SANITATION AND HYGIENE ON TROPICAL ESTATES 89 



mosquitoes cannot continue to exist in that district. 

 Owing to careless wording in the writings of some 

 authorities, an idea is prevalent that certain mosquitoes 

 can breed in running water. To disabuse the mind of 

 this incorrect notion, it is only necessary to remember 

 that mosquito larvae are for two or three days at least 

 quite helpless, or nearly so. Mosquitoes breed in the 

 pools formed along streams and among the weeds and 

 algae of their margins; and it is owing to the way pools 

 are formed along hill-streams and ordinary earth drains 

 in hill country owing to violent flooding during rains, 

 that hill-land drained to a certain standard for agriculture 

 yet remains a breeding ground for mosquitoes, and hence 

 is often malarious. In addition, hill-land is full of springs 

 which are constantly breaking out in fresh places. 



To drain hill-land thoroughly it was necessary to use 

 agricultural pipe drains, although their use was attended 

 by great difficulty, and, it may be remarked, that except 

 in the case of work carried out under the Malaria 

 Advisory Board, often resulted in much expense, and at 

 least partial failure. A description of the work cannot be 

 given here, but it is hoped that an exposition of the 

 methods employed will shortly be available. It may be 

 stated, however, that complete success has attended the 

 work of the Board, and that the most precipitous country 

 has been drained at a very moderate cost, and that 

 thorough drainage can now be employed with confidence 

 on any ground by those properly qualified to under- 

 take it. 



The results of the work in Kuala Lumpur are most 

 satisfactory, and demonstrate in a striking manner the 

 advantage of anti-malarial drainage well carried out. 

 Unfortunately, the returns are still effected by the con- 

 tinued existence of four large swamps, known to breed 

 anopheline mosquitoes, where filling work is in progress 

 under the Public Works Department, and what malarial 

 sickness remains in the town is largely due to these 

 swamps. The table below gives the true death-rate and 

 the malarial death-rate for each year since 1907: 



1907 1908 1909 1910 1911 1912 1913 



True death-rate per 1,000 ... 37-9 437 32-3 30-3 39-4 367 35-5 

 Malarial death-rate per 1,000 ... 9-7 107 77 9*8 9*9 5*8 4'2 



