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 ina 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 Wolffhigel 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 uf 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). 
