Vines . — Proteolytic Enzymes in Plants (//). 605 
25 cc. of each of these solutions were then placed in each of 10 
stoppered bottles : the contents of 3 of these were acidified by the 
addition to each of *25 grm. of citric acid (—0*5 %), the contents of 
other 3 made alkaline by the addition to each of 0*12 grm. of 
Na 2 Co 3 (= -25%), whilst to the remaining 3 neither acid nor alkali 
was added : the contents of the last 3 were slightly acid, but they are 
distinguished below as ‘ neutral/ 
To an acid, an alkaline, and a neutral bottle, 0-5 grm. of NaF was 
added (= 1 %) : to a similar set, HCN was added to 0-2 % : to a third 
set of 3, chloroform was added to 0-5 %. 
A control bottle contained 25 cc. of boiled papai'n-solution, with 
25 cc. of Witte-peptone solution. 
After 18 hours’ digestion at 4o°C., the tryptophane-reactions were 
as follows : — 
HCN. 
Chlorof. 
NaF. 
Acid 
very strong 
marked 
distinct 
Alkaline 
distinct 
faint 
faint 
Neutral 
distinct 
faint 
faint. 
The control bottle gave a scarcely perceptible reaction. 
These results indicate to how great an extent the activity 
of papain is affected by the antiseptic employed ; and more 
especially that sodium fluoride exerts a strong inhibitory 
influence. Moreover, the advantage of an acid over an alkaline 
or a neutral medium is apparent. 
In order to more definitely establish these conclusions, the 
experiment was repeated with fibrin instead of Witte-peptone : 
each bottle contained 1 grm. of fibrin, otherwise the contents 
were the same as in the preceding experiment, except that 
the percentage of Na 2 C 0 3 in the alkaline bottles was increased 
to 0-5 °/ o . After eighteen hours’ digestion, at 40° C. 3 the 
results were : — - 
NaF. 
distinctly attacked 
faint trypt. 
scarcely attacked 
doubtful trypt. 
mostly disintegrated 
faint trypt. 
Acid 
HCN. 
J fibrin quite disintegrated 
(marked tryptophane 
( fibrin quite disintegrated 
JrL LK>CLLZfl& \ r • . . . 1 
(faint tryptophane 
( fibrin nearly all gone 
Neutral 
(distinct tryptophane 
Chlorof. 
scarcely attacked 
faint trypt. 
scarcely attacked 
doubtful trypt. 
distinctly attacked 
faint trypt. 
