1900.] and the distribution of Anopheles Mosquitos. 461 



sides of the four main roads, and is carried under the New Cut Canal 

 by means of siphons into the Great Salt Water Lake, but these have to 

 be closed at high tides to prevent the salt water running up into the 

 drains, and they do not work very efficiently at present. The portion 

 of the main drains in the western and more densely populated portion 

 of the Municipality are brick-lined, but the eastern portions are of earth 

 only. The water-level was taken in several wells, and in February it 

 was found to average 5 feet from the surface of the ground, while 

 evidence was obtained that it rises to within from one to two feet during 

 the rainy season. A more typically water-logged place it would be 

 difficult to find. For purposes of comparison it was divided up into 

 western and eastern portions, and the spleen-rates were found to be 

 124 for the former and 14 for the latter, although it might have been 

 expected that the less densely inhabited and more water-logged enstern 

 portion would have had a decidedly higher rate. It was in the west 

 part of this Municipality also in which the larvse of the malarial- 

 bearing mosquito was found in from half to two-thirds of the tanks as 

 well as in some other pools, as will be detailed further on, so that none 

 of the known causes of malaria were absent, in spite of which this 

 Municipality, together with that of Chitpore and Cossipore, were the 

 two which showed considerably the lowest spleen-rates of all the 

 thirteen, and these two are the only ones which have a full filtered 

 water supply. 



The following table shows the above figures in a convenient form. 



TABLE II. 



Maniktolla. 



Gonnd 



Area. Water-Level. Water-supply. Corrected Spleen percentages. 



Feb., Rains, Adult Children. General 



1900. 1899. Males. Total. 



Westpart(l) 5 ft. 1 to 2 ft. Filtered. 13 11*8 12*5 



East (2) 5 ft. 2 ft. 6 in. do. 13 150 140 



Chitpore-Cossipore. — This Municipality is situated immediately 

 to the north of Calcutta, and extends eastwards as far as the Eastern 

 Bengal Railway and northwards to the southern border of Baranagar. 

 It is divided into four Wards, namely, Chitpore and Cossipore West ex- 

 tending from the river to the Grand Trunk Road, the spleen per- 

 centages of which are 4*8 and 9*9 respectively; and Chitpore and 

 Cossipore East, extending from the Grand Trunk Road to the Railway, 

 and consequently distant from one to two miles from the river bank, 

 the spleen-rates of which are 13 and 16*75 per cent, respectively. The 

 whole area is supplied fully with filtered water, while those people 

 who do not drink this (and they are certainly a decided minority) 



