RELATION OF PATHOGENIC TO SEPTIC BACTERIA. 63 



a cultivation, which, owing to having been kept for a certain 

 length of time, produced no fatal effect, are " vaccinated'' and 

 protected from anthrax in a virulent form. 



As regards my mice, guinea-pigs, and rabbits, I have not 

 found anything of the sort. Either the inoculation with my 

 cultivations is fatal or it is not; in the latter case it has no 

 effect whatever, and does not at all protect against active 

 virus ; in the former case it is always fatal. The inactivity on 

 mice of a cultivation may be due to the absence of spores, or 

 to the age of a cultivation — Pasteur's statement of a diminu- 

 tion in virulence in two days and four days, does not quite 

 cover my facts — or the bacillus mass in a cultivation, not 

 being able to form spores and gradually degenerating and 

 dwindling away and becoming macerated into a granular 

 debris, loses after a time altogether its power to infect mice, 

 guinea-pigs, or rabbits, or to start new cultivations.' 



These latter conditions come out especially strikingly in 



1 As regards the slight effect (constitutional disturbance and rise of tem- 

 perature) produced in cattle after inoculation with anthrax blood of rodents 

 (Sanderson andDuguid),or with artificially cultivated Bacillus anthracis(?) 

 of a rodent (Greenfield), as well as the non-fatal effect produced on sheep by 

 Pasteur with his vaccine, we have to deal with peculiar conditions, not solely 

 due to a diminution of virulence of the bacillus, but chiefly to some pecu- 

 liarity (breed appears to be one of such peculiarities) of the animal inocu- 

 lated. These cases are comparable in a certain sense to those mild cases of 

 other infectious maladies, which not occurring more than once during the 

 lifetime of an individual, would naturally confer immunity on this individual 

 against a second attack. Thus, a person once having had a mild attack of 

 scarlatina, measles, &c., very likely remains free from a second attack. In 

 cases of scarlatina the differences in the severity of the attacks are due to 

 differences of the source of the virus [i. e. differences of the nature of the 

 virus], as well as to differences of the individuals attacked, — cases of varying 

 severity being derived from the same source, i. e. the same virus. The same is 

 also noticed in the cases of anthrax produced by the Bacillus authracis; 

 the bacillus of some cultivations is altogether ineffectual on mice, deadlv on 

 guinea-pigs and rabbits, while it appears to produce, according to Pasteur 

 only a slight effect on sheep. Now, no one could say this difference is due 

 entirely to a change of the bacillus, since it is equally due to the difference 

 of the individual. Again, the non-fatal result with the blood bacillus of a 

 guinea-pig, dead of anthrax, produced in a cow contrasts strongly with the 



