Vines . — Tryptophane in Proteolysis , . 21 
form of a provisional arrangement of the enzymes from this 
point of view, based upon the tryptophane-reaction, 
I. Active in Acid liquid : 
1 . active only in acid liquid : 
(a) most active with HC1: Pepsin. 
(b) active with HC1 or natural acid : Nepenthin. 
2 . more active in acid than in neutral or alkaline liquid : 
( a ) equally active with HC1 or natural acid : Bromelin : Coco. 
(b) more active with natural or organic acid : Papain ; Cradein : 
c Peptase’ of Barley. 
II. Active in Neutral or Acid liquid : 
enzyme of Yeast. 
III. Active in Neutral or Alkaline liquid : 
(a) active in either : enzyme of Bean (?) : putrefactive Bacteria. 
(b) more active in alkaline : Trypsin. 
In conclusion, I would add a few words regarding the 
observation that hydrocyanic acid promotes proteolysis in 
certain cases. I regard this as a matter of some importance, 
as it may, if followed up, throw light upon the physiological 
significance of this acid in plants. Its general occurrence in 
certain families has long been known ; and it was assumed, by 
a too facile oecology, that its importance lay in the protection 
which it was assumed to afford, by reason of its poisonous 
properties, against the depredations of animals. It is only 
recently that the matter has been seriously investigated. As 
the result of experiments, extending over several years, made 
upon Pangium edule , Reinw., a tropical tree which contains it 
in all its parts, Treub (23) has come to the conclusion that 
hydrocyanic acid is an early product in the nitrogenous ana- 
bolism of the plant. The presence of the acid in many ger- 
minating seeds, such as the Almond, the Peach, &c., is quite 
consistent with this view, for it may serve as nitrogenous 
plastic material for the growing embryo. At the same time: 
the observations that I have made suggest that the acid may 
also be of importance in facilitating the proteolysis of the 
reserve-materials of the seed, a suggestion which I propose to 
test experimentally. 
