THE NEW METHODS 135 



declared itself in the surrounding Republics, and that 

 dredging has been carried on over and over again 

 without any epidemic occurring. I lay stress on this 

 clinging to past beliefs because I am convinced that 

 a great deal of harm is done even at the present time, 

 and that the necessity for active preventive measures is 

 unfortunately not fully realised. 



Without a clear and precise knowledge of the 

 method of transmission it is impossible for any authority 

 to effectively prevent or check a disease like yellow 

 fever, in wliicli scientific precision, thoroughness, and 

 immediate action are essential. 



Difficulties of Combating the Disease in the Past 



It can be readily understood from the preceding 

 remarks how hopeless and ineffective were the measures 

 of prevention used in the past, and that, too, in spite 

 of the fact that in the more recent periods Listerian 

 principles of disinfection were applied, carbolic acid 

 and perchloride of mercury being freely used as dis- 

 infectants. For instance, although INIajor Gorgas had, 

 previous to the advent of Reed, Carroll, Agramonte, 

 and Lazear, made a vast change in the sanitary con- 

 dition of Havana, yellow fever was, nevertheless, not 

 affected ; it only ceased after employing methods directed 

 against the mosquito, viz. fumigation, screening, and 

 destroying the breeding places of the larvce. In Belize, 

 during the recent (1905) epidemic, cases of yellow 

 fever occurred amongst the best-cared-for class of 

 people living in the best residential houses, where 

 the sanitary arrangements were excellent 



