 % ; to 4, 
HC 1 to 0-04 % ; to 5, HC 1 to o-i % ; to 6, HC 1 to 0-2 %. 
After 23 hours in the incubator the tryptophane-reactions were — 1, marked; 
2, marked; 3, strong; 4, marked ; 5, strong; 6, faint. 
There was thus evidence of active peptolysis having taken place within 
a distinctly alkaline and a distinctly acid range of reaction, and of its arrest 
in the presence of stronger acid. 
