Vines. — Tryptophane in Proteolysis. 5 
for action in an acid medium ; nor is this surprising in view 
of the fact that, according to Chittenden, the natural acidity 
of Pine-Apple juice is equal, on the average, to about 0*5 °/ o 
HC 1 . The divergence between Chittenden’s results and my 
own is probably due to his having used albumin, and I fibrin 
and Witte-peptone, as the digestible proteids ; he himself 
found the acid juice to digest fibrin more rapidly than did 
the neutralized. I did not find that the addition of HC1, up 
to o-2 °/ o , to the already acid juice had any marked effect 
upon the tryptophane-reaction as compared with juice of 
natural acidity. On the other hand, I found neutralized juice 
to be distinctly less active than the natural acid juice ; and 
further, that alkalinity, though it did not altogether inhibit, 
very much diminished the activity of the enzyme. 
The following example illustrates the general method and results 
of the experiments. 
The expressed juice is strongly acid, and gives a weak tryptophane- 
reaction. The amount of liquid in each of the bottles was 50 cc. ; 
the duration of the digestion was 4 hours. 
A. Natural acidity : 
(1) no proteid added (auto-digestion) ; faint tryptophane-reaction. 
(2) 1 grm. fibrin added: marked reaction. 
(3) 1 grm. Witte-peptone added : strong reaction. 
B. Neutralized juice : 
(4) 1 grm. fibrin added : distinct reaction, 
(5) 1 grm. Witte-peptone added : marked reaction. 
C. HC 1 added to 0.2%: 
(6) 1 grm. fibrin added : marked reaction. 
(7) 1 grm. Witte-peptone added : strong reaction. 
D. Alkaline (0-5 °/ Q Na 2 C 0 3 ) : 
(8) 1 grm. fibrin added: faint reaction. 
(9) 1 grm. Witte-peptone added : weak reaction. 
Next morning, after nearly 24 hours’ digestion, Nos. 4, g, 8, and 9 
were distinctly acid, and gave more or less strong tryptophane-reaction. 
I obtained this result also in other experiments, in which HCN was 
used as an antiseptic. 
Papain. 
This is the enzyme of the Papaw ( Carica Papaya , L.), and 
is obtained from the latex and more especially from the fruit : 
