146 
Malaria in Ceylon 
( c ) Holes formed by the feet of cattle ( vide PI. XI, fig. 6), and into 
which the fish are not able to enter, are ideal breeding places, and in 
these Anopheline larvae are invariably found. 
Frogs abound in all streams and paddy fields, but they do not appear 
to feed on larvae at all. 
(2) Larvivorous larvae. The commonest larvae with cannibalistic 
proclivities are the large Culicine larvae of Culex concolor, a common 
and voracious mosquito often found in the roofs of native houses. 
These larvae are frequently met with in paddy field water. 
The effect of these areas on the prevalence of local malaria. 
Adopting the plan which has been utilized, whenever malaria has 
been adequately studied, I have taken the degree of infection of children 
under fourteen years of age as an index of the general population. 
To determine which of the breeding grounds is the main focus of 
infection, two courses are open—one, to determine the evidences of 
past; the other, of present malarial infection— 
(1) By taking the splenic index. 
(2) By microscopical examination of the blood. 
(1) Splenic Index of the Children. 435 children have been examined 
by abdominal palpation to determine the percentage with enlarged 
spleens (Appendix I). These children have been selected in batches, 
bred and born in certain areas of the town. As far as was possible every 
child in Kurimegala was examined. The total spleen rate was found 
to be 34'7 per cent., and was higher in males than in females. In the 
male sex the highest index was found to be reached by the tenth, in 
the female by the twelfth year (Appendix I). 
A cursory glance at the map will convince the reader that the inci¬ 
dence of malaria, as judged by the spleen rate, varies considerably in 
various parts of the town ; detailed statistics on this point are given 
in Appendix II. The letters A, B, C, etc. on Map 2 refer to different 
collections of houses where these observations were made. 
The conclusions I arrived at from this study are that, wherever the 
houses are crowded together in the vicinity of paddy fields , there the spleen 
rate is a high one, irrespective of the social status of the inhabitants or 
of the sanitary conditions under which they are living. There are one 
or two areas to which I would call attention. 
