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Sample No. 10—Shows the fœcal bacilli as low as 1 in 3 cc. and a tendency
among the organisms present for cloacæ to again preponderate. This is very r e m a r k
able ; in sample No. 11 the water seems to have returned to what may be termed its
hit weather condition, containing no other organism than B. cloacæ. This however
may be a coincidence, for although no rain has fallen for 2 weeks, it seems hardly
likely, that after two recent heavy downpours of rain, that washed a mixture of organisms
• into the soil, the subsoil water would return to the same condition bacteriologically, as
was observed after six months of drought. Further, a glance at the succeeding analysis
shows the numerical preponderance of cloacæ is not maintained, though no rain fell to
cause a fresh contamination.
Samples Nos. 12, 13 and 14—Demonstrate the correct nature of the above
surmise, for all three of these samples contain a mixture of bacilli. It may be observed
that from this point coli communis is seldom present, little or no rain having fallen
between September 28th and October 16th, the period during which these samples
were taken.
Sample No. 15—Is a particularly important one ; its chief interest lies in the
fact that it is taken after an extraordinarily heavy downpour of rain. Between the
dates of 18th and 23rd October 5 inches of rain fell ; the whole of the low-lying country
was submerged and floods were prevalent in all directions. A bacillus was found in
the water, very shortly after this heavy deluge, which is usually not associated with
water-supplies, but is looked upon as belonging exclusively to contaminated milk ; it is
known by the name of oxytocus perniciosus ; we do not propose to say more about
this sample, because the subject of the influence of these phenomenally heavy rains is
dealt with separately in chapter V in this report.
Sample No. 16—Was taken after an additional heavy downpour of 12½ inches, but
oxytocus perniciosus was not present in the sample. The bacilli present the usual
• mixture of fœcal organisms, but do not include coli communis amongst their number.
This heavy rain seems to have disseminated contamination widely, for .01 of a cc. shows
the presence of fœcal organisms. There is another point that must be noted in this
sample, viz., that, owing to the unusually saturated nature of the ground, and also to
rapid pumping about 3 feet of sand " blew up " into the well, thereby decreasing the
depth by this amount.
Sample No. 17.—Nothing particular to remark Fœcal bacilli are present in 1 co.
•
Samples Nos. 18 and 19—Show that the recent rains have greatly improved the
quality of the subsoil water, as soon as the highly contaminated surface water had run
off. In both these samples fœcal bacilli are present only in 20 cc. which is unusually
good for shallow well.
'ample No. 20—Demonstrates the fact that a subsequent downpour of nearly
inches, which occurred at the end of November, spoiled the quality of the deeper
layers of water by admixture from the surface. This is also seen in the next sample.
t i
Sample No. 21.—The quantity of fœcal bacilli has gone up considerably. It
will be observed that the samples taken in December, viz., samples Nos. 20, 21 and
22 show a decided prevalence of bacilli coscoroba, the number of organisms varying
very little.
Sample Ho. 23—Was taken almost immediately after a heavy downpour of rain (over
6 ½inches). The depth of the water in the well has increased considerably. Fœcal
bacilli are present in. 5 cc. ; and it will be observed, that a mixture of organisms is the
result of this heavy rain. It is also interesting to note that a rare organism No.,
• which was isolated from samples taken in two or three places in the Presidency, about
the same time, is present.
.
Sample No. 24.—The rainfall during this week measures only about ½ an inch.
Fœcal bacilli are still present. in 5 cc. ; so that the recent rains have improved the quality
of the well water. The bacilli show a mixture of varieties, 1 coli cummunis and
• several neapolitanus and grunthal being present.
Sample No. 25.—No rain has fallen during the past week. The quality of the water
appears to have deteriorated, fœcal bacilli are present in 1 cc. This is rather difficult
to explain. Coli communis have also appeared, and the analysis of the sample presents
a distinctly undesirable mixture of fœcal organisms of which coli communis is one.
9