210 TWENTY-FIFTH ANNIVERSARY REPORT. 
work in normal cheese which is not active in cheese made in the 
presence of chloroform. 
In those cases in which lactic acid was added to chloroformed 
milk in the process of cheese-making, the amount of soluble nitrogen 
compounds was much increased. The presence of acid favored 
enzym action. ) 
In 1897 Babcock and Russell discovered galactase in milk and, as 
the result of an extended investigation regarding its action in milk, 
they concluded that it was the chief agent of cheese-ripening. When 
our work demonstrated that galactase does not produce in cheese 
ammonia, which is a normal constituent of ripened cheese, they ex- 
amined samples of our cheese and confirmed our results as to the 
absence of ammonia. They then acknowledged, as the result of our 
experiments, that galactase could not be the chief agent of cheese- 
ripening. 
Moreover, in their study of the properties of galactase, Babcock 
and Russell found it so sensitive to the presence of acids that its 
activity was easily diminished by small amounts of acid. Our ex- 
periments demonstrated that the presence of acid increases the 
soluble products of cheese-ripening, an effect characteristic of ren- 
net but not of galactase. These experiments showed the combined, 
but not the separate effects of rennet and galactase in cheese-ripen- 
ing. 
The action of galactase and rennet-enzym has been studied also 
from a quite different point. The amounts of carbon dioxide given 
off by a normal cheese and a chloroformed cheese were measured 
for a period of thirty-two weeks. (Bulletin No. 231.) In addition, 
certain compounds were determined in the cheese at the end of the 
investigation. The results are summarized as follows: 
In Normal Cheese. In Cheese Containing Chloro- 
form. 
(1) Production of carbon diox- (1) Production of carbon diox- 
ide. ide. 
(a) Total in 32 weeks, (a) Total, 0.205 gram. 
15.099 grams. | 
(b) Weekly variation from (b) Ceased entirely after 
0.735 gram in first, three weeks. 
to 0.224 gram in last, 
week. 
