VACCINES IN PROPHYLAXIS OF DISEASE 175 



find more general application to the diseases of 

 man. But unfortunately it has not been possi- 

 ble to materially extend the application of this 

 principle, and all important advances have since 

 been made with other means of active immuniz- 

 ation. 



It was shown by Salmon and Smith in 1886 

 and by Chamberland and Roux that it was not 

 necessary to introduce living microorganisms in 

 order to produce immunity; and further, that 

 the same result could be obtained by injecting 

 bacteria killed by heat. Vaccination by the use 

 of cultures killed by heat or antiseptics was in- 

 troduced by Kolle in 1896. In the same year, 

 Wright introduced the use of killed cultures for 

 immunization against typhoid fever, and this 

 method of prophylactic immunization has also 

 been successfully applied to cholera, plague, 

 meningitis, and whooping-cough. 



SMALLPOX 



Historic Smallpox has been known since 

 very early times, particularly in China; and, 

 while there is every reason to believe that it 

 was present in the various countries, the older 

 writers do not give very clear descriptions of 

 it. Smallpox is supposed to have originated in 



