CLASSIFICATION OF DAIRY BACTERIA. 139 
Milk.—l\s rendered alkaline, curdled and digested completely, with a promi- 
nent odor. 
Potato.—Spreading, thin or raised, smooth, opaque, cream colored, luxuriant; 
discolored. 
Grows at 20° and 37°. Facultative anaerobic. 
Bact, lactis erythrogenes Grotenfeld. Bacterium with pink fluorescence. We 
have several times found bacteria that belong probably to this well known type. 
None of them produce much red color in milk, although some render it of a 
_ pinkish color, and one turned it deep red after several weeks’ growth. All of 
them, except variety D, produce a peculiar pinkish fluorescence in agar. We 
give below the characters of one of the cultures isolated, with the others as 
varieties. 
Morphology.—Size, 1.2ux.gu-Iu. Not forming chains. It forms no spores, 
stains by the Gram method and shows a capsule. 
Gelatine colony.—Round, raised, smooth, homogeneous, entire, translucent, 
yellowish, shining, later liquefying. 
Gelatine stab.—Begins to liquefy in three days, stratiform. 
Agar streak.—F¥iliform, raised, smooth, translucent, flesh color or pink, 
shining, luxuriant. The agar shows a pink fluorescence. 
Fermentation tubes.—Dextrose and saccharose show growth in closed arm, 
but not lactose. No acidity nor gas produced in any sugar bouillon. 
Bouillon.—A flocculent sediment, a membranous pellicle, and a decided tur- 
bidity. 
Milk. 
to digest. The digestion is nearly complete in three weeks and the liquid is of 
a pinkish color, with a slight odor. 

No change in reaction. The milk may curdle in ten days and begin 
Potato.—A luxuriant growth, white, with discolored potato. There is no 
pink color shown. 
Grows both at 20° and 37°. Facultative anaerobic. 
This organism was from a yellow slime on the surface of cheese. 
Variety A.—Differs from the above in showing no closed arm growth, a 
yellowish growth on agar, no curd or digestion in milk, and a scanty growth on 
potato. 
Variety B.—Shows yellow growth on agar. No pellicle on bouillon. Milk 
becomes alkaline and digests into a red liquid, which later becomes very red. 
Growth on potato scanty. 
Variety C.—Size, .3ux .5u-.64. No pellicle on bouillon. Milk digests; 
pinkish. Potato scanty. Growth on agar not yellow. 
Variety D.—This fails to produce a pink fluorescence, but has a yellow 
growth and is wrinkled. The milk is rendered pink, and the growth on the 
potato is yellow and scanty. This variety is, perhaps, Bact. erythrogenes of 
Dyar (Trans. N. Y. Acad, of Sci., 1895). Probably the same as Bact. luteum 
of Zimmermann. (See p. 142.) 
