1913-14.] Enzymatic Peptolysis in Germinating Seeds. 
123 
Agaricus campestris — Extract on 
Protein . 
Pepton Witte 
Pepton Roche 
Titrations. 
Average. 
Control. 
5-9, 6-0, 6T 
6-0 
7-3 
2-8, 2-3, 2-35 
2-5 
6-3 
Positive result- 
—marked. 
Difference. 
1-3 
3-8 
A number of experiments similar to those just described have also been 
carried out, using as material Saccharomyces cerevisice, Penicillium glaucum, 
Aspergillus niger. 
In the case of Saccharomyces cerevisice three experiments were 
carried out: — 
I. Washed and pressed yeast was extracted for twenty-four hours with 
chloroform water, and the filtered liquid allowed to act on the protein, 
Pepton Witte, and Pepton Roche as before, at 37° C., using the same concen- 
trations as in the previous experiments. Three digestions were carried 
out with each substrate, and in the case of the protein and Pepton Witte 
two controls were precipitated before digestion. 
The Pepton Roche digestions did not give any precipitate of tyrosin 
within three weeks, thus indicating the absence of this form of activity 
in the extract. The other digestions were all precipitated after twenty-four 
hours’ incubation and used for nitrogen determination in the usual manner, 
with the following results : — 
Titrations. 
Average. 
Control. 
Difference. 
Protein .... 
9-3, 9T, 9T5 
9T8 
9T0 
*08 
Pepton Witte 
7-9, 7-6, 7-8 
7*77 
8*5 
•27 
II. Washed and pressed yeast was ground with sand and kieselguhr in 
the Buchner mortar, the liquid expressed in the usual manner and freed 
from suspended particles by means of a centrifuge. Digestions similar to 
those described above were carried out, using 2 c.c. of the liquid in each 
case and adding distilled water to obtain the same concentrations of the 
substrate. 
All the Pepton Roche digestions gave a strong deposit of tyrosin within 
twenty-four hours. 
The other digestions were all precipitated after twenty-four hours’ incuba- 
