Pathogenic Bacteria

SPIRILLA RESEMBLING CHOLERA. 337

turf s of the cholera spirillum. The spirillum does not
stain by Gram's method.

Spirillum Dunbar.—This organism (Fig. 92) was de~

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FIG. 92.—Spirillum Dunbar, from agar-agar; x 1000 (Itzerott and Niemann).

scribed in 1893 by Dunbar and Oergel, who secured it
from the water of the Elbe River. It much resembles
the cholera spirillum, but it never exhibits sigmoid forms*
It stains poorly, the ends taking the color much better
than the central portion.

Gelatin is liquefied by the growth of this organism
more quickly than by the cholera spirillum. The colo-
nies upon gelatin and the puncture-cultures in gelatin
are identical with those of the cholera spirillum.
. On agar-agar a luxuriant whitish-yellow layer is pro-
duced.

In bouillon and peptone solution the addition of dilute
sulphuric acid produces the red color of nitro-indol.

It is said that cultures grown at a temperature of 22° C.
phosphoresce in the dark.

The spirillum seems to be pathogenic for guinea-pigs
when introduced into the stomach according to Koch's
method for cholera.

Spirillum Danubicus,—This organism (Fig. 93) also;
22