THE BACILLUS OF ANTHRAX. 427 



produced an " attenuated virus" by keeping his cultures for a con- 

 siderable time before replanting them upon fresh soil, and supposed 

 the effect was due to the action of atmospheric oxygen. It seems 

 probable that it was rather due to the deleterious action of its own 

 products of growth present in the culture media. It has been 

 shown by Chamberlain and Roux that cultivation in the presence 

 of certain chemical substances added to the culture medium e.g., 

 bichromate of potassium 0.01 per cent causes an attenuation of 

 virulence. The same result occurs when cultures are subjected to a 

 temperature a little below that which is fatal to the bacillus 50 C. 

 for eighteen minutes (Chauveau); 42.5 C. for two or three weeks 

 (Koch). Attenuation of pathogenic virulence is also effected by cul- 

 tivation in the body of a non-susceptible animal, like the frog (Lu- 

 barsch, Petruschky); or in the blood of a rat (Behring); by exposure 

 to sunlight (Arloing); and by compressed air (Chauveau). 



Anthrax spores may be preserved in a desiccated condition for 

 years without losing their vitality or pathogenic virulence when in- 

 oculated into susceptible animals. They also resist a comparatively 

 high temperature. Thus Koch and Wolffhiigel found that dry spores 

 exposed in dry air required a temperature of 140 C. , maintained for 

 three hours, to insure their destruction. But spores suspended in a 

 liquid are destroyed in four minutes by the boiling temperature, 

 100 C. (writer's determination). 



The bacilli, in the absence of spores, according to Chauveau, are 

 destroyed in ten minutes by a temperature of 54 C. 



For the action of various antiseptic and germicidal agents upon 

 this bacillus we must refer to the sections especially devoted to this 

 subject (Part Second). 



Toussaint, by injecting filtered anthrax blood into animals, obtained 

 evidence that it contained some toxic substance which in his experi- 

 ments gave rise to local inflammation without any noticeable general 

 symptoms. More recent investigations show that a poisonous sub- 

 stance is formed during the growth of the anthrax bacillus, and that 

 cultures containing this toxin, from which the bacilli have been re- 

 moved by filtration through porcelain, produce immunity when in- 

 jected into susceptible animals, similar to that resulting from inocu- 

 lations with an attenuated virus. It is probable that the pathogenic 

 power of the anthrax bacillus depends largely upon the presence of 

 this toxin, and that the essential difference between virulent and 

 attenuated varieties depends upon the more abundant production of 

 this toxic substance by the former. It has also been shown that 

 virulent cultures produce a larger quantity of acid than those which 

 have been attenuated by any of the agencies above mentioned 

 (Behring). 



