THE BACILLUS OF ANTHRAX. 423 
anthrax in susceptible animals as certainly as does the blood of an 
animal recently dead from the disease. 
Owing to the fact that this was the first pathogenic bacillus cul- 
tivated in artificial media, and to the facility with which it grows ix 
various media, it has served more than any other microérganism for 
researches relating to a variety of questions in pathology, general 
biology, and public hygiene, some of which are discussed in other 
sections of this volume. 
BACILLUS ANTHRACIS. 
Synonyms.—Milzbrandbacillus, Ger. ; Bactéridie du charbon, F'r. 
First observed in the blood of infected animals by Pollender (1849) 
and by Davaine (1850). Etiological relation affirmed by Davaine 
tit 
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——— AN 
pcan 
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wf % Ba . 
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oN sre us 
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rae . OWE 
“sr” S/h ou 
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om “ Mao 
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Fig. 98.—Bacillus anthracis, from a culture, showing development of long threads in convo- 
luted bundles. x 300. (Klein.) 
(1863), and established by the inoculation of pure cultures by Pasteur 
(1879) and by many other investigators. 
‘Morphology.—Rod-shaped bacteria having a breadth of 1 to 
1.25 p, and 5 to 20 » in length; or, in suitable culture media, growing 
out into long, flexible filaments, which are frequently united in 
twisted, cord-like bundles. These filaments in hanging-drop cul- 
tures, before the development of spores, appear to be homogeneous ; 
or the protoplasm is clouded and granular, but without distinct seg- 
mentation. But in stained preparations the filaments are seen to be 
made up of a series of rectangular, deeply stained segments. In 
hanging-drop cultures the ends of the rods appear ruunded, but in 
stained preparations from the blood of an infected animal they are 
seen to present a slight concavity, and a lenticular interspace is 
formed where two rods come together. The diameter of the rods 
