2l8 
Vines .— The Proteases of Plants ( VII ). 
Experiment i. A i-g % solution in water forms an opalescent liquid which is 
distinctly acid, gives no precipitate on boiling or on adding HN 0 3 , and no biuret nor 
tryptophane reaction; but its xanthoproteic reaction is distinct. Only a very small 
quantity, therefore, of protein is present. 
30 c.c. of the solution were put into each of two bottles: to the one was added 
o*2 grm. fibrin, to the other 0-2 grm. Witte-peptone ; to each a few drops of HCN. 
After 24 hours in the incubator at 37°C., the fibrin had disappeared, and the 
liquid gave a marked tryptophane-reaction : the liquid in the other bottle gave a very 
strong tryptophane-reaction ; the liquid in both bottles was now strongly acid. 
These results indicate great proteolytic activity, both peptonizing and 
peptolyzing. The next experiment was made to ascertain in what way 
digestion was affected by the reaction of the medium. 
Experiment 2. 40 c.c. of 1*5% solution were put into each of 5 bottles: to 
each bottle were added 0*2 grm. of fibrin and 0*2 grm. of Witte-peptone, and some 
HCN. To No. 1 nothing further was added; to No. 2, HC 1 to o-i % ; to No. 3, 
HC 1 to o-2 % ; to No. 4, citric acid to 0-5 %; to No. 5, Na 2 C 0 3 to 0-5 %. 
After 19 hours in the incubator, the fibrin had disappeared in all the bottles; the 
tryptophane-reactions were—in Nos. 1 and 5, marked; in Nos. 2, 3, 4, strong. 
Hence it appears that the amounts of acid and of alkali added had not 
materially affected fibrin-digestion, whereas the added acid had distinctly 
promoted the digestion of Witte-peptone. 
In view of the activity of the proteases, a more dilute solution was used 
in the next experiment (1 %), and the process of digestion was closely 
watched. 
Experiment 3. 40 c.c. of a 1 % solution were put into each of 2 bottles: to each 
were added 0-2 grm. of fibrin and 0-2 grm. of Witte-peptone, and some HCN; to 
the one was added HC 1 to 0-2 %, to the other Na 2 C 0 3 to 1 %. 
The fibrin disappeared in the acid bottle in 3 hours, in the alkaline bottle in 
4-| hours ; both liquids then gave marked tryptophane-reaction. 
Experiment 4. This experiment was similar to the foregoing, except that 
a 0-5 % solution was used. 
The fibrin disappeared in 2 \ hours in the acid bottle, and in 3^ hours in the 
alkaline bottle : the tryptophane-reaction was distinct in the former, faint in the latter : 
19 hours later, the tryptophane-reaction was strong in the acid bottle, distinct in the 
alkaline. 
These experiments show that both fibrin-digestion and peptolysis 
are more rapid in an acid than in an alkaline medium ; and further, that 
peptolysis proceeds more slowly than fibrin-digestion. 
I may quote yet one more experiment illustrating the relation between 
peptolysis and the reaction of the liquid. 
