REPORT OF THE KING INSTITUTE, GUINDY
Institute and a bacteriological chemist Mr. N. Swaminathan was engaged and put in
charge and worked under the Director. He has made more than 500 different
analyses of the various effluents with the main intention of comparing the
effluents from the different tanks. It was found that there was not enough
sewage to regularly work the Imhoff tank so that the latter was worked only
intermittently and falls out of the comparison. Sewage was passed through the
tanks at the same rate as regards each other but at different rates in different
periods, the time of stay in the tanks varied from 12 to 24 hours. The results show
that whatever the rate of passing, there was practically no difference between the
open and closed septic tanks as regards the amount of free ammonia present in
the effluents. The average percentage reduction of albuminoid ammonia through-
out the year in the closed tank was 41.95 and in the open tank 32.26. Thus the
closed tank was definitely superior in this respect.
As regards the oxygen absorbed as was to be expected, the open tank was a
little the better but since this criterion is less important, we conclude that on the
whole the closed septic tank was a little better than the open.
(E) RESEARCH WORK.
1. Malarial survey of Udayagiri in Nellore District in April 1926 by an
Investigation Unit in charge of Assistant Surgeon K. V. Krishnan. An extra-
ordinary state of affairs was found. Almost every one of the inhabitants
questioned gave a history of recent malaria. That these statements were true is
shown by the fact that 96 per cent of the children in the main village had malaria
parasites in their blood. The spleen rate was 54.4 per cent. The area was at
the height of a very severe epidemic of malaria which had gone on increasing from
the autumn of the previous year. Adult anophelines abounded. Though A.
rossi was the commonest, yet malaria carrying species such as A. culicifacies and
A. f u l i g i n n o s u s , p a r t i c u l a r l y t h e f o r me r , wa s a l mo s t a s c o mmo n . T h e i n f e c t i o n
rate in A. culicifacies and A. fuliginosus was as high as 10 per cent. The important
breeding places of these carriers were wells, tanks, irrigation canals, and streams
from the hill adjacent. The conditions here presented a strong contrast to
the Mopad area, which is only 30 miles away and which had been surveyed in
the previous month as reported on page 10 of last year’s report. At Mopad the
annual malaria epidemic was over as is usual at this commencing hot time of
the year and hardly any adult anopheline carriers could be found despite the
abundance of breeding places containing larvæ. On the other hand Udayagiri
near by at the foot of a hill had received particularly heavy rains both in 1925
and in spring 1926 with the result described. I think that the difference between
the two places is to be ascribed almost entirely to the effect of the difference in
rainfall and other local conditions on adult malaria carrying anophelines as regards
their breeding and length of life.
2. Malaria survey of Duttalore in April 1926, by the same unit as in (1)
above. Duttalore is a large village 10 miles east of Udayagiri. Despite its
proximity to the latter it was found that as usual at this time of the year there was
very little active malaria and that malaria carrying anophelines A. culicifacies
and A. fuliginosus though present were scanty. A comparison with Udayagiri
again shows the importance of local conditions and local rainfall in producing
malaria. It is worth mentioning that A. jamesi which is uncommon in this
Presidency was found breeding freely in a single well in the adjacent hamlet of
Kamavaripalem.
3. Second malaria survey of the Mopad area—for first survey see Annual
Report for 1926, page 10. This is a very heavily irrigated area in the Nellore
District and it was hoped that a definite recommendation could be made that would
diminish the present heavy incidence of malaria. The first survey had been made
in March 1926 at a time when with the commencing hot weather conditions had
become unfavourable for malaria—see remarks in (1) above in the Udayagiri report.
In the absence of Dr. Krishnan who had done the first survey, a unit under Assistant