1 74 
Journal of Agricultural Research 
Vol. II, No. 3 
Table II. —The constancy of the Bacterium lactis acidi and coccus groups in their action 
upon test substances —Continued 
Micrococcus 
Production of acid in broth containing— 
Sucrose. 
Glycerin. 
Salicin. 
Mannit. 
No. of 
culture. 
First 
test. 
Age of 
culture 
at 
time of 
second 
test. 
Sec¬ 
ond 
test. 
Age of 
culture 
. 
time of 
third 
test. 
Third 
test. 
First 
test. 
Sec¬ 
ond 
test. 
Third 
test. 
First 
test. 
Sec¬ 
ond 
test. 
Third 
test. 
First 
test. 
Sec¬ 
ond 
test. 
Third 
test. 
Months. 
Months 
8 
10 
O 
11 
4 _ 
22. 
-f- 
-f 
_ 
_ 
_ 
_ 
_ 
_ 
23 . -. 
4- 
+ 
x 1 
I* 
+ 
_ 
_ 
, _ 
_ 
_ 
_ 
_ 
_ 
1 
_L 
24 . 
25 . 
+ 
9 
6 
-f- 
J 3 
9 
-f 
_ 
_ _ 
+ 
_ 
_ 
_ 
_ 
_ 
26. 
6 
9 
+ 
+ 
_ 
_ 
+ 
+ 
_ 
_ 
27. 
4 
+ 
8 
+ 
+ 
_ 
_ 
+ 
_ 
_ 
In the Bacterium lactis acidi group there is a tendency for those cultures 
which have a low ability for fermentation to increase that ability when 
cultivated upon the plain agar slopes. This appears to be a change in 
the physiological properties of the cultures when grown under artificial 
conditions, for every variation which occurred in this group was an 
increased ability to attack the more difficultly fermentable substances. 
Thus, cultures 2 and 3, which at the time the first test was made fer¬ 
mented only lactose and were classified as variety “a,” in later tests 
fermented also salicin and mannit and would therefore be classified as 
variety “d.” Also, culture 5 acquired the ability to ferment mannit, 
and culture 6 acquired the ability to ferment salicin. 
The Streptococcus cultures all remained constant in their action upon 
lactose, salicin, and mannit. Cultures 9 and 10 acquired the ability to 
ferment sucrose, and culture 10 also acquired the property of fermenting 
glycerin. Culture 19 lost the power of fermenting glycerin. The Micro¬ 
coccus cultures also showed some inconstancy upon sucrose and glycerin, 
and one culture, 25, varied in its action on salicin. On the whole, the 
reactions are sufficiently constant to be considered valuable in the differ¬ 
entiation of cheese organisms. 
CLASSIFICATION OF THE BACTERIUM CASEI GROUP BY BIOCHEMICAL 
TESTS 
The study of a number of cultures of the Bacterium casei group isolated 
from Cheddar cheese showed that there is a great variation in the amount 
of acidity the different cultures are able to produce in milk. It has 
been found (Currie, 1911) also that the cultures differ in the rotatory power 
of their acids. It was evident that different strains of this group were 
present in cheese, and therefore it was desirable to classify them, in 
order to study the significance of the various strains in cheese ripening. 
Accordingly the biochemical tests which were used for the differentia¬ 
tion of the other cheese organisms were adopted also for the classification 
of this group. 
