i ro 
Vines . — The Proteases of Plants ( V ). 
After 48 hours’ digestion the fibrin in the NaCl-bottle had disappeared, and that in the 
H 2 0 -bottle was attacked ; the contents of the NaCl-bottle gave a faint, those of the 
H 2 0 -bottle a distinct, tryptophane-reaction. Three days later the fibrin in the H 2 0 - 
bottle had disappeared. At the close of the experiment, after 10 days’ digestion, the 
tryptophane-reactions were : — 
H 2 0 -extract with fibrin strong 
„ „ without fibrin marked 
NaCl „ with fibrin „ 
,, ,, without fibrin „ 
These experiments, incomplete as they are, show that all the oily seeds 
investigated either contained to begin with, or developed during the 
experiment, proteases that effected both peptonization and peptolysis, and 
proved themselves to be more proteolytically active than starchy seeds ; 
but they were all much less active than Hemp-seed. There is, however, 
the serious difficulty in comparing the seeds in this way, that I had no means 
of knowing how old they were : accurate comparative results can only be 
expected when the seeds compared are known to be of the same harvest. 
It is well known that old seed does not germinate so well as new, and 
probably it is not so active proteolytically ; in fact the capacity for 
germination may depend to some extent upon the presence of active 
proteases. 
The Separation of the Proteases. 
In the series of papers on the proteases of plants that I have published in 
previous volumes of this periodical (1903 to 1906), I have shown that a pepto- 
lyzing protease, an ereptase, is generally present, perhaps universally, in the 
tissues of plants. In some cases — for instance, ordinary foliage-leaves — it 
appeared that this was the only protease present, since the extract did not 
digest fibrin. In many cases, however, the extracts not only peptolyzed 
Witte-peptone, as indicated by the development of the tryptophane-reaction, 
but digested fibrin as well. The question remained — what is the nature of 
this fibrin-digesting protease ? is it a tryptase or a peptase ? In my last 
paper (April, 1906) I pointed out that though my experiments up to that 
time did not afford evidence to prove that there is no such thing as 
‘ vegetable trypsin yet they sufficed to prove that ‘ vegetable trypsin 5 is 
a mixture of proteases, and that ereptase is one of the constituents ; and 
I expressed the opinion that it seemed more probable that the fibrin- 
digesting constituent was a peptase rather than a tryptase. 
In the course of this year I have endeavoured to contribute something 
to the definite settlement of this vexed question. My idea was to obtain 
extracts which should contain only either the ereptase or the fibrin-digesting 
protease. It is, of course, quite easy to obtain an extract containing only 
ereptase ; almost any leaf, bulb, or seed, extracted quickly with a relatively 
