36 INFECTION AND IMMUNITY 



of a fatal form of septicaemia in rabbits, which is 

 known by his name. Other investigators have fol- 

 lowed up these experiments upon infectious material 

 of the same kind, and also upon material from other 

 sources the infectious material of glanders, of tuber- 

 culosis, of symptomatic anthrax, of fowl cholera, of 

 swine plague, etc. 



It has been proved that the infectious agent in all 

 of the diseases mentioned is a living germ, and that 

 disinfection consists in destroying the vitality of this 

 germ. But in experiments made with blood or other 

 material obtained directly from diseased animals, the 

 results would be just as definite and satisfactory if 

 we were still ignorant as to the exact nature of the 

 infecting agent. The test shows the destruction of 

 infecting power without any reference to the cause 

 of the special virulence, which is demonstrated to be 

 neutralised by certain chemical agents in a given 

 amount. All of the experiments made with the 

 above-mentioned kinds of virus have been made 

 upon the lower animals ; but there is one kind of 

 material which it is justifiable to use upon man 

 himself, and with which numerous experiments of a 

 very satisfactory character have been made. This 

 material is vaccine virus. Fresh vaccine, when inocu- 

 lated into the arm of an unvaccinated person, gives 

 rise to a very characteristic result the vaccine vesi- 



