REPORT OF THE KING INSTITUTE, GUINDY
15
by sera from human cases of elephantiasis against Microfilaria bancrofti. The
sera used in the experiments here had been obtained. from local cases. Dr. Menon
visited Negapatarn and Vizagapatam and compared the reactions against Micro-
filariae from infected people in those localities that were obtained using the same
sera as used in the work at Guindy. The opposite change was also made. Sera
from elephantiasis cases in Negapatam and Vizagapatam were tested against
Guindy strains of Micro-filariae. All the reactions were positive, so evidence was
obtained that there is no species difference in strains of Micro-filariae Bancrofti
from people in Guindy, Negapatam and Vizagapatam.
(4) Rat Flea Survey of the Madras Presidency. —This Survey financed by the
Indian Research Fund Association was continued. It was controlled by Dr.
C. G. Pandit while I was on leave in the first half of the year. There have been
two Units working continuously on this Survey and in order to help to finish it a
third Unit was added in August. The Officers in charge of these Units during
the year have been :—
( i ) P . V . G e o r g e , B . A . , L . M . s . , B . S . S C .
( i i ) D . S , M a n k i k a r , M . B . , B . S .
( i i i ) J e m a d a r F . J e s u d a s a n , I . M . D .
About 24 places have been surveyed this year and 7 places previously ; so
the Survey is practically finished—it ended in April 1930. Reports already
published are Reports Nos. I, II and III by Lt.-Col. H. H. King, I.M.S., Mr. P. V.
Sitharama Ayyar, M.A., Drs. N. Natarajan, M.B.,B.S., B.S.SC., and P. V. George, B.A.,
L.M.S., in the Indian Journal of Medical Research, Vol. XVII, No. 1 (July 1929).
Reports Nos. IV, V and VI by Drs. C. G. Pandit, M.B.,B.S., P.H.D., D.PH. & D.T.M.,
P. V. George, B.A., L.M.S., B.S.SC., D. S. Mankikar, M.B., B.S., and N. Natarajan, M.B.,
B.S., B.S.Sc., in Vol. XVII No. IV (April 1930) of the same journal.
All the other Surveys have been written up and the Reports Nos. VII to
XIII by myself and the officers in charge of Units have been sent for publication.
Dr. Pandit and I hope to shortly complete a general summary of these
reports and so end the Survey. The main lesson to be learnt from the Survey is,
that, although climate has a great influence in determining the nature of the
rat-fleas prevalent in any place, yet, cheopis, the main plague carrier, is a persis-
tent invader, and that in such invasions not only do grain movements play a
great part, but also, and probably to a much greater extent, movements of cotton
are responsible for the continued introduction of cheopis into localities in which
it has not yet settled down.
(5) Work for the Water and Sewage Purification Committee at the Experimen-
tal Filters at Guindy and Kilpauk .—The important experiments on aeration and
percolation followed by sand filtration were continued, and as noted, the tests
involved have given the Institute a great deal of work, particularly to Mr. Ragha-
vachari, the Senior Bacteriological Assistant in the Public Health Section, who is
in charge of our secondary laboratory at Kilpauk. A full report on the work
from January to November 1929 was submitted and published by Government in
G.O. No. 932, P.H., dated 12th April 1930. The summary runs as follows :
—
(a) As will be seen from the results of experiments the final effluent from a
suitable percolating suite is decidedly superior in every respect to that from an
ordinary slow sand filter. Preliminary percolation greatly diminishes the load
on the secondary sand filter and not only allows it to be run at twice the rate but
also prolongs its life.
(b) Not only were the final effluents from good percolating suites better
than the effluent from the control slow sand filter, but the effluents from such
preliminary percolators alone were on the whole as good as that from the control
filter, and were always free from sulphuretted hydrogen. So, if at any time it be
advisable to cut out the submerged sand filters, then the percolator effluents
alone can be used, and it is to be noted that such effluents could be far more easi-
ly chlorinated than either the raw water or the effluents from the present slow
sand submerged filters.
(c) So far, fine gravel as a percolating medium has yielded the best results,
but other materials are being investigated with a view to obtaining as coarse a