15
REPORT OF THE KING INSTITUTE, GUINDY
dilution, despite which all except one (from the Madras City Water) proved
pathogenic to guinea pigs on intraperitoneal injection. High titre sera made from
each strain gave cross agglutination reactions with all other strains. Work is
being continued. This subject is very important in the light of some recent
work which claims that atypical vibrios become pathogenic and produce cholera
under certain conditions. No definite evidence on this point has yet been
obtained here.
21. Comparison of chlorine dosage for water required according to Chemical
and Bacteriological tests.— It has been observed by some workers that the dose of
chlorine required to kill all lactose fermenting organisms in water is in some cases
very much less than that indicated by the preliminary chemical tests usually
made. Mr. T. N. S. Raghavachari and Mr. P. V. Sitarama Ayyar are making
an extended investigation on this point on all the main water supplies in the
Presidency. The results will be reported later, but so far it has been found that
under laboratory conditions in almost every case the observation mentioned is
true which points to a waste of money in over chlorination if it is found that the
same results hold good for chlorination carried out on the water works scale.
22. Comparison of media made isotonic by the addition of Locke's salt
with ordinary media made isotonic by the addition of common salt :
—
At the instance of the Director, Military Assistant Surgeon F. G. Martin,
I.M.D., carried out experiments on the differences in growth obtained in broth
and agar media using common organisms such as B. Typhosus the Para
Typhoids, B. Dysenteriae, Staphylococcus Pyogenous aureus, haemolytic and
non-haemolytic streptococci and Pneumococcus. On the whole the Locke's salt
media gave better growth as tested by opacity findings and this was particularly
the case with the typhoid and dysentery group. This is important in the large
scale manufacture of vaccines where every encouragement to growth however
slight has to be obtained.
23. Filariasis.—The Assistant Director, Dr. C. G. Pandit with the help of
Mr. P. V. Sitarama Ayyar has made observations on the filarial infection in
Calotis versicolor, the so-called "blood sucker." This investigation was under--
taken from two points of view, viz. (1) to study the incidence of infection in these
animals in all its aspects, i.e., a filarial survey with special reference to incidence
of infection in different localities, as also the influence of season, age, sex, etc.,
and (2) to ascertain the possibility of their use as suitable animal for laboratory
investigation into various problems connected with human filariasis.
This specific filaria was called F. flavescens by Castellani in 1904. It has
now been identified as belonging to the new genus " Saurositus " created by
McFie in 1924. The proper name of the parasite is therefore Saurositus
flavescens. It was found that the percentage of infected animals varies in
different localities ; in some, e.g., in individuals from the vicinity of the institute,
it is as high as 70 per cent, in others it falls below 20 per cent while individuals
from some localities show no infection at all. Age also plays a prominent part in
determining the incidence of infection. These points are being studied in detail.
After observations made on some probable intermediate hosts such as mites and
biting flies, the development of the micro filaria was observed to take place
readily in Culex fatigans (Wied). Various stages of development in the
mosquito have been noted. Factors leading to the successful infection of the
mosquito are being studied and attempts are being made to transmit the infection
to healthy animals by various methods.
A third line of investigation has been taken up in making serological
observations on bloods from Calotes and from human cases of filariasis. The
results obtained are very encouraging. The whole research is being continued
and it is intended to give Dr. Pandit the assistance of an investigation unit in
this important research. A paper will be published later.
24. Interrelation of the viruses of the vaccinia group :—Reference page
10 of last year's Annual Report. Dr. C. G. Pandit continued the work and
published a paper.