CHAPTER VIII. 



INFLAMMATORY AND SUPPURATIVE CONDITIONS, 

 CONTINUED: THE ACUTE PNEUMONIAS, EPI- 

 DEMIC CEREBRO-SPINAL MENINGITIS. 



Introductory. The term Pneumonia is applied to several con- 

 ditions which present differences in pathological anatomy and in 

 origin. All of these, however, must be looked on as varieties of 

 inflammation in which the process is modified in different ways, 

 depending on the special structure of the lung or of the parts 

 which compose it. There is, first of all, and, in adults, the com- 

 monest type, the acute croupous or lobar pneumonia, in which 

 an inflammatory process attended by abundant fibrinous exuda- 

 tion affects, by continuity, the entire tissue of a lobe or of a 

 large portion of the lung. It departs from the course of an 

 ordinary inflammation in that the reaction of the connective 

 tissue of the lung is relatively slight, and there is usually no 

 tendency for organisation of the inflammatory exudation to 

 take place. Secondly, there is the acute catarrhal or lobular 

 pneumonia, where a catarrhal inflammatory process spreads from 

 the capillary bronchi to the air vesicles, and in these a change, 

 consisting largely of proliferation of the endothelium of the 

 alveoli, takes place which leads to consolidation 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, however, influenza in an 

 epidemic form has become frequent, catarrhal pneumonia has 

 been of much more common occurrence in adults, has assumed 

 a very fatal tendency, and has presented the formerly quite 

 unusual feature of being sometimes the precursor of gangrene 

 of the lung. Besides these two definite types other forms also 

 exist. Thus instead of a fibrinous material the exudation may 

 be of a serous, hsemorrhagic, or purulent character. Cases of 

 mixed fibrinous and catarrhal pneumonia also occur, and 



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