1900.] and the distribution of Anopheles Mosquitos. 467 



The results are as follows, beginning from the south as before. Ward 

 IV., which is a narrow strip situated on the north bank of the Khardaha 

 Khal, up to which the tidal water flows as far as a sluice gale in a bridge 

 under the Grand Trunk Road, and which contains a series of bustees, 

 had a spleen-rate of 48 per cent., that is a high one for a riparian 

 area. The water-level was 10 ft. 1 in. below the surface in February, 

 but had risen to within lft. 3 in. in the rains of 1899. Only 16 per 

 cent, of those who were examined stated that they drank filtered water. 

 In Ward III. 32 per cent, of those examined had drunk filtered water, 

 and the spleen -rate was 30 per cent. The water-level had been 1 ft. 

 6 in. below the surface in the rains of 1899, and was 10 ft. 3 in. down 

 in February, so that in this respect the conditions were just the same 

 as in Ward IV., so this factor will not explain the considerable difference 

 between the health of these two Wards ; the water-supply only being 

 different. Still more marked, however, was the difference between the 

 spleen-rates of the two northern Wards, that of Ward III., which is 

 opposite the Mills, being 19 per cent., and that of Ward IV. immediately 

 further north, was 54'3 ; in spite of the ground water-level of the latter 

 having been 6 ft. from the surface at the height of the rains of 1899, 

 and 18 ft. 4 in. down in February last ; an exceptionally low rate. On 

 the other hand, the number of the people examined in Ward III. who 

 had drunk filtered water was no less than 82"5 per cent., while only 

 19'6 of those of the Ward I. stated that they drunk filtered water, and 

 owing to their greater distance from the supply they were probably 

 less regular in obtaining it than were the inhabitants of Ward fl.at 

 whose doors it was placed. These figures are sufficiently striking, 

 especially as they confirm the data obtained in several other muni- 

 cipalities, to be given immediately, and they are also in entire agree- 

 ment with the following results of the differences in the spleen-rate 

 among the drinkers of the different kinds of water in this Municipality. 

 Thus among 140 filtered water drinkers, 37, or 264 per cent., had enlarged 

 spleens; while among 179 river water drinkers 74, or 41*3 percent., 

 were similarly affected ; but of 55 tank water drinkers no less than 33, 

 or 67*2 percent., had enlargement of this organ. Further, if we take the 

 degree of enlargement among the different classes as detailed in Table IX, 

 below, we find that of those who had enlarged spleens the degree of 

 enlargement was very slight in 62 per cent, of the filtered water 

 drinkers, in 43*2 per cent, of the river water drinkers, but only in 27 

 of those who drank tank water, it being considerable or very enlarged 

 in the remainder. Not only, theu. is the percentage of enlarged organs 

 much greater in those who drank until tered water (the percentage of 

 mixed river and tank water drinkers being 47-4), but the degree of 



