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Scientific Memoirs by

      On the twenty-first day another plate was inoculated. Two days later
it had a strong disagreeable smell, and was covered with large blue and yellow
colonies. Three out of four preparations contained commas.

      Twenty-eight days after the inoculation of the soil another plate was set.
Forty-eight hours later it had a strong but somewhat choleraic smell, and con-
tained numerous colonies, the majority of a yellowish tint, but a few bluish ones
also being present. The former consisted of large, thick, straight rods, the
latter of small commas.

      On the forty-seventh day a final cultivation was set. In the course of
twenty-four hours it had become full of colonies, like those in the previous case,
and had acquired a faint, somewhat choleraic smell. The blue colonies, as before,
consisted of commas.

      EXPERIMENT VI.—Some fresh fæcal matter was triturated with 100
grammes of dry garden-earth and set in a covered beaker as in the previous ex-
periment. Two days afterwards the growth of two tube-cultivations of commas
of four days' date was stirred up in sterilised salt solution and poured over the
earth. Nine days later the soil was still very moist, with a slightly fæculent
odour and a neutral re-action. A plate-cultivation of it was set. Numerous
schizomycete colonies and patches of fungal hyphæ appeared in it. It had no
perceptible odour and no commas could be found in it.

      On the nineteenth day the surface of the soil was still quite moist, emitted
a faint stercoraceous odour, and was covered by a puffed-up sheet of fungal
mycelium, with radiant, whitish tufts of hyphæ. A plate-cultivation was set.
On the following day it was covered by a continuous stratum, of ochre colour,
which involved isolated colonies of several kinds. The smell was faint and dis-
agreeable but non-choleraic. No commas were to be found in it.

      Taking the experiments as a whole, they indicate that comma-Bacilli, when
introduced into soil and water of very different qualities, so long as these retain
their natural condition, tend to disappear very rapidly.

      The periods of survival are shown in the following tables:—

Table I.—Periods of Survival of Commas in Water.