Vines . — ■ Tryptophane in Proteolysis. y 
Bottle No. 1 contained, in addition, 50 cc. of distilled water. 
„ No. 2 „ „ 50 cc. of o*2 °/ 0 HC 1 solution. 
„ No. 3 ,, „ 50 cc. of 0-5 % citric acid solution. 
„ No. 4 ,, „ 50 cc. of 0-5 °/ o Na 2 C 0 3 solution. 
After 23 hours in the incubator, the strongest reaction was given 
by No. 3 : next in order came Nos. 1, 2, 4, the reaction in No. 4 being 
very faint. 
I had noticed in experiments with other enzymes, that the presence 
of a considerable proportion of HCN in acid digestions promoted the 
en zymotic action to a marked degree. I found this to be the case 
with papain. Comparing digestions, as above, of both Witte-peptone 
and fibrin (Nos. 2) in 0-2 °/ Q HC 1 alone, with others exactly similar 
which contained HCN to the extent of 0-2 °/ 0 in addition, the trypto- 
phane-reaction was much stronger in the latter than in the former. 
In fact the reactions in the mixtures containing 0-2 °/ 0 HCN were 
more marked than any of the others. This is not the case when 
HCN is the only acid present. 
Cradein of the Fig (Ficus Carica , L.). 
The presence of a proteolytic enzyme in the latex of this 
plant was discovered by Bouchut (5) : but its properties were 
first investigated by Hansen (6), who found that the latex 
causes the solution of fibrin, in liquid containing 0-2 °/ o HC1, 
almost as rapidly as does pepsin ; and also in a liquid con- 
taining 2 °/ 0 of Na 2 C0 3 , but much less rapidly. The possibility 
that the enzyme might have ‘ tryptic ’ action was present to 
Hansen ; for he applied the tryptophane-test to the alkaline 
digestion, and also sought for tyrosin among the products, but 
with negative results. It is not clear whether or not he 
similarly investigated the acid digestion. Subsequently the 
properties of the latex and of the juice of the fruit were 
studied by Mussi (7). He obtained from the liquid a pre- 
cipitate, on treatment with alcohol, which was insoluble in 
water but soluble in the presence of a trace of acid or alkali, 
the solution having digestive power. He gave the name 
cradina (cradei'n) to the precipitate which consisted, in part 
at any rate, of the proteolytic enzyme, and confirmed Hansen’s 
statement that it is active in alkaline and in acid (HC1) liquids, 
