49 2 
Journal of Agricultural Research 
Vol. I, No. 6 
be considered as a possible source of bacteria in milk, among which 
would undoubtedly be found members of the lactic group. Kinyoun 
and Dieter believe that the presence in milk of cocci which form chains 
in lactose bile at 37 0 C. is presumptive evidence that the milk is con¬ 
taminated with feces. 1 It is the more common practice, however, to 
consider this type as the indication of the presence in the herd pro¬ 
ducing the milk of one or more cows with infected udders. 
The mouth is known to contain streptococci, and the habit of cows of 
licking their flanks and udders provides a more or less direct connection 
between the mouth and the milk pail. Each of these sources may be 
considered as the normal habitat of bacteria. Under these conditions 
they persist for indefinite generations, adapting themselves to their 
environment until it is reasonable to suppose the characters acquired 
become sufficiently fixed to have at least varietal significance. 
The study of streptococci originating within such circumscribed limits 
is of interest in addition to its taxonomic importance, in the light it may 
cast on the origin of some of the bacteria in milk and the significance 
from the hygienic standpoint of the presence of certain types. 
In this paper are recorded the results of a study of streptococci repre¬ 
senting three of the possible sources from which this group may find its 
way into milk. The morphology of this collection was studied with 
the hope that this would give some basis for a division into varieties. 
The ability of these cultures to utilize a number of carbohydrates and 
alcohols was determined. On the basis of these fermentations several 
groups are established, each of which is made up of a large number of 
identical cultures constituting the type about which are grouped similar 
cultures, but which varied from it in one or two reactions. The prob¬ 
able relation of one of these groups to well-known species is pointed out. 
THE CULTURES STUDIED 
A collection of streptococci were obtained from milk, from bovine 
feces, from the mouths of cows, and from the udders of cows. With the 
exception of those from milk an effort was made to make the cultures 
as representative as possible. The procedure of isolating the milk cuh 
tures followed that usually employed in the laboratories of boards of 
health. Small portions of the milk were added to lactose-bile tubes 
which were incubated at 37 0 C. Tubes showing streptococci in distinct 
chains on microscopical examination were plated on lactose agar and the 
chain-forming cocci subcultured. In this way 42 cultures were isolated 
from 25 samples of milk and cream collected at Washington or at the 
creamery at Troy, Pa. No two samples came from the same farm. A 
few cultures were obtained through the courtesy of Dr. Kinyoun and 
Mr. Dieter from lactose-bile tubes in the laboratory of the health depart¬ 
ment of the District of Columbia. These cultures, therefore, did not 
1 Kinyoun, J. J., and Dieter, I,. V. A bacteriological study of the milk supply of Washington, D. C, 
Jour. Amer. Pub. Health Assoc., v. 2, no. 4, p. 262-274. 1912. 
