NEW YoRK AGRICULTURAL EXPERIMENT STATION. 53 
of hard cheese. It was the conclusion of Duclaux that the ripen- 
ing of cheese was due to the enzyms formed by the bacteria which 
he had isolated. Since this was the first theory concerning the 
relation of bacteria to cheese ripening which rested upon any ex- 
tended study of the germ content it was generally accepted as ap- 
plying to all forms of cheese and must still be considered as one of 
the current theories on the subject. 
Taking advantage of solid media Adametz’ in 1889 reported upon 
the bacteria of emmenthaler cheese and “ Hauskase.”’ His observa- 
tion that the larger part of the germs present decomposed sugar 
with the formation of acid laid the foundation for the theory that 
the bacteria of the acid-forming group were responsible for the 
ripening changes in cheese. 
Here, again, the inability to treat the subject upon the basis of 
species forced the classification back to that of general groups. 
The selection of acid formation as a group characteristic in this 
case was unfortnnate; as the work of Smith’ and others has shown 
that in the presence of sugar practically all bacteria form acid, 
the apparent variation in its formation being largely due to a si- 
multaneous production of other neutralizing compounds. | 
For nearly twenty years the students of this subject have been 
divided into two camps, one holding that cheese-ripening is due 
to the enzym-forming bacteria, the other that it is due to the acid- 
forming group. During this time neither camp has succeeded in 
demonstrating that its view is right or that the other is wrong. 
Von. Freudenreich? has been the leading exponent of the lactic- 
acid theory while Adametz!®? and Weigmann!! have led in the sup- 
port of the theory of bacterial enzyms. During this controversy 
the study of the flora consisted mainly in a quantitative determina- 
tion of the numbers of each of these two large groups at various 
stages in the ripening process, supplemented by studies of the phys- 
iological activity of representatives of each group. Thus von Freu- 
denreich!? showed that lactic-acid bacteria could render casein 


* Adametz, L. Bakteriologische Untersuchungen tiber den Reifungspro- . 
zess der Kase. Land. Jahrb., 18: 227-270. 1880. 
“Smith, Theo. Ueber die Bedeutung des Zuckers im Kulturmedien fiir 
Bakterien. Cent. Bakt., I Abt; 18: 1-9. 1895. 
*y. Freudenreich, Ed. Ueber die Erreger der Reifung bei dem Emmen- 
thaler Kase. Cent. Bakt., II Abt, 3: 231-235. . 1807. 
® Adametz, L. Sind Milchsaurebakterien oder Tyrothrixarten die Erreger 
von Reifurg und Aroma beim Emmenthalerkase? Milch Ztg., 29: 753-754. 
1G00. 
“Wegrann, H. Handbuch der technischen Mykologie, 2: 168. 1906. 
™ See rote 9. 
