CLASSIFICATION OF DAIRY BACTERIA. 127 
The white non-acid bacteria are very numerous and show many slight varia- 
tions. We have tried to separate them into groups, but they are all more or 
less connected by intermediate forms and our grouping is not very satisfactory. 
Bact. lactis myceloidium, A mycoloid, non spore-bearing Bacterium. We 
have studied two cultures of this type, one from this locality and one sent us 
by Weigmann, from Kiel, as Bact. mycoides. The Kiel culture is not mycoides, 
for it fails to produce spores and does not liquefy gelatine. This raises the 
question whether it may not be a cultural variety of 2. mycoides, having lost 
these two properties. As tested in our laboratory, it had the following charac- 
ters: 
Morphology.—Long filaments, the individual elements of which are .7u x 2u- 
3.5¢@. ‘The Gram stain is irregular and there are no spores. 
Gelatine colony.—A myceloid colony, 2 cm. in diameter, spreading rapidly; 
largely under the surface. 
Gelatine stab,—A needle growth and a surface growth; a layer of threads is 
seen extending horizontally, a short distance below the surface, to the sides of 
the tube. 
Agar streak.—A luxuriant, moderately thick, slightly yellowish growth. 
Fermentation tubes.—No acidity, gas, nor closed arm growth in any sugar 
bouillon. 
Louillon.—A sediment and turbidity, but no pellicle. 
Milk.—Becomes slightly acid, but does not curdle, even when heated, and 
shows no other change. 
Potato.—A scanty growth, thin, white. 
Grows better at 20° than at 37°. Aerobic. 
We have found a local variety of the above, agreeing with it in most respects, 
It is shorter, .g u%, does not show the peculiar horizontal growth in gelatine stab, 
and produces no acidity in milk. 
Bact. lactis arborescens [,n.s. An arborescent, non-acid Bacterium. 
Morphology.—Size, .ou@x 1.24-1.4m. It has no spores nor capsules, forms no 
filaments, and Gram stain is negative. 
Gelatine colony.—Round, raised, smooth, entire, white colony. On litmus 
gelatine brownish and not acid. 
Gelatine stab,—An arborescent needle growth and a surface growth. 
Agar streak.—Scanty, thin, white to cream color, slightly viscous. 
Fermentation tubes.—No acidity, gas, nor closed arm growth. 
Bouillon.—A sediment, ring-formed pellicle, and a slight turbidity. 
Milk.—Is rendered alkaline and slimy. After some days it becomes slightly 
transparent, indicating a slight digestion. ; 
Potato.—Scanty, raised, grayish-brown color; potato discolored. 
Grows at both 20° and 37°. Aerobic. 
This organism was sent us from Michigan by Marshall, but we have not our- 
selves found it. Its slight digestion of milk and its slight pit in gelatine stab 
suggest an intermediate step toward a liquefying form. If regarded as a slow 
liquefier it is not unlike Bact. arborescens Frankland, found in water. 
