4
Obviously therefore we have different conditions to deal with ; the constitution
of the people is different ; our definition of the term " dangerous pollution " must also
be changed ; and the inferences to be drawn from the relation between quality and
quantity of pollution require re-adjusting. The query that we are face to face with
in India is, what indicates a dangerous pollution, and at what point should a water be
condemned as unsuitable for human consumption ? It has been our endeavour to so
model our work, that, by a careful study of the natural conditions obtaining around
us, we may be able to put a correct interpretation on the phenomena observed, and
by studying things as they exist, to be able to answer the above query. The actual
arrangement of the work has served a dual purpose. Firstly, to carry out that essential
duty of Sanitary Department of keeping a watch on the quality of the water, provided
in these protected supplies, and if possible to improve it ; and secondly, to establish
some working standards, that may be of use to ourselves, and to other water analysts
in India, in giving an opinion on the suitability of a sample of water for domestic
purposes.
From what one can gather there has been little or no detailed research on these
lines carried out in this country. The various workers, who have made bacteriological
analysis of water have either accepted European standards as applicable, or have in some
way modified them to suit what they consider to be the needs of this country ; but
apparently nobody has published these modifications, and it is highly probable that no
two analysts use the same method, or would hold the same opinion as to the inference
to be drawn from the presence of certain organisms in a given sample. It is obvious
therefore, that if some uniform method of work can be arrived at, the opinions of
different workers will rest on a much sounder scientific basis than at present, and will
be comparable one with another. In this way experience as regards the use of local
standards will accumulate rapidly.
Our next difficulty was to find a method of work that would be most successful
in solving these very considerable problems.
As we were setting out to study the organisms found in contaminated water, a
method of analysis that told us most about the f œ cal bacilli was the one best suited to
our needs, for, having decided that the usual European standards did not apply to this
country, it was necessary, if we intended to establish new ones, that the research
should go into great detail.
The method that appeared to promise the best results (in an undertaking such as
the above), is a modification of the one described by Dr. A. MacConkey in his works on
the lactose fermenters (Journal of Hygiene, July 1905), and subsequent papers. A
detailed description of this will be found in another place in this report, but it may be
briefly stated here that by using the two sugars saccharose and dulcit, he divides all
lactose fermenting organisms into four groups :—
Group
I ferments neither saccharose or dulcit.
G r o u p
II ferments
dulcit but not saccharose.
G r o u p
III ferme nts
dulcit and saccharose.
G r o u p
IV ferments
saccharose but not dulcit.
This, we shall show later, is a very small part of the process, and as it is only an
arbitrary laboratory classification, is of very little value to the analyst in interpreting
his results. But by the use of the fermentation of adonit, inulin, duleit, saccharose, the
Voges and Proskauers reaction, the Indol reaction, motility test and (when possible) the
liquifaction of gelatine, it is possible to split up this important group of fcecal bacilli,
into their individual species so that they can be studied separately. In time it is
hoped to be able to assign a relative value, as an indicator of pollution, to each of these
different organisms.
Of course the lactose fermenters are not the only group of fœcal organisms, but
they are undoubtedly one of the most important, the others will, we hope, receive
attention in due course at present the only organism, other than lactose fermenters,
whose presence is looked for in the samples, is the Bacillus Sporogenes enteriditis.