57 



infected persons, the percentage of infected mosquitoes 

 among the insects which remain, will also be reduced in 

 its turn, because the insects will now find fewer infected 

 persons to bite. Hence, ultimately, the number of in- 

 fected persons in the locality will be reduced by much 

 more than one-half. In fact, we may perhaps assume that 

 the number of infected persons will be reduced to one- 

 quarter that is, in the duplicate ratio of the percentage of 

 reduction of the mosquitoes. Similarly, if we can reduce 

 the mosquitoes to one-tenth, we may hope to reduce the 

 mosquito-borne disease to the one-hundredth part of its 

 former prevalence. / think that this degree of reduction 

 will always be possible. 



25. Sanitary Anarchy. In conclusion, it will be asked, 

 why is it that such measures as draining and cleaning up 

 towns must ever be commenced by private enterprise ; 

 surely the matter is one which lies in the province of the 

 public authorities who ought to attend to it at once, 

 especially in view of recent discoveries regarding mosquitoes. 

 The Imperial Government of Britain possesses an enormous 

 medical and sanitary machinery, the branches of which 

 extend into even very small towns in our tropical depen- 

 dencies a machinery which costs the country a heavy sum 

 of money ; why can it not be set in motion by a word from 

 headquarters ; why cannot the host of medical and health 

 officers, of sanitary engineers and inspectors, all paid out 

 of public moneys, be directed to commence the obviously 

 necessary improvements indicated above ? 



In Cuba, no sooner was the mosquito proved to be the 

 disseminating agent of yellow fever than, without delay or 



