Vines . — Proteolytic Enzymes in Plants (II). 609 
doubt that the undiluted juice used in this series of experi- 
ments contained a much higher percentage of protease than did 
the extracts of papain in the previous series ; and it seemed 
possible that the diverse results might be due rather to the 
relative amount of the proteases in the solutions than to a 
difference in their properties. With this possibility in view, 
I instituted the following experiments with papain-extracts 
of different strengths, and with diluted and undiluted Pine- 
apple juice, NaF and HCN being the antiseptics employed. 
Papain. 
50 cc. of 4 % watery extract were placed in each of two bottles, 
together with 0*2 grm. citric acid and 1 grm. of moist fibrin : to one 
bottle o*5 grm. NaF (= 1%) was added, to the other 2*5 cc. of 
4 % HCN (= 0-2 %). 
Two exactly similar bottles were prepared in which, however, the 
strength of the papain-extract was 2 %. 
After 18 hours’ digestion at 40°C., the fibrin was completely dis- 
solved in both the HCN bottles ; only partially dissolved in the NaF 
bottles. The tryptophane-reaction was strong in the bottle containing 
the 4 % extract and HCN ; distinct in the bottle containing the 2 % 
extract and HCN ; faint in both the NaF bottles. 
30 hours later, the fibrin was completely dissolved, except for 
a small residue, in all the bottles. The tryptophane-reaction was 
strong in both the HCN bottles ; faint in both the NaF bottles. 
Bromelin. 
50 cc. of undiluted Pine-apple juice were placed in each of 2 
bottles with 1 grm. moist fibrin : to the one 0*5 grm. NaF 1 %) 
was added, to the other 2*5 cc. 4 % HCN (0-2 %). 
Two exactly similar bottles were prepared in which the juice had 
been diluted with an equal volume of distilled water. 
After 18 hours’ digestion, the fibrin was mainly dissolved in all the 
bottles. The tryptophane-reaction was strong in the bottle con- 
taining undiluted juice and NaF ; marked in the bottle containing 
diluted juice and NaF ; distinct in that containing undiluted juice and 
HCN ; faint in that containing diluted juice and HCN. 
30 hours later, the fibrin was dissolved in all the bottles. The 
tryptophane-reaction was very strong in the NaF bottle with undiluted 
