CONDITIONS INFLUENCING PREVALENCE 207 



Let it be at once admitted that the extermination of 

 Mosquitoes may be impracticable ; but it does not follow 

 that we should fold our hands and make no effort to pre- 

 vent their fullest multiplication. Every Anopheles puddle 

 filled up means one focus the less of infectible material, and 

 the mere fact that without any specially directed sanitary 

 efforts the city of Rome is malaria free, though standing in 

 the midst of most deadly surroundings, shows how much 

 may be effected. 



There are millions of unvaccinated persons in India, and 

 everyone of them is a possible focus of variolous infection, 

 but no one can doubt that vaccination has effected an enor- 

 mous diminution of small-pox in the country, though the 

 impossibility of securing universal vaccination might have 

 served equally well as an argument for attempting nothing 

 in the matter. In the wide expanse of the country in 

 general such detailed measures are certainly impractic- 

 able, but in limited areas, such as those of municipalities, 

 much might undoubtedly be done by the intelligent applica- 

 tion of our present knowledge, albeit of a " hand-to-mouth " 

 character, and that at but a trifling cost. Much also might 

 be done by the enforcement by municipalities of bye-laws 

 prohibiting the indiscriminate honeycombing of the surface 

 for earth for building and plastering purposes. Such a 

 regulation need not give rise to any real inconvenience, 

 as tanks and other excavations of a size unlikely to serve 

 as nurseries for larvae are so numerous in most such 

 municipal areas that it would cause no hardship to insist 

 on the earth required for such purposes being taken from 

 their banks. The systematic filling up of small depressions 

 with any hard rubbish that may be available is another 

 measure that obviously suggests itself, and as the most 

 dangerous collections are generally quite small and shallow, 

 need not be beyond the pecuniary resources of even small 

 places. 



In the North-west Provinces and Punjab I have rarely 

 met with any large collection of water or " tank" within 

 the limits of a native town which contained Anopheles 

 larvae. Most of them, indeed, are too foul for even the least. 



