J I 2 
Vines . — The Proteases of Plants ( V ). 
filtered washings was tested : 40 cc. of the liquid, which gave no tryptophane-reaction, 
were put into a bottle with 0-2 grm. of Witte-peptone ; after 24 hours’ digestion the 
liquid gave distinct tryptophane-reaction. Consequently the precipitate on the filter 
was again washed with 100 cc. 10% NaCl-solution containing 0-2% acetic acid, and 
the washings were tested : 40 cc. were put into a bottle with 0-2 grm. Witte-peptone ; 
no tryptophane-reaction was observable after 24 hours’ or after 48 hours’ digestion; 
it was therefore concluded that all the ereptase had been washed out of the 
precipitate. 
It now remained to ascertain if the precipitate contained a fibrin-digesting protease. 
2 grms. of the precipitate (which was kept in the cold all the time) were treated with 
about 70 cc. distilled water, and the mixture put to filter. Filtration soon became 
very slow ; the filtrate was turbid, and seemed to continue precipitating ; 40 cc. 
were put into a bottle with 0-5 grm. fibrin, and 30 cc. into another bottle with 
a solution of 0-2 grm. Witte-peptone in 10 cc. distilled water that had been boiled and 
filtered ; after 24 hours’ digestion the fibrin was seen to be much broken up, and in 
72 hours it had entirely disappeared: at the end of this time the liquid to which 
Witte-peptone had been added gave no trace of tryptophane-reaction, nor did the 
other. 
This last experiment was repeated with a more dilute solution : 1 grm. of the 
precipitate was treated with 50 cc. distilled water; 20 cc. of the filtrate were put into 
each of two bottles, to one of which 20 cc. distilled water and 0-5 grm. of fibrin were 
added, to the other 20 cc. of a boiled and filtered solution of 0-2 grm. of Witte- 
peptone; after 48 hours’ digestion the fibrin was disintegrated, though it had not 
altogether disappeared, in the one bottle, and the contents of the other gave no 
tryptophane-reaction. Thus a very small quantity of the washed acetic acid 
precipitate sufficed to give a solution that readily digested fibrin. 
In another experiment with the precipitate, 2 grms. were extracted with 80 cc. 
distilled water, and filtered through muslin instead of through filter-paper. The filtered 
liquid gave no precipitate on boiling, and no biuret-reaction : 35 cc. of the solution 
were put into each of two bottles, after boiling in one case ; to each 0-2 grm. fibrin was 
added. After 24 hours in the incubator the fibrin had nearly disappeared in the 
unboiled liquid, which now gave a strong biuret-reaction ; the fibrin in the boiled liquid 
was unaltered, and the liquid gave no biuret-reaction : 0-4 grm. of fibrin was now 
added to the unboiled liquid ; in 24 hours the fibrin was quite broken up, and neither 
liquid gave tryptophane-reaction, nor did the boiled liquid give a biuret-reaction. 
To return to the acid filtrate : I endeavoured to obtain from this a precipitate 
which, on being dissolved, would give a solution that would act on Witte-peptone. 
About 130 cc. of it were poured into twice the volume of strong alcohol; a precipitate 
was formed, and the liquid was filtered. 1 grm. of the precipitate was treated with 
50 cc. distilled water and filtered; the filtrate gave no tryptophane-reaction : 20 cc. of 
it were put into each of two bottles, and to one of them o-i grm. Witte-peptone was 
added. After 24 hours’ digestion the contents of the latter gave a faint tryptophane- 
reaction, which had become quite distinct after 48 hours ; the contents of the other 
bottle gave no reaction. 
In all these experiments HCN, o-i%, was the antiseptic. 
