SPIRILLA RESEMBLING CHOLERA.	333
It forms long spirals in appropriate media, and is actively
motile. Each spirillum is provided with a terminal flagel-
lum. No spores have been positively demonstrated.
The organism, like the cholera vibrio, is very suscep-
tible to the influence of acids, high temperatures, and
drying, so that spores are probably not formed. It grows
well both at the temperature of the room and at that of
incubation.
The thermal death-point is 50° C., continued for five
minutes.
The bacterium stains easily, the ends more deeply than
the center. It is not stained by Gram's method.
Upon gelatin plates a remarkable similarity to the

fig. 90.—Spirillum Metschnikoff; puncture-culture in gelatin forty-eight hours
ol/^   fTTrHnlrPi *v\<\  PfViffcrV
old (Frankel and PfeifTer).
colonies of the cholera spirillum is developed, yet there
is a difference, and Pfeiffer points out that "it is com-
paratively easy to differentiate between a plate of pure
cholera spirillum and a plate of pure Spirillum Metch-
nikoff, yet it is almost impossible to pick out a few
colonies of the latter if mixed upon a plate with the
former."
Frankel regards this bacterium as a kind of intenne-