TESTS OF DISINFECTION 35 



Having pointed out the fact that negative evidence, 

 in a restricted field of observation, must be accepted 

 with great caution in estimating the value of disin- 

 fectants, we hasten to say that the combined experi- 

 ence of sanitarians, derived from practical efforts to 

 restrict the extension of infectious diseases, is of the 

 greatest value, and that this experience is, to a great 

 extent, in accord with the results of exact experi- 

 ments made in the laboratory. 



(6) Inoculation experiments upon susceptible ani- 

 mals, made directly with infectious material which 

 has been subjected to the action of a disinfectant, 

 have been made by numerous observers. The proof 

 of disinfection in this case is failure to produce the 

 characteristic symptoms which result from inoculation 

 with similar material not disinfected. Thus, Davaine 

 found that the blood of an animal just dead from the 

 disease known by English writers as anthrax or 

 splenic fever, inoculated into a healthy rabbit or 

 guinea-pig, in the smallest quantity, infallibly pro- 

 duces death within two or three days ; and the blood 

 of these animals will again infect and cause the death 

 of others, and so on indefinitely. This anthrax blood 

 therefore is infectious material, which can be utilised 

 for experiments relating to the comparative value of 

 disinfectants. Davaine made many such experiments, 

 not only with the blood of anthrax, but also with that 



