574 BACTERIOLOGY. 
simple peptone solution, and it has been shown by ex- 
periment that it also multiplies to some extent in steril- 
ized river or well-water, and preserves its vitality in 
such water for several weeks or even months. Koch 
found in his early investigations that rapid multiplica- 
tion may occur upon the surface of moist linen, and also 
demonstrated the presence of this spirillum in the foul’ 
water of a tank in India which was used PEL the natives 
for drinking purposes. 
The comma bacillus belongs to the clase-ot aérobie 
organisms, inasmuch as it grows readily only in the pres- 
ence of oxygen, and that it develops active motility 
only when a certain amount of oxygen is present. It 
does not grow in the total absence of oxygen, but a 
small quantity of oxygen is all that is required for its 
development, as in the intestines. : 
Temperature is also of considerable importance in the 
growth of cultures. Active growth does not begin - 
until a temperature of 22° to 25° C. is reached, though 
the optimum growth is between 30° and 40° C. 
The vitality of cultures of. the comma bacillus is 
quickly destroyed by desiccation. If a culture be 
spread on a cover-glass and exposed to the action of 
the air at room-temperature the bacilli are dead at the 
end of two or three hours, unless the layer of culture 
is very thick, when it may take twenty-four hours or 
more to kill all the bacilli. This fact indicates that 
infection is not produced by means of dust or other dried 
objects contaminated with cholera bacilli. The trans- 
misson of these organisms through the air, therefore, 
can only take place for short distances, as by a spray of 
infectious liquids by mechanical means—as, for instance, 
