SPIRILLA RESEMBLING CHOLERA. 331
shape and coarsely granular. The color is yellow, and is
pale at the edges, gradually becoming intense toward the
centre. The colonies are surrounded at first by distinct
lines of circumscription, later by clear zones, which, ac-
cording to the illumination, are pale or dark. From this
description it will be seen that the colonies differ from
those of cholera in the prompt liquefaction of the gelatin,
their rapid growth, yellow color, irregular form, and dis-
tinct lines of circumscription.
In gelatin punctures the growth takes place all along
the track of the wire, and forms a cloudy liquid which
precipitates at the apex in the form of a coiled mass.
Upon the surface a delicate imperfect yellowish myco-
FIG. 88.—Spirillum Denecke : gelatin puncture-cultures aged forty-eight and
sixty hours (Shakespeare).
derma forms. Liquefaction of the entire gelatin gen-
erally requires about two weeks.
Upon agar-agar this spirillum grows as a thin yellow-
ish layer which does not seem inclined to spread widely.
The culture upon potato is luxuriant if grown in the
incubating oven. It appears as a distinct yellowish moist