179

SAMPLE V.—TAP WATER NEAR SAIDAPET TOLL-GATE. Colony
number.		 Lactose. Saccharose. Dulcite. Adonite. Inulin. Voges and prosk. Indol. Motility. Group. Bacillus. Group and
remarks.
        (a) Total colonies per cc. on agar at 37°—countless.
        (b) Bile salt lactose, medium. + –
  1 + + + + – – – – III B. Pneumoniæ. Group I, nil.
               1 tube 20 cc. water taken 1 .. 2 + + + + – – – – III Do.    ,,    II, nil.
               2 tubes 10 cc. ,, 1 1 3 + + + + – – – – III Do.    ,,   III, 10.
               3 ,, 5 cc. ,, 1 2 4 + + + + – – – – III Do.    ,,   IV, nil.
               3 ,, 1 cc. ,, .. 3 5 + + + + – – – – III Do.  
               3 ,, .1 cc. ,, .. 3 6 + + + + – – – – III Do.  
               3 ,, .01 cc. ,, .. 3 7 + + + + – – – – III Do. Class I, nil.
  8 + + + + – – – – III Do.    ,,    II, 10.
        (c) Fcecal bacilli in 5 cc. and upwards. 9 + + + + – – – – III Do.    ,,   III, nil.
  10 + + + + – – – – III Do.  

REPORT.

          Bacteriologically the conditions found on examining these samples are those typical of dry weather. Germs
of excremental origin are few in number and only one or two species are represented in any one sample. The
total count of saprophytic germs is however undesirably high, and a reason for this is to be found in the
chemical constituents of the water. Chemically the water is bad, and probably many germs find in it a suitable
medium for growing in. The figures for albuminoid nitrogen and absorbed oxygen are too high in all the
samples. This points to the presence of organic matter in the water, and the ratio of the nitrogen to the oxygen
is too high to support the contention that that organic matter is of purely vegetable origin. At least a portion of
the organic matter being of animal origin it follows that the gathering ground or the channels are not suffici-
ently conserved, and though the prevailing weather conditions have brought about the disappearance of the
objectionable and dangerous features of animal pollution, there is but small ground for security should less arid
weather supervene. The water of the Red Hills lake furnishes a good example of the purification brought
about by the action of sunlight. Fæcal bacilli in it are only one-fifth as numerous as in the supply channel, and
yet the total count is just as high or higher. Sedimentatiou, we must suppose, will affect all sorts of germs
equally, but here we have distinct evidence of one class of germ, fortunately the class we desire to get rid of, being
more susceptible than the purely saprophytic classes are.