REPORT ON THE WORKING OF THE MICRO-BIOLOGICAL SECTION
OF THE KING INSTITUTE OF PREVENTIVE MEDICINE, GUINDY,
FOR THE YEAR 1917.
Up till the 24th of June there were no changes in the staff but on that date
the Director was compelled by ill-health to go on combined leave for six and a half
months. Major W. A. Justice, I.M.S., was in charge of the Institute up till the
16th August, in addition to his duties as Sanitary Commissioner for Madras, when
he was relieved by Dr. M. Kesava Pai, who was appointed to the position of Acting
Director and who remained in charge of the Institute for the rest of the year.
During the year Government was approached with a scheme for the more
efficient and rapid transit of pathological and other materials between the Insti
-tute and the various State Hospitals in the City. In G.O. No. 452, Medical,
dated 3rd November 1917, Government sanctioned this which involved the depu
-tation of a Civil Assistant Surgeon to be in charge of this work and the purchase
of a specially equipped motor-car. Civil Assistant Surgeon S. Ramakrishnan,
who had been assisting in the Vaccine Section, was appointed to take charge of
these new duties, his place in the Vaccine Section being taken up by Civil Assist
-ant Surgeon M. Gopala Ayyar on 3rd December 1917.
As in previous years a very large volume of work was dealt with at the
Institute.
Water analysis. —There was an increase of 30 per cent in the number of
samples examined chemically but a drop of 40 per cent in the number of samples
examined bacteriologically. This very considerable drop must however be associ
-ated with the marked rise in the number of other specimens sent for examination.
This rise was from 2,524 to 3,414 or 35 per cent.
Sand filters.—During the first seven months of the year, the question of
sedimentation as a preparation for filtration was studied. In the case of Adyar
water, and probably in that of any other highly polluted river water, sedimenta
-tion was found to be of great value. Storage in sedimentation tanks for periods
of 4—8 days was found to bring about a ten thousandfold reduction in the lac
-tose fermenters. Sedimentation up to 15 days was tried but the results obtained
were not so good above 8 days and below 4. This is radically different from
Thames water which goes on improving from storage up to three weeks or more.
It is therefore not safe to assume that what occurs in England will necessarily be
true in India. This circumstance adds greatly to the value of the experimental
work on the subject of filtration which is being carried out here when, for the
first time in India, the matter has been adequately studied. A farther advantage
from pre-sedimentation is to be found in the efficiency of the filters. These are
found to work more steadily for a longer period between cleanings and to be more
immune to accidents. This may be attributed to the filtering skin in sedimented
water being more even in grain and probably better felted together, the particles
deposited from the water being of course smaller. Unfortunately it was not pos
-sible to carry out more than one experiment for longevity and this gave a period
of 97 days for the covered filter and 80 days for the open filter. These results
are quite conclusive for the open filter as 80 days is considerably longer than the
longest period this filter worked with unsedimented water. Of five experiments
done in 1916, 64 days was the longest and 54 was the average. In the case
of the covered filter the case is not so clear as longer periods of running were
got in 1916 but the average of five was only 83. From July to December
experiments in varying the depth of the sand in the filters were tried. Thus in
the covered filter the depth of the sand was reduced from 2 feet 3 inches to 1 foot
6 inches and in the open filter from 3 feet to 2 feet. In the former case the
results were not satisfactory but good results were obtained with the latter.