27
In the town of Madras itself the water samples taken from the two sources, that
are kept under regular weekly scrutiny, viz., the King Institute well and the Red Hills
lake, both showed the presence of oxytocus perniciosus. In the former of these, the
sample of 24th October, after a fall of 15 inches of rain in 24 hours, showed almost a
pure culture of this organism, but a week later, 3rd November, the latter had
disappeared though an additional 13 inches of rain had fallen in the interval. A full
description of the King Institute well is given in Chapter VI, from which it will be
seen that no flood water could get into the well except by percolating through some 30
feet of porous earth.
The Red Hills lake is a very large sheet of water being about 14 miles round. It
r os e s uddenl y about 4 1/ 2 f eet i n one ni ght , i n cons equence of t he heavy bur s t of r ai n, t he
whole volume of this water being flood water washed from paddy lands and from the
more barren parts of the catchment area, which must be at least 20 square miles in
extent. The sample taken on 25th October, after 15 inches of rain had fallen, contained.
oxytocus perniciosus and. also a second rare organism. The one taken on 31st October
after 10 inches more rain showed that the organisms were disappearing rapidly and
from next sample, taken on 7th November, all had disappeared. The water of the
lake at this time was not very clear, so that the action of the sun's rays could not
have been very effective at any depth; further the sky was mostly overcast, yet these
organisms only survived for a short time in the lake, so that it seems fair to conclude
that they were not in a very congenial environment.
It should be noticed that these places, from which samples have been taken, are
situated hundreds of miles apart over the southern part of India, and. that lakes,
rivers and. wells equally showed. the presence of these rare organisms. Considering
the very few occasions on which these organisms have been met with, except in this
month of October, it is very remarkable that they should suddenly become so very
common over so very large an area.
Now another extraordinary fact became apparent at. this juncture, viz., that at
the same time when these rare organisms were found in the water-supplies, a similar
set of bacteria suddenly made their appearance in large numbers in human fces,
cowdung and the excrement of goats. In some cases the identical species found in
the water-supplies were isolated. from feces, but in all cases this was not so; strange to
say, however, that all the rare organisms found. at this time in fwces, as well as in
water, fermented inulin. The table V (a) shows these organisms.
It is now necessary to discuss the possible causes and explanation of this remark-
able and. widespread. change in the flora of the water in these localities. It seems fairly
certain that the monsoon conditions were in some way responsible for the change. In
a heavy cyclonic disturbance such as the bursting of the monsoon, the rainfall is very
great, 10 inches in 24 hours being not uncommon; the whole country is more or less
submerged; the sky is overcast with clouds for many days; the atmosphere is saturated
with moisture; the temperature is lowered thus the normal conditions of powerful
and prolonged, sunlight, the rapid. dessicating action of hot dry winds, and high
temperature are completely in abeyance.
Further it will be observed. that all conditions were favourable for a large
quantity of fresh and. dry fnces, to be washed direct into the water-courses. But
these remarks, anent the washing of pollution from the land, apply equally well to
heavy showers, and yet, although many samples of water have been taken after a heavy
downpour of rain of short duration, these rare organisms have never in such circum-
stances been found. in the water. Consequently it is not likely that these organisms
exist at all times on the surface of the soil, for if this were the case we should. have
found them in the work reported. in Chapter VI and moreover every shower would.
wash them into the streams and. wells. Further if these bacilli were always present in
fces, precisely the same remarks would apply.
On the other hand it is a fact that these organisms are rare inhabitants of the
intestinal tract of animals and man. They are occasionally met with in faeces at other
times of the year, but a very exhaustive search for them in the foces of a large
number of calves, carried out in January was entirely without result. Inulin bile salt
broth was used. as a selective medium, but not a single organism fermenting this sugar
Could be isolated.