Mar. 25, 1914 
Streptococci in Milk 
509 
more cows were rendered useless. There was no apparent connection 
between the two epidemics except that they occurred at about the 
same time. We may assume that these epidemics originated in one 
of two ways, either of which must admit more or less variation in phys¬ 
iological reactions from the original type. It may be possible that the 
udders of one or more cows may have become infected by some of the 
streptococci coming originally from the mouth, intestines, or other 
sources. Under the influence of its new environment this organism may 
have acquired pathogenic properties sufficient to produce the symptoms 
observed in mammitis. Heinemann has shown that pathogenicity is a 
property readily acquired when ordinary streptococci are grown in ani¬ 
mals. 1 If these infecting organisms came from the mouth, the intes¬ 
tines, or the milk they must have acquired in a comparatively short time 
an-entirely new set of biochemical reactions in addition to a variation 
in pathogenicity. On the other hand, we may assume with much more 
appearance of reasonableness that the infection spread from a single 
infecting cell or aggregate of similar cells which already possessed patho¬ 
genic powers and general characters identical with those we have found 
to be characteristic of the udder organisms. This assumption is in accord 
with the established fact that streptococci from pathological lesions in 
general have similar biochemical reactions. If the infection in these two 
cases came from various sources, it must follow that growth under 
similar conditions would produce uniform fermentation reactions in a 
short time, a view held by Walker, who maintains that these reactions 
may be varied almost at will and can only indicate the latest habitat of 
the culture. 2 If the infection came from a single cell, there must have 
been some variation, since the fermentation reactions were not identical 
at the time of this isolation. 
In Table X are shown the varieties of nonliquefying udder cultures and 
the number occurring in each of the two herds. There were seven varie¬ 
ties in all. The most numerous one ferments dextrose, saccharose, and 
lactose only and occurred 24 times, equally divided between the two 
herds. The next most numerous variation differed from the first in 
failing to ferment saccharose and occurred 8 times. A third variation 
fermented mannite in addition to dextrose, saccharose, and lactose and 
occurred 4 times. The remaining four varieties evidently occur only 
once or twice in every 40 cultures. Viewed from any standpoint it is 
evident that these organisms are subject to variation from the type, but. 
these variations are not of sufficient magnitude or frequency to detract 
from the value of the physiological reactions as a means of establishing 
true species. 
1 Heinemann, P. G., The pathogenicity of Streptococcus lacticus. Jour. Infect. Diseases, v. 4. no. 1, 
p. 87-92. 1907. 
* Walker. E. W. A. f On variation and adaptation in bacteria, illustrated by observations upon strepto* * 
cocci, with special reference to the value of fermentation tests as applied to these organisms. Proc. Roy. 
Soc. [London], s. B, v. 83, no. 567, P. 541-558. 1911. 
