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CHOLERA.                              313

A study of the growth of the organism and the forms
which it assumes upon different culture-media soon con-
vinces us that we have to do with an organism in no way
related to the bacilli. If the conditions of nutrition are

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FIG. So.—Spirillum of Asiatic cholera, showing the flagella; x looo (Gunther).

diminished so that the multiplication of the bacteria by
simple division does not progress with the usual rapidity,
we find a distinct tendency toward—and in some cases,
as upon potato, a luxuriant development of—long spiral
threads with numerous windings—unmistakable spirilla.
Prankel has found that the exposure of cultures to unusu-
ally high temperatures, the addition of small amounts
of alcohol to the culture-media, etc., will so vary the
growth of the organism as to favor the production of
spirals instead of commas. One of the most common
of the numerous forms observed is that in which two
short curved individuals are so joined as to produce an
S-shaped curve.

The cholera spirilla are exceedingly active in their
movements, and in hanging-drop cultures can be seen
to swim about with great rapidity. Not only do the
comma-shaped organisms move, but when distinct spirals
exist, they, too, move with the rapid rotary motion so
common among the spirilla.