336

PATHOGENIC BACTERIA.

is of great interest in comparison with the spirillum of
cholera and its related forms. Its morphology is in every
particular exactly like that of the cholera spirillum, but
its growth is a little more rapid. It grows upon the
same culture-media and at the same temperature. The
colonies are, however, quite different.

Upon the second day, when grown upon gelatin
plates, the colonies of the Spirillum Berolinensis appear
finely granular and paler than those of cholera. The
borders are generally smooth and circular. As it be-
comes older the colony takes on a slightly brownish
color, and may be nodulated or radiately lobulated. The
gelatin is very slowly liquefied.

FIG. 91.—Spirillum Berolinensis, from an agar-agar culture; x 1000 (Itzerott.

and Niemann).

In puncture-cultures the development takes place along
the entire puncture, and causes a gradual liquefaction of
the gelatin.

Upon agar-agar the growth is generally similar to that
of the cholera spirillum, but at times is copious, dry,
and ragged, and suggests leather by its appearance.

When introduced intraperitoneally 'into guinea-pigs,
the animals die in from one to two days.

The indol reaction is exactly like that given by cul-