June is, 1914 
Flavor of Cheddar Cheese 
171 
ber of such cultures showed that the litmus paper will detect increases 
of acidity as low as 0.5 per cent; these were recorded as positive. Hence, 
in the comparatively few instances in which the development of acid is 
slight the results may sometimes be recorded as positive in this study, 
where other investigators would have recorded them as negative. 
The amount of acid produced is regarded as unimportant in the classi¬ 
fication of the cheese organisms. The consideration of degrees of acidity 
ViTould greatly complicate a system which, if it is to be valuable in the 
study of the cheese problem, should rather be made as simple as possible. 
CLASSIFICATION OF THE BACTERIUM LACTIS ACIDI AND COCCUS 
GROUPS 
In the present study an especial effort has been made to differentiate 
the Bacterium lactis acidi and coccus groups. Since they were submitted 
to the same tests, the classification of these groups will be considered 
together. The organic substances which were adopted as the most useful 
test substances for the coccus and B . lactis acidi groups are lactose, sali- 
cin, mannit, sucrose, and glycerin. The morphology, the growth on 
plain agar slopes, and the growth in litmus milk were also considered. 
Cultures in which some or all of the cells are elongated and in pairs 
and which curdle litmus milk with the reduction of the litmus charac¬ 
teristic for Bacterium lactis acidi were classed in that group. The Strepto¬ 
coccus group includes all cultures in which the cells are spherical and 
arranged in pairs or in chains. The cultures of this group do not give the 
reduction of litmus which is characteristic for the B. lactis acidi group. 
Most of the cultures of the Micrococcus group produce a heavy growth 
upon the agar slope, which is often of some shade of yellow. They are the 
members of the Coccaceae which divide in two planes; consequently the 
cells appear in pairs, fours, or bunches. 
In Table I the sign ± indicates that individual cultures of the given 
variety may produce acid from the substance in question; or they may 
fail to produce acid. The test substances are arranged in the table 
according to their order of availability. For example, lactose is fer¬ 
mented by the greatest number of cultures, and mannit is fermented by 
the least number of cultures of both groups of the Coccaceae. 
Table I .—Classification of the groups of cheese organisms 
Bacterium: Lactis Acidi 
Production of acidity in broth containing- 
Variety No. 
Lactose. 
Salicin. 
a. , . 
b. .. 
c. . . 
d. .. 
Mannit. 
Sucrose. J Glycerin. 
