Vines . — The Proteases of Plants ( V ). 107 
After 72 hours the fibrin had almost entirely disappeared in Nos. 4, 5, 6 ; the 
reactions were : — 
Tryptophane. 
Boiling. 
Biuret. 
No. 1, 
strong 
very slight ppt. 
none 
,i 2 > 
very faint 
no ppt. 
distinct 
» 3 > 
strong 
turbidity 
none 
» 4 (fibrin), 
strong 
slight ppt. 
fair 
5 >5 
very faint 
no 
distinct 
33 33 
strong 
no 
fair. 
From this it appears that fibrin-digestion was not materially interfered 
with by the addition of either acid or alkali. The effect on autolysis could 
not be gauged by the presence or absence of a precipitate on boiling, inas- 
much as the native proteids were converted into acid-albumin or alkali- 
albumin ; but it is clear that peptolysis was prevented by alkalinity, since 
the liquids containing Na 2 C 0 3 gave but faint tryptophane-reaction, whilst 
retaining the biuret-reaction which disappeared in the two other liquids 
(Nos. 1 and 3). Thus the results, so far as they go, are differential as 
between peptonization and peptolysis in the presence of alkali. 
This experiment, however, is not only of interest in this respect, but 
also in that it confirms the previous observation (Experiment 3, p. 105), 
that the biuret-reaction disappears during the autolysis of H 2 0 -extracts, and 
persists in NaCl-extracts ; this result was further established by other 
experiments on autolysis, of which the following are examples : — - 
Experiment 6. 20 grms. crushed seed were extracted with 200 cc. 2% NaCl- 
solution ; and 20 grms. with 100 cc. H 2 0 : 50 cc. of each filtered extract were placed 
separately in two bottles, to which some HCN was added : both extracts were acid, 
the H 2 0 -extract being darker in colour and less clear than the NaCl-extract ; their 
reactions were : — 
Boiling. Tryptophane . Biuret . 
NaCl-ext. dense ppt. faint good 
H 2 0 „ less „ distinct „ 
After 48 hours’ digestion the reactions were — 
NaCl-ext. slight ppt. distinct good 
H 2 0 ,, rather more ppt. marked none 
The experiment extended over six days ; at the close the reactions were— 
NaCl-ext. very little ppt. marked good 
H 2 0 „ slight „ „ none. 
In another experiment, Witte-peptone was added to the extracts with 
the object of ascertaining whether the H 2 0 -extract was capable of pepto- 
lyzing proteids in addition to those formed in autolysis. 
Experiment 7. 20 grms. of crushed seed were extracted with 200 cc. H 2 0 , and 
20 grms. with 200 cc. 2% NaCl ; the filtered extracts both gave a considerable precipitate 
