2 I 6 
Vines.—The Proteases of Plants {VII). 
No. 3, o-2 grm. Witle-peptone and HC 1 to 0-12 % ; to No. 4, 0-2 grm. Witte-peptone 
and Na 2 C 0 3 to about o-6 %. 
After 24 hours' digestion in the incubator, the tryptophane-reactions were found 
to be—in No. 1, faint ; No. 2, marked; No. 3, very strong; No. 4, faint. 48 hours 
later, the only changes were that the reaction had become strong in No. 2 and distinct 
in No. 4. 
The following are the results of an experiment without added protein, 
that is, of an autolysis-experiment:— 
Experiment 5. A 5 % watery solution was prepared: the filtered liquid was 
slightly acid, and gave a good biuret-reaction, but no tryptophane-reaction. 
40 c.c. were put into each of 3 bottles : to No. 1 nothing was added; to No. 2, 
HC 1 to 0-15 % ; to No. 3, Na 2 C 0 3 to 0-625 %• 
After 20 hours in the incubator, the tryptophane-reactions were—in No. 1, 
faint; in No. 2, marked; in No. 3, none: after 45 hours they were—in Nos. 1 and 
2, strong; in No. 3, none: at this time No. 3 still gave a distinct biuret-reaction, 
whilst Nos. 1 and 2 did not. 
The results of all these experiments agree in proving that acidity 
promotes, whilst alkalinity retards or arrests, the digestive action of the 
proteases. 
So far it has been assumed, on the strength of the previous experi¬ 
ments with malt, that there are two proteases, a peptase and an ereptase 
in the diastase-preparation. It remains now to adduce some evidence 
to justify this assumption. 
With this object in view, attempts were made to isolate the proteases 
by means of alcohol ; three grms. of diastase were extracted, in different 
experiments, with 100 c.c. of 40, 50, and 60% alcohol; the alcoholic ex¬ 
tracts were evaporated to half their bulk, to get rid of most of the alcohol, 
and then made up with distilled water to their original volume. Digestion- 
experiments showed that in no case had the extract any action on fibrin, 
but that it acted in some cases on Witte-peptone, as shown by the trypto¬ 
phane-reactions. 
40 % alcohol extract gave marked reaction in 24 hours, strong in 
48 hours. 
50 % „ „ „ faint „ „ and in 48 
hours. 
60 % „ „ ,, no reaction in 48 hours. 
Hence it appears that the peptolytic enzyme (ereptase) can be extracted, 
without the peptonizing enzyme (peptase), by means of 40 % alcohol. 
Having determined this point, I proceeded now to ascertain what 
effect extraction with alcohol had had upon the diastase. The residues 
after extraction with alcohol of 40, 50, and 60 % respectively, were extracted 
with distilled water, and the action of these watery extracts upon fibrin and 
