7 
a 
| 
1905] DEAN—PROTEOLYTIC ENZYMES 335 
days longer and the tests repeated. This time the unboiled digestion 
required 0.5°° of acid; the boiled digestion required 0.5°°. 
This experiment was repeated, using different conditions of 
reaction to make sure that such conditions played no part in the 
results previously obtained. Fifty grams of cotyledons from seven- 
day etiolated bean seedlings were comminuted and an extract pre- 
pared as before. This was divided between five flasks as follows: 
No. 1— 50°¢ extract. 
No. 2— 50°¢ extract—boiled. 
aaa. eee 
No. 3—50°¢ extract +o. 14®™ citric acid (= ms acid). 
N 
No. 4— 50° extract +o. 1068™ Na,CO, (= jee 
No. 5— 50° extract + 28™ Witte peptone. 
Toluol was added in equal amount to all the flasks. The quantitative 
estimations were made in the same manner as in the last experiment 
except that 10° of each filtrate were used for an analysis instead of 
5°. In place of a boiled control for no. 5, a determination was 
made at the start of the experiment, when it appeared that 1.4°° of 
standard acid were required to neutralize the ammonia formed from 
the nitrogen compounds in 10° of the filtrate from the tannic acid 
Precipitate. After three days’ digestion quantitative determinations 
were made on all. 
No. I—required 1 .3°¢ of standard acid. 
No. 2—required 1.0°¢ of standard acid. 
No. 3—Tequired 1.5°¢ of standard acid. 
o. 4— 
No. oe analyses lost by breaking of the apparatus. 
| Three days later the tests were repeated. 
0. I—required 1. 4°¢ standard acid. 
No. 5—required 6.5°° standard acid. 
The digestion fluid of no. 5 at the close of the experiment gave a 
Strong tryptophan reaction. The variations among the digestions, 
xcept no. 5, are within o. 3°° of standard acid; in such a method 
