74 



the time of examination, have been shown to be closely associated 

 with these species by a preference for similar breeding-places. It is 

 possible, therefore, that under other conditions the carriers may 

 become much more numerous. 



The small-pool breeders, A . vagus and A . kochi, were not so widely 

 distributed, but supplied proportionately more specimens. The 

 recognised carrier, A . macidatus, has been shown to occur in the same 

 kind of places as these species, and in more continuous wet weather 

 would probably be more numerous, owing to the increase in seepage 

 water and small pools in the districts characterised by the small- 

 pool breeders. The dry weather at the time of the examination was 

 unfavourable to A. maculatus, as many of the springs would be dry, 

 and those containing water would be flushed out by intermittent 

 •heavy rain. 



An adequate cause of the malaria cases admitted to hospital has 

 been found, therefore, and a reclamation of the swamps is justified 

 as a measure for malaria prevention, apart from other considerations. 



In the first of two notes appended to the above report, details are 

 given regarding the association method referred to, series of figures 

 being given in the case of each species. The grouping agrees closely 

 with what is generally known about the breeding-places. Group I, 

 depending on a common preference for small open pools or open hilly 

 country, includes A. kochi, A. vagus, A. macidatus, A. karwari, 

 and A. ludlowi. The last-named may separate itself from this group 

 as the chief member of a salt-water fauna when further data have 

 been collected. Group II, depending on a preference for large swampy 

 pools or low-lying country, includes A. barbirostris, A. hyrcanus, 

 A. aconitiis, A.fuliginosus, A. subpictus var. malayensis, A. separatus, 

 A. tessellatus, and A. umbrosus, and probably A. aurirostris. The 

 last three may separate themselves into a jungle-swamp fauna leaving 

 the rest of the group as an open swamp fauna. Group III, depending 

 on a preference for jungle, probably hilly jungle, includes A. aitkeni, 

 A. leiicosphyrus, A. albotaeniatus var. montanus, and A. ndvumbrosus. 

 Group IV (species with highly specialised breeding-places) is represented 

 by A. asiaticus. 



The second note deals with artificial receptacles of water as breeding- 

 places of Anophelines. The following conclusions are reached : — Larvae 

 are found occasionally in such receptacles and more commonlj^ so when 

 the external conditions are unfavourable for their breeding. Age 

 and disuse render such receptacles more suitable for breeding. The 

 care of domestic collections of water and the clearing up of disused 

 tins and bottles are justified. 



The second report deals with an outbreak of malaria on the banks 

 of the Perak River in January 1918. The Anophelines found were : — 

 A. ludlowi, A. vagus, A. kochi, A. tessellatus, A. aiirirostris, A. 

 leucosphyrus, A. hyrcanus and larvae resembling those of A. umbrosus. 

 As regards the pathogenicity of the various species, while no Anopheline 

 is free from suspicion, the important carriers are A. umbrosus and 

 A . ludlowi, especially the latter. From the data discussed it is con- 

 cluded th'at A . ludlowi was the main cause of the outbreak, that it was 

 enabled to travel up-river by the increase of the salinity of the water 

 during the dry weather, and that the onset of the rains made the w^ater 

 unsuitable for it to breed in and thereby stopped the outbreak. 



The suggestions for the reduction of malaria in this area include 

 methods against the infection of mosquitos, and the reduction of 



