Vines . — The Proteases of Plants ( VI ). 15 
would be purely peptonizing (i.e. containing peptase only), the other 
purely peptolysing (i. e. containing ereptase only). 
Some further indirect evidence in favour of the new view was obtained 
by a series of experiments that I made with certain, chiefly starchy, seeds 
(. Phaseolus multiflorus and vulgaris , Vicia Faba , Lupinus hirsntus , Pisum 
sativum , and Zea Mais ). In discussing these experiments, I stated the 
position of the question as follows (20, April 1906) : ‘ It must be admitted, 
however, that all the evidence that I have accumulated does not yet suffice 
to prove that there is no such thing as “vegetable trypsin One point, at 
any rate, has become clear, namely, that “ vegetable trypsin ” is a mixture 
of enzymes, and that ereptase is one of the constituents. But the nature 
of the other constituent (or constituents), the fibrin-digesting protease, 
remains uncertain : it may be a tryptase, but it may also be a peptase. 
It is not, I think, going too far to suggest that the known facts make the 
latter suggestion the more probable — to transfer, in fact, the onus probandi 
to those who hold that the enzyme in question is a tryptase.’ 
Pursuing my researches on seeds, I next turned my attention to oily 
seeds, and found them to be much more proteolytically active than starchy 
seeds, even when ungerminated. Most of the experiments were made with 
ungerminated Hemp-seed ( Cannabis sativd) ; but several others, such as 
those of the Mustard ( Sinapis alba), the Hazel ( Corylus avellana :), the 
Castor-oil plant ( Ricinus communis ), and the Flax ( Linum usitatissimum) 
were also examined. 
In the course of my investigation of the Hemp-seed, I made an 
attempt, which eventually proved successful, to prepare solutions con- 
taining respectively the peptase and the ereptase which my experiments 
had shown to be present in the seed. It is unnecessary to repeat here the 
description of the process employed, which is fully given in the paper in 
which the account of the experiments was published (21, Jan. 1908). The 
really important result was the preparation, from the Hemp-seed, of a 
solution containing only a fibrin-digesting enzyme (peptase). I had 
frequently prepared extracts of various kinds of material which contained 
only ereptase ; but never before had I, or indeed any one else, prepared from 
a part of a plant a solution of a peptase unmixed with ereptase. 
This result seems to me to involve the final demolition of the 
‘ vegetable trypsin ’ theory. But of course it requires reinforcing by 
similar results obtained with other material. This reinforcement is, to 
some extent, afforded by the results obtained with papain and with Yeast, 
described in the earlier part of this paper. It is, however, necessary that 
I should repeat most of the experiments that I have described in this series 
of papers, from the fresh stand-point and with the application of the new 
methods, so as to complete the confirmation of this view as to the nature of 
the proteases, and perhaps to come upon further developments of it. 
