208 GNATS OR MOSQUITOES — CHAPTER VIII 



fastidious of Cidices, though, within cantonments, where 

 their contents may be little else than rainwater, they occa- 

 sionally do so. In provinces, on the other hand, where the 

 rainfall is heavy, and especially in such tanks as lie in the line 

 of a natural drainage depression, and are hence scoured oat 

 by heavy falls, such tanks n)ay contain larvte ; but I doubt 

 if they are likely to do so for any considerable portion of the 

 year, though it is hazardous to attempt to generalise in such 

 a matter, as exact local knowledge is alone of any value. 



It must be remembered in this connection that, in Lower 

 Bengal, tanks are largely used as sources of drinking water, 

 and such tanks are more or less guarded from pollution, for 

 callous as the Indian may be in this matter, there are few 

 who would drink the water of a town tank in Northern 

 India ; and any tank containing water that would be 

 regarded as drinkable, even from a native point of view, 

 would certainly form a congenial habitat for Anopheles 

 larvae, and the improvement of municipal sanitation against 

 malaria will be in such places proportionally difficult. 



Where not indispensable as sources of drinking-water, 

 such tanks might doubtless be dealt with by the use of 

 larvicides ; but in such places these tanks are both large 

 and numerous, so that the expense would be a large and 

 constant one, and we are further met with a difficulty that 

 must be fatal to the success of all temporary, and therefore 

 continuous measures in India — the difficulty of providing 

 adequate intelligent supervision. 



Another reason why not only cities but also smaller long- 

 inhabited sites tend to become less malarious is that the 

 ground level is being slowly but continuously raised by the 

 accumulation of the ruins of older buildings on which, from 

 time to time, new buildings are raised. Often, in India, 

 village sites are of an unknown antiquity, and in such the 

 tortuous village streets wind their way always up hill to its 

 centre, where often there still stands the more imposing 

 home of the headman. The older the hamlet, the higher 

 the hill, and some have lasted so long that the site of the hut 

 from which it grew may now be 50 feet or more above the 

 unbroken level of the surrounding plain. Now it is obvious 



