6o8 Vines v — Proteolytic Enzymes in Plants {II). 
that HCN does not exercise any direct proteolytic action, the 
following experiment was made : — 
30 cc. of a papain solution like the above were placed in each of 
2 bottles, that in one of the bottles having been previously boiled : 
to each bottle were added 1 grm. Witte-peptone, *25 grm. citric acid, 
and 20 cc. dist. water containing HCN so that the percentage of 
HCN in the mixture was 0*2. After 18 hours’ digestion, the unboiled 
contents of the one bottle gave strong tryptophane-reaction, whilst 
the boiled contents of the other gave none. 
I then proceeded, for purposes of comparison, to make a 
similar experiment with the juice of the Pine-apple. 
50 cc. of expressed juice were placed in each of 7 bottles, with 
1 grm. of moist fibrin : in 5 of the bottles the juice was of natural 
acidity, and to each of these antiseptics were added respectively as 
follows: 0-2% HCN, 1% NaF, 0-5% thymol, 0-5 % toluol, 0-5% 
chloroform: the juice in the sixth bottle was neutralized and then 
made distinctly alkaline by the gradual addition of 1-7 grm. Na 2 Co 3 , 
when 0*2 % HCN was added : no antiseptic was added to the seventh 
bottle. 
After 24 hours’ digestion at 40° C., the results were as follows. 
The fibrin had been quite or almost completely dissolved in all the 
bottles : least in the NaF and chloroform bottles. The tryptophane- 
reactions were : — very strong in NaF, thymol, toluol, and chloroform 
bottles ; marked in the toluol bottle and in the alkaline HCN bottle ; 
less marked in the acid HCN bottle and in the bottle without anti- 
septic. 
These results are altogether contradictory to those obtained 
with papain : for in this case proteolysis was most active in 
the presence of NaF, and least active in the presence of HCN. 
It seems natural to infer that the difference in the behaviour 
of the two proteases with the two antiseptics indicates a funda- 
mental diversity in their properties. It is generally agreed 
that bromelin is a more active protease than papain, though no 
digestion-experiments have been made with equivalent weights 
of the pure substances ; and until that has been done, there is 
no real basis for comparison. There can, however, be little 
