Vines. — T he Proteolytic Enzyme of Nepenthes. 581 
there is no precipitate of copper hydrate, nor is there any 
biuret-reaction. I am inclined to infer that this substance 
is one of the ultimate products of digestion, as also to con- 
clude that it may be leucin or some allied body : but I have 
failed to find the characteristic scales of leucin in sufficient 
quantity. I propose to continue investigation in this direction. 
I may add that I have tried the action of the pitcher-liquid 
upon the gluten of wheat, which it readily digests, and that 
I have found the products of digestion to be essentially 
the same as those obtained by the digestion of fibrin. 
Conclusion. 
The fact that the pitcher-liquid digests fibrin in the presence 
of i 0 / o hydrocyanic acid, together with the fact that it is 
possible to prepare active glycerin-extracts from the pitcher- 
tissue, seems to me to conclusively prove that the proteolytic 
digestion is due to an enzyme and not to a Bacterium. 
I would go so far as to urge that the onus probandi is now 
transferred to those who maintain that the process is one of 
bacterial action. Before this view can be accepted, it is 
incumbent upon those who support it to produce an organism 
which will digest fibrin in the presence of i°/ o of hydrocyanic 
acid, and which will retain its digestive activity when kept 
for several weeks in pure glycerin. Until this is done there 
can be no valid argument against the enzyme-theory. 
With regard to the nature of the enzyme, whilst it is clearly 
allied to the peptic group inasmuch as it is only active in an 
acid medium, it is apparently tryptic in its action, like all the 
other better known proteolytic enzymes of plants, with no one 
of which it can, however, be identified. So far as I am aware, 
the following are the only cases in which the products of 
proteolytic vegetable enzymes have been determined with 
any accuracy. Von Gorup-Besanez states that the peptic 
enzyme which he extracted from Vetch-seeds 1 dissolved fibrin 
with the formation of peptone, and he makes the same state- 
1 Von Gorup-Besanez, Sitzber. d. phys.-med. Soc. zu Erlangen, 1874; ibid. 1875. 
