~ 
JERS aa 
in. 
CLASSIFICATION OF DAIRY BACTERIA. 10g 
Gelatine colony.—A distinctly round, thin, yellow surface colony, which be- 
comes about I mm. in size. Not characteristic. 
Gelatine stab.—A good needle growth and a moderately luxuriant surface 
growth, of a yellow color. 
Agar streak.—A luxuriant, yellow growth. 
‘Lermentation tubes.—There is no production of acid or gas in any sugar 
bouillon, and no growth in closed arm. 
Bouilion.—An abundant sediment and turbidity, and a thin pellicle on the 
surface. | | 
Milk.—At both 20° and 37° the milk is rendered acid, but it is not curdled 
or otherwise affected. The acidity is very slight. 
Potato.—An abundant, canary-yellow growth, and the potato is discolored. 
Grows well at both 20° and 37°. Aerobic. 
M. lactis flavus n.s. An orange, non-acid Micrococcus. 
Morphology.—A micrococcus, Size, .5¢-.8u. Stains by the Gram method. 
Gelatine colony.—A round, smooth, thick, homogeneous, orange-colored 
surface colony. 
Gelatine stab.—A good needle and surface growth, with an orange color. 
Agar streak.—Luxuriant, moist, smooth, of an orange to a red-brown color. 
Fermentation tubes.—No acidity or gas in any sugar bouillon. Dextrose and 
lactose may be rendered alkaline. No growth in the closed arm. 
Bouilion.—A sediment, a turbidity, and a pellicle; or the turbidity and pellicle 
may be wanting, the latter characteristic belonging to a second culture isolated 
at a different time. 
Milk.—\s rendered acid both at 20° and 37°, but no other change is pro- 
duced, except a slight yellow color in some cases. 
Potato.—Moderate to luxuriant, moist, smooth, red-brown to orange. 
Grows at 20° and 37°. Aerobic. 
We have found this organism several times. The different cultures differ, 
however, in small points. The chief lines of difference were the following: In 
color it ranges from orange to bright yellow. In two cultures the gelatine 
colony was white rather than yellow, and in these same two cultures milk was 
not rendered acid. One culture curled milk, acid. One culture grew in the 
closed arm of the fermentation tube, while the others did not. Weare not in- 
clined to think these differences sufficient to separate them as varieties. 
Apparently this is identical with J/zcrococcus D. of Barthel, and perhaps 
with 7. aurantiacus Cohn. 
M. lactis viscosus Cn. s. A slimy milk Micrococcus. This culture was 
sent us by Harrison and was isolated by him from Pasteurized milk. We have 
not found it ourselves. Its failure to make milk acid and its dark colored 
growth on potato seem to distinguish it from any other slimy milk micrococci. 
Hence we call it variety B. (See p. 114). The characters are as follows: 
Morphology.—A micrococcus. Size, .8u-.94%. Gram stain positive. 
Gelatine colony.—A thick, round, smooth, white colony. In old cultures the 
gelatine is turned green. On “tmus gelatine the colony is coarse, granular and 
nucleated. The surface growth is rather transparent. Below the surface it is 
opaque and brownish. 
