TESTS OF DISINFECTION 37 



cle. The inference seems justified that any agent 

 which will neutralise the specific infecting power of 

 this material will also neutralise the smallpox virus. 

 In these experiments the more careful investigators 

 have taken the precaution of vaccinating the same 

 person with disinfected and non-disinfected virus from 

 the same source. A successful vaccination with the 

 non-disinfected virus shows that the individual is 

 susceptible and the material good ; failure to produce 

 any result is evidence that the potency of the disin- 

 fected virus has been destroyed by the chemical 

 agent to which it was exposed. 



(c) As already stated, it has been demonstrated 

 that the infectious diseases of the lower animals, 

 which have furnished the material for experiments 

 upon disinfectants by the method of inoculation, are 

 "germ diseases," and that the infectious agent is in 

 each case a living micro-organism, belonging to the 

 class known under the general name of Bacteria. 

 The bacteria are vegetable organisms, which, by 

 reason of their minute size and simple organisation 

 must be placed at the very foot of the scale of living 

 things ; but they make up in number and in rapidity 

 of development for their minute size. 



Many of these disease germs are now known to 

 us, not only by microscopic examination of the blood 

 and tissues of infected animals, but also by " culture 



