Vines . — The Proteases of Plants {IV). 1 1 9 
some constituent of the reserve proteid. But the differences in the rapidity 
of action remain to be accounted for : they may be due (1) to variation in 
the amount of enzyme present in the seeds ; or (2) to differences in the 
amount of the digestible proteid stored in the seeds: or perhaps to 
a combination of these conditions. I have not attempted to go minutely 
into the matter ; but I have made an observation, based upon my earlier 
experiments with Vicia Faba, that throws some light upon it. I have 
found that 10 °/ Q mixtures of the six species of seeds investigated gave 
in every case a more or less strong tryptophane-reaction within 24 hours 
when Witte-peptone had been added to the extent of 0-5 °/ o . Un- 
doubtedly these ungerminated seeds all contained sufficient protease : 
hence the results of the autolysis-experiments indicate an absence, not of 
the enzyme, but of the particular proteids upon which the enzyme could act, 
except in the case of the Lupin, where the tryptophane-reaction was 
developed as rapidly without as with the addition of Witte-peptone. The 
slow development of the tryptophane-reaction in the other cases suggests 
a gradual conversion of less tractable reserve proteids, probably forms 
of proteoses, into others more readily digestible, probably deutero-albumoses 
and peptones. However, it is impossible to account fully for the differences 
observed in the proteolysis of these seeds without an adequate investigation 
of the nature of their reserve proteids ; and this I have not attempted. 
But I may record my impression that the differences in the constitution of 
the proteid reserves are not so much dependent upon the kind of seed — that 
is, are not altogether specific differences — as upon the degree of ripeness 
of the seed. It would appear that the more completely ripe the seed, the 
more intractable are the reserve proteids. This point, again, can only 
be settled by further investigation : by comparative experiments with seeds 
at different stages in the process of ripening. 
Having thus dealt with the autolysis of ungerminated seeds, the 
possibility of fibrin-digestion remains to be considered. The experiments 
on this question were carried on in the same way as those already described 
for germinated seeds : in every case 0-3 grm. fibrin was suspended in 
a mixture consisting of 10 grms. seed-flour and 100 c.c. distilled water, with 
01 °/ o HCN as the antiseptic. 
The results were these : in the case of Vicia Faba , Phaseolus multiflorus , 
and Phaseolus vulgaris , the fibrin showed no appreciable diminution even 
when, as in one instance, the experiment was continued for 14 days : in 
the case of Pisum sativum , Lupinus hirsutns , and Zea Mais , the fibrin 
completely disappeared in the course of several days. Thus, with Pisum , 
the fibrin showed signs of diminution on the ninth day, and had disappeared 
on the tenth : with Lupinus , in one experiment, the fibrin began to break 
up on the fourth day and disappeared on the fifth ; in another experiment, 
it disappeared on the sixth day : with the Maize, the fibrin was seen to be 
