308 Vines . — The Proteases of Plants. 
shows that the two processes do not exactly agree in the latter respect : 
it appears that the range of reaction is rather more limited for peptoniza- 
tion than for peptolysis. Thus, with regard to the action of added acid, 
the only case in which digestion of fibrin took place in the presence of 
as much as 0*5 °/ o HC 1 was one in which the mixture or extract was very 
strong (20% see p. 302) ; on the other hand, 0-5 °/ o HC 1 did not inhibit 
peptolysis in a 5 °/ o yeast-mixture (p. 29 6) or in 5 °/ o yeast-extract (p. 299). 
Similarly, with regard to the action of added alkali, whilst it is true that in 
the experiments in which solid yeast was used, peptonization and peptolysis 
were equally affected by the addition of Na 2 C 0 3 to 2 °/ o (compare 
Expt. 2, p. 302, with Expt. 4, p. 296), there was a marked difference 
in favour of peptolysis when extracts were employed (compare Expt. 2, 
p. 303, and Expt. 2, p. 304, with Expts. 2, p. 299, and 4, p. 300). In the 
two former digestion of fibrin by io°/ o or 20 °/ o extracts was inhibited, whilst 
in the two latter peptolysis was effected by 5 °/ o extracts treated with 
the same amount of alkali. In Expt. 3, p. 305, digestion of fibrin was 
inhibited by 1 °/ o Na 2 C 0 3 . 
Conclusions . The chief results of the investigation are these : — • 
(1) dilute yeast-mixtures or aqueous extracts rapidly effect peptolysis, 
as indicated by the tryptophane reaction, but do not digest fibrin ; 
(2) dilute NaCl extracts of yeast readily digest fibrin ; 
(3) peptolysis and peptonization are influenced in the same manner, 
but not in the same degree, by the addition of acid or alkali. 
I infer that these two digestive processes are not effected by one and 
the same protease. On the contrary, the facts indicate the presence of two 
proteases : the one exclusively peptolytic, readily soluble in water ; the 
other peptonizing, less soluble in water, but readily soluble in 2°/ o NaCl 
solution. 
The Mushroom. 
Agaricus (Psalliotd) campestris. 
The discovery of proteases in Basidiomycetous Fungi seems to have 
been made by Hjort (11), who found that watery extracts of them digested 
fibrin. In the case of Agaricus (. Pleurotus ) ostreatus , digestion was most 
active when the liquid was neutral ; less active when acidified with 0-5 °/ o 
oxalic acid, and was altogether inhibited by alkalinity. The fibrin entirely 
disappeared in 40 hours ; the digested liquid then giving no biuret, but 
strong tryptophane-reaction, and containing leucin and tyrosin. In the case 
of Polyporus sulfur eus, the naturally acid extract readily digested fibrin, 
as did also extracts acidified with HC1 to 0*2 °/ 0 or with oxalic acid to 
0-25 °/ Q ; but neutralized or alkaline extracts did not digest at all. In 
a 12-hours’ digestion the liquid contained albumoses and peptones, but 
no amido-acids or hexon-bases. 
