12

Scientific Memoirs by

were then added to them, each receiving the contents of one and a half tubes of
common gelatine and one tube of agar-agar gelatine mixed with a certain amount
of freshly-sterilised salt solution and full of healthy commas. They were then
set aside under a bell-glass on a table in the laboratory. Both beakers were
allowed to remain thus until the 6th of January 1887. At this time the surface
of the soil in each was still moist and showed scattered patches of greyish
gelatinous matter, seemingly remains of the gelatine of the cultivations, together
with a few heads of Pilobolus crystallinus. One of them was now set on the
incubator to dry, and materials for cultivation were removed from the other.
These consisted of portions of the gelatinous matter from the surface. Some
of these were broken up in sterilised salt solution and used to start plate-cultiva-
tions, while others afforded material for preparations. The material was faintly
alkaline. It contained no active Schizomycetes, but numerous fungal cells and
encysted fæcal amœbæ, and innumerable still Schizomycete forms, especially in
the spore-condition. The plate-cultivations yielded an abundant crop of colonies
of various kinds of Schizomycetes, but, in spite of careful examination, no com-
mas could be detected.

     On the 18th January another preparation and a plate-cultivation were made
from the same sample of earth. On this occasion the materials were taken from
about a quarter of an inch beneath the surface. No comma-bacilli were recognis-
able in the preparation. The plate-cultivation yielded a very abundant crop of
Schizomycete colonies after it had been for twelve hours in the incubator. It
had a peculiar, strong, bat-like odour, very unlike that characteristic of cultiva-
tions of the choleraic comma-bacilli. Two distinct forms of Bacilli were present
in large numbers, but not a trace of commas could be detected anywhere.

     On the 1st March another plate-cultivation from the same soil was initiated.
The soil was now fairly dry, and after the material required for cultivation had
been removed, some freshly-boiled tap water was poured over it. The cultiva-
tion yielded numerous Schizomycete colonies. They all consisted of straight
Bacilli of various sizes, and no signs of commas could be detected anywhere.
Subsequent cultivations of the same sample of earth also failed to yield any
commas.

     On the 18th March the beaker which had been in the incubator since the
6th January was examined. The earth was found to be perfectly dry. A small
portion was removed and mixed with freshly-sterilised salt solution to form the
basis of a plate-cultivation, a large quantity of freshly-boiled distilled water was
then poured into the beaker, so as to flood the soil, and the beaker was replaced
in the incubator. On the following day the plate-cultivation showed numerous
colonies, consisting of two forms of straight Bacilli, but no commas could be
found. On the 21st March the surface water had disappeared from the soil in
the beaker. Materials for a plate-cultivation were removed, and the earth was
again flooded with freshly-boiled distilled water. On the following day the plate-