

CLASSIFICATION OF DAIRY BACTERIA. 167 
Morphology.—An active rod. Size, 2u-2.sux.6u. No chains nor spores, 
It accepts the Gram stain. 
Gelatine colony.—A large [6-8 mm.], spreading, white colony, with a rough, 
irregular, contoured surface, outline indented. On Atmus gelatine the colony 
is acid. 
Gelatine stab.—A needle growth and a very thin surface growth. 
Agar streak.—Thin, linear, white, rather scanty, and not characteristic. 
Fermentation tubes.—All three sugar bouillons show acidity and growth in 
the closed arm, but no gas. 
_ Boutllon.—A flocculent sediment, but no turbidity nor surface pellicle. 
Mitk.—Becomes acid but does not curdle unless heated. No other change. 
Potato.—Thin, scanty, moist, white. 
Grows both at 20° and 37°. Facultative anaerobic. 
B. aromaticus lactis Grimm, (Cent. f. Bac. u. Par. II., VIII., 584, 1902) seems 
to belong here. 
For peritrichic gas-producing acid bacilli see p. 182. 
B. disenteriae Shiga. This organism, regarded as the cause of some forms 
of dysentery and some cases of summer complaint, we insert here, although, so 
far as we know, it has not actually been found in milk. It is strorfgly suspected, 
however, that it is sometimes distributed by milk, and we have thought it well 
to include it in our list. |The characters as given below are described by Ved- 
der and Duval. 
Morphology.—A peritrichic rod, Iu-3u in length, and very slender. Some- 
times it is extremely short, almost a coccus. It produces no chains nor spores. 
It does not accept the Gram stain. 
' Gelatine colony.—Practically identical with the colony of B. coli communts. 
A thin, slightly spreading, white colony, which is acid in litmus agar. 
Gelatine stab.—There is a needle growth and a slight surface growth which 
does not spread. 
Agar streak.—A luxuriant, uneven, rather thick, cream-white growth, which 
later shows a feathery edge. 
Fermentation tubes.—All sugar bouillons are rendered acid but no gas is pro- 
duced. 
Boutllon.—A sediment and turbidity are formed, and occasionally a thin 
pellicle; later the liquid is clear. 
Milk. — At first acid, but later alkaline. “No curdling nor other change. 
Potato.—A luxuriant, rough, thick, spreading, yellowish growth. 
Grows better at 37° than at 20°. Produces indol, and is pathogenic. 
This is very similar to B. coi, but-grows less rapidly at 37°. They are not 
easy to separate from each other, special culture methods being necessary. 
B. lactis fragariae (Weig.). This culture was sent me by Weigmann, 
labeled Pseudomonas fragariae. The culture we have received is a peritrichic 
bacillus rather than a Pseudomonas, and does not produce any peculiar odor in 
