3i8 PA THOGENIC BACTERIA.

The luxuriant development of the spirilla in gelatin
produces considerable solid material to sediment and fill
up the lower third or lower half of the liquefied area.
This solid material consists of masses of spirilla which
have probably completed their life-cycle and become
inactive. Under the microscope they exhibit the most
varied involution-forms. The liquefaction reaches the
sides of the tube in from five to seven days. Liquefac-
tion of the medium is not complete for several weeks.
According to Frankel, in eight weeks the organisms in
the liquefied culture all die, and cannot be transplanted.
Kitasato, however, has found them living and active on
agar-agar after ten to thirty days, and Koch was able
to demonstrate their vitality after two years.

When planted upon the surface of agar-agar the spi-
rilla produce a white, shining, translucent growth along
the entire line of inoculation. It is in no way peculiar.
The vitality of the organism is retained much better upon
agar-agar than upon gelatin, and, according to Frankel,
the organism can be transplanted and grown when nine
months old.

The growth upon blood-serum likewise is without dis-
tinct peculiarities, and causes gradual liquefaction of the
medium.

Upon potato the spirilla grow well, even when the
reaction of the potato is acid. In the incubator at a
temperature of 37° C. a transparent, slightly brownish
or yellowish-brown growth, somewhat resembling the
growth of glanders, is produced. It contains large
numbers of long spirals.

In bouillon and in peptone solution the cholera organ-
isms grow well, especially upon the surface, where a
folded, wrinkled mycoderma is formed. Below the my-
coderma the culture fluid generally remains clear. If
the glass be shaken and the mycoderma broken up,
fragments of it sink to the bottom.

In milk the development is also luxuriant, but takes
place in such a manner as not visibly to alter its appear-