114 MICRO-ORGANISMS AND DISEASE. [CHAP. 



affects greater and greater numbers, and when the fluid is 

 exhausted for the formation of new bacilli, it necessarily 

 follows that the whole growth gradually becomes involved in 

 the process of degeneration, the whole mass becoming smaller, 

 and finally only debris is left. Such cultures, namely, those 

 in which the degeneration involves the whole mass of the 

 bacilli, are quite innocuous when inoculated into animals, or 

 into fresh nourishing media. But as long as there are any 

 good protoplasmic elements of the bacilli left, the culture is 

 virulent to rodents, with the exception of mice, as will be 

 stated presently ; and it is capable, when transferred to new 

 suitable nourishing media, of starting new cultures that prove 

 virulent to all rodents and sheep. 



The same holds good of the bacilli in the blood and organs 

 of an animal dead of anthrax, provided the animal be not 

 opened, and its organs, exudations, or urine be not exposed to 

 the free air ; for the bacilli not exposed to the air gradually 

 degenerate, and the blood and organs of such an animal, 

 although at first deadly poison to other susceptible animals, 

 become at length quite innocuous. Systematic observation has 

 shown me that small animals, such as mice and guinea-pigs, 

 when kept unopened or buried in earth, become quite innocu- 

 ous after five to eight days, the anthrax-bacilli having by this 

 dme, by degeneration, altogether disappeared from the blood, 

 spleen, and other organs. Pasteur's statement that in animals 

 dead of anthrax and buried, the bacilli form spores, that these 

 spores are taken up by earthworms and carried to the surface 

 of the soil, where they are deposited with their castings and 

 thus are capable of infecting animals grazing or sojourning on 

 this soil, is not borne out by the above observations. And 

 further, Koch has proved J by direct experiment that spores of 

 anthrax-bacilli, when mixed with earth in which worms are 

 present, are not taken up by these creatures. 



Drying bacilli of the blood or of a culture in a thin layer 

 invariably kills them, but the spores remain unaffected. 



The bacilli of the blood of a rodent dead of anthrax are 

 always thinner than the bacilli cultivated in a neutral fluid 

 medium like pork-broth. 



Cultivation of the blood-bacilli at temperatures varying 

 between 20 and 40 C. in any suitable nourishing material, 

 solid or fluid, however many transferences (new cultivations, 

 or so-called new generations) be made, always yields a crop of 

 virulent bacilli. It is absolutely incorrect to say, as Buclmer^ 



1 Mittheil. a. d. k. Gesudhei/samte, 1881. 



2 Uebtr d. Erzeug. des MiUbrandes, Munich, 1S0. 



