_Definition._ Inflammation of the spongy tissue of the lungs
uncomplicated by that of the bronchia or pleura.
_Divisions._ This affection has been variously divided according to
_seat_, _nature_, and _complications_: thus:
_Single Pneumonia_: Affecting one lung: _right_ or _left_.
_Double Pneumonia_: Affecting both lungs.
_Lobar Pneumonia_: Affecting one lobe or by lobes.
_Lobular Pneumonia_: Affecting by lobules.
_Acute Pneumonia_: _Subacute Pneumonia._ _Chronic Pneumonia._
_Croupous or Fibrinous_: With fibrinous exudate.
_Catarrhal_: With exudate rich in cells and granules.
_Hæmorrhagic_: With extravasation of blood.
_Purulent_: Tending to pus: abscess.
_Necrotic_: Tending to gangrene: sequestra.
_Desquamative_: With great proliferation of alveolar epithelium.
_Interstitial_. _Interlobular_: Affecting mainly the interlobular
connective tissue.
_Hypostatic_: Dependent on gravitation of the blood.
_Metastatic_: Due to embolism.
_Parasitic_: Caused by parasites. Due to wounds or foreign bodies.
_Contagious_ and _Traumatic Pneumonia_.
Many of these are, however, but localizations of the same affection and
others are manifestly microbian diseases which in the present state of
pathology it is not always easy to early distinguish sufficiently for
clinical and therapeutic purposes. For the sake of convenience therefore
pneumonia will here be treated of generally, and under the headings
devoted to etiology, pathology, therapeutics, etc., attention will be
given to distinctions. Those pneumonias that are but pulmonary
manifestations of other diseases—influenza, glanders, tuberculosis,
strangles, contagious pneumo-enteritis, lung plague, septicæmia, pyæmia,
swine plague, hog cholera, petechial fever, actinomycosis, and neoplasms
will be considered under these respective headings.