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Sample (8) taken on 30th March 1909, showed the following analysis : 1 coli
communis, 9 coscoroba.
Of course it is much too early to draw conclusions from these experiments ; but
the_results given are extremely interesting. The following points should be noted :
that although coli communis was not isolated in the first two specimens, it was found
in the 3rd, 4th, 5th and 8th ; hence this bacillus can exist in the ground for 97 days
at l east . *
Another interesting point is that quite late on (that, is to say, 82 days after the
trench was started) the rare organism No. 33, which belongs to MacConkey's group
No . 2 made its appearance in that sample, though it was not isolated in subsequent
ecimens. Up
to the present (97 days) we are still obtaining the common faecal
sp.
organisms in the ground. It should be noted that in very few samples bacillus cloacae
was absent.
2. Earth derived from the Ootacamund sewage farm was buried in a shallow
trench at a depth of about 5 to 7 inches. Analyses of the earth have already been
described on the preceding page. Samples of this earth also were taken from time to
time and the results recorded. These experiments are still being continued and are
proving of considerable interest.
The earth was buried on 25th January 1909. The organisms found before burial
were in this sample, 6 acidi lactici and 4 grunthal.
Sample (2) taken on 8th February 1909 showed the following analysis : 2
cloacae, 6 grunthal, 2 organisms No. 67.
Sample (3) taken on 15th March 1909 showed 10 bacillus cloacae.
Sample (4) taken on 23rd March 1909 showed the following analysis : 10
cloacae, 1 bacillus No. 73.
Sample (5) taken on 30th March 1909, showed the following results : 2
grunthal, 1 cloace, 2 lactis æærogenes, 1 No. 67, 4 No. 75.
It would appear from these results as though the organisms present in the sewage
farm earth were dying out rather quicker than those from night-soil, but it is yet
rather early to dogmatise. Apparently coli communis does not seem to be present, at
any rate not in sufficient numbers to enter into the results. Cloaca and organism
No. 75, it will be remembered, are both frequently met with in the older specimens
taken from the trenching ground, and are resistant organisms.
Further work on this very important subject of the vitality of organisms
in the ground is in progress, but we consider that the following conclusions are justified
from the results already reported :-fæcal
(1) Bacillus cloacæ, bacillus grunthal, bacillus No. 75 and to a less extent
bacillus coscoroba are capable, under favourable conditions, of remaining alive in the soil
for a considerable length of time, probably up to 3 or 4 years.
(2) That fcal organisms of any kind do not appear to exist in large numbers
after they have been in the earth for longer than 1--2 years ; night-soil buried in the
ground, even in large quantities loses most of its organisms in this period.
(3) Sporogenes enteritidis spores are capable of remaining alive in the ground
for a period of something between 3 and 4 years.
( 4) Bacillus coli communis has never been isolated from the trenching ground
hence it is probable, though not certain, that this organism does not remain
samples ;
alive in the ground as long as the more resistant organisms like cloacae, etc. It has
been proved in one experiment to exist in the ground for a period of 97 days.
* Note the ground in which the trench was made did not contain lactose fermenters.