354 PA THOGENIC BA CTERIA.
cumscribed growth occurs. The growth upon blood-
serum is the same.
Upon potato the growth is abundant, quickly covering
the entire surface with a thick yellowish-white layer,
which sometimes contains bubbles of gas. Gas is also
sometimes developed in gelatin cultures.
A most superficial comparison will suffice to show the
great difference in vegetation between these two so-called
Friedlander had considerable difficulty in causing any
pathogenic changes by the injection of his bacillus into
animals. Rabbits and guinea-pigs were immune, and
the only actual pathogenic results which Friedlander ob-
tained were in mice, into whose lungs and pleura he
injected the cultures. The remarks of Frankel upon
such mouse-operations, which do not add much weight
to experiments, have already been quoted.
In the status prtzsens of bacteriologic knowledge the
tbacillus of Friedlander is regarded as an organism of very
feeble pathogenic powers, generally a harmless sapro-
phyte, but which may at times aid in producing inflam-
matory changes when, in the tissues of the human body.
2. Catarrhal Pneumonia.—This form of pulmonary
inflammation occurs in local areas, generally situated
about the distribution of a bronchiole. It cannot be
said to have a specific micro-organism, as almost any
irritant foreign materials accidentally inhaled can cause
it. The majority of the cases, however—and especially
those which are distinctly peribronchial—are caused by
the presence of the staphylococcus and streptococcus of
suppuration. Friedlander's bacillus may also aid in pro-
ducing local inflammations.
3. Tubercular Pneumonia.—At times the process of
pulmonary tuberctilosis is so rapid, and associated with
the production of so much semi-liquid, semi-necrotic
material, that the auto-infection of the lung is greatly
favored; the tubercle-bacilli are distributed to the entire
lung or to large parts of it, and a distinct inflammation