BACTERIA IN THE DAIRY. 85 
Species No. 38. 
As will be noticed from the above description, No. 38 is the 
common Lacillus subtilis, an organism which is well known and 
abundant in and around barns and dairies. It is, therefore, 
of especial interest to notice the effect of this organism upon 
the ripening of cream and the flavor of the butter. For that 
reason a larger number of experiments were performed with 
No. 38 than with most of the others, and the experiments were 
practically uniform in their results. The cream under its influ- 
ence was thickened, the amount of the thickening depending upon 
the length of ripening and the temperature. At 20° C. (68° F.) 
for 24 hours the cream was only slightly thickened as a rule, 
while, if ripened for a few hours longer, or if inoculated with a 
larger culture, the cream became quite thick, but not properly 
curdled. The reaction of the cream remained practically un- 
changed, the cream being essentially amphoteric, like normal 
fresh milk. There was noticed scarcely any change in the odor 
of the ripened cream, and it had hardly any appreciable taste. 
The peculiar flavor of fresh cream, however, had disappeared, 
and no prominent flavor or odor appeared in its place. The 
cream usually churns with considerable difficulty, and the butter 
made therefrom is poor in quality. There is no decidedly dis- 
agreeable taste unless the cream is over-ripened, but the action 
of this species seems to take away the somewhat pleasant flavor 
of the sweet cream which would ordinarily produce a delicate 
flavor of sweet cream butter. Although sweet cream butter is 
usually regarded as rather a tasteless product, it does have a 
slight and to many agreeable flavor. Aaczllus subtilis completely 
destroys this delicate flavor and leaves the butter almost abso- 
lutely tasteless. It makes butter which is much inferior to that 
of sweet cream butter, because it takes away from the butter even 
the slight taste which it would have had without the ripening. 
Bacillus subtilis is, therefore, a species that is distinctly objection- 
able in ripening cream, and if present in any considerable quan- 
tity will result in a deterioration of the flavor and the quality of 
the butter. When, however, it is present in small quantity it 
probably will have no especial influence, because it has no decided 
flavor of its own, and if other organisms are present with it to 
give a proper flavor, Bacillus subtilis will probably produce no 
objectionable results. 
