CHAPTER VIII. 



ACUTE PNEUMONIA. 



Introductory. Pneumonia, as a clinical term, is applied to 

 several conditions which present differences in pathological 

 anatomy and in origin. There is, first of all, the acute 

 croupous or lobar pneumonia, in which an inflammatory 

 process attended by abundant fibrinous exudation affects, 

 by continuity, the entire tissue of a lobe or of a large 

 portion of the lung. This type is, both in its clinical 

 symptoms and pathological effects, familiar. Secondly, 

 there is the acute catarrhal or lobular pneumonia, where 

 the inflammatory process spreads from the capillary 

 bronchi to the air vesicles, and leads to a catarrhal con- 

 solidation of patches of the lung tissue. Up till 1889 

 acute catarrhal pneumonia was comparatively rare except 

 in children. In adults it was chiefly found as a secondary 

 complication to some condition such as diphtheria, typhoid 

 fever, etc. Since the first recent great epidemic of in- 

 fluenza in the year named, however, it has been of much 

 more frequent occurrence in adults, has assumed a very 

 fatal tendency, and has presented the formerly quite un- 

 usual feature of being sometimes the precursor of gangrene 

 of the lung. Moreover, not only has the prevalent type of 

 pneumonia (the term being used in its widest sense) changed 

 through the occurrence of a greater proportion of catarrhal 

 cases, but it appears to be now more common to find 

 cases which microscopically present a mixed type, i.e., in 



