176 
Vines . — The Proteases of Plants (///). 
employed in each case was that which I had found by previous experience 
to affect proteolysis as little as possible : in some cases the antiseptic was 
varied in different experiments for the sake of comparison. 
Carica Papaya . 
4 grms. of papain (Christy) were extracted for a couple of hours with 200 cc. 
distilled water: 4 grms. of Witte-peptone were added, and after standing for 
3 hours the liquid was decanted from the undissolved residue : the liquid was faintly 
acid : HCN to 0-2% was added as the antiseptic. 40 cc. of the liquid were put into 
each of 5 bottles with 0-2 grm. of fibrin, and treated respectively as follows: No. 1, 
nothing added ; No. 2, Na 2 C 0 3 to 0-5 % (alkaline); No. 3, Na 2 C 0 3 to 1 % ; No. 4, 
HC 1 to o*2 % ; No. 5, HC1 to 0-3 %. 
After 24 hours’ digestion in the incubator at 38° C. the fibrin had disappeared in 
all the bottles : the tryptophane-reactions were : — 
1. 2. 3. 4. 5. 
distinct distinct distinct strong strong 
Another experiment, in which half the quantity of papain was used, gave similar 
results. 
Conclusion : fibrin-digestion not materially affected by difference of reaction : 
peptolysis diminished by neutral or alkaline reaction. 
In the following experiment no Witte-peptone was added, but the quantity of 
fibrin was increased to \ grm., and the limits of alkalinity and acidity were extended : 
in all other respects the conditions were as in the preceding experiment : the bottles 
were: — No. 1, natural reaction (nearly neutral); No. 2, Na 2 C 0 3 to 1-5%; No. 3, 
HC 1 to o-2 % ; No. 4, HC 1 to 0-5 %. 
After 24 hours’ digestion the fibrin had disappeared- in all the bottles except 
No. 4, where it did not seem to have been materially reduced : the tryptophane- 
reactions were 
1. 2. 3. 4. 
distinct none marked none 
Conclusion. The results given by bottles Nos. 1-3 confirm the conclusion drawn 
from the preceding experiments: it appears that the addition of Na 2 C 0 3 to 1-5% 
inhibited peptolysis but did not materially affect fibrin-digestion. With regard to 
bottle No. 4, HC 1 to the extent of 0-5 % completely arrested both processes. 
These experiments demonstrate the differential effect of alkalinity on 
the activity of papain, diminishing or arresting peptolysis but not fibrin- 
digestion. I interpret this to mean that papain contains a fibrin-digesting 
enzyme having a wide range of action, limited in one direction by 0*5 °/ o HC1, 
and in the other by a greater amount than 1-5 °/ o Na 2 Co 3 ; as well as 
a peptolytic enzyme of narrower range, limited by 0-5 °/ o HC1 on the one 
hand and by i*5°/ o Na 2 Co 3 on the other. I may add that these experi- 
mental results agree on the whole with those previously recorded ( 5 , p. 155 ; 
