The level of the subsoil water is high, pools are formed with each 
shower and many of them are permanent. In any engineering undertaking 
it is common to find that roads, railway permanent way or embankments 
are made without due regard to the necessity of maintaining the natural 
system of drainage or of providing a superior one. In the making of these 
embankments “ borrow pits ” are made in numbers and no provision made 
for their drainage. 
Under these circumstances mosquitoes of many genera abound, and 
amongst these are several species of anopheles though not the species 
prevalent in the jungle. 
Drainage of such areas presents no real difficulty, and where a 
permanent station is to be formed is economical as well as successful. 
This is well illustrated by the success which has attended this method 
of dealing with the matter at Klang and Port Swettenham. 
Two areas were treated. One consisted of swampy ground near the 
coast through which the Klang River passed. This region is partially closed 
in by a semicircle of hills. The second was flat land and mangrove swamp 
on the coast flooded at high tides. 
During clearing of the mangrove there was a certain amount of Malaria 
amongst those employed. 
When a railway embankment was built there was great interference 
with the natural drainage and the swampy areas were increased, rendered 
more permanent, and protected to some extent from flooding by sea water. 
A great increase in the number of cases of Malaria occurred so much 
as that between September 15th and November 25th, 1901, out of 260 
inhabitants of certain quarters and shop houses 158 or 60 per cent, were 
attacked. In the township of Klang, some o.\ miles up the river at the foot 
of the hills and very swampy, Malaria was also rife. 
A Government Commission composed of three engineers and three 
medical men was appointed, and as a result of their enquiries extensive 
carefully devised measures were undertaken at a cost of some £3,500. The 
results were highly satisfactory. In the last quarter of 1901 the admissions 
for malaria for the two townships were 252 ; for the same period in 1902 
they were only 26. Full details are given in the reports by Drs. Travers 
and Watson. 
These satisfactory results were obtained although the drainage was not 
complete, and there is no difficulty in still finding places, especially during 
wet months, in which anopheles larvae can still be found. Dr. Leicester 
has shown that the species of Anophelina in the drained area does not 
correspond to those met with in the undrained, and that the great majority 
of larvae found in the districts treated are now the comparatively harmless 
M. Rossii, whilst other species not found in these areas abound in the 
surrounding untreated district. 
The effect of the drainage has not only been to diminish the number of 
breeding places, but also to exclude certain species. The measures adopted 
have reduced the amount of Malaria and the deaths from Malaria in hospital 
from 52 in 1901 to 9 in 1902, and still more the general death rate, whilst 
there has been no reduction in these rates in the surrounding district. 
This has been accomplished by the adoption of measures which aimed 
at reduction and not at abolition of breeding-places in the respective areas. 
A certain amount of up-keep is required, and it is to be anticipated that 
