° aa 
alee .« 
ae my 8. 
CLASSIFICATION OF DAIRY BACTERIA. 120 
Morphology.—A bacterium (.5u-.74x 1.4m), forming short chains. It has no 
spores nor capsules and the Gram stain is negative. 
Gelatine colony.—Round, raised, smooth, entire, white or cream color. Lié¢- 
mus gelatine shows a non-acid, white, not characteristic surface colony. 
Gelatine stab.—A good needle growth and a white surface. 
Agar streak.—Luxuriant, filiform, raised, smooth, white, opaque. 
Fermentation tubes.—No acidity, gas, nor closed arm growth in any sugar 
bouillon. 
? 
Boutllon.—A sediment, ring-formed pellicle, and slight turbidity. 
Milk.—Rendered slightly alkaline, is not curdled, and shows no digestion. 
In one case milk became pasty in about three weeks. 

Potato.—Luxuriant, convex, smooth, white, potato discolored. 
Grows both at 20° and 37°. Aerobic. 
Among the numerous cultures which we have studied we can recognize two 
sub-varieties. 
Variety A.—A less vigorous organism than the one described. Size, 1.4ux 
1.24, forming rather long filaments. Bouillon sometimes shows no pellicle 
and milk is not rendered alkaline. Potato growth is rather scanty. The potato 
shows no discoloration, but the growth itself is slightiy yellowish. 
Variety B.—Stains by the Gram method; agar streak is dry and wrinkled; 
dextrose slightly acid; no discoloration of potato. 
This seems to be identical with B. /actartws of Adametz and a Bacterium 
) 
described by Burri and Dugelli, mentioned as having a ‘‘dog odor” appears 
also to be the same. 
II. Acid in Dextrose or other Sugars. 
Bact. rudensits Connelli. A red, acid Bacterium. This organism was isolated 
by Harding from cheese vats, and regarded by him as the above species. Four 
cultures were sent to us by him after he had kept them in stock for a year. Of 
these four cultures two came originally from Canada; two of them had entirely 
lost their power of producing red pigments, and two still gave a slight red color 
to milk. All were said to produce red pigment originally. The cultures which 
I received had also totally lost their flagella and motility, and in this condition 
were not distinguishable from #&. /actis acidi, except by showing a better 
growth on potato. These cultures, when studied by us, had the following 
characters. 
Morphology.—A short rod, mx 1.84; forming no chains, showing no spores, 
and staining by the Gram method (originally motile). 
Gelatine colony.—A small colony, mostly under the surface, quite dense. On 
litmus gelatine it is intensely acid. ~ 
Gelatine stab,—A needle growth, but no surface growth (originally a thin 
surface). 
Agar streak.—No visible growth, or sometimes an extremely thin transparent 
growth. 
