8 Vines . — Tryptophane in Proteolysis . 
but not in neutral : he does not appear to have investigated 
the digestive products. 
As my experiments have been carried on during the autumn 
and winter, I have not been able to do much with the latex or 
with the juice of fresh fruit. I had just time to make one 
experiment, last October, with a watery extract of the already 
withering leaves. A mixture, consisting of 50 cc. of the 
neutral extract, 1 grm. of Witte-peptone, and o-i grm. of citric 
acid, gave a good tryptophane-reaction after 20 hours’ digestion. 
In November, I experimented with the juice of some fresh 
fruit, and obtained the tryptophane-reaction by the digestion 
of fibrin : but the material was not satisfactory, and there was 
the difficulty that the Fig-juice was of a red colour to begin 
With, so that the tryptophane-reaction could not be readily 
distinguished. I therefore turned my attention to dried 
Figs, and obtained satisfactory results with a watery extract. 
The acid watery extract, digested by itself for 24 hours, 
gave no tryptophane-reaction ; whereas, when either fibrin 
or Witte-peptone was digested with it, the reaction was 
marked. 
The results that I have obtained with a watery extract of 
dried Figs do not confirm the conclusions of Hansen and of 
Mussi that cradei'n is especially active in acid liquids con- 
taining HC 1 , and in alkaline liquids containing Na 2 C 0 3 . On 
the evidence of the tryptophane-reaction, which I regard as 
indicating whether or not digestion by the enzyme has taken 
place, I find that cradei'n is most active in naturally ac id 
liquids ; less active in acid liquids containing HC 1 ; and least 
active in neutral and alkaline liquids. In some cases I 
observed that the neutralized and alkaline liquids became 
strongly acid when the digestion was prolonged to 24 hours ; 
and in such cases the tryptophane-reaction was then more or 
less strongly marked. It is possible that the results ascribed 
by Hansen and by Mussi to alkaline liquids may have been 
due to this secondary development of acid. 
The following will serve to illustrate the experiments. 
Half a pound of dried figs were extracted with 500 cc. of cold 
distilled water, the mixture allowed to filter all night in a cold room. 
