850 
REMARKS ON MICRO-ORGANISMS. 
putrid fluid under the mouse’s skin, Koch found, besides 
septicaemia, a local affection of the seat of inoculation, in the 
form of spreading gangrene; and, on investigating the part, 
he discovered in it, exactly corresponding with the extent of 
the local affection, another organism very differently formed 
from that of the septicaemia—viz. a micrococcus, consisting 
Magnified 700 Diameters. 
fO 
Bacillus Anthracis 
after Koch . 
Bacillus Septicce?nicd, 
House Mouse — Koch. 
C 
IT O ?™* 
V) 
& 
Chain Micrococcus y 
Gangrene in the Mouse. 
Koch. 
Bacterium of Foicl Cholera. 
Camera lucida sketch. 
of minute spherical granules arranged in linear series, like 
strings of exquisitely minute beads, as represented at c in the 
woodcut. Believing that this locally developing organism 
must be the cause of the gangrene, he tried to separate it 
from the bacillus of the septicaemia, and succeeded through 
an accidental observation of*great interest. Having till that 
time employed the house-mouse in his experiments, he hap¬ 
pened to try the inoculation of a field-mouse. This animal, 
though so closely allied, proved not susceptible of the septi¬ 
caemia. The bacillus of that disease was unable to grow in 
the blood of the field-mouse, but the micrococcus of the gan¬ 
grene could develop among its tissues. The new organism 
