48 DR. E. KLEIN. 



having become diminished by cultivation in the former and 

 not in the latter. These statements may be, and probably are, 

 best explained after Koch, by the assumption that the original 

 cultivation had become contaminated by another bacillus, the 

 Bacillus anthracis remaining in the minority is gradually 

 overgrown after a certain period or after a certain number of 

 cultivations by the contamination of bacillus, and hence larger 

 quantities of the fluid are to be used to get hold of one or the 

 other stray Bacillus anthracis left therein, and after some 

 more transfers the original number of Bacillus anthracis 

 had become so much diminished that perhaps even a larger 

 quantity contains no other than the contamination bacillus. In 

 my cultivations I never noticed such a condition, i. e. I never 

 found reason for supposing the anthrax bacillus to undergo 

 change in its virulence, otherwise than as there might be ques- 

 tion of spore formation on the one hand, or of degeneration 

 (that rendered the bacillus completely inert) on the other hand. 

 I have, indeed, on occasion found an exceptionally large quantity 

 of inoculating material to be required ; but this circumstance 

 has always appeared to me perfectly well explained through 

 the small number of really active bacilli existing in the par- 

 ticular material. This has taken place, e. g. in cultures of pure 

 Bacillus anthracis without spores, that had been kept for 

 some weeks (see below), and where there had been a gradual 

 diminution of the number of active anthrax bacilli. 



A point of importance which I wish to mention here refers to 

 the time of death of rodents after inoculation with anthrax. As 

 a rule they die within forty-eight hours from the time of inocu- 

 lation ; some within twenty hours, others in thirty or thirty-six 

 hours, and a few others between this and forty-eight hours. 

 Few animals survive the third day, although I have seen mice 

 and guinea-pigs die after five days of typical anthrax. A given 

 cultivation used after the same method and in the same quan- 

 tity for the inoculation of several mice will kill some of them 

 more rapidly than it will kill others, and the same is true if 

 guinea-pigs are the animals under experiment. I have seen 

 animals (mice and guinea-pigs) die within twenty hours after 



