THE NATURAL HISTORY OF BOMBAY MALARIA. 411 



fact and one of considerable importance in relation to malaria 

 prevention in Bombay, that temporary pools and collections of 

 water only appear to become infected with the larvae of the malaria- 

 carrier N. stephensi. when permanent breeding places of that mos- 

 quito exist in their immediate neighbourhood. Thus in the mon- 

 soon while numerous pools of fresh rain-water in the New Dock 

 Works contained great numbers of larvae of N. stephensi, it was 

 impossible to find the insect breeding in the countless pools of rain- 

 water to be found in Byculla and other areas in the centre of the 

 island.. The only explanation that I can offer for this condition of 

 things is that, in Byculla and the centre of the island there are 

 few wells and other permanent breeding places suitable for N. 

 stephensi, which as a result is almost non-existent there : the 

 scores of pools in that part of the island remaining uninfected 

 because of the absence of permanent breeding places of this mos- 

 quito. 



Whether or not this is the true explanation I cannot say, but the 

 fact remains that the vast majority of pools in the north of the city 

 do not appear to be a danger from the point of view of malaria. 

 This is proved by the fact that not more than 1 per cent, of the 

 people living in the neighbourhood of Gilder Street and Jacob 

 Circle are infected with malaria whereas from 40 to 50 per cent, 

 of the people residing in the neighbouring of Frere Eoad harbour 

 the malarial parasite. In the neighbourhood of Frere B,oad there are 

 wells, fountains, cisterns and tanks which have probably formed per- 

 manent breeding places for N. stephensi for many years, and when 

 increased facilities for its breeding were aiibrded by the numerous 

 pools of water which formed in the enclosure of the New Dock 

 Works during the monsoon, it was enabled to take advantage of 

 them with disastrous results to residents in that neighbourhood. 



Minor temporary breeding places. 



In giving a list of places in which N. stephensi could often be 

 found breeding, I mentioned, tubs, tin-pots and other miscellaneous 

 collections of fresh water. But what I have just told you about the 

 temporary pools of water becoming dangerous only in the presence 

 of permanent breeding places of N. stephensi holds -good in regard 

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