45
is met with in 5 of the series (excluding 3 and 4); it is entirely absent from I
only. Cloacæ has been found occasionally [vide table VII-(c)].
The proportion between saccharose and non-saccharose fermenters is 147 to 604
(about 1 to 4). This increase in the non-saccharose fermenters in India, coupled with
the fact that soli communis is frequently a rare organism in fœces, emphasizes the
difference between the two parts of the world, when considered from the standpoint of
the water analyst.
It should be mentioned here, that the samples of human fœces, used by us,
were taken from the native population, who are almost entirely vegetarians; it would
not appear that the diet had any very great influence on the bacteriological contents.
In cowdung MacConkey (1905) gives the following percentage in his groups : —
Our average in 955 organisms.
Group No. I
... 16.6 per cent.
43.1 per cent.
No. II
25.0
11.0
,,
No. III
... 479
„
13.0
,,
,,
No. IV
12.5.
32.9
He also states " none of the organisms isolated of group IV were identified as
bacillus lactis ærogenes type." These percentages appear to be worked out on 48
colonies from six samples of cowdung ; so the data are rather small. It will be observed
that the relation between the four groups in this country is very different from that in
Europe. Lactis ærogenes is usually met with in small numbers in cowdung in this-
country. Bacillus cloacæ is sometimes extraordinarily common.
The proportion of saccharose fermenters to non-saccharose fermenters is 409 to
552 (about 4 to 5).
Human.
Cowdung.
Placing the averages for cowdung and human fœces side-
55 .7 per cent. 43 • 1 per cent.
23 . 2 „
11.0 „
by side, it would appear that in human fœces groups Nos. I
7.5
,,
13.0
32.9 „ and II predominated, in cowdung Nos. I and IV.
14.3
This conclusion may be interesting, but we doubt if it is of very much practical
use to th.e water analyst. It would certainly not be safe to conclude, that, because
the organisms in any sample of water (especially after exposer to the sun) followed
the usual percentage of cowdung or human fœces, that therefore cowdung or human
fœces was the polluting agent.
If we compare the group percentages of the natural river and lake waters, quarter.
by quarter (see Chapter XIII) with these averages, we find that we should arrive at the
conclusion, that rivers in the first quarter were polluted with cowdung and in the
second by human fœces ; in the case of lakes the first and third quarters suggest
pollution by cowdung, whilst the contamination in the second does not correspond with
either cowdung or human fœces.
MacConkey (1906) has shown that in the examination of milk these figures may
be of considerable value.
In studying the figures of the various series it is apparent that there are very
considerable differences in the percentage proportions at various times of year. Compare,
for instance, the percentages of series Nos. 1 and 9 in human fœces ; again, series No. 6,
human fœces, might easily be mistaken for a cowdung average ; it very closely resembles.
series No. 2, cowdung. Series No. 5, cowdung, might easily pass for human fœces.
Further, by reading the figures in the various groups, in tables VII (a) and (b) from
left to right, very considerable variations will be observed ; apparently groups II and
III are subject to the greatest irregularities.
Still the broad generalization, that, in human fœces groups I and II and in
cowdung groups I and IV predominate, must in the main be admitted as correct.
Considerably more work is necessary before a more definite statement can be made.
In this country we do not place very great importance on this method of
dividing up fœcal organisms into arbitrary groups, based on fermentation reactions.
We shall show later on that the actual flora of fœces, apart from groups, varies
considerably at different times of the year. We consider information of this kind
to be of much greater interest and practical value than the division of micro-organisms
with artificial groups.
12