154 MALARIA 



Colombo that the mosquitoes have distinctly dimin- 

 ished in number in parts of that town since the custom 

 of storing water near the houses was abandoned. 

 During the summer of 1900 the authorities at Sassari 

 in Sardinia claim to have 'practically exterminated the 

 mosquitoes ... by killing the larvae in the swamps 

 with petroleum, and the flies with chlorine and other 

 destructive chemicals.'* 



The extinction of malaria in England is a kind of 

 by-product of the draining operations which restored 

 to the agriculturist large tracts of land in the fen 

 districts and elsewhere. The breeding-places of the 

 mosquitoes were dried up and their numbers materi- 

 ally lessened ; at the same time the parasite was 

 killed in an increasing number of patients. Thus the 

 mosquitoes which survived had fewer opportunities 

 of infecting themselves, and as time went on the 

 parasite was ultimately eliminated. Anopheles, though 

 in diminished numbers, is still with us, and is espe- 

 cially to be found in those parts of England once 

 infested with the malaria ; but the parasite has 

 disappeared. 



* Vide p. 162. 



