6 Vines . — Tryptophane in Proteolysis. 
for our knowledge of its properties we are chiefly indebted to 
the researches of Martin, who experimented, not with the 
enzyme, but with the dried juice. In his first series of 
observations ( 4 ), Martin established the * tryptic ’ character of 
the enzyme by finding leucin, and traces of tyrosin among the 
products of digestion, coagulated egg-albumin being the 
proteid supplied when quantitative estimations were made : in 
the second series of observations (4 a), in which the enzyme 
digested the proteids of its own juice (globulin, albumose, 
albumin), leucin was found and the presence of tyrosin more 
definitely ascertained. He concludes that papain is active in 
neutral liquid; more active in the presence of 0*25 °/ o of 
Na 2 C 0 3 , but less active with larger amounts of the alkaline 
salt up to 1 % ; and that it acts slightly in liquid containing 
0-05 °/ o HC 1 , but not at all with a higher percentage. My own 
results tend to show that papai'n is more adapted, than Martin 
found, to an acid medium, and, more especially, that it can 
act powerfully in a liquid containing -2% of HC1: but 
Martin’s results were obtained with albumin, mine with Witte- 
peptone and fibrin. 
The following are some of the experiments upon which my con- 
clusions are based. 
Each of four bottles contained 1 grm. of Witte-peptone, and 
•5 grm. of ‘pure papain’ (Christy), which gives a neutral watery 
solution. 
Bottle No. 1 contained, in addition, 50 cc. of distilled water. 
„ No. 2 „ „ 50 cc. of o-2 °/ o HC 1 solution. 
„ No. 3 ,, „ 50 cc. of 0-5 °/ Q citric acid solution. 
„ No. 4 „ „ 50 cc. of 0-5 °/ 0 Na 2 Co 3 solution. 
To each were added 5 drops of a 4 °/ 0 solution of HCN. 
After 3 1 hours in the incubator, the only bottle which showed any 
tryptophane-reaction was No. 3, where it was weak but distinct. 
After 22 hours in the incubator, bottles 2 and 3 gave a strong 
reaction, whilst bottles 1 and 4 gave a weak reaction. 
A similar series of experiments was made with fibrin as the digestible 
proteid. 
Four bottles were taken, as before, each containing 2 grms. of 
fibrin, and -5 grm. of pure papain. 
