CHOLERA. 315

the cholera organism, and the true nature of the bodies
described by Hiippe must be regarded as doubtful.
Most bacteriologists disagree with Hiippe in believing
that arthrospores exist at all, and the fact (which will be
pointed out later on) that there is very little permanence
about cholera cultures throws additional doubt upon the
accuracy of Hiippe's conclusion.

The cholera spirillum stains well with the ordinary
aqueous solutions of the anilin dyes ; fuchsin seems par-
ticularly appropriate. At times the staining must be con-
tinued for from five to ten minutes to secure homogeneity.
The cholera spirillum does not stain by Gram's method.
It may be colored and examined while alive; thus Cornil
and Babes, in demonstrating it in the rice-water dis-
charges, u spread out one of the white mucous fragments
upon a glass slide and allow it to dry partially; a small
quantity of an exceedingly weak solution of methyl violet
in distilled water is then flowed over it, and it is flattened
out by pressing down on it a cover-glasSj over which is
placed a fragment of filter-paper, which absorbs any
excess of fluid at the margin of the cover-glass. Comma
bacilli so prepared and examined with an oil-immersion
lens (x 700-800) may then be seen: their characters are
the more readily made out because of the slight stain
which they take up, and because they still retain their
power of vigorous movement, which would be entirely
lost if the specimen were dried, stained, and mounted in
the ordinary fashion."

The colonies of the spirillum when grown upon gel-
atin plates are highly characteristic. They appear in
the lower strata of the gelatin as small white dots, grad-
ually grow out to the surface, effect a gradual liquefaction
of the medium, and then appear to be situated in little
pits with sloping sides (Fig. 82). This peculiar appear-
ance, which gives one the suggestion that the plate is
full of little holes or air-bubbles, is due to the evapora-
tion of the liquefied gelatin.

One of the best methods of securing pure cultures of