72 
BACTERIOLOGY. 
morphology and manner of growth. The members of 
this group differ but little from those of the colon 
group. 
The Bacillus Mucosus Capsulatus. 
This bacillus was discovered by Friedlander in 
1883, and is often called the Friedlander bacillus. It 
is a short, plump bacillus, with rounded ends, exhibit¬ 
ing considerable variation in size. It may occur 
singly, in pairs, or in chains. It is not motile and 
forms no spores. On all the ordinary culture media it 
grows readily even at room temperature. The most 
characteristic feature is the transparent capsule about 
the organism. Exposure to heat of 6o° C. destroys 
the bacillus in a short time. 
At the time of its discovery this bacillus was be¬ 
lieved to be the chief cause of lobar pneumonia, but 
it has since been proved that it is responsible for only 
a small percentage of the cases. In addition to caus¬ 
ing pneumonia, it has been found in suppurations of 
the nasal sinuses, empyema, pericarditis, and menin¬ 
gitis. No method of immunization has been found as 
yet. 
The Bacillus Lactis Aerogenes. 
The Bacillus lactis aerogenes is constantly present 
in milk and, with other micro-organisms, is the cause 
of souring. It is also present in water, sewage, and 
feces. It closely resembles the colon bacillus, but 
differs from it chiefly in being non-motile and having 
