PA THOGENIC BA CTERIA.

of bone. When further developed the colonies flow
together and give the plate a' cloudy gray appearance.
The gelatin is not liquefied, but is gradually softened and
its evaporation thus aided.

In gelatin puncture-cultures the growth is quite cha-
racteristic, and the tendency of the bacillus to grow
anerobically is well shown (Fig. 119). The develop-

FlG. 119.—Bacillus of mouse-septicemia: gelatin puncture-culture three and a
half days old (Giinther).

ment takes place all along the line of puncture, but is
more marked below than at the surface. The growth
takes place in a peculiar form, resembling superimposed
disks, each disk separate from its neighbors and consist-
ing of an area of clouded grayish gelatin reaching almost
to the walls of the tube. This growth develops slowly,
and causes a softening rather than an actual liquefaction
of the gelatin.

Upon agar-agar and blood-serum a very delicate, trans-
parent grayish line develops along the path of the needle.
It does not grow upon potato.

The bacillus grows at the room temperature, but much
better at the temperature of the incubator.

The disease affects quite a variety of animals, notably
hogs, rabbits, mice, white rats, pigeons, and sparrows.