PATHOGENIC BACTERIA.

examined in the living condition it is found to be non-
motile.1

The bacillus readily succumbs to the action of heat
and dryness. The cultures upon gelatin plates after
about two days appear as irregular, small, white points.
The deep colonies reach the surface slowly, and do not
attain any considerable size. The gelatin is not lique-
fied. The microscope shows the colonies to be irregularly

Km. 112.—Bacillus of chicken-cholera, from the heart's blood of a pigeon;
x 1000 (Frankel and Pfeiffer).

rounded disks with distinct smooth borders. The color
is yellowish-brown, and the contents are granular. Some-
times there is a distinct concentric arrangement.

In gelatin puncture-cultures a delicate white line occurs
along the entire path of the wire. When viewed through
a lens this line is seen to consist of aggregated mi-
nute colonies. Upon the surface the development is

1 Most authorities state that the bacillus is not motile, but Thoinot and Mas-
selin assert that it is so. Precis de Microbie, 2d ed., 1893.