1900.] 



and the distribution of Anopheles Mosquitos. 



469 



named, its spleen-rate being 28'6 per cent., while the water-level was 

 9 ft. below the surface of the ground in February, and had risen to 5 ft, 

 from the ground in the rains of 1899. The water-supply is mainly derived 

 from the river. Thirdly, Tchapur, which is situated to the north-east 

 of the last circle, and the main portion of whose inhabitants reside at a 

 distance of about one mile from the river, and near the Grand Trunk 

 Road, and consequently are mainly dependant on tanks for their water- 

 supply. The spleen-rate of this circle was 56 per cent., although as the 

 ground water-level was 10 ft. from the surface in February and had not 

 risen above 4 ft. in the rains of 1899 there was no difference in this respect 

 from the other two circles which could possible account for the greatly 

 higher spleen-rate of Ichapur, whose water-supply from tanks instead 

 of from the river appears to be the only possible explanation of the 

 facts recorded. 



TABLE XI. 



North Barrackpore. 



Area. 



Ground 



Water-Level. 



Feb., Rains, 



1900. 1899. 



Water-supply 



Corrected 

 Spleen percentages. 

 Adult Children. General 

 Males. 



Monirampur(28) Below 9 ft. ... 

 Nawabgung(29) 9 ft. 5 ft. 



Ichapur (30) 10 ft. 4 ft. 



Total. 

 240 



286 

 560 



Mainly river. 24*5 23-5 

 do. 372 30-1 



Tank. 52-0 660 



Garihja. — This small Municipality is situated between the Hooghly 

 river and the Grand Trunk Road immediately to the north of the 

 Ichapur Khal, and its northern half has been supplied with filtered 

 water from the Dunbar Cotton Mill for the past two years, but the 

 inhabitants of the southern portion for the most part still drink river 

 and tank water. As there was a very general opinion among the people 

 living near the Mill that they had suffered much less from fever 

 since the filtered water had been introduced, I determined to examine 

 100 persons who resided near the Mill, and the great majority 

 of whom (about 80 per cent.) were found on inquiry to have been 

 drinking the filtered water ; and another 100 a little further to the 

 south, but all within one mile of the former, and who stated that they 

 drank river or tank water. Among the former class the spleen-rate 

 was found to be 21*1 per cent , while among the river and tank water 

 drinkers it was 46'5 per cent., although the latter included 28 men who 

 had arrived from the North- West Provinces only in November last 

 that is after the fever season is nearly over, and whose spleen-rate was 

 only 10*7 per cent. If these men are excluded from the calculation the 

 spleen-rate of the permanent residents of this southern portion of the 



