THE BACILLUS OF ANTHRAX. 425 
temperature of 20° to 38°C. Development ceases at temperatures 
below 12° C. or above 45° C. 
This bacillus grows best in neutral or slightly alkaline media, and 
its development is arrested by a decidedly acid reaction of the cul- 
ture medium. It may be cultivated in infusions of flesh or of vari- 
ous vegetables, in diluted urine, in milk, etc. 
In gelatin plate cultures small, white, opaque colonies are devel- 
oped in from twenty-four to thirty-six hours, which under the micro- 
scope are seen to be somewhat irregular in outline and of a greenish 
tint ; later the colonies spread out upon the surface of the gelatin, 
and the darker central portion is surrounded by a brownish mass of 
wavy filaments, which are associated in tangled bundles. Mycelial- 
like outgrowths from the periphery of 
the colony may often be seen extending 
into the surrounding gelatin. At the 
end of two or three days liquefaction of 
the gelatin commences, and the colony 
is soon surrounded by the liquefied me- 
dium, upon the surface of which it floats 
as an irregular white pellicle. In gela- 
tin stab cultures growth occurs all 
along the line of puncture as a white cen- 
tral thread, from which lateral thread- 
like ramifications extend into the culture 
medium. At the end of two or three 
days liquefaction of the culture medium 
commences near the surface, where the 
development has been most abundant. 
At first a pasty, white mass is formed, 
but as liquefaction progresses the upper 
part of the liquefied gelatin becomes 
transparent from the subsidence of the ig 109 culture of Bacillus an- 
motionless bacilli, and these are seen thracis in nutrient gelatin: a, end 
upon the surface of the non-liquefied 0] [our Qaysi, > end of eight days. 
portion of the medium in the form of 
cloudy, white masses, while below the line of liquefaction the charac- 
teristic branching growth may still be seen along the line of puncture. 
In agar plate cultures, in the incubating oven at 35° to 37° C., 
colonies are developed within twenty-four hours, which under the. 
microscope are seen to be made up of interlaced filaments and are 
very characteristic and beautiful. Upon the surface of nutrient agar 
a grayish-white layer is formed, which may be removed in ribbon-like 
strips ; and in stick cultures in this medium a branching growth is 
seen, like that in gelatin, but without liquefaction. The addition of 
