CHAPTER V.
PNEUMONIA.

THE term "pneumonia," while generally understood
to refer to the lobar disease particularly designated as
croupous pneumonia, is a vague one, really comprehend-
ing a variety of inflammatory conditions of the lung
quite dissimilar in character. This being true, no one
should be surprised to find that a single organism cannot
be described as ''specific" for all. Indeed, pneumonia
must be considered as a group of diseases, and the various
microbes found associated with it must be described suc-
cessively in connection with the peculiar phase of the
disease in which they occur.

i. Lobar or Croupous Pneumonia.—The bacterium,
which can be demonstrated in at least 75 per cent of the
cases of lobar pneumonia, which is now almost uni-
versally accepted as the cause of the disease, and about
whose specificity very few doubts can be raised, is the
pneumococcus of Prankel and Weichselbaum.

Priority of discovery in the case of the pneumococcus
seems to be in favor of Sternberg, who as early as 1880 de-
scribed an identical organism which he secured from his
saliva. Curiously enough, Pasteur seems to have cap-
tured the same organism, also from saliva, in the same
year. The researches of the observers whose names are
attached to the organism were not completed until five
years later. It is to Frankel, Telamon, and particularly
to Weichselbaum, however, that we are indebted for the
discovery of the relation which the organism bears to
pneumonia.

The organism (Fig. 98) is variable in its morphology.
When grown in bouillon it is oval, has a pronounced dis-

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