164 STORRS AGRICULTURAL EXPERIMENT STATION. 
THE GENUS BACILLUS, PERITRICHIC, NON-LIQUEFYING, 
I. No acid in dextrose or other sugars. 
B. lactis nigroferous n. s. A black bacillus. This bacillus was obtained 
from milk in New York city, and is distinctly characterized by its /ue-black, 
nearly jet-black color. B. niger of Biel, and a species isolated by Gorini, pro- 
duces black colonies on gelatine, but not on agar. We have seen only one 
culture of this remarkable bacillus, which is, so far as we know, the only bac- 
terium described of a jet-black color. : 
Morphology.—A peritrichic rod. Size, .qu-1ux.gu. There are no spores, 
and the organism does not accept the Gram stain. No chains are formed. 
Gelatine colony.—A round, thin, smooth, moist colony, at first white in color, 
but later a very deep blue-black. On Atmus gelatine, black; in a pit, not acid. 
Gelatine stab,—A needle growth and a good surface growth, slightly arbores- 
cent at the top, becoming black. 
Agar streak.—A moderately thick, smooth, moist growth, which becomes 
jet-black. 
Fermentation tubes.—There is growth in the closed arm in all three sugar 
bouillons, but no acid is produced, and no gas. An indigo blue scum appears. 
Bouillon.—An abundant sediment, a turbidity, and a blue-black pellicle. 
Milk.—No change, except the formation of a thick, black scum. Later the 
milk becomes black. 
Potato.—A thick, spreading, moist, very luxuriant growth, of a deep blue- 
black color; potato discolored. 
Grows at 37° and 20°, but not well at 37°. Aerobic. 
We have several times isolated from milk bacilli that seem essentially identical 
with B. Zenkeri (Hauser). They have been found in milk from several localities 
in Connecticut. This essential agreement is indicated by the name we have 
given it. The culture as studied by us has the following characters: 
B. lactis Zenkert n, s. (Hauser). A rhizoid or proteus-like bacillus. 
Morphology.—Size, 24-34x 14. Frequently in chains. It produces no 
spores, and does not accept the Gram stain. 
Gelatine colony.—A peculiar rhizoid colony is formed, with lateral extensions 
of variable character. 
Gelatine stab.—A prominent needle growth and a lobate or polypiform surface. 
Agar streak,—A thick, luxuriant, white growth, with radiating fibres from a 
ragged edge. Its surface is dull. Sometimes viscous. ‘ 
Fermentation tubes.—No acidity, gas, nor growth in closed arm in any sugar 
bouillon. 
Bouillon.—A sediment, but no pellicle, and usually no turbidity. 
Mitk.—Unchanged, except for a slight alkalinity. Some specimens, however, 
show a slight sliminess. 
Potato.—A moderately thick, dirty white or brown growth, which is apt to be 
rough and dry, Sometimes it is yellow, and the potato is discolored. 
