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larval niul adult stages. But once the quarantine station with 

 its zeers and trap pits became established, a marked improvement 

 resulted, as had been foretold. The site of the station a little to 

 the east of Mogren village is very suitable, as the reclaimed 

 land to the south is still destitute of human habitations, and 

 mosquitos driven ashore either hang about and lay eggs in the 

 zeers and pits, are destroyed at the station, or are carried by the 

 north wind to Tuti Island where they can do little damage and 

 tlieir broods are found and killed. 



Last summer, trains were for the first time found to be operative 

 on a considerable scale as mosquito carriers. Trains from the 

 north pass close to Anopheline-ridden farms, while those from 

 the south pass along the Tayiba cultivation near Wad Medani, 

 wliich for a time also harboured Anophelines. Mosquitos of the 

 subfamily MECiARHiNiNAE occurred round the central station. 

 They have not hitherto been discovered in the Sudan and must 

 have been introduced by the railway. It will probably be 

 necessary to establish a quarantine trapping station here also, 

 at least during rainy seasons. 



The connection between meteorological conditions and the 

 incidence of malaria are discussed. Of the 87 cases of locally 

 acquired primary malaria notified during the year the great 

 majority followed the rainfall of August. The author lays stress 

 on the danger of irrigated areas generally, and on the part they 

 play as ' attraction centres.' When the Gezira to the south of 

 Khartoum is irrigated on a large scale, the Sudan Government 

 will be face to face with a very serious problem. But with due 

 care and stringent enforcement of existing regulations any 

 danger should be comparatively easily averted. 



As regards larvicides, petroleum has its limitations, for in 

 pools exposed to a high wind it gets blown aside, leaving an 

 untreated water surface on which mosquitos readily lay their 

 eggs. Hence the workers at the Wellcome Tropical Eesearch 

 Laboratories have come to rely more or less on such preparations as 

 sanitas-okol. Mr. H. H. King, the entomologist, found that izo- 

 izal kills or renders moribund all larvae of Pyretophorvs costah'.<! 

 in half an hour when in a strength of l:oO,000. A preparation 

 of 1:40,000 is effective in one and a half hours. Pupae require 

 a stronger emulsion. Owing to its higher price it does not seem 

 to possess any advantage over sanitas-okol, wliich is a very 

 satisfactory larvicide. Creosote has also been tried, but does not 

 seem to have any special virtue to commend it, though perhaps 

 a more extensive trial is required. For dealing with adult 

 mosquitos in the cabins and holds of steamers the method of cresyl 

 fumigation, described by lionet and Eoubaud, is being employed, 

 and in addition the special spray together with the ' Miicken ' 

 fluid recommended by Giemsa. This consists of a special tincture 

 of pyrethrum, soft soap and glycerine, the fluid being diluted for 

 use with twenty times its amount of water. 



The mosquito trap used in houses is on the lines of those 



advocated for sandflies, and consists of a wooden box lined with 



a dark material or painted black inside. There is a hinged door 



closing it below, and in this trap door tliere is a hole whicli can 



.31805 A 2 dr 



