Medical Officers of the Army of India.

15

A mass of it was set in a sterilised watch-glass in a moist chamber, and a
plate-cultivation was started at the same time. Numerous colonies appeared
in the latter. They were of small size and yellowish colour, and were accom-
panied by a faint odour quite distinct from that present in cultivations of cho-
leraic commas. They all appeared to be alike and composed of very short,
thick, almost micrococcoid Bacilli. On the 31st March the cowdung was
inoculated with a mass of agar-agar full of commas. Numerous plate-cultiva-
tions were carried out from time to time up to the 20th pril, but in no case
did any commas make their appearance. Numerous colonies developed in all
cases, but these never contained commas. The majority of them consisted of
short, thick Bacilli, which, when in mass, had a peculiar greenish-yellow colour,
and which imparted an odour to the cultivations very similar to that of cultiva-
tion of commas. Repeated cultivations showed clearly that they bred perfectly
true under conditions most favourable to the development of commas, and
that they, therefore, were specifically distinct from the latter. On the 20th April
a plate-cultivation was inoculated from the portion of agar-agar introduced into
the dung on the 31st March, and which was now, curiously enough, absolute-
ly crowded with the myceleum and zygospores, or, perhaps mote correctly,
oospores, of a small mucorine fungus, apparently parasitic on Pilobolus crystalli-
nus, which at this comparatively late period had begun to appear in abundance
on the surface. There were no recognisable commas in the agar-agar, and the
cultivation failed to produce anything save a few minute colonies of straight
Bacilli.

        The above data appear to indicate that cowdung, apart from the organisms
normally present in it and destroyed by boiling, constitutes a highly favourable
medium for the development of choleraic commas, but that in its normal
state the development is either entirely repressed or very much enfeebled, due to
the influence exerted by other fungal and Schizomycete organisms. They
also clearly show that in this medium also the commas have no capacity for
the assumption of a resting condition.

        The first set of experiments had appeared to show that human excreta did
not constitute a favourable medium for the growth of choleraic comma-bacilli,
but it appeared desirable to endeavour to ascertain how far the results then
attained were not due to the acid fermentation normally occurring in such
materials in connection with the abundant development of fungi usually occurring
in them during the earlier stages of decomposition. Some normal, fresh, almost
neutral human fæces were accordingly diluted with distilled water and strongly
boiled for some time, and a portion of the material was then set in a sterilised
watch-glass in a moist chamber. On the following day the re-action was
distinctly and permanently alkaline. A portion of agar-agar, full of healthy
choleraic commas, was now introduced. Forty-eight hours later the material
had a peculiar mawkish smell and was alkaline in re-action. From this, time